Method for fabricating a gate mask of a semiconductor device

Abstract

A nitride layer of the gate mask for the semiconductor device is deposited at a temperature higher than 750 deg. C. so as to release hydrogen from the nitride layer. Alternatively, a nitride layer of the gate mask for the semiconductor device is deposited in a gas atmosphere with use of an ammonia gas and a silane gas such that a flow rate of the ammonia gas is set at least twenty times or greater than that of the silane gas. Accordingly, the problem with respect to the threshold voltages Vt of the semiconductor devices varying greatly from device to device when the polysilicon layer or the amorphous silicon layer is formed in the vicinity of the nitride layer and is doped with Group III impurities, will be solved.

What is claimed is:  
     
         1 . A method for fabricating a gate mask for a semiconductor device, wherein a nitride layer of the gate mask for the semiconductor device is deposited at a temperature higher than 750 deg. C. so as to release hydrogen from said nitride layer.  
     
     
         2 . The method for fabricating a gate mask for a semiconductor device according to  claim 1 , wherein said temperature is higher than 830 deg. C.  
     
     
         3 . A method for fabricating a gate mask of a semiconductor device, wherein a nitride layer of the gate mask for the semiconductor device is deposited in a gas atmosphere of an ammonia gas and a silane gas, a flow rate of said ammonia gas being at least twenty times a flow rate of the silane gas.  
     
     
         4 . A method for fabricating a gate mask of a semiconductor device, wherein a nitride layer of the gate mask for the semiconductor device is deposited in a gas atmosphere of an ammonia gas and a silane gas, a flow rate of said ammonia gas being from twenty to one hundred times a flow rate of the silane gas.  
     
     
         5 . The method for fabricating a gate mask of a semiconductor device according to any one of claims  1  through  4 , comprising: 
 depositing a tungsten silicide layer on a polysilicon layer or an amorphous silicon layer which is formed on a silicon substrate; and  
 depositing a nitride layer on said tungsten silicide layer with an ammonia gas and a silane gas.