Lithography system and method for device manufacture

• US 6,753,947 B2
• Filed: 05/10/2001
• Issued: 06/22/2004
• Est. Priority Date: 05/10/2001
• Status: Expired due to Term

• Current Assignee: Veeco Instruments Incorporated
• Original Assignee: Ultratech Stepper, Inc. (Veeco Instruments Incorporated)
• Inventors: Meisburger, Dan, Markle, David A.
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Brown, Khaled
• Application Number:
  US09/854,226
• Publication Number:
  US 20020186359A1
• Time in Patent Office: 1,139 Days
• Field of Search: 355/69, 355/53, 355/77, 355/55, 355/60, 355/67, 356/399, 356/400, 356/401, 250/548, 250/492.2, 430/30
• US Class Current: 355/69
• CPC Class Codes: G03F 7/70041 by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control
• CPC Class Codes: G03F 7/70225 Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements
• CPC Class Codes: G03F 7/70425 Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
• CPC Class Codes: G03F 7/7055 Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
• CPC Class Codes: G03F 7/70558 Dose control, i.e. achievement of a desired dose
• CPC Class Codes: G03F 7/70725 control

Abstract

A lithography system and method for cost-effective device manufacture that can employ a continuous lithography mode of operation is disclosed, wherein exposure fields are formed with single pulses of radiation. The system includes a pulsed radiation source (14), an illumination system (24), a mask (M), a projection lens (40) and a workpiece stage (50) that supports a workpiece (W) having an image-bearing surface (WS). A radiation source controller (16) and a workpiece stage position system (60), which includes a metrology device (62), are used to coordinate and control the exposure of the mask with radiation pulses so that adjacent radiation pulses form adjacent exposure fields (EF). Where pulse-to-pulse uniformity from the radiation source is lacking, a pulse stabilization system (18) may be optionally used to attain the desired pulse-to-pulse uniformity in exposure dose. The rapidity at which exposures can be made using a single radiation pulse allows for a very high throughput, which in turn allows for a small-image-field projection lens to be utilized in a cost-effective manner in the manufacture of devices such as semiconductor integrated circuits and the like. The system can also be used in the conventional “step-and-repeat” mode of operation, so that the system owner can decide the most cost-effective mode of operation for any given application.

Claims

1. A lithography system capable of rapidly, and repeatedly, exposing an entire mask having a single pattern to form a plurality of spaced-apart exposure fields on a workpiece, comprising:

a radiation source capable of emitting pules of radiation each having a temporal pulse length of one millisecond or less and a pulse-to-pulse energy variation of 10% (3σ

) or less;

an illuminator arranged to receive each pulse of radiation from said radiation source to illuminate the entire mask;

a projection lens arranged to receive each pulse of radiation passing through the mask and adapted to form a full mask image in a separate exposure field on the workpiece by each pulse;

a workpiece stage capable of supporting the workpiece and moving the workpiece over a scan path;

a workpiece stage position control unit in operable communication with said workpiece stage to control the movement of said workpiece stage over said scan path and to generate workpiece stage location information; and

a radiation source controller in operative communication with said radiation source and said workpiece stage position control unit receive position information from said workpiece stage position control unit to coordinate the emission of each pulse of radiation from the radiation source with the position of the workpiece stage such that each radiation pulse is provided to expose a different spaced-apart exposure field on the workpiece with the same full mask image at each desired position along said scan path in forming the plurality of separate and spaced-apart exposure fields on the workpiece.

2. A system according to claim 1, further including an alignment system in electrical communication with said workpiece stage position control system and in operable communication with the workpiece, to control the trajectory of the stage with respect to previously laid down patterns in exposure fields on the workpiece in at least one previous layer to sequentially align each exposure field on the workpiece relative to the mask image at each desired position along the scan path.

3. A system according to claim 2, wherein said radiation source controller causes said radiation source to emit a pulse to expose each existing exposure field to overlay a previously laid down pattern therein.

4. A system according to claim 1, wherein said workpiece includes an image-bearing surface, and each radiation pulse has energy sufficient to expose but not ablate the image-bearing surface.

5. A system according to claim 4, wherein each radiation pulse delivers an exposure dose in the range between 1 and 500 mJ/cm² as measured at the workpiece.

