Method for decreasing wet etching speed of silicon nitride

Abstract

A method for decreasing the wet etching speed of silicon nitride includes implanting the nitrogen-containing ions into silicon nitride layer and thermal tempering to repair the damage caused by implanting and to generate Si-N bonds. It can increase the etching selectivity of silicon oxide to silicon nitrode, so using the silicon nitride layer as the etch terminating layer in LPCVD.

Description

technical field [0001] The invention relates to a semiconductor manufacturing technology, and in particular to a method for reducing the wet etching rate of silicon nitride. Background technique [0002] Silicon nitride (Si 3 N 4 ) is a common dielectric material in semiconductor manufacturing, and its main application is as an etching mask for silicon oxide layers (for example, in the process of self-aligned contact windows). In current semiconductor manufacturing, silicon nitride is mainly formed by Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD). There is not much difference in the dry etching rate of the silicon nitride layer formed by the above two methods, but in terms of the wet etching rate, the PECVD silicon nitride layer is about 10 times faster than the LPCVD silicon nitride layer. [0003] Traditional LPCVD silicon nitride layers are usually made of SiH 2 Cl 2 with NH 3 For the deposition of reactants, the...

AI Technical Summary

Problems solved by technology

Although the LPCVD silicon nitride layer deposited at 700-800°C in the traditional way can be used as an etch stop layer, in the manufacturing process of stacked DRAM, since the capacitor is made after the transistor is formed, if the LPCVD deposited at high temperature is used The silicon nitride layer will increase the contact resistance of the connecting diffusion region, which will affect the performance of the transistor

Therefore, if the LPCVD silicon nitride layer deposited at low temperature can be used here, it will help reduce the thermal budget, but first, the problem of its wet etching rate being too fast must be solved

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