| Cadmium Zinc Telluride (CZT) is one of the ternary semi conducting compounds ofⅡ-Ⅵtype, it has high resistively. high atomic number, wide energy gap which can vary from 1.4eV to 2.26eV along with the Zinc changes. Due to the CZT could work at room temperature and does not need to be cooled in liquid nitrogen, it has outstanding performance and strong energy resolving ability to x-ray andγ-ray, it is used in semiconductor detectors for astrophysical research, medicine analysis, industrial ganging and military fields et al. It is also made as substrate for HgCdTe. laser window, solar cell and so on. Up to now, there are few papers dealing with the ultra polishing technology of CZT crystal, because the ultra-precision machining technology with the high accuracy and quality is the business secret.In this paper, a systematic experimental study is presented on the polishing mechanism and process for CZT crystal. The main studied contents and conclusions are as follows:The mechanical polishing process of CZT crystal is investigated by using Al2O3 abrasive with the size of W2.5. The effects of polishing pressure, polishing plate rotational speed. slum7 flow rate and abrasive concentration on surface roughness and material removal rate (MRR) are analyzed. The results show that there are the suitable polishing process parameters by which the low surface roughness and the high MRR can be achieved concurrently.On the basis of the physical and chemical properties of the CZT crystal, the different kinds of abrasive free polishing fluid containing different concentration of oil of vitriol, nitric acid. Na2O2 are prepared. And the abrasive free polishing experiments are performed. From the solubility of the reactive products of CZT crystal in polishing, chemical action mechanism of the polishing fluid are analyzed, and the effects of the different kinds of polishing fluids on surface roughness and MRR are investigated. It is shown that ideal polishing slurry to efficiently achieve high surface quality of CZT crystal wafer should have two characteristics: the resultant on the CZT wafer must be insoluble; then, the generation should be equal to removal speed.By using the polishing slurry containing SiO2 abrasive with size of 10～20 run and nitric acid, the systematic experiments on chemical mechanical polishing (CMP) process of CZT are performed: The suitable polishing process and polishing slurry for CZT are developed. The results show that the CMP is an applied ultra-precision machining technology for CZT wafer, the developed polishing process and polishing slurry can meet the demands of the surface quality and MRR of CZT wafer. Through selecting the suitable polishing parameters, the surface roughness of the mechanical polished CZT substrate can be improved to Ra 0.5 nm and the MRR of CMP can be more than 80nm/min after 30 minutes.
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