Method for filling a contact hole having a small diameter and a large aspect ratio
A method for manufacturing a semiconductor device having a semiconductor substrate with a contact hole filled by an aluminum-containing thin film. This manufacturing method includes a step of forming a silicon-containing thin film in a region having a predetermined area including the inner surface of the contact hole on the surface of the semiconductor substrate, an step of forming an aluminum-containing thin film on the surface of the semiconductor substrate on which the silicon-containing thin film is formed, and a step of heating the semiconductor substrate on which the aluminum-containing thin film is formed to such a temperature as to cause silicon to diffuse with respect to aluminum.
1. A method for manufacturing a semiconductor device having a semiconductor substrate with a contact hole filled by an aluminum-containing thin film, comprising the steps of:
forming a silicon-containing thin film in a region having a predetermined area including the inner surface of the contact hole on the surface of the semiconductor substrate;
forming an aluminum-containing thin film on the surface of the semiconductor substrate on which the silicon-containing thin film is formed; and
heating the semiconductor substrate on which the aluminum-containing thin film is formed to such a temperature as to cause silicon to diffuse with respect to aluminum;
wherein the semiconductor substrate is provided with a plurality of cells each including the contact hole, and
the ratio of the amount of silicon contained in the silicon-containing thin film formed in the region having the predetermined area per unit cell to the amount of aluminum supplied to a unit cell in the step of forming the aluminum thin film is not less than 0.1% and not more than 2% by atomic ratio.
2. A method for manufacturing a semiconductor device as claimed in claim 1 , wherein the step of forming an aluminum-containing thin film and the step of heating the semiconductor substrate are carried out simultaneously.
3. A method for manufacturing a semiconductor device as claimed in claim 1 , wherein the step of heating the semiconductor substrate is carried out after completing the step of forming the aluminum thin film.
4. A method for manufacturing a semiconductor device as claimed in claim 1 , wherein the step of forming a silicon-containing thin film in the region having the predetermined area includes the steps of:
forming a silicon-containing thin film in a region larger than the predetermined area; and
removing the silicon-containing thin film so that the area of the silicon-containing thin film can become the abovementioned predetermined area.
5. A method for manufacturing a semiconductor device as claimed in claim 4 , wherein the step of removing the silicon-containing thin film includes a step of removing the silicon-containing thin film using a mask having a predetermined pattern.
6. A method for manufacturing a semiconductor device as claimed in claim 4 , wherein the step of removing the silicon-containing thin film includes a step of removing the silicon-containing thin film by etching.
7. A method for manufacturing a semiconductor device as claimed in claim 1 , wherein the predetermined area is not more than 99% of the area of the aluminum-containing thin film formed in the step of forming the aluminum thin film.
8. A method for manufacturing a semiconductor device as claimed in claim 1 , wherein the step of heating the semiconductor substrate includes a step of heating the semiconductor substrate to 380° C.˜570° C.