Substrate Update: It’s All About Patterning & Large Diameter Wafers

yole_developpement_logoMarket research firm Yole Developpement recently published a new report on front-end manufacturing trends for LEDs. Their latest report gives us some very good news about the sapphire market. Semiconductor Today reported on Yole’s analysis. Here are some big take-aways:

  • There is increased demand for larger-diameter sapphire wafers, with big players (such as LG, Sharp or Osram) moving to 6” wafers and Taiwanese players moving to 4” wafers.
  • LED chip makers demand more patterned sapphire substrates (PSS). PSS are now mainstream in the market with an 87% share as of Q1 2014.
  • While some companies (such as Soraa and Toshiba) have begun mass production of gallium nitride-on-silicon (GaN-on-Si) and GaN-on-GaN LEDs, market penetration of these alternative substrates will depend on future improvements in terms of performance and cost.  Without these improvements, alternative substrates will not be able to fully compete with sapphire-based LEDs.

What does this mean for sapphire makers? LED chip manufacturers are looking to gain production efficiencies, lower costs, and increase performance for their LEDs.  As the adoption for LED lighting increases, they need to make more and better performing LEDs. Large diameter sapphire wafers enable more throughput for each run of the MOCVD reactor, making better use of the reactor “real estate” and decreasing the cost per unit of area processed. Depending on the type of MOCVD reactor used, LED chip manufacturers using six-inch wafer platforms may achieve up to 48% greater usable area per reactor run as compared to two-inch wafers.

What does PSS offer? First, PSS helps improve epitaxial growth by promoting growth of the GaN in parallel to the substrate surface. This helps reduce the number of dislocations, called the dislocation density, which can degrade performance of an LED.  Secondly, patterning can help extract as much as 30 percent more light from an LED.  This is particularly advantageous for high brightness LEDs (HB LEDs) that are used in LED lighting applications.

LED chip manufacturers have been buying smaller 2-inch and 4-inch PSS from outside suppliers for years.  The next step in the evolution in the market is the migration to large diameter PSS. Already a pioneer in the development of large diameter sapphire substrates, Rubicon Technology has developed capabilities for large diameter PSS making it possible to manufacture 6-inch and even 8-inch PSS. Rubicon is already gaining traction in the PSS market.  The company recently reported in their Q1 2014 earnings call that they received their first order for PSS and have samples out to more than a dozen LED chip manufacturers.

For more information about the report from Yole, visit http://www.i-micronews.com/reports/LED-Front-End-Manufacturing-Trends-report/14/433

For Further Reading

Semiconductor Today, Substrates shaping trends in LED front-end manufacturing, http://www.semiconductor-today.com/news_items/2014/APR/YOLE_300414.shtml

Clearlysapphire.com, Larger Wafers, Larger Yield – The Numbers Behind Large Diameter Sapphire Wafers and Yield, http://blog.clearlysapphire.com/?p=435

Clearlysapphire.com, Large Diameter Patterned Sapphire Substrates Explained, http://blog.clearlysapphire.com/?p=582

Clearlysapphire.com, Sapphire Substrates for LED: The Big Move Toward 6″ Has Already Started, http://blog.clearlysapphire.com/?p=37

Rubicon Announces Large Diameter Patterned Sapphire Substrates

PSS with dome shape

PSS with dome shape

 

This week, Rubicon Technology announced the launch of the first commercial line of large diameter patterned sapphire substrates (PSS) in four-inch through eight-inch diameters.  The new product line provides LED chip manufacturers with a ready-made source of large diameter PSS to serve the needs of the rapidly growing LED general lighting industry.

This is doubly important since patterning helps improve both epitaxial growth and light extraction for each chip and enhances a chipmaker’s throughput and efficiency.  Rubicon announced that they have fully customizable sub-micron patterning capability with tight dimensional tolerances, within ±0.1 µm.  Rubicon offers LED chip manufacturers more usable area to maximize the number of chips per wafer due to an edge exclusion zone as small as 1 mm.  Rubicon’s patterning is available in a range of shapes including cone, dome and pyramid, and in a range of orientations.  Further customization of geometry, pattern and orientation is available too.  You can find a brochure about it on Rubicon’s web site here.

