GaAs表面旋转超声雾化清洗新技术

研究了一种新型湿法化学清洗半导体GaAs表面的方法。通过简单设计清洗工艺能使GaAs表面产生最低的损伤。GaAs表面清洗必须满足三个条件：(1)清除热力学不稳定因素和表面粘附的杂质，(2) 除去GaAs表面氧化层，(3)提供一个光滑平整的GaAs表面。本文采用旋转超声雾化方式用有机溶剂除去GaAs表面的杂质，再用NH4OH:H2O2:H2O= 1:1:10和HCl:H2O2:H2O=1:1:20顺次腐蚀非常薄的GaAs层，去除表面的金属污染，并在GaAs表面形成一个非常薄的氧化层表面，最后用NH4OH:H2O= 1:5溶液来清除GaAs表面氧化层。测试GaAs表面的特性，分别用X射线光电光谱仪、X射线全反射荧光光谱仪和原子力显微镜测试了GaAs表面氧化的组分、GaAs表面金属污染和GaAs表面形貌，测试结果表明通过旋转超声雾化技术清洗可提供表面无杂质污染、金属污染和表面非常光滑的GaAs衬底，以供外延生长。

GaAs surface wet cleaning by a novel treatment in revolving ultrasonic atomization solution

A novel process for the wet cleaning of GaAs surface is presented. It is designed for technological simplicity and minimum damage generated within the GaAs surface. It combines GaAs cleaning with three conditions consisting of (1) removal of thermodynamically unstable species and (2) surface oxide layers must be completely removed after thermal cleaning, and (3) a smooth surface must be provided. Revolving ultrasonic atomization technology is adopted in the cleaning process. At first impurity removal is achieved by organic solvents; second NH4OH : H2O2 : H2O = 1 : 1 : 10 solution and HCl : H2O2 : H2O = 1 : 1 : 20 solution in succession to etch a very thin GaAs layer, the goal of the step is removing metallic contaminants and forming a very thin oxidation layer on the GaAs wafer surface; NH4OH : H2O = 1 : 5 solution is used as the removed oxide layers in the end. The effectiveness of the process is demonstrated by the operation of the GaAs wafer. Characterization of the oxide composition was carried out by X-ray photoelectron spectroscopy. Metal-contamination and surface morphology was observed by a total reflection X-ray fluorescence spectroscopy and atomic force microscope. The research results show that the cleaned surface is without contamination or metal contamination. Also, the GaAs substrates surface is very smooth for epitaxial growth using the rotary ultrasonic atomization technology.