Metal Oxide Thin-Film Transistor Markets

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Metal Oxide Thin-Film Transistor Markets Nano-527

Published April 2012 © NanoMarkets, LC

NanoMarkets, LC PO Box 3840 Glen Allen, VA 23058 Tel: 804-270-1718 Web: www.nanomarkets.net

NanoMarkets, LC | PO Box 3840 | Glen Allen, VA 23058 | TEL: 804-270-1718 | FAX: 804-360-7259

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About the Report: Display backplanes fabricated with silicon TFTs are the industry standard for displays of all kinds. However, in the past decade various attempts have been made to move beyond silicon either on cost or performance grounds. A decade ago, the big promise seemed to come from Page | 1 organic transistors, but their promise has faded as their electron mobilities have proven to be woefully inadequate. This report analyzes the market for the next wave of non-silicon TFTs to be pitched towards backplane and other applications. This wave uses metallic oxides and TFTs made from these materials promise electron mobilities of more or less the same level as amorphous silicon, but with lower costs. Interest in these materials is at a high point with some of the biggest names in displays – Sony, Sharp, Samsung, LG and Toshiba – making serious efforts to commercialize TFTs. This report also examines the potential of these developments for new business revenues for materials firms that produce complex metallic oxide semiconductors. Until very recently, the addressable markets for such materials have been entirely in the R&D space. This report examines the key markets for oxide TFTs in the LCD, OLED and e-paper space. In addition, it also takes look at their role in other more speculative markets such as flexible displays, transparent electronics, sensors, RFID and even power electronics. This report also presents an analysis and roadmap for the development of oxide OTFT technology both in terms of materials and manufacturing technology. In terms of the former, it takes a look at the difference that the arrival of p-type oxide semiconductors may have on the commercialization of oxide TFT technology. In addition, this report analyzes the market strategies for companies developing this technology and also includes an eight-year forecast made by application and material type. Table of Contents Executive Summary E.1 Summary of opportunities for products utilizing metal oxide TFTs E.1.1 Display opportunities E.1.2 Other opportunities E.1.3 Opportunities for materials firms E.2 Firms to watch in this space E.3 Summary of eight-year forecasts for metal oxide TFT products Chapter One: Introduction 1.1 Background to report NanoMarkets, LC | PO Box 3840 | Glen Allen, VA 23058 | TEL: 804-270-1718 | FAX: 804-360-7259

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1.2 Objective and scope of report 1.3 Methodology of report 1.4 Plan of report Chapter Two: Oxide TFTs Technology: Assessment and Roadmap 2.1 Zinc oxide-based materials 2.1.1 Indium Gallium Zinc Oxide (IGZO) 2.1.2 Indium Zinc Oxide (IZO) 2.1.3 Zinc Tin Oxide (ZTO) 2.1.4 HIZO 2.1.5 Aluminum-doped zinc oxides 2.1.6 MZO as a substrate for GaN devices 2.2 Potential for p-type oxide semiconductors 2.3 Assessment of oxide TFT development programs at leading firms 2.4.1 AUO 2.4.2 CBRITE 2.4.3 HP 2.4.4 LG 2.4.5 Samsung 2.4.6 Sharp 2.4.7 Sony 2.4.8 Toppan 2.4.9 Toshiba 2.5 Evolution of fabrication technology for oxide TFTs 2.3 Key points from this chapter Chapter Three: Market Requirements and Opportunities for Oxide TFTs 3.1 What is the future role of oxide TFTs in the LCD market? 3.2 Oxide TFTs and OLEDs 3.2.1 PM OLEDs 3.2.2 Mobile displays 3.2.3 OLED TVs 3.3 E-paper 3.3.1 Electrophoretic displays 3.3.2 Other e-paper 3.4 Potential future markets for oxide TFTs 3.4.1 Flexible displays 3.4.2 Transparent electronics 3.4.3 Sensors and RFID 3.4.4 Power electronics


