Alignment device, photolithography machine and alignment method

Abstract

The present invention provides an alignment device, a photolithography machine and an alignment method. The illumination provided by the illumination unit generates diffracted light after passing through a grating mark. The spectroscopic unit divides the light field of the diffracted light into at least two sub-light fields. The diffracted light in each sub-light field enters a corresponding detection lens group and generates interference to form interference light. The interference light is divided into a first polarized light and a second polarized light by a first polarization beam splitter prism. The two detectors respectively obtain the light energy of the first polarized light and the second polarized light. When the grating mark is moved until the light energy obtained by each detector reaches a preset value, the position of the grating mark is the alignment position. Therefore, the present invention uses the spectroscopic unit to divide at least two sub-light fields, realizes the interference of the diffracted light in each sub-light field through the detection unit, and then uses a plurality of the detectors for detection, thereby greatly improving the alignment accuracy, and can achieve position alignment without using a self-reference interference prism, which not only reduces the cost but also is simple to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to an alignment device, a photolithography machine and an alignment method. Background Art

[0002] In the field of integrated circuit manufacturing technology, a photolithography machine can apply a mask pattern to a photosensitive film layer such as a photoresist on a silicon wafer (also called a substrate) to prepare the desired circuit structure. In order to accurately control the position of each photolithography on the silicon wafer, it is necessary to set photolithography alignment marks (usually grating marks) on the silicon wafer, and determine the position of the corresponding photolithography alignment marks on the silicon wafer by setting one or more corresponding alignment devices, thereby determining the alignment position of the silicon wafer.

[0003] Currently, commonly used alignment devices use self-referencing interference prisms to achieve interference of diffracted light, and then determine the position of grating marks on silicon wafers. However, alignment devices based on self-referencing interference prisms have some unavoidable defects. For example, self-referencing interference prisms use prism components that require special optical design and manufacturing, which have high processing indicators, are difficult to assemble and adjust, and require high costs; and self-referencing interference prisms are usually bulky, which will produce some negative effects such as low-bandwidth vibration modes, which will ultimately affect the alignment accuracy.

[0004] Therefore, a new alignment device and alignment method are needed to avoid the disadvantages of using a self-referencing interference prism, so as to reduce the alignment measurement cost and improve the alignment accuracy. Summary of the invention

[0005] An object of the present invention is to provide an alignment device, a photolithography machine and an alignment method to solve at least one of the problems of high alignment measurement cost and low alignment accuracy.

[0006] In order to solve the above technical problems, the present invention provides an alignment device, which comprises: an illumination unit, a spectroscopic unit and a detection unit;

[0007] The illumination unit is used to provide illumination; the illumination is diffracted after passing through a grating mark and generates diffracted light arranged in at least one direction, and the diffracted light enters the light splitting unit;

[0008] The light splitting unit includes at least one light splitting mirror group, which is used to split the light field of the diffracted light into at least two sub-light fields, each of which includes diffracted light with a first polarization direction and diffracted light with a second polarization direction;

[0009] The detection unit comprises at least two detection mirror groups and at least four detectors, each of the detection mirror groups comprises a first wave plate and a first polarization beam splitter prism, and each of the detection mirror groups is configured with two of the detectors;

[0010] Wherein, the diffracted light in each of the sub-light fields enters one of the detection mirror groups accordingly, and the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change their polarization directions after being transmitted through the first wave plate, so as to interfere in the first polarization direction and the second polarization direction respectively and form interference light; the interference light enters the first polarization beam splitter prism, and is split into the first polarization light and the second polarization light by the first polarization beam splitter prism; one of the detectors corresponding to the detection mirror group acquires the light energy of the first polarization light, and another of the detectors corresponding to the detection mirror group acquires the light energy of the second polarization light;

[0011] When the grating mark is moved until the light energy acquired by each detector corresponding to each detection lens group reaches a preset value, the position of the grating mark is the alignment position.

[0012] Optionally, in the alignment device, the first polarization direction and the second polarization direction are perpendicular to each other.

[0013] Optionally, in the alignment device, the first polarized light has a first polarization direction, and the second polarized light has a second polarization direction.

[0014] Optionally, in the alignment device, when the diffracted light is arranged in one direction, the beam splitter unit includes a first beam splitter group, the first beam splitter group includes a second polarization beam splitter prism, a third polarization beam splitter prism, a second wave plate, a third wave plate and a first reflector; the detection unit includes a first detection mirror group, a first detector, a second detector, a second detection mirror group, a third detector and a fourth detector; wherein,

[0015] The negative-order diffracted light in the diffracted light is divided into a first diffracted light having a first polarization direction and a second diffracted light having a second polarization direction after passing through the second polarization beam splitter prism; after the first diffracted light is reflected by the second polarization beam splitter prism, it is first transmitted through the second wave plate to change the polarization direction to the second polarization direction, and then passes through the third polarization beam splitter prism to enter the first detection lens group;

[0016] After the second diffracted light passes through the second polarization beam splitter prism, it is first transmitted through the third wave plate and reflected by the first reflector in sequence, and then transmitted through the third wave plate again, and after the polarization direction is changed to the first polarization direction, it is reflected by the second polarization beam splitter prism and enters the second detection lens group;

[0017] The positive-order diffracted light in the diffracted light is divided into a third diffracted light having a first polarization direction and a fourth diffracted light having a second polarization direction after passing through the third polarization beam splitter prism; after being reflected by the third polarization beam splitter prism, the third diffracted light is first transmitted through the second wave plate to change the polarization direction to the second polarization direction, and then passes through the second polarization beam splitter prism to enter the second detection lens group;

[0018] After the fourth diffracted light passes through the third polarization beam splitter prism, it is first transmitted through the third wave plate and reflected by the first reflector in sequence, and then transmitted through the third wave plate again, and after the polarization direction is changed to the first polarization direction, it is reflected by the third polarization beam splitter prism and enters the first detection lens group.

[0019] Optionally, in the alignment device, the second wave plate is a half wave plate, and the third wave plate is a quarter wave plate.

[0020] Optionally, in the alignment device, the first diffracted light and the fourth diffracted light entering the first detection lens group constitute a first sub-light field; the second diffracted light and the third diffracted light entering the second detection lens group constitute a second sub-light field; and the light energy of the first sub-light field and the second sub-light field is the same.

[0021] Optionally, in the alignment device, when the diffracted light is arranged in multiple directions, the beam splitting unit includes a second beam splitter group, and the second beam splitter group includes a plurality of fourth polarization beam splitting prisms, a fourth wave plate, a fifth wave plate and a second reflector;

[0022] The plurality of fourth polarization beam splitting prisms are arranged in a ring shape corresponding to the plurality of arrangement directions of the diffracted light and form a fourth polarization beam splitting prism ring. The fourth wave plate is arranged at the center of the fourth polarization beam splitting prism ring. The first surface of the fifth wave plate covers the side opposite to the diffracted light incident on the fourth polarization beam splitting prism ring. The second reflector covers the second surface opposite to the first surface of the fifth wave plate. The side of each of the fourth polarization beam splitting prisms away from the fourth wave plate corresponds to one of the detection mirror groups.

[0023] Wherein, the diffracted light is equally divided into a fifth diffracted light having a first polarization direction and a sixth diffracted light having a second polarization direction by each of the fourth polarization beam splitting prisms; the fifth diffracted light is reflected by the fourth polarization beam splitting prism, transmitted by the fourth wave plate, and the polarization direction is changed to be opposite to the second polarization direction, and then passes through another fourth polarization beam splitting prism in the propagation direction of the sixth diffracted light, and enters the detection lens group corresponding to the other fourth polarization beam splitting prism;

[0024] After the sixth diffracted light passes through the fourth polarization beam splitter prism, it is transmitted through the fifth wave plate and reflected by the second reflector in sequence, and then transmitted through the fifth wave plate again to change the polarization direction to the opposite direction of the first polarization. After being reflected by the fourth polarization beam splitter prism, it enters the detection lens group corresponding to the fourth polarization beam splitter prism.

[0025] Optionally, in the alignment device, the fourth wave plate is a half wave plate, and the fifth wave plate is a quarter wave plate.

[0026] Optionally, in the alignment device, when the diffracted light is arranged in multiple directions, the beam splitting unit includes a third beam splitter group; wherein the third beam splitter group includes a fifth polarization beam splitter prism, a sixth polarization beam splitter prism, a sixth wave plate, a seventh wave plate and a third reflector;

[0027] Part of the diffracted light enters the fifth polarization beam splitter prism, and is split into a seventh diffracted light having a first polarization direction and an eighth diffracted light having a second polarization direction after passing through the fifth polarization beam splitter prism;

[0028] After being reflected by the fifth polarization beam splitter prism, the seventh diffracted light is transmitted through the sixth wave plate, and the polarization direction is changed to the second polarization direction to form the ninth diffracted light. The ninth diffracted light is emitted from the third beam splitter group through the sixth polarization beam splitter prism;

[0029] After passing through the fifth polarization beam splitter prism, the eighth diffracted light is sequentially transmitted through the seventh wave plate and reflected by the third reflector, and then transmitted through the seventh wave plate again to change the polarization direction to the first polarization direction to form the tenth diffracted light. The tenth diffracted light is then reflected by the fifth polarization beam splitter prism out of the third beam splitter group;

[0030] Part of the diffracted light enters the sixth polarization beam splitter prism, and is split into an eleventh diffracted light having a first polarization direction and a twelfth diffracted light having a second polarization direction after passing through the sixth polarization beam splitter prism;

[0031] After being reflected by the sixth polarization beam splitter prism, the eleventh diffracted light is transmitted through the sixth wave plate, and the polarization direction is changed to the second polarization direction to form the thirteenth diffracted light. The thirteenth diffracted light is emitted from the third beam splitter group through the fifth polarization beam splitter prism;

[0032] After passing through the sixth polarization beam splitter prism, the twelfth diffracted light is transmitted through the seventh wave plate and reflected by the third reflector in sequence, and is transmitted through the seventh wave plate again to change the polarization direction to the first polarization direction to form the fourteenth diffracted light. The fourteenth diffracted light is then reflected from the third beam splitter group by the sixth polarization beam splitter prism.

