Method for adjusting spectral line width of narrow-band laser
An upper limit and a lower limit are preliminarily set for a spectral line width common to a plurality of narrow-band laser devices. When delivered or subjected to maintenance, the narrow-band laser device is caused to laser oscillate to detect its spectral line width before it is used as a light source for semiconductor exposure. A spectral line width adjustment unit provided in the narrow-band laser device is adjusted so that the spectral line width assumes a value between the upper limit and the lower limit. The present invention is able to suppress the variation in spectral line width such as E95 bandwidth caused by machine differences during the manufacture of the laser device, or by replacement or maintenance of the laser device, whereby the quality of integrated circuit patterns formed by the semiconductor exposure tool can be stabilized.
1. A narrow-band laser spectral line width adjustment method for adjusting the spectral line width of laser light emitted from a narrow-band laser device being used as a light source for semiconductor exposure, the method comprising:
setting in advance an upper limit and a lower limit for a spectral line width allowed in semiconductor exposure;
before semiconductor exposure and after said setting the upper limit and lower limit for the spectral line width, emitting the laser light from the narrow-band laser device;
after said emitting the laser light and before semiconductor exposure, detecting the spectral line width of the laser light using a monitor module arranged on an optical path of the laser light; and
after said detecting the spectral line width of the laser light and before semiconductor exposure, adjusting, based on the detected spectral line width, a distance between a cylindrical concave lens and a cylindrical convex lens arranged on an optical path at a front side inside a resonator of the narrow-band laser device by using a micrometer to set the spectral line width to a value between the upper limit and the lower limit.
2. The narrow-band laser spectral line width adjustment method of claim 1 ,
wherein central axes of the cylindrical concave lens and the cylindrical convex lens are respectively arranged on the optical path at the front side inside the laser resonator and mechanical axes thereof are respectively arranged so as to be parallel to a multiplicity of grooves of a grating arranged inside the resonator of the narrow-band laser device,
wherein either the cylindrical concave lens or the cylindrical convex lens is fixed on a movable plate, and
wherein said adjusting the distance between the cylindrical concave lens and the cylindrical convex lens includes moving the movable plate on a stage configured to be movable in parallel to the optical path.
3. The narrow-band laser spectral line width adjustment method of claim 2 , further comprising:
fixing the movable plate on the stage with a fixing screw after the distance between the cylindrical concave lens and the cylindrical convex lens is adjusted using the micrometer.
4. The narrow-band laser spectral line width adjustment method of claim 1 ,
wherein the narrow-band laser device comprises an oscillation stage laser for outputting the laser light, and one or more amplification stage chambers or amplification stage lasers for receiving, amplifying and outputting the laser light output from the oscillation stage laser, and
wherein the cylindrical concave lens and the cylindrical convex lens are arranged on a the laser optical path at the front side inside the laser resonator of the oscillation stage laser.
5. The narrow-band laser spectral line width adjustment method of claim 4 , wherein the monitor module is arranged in an output unit of the amplification stage chamber or the amplification stage laser.
6. The narrow-band laser spectral line width adjustment method of claim 1 , further comprising:
detecting a spectrum line width of the laser device after maintenance is performed on the laser device.
7. The narrow-band laser spectral line width adjustment method of claim 1 , wherein said setting operation includes setting the spectral line width of the laser device to a value between an upper limit and a lower limit.
8. The narrow-band laser spectral line width adjustment method of claim 1 , wherein variation in spectral line width is suppressed by setting the spectral line width of the laser device to the value between the upper limit and the lower limit.
9. The narrow-band laser spectral line width adjustment method of claim 1 , wherein said adjusting operation includes adjusting the spectral line width from a value below the lower limit to a value above the lower limit.
10. The narrow-band laser spectral line width adjustment method of claim 1 , wherein the upper limit and the lower limit are set based on a target value of the spectral line width.
11. The narrow-band laser spectral line width adjustment method of claim 1 , wherein the narrow-band laser device is a KrF excimer laser or an ArF excime laser.
12. The narrow-band laser spectral line width adjustment method of claim 1 , wherein said setting operation includes setting the upper limit and the lower limit for the spectral line width common to a plurality of narrow band laser devices.
13. The narrow-band laser spectral line width adjustment method of claim 12 , wherein the lower limit is greater than a minimum value of the spectral line width of the laser device.
14. The narrow-band laser spectral line width adjustment method of claim 1 , wherein the lower limit is greater than a minimum value of the spectral line width of the laser device.
15. The narrow-band laser spectral line width adjustment method of claim 1 , wherein the spectral line width is E95 width.
16. A narrow-band laser spectral line width adjustment method for adjusting the spectral line width of laser light emitted from a narrow-band laser device being used as a light source for semiconductor exposure, the method comprising:
performing maintenance on the narrow-band laser device;
setting in advance an upper limit and a lower limit for a spectral line width allowed in semiconductor exposure;
after said maintenance and said setting the upper limit and lower limit for the spectral line width, and before semiconductor exposure, emitting the laser light from the narrow-band laser device;
after said emitting the laser light and before semiconductor exposure, detecting the spectral line width of the laser light using a monitor module arranged on an optical path of the laser light; and
after said detecting the spectral line width of the laser light and before semiconductor exposure, adjusting, based on the detected spectral line width, a distance between a cylindrical concave lens and a cylindrical convex lens arranged on an optical path at a front side inside a resonator of the narrow-band laser device by using a micrometer to set the spectral line width to a value between the upper limit and the lower limit.
17. The narrow-band laser spectral line width adjustment method of claim 16 , wherein the spectral line width is E95 width.
18. A narrow-band laser spectral line width adjustment method for adjusting the spectral line width of laser light emitted from a narrow-band laser device being used as a light source for semiconductor exposure, the method comprising:
assembling the narrow-band laser device;
setting in advance an upper limit and a lower limit for a spectral line width allowed in semiconductor exposure;
after said assembling and said setting the upper limit and the lower limit, and before semiconductor exposure, emitting the laser light from the narrow-band laser device;
after said emitting the laser light and before semiconductor exposure, detecting the spectral line width of the laser light using a monitor module arranged on an optical path of the laser light; and
after said detecting the spectral line width of the laser light and before semiconductor exposure, adjusting, based on the detected spectral line width, a distance between a cylindrical concave lens and a cylindrical convex lens arranged on the optical path at a front side inside a resonator of the narrow-band laser device by using a micrometer to set the spectral line width to a value between the upper limit and the lower limit.
19. The narrow-band laser spectral line width adjustment method of claim 18 , wherein the spectral line width is E95 width.