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GaN-on-Silicon Substrate Patent Investigation

yole gan-on-si time evolution of patent app april 2014
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YOLE Gan on Si 2014More players on the playground, business is starting: when will the IP battle begin?


GaN-on-Si technology appeared naturally as an alternative to GaN-on-Sapphire—the main stream technology for LED applications. Today, despite potential cost benefits, the mass adoption of GaN-on-Si technology for LED applications remains unclear. Most major LED makers have a patenting activity related to GaN-on-Si technology, but so far, few have made it the core of their strategy and technology roadmap. Contrary to the LED industry, we expect GaN-on-Si to be widely adopted by Power Electronics and RF applications because of its lower cost and CMOS compatibility.

The growth of GaN-on-silicon substrate was first reported in the early-1970s (T. L. Chu et al., J. Electrochemical Society, Vol. 118, page 1200), since the early 1990s more and more academics and industrials have been involved in developing this technology. GaN-on-Si technology is now poised for a list of technical challenges. The high lattice mismatch between GaN and Si results in a high defect density in epitaxial layers (dislocations). The high thermal expansion coefficient (TCE) mismatch between GaN and Si leads to a large tensile stress during cooling from the growth temperature to room temperature. The tensile stress causes film cracking and a concave bending of the wafer (warpage). These factors combine to make both dislocation density and crack/warpage reduction a challenging task.

This patent investigation covers patents published worldwide up to December, 2013. The patents addressing the above mentioned challenges have been selected, and an in-depth analysis of patent holders and corresponding patented technologies is provided. This report does not include patents related to active layers or GaN-based devices.

Fundamental patents describing a gallium-nitride-based compound semiconductor grown on a silicon substrate were filed before the 1990s with the most significant assigned to TDK and Fujitsu. In the early 1990s, Toyoda Gosei and the University of Nagoya filed the first concepts of a buffer layer for improving the crystallinity of GaN. Those fundamental patents have been followed by an ever increasing number of applications since 1995 as more companies competed in GaN-on-Si technology to meet the technological challenges, the market demand and to lower manufacturing costs. Currently, the patented technologies reflect the significant improvements that have been made on key material issues such as dislocation density reduction and stress management for preventing cracks and warpage of the wafer. According to our analysis, GaN-on-Si IP is mature enough to initiate mass production.

Yole GaN-on-Si Time evolution April 2014


Our search strategy combines automated and manual screenings that have led to the selection of more than 560 relevant patent families. Those have been manually segmented by type (epitaxial layer, layer transfer) and organized in various technology segments that are analyzed in detail: defect reduction (ELOG, pendeoepitaxy, nanomasking, defect selective passivation …), stress management (AlN-based interlayer, buffer engineering, patterned substrate, compliant substrate…), and type of buffer (Al-containing single layer, compositionally graded AlGaN, superlattices…). For each segment, the report provides a detailed analysis including the time evolution of patent filings, identification of the key players and collaboration networks. More than 60 key patents have been identified based on several indicators (family size, legal status, citations analysis, and impact in GaN-on-Si technology…).

Yole GaN-on-Si Technology Breakdown April 2014

An excel database with all patents analyzed is also included with the report. This database allows multi-criteria searches and includes; patent publication number, hyperlinks to the original documents, priority date, title, abstract, patent assignees, technological segments, and legal status for each member of the patent family.


More than 50 companies and academics are involved in GaN-on-Si IP, and most of the major GaN players are present in the list of the top patent applicants. Toyoda Gosei, Toshiba, Panasonic, Mitsubishi, Nitronex, Soitec, and Azzurro have strong IP portfolios related to GaN-based epitaxial layers on Silicon. But Samsung, Dowa, LG, Sharp, and NGK Insulators are becoming major forces in the GaN-on-Si IP landscape. Soitec and Sumitomo lead patent filings related to GaN layer transfer on Si substrate.

The report provides a ranking and analysis of the relative strength of the top GaN-on-Si patent holders derived from their portfolio size, patent citations networks, countries of patent filings, and current legal status of patents. Based on this portfolio analysis, we have identified 15 major players that are profiled in this report. Each profile includes: a detailed portfolio summary with patenting activity, patented technologies, key patents, granted patents near expiration, partnerships, and IP strength and strategy.

Yole GaN-on-Si Time evolution of Patent app April 2014


Today, there are only a few players selling either epiwafers or templates - or both - on the open market. The number of commercial GaN-on-Si device makers is also limited. Apart from a few noticeable IP collaborations (Nitronex / International Rectifier, Toshiba / Bridgelux, Soitec / Sumitomo, Macom (Nitronex)/IQE), the GaN-on-Si IP has not yet been widely used by companies as leverage to negotiate licensing and supply agreements. So far, only a few litigations have been observed. However, the existing IP covers all subjects related to the technical challenges, and these last 5 years we have witnessed a reinforcement of critical patent filings by major GaN players (Toshiba, Samsung, LG, Sharp, NGK, Sumitomo, Soitec, Azzurro and Dowa). Furthermore, the GaN-on-Si industry is beginning to take shape as evidenced by the recent interest of the RF/Power industrials for the GaN-on-Si technology (Nitronex acquired by MACOM) and the will of several firms to move onto the production stage (Toshiba, Samsung …). Therefore, the IP battle should be expected in the next 3 years.