[0033] Optionally, in the alignment device, the sixth wave plate is a half wave plate, and the seventh wave plate is a quarter wave plate.

[0034] Optionally, in the alignment device, the beam splitter unit further includes a fourth beam splitter group; the fourth beam splitter group includes a seventh polarization beam splitter prism, an eighth polarization beam splitter prism, an eighth wave plate, a ninth wave plate and a fourth reflector; the detection unit includes a third detection mirror group, a fifth detector, a sixth detector, a fourth detection mirror group, a seventh detector and an eighth detector; wherein,

[0035] The ninth diffracted light with the second polarization direction overlaps with the fourteenth diffracted light with the first polarization direction and enters the fourth beam splitter group;

[0036] After part of the ninth diffracted light passes through the seventh polarization beam splitter prism, it is sequentially transmitted through the ninth wave plate and reflected by the fourth reflector, and then transmitted through the ninth wave plate again to change the polarization direction to the first polarization direction, and then reflected by the seventh polarization beam splitter prism to enter the third detection mirror group;

[0037] After part of the ninth diffracted light passes through the eighth polarization beam splitter prism, it is sequentially transmitted through the ninth wave plate and reflected by the fourth reflector, and then transmitted through the ninth wave plate again to change the polarization direction to the first polarization direction, and then reflected by the eighth polarization beam splitter prism to enter the fourth detection mirror group;

[0038] After being reflected by the seventh polarization beam splitter prism, part of the fourteenth diffracted light is first transmitted through the eighth wave plate to change the polarization direction to the second polarization direction, and then passes through the eighth polarization beam splitter prism to enter the fourth detection lens group;

[0039] After being reflected by the eighth polarization beam splitter prism, part of the fourteenth diffracted light is first transmitted through the eighth wave plate to change the polarization direction to the second polarization direction, and then passes through the seventh polarization beam splitter prism to enter the third detection lens group;

[0040] The fifth detector obtains the light energy of the first polarized light emitted by the third detection mirror group, the sixth detector obtains the light energy of the second polarized light emitted by the third detection mirror group; the seventh detector obtains the light energy of the first polarized light emitted by the fourth detection mirror group; the eighth detector obtains the light energy of the second polarized light emitted by the fourth detection mirror group.

[0041] Optionally, in the alignment device, the eighth wave plate is a half wave plate, and the ninth wave plate is a quarter wave plate.

[0042] Optionally, in the alignment device, the beam splitter unit further includes a fifth beam splitter group; the fifth beam splitter group includes a ninth polarization beam splitter prism, a tenth polarization beam splitter prism, a tenth wave plate, an eleventh wave plate and a fifth reflector; the detection unit further includes a fifth detection mirror group, a ninth detector, a tenth detector, a sixth detection mirror group, an eleventh detector and a twelfth detector; wherein,

[0043] The tenth diffracted light with the first polarization direction and the thirteenth diffracted light with the second polarization direction overlap and enter the fifth beam splitter group;

[0044] After being reflected by the ninth polarization beam splitter prism, part of the tenth diffracted light is first transmitted through the tenth wave plate to change the polarization direction to the second polarization direction, and then passes through the tenth polarization beam splitter prism to enter the sixth detection lens group;

[0045] After being reflected by the tenth polarization beam splitter prism, part of the tenth diffracted light is first transmitted through the tenth wave plate to change the polarization direction to the second polarization direction, and then passes through the ninth polarization beam splitter prism to enter the fifth detection lens group;

[0046] After part of the thirteenth diffracted light passes through the ninth polarization beam splitter prism, it is sequentially transmitted through the eleventh wave plate and reflected through the fifth reflector, and then transmitted through the eleventh wave plate again to change the polarization direction to the first polarization direction, and then reflected through the ninth polarization beam splitter prism to enter the fifth detection mirror group;

[0047] After part of the thirteenth diffracted light passes through the tenth polarization beam splitter prism, it is sequentially transmitted through the eleventh wave plate and reflected by the fifth reflector, and then transmitted through the eleventh wave plate again to change the polarization direction to the first polarization direction, and then reflected by the tenth polarization beam splitter prism to enter the sixth detection mirror group;

[0048] The ninth detector obtains the light energy of the first polarized light emitted by the fifth detection mirror group, the tenth detector obtains the light energy of the second polarized light emitted by the fifth detection mirror group; the eleventh detector obtains the light energy of the first polarized light emitted by the sixth detection mirror group; the twelfth detector obtains the light energy of the second polarized light emitted by the sixth detection mirror group.

[0049] Optionally, in the alignment device, the tenth wave plate is a half wave plate, and the eleventh wave plate is a quarter wave plate.

[0050] Optionally, in the alignment device, when the diffracted light is arranged in multiple directions, the beam splitter unit includes a sixth beam splitter group; the sixth beam splitter group includes an eleventh polarization beam splitter prism, a twelfth polarization beam splitter prism, a twelfth wave plate, a thirteenth wave plate, a fourteenth wave plate, a fifteenth wave plate, a sixth reflector and a seventh reflector; wherein,

[0051] A part of the diffracted light is divided into a fifteenth diffracted light having a first polarization direction and a sixteenth diffracted light having a second polarization direction by the eleventh polarization beam splitter prism; after the fifteenth diffracted light is reflected by the eleventh polarization beam splitter prism, it is first transmitted through the thirteenth wave plate and reflected by the sixth reflector in sequence, then transmitted through the thirteenth wave plate again, after the polarization direction is changed to the second polarization direction, it is transmitted through the eleventh polarization beam splitter prism, transmitted through the twelfth wave plate, after the polarization direction is changed to the first polarization direction, it is reflected by the twelfth polarization beam splitter prism, then transmitted through the fifteenth wave plate, after the polarization direction is changed to the second polarization direction, it forms a seventeenth diffracted light and is emitted from the sixth beam splitter group;

[0052] After the sixteenth diffracted light passes through the eleventh polarization beam splitter prism, it passes through the fifteenth wave plate, changes its polarization direction to the first polarization direction, forms the eighteenth diffracted light, and emits out of the sixth beam splitter group;

[0053] A part of the diffracted light is divided into a nineteenth diffracted light having a first polarization direction and a twentieth diffracted light having a second polarization direction by the twelfth polarization beam splitter prism; after the nineteenth diffracted light is reflected by the twelfth polarization beam splitter prism, it is first transmitted through the fourteenth wave plate and reflected by the seventh reflector in sequence, then transmitted through the fourteenth wave plate again, after the polarization direction is changed to the second polarization direction, it is transmitted through the twelfth polarization beam splitter prism, transmitted through the twelfth wave plate, after the polarization direction is changed to the first polarization direction, then reflected by the eleventh polarization beam splitter prism, transmitted through the fifteenth wave plate, after the polarization direction is changed to the second polarization direction, a twenty-first diffracted light is formed, and then emitted from the sixth beam splitter group;

[0054] After passing through the twelfth polarization beam splitter prism, the twentieth diffracted light passes through the fifteenth wave plate, changes its polarization direction to the first polarization direction, forms a twenty-second diffracted light, and emits out of the sixth beam splitter group.

[0055] Optionally, in the alignment device, the twelfth wave plate and the fifteenth wave plate are both half wave plates, and the thirteenth wave plate and the fourteenth wave plate are both quarter wave plates.

[0056] Optionally, in the alignment device, the beam splitter unit further includes a seventh beam splitter group; the seventh beam splitter group includes a thirteenth polarization beam splitter prism, a fourteenth polarization beam splitter prism, a sixteenth wave plate, a seventeenth wave plate and an eighth reflector; the detection unit includes a seventh detection mirror group, a thirteenth detector, a fourteenth detector, an eighth detection mirror group, a fifteenth detector and a sixteenth detector; wherein,

[0057] The eighteenth diffracted light and the twenty-second diffracted light having the first polarization direction, and the seventeenth diffracted light and the twenty-first diffracted light having the second polarization direction overlap to form a twenty-third diffracted light, and the twenty-third diffracted light enters the seventh beam splitter group;

[0058] Part of the twenty-third diffracted light enters the thirteenth polarization beam splitter prism; wherein, part of the twenty-third diffracted light having the first polarization direction is reflected by the thirteenth polarization beam splitter prism and enters the seventh detection mirror group; part of the twenty-third diffracted light having the second polarization direction is transmitted through the thirteenth polarization beam splitter prism, sequentially transmitted through the seventeenth wave plate and reflected by the eighth reflector, transmitted through the seventeenth wave plate again, the polarization direction is changed to the first polarization direction, then reflected by the thirteenth polarization beam splitter prism, transmitted through the sixteenth wave plate, the polarization direction is changed to the second polarization direction, then transmitted through the fourteenth polarization beam splitter prism, and enters the eighth detection mirror group;

[0059] Part of the twenty-third diffracted light enters the fourteenth polarization beam splitter prism; wherein, part of the twenty-third diffracted light having the first polarization direction is reflected by the fourteenth polarization beam splitter prism and enters the eighth detection mirror group; part of the twenty-third diffracted light having the second polarization direction passes through the fourteenth polarization beam splitter prism, is sequentially transmitted through the seventeenth wave plate and reflected by the eighth reflector, is transmitted through the seventeenth wave plate again, changes the polarization direction to the first polarization direction, is reflected by the fourteenth polarization beam splitter prism, is transmitted through the sixteenth wave plate, changes the polarization direction to the second polarization direction, and then passes through the thirteenth polarization beam splitter prism to enter the seventh detection mirror group;

[0060] The thirteenth detector obtains the light energy of the first polarized light emitted by the seventh detection mirror group, the fourteenth detector obtains the light energy of the second polarized light emitted by the seventh detection mirror group; the fifteenth detector obtains the light energy of the first polarized light emitted by the eighth detection mirror group; the sixteenth detector obtains the light energy of the second polarized light emitted by the eighth detection mirror group.