Rubicon’s president and CEO Raja Parvez pointed out the importance of large diameter patterned sapphire substrates in a news release.  “As LED-based general lighting gains worldwide adoption, large-diameter patterned sapphire substrates will become necessary to meet the demands of the rapidly growing lighting market.”

Parvez added that the company developed an unmatched technology platform that is vertically integrated from raw material through crystal growth, large diameter polished wafers, and now custom PSS in 4”, 6” and 8” diameters.  According to Parvez, vertical integration enables Rubicon to produce progressively larger sapphire products while providing customers with exceptional quality, cost control, reliability, and consistency.

For Further Reading

Rubicon Technology, Rubicon Technology Launches First Commercial Line of Large Diameter Patterned Sapphire Substrates for the LED Industry, http://bit.ly/1itVMHq

Clearlysapphire.com, LED Lighting Spotlight: Patterned Sapphire Substrates, http://blog.clearlysapphire.com/?p=390

 

Alternative Substrates – Dimming the Hype

Two-inch, Four-inch and Six-inch Sapphire Wafers

Two-inch, Four-inch and Six-inch Sapphire Wafers

Today, more than 80% of LEDs are made based on sapphire wafers.   Recently, Lux Research published a report, Dimming the Hype: GaN-on-Si Fails to Outshine Sapphire by 2020, about the state of alternative substrates.  In LED production, sapphire is used as the substrate onto which the chemicals that will become the emitting layer of the LED are deposited as a vapor.  With the LED lighting market expected to grow to $80 billion, Lux Research expects the substrate market to grow to $4 billion in 2020 making it a highly attractive market.  Lux expects sapphire to continue to dominate the substrate market.

“Silicon is already widely used for electronics, and some LED die manufacturers are hoping to take advantage of silicon substrates,” said Pallavi Madakasira, Lux Research Analyst and lead author of the Lux report.  She explained that GaN-on-Si presents technical challenges such as cracking and a lattice mismatch that reduces the performance of LEDs based on the alternative substrate.

In an interview with Compound Semiconductor, Madakasira spoke about LEDs based on silicon substrates.  She doesn’t buy the argument that GaN-on-silicon makers can save on costs.  She says that even if they use fully depreciated CMOS equipment, the process of depositing complex buffer layers onto silicon prior to GaN deposition to overcome GaN and silicon lattice mismatches, adds time and cost to a manufacturing line.

Madakasira also shared performance data in her report with Compound Semiconductor. She notes that alternative substrates haven’t provided the performance of sapphire.  According to Lux, the luminance efficacy of GaN-on-SiC LEDs is 200 Lumens per Watt with GaN-on-sapphire devices coming in at between 150 to 180 Lumens per Watt.

What does this mean?  The Lux report concluded that sapphire will remain highly competitive for the rest of the decade.  GaN-on-silicon, will snare only 10% market share while GaN-on-silicon carbide will grow to 18% of the market.   Where do they fit? Here are Lux’s conclusions:

  • Choice and cost of LEDs will determine adoption. Where GaN-on-sapphire is suited to all applications, GaN-on-bulk GaN will be relegated to niche commercial lighting and GaN-on-Si, with unproven performance, will be better suited to cost-sensitive residential applications.
  • Four-inch wafers will rule (for now), though six-inch wafers start to come into vogue. Four-inch wafers will peak at 62% market share with $2.1 billion in 2017 sales. Later, the LED industry will move towards 6” epiwafers, which will take a 35% share, equivalent to $1.4 billion, in 2020.
  • Technology will advance sapphire substrates. Sapphire substrate manufacturing technology has advanced significantly with specialists such as Rubicon and Monocrystal demonstrating substrates up to 12” in diameter. New methods like hydride vapor phase epitaxy (HVPE) will further improve throughput and cut costs, keeping sapphire highly competitive for the rest of the decade.

For Further Reading

Lux Research, Epi-Wafer Market to Grow to $4 Billion in 2020 as LED Lighting Zooms to $80 Billion, http://www.luxresearchinc.com/news-and-events/press-releases/182.html

Compound Semiconductor, Sapphire Substrates to Lead Future LED Markets, http://www.compoundsemiconductor.net/csc/indepth-details/19736669/Sapphire-substrates-to-lead-future-LED-market.html

Larger Wafers, Larger Yield – The Numbers Behind Large Diameter Sapphire Wafers and Yield

rubicon-waferyield-540x720-3Today, more than 80% of LEDs are based on sapphire substrates. For years, two-inch and four-inch diameter sapphire wafers have been the standard for LED production.  Now, LED chip manufacturers are looking to migrate to six-inch diameter wafers to increase the yield or the amount of LED chips they can make out of each wafer.  This is important as new market opportunities like LED-based general lighting take off, demanding more sapphire.

