Stacked CMOS circuits integrated in laser-recrystallized silicon films

Abstract

Laser-recrystallized poly-silicon films are used as a substrate for the integration of MOS transistors and CMOS circuits. Ring oscillators and frequency divider circuits up to 100 transistors operate well with a yield of about 80%. For the integration of stacked CMOS circuits already tested bulk structures are covered with a dielectric layer and a poly-silicon film which is recrystallized at low temperature. The SOI integration technique, with a maximum temperature treatment of 960°C, is employed to manufacture the second active area as a 3-D technology. After the integration process SOI and bulk CMOS transistors operate independently at two different active levels.