Fabrication process for thin film transistors in a display or electronic device

A fabrication process for a thin film transistor, which includes at least:

• a first process step comprising:
• formation of a semiconductor layer on a substrate, followed by crystallization of the semiconductor layer during which the substrate is isolated from atmosphere;
• formation of a first gate insulator layer on the semiconductor layer without exposing the substrate to atmosphere,
• a second process step, following completion of the first step, which involves a patterning of the semiconductor layer and the first gate insulator layer by using a single mask;
• a third process step, following completion of the second step, which involves formation of a second gate insulator layer at least on the first gate insulator layer;
• and
• a fourth process step, following completion of the third process step, which involves thermal processing of the first gate insulator layer, the second gate insulator layer, and the semiconductor layer.

A fabrication process for a thin film transistor that includes at least:

• a first process step comprising:
• formation of an underlevel protection layer on a substrate without exposing the substrate to atmosphere;
• formation of a semiconductor layer on the underlevel protection layer without exposing the substrate to atmosphere;
• crystallization of the semiconductor layer without exposing the substrate to atmosphere, followed by formation of a first gate insulator layer on the semiconductor layer during which the substrate is not exposed to atmosphere,
• a second process step, following completion of the first step, which involves a patterning of the semiconductor layer and the first gate insulator layer by using a single mask;
• and
• a third process step, following completion of the second step, which involves formation of a second gate insulator layer at least on the first gate insulator layer.

A fabrication process for a thin film transistor which includes at least:

• a first process step which involves the formation of a semiconductor layer on a substrate which is isolated from atmosphere, followed by crystallization of said semiconductor layer in a non-oxidizing atmosphere without exposing said substrate to atmosphere, followed by formation of a first gate insulator layer on top of said semiconductor layer during which said substrate is not exposed to atmosphere;
• a second process step, following completion of the first process step, which involves thermal processing of said first gate insulator layer and said semiconductor layer;
• a third process step, following completion of the second process step, which involves patterning of said first gate insulator layer and said semiconductor layer;
• and a fourth process step, following completion of the third process step, which involves hydrogenation of said substrate followed by formation of a second gate insulator layer on the surface of said first gate insulator layer.