CN114690595A

CN114690595A - Alignment device, photoetching machine and alignment method

Info

Publication number: CN114690595A
Application number: CN202011625887.5A
Authority: CN
Inventors: 邢奕飞; 高安; 孙建超
Original assignee: Shanghai Micro Electronics Equipment Co Ltd
Current assignee: Shanghai Micro Electronics Equipment Co Ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2022-07-01

Abstract

The invention provides an alignment device, a photoetching machine and an alignment method. The illumination provided by the illumination unit generates diffracted light after being marked by a grating. The splitting unit splits the light field of the diffracted light into at least two sub-light fields. The diffracted light in each sub-light field correspondingly enters a detection mirror group and generates interference to form interference light. The interference light is divided into first polarized light and second polarized light through the first polarization beam splitter prism. The two detectors acquire light energy of the first polarized light and the second polarized light respectively. And 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 an alignment position. Therefore, the invention uses the light splitting unit to split at least two sub-light fields, realizes the interference of diffracted light in each sub-light field through the detection unit, and then uses a plurality of detectors to detect, thereby greatly improving the alignment precision, realizing the position alignment without using a self-reference interference prism, reducing the cost and having simple operation.

Description

Alignment device, photoetching machine and alignment method

Technical Field

The present invention relates to the field of integrated circuit manufacturing technologies, and in particular, to an alignment apparatus, a lithography machine, and an alignment method.

Background

In the field of integrated circuit manufacturing, a lithography machine is capable of applying a reticle pattern onto a photosensitive film layer, such as a photoresist, of a silicon wafer (also referred to as a substrate) to produce a desired circuit structure. In order to accurately control the position of each lithography corresponding to the silicon wafer, it is necessary to set a lithography alignment mark (usually a grating mark) on the silicon wafer, and determine the position of the corresponding lithography alignment mark on the silicon wafer by setting a corresponding alignment device or devices, thereby determining the alignment position of the silicon wafer.

Currently, a commonly used alignment apparatus uses a self-reference interference prism to realize interference of diffracted light, so as to determine the position of a grating mark on a silicon wafer. But alignment devices based on self-referencing interference prisms have some drawbacks that are difficult to avoid. For example, the self-reference interference prism adopts a prism component which needs to be subjected to special optical design and manufacture, and has high processing index, high assembly and adjustment difficulty and higher required cost; also, self-referencing interference prisms are typically bulky, which can have negative effects such as low bandwidth vibration modes, which can ultimately affect alignment accuracy.

Therefore, a new alignment apparatus and alignment method are needed to avoid the disadvantages caused by using the self-reference interference prism, so as to reduce the alignment measurement cost and improve the alignment accuracy.

Disclosure of Invention

The invention aims to provide an alignment device, a photoetching machine and an alignment method, which are used for solving at least one problem of high alignment measurement cost and low alignment precision.

In order to solve the above technical problem, the present invention provides an alignment apparatus, including: the device comprises an illumination unit, a light splitting unit and a detection unit;

the illumination unit is used for providing 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 comprises at least one light splitting mirror group and is used for splitting the light field of the diffracted light into at least two sub light fields, and each sub light field comprises the diffracted light with the first polarization direction and the diffracted light with the second polarization direction;

the detection unit comprises at least two detection mirror groups and at least four detectors, each detection mirror group comprises a first wave plate and a first polarization splitting prism, and each detection mirror group is provided with two detectors;

when the diffracted light in each sub-light field correspondingly enters one detection mirror group, the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change the polarization directions after being transmitted by the first wave plate, so that interference occurs in the first polarization direction and the second polarization direction respectively, and interference light is formed; the interference light enters the first polarization beam splitter prism and is divided into first polarized light and second polarized light by the first polarization beam splitter prism; one detector corresponding to the detection mirror group acquires light energy of first polarized light, and the other detector corresponding to the detection mirror group acquires light energy of second polarized light;

and when the grating mark is moved until the light energy acquired by each detector corresponding to each detection mirror group reaches a preset value, the position of the grating mark is an alignment position.

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

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

Optionally, in the alignment apparatus, when the diffracted lights are arranged in one direction, the splitting unit includes a first splitting mirror group, and the first splitting mirror group includes a second polarization splitting prism, a third polarization splitting prism, a second wave plate, a third wave plate, and a first reflector; the detection unit comprises a first detection mirror group, a first detector, a second detection mirror group, a third detector and a fourth detector; wherein the content of the first and second substances,

the negative order diffraction light in the diffraction light is divided into first diffraction light with a first polarization direction and second diffraction light with a second polarization direction after passing through the second polarization light splitting prism; the first diffracted light is reflected by the second polarization beam splitter prism, then is transmitted by the second wave plate, changes the polarization direction into a second polarization direction, and then enters the first detection mirror group through the third polarization beam splitter prism;

after the second diffracted light penetrates through the second polarization beam splitter prism, the second diffracted light is transmitted through the third wave plate and reflected by the first reflector in sequence, is transmitted through the third wave plate again, changes the polarization direction into the first polarization direction, and then is reflected through the second polarization beam splitter prism to enter the second detection mirror group;

the positive order diffraction light in the diffraction light is divided into third diffraction light with a first polarization direction and fourth diffraction light with a second polarization direction after passing through the third polarization light splitting prism; after being reflected by a third polarization beam splitter prism, the third diffraction light is transmitted by the second wave plate, changes the polarization direction into a second polarization direction, and then enters the second detection mirror group through the second polarization beam splitter prism;

and after the fourth diffracted light passes through a third polarization beam splitter prism, the fourth diffracted light is transmitted by the third wave plate and reflected by the first reflector in sequence, is transmitted by the third wave plate again, changes the polarization direction into the first polarization direction, and then is reflected by the third polarization beam splitter prism to enter the first detection mirror group.

