Heraeus Quarzglas GmbH has sued Corning Inc. in Germany, alleging that the American firm is infringing a European patent for fused silica glass used in semiconductor manufacturing equipment. According to Corning's Aug. 3 quarterly report, the lawsuit asks the court to order Corning to stop importing or selling fused silica optical components for stepper machines in Germany. "Corning is in discussions with Heraeus in an effort to reach an amicable resolution," Corning's report says. The lawsuit is the third faced by Corning in connection with patents for fused silica for steppers. Shin Etsu Quartz Products Co. filed the first two in Japan in 1999 and 2000. In June, a Japanese court ordered Shin Etsu and Corning into settlement discussions, Corning's report says.