LIGHT SENSOR DEVICES AND MANUFACTURING METHODS

Abstract

A single-photon avalanche diode (SPAD) image sensor comprising at least three device layers. The first device layer contains an array of SPADs. The second device layer provides in-pixel circuitry for the SPADs. Row driver circuitry, column readout circuitry, and other circuitry are located in the third device layer or in a fourth device layer. The first device layer can be fabricated using a simplified process that does not produce transistors. The second device layer can be fabricated using a mature process technology that provides high-voltage transistors. The third and optional fourth device layers can be fabricated using an advanced process technology that provides high-density transistors with lower operating voltages than those required for the in-pixel circuitry.This structure increases the number of SPAD pixels that can be provided per device area unit and is cost-effective.

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