[0061] Optionally, in the alignment device, the sixteenth wave plate is a half wave plate; the seventeenth wave plate is a quarter wave plate.

[0062] Optionally, in the alignment device, the first wave plate is a half wave plate.

[0063] Optionally, in the alignment device, the illumination unit includes a light emitter and a ninth reflector; the light emitter is used to provide illumination, and the ninth reflector is used to change the propagation direction of the illumination so that the illumination is vertically irradiated on the grating mark.

[0064] Optionally, in the alignment device, the alignment device also includes an objective lens and an eighteenth wave plate; the objective lens is used to converge and transmit the light and the diffracted light; the eighteenth wave plate is used to change the polarization direction of the diffracted light so that the diffracted light enters the spectroscopic unit as 45-degree linear polarized light.

[0065] Optionally, in the alignment device, the eighteenth wave plate is a half wave plate.

[0066] Based on the same inventive concept, the present invention also provides a lithography machine, which includes the alignment device.

[0067] Based on the same inventive concept, the present invention also provides an alignment method, the alignment method comprising:

[0068] The illumination unit provides illumination, and the illumination is diffracted after passing through a grating mark to generate diffracted light arranged in at least one direction, and the diffracted light enters the light splitting unit;

[0069] The light splitting unit splits the light field of the diffracted light into at least two sub-light fields, each of which includes diffracted light with a first polarization direction and diffracted light with a second polarization direction;

[0070] The diffracted light in each of the sub-light fields corresponds to entering one of the detection mirror groups in the detection unit, and the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change their polarization directions after being transmitted through the first wave plate, so as to interfere in the first polarization direction and the second polarization direction respectively to form interference light; the interference light enters the first polarization beam splitter prism, and is divided into the first polarization light and the second polarization light by the first polarization beam splitter prism; one of the detectors corresponding to the detection mirror group obtains the light energy of the first polarization light, and another of the detectors corresponding to the detection mirror group obtains the light energy of the second polarization light;

[0071] The workpiece stage is moved to drive the grating mark to move. When the grating mark is moved until the light energy acquired by each detector corresponding to each detection lens group reaches a preset value, the position of the grating mark is the alignment position.

[0072] In summary, the present invention provides an alignment device, a photolithography machine and an alignment method. The alignment device includes an illumination unit, a spectrometer unit and a detection unit. The illumination provided by the illumination unit generates diffracted light arranged in at least one direction after passing through a grating mark. The diffracted light enters the spectrometer unit, and the spectrometer unit divides the light field of the diffracted light into at least two sub-light fields. The diffracted light in each sub-light field enters one of the detection mirror groups in the detection unit. The diffracted light with the first polarization direction and the diffracted light with the second polarization direction change their polarization directions after being transmitted through the first wave plate, so as to interfere in the first polarization direction and the second polarization direction respectively, and form interference light. The interference light enters the first polarization beam splitter prism and is divided into the first polarization light and the second polarization light by the first polarization beam splitter prism. One of the detectors corresponding to the detection mirror group obtains the light energy of the first polarization light, and the other detector corresponding to the detection mirror group obtains the light energy of the second polarization light. When the grating mark is moved until the light energy acquired by each detector corresponding to each detection lens group reaches a preset value, the position of the grating mark is the alignment position.

[0073] Therefore, the present invention sets a spectroscopic unit that is compatible with diffracted light arranged in multiple directions, and divides the light field of the diffracted light into at least two sub-light fields, and realizes the interference of the diffracted light in each sub-light field through a detection unit, and then uses multiple detectors for detection, which greatly improves the alignment accuracy, and can achieve position alignment without using a self-reference interference prism, which not only reduces costs but also simplifies operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 is a structural schematic diagram of an alignment device in Embodiment 1 of the present invention;

[0075] Figure 2 is a structural schematic diagram of a light splitting unit in Embodiment 1 of the present invention;

[0076] Figure 3 is a structural schematic diagram of a light splitting unit in Embodiment 2 of the present invention;

[0077] Figure 4 It is a structural schematic diagram of a light splitting unit in the third embodiment of the present invention. DETAILED DESCRIPTION

[0078] The following is a further detailed description of an alignment device, a lithography machine and an alignment method proposed in the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the accompanying drawings is often a part of the actual structure. In particular, the emphasis that each drawing needs to show is different, and sometimes different proportions are used.

[0079] <Example 1>

[0080] In order to solve the above technical problems, this embodiment provides an alignment device, see Figure 1 , including: an illumination unit 10, a spectroscopic unit 20 and a detection unit 30.

[0081] The illumination unit 10 is used to provide illumination. After the illumination passes through a grating mark M, it diffracts and generates diffracted light arranged in at least one direction, and the diffracted light enters the light splitting unit 20. The illumination unit 10 includes a light emitter 101 and a ninth reflector 102. The light emitter 101 is used to provide illumination, and the illumination is linearly polarized light. The ninth reflector 102 is used to change the propagation direction of the illumination so that the illumination is vertically irradiated on the grating mark M.

[0082] Further, the diffracted light includes positive diffracted light and negative diffracted light. The positive diffracted light and the negative diffracted light are arranged according to the diffraction order. In order to clearly indicate the light path, only the positive first-order (+1) and negative first-order (-1) diffracted light are indicated in the diagram of this embodiment, and the positive first-order (+1) diffracted light represents the positive diffracted light; the negative first-order (-1) diffracted light represents the negative diffracted light.

[0083] The light splitting unit 20 includes at least one light splitter group, and the light field is divided into at least two sub-light fields, each of which includes diffracted light with a first polarization direction and diffracted light with a second polarization direction. The first polarization direction and the second polarization direction are perpendicular to each other.

[0084] The detection unit 30 includes at least two detection mirror groups and at least four detectors. The detection mirror group includes a first wave plate 300 and a first polarization beam splitter prism PBS1. Each of the detection mirror groups is configured with two detectors D. Further, the first wave plate 300 is a half wave plate, so that the diffracted light passing through the first wave plate changes the polarization direction to +45 degree polarization and\or -45 degree polarization, so that interference can be achieved in the first polarization direction and in the second polarization direction respectively. And the polarization beam splitter prism has the following characteristics: it reflects light with a first polarization direction, and transmits light with a second polarization direction.

[0085] Wherein, the diffracted light in each of the sub-light fields enters into one of the detection mirror groups, and the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change their polarization directions after being transmitted through the first wave plate 300, so as to interfere in the first polarization direction and the second polarization direction respectively, and form interference light. The interference light enters the first polarization beam splitter prism PBS1, and is divided into the first polarization light and the second polarization light by the first polarization beam splitter prism PBS1. One of the detectors D corresponding to the detection mirror group obtains the light energy of the first polarization light, and another of the detectors D corresponding to the detection mirror group obtains the light energy of the second polarization light. Wherein, the first polarization light has a first polarization direction, and the second polarization light has a second polarization direction.

[0086] When the grating mark M is moved until the light energy acquired by each detector D corresponding to each detection lens assembly reaches a preset value, the position of the grating mark M is the alignment position.

[0087] When the diffracted light is arranged in one direction, such as Figure 1 As shown, the positive diffracted light and the negative diffracted light are arranged along the X direction. Then the beam splitting unit 20 in the alignment device in this embodiment includes a first beam splitter group 201. The first beam splitter group 201 includes a second polarization beam splitter prism PBS2, a third polarization beam splitter prism PBS3, a second wave plate 2011, a third wave plate 2012 and a first reflector 2013. The detection unit 30 includes a first detection mirror group 301, a first detector D1, a second detector D2, a second detection mirror group 302, a third detector D3 and a fourth detector D4.

[0088] Among them, the negative order diffraction light in the diffraction light ( Figure 1 The first diffracted light a is a first diffracted light and the second diffracted light b is a second diffracted light. The first diffracted light a has a first polarization direction, and the second diffracted light b has a second polarization direction. After being reflected by the second polarization splitter prism PBS2, the first diffracted light a is first transmitted through the second wave plate 2011, and the polarization direction is changed to the second polarization direction, and then passes through the third polarization splitter prism PBS3 to enter the first detection lens group 301.

[0089] After the second diffracted light b passes through the second polarization beam splitter prism PBS2, it is first transmitted through the third wave plate 2012 and reflected by the first reflector 2013 in sequence, and then transmitted through the third wave plate 2012 again, and after the polarization direction is changed to the first polarization direction, it is reflected by the second polarization beam splitter prism PBS2 and enters the second detection lens group 302.

