CN112445076A

CN112445076A - Photoetching machine, exposure system, off-axis illumination method and off-axis illumination device

Info

Publication number: CN112445076A
Application number: CN201910818265.5A
Authority: CN
Inventors: 田毅强; 兰艳平; 储兆祥
Original assignee: Shanghai Micro Electronics Equipment Co Ltd
Current assignee: Shanghai Micro Electronics Equipment Co Ltd
Priority date: 2019-08-30
Filing date: 2019-08-30
Publication date: 2021-03-05
Anticipated expiration: 2039-08-30
Also published as: CN112445076B

Abstract

The invention relates to a photoetching machine, an exposure system, a method for realizing off-axis illumination and an off-axis illumination device, wherein the off-axis illumination device comprises a light source, a reflecting unit, a coupling unit, a light homogenizing unit and a relay lens group which are sequentially arranged, the coupling unit at least comprises a zoom lens group and a converging lens group, the converging lens group is positioned between the zoom lens group and the light homogenizing unit, and the method comprises the following steps: before the light beams are projected to the dodging unit, the pupil position is translated, so that the light beams in the translated pupil are incident to the dodging unit in an asymmetric mode, but the incident asymmetric light beams form an off-axis illumination field after being subjected to dodging. The invention has the advantages of reducing energy loss, improving yield, simplifying light path structure, reducing cost and saving installation space on the premise of ensuring pupil uniformity.

Description

Photoetching machine, exposure system, off-axis illumination method and off-axis illumination device

Technical Field

The invention relates to the technical field of optical design, in particular to a photoetching machine, an exposure system, a method for realizing off-axis illumination and an off-axis illumination device.

Background

Microlithography in semiconductor fabrication uses an optical system to precisely project and expose a pattern on a reticle onto a photoresist-coated silicon wafer.

The exposure system comprises an illumination system, a mask plate, a projection objective and a workpiece table for accurately aligning the silicon wafer. The illumination system needs to provide a uniform rectangular field of view on the mask surface, and then the pattern on the reticle is projected through the projection objective onto the silicon wafer for exposure. In order to further enhance the resolution of the exposure system, increase the focal depth and enlarge the process window, off-axis illumination technology has been widely adopted in scanning exposure systems.

Conventional off-axis illumination includes annular illumination, second-order illumination, and fourth-order illumination, among others, with the choice of different off-axis illumination pupil distributions being primarily based on the particular mask pattern. And the two-level illumination and the four-level illumination both belong to a part of a pupil-Mask Optimization (SMO) technical scheme, and in practical application, the optimal energy distribution of a pupil plane of an illumination system can be calculated according to the distribution of a Mask pattern, and the pupil distribution is obtained through modulation, so that the resolution of the system is enhanced, and the focal depth is enhanced.

In the present solutions for two-level or four-level illumination, the energy distribution in the pupil plane is mainly changed by:

1. the energy distribution of the pupil plane is directly changed by arranging a baffle plate or a glass flat plate with variable transmittance distribution on the pupil plane, but the energy loss is large, which is not beneficial to increasing the yield;

2. diffraction Optical Elements (DOEs) with different far-field distributions are selected, so that corresponding energy distributions are obtained on a pupil plane, and although the scheme can improve the energy utilization rate, the DOEs are high in use cost;

3. utilize 1 pair of axicon group, pull open the axicon group and can form annular illumination with traditional illumination, also can cooperate the zoom group, form the change of lighting system coherence factor to change the energy distribution of pupil plane, nevertheless because axicon processing is more difficult, the processing cost is high, especially the top can remove one of them part often, causes traditional illumination mode center still to have the cavity, and needs great axial space.

4. The method uses a micro-Mirror Array (MMA) to change the reflection angle of any reflecting Mirror in the MMA, and obtains corresponding energy distribution on a pupil plane, the energy utilization rate of the scheme is high, any pupil distribution can be formed, however, the research and development cost is high, and the calculation method for forming the corresponding pupil energy distribution is very complex.

Disclosure of Invention

The invention aims to provide a photoetching machine, an exposure system, a method for realizing off-axis illumination and an off-axis illumination device, which are used for solving the problems of difficult processing, high cost and large required axial space of parts used for adjusting a light path and also used for solving the problems of large energy loss and low yield when generating a uniform off-axis illumination field.

In order to achieve the above object, the present invention provides a method for implementing off-axis illumination, based on an off-axis illumination device, the off-axis illumination device includes a light source, and a reflection unit, a coupling unit, a light-equalizing unit, and a relay lens group that are sequentially arranged, the coupling unit at least includes a zoom lens group and a converging lens group, the converging lens group is located between the zoom lens group and the light-equalizing unit, the method includes:

before the light beams are projected to the dodging unit, the pupil position is translated, so that the light beams in the translated pupil are incident to the dodging unit in an asymmetric mode, and the dodging unit further dodges the incident asymmetric light beams to form an off-axis illumination field.

Optionally, in the method for implementing off-axis illumination, the propagation process of the light beam is as follows: the light source is used for emitting light beams to the coupling unit after being reflected by the reflection unit, the coupling unit is used for further coupling the light beams and then projecting the light beams to the dodging unit, and the dodging unit is used for further dodging the light beams and then projecting the light beams to the relay lens group.

Optionally, in the method for implementing off-axis illumination, the step of translating the pupil position includes:

and adjusting the inclination angle of the reflection unit to enable the light beams to be obliquely incident to the coupling unit, so that the pupil position formed on the pupil plane of the zoom lens group is translated.

Optionally, in the method for implementing off-axis illumination, when the inclination angle of the reflection unit is adjusted, the reflection unit is inclined along one or two directions perpendicular to the optical axis, so that a dipole or quadrupole and centrosymmetric off-axis illumination field can be formed.

Optionally, in the method for implementing off-axis illumination, the light source is a laser light source, the off-axis illumination device further includes a beam expander for collimating and expanding a laser beam and then irradiating the laser beam to the reflection unit, the coupling unit further includes a first diffractive optical element and a second diffractive optical element, and the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged and coaxially arranged.

and moving the reflecting unit and at least the zoom lens group in the coupling unit together along one or two directions vertical to the optical axis, so that the pupil position formed on the pupil plane of the zoom lens group is translated, and a dipolar or quadrupolar off-axis illumination field with central symmetry can be formed.

Optionally, in the method for implementing off-axis illumination, the light source is a laser light source, the off-axis illumination device further includes a beam expander, configured to collimate and expand a beam of a laser beam and then irradiate the laser beam to the reflection unit, the coupling unit further includes a first diffractive optical element and a second diffractive optical element, the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged, and the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are coaxially arranged;

when the reflection unit and at least the zoom lens group in the coupling unit are moved together along one or two directions perpendicular to the optical axis, the first diffractive optical element is also moved together with the reflection unit and the zoom lens group.

and moving the light source, the reflecting unit and the zoom lens group together along one or two directions vertical to the optical axis so as to enable the pupil position formed on the pupil plane of the zoom lens group to translate, thereby forming an off-axis illumination field with dipole or quadrupole and central symmetry.