Optionally, in the alignment apparatus, the second wave plate is a half wave plate, and the third wave plate is a quarter wave plate.

Optionally, in the alignment apparatus, the first diffracted light and the fourth diffracted light entering the first detecting mirror group constitute a first sub-optical field; the second diffracted light and the third diffracted light entering the second detection mirror group form a second sub-optical field; the optical energy of the first sub-optical field and the second sub-optical field is the same.

Optionally, in the alignment apparatus, when the diffracted light is arranged in multiple directions, the splitting unit includes a second splitting mirror group, and the second splitting mirror group includes a plurality of fourth polarization splitting prisms, a fourth wave plate, a fifth wave plate, and a second mirror;

the fourth polarization splitting prisms are arranged in a ring shape corresponding to a plurality of arrangement directions of the diffracted light and form a fourth polarization splitting prism ring, the fourth wave plate is arranged at the position of the center of the fourth polarization splitting prism ring, the first surface of the fifth wave plate covers the surface, opposite to the fourth polarization splitting prism ring, of the diffracted light, and the second reflector covers the second surface, opposite to the first surface of the fifth wave plate; one side of each fourth polarization beam splitter prism, which is far away from the fourth wave plate, corresponds to one detection mirror group;

and the diffracted light is equally divided into fifth diffracted light with the first polarization direction and sixth diffracted light with the second polarization direction by each fourth polarization splitting prism. After the fifth diffraction light is reflected by the fourth polarization beam splitter prism, the fifth diffraction light is transmitted by the fourth wave plate, the polarization direction is changed into a second polarization direction, and the second diffraction light passes through another fourth polarization beam splitter prism in the transmission direction of the sixth diffraction light and enters the detection mirror group corresponding to the other fourth polarization beam splitter prism;

and the sixth diffracted light is transmitted by the fifth wave plate and reflected by the second reflector in sequence after penetrating through the fourth polarization beam splitter prism, is transmitted by the fifth wave plate again, changes the polarization direction into the first polarization direction, is reflected by the fourth polarization beam splitter prism, and then enters the detection mirror group corresponding to the fourth polarization beam splitter prism.

Optionally, in the alignment apparatus, the fourth wave plate is a half wave plate, and the fifth wave plate is a quarter wave plate.

Optionally, in the alignment apparatus, when the diffracted light is arranged in a plurality of directions, the light splitting unit includes a third light splitting lens group; the third beam splitter group comprises a fifth 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 divided into seventh diffracted light with a first polarization direction and eighth diffracted light with a second polarization direction after passing through the fifth polarization beam splitter prism;

the seventh diffracted light is reflected by the fifth polarization beam splitter prism, transmitted by the sixth wave plate, and changed in polarization direction into a second polarization direction, so that ninth diffracted light is formed, and the ninth diffracted light is emitted out of the third beam splitter group through the sixth polarization beam splitter prism;

the eighth diffracted light is transmitted by the seventh wave plate, reflected by the third reflector and transmitted by the seventh wave plate again, the polarization direction of the eighth diffracted light is changed into the first polarization direction, and the tenth diffracted light is reflected out of the third beam splitter group by the fifth polarization beam splitter prism;

part of the diffracted light enters the sixth polarization beam splitter prism, and is divided into eleventh diffracted light with a first polarization direction and twelfth diffracted light with a second polarization direction after passing through the sixth polarization beam splitter prism;

the eleventh diffraction light is reflected by the sixth polarization beam splitter prism, is transmitted by the sixth wave plate, changes the polarization direction to the second polarization direction, and forms thirteenth diffraction light, and the thirteenth diffraction light penetrates through the fifth polarization beam splitter prism and exits the third beam splitter group;

and the twelfth diffraction light passes through the sixth polarization beam splitter prism, is transmitted by the seventh wave plate, is reflected by the third reflector, is transmitted by the seventh wave plate again, changes the polarization direction into the first polarization direction, forms fourteenth diffraction light, and is reflected out of the third beam splitter group by the sixth polarization beam splitter prism.

Optionally, in the alignment apparatus, the sixth wave plate is a half wave plate, and the seventh wave plate is a quarter wave plate.

Optionally, in the alignment apparatus, the light splitting unit further includes a fourth light splitting mirror group; the fourth light splitting lens group comprises a seventh polarization light splitting prism, an eighth wave plate, a ninth wave plate and a fourth reflector; the detection unit comprises 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 content of the first and second substances,

the ninth diffraction light with the second polarization direction and the fourteenth diffraction light with the first polarization direction are superposed and enter the fourth beam splitter group;

after part of the ninth diffracted light penetrates through the seventh polarization beam splitter prism, the ninth diffracted light is transmitted by the ninth wave plate, reflected by the fourth reflector, transmitted by the ninth wave plate again, changed into the first polarization direction, reflected by the seventh polarization beam splitter prism and enters the third detection mirror group;

after part of the ninth diffracted light penetrates through the eighth polarization beam splitter prism, the ninth diffracted light is transmitted by the ninth wave plate, reflected by the fourth reflector, transmitted by the ninth wave plate again, changed in polarization direction into the first polarization direction, reflected by the eighth polarization beam splitter prism, and enters the fourth detection mirror group;

after part of the fourteenth diffraction light is reflected by the seventh polarization beam splitter prism, the fourteenth diffraction light is transmitted by the eighth wave plate, changes the polarization direction into a second polarization direction, and then enters the fourth detection mirror group through the eighth polarization beam splitter prism;

part of the fourteenth diffraction light is reflected by the eighth polarization beam splitter prism, then is transmitted by the eighth wave plate, changes the polarization direction into a second polarization direction, and then passes through the seventh polarization beam splitter prism to enter the third detection mirror group;

the fifth detector obtains the light energy of the first polarized light emitted by the third set of detector mirrors, and the sixth detector obtains the light energy of the second polarized light emitted by the third set of detector mirrors; the seventh detector acquires light energy of the first polarized light emitted by the fourth detecting mirror group; the eighth detector acquires light energy of the second polarized light emitted by the fourth set of detector mirrors.

