Method for forming silicon nitride passivation film, method for manufacturing semiconductor device and semiconductor device

Abstract

A method of forming a silicon nitride passivation film on a nitride semiconductor layer is comprising steps of, introducing a substrate including the nitride semiconductor layer into a reaction furnace, replacing an atmosphere in the reaction furnace from air to an ammonia (NH3) atmosphere or to a hydrogen (H2) atmosphere, raising a temperature in the reaction furnace to a first temperature, maintaining both the temperature in the reaction furnace at the first temperature and the atmosphere in the reaction furnace at the NH3 atmosphere or the H2 atmosphere for three minutes or more, lowering the temperature in the reaction furnace to a second temperature lower than the first temperature, and forming the silicon nitride passivation film by supplying dichlorosilane (SiH2Cl2) into the reaction furnace under the first pressure of 100 Pa or less in the reaction furnace.

What is claimed is: 
     
         1 . A method of forming a silicon nitride passivation film on a nitride semiconductor layer, comprising steps of:
 introducing a substrate including the nitride semiconductor layer into a reaction furnace;   replacing an atmosphere in the reaction furnace from air to an ammonia (NH 3 ) atmosphere or to a hydrogen (H 2 ) atmosphere;   raising a temperature in the reaction furnace to a first temperature;   maintaining both the temperature in the reaction furnace at the first temperature and the atmosphere in the reaction furnace at the NH 3  atmosphere or the H 2  atmosphere for three minutes or more;   lowering the temperature in the reaction furnace to a second temperature lower than the first temperature; and   forming the silicon nitride passivation film by supplying dichlorosilane (SiH 2 Cl 2 ) into the reaction furnace under the first pressure of 100 Pa or less in the reaction furnace.   
     
     
         2 . The method of forming the silicon nitride passivation film according to  claim 1 , wherein the step of maintaining both the temperature and the atmosphere also maintains the pressure in the reaction furnace at a second pressure greater than the first pressure. 
     
     
         3 . The method of forming the silicon nitride passivation film according to  claim 2 , wherein the second pressure is 300 Pa or more. 
     
     
         4 . The method of forming the silicon nitride passivation film according to  claim 1 , wherein the second temperature is 700° C. or more and the first temperature is at least 20° C. higher than the second temperature. 
     
     
         5 . The method of forming the silicon nitride passivation film according to  claim 1 , wherein the first temperature is 750° C. or more and 900° C. or less. 
     
     
         6 . The method of forming the silicon nitride passivation film according to  claim 1 , wherein the step of lowering the temperature reduces the pressure in the reaction furnace to the first pressure. 
     
     
         7 . A method of manufacturing a semiconductor device using a nitride semiconductor as a main constituent material, comprising steps of:
 forming a semiconductor stacking structure including a nitride semiconductor layer on the substrate;   forming a silicon nitride passivation film on the semiconductor stacking structure using the method according to  claim 1 ;   forming an opening in the silicon nitride passivation film; and   forming an electrode on the semiconductor stacking structure through the opening.   
     
     
         8 . A semiconductor device comprising:
 a substrate;   a semiconductor stacking portion formed on the substrate, which includes a plurality of nitride semiconductor layers;   a silicon nitride passivation film covering the surface of the semiconductor stacking portion; and   oxygen atoms existing at an interface between the silicon nitride passivation film and the semiconductor stacking portion;   wherein the interfacial oxygen content of the oxygen atoms is in 0.6×10 15  atom/cm 2  or less.   
     
     
         9 . The semiconductor device according to  claim 8 , wherein the oxygen atoms exist as silicon oxynitride (Si 2 N 2 O). 
     
     
         10 . A method of forming a silicon nitride passivation film on a nitride semiconductor layer, comprising steps of:
 introducing a substrate including the nitride semiconductor layer into a reaction furnace;   replacing an atmosphere in the reaction furnace from air to a hydrogen (H 2 ) atmosphere;   raising a temperature in the reaction furnace to a first temperature;   maintaining the temperature in the reaction furnace at the first temperature;   lowering the temperature in the reaction furnace to a second temperature lower than or equal to the first temperature; and   forming the silicon nitride passivation film by supplying dichlorosilane (SiH 2 Cl 2 ) into the reaction furnace under the first pressure of 100 Pa or less in the reaction furnace.   
     
     
         11 . The method of forming the silicon nitride passivation film according to  claim 10 , wherein the step of maintaining the temperature also maintains a partial pressure of H 2  in the reaction furnace at 0.5% or more. 
     
     
         12 . The method of forming the silicon nitride passivation film according to  claim 10 , wherein the step of maintaining the temperature also maintains the pressure in the reaction furnace at 300 Pa or more. 
     
     
         13 . The method of forming the silicon nitride passivation film according to  claim 10 , wherein the step of maintaining the temperature maintains the temperature in the reaction furnace at the first temperature for two minutes or more.