A kind of manufacturing method of image sensor based on germanium p-i-n photodiode

Abstract

The present invention provides a method for manufacturing an image sensor based on a germanium p‑i‑n photodiode, which relates to the field of semiconductor technology, and in particular to a method for manufacturing and integrating a germanium p‑i‑n photodiode into an image sensor structure. The germanium p‑i‑n photodiode is a vertical p‑i‑n photodiode for fabricating a CMOS image sensor. The invention realizes the manufacturing process of the short-wave infrared image sensor with high speed and small pixel size with relatively simpler manufacturing process; The image sensor manufactured by the production process of the present invention has lower dark current and higher sensitivity from visible light to short-wave infrared wavelengths.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and relates to a method for manufacturing an image sensor based on a germanium p-i-n photodiode, in particular to a method for manufacturing and integrating a germanium p-i-n photodiode into an image sensor structure, wherein the germanium p-i-n photodiode is used for manufacturing Vertical p-i-n photodiodes for CMOS image sensors. Background technique [0002] At present, SWIR CMOS Image Sensor has been widely used in small unmanned aerial vehicle systems, motor vehicle systems, intelligent agricultural systems, monitoring systems and other fields. As is well known in the art, using silicon material as photodiode has low quantum efficiency for infrared absorption, especially for wavelength bands above 1 μm with almost no absorption; compared with silicon, germanium-based short-wave infrared CMOS image sensors can capture images from visible light ( 0.4μm - 0.75μm) and further wavelengths...

AI Technical Summary

Problems solved by technology

[0003] When manufacturing germanium-based CMOS image sensors, the existing technology generally uses direct epitaxial growth of germanium on a silicon target wafer, but due to the 4.2% lattice mismatch between germanium and silicon, epitaxial growth will produce misfit dislocations and Penetrating dislocation (thread dislocation), so there are more defects and lower quality, which affects the detection signal-to-noise ratio and detection sensitivity

Although this problem can be improved by some technical means, it will increase the complexity of the device structure and / or process, such as the use of narrow aperture selective manufacturing growth

In addition, since germanium is grown on a silicon wafer at a low temperature by direct epitaxial growth of germanium on a silicon target wafer, the quality of the germanium layer is directly reduced.

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