碲镉汞表面处理中异常现象的分析及控制

Analysis and control of abnormal phenomena in HgCdTe surface treatment

表面处理是碲镉汞(HgCdTe)红外探测器芯片制作流程的开始,其效果会直接影响芯片的良品率。采用金相显微镜、扫描电子显微镜(SEM)和X射线光电子能谱(XPS)分析手段,探究了碲镉汞表面处理工艺中四种典型的表面异常现象的成因,并提出了相应的控制措施。水痕缺陷的形成机理为吸氧腐蚀,通过稳定氮气气流快速将晶片表面吹干可以控制该缺陷的形成;染色现象的成因为腐蚀液被不均匀稀释或腐蚀液被水等杂质污染,工艺中应严格避免杂质的污染,腐蚀结束后快速冲洗表面;圆斑现象是由于缺陷处吸附清洗液引起,采用异丙醇浸泡后再干燥可以降低该缺陷出现的概率;甲苯与HgCdTe表面直接接触时会导致碲镉汞表面粗糙度增大,工艺中需要避免甲苯和HgCdTe表面的直接接触。

The surface treatment is the beginning of the manufacturing process of HgCdTe infrared detector chip,and its quality will directly affect the yield of the chip.The mechanisms of four typical surface anomalies in the HgCdTe surface treatment process were explored using metallographic microscope,scanning electron microscope(SEM)and X-ray photoelectron spectroscopy(XPS)analysis methods,and the corresponding control measures are proposed.The water mark defect is triggered by oxygen absorption corrosion,and this defect can be con⁃trolled by rapidly drying the HgCdTe surface with a stable nitrogen gas flow.The staining is induced by the corro⁃sive liquid unevenly diluted or contaminated by impurities such as water.To reduce the probability of staining,the contamination should be strictly avoided in the process,and the surface should be quickly rinsed after corro⁃sion finish.The round spot originates from the adsorption of the cleaning solution at the material defect,which can be controlled via using isopropanol to soak the HgCdTe before drying.When toluene is in direct contact with HgCdTe,the surface roughness of HgCdTe will increase,thus this direct contact should be restricted.