PROJECTION OBJECTIVE FOR MICROLITHOGRAPHY

Abstract

A projection objective with obscurated pupil for microlithography has a first optical surface, which has a first region provided for application of useful light, and at least one second optical surface, which has a second region provided for application of useful light. A beam envelope of the useful light extends between the first region and the second region. At least one tube open on the input side and on the output side in the light propagation direction severs to screen scattered light. The at least one tube is between the first optical surface and the second optical surface. The wall of the tube is opaque in the wavelength range of the useful light. The tube extends in the propagation direction of the useful light over at least a partial length of the beam envelope and circumferentially surrounds the beam envelope.

Claims

1.-20. (canceled)

21. An objective configured so that, during use, useful light can propagate through the objective along a light propagation direction, the objective comprising: a first optical surface having a first region that interacts with the useful light during use of the objective; a second optical surface having a second region that interacts with the useful light during use of the objective; a third optical surface comprising a reflective surface and a through hole; and a tube between the first and second optical surfaces along the light propagation direction, wherein: during use of the objective, a beam envelope of the useful light extends between the first and second regions; during use of the objective, an intermediate image is generated between the first and second optical surfaces; the intermediate image is in the through hole; the tube is arranged at least in proximity to the intermediate image; the tube is open on an input side in the light propagation direction; the tube is open on an output side in the light propagation direction; the tube screens scattered light during use of the objective; the tube has a wall that is opaque in a wavelength range of the useful light; the tube extends in the propagation direction of the useful light over at least a partial length of the beam envelope; the tube extends circumferentially surrounding the beam envelope; the reflective surface comprises first and second portions; the through hole is between the first and second portions of the reflective surface; during use of the objective, the useful light is reflected from the first and second portions of the reflective surface; and the objective is microlithography objective.

22. The objective of claim 21, wherein the beam envelope between the first and second optical surfaces is a first beam envelope, the first beam envelope is overlapped by a second beam envelope of the useful light over a partial length of the first beam envelope so that a portion of the first beam envelope does not overlap with the second beam envelope, and the tube extends over at least part the portion of the first beam envelope that does not overlap with the second beam envelope.

23. The objective of claim 22, wherein the tube extends over an entire length of the portion of the first beam envelope that does not overlap with the second beam envelope.

24. The objective of claim 21, wherein the tube contactlessly circumferentially surrounds the beam envelope.

25. The objective of claim 24, wherein a distance between the tube and the beam envelope is less than 2 mm.

26. The objective of claim 24, wherein a distance between the tube and the beam envelope is less than 1 mm.

27. The objective of claim 24, wherein a distance between the tube and the beam envelope is less than 0.2 mm.

28. The objective of claim 21, wherein the geometrical shape of an interior of the tube is adapted to a shape of the beam envelope.

29. The objective of claim 28, wherein the tube is truncated-cone-shaped.

30. The objective of claim 21, wherein the objective is a catoptric objective.

31. The objective of claim 30, wherein the objective is configured to be used for EUV microlithography.

32. The objective of claim 21, wherein the objective is configured to be used for EUV microlithography.

33. The objective of claim 21, wherein the input side of the tube is upstream of the through hole in the light propagation direction, and the output side of the tube is downstream of the though hole in the light propagation direction.

34. The objective of claim 21, wherein the tube is in the through hole.

35. An apparatus, comprising: a projection objective being configured so that, during use of the apparatus, useful light can propagate through the projection objective along a light propagation direction, the projection objective comprising: a first optical surface having a first region that interacts with the useful light during use of the apparatus; a second optical surface having a second region that interacts with the useful light during use of the apparatus; a third optical surface comprising a reflective surface and a through hole; and a tube between the first and second optical surfaces along the light propagation direction, wherein: the apparatus is a microlithography projection exposure apparatus; during use of the apparatus, a beam envelope of the useful light extends between the first and second regions; during use of the objective, an intermediate image is generated between the first and second optical surfaces; the intermediate image is in the through hole; the tube is arranged at least in proximity to the intermediate image; the tube is open on an input side in the light propagation direction; the tube is open on an output side in the light propagation direction; the tube screens scattered light during use of the apparatus; the tube has a wall that is opaque in a wavelength range of the useful light; the tube extends in the propagation direction of the useful light over at least a partial length of the beam envelope; the tube extends circumferentially surrounding the beam envelope; the reflective surface comprises first and second portions; the through hole is between the first and second portions of the reflective surface; and during use of the objective, the useful light is reflected from the first and second portions of the reflective surface.

