Method for forming semiconductor films at desired positions on a substrate
View Patent ↗A semiconductor film formation method allowing a single-crystal semiconductor film to be formed at a desired position on a substrate with reliability is disclosed. After preparing the substrate having a non-single-crystal semiconductor film formed thereon and an optical mask having a predetermined pattern, a projection area of the optical mask is relatively positioned at the desired position on the substrate. Thereafter, the desired position of the non-single-crystal semiconductor film is irradiated with laser light through the optical mask to change an irradiated portion of the non-single-crystal semiconductor film to the single-crystal semiconductor film. Then, an insulation film is formed on at least the single-crystal semiconductor film.
1. A method for forming a first-property semiconductor film at a desired position on a substrate, comprising the steps of:
preparing the substrate having a second-property semiconductor film formed thereon in a gas atmosphere with a pressure of substantially atmospheric pressure;
b) preparing an optical mask having a predetermined pattern on another substrate which is apart from the substrate;
c) relatively positioning a projection area of the optical mask at the desired position on the substrate;
d) irradiating the desired position of the second-property semiconductor film with laser light through the optical mask to change an irradiated portion of the second-property semiconductor film to the first-property semiconductor film; and
e) forming an insulation film on the first-property semiconductor film and the second-property semiconductor film;
wherein the optical mask has an alignment mark pattern, wherein, in the step (d), an alignment mark corresponding to the alignment mark pattern is formed by the irradiation of the desired portion of the second-property semiconductor film with the laser light through the optical mask to change the irradiated portion of the second-property semiconductor film to the first-property semiconductor film, and wherein the alignment mark is visible due to a difference in optical characteristic between the first-property semiconductor film and the second-property semiconductor film.
2. The method according to claim 1 , wherein a positioning process after the step (d) is performed with reference to the alignment mark.
3. The method according to claim 1 , wherein the first-property semiconductor film is a crystalline semiconductor film and the second-property semiconductor film is an amorphous semiconductor film.
4. The method according to claim 3 , further comprising the step of:
(f) forming an island comprised of the insulation film and the crystalline semiconductor film by a patterning process, wherein the crystalline semiconductor film of the island is a single-crystal semiconductor film used for source, drain, and channel regions of a field effect transistor.