A method for fabricating a self-aligned double-mesa device structure

Abstract

The invention relates to a self-aligning dual mesa device structure making method. Based on the photoresist reflow process, one-step photolithography is used to make a dual mesa device structure, anddual mesa center self-aligning is carried out. The method is advantaged in that one step of lithography is omitted, flow sheet efficiency is improved, flow sheet cost is reduced, the edge interval between a large mesa and a small mesa can be smaller than 1um and can be further adjusted through photoresist reflow technology control, and the method is especially suitable for making a focal plane array with the high duty ratio.

Description

technical field [0001] The invention belongs to the application field of semiconductor photoelectric devices, and in particular relates to a method for manufacturing a self-aligned double-mesa device structure. Background technique [0002] Wide bandgap semiconductor materials are widely used in optoelectronic devices in the ultraviolet band, and typical materials include GaN, SiC, ZnO, etc. The APD (Avalanche Photodiode) photodetector device prepared by using the avalanche breakdown effect of wide bandgap materials has extremely high avalanche gain, can detect weak ultraviolet light or even ultraviolet single photons, and is widely used in environmental monitoring, medical equipment and other fields. [0003] The APD device structure based on wide-bandgap materials is generally a mesa structure, and mesa sidewall absorption recombination leakage and edge breakdown are prone to occur during high-field avalanche. In order to achieve a high avalanche gain above 10^5, the lite...

AI Technical Summary

Problems solved by technology

[0005] 1. The photolithography registration step is introduced, and the registration error of each film is different, which reduces the process yield and also affects the chip consistency

The registration error of the two overlays makes the small table deviate from the center of the large table. If the registration error is large, the small table will be close to the side of the large table, and the device structure will fail.

[0006] 2. There is a secondary etching problem

In the second step of photolithography and etching, a small mesa is formed, but the large mesa in the first step is etched twice, and the effective depth of the large mesa is not easy to control

Considering that the diameter of the small mesa is the effective area of ​​the device, although the double-mesa structure can improve the performance of the device, it greatly reduces the duty cycle of the focal plane device array and wastes the chip area.

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