semiconductor materials needed to manufacture display screens for sale

Today, semiconductor and LCD panel manufacturing equipment is essential for the production of all kinds of electric and electronic appliances, including PCs, cell phones and flat-panel televisions. Advances in this equipment promote enhancements to PC performance and cell phone functions, and enrich people"s lives by reducing the cost of flat panel TV sets. THK"s products can meet this kind of high-technology need for fine movement control.

Compact ball screws and Caged Ball LM Guides exhibiting very smooth movement are used in highly efficient production systems used for LCD panels for car navigation systems and mobile tools.

To transfer large crystal glass substrates over long distances quickly, high speed, superb accuracy and the ability to track even when long strokes are necessary. A combination of LM Guides and linear motor driving systems can deliver this.

In order to test the electrical characteristics of LCD panel substrates, the measuring instrument must be capable of positioning the substrates accurately over a wide area. LM Guides and ball screws, machined to a high level of accuracy, can provide this tracking control and contribute to efficient manufacturing even as the size of the substrates increases.

Dicing saws cut and separate each IC chip from its larger wafer. Laser cutting devices and very thin radial blades at the end of high-speed rotating spindles are used to accurately cut out the IC chips. LM Guides and Ball Screws are used in the guidance and driving sections, which must always operate with a high level of accuracy and stability. THK’s ultra precision technologies excel in this technology.

The LM Guide (Linear Motion Guide) is our main product, incorporating a part with a linear rolling motion into practical usage for the first time in the world.

The technology that me and my colleagues have chosen to examine as a possible semiconductor recycling project is the LCD PC monitor. We have chosen Dell

The process of which the hydrogenated amorphous silicon is deposited onto a substrate is called plasma-enhanced chemical vapor deposition (PECVD). This process uses silane gas which enters the chemical vapor deposition chamber and dissociates into a cloud of plasma. This plasma is induced by a radio frequency power generator; the chamber that holds this process must be in a vacuum to eliminate any impurities in the process. Similiar to an electron beam deposition process,the silicon and hydrogen atoms condense on a substrate, in LCD monitors this would be the glass, and make the thin layer of hydrogenated amorphous silicon. The setup of this process is shown in Figure 2.

The production of PC LCD monitors on the worldwide market shows Dell, Samsung, and LGE at the top of the market selling most for the 12 Brands selling from as low as 10 million units in a month to nearly 15 million units a month for 2010. Dell was ranked number one in the production of LCD for 2010. We were capable of determining the amount of units sold by Dell, which is estimated at 22.5 million units in 2010.

The growth for the production of LCD screens is expected to slowdown in the next two years. The growth in production of LCD panels for LCD has decreased, by the slow economic recovery, which is causing consumers to buy less and is predicted to slow down further for the next few years.

Recycling LCD monitors is easy if you do not have to go through the process yourself. There are multiple companies that allow you to send in your monitors for free, for a price or you can even drop them off at specific locations and they will handle it all for you. Some of these companies include Apple, Staples and Dell. Michigan Technological University allows people to drop off their monitors and the Apple store will recycle it all. If you want to go straight through Apple, their recycling process is to purchase any Apple computer or monitor and receive free recycling of your old computer and monitor no matter what the brand is.

Computers consist of valuable resources, such as precious metals, copper, and engineered plastics. Recycling computers enables us to collect and reuse these valuable resources. For example, by recycling 100 million cell phones, about 7,500 pounds of gold could be recovered. Recovering this gold, instead of mining it, would prevent 12,000,000,000 pounds of loose soil, sand, and rock from having to be moved, mined, and processed.

Electronic waste isn"t just waste. It contains contaminants, such as mercury, lead, cadmium, arsenic, and beryllium. When these contaminants are burned at low temperatures they create more toxins and are released into the air. The toxic materials in electronics can cause cancer, reproductive disorders, endocrine failures and many other health problems if the waste is not properly disposed of. An estimated 70-80% of the electronic waste is exported to third-world countries. Once there the toxins are released into water sources and the land.

Scientists have found that by separating the panels in LCD screens, they can remove the polyvinyl-alcohol (PVA) and then produce a disinfectant. This substance is able to kill harmful bacteria including E-coli.

Andrew Hunt of the University of York says, "We can add significant value to this waste...that has great potential for use in biomedicine. Now we have gone a step further by enhancing its anti-microbial properties through the addition of silver nanoparticles, with the result being that it can destroy bacterial infections."

The amount of hydrogenated amorphous silicon is all dependable on the thickness of the thin film layer. These layers can range from nanometers to micrometers, and for the LCD monitors an average between the two will be used to determine the thickness.

1. Supercritical Carbon Dioxide Fluid Technology extracts the liquid crystals from the glass. This method uses iso-thermal and a depressurization method to remove the liquid crystal from the glass panel, by converting carbon dioxide gas to its supercritical fluid state, thus dissolving the liquid crystal. Then the temperature is dropped, the carbon dioxide reverts back to gas, leaving the liquid crystal

This process involves the use of a base, usually quaternary ammonium hydroxide, a surfactant and a high boiling solvent (di- or tri- propylene glycol alkyl ether.) to strip the silicon.

The cured silicon can be exposed to tetrabutyammonium fluoride reagent (TBAF) in non-hydroxylic aprotic solvent. This causes a disintegration of the polymer matrix, thus removing the silicon into the solvent.

Some computer monitors that use liquid crystal display (LCD) technology contaisn mercury, a highly toxic metal that can cause serious damage if ingested. The mercury in monitors is there to produce light when it is electrically energized. When the laptop monitors are tilted, mercury flows to one end cutting off the circuit and opening it on the opposite end. This is often function of an on and off switch.

At Stena Innovative Recycling, they clean units by separating it into iron, metals, plastics, circuit boards and glass with liquid crystals. The whole process works in a closed and controlled environment and during the process the levels of mercury are controlled, so Stena can be sure that all the mercury is removed from the material that will be recycled. The units that are contaminated with mercury are then sent to a hazardous waste treatment center.

