Method for manufacturing a semiconductor device
It is made possible to restrain generation of defects at the time of insulating film formation. A method for manufacturing a semiconductor device, includes: placing a semiconductor substrate into an atmosphere, thereby forming a nitride film on a surface of the semiconductor substrate, the atmosphere containing a first nitriding gas nitriding the surface of the semiconductor substrate and a first diluent gas not actually reacting with the semiconductor substrate, the ratio of the sum of the partial pressure of the first diluent gas and the partial pressure of the first nitriding gas to the partial pressure of the first nitriding gas being 5 or higher, and the total pressure of the atmosphere being 40 Torr or lower.
1. A method for manufacturing a semiconductor device, comprising:
exposing a silicon layer to a first atmosphere to form a first nitride layer on a surface of the silicon layer, the first atmosphere containing a first nitriding gas nitriding the surface of the silicon layer and a first diluent gas not actually reacting with the silicon layer during production, the ratio of the sum of the partial pressure of the first diluent gas and the partial pressure of the first nitriding gas to the partial pressure of the first nitriding gas being 5 or higher, and the total pressure of the first atmosphere being 3 Torr or higher but 40 Torr or lower; and
after forming of the first nitride layer on the surface of the silicon layer, exposing the silicon layer having the first nitride layer formed on the surface thereof to a second atmosphere containing a radical second nitriding gas to form a second nitride layer between the silicon layer and the first nitride layer.
2. The method for manufacturing a semiconductor device according to 1 , wherein the first nitriding gas is one of NH 3 gas, radical N* gas, and N 2 * gas.
3. The method for manufacturing a semiconductor device according to claim 1 , wherein the total pressure of the first atmosphere is 30 Torr or lower.
4. The method for manufacturing a semiconductor device according to claim 1 , wherein the first diluent gas contains N 2 gas.
5. The method for manufacturing a semiconductor device according to claim 1 , wherein the first diluent gas contains a component having natural vibration energy similar to atomic vibration energy at the interface between the silicon layer and the first nitride layer.
6. The method for manufacturing a semiconductor device according to claim 1 , further comprising:
performing heat treatment for the silicon layer exposed to an atmosphere of a gas not actually reacting with the silicon layer, after the first nitride layer film is formed on the surface of the silicon layer.
7. The method for manufacturing a semiconductor device according to claim 6 , wherein the gas not actually reacting with the silicon layer is N 2 gas or He gas.
8. The method for manufacturing a semiconductor device according to claim 1 , wherein, in the first atmosphere for forming the first nitride layer,
the ratio of the sum of the partial pressure of the first dilution gas and the partial pressure of the first nitriding gas to the partial pressure of the first nitriding gas is 10000 or lower.
9. The method for manufacturing a semiconductor device according to claim 1 , wherein the first nitride layer is formed at a temperature of 700° C. or more but 850° C. or less.
10. The method for manufacturing a semiconductor device according to claim 1 , wherein a film thickness of the first nitride layer is 4 Å or more but 1 nm or less.
11. The method for manufacturing a semiconductor device according to claim 1 , wherein the second nitriding gas is radical N* gas or radical N 2 * gas.
12. The method for manufacturing a semiconductor device according to claim 1 , wherein the first and second nitride layers are included in a tunnel insulating film of a floating-gate non-volatile memory.
13. The method for manufacturing a semiconductor device according to claim 1 , wherein the first and second nitride layers are included in a tunnel insulating film of a MONOS non-volatile memory.
14. The method for manufacturing a semiconductor device according to claim 1 , wherein the first and second nitride layers are included in a gate insulating film of a MISFET.
15. The method for manufacturing a semiconductor device according to claim 1 , wherein the exposing of the silicon layer having the first nitride layer formed on the surface thereof to the second atmosphere comprises forming a third nitride layer formed on the surface of the first nitride layer.
16. The method for manufacturing a semiconductor device according to claim 1 , wherein a film thickness of the first nitride layer is 7 Å or more but 1 nm or less.