| 摘要 |
<p>PURPOSE:To provide an optical heterodyne system alignment equipment capable of restraining the influence of gap length between aligned objects. CONSTITUTION:At least a pair of diffraction gratings 13a, 14a are installed in the facing relation to a mask and a wafer. Two light beams 15, 16 different in frequency are applied to the diffraction grating 13a, in the manner in which the right and the left are symmetic, setting the surface intersecting rectangularly to the position alignment direction as a boundary. A diffraction light beam IM(0.1) having a specified order of diffraction out of diffraction light beams obtained by the irradiation is used as position information. In this optical heterodyne system alignment equipment, the effective width LWy of the diffraction grating in the direction rectangular to the alignment direction is set equal to or less than LWy=3XtanthetaXZ (where theta=sin<-1>(lambda/Py2)). In the above formula, Py2 is the grating pitch in the direction vertical to the alignment direction, lambdais the wavelength of the shorter wavelength light beam out of the two light beams, and Z is the minimum gap length between a mask and a wafer.</p> |