6. A system according to claim 1, wherein said radiation source is capable of emitting pulses of radiation at a repetition rate of between 1 and 100 Hz.

7. A system according to claim 1, wherein the projection lens has a reduction magnification of 4×

or greater.

8. A system according to claim 1, wherein the projection lens is an on-axis catadioptric lens design having a reduction ratio between 4×

and 8×

, and an image field less than 2.2 cm² and an image-side numerical aperture of 0.6 or greater.

9. A system according to claim 1, wherein the projection lens is a Wynne-Dyson lens design having a unity reduction ratio.

10. A system according to claim 1, wherein the projection lens has a rectangular image field circumscribed by a circular image field of 16 mm diameter.

11. A system according to claim 1, wherein said workpiece stage is one of an air-bearing stage and a magnetically levitated stage capable of moving at a velocity between 50 mm/s and 5000 mm/s.

12. A system according to claim 2, further including a workpiece handling system in operable communication with said workpiece stage to place and remove workpieces to and from said workpiece stage.

13. A system according to claim 2, further including a system controller electrically connected to said alignment system, said workpiece stage position control system, said radiation source control system, and said workpiece handling system.

14. A system according to claim 1, wherein said radiation source is a solid state laser operating with m⁴ spatial modes and having a m⁴ value of 1000 or greater.

15. A system according to claim 1, wherein said radiation source includes a flash lamp.

16. A system according to claim 14, wherein said solid-state laser is a multi-mode, frequency-multiplied, YAG laser operating at a wavelength of 266 nm, 213 nm, 177 nm or 152 nm.

17. A system according to claim 14, wherein said solid state laser is a multi-mode, frequency-multiplied and frequency mixed YAG laser operating at a wavelength of 240 nm, 193 nm or 157 nm.

18. A system according to claim 14, wherein said solid-state laser is a multi-mode, frequency-multiplied, alexandrite laser operating at a wavelength of 248 nm, 193 nm or 157 nm.

19. A system according to claim 1, wherein said radiation source is a Xenon plasma source operating at a wavelength in the 6 nm-14 nm wavelength region.

20. A system according to claim 1, wherein said radiation source is an excimer laser operating at a wavelength of 248 nm, 193 nm or 157 nm.

21. A system according to claim 1, further including a pulse stabilization system.

22. A system according to claim 1, wherein said radiation source is capable of generating radiation pulses having a temporal pulse length between 1 nanosecond and 1 millisecond.

97. A system according to claim 14, further including a pulse stabilization system coupled to said radiation source.

98. A system according to claim 15, further including a pulse stabilization system coupled to said radiation source.

99. A system according to claim 19, further including a pulse stabilization system coupled to said radiation source.

100. A system according to claim 20, further including a pulse stabilization system coupled to said radiation source.

23. A system to rapidly expose a workpiece repeatedly with the same image of an entire mask having a single pattern to form a plurality of spaced-apart exposure fields on the workpiece using a single radiation pulse per exposure field, comprising, in order along an optical axis:

a radiation source to provide pulses of radiation having a pulse-to-pulse uniformity of 10% (3σ

) or less;

an illuminator arranged to receive said pulses of radiation and substantially uniformizing each radiation pulse over the mask plane;

a mask holder capable of supporting the mask that is to be substantially uniformly illuminated by each radiation pulse exiting the illuminator;

a projection lens having an object plane arranged at or near the mask, an image plane arranged at or near the workpiece, and an image field within said image plane, said projection lens arranged to receive radiation transmitted through the mask to form a full mask image on the workpiece within said image field; and

a workpiece stage to support the workpiece at or near said image plane and adapted to move the workpiece over a scan path at a velocity that allows each pulse of radiation to expose a different adjacent spaced-apart exposure field with the same full mask image without appreciably smearing each full mask image on the workpiece in the various exposure fields.

24. A system according to claim 23, further including a workpiece stage position control system operatively connected to said workpiece stage, to control movement of said workpiece stage over said scan path.

25. A system according to claim 23, further including a pulse stabilization system to enhance the stability of the pulse-to-pulse energy uniformity of the radiation pulses from the radiation source.

26. A system according to claim 24, further including a radiation source control system operatively connected to said radiation source and said workpiece stage position control system, to coordinate and control the operation of the radiation source with respect to the position of the workpiece along said scan path.

