Stacked image sensor pixel cell with in-pixel vertical channel transfer transistor and reflective structure

US10051218B1 · kind B1 · utility

Assignee

• SMARTSENS TECHNOLOGY (U.S.), INC. · CN

Inventors

• Ko Ping Keung · Ma On Shan, CN
• Zhibin Xiong · Santa Clara, US
• Chen Xu · New Providence, US
• Zexu Shao · Shanghai, CN

Key dates

• Filing date: May 1, 2017
• Grant date: Aug 14, 2018
• Expiry date: May 1, 2037

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10F39/811

Abstract

A pixel cell has a photodiode, a readout circuit, a vertical transfer transistor and a reflective structure. The photodiode is disposed within a first substrate of a first semiconductor chip for accumulating an image charge in response to light incident upon the photodiode. The readout circuit is disposed within a second substrate of a second semiconductor chip. The vertical transfer transistor is coupled between the photodiode and the readout circuitry to transfer the image charge from the photodiode to the readout circuitry. The reflective structure is positioned between the readout circuit and the photodiode to reflect incident light, that passes through the photodiode without being absorbed, back towards the photodiode for a second chance at being absorbed.