Alignment apparatus in projection exposure apparatus

An alignment apparatus, which is set in an exposure apparatus having a projection optical system for projecting a projection pattern formed on a mask onto a substrate under exposure light and which performs relative alignment between said mask and said substrate, comprising:

• alignment light irradiating system for forming a pair of two beams from each of light beams of plural wavelengths different from that of said exposure light to obtain a plural sets of beam pairs and splitting said beam pairs into two portions to obtain a first irradiation beam and a second irradiation beam, said alignment light irradiating system irradiating said first irradiation beam onto a first alignment mark formed on said mask with two beams in each beam pair being incident at substantially equal incident angles, and said alignment light irradiating system irradiating said second irradiation beam onto a second alignment mark on said substrate through a transmission window formed in a portion on said mask and then through said projection optical system;
• a plurality of chromatic aberration correction optical elements provided on or near a Fourier transform plane to said projection pattern formed on said mask in said projection optical system and in an optical path of said second irradiation beam irradiated onto said second alignment mark, said chromatic aberration correction optical elements deflecting said beam pairs in said second irradiation beam to make two beams in each beam pair incident at substantially equal incident angles into said second alignment mark on said substrate;
• first photoelectric detector for receiving beams of first diffracted light emerging at a substantially same direction from said first alignment mark to generate a first signal corresponding to said first diffracted light;
• second photoelectric detector for receiving beams of second diffracted light emerging at a substantially same direction from said second alignment mark to generate a second signal corresponding to said second diffracted light;
• and
• controller for controlling the relative alignment between said mask and said substrate, based on said first and second signal.

An alignment apparatus, which is set in an exposure apparatus having a projection optical system for projecting a projection pattern formed on a mask onto a substrate under exposure light and which performs relative alignment between said mask and said substrate, comprising:

• alignment light irradiating system for irradiating a beam pair with a wavelength different from that of said exposure light through said projection optical system onto a specific alignment mark on said substrate;
• a plurality of first chromatic aberration correction optical elements sets on or near a Fourier transform plane to said projection pattern formed on said mask in said projection optical system and in optical paths of said beam pair, said first chromatic aberration correction optical elements deflecting said beam pair to make two beams therein incident at substantially equal incident angles into said specific alignment mark on said substrate;
• photoelectric detector for receiving diffracted light including groups of diffracted beams, group by group, said diffracted light emerging from said specific alignment mark when said beam pair is irradiated onto said specific alignment mark through said plurality of first chromatic aberration correction optical elements and diffracted thereby, and returning in said projection optical system as the groups of diffracted beams, each group of beams emerging in a substantially same direction, said photoelectric detector then generating signals corresponding to the diffracted light;
• a plurality of second chromatic aberration correction optical elements set on or near the Fourier transform plane in said projection optical system and in an optical path of said diffracted light to deflect said diffracted light toward said photoelectric detector;
• and
• controller for performing alignment between said mask and said substrate, based on at least one signal corresponding to said diffracted light from said photoelectric detecting means.

An alignment apparatus, which is set in an exposure apparatus having a projection optical system for projecting a projection pattern formed on a mask onto a substrate under exposure light and which performs relative alignment between said mask and said substrate, comprising:

• alignment light irradiating system for forming a beam pair with a wavelength different from that of said exposure light and splitting said beam pair into two portions as a first irradiation beam and a second irradiation beam, said alignment light irradiating system irradiating two beams in said first irradiation beam at substantially equal incident angles onto a first alignment mark formed on said mask, and said alignment light irradiating system irradiating said second irradiation beam onto a second alignment mark on said substrate through a transmission window formed on said mask and then through said projection optical system;
• first chromatic aberration correction optical elements set on or near a Fourier transform plane to said projection pattern formed on said mask in said projection optical system and in optical paths of said second irradiation beam irradiated onto said second alignment mark, said first chromatic aberration correction optical elements deflecting said second irradiation beam to make two beams in said beam pair incident at substantially equal incident angles into said second alignment mark;
• first photoelectric detector for receiving first diffracted light emerging at a substantially same direction from said first alignment mark to generate a signal corresponding to the first diffracted light;
• second photoelectric detector for receiving second diffracted light including groups of diffracted beams, said second diffracted light emerging at a substantially same direction from said second alignment mark to generate signals corresponding to the second diffracted light;
• second chromatic aberration correction optical elements set in said groups of diffracted beams return optical path to deflect said second diffracted light toward said second photoelectric detector;
• and
• controller for controlling the relative alignment between said mask and said substrate, based on said signal from said first photoelectric detector and at least one of said signals from said second photoelectric detector.