36. The apparatus of claim 35, wherein the projection objective is a catoptric projection objective.

37. The apparatus of claim 36, wherein the apparatus is an EUV microlithography apparatus.

38. The apparatus of claim 35, wherein the tube is in the through hole.

39. A method, comprising: using the apparatus of claim 35 to produce semiconductor components.

40. An objective configured so that, during use, useful light can propagate through the objective along a light propagation direction, the objective comprising: a first optical surface having a first region that interacts with the useful light during use of the objective; a second optical surface having a second region that interacts with the useful light during use of the objective; a third optical surface comprising a reflective surface and a through hole, the reflective surface comprising first and second portions and a through hole between the first and second portions, the first and second portions of the reflective surface interacting with the useful light during use of the objective; and a tube between the first and second optical surfaces along the light propagation direction, the tube having first and second openings, wherein: during use of the objective: a beam envelope of the useful light extends between the first and second regions; and an intermediate image is generated between the first and second optical surfaces so that the intermediate image is in the through hole and so that the tube is arranged at least in proximity to the intermediate image; the tube extends in the propagation direction of the useful light over at least a partial length of the beam envelope so that the tube circumferentially surrounds the partial length of the beam envelope and useful light passes through the tube between the first and second openings; and the objective is microlithography objective.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Further advantages and features will become apparent from the description below and the accompanying drawing. It goes without saying that the features mentioned above and those explained below can be used not only in the combination respectively specified, but also in other combinations or by themselves, without departing from the scope of the present dislcosure. Exemplary embodiments of the disclosure are illustrated in the drawing and are described below with reference to the drawing, in which:

[0034] FIG. 1 shows a first exemplary embodiment of a projection objective for microlithography with an obscurated pupil;

[0035] FIG. 2 shows a tube for screening scattered light, which can be used in the projection objective in FIG. 1;

[0036] FIG. 3 shows a further exemplary embodiment of a projection objective for microlithography with an obscurated pupil;

[0037] FIG. 4 shows a tube for use in the projection objective in FIG. 3; and

[0038] FIG. 5 shows yet another exemplary embodiment of a projection objective for microlithography with an obscurated pupil.

DETAILED DESCRIPTION

[0039] FIG. 1 illustrates a projection objective for microlithography 10 with an obscurated pupil. The projection objective 10 has six optical surfaces S1, S2, S3, S4, S5 and S6 between an object plane O and an image plane B as seen in the light propagation direction. The optical surfaces S1 to S6 are all mirrors, such that the projection objective 10 is a catoptric projection objective.

[0040] An optical axis of the projection objective 10 is designated by OA.

[0041] The optical surfaces S1 to S6 each have a region provided for application of useful light. FIG. 1 illustrates the optical surfaces S1 to S6 exclusively with their regions provided for application of useful light.

[0042] FIG. 1 also illustrates the beam path of the useful light. The beam envelope SH of the useful light is illustrated, that is to say the beam cone formed by the totality of the marginal rays of the useful light beam bundle, of which two marginal rays 13 and 15 are illustrated.

[0043] An intermediate image Z is furthermore situated between the optical surfaces S4 and S5. On account of the intermediate image Z, the beam envelope SH of the useful light between the optical surfaces S4 and S5 has the shape of a double cone or double truncated cone, the circumferentially narrowest location of which lies in the intermediate image Z.

[0044] The optical surface S5 has a through hole A1 and the optical surface S6 has a through hole A2, through which the useful light passes in each case. The useful light passes through the through hole A2 on the way from the optical surface S4 to the optical surface S5, and the useful light passes through the through hole A1 proceeding from the optical surface S6 to the image plane B.

[0045] In order, then, to prevent scattered lightwhich is generated for example at one of the optical surfaces S1, S2, S3 or S4 or which includes over-aperture lightfrom passing through the through hole A2 and through the through hole A1 directly into the image plane B, the beam envelope SH of the useful light between the optical surfaces S4 and S5 is surrounded by a tube 12 over a partial length of the beam envelope SH, the tube screening scattered light or preventing it from propagating.

[0046] The tube 12 is illustrated by itself in FIG. 2. The tube 12 is open at an input side 14 and at an output side 16, that is to say has no material there, not even a material that is transparent to the useful light.

[0047] The tube 12 has a circumferential wall 18, which, by contrast, is fully circumferentially closed and optionally absorbent on the inside and/or on the outside.

[0048] In accordance with FIG. 1, the tube 12 surrounds the beam envelope of the useful light between the optical surfaces S4 and S5 only over a partial length, to be precise in the region in which the beam envelope of the useful light does not overlap the beam envelope of the useful light between the optical surfaces S3 and S4 or the beam envelope between the optical surfaces S5 and S6 or the beam envelope between the optical surface S6 and the image plane.

[0049] For better utilization of the overlap-free region of the beam envelopes, the tube 12 can also have a shape such as is supplemented by interrupted lines in FIG. 1.

[0050] In this case, therefore, the tube 12 extends over the entire length of the beam envelope of the useful light between the optical surfaces S4 and S5 in which the beam envelope does not overlap the beam envelopes between the optical surfaces S3 and S4, or S5 and S6, or S6 and the image plane.