The most efficient waste treatment process is to separate the backlight lamps from the panel. If the lamp is not taken out before, the whole display is deemed hazardous waste. Many treatment processes were explored, such as water-jet cutting, laser cutting and circular sawing, but the most efficient way is by manual dismantling. Costs per unit and the assessment quality were variables in the processes explored.

The purity of silane is 99.9999 percent. Electronically active impurities, such as boron, phosphorus, and arsenic are controlled to less than 10 parts per trillion. Silane is one of the purest materials on Earth.

The manufacturing process of silane that is used by REC produces consistent, pure silane by converting metallurgical grade silicon into trichlorosilane and redistributiing and distilling to silane. The constant flow process, recycles all hydrogen and chloride to initial reactors, while constant distillation steps purify the gas. This process is environmentally friendly.

In the most simple way to describe the production of silane, silicon is turned into a gas by grinding it down to a fine, sand-like consistency and heating it with hydrogen and silicon tetrachloride. After this is done it is then put through a series of reactions, as seen below, and silane and pure polysilicon are made.

Industrially, silane is produced from silicon in a two-step process. In the first step, powdered silicon reacts with hydrogen chloride at 300 °C to produce trichlorosilane, HSiCl3, along with hydrogen gas.

Another way to process silane is to start with metallurgical grade silicon, hydrogen, and silicon tetrachloride and let them go through a series of redistribution reactions and distillations as seen below:

In comparison to our characterization methods to purify our material, the in-situ analysis can be adapted by looking at the comparison of what our purity level is compared to the purity level found in nature.

As this figure is unknown, we can still determine what the cost per kg of recycling of the monitor must be less than in order to be a practical recycling process.

Alternatively instead of straight recycling only the silane recovered from the LCD PC monitors back into new monitors, we can also collect and extract the silane from other electronic devices that contain silane. The silane can also be put in other electronics devices with LCD screens. The silane can be used in the production solar panels, LCD TVs, smartphones, and other electronic devices which either have a LCD screen or need the silane to connect the glass to the polymer matrix in these devices.

One of the alternatives to straight cycling of the Silane is down-cycling it into titanium implants, so the biologically inert material in the implant can attach to the titanium implant. The recovered Silane can also be used as water repellent and masonry protection. The Silane can also be used for initiating the combustion for ramjets, reaction engines and liquid fuel rockets that have carbon dioxide in it.

As with any form of alternative recycling such as downcycling there are goods things and there are bad things. The good thing about downcycling is the silane is reused instead of extracting the silane from the Earth and having to go through the process of purification, which all require labor, energy, and other expenses. The bad thing about downcycling the silane is the loss in value of the silane. When the high quality silane extracted from the LCD PC monitor is downcycled into water repellent, then there is a tremendous loss in value of the silane.

-Amerimade designs a quartz bath specifically for use with semiconductor materials. It can also be heated to desirable tempertures. It is a great machine for the first step.

-This bath is made from quartz and can be heated to desirable tempertures. This particular bath was designed specifically for use with semiconductor materials. It is the same piece of equipment as step one, however it is a great fit for step two as well.

-Jinan Bakr Ultrasonic Technology Co., Ltd. makes an industrial cleaner that runs on electric power and can be heated, although it is not necessary for this particular step. It is a great machine to use for the isopropyl alcohol rinse because it"s also an ultrasonic cleaner.

-This industrial cleaner runs on electric power and can be heated, although it is not necessary for this particular step. It is a great machine to use for the deionized water rinse because it"s also an ultrasonic cleaner.

-This industrial cleaner runs on electric power and can be heated, although it is not necessary for this particular step. It is a great machine to use for the anhydrous IPA rinse because it"s also an ultrasonic cleaner.

-Gulf Coast Environmental makes industrial ovens engineered to your specific needs. These ovens will dry the substrate of any unwanted remaining chemicals so it will be able to be used in other applications.

Eye protection must be worn at all times throughout the plant, ear protection is encourage, closed toe boots are recommended, and proper clothing made of non-synthetic material should always be worn. Over-head showers and eye washing stations will be found near the exits as well as the middle of most work stations. Fire extinguishers will be within 20 feet of every machine. Emergency exits will be thoroughly outlined on the maps as you enter each room. Although the facility is ventilated, there will be fume heads located toward the more hazardous chemicals will be dealt with as well as emergency fans nearest the windows. Hazardous waste disposal bins will be located near fume hoods. OSHA regulations will be strictly reinforced.

Silane is flammable and will ignite on contact with air. It is irritating to the eyes and skin. In case of emergency and silane comes into contact with the skin, wash the affected area with soap and water. In case of contact with eyes, flush with water for 15 minutes. In case of deep inhalation, seek medical attention immediately. When handling, avoid air contact and make sure that there is no source of ignition anywhere near. Electrical equipment needs to be explosion proof. Neoprene, butyl rubber or polyethylene gloves should be warn when handling. To store silane, keep away from bases such as halogens and other oxidizing agents. Disposal of silane must be done in a compressed gas distributor when no longer in use.

This is the optimal flow for the theoretical process of recycling the semiconductor and other materials in LCD PC Monitors. There are two ways of the recycling center receiving the monitors, either by customer drop off or shipment to the center. This process is optimal because it recycles all of the material in the monitors. Also, the process of removing the semiconductor from the substrate has been laboratory approved to efficiently and easily remove the material.

"LCD Monitor Production Will Continue to Soar." TechEye. N.p., 07 June 2010. Web. 29 Sept. 2012.

"LCD Monthly Desktop Monitor Production Rate Highest Since Mid-2008 - DisplaySearch." LCD Monthly Desktop Monitor Production Rate Highest Since Mid-2008 - DisplaySearch. N.p., 01 Feb. 2010. Web. 29 Sept. 2012.

"LCD Monitors recycling." B.W Recycling Inc.. B.W. Recycling, Inc, 1 Sept. 2012. Web. 20 Sept. 2012.

"Recovery of Valuable Material from Waste Liquid Display Panel" Sciencedirect.com N.p., 7 Jul. 2009. Web. 29 Sept. 2012.

