Projection exposure apparatus and method which uses multiple diffraction gratings in order to produce a solid state device with fine patterns
AssigneeHitachi, Ltd.
InventorsHiroshi Fukuda, Rudolf Murai von Bunau
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Abstract
In exposing and projecting a mask onto a substrate using projection optics, a first grating is provided between the substrate and the projection optics and a second grating is provided between the projection optics and the mask so that the image of the mask pattern is formed near the substrate surface by the interference of beams diffracted by the first grating. This arrangement produces the effect of virtually increasing the NA of the optical system by up to a factor of two, making it possible to manufacture LSIs with fine patterns.
Claims78
A projection exposure method for forming patterns on a substrate comprising:
- a) applying light of wavelength (.lambda.) emitted from a light source, onto a mask having a pattern, through illumination optics;
- b) imaging the pattern on the mask onto the substrate utilizing projection optics with a reduction ratio of M:1 and a numerical aperture of NA;
- and
- c) forming an image of the mask pattern, by means of light diffracted by a first grating, positioned between the substrate and the projection optics, parallel to the substrate, interfering on a nearby substrate surface.
Projection exposure equipment, for projecting an image of a mask onto a substrate comprising:
- a) a light source directed onto the mask;
- b) projection optics to project an image of said mask;
- c) a diffraction grating diffracting the light from said projection optics;
- and
- d) a stage for securing the substrate disposed below said diffraction grating.
Projection exposure equipment for projecting an image of a mask having a pattern thereon onto a substrate comprising:
- a) a light source directed onto the mask;
- b) a first diffraction grating disposed to diffract the light from the pattern on the mask;
- c) projection optics projecting the diffracted light onto a substrate;
- d) a second diffraction grating disposed to diffract light from said projection optics;
- and
- e) a stage for securing the substrate disposed below said second diffraction means.
Projection exposure equipment comprising:
- a) a light source directed toward the mask;
- b) a first diffraction grating between said light source and said mask to diffract the light from said source such that it enters the mask at an oblique incident;
- c) projection optics to project the mask pattern onto a substrate;
- d) a second diffraction grating diffracting light from projection optics;
- and
- e) a stage on which to place the substrate disposed below the second diffractor.
Projection exposure equipment comprising:
- a) a light source emitting light of wavelength .lambda.;
- b) a mask stage for receiving a mask;
- c) a substrate stage for receiving a substrate;
- d) illumination optics directing the light from said light source onto a mask on said mask stage;
- e) projection optics, having a numerical aperture (NA) and magnification (M:1) imaging patterns of the mask onto a substrate surface on said substrate stage;
- f) a first diffraction grating with a spatial pitch P1(.lambda./1.42*NA) .ltoreq.P1.ltoreq..lambda./NA) in at least one direction, disposed at a position Z1, where Z1 is the optical path length between the substrate and the projection optics to diffract light from said projection optics;
- and
- g) an optical element selected from the group consisting of imaging optics or a second grating disposed between the mask and the illumination optics, or between the projection optics and the mask, said optical element forming an image of the mask pattern nearby the surface of the substrate by interference of light diffracted by said first grating.
Exposure equipment comprising:
- a) a light source for exposure;
- b) a holding means for holding a mask having a specified pattern;
- c) a projection optics;
- d) a stage on which a wafer substrate is mounted;
- e) a second holding means disposed between the projection optics and the stage to hold a first grating that diffracts exposure light form the light source;
- and
- f) a third holding means disposed between the light source and the projection optics to hold an image forming means which forms the image of the specified pattern from the exposure light diffracted by the first grating.
Exposure equipment according to 25 wherein the equation
- Z2=M*(P2/P1)*Z1
- is satisfied where Z1 is the distance between the pattern formed from the exposure light diffracted from the first grating, and the first grating, Z2 is the distance between the mask and the second grating, M is the magnification of the projection optics, P1 is the pitch of the first grating, and P2 the pitch of the second grating.
Exposure equipment according to 49, and further including an opaque pattern disposed between the projection optics and the second grating, and wherein the pitch of said micro lens array and the pitch of the exposure area of said opaque pattern are equal.
A pattern creation method utilizing exposure equipment including a light source for exposure, a mask support, projection optics, and a substrate stage comprising:
- a) supporting a mask with a prescribed pattern utilizing the mask support;
- b) supporting a first grating between the stage and the projection optics;
- c) supporting an imaging optical element which forms the image of the fixed pattern through the exposure light, from the light source, which is diffracted by the first grating,
- d) placing a substrate coated with a photo sensitive film onto the stage;
- and
- e) exposing the surface of the substrate with a exposure light which passes through the mask, imaging optical element, the projection optics, and the first grating.
The pattern forming method claimed in 53 wherein said imaging optical element include imaging optics disposed between the mask and the projection optics, and a second grating disposed between the imaging optics and the projection optics.
Dependencies are inferred from the claim text.