Optionally, in the method for realizing off-axis illumination, the light source is a mercury lamp, the reflecting unit comprises an ellipsoidal reflector, and the mercury lamp is positioned at one focus of the ellipsoidal reflector.

two wedge-shaped flat plates are arranged between the zoom lens group and the converging lens group, and inclined surfaces of the two wedge-shaped flat plates are arranged face to face;

and increasing the distance between the two wedge-shaped flat plates and enabling the wedge angle to face the direction vertical to the optical axis, so that the pupil position formed on the pupil plane of the zoom lens group is translated, and further an off-axis illumination field with dipole or quadrupole and central symmetry can be formed.

Optionally, in the method for implementing off-axis illumination, the light source is a laser light source, the off-axis illumination device further includes a beam expander for collimating and expanding a beam of a laser beam and then irradiating the beam to the reflection unit, the coupling unit further includes a first diffractive optical element and a second diffractive optical element, the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged and coaxially arranged, and the two wedge-shaped flat plates are located between the zoom lens group and the second diffractive optical element.

In order to achieve the above object, the present invention further provides an off-axis illumination device, which includes a light source, and a reflection unit, a coupling unit, a light uniformizing unit and a relay lens group which are sequentially arranged, wherein the coupling unit at least includes a zoom lens group and a converging lens group, and the converging lens group is located between the zoom lens group and the light uniformizing unit;

the off-axis illumination device further comprises a position adjusting unit, wherein the position adjusting unit is used for translating the pupil position before the light beam is projected to the dodging unit, so that the light beam is incident to the dodging unit in an asymmetrical mode, and the dodging unit is used for dodging the incident asymmetrical light beam to form an off-axis illumination field.

Optionally, in the off-axis illumination apparatus, the propagation process of the light beam is: the light beam emitted by the light source is reflected by the reflection unit and then enters the coupling unit, the coupling unit further couples the incident light beam and then projects the incident light beam to the light uniformizing unit, and the light uniformizing unit further uniformizes the incident light beam and then projects the incident light beam to the relay lens group.

Optionally, in the off-axis illumination apparatus, the position adjusting unit is connected to the reflecting unit, and is configured to adjust an inclination angle of the reflecting unit, so that the light beam is obliquely incident on the coupling unit, and a pupil position formed on a pupil plane of the zoom lens group is translated.

Optionally, in the off-axis illumination device, the position adjusting unit is configured to tilt the reflection unit in one or two directions perpendicular to the optical axis when adjusting the tilt angle of the reflection unit, so as to form an off-axis illumination field with dipole or quadrupole and central symmetry.

Optionally, in the off-axis illumination device, the light source is a laser light source, the off-axis illumination device further includes a beam expander for collimating and expanding a beam of a laser beam and then irradiating the beam to the reflection unit, the coupling unit further includes a first diffractive optical element and a second diffractive optical element, and the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged and coaxially arranged.

Optionally, in the off-axis illumination apparatus, the off-axis illumination apparatus further comprises a movable assembly, the movable assembly comprises the reflection unit and at least the zoom lens group in the coupling unit;

the position adjusting unit is connected with the movable assembly and used for driving the movable assembly to move along one or two directions vertical to the optical axis, so that the pupil position formed on the pupil plane of the zoom lens group is translated to form an off-axis illumination field with dipole or quadrupole and central symmetry.

Optionally, in the off-axis illumination device, the light source is a laser light source, the off-axis illumination device further includes a beam expander, configured to collimate and expand a beam of a laser beam and then irradiate the laser beam to the reflection unit, the coupling unit further includes a first diffractive optical element and a second diffractive optical element, the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit, and the relay lens group are sequentially arranged, and the second diffractive optical element, the converging lens group, the dodging unit, and the relay lens group are coaxially arranged; the movable assembly further includes the first diffractive optical element.

Optionally, in the off-axis illumination apparatus, the off-axis illumination apparatus further comprises a movable assembly, the movable assembly comprises the light source, the reflection unit and the zoom lens group;

the position adjusting unit is connected with the movable assembly and used for driving the movable assembly to move along one or two directions vertical to the optical axis, so that the pupil position formed on the pupil plane of the zoom lens group is translated, and a dipolar or quadrupole off-axis illumination field with central symmetry can be formed.

Alternatively, in the off-axis illumination apparatus, the light source is a mercury lamp, the reflection unit includes an ellipsoidal mirror, and the mercury lamp is located at one focal point of the ellipsoidal mirror.

Optionally, in the off-axis illumination apparatus, the off-axis illumination apparatus further includes a movable assembly, the movable assembly includes two wedge-shaped flat plates, the two wedge-shaped flat plates are disposed between the zoom lens group and the converging lens group, and inclined surfaces of the two wedge-shaped flat plates are arranged face to face;

the position adjusting unit is connected with the movable assembly and used for adjusting the distance between the two wedge-shaped flat plates and the orientation of a wedge angle, so that the pupil position formed on the pupil plane of the zoom lens group is translated, and further an off-axis illumination field with dipole or quadrupole and central symmetry is formed.

Optionally, in the off-axis illumination device, the light source is a laser light source, the off-axis illumination device further includes a beam expander for incidenting to after laser beam collimation and beam expansion the reflection unit, the coupling unit further includes a first diffractive optical element and a second diffractive optical element, the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the convergence lens group, the dodging unit and the relay lens group are arranged in sequence and coaxially arranged, and two wedge-shaped flat plates are located between the zoom lens group and the second diffractive optical element.

Optionally, in the off-axis illumination device, the dodging unit is a dodging integrator rod, and the length of the dodging integrator rod is configured to allow the light beam to be reflected at least six times within the dodging integrator rod.

In order to achieve the above object, the present invention further provides an exposure system, including any one of the off-axis illumination apparatuses, the exposure system further includes a mask plate, a projection objective, and a stage; the mask plate is located between the projection objective and the relay lens group, and the workpiece stage is located on one side, away from the relay lens group, of the projection objective.

In order to achieve the above object, the present invention further provides a lithography machine, which is characterized by comprising the exposure system.

The photoetching machine, the exposure system, the off-axis illumination method and the off-axis illumination device have the following advantages that:

when off-axis illumination is realized, incident beams are emitted into the dodging unit in an asymmetrical mode, and then the dodging unit performs dodging treatment on asymmetrical beams to form an off-axis illumination view field, so that under the condition that pupil uniformity is ensured, energy loss of off-axis illumination can be reduced, and yield is improved; meanwhile, the parts used for adjusting the light path have simple structures and are convenient to process, so that the cost can be reduced, and the space can be saved.