[0090] The positive order diffraction light in the diffraction light ( Figure 1 The first-order diffraction light is taken as an example in the figure) and is divided into a third diffraction light c and a fourth diffraction light d after passing through the third polarization beam splitter prism PBS3. The third diffraction light c has a first polarization direction, and the fourth diffraction light d has a second polarization direction. After being reflected by the third polarization beam splitter prism PBS3, the third diffraction light c is transmitted through the second wave plate 2011, and the polarization direction is changed to the second polarization direction, and then the third diffraction light c enters the second polarization beam splitter prism PBS2, and enters the second detection lens group 302 through the second polarization beam splitter prism PBS2.

[0091] After the fourth diffracted light d passes through the third polarization beam splitter prism PBS3, it is transmitted through the third wave plate 2012 and reflected by the first reflector 2013 in sequence, and then transmitted through the third wave plate 2012 again to change the polarization direction to the first polarization direction, and then reflected by the third polarization beam splitter prism PBS3 to enter the first detection lens group 301.

[0092] Furthermore, the second wave plate 2011 is a half wave plate, and the third wave plate 2012 is a quarter wave plate.

[0093] The first diffracted light a and the fourth diffracted light d entering the first detection mirror group 301 constitute a first sub-light field. The second diffracted light b and the third diffracted light c entering the second detection mirror group 302 constitute a second sub-light field, and the first beam splitter group divides the light field of the diffracted light into the first sub-light field and the second sub-light field. The light energy of the first sub-light field and the second sub-light field is the same.

[0094] In addition, the alignment device also includes an objective lens 40 and an eighteenth wave plate 50. The objective lens 40 is used to converge and transmit the illumination and the diffracted light. The eighteenth wave plate 50 is used to change the polarization direction of the diffracted light. Among them, the eighteenth wave plate is a half wave plate. The polarization direction of the diffracted light is changed to a 45-degree polarization direction after passing through the eighteenth wave plate, so that the light energy of the first diffracted light a, the second diffracted light b, the third diffracted light c and the fourth diffracted light d separated by the second polarization beam splitter prism PBS2 and the third polarization beam splitter prism PBS3 in the light splitting unit 20 is the same.

[0095] Furthermore, the first detector D1 acquires the light energy of the first polarized light emitted by the first detection lens group 301 , and the second detector D2 acquires the light energy of the second polarized light emitted by the first detection lens group 301 .

[0096] The relationship between the displacement x of the grating mark M and the light energy I1 acquired by the first detector D1 and the light energy I2 acquired by the second detector D2 is as follows:

[0097]

[0098]

[0099] Wherein, x is the displacement of the grating mark, and t is the period of the grating mark.

[0100] The third detector D3 acquires the light energy of the first polarized light emitted by the second detection lens group 302 , and the fourth detector D4 acquires the light energy of the second polarized light emitted by the second detection lens group 302 .

[0101] The relationship between the displacement x of the grating mark M and the light energy I3 acquired by the third detector D3 and the light energy I4 acquired by the fourth detector D4 is as follows:

[0102]

[0103] Wherein, x is the displacement of the grating mark, and t is the period of the grating mark.

[0104] Specifically, taking the light energy I3 acquired by the third detector D3 and the light energy I4 acquired by the fourth detector D4 as an example, the calculation process is described:

[0105] Among them, the diffraction order light field of the grating mark M is:

[0106]

[0107] And n is the diffraction order, t is the period of the grating mark M, and x is the displacement of the grating mark M. Here we first assume that the amplitude is 1, and the angle between the fast axis of the half wave plate and the first polarization direction is 22.5 degrees. The following takes the coherence of + / -1 diffraction order as an example to calculate the signals detected by the two detectors D3 and D4.

[0108] The negative first-order diffracted light passes through the eighteenth wave plate 50 in sequence and enters the second polarization beam splitter PBS2 to be divided into the first diffracted light a with the first polarization direction and the second diffracted light b with the second polarization direction. The second diffracted light b enters the second detection lens group 302 .

[0109] After the second diffracted light b passes through the second polarization beam splitter prism PBS2, it is first transmitted through the third wave plate 2012 and reflected by the first reflector 2013 in sequence, and then transmitted through the third wave plate 2012 again, and after the polarization direction is changed to the first polarization direction, it is reflected by the second polarization beam splitter prism PBS2 and enters the second detection lens group 302.

[0110] Then the light energy of the negative first-order diffracted light entering the third detector D3 is as follows:

[0111]

[0112]

[0113] The light energy of the negative first-order diffraction light entering the fourth detector D4 is as follows:

[0114]

[0115] The positive first-order diffracted light passes through the eighteenth wave plate 50 in sequence and enters the third polarization beam splitter PBS3 to be divided into the third diffracted light c with the first polarization direction and the fourth diffracted light d with the second polarization direction. The third diffracted light c enters the second detection lens group 302 .

[0116] After being reflected by the third polarization beam splitter prism PBS3, the third diffracted light c is transmitted through the second wave plate 2011, changes its polarization direction to the second polarization direction, enters the second polarization beam splitter prism PBS2, and enters the second detection lens group 302 through the second polarization beam splitter prism PBS2.

[0117] The light energy of the positive first-order diffraction light entering the third detector D3 is as follows:

[0118]

[0119] The light energy of the positive first-order diffraction light entering the fourth detector D4 is as follows:

[0120]

[0121] Where J is the Jones matrix of each optical device, E in is the incident light field (1, 0), the negative first-order diffraction light field E -1 for The positive first-order diffraction light field E +1 for The subscripts 1 and 2 in the formula represent the corresponding light beams of the first polarization direction and the second polarization direction, respectively. The subscripts -1 and +1 represent the negative first-order diffracted light and the positive first-order diffracted light, respectively.

[0122] Furthermore, Figure 1 The close relationship between the second wave plate 2011, the third wave plate 2012, the first reflector 2013, the second polarization beam splitter prism PBS2 and the third polarization beam splitter prism PBS3 is not a necessary condition for this embodiment. The drawing is made in this way to show that the optical paths of the positive and negative order diffracted lights entering the same detection lens group through different optical paths are equal. Optionally, the second polarization beam splitter prism PBS2 and the third polarization beam splitter prism PBS3 can be simultaneously translated along their respective splitting planes by any distance to keep the optical paths of the positive and negative order diffracted lights entering the same detection lens group equal.

[0123] Therefore, when the positive first-order diffraction light and the negative first-order diffraction light change their polarization directions to -45 degree polarization and\or +45 degree polarization after passing through the first wave plate 300, so as to achieve interference in the first polarization direction and the second polarization direction respectively, the light energy I3 obtained by the third detector D3 and the light energy I4 obtained by the fourth detector D4 are:

[0124]

[0125] Wherein, x is the displacement of the grating mark, and t is the period of the grating mark.

[0126] Similarly, referring to the above method, the relationship between the light energy I1 acquired by the first detector D1 and the light energy I2 acquired by the second detector D2 can be obtained as follows:

[0127]

[0128] Wherein, x is the displacement of the grating mark, and t is the period of the grating mark.

[0129] Therefore, the alignment device provided in this embodiment divides the light field of the diffracted light into two sub-light fields, and four detectors (D1, D2, D3 and D4) detect the light energy of the two sub-light fields. Therefore, the light energy obtained by subdividing the light field is more accurate. When the displacement of the grating mark M changes to the point where the light energy obtained by each detector reaches the peak, the position of the grating mark is the desired alignment position.

[0130] because Figure 1 The alignment device shown can only adapt to the diffraction caused by the grating marks M arranged in one direction. Therefore, in order to adapt to multiple directions of grating marks M, please refer to Figure 2 This embodiment further provides a beam splitter unit 20 , which includes a second beam splitter group 202 . The second beam splitter group includes a plurality of fourth polarization beam splitting prisms PBS4 , a fourth wave plate 2021 , a fifth wave plate 2022 and a second reflector 2023 .

[0131] The plurality of fourth polarization beam splitting prisms PBS4 are arranged in a ring shape corresponding to the plurality of arrangement directions of the diffracted light and form a fourth polarization beam splitting prism ring, the fourth wave plate 2021 is arranged at the center of the fourth polarization beam splitting prism ring, the first surface of the fifth wave plate 2022 covers the side opposite to the diffracted light incident on the fourth polarization beam splitting prism ring, and the second reflector 2023 covers the second surface opposite to the first surface of the fifth wave plate 2022. And the side of each of the fourth polarization beam splitting prisms PBS4 away from the fourth wave plate 2021 corresponds to one of the detection mirror groups (not shown), and each of the detection mirror groups is configured with two detectors (not shown).

[0132] The diffracted light path is Figure 1 The diffraction light paths shown are consistent. The diffracted light is evenly divided into a fifth diffracted light having a first polarization direction and a sixth diffracted light having a second polarization direction by each of the fourth polarization beam splitter prisms PBS4. After the fifth diffracted light is reflected by the fourth polarization beam splitter prism PBS4, it is transmitted through the fourth wave plate 2021, the polarization direction is changed to the opposite direction of the second polarization, and then passes through another fourth polarization beam splitter prism PBS4 in the propagation direction of the sixth diffracted light, and enters the detection lens group corresponding to the other fourth polarization beam splitter prism PBS4.

[0133] After the sixth diffracted light passes through the fourth polarization beam splitter prism PBS4, it is transmitted through the fifth wave plate 2022 and reflected by the second reflector 2023 in sequence, and is transmitted through the fifth wave plate 2022 again to change the polarization direction to be opposite to the first polarization direction, and then is reflected by the fourth polarization beam splitter prism PBS4 before entering the detection mirror group corresponding to the fourth polarization beam splitter prism PBS4.