"Recovery of Valuable Material from Waste Liquid Display Panel" Sciencedirect.com N.p., 7 Jul. 2009. Web. 29 Sept. 2012.

"Recycling Liquid Crystal Displays (LCD)" voices.yahoo.com N.p., 11 Sept. 2006. Web. 29 Sept. 2012.

Falkenberg, Hedvig. "LCD RECYCLING." Stena Innovative Recycling. Stena, n.d. Web. 5 Oct. 2012. .

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Advantest (TSE: 6857) is the leading manufacturer of automatic test and measurement equipment used in the design and production of semiconductors for applications including 5G communications, the Internet of Things (IoT), autonomous vehicles, high performance computing (HPC) including artificial intelligence (AI) and machine learning, and more. Its leading-edge systems and products are integrated into the most advanced semiconductor production lines in the world. The company also conducts R&D to address emerging testing challenges and applications; develops advanced test-interface solutions for wafer sort and final test; produces scanning electron microscopes essential to photomask manufacturing; and offers system-level test solutions and other test-related accessories. Founded in Tokyo in 1954, Advantest is a global company with facilities around the world and an international commitment to sustainable practices and social responsibility.

Applied Materials, Inc. (Nasdaq: AMAT) is the leader in materials engineering solutions used to produce virtually every new chip and advanced display in the world. Our expertise in modifying materials at atomic levels and on an industrial scale enables customers to transform possibilities into reality. At Applied Materials, our innovations make possible a better future.

ASML is a leading supplier to the semiconductor industry. The company provides chipmakers with hardware, software and services to mass produce the patterns of integrated circuits (microchips). Together with its partners, ASML drives the advancement of more affordable, more powerful, more energy-efficient microchips. ASML enables groundbreaking technology to solve some of humanity"s toughest challenges, such as in healthcare, energy use and conservation, mobility and agriculture. ASML is a multinational company headquartered in Veldhoven, the Netherlands, with offices across Europe, the US and Asia. Every day, ASML’s more than 33,100 employees (FTE) challenge the status quo and push technology to new limits. ASML is traded on Euronext Amsterdam and NASDAQ under the symbol ASML.

ASMPT (HKEX stock code: 0522) is a leading global supplier of hardware and software solutions for the manufacture of semiconductors and electronics. Headquartered in Singapore, ASMPT’s offerings encompass the semiconductor assembly & packaging, and SMT (surface mount technology) industries, ranging from wafer deposition, to the various solutions that organise, assemble and package delicate electronic components into a vast range of end-user devices, which include electronics, mobile communications, computing, automotive, industrial and LED (displays). ASMPT partners with customers very closely, with continuous investment in R&D helping to provide cost-effective, industry-shaping solutions that achieve higher productivity, greater reliability and enhanced quality.

Edwards is the leading developer and manufacturer of sophisticated vacuum products, exhaust management systems and related value-added services. These are integral to manufacturing processes for semiconductors, flat panel displays, LEDs and solar cells; are used within an increasingly diverse range of industrial processes including power, glass and other coating applications, steel and other metallurgy, pharmaceutical and chemical; and for both scientific instruments and a wide range of R&D applications. Edwards has around 7,000 employees worldwide engaged in the design, manufacture and support of high technology vacuum and exhaust management equipment and has state-of-the-art manufacturing facilities in Europe, Asia and North America. Edwards is part of the Atlas Copco Group (NASDAQ OMX Stockholm: ATCO A, ATCO B), a Sweden-based provider of industrial productivity solutions.

EV Group (EVG) is a leading supplier of equipment and process solutions for the manufacture of semiconductors, microelectromechanical systems (MEMS), compound semiconductors, power devices and nanotechnology devices. Key products include wafer bonding, thin-wafer processing, lithography/nanoimprint lithography (NIL) and metrology equipment, as well as photoresist coaters, cleaners and inspection systems. Founded in 1980, EV Group services and supports an elaborate network of global customers and partners all over the world.

FormFactor, Inc. (NASDAQ: FORM), is a leading provider of essential test and measurement technologies along the full IC life cycle - from metrology and inspection, characterization, modeling, reliability, and design de-bug, to qualification and production test. Semiconductor companies rely upon FormFactor"s products and services to accelerate profitability by optimizing device performance and advancing yield knowledge. The Company serves customers through its network of facilities in Asia, Europe, and North America.

Founded in 1980 for the development of Korea semiconductor-based industry, Hanmi Semiconductor has grown steadily into a world-class semiconductor manufacturer and now we are the leading designer, developer & manufacturer of semiconductor equipment industry. Our success has been based on a number of factors such as the best assembly systems, efficiency of production, ongoing R&D investment & high-tech modules through 25 years quality improvement.

Hitachi High-Tech, headquartered in Tokyo, Japan, is engaged in activities in a broad range of fields, including Analytical & Medical Solutions (manufacture and sales of clinical analyzers, biotechnology products, and analytical instruments), Nano-Technology Solutions (manufacture and sales of semiconductor manufacturing equipment and analysis equipment), and Industrial Solutions (providing high value-added solutions in fields of social & industrial infrastructures and mobility, etc.).

HORIBA, Ltd. manufactures and sells instruments and systems for various applications. It operates in five segments: Automotive, Process & Environmental, Medical-Diagnostic, Semiconductor, and Scientific. The Automotive segment offers automotive emission analyzers, emission measurement systems, drive line test systems, engine test and fuel cell test systems, and battery test systems; test systems for engines, chassis, powertrains, brakes, and catalysts; and vehicle development engineering and testing engineering services, as well as leases and manages R&D facilities.

Jiangsu ASIA Electronics is a wet process equipment manufacturer in the semiconductor wafer manufacturing industry. It focuses on the wet etching and cleaning technology of the wafer front-end. It is one of the first domestic enterprises to promote the localization of high-end semiconductor equipment. Based on independent innovation, the company has formed a business model integrating R&D, design, production and sales, providing efficient wet process solutions for domestic and foreign wafer manufacturers.

KOKUSAI ELECTRIC designs, manufactures, and services thermal thin film processing solution systems. Our diffusion and deposition systems can be found in the majority of semiconductor fabrication plants worldwide.