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3.4.5 Memory 3.6 Key points from this chapter Chapter Four: Eight-Year Forecasts for Oxide TFTs 4.1 Forecasting methodology 4.2 Forecast by material type 4.3 Forecast by application 4.4 Alternative scenarios


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Chapter One: Introduction 1.1 Background to this Report

Metal oxide thin-film transistors (TFTs) are poised to capture a very real revenue opportunity in Page | 4 the display industry. Amorphous metal oxide materials have the potential to be used in the backplane of flat-panel displays as an alternative to amorphous silicon (a-silicon), which is currently the industry standard. a-Silicon is limited in its performance as a backplane material, and its newer, high performance alternative, low temperature polysilicon (LTPS) is extremely expensive to produce. Metal oxide materials offer better performance than a-silicon, and are cheaper to manufacture than LTPS, which is in good alignment with the needs of the display industry going forward. The importance of addressing each picture element (each unit of which is called a pixel) in a flat-panel display containing well over a million pixels is a task that is accomplished by either a passive or active matrix in the backplane of the display. This act of addressing is what renders the image on the screen from the electronic input. LCD technology has dominated the market in the recent past in high-resolution, fast-refreshing large display applications such as laptops and TVs. The addressing of pixels in LCDs has typically been achieved using what is known as an “active matrix” of thin-film transistors fabricated, most commonly, out of amorphous silicon (asilicon). It has, however, been known for some time now that a-silicon isn’t the ideal material for thinfilm transistor (TFT) backplanes. Even so, they have met the requirements of the display industry that is currently dominated by LCD technology. But LCD display makers have come to the realization that a-silicon is really a stagnant technology. It has reached the upper limits of process and morphological improvement that engineering of the production processes can provide, and is now really limited by the properties of a-silicon itself. Displays for the next decade are either going to be LCD-based or organic light emitting diode (OLED)-based for the most part. Next-generation LCD displays are not going to have their performance needs satisfied by a-silicon; it quite simply doesn’t have the potential to meet the improved resolution requirements, higher refresh rates, and lower power goals of nextgeneration LCD displays. It is also incapable of satisfying the requirements of large-area OLED displays. It will eventually come to the point where a-silicon will potentially become a limiting factor with regard to improving the performance of next-generation displays unless a novel backplane NanoMarkets, LC | PO Box 3840 | Glen Allen, VA 23058 | TEL: 804-270-1718 | FAX: 804-360-7259

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material is introduced. NanoMarkets believes that there is room for a technological improvement at a fundamental level. Hence, there is a very real revenue opportunity for companies seeking to bring newer backplane technologies to the market. Amorphous transparent metal oxide-based TFTs have the requisite materials properties to Page | 5 satisfy the needs of next-generation displays, as will be evidenced later in this report. It’s very realistic that metal oxide TFTs will, in fact, be a suitable replacement for a-silicon. There are some obstacles that need to be overcome with regard to device stability in large area and large volume production, but the development of these materials is being backed in a large way by multiple companies. The display industry is rapidly expanding with regard to the number of consumer electronics devices on the market. The tablet and smartphone segments have added a new dimension to the market, allowing OLED displays to make an entrance in smaller area applications (they have, until very recently, been found unsuitable for large-area displays). There are also flexible displays in the works at a few companies, as well as electrophoretic ink-based displays that have been present in the market for some time now. This suite of commercialized devices allows for a targeted segmentation approach by a new technology entering the market. Certain companies are pioneering metal oxide TFTs for largearea LCD and OLED display applications, while others are planning on targeting the tablet display market. Strategies behind these decisions revolve around production capability, the substrate area capable of being handled by the manufacturing facilities, and where companies believe they can see the highest revenue opportunity for their amorphous oxide backplanes. Segmentation in a relatively mature market is essential in meeting customer demands and positioning the product so as to maximize revenue. New, high growth segments (smartphones, tablets, notebooks) in the consumer electronics device market have led to a large increase in the potential revenue to be captured by display makers. With these high-growth segments, however, comes increased consumer expectations from the point of view of visual quality and performance in displays, and the need to meet these expectations is why bringing new technology to the market is crucial. NanoMarkets believes that the industry is on the brink of an overhaul with regard to its backplane technology. It is not really a question of IF a-silicon will be replaced, but rather, WHEN. At its present stage of development, amorphous metal oxide backplane technology, with the properties it displays from a performance point of view, is the most realistic replacement.


