New stack capacitor for dynamic data storage in polysilicon active matrix arrays

A stack capacitor for dynamic circuits employing self-aligned polysilicon thin-film transistors (TFTs) is proposed. Through circuit layout without deviation in processing, a thin-oxide capacitor can be fabricated directly underneath the conventional planar thick-oxide capacitor to form a sandwiched stack capacitor. Due to the addition of the thin-oxide capacitor with high unit capacitance, significant savings in chip area can be achieved. The stack capacitor structure has been successfully demonstrated in polysilicon linear arrays for printer applications. Improved data retention and decreased feedthrough voltage, characteristic of higher storage capacitance, are demonstrated.<
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