Sapphire substrate polishing device and process

Abstract

The invention discloses a sapphire substrate polishing device and a polishing process. A rotating shaft is rotatably mounted on a frame, a polishing table is fixed to the top end of the rotating shaft, a crystal polishing pad is fixed to the upper surface of the polishing table, an abrasive feeding mechanism is arranged above the crystal polishing pad, a fixing ring is mounted on a mechanical armthrough a rubber wheel, a substrate fixing disk is arranged in the fixing ring, a pressing mechanism for pressing a sapphire substrate fixed by the substrate fixing disk towards the crystal polishingpad is arranged above the substrate fixing disk, the crystal polishing pad is formed by adhering crystal chips of the same thickness onto the upper surface of the polishing table through ultraviolet glue, and the gap between each two adjacent crystal chips ranges from 0.5mm to 2mm. After polishing, the planeness of the sapphire substrate is smaller than 5 micrometers, the surface roughness of thesapphire substrate is smaller than 0.3 nanometer, the surface of the substrate is not provided with complicated products, complicated post cleaning is omitted, cost is saved, and the rate of finishedproducts is increased.

Description

technical field [0001] The invention relates to the field of semiconductor materials. The invention discloses a sapphire substrate polishing device, and the invention also discloses a sapphire substrate polishing process. Background technique [0002] With the sharp increase in the demand for high-brightness LEDs in the field of lighting engineering, it has driven the development of the domestic sapphire substrate material preparation industry. Since the sapphire crystal (α—Al 2 o 3 ) has remarkable characteristics such as high temperature resistance, corrosion resistance, and wide light transmission band, and is the preferred substrate material for externally extended GaN. , especially the nanoscale polishing of the wafer surface brings many technical difficulties. In order to cope with the ultra-smooth and non-damaging requirements on the surface of product substrate materials put forward by the development of optoelectronic technology, the sapphire substrate must be fi...

AI Technical Summary

Problems solved by technology

CMP technology mainly uses polyurethane and non-woven soft polishing discs. Although the modified layer and surface roughness of the polished surface can meet the requirements for the use of LED substrates, the elastic deformation of the soft polishing discs during the polishing process causes the workpiece The surface pressure distribution is uneven, which often causes the wafer to "sag", and the polishing disc is gradually "glazed" due to the repeated friction of the abrasive grains during use, and the flatness is gradually reduced.

In CMP technology, a good polishing effect can be obtained by accurately controlling the particle size, concentration, hardness, pH value and temperature of the polishing liquid in the polishing liquid, but it is difficult to comprehensively control these parameters in the actual operation process and the polishing liquid It is easy to take away the heat generated by the friction between the abrasive grains and the wafer, and the temperature required for chemical corrosion cannot be reached. The abrasive grains are also easily affected by the hydraulic pressure, so that the abrasive grains cannot smoothly enter the wafer surface for mechanical grinding, resulting in low polishing efficiency.

Generally speaking, alkaline medium is generally used in CMP polishing liquid, such as NaOH, KOH and other strong bases. Alkali metal ions enter the substrate during the polishing process, which is likely to cause partial punch-through of the device and increase the leakage current. The reliability of the work is reduced, causing the device to fail

The post-processing of alkaline polishing liquid is also quite troublesome. If it is not handled properly, it will cause considerable losses to people or the environment.

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