Optionally, in the alignment apparatus, the eighth wave plate is a half wave plate, and the ninth wave plate is a quarter wave plate.

Optionally, in the alignment apparatus, the light splitting unit further includes a fifth light splitting lens group; the fifth beam splitter group comprises a ninth polarization beam splitter prism, a tenth wave plate, an eleventh wave plate and a fifth reflector; the detection unit further includes: the optical fiber laser comprises a fifth detection lens group, a ninth detector, a tenth detector, a sixth detection lens group, an eleventh detector and a twelfth detector; wherein, the first and the second end of the pipe are connected with each other,

the tenth diffraction light with the first polarization direction and the thirteenth diffraction light with the second polarization direction are superposed and enter the fifth beam splitter group;

after part of the tenth diffraction light is reflected by the ninth polarization beam splitter prism, the tenth diffraction light is transmitted by the tenth wave plate, the polarization direction is changed into a second polarization direction, and then the tenth diffraction light penetrates through the tenth polarization beam splitter prism and enters the sixth detection mirror group;

part of the tenth diffraction light is reflected by the tenth polarization beam splitter prism, then is transmitted by the tenth wave plate, changes the polarization direction into a second polarization direction, and then passes through the ninth polarization beam splitter prism to enter the fifth detection mirror group;

after part of the thirteenth diffracted light penetrates through the ninth polarization beam splitter prism, the thirteenth diffracted light is transmitted by the eleventh wave plate, reflected by the fifth reflector, transmitted by the eleventh wave plate again, changed in polarization direction into the first polarization direction, reflected by the ninth polarization beam splitter prism, and enters the fifth detection mirror group;

after part of the thirteenth diffracted light penetrates through the tenth polarization beam splitter prism, the thirteenth diffracted light is transmitted by the eleventh wave plate, reflected by the fifth reflector, transmitted by the eleventh wave plate again, changed in polarization direction into the first polarization direction, reflected by the tenth polarization beam splitter prism, and enters the sixth detection mirror group;

said ninth detector acquiring light energy of said first polarized light emitted by said fifth set of detectors and said tenth detector acquiring light energy of said second polarized light emitted by said fifth set of detectors; the eleventh detector acquires the light energy of the first polarized light emitted by the sixth detecting mirror group; the twelfth detector acquires light energy of the second polarized light emitted by the sixth set of detector mirrors.

Optionally, in the alignment apparatus, the tenth wave plate is a half wave plate, and the eleventh wave plate is a quarter wave plate.

Optionally, in the alignment apparatus, when the diffracted light is arranged in a plurality of directions, the light splitting unit includes a sixth light splitting lens group; the sixth beam splitting mirror group comprises an eleventh polarization beam splitting prism, a twelfth wave plate, a thirteenth wave plate, a fourteenth wave plate, a fifteenth wave plate, a sixth reflecting mirror and a seventh reflecting mirror; wherein the content of the first and second substances,

part of the diffracted light is divided into fifteenth diffracted light with a first polarization direction and sixteenth diffracted light with a second polarization direction through the eleventh polarization splitting prism; the fifteenth diffraction light is reflected by the eleventh polarization splitting prism, then sequentially transmitted by the thirteenth wave plate and reflected by the sixth reflector, then transmitted by the thirteenth wave plate again, changed in polarization direction into the second polarization direction, then transmitted through the eleventh polarization splitting prism, transmitted by the twelfth wave plate, changed in polarization direction into the first polarization direction, then reflected by the twelfth polarization splitting prism, then transmitted through the fifteenth wave plate, changed in polarization direction into the second polarization direction, to form seventeenth diffraction light, and then emitted out of the sixth splitting mirror group;

after the sixteenth diffraction light penetrates through the eleventh polarization beam splitter prism and passes through the fifteenth wave plate, the polarization direction is changed into the first polarization direction, and eighteenth diffraction light is formed and emitted out of the sixth beam splitter group;

part of the diffracted light is divided into nineteenth diffracted light with the first polarization direction and twentieth diffracted light with the second polarization direction through the twelfth polarization splitting prism; the nineteenth diffraction light is reflected by the twelfth polarization splitting prism, then sequentially transmitted by the fourteenth wave plate and reflected by the seventh reflector, then transmitted by the fourteenth wave plate again, changed in polarization direction into a second polarization direction, transmitted through the twelfth polarization splitting prism, transmitted by the twelfth wave plate, changed in polarization direction into a first polarization direction, reflected by the eleventh polarization splitting prism, transmitted through the fifteenth wave plate, changed in polarization direction into a second polarization direction, so as to form twenty-first diffraction light, and then emitted out of the sixth splitting mirror group;

and the twentieth diffracted light passes through the twelfth polarization beam splitter prism, passes through the fifteenth wave plate, changes the polarization direction into the first polarization direction, forms twenty-second diffracted light, and emits out of the sixth beam splitter group.

Optionally, in the alignment apparatus, 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.