27. A system according to claim 23, wherein said workpiece includes an image-bearing surface, and each radiation pulse has energy sufficient to expose but not ablate the image-bearing surface.

28. A system according to claim 27, wherein the image-bearing surface is photoresist.

29. A system according to claim 23, wherein each radiation pulse delivers an exposure dose in the range between 1 and 500 mJ/cm² as measured at the workpiece.

30. A system according to claim 23, wherein said radiation source is capable of emitting pulses of radiation at a rate of between 1 and 500 Hz.

31. A system according to claim 23, wherein the reduction magnification of the projection lens is 4×

or greater.

32. A system according to claim 23, wherein the projection lens has a reduction magnification of 1×

.

33. A system according to claim 23, wherein the projection lens has a rectangular image field circumscribed by a circular image field of 16 mm diameter.

34. A system according to claim 27, further including an alignment system in operative communication with said workpiece stage and in optical communication with the workpiece, to align the workpiece relative to said mask image.

35. A system according to claim 34, further including a workpiece handling system in operable communication with said workpiece stage to place and remove workpieces to and from said workpiece stage.

36. A system according to claim 35, further including a system controller electrically connected to, and to coordinate the control of, said alignment system, position of said workpiece stage, said radiation source, and said workpiece handling system.

37. A system according to claim 23, wherein said workpiece stage is an air-bearing stage or a magnetically levitated stage capable of moving the workpiece at a velocity up to 5000 mm/s.

38. A system according to claim 23, wherein said radiation source is a solid state laser operating with m⁴ multiple spatial modes and having a value m⁴ of 1000 or greater and having a pulse-to-pulse variation of 10% (3σ

) or less.

39. A system according to claim 38, wherein said solid-state laser is a multi-mode, frequency-multiplied, YAG laser operating at a wavelength of 266 nm, 213 nm, 177 nm or 152 nm.

40. A system according to claim 38, wherein said solid state laser is a multi-mode, frequency-multiplied and frequency-mixed YAG laser operating a wavelength of 248 nm, 193 nm or 157 nm.

41. A system according to claim 23, wherein said radiation source is a Xenon plasma source operating at a wavelength in the 6 nm-20 nm wavelength region.

42. A system according to claim 23, wherein said radiation source is an excimer laser operating at wavelength 248 nm, 193 nm or 157 nm.

43. A system according to claim 23, wherein said radiation source is flash lamp operating at wavelength between about 350 nm and about 450 nm.

44. A system according to claim 23, wherein said radiation source is capable of generating said radiation pulses each having a temporal pulse length between 1 nanosecond and 1 millisecond.

45. A system according to claim 23, wherein said illuminator includes, in order along the optical axis from said radiation source:

a first beam transport optical system;

a diffuser;

an optical integrator; and

a second beam transport optical system.

46. A system according to claim 45, wherein said illuminator system further includes:

beam diagnostic subsystem to measure the pulse-to-pulse energy variation of the radiation pulses.

47. A method of forming multiple spaced-apart exposure fields on a workpiece with a projection lens having an object plane at which a mask having a single pattern is supported, and an image plane with an image field within which a full mask image is formed, the method comprising the steps of:

a) continuously moving the workpiece relative to the image field in a scan path;

b) irradiating the mask with a single radiation pulse each time a position on the workpiece where a different exposure field is to be formed is aligned with the image field with said radiation pulse being one of a sequence of such pulses having a pulse-to-pulse exposure dose variation of 10% (3σ

) or less and a uniformity variation over the object plane of 10% (3σ

) or less; and

c) collecting, with the projection lens, a portion of each radiation pulse transmitted through the mask to form a full mask image for each radiation pulse in the image field;

wherein each time the mask is illuminated with one radiation pulse, the mask image in the image field forms a corresponding separate spaced-apart exposure field on the workpiece.

48. A method according to claim 47, wherein said step b) includes the step of:

d) aligning the mask image to one or more pre-existing exposure field on the workpiece.

49. A method according to claim 47, wherein:

the workpiece has an image-bearing surface; and

step b) includes the step of;

d) providing each radiation pulse with enough energy to expose but not ablate the image-bearing surface.

50. A method according to claim 47, wherein said step b) includes the step of:

d) operating a solid-state laser with a m⁴ spatial modes and having a value of m⁴ of 1000 or greater.

