How to make a trench device

Abstract

The invention provides a method for manufacturing a trench device, which comprises the steps of carrying out chemical-mechanical polishing until an epitaxial layer is flush with the surface of a stop layer, then carrying out measurement to acquire the actual thickness of the stop layer above a silicon substrate, carrying out thermal oxide growth according to the actual thickness of the stop layer above the silicon substrate so as to completely oxidize the epitaxial layer above the surface height of the silicon substrate in a trench into a silicon dioxide layer, and then carrying out etching so as to remove the stop layer and the silicon dioxide layer, thereby not only being capable of removing the epitaxial layer above the substrate surface, but also not damaging zero layer photoetching marks. Therefore, the method not only can ensure that photoetching alignment is not affected, but also can acquire excellent flattening effects, thereby avoiding that the epitaxial layer has bulges relative to the silicon substrate and enables subsequent gate oxide, polycrystalline processes and the like to form steps, and being conducive to improving the performance such as voltage resistance and the like of the device.

Description

technical field [0001] The invention relates to the field of integrated circuit manufacturing, in particular to a method for manufacturing a trench device. Background technique [0002] Trench superjunction MOSFET is a new type of semiconductor power device. Due to its special vertical PN column alternating structure, the charges in this special structure compensate each other. When the device is in the off state, applying a lower voltage can make the P-type region and the The N-type region can achieve higher breakdown voltage and lower on-resistance when using higher doping concentration. Usually, trench etching is performed on a substrate of a specific doped type, and then filled with epitaxial doped silicon with the opposite doping type of the substrate to form a P / N type alternating structure, which is characterized by low cost but complex process , the technical difficulty is very high. [0003] Among them, the surface planarization treatment after trench epitaxial fi...

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Problems solved by technology

Another method is not too much grinding, but after the CMP removal of the part of the entire epitaxial filling region that is raised above the stopper layer, the stopper layer 11 is completely removed by an etching process. However, as Figure 5 As shown, in this case, after the removal of the blocking layer 11, there is a protrusion with a height of h3 in the epitaxial layer of the trench relative to the substrate 10, and the poor treatment of this protrusion will make the subsequent gate oxide, polycrystalline, etc. Steps are formed, there is a risk of leakage, which seriously affects the withstand voltage and other performance of the device structure

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