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1.1.1 The Silicon Landscape

a-Silicon has, for a long time, been the material of choice for use in the transistors in backplanes in the display market. There are various reasons why, but it is also readily apparent that there is room for improvement, and changes in the morphology of silicon itself have led to performance improvements that could prove to usurp a-silicon. The base material is still silicon however, and Page | 6 it appears that silicon has really made itself indivisible from the backplane transistor. a-Silicon provides adequate performance for large-scale display applications in terms of its electronic performance. The key word in the above sentence is adequate, but it definitely has limitations: 

The mobility of amorphous silicon is a few orders of magnitude less than that of crystalline silicon, but yet it has managed to become the material of choice for the active matrix of thin-film transistors in displays.

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The low mobility of a-silicon, a fundamental materials property, is coupled with a loss of real estate on the backplane, because the size of each transistor is forced to be relatively large, leading to a larger pixel, and hence lower screen resolution.

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a-Silicon requires an external driver circuit to manipulate the transistors at each pixel, and this driving circuit can’t be made out of a-silicon due to its low mobility. The external circuit is an added production step, and is a potential target for cost savings if it can be incorporated into the TFT active matrix fabrication process.

a-Silicon is still favored because of its low temperature, relatively inexpensive production process compared to better-performing materials. Additionally, the production process allows for relatively simple scalability to large areas, which has led to the general adoption of a-silicon in large-area electronics applications. An important question is whether a-silicon has the potential to continue its dominance in these applications. It beats competitors on cost, but one wonders when the value of added performance will prove itself worth the additional cost for switching materials. Development efforts have been specifically targeted at low temperature poly-silicon (LTPS) as a thin-film transistor material for displays. Its benefits include:    

A significantly higher mobility than a-silicon; Smaller grain sizes, leading to smaller transistors, smaller pixels and higher resolution; The ability to integrate driver circuits onto the glass substrate, significantly reducing the number of connections on the substrate and improving durability; and Lower power consumption than a-silicon.


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LTPS does have certain problems, though. It is usually manufactured by a process that depends on laser annealing, which is an expensive fabrication method with questionable scalability compared to the relatively standard lithographic manufacturing of a-silicon. This issue is a strong inhibitor to the adoption of poly-silicon in large-area display applications, and so far this Page | 7 technology has made limited inroads, and mostly in devices with small displays. Small display applications have grown strongly as a revenue stream with the advent of smartphones and tablets. And this market segment has actually made it possible for higherperforming materials like poly-silicon to see applicability in the market. At the very least, small area displays provide an avenue for market entry while development efforts continue to address the scalability of the production process for large-area displays. The recent advances in OLED displays have also spurred the development of LTPS for display applications. LTPS has the potential to really push the large scale adoption of OLED devices, the highest volumes of which are used in small area displays. The competitive landscape between OLED and LCD displays over the forecast period could lead to interesting backlashes in the backplane sector as well. Currently, OLEDs have not been able to penetrate the large-area display market, primarily due to high production costs. However, organic displays are experiencing extremely rapid increases in adoption in the smartphone market. The emerging adoption of LTPS in response to superior performance demands in the small area display segment could lead to the displacement of a-silicon as the dominant force in smaller device backplanes. LCDs currently dominate the large-area display market, and a-silicon is the industry standard backplane technology in this segment. It is cheap and its performance meets the device requirements, but how long will this last? Going one step further than that, in an application entirely dominated by variations on silicon thin films, is there room for revolutionary material substitutes to squeeze out a position in the short term, and perhaps expand it to a reasonable market share in the long run? This report aims to shed some light on the answer to that question, specifically with regard to the potential of thin-film metal oxides in this market. 1.1.2 Metal Oxide TFTs and How They Fit In