Lam Research Corporation is a global supplier of innovative wafer fabrication equipment and services to the semiconductor industry. Lam’s equipment and services allow customers to build smaller and better performing devices. In fact, today, nearly every advanced chip is built with Lam technology. We combine superior systems engineering, technology leadership, and a strong values-based culture, with an unwavering commitment to our customers. Lam Research (Nasdaq: LRCX) is a FORTUNE 500® company headquartered in Fremont, Calif., with operations around the globe.

Established in 1974, Plasma-Therm is a global manufacturer of advanced plasma processing equipment, providing etch, deposition, surface modification, and plasma dicing technologies to the specialty semiconductor markets, including wireless communication, power devices, MEMS, photonics, advanced packaging, memory and storage, and R&D. Plasma-Therm"s products have been adopted globally and have earned their reputation for value, reliability, and world-class support. Sales and service locations throughout North America, Europe and Asia-Pacific meet the diverse needs of Plasma-Therm’s global customer base.

Teradyne (NASDAQ:TER) brings high-quality innovations such as smart devices, life-saving medical equipment and data storage systems to market, faster. Its advanced test solutions for semiconductors, electronic systems, wireless devices and more ensure that products perform as they were designed. Its Industrial Automation offerings include collaborative and mobile robots that help manufacturers of all sizes improve productivity and lower costs. In 2021, Teradyne had revenue of $3.7 billion and today employs over 6,000 people worldwide.

Tokyo Electron Limited (TEL) is a leading global company of semiconductor and flat panel display (FPD) production equipment, TEL engages in development, manufacturing, and sales in a wide range of product fields. All of TEL"s semiconductor and FPD production equipment product lines provide the foundation for the information industry, and also serves as core technologies that support innovations and enable the evolution of wide-ranging electronic devices. TEL provides outstanding products and services to customers through a global network in the U.S., Europe, and Asia.

VAT is the leading global developer, manufacturer and supplier of high-end vacuum valves. VAT vacuum valves are mission-critical components for advanced manufacturing processes of innovative products used in daily life such as portable devices, flat screen monitors or solar panels. VAT is organized into two different reporting segments: Valves and Global Service offering high-end vacuum valves, multi-valve modules, edge-welded bellows and related value-added services for an array of vacuum applications. VAT Group is a global player with over 2’500 employees and main manufacturing sites in Haag (Switzerland), Penang (Malaysia) and Arad (Romania).

We develop, design, manufacture, and sell displays where it is necessary for the interface that deliver a lot of information at an instant and deliver it to the global market. We create interactive spaces that go beyond the expected, elevate everyday lives, and move people"s hearts. From bases in major cities in Asia, Europe, and North America, we build strong customer relationships by developing products that respond to market needs.

Technology trends in backplane technology are driving higher gas demand in display manufacturing. Specific gas requirements of process blocks are discussed, and various supply modes are reviewed.

Since its initial communalization in the 1990s, active matrix thin-film-transistor (TFT) displays have become an essential and indispensable part of modern living. They are much more than just televisions and smartphones; they are the primary communication and information portals for our day-to- day life: watches (wearables), appliances, advertising, signage, automobiles and more.

There are many similarities in the display TFT manufacturing and semiconductor device manufacturing such as the process steps (deposition, etch, cleaning, and doping), the type of gases used in these steps, and the fact that both display and semiconductor manufacturing both heavily use gases.

However, there are technology drivers and manufacturing challenges that differentiate the two. For semiconductor device manufacturing, there are technology limitations in making the device increasingly smaller. For display manufacturing, the challenge is primarily maintaining the uniformity of glass as consumers drive the demand for larger and thinner displays.

While semiconductor wafer size has maxed because of the challenges of making smaller features uniformly across the surface of the wafer, the size of the display mother glass has grown from 0.1m x 0.1m with 1.1mm thickness to 3m x 3m with 0.5mm thickness over the past 20 years due to consumer demands for larger, lighter, and more cost-effective devices.

As the display mother glass area gets bigger and bigger,so does the equipment used in the display manufacturing process and the volume of gases required. In addition, the consumer’s desire for a better viewing experience such as more vivid color, higher resolution, and lower power consumption has also driven display manufacturers to develop and commercialize active matrix organic light emitting displays (AMOLED).

In general, there are two types of displays in the market today: active matrix liquid crystal display (AMLCD) and AMOLED. In its simplicity, the fundamental components required to make up the display are the same for AMLCD and AMOLED. There are four layers of a display device (FIGURE 1): a light source, switches that are the thin-film-transistor and where the gases are mainly used, a shutter to control the color selection, and the RGB (red, green, blue) color filter.

The thin-film-transistors used for display are 2D transitional transistors, which are similar to bulk CMOS before FinFET. For the active matrix display, there is one transistor for each pixel to drive the individual RGB within the pixel. As the resolution of the display grows, the transistor size also reduces, but not to the sub-micron scale of semiconductor devices. For the 325 PPI density, the transistor size is approximately 0.0001 mm2 and for the 4K TV with 80 PPI density, the transistor size is approximately 0.001 mm2.

Technology trends TFT-LCD (thin-film-transistor liquid-crystal display) is the baseline technology. MO / White OLED (organic light emitting diode) is used for larger screens. LTPS / AMOLED is used for small / medium screens. The challenges for OLED are the effect of < 1 micron particles on yield, much higher cost compared to a-Si due to increased mask steps, and moisture impact to yield for the OLED step.

Mobility limitation (FIGURE 2) is one of the key reasons for the shift to MO and LTPS to enable better viewing experience from higher resolution, etc.

The challenge to MO is the oxidation after IGZO metalization / moisture prevention after OLED step, which decreases yield. A large volume of N2O (nitrous oxide) is required for manufacturing, which means a shift in the traditional supply mode might need to be considered.

