Method of manufacturing silicon-on-insulator wafers
View Patent ↗A method is provided for preparing multilayer semiconductor structures, such as silicon-on-insulator wafers, having reduced warp and bow. Reduced warp multilayer semiconductor structures are prepared by forming a dielectric structure on the exterior surfaces of a bonded pair of a semiconductor device substrate and a semiconductor handle substrate having an intervening dielectric layer therein. Forming a dielectric layer on the exterior surfaces of the bonded pair offsets stresses that may occur within the bulk of the semiconductor handle substrate due to thermal mismatch between the semiconductor material and the intervening dielectric layer as the structure cools from process temperatures to room temperatures.
1. A method of preparing a multilayer semiconductor structure, the method comprising the following steps in order:
(a) forming a first dielectric layer on a front surface of a semiconductor device substrate, the semiconductor device substrate comprising two major, generally parallel surfaces, one of which is the front surface of the semiconductor device substrate and the other of which is a back surface of the semiconductor device substrate, a circumferential edge joining the front and back surfaces of the semiconductor device substrate, and a central plane between the front and back surfaces of the semiconductor device substrate;
(b) bonding the front surface of the semiconductor device substrate having the first dielectric layer to a front surface of a handle substrate to thereby form a bonded structure, wherein the handle substrate comprises two major, generally parallel surfaces, one of which is the front surface of the handle substrate and the other of which is a back surface of the handle substrate, a circumferential edge joining the front and back surfaces of the handle substrate, and a central plane between the front and back surfaces of the handle substrate;
(c) forming a second dielectric layer on the back surface of the handle substrate ; and
(d) thinning the semiconductor device substrate.
2. The method of claim 1 wherein the semiconductor device substrate comprises a material selected from the group consisting of silicon, silicon carbide, silicon germanium, silicon nitride, silicon dioxide, gallium arsenic, gallium nitride, indium phosphide, indium gallium arsenide, germanium, and combinations thereof.
3. The method of claim 1 wherein the semiconductor device substrate comprises a silicon wafer sliced from a single crystal silicon ingot grown by the Czochralski method.
4. The method of claim 3 wherein the first dielectric layer formed on the front surface of the semiconductor device substrate comprises silicon dioxide.
5. The method of claim 4 wherein the first dielectric layer comprising silicon dioxide has a thickness between about 50 nanometers and about 5000 nanometers.
6. The method of claim 1 wherein the handle substrate is a silicon wafer.
7. The method of claim 6 wherein the handle substrate further comprises a third dielectric layer on the front surface thereof.
8. The method of claim 7 wherein the third dielectric layer comprises silicon dioxide and has a thickness between about 50 nanometers and about 5000 nanometers.
9. The method of claim 6 wherein the second dielectric layer formed on the back surface of the handle substrate during step (c) comprises silicon dioxide.
10. The method of claim 9 wherein the second dielectric layer comprising silicon dioxide has a thickness between about 50 nanometers and about 5000nanometers.
11. The method of claim 1 wherein step (c) further comprises concurrent formation of a fourth dielectric layer on the back surface of the semiconductor device substrate.
12. The method of claim 11 wherein both the second dielectric layer formed on the back surface of the handle substrate and fourth dielectric layer on the back surface of the semiconductor device substrate comprises silicon dioxide.
13. The method of claim 12 wherein the second and fourth dielectric layers comprising silicon dioxide have thicknesses between about 50 nanometers and about 5000 nanometers.
14. The method of claim 13 wherein the semiconductor device substrate is thinned by grinding, etching, polishing or any combination of such techniques the back surface of the semiconductor device substrate.
15. The method of claim 14 wherein after step (d), the thinned semiconductor device substrate has a thickness between about 3 micrometers and about 70 micrometers.
16. The method of claim 1 wherein the multilayer semiconductor structure has warpage no greater than 30 micrometers.