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Technical Insight

Knowmade: A perspective on the Allos-Azur deal


Allos Semiconductors is moving away from power electronics and transferring its know-how to Azur, a new entrant in GaN-on-Si technology. Rémi Comyn of Knowmade, explores the patent and IP background.

On July 8th, 2020, Allos Semiconductors disclosed a deal with Azur Space, a company specialising in the development and production of multi-junction solar cells, to sell its GaN RF and power electronics business, in a view to focus on its GaN-on-Si micro LED epiwafer technology for up to 300 mm.

Azur Space is a new entrant in the power electronics business; in fact it has no preexisting intellectual property (IP) assets related to GaN-on-Si epitaxy and power GaN device technology, but it does have the ability to leverage its manufacturing expertise and facilities for high-volume production with a relatively limited initial investment (10 million euros).

Since the very beginning and its foundation in 2014, Allos Semiconductors has made its epiwafer technology – inherited from Azzurro Semiconductors – available through licensing and technology transfer to “high-power electronics companies that would like to enter the GaN-on-Si sector and avoid the cost, risk and uncertainty of starting their own epi development from scratch”. In other words, Allos Semiconductors would enable new players to safely enter the GaN-on-Si business, relying on Allos’ patented and proprietary growth techniques and epi-structures.

In 2017, the licensing & technology engineering firm further strengthened its value proposition by disclosing a carbon-doping-free GaN-on-Si technology, offering good dynamic resistance, good crystal quality and extremely low leakage current all at once, thereby enabling customers to overcome the usual trade-off between these parameters when using carbon doping in epi-structures.

Moreover, it would provide an effective way for customers to avoid conflicts with well-established IP competitors relying on carbon doping to achieve the power electronics industry’s requirements. As of 2017, Allos Semiconductors’ approach was based on the insertion of multiple interlayers in an unintentionally doped thick GaN buffer layer (Fig. 1). To our knowledge, neither Allos nor Azzurro has filed patents describing such a structure, or how to design and grow the interlayers in order to effectively reduce the leakage current in high-voltage applications.

At the time of Azzurro Semiconductors’ bankruptcy, the GaN-on-Si epi-foundry had filed 29 patent families (i.e. single inventions patented in multiple countries). Most of them were reviewed by Knowmade in the GaN-on-Silicon Patent Landscape 2020. However, since Allos Semiconductors was created in 2014 and acquired Azzurro’s technology, know-how and patents, the engineering and consulting company has not relied on patents to protect new inventions.

As a result, Allos Semiconductors’ IP portfolio shrunk to eight alive patent families (21 of Azzurro’s inventions were abandoned and no patent application has been filed by Allos), grouping less than 50 patents and patent applications filed in the main area of interest for Azzurro Semiconductors’ business: Europe (12), USA (9), China (8), Korea (5), Japan (2) and Taiwan (2). Furthermore, as of 2020, all Allos’ alive patent families have already been the subject of a transfer of rights to Azur Space.

Indeed, the first patent transfers between the two companies occurred in 2015 and concerned the most relevant inventions for power applications, filed by Azzurro Semiconductors in 2013:

• P-doping of group-III-nitride buffer layer structure on a hetero-substrate, to provide good stress management and the high resistivity required for RF & power applications (Fig. 2, Patent US 9,496,349).

• Layer structure for a group-III nitride normally-off transistor, with a recess-free design (Fig. 3 Patent US 9,773,896).

Both patent families were granted thereafter with a protection in main market areas such as Europe, USA, China and Korea, with the notable exception of Japan. Moreover, four domestic granted patents (filed only in Germany) dealing with electronics as well as optoelectronics were transferred to Azur Space in 2016:

• III-nitride p-channel transistor structures to produce logic components comprises growing an aluminum indium nitride barrier layer on a group-III nitride buffer layer (patent DE10200403434)

• Field-effect transistors, comprises an aluminum-gallium-indium-nitrogen layer, aluminum-gallium-nitrogen intermediate layer, and another aluminum-gallium-indium-nitrogen layer (patent DE102006030305)

• Group-III nitride transistor component on a Si substrate for high temperature and microwaves, with a buffer layer formed by gas phase epitaxy, iron-doping of GaN-based buffer layers (patent DE10256911)

• Production of a planar tear-free light emitter structure comprises applying an aluminum-containing group III-V seed layer, aluminum-containing group III-V intermediate layers, and silicon nitride intermediate layers on a Si substrate (patent DE10151092)