Method for preventing formation of polycrystalline particles on back face during multi-layer epitaxial growth and back sealing structure

Abstract

The invention provides a method for preventing formation of polycrystalline particles on a back face during multi-layer epitaxial growth and a back sealing structure. The method comprises the following steps: providing a semiconductor substrate, wherein the semiconductor substrate is used for performing multi-layer ion injection and multi-layer epitaxial growth to form a super junction structure; forming a first back sealing protection layer on the back face of the semiconductor substrate, wherein the first back sealing protection layer is a tetraethyl orthosilicate layer; forming a second back sealing protection layer on the surface of the first back sealing protection layer. A layer of new hard back sealing protection layer is added on the basis of an original back sealing protection layer, thereby avoiding damages to the back sealing structure due to repeated epitaxial growth and other processes, avoiding providing a growth core for next epitaxial growth, and preventing formation of polycrystalline particles on the back face of a wafer. During epitaxial layer growth of the new back sealing protection layer, an epitaxial layer can grow uniformly on the entire back face, thereby keeping the substrate flat on the back face of the wafer, avoiding influences on subsequent processes such as photoetching, and increasing the yield and online output.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for preventing polycrystalline particles from forming on the back of a wafer during multi-layer epitaxial growth and a back seal structure. Background technique [0002] With the improvement of the operating voltage of power transistors, the characteristics of high-power transistors are further improved, and the concept of super junction is proposed. The on-resistance of a superjunction structure is only 20% of that of a conventional power transistor with the same area. Moreover, its output capacitance and input capacitance are also reduced synchronously, and the operating frequency characteristics are improved. [0003] There are generally two ways to realize the super junction structure: one is to use multi-layer implantation and multi-layer epitaxy to form a super junction; the other is to use deep trench etching and epitaxial filling growth to fo...

AI Technical Summary

Problems solved by technology

According to the thickness of epitaxial growth, polycrystalline particles can grow to a few microns to tens of microns, which seriously affects the subsequent process, especially photolithography, resulting in low yield or even inability to tape out online

[0005] Specifically, the polycrystalline particles on the back of the substrate make the back of the entire wafer uneven, and when the wafer is bonded by vacuum adsorption, there is a certain degree of warpage on the wafer surface

In photolithography, this causes local focal length changes, which cause line width changes, image distortion, and exposure failures

When the situation is serious, it may even cause the wafer to be unable to suck and fix it

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