Omnivision Technologies, Inc.

Chiao-Ti Huang

Gang Chen

Bill Phan

Shiyu Sun

Yuanwei Zheng

Sing-Chung Hu

An image sensor includes a photodiode disposed in a semiconductor substrate having a first surface and a second surface opposite to the first surface. A floating diffusion is disposed in the semiconductor substrate. A transfer transistor is configured for coupling the photodiode to the floating diffusion. The transfer transistor includes a vertical transfer gate extending a first depth in a depthwise direction from the first surface into the semiconductor substrate. A transistor is coupled to the floating diffusion. The transistor includes: a planar gate disposed proximate to the first surface of the semiconductor substrate; and a plurality of vertical gate electrodes, each extending a respective depth into the semiconductor substrate from the planar gate in the depthwise direction. The respective depth of at least one of the plurality of vertical gate electrodes is the same as the first depth of the vertical transfer gate.

Transistors having increased effective channel width

A method for manufacturing an image sensor includes, for each of a plurality of photosensitive pixels of the image sensor, forming a trench in a semiconductor substrate of the image sensor, and depositing temporary transfer gate material in and above the trench. The method further includes, after the step of depositing temporary transfer gate material, high-temperature annealing at least a portion of the semiconductor substrate. In addition, the method includes, after the step of high-temperature annealing, (a) removing the temporary transfer gate material, thereby reopening the trench, (b) depositing a passivation lining, having a high-k dielectric, in the reopened trench, and (c) depositing metal on the high-k dielectric passivation lining to form a metal vertical transfer gate in the trench and extending above the trench.

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Beaverton, OR, United States of America

Chiao-Ti Huang