Optionally, in the alignment apparatus, the light splitting unit further includes a seventh light splitting mirror group; the seventh spectroscope group comprises a thirteenth polarizing spectroscope, a fourteenth polarizing spectroscope, a sixteenth wave plate, a seventeenth wave plate and an eighth reflector; the detection unit comprises 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 content of the first and second substances,

the eighteenth diffraction light with the first polarization direction and the twenty-second diffraction light, and the seventeenth diffraction light with the second polarization direction and the twenty-first diffraction light are superposed to form twenty-third diffraction light, and the twenty-third diffraction light enters the seventh spectroscope group;

part of the twenty-third diffracted light enters the thirteenth polarization splitting prism; part of the twenty-three diffracted lights with the first polarization direction are reflected by the thirteenth polarizing beam splitter and enter a seventh detection mirror group; part of the twenty-third diffracted light with the second polarization direction penetrates through the thirteenth polarization beam splitter, is transmitted through the seventeenth wave plate and reflected by the eighth reflector in sequence, is transmitted through the seventeenth wave plate again, changes the polarization direction into the first polarization direction, is reflected by the thirteenth polarization beam splitter prism, is transmitted through the sixteenth wave plate, changes the polarization direction into the second polarization direction, penetrates 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 splitting prism; part of the twenty-three diffracted lights with the first polarization direction are reflected by the fourteenth polarizing beam splitter and enter an eighth detection mirror group; part of the twenty-third diffracted light with the second polarization direction penetrates through the fourteenth polarization beam splitter, then is transmitted by the seventeenth wave plate and reflected by the eighth reflector in sequence, is transmitted by the seventeenth wave plate again, changes the polarization direction into the first polarization direction, then is reflected by the fourteenth polarization beam splitter prism, is transmitted by the sixteenth wave plate, changes the polarization direction into the second polarization direction, and then penetrates through the thirteenth polarization beam splitter prism to enter the seventh detection mirror group;

said thirteenth detector capturing light energy of said first polarized light emitted by said seventh set of detector mirrors and said fourteenth detector capturing light energy of said second polarized light emitted by said seventh set of detector mirrors; the fifteenth detector acquires light energy of the first polarized light emitted by the eighth set of detectors; the sixteenth detector acquires light energy of the second polarized light emitted by the eighth detector mirror group.

Optionally, in the alignment apparatus, the sixteenth wave plate is a half wave plate; the seventeenth wave plate is a quarter wave plate.

Optionally, in the alignment apparatus, the first wave plate is a half wave plate.

Optionally, in the alignment device, the illumination unit includes a light emitter and a ninth mirror; the light emitter is used for providing illumination, and the ninth reflector is used for changing the propagation direction of the illumination so that the illumination vertically irradiates on the grating marks.

Optionally, in the alignment device, the alignment device further includes an objective lens and an eighteenth wave plate; the objective lens is used for converging and transmitting the illumination and the diffracted light; the eighteenth wave plate is used for changing the polarization direction of the diffracted light so that the diffracted light enters the light splitting unit in a 45-degree linearly polarized light mode.

Optionally, in the alignment apparatus, the eighteenth wave plate is a half wave plate.

Based on the same inventive concept, the invention also provides a photoetching machine, which comprises the alignment device.

Based on the same inventive concept, the invention also provides an alignment method, which comprises the following steps:

the illumination unit provides illumination, the illumination is diffracted after being marked by a grating and generates diffracted light arranged in at least one direction, and the diffracted light enters the light splitting unit;

the splitting unit splits the light field of the diffracted light into at least two sub-light fields, each of the sub-light fields including therein the diffracted light having a first polarization direction and the diffracted light having a second polarization direction;

the diffracted light in each sub-light field correspondingly enters 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 the polarization directions after being transmitted by the first wave plate so as to respectively interfere in the first polarization direction and the second polarization direction to form interference light; the interference light enters the first polarization beam splitter prism and is divided into first polarized light and second polarized light by the first polarization beam splitter prism; one detector corresponding to the detection mirror group acquires light energy of first polarized light, and the other detector corresponding to the detection mirror group acquires light energy of second polarized light;

and moving the workpiece table to drive the grating marks to move, wherein when the grating marks are moved until the light energy obtained by each detector corresponding to each detection mirror group reaches a preset value, the positions of the grating marks are alignment positions.

In summary, the present invention provides an alignment apparatus, a lithography machine and an alignment method. Wherein, the aligning device comprises an illumination unit, a light splitting unit and a detection unit. The illumination provided by the illumination unit is marked by a grating to generate diffracted light arranged in at least one direction. The diffracted light enters the light splitting unit, which splits 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 detecting mirror groups in the detecting unit. The diffraction light with the first polarization direction and the diffraction light with the second polarization direction change the polarization direction after being transmitted by the first wave plate, so that interference occurs in the first polarization direction and the second polarization direction respectively, and interference light is formed. The interference light enters the first polarization beam splitter prism and is divided into first polarized light and second polarized light through the first polarization beam splitter prism. One of the detectors corresponding to the set of detection mirrors obtains light energy of a first polarized light, and the other of the detectors corresponding to the set of detection mirrors obtains light energy of a second polarized light. And when the grating mark is moved until the light energy acquired by each detector corresponding to each detection mirror group reaches a preset value, the position of the grating mark is an alignment position.

Therefore, the light splitting unit is arranged, so that the light splitting unit can be compatible with the diffracted light distributed in multiple directions, the light field of the diffracted light is divided into at least two sub-light fields, the interference of the diffracted light in each sub-light field is realized through the detection unit, the detectors are used for detection, the alignment precision is greatly improved, the position alignment can be realized without using a self-reference interference prism, the cost is reduced, and the operation is simple.