[0134] Therefore, the second beam splitter group 202 can be applicable to diffracted light fields with various arrangement directions, and divide the diffracted light field into a plurality of sub-light fields, the number of which is equal to the number of the fourth polarization beam splitter prisms PBS4. Figure 2 8 fourth polarization beam splitting prisms PBS4 are shown, which divide the diffracted light field into 8 sub-light fields, each sub-light field corresponds to a detection lens group. Then the second beam splitter group 202 further subdivides the diffracted light field, which can not only be compatible with diffracted light arranged in various directions, but also improve the alignment accuracy.

[0135] Furthermore, the fourth wave plate 2021 is a half wave plate, and the fifth wave plate 2022 is a quarter wave plate.

[0136] Based on the same inventive concept, this embodiment also provides a lithography machine, which includes the alignment device.

[0137] Based on the same inventive concept, this embodiment also provides an alignment method, including:

[0138] Step 1: the illumination unit 10 provides illumination, and the illumination is diffracted after passing through a grating mark M and generates diffracted light arranged in at least one direction, and the diffracted light enters the light splitting unit 20 .

[0139] Step 2: The light splitting unit 20 splits the light field of the diffracted light into at least two sub-light fields, each of which includes diffracted light with a first polarization direction and diffracted light with a second polarization direction.

[0140] Step 3: The diffracted light in each of the sub-light fields enters into one of the detection mirror groups (301 or 302) in the detection unit 30. The diffracted light with the first polarization direction and the diffracted light with the second polarization direction change their polarization directions after being transmitted through the first wave plate 300, so as to interfere in the first polarization direction and the second polarization direction respectively, and form interference light. The interference light enters the first polarization beam splitter prism PBS1, and is divided into the first polarization light and the second polarization light by the first polarization beam splitter prism PBS1. One of the detectors (D1 or D3) corresponding to the detection mirror group (301 or 302) obtains the light energy of the first polarization light, and the other detector (D2 or D4) corresponding to the detection mirror group (301 or 302) obtains the light energy of the second polarization light.

[0141] Step 4: Move the workpiece table to drive the grating mark M to move. When the grating mark M is moved until the light energy obtained by each detector corresponding to each detection lens group reaches a preset value, that is, when the light energy obtained by each detector reaches the peak, the position of the grating mark M is the alignment position.

[0142] The displacement of the grating mark M includes displacement in the X direction and displacement in the Y direction.

[0143] <Implementation 2>

[0144] Figure 2 The light splitting unit 20 shown is provided with a plurality of the fourth polarization beam splitting prisms PBS4, and a plurality of the detection lens groups and a plurality of detectors need to be provided correspondingly, so the position adjustment is relatively complicated and the cost is relatively high. Therefore, this embodiment provides an alignment device, which can reduce the cost, avoid the use of a plurality of the fourth polarization beam splitting prisms PBS4, and can also be compatible with the diffracted light arranged in multiple directions.

[0145] This embodiment only describes the light splitting unit. For other components of the alignment device, please refer to the description of the first embodiment, which will not be described in detail here. Figure 3As shown, the light splitting unit includes a third beam splitter group 203, a fourth beam splitter group 204 and a fifth beam splitter group 205. The third beam splitter group 203 includes a fifth polarization beam splitter prism PBS5, a sixth polarization beam splitter prism PBS6, a sixth wave plate 2031, a seventh wave plate 2032 and a third reflector 2033. The fourth beam splitter group 204 includes a seventh polarization beam splitter prism PBS7, an eighth polarization beam splitter prism PBS8, an eighth wave plate 2041, a ninth wave plate 2042 and a fourth reflector 2043; the fifth beam splitter group 205 includes a ninth polarization beam splitter prism PBS9, a tenth polarization beam splitter prism PBS10, a tenth wave plate 2051, an eleventh wave plate 2052 and a fifth reflector 2053. The detection unit (not shown) includes a third detection mirror group, a fifth detector, and a sixth detector corresponding to the fourth spectroscope group 204; a fourth detection mirror group, a seventh detector, and an eighth detector; and a fifth detection mirror group, a ninth detector, and a tenth detector corresponding to the fifth spectroscope group 205; and a sixth detection mirror group, an eleventh detector and a twelfth detector.

[0146] Part of the diffracted light enters the fifth polarization beam splitter prism PBS5, and the remaining part of the diffracted light enters the sixth polarization beam splitter prism PBS6. The specific optical path is as follows:

[0147] Part of the diffracted light enters the fifth polarization beam splitter prism PBS5, and is split into a seventh diffracted light having a first polarization direction and an eighth diffracted light having a second polarization direction after passing through the fifth polarization beam splitter prism PBS5.

[0148] After being reflected by the fifth polarization beam splitter prism PBS5, the seventh diffracted light is transmitted through the sixth wave plate 2031, and the polarization direction is changed to the second polarization direction to form the ninth diffracted light. The ninth diffracted light is emitted from the third beam splitter group 203 through the sixth polarization beam splitter prism PBS6, and enters the fourth beam splitter group 204.

[0149] After the eighth diffracted light passes through the fifth polarization beam splitter prism PBS5, it is transmitted through the seventh wave plate 2032 and reflected by the third reflector 2033 in sequence, and is transmitted through the seventh wave plate 2032 again to change the polarization direction to the first polarization direction to form the tenth diffracted light. The tenth diffracted light is then reflected by the fifth polarization beam splitter prism PBS5 out of the third beam splitter group 203 and enters the fifth beam splitter group 205.

[0150] Part of the diffracted light enters the sixth polarization beam splitter prism PBS6, and is split into an eleventh diffracted light having a first polarization direction and a twelfth diffracted light having a second polarization direction after passing through the sixth polarization beam splitter prism PBS6.

[0151] After being reflected by the sixth polarization beam splitter prism PBS6, the eleventh diffracted light is transmitted through the sixth wave plate 2031, and the polarization direction is changed to the second polarization direction to form the thirteenth diffracted light. The thirteenth diffracted light is emitted from the third beam splitter group through the fifth polarization beam splitter prism PBS5 and enters the fifth beam splitter group 205.

[0152] After the twelfth diffracted light passes through the sixth polarization beam splitter prism PBS6, it is transmitted through the seventh wave plate 2032 and reflected by the third reflector 2033 in sequence, and is transmitted through the seventh wave plate 2032 again to change the polarization direction to the first polarization direction to form the fourteenth diffracted light. The fourteenth diffracted light is then reflected by the sixth polarization beam splitter prism PBS6 out of the third beam splitter group and enters the fourth beam splitter group 204.

[0153] Wherein, the sixth wave plate 2031 is a half wave plate, and the seventh wave plate 2032 is a quarter wave plate.

[0154] The ninth diffracted light with the second polarization direction and the fourteenth diffracted light with the first polarization direction overlap and enter the fourth beam splitter group 204. After part of the ninth diffracted light passes through the seventh polarization beam splitter prism PBS7, it is sequentially transmitted through the ninth wave plate 2042 and reflected by the fourth reflector 2043, and then transmitted through the ninth wave plate 2042 again, the polarization direction is changed to the first polarization direction, and then reflected by the seventh polarization beam splitter prism PBS7, and enters the third detection mirror group.

[0155] After part of the ninth diffracted light passes through the eighth polarization beam splitter prism PBS8, it is transmitted through the ninth wave plate 2042 and reflected by the fourth reflector 2043 in sequence, and then transmitted through the ninth wave plate 2042 again, changing the polarization direction to the first polarization direction, and then reflected by the eighth polarization beam splitter prism PBS8 to enter the fourth detection mirror group.

[0156] After being reflected by the seventh polarization beam splitter prism PBS7, part of the fourteenth diffracted light is first transmitted through the eighth wave plate 2041 to change the polarization direction to the second polarization direction, and then passes through the eighth polarization beam splitter prism PBS8 to enter the fourth detection lens group.

[0157] After being reflected by the eighth polarization beam splitter prism PBS8, part of the fourteenth diffracted light is first transmitted through the eighth wave plate 2041 to change the polarization direction to the second polarization direction, and then passes through the seventh polarization beam splitter prism PBS7 to enter the third detection lens group.

[0158] Furthermore, the eighth wave plate 2041 is a half wave plate, and the ninth wave plate 2042 is a quarter wave plate.

[0159] The fifth detector obtains the light energy of the first polarized light emitted by the third detection mirror group, the sixth detector obtains the light energy of the second polarized light emitted by the third detection mirror group; the seventh detector obtains the light energy of the first polarized light emitted by the fourth detection mirror group; the eighth detector obtains the light energy of the second polarized light emitted by the fourth detection mirror group.

[0160] The tenth diffracted light with the first polarization direction and the thirteenth diffracted light with the second polarization direction overlap and enter the fifth beam splitter group 205. Part of the tenth diffracted light is reflected by the ninth polarization beam splitter prism PBS9, firstly transmitted through the tenth wave plate 2051, and the polarization direction is changed to the second polarization direction, and then passes through the tenth polarization beam splitter prism PBS10 to enter the sixth detection mirror group.

[0161] After being reflected by the tenth polarization beam splitter prism PBS10, part of the tenth diffracted light is first transmitted through the tenth wave plate 2051 to change the polarization direction to the second polarization direction, and then passes through the ninth polarization beam splitter prism PBS9 to enter the fifth detection lens group.