Drawings

The drawings are included to provide a better understanding of the invention and are not to be construed as unduly limiting the invention. Wherein:

FIG. 1a is a schematic diagram of an off-axis illumination apparatus using a laser light source according to a first embodiment of the present invention, wherein a light beam is perpendicularly incident on a first diffractive optical element;

FIG. 1b is a schematic structural diagram illustrating a pupil position shift after a change in the tilt angle of a mirror according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram of a dodging unit for dodging a light beam according to a first embodiment of the present invention;

fig. 3 is a schematic diagram of a first embodiment of the present invention, in which (a) outgoing beams are symmetrically distributed along the Y direction, (b) outgoing beams are symmetrically distributed along the X direction, and (c) outgoing beams are symmetrically distributed along both the X direction and the Y direction;

FIG. 4 is a schematic view illustrating a gradual increase of a pupil when a focal length of the zoom lens assembly according to the first embodiment of the present invention increases from top to bottom;

FIG. 5a is a state diagram illustrating the gradual transition of the field of view of illumination to two-pole off-axis illumination along the Y-direction as the tilt angle of the reflector is gradually increased from left to right according to the first embodiment of the present invention;

FIG. 5b is a state diagram illustrating the gradual transition of the field of view of illumination to two-pole off-axis illumination along the X-direction as the tilt angle of the reflector is gradually increased from left to right according to the first embodiment of the present invention;

FIG. 5c is a state change diagram illustrating the gradual transition of the illumination field to quadrupole off-axis illumination in the X-direction and the Y-direction as the tilt angle of the mirror is gradually increased from left to right according to the first embodiment of the present invention;

FIG. 5d is a diagram illustrating the change of the illumination field when the focal length of the zoom lens assembly according to the first embodiment of the present invention increases from left to right;

FIG. 6a is a schematic structural diagram of an off-axis illumination apparatus using a laser light source according to a second embodiment of the present invention, wherein the movable assembly is in an initial position;

FIG. 6b is a schematic diagram of a pupil position shift after the movable assembly has shifted according to the second embodiment of the present invention;

FIG. 7a is a schematic structural diagram of an off-axis illumination apparatus using a mercury lamp according to a third embodiment of the present invention, in which a movable assembly is in an initial position;

FIG. 7b is a schematic diagram of a movable assembly according to a third embodiment of the present invention, showing the pupil position translated after translation;

FIG. 8a is a schematic structural view of an off-axis illumination apparatus using a laser light source according to a fourth embodiment of the present invention, in which two wedge-shaped plates are attached to each other to be in an initial position;

fig. 8b is a schematic structural diagram illustrating a pupil position shift when two wedge plates are separated from each other and the wedge angle is oriented to a predetermined direction according to a fourth embodiment of the present invention;

FIG. 9a is a schematic structural view of an off-axis illumination apparatus using a mercury lamp according to a fourth embodiment of the present invention, in which two wedge-shaped plates are attached to each other in an initial position;

fig. 9b is a schematic structural diagram illustrating a pupil position shift when two wedge plates are separated from each other and the wedge angle is oriented to a predetermined direction according to a fourth embodiment of the present invention;

fig. 10 is a schematic structural diagram of an exposure system according to a fifth embodiment of the present invention.

In the figure:

101-a light source;

102-a beam expander;

103-a mirror;

104-a first diffractive optical element;

105. 1003-zoom lens group;

106-a second diffractive optical element;

107. 1005-a converging lens group;

108. 1006, 205-dodging integrator rod; 1081-an inlet port; 1082-outlet end;

109. 1007, 204-relay lens group;

110-an image plane;

111-a position adjustment unit;

901. 1004 — a movable assembly;

1001-mercury lamps;

1002-an ellipsoidal mirror;

1101-a first wedge-shaped plate;

1102-a second wedge plate;

201-mask plate;

202-projection objective;

203-a workbench;

1. 2, 3, 4-ray.

Detailed Description

The invention is described in further detail below with reference to the figures and the detailed description. Advantages and features of the present invention will become more apparent from the following description, which is given to enable those skilled in the art to fully and effectively understand the nature of the present invention and to repeatedly implement the technical solution described above, while understanding the content of the present invention. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. The term "plurality" is generally used in a sense that it includes two or more.

The core idea of the invention is to provide a method for realizing off-axis illumination, which is based on an off-axis illumination device. The off-axis illumination device comprises a light source, and a reflection unit, a coupling unit, a light homogenizing unit and a relay lens group which are sequentially arranged, wherein the coupling unit at least comprises a zoom lens group and a converging lens group, and the converging lens group is positioned between the zoom lens group and the light homogenizing unit.

In practical application, before the light beam is projected to the dodging unit, the pupil position is translated, so that the light beam in the translated pupil is asymmetrically incident to the dodging unit, and the dodging unit forms an off-axis illumination field, preferably a centrosymmetric off-axis illumination field, after the incident asymmetric light beam is dodged. Further, the propagation process of the light beam is as follows: the light source is used for emitting light beams to the coupling unit after being reflected by the reflection unit, the coupling unit is used for further coupling the light beams and then projecting the light beams to the dodging unit, the dodging unit is used for further dodging the light beams and then projecting the light beams to the relay lens group, and the light beams are asymmetrically incident to the dodging unit.

In this way, compared with the light beam symmetrically injected into the dodging unit, the uniformity of the pupil can be ensured, the energy loss can be reduced, and the yield is improved. Meanwhile, the adjusting device can use parts with simple structure and low processing cost to complete the adjustment of the light path, and compared with the existing axicon group, the adjusting device has low cost, can save axial space and is convenient to install and use.

Further, in order to realize the adjustment of the pupil position, in the off-axis illumination apparatus of the present invention, a position adjustment unit is further included for adjusting a propagation direction of the light beam such that the pupil position of the light beam is translated before being projected to the dodging unit, so that the light beam is incident to the dodging unit in an asymmetric manner. In the present invention, there are various schemes for realizing the pupil position adjustment.

In a first solution, the position adjusting unit is connected to the reflection unit, and is configured to adjust an inclination angle of the reflection unit, so that the light beam is obliquely incident on the coupling unit, and a pupil position formed on a pupil plane of the zoom lens group is translated.

In a second solution, the position adjusting unit is connected to a movable assembly, the movable assembly includes the reflecting unit and at least the zoom lens group in the coupling unit, and the movable assembly is driven to move along one or two directions perpendicular to the optical axis, so that a pupil formed on a pupil plane of the zoom lens group also translates along the corresponding direction, and finally, an off-axis illumination field with dipole or quadrupole and central symmetry is formed at the exit end of the dodging unit.