Drawings

FIG. 1 is a schematic structural diagram of an alignment apparatus according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a light splitting unit according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a light splitting unit according to a second embodiment of the present invention;

fig. 4 is a schematic structural diagram of a light splitting unit in a third embodiment of the present invention.

Detailed Description

An alignment apparatus, a lithography machine and an alignment method according to the present invention will be described in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.

< example one >

To solve the above technical problem, the present embodiment provides an alignment apparatus, referring to fig. 1, including: an illumination unit 10, a light splitting unit 20 and a detection unit 30.

The illumination unit 10 is used to provide illumination. After passing through a grating mark M, the illumination is diffracted to generate diffracted light arranged in at least one direction, and the diffracted light enters the light splitting unit 20. Wherein the illumination unit 10 comprises a light emitter 101 and a ninth mirror 102. The light emitter 101 is used for providing illumination, and the illumination is linearly polarized light. The ninth reflector 102 is used for changing the propagation direction of the illumination so that the illumination is vertically irradiated on the grating mark M.

Further, the diffracted light includes positive order diffracted light and negative order diffracted light. The positive order diffraction light and the negative order diffraction light are arranged according to diffraction orders. For the sake of clarity of the optical path, only the plus (+1) and minus (-1) diffracted lights are indicated in the illustration of the present embodiment, and the plus (+1) diffracted light represents the plus diffracted light; the minus first (-1) order diffracted light represents the minus diffracted light.

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

The detection unit 30 comprises at least two detection mirror groups and at least four detectors. The detection mirror group comprises a first wave plate 300 and a first polarization splitting prism PBS 1. Each detection mirror group is provided with two detectors D. Further, the first wave plate 300 is a half wave plate, so that the polarization direction of the diffracted light passing through the first wave plate is changed to +45 degree polarization and/or-45 degree polarization, thereby enabling interference to occur in the first polarization direction and the second polarization direction, respectively. And the polarization beam splitter prism has the following characteristics: the light having the first polarization direction is reflected, and the light having the second polarization direction is transmitted.

When the diffracted light in each sub-optical field correspondingly enters one of the detecting mirror groups, the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change the polarization directions after being transmitted by the first wave plate 300, so as to respectively interfere in the first polarization direction and the second polarization direction, and form interference light. The interference light enters the first polarization beam splitter PBS1, and is split into first polarized light and second polarized light by the first polarization beam splitter PBS 1. One detector D corresponding to the detection mirror group acquires light energy of first polarized light, and the other detector D corresponding to the detection mirror group acquires light energy of second polarized light. Wherein the first polarized light has a first polarization direction and the second polarized light has a second polarization direction.

And when the grating mark M is moved until the light energy obtained by each detector D corresponding to each detection mirror group reaches a preset value, the position of the grating mark M is an alignment position.

When the diffracted lights are arranged in one direction, as shown in fig. 1, the positive order diffracted light and the negative order diffracted light are arranged in the X direction. The light splitting unit 20 in the aligning apparatus in this embodiment includes a first light splitting mirror group 201. The first beam splitter set 201 includes a second polarization beam splitter PBS2, a third polarization beam splitter PBS3, a second wave plate 2011, a third wave plate 2012 and a first reflecting mirror 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 D2 and a fourth detector D4.

The negative order diffracted light (the negative order diffracted light is taken as an example in fig. 1) in the diffracted lights is divided into a first diffracted light a and a second diffracted light b after passing through the second polarization splitting prism PBS 2. 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 beam splitter PBS2, the first diffracted light a is transmitted through the second wave plate 2011, changes the polarization direction to the second polarization direction, and then enters the first detection mirror group 301 through the third polarization beam splitter PBS 3.

After the second diffracted light b passes through the second polarization beam splitter PBS2, the second diffracted light b is sequentially transmitted through the third wave plate 2012, reflected by the first reflecting mirror 2013, and transmitted through the third wave plate 2012 again, changes the polarization direction to the first polarization direction, and then is reflected by the second polarization beam splitter PBS2 to enter the second detection mirror group 302.

The positive order diffracted light (the positive order diffracted light is taken as an example in fig. 1) of the diffracted lights is divided into a third diffracted light c and a fourth diffracted light d by the third polarization beam splitter prism PBS 3. The third diffracted light c has a first polarization direction, and the fourth diffracted light d has a second polarization direction. After being reflected by the third polarization beam splitter PBS3, the third diffracted light c is transmitted by the second wave plate 2011, changes the polarization direction into a second polarization direction, enters the second polarization beam splitter PBS2, and enters the second detection mirror group 302 through the second polarization beam splitter PBS 2.

After passing through the third polarization beam splitter PBS3, the fourth diffracted light d is sequentially transmitted by the third wave plate 2012, reflected by the first reflecting mirror 2013, transmitted by the third wave plate 2012 again, changed in polarization direction to the first polarization direction, and reflected by the third polarization beam splitter PBS3 to enter the first detection mirror group 301.

Further, the second wave plate 2011 is a half wave plate, and the third wave plate 2012 is a quarter wave plate.

Wherein, the first diffracted light a and the fourth diffracted light d entering the first detecting mirror group 301 constitute a first sub-optical field. The second diffracted light b and the third diffracted light c entering the second detecting mirror group 302 constitute a second sub-light field, and the first beam splitting mirror group divides the light field of the diffracted light into the first sub-light field and the second sub-light field. The optical energy of the first sub-optical field and the second sub-optical field is the same.