[0162] After part of the thirteenth diffracted light passes through the ninth polarization beam splitter prism PBS9, it is transmitted through the eleventh wave plate 2052 and reflected by the fifth reflector 2053 in sequence, and is transmitted through the eleventh wave plate 2052 again, changing the polarization direction to the first polarization direction, and is reflected by the ninth polarization beam splitter prism PBS9 to enter the fifth detection mirror group.

[0163] After part of the thirteenth diffracted light passes through the tenth polarization beam splitter prism PBS10, it is transmitted through the eleventh wave plate 2052 and reflected by the fifth reflector 2053 in sequence, and is transmitted through the eleventh wave plate 2052 again, changing the polarization direction to the first polarization direction, and is reflected by the tenth polarization beam splitter prism PBS10 to enter the sixth detection mirror group.

[0164] The ninth detector obtains the light energy of the first polarized light emitted by the fifth detection mirror group, the tenth detector obtains the light energy of the second polarized light emitted by the fifth detection mirror group; the eleventh detector obtains the light energy of the first polarized light emitted by the sixth detection mirror group; the twelfth detector obtains the light energy of the second polarized light emitted by the sixth detection mirror group.

[0165] Further, the tenth wave plate 2051 is a half wave plate, and the eleventh wave plate 2052 is a quarter wave plate.

[0166] Therefore, the alignment device provided by the present invention can be compatible with the diffracted light arranged in multiple directions, and the diffracted light field is divided into four sub-light fields by secondary division, so that the diffracted light in the four sub-light fields interferes in the first polarization direction and the second polarization mode respectively, thereby reducing the error and improving the alignment accuracy. Figure 2 The alignment device shown has low cost and is easy to operate.

[0167] <Implementation Three>

[0168] In the second embodiment, three beam splitter groups are used. To further reduce the cost, this embodiment provides an alignment device. This embodiment only describes the beam splitter unit. For other components of the alignment device, please refer to the description of the first embodiment, which will not be described here.

[0169] Figure 4 As shown, the beam splitting unit includes a sixth beam splitter group 206 and a seventh beam splitter group 207. The sixth beam splitter group 206 includes an eleventh polarization beam splitter prism PBS11, a twelfth polarization beam splitter prism PBS12, a twelfth wave plate 2061, a thirteenth wave plate 2062, a fourteenth wave plate 2064, a fifteenth wave plate 2066, a sixth reflector 2063 and a seventh reflector 2065. The seventh beam splitter group 207 includes a thirteenth polarization beam splitter prism PBS13, a fourteenth polarization beam splitter prism PBS14, a sixteenth wave plate 2071, a seventeenth wave plate 2072 and an eighth reflector 2073. Among them, the polarization direction of the diffracted light after being split by the eleventh polarization beam splitter prism PBS11, the twelfth polarization beam splitter prism PBS12, the thirteenth polarization beam splitter prism PBS13 and the fourteenth polarization beam splitter prism PBS14 is mirror-symmetrical with the first embodiment and the second embodiment. The detection unit (not shown) includes a seventh detection mirror group corresponding to the seventh beam splitter group, a thirteenth detector, a fourteenth detector, an eighth detection mirror group, a fifteenth detector and a sixteenth detector.

[0170] The specific optical path is as follows:

[0171] Part of the diffracted light is divided into a fifteenth diffracted light having a first polarization direction and a sixteenth diffracted light having a second polarization direction by the eleventh polarization beam splitter prism PBS11. After being reflected by the eleventh polarization beam splitter prism PBS11, the fifteenth diffracted light is first transmitted through the thirteenth wave plate 2062 and reflected by the sixth reflector 2063 in sequence, then transmitted through the thirteenth wave plate 2602 again, after the polarization direction is changed to the second polarization direction, transmitted through the eleventh polarization beam splitter prism PBS11, transmitted through the twelfth wave plate 2061, after the polarization direction is changed to the first polarization direction, reflected by the twelfth polarization beam splitter prism PBS12, then transmitted through the fifteenth wave plate 2066, after the polarization direction is changed to the second polarization direction, the seventeenth diffracted light is formed, and then emitted from the sixth beam splitter group 206 and enters the seventh beam splitter group 207.

[0172] After passing through the eleventh polarization beam splitter prism PBS11 , the sixteenth diffracted light passes through the fifteenth wave plate 2066 , and changes its polarization direction into the first polarization direction to form the eighteenth diffracted light, which then exits the sixth beam splitter group 206 and enters the seventh beam splitter group 207 .

[0173] Part of the diffracted light is divided into a nineteenth diffracted light having a first polarization direction and a twentieth diffracted light having a second polarization direction by the twelfth polarization beam splitter prism PBS12. After the nineteenth diffracted light is reflected by the twelfth polarization beam splitter prism PBS12, it is first transmitted through the fourteenth wave plate 2064 and reflected by the seventh reflector 2065 in sequence, and then transmitted through the fourteenth wave plate 2064 again to change the polarization direction to the second polarization direction, and then transmitted through the twelfth polarization beam splitter prism PBS12, and then transmitted through the twelfth wave plate 2061 to change the polarization direction to the first polarization direction, and then reflected by the eleventh polarization beam splitter prism PBS11, and then transmitted through the fifteenth wave plate 2066 to change the polarization direction to the second polarization direction, and then forms a twenty-first diffracted light, which is emitted from the sixth beam splitter group 206 and enters the seventh beam splitter group 207.

[0174] After passing through the twelfth polarization beam splitter prism PBS12 , the twentieth diffracted light passes through the fifteenth wave plate 2066 , and changes its polarization direction into the first polarization direction to form a twenty-second diffracted light, which then exits the sixth beam splitter group 206 and enters the seventh beam splitter group 207 .

[0175] Further, the twelfth wave plate 2061 and the fifteenth wave plate 2066 are both half wave plates, and the thirteenth wave plate 2062 and the fourteenth wave plate 2064 are both quarter wave plates.

[0176] The eighteenth diffracted light and the twenty-second diffracted light with the first polarization direction, and the seventeenth diffracted light and the twenty-first diffracted light with the second polarization direction overlap to form a twenty-third diffracted light, and the twenty-third diffracted light enters the seventh beam splitter group 207 .

[0177] Part of the twenty-third diffracted light enters the thirteenth polarization beam splitter prism PBS13, and part of the twenty-third diffracted light with the first polarization direction is reflected by the thirteenth polarization beam splitter prism PBS13 and enters the seventh detection mirror group. Part of the twenty-third diffracted light with the second polarization direction is transmitted through the thirteenth polarization beam splitter prism PBS13, sequentially transmitted through the seventeenth wave plate 2072 and reflected by the eighth reflector 2073, transmitted through the seventeenth wave plate 2072 again, changed the polarization direction to the first polarization direction, reflected through the thirteenth polarization beam splitter prism PBS13, transmitted through the sixteenth wave plate 2071, changed the polarization direction to the second polarization direction, and then transmitted through the fourteenth polarization beam splitter prism PBS14 to enter the eighth detection mirror group.

[0178] The remaining part of the twenty-third diffracted light enters the fourteenth polarization beam splitter prism PBS14. Among them, the part of the twenty-third diffracted light with the first polarization direction is reflected by the fourteenth polarization beam splitter prism PBS14 and enters the eighth detection mirror group. The part of the twenty-third diffracted light with the second polarization direction passes through the fourteenth polarization beam splitter prism PBS14, and then sequentially passes through the seventeenth wave plate 2072 and reflects from the eighth reflector 2073, and then passes through the seventeenth wave plate 2072 again, changes the polarization direction to the first polarization direction, and then reflects from the fourteenth polarization beam splitter prism PBS14, and after passing through the sixteenth wave plate 20721, changes the polarization direction to the second polarization direction, and then passes through the thirteenth polarization beam splitter prism PBS13 and enters the seventh detection mirror group.

[0179] The thirteenth detector obtains the light energy of the first polarized light emitted by the seventh detection mirror group, the fourteenth detector obtains the light energy of the second polarized light emitted by the seventh detection mirror group; the fifteenth detector obtains the light energy of the first polarized light emitted by the eighth detection mirror group; the sixteenth detector obtains the light energy of the second polarized light emitted by the eighth detection mirror group.

[0180] Furthermore, the sixteenth wave plate is a half wave plate; and the seventeenth wave plate is a quarter wave plate.

[0181] Therefore, the alignment device provided in this example divides the diffracted light field into two sub-light fields. Only two beam splitter groups are needed to achieve interference of the diffracted light in the two sub-light fields in the first polarization direction and the second polarization direction, thereby reducing errors and improving alignment accuracy. Figure 3 The alignment device shown has low cost and is easy to operate.

[0182] In summary, each embodiment sets the light splitting unit 20 to achieve compatibility with diffracted light arranged in multiple directions, and divides the light field of the diffracted light into at least two sub-light fields, and uses the detection unit 30 to achieve interference of the diffracted light in each sub-light field in the first polarization direction and the second polarization mode, and then uses multiple detectors for detection, which greatly improves the alignment accuracy and reduces the error. And position alignment can be achieved without using a self-reference interference prism, which not only reduces the cost but also simplifies the operation.

[0183] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. In addition, the different parts between the various embodiments can also be used in combination with each other, and the present invention is not limited to this.

