Method of forming carbon-containing silicon nitride layer

Abstract

A method for forming a carbon-containing silicon nitride layer with superior uniformity by low pressure chemical vapor deposition (LPCVD) using disilane, ammonia and at least one carbon-source precursor as reactant gases is provided.

What is claimed is: 
     
         1 . A method for forming a gate, comprising:
 providing a substrate having a gate dielectric layer thereon;   forming a conductive layer on the gate dielectric layer;   patterning the conductive layer and the gate dielectric layer to form a gate electrode;   forming offset spacers on the sidewalls of the gate electrode, the material of the offset spacers is carbon-containing silicon nitride;   forming a material layer over the substrate and covering the gate electrode, wherein the material layer comprises a carbon-containing silicon nitride layer formed by low pressure chemical vapor deposition (LPCVD); and   etching back the material layer to form spacers over sidewalls of the gate electrode.   
     
     
         2 . The method according to  claim 1 , wherein the carbon-containing silicon nitride layer has a carbon content higher than 9%. 
     
     
         3 . The method according to  claim 2 , wherein the carbon-containing silicon nitride layer has a carbon content ranging from about 9% to about 30%. 
     
     
         4 . The method according to  claim 1 , wherein the carbon-containing silicon nitride layer is formed by a single wafer tool. 
     
     
         5 . The method according to  claim 1 , wherein the carbon-containing silicon nitride layer is formed by using reactant gases including at least a carbon-source precursor, and the carbon-source precursor is selected from the group consisting of TEASAT (triethylarsenate, C 6 H 15 AsO 4 ), Trans-LC (C 2 H 2 Cl 2 ), TCS (trichlorosilane, SiHCl 3 ), TMAl (trimethyl aluminum, Al(CH 3 ) 3 ), C 2 H 4 , C 3 H 6 , TEB (triethylborate, B(OC 2 H 5 ) 3 ), TEPO (triethylphosphate, PO(C 2 H 5 O) 3 ), TDMAT (tetrakis-dimethylamino titanium, Ti[N(CH 3 ) 2 ] 4 ) and combinations thereof. 
     
     
         6 . The method according to  claim 5 , wherein a gas flow rate of the carbon-source precursor is less than 2 slm (standard liter per minute). 
     
     
         7 . The method according to  claim 1 , wherein a reaction pressure of the LPCVD for forming the carbon-containing silicon nitride layer is below 250 Torr. 
     
     
         8 . The method according to  claim 1 , wherein a reaction temperature of the LPCVD for forming the carbon-containing silicon nitride layer is below 800° C. 
     
     
         9 . The method according to  claim 1 , the step of forming the offset spacers comprises:
 forming a carbon-containing silicon nitride offset material layer over the substrate; and   etching back the carbon-containing silicon nitride offset material layer to form the offset spacers on the sidewalls of the gate electrode.   
     
     
         10 . The method according to  claim 9 , wherein the carbon-containing silicon nitride offset material layer is formed by low pressure chemical vapor deposition (LPCVD) using disilane, ammonia and at least a carbon-source precursor as reactant gases. 
     
     
         11 . The method according to  claim 10 , wherein the carbon-source precursor is selected from the group consisting of TEASAT (triethylarsenate, C 6 H 15 AsO 4 ), Trans-LC (C 2 H 2 Cl 2 ), TCS (trichlorosilane, SiHCl 3 ), TMAl (trimethyl aluminum, Al(CH 3 ) 3 ), C 2 H 4 , C 3 H 6 , TEB (triethylborate, B(OC 2 H 5 ) 3 ), TEPO (triethylphosphate, PO(C 2 H 5 O) 3 ), TDMAT (tetrakis-dimethylamino titanium, Ti[N(CH 3 ) 2 ] 4 ) and combinations thereof. 
     
     
         12 . The method according to  claim 10 , wherein a reaction pressure of the LPCVD for forming the carbon-containing silicon nitride offset material layer is below 250 Torr. 
     
     
         13 . The method according to  claim 10 , wherein a reaction temperature of the LPCVD for forming the carbon-containing silicon nitride offset material layer is below 800° C. 
     
     
         14 . The method according to  claim 9 , wherein the carbon-containing silicon nitride offset material layer has a carbon content higher than 9%. 
     
     
         15 . The method according to  claim 14 , wherein the carbon-containing silicon nitride offset material layer has a carbon content ranging from about 9% to about 30%. 
     
     
         16 . The method according to  claim 9 , wherein the carbon-containing silicon nitride offset material layer is formed by a single wafer tool.