GaAs的CH_4／H_2反应离子腐蚀研究

Methane/Hydrogen-Based Reactive Ion Etching on GaAs

在前研究ＩｎＰ的ＣＨ４／Ｈ２反应离子腐蚀的基础上，进行了ＧａＡｓ的ＣＨ４／Ｈ２反应离子腐蚀研究。ＧａＡｓ的腐蚀速率比ＩｎＰ慢，随ＣＨ４／Ｈ２组份之比值、工作压强、总流量率等而改变，从２ｎｍ／ｍｉｎ到８ｎｍ／ｍｉｎ。当总流量率为３０～１２３ｓｃｃｍ之间、ＣＨ４／Ｈ２＝０．１８，腐蚀后的表面总是光亮平滑的，损伤层的厚度≥３０ｎｍ。当用ＣＨ４／Ｈ２ＲＩＥ在ＣａＡｓ上制作深度＞０．６μｍ的结构时，必须要考虑高能离子的轰击给晶体造成的损伤和给光刻胶掩模造成的浸蚀，此时光刻胶作掩模已经不能满足要求，应改用介质薄膜。

This study is based on the results of studing CH./H, reactive ion etching (RIE) on InP,at which we worked previously. We have investigated etch rates,surface morphologies of GaAs RIE. Etch rates of GaAs are very low,from 2 nm/min to 8 nm/min. It all depends on ratio of CH4/H2. GaAs etched surface is always smooth at the CH4/H2 ratio of 0.18 with total flow rates from 30 seem to 123 seem. The thickness of residul damage layer of etched GaAs is greater than 30 nm.It is necessary to consider crystal damage and mask erosion during RIE of deep(>0. 6 um)features. Photoresist as etching mask may not satisfy that requirements. It should be replaced by dielectric film.