[0051] In the exemplary embodiment in accordance with FIGS. 1 and 2, the tube 12 has the shape of a truncated cone, in which case the end sides of the truncated cone need not necessarily run parallel to one another, as is shown by interrupted lines from the illustration in FIG. 1. Within the meaning of the present disclosure, truncated cone shaped encompasses all geometries in which the tube widens rectilinearly in diameter from one end to the other, in which case the base areas of the tube can be any closed one-dimensional curves, that is to say including non-circular curves.

[0052] The tube 12 surrounds the beam envelope of the useful light between the optical surfaces S4 and S5 at as minimal a distance as possible, but without touching the beam envelope SH.

[0053] In the projection objective 10, the tube 12 is arranged in the vicinity of the intermediate image Z, but cannot reach as far as the intermediate image Z for structural reasons owing to the optical surface S3.

[0054] FIG. 3 illustrates a further exemplary embodiment of a projection objective for microlithography 20 with an obscurated pupil.

[0055] The projection objective 20 has eight optical surfaces S1 to S8 between an object plane O and an image plane B in the sequence of light propagation, the optical surface S6 having a through hole A1, the optical surface S5 having a through hole A2, the optical surface S8 having a through hole A3 and the optical surface S7 having a through hole A4.

[0056] The optical surfaces S1 to S8 are all realized by mirrors, such that the projection objective 20 is a catoptric projection objective. In contrast to the illustration in accordance with FIG. 1, the illustration in FIG. 3 illustrates the optical surfaces S1 to S8 symmetrically with respect to the optical axis OA, that region of each optical surface to which the useful light is applied in each case resulting from the beam envelope of the useful light depicted in FIG. 3 at each optical surface S1 to S8. In contrast to FIG. 1, the obscurated partial region of the beam bundle is not illustrated in FIG. 3.

[0057] The arrangement of the optical surfaces S1 to S8 generates a first intermediate image at Z1 and a second intermediate image at Z2.

[0058] A tube 22 is arranged between the optical surfaces S4 and S5. The tube circumferentially surrounds the beam envelope of the useful light between the optical surfaces S4 and S5. The tube 22 extends over a partial length of the beam envelope of the useful light between the optical surfaces S4 and S5 in which the useful light does not overlap the useful light between the optical surfaces S3 and S4 and S5 and S6 and between the optical surface S6 and the image plane.

[0059] The tube 22 surrounds the beam envelope of the useful light in the intermediate image Z1 and on both sides of the intermediate image Z1, as revealed in FIG. 3.

[0060] Furthermore, the tube 22 passes through the through hole A1 in the optical surface S6, which makes it possible for the tube 22 to be mechanically fixed in particular to the through hole A1.

[0061] Since the beam envelope of the useful light on both sides of the intermediate image Z1 has the shape of a double truncated cone, the tube 22 is advantageously likewise formed as a double truncated cone.

[0062] FIG. 4 illustrates the tube 22 by itself.

[0063] Like the tube 12, the tube 22 is open at its longitudinal ends 24 and 26 and has a wall 28 that is opaque to light in the wavelength range of interest and is optionally absorbent on the inside and/or on the outside.

[0064] Instead of the double-truncated-cone-shaped tube 22, it is also possible to arrange two tubes in accordance with FIG. 2 in the place of the tube 22 in the projection objective 20 in FIG. 3, these tubes then correspondingly being arranged with their narrow ends facing one another.

[0065] FIG. 5 illustrates yet another exemplary embodiment of a projection objective for microlithography 30 with an obscurated pupil.

[0066] The projection objective 30 has a total of ten optical surfaces S1 to S10 between an object plane O and an image plane B, the optical surfaces being realized as mirrors, such that the projection objective 30 is catoptric.

[0067] The projection objective 30 generates three intermediate images at Z1, Z2 and Z3. As in FIG. 3, the obscurated partial region of the beam bundle is not illustrated in FIG. 5.

[0068] In the projection objective 30, the beam envelope of the useful light in the region of the intermediate image Z1 between the optical surfaces S4 and S5 is surrounded by a tube 32 over a partial length that is free of overlaps with adjacent beam envelopes of the useful light, and, in addition, the beam envelope of the useful light between the optical surfaces S6 and S7 is surrounded by a second tube 34.

[0069] The tubes 32 and 34 essentially correspond to the tube 22 in accordance with the exemplary embodiment in FIG. 3.

[0070] In the region of the intermediate image Z2, the optical surface S8 has a through hole A1, in which the tube 34 is advantageously arranged. Further through holes are situated at the optical surfaces S7, S9 and S10, the through holes being designated by A2, A3 and A4.

[0071] The projection objectives 10, 20 and 30 described above are suitable in particular for use in EUV lithography.