Method of manufacturing an ohmic electrode containing titanium, aluminum and silicon on a silicon carbide surface
To provide a method of manufacturing a semiconductor device that can be in contact with both of an n-type SiC region and a p-type SiC region and can suppress increase in contact resistance due to oxidation, a method of manufacturing a semiconductor device includes the steps of preparing a SiC layer, and forming an ohmic electrode on a main surface of the SiC layer. The step of forming the ohmic electrode includes the steps of forming a conductor layer which will become the ohmic electrode on the main surface of the SiC layer, and performing heat treatment such that the conductor layer becomes the ohmic electrode. After the step of performing the heat treatment, a temperature of the ohmic electrode when a surface of the ohmic electrode is exposed to an atmosphere containing oxygen is set to 100° C. or lower.
1. A method of manufacturing a semiconductor device, comprising the steps of:
preparing a SiC layer composed of silicon carbide;
forming an n-type region and a p-type region in said SiC laver; and
forming an ohmic electrode on a main surface of said SiC layer,
wherein the step of forming said ohmic electrode includes the steps of forming a conductor layer having an aluminum film and a titanium film which will become said ohmic electrode on the main surface of said SiC layer, and performing heat treatment such that said conductor layer becomes said ohmic electrode,
in the step of forming said ohmic electrode, said conductor layer having the titanium film, the aluminum film, and a silicon film is formed such that the titanium film is to be in contact with both of said n-type region and said p-type region,
in the step of forming said ohmic electrode, an ohmic contact electrode containing titanium, aluminum, and silicon is formed, and
after the step of performing said heat treatment, a temperature of said ohmic electrode when a surface of said ohmic electrode is exposed to an atmosphere containing oxygen is set to 100° C. or lower.
2. The method of manufacturing a semiconductor device according to claim 1 , further comprising the step of forming an electrode pad on one main surface of said ohmic electrode after the step of forming said ohmic electrode.
3. The method of manufacturing a semiconductor device according to claim 2 , comprising the step of removing an oxidized region formed in the one main surface of said ohmic electrode after the step of forming said ohmic electrode and before the step of forming said electrode pad.
4. The method of manufacturing a semiconductor device according to claim 2 , comprising the step of maintaining the one main surface of said ohmic electrode at 100° C. or lower in the atmosphere containing oxygen after the step of forming said ohmic electrode and before the step of forming said electrode pad.
5. The method of manufacturing a semiconductor device according to claim 2 , comprising the step of forming a protective film on the one main surface of said ohmic electrode after the step of forming said ohmic electrode and before the step of forming said electrode pad.
6. The method of manufacturing a semiconductor device according to claim 1 , wherein said SiC layer contains an n-type impurity.
7. The method of manufacturing a semiconductor device according to claim 1 , wherein the titanium film has a thickness of not smaller than 100 Å and not greater than 400 Å.
8. The method of manufacturing a semiconductor device according to claim 1 , wherein the silicon film has a thickness of not smaller than 100 Å and not greater than 500 Å.
9. The method of manufacturing a semiconductor device according to claim 1 , wherein the aluminum film is at least 1.5 times and at most 6 times as thick as the titanium film.
10. The method of manufacturing a semiconductor device according to claim 1 , wherein, in the step of forming said ohmic electrode, the titanium film, the aluminum film, and the silicon film are formed in this order.