METHOD FOR FORMING METAL-GATE OF SEMICONDUCTOR DEVICE

摘要

PURPOSE: A method for manufacturing a metal gate of a semiconductor device is provided to prevent a polysilicon layer from being undercut in a lower portion of a titanium nitride layer, by making the titanium nitride layer have the same etch rate as the polysilicon layer under the titanium nitride layer in a process for etching the titanium nitride layer. CONSTITUTION: A gate insulating layer(22) is formed on a semiconductor substrate(21). A polysilicon layer(23), a titanium nitride layer(24) and an insulating layer are sequentially formed on the gate insulating layer. The insulating layer is patterned. The titanium nitride layer is etched by using the patterned insulating layer as a mask and using a mixture gas composed of Cl-including gas and Cl2 gas. The polysilicon layer is etched by using Cl-based or Br-based gas.