In a third solution, the position adjusting unit is connected to a movable assembly, and the movable assembly includes the light source, the reflecting unit and the zoom lens group in the coupling unit, so that by driving the movable assembly to move along one or two directions perpendicular to the optical axis, the pupil formed on the pupil plane of the zoom lens group also translates along the corresponding direction, and finally, an off-axis illumination field with dipole or quadrupole and central symmetry is formed at the exit end of the dodging unit.

In addition to the above method, a fourth solution is provided, specifically, two wedge-shaped flat plates are disposed between the zoom lens group and the converging lens group, the two wedge-shaped flat plates form a movable assembly, and the position adjusting unit is connected to the movable assembly to change the distance between the two wedge-shaped flat plates and the orientation of the wedge angle through the position adjusting unit. In particular, when the distance between the wedge-shaped plates increases and the wedge angle faces to the direction perpendicular to the optical axis, the pupil position formed on the pupil plane of the zoom lens group can be translated, so as to form an off-axis illumination field with dipole or quadrupole and central symmetry.

The above modes can adjust the position of the pupil formed on the pupil plane of the zoom lens group, so that the light beams are projected onto the light homogenizing unit in an asymmetrical mode, and the light homogenizing unit modulates the incident light beams into symmetrical distribution and forms an off-axis illumination view field with symmetrical center.

The method for realizing off-axis illumination according to the present invention is further described with reference to the accompanying drawings and several embodiments.

Example one

Fig. 1a is a schematic structural diagram of an off-axis illumination apparatus according to a first embodiment of the present invention, in which various optical components are shown in a simplified manner, but those skilled in the art should know how to implement these optical components, as this is well known in the art.

As shown in fig. 1a, the off-axis illumination apparatus of the present embodiment includes a light source 101, a reflector 103, a first diffractive optical element 104, a zoom lens group 105, a second diffractive optical element 106, a converging lens group 107, a dodging integrator rod 108, and a relay lens group 109. The reflecting mirror 103 constitutes a reflecting unit, but the reflecting mirror 103 may be one or more, and optionally, the reflecting mirror 103 is a plane reflecting mirror, or the reflecting mirror 103 may also be composed of two concave mirrors. The first diffractive optical element 104, the zoom lens group 105, the second diffractive optical element 106, and the condensing lens group 107 constitute a coupling unit. The integrator rod 108 constitutes a light uniformizing unit for uniformizing the incident light beam. In the present embodiment, the light source 101 may be a laser light source, and this is taken as an example for explanation in the following description, but should not be taken as a limitation of the present invention.

In the laser light source, the off-axis illumination device further includes a beam expander 102, configured to collimate and expand the laser beam and then enter the reflector 103. The reflecting mirror 103, the first diffractive optical element 104, the zoom lens group 105, the second diffractive optical element 106, the converging lens group 107, the dodging integrator rod 108 and the relay lens group 109 are sequentially arranged and coaxially arranged. In practical use, the off-axis illumination device of the embodiment is used for providing an off-axis illumination field, especially an off-axis illumination field with central symmetry, and can be applied to not only lithography exposure equipment, but also other situations requiring off-axis illumination. In addition, the off-axis illumination device of the embodiment mainly uses the dodging integrator rod 108 as a dodging unit, the dodging integrator rod 108 further homogenizes the incident angle of the incident light beam, and finally modulates the emergent light beam into a symmetrical distribution characteristic to form a plurality of off-axis illumination fields with central symmetry, that is, the dodging integrator rod 108 can homogenize the oblique incident light beam to form a plurality of off-axis illumination schemes with central symmetry.

In more detail, as shown in fig. 1a, a laser beam emitted from a light source 101 is collimated and expanded by a beam expander 102, and then enters a reflector 103, and then enters a first diffractive optical element 104 after being reflected by the reflector 103, the first diffractive optical element 104 diffracts the incident beam to form a certain angle distribution, and the first diffractive optical element 104 forms a certain pupil distribution on a pupil plane of a zoom lens group 105 together with the zoom lens group 105. The second diffractive optical element 106 is located on the pupil plane, and the second diffractive optical element 106 and the converging lens group 107 together form a light spot (or called pupil) on the image plane of the converging lens group 107, the aperture of which is matched with that of the dodging integrator rod 108, so that the light beams can completely enter the dodging integrator rod 108 without damaging the dodging integrator rod 108. The light receiving surface of the light homogenizing rod 108 is located on the image surface of the converging lens group 107, and the light beam entering the light homogenizing rod 108 is subjected to light homogenizing treatment, so that a uniform illumination field is formed at the outlet end of the light homogenizing rod 108. The object plane of the relay lens group 109 is located at the exit end of the integrator rod 108, and the illumination field is scaled up and forms an illumination field with a certain wavelength with a desired uniformity on the image plane 110 of the relay lens group 109, and the image plane 110 may be a mask plane in a non-limiting application example. Further, in order to form an off-axis illumination field on the image plane 110, the pupil on the pupil plane needs to be further translated, so that the light beam in the translated pupil is incident to the integrator rod 108 in an asymmetric manner, and the integrator rod 108 further homogenizes the incident asymmetric light beam to form the off-axis illumination field (see fig. 1 b).

In the present embodiment, in order to shift the pupil position, it is realized to adjust the tilt angle of the mirror 103 so that the light beam is obliquely incident to the first diffractive optical element 104, as shown in fig. 1 b. It should be understood that, when the angle between the mirror 103 and the optical axis L1 is 45 °, the light beam is perpendicularly incident to the first diffractive optical element 104, and further adjusting the angle between the mirror 103 and the optical axis L1 can change the reflection direction of the reflected light beam to make the light beam obliquely incident, so as to change the propagation direction of the optical path, so that the imaging position of the light beam is shifted, and the pupil formed on the pupil plane is asymmetrically distributed, and the light beam incident to the integrator rod 108 is also asymmetrically distributed.

Preferably, the off-axis illumination device further comprises a position adjusting unit 111 connected to the reflector 103 for adjusting the inclination angle of the reflector 103, so as to ensure the rotation precision of the reflector and ensure the imaging quality.

Referring specifically to fig. 1b, a spatial rectangular coordinate system XYZ is established, and the Z-axis is disposed along the optical axis L1, and both the X-axis and the Y-axis are perpendicular to the optical axis L1. When the angle between the mirror 103 and the optical axis is 45 °, the light beam enters the first diffractive optical element 104 perpendicularly, and the pupil on the pupil plane is distributed symmetrically without forming an off-axis illumination field, as shown in fig. 1 a. As shown in fig. 1b, when the position adjustment unit 111 drives the mirror 103 to rotate to change the inclination angle of the mirror 103, the light beam obliquely enters the first diffractive optical element 104, so that the light beam propagates away from the optical axis, and the incident light beam entering the integrator rod 108 is asymmetrically distributed, that is, the axis of the pupil at the entrance end of the integrator rod 108 does not coincide with the optical axis L1.