The fact is that metal oxide thin-film transistors have the very real potential to be a disruptive technology in this market. This potential stems from the fact that they, in a sense, combine the best of both the a-silicon and LTPS worlds. They offer: NanoMarkets, LC | PO Box 3840 | Glen Allen, VA 23058 | TEL: 804-270-1718 | FAX: 804-360-7259

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

A mobility higher than a-silicon, though lower than LTPS;

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Low temperature fabrication, coupled with the potential for relatively cheap large scale production, which LTPS does not offer (yet);

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Smaller pixel sizes than a-silicon, and hence higher resolution displays; and

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A larger aperture ratio compared to a-silicon per pixel, allowing for higher transmission through the backplane. This feature could be used to reduce the power of the backlight, or to increase brightness as per the device requirements.

Metal oxide thin films are potentially a competitive force to be reckoned with in this space, and have garnered the commercial interests of multiple companies looking to capitalize on these advantages. These firms will be elaborated on more in the following chapters in this report, but big names in the display space such as Sharp, as well as smaller companies like CBrite Inc., are hoping to really capitalize on the potential of thin-film metal oxide transistors to gain traction in the display market. Metal oxides have the potential to simultaneously impact both large and small area displays, and offer a cost effective replacement for a-silicon. Improvements in fabrication processes and the shift to truly large volume manufacturing will lower costs for metal oxides, easing their entry into the laptop and television market. Companies like Sharp and LG Display are already pushing metal oxide TFT backplanes for largearea applications, and the relative simplicity and scalability of the production process for metal oxide TFTs is a strong enabling factor for the technology. Oxide TFT technology is largely compatible with existing production lines in use for LCD displays, reducing the capital expenditure for panel makers. The production of large-scale OLED displays will allow companies to leverage this factor, since they can modify existing LCD production lines for the shift to oxide TFTs. Large scale OLED displays are going into production soon, and oxide TFTs will be a very important factor in ensuring that they are cost-competitive with LCD displays. The production of large-scale active matrix OLEDs (AMOLEDs) and oxide TFTs will go hand-in-hand as they push forth into the large-area display marketplace. Metal oxides will offer strong competition to LTPS, since both of these materials are ideally suited for OLED displays. The explosive growth of the smartphone and tablet markets using NanoMarkets, LC | PO Box 3840 | Glen Allen, VA 23058 | TEL: 804-270-1718 | FAX: 804-360-7259

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active matrix OLEDs is the market driver most strongly pushing the development and commercialization of these materials in this market segment. The high resolution and increased transmission through the backplane of both of these technologies are key requirements for small area displays. From purely a performance point of view, LTPS actually is superior to metal oxide TFTs at their current state-of-the-art. However the high costs associated with LTPS might prove to be a technology killer going forward. This high-cost position of LTPS will allow metal oxide TFTs to be used in a significant portion of the applications that LTPS would have been attempting to capture going forward. So while LTPS may have the edge in the near term, metal oxide TFTs could really pose a serious threat to its continued use. The focus paid to silicon so far in this report is intended to provide a view of the competitive landscape that metal oxide TFTs face as they enter the market. The devices they are used in (and hence display size) will end up segmenting the market for metal oxide TFTs in a way that allows the technology to leverage its strengths. The market has effectively done the same thing for silicon, with a-silicon dominating the largearea display formats, and LTPS making an impact in smaller area displays and emerging OLED displays. Metal oxide TFTs will need to position themselves slightly differently in each of these markets, and do offer the potential for capturing significant revenue from each segment. The success of metal oxide TFTs coming off of high volume production lines is yet to be evaluated. Performance and quality control in manufacturing situations can be challenging in a material that inherently has been shown to have inferior electrical stability (with regard to the transistor threshold voltage) than a-silicon. The most important questions that will affect the adoption of metal oxide TFTs as their output is increased over the next one to three years: 

Cost effectiveness of the production process. Will the expected minimal overhaul of the existing LCD backplane production lines be a low capital expenditure move while still providing high product quality?