Rubicon put together an infographic, Larger Wafer, Larger Yield, about the yield from large diameter wafers. You can see it here on Rubicon’s new web site:  http://www.rubicontechnology.com/sites/default/files/Rubicon_WaferYield_v3.pdf

Rubicon Technology’s CEO Raja Parvez talked about the benefits of moving to large diameter sapphire wafers in an article, Vertical Integration Streamlines Sapphire Production, in Compound Semiconductor earlier this year.

According to Parvez, LED chip manufacturers look to large diameter sapphire wafers to cut costs.  Large diameter sapphire wafers enable more throughput for each run of the MOCVD reactor, making better use of the reactor “real estate” and decreasing the cost per unit of area processed.  The outer curvature of the 6 inch wafer is less, enabling greater use of the surface area than a 2 inch wafer resulting in less edge loss. In addition, large wafers provide post-MOCVD efficiencies.  Depending on the type of MOCVD reactor used, LED chip manufacturers using six-inch wafer platforms may achieve up to 48% greater usable area per reactor run compared with two-inch wafers.  These efficiency gains become very compelling when LED chip production ramps up in large volumes to support a high growth market like general lighting.

For Further Reading

Compound Semiconductor, Vertical Integration Streamlines Sapphire Production http://www.compoundsemiconductor.net/csc/features-details.php?cat=features&id=19736275&key=rubicon%20technology&type=

Opportunities for Sapphire: New Applications & Markets Explained

Rubicon Technology announced the publication of Opportunities for Sapphire, a new white paper that examines markets that leverage the highly versatile material, sapphire.  Based on research from IMS Research, the paper takes an in-depth look at the demand for sapphire in key markets including LED, semiconductor and optical.  You can find the white paper on Rubicon’s new web site at http://rubicontechnology.com/resources/papers, but here’s a look at what you’ll find.

Sapphire has emerged as a versatile material in a range of industries for many varied applications.  Sapphire’s inherent physical attributes for durability, light transmission, chemical inertness and thermal insulation make it desirable for a growing list of applications in a range of markets.  The white paper examines the opportunity for the LED market in general lighting, backlighting and display and uses in industries like automotive.  It also explores sapphire applications for optical-grade sapphire windows, lenses and covers as well as semiconductor applications such as silicon-on-sapphire chips in radio frequency integrated circuits (RFICs) for RF antennas, as digitally tunable capacitors (DTCs) and power amplifiers in smart phones and other consumer devices.

According to white paper author Jamie Fox of IMS Research, high quality sapphire delivers great benefits to LED chip manufacturers gearing up for applications like LED-based general lighting.  “Every LED company we spoke to during the research for this paper purchases sapphire and benefits from the superior yields and quality,” writes Fox.  “Substrate demand in 2012 is estimated at 42 million two-inch equivalent wafers (TIE) and expected to grow to 57 million TIE in 2013 according to market research firm Displaybank.  As the lighting market grows into a more significant segment and larger, thicker wafers are utilized, sapphire demand will accelerate.”

“Opportunities for Sapphire” also discusses the role of sapphire in LED production, the emergence of the market for large diameter sapphire wafers and sapphire demand by application.

LED Sapphire Ingot Demand Forecast

LED Sapphire Demand Graphic WPPR

(source: DisplayBank)

 

 

 

 

 

 

 

The market has shown growing demand since 2010 with an expansion of the LED/LCD TV market and the growth of applications such as general lighting.

Green line indicates rate of growth per year

Key:  Demand in thousands of millimeters of two-inch equivalent sapphire

Alternative Substrates for LEDs – Not Ready for Prime Time

Over the past several months, there has been some industry chatter about alternative substrates for the production of LEDs.  In fact, the dialog has been more heat than light until now if you think about it in terms of a filament in an incandescent light bulb.

