Projection exposure apparatus and method which uses multiple diffraction gratings in order to produce a solid state device with fine patterns
First Claim
Patent Images
1. A projection exposure method for forming patterns on a substrate comprising:
- a) applying light of wavelength (λ
) 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.
1 Assignment
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Accused Products
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.
1370 Citations
78 Claims
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1. A projection exposure method for forming patterns on a substrate comprising:
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a) applying light of wavelength (λ
) 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; andc) 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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10. A projection exposure method, according to claim 9 wherein said second and third gratings are phase gratings.
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11. A projection exposure method as claimed in claim 1, wherein a second imaging optics are disposed between the mask and the projection optics and further including inserting a second grating at a position that is approximately a conjugate of said first phase grating, and said second grating having a spatial pitch P2 in one direction described approximately as:
space="preserve" listing-type="equation">P2=P1*M.sub.c.
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12. A projection exposure method, as claimed in claim 1 comprising to simultaneously illuminating patterns existing in two locations on the mask, both containing the desired identical patterns, with a coherent light from at least two unique directions.
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13. A projection exposure method according to claim 1, the wavefront aberration of the projection optics are compensated to be symmetrical with respect to the diameter, on the pupil plane, perpendicular to the direction of illumination and illuminating the mask with a pair of coherent illumination with an incident angle symmetrical with respect to the optical axis.
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14. A projection exposure method, according to claim 1, wherein the mask contains an alternate phase shift mask.
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15. A projection exposure method according to claim 1, said mask has a fine pattern in a particular direction, depending on the pitch and direction of the first grating.
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16. A projection exposure method according to claim 1 wherein said mask is constructed to compensate for the pattern shapes, depending on the pitch and direction of the pattern of the first grating.
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17. A projection exposure method according to claim 1, further including filling the gap between the first grating and the substrate with a liquid with an index of refraction n greater than 1 wherein the NA of the projection optics is in the following range:
space="preserve" listing-type="equation">0.5<
NA<
n/2.
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18. Projection exposure equipment, for projecting an image of a mask onto a substrate comprising:
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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.
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19. Projection exposure equipment for projecting an image of a mask having a pattern thereon onto a substrate comprising:
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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.
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20. Projection exposure equipment comprising:
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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.
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21. Projection exposure equipment comprising:
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a) a light source emitting light of wavelength λ
;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(λ
/1.42*NA) ≦
P1≦
λ
/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; andg) 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. - View Dependent Claims (22, 23)
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24. Exposure equipment comprising:
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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. - View Dependent Claims (25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
- 29. Exposure equipment according to claim 25 wherein the equation
- space="preserve" listing-type="equation">sin (θ
i)=±
{1/(M·
P1)+1/P2}
is satisfied where θ
i is the incident angle of the exposure light to the mask, λ
is the wavelength of the exposure light, M is the magnification of the projection optics, P1 is the pitch of the first grating, and P2 is the pitch of the second grating. - space="preserve" listing-type="equation">sin (θ
-
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31. Exposure equipment according to claim 25 wherein said illumination means include a third grating between the light source and the mask.
- 32. Exposure equipment according to claim 31, wherein the equation
- space="preserve" listing-type="equation">1/P3=1/(M·
P1)+1/P2
is satisfied where P3 is the pitch of the third grating, M is the magnification of the projection optics, P1 is of the pitch of the first grating, and P2 is the pitch of the pitch of the second grating. - space="preserve" listing-type="equation">1/P3=1/(M·
- space="preserve" listing-type="equation">0.5<
NA<
n/2
- 30. Exposure equipment according to 25 wherein the equation
- space="preserve" listing-type="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.
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53. A pattern creation method utilizing exposure equipment including a light source for exposure, a mask support, projection optics, and a substrate stage comprising:
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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. - View Dependent Claims (54, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78)
- 58. The pattern forming method of claim 54 wherein the equation
- space="preserve" listing-type="equation">sin (θ
i)=±
{1/(M·
P1)+1/P2}
is satisfied when θ
i is the incident angle of the exposure light onto the mask, λ
is the wavelength of the exposure light, M is the magnification of the projection optics, P1 is the pitch of the first grating, and P2 is the pitch of the second grating. - space="preserve" listing-type="equation">sin (θ
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- 59. The pattern forming method of claim 54 wherein the equation
- space="preserve" listing-type="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 of the pitch of the first grating, and P2 is the pitch of the second grating.
- space="preserve" listing-type="equation">1/P3=1/(M·
P1)+1/P2
- space="preserve" listing-type="equation">0.5<
NA<
n/2
- M where M is the magnification of the projection optics.
- and carrying out a further exposure step to re-expose said substrate.
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55. 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.
Specification