Polishing process for cadmium-zinc-cadmium wafer

Abstract

The invention discloses a polishing process for a cadmium-zinc-cadmium wafer. The polishing process comprises the following steps of grinding: grinding the cadmium-zinc-cadmium crystal by selecting afrosted puffed glass disc; milling: rotating a grinding wheel of a milling machine, removing a surface damage layer of the wafer, controlling the removal amount to be 80-150 microns and the surface roughness to be less than or equal to 20 nm, spraying cooling water between the wafer and the grinding wheel in the milling process, and transferring the wafer to a polishing procedure after processingis finished; and chemical-mechanical polishing: arranging the surface of a bearing disc to be in an inclined shape which is gradually lowered from the middle part of the disc to the circumference of the disc with an inclination angle to be 2 plus / minus 0.5 degrees, placing the cadmium-zinc-cadmium wafer on the bearing disc, adding a polishing solution with a pH value to be 9-11 in the chemical-mechanical polishing process, controlling a rotating speed of a grinding head to be 3-20r / min, the pressure to be 2-10N / cm2, the removal amount to be 20-40 microns and the time to be 20-40 min, and enabling the polishing solution to flow back and return to a polishing solution supply system after polishing is finished. The polishing process can effectively reduce scratches, scorings and cracks of thewafer, can reduce the surface roughness of the wafer and has a wide application prospect.

Description

technical field [0001] The invention relates to the technical field of wafer processing, in particular to a polishing process of cadmium zinc telluride. Background technique [0002] Cadmium zinc telluride crystal is a wide bandgap II-VI compound semiconductor, which has excellent photoelectric properties, and is by far the most ideal semiconductor material for the manufacture of room temperature X-ray and γ-ray detectors, and is widely used as the epitaxy of infrared detector HgCdTe Substrates and room temperature nuclear radiation detectors and other fields. In the existing CdZnTe wafer polishing process, the wafer is usually mechanically ground first and then chemically mechanically polished. During the mechanical grinding process, the material for making the grinding disc is usually ductile iron, which is easily oxidized to obtain ferric oxide Particles, resulting in wafer scratches, scratches, dark cracks. [0003] Chemical Mechanical Polishing (CMP) is a means of obt...

AI Technical Summary

Problems solved by technology

However, there is still a problem in chemical mechanical polishing: the middle line speed of the wafer is slow, and the line speed increases as it gets closer to the outer edge, which causes the phenomenon of unbalanced internal and external drops of the wafer to always exist, so that the surface roughness of the product is always unsatisfactory. further improvement

According to reports, the surface roughness of existing CdZnTe wafers is usually above 1nm

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