Oerlikon Asserts Thin-Film Solar Production Patent; Sunfilm Defends in Dusseldorf

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Oerlikon is a Swiss company that makes thin-film solar production equipment.  Oerlikon is the worldwide exclusive licensee of “micromorph” tandem cell technology, which it acquired in 2003 from the University of Neuchatel in Switzerland. 

Micromorph tandem cells have two different silicon materials – amorph and microcrystalline – in a top and a bottom cell.  This setup increases efficiency because the amorphous top cell converts the visible light from the sun while the microcrystalline bottom cell absorbs sunlight in the infrared part of the spectrum.

The technology is covered by a family of patents, including European patent EP 0 871 979 (EP patent) and U.S. Patent No. 6,309,906 (U.S. patent), and generally provides a process for making thin-film solar cells using microcrystalline or nanocrystalline silicon.  As discussed in Oerlikon’s U.S. patent, this patent family addresses some of the problems of thin film solar cell production and facilitates large scale production. 

Last month Oerlikon sued German thin-film solar cell maker Sunfilm AG (Sunfilm) in the German District Court of Dusseldorf (pictured above), alleging infringement of the EP patent.* 

One common method of laying microcrystalline silicon on a substrate to make solar cells is called Chemical Vapor Deposition (CVD) and involves using one or more volatile gases, which react or decompose to deposit the desired material.  CVD often results in defects in the silicon layer, including weak photocurrent and negative “doping.”  (doping means intentionally adding impurities to a semiconductor to increase the number of free charge carriers; the level of doping needs to be controlled to achieve efficient solar cells).  According to the U.S. patent, oxygen is one culprit that can cause flaws in the microcrystalline silicon layer.  Oerlikon’s patented technology overcomes these problems by purifying one of the gases before the silicon deposition step to reduce the oxygen content of the deposition gas. 

One interesting point here is that Oerlikon, a production equipment manufacturer, has not sued a direct competitor in Sunfilm, but has instead sued a competitor’s customer (Sunfilm is a thin film solar cell manufacturer, not a production equipment maker) .

Therefore, this lawsuit has raised the question whether Oerlikon also plans to sue Sunfilm’s supplier, California production equipment maker Applied Materials, Inc. (AMAT) (Sunfilm recently awarded AMAT a contract to supply a second line of manufacturing equipment).  Although Oerlikon denies that it intends to sue AMAT for infringement, AMAT knows it may be in the line of fire and has taken a preemptive step in the court of public opinion.  It has issued a statement defending its manufacturing process and asserting that it does not infringe Oerlikon’s patent.

* Unfortunately, I can’t get a copy of the complaint filed by Oerlikon – a German patent attorney informed me that German court papers are only available upon written request and only if one can demonstrate a special interest in the case.  I also can’t get an English translation of the European patent.  Thus, I will limit my discussion to the U.S. patent (which is a sister application of the EP patent and therefore contains a similar or identical description of the technology).

Eric Lane Avatar

Eric Lane

Eric Lane, the founder and principal of Green Patent Law, is an intellectual property lawyer and registered U.S. patent attorney in New York and is a member of the bar in New York and California. Eric has more than two decades of experience working with wind, solar PV, CSP, biofuels, and geothermal, energy storage technologies, carbon capture and sequestration, medical devices, data communications, mechanical, chemical, internet and software.