| 摘要 |
PURPOSE: A unit pixel of a CMOS image sensor is provided to enhance reset efficiency under a low input voltage by removing lag of an output voltage and to stabilize process by using a butting contact with high aspect ratio instead of a metal contact. CONSTITUTION: A unit pixel comprises a photodiode(21), a transfer transistor(22), a reset transistor(24), a drive transistor(25), and a select transistor(26). A source-drain path of the transfer transistor is formed between the photodiode and a floating node(23), and a control signal(Tx) is applied to a gate. In the reset transistor, a source-drain path is formed between the floating node and a power voltage node(VDD) and a control signal(Rx) is applied to a drain. In the drive transistor, a gate is connected to the floating node and a drain is connected to the power voltage node. In the select transistor, a control signal(Sx) is applied to a gate, a drain is connected to the source of the drive transistor, and a source is connected to an output node. The reset transistor has the same threshold voltage to the drive and select transistor, and has high threshold voltage compared to the transfer transistor.
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