[0184] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. An alignment device, characterized in that: The alignment device comprises: an illumination unit, a light splitting unit and a detection unit; The illumination unit is used to provide illumination; the illumination is diffracted after passing through a grating mark and generates diffracted light arranged in at least one direction, and the diffracted light enters the light splitting unit; The light splitting unit includes at least one light splitting mirror group, which is used to split the light field of the diffracted light into at least two sub-light fields, each of which includes diffracted light with a first polarization direction and diffracted light with a second polarization direction; The detection unit comprises at least two detection mirror groups and at least four detectors, each of the detection mirror groups comprises a first wave plate and a first polarization beam splitter prism, and each of the detection mirror groups is configured with two of the detectors; Wherein, the diffracted light in each of the sub-light fields enters one of the detection mirror groups accordingly, and the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change their polarization directions after being transmitted through the first wave plate, so as to interfere in the first polarization direction and the second polarization direction respectively and form interference light; the interference light enters the first polarization beam splitter prism, and is split into the first polarization light and the second polarization light by the first polarization beam splitter prism; one of the detectors corresponding to the detection mirror group acquires the light energy of the first polarization light, and another of the detectors corresponding to the detection mirror group acquires the light energy of the second polarization light; When the grating mark is moved until the light energy acquired by each detector corresponding to each detection lens group reaches a preset value, the position of the grating mark is the alignment position.

2. The alignment device according to claim 1, characterized in that The first polarization direction and the second polarization direction are perpendicular to each other.

3. The alignment device according to claim 1, characterized in that The first polarized light has a first polarization direction, and the second polarized light has a second polarization direction.

4. The alignment device according to claim 1, characterized in that When the diffracted light is arranged in one direction, the beam splitter unit includes a first beam splitter group, which includes a second polarization beam splitter prism, a third polarization beam splitter prism, a second wave plate, a third wave plate and a first reflector; the detection unit includes a first detection mirror group, a first detector, a second detector, a second detection mirror group, a third detector and a fourth detector; wherein, The negative-order diffracted light in the diffracted light is divided into a first diffracted light having a first polarization direction and a second diffracted light having a second polarization direction after passing through the second polarization beam splitter prism; after the first diffracted light is reflected by the second polarization beam splitter prism, it is first transmitted through the second wave plate to change the polarization direction to the second polarization direction, and then passes through the third polarization beam splitter prism to enter the first detection lens group; After the second diffracted light passes through the second polarization beam splitter prism, it is first transmitted through the third wave plate and reflected by the first reflector in sequence, and then transmitted through the third wave plate again, and after the polarization direction is changed to the first polarization direction, it is reflected by the second polarization beam splitter prism and enters the second detection lens group; The positive-order diffracted light in the diffracted light is divided into a third diffracted light having a first polarization direction and a fourth diffracted light having a second polarization direction after passing through the third polarization beam splitter prism; after being reflected by the third polarization beam splitter prism, the third diffracted light is first transmitted through the second wave plate to change the polarization direction to the second polarization direction, and then passes through the second polarization beam splitter prism to enter the second detection lens group; After the fourth diffracted light passes through the third polarization beam splitter prism, it is first transmitted through the third wave plate and reflected by the first reflector in sequence, and then transmitted through the third wave plate again, and after the polarization direction is changed to the first polarization direction, it is reflected by the third polarization beam splitter prism and enters the first detection lens group.

5. The alignment device according to claim 4, characterized in that The second wave plate is a half wave plate, and the third wave plate is a quarter wave plate.

6. The alignment device according to claim 4, characterized in that The first diffracted light and the fourth diffracted light entering the first detection mirror group constitute a first sub-light field; the second diffracted light and the third diffracted light entering the second detection mirror group constitute a second sub-light field; the light energy of the first sub-light field and the second sub-light field is the same.

7. The alignment device according to claim 1, characterized in that When the diffracted light is arranged in multiple directions, the light splitting unit includes a second light splitter group, and the second light splitter group includes a plurality of fourth polarization light splitting prisms, a fourth wave plate, a fifth wave plate and a second reflector; The plurality of fourth polarization beam splitting prisms are arranged in a ring shape corresponding to the plurality of arrangement directions of the diffracted light and form a fourth polarization beam splitting prism ring. The fourth wave plate is arranged at the center of the fourth polarization beam splitting prism ring. The first surface of the fifth wave plate covers the side opposite to the diffracted light incident on the fourth polarization beam splitting prism ring. The second reflector covers the second surface opposite to the first surface of the fifth wave plate. The side of each of the fourth polarization beam splitting prisms away from the fourth wave plate corresponds to one of the detection mirror groups. Wherein, the diffracted light is equally divided into a fifth diffracted light having a first polarization direction and a sixth diffracted light having a second polarization direction by each of the fourth polarization beam splitting prisms; the fifth diffracted light is reflected by the fourth polarization beam splitting prism, transmitted by the fourth wave plate, and the polarization direction is changed to be opposite to the second polarization direction, and then passes through another fourth polarization beam splitting prism in the propagation direction of the sixth diffracted light, and enters the detection lens group corresponding to the other fourth polarization beam splitting prism; After the sixth diffracted light passes through the fourth polarization beam splitter prism, it is transmitted through the fifth wave plate and reflected by the second reflector in sequence, and then transmitted through the fifth wave plate again to change the polarization direction to the opposite direction of the first polarization. After being reflected by the fourth polarization beam splitter prism, it enters the detection lens group corresponding to the fourth polarization beam splitter prism.

8. The alignment device according to claim 7, characterized in that The fourth wave plate is a half wave plate, and the fifth wave plate is a quarter wave plate.

9. The alignment device according to claim 1, characterized in that When the diffracted light is arranged in multiple directions, the light splitting unit includes a third beam splitter group; wherein the third beam splitter group includes a fifth polarization beam splitter prism, a sixth polarization beam splitter prism, a sixth wave plate, a seventh wave plate and a third reflector; Part of the diffracted light enters the fifth polarization beam splitter prism, and is split into a seventh diffracted light having a first polarization direction and an eighth diffracted light having a second polarization direction after passing through the fifth polarization beam splitter prism; After being reflected by the fifth polarization beam splitter prism, the seventh diffracted light is transmitted through the sixth wave plate, and the polarization direction is changed to the second polarization direction to form the ninth diffracted light. The ninth diffracted light is emitted from the third beam splitter group through the sixth polarization beam splitter prism; After passing through the fifth polarization beam splitter prism, the eighth diffracted light is sequentially transmitted through the seventh wave plate and reflected by the third reflector, and then transmitted through the seventh wave plate again to change the polarization direction to the first polarization direction to form the tenth diffracted light. The tenth diffracted light is then reflected by the fifth polarization beam splitter prism out of the third beam splitter group; Part of the diffracted light enters the sixth polarization beam splitter prism, and is split into an eleventh diffracted light having a first polarization direction and a twelfth diffracted light having a second polarization direction after passing through the sixth polarization beam splitter prism; After being reflected by the sixth polarization beam splitter prism, the eleventh diffracted light is transmitted through the sixth wave plate, and the polarization direction is changed to the second polarization direction to form the thirteenth diffracted light. The thirteenth diffracted light is emitted from the third beam splitter group through the fifth polarization beam splitter prism; After passing through the sixth polarization beam splitter prism, the twelfth diffracted light is transmitted through the seventh wave plate and reflected by the third reflector in sequence, and is transmitted through the seventh wave plate again to change the polarization direction to the first polarization direction to form the fourteenth diffracted light. The fourteenth diffracted light is then reflected from the third beam splitter group by the sixth polarization beam splitter prism.

10. The alignment device according to claim 9, characterized in that The sixth wave plate is a half wave plate, and the seventh wave plate is a quarter wave plate.

11. The alignment device according to claim 9, characterized in that The light splitting unit also includes a fourth beam splitter group; the fourth beam splitter group includes a seventh polarization beam splitter prism, an eighth polarization beam splitter prism, an eighth wave plate, a ninth wave plate and a fourth reflector; the detection unit includes a third detection mirror group, a fifth detector, a sixth detector, a fourth detection mirror group, a seventh detector and an eighth detector; wherein, The ninth diffracted light with the second polarization direction overlaps with the fourteenth diffracted light with the first polarization direction and enters the fourth beam splitter group; After part of the ninth diffracted light passes through the seventh polarization beam splitter prism, it is sequentially transmitted through the ninth wave plate and reflected by the fourth reflector, and then transmitted through the ninth wave plate again to change the polarization direction to the first polarization direction, and then reflected by the seventh polarization beam splitter prism to enter the third detection mirror group; After part of the ninth diffracted light passes through the eighth polarization beam splitter prism, it is sequentially transmitted through the ninth wave plate and reflected by the fourth reflector, and then transmitted through the ninth wave plate again to change the polarization direction to the first polarization direction, and then reflected by the eighth polarization beam splitter prism to enter the fourth detection mirror group; After being reflected by the seventh polarization beam splitter prism, part of the fourteenth diffracted light is first transmitted through the eighth wave plate to change the polarization direction to the second polarization direction, and then passes through the eighth polarization beam splitter prism to enter the fourth detection lens group; After being reflected by the eighth polarization beam splitter prism, part of the fourteenth diffracted light is first transmitted through the eighth wave plate to change the polarization direction to the second polarization direction, and then passes through the seventh polarization beam splitter prism to enter the third detection lens group; The fifth detector obtains the light energy of the first polarized light emitted by the third detection mirror group, the sixth detector obtains the light energy of the second polarized light emitted by the third detection mirror group; the seventh detector obtains the light energy of the first polarized light emitted by the fourth detection mirror group; the eighth detector obtains the light energy of the second polarized light emitted by the fourth detection mirror group.

12. The alignment device according to claim 11, characterized in that The eighth wave plate is a half wave plate, and the ninth wave plate is a quarter wave plate.

