Semiconductor device manufacturing method
A first nickel film is deposited inside a contact hole of an interlayer dielectric formed on an n + -type SiC substrate. Irradiation with a first laser is carried out, forming an Ohmic contact with a silicon carbide semiconductor. A second nickel film and a front surface electrode film are deposited on the first nickel film, forming a source electrode. The back surface of the n + -type SiC substrate is ground, and a third nickel film is formed on the ground back surface of the n + -type SiC substrate. Irradiation with a second laser is carried out, forming an Ohmic contact with the silicon carbide semiconductor. A fourth nickel film and a back surface electrode film are deposited on the third nickel film, forming a drain electrode. By so doing, it is possible to prevent electrical characteristic deterioration of a semiconductor device, and to prevent warping and cracking of a wafer.
1. A semiconductor device manufacturing method, comprising:
a dielectric formation step of forming a dielectric on a surface of a semiconductor substrate;
a step of selectively removing the dielectric, thereby selectively exposing the surface of the semiconductor substrate;
a first electrode film formation step of forming a first nickel electrode film of a thickness of 20 nm to 100 nm on the exposed surface of the semiconductor substrate;
an annealing step of forming an Ohmic contact between the first nickel electrode film and semiconductor substrate by irradiating a pattern portion of the first nickel electrode film with a laser of a wavelength of 200 nm to 600 nm from a surface of the first nickel electrode film, thereby annealing a junction portion of the first nickel electrode film and semiconductor substrate;
a second electrode film formation step of forming a second nickel electrode film on the first nickel electrode film;
a third electrode film formation step of forming a front surface electrode film on the second nickel electrode film; and
a source electrode formation step including carrying out another annealing step to form a source electrode film formed by the first nickel electrode film, the second nickel electrode film and the front surface electrode film.
2. The semiconductor device manufacturing method according to claim 1 , wherein the annealing step is such that the laser is concentrated through a lens, and irradiation with the laser is carried out in a state wherein a spot diameter of the laser is brought near a diffraction limit.
3. The semiconductor device manufacturing method according to claim 1 , wherein an energy density of the laser is 1.6 J/cm 2 to 2.4 J/cm 2 , and an overlapping rate of the laser is 70% or less.
4. The semiconductor device manufacturing method according to claim 1 , wherein the dielectric and first nickel electrode film are formed on a front surface of the semiconductor substrate, and
the semiconductor device manufacturing method further comprises a thinning step of grinding a back surface of the semiconductor substrate, thereby reducing a thickness of the semiconductor substrate, after the annealing step.
5. The semiconductor device manufacturing method according to claim 1 , wherein the semiconductor substrate is formed of silicon, silicon carbide, or gallium nitride.
6. The semiconductor device manufacturing method according to claim 2 , wherein the dielectric and the first nickel electrode film are formed on a front surface of the semiconductor substrate, and
the semiconductor device manufacturing method further comprises a thinning step of grinding a back surface of the semiconductor substrate, thereby reducing a thickness of the semiconductor substrate, after the annealing step.
7. The semiconductor device manufacturing method according to claim 3 , wherein the dielectric and the first nickel electrode film are formed on a front surface of the semiconductor substrate, and
the semiconductor device manufacturing method further comprises a thinning step of grinding a back surface of the semiconductor substrate, thereby reducing a thickness of the semiconductor substrate, after the annealing step.
8. The semiconductor device manufacturing method according to claim 2 , wherein the semiconductor substrate is formed of silicon, silicon carbide, or gallium nitride.
9. The semiconductor device manufacturing method according to claim 3 , wherein the semiconductor substrate is formed of silicon, silicon carbide, or gallium nitride.
10. The semiconductor device manufacturing method according to claim 4 , wherein the semiconductor substrate is formed of silicon, silicon carbide, or gallium nitride.
11. A method, comprising:
forming a first electrode film of a thickness substantially between 20 nm and 100 nm on a portion of a semiconductor device corresponding to a source;
annealing a junction portion between the first electrode film and a substrate of the semiconductor device by selectively irradiating the first electrode film with radiation having a wavelength substantially between 200 nm and 600 nm;
forming a second electrode film on the first electrode film;
forming a front surface electrode film on the second electrode film; and
annealing to form a source electrode from the first electrode film, the second electrode film and the front surface electrode film.
12. The method of claim 11 , wherein the selectively irradiating comprises concentrating the radiation to form a spot of a predetermined diameter on the first electrode film.
13. The method of claim 12 , wherein the predetermined diameter is based on a diffraction limit.
14. The method of claim 13 , wherein the concentrating the radiation comprises passing the radiation through a lens, and the diffraction limit is based at least partly on characteristics of the lens.
15. The method of claim 11 , wherein the first electrode film is formed in a contact hole of an interlayer dielectric.