national technology roadmap for flat panel displays
01/01/1998
National Technology Roadmap for Flat Panel Displays
J. Norman Bardsley, US Display Consortium, San Jose, California
Following decades of research, the flat panel display (FPD) industry has expanded rapidly in the past decade, primarily through the development of manufacturing techniques for liquid crystal displays (LCDs) and courageous investments at the multibillion dollar level by Japanese companies. The growth of this $10B industry has been mainly driven by one product, the laptop computer screen. Much of the financial reward for this invention has accrued to the US companies, such as IBM and Compaq, that have led the development of the portable computer.
A few US companies have also gained dominant positions in supplying equipment and materials to the FPD industry. Corning Glass has maintained its lead in supplying alkali-free glass for active matrix LCDs (AMLCDs), which is now available in sizes over 1 m2. Within a few years of entry into the market, Applied Materials became the leading supplier of manufacturing tools, through its joint venture, Applied Komatsu Technologies (AKT).
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Leveraging the support of technology development by the Defense Advanced Research Projects Agency and the base of manufacturing infrastructure built by the US Display Consortium (USDC), pioneering US companies have developed excellent products for specialized markets. To facilitate strategic planning by all participants in the display industry, the USDC has embarked on the development of a National Technology Roadmap for Flat Panel Displays. The Roadmap should be completed for review by the USDC membership in mid-1998, and released to the public later this year. As shown in the table (above), the Roadmap is based on the work of 14 committees organized at three levels: display users, display manufacturers, and suppliers of equipment, materials, and components.
Consumer applications
During the past two years, FPD manufacturers with third-generation lines, which use glass substrates of 550 ? 650 mm and up, gained considerable advantage from the manufacture of six 12.1-in. and 13.3-in. notebook panels from each substrate. The capacity for these displays appears to have overtaken the demand, leading to price reductions similar to those experienced for 10.4-in. displays in 1995. The pixel count of the displays has improved by one generation, and XGA may soon replace VGA as the most popular format. Although further increases in screen size, to 14.1 in. or even 15 in., may occur, properties such as weight and power consumption will become more important in differentiating notebook displays. Recent reductions in the cost of 8-bit drivers should result in better color scales. With respect to resolution, it will be interesting to see whether customers remain satisfied with pixel sizes of 0.25-0.30 mm, similar to CRT monitors, or whether they will demand picture quality closer to that of photographs and magazines.
Even if improvements in technology revive the notebook market, still more additional capacity will come on-line in Japan, Korea, and Taiwan during the next few months. This overcapacity should lead to further price erosion unless new large-volume markets emerge. Penetration of the desktop monitor market is difficult, because of the low cost and good performance of the CRT, but the recovery of lost desk space alone will justify a modest price premium. Entry to this sector is possible because of improvements in viewing angle, obtained by in-plane switching, multiple-domain pixels, or compensation films. Continued progress in such areas as resolution, brightness, and color quality will be needed, as well as reduced manufacturing costs for large displays. The price sensitivity of this market sector has given new life to the passive matrix LCD devices, especially super-twisted nematic (STN) devices with improved response times.
The home entertainment market is being driven by the onset of high-definition television and the convergence of the TV and computer industries. The large weight and volume of direct-view CRTs above 40 in. in diagonal size open opportunities for projection systems and plasma displays, provided that the cost can be brought down. Asian companies have already made substantial investments in fabrication facilities for large-screen plasma display panels (PDPs), and many companies have recently entered the projection market, which also includes educational and business applications.
Japanese and European markets have seen rapidly growing interest in navigation systems, with high-resolution maps backed up by often-refreshed data bases with information on traffic conditions, parking lot availability, restaurants, and lodging. However, US automobile companies seem to regard displays as opportunities for cost reduction rather than for product differentiation. There are perhaps greater openings for sunlight-readable, hand-held displays with very low weight and power consumption. Truly portable multifunctional devices will soon be feasible, combining many of the capabilities of the current pager, cellular phone, personal computer, internet interface, and camera.
Military applications
The USDC`s Military and Avionics Users Group has been working closely with the Department of Defense (DoD) to analyze the display needs of the military, including the replacement of traditional electromechanical and CRT displays in aircraft, surface vehicles, and submarines, and the requirements of future systems. These applications require relatively small numbers of a wide variety of displays. The current annual demand of around 30,000 displays would represent approximately three days` output from a single fabrication line, if they could be produced with the same efficiency as notebook displays. Most military displays must endure much greater environmental stress than the typical notebook. For example, temperatures of well over 100?C have been measured in armored vehicles and parked aircraft in desert conditions.
