Patent ID: 8804780

Claim:
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.