Although AMLCD displays are still dominant in the market today, AMOLED displays are growing quickly. Currently about 25% of smartphones are made with AMOLED displays and this is expected to grow to ~40% by 2021. OLED televisions are also growing rapidly, enjoying double digit growth rate year over year. Based on IHS data, the revenue for display panels with AMOLED technol- ogies is expected to have a CAGR of 18.9% in the next five years while the AMLCD display revenue will have a -2.8% CAGR for the same period with the total display panel revenue CAGR of 2.5%. With the rapid growth of AMOLED display panels, the panel makers have accel- erated their investment in the equipment to produce AMOLED panels.

There are three types of thin-film-transistor devices for display: amorphous silicon (a-Si), low temperature polysilicon (LTPS), and metal oxide (MO), also known as transparent amorphous oxide semiconductor (TAOS). AMLCD panels typically use a-Si for lower-resolution displays and TVs while high-resolution displays use LTPS transistors, but this use is mainly limited to small and medium displays due to its higher costs and scalability limitations. AMOLED panels use LTPS and MO transistors where MO devices are typically used for TV and large displays (FIGURE 3).

This shift in technology also requires a change in the gases used in production of AMOLED panels as compared with the AMLCD panels. As shown in FIGURE 4, display manufacturing today uses a wide variety of gases.

These gases can be categorized into two types: Electronic Specialty gases (ESGs) and Electronic Bulk gases (EBGs) (FIGURE 5). Electronic Specialty gases such as silane, nitrogen trifluoride, fluorine (on-site generation), sulfur hexafluoride, ammonia, and phosphine mixtures make up 52% of the gases used in the manufacture of the displays while the Electronic Bulk gases–nitrogen, hydrogen, helium, oxygen, carbon dioxide, and argon – make up the remaining 48% of the gases used in the display manufacturing.

The key ga susage driver in the manufacturing of displays is PECVD (plasma-enhanced chemical vapor deposition), which accounts for 75% of the ESG spending, while dry etch is driving helium usage. LTPS and MO transistor production is driving nitrous oxide usage. The ESG usage for MO transistor production differs from what is shown in FIGURE 4: nitrous oxide makes up 63% of gas spend, nitrogen trifluoride 26%, silane 7%, and sulfur hexafluoride and ammonia together around 4%. Laser gases are used not only for lithography, but also for excimer laser annealing application in LTPS.

Silane: SiH4 is one of the most critical molecules in display manufacturing. It is used in conjunction with ammonia (NH3) to create the silicon nitride layer for a-Si transistor, with nitrogen (N2) to form the pre excimer laser anneal a-Si for the LTPS transistor, or with nitrous oxide (N2O) to form the silicon oxide layer of MO transistor.

Nitrogen trifluoride: NF3 is the single largest electronic material from spend and volume standpoint for a-Si and LTPS display production while being surpassed by N2O for MO production. NF3 is used for cleaning the PECVD chambers. This gas requires scalability to get the cost advantage necessary for the highly competitive market.

Nitrous oxide: Used in both LTPS and MO display production, N2O has surpassed NF3 to become the largest electronic material from spend and volume standpoint for MO production. N2O is a regional and localized product due to its low cost, making long supply chains with high logistic costs unfeasible. Averaging approximately 2 kg per 5.5 m2 of mother glass area, it requires around 240 tons per month for a typical 120K per month capacity generation 8.5 MO display production. The largest N2O compressed gas trailer can only deliver six tons of N2O each time and thus it becomes both costly and risky

Nitrogen: For a typical large display fab, N2 demand can be as high as 50,000 Nm3/hour, so an on-site generator, such as the Linde SPECTRA-N® 50,000, is a cost-effective solution that has the added benefit of an 8% reduction in CO2 (carbon dioxide) footprint over conventional nitrogen plants.

Helium: H2 is used for cooling the glass during and after processing. Manufacturers are looking at ways to decrease the usage of helium because of cost and availability issues due it being a non-renewable gas.

N2 On-site generators: Nitrogen is the largest consumed gas at the fab, and is required to be available before the first tools are brought to the fab. Like major semiconductor fabs, large display fabs require very large amounts of nitrogen, which can only be economically supplied by on-site plants.

Individual packages: Specialty gases are supplied in individual packages. For higher volume materials like silane and nitrogen trifluoride, these can be supplied in large ISO packages holding up to 10 tons. Materials with smaller requirements are packaged in standard gas cylinders.

Blended gases: Laser gases and dopants are supplied as blends of several different gases. Both the accuracy and precision of the blended products are important to maintain the display device fabrication operating within acceptable parameters.

In-fab distribution: Gas supply does not end with the delivery or production of the material of the fab. Rather, the materials are further regulated with additional filtration, purification, and on-line analysis before delivery to individual production tools.

The consumer demand for displays that offer increas- ingly vivid color, higher resolution, and lower power consumption will challenge display makers to step up the technologies they employ and to develop newer displays such as flexible and transparent displays. The transistors to support these new displays will either be LTPS and / or MO, which means the gases currently being used in these processes will continue to grow. Considering the current a-Si display production, the gas consumption per area of the glass will increase by 25% for LTPS and ~ 50% for MO productions.

To facilitate these increasing demands, display manufacturers must partner with gas suppliers to identify which can meet their technology needs, globally source electronic materials to provide customers with stable and cost- effective gas solutions, develop local sources of electronic materials, improve productivity, reduce carbon footprint, and increase energy efficiency through on-site gas plants. This is particularly true for the burgeoning China display manufacturing market, which will benefit from investing in on-site bulk gas plants and collaboration with global materials suppliers with local production facilities for high-purity gas and chemical manufacturing.

As display panels get bigger, thinner and more expensive, manufacturers look to the semiconductor industry for guidance on how to get particle contamination under control

In the electronics industry where the never-ending goal is usually to shrink the size of products and technology, display manufacturing is an anomaly. It is one of the few sectors struggling to meet the demand for bigger technology, bigger tools, and bigger production facilities. In a world where smaller equals better, display manufacturers are often pushing the envelope in the opposite direction.

As consumer demand for giant screen TVs, advanced gaming devices, and huge computer monitors grows, the display industry rushes to advance its technology and fabs to accommodate the need. New glass technology and world-class processes are constantly moving forward to address the continual development of larger, thinner, lighter, sharper and more cost-efficient displays.