51. A method according to claim 47, wherein said step b) includes the step of:

d) evenly distributing each radiation pulse over the mask plane by passing each radiation pulse through an illuminator system located between the radiation source and the mask.

52. A method according to claim 47, wherein said step b) includes the step of:

d) providing the radiation pulses at a repetition rate of between 1 Hz and 500 Hz.

53. A method according to claim 47, wherein said step b) includes the step of:

d) providing the radiation pulses with sufficient energy such that the exposure dose from a single pulse at the workpiece has a value between 1 mJ/cm² and 500 mJ/cm².

54. A method according to claim 47, further includes the step of:

d) defining the image field to be a rectangular section of a circular image field of 16 mm diameter.

55. A method according to claim 47, wherein said step a) includes the step of:

d) moving the workpiece at a constant velocity.

56. A method according to claim 47, further includes the step of:

d) monitoring the energy of each of the radiation pulses.

57. A method according to claim 47, wherein said step c) includes the step of:

d) forming the separate exposure fields in juxtaposed registration with pre-existing, separate spaced-apart exposure fields with previously laid down patterns therein.

58. A method according to claim 47, wherein:

the mask pattern has a minimum feature size, the radiation pulses have a repetition rate and a temporal pulse length, and the workpiece has a scan speed; and

the method further includes the step of;

d) selecting the repetition rate, the scan speed and the temporal pulse length such that each mask image forming each exposure field is blurred by no more than 20% of the minimum feature size.

59. A method according to claim 47, wherein:

the mask pattern has a minimum feature size defining a mask image modulation frequency, the radiation pulses have a repetition rate and a temporal pulse length, and the workpiece has a scan speed; and

the method further includes the step of;

d) selecting the repetition rate, the scan speed and the temporal pulse length such that each mask image forming each exposure field is blurred by an amount that reduces the amplitude of the maximum mask image modulation frequency by 34.6% or less.

60. A method according to claim 47, wherein the mask has a cost that is amortized over exposing 3000 workpieces or less.

61. A method according to claim 47, further includes the step of:

d) sending the radiation pulses through a pulse stabilization system to improve the pulse-to-pulse energy uniformity.

62. A method of rapidly forming a plurality of sequentially arranged, spaced-apart exposure fields on a workpiece with a projection lens having an object plane, an image plane and an image field, comprising the steps of:

a) supporting a mask having a single pattern at or near the object plane;

b) arranging a workpiece stage on which the workpiece is mounted to be movable within the image plane over a scan path relative to the image field with the workpiece having sequentially arranged, spaced-apart exposure fields to be formed;

c) continuously moving the workpiece stage over the scan path; and

d) irradiating the mask with a single radiation pulse and collecting the transmitted radiation pulse with the projection lens to form a full mask image within the image field each time the workpiece is aligned relative to the image field to form a different one of the adjacent, spaced-apart exposure fields.

63. A method according to claim 62, wherein the adjacent exposure fields are formed in registered juxtaposition with pre-existing exposure fields formed on the workpiece.

64. A method according to claim 62, wherein step d) includes the step of:

e) providing the pulses of radiation from a solid-state laser having a number of spatial modes m⁴ and having a value m⁴ of 1000 or greater.

65. A method according to claim 62, wherein step d) includes the step of:

e) providing the pulses of radiation from a flash lamp operating in the near UV part of the spectrum.

66. A method according to claim 62, wherein:

the workpiece has an image-bearing surface; and

the method further includes the step of;

e) providing each radiation pulse with enough energy to expose but not ablate the image-bearing surface.

67. A method according to claim 62, wherein:

the mask defines a mask plane; and

step d) includes the step of;

e) spreading each radiation pulse uniformly across the mask plane by passing each radiation pulse through an illuminator arranged upstream of the mask.

68. A method according to claim 62, wherein step d) includes the step of:

e) providing the radiation pulses at a repetition rate of between 1 Hz and 500 Hz.

69. A method according to claim 62, wherein step d) includes the step of:

e) providing radiation pulses with sufficient energy to provide an exposure dose at the image plane of between 1 mJ/cm² and 500 mJ/cm².

70. A method according to claim 62 further includes the step of:

e) defining a rectangular image field that fits within a circular image field of 16 mm in diameter.