In addition, the alignment apparatus further includes an objective lens 40 and an eighteenth wave plate 50. The objective lens 40 is used for converging and transmitting the illumination and the diffracted light. The eighteenth wave plate 50 is for changing the polarization direction of the diffracted light. Wherein the eighteenth wave plate is a half wave plate. The polarization direction of the diffracted light is changed to 45 degrees 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, which are separated by the second polarization beam splitter PBS2 and the third polarization beam splitter PBS3 in the beam splitting unit 20, are the same.

Further, first detector D1 obtains light energy of the first polarization emitted by first detecting mirror group 301, and second detector D2 obtains light energy of the second polarization emitted by first detecting mirror group 301.

Wherein the displacement x of the grating mark M is respectively equal to the light energy I obtained by the first detector D1₁And the light energy I acquired by the second detector D2₂The relationship between them is as follows:

wherein x is the displacement of the grating mark, and t is the period of the grating mark.

The third detector D3 acquires light energy of the first polarization emitted by the second set of detector mirrors 302 and the fourth detector D4 acquires light energy of the second polarization emitted by the second set of detector mirrors 302.

Wherein the displacement x of the grating mark M is respectively equal to the light energy I obtained by the third detector D3₃And the light energy I acquired by the fourth detector D4₄The relationship between them is as follows:

In particular, the light energy I acquired with the third detector D3₃And the light energy I captured by the fourth detector D4₄For example, a calculation process is illustrated:

wherein, the diffraction order light field of the grating mark M is:

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, wherein the amplitude is assumed to be 1, and the included angle between the fast axis of the half-wave plate and the first polarization direction is 22.5 degrees. The signals detected by two of the detectors D3 and D4 are calculated below using the coherence of +/-1 diffraction order as an example.

The negative first-order diffracted light sequentially passes through the eighteenth wave plate 50, enters the second polarization beam splitter prism PBS2, and is divided into a first diffracted light a with a first polarization direction and a second diffracted light b with a second polarization direction. Wherein, the second diffracted light b enters the second detecting mirror group 302.

The light energy of the first order negative diffracted light entering the third detector D3 is as follows:

the light energy of the first order negative diffracted light entering the fourth detector D4 is as follows:

the positive first-order diffracted light sequentially passes through the eighteenth wave plate 50, enters the third polarization beam splitter prism PBS3, and is divided into a third diffracted light c with a first polarization direction and a fourth diffracted light d with a second polarization direction. Wherein the third diffracted light c enters the second detecting mirror group 302.

After being reflected by the third polarization beam splitter PBS3, the third diffracted light c is transmitted through the second wave plate 2011, changes the polarization direction into the second polarization direction, enters the second polarization beam splitter PBS2, and enters the second detecting lens group 302 through the second polarization beam splitter PBS 2.

The light energy of the first order diffracted light entering the third detector D3 is as follows:

the light energy of the first order diffracted light entering the fourth detector D4 is as follows:

wherein J is Jones matrix of each optical device, E_inFor the incident light field (1, 0), the negative first order diffracted light field E_-1Is composed of

Positive first order diffracted light field E₊₁Is composed of

The subscripts in the formula are 1 and 2, which respectively represent the light and the second polarization direction corresponding to the first polarization direction of the light beam. The subscripts-1 and +1 denote negative and positive first order diffracted light, respectively.

Furthermore, the relationship that the second wave plate 2011, the third wave plate 2012, the first reflecting mirror 2013, the second polarization beam splitter PBS2 and the third polarization beam splitter PBS3 are tightly attached to each other in fig. 1 is not a necessary condition of the present embodiment, and the drawing is for showing that the optical paths of the positive and negative order diffracted lights entering the same detection mirror group through different optical paths are equal. Optionally, the second polarization beam splitter PBS2 and the third polarization beam splitter PBS3 may respectively translate along the splitting planes thereof at the same time by any distance, so that the optical paths of the positive and negative order diffracted lights entering the same detection mirror group are equal.

Therefore, when the positive first-order diffraction light and the negative first-order diffraction light pass through the first wave plate 300 and then change the polarization direction to-45-degree polarization and/or + 45-degree polarization so as to realize interference in the first polarization direction and the second polarization direction respectively, the light energy I obtained by the third detector D3₃And the light energy I acquired by the fourth detector D4₄Comprises the following steps:

Also, with reference to the above method, the light energy I acquired by the first detector D1 may be obtained₁And the light energy I acquired by the second detector D2₂The relationship between them is as follows:

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 light energies of the two sub-light fields. The light energy obtained by subdividing the light field is more accurate. When the displacement of the grating mark M is changed until the light energy obtained by each detector reaches a peak, the position of the grating mark is the required alignment position.

The diffraction due to the grating marks M arranged in one direction can only be accommodated by the alignment arrangement shown in fig. 1. Therefore, please refer to fig. 2 to accommodate various grating marks M directions. The present embodiment further provides a light splitting unit 20, which includes a second light splitting lens group 202. The second beam splitter group includes a plurality of fourth polarization beam splitters PBS4, a fourth wave plate 2021, a fifth wave plate 2022, and a second reflecting mirror 2023.

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

The diffracted light path coincides with the diffracted light path shown in FIG. 1. The diffracted light is equally divided into fifth diffracted light having the first polarization direction and sixth diffracted light having the second polarization direction by each of the fourth polarization beam splitters PBS 4. The fifth diffracted light is reflected by the fourth polarization beam splitter PBS4, transmitted by the fourth wave plate 2021, changed in polarization direction to a second polarization direction, and then passes through another fourth polarization beam splitter PBS4 in the propagation direction of the sixth diffracted light to enter the detection mirror group corresponding to the another fourth polarization beam splitter PBS 4.