In the beginning, consumers were happy with boxy 30-inch TVs and would tolerate a few blank spots on an otherwise working screen, but today expectations are much higher. Liquid crystal displays (LCDs), which offer several advantages over traditional cathode-ray tube (CRT) displays, are becoming the norm for today’s TV and computer screens. Since 2000, glass substrate size has approximately doubled every 1.5 years. It took ten years for the display industry to migrate from Generation One glass sizes to Generation Four, but it took only four years to get from Generation Four to Generation Seven glass sizes. Generation Five and larger size substrates are expected to account for nearly 80 percent of all glass substrates produced by 2007.

This fast migration to larger-generation glass is driven both by product applications, such as bigger, flatter TVs and desktop monitors, and by economies of scale. Large generation glass offers dramatic manufacturing efficiencies, allowing display makers to produce more panels at lower costs with less waste. While a typical Generation Four sheet yields four 17-inch panels, a Generation Five sheet increases that yield threefold, to twelve 17-inch panels. A Generation Six substrate can produce eight larger panels of 32 inches, and a Generation Seven substrate can produce twelve 32-inch panels.

The industrywide migration by LCD manufacturers to large-generation substrates is expected to reduce prices to consumers, further driving the adoption of LCD technology in the desktop monitor and television market segments. LCD desktop monitors accounted for more than 50 percent of all monitors sold in 2004 and are projected to account for nearly 80 percent in 2007, which is twice the penetration rate of 2003. In 2004, LCD TVs represented only 5 percent of the color television market, but new screen sizes, falling prices and expanding availability are expected to drive market penetration to approximately 20 percent by 2007.

Ironically, even though display screens and the tools and fabs that make them are expanding in size with every new product generation, display manufacturers face the same challenges that the semiconductor industry faced as its products and technology continued to shrink.

Contamination control, for example, is becoming more critical, and the need for standards to manage the production process is increasing, just as it did for the semi industry several years ago. As a result, display manufacturers often look to the semi industry for guidance, says Mark Merrill, vice president of Photon Dynamics, a San Jose, California-based yield management company that offers test, repair and inspection tools throughout array, cell and module fabs for the display-panel manufacturing industry (see Fig. 1). “The display manufacturing process is a lot like the semiconductor manufacturing process, it’s just simpler and bigger.”

Figure 1. Photon Dynamics offers a full suite of yield management solutions for the FPD industry, including test, repair and inspection of LCDs. Photo courtesy of Photon Dynamics, Inc.Click here to enlarge image

For display manufacturers, how well they manage contaminants in the processing environment determines increases or decreases in their yield. Even though display products keep increasing in size, particle contamination is becoming more of a problem, with tolerances for particulate size and counts continually decreasing.

As in the semi industry, where one particulate can destroy an entire chip, in large-display manufacturing one unfortunately placed particle can ruin an entire large, flat screen, which is a much more costly yield loss than the smaller panels of previous generations.

If the manufacturer is making smaller displays, a single panel of glass might be cut into 16 individual panels, whereas if it’s making larger displays, it may only be cut into four panels. “Imagine 100 particles falling on that piece of glass, and five of them cause pixel damage,” Merrill says. “That might kill five of the 16 smaller panels, but it could kill all of the four larger panels. That has a huge impact on yield.”

Managing yields through process control is an essential component of optimizing costs and time-to-market throughout the electronics industry. In the flat-panel display sector, the industry’s migration toward high-volume production of larger display panels is driving the need to maximize manufacturing yields. “They are bigger panels, but they have the same defect density,” Merrill points out, which means the environment can support fewer particles just to achieve the same yields.

While there are no conclusive statistics about the average yield of display manufacturers, Merrill estimates the industry is achieving 70 to 90 percent yields. The numbers improve as a fab matures and kinks are worked out of the system, he says.

A 90 percent yield may sound impressive for some industries, but in display manufacturing, where one panel costs close to $1000, a yield loss of 2 percent can cost a company several million dollars. Because of the high cost of materials used in the manufacture of LCDs, defective LCDs, especially larger displays, can be quite costly and ultimately drive up both panel and end-product costs. “That’s the reason why, in this industry, you test 100 percent of the product,” Merrill says. “We don’t just sample. We need to know that every single panel is going to work.”

As a result of the growing cost of yield loss, display fabs are fighting to achieve cleaner environments, and manufacturers are paying closer attention to the tools used to monitor and control contaminants throughout the manufacturing process (see Fig. 2).

Figure 2. Pictured here is the latest-generation ArraySaver™ system from Photon Dynamics, Inc. used in the manufacture of LCDs. Photo courtesy of Photon Dynamics, Inc.Click here to enlarge image

“Yield management becomes increasingly critical with each successive product generation,” Merrill says. “As manufacturers bring sixth-, seventh- and eighth-generation fabs online, yield management will emerge as one of the chief gating factors.”

Manufacturing high performance LCDs for TV applications further increases process complexities, especially when dealing with color filters on array, viewing angle technologies, and photo spacers on color filters that are applied to the glass during processing.

Adding to the challenge of controlling particulate contamination is the fact that the fabs, the tools and the glass keep getting bigger. Every new generation of fab increases in size to accommodate the equipment needed to manage the product. Fabs today span several football fields in size, and the glass panels may be two to three meters across. Because of its size and weight, the glass is transported on ever bigger conveyers, which require larger open air spaces and broader chamber doors to move the glass in and out of the work space. The fab itself continues to expand, requiring more floor and air space, making environmental control processes more complex.

New equipment is also much heavier, creating greater stress on the environment and tools, both when it’s moved and used. “It’s also more complicated to install,” adds Merrill who notes that the photo equipment alone can weigh 60,000 kilograms and take months to install.

Once a fab is up and running, the display manufacturing process begins with the production of the glass, explains Peter Bocko, division vice president of commercial technology for Corning Display Technologies, maker of pristine flat glass used in LCDs for computer and electronics companies. These glass substrates are the foundation for active matrix LCDs.