71. A method according to claim 62, wherein step c) includes the step of:

e) moving the workpiece at a constant velocity.

72. A method according to claim 62, wherein the pulses of radiation have a pulse-to-pulse variation in energy that is less than 10% (3σ

).

73. A method according to claim 62, wherein the pulses of radiation have a pulse-to-pulse variation in energy that is less than 1% (3σ

).

74. A method according to claim 62, wherein:

the mask pattern has a minimum feature size; and

steps c) and d) are performed such that each exposure field contains a full mask image with the amount of blurring, due to continuously moving the workpiece stage, being less than 20% of said minimum feature size.

75. A method according to claim 62, wherein:

the mask pattern has a minimum feature size, the mask image has a maximum modulation frequency based on the minimum feature size; and

steps c) and d) are performed such that each exposure field contains a full mask image with the amount of blurring, due to continually moving the workpiece stage during the mask irradiation step, decreases the amplitude of the maximum modulation frequency corresponding to the minimum feature size by less than 36.4%.

76. A lithography system capable of cost-effectively patterning a workpiece in the manufacturing of semiconductor devices in a semiconductor manufacturing environment, comprising:

a mask with a patterned area having a single pattern to be repeatedly imaged onto the workpiece and having a cost that is amortized over processing 3000 workpieces or less;

a radiation source and illumination system operatively arranged to illuminate the mask with a series of spatially uniformized pulses of radiation;

a reduction projection lens with an output end having numerical aperture NA and demagnification of 5×

or greater, arranged adjacent the mask to receive pulses of radiation passing through the mask, the lens being designed to form a full mask image of the mask pattern onto the workpiece over a different, spaced-apart exposure field with each pulse, each exposure field having a maximum area of 2 cm² or less; and

a workpiece stage and workpiece stage position control system to move the workpiece under the projection lens.

77. A system according to claim 76, wherein the movement of the workpiece by said workpiece stage and said workpiece stage position control system is continuous during exposure of a plurality of separate spaced-apart exposure fields with said pulses of radiation.

78. A system according to claim 76, further including an alignment system in electrical communication with the workpiece stage position control system and in operable communication with the workpiece to align the workpiece relative to the mask image.

79. A system according to claim 76, wherein the radiation source emits radiation having a wavelength of 248 nm or shorter.

80. A system according to claim 79, wherein the projection lens has a numerical aperture of 0.6 or greater.

81. A system according to claim 80, wherein the projection lens is a four-mirror on-axis catadioptric optical system having an image plane, with one of the four mirrors being a Mangin mirror disposed adjacent the image plane.

82. A lithography system operating at a wavelength λ

and numerical aperture NA capable of cost-effectively patterning a workpiece having an image-bearing surface with a plurality of spaced-apart exposure fields, comprising;

a mask with a single patterned area to be imaged entirely onto the workpiece as a mask image having a minimum feature size of 0.5 λ

/NA or smaller, the mask having a cost that is amortized over processing 3000 workpieces or less;

a pulsed radiation source capable of emitting pulses of radiation having a temporal duration of 10 microseconds or less, wavelength λ

, a repetition rate between 1 Hz and 50 Hz, and each pulse having energy sufficient to expose but not ablate the image bearing surface;

an illumination system operatively arranged to receive render and spatially uniformize single pulses of radiation from the radiation source and to illuminate the mask with the spatially uniform pulses of radiation;

a reduction projection lens with an output end having numerical aperture NA and reduction magnification of 5×

or greater, arranged adjacent the mask to receive pulses of radiation passing through the mask, the lens being designed to form a full mask image onto the workpiece over each spaced-apart exposure field having a maximum rectangular area of 2.2 cm² or less with each pulse of radiation imaging a different spaced-apart exposure filed on the workpiece; and

a workpiece stage to continuously transport the workpiece under the projection lens output end and over a scan path at a scan velocity in a coordinated manner with the emission of radiation pulses from the radiation source such that each spaced-apart exposure field is formed from a single full mask image by a single pulse of radiation.

83. A system according to claim 82, wherein the radiation source has a pulse-to-pulse energy dose variation less than 5% (3σ

).

84. A system according to claim 82, wherein the radiation source has temporal pulse duration that is less than the minimum feature size divided by the scan velocity.

