Characteristics of MOSFETs on large-grain polysilicon films

Polysilicon transistors with improved characteristics are reported. Solid-phase crystallization of evaporated amorphous silicon is used to grow grains in the film up to 3.5 mu m. MOSFETs fabricated on this poly-Si film exhibit a carrier mobility of 165 cm/sup 2//V-s for electrons and 69 cm/sup 2//V-cm for holes. CMOS 100-stage inverter chains with propagation delay times of 400 ps/stage are demonstrated. The dependence of electrical characteristics on channel length is found and explained by the number of grain boundaries in the channel region. The results indicate that the characteristics of MOSFETs are improved if the grain size of the poly-Si film is as large as the device dimensions. All the devices fabricated are applicable to high-density VLSIs.<
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