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What is the true lifetime of the metal oxide backplane, and will electrical stability prove to be a problem with use?

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Can the uniformity of the metal oxide thin film be improved and made comparable to asilicon, particularly in large scale displays? What are the scalability limits of the film?


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Metal oxide TFTs should really be aiming at becoming the industry standard technology for display backplanes over the next decade. In the current industry environment, the technologies competing with metal oxide TFTs are really LTPS, from the point of view of performance, and asilicon, simply because it is the current industry standard; there are no other emerging technologies on the horizon that are far enough along in their development at this point to Page | 10 really present a challenge to metal oxides. Additionally, LTPS is expensive for large-area manufacturing, and this fact is a prime example of where performance alone doesn’t guarantee success in the marketplace. Metal oxide TFTs are much better-suited to the industry needs from the overall point of view of cost, performance, manufacturability, and scalability. 1.2 Objectives and Scope of this Report

The objective of this report is to highlight the business revenue opportunities for metal oxide TFT backplane materials in the various market segments of the display industry. This goal is achieved through an analysis of the evolution of the display market and its expected future directions. With regard to forecasting, more attention has been paid to the opportunities for the metal oxide films that are likely to see commercialization over the course of this forecast period, such as indium gallium zinc oxide (IGZO). The range of possible material compositions available to fabricate transparent metal oxide thin films is vast, and hence the ones that are being focused on actively by companies in the industry are similarly highlighted here. The other oxide materials that might have a role to play in the industry further on down the road have been mentioned. These include aluminum zinc oxide, indium zinc oxide, zinc tin oxide, hafnium indium zinc oxide and p-type amorphous oxides. However, their role as backplane materials is not strongly emphasized from a commercial point of view by the display industry, and they have been treated as such here. The value propositions of the amorphous metal oxides discussed in this report are then analyzed from the point of view of the needs of the display market, and their potential for generating revenue is discussed. This report also provides detailed market forecasts for metal oxide TFT backplanes in the display industry. The market forecasts will be presented by the main types of backplane materials, as well as by the key market segments that metal oxide TFT backplanes will cater to. The forecasts will consist of annual revenue figures for panels using these materials, as well as the area of NanoMarkets, LC | PO Box 3840 | Glen Allen, VA 23058 | TEL: 804-270-1718 | FAX: 804-360-7259

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backplane material used, over an eight-year period. The numbers have been arrived at based on analyzing the state of the display industry and the various competitive forces at play within it. In addition, this report is international in scope. We have not been geographically selective in Page | 11 the firms covered or interviewed for the purposes of compiling this report. 1.3 Methodology of this Report

The information for this report is derived from a variety of sources, primarily from NanoMarkets’ interview program of technologists, business development managers and academics associated with this field. An extensive search of the technical literature and relevant company Web sites was also conducted. Additionally, previous reports from NanoMarkets that bear relevance to the subject have been consulted, including the following: Markets for OLED Materials–2011, Emerging Markets for Non-ITO Transparent Conductive Oxides–2011, and Zinc Oxide Markets 2010 and Beyond. The forecasting method used in this report is explained in detail in Chapter Four, but the fundamental approach is to identify the key driving forces for the adoption of metal oxide technology over the course of the forecasting period, and use these drivers as the basis for our predictions. The driving forces within each display application are then evaluated to judge the level of market penetration that metal oxide TFTs are likely to achieve in the various segments in the display space. 1.4 Plan of this Report

Chapter Two will discuss the present technology roadmap for metal oxide TFTs, as well as provide an assessment of the developmental progress of this technology at various firms. Chapter Three will then go on to investigate the market requirements that are expected to drive the adoption of oxide TFTs, and how these requirements will translate to revenue opportunities. Finally, Chapter Four will go over our eight-year forecasts for metal oxide TFTs, both from the point of view of the material type, as well as the applications that present themselves.