85. A system according to claim 82, wherein the radiation source has a wavelength λ

of 248 nm or shorter.

86. A system according to claim 82, wherein the projection lens NA is 0.6 or greater.

87. A system according to claim 82, wherein the projection lens has a corrected spectral range of one Angstrom or greater.

88. A pulse stabilization system to stabilize the pulse-to-pulse energy of a beam of radiation pulses emitted from a radiation source along an optical path, comprising:

a detector arranged downstream of the radiation source to detect a portion of radiation emitted from the radiation source and produce an electrical signal corresponding to the detected radiation;

an integration circuit electrically connected to the detector to integrate the electrical signal from the detector and provide an integrated electrical signal;

a programable threshold detector coupled to said integration circuit to receive the integrated electrical signal and programed with a threshold value to generate an activation signal when the integrated electrical signal reaches the threshold value;

a Pockels cell driver electrically connected to the programable threshold detector;

a Pockels cell, electrically connected to the Pockels cell driver, responsive to said activation signal and arranged in the optical path; and

a delay line, in the optical path between the radiation source and the Pockels cell, designed such that activation of the Pockels cell via the activation signal serves to truncate the radiation pulse responsible for generating the activation signal leaving the radiation pulse with an amount of energy corresponding substantially to the threshold value.

89. A system according to claim 88, further including:

an optical system arranged adjacent the light source in the optical path to divide the radiation pulses along first and second optical paths each having associated therewith a different polarization; and

a half-wave plate arranged in one of the first and second optical paths to make the radiation pulses in the first and second optical paths have the same polarization;

wherein said optical system directs the first and second optical paths in a common direction.

90. A system according to claim 89, wherein said optical system comprises a polarizing beam splitter and a plurality of mirrors.

91. A system according to claim 88, further including an optical system arranged in the first optical path upstream of the Pockels cell and designed so that a portion of the beam of radiation pulses is directed around the Pockels cell and recombined with the portion of the beam of radiation pulses passing through the Pockels cell.

92. A system according to claim 91, wherein the optical system includes a first beam splitter arranged in the first optical path upstream of the Pockels cell and a second beam splitter arranged downstream of the Pockels cell.

93. A pulse stabilization system to stabilize the pulse-to-pulse output of an output beam of radiation pulses formed by a first beam of radiation pulses emitted from a first radiation source along a first optical path, and a second beam of radiation pulses emitted from a second radiation source along a second optical path, comprising:

first means for detecting and processing a portion of the radiation emitted from the first radiation source and for producing a first integrated electrical signal;

second means for detecting and processing a portion of the radiation emitted from the second radiation source and for producing a second integrated electrical signal;

third means for receiving said first and second integrated electrical signals and generating an activation signal when said first and second integrated electrical signals reached a combined threshold value;

electro-optical means responsive to said activation signal and arranged in the first optical path to attenuate the radiation pulses in the first beam of radiation pulses; and

optical means for combining the first and second beams of radiation pulses to form the combined output beam of radiation pulses that have a substantially uniform energy from pulse to pulse.

94. A lithography system to cost-effectively process 3000 workpieces or less per set of masks as compared to a conventional lithography system the cost-effective lithography system comprising in order along an optical axis:

a radiation source to provide radiation pulses;

an illuminator arranged to receive the radiation pulses and substantially spread each radiation pulse uniformly over a mask plane with a spatial uniformity of 10% (3σ

) or less;

a mask holder capable of supporting one of the masks in the set of masks at the mask plane;

a workpiece stage to support a workpiece and move the workpiece relative to the optical axis; and

a catadioptric projection lens having an object plane arranged at or near the mask plane, an image plane arranged at or near one of the workpieces, and an image field within the image plane, the image field having an area of about 2.2 cm² or less so that each of the masks in the mask set contains less than or equal to about half the amount of information of a mask used with the conventional lithography system;

wherein the workpiece stage is adapted to step the workpiece to allow a plurality of bursts of radiation pulses to form a corresponding plurality of exposure fields in a one pulse to one exposure field relationship on the workpiece being processed.

95. A system according to claim 94, wherein the radiation source and workpiece stage are adapted to alternatively provide single-pulse exposures of each exposure field.

96. A system according to claim 94, wherein the radiation source is a flash lamp or a laser.