MEMC Conducts Seizure and Files Suit Against Soitec for Patent Infringement

ST. PETERS, Mo. -- Dec. 29, 2005 -- MEMC Electronic Materials, Inc. (NYSE: WFR) announced today that a lawsuit has been filed against Soitec for violation of MEMC's European patents on defect-free silicon, referred to as Perfect Silicon. The lawsuit, which was filed with the First Instance Court in Lyon, France, follows a seizure which MEMC conducted in accordance with French law at Soitec's facility in Bernin, France on December 15, 2005. This lawsuit pertains to the same family of patents for which MEMC recently received favorable rulings in the U.S. Court of Appeals and the European Patent Office.

MEMC had previously requested and received the seizure order from the First Instance Court in Lyon. During the seizure, evidence was collected which MEMC believes shows clear violation of its patents by Soitec.

"We believe that Soitec infringes our patents that protect the use, manufacture and sale of Perfect Silicon wafers. We have filed suit following the seizure of evidence, and intend to vigorously pursue this matter using all available remedies, including past damages, royalties, lost profits and injunctions," said Nabeel Gareeb, MEMC's Chief Executive Officer.

Gareeb explained, "Soitec has filed a suit against us in the U.S. to try and have our related patents declared invalid, and has also threatened to do the same in Europe. Given our recent victory in the European Patent Office against another competitor regarding our Perfect Silicon patent family, we are confident that both the European and U.S. patents will be upheld in the courts."

About MEMC

MEMC is the world's largest public company solely devoted to the supply of wafers to semiconductor device manufacturers. MEMC has been a pioneer in the design and development of wafer technologies over the past four decades. With R&D and manufacturing facilities in the U.S., Europe and Asia, MEMC enables the next generation of high performance semiconductor devices.  www.memc.com