As shown in fig. 2, integrator rod 108 is typically made of quartz material, and homogenizes the incident angle of the light beam, and finally modulates the emergent angle of the light beam into a symmetrical distribution. Specifically, the light ray 1 enters at the same angle (including the same direction) as the light ray 2, but exits at a symmetrically opposite angle, and similarly, the light ray 3 enters at the same angle (including the same direction) as the light ray 4 and exits at a symmetrically opposite angle. Herein, the vertical direction is along the Y-axis direction, and the horizontal direction is along the X-axis direction, as follows.

Specifically, when the pupil of the incident light beam (i.e. the light beam entering the integrator rod) has only an upper light beam, the pupil of the emergent light beam after passing through the integrator rod 108 includes both the upper light beam and the lower light beam; similarly, when the pupil of the incident light beam only has a left light ray, the pupil of the emergent light beam after passing through the light homogenizing integrator rod 108 includes both the left light ray and the right light ray; or, when the pupil of the incident light beam has only the upper left light, the pupil of the emergent light beam after passing through the integrator rod 108 includes both the upper left light and the lower left light, the upper right light and the lower right light. The other entrance pupils are the same. Therefore, even if the entrance pupil is on one side, the exit pupil becomes a symmetrical distribution after passing through the integrator rod 108.

More specifically, as shown in FIG. 3, when the mirror 103 is adjusted in different directions, the translational directions of the pupil will also be different, where the black circles represent the pupil. As shown in fig. 3 (a), if the position adjustment unit 111 drives the mirror 103 to tilt in the Y-axis direction (i.e., to rotate around the X-axis), the pupil is deviated from the optical axis in the Y-axis direction, i.e., a single-sided pupil distributed along the Y-axis is formed at the entrance end 1081 of the integrator rod 108, and two pupils distributed vertically symmetrically are formed at the exit end 1082 of the integrator rod 108, i.e., two-pole off-axis illumination in the Y-axis direction is formed. Alternatively, as shown in fig. 3 (b), if the position adjustment unit 111 drives the mirror 103 to tilt in the X-axis direction (i.e., to rotate around the Y-axis), the pupil is deviated from the optical axis in the Y-axis direction, i.e., a single-sided pupil distributed in the X-axis is formed at the entrance end 1081 of the integrator rod 108, and two pupils distributed in bilateral symmetry are formed at the exit end 1082 of the integrator rod 108, i.e., two-pole off-axis illumination in the X-axis is formed. Still alternatively, as shown in fig. 3 (c), if the position adjusting unit 111 drives the mirror 103 to tilt in both the X-axis and Y-axis directions, the pupil is deviated from the optical axis in both the X-axis and Y-axis directions, that is, a single-sided pupil deviated from the X-axis and Y-axis distributions is formed at the entrance end 1081 of the integrator rod 108, and further four pupils distributed symmetrically up and down and left and right are formed at the exit end 1082 of the integrator rod 108, that is, quadrupole off-axis illumination in the X and Y directions is formed. And different tilt angles, the amount of pupil translation is also different. Since the zoom lens group 105 has an image-side telecentric structure, the relationship between the translation amount d of the pupil and the tilt angle θ of the mirror is:

d＝f×tan(θ)；

wherein: f is the focal length of the zoom lens group; the inclination angle θ is an angle formed by rotating relative to an initial angle of the reflector, which is an angle of 45 ° with respect to the optical axis.

Further, simulation experiments also show that the distribution of the pupil can be effectively changed and a plurality of off-axis illumination schemes with central symmetry can be formed by changing the inclination angle of the reflector. In the following description, the mirror 103 is tilted from an initial position, that is, a position at which the angle between the mirror and the optical axis is 45 ° and the light beam is incident perpendicularly on the first diffractive optical element 104.

As shown in fig. 5a, when the position adjusting unit 111 drives the mirror 103 to tilt along the Y direction (i.e. rotate around the X axis), the distribution of the exit pupil of the light beam passing through the dodging integrator rod 108 changes with the change of the tilt angle, specifically, the tilt angle is gradually increased, the exit pupil gradually forms an off-axis illumination field with a vertically symmetric distribution from left to right from the initial single illumination field S, and meanwhile, the coherence factor of the two-pole off-axis illumination can be changed by changing the size of the tilt angle θ.

As shown in fig. 5b, when the position adjustment unit 111 drives the mirror 103 to tilt in the X direction (i.e. rotate around the Y axis), the distribution of the exit pupil of the light beam passing through the integrator rod 108 changes with the change of the tilt angle, and as the tilt angle gradually increases, the exit pupil gradually forms an off-axis illumination field of left-right symmetric distribution from the initial single illumination field S from left to right, and the coherence factor of the two-pole off-axis illumination can also be changed by changing the size of the tilt angle θ.

As shown in fig. 5c, when the position adjusting unit 111 drives the mirror 103 to tilt in the X direction and the Y direction simultaneously, the distribution of the exit pupil of the light beam after passing through the dodging integration rod 108 changes with the change of the tilt angle, and similarly, with the increase of the tilt angle, the exit pupil gradually forms an off-axis illumination field from left to right, which is symmetrically distributed from the initial two illumination fields S, and the size of the coherence factor of the quadrupole off-axis illumination can also be changed by changing the size of the tilt angle θ.

In addition, by adjusting the focal length of the zoom lens group 105, the size of the off-axis illumination coherence factor ring width and the size of the polar aperture angle can be changed. Taking the adjustment in the Y direction as an example, as shown in fig. 5d, the focal length is gradually increased from left to right, the coherence factor ring width of each illumination field S is increased, and the polar angle is also increased. Similarly, the size of the coherence factor ring width and the size of the polar opening angle of the off-axis illumination can be changed by the X-direction two-pole off-axis illumination and the four-pole off-axis illumination. In more detail, referring to fig. 4, when the pupil is not shifted, by adjusting the focal length of the zoom lens assembly 105, the light intensity of the pupil plane can be changed, and the pupil size of the whole illumination apparatus and the coherence factor can be further changed, for example, from (a) to (d), i.e. from top to bottom, the focal length of the zoom lens assembly 105 is sequentially decreased, and the pupil size is increased accordingly, based on this principle, the situation shown in fig. 5d can be realized.