After the sixth diffracted light passes through the fourth polarization beam splitter PBS4, the sixth diffracted light is sequentially transmitted by the fifth wave plate 2022, reflected by the second reflecting mirror 2023, transmitted by the fifth wave plate 2022 again, changed in polarization direction to the first polarization direction, reflected by the fourth polarization beam splitter PBS4, and then enters the detection mirror group corresponding to the fourth polarization beam splitter PBS 4.

Therefore, the second beam splitter group 202 can be applied to the diffracted light field with various arrangement directions, and divides the diffracted light field into a number of sub light fields, the number of the sub light fields is equal to the number of the fourth polarization beam splitter PBS4, 8 fourth polarization beam splitter PBS4 is shown in fig. 2, and the diffracted light field is divided into 8 sub light fields, each of which corresponds to one detection mirror group. The second spectroscope group 202 further subdivides the diffracted light field, which not only can be compatible with the diffracted light arranged in multiple directions, but also can improve the alignment accuracy.

Further, the fourth wave plate 2021 is a half wave plate, and the fifth wave plate 2022 is a quarter wave plate.

Based on the same inventive concept, the embodiment further provides a lithography machine, and the lithography machine comprises the alignment device.

Based on the same inventive concept, the present embodiment further provides an alignment method, including:

the method comprises the following steps: the illumination unit 10 provides illumination, which 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.

Step two: the splitting unit 20 splits the light field of the diffracted light into at least two sub-light fields, each of which includes within it a diffracted light having a first polarization direction and a diffracted light having a second polarization direction.

Step three: the diffracted light in each sub-light field correspondingly enters one of the detecting mirror groups (301 or 302) in the detecting unit 30, and the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change the polarization directions after being transmitted through the first wave plate 300, so as to respectively interfere in the first polarization direction and the second polarization direction, and form interference light. The interference light enters the first polarization beam splitter PBS1, and is split into first polarized light and second polarized light by the first polarization beam splitter PBS 1. One of the detectors (D1 or D3) corresponding to the set of detecting mirrors (301 or 302) acquires light energy of a first polarization and the other detector (D2 or D4) corresponding to the set of detecting mirrors (301 or 302) acquires light energy of a second polarization.

Step four: and moving the workpiece table to drive the grating mark M to move, wherein when the grating mark M is moved until the light energy obtained by each detector corresponding to each detection mirror group reaches a preset value, namely the light energy obtained by each detector reaches a peak, the position of the grating mark M is an alignment position.

Wherein, the displacement of the grating mark M comprises displacement in X direction and displacement in Y direction.

< EXAMPLE two >

In the light splitting unit 20 shown in fig. 2, a plurality of fourth polarization beam splitters PBS4 are provided, and a plurality of detection mirror groups and a plurality of detectors need to be correspondingly provided, so that the position adjustment is complex and the cost is high. Therefore, the present embodiment provides an alignment apparatus, which can reduce the cost, avoid using a plurality of fourth polarization beam splitters PBS4, and is also compatible with the diffracted light arranged in a plurality of directions.

In this embodiment, only the light splitting unit is described, and for other components of the alignment apparatus, reference is made to the description of implementation one, which is not described herein again. As shown in fig. 3, the light splitting unit includes a third light splitting mirror group 203, a fourth light splitting mirror group 204, and a fifth light splitting mirror group 205. The third beam splitter group 203 includes a fifth polarization beam splitter PBS5, a sixth polarization beam splitter PBS6, a sixth wave plate 2031, a seventh wave plate 2032, and a third reflector 2033. The fourth light splitting mirror group 204 comprises a seventh polarization beam splitter PBS7, an eighth polarization beam splitter 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 PBS9, a tenth polarization beam splitter PBS10, a tenth wave plate 2051, an eleventh wave plate 2052, and a fifth reflecting mirror 2053. The detection unit (not shown) comprises 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; a fifth detection lens group, a ninth detector and a tenth detector corresponding to the fifth spectroscope group 205; a sixth detection mirror group, an eleventh detector and a twelfth detector.

Part of the diffracted light enters the fifth polarization beam splitter PBS5, and the rest of the diffracted light enters the sixth polarization beam splitter PBS6, and the specific optical path is as follows:

part of the diffracted light enters the fifth polarization beam splitter PBS5, and is split into seventh diffracted light having the first polarization direction and eighth diffracted light having the second polarization direction after passing through the fifth polarization beam splitter PBS 5.

The seventh diffracted light is reflected by the fifth polarization beam splitter PBS5, and then is transmitted by the sixth wave plate 2031, and the polarization direction is changed to the second polarization direction, so as to form ninth diffracted light, and the ninth diffracted light passes through the sixth polarization beam splitter PBS6, exits the third beam splitter group 203, and enters the fourth beam splitter group 204.

After the eighth diffracted light passes through the fifth polarization beam splitter PBS5, the eighth diffracted light is sequentially transmitted by the seventh wave plate 2032, reflected by the third reflector 2033, and transmitted by the seventh wave plate 2032 again, the polarization direction is changed to the first polarization direction, so as to form tenth diffracted light, and the tenth diffracted light is reflected by the fifth polarization beam splitter PBS5 out of the third beam splitter group 203 and enters the fifth beam splitter group 205.

Part of the diffracted light enters the sixth polarization beam splitter PBS6, and is split into eleventh diffracted light having the first polarization direction and twelfth diffracted light having the second polarization direction after passing through the sixth polarization beam splitter PBS 6.