13. The alignment device according to claim 9, characterized in that The light splitting unit further includes a fifth beam splitter group; the fifth beam splitter group includes a ninth polarization beam splitter prism, a tenth polarization beam splitter prism, a tenth wave plate, an eleventh wave plate and a fifth reflector; the detection unit further includes a fifth detection mirror group, a ninth detector, a tenth detector, a sixth detection mirror group, an eleventh detector and a twelfth detector; wherein, The tenth diffracted light with the first polarization direction and the thirteenth diffracted light with the second polarization direction overlap and enter the fifth beam splitter group; After being reflected by the ninth polarization beam splitter prism, part of the tenth diffracted light is first transmitted through the tenth wave plate to change the polarization direction to the second polarization direction, and then passes through the tenth polarization beam splitter prism to enter the sixth detection lens group; After being reflected by the tenth polarization beam splitter prism, part of the tenth diffracted light is first transmitted through the tenth wave plate to change the polarization direction to the second polarization direction, and then passes through the ninth polarization beam splitter prism to enter the fifth detection lens group; After part of the thirteenth diffracted light passes through the ninth polarization beam splitter prism, it is sequentially transmitted through the eleventh wave plate and reflected through the fifth reflector, and then transmitted through the eleventh wave plate again to change the polarization direction to the first polarization direction, and then reflected through the ninth polarization beam splitter prism to enter the fifth detection mirror group; After part of the thirteenth diffracted light passes through the tenth polarization beam splitter prism, it is sequentially transmitted through the eleventh wave plate and reflected by the fifth reflector, and then transmitted through the eleventh wave plate again to change the polarization direction to the first polarization direction, and then reflected by the tenth polarization beam splitter prism to enter the sixth detection mirror group; The ninth detector obtains the light energy of the first polarized light emitted by the fifth detection mirror group, the tenth detector obtains the light energy of the second polarized light emitted by the fifth detection mirror group; the eleventh detector obtains the light energy of the first polarized light emitted by the sixth detection mirror group; the twelfth detector obtains the light energy of the second polarized light emitted by the sixth detection mirror group.

14. The alignment device according to claim 13, characterized in that The tenth wave plate is a half wave plate, and the eleventh wave plate is a quarter wave plate.

15. The alignment device according to claim 1, characterized in that When the diffracted light is arranged in multiple directions, the beam splitter unit includes a sixth beam splitter group; the sixth beam splitter group includes an eleventh polarization beam splitter prism, a twelfth polarization beam splitter prism, a twelfth wave plate, a thirteenth wave plate, a fourteenth wave plate, a fifteenth wave plate, a sixth reflector and a seventh reflector; wherein, A part of the diffracted light is divided into a fifteenth diffracted light having a first polarization direction and a sixteenth diffracted light having a second polarization direction by the eleventh polarization beam splitter prism; after the fifteenth diffracted light is reflected by the eleventh polarization beam splitter prism, it is first transmitted through the thirteenth wave plate and reflected by the sixth reflector in sequence, then transmitted through the thirteenth wave plate again, after the polarization direction is changed to the second polarization direction, it is transmitted through the eleventh polarization beam splitter prism, transmitted through the twelfth wave plate, after the polarization direction is changed to the first polarization direction, it is reflected by the twelfth polarization beam splitter prism, then transmitted through the fifteenth wave plate, after the polarization direction is changed to the second polarization direction, it forms a seventeenth diffracted light and is emitted from the sixth beam splitter group; After the sixteenth diffracted light passes through the eleventh polarization beam splitter prism, it passes through the fifteenth wave plate, changes its polarization direction to the first polarization direction, forms the eighteenth diffracted light, and emits out of the sixth beam splitter group; A part of the diffracted light is divided into a nineteenth diffracted light having a first polarization direction and a twentieth diffracted light having a second polarization direction by the twelfth polarization beam splitter prism; after the nineteenth diffracted light is reflected by the twelfth polarization beam splitter prism, it is first transmitted through the fourteenth wave plate and reflected by the seventh reflector in sequence, then transmitted through the fourteenth wave plate again, after the polarization direction is changed to the second polarization direction, it is transmitted through the twelfth polarization beam splitter prism, transmitted through the twelfth wave plate, after the polarization direction is changed to the first polarization direction, then reflected by the eleventh polarization beam splitter prism, transmitted through the fifteenth wave plate, after the polarization direction is changed to the second polarization direction, a twenty-first diffracted light is formed, and then emitted from the sixth beam splitter group; After passing through the twelfth polarization beam splitter prism, the twentieth diffracted light passes through the fifteenth wave plate, changes its polarization direction to the first polarization direction, forms a twenty-second diffracted light, and emits out of the sixth beam splitter group.

16. The alignment device according to claim 15, characterized in that The twelfth wave plate and the fifteenth wave plate are both half wave plates, and the thirteenth wave plate and the fourteenth wave plate are both quarter wave plates.

17. The alignment device according to claim 15, characterized in that The light splitting unit further includes a seventh beam splitter group; the seventh beam splitter group includes a thirteenth polarization beam splitter prism, a fourteenth polarization beam splitter prism, a sixteenth wave plate, a seventeenth wave plate and an eighth reflector; the detection unit includes a seventh detection mirror group, a thirteenth detector, a fourteenth detector, an eighth detection mirror group, a fifteenth detector and a sixteenth detector; wherein, The eighteenth diffracted light and the twenty-second diffracted light having the first polarization direction, and the seventeenth diffracted light and the twenty-first diffracted light having the second polarization direction overlap to form a twenty-third diffracted light, and the twenty-third diffracted light enters the seventh beam splitter group; Part of the twenty-third diffracted light enters the thirteenth polarization beam splitter prism; wherein, part of the twenty-third diffracted light having the first polarization direction is reflected by the thirteenth polarization beam splitter prism and enters the seventh detection mirror group; part of the twenty-third diffracted light having the second polarization direction is transmitted through the thirteenth polarization beam splitter prism, sequentially transmitted through the seventeenth wave plate and reflected by the eighth reflector, transmitted through the seventeenth wave plate again, the polarization direction is changed to the first polarization direction, then reflected by the thirteenth polarization beam splitter prism, transmitted through the sixteenth wave plate, the polarization direction is changed to the second polarization direction, then transmitted through the fourteenth polarization beam splitter prism, and enters the eighth detection mirror group; Part of the twenty-third diffracted light enters the fourteenth polarization beam splitter prism; wherein, part of the twenty-third diffracted light having the first polarization direction is reflected by the fourteenth polarization beam splitter prism and enters the eighth detection mirror group; part of the twenty-third diffracted light having the second polarization direction passes through the fourteenth polarization beam splitter prism, is sequentially transmitted through the seventeenth wave plate and reflected by the eighth reflector, is transmitted through the seventeenth wave plate again, changes the polarization direction to the first polarization direction, is reflected by the fourteenth polarization beam splitter prism, is transmitted through the sixteenth wave plate, changes the polarization direction to the second polarization direction, and then passes through the thirteenth polarization beam splitter prism to enter the seventh detection mirror group; The thirteenth detector obtains the light energy of the first polarized light emitted by the seventh detection mirror group, the fourteenth detector obtains the light energy of the second polarized light emitted by the seventh detection mirror group; the fifteenth detector obtains the light energy of the first polarized light emitted by the eighth detection mirror group; the sixteenth detector obtains the light energy of the second polarized light emitted by the eighth detection mirror group.

18. The alignment device according to claim 17, characterized in that The sixteenth wave plate is a half wave plate; the seventeenth wave plate is a quarter wave plate.

19. The alignment device according to claim 1, characterized in that The first wave plate is a half wave plate.

20. The alignment device according to claim 1, characterized in that The illumination unit comprises a light emitter and a ninth reflector; the light emitter is used to provide illumination, and the ninth reflector is used to change the propagation direction of the illumination so that the illumination is vertically irradiated on the grating mark.

21. The alignment device according to claim 1, characterized in that The alignment device also includes an objective lens and an eighteenth wave plate; the objective lens is used to converge and transmit the illumination and the diffracted light; the eighteenth wave plate is used to change the polarization direction of the diffracted light so that the diffracted light enters the spectroscopic unit as 45-degree linear polarized light.

22. The alignment device according to claim 21, characterized in that The eighteenth wave plate is a half wave plate.

23. A photolithography machine, characterized in that: The lithography machine comprises an alignment device as described in any one of claims 1-22.

24. An alignment method, characterized in that: Using the lithography machine as claimed in claim 23, the alignment method comprises: The illumination unit provides illumination, and the illumination is diffracted after passing through a grating mark to generate diffracted light arranged in at least one direction, and the diffracted light enters the light splitting unit; The light splitting unit splits the light field of the diffracted light into at least two sub-light fields, each of which includes diffracted light with a first polarization direction and diffracted light with a second polarization direction; The diffracted light in each of the sub-light fields corresponds to entering one of the detection mirror groups in the detection unit, and the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change their polarization directions after being transmitted through the first wave plate, so as to interfere in the first polarization direction and the second polarization direction respectively and form interference light; the interference light enters the first polarization beam splitter prism, and is divided into the first polarization light and the second polarization light by the first polarization beam splitter prism; one of the detectors corresponding to the detection mirror group obtains the light energy of the first polarization light, and another of the detectors corresponding to the detection mirror group obtains the light energy of the second polarization light; The workpiece stage is moved to drive the grating mark to move. When the grating mark is moved until the light energy acquired by each detector corresponding to each detection lens group reaches a preset value, the position of the grating mark is the alignment position.

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