Method for manufacturing a semiconductor substrate by laser irradiation
View Patent ↗An SOI substrate having a single crystal semiconductor layer the surface of which has high planarity is manufactured. A semiconductor substrate is doped with hydrogen to form a damaged region containing a large amount of hydrogen. After a single crystal semiconductor substrate and a supporting substrate are bonded to each other, the semiconductor substrate is heated to separate the single crystal semiconductor substrate in the damaged region. While a heated high-purity nitrogen gas is sprayed on a separation surface of a single crystal semiconductor layer which is separated from the single crystal semiconductor substrate and irradiation with a microwave is performed from the back side of the supporting substrate, the separation surface is irradiated with a laser beam. The single crystal semiconductor layer is melted by irradiation with the laser beam, so that the surface of the single crystal semiconductor layer is planarized and re-single-crystallization thereof is performed. In addition, the length of the melting time is increased by irradiation with the nitrogen gas and the microwave; thus, the re-single-crystallization is performed more efficiently.
1. A method for manufacturing a semiconductor substrate comprising the steps of:
irradiating a first part of a single crystal semiconductor layer fixed to a supporting substrate with a buffer layer interposed therebetween with a laser beam from a first side of the single crystal semiconductor layer;
spraying a heated nitrogen gas on the first part of the single crystal semiconductor layer from the first side of the single crystal semiconductor layer; and
irradiating a second part of the single crystal semiconductor layer with a microwave from a second side of the single crystal semiconductor layer which is the opposite side of the first side of the single crystal semiconductor layer,
wherein the first part of the single crystal semiconductor layer overlaps with the second part of the single crystal semiconductor layer, and
wherein the irradiation with the laser beam, the spraying of the heated nitrogen gas, and the irradiation with the microwave are performed simultaneously.
2. The method for manufacturing a semiconductor substrate according to claim 1 , wherein a time until the single crystal semiconductor layer in the first part which is irradiated with the laser beam is melted and recrystallized by the irradiation with the laser beam, the spraying of the heated nitrogen gas, and the irradiation with the microwave is greater than or equal to 200 nanoseconds and less than or equal to 1000 nanoseconds.
3. The method for manufacturing a semiconductor substrate according to claim 1 , wherein a concentration of oxygen contained in the nitrogen gas is less than or equal to 30 ppm.
4. The method for manufacturing a semiconductor substrate according to claim 1 , wherein a concentration of moisture contained in the nitrogen gas is less than or equal to 30 ppm.
5. The method for manufacturing a semiconductor substrate according to claim 1 , wherein a temperature of the single crystal semiconductor layer is heated to be greater than or equal to 400° C. and less than a strain point of the supporting substrate by spraying the heated nitrogen gas.
6. The method for manufacturing a semiconductor substrate according to claim 1 ,
wherein the heated nitrogen gas is ejected from an opening of a gas ejection portion, and
wherein the laser beam passes through the opening of the gas ejection portion.
7. The method for manufacturing a semiconductor substrate according to claim 1 ,
wherein the heated nitrogen gas having passed through a heated tube is sprayed on the first part of the single crystal semiconductor layer.
8. The method for manufacturing a semiconductor substrate according to claim 1 ,
wherein the heated nitrogen gas is at a temperature of greater than or equal to 450° C. and less than or equal to 625° C.
9. The method for manufacturing a semiconductor substrate according to claim 1 ,
wherein the microwave is scanned relatively to the single crystal semiconductor layer when the supporting substrate is transferred.
10. The method for manufacturing a semiconductor substrate according to claim 1 ,
wherein the supporting substrate is transferred relative to a dielectric that is incorporated into a stage, and
wherein the microwave transmits through the dielectric.
11. A method for manufacturing a semiconductor substrate comprising the steps of:
irradiating a first part of a semiconductor layer over a substrate with a laser beam from a first side of the semiconductor layer;
spraying a heated nitrogen gas on the first part of the semiconductor layer from the first side of the semiconductor layer; and
irradiating a second part of the semiconductor layer with a microwave from a second side of the semiconductor layer which is the opposite side of the first side of the semiconductor layer,
wherein the first part of the semiconductor layer overlaps with the second part of the semiconductor layer, and
wherein the irradiation with the laser beam, the spraying of the heated nitrogen gas, and the irradiation with the microwave are performed simultaneously.
12. The method for manufacturing a semiconductor substrate according to claim 11 , wherein a time until the semiconductor layer in the first part which is irradiated with the laser beam is melted and recrystallized by the irradiation with the laser beam, the spraying of the heated nitrogen gas, and the irradiation with the microwave is greater than or equal to 200 nanoseconds and less than or equal to 1000 nanoseconds.
13. The method for manufacturing a semiconductor substrate according to claim 11 , wherein a concentration of oxygen contained in the nitrogen gas is less than or equal to 30 ppm.
14. The method for manufacturing a semiconductor substrate according to claim 11 , wherein a concentration of moisture contained in the nitrogen gas is less than or equal to 30 ppm.
15. The method for manufacturing a semiconductor substrate according to claim 11 , wherein a temperature of the semiconductor layer is heated to be greater than or equal to 400° C. and less than a strain point of the substrate by spraying the heated nitrogen gas.
16. The method for manufacturing a semiconductor substrate according to claim 11 ,
wherein the heated nitrogen gas is ejected from an opening of a gas ejection portion, and
wherein the laser beam passes through the opening of the gas ejection portion.
17. The method for manufacturing a semiconductor substrate according to claim 11 ,
wherein the heated nitrogen gas having passed through a heated tube is sprayed on the first part of the semiconductor layer.
18. The method for manufacturing a semiconductor substrate according to claim 11 ,
wherein the heated nitrogen gas is at a temperature of greater than or equal to 450° C. and less than or equal to 625° C.
19. The method for manufacturing a semiconductor substrate according to claim 11 ,
wherein the microwave is scanned relatively to the semiconductor layer when the substrate is transferred.
20. The method for manufacturing a semiconductor substrate according to claim 11 ,
wherein the substrate is transferred relative to a dielectric that is incorporated into a stage, and
wherein the microwave transmits through the dielectric.