An alignment apparatus, which is set in an exposure apparatus having a projection optical system for projecting a projection pattern formed on a mask onto a substrate under exposure light and which performs relative alignment between said mask and said substrate, comprising:

• alignment light irradiating system for irradiating a first beam pair and a second beam pair, each pair composed of two beams with a substantially same wavelength different from that of said exposure light, onto a specific alignment mark on said substrate through said projection optical system, said alignment light irradiating system having first frequency shifting device for providing two beams of said first beam pair with a first beat frequency (.DELTA.f.sub.1) and second frequency shifting device for providing two beams of said second beam pair with a second beat frequency (.DELTA.f.sub.2) different from said first beat frequency (.DELTA.f.sub.1);
• a plurality of chromatic aberration correction optical elements set on or near a Fourier transform plane to said projection pattern formed on said mask in said projection optical system and in optical paths of said first and second beam pairs, said chromatic aberration correction optical elements deflecting said first beam pair to make the two beams incident at substantially equal incident angles into said specific alignment mark on said substrate and deflecting said second beam pair to make the two beams incident at substantially equal incident angles into said specific alignment mark on said substrate, wherein said incident angles of the first beam pair and the second beam pair are set in a relation of an integral number of times;
• photoelectric detector for receiving diffracted light including groups of diffracted beams, group by group, each group including beams emerging in a substantially same direction, said diffracted light emerging when said first and second beam pairs are irradiated onto said specific alignment mark through said chromatic aberration correction optical elements and then returning through said projection optical system, said photoelectric detector then generating signals corresponding to said groups of diffracted beams;
• reference signal generator for generating a first reference signal with a frequency equal to said first beat frequency (.DELTA.f.sub.1) and a second reference signal with a frequency equal to said second beat frequency (.DELTA.f.sub.2);
• and
• controller for performing alignment between said mask and said substrate, based on phase differences between said signals of the first and second beat frequencies (.DELTA.f.sub.1, .DELTA.f.sub.2) from said photoelectric detector, and said first and second reference signals.

An alignment apparatus, which is set in an exposure apparatus having a projection optical system for projecting a projection pattern formed on a mask onto a substrate under exposure light and which performs relative alignment between said mask and said substrate, comprising:

• alignment light irradiating system for forming a first irradiation beam and a second irradiation beam each having a first beam pair and a second beam pair each pair composed of two beams with a substantially same wavelength different from that of said exposure light, said alignment light irradiating system irradiating said first irradiation beam at equal incident angles for two beams in each beam pair onto a first alignment mark formed on said mask and irradiating said second irradiation beam onto a second alignment mark on said substrate through a transmission window formed on said mask and then through said projection optical system, wherein said alignment light irradiation system comprises first frequency shifting device for providing two beams in said first beam pair with a first beat frequency (.DELTA.f.sub.1), and second frequency shifting device for providing two beams in said second beam pair with a second frequency difference (.DELTA.f.sub.2) different from the first beat frequency (.DELTA.f.sub.1);
• a plurality of chromatic aberration correction optical elements set on or near a Fourier transform plane to said projection pattern formed on said mask in said projection optical system and in optical paths of said second irradiation beam, said chromatic aberration correction optical elements deflecting said first beam pair in said second irradiation beam to make two beams incident at substantially equal incident angles into said second alignment mark on said substrate and deflecting the second beam pair to make two beams incident at substantially equal incident angles into said second alignment mark on said substrate, wherein the incident angles of the first beam pair and the second beam pair are set in a relation of an integral number of times;
• first photoelectric detector for receiving beams of first diffracted light emerging in a substantially same direction from said first alignment mark to generate a signal corresponding to the first diffracted light;
• second photoelectric detector for receiving beams of diffracted light including groups of beams, group by group, each group including diffracted beams emerging in a substantially same direction, said diffracted light emerging when said first and second beam pairs are irradiated onto said second alignment mark through said chromatic aberration correction optical elements and then returning through said projection optical system, said second photoelectric detector then generating a signal corresponding to the diffracted light;
• reference signal generator for generating a first reference signal with a frequency equal to said first beat frequency (.DELTA.f.sub.1) and a second reference signal with a frequency equal to said second beat frequency (.DELTA.f.sub.2);
• and
• controller for performing alignment between said mask and said substrate, based on phase differences between signals of first and second beat frequencies (.DELTA.f.sub.1, .DELTA.f.sub.2) from said first and second photoelectric detector, and said first and second reference signals.