Substrate etching method

Abstract

A substrate etching method provided in the invention comprises the following steps of a main etching step: etching a graph on a substrate and increasing a bottom width of a profile graph through reducing a substrate surface temperature and lower electrode power during an etching process; an over etching step: continuously etching the substrate, increasing a height of the profile graph through increasing the substrate surface temperature and the lower electrode power and simultaneously modifying a graphic morphology. The main etching step is stopped when a mask layer begins to carry out transverse shrinkage and simultaneously the over etching step begins to carry out. By using the substrate etching method, the ideal graphic morphology can be acquired, and the bottom width and the height of the profile graph can satisfy a technology requirement.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a substrate etching method. Background technique [0002] PSS (Patterned Sapphire Substrate, patterned sapphire substrate) technology is currently a relatively popular method for improving the light extraction efficiency of blue LED chips. It has been proved by production and experiments that the shape of PSS graphics has a great influence on the degree of improving the light extraction efficiency. Among them, the conical shape with straight side walls (the side section is triangular) is more and more popular because of its significant effect on improving light extraction efficiency. It has become more and more popular and has become a more popular process indicator. Generally, the ideal PSS graphic morphology requires that the height of the cross-sectional graphic (triangular) be 1.6±0.1μm, and the bottom width be 2.6±0.15μm; figure 1 shown. [0003] At present, the sa...

AI Technical Summary

Problems solved by technology

The upper RF system of the ICP equipment generally uses a 13.56MHz power supply, and cooperates with the helical coil to generate induction plasma; the lower RF system can use either a 13.56MHz power supply or a 2MHz power supply. Both have their own advantages and disadvantages: the former is prone to upper and lower The problem of energy loss and interference caused by radio frequency coupling; and the latter will cause the problem of insufficient bottom width of PSS graphics due to the enhanced particle bombardment ability

[0011] The over-etching step mainly plays the role of modifying the graphic morphology, and the proportion of the process time is relatively small, and if the remaining amount of the mask is small and the height of the corner is high, if the substrate is continued to be etched, it often occurs The mask has been exhausted, but the problem still exists at the corners of the sidewalls, so that the etching has to be continued to obtain a triangular profile, which results in insufficient height of the profile, such as image 3 shown

[0012] Although the above-mentioned substrate etching method can obtain a relatively ideal pattern shape, the bottom width of the cross-sectional triangle is only about 2.4 μm, which cannot meet the process requirements for the bottom width of more than 2.6 μm.

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