Further, considering that the incident light beam of the integrator rod 108 is obliquely incident, it has a certain influence on the symmetry of the exit pupil. To ensure the dodging effect, it is preferable that the length of integrator rod 108 be such that the incident beam undergoes at least 6 reflections within integrator rod 108. In this embodiment, on the basis of the existing dodging integration rod, the length of the dodging integration rod 108 is preferably increased by 50%, so as to ensure pupil symmetry and dodging effect. However, the integrator rod 108 cannot be too long, too short, and cannot ensure the light homogenizing effect, and too long causes energy loss, and therefore, the length can be increased by 50% based on the existing integrator rod to meet the requirement.

In this embodiment, the inclination angle of the reflecting mirror 103 can be adjusted by the position adjusting unit 111 to be inclined in the X direction and/or the Y direction, so that the axis of the pupil of the incident integrator rod 108 is not coincident with the axis of the integrator rod 108, that is, light rays in the pupil are asymmetrically incident on the integrator rod 108, thereby reducing energy loss and improving yield while ensuring pupil symmetry. However, the present invention is not limited to the specific structure of the position adjustment unit 111, and those skilled in the art should understand how to realize one or two degrees of freedom of rotation of the mirror 103 through the related motion mechanism based on the disclosure of the present application, for example, the position adjustment unit 111 may include two rotational joints, one rotational joint driving the mirror 103 to rotate around the X axis to tilt the mirror in the Y direction, and the other rotational joint driving the mirror 103 to rotate around the Y axis to tilt the mirror in the X direction. Further, the second diffractive optical element 106 may be selected as a microlens array.

Example two

The structure of the off-axis illumination device provided in this embodiment is substantially the same as that of the first embodiment, and only different points are described below.

As shown in fig. 6a, the off-axis illumination apparatus further comprises a movable assembly 901, wherein the movable assembly 901 comprises the reflector 103, the zoom lens group 105 and the first diffractive optical element 104. In this embodiment, the movable assembly 901 can be translated in a direction perpendicular to the optical axis L1, i.e. along the X-axis and/or Y-axis, so that the pupil position in the pupil plane is also translated in the same direction.

In practical applications, the position adjusting unit 111 is connected to the movable assembly 901 for driving the movable assembly 901 to translate along the X direction and/or the Y direction, so as to ensure the moving precision of the movable assembly and ensure the imaging quality. Fig. 6a shows the movable assembly 901 in an initial position, in which the pupil is distributed symmetrically in the pupil plane without translation. While the movable assembly 901 may be translated in the X-direction and/or the Y-direction, the pupil positions may be translated synchronously, as shown in particular in fig. 6 b. It should be noted that when the movable assembly 901 is located at the initial position, the reflecting mirror 103, the first diffractive optical element 104, the zoom lens group 105, the second diffractive optical element 106, the converging lens group 108, the integrator rod 108 and the relay lens group 109 are sequentially arranged and coaxially arranged, and when the movable assembly 901 is translated, the stationary optical elements are always kept coaxially.

Based on the same principle, if the position adjustment unit 111 drives the movable assembly 901 to translate in the Y direction, a two-pole off-axis illumination field of view is formed as shown in fig. 5 a; if the position adjustment unit 111 drives the movable assembly 901 to translate in the X-direction, a two-pole off-axis illumination field is formed as shown in fig. 5 b; if the position adjustment unit 111 drives the movable assembly 901 to translate in both the X-direction and the Y-direction, a quadrupole off-axis illumination field of view is formed as shown in fig. 5 c. That is, the exit pupil distribution of the light beam passing through the integrator rod 108 changes with the translation of the movable assembly 901, and becomes a dipole or quadrupole centrosymmetric off-axis illumination in a predetermined direction at a certain amount of translation. Similarly, as the movable assembly is translated, the coherence factor and the polar angle of the off-axis illumination are changed, and the focal length of the zoom lens assembly 105 is changed to change the ring width and the polar angle of the off-axis illumination coherence factor.

However, it should be understood that in this embodiment, the optical axis L1 refers to a symmetry axis of the optical system formed by the second diffractive optical element 106, the converging lens group 107, the integrator rod 108 and the relay lens group 109, and the symmetry axis is always fixed. In addition, the specific structure of the position adjusting unit 111 of the present embodiment is not limited, and for example, the position adjusting unit may include a double-layer guide rail, where a first linear guide rail is disposed along the X direction, a second linear guide rail is disposed on the first linear guide rail and is disposed along the Y direction, and the movable assembly 901 is connected to the second linear guide rail, so that the movable assembly 901 is moved along the X direction and/or the Y direction by the movement of the double-layer linear guide rail.

EXAMPLE III

The structure of the off-axis illumination device provided in this embodiment is different from that of the light source, the reflector and the coupling unit, and the other structure is substantially the same as that of the first embodiment.

As shown in fig. 7a, the off-axis illumination apparatus of the present embodiment includes a mercury lamp 1001, an ellipsoidal reflector 1002, a zoom lens group 1003, a converging lens group 1005, a light homogenizing rod 1006, and a relay lens group 1007; the ellipsoidal reflector 1002, the zoom lens group 1003, the converging lens group 1005, the light homogenizing and integrating rod 1006 and the relay lens group 1007 are sequentially arranged, and the converging lens group 1005, the light homogenizing and integrating rod 1006 and the relay lens group 1007 are coaxially arranged to define an optical axis L1. In this embodiment, the zoom lens group 1003 and the condenser lens group 1005 constitute a coupling unit of the present invention, the mercury lamp 1001 constitutes a light source, and the ellipsoidal mirror 1002 constitutes a reflecting unit, but the mirror used in cooperation with the mercury lamp 1001 is not limited to the ellipsoidal mirror, and may be a parabolic mirror. In actual setting, the mercury lamp 1001 is located at a focus of the ellipsoidal reflector 1002, and in the initial position, the optical axis L1 passes through the symmetry center of the ellipsoidal reflector 1002, that is, in the initial position, the zoom lens group 1003, the converging lens group 1005, the light uniformizing integrator rod 1006, and the relay lens group 1007 are sequentially arranged and coaxially arranged, and the axis passes through the symmetry center of the ellipsoidal reflector 1002.

In practical application, the object plane of the zoom lens group 1003 is located at the light-emitting ends of the mercury lamp 1001 and the ellipsoidal reflector 1002, and the zoom lens group 1003 and the converging lens group 1005 jointly couple light beams emitted by the mercury lamp 1001 and the ellipsoidal reflector 1002 into the light-homogenizing integrator rod 1006. The light receiving surface of the dodging integrator rod 1006 is located on the image surface of the coupling unit, and the light beam is dodged, so that a uniform illumination field of view is formed at the outlet end of the dodging integrator rod 1006. The object plane of the relay lens group 1007 is located at the exit end of the dodging integrator rod 1006. The relay lens group 1007 enlarges the uniform illumination field of view, and forms an illumination field of view with a certain wavelength and uniformity satisfying requirements on the image plane 1008.

