Backside-illuminated sensor

Abstract

Provides is a backside-illuminated sensor including a semiconductor substrate having a front surface and a back surface. A plurality of image sensor elements is formed on the front surface of the semiconductor substrate. At least one of the image sensor elements includes a transfer transistor and a photodetector. The gate of the transfer transistor includes an optically reflective layer. The gate of the transfer transistor, including the optically reflective layer, overlies the photodetector. In one embodiment, the gate overlies the photodetector by at least 5%. The invention can resolve the penetrating problem and improve the sensitivity for the image sensor element.

Description

technical field [0001] The present invention relates to a semiconductor device, and more particularly to a back-illuminated sensor. Background technique [0002] In the application of semiconductor technology, the back-illuminated sensor is used to sense the amount of radiation (such as light) projected on the back surface of the substrate. For this purpose, the image sensor uses an array of elements (such as pixels) to detect the amount of radiation. Each image sensing element includes at least one radiation sensing element, where the radiation sensing element refers to a light sensor. The light sensor can be located on the front side of the substrate, and the substrate must be thin enough to allow radiation incident on the backside of the substrate to reach the light sensor. Thin substrates reduce optical or electrical crosstalk between image sensor elements. However, thin substrates can also reduce sensor performance, such as reducing quantum efficiency (the ability to ...

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Problems solved by technology

However, thin substrates can also reduce sensor performance, such as reduced quantum efficiency (the ability to convert radiation into a signal), especially for visible light with long wavelengths (such as 650nm)

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