Active debate is underway as to the relative merits of custom manufacturing of military displays and the ruggedization of displays designed for civilian applications. However, using either approach, the defense market alone seems insufficient to support a viable business. Successful companies must develop products for both military and civilian segments. A fine example of such dual use is seen in the 19-in. LCD from dpiX, shown in the photo, which was first developed for the DoD Common Large Area Display Program, but has now been adapted for commercial use. Further collaboration between industry and the DoD is essential to provide a more attractive business climate, while reducing the total costs of purchasing, maintaining, and updating military displays. Greater standardization of both the physical characteristics and the electronic interface for military displays will also be necessary.
Display technologies
US display manufacturers are pursuing various technologies, six of which are included in the Roadmap. At least two companies should soon be producing field emission displays aimed at the communications, automobile, instrumentation, and computer markets. Following the success of projection systems based on the Digital Micromirror Device from Texas Instruments and on small polysilicon LCDs from Japan, several innovative techniques have emerged for the fabrication of miniature light valves on silicon substrates. The major problems are providing compact light sources and faithful, but inexpensive, viewing optics. Improved techniques for the generation of blue light have given renewed impetus to electroluminescent and inorganic light-emitting diodes (LEDs), and the potential of organic LEDs (OLEDs), using either polymers or small molecules, is exciting. PDPs provide excellent performance on large-area screens, but require improvement in resolution as well as reductions in manufacturing cost. However, it is becoming more difficult for alternative technologies to compete with the ever-improving price and performance of LCDs and CRTs.
Suppliers
The most successful new suppliers to the large-volume manufacturers have been those companies that can leverage experience in the semiconductor industry, for example, through coating, deposition and etch equipment, driver electronics, and handling equipment (PST). Other companies, such as Intevac in sputtering and MRS and Tamarack in lithography, are developing tools with special characteristics for the FPD market.
The major emphasis, on minimizing cost of ownership, can be achieved by faster processing to increase throughput, as in the Lam high-density etching tool, or reduced use of consumables, as in the extrusion coater from FAS or the PVD tool from AKT. The number of process steps can be reduced through multilayer deposition or etching or avoiding the need for passivation layers in TFTs.
Reduced downtime can be achieved by inline chamber cleans in AKT`s CVD tool or better integration of handling equipment and processing tools. Yield must be increased, for example, by minimizing contamination and damage during handling.
There are also many opportunities for suppliers to support US companies in the flexible manufacturing of specialized displays through the production of more light sources, sealing equipment, or high-voltage drivers. Perhaps the greatest challenge and opportunity is to develop an alternative substrate, which is lighter and more flexible, but does not compromise glass` excellent optical transmission, strength, and chemical protection.
Fourth-generation equipment
The rapid pace of change in FPD fabri-cation methods and the difficulty of sus-taining profits in a competitive business give great incentive for those at all industry levels to collaborate in productivity improvements through innovative manufacturing techniques, better materials, and adoption of industrywide standards.
Under the auspices of Semi/Japan, the Production Cost Savings Task Force has just concluded the second phase of its studies. This committee brings together the leading manufacturers of LCD displays in Japan with major suppliers of equipment and materials. Its goal was to achieve a two-fold increase in productivity within about three years, either by optimization of third-generation fabrication lines or through the introduction of fourth-generation equipment.
The group first concluded a major gap exists between the desires of display manufacturers and the expectations of suppliers. This gap reminds us that progress is never easy, but does offer an opportunity for innovative tool or material products to enter the market. Second, the task force found that the major benefits of fourth-generation equipment will be seen in the manufacture of screens >15 in. diagonal. The study assumed that the size of fourth-generation substrates would be 800 ? 950 mm, suitable for production of nine 14-in. panels, six 17-in. panels, or four 21-in. panels.
Some of the major problems anticipated with the introduction of such large substrates include size, cost, and weight of the lithography equipment, the lower yields predicted for glass manufacturing, and the difficulty of glass handling and storage. Vigorous discussions of the relative merits of horizontal and vertical handling and of single-substrate vs. cassette transport are to be expected. Floor space will become even more precious and greater use of overhead or subfloor conveyance may develop.
Conclusion
Success at any level of the display industry requires a combination of innovative technology, efficient manufacturing, international partnerships, and a timely business plan. The rapid pace of change provides many opportunities, especially for companies that are already established in industries with some overlapping techniques or material needs.n
J. Norman Bardsley is director of roadmaps and standards at USDC, 50 West San Fernando Street, Suite 920, San Jose, CA 95113; ph 408/277-2400, fax 408/277-2490.