As shown in fig. 7b, a mercury lamp 1001, an ellipsoidal mirror 1002, and a zoom lens group 1003 together constitute a movable assembly 1004. As long as movable assembly 1004 is driven to move in the X-direction and/or Y-direction, the position of the pupil can be changed, causing the pupil to translate in the same direction. Preferably, the movable assembly 1004 is connected with the position adjusting unit 111, and the position adjusting unit 111 drives the movable assembly 1004 to integrally translate along the X direction and/or the Y direction, so that the moving precision is improved, and the imaging quality is ensured. More specifically, fig. 7a shows the movable element 1004 in an initial position, in which the pupil formed on the pupil plane is not translated but symmetrically distributed with respect to the optical axis L1, but when the movable element 1004 is translated in a predetermined direction, the pupil is also translated therewith in that direction, i.e. as shown in fig. 7 b.

Based on the same principle, if the position adjustment unit 111 drives the movable assembly 1004 to translate in the Y direction, a two-pole off-axis illumination field of view as shown in fig. 5a is formed; if the position adjustment unit 111 drives the movable assembly 1004 to translate in the X-direction, a two-pole off-axis illumination field of view is formed as shown in fig. 5 b; if the position adjustment unit 111 drives the movable assembly 1004 to translate in both the X-direction and the Y-direction, a quadrupole off-axis illumination field of view is formed as shown in fig. 5 c. That is, the exit pupil distribution of the light beam passing through the integrator rod 1006 changes with the translation of the movable assembly 1004, and becomes a dipole or quadrupole centrosymmetric off-axis illumination along the predetermined direction at a certain amount of translation. Similarly, as the movable assembly moves horizontally, the coherence factor and the polar angle of the off-axis illumination are changed, and the focal length of the zoom lens set 1003 is changed, so that the ring width and the polar angle of the off-axis illumination coherence factor can be changed.

Example four

In contrast to the first embodiment, the present embodiment only provides a movable assembly capable of changing the propagation direction of light between the zoom lens group 105 and the second diffractive optical element 106, and the movable assembly includes two wedge-shaped flat plates, namely a first wedge-shaped flat plate 1101 and a second wedge-shaped flat plate 1102. The first wedge plate 1101 and the second wedge plate 1102 are two plates having the same structure.

In the initial position, as shown in fig. 8a, the inclined surfaces of the two wedge-shaped flat plates are attached to each other, and the structure does not affect the propagation direction of the light beam, so that pupils distributed symmetrically are formed on the pupil plane. And as shown in fig. 8b, when the two wedge-shaped flat plates are separated and staggered by a certain angle around the optical axis, the light beam can be translated after passing through the two wedge-shaped flat plates in sequence. In this embodiment, the second wedge plate 1102 may be kept still, and the first wedge plate 1101 may be translated leftward, and the first wedge plate 1101 may be rotated around the optical axis by a certain angle relative to the initial position, so that the wedge angle of the first wedge plate 1101 is oriented in the X direction or the Y direction, or in a direction forming an angle with the X direction and the Y direction, so that the pupil distribution formed on the pupil plane is translated. In this context, the included angle defined by the inclined planes of the two wedge-shaped plates is the wedge angle.

Preferably, the position adjusting unit 111 is connected to at least one of the two wedge plates to drive the at least one wedge plate to move and rotate, thereby changing a distance between the two wedge plates and orienting the wedge angle in a predetermined direction. For example, the position adjustment unit 111 includes a guide rail arranged in the Z direction, at least one wedge plate is movably disposed on the guide rail, and the wedge plate is further connected with a rotary joint that drives the wedge plate to rotate about the optical axis L1.

More specifically, when the wedge angle direction of the first wedge-shaped flat plate 1101 is oriented to the Y direction, the distance between the two wedge-shaped flat plates is adjusted, and the pupil distribution is translated along the Y direction, so as to form a two-pole off-axis illumination field as shown in fig. 5 a; when the wedge angle direction of the first wedge-shaped flat plate 1101 faces the X direction, the distance between the two wedge-shaped flat plates is adjusted, the pupil distribution will translate along the X direction, and a two-pole off-axis illumination field is formed as shown in fig. 5 b; when the wedge angle direction of the first wedge-shaped plate 1101 is towards the direction forming an included angle with the X direction and the Y direction, the distance between the two wedge-shaped plates is adjusted, and the pupil distribution is translated along the X direction and the Y direction, so as to form the quadrupole off-axis illumination field as shown in fig. 5 c. Similarly, as the wedge-shaped plate is translated, the coherence factor and the polar angle of the off-axis illumination are changed, and the focal length of the zoom lens group 105 is changed, so that the ring width and the polar angle of the off-axis illumination coherence factor can be changed.

Similarly, in the mercury lamp lighting scheme, two wedge-shaped flat plates may also be disposed as above, specifically, as shown in fig. 9a and 9b, only two wedge-shaped flat plates are disposed between the zoom lens group 1003 and the converging lens group 1005, and the implementation manner is as described above and will not be described in detail. It should be noted that the present invention is not limited to moving only one wedge-shaped plate, and can also move two wedge-shaped plates at the same time, or the first wedge-shaped plate is stationary and the second wedge-shaped plate is moving.

EXAMPLE five

Fig. 10 is a schematic structural diagram of an exposure system provided in this embodiment, and referring to fig. 10, the exposure system includes the off-axis illumination apparatus in any one of the embodiments, and further includes a mask plate 201, a projection objective 202, and a workpiece stage 203. The mask plate 201 is located between the projection objective 202 and the relay lens group 204, and the dodging integrator rod 205 is disposed in front of the relay lens group 204, but other components of the off-axis illumination apparatus are omitted in fig. 10. The workpiece stage 203 is located on a side of the projection objective 202 away from the relay lens group 204. An optical axis L2 of the projection objective 202 intersects with an optical axis L1 of the integrator rod 205 in the relay lens group 204, a light beam emitted from a light-emitting surface of the integrator rod 205 irradiates the relay lens group 204 along an optical axis L1, then emits along an optical axis L2 and irradiates on the mask plate 201, and a pattern on the mask plate 201 is projected onto a workpiece (not shown in fig. 10) on the workpiece stage 203, so as to realize exposure of the workpiece. Since the exposure system includes the off-axis illumination device in any of the above embodiments, the advantages associated with the off-axis illumination device are provided, and repeated descriptions are omitted here.