The display manufacturing process has greatly improved over the last two decades, according to Bocko. He remembers a time when glass furnaces were made out of brick, and they often sat outside a machine shop perpetually encased in a cloud of dust. When the glass hardened, a worker would manually etch and break it and carry it to the next step in the process. “In the early days it was amazing what you’d find on the surface of the glass-cigarette smoke particles, lubricants, binder materials from gloves, skin flakes. Anything you can imagine,” Bocko says.

The manufacturing process has evolved dramatically since the early days, with much stricter monitoring of the process and environment, from raw material to finished product. “Today, the entire process, from melting on, is in a controlled environment,” he says.

Most display fabs today are Class 10,000 [ISO Class 7] environments, and for the last 10 years they’ve been managed mostly by robotics. The automation is both to eliminate human error and because the glass is too heavy for human handling (see Fig. 3).

Figure 3. To eliminate human error and because the glass is too heavy for human handling, many display fabs today use robotics in their manufacturing processes. Photo courtesy of Corning Display Technologies.Click here to enlarge image

At Corning, source material is fed into a furnace through a platinum tube where it is blended into a precise glass composition, which is then melted and conditioned to be homogenous and virtually defect-free.

When the molten glass achieves the right viscosity and temperature, it is fed into an arrowhead-shaped trough called an Isopipe. The glass flows evenly over both sides of the trough, meeting at the pointed bottom where it forms into a continuous sheet of viscous glass that is 0.7 to 0.5 millimeter in thickness. These thinner glass panels dramatically reduce the overall weight of the end product, but create a more delicate surface with which to work.

Because the glass sheet is formed in air, its surface is pristine and flat; no subsequent grinding or polishing, which could damage the glass, is required. The fusion process also maintains tight control over the thickness of the glass, leading to a consistent product. This is critical in the production of panels for LCD televisions, where viewing angle technology sensitizes the image to thickness differences in the glass.

“At this point in the process, the glass has the purest surface imaginable,” Bocko says. “There are no particulates or organic content anywhere. From this fusion step until it reaches the customer, it’s all about contamination control. Everything you do to it from here on only degrades the surface.”

How much degradation occurs depends on how the glass is handled and how clean the environment is in which it is processed. Every step in the process creates potential contaminants. When the glass is etched, broken and polished, particulate material is generated; the tools used to process the glass create dust and metal particles; cleaning chemicals and water used during beveling can leave residues; and transportation exposes the glass to potential damage from contaminants and movement. “There are two things that are especially bad for an LCD surface-water and particulates,” Bocko says.

At Corning, to reduce the risk of both kinds of contamination, once the glass is cut and broken using robotic devices, it is covered in a protective polymer coating sheet, which prevents environmental contamination from adhering to the glass, Bocko says. This coating, specially designed for Corning’s glass-manufacturing process, took years to develop because it required a surface that would adhere to the glass to protect it during processing but would also be easy to peel off without leaving surface material behind. “This is a highly engineered polyethylene-based adhesive that won’t leave a residue when it’s removed,” he says.

The coated glass is taken to a finishing area where it is etched, cut to fit, and the raw edges are polished. The coating is then removed so the glass can be washed and dried.

Washing is done through ultrasonic mechanical agitation, using pure water and chlorine-based detergents. It includes a soft-brush scrub, sonic rinsing processes, and drying using compressed air to push the water off the back of the glass, eliminating the risk of water residue.

Once the glass is cleaned, a worker uses a computer monitor to inspect it for defects. If particulates are discovered, the inspector must judge whether they can be removed during processing or whether the glass should be scrapped (see Fig. 4).

Figure 4. If particulates are discovered, an inspector must judge whether they can be removed during processing or whether the glass should be scrapped. Photo courtesy of Corning Display Technologies.Click here to enlarge image

“We monitor particulates to one micron,” Bocko says. “And if any particulate larger than three to five microns remains on the glass after it is washed, the glass can be rejected.” The size limit of three to five microns is critical because this is the thickness of the LCD layer that’s sandwiched between the layers of glass.

Liquid crystal is a state that exists between solid and liquid, which certain kinds of matter can achieve under the right conditions. The molecules in liquid crystal do not all point in the same direction all the time as they do in solids; however, over time, they tend to point more in one direction than others. This direction is referred to as the director of the liquid crystal. The “amount” of order is measured by the order parameter of the liquid crystal, which in turn is highly dependent on temperature.

LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light. They are flat, and use only a fraction of the power required by CRTs. Thus, a particle thicker than the liquid center will create a cell gap in the final product, knocking out pixels and leaving dark spots on the screen.

If a panel is approved, the finished glass is then packed for delivery to the customer (see Fig. 5). Packaging and transporting large-generation substrates present another set of challenges.

Figure 5. If a panel is approved, the finished glass is then packed for delivery to the customer, presenting another set of challenges. Photo courtesy of Corning Display Technologies.Click here to enlarge image

In the conventional system, glass panels are packed in slotted crates to prevent them from touching as a result of vibration during transport. The air gap needed between each substrate in a slotted crate limits the number of substrates per case to twenty.

Corning recently switched to a new technique that protects the glass and allows for greater numbers of panels to be shipped in a smaller amount of space. Called the “DensePak” system, it allows for the safe transport, storage and staging of up to 500 sheets per case, in the same footprint as a 20-substrate case.

In the DensePak, another layer of polymer film is adhered to each panel, so they can be packed side-by-side in a vertical glass brick. “The polymer surface is enough to protect the glass, and it’s more efficient because it doesn’t require huge shipping boxes full of air,” Bocko says.

Once the glass is received, the film is removed and any remaining residue is cleaned away. “That cleaning process brings the glass back to the original surface quality,” Bocko says.

The glass is then reinspected and prepped for LCD applications. At this stage in the process, the two layers of glass are sandwiched together with a thin layer of LCD material between them.

Particulates continue to be an increasing risk as the display-manufacturing industry strives to master thinner LCD layers in an effort to create clearer, sharper pictures. “With thinner technology, even smaller particulates will cause problems,” Merrill says. “A half-micron particle in the right spot could take out a whole panel.”