Large Diameter Sapphire Wafer (source: Rubicon Technology)

Sapphire substrates have been established for quite some time as the base material for LED chips.  Today, more than 80% of LEDs are based on sapphire substrates with the remainder based on SiC and a few other materials.  But the big question is whether an alternative substrate like silicon or GaN can offer the performance and cost advantages of sapphire.

Last week, market research firm Yole Developpement held a webcast, Alternative Substrates for LED Manufacturing, to examine the alternatives, the technical challenges and the conditions for success.  You can access the archive here.

According to Yole analyst Eric Virey, the principal benefit of using Si as an LED substrate would be the ability to leverage larger 8” wafers and use fully depreciated and highly automated CMOS fabs.  But “the jury is still out,” he said, “regarding a massive industry transition from sapphire to silicon.  At the end of the day, this is a cost game; manufacturing yields are a major cost contributor to LED, and they pose specific challenges to the use of silicon.”

These challenges range from a lattice mismatch and thermal expansion coefficient mismatch, to melt back and blue light absorption. Sapphire outperforms silicon on all of these factors, and each is having a negative impact on LED chip yields from silicon.  Virey commented silicon and/or GaN must meet the performance of sapphire to be successful. To date, that hasn’t happened.

In the meantime, the sapphire substrate manufacturers have made great strides to making large diameter substrates that help LED manufacturers drive down costs and increase yields to support the aggressive cost targets of SSL.  For example, Rubicon Technology has shipped more than 230,000 large diameter sapphire wafers with this number growing.

Where are efforts now? Virey mentioned during the webinar that almost all LED manufacturers are exploring alternative substrates, although most are doing so only as a defensive strategy. Toshiba and Bridgelux have been working with silicon as a substrate. In July, the companies announced Toshiba would begin silicon-based LED production in October 2012, but there has been no further word. Plessey Semiconductors and Lattice Power also announced they would enter production in 2012.

LED Magazine reports that silicon-based substrates are “no sure thing” in their latest SSL Technology Update video blog.  Associate editor Nicole Pelletier said, “A number of companies plan to ride the incumbent sapphire technology. At The LED Show back in August, LED market leader Nichia said it had investigated and dismissed the possibility of using silicon.”

At the conclusion of the webcast, Virey agreed.  “If the technology hurdles are cleared, LED on silicon will be adopted by some LED manufacturers, but not necessarily become the standard.”

For Further Reading

LED Magazine, SSL Technology Update: October 22, 2012, http://ledsmagazine.com/features/9/10/11

Yole Developpement Webinar, Alternative Substrates for LED Manufacturing, http://www.i-micronews.com/consult_webcast.asp?uid=97

Solid State Technology, Beyond sapphire: LED substrates from GaN to ZnO, SiC, and Si, http://www.electroiq.com/articles/sst/2012/05/beyond-sapphire-led-substrates-gan-zno-sic-si.html

Solid State Technology, The demise of sapphire wafers? http://www.electroiq.com/articles/sst/print/vol-55/issue-6/columns/leds/the-demise-of-sapphire-wafers.html

Barriers to Entry 2: Yole Developpement Talks Sapphire, New Market Entrants Unlikely to Match Yields of Industry Leaders

In Part 2 in our Barriers to Entry posts (Part 1 is here), we’re focusing on a recent report from the industry experts at Yole Developpement.  Yole analysts have been keeping a keen eye on worldwide capacity for sapphire crystal growth.  According to Yole’s Eric Virey, more than 50 companies have announced their intention to enter the sapphire growth market, with more than 40 located in China.  While the capacity plans announced by all of the new companies collectively would add up to triple world demand, Yole believes it is “a situation unlikely to actually materialize.”

Why?  These new market players have little or no prior experience in sapphire crystal growth and wafer manufacturing.  And, while there are some “turn-key” solutions to lower the barrier to entry, “reaching and sustaining high quality and high yields in sapphire crystal growth still requires significant expertise.”  Indeed the learning curve is steep to reach yield levels on par with established Tier 1 manufacturers.

Yole’s report also said that margins in 2010 were favorable to new entrants allowing them to achieve comfortable margins “despite low yields and sub-par technology.”  However, with 2 inch pricing at historic lows, Yole calculates that they will lose money at the current market prices while “established vendors with higher yields, large volumes, and a more favorable product mix, including large-diameter wafers, can achieve production cost <$5 that will allow them to maintain positive margins and weather the storm.”

For Further Reading: Yole Developpement web site