Wet etching method for preparation of super-junction device

Abstract

The invention discloses a wet etching method for preparation of a super-junction device, which includes firstly, forming an epitaxial layer on a silicon substrate, secondly, forming medium films on the front face and the back face of a silicon chip, thirdly, defining patterns on the front face by photoresist and opening the medium films by means of dry etching, fourthly, removing the photoresist and using the medium films as mask layers to form perpendicular deep grooves by means of wet anisotropic etching, fifthly, filling another epitaxial layer which is opposite to the epitaxial layer in the step one into the deep grooves to form a P-type structure and an N-type structure in an alternative array, sixthly, performing planarization by means of chemical mechanical polishing and standing on the medium films, seventhly, removing the medium films on the front face and the back face by means of wet etching, and eighthly, using mature longitudinal double-diffused metal-oxide semiconductor in the subsequent process to prepare a complete super-junction device. Using the wet etching method for preparation of the super-junction device has smaller damage to the silicon substrate, reduces defects of a PN junction surface and leakage current, and further can guarantee uniformity of perpendicular profiles of the deep grooves and the interior profiles of the faces and reduce production cost.

Description

technical field [0001] The invention belongs to the field of semiconductor integrated circuit manufacturing, and in particular relates to a method for preparing a super junction device by wet etching. Background technique [0002] The super junction device is characterized by the formation of alternately arranged P-type semiconductor thin layers and N-type semiconductor thin layers, using the principle of depletion of P-type semiconductor thin layers and N-type semiconductor thin layers to realize mutual charge compensation, so that the P-type semiconductor thin layers And N-type semiconductor thin layer can achieve high breakdown voltage under high doping concentration, so as to obtain low on-resistance and high breakdown voltage at the same time. One way of forming the super junction device structure is to open a deep trench on the N-type epitaxial layer, and then fill it with P-type epitaxial layers to form alternately arranged P-type and N-type structures. [0003] In t...

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Problems solved by technology

[0003] In the current process, dry etching is mostly used for deep trench etching, which is relatively easy to cause damage to the silicon substrate, and the cost is relatively high

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