Smear-less SOI image sensor

An SOI image sensor where the read-out transistors are well isolated from the silicon substrate is proposed. The isolation results in remarkable reduction of the photo-leakage current to a value as low as 1/8000 times that in the conventional bulk transistors, implying the corresponding reduction of smear noise of the sensor. It is pointed out also that the parasitic capacitance of the vertical signal line in the SOI structure is reduced to a half value of that in the bulk structure. With the use of the large area seeding-region serving also as a photodiode region, a high-quality SOI film has been obtained by the laser recrystallization. The structure of the SOI image sensor is the hybrid integration of the SOI transistors and the bulk transistors. As a result, the video output signal of 50 pixels has been successfully obtained.