Thin film semiconductor and process for producing the same

A thin film semiconductor comprising:

• a substrate made of quartz;
• a single-crystalline silicon layer;
• and
• an intermediate layer formed between said substrate and said single-crystalline silicon layer, said intermediate layer having a composition which varies according to depth such that a first boundary of said intermediate layer has a first thermal expansion coefficient approximately equal to the thermal expansion coefficient of said substrate, said first boundary contacting with said substrate, and that a second boundary of said intermediate layer has a second thermal expansion coefficient approximately equal to the thermal expansion coefficient of said single-crystalline silicon layer, said second boundary contacting with said single-crystalline silicon layer, said intermediate layer including a first layer of SiO.sub.2 formed on a surface of said substrate and having said first thermal expansion coefficient, a second layer of SiON formed on said first layer, and a third layer of Si.sub.3 N.sub.4 formed on said second layer and having said second thermal expansion coefficient, said second layer of SiON having a thermal expansion coefficient intermediate between said first thermal expansion coefficient and said second thermal expansion coefficient.

A thin film seconductor comprising:

• a substrate made of quartz;
• a single-crystalline silicon layer;
• and
• an intermediate layer is formed between said substrate and said single-crystalline silicon layer, and said intermediate layer having a composition which varies according to depth such that a first boundary of said intermediate layer has a first thermal expansion coefficient approximately equal to the thermal expansion coefficient of said substrate, said first boundary contacting with said substrate, and that a second boundary of said intermediate layer has a second thermal expansion coefficient approximately equal to the thermal expansion coefficient of said single-crystalline silicon layer, said second boundary contacting with said single-crystalline silicon layer, said intermediate layer including a first layer of SiO.sub.2 formed on a surface of said substrate and having said first thermal expansion coefficient, and a second layer of SiON formed on said first layer and having said second thermal expansion coefficient.