1. An information reproducing apparatus capable of reproducing an information storage medium storing BCA information recorded in a first area and RF information recorded in a second area on an outer side of the first area, the information reproducing apparatus comprising:
an optical pickup for radiating laser light onto the first and second areas of the information storage medium and detect reflected light thereof;
a reproducing system unit for reproducing an RF signal and a BCA signal on the basis of the reflected light detected by the optical pickup; and
a focus control unit for controlling focusing by setting a focus position of the optical pickup to a signal layer of the optical disc when the RF signal is to be reproduced and control defocusing by displacing the focus position of the optical pickup from the signal layer when the BCA signal is to be reproduced, thereby equivalently suppressing a high-frequency component of the BCA signal.
2. The information reproducing apparatus according to claim 1, wherein the reproducing system unit processes both the RF signal and the BCA signal in the same route from the optical pickup to a digital converter.
3. The information reproducing apparatus according to claim 1, wherein the focus control unit controls defocusing by setting the focus position to a point under the signal layer.
4. The information reproducing apparatus according to claim 1, further comprising:
a rotation control unit for setting a rotation speed of the optical disc to a higher speed than that for reproducing the RF signal when the BCA signal is reproduced.
5. The information reproducing apparatus according to claim 4, further comprising:
an error measuring unit for measuring a symbol error rate of the BCA signal,
wherein the rotation control unit sets the rotation speed to high if the symbol error rate exceeds a predetermined threshold.
6. The information reproducing apparatus according to claim 4, further comprising:
an error measuring unit for measuring a symbol error rate of the BCA signal,
wherein the focus control unit controls defocusing if the symbol error rate exceeds a predetermined threshold.
7. The information reproducing apparatus according to claim 1, wherein the focus control unit is capable of changing the focus position for defocusing, thereby being capable of changing a cutoff frequency to equivalently suppress a high-frequency component of the BCA signal.
8. An information reproducing method capable of reproducing an information storage medium storing BCA information recorded in a first area and RF information recorded in a second area on an outer side of the first area, the information reproducing method comprising the steps of:
radiating laser light onto the first and second areas of the information storage medium and detecting reflected light thereof by an optical pickup;
reproducing an RF signal and a BCA signal on the basis of the reflected light detected by the optical pickup;
controlling focusing by setting a focus position of the optical pickup to a signal layer of the optical disc when the RF signal is to be reproduced; and
controlling defocusing by displacing the focus position of the optical pickup from the signal layer when the BCA signal is to be reproduced, thereby equivalently suppressing a high-frequency component of the BCA signal.
9. The information reproducing method according to claim 8, wherein the step of reproducing processes both the RF signal and the BCA signal in the same route from the optical pickup to a digital converter.
10. The information reproducing method according to claim 8, wherein the step of controlling defocusing controls defocusing by setting the focus position to a point under the signal layer.
11. The information reproducing method according to claim 8, further comprising:
setting a rotation speed of the optical disc to a higher speed than that for reproducing the RF signal when the BCA signal is reproduced.
12. The information reproducing method according to claim 11, further comprising:
measuring a symbol error rate of the BCA signal,
wherein the step of setting sets the rotation speed to high if the symbol error rate exceeds a predetermined threshold.
13. The information reproducing method according to claim 11, further comprising:
measuring a symbol error rate of the BCA signal,
wherein the step of controlling defocusing controls defocusing if the symbol error rate exceeds a predetermined threshold.
14. The information reproducing method according to claim 8, wherein the step of controlling defocusing is capable of changing the focus position for defocusing, thereby being capable of changing a cutoff frequency to equivalently suppress a high-frequency component of the BCA signal.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for manufacturing a semiconductor device, comprising the steps of:
introducing an impurity into a silicon carbide layer;
forming a carbon layer in a surface layer portion of said silicon carbide layer having said impurity introduced therein, by selectively removing silicon from said surface layer portion; and
activating said impurity by heating said silicon carbide layer having said carbon layer formed therein.
2. The method for manufacturing a semiconductor device according to claim 1, wherein, in the step of forming said carbon layer, the silicon is selectively removed by reaction of a halogen element and the silicon.
3. The method for manufacturing a semiconductor device according to claim 2, wherein, in the step of forming said carbon layer, the silicon is selectively removed by heating said silicon carbide layer in an atmosphere including a gas containing the halogen element.
4. The method for manufacturing a semiconductor device according to claim 2, wherein, in the step of forming said carbon layer, the silicon is selectively removed by holding said silicon carbide layer in a plasma containing the halogen element.
5. The method for manufacturing a semiconductor device according to claim 1, further comprising the step of oxidizing and removing said carbon layer after the step of activating said impurity.
6. The method for manufacturing a semiconductor device according to claim 1, wherein, in the step of activating said impurity, said silicon carbide layer is heated to a temperature range of not less than 1600\xb0 C. and not more than 1900\xb0 C.