Processing Technique For Single Crystal Diamond With Mechanical Lapping And Chemical Mechanical Polishing

Single crystal diamond material has excellent mechanical, thermal, acoustic, optical and electrical properties. It has a wider application in the high-tech especially ultra-precision machining. With the development of single crystal diamond synthesis technology, applications of single crystal diamond had become more widely. However, it is so excellent in various properties due to single-crystal diamond that its processing is extremely difficult. Each of various processing methods has its advantages and disadvantages, but no one can get the high quality surface of the diamond efficiently and economically. In order to integrate the advantages of various methods, the combination process becomes an important direction of research. This paper presents a method for processing single crystal diamond, which integrates mechanical lapping with chemical mechanical polishing. The main contents are as follows:(1) Mechanical lapping technology of single crystal diamond was researched. Choose suitable diamond grits for processing of single crystal diamond lapping by contrasting influence of different size diamond abrasives on the lapping efficiency and the limit surface roughness. The lapping pressure and processing time were selected by comparison experiments.(2) Chemical mechanical polishing technology of single crystal diamond was researched. The polishing pressure was selected by comparison experiments. Alkaline slurry proved to be better by comparison experiments of three selected polishing slurries. Process of coarse and fine apart was used. The processing time and the limit surface roughness were determined and confirmed.(3) The optimized processing is to obtain a plane of single crystal diamond with lapping using5μm and2μm diamond powders firstly and then to remove the damage brought by lapping with chemical mechanical polishing. A surface roughness Ra, about0.5nm (measured area70μm×53μm), is achieved by using this machining process.(4) The surface of single crystal diamond after processing was analyzed. The diamond surface processed was analyzed by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Raman spectroscopy analysis showed that the Raman line of the surface processed with chemically assisted mechanical polishing only had the peak at1332cm-1, and XPS spectroscopy analysis found oxygen adsorbed on the surface of single crystal diamond. Speculated that the surface of single crystal diamond is formed by the mechanical wear and the mechanical chemical wear involved later.