Further, the embodiment of the present invention also provides a lithography machine, which includes the exposure system in the embodiment.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. The off-axis illumination method is based on an off-axis illumination device, the off-axis illumination device comprises a light source, and a reflection unit, a coupling unit, a light homogenizing unit and a relay lens group which are sequentially arranged, the coupling unit at least comprises a zoom lens group and a converging lens group, and the converging lens group is positioned between the zoom lens group and the light homogenizing unit, and the off-axis illumination method is characterized by comprising the following steps:

2. A method for performing off-axis illumination as defined in claim 1, wherein the light beam propagates by: the light source is used for emitting light beams to the coupling unit after being reflected by the reflection unit, the coupling unit is used for further coupling the light beams and then projecting the light beams to the dodging unit, and the dodging unit is used for further dodging the light beams and then projecting the light beams to the relay lens group.

3. A method for performing off-axis illumination as defined in claim 1, wherein translating the pupil position comprises:

4. A method for performing off-axis illumination as claimed in claim 3, wherein the tilting angle of the reflecting unit is adjusted by tilting the reflecting unit in one or two directions perpendicular to the optical axis to form a bi-or quadrupole and centrosymmetric off-axis illumination field.

5. The method for realizing off-axis illumination according to claim 3 or 4, wherein the light source is a laser light source, the off-axis illumination device further comprises a beam expander for collimating and expanding a laser beam and then making the laser beam incident on the reflection unit, the coupling unit further comprises a first diffractive optical element and a second diffractive optical element, and the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged and coaxially arranged.

6. A method for performing off-axis illumination as defined in claim 1, wherein translating the pupil position comprises:

7. The method for realizing off-axis illumination according to claim 6, wherein the light source is a laser light source, the off-axis illumination device further comprises a beam expander for collimating and expanding a laser beam and then irradiating the laser beam to the reflection unit, the coupling unit further comprises a first diffractive optical element and a second diffractive optical element, the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged, and the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are coaxially arranged;

8. A method for performing off-axis illumination as defined in claim 1, wherein translating the pupil position comprises:

9. A method for performing off-axis illumination as defined by claim 8 wherein the light source is a mercury lamp and the reflecting unit comprises an ellipsoidal reflector, the mercury lamp being located at one focal point of the ellipsoidal reflector.

10. A method for performing off-axis illumination as defined in claim 1, wherein translating the pupil position comprises:

11. The method according to claim 10, wherein the light source is a laser light source, the off-axis illumination device further comprises a beam expander for collimating and expanding a laser beam and then irradiating the laser beam to the reflection unit, the coupling unit further comprises a first diffractive optical element and a second diffractive optical element, the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the convergence lens group, the dodging unit and the relay lens group are sequentially arranged and coaxially arranged, and the two wedge-shaped flat plates are located between the zoom lens group and the second diffractive optical element.

12. A method for performing off-axis illumination as defined by claim 10 wherein the light source is a mercury lamp and the reflecting means comprises an ellipsoidal reflector, the mercury lamp being located at one focal point of the ellipsoidal reflector.

13. An off-axis illumination device is characterized by comprising a light source, a reflection unit, a coupling unit, a light homogenizing unit and a relay lens group which are sequentially arranged, wherein the coupling unit at least comprises a zoom lens group and a converging lens group, and the converging lens group is positioned between the zoom lens group and the light homogenizing unit;

14. An off-axis illumination device as claimed in claim 13, wherein the light beam propagates by: the light beam emitted by the light source is reflected by the reflection unit and then enters the coupling unit, the coupling unit further couples the incident light beam and then projects the incident light beam to the light uniformizing unit, and the light uniformizing unit further uniformizes the incident light beam and then projects the incident light beam to the relay lens group.

15. An off-axis illumination device according to claim 13, wherein the position adjustment unit is connected to the reflection unit for adjusting the tilt angle of the reflection unit such that the light beam is obliquely incident on the coupling unit and the pupil position formed on the pupil plane of the zoom lens group is translated.

16. An off-axis illumination device as claimed in claim 15, wherein the position adjustment unit is adapted to tilt the reflection unit in one or two directions perpendicular to the optical axis to form a dipole or quadrupole and centrosymmetric off-axis illumination field when adjusting the tilt angle of the reflection unit.

17. An off-axis illumination device as claimed in claim 15 or 16, wherein the light source is a laser light source, the off-axis illumination device further comprises a beam expander for collimating and expanding the laser beam and then irradiating the laser beam to the reflection unit, the coupling unit further comprises a first diffractive optical element and a second diffractive optical element, and the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged and coaxially arranged.

18. An off-axis illumination device according to claim 13 further comprising a movable assembly comprising the reflection unit and at least the zoom lens group in the coupling unit;

19. An off-axis illumination device as claimed in claim 18, wherein the light source is a laser light source, the off-axis illumination device further comprises a beam expander for collimating and expanding the laser beam and then irradiating the laser beam to the reflection unit, the coupling unit further comprises a first diffractive optical element and a second diffractive optical element, the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged, and the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are coaxially arranged; the movable assembly further includes the first diffractive optical element.

20. An off-axis illumination device as claimed in claim 13, further comprising a movable assembly comprising the light source, the reflection unit and the zoom lens group;

21. An off-axis illumination device as claimed in claim 20, wherein the light source is a mercury lamp, the reflecting unit comprises an ellipsoidal reflector, and the mercury lamp is located at one focal point of the ellipsoidal reflector.

22. An off-axis illumination device as claimed in claim 13, further comprising a movable assembly comprising two wedge-shaped plates disposed between the zoom lens group and the collection lens group with their slopes arranged face to face;

23. An off-axis illumination device as claimed in claim 22, wherein the light source is a laser light source, the off-axis illumination device further comprises a beam expander for collimating and expanding the laser beam and then irradiating the laser beam to the reflection unit, the coupling unit further comprises a first diffractive optical element and a second diffractive optical element, the reflection unit, the first diffractive optical element, the zoom lens group, the second diffractive optical element, the converging lens group, the dodging unit and the relay lens group are sequentially arranged and coaxially arranged, and two wedge-shaped flat plates are located between the zoom lens group and the second diffractive optical element.

24. An off-axis illumination device as claimed in claim 22, wherein the light source is a mercury lamp, the reflecting unit comprises an ellipsoidal reflector, and the mercury lamp is located at one focal point of the ellipsoidal reflector.

25. An off-axis illumination device as claimed in claim 13, wherein the integrator bar is of a length configured to allow the beam of light to reflect at least six times within the integrator bar.

26. An exposure system comprising the off-axis illumination apparatus of any one of claims 13-25, the exposure system further comprising a reticle, a projection objective, and a workpiece stage; the mask plate is located between the projection objective and the relay lens group, and the workpiece stage is located on one side, away from the relay lens group, of the projection objective.

27. A lithography machine comprising the exposure system of claim 26.