Table of contents

The authors 6
Scope of the report 7
Key features of the report 9
Objectives of the report 11
Terminologies for patent analysis 13
Methodology 15
Patent search strategy 17
Technological segmentation 18
Executive summary 19
GaN-on-Si technology overview 31
GaN on Si: technological challenges and known solutions 32
> GaN-on-Si: growth technique overview
> GaN on Si template & epiwafer: manufacturing steps
> GaN on Si epitaxy challenges: overview
> Si surface preparation
> Prevention of the melt-back etching
> Different types of buffer layers
> Crack and wafer bow due to TCE mismatch
> Stress managements
> Dislocation in GaN-on-Si system
> Dislocation reduction
>3D to 2D transition
> SiNx in situ masking for dislocation control

Si and GaN orientations 46

> Silicon substrate orientation
> GaN structure orientation
> Non-polar & semi-polar GaN: main interests
> Semi-polar and non-polar GaN on Si

GaN on Si engineered substrates 51

> Engineered substrate via Smart Cut™
> Engineered substrate players: Soitec (FR)
> Engineered substrate players: AmberWave Inc. (US)
> Engineered substrates: conclusion

GaN-on-Si patent investigation 59

Patent landscape overview 60
> Time evolution of patent publications (epitaxial layer & layer transfer)
> Country of patent filings (epitaxial layer & layer transfer)

Patent landscape overview: epitaxial Layers 62

> Time evolution by country of filing
> Current legal status of patents
> Main patent applicant ranking
> Time evolution of patent applicants
> Country of filing for patent applicants
> Summary of applicant’s patent portfolio
> Leadership of patent applicants
> Mapping of current IP holders
> Current legal status of patent portfolio
> Impact of patent portfolios
> IP Blocking potential of applicants
> Potential future plaintiffs
> Patent applicant IP network
> Main IP collaborations
> Main patent litigations

Patent landscape overview: layer transfer 82

> Time evolution by country of filing
> Current legal status of patents
> Main patent applicant ranking
> Time evolution of patent applicants
> Country of filing for patent applicants
> Patent applicant IP network
> Main IP collaborations

Analysis of technology segments 90
> Technology breakdown of patent filings
> Matrix applicants/technology segments
> Patent Differentiation for Defect/stress issues
> Current legal status of patents - Breakdown by technology segment

For all segments: overview, time evolution of patent publications, main patent applicants, time evolution of patent applicants, patent assignee ip network, granted patents near expiration, key patents: 

Buffer type (p96)

> Al-containing single layer
> Al-containing superlattices
> Others type of buffer
Defect reduction (p106)

> 3D-2D transition (ELOG, pendeoepitaxy,nanomasking, growth conditions)
> Buffer engineering
> Other techniques
Stress management (p123)

> Stress compensation layer (AlN-based interlayer, buffer engineering)
> Patterned substrate
> Compliant substrate
> Other techniques
Non-polar GaN (p137)
GaN on (001)-oriented Si (p141)

Summary of key players 145
For all of them: patenting activity, patented technologies, key patents, granted patents near expiration, partnerships, ip strength.
> Azzurro (p146), Dowa (p147), International Rectifier (p148), LG (p149), Mitsubishi (p150), NGK Insulators (p151), Nitronex (p152), Panasonic (p153), Samsung Electronics (p154), Sharp (p155), Soitec (p156), Sumitomo (p158), Toshiba (p159), Toyoda Gosei (p160), Toyota (p161)

Conclusion 162

GaN-on-Si market overview 165
> Comparison between different GaN-based technologies
> GaN-on-Si industry context
> Overview of the GaN-on-Si industry: from lighting to power electronics
> Possible competing technologies for GaN-on-Si
> LED qualified die surface: forecast by application
> GaN LED on Si penetration forecast
> GaN devices in power application: 2010-2020 market size, split by application
> GaN could reach 7% of the overall power device market by 2020 in the best case
> GaN-on-Si epiwafers will reach 1.6% of the overall power substrate volume by 2020…
> 6” GaN-on-Si epiwafer: suggested price evolution on the open market
> 2013-2020 6” GaN-on-Si epiwafer volumes: open + captive market
> Mapping of open market players
> LED makers positioning
> GaN power device manufacturers
> The pro/cons of various GaN-on-Si substrate procurement as perceived by device makers
> Buying or making GaN-on-Si epiwafer?: LED applications
> Buying or making GaN-on-Si epiwafer?: power applications
> Buying or making GaN-on-Si epiwafer?: RF applications

Latest news 184


Companies cited

Academic Sinica
Advanced Optoelectronic Technology (AOT)
Advanced Technology Materials (ATMI)
Amberwave Systems
Aonex Technologies
Applied Materials
Arizona University

Covalent Materials
Formosa Epitaxy
Fuji Electric
Institute of Semiconductors (Chinese Academy of Sciences)
International Rectifier
Industrial Technology Research Institute (ITRI) ...



  • GaN-on-Si substrate market data and forecasts
  • Analysis of key technology segments and patent assignees
  • Focus on key technology issues: defect reduction, stress management, buffer type, non-polar GaN, GaN on Si(001), layer transfer technology
  • IP collaboration network of main patent applicants
  • Matrix patent applicants/technology segments
  • Relative strength of main companies’ IP
  • Key patents and granted patents near expiration
  • GaN-on-Si IP” profiles of 15 major companies with key patents, patented technologies, partnerships, and IP strength and strategy
  • Excel database with all patents analyzed in the report with technology segmentation