By Dr. Chris Moore & Winthrop Baylies, BayTech-Resor LLC
When you say the word sapphire most people think of a brilliant blue gemstone. The members that have formed the Tablet Working Group think of sapphire as a key enabler of future growth for their respective businesses. This article discusses the rationale for forming SEMI’s Tablet Working Group and the action plan moving forward.
At SEMICON West 2014 a presentation  to the HBLED technical committee summarized the information available on the expected impact of sapphire on both the Tablet and Smartphone market. It was decided to form a small working group of material suppliers and other interested parties to investigate this area. The mandate of the Tablet Working Group is to determine the needs for standards as they would apply to the eclectic group of manufacturers and service companies that form SEMI. During this discussion it was decided that the group should include not only the use of sapphire in these devices but glass as well. This article will focus on why sapphire and why this effort is starting now.
To put this in perspective the Tablet Working Group is interested in the rectangular pieces of sapphire or glass used as either the cover material (camera lens cover/TP cover) or basic screen of touch devices for tablets and smartphones. Figure 1 shows multiple sapphire cover components for mobile device from Chitwing – Silian optoelectronics. Figure 1 shows sapphire components without ink and coating and sapphire components with ink and AR/AF coating.
The Tablet Working Group’s interest encompasses the whole supply chain from the initial starting materials though the growth of boules (which may be rectangular) or sheets, shaping of the boule/sheet, slicing, dimensioning and polishing of the surfaces, applying the necessary anti-reflection (AR) or oleo phobic (Anti-fingerprint , AF) coating which creates the screen or cover glass. Figure 2 contains a more detailed illustration of this supply chain.
The reasons for looking at this area now are clear. As you may (may not) know there has been considerable interest and a number of articles [2,3] published on the large sapphire growth facility purported to be related to Apple in Mesa Arizona. Depending on the analyst it is believed that the original facility (there is talk of an expansion) contains 2500 furnaces. These boules are shipped overseas to be sliced, dimensioned and polished. The analysts expect that this material will be used in the next generation of iPhone. This is definitely a large investment in the future and represents a significant jump in the predicted use of sapphire material over the next few years.
Given the cost of production (which is expected to be higher than for the equivalent glass unit ) the question becomes: why use sapphire in a mainline consumer product? The first answer is hardness and mechanical strength. Sapphire has been used for many years in higher-end watch products because it resists scratching and is extremely durable. Videos on the net show sheets of sapphire being rubbed by concrete blocks  with no effect. As part of the mechanical strength it is also predicted that sapphire units will be thinner than their glass equivalents enabling even thinner device designs.
The second reason is more obscure and yet in many ways more important than the first and is a result of sapphire’s optical and electrical properties. It has been reported that touch / camera lens cover screens and sensors made from sapphire are more durable and reliable in its function. Since all of the devices discussed here are by their nature touch screen-driven this becomes a significant factor in final device performance.
With this background we can start explaining why the interest by some SEMI members to examine this manufacturing area. SEMI itself is a collaborative of material suppliers, production equipment manufacturers, metrology system makers, automation suppliers, device producers and service support companies. Given the level of investment predicted for sapphire in the Tablet/Smart phone area one can see that all of these areas will be affected. At least one furnace manufacturer has pinned a large portion of their company’s future on the sapphire industry and it is expected that others will follow. Thus the equipment producers are already moving down this path with significant investment in both equipment and process development. As usual at this stage of development in a new market segment there are very few standards that exist for both the material and its testing. More important, since there is no standard guidance, the end user has less information on how to define sapphire product specification. This non-standard fabrication from material to final product would cost more than standard process.
The Apple business model for sapphire production is highly vertically oriented. However, it is expected that many of the other suppliers of Tablets and Smart phones will contract out the growth and manufacturing of their cover/screen needs resulting in a significant growth market. Although some analysts predict the eventual displacement of glass from this area in all but the lowest-end tablet and smart phone products, many still look at the economic factors which favor glass. However, it is clear that the economics of sapphire screens will be greatly affected by the scale of production now being envisioned.
Thus we have a potentially large sapphire market which is currently in its early growth stage. SEMI and its Standards groups have effectively participated many times in markets of this type including flat panel displays, photo-voltaic devices, and the emerging work of the HBLED committee.
One of the questions asked is why this work would be under the auspices of the HBLED Technical Committee. The original presentation  was discussed as part of the HBLED Substrate Taskforce which is the group responsible for generating the first standards  for the sapphire wafers used in the HBLED manufacturing process. Since the group has an interest in sapphire the initial thoughts were that this area could be looked at as developing standards for “substrates” which are now rectangular as opposed to round.
As the presentation was discussed in the technical committee meeting it was clear that the definition of the “substrate” was only part of the potential work to be done. Thus it was decided to form a working group to look at the potential for standards work in the Tablet/Smart phone area. It was also clear that SEMI expertise in materials, automation and metrology standards filled a niche not being addressed by the IEC standards group. At no point did any of the volunteers present want to take on work that was already being done or outside the normal area SEMI would cover. The discussion also highlighted work other than standards which may be of benefit for SEMI but this is beyond the scope of the working group.
The Tablet Working Group will hold its first phone conference in September. Current working group members include material suppliers like Silian ( a pioneer in sapphire) and Corning, metrology suppliers and other interested parties. The first face to face meeting will be at the fall Standards meeting in San Jose. If you have interest in joining the group please contact Michael Tran of SEMI staff or Chris Moore at email@example.com or Win Baylies at Win.Baylies @ BayTech-Resor.com.
 Tablet Substrates SEMI Standards Presentation https://sites.google.com/a/semi.org/hbled/hb-led-wafer-tf/july-10-2014
 Analyst article on Apple/Mesa AZ http://seekingalpha.com/article/2167493-gt-advanceds-sapphire-operations-in-arizona-are-likely-fully-ramped-and-ready-to-deliver-the-goods-to-apple?isDirectRoadblock=false&app=1&uprof=45
 Analyst article on Sapphire Composite Cover Screens for Mobile Devices and Point-of-Sale Scanners http://seekingalpha.com/article/2235313-gt-advanced-technologies-next-frontier-sapphire-composite-cover-screens-for-mobile-devices-and-point-of-sale-scanners?app=1&uprof=45
 Analyst article on Glass Demand for Higher-Generation Glass Substrates will Drive Corning’s Display Volume – http://seekingalpha.com/article/2230553-ignore-the-sapphire-threat-corning-is-on-a-roll
 Internet video Aero Gear’s Flight Glass SX Sapphire Crystal vs a Concrete …
 SEMI HB-LED standards (www.SEMI.org/standards)
HB-1-0814 Specification for Sapphire Wafers for Use for Manufacturing High-Brightness Light Emitting Diode Devices
HB-2-0613 Specification for 150 mm Open Plastic and Metal Wafer Cassettes Intended for Use for Manufacturing HB-LED Devices
HB-3 -1113 Mechanical Interface for 150 mm HB-LED Load Port
HB-4-0913 Specification of Communication Interfaces for High Brightness LED Manufacturing Equipment (HB-LED ECI)