Method for making image sensor with reduced etching damage

Abstract

A method of forming a pixel of an image sensor with reduced etching damage is disclosed. The method first includes forming a light sensitive element in a substrate. Then, a transfer gate is formed atop the substrate and adjacent to the light sensitive element. A protective layer, such as an anti-reflective coating, is then formed over the light sensitive element. A blanket oxide layer is formed over the protective layer and the transfer gate. Finally, the oxide layer is etched back to form a sidewall spacer the sidewall of a gate stack. The protective layer protects the surface of the light sensitive element from etching damage.

Description

technical field [0001] The present invention relates to methods of manufacturing image sensors, and more particularly, to a method of reducing the extent of etching damage to photodiodes during the manufacturing process. Background technique [0002] Image sensors have become ubiquitous, and they are widely used in digital cameras, cellular phones, security cameras, medical equipment, automobiles, and other applications. The technology of manufacturing image sensors, especially CMOS (Complementary Metal Oxide Semiconductor) image sensors continues to develop rapidly. For example, the requirements of high resolution and low power consumption promote the further miniaturization and integration of image sensors. [0003] The manufacture of high-performance image sensors is a rather complex process with many processing steps. For example, to form the photodiodes and other elements of the active pixels in an image sensor, various etching, implantation, photolithograph, and clea...

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Problems solved by technology

This method of extending the mask into opposing wells can create undesirable "hedges"

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