Because the challenges of managing particulates in such a large environment are so great, and the impact on yield so significant, reliable, repeatable methods of analyzing production-line data and repairing process-related defects are essential for the production of larger, higher-quality LCDs at affordable price points. This means testing the glass at key steps in the manufacturing process to ensure that particulates have been removed before panels are permanently affixed with LCD material.

When the pixels are in place on a display prior to its completion, they can be powered up using an LCD sensor that determines whether they will turn on. If the test reveals a dark pixel due to a microscopic particle, it can often be vaporized or knocked out with a laser to fix the problem, Merrill says.

If particulate is inside, however, once the LCD material is sandwiched between the glass, it can’t be repaired. “At that point, the best you can do is try to determine the source of the contamination so you can fix it before it does more damage,” he says.

Fortunately, there are only four or five steps in the display-manufacturing process, making it easier to find the contamination culprit. The industry doesn’t always analyze the make-up of any given particulate, instead manufacturers look back over the life of the panel to identify the problem. It may be caused by failure in a process tool, human error, or a cleaning problem. “Finding the source requires a lot of excursion control,” Merrill says.

To determine whether tools are emitting high particulate counts, process inspectors may use a laser particle counter. They also perform regular airflow monitoring and use HEPA filters to remove low concentrations of airborne molecular contaminants generated during the manufacturing process or by the equipment, says Manjaya Hegde, continuous improvement leader in the Silicon Valley office of PerkinElmer, a global technology leader for health sciences, optoelectronic and photonics markets. “We have 100 percent HEPA coverage in our fabs,” he says.

At PerkinElmer, the tools, ovens and vacuums all have HEPA filters, which are changed on a set schedule, and the overall environment also has a laminar airflow control system. The airflow is maintained at 90 FPM (+/-20 FPM), Hegde says. “If it goes above 110 FPM, it will generate turbulence that can cause particles to swirl through the room.”

In the scribing and breaking areas, which generate a lot of larger glass particles, HEPA-filtered vacuums are used to clean the glass surfaces and remove particles from the air and equipment surfaces.

Strict gowning techniques are followed, and personnel are prohibited from wearing makeup or perfume in the fab. All consumables, including wipes, swabs, and filters, are sterilized and double-bagged before they are brought into the fab. The first bag is opened in the first chamber of the cleanroom, after gowning is completed. To prevent any external contaminants entering the cleanroom environment, the outer bag is left in the transition chamber, and the inner sterile bag is opened in the fab. “Fab personnel go through retraining every six months to reinforce these techniques,” Hegde says.

Cleanroom gowns are washed weekly and are tested for particulates before being bagged and returned to the fab for use. PerkinElmer conducts audits of its garment suppliers twice a year, testing the water, equipment, preventive maintenance techniques, and environmental particulates to ensure they meet cleanroom compliance standards.

To further manage contamination before it gets out of control, monitors in the fab run checks every five seconds on temperature and humidity, and manual checks are conducted monthly in eight zones in the fab to verify that the environment is clean and tools are running according to spec.

Regular, systematic cleaning, sanitation and preventive maintenance strategies also help to reduce particulates in the fab environment. During cleaning, the tool components are regularly wiped down to eliminate rogue particles, and the quality-control team monitors cleaning chemicals and the chemical filters, changing them when the liquid particle counts become too high.

Through an environmental monitoring program, Hegde’s team also regularly counts and measures particle contaminants in 500 locations in the fab, looking for changes in trends throughout the processing steps.

He’s found that the best way to monitor actual particles in the fab is to use a witness panel, which is a glass substrate with a metalized layer, left at workbench level in a working fab for up to 10 days. Hegde moves the witness panel around the fab, scanning the particles accumulated in each area. “Even with HEPA filters there are going to be a lot of particles in the environment,” he admits. “But if they get outrageous, we analyze them and try to eliminate the problem.”

The display industry is still easily a decade behind semconductor in its ability to control contaminants, and it continues to be an issue. As the display industry moves toward the future, fabs will get bigger and processors will struggle to bring yields under control. Consumers will continue to demand bigger and higher-quality screens, and their tolerance for any faults is already minimal, notes Bob Pinnel, chief technology officer for the U.S. Display Consortium in San Jose, Calif. “In the first laptops, six faulty pixels were considered acceptable,” he says. “Now it’s zero in almost all high-quality display products.”

Because the environments are so large, Pinnel suggests that the way the industry will manage its contamination challenges is to eliminate risks as early as possible and improve its inspection and repair technology. “Quality control tools are the way manufacturers will manage yield,” he says.

Merrill agrees: “In the future, even more emphasis will be placed on cleaner environments and on the ability to measure the quality of the contamination-control techniques,” he says, but he notes that quality and quantity go hand-in-hand. “You can spend the time to create the perfect clean environment, but while you do that, your competition will leapfrog ahead of you,” he says. “It’s a constant balancing act.”

He also suspects fabs will move toward vertical glass handling, more minienvironments within the fab, and pick-in-place robot cassettes to streamline processes. “When you get every processing step in line, you can deal with it more predictably,” Merrill says. “It’s a cleaner manufacturing process.”

While the equipment manufacturers would like to see standards developed for manufacturing technology, display manufacturers are typically so large and self-contained that this has, thus far, been a tough sell. “For larger groups, it’s cost effective to create their own in-house handling systems,” Merrill says. Even though standards would ultimately bring the costs of equipment down, the companies would have to change the way they do things internally to meet the standards, which is unlikely to happen unless external forces in the industry demand it. “It’s a Catch 22, but eventually standards will come.”

SCREEN SPE USA (SEUS) was established in 1987 in Sunnyvale, California. SEUS is the sales, marketing, engineering and service organization responsible for operations in the US market for SCREEN Semiconductor Solutions, Co. Ltd., Kyoto, Japan. SEUS has 8 major local offices in the US to better serve our customers.

SCREEN Semiconductor Solutions, Co., Ltd is a manufacturer of semiconductor equipment for lithography coat/develop, wet cleaning/etching, thermal annealing and metrology applications. SCREEN is well known in the industry for manufacturing the most reliable equipment used in the production of semiconductor wafers and has won high marks year after year for its equipment reliability.

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