The eleventh diffracted light is reflected by the sixth polarization beam splitter PBS6, and then transmitted by the sixth wave plate 2031, and the polarization direction is changed to the second polarization direction, so as to form thirteenth diffracted light, and the thirteenth diffracted light passes through the fifth polarization beam splitter PBS5, exits the third beam splitter group, and enters the fifth beam splitter group 205.

After the twelfth diffraction light passes through the sixth polarization beam splitter PBS6, the twelfth diffraction light is sequentially transmitted by the seventh wave plate 2032, reflected by the third reflector 2033, and transmitted by the seventh wave plate 2032 again, the polarization direction is changed to the first polarization direction, so as to form fourteenth diffraction light, and the fourteenth diffraction light is reflected out of the third lens group by the sixth polarization beam splitter PBS6 and enters the fourth lens group 204.

The sixth wave plate 2031 is a half wave plate, and the seventh wave plate 2032 is a quarter wave plate.

The ninth diffracted light with the second polarization direction and the fourteenth diffracted light with the first polarization direction are overlapped and enter the fourth light splitting mirror group 204. Then, a part of the ninth diffracted light passes through the seventh polarization beam splitter PBS7, is sequentially transmitted through the ninth wave plate 2042 and reflected by the fourth reflector 2043, is transmitted through the ninth wave plate 2042 again, changes the polarization direction to the first polarization direction, is reflected by the seventh polarization beam splitter PBS7, and enters the third detecting mirror group.

After a part of the ninth diffracted light passes through the eighth polarization splitting prism PBS8, the ninth diffracted light is sequentially transmitted through the ninth wave plate 2042 and reflected by the fourth reflector 2043, and is transmitted through the ninth wave plate 2042 again, changes the polarization direction into the first polarization direction, and is reflected by the eighth polarization splitting prism PBS8 to enter the fourth detection mirror group.

After being reflected by the seventh polarization beam splitter PBS7, part of the fourteenth diffraction light is transmitted by the eighth wave plate 2041, changes the polarization direction to the second polarization direction, and then passes through the eighth polarization beam splitter PBS8 to enter the fourth detection mirror group.

After being reflected by the eighth polarization beam splitter PBS8, part of the fourteenth diffraction light is transmitted by the eighth wave plate 2041, changes the polarization direction to the second polarization direction, and then passes through the seventh polarization beam splitter PBS7 to enter the third detection mirror group.

Further, the eighth wave plate 2041 is a half wave plate, and the ninth wave plate 2042 is a quarter wave plate.

The tenth diffracted light with the first polarization direction and the thirteenth diffracted light with the second polarization direction coincide and enter the fifth dichroic mirror group 205. After being reflected by the ninth polarization beam splitter PBS9, part of the tenth diffracted light is transmitted through the tenth wave plate 2051, changes the polarization direction to the second polarization direction, and then passes through the tenth polarization beam splitter PBS10 to enter the sixth detection mirror group.

After being reflected by the tenth polarization beam splitter PBS10, a part of the tenth diffracted light is transmitted through the tenth wave plate 2051, changes the polarization direction to the second polarization direction, and then passes through the ninth polarization beam splitter PBS9 to enter the fifth detection mirror group.

After part of the thirteenth diffracted light passes through the ninth polarization beam splitter PBS9, it is sequentially transmitted through the eleventh wave plate 2052 and reflected by the fifth reflector 2053, 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 PBS9 to enter the fifth detecting mirror group.

After a part of the thirteenth diffracted light passes through the tenth polarization beam splitter PBS10, the thirteenth diffracted light is sequentially transmitted by the eleventh wave plate 2052, reflected by the fifth reflecting mirror 2053, transmitted by the eleventh wave plate 2052 again, changed in polarization direction into the first polarization direction, reflected by the tenth polarization beam splitter PBS10, and enters the sixth detection mirror group.

Said ninth detector acquiring light energy of said first polarized light emitted by said fifth set of detectors and said tenth detector acquiring light energy of said second polarized light emitted by said fifth set of detectors; the eleventh detector acquires light energy of the first polarized light emitted by the sixth detector mirror group; the twelfth detector acquires light energy of the second polarized light emitted by the sixth set of detector mirrors.

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

Therefore, the alignment device provided by the invention can be compatible with the diffracted light arranged in a plurality of directions, and the diffracted light field is divided into four sub-light fields twice, so that the diffracted light in the four sub-light fields interferes in the first polarization direction and the second polarization mode respectively, the error is reduced, the alignment precision is improved, and compared with the alignment device shown in fig. 2, the alignment device is low in cost and convenient to operate.

< EXAMPLE III >

In the second embodiment, three beam splitting lens sets are used, and in order to further reduce the cost, the present embodiment provides an alignment apparatus. In this embodiment, only the light splitting unit is described, and for other components of the alignment apparatus, reference is made to the description of implementation one, which is not described herein again.

As shown in fig. 4, the light splitting unit includes a sixth light splitting group 206 and a seventh light splitting group 207. The sixth beam splitter group 206 includes an eleventh polarization beam splitter PBS11, a twelfth polarization beam splitter PBS12, a twelfth wave plate 2061, a thirteenth wave plate 2062, a fourteenth wave plate 2064, a fifteenth wave plate 2066, a sixth reflecting mirror 2063, and a seventh reflecting mirror 2065. The seventh beam splitter group 207 includes a thirteenth polarization beam splitter PBS13, a fourteenth polarization beam splitter PBS14, a sixteenth wave plate 2071, a seventeenth wave plate 2072 and an eighth reflecting mirror 2073. The polarization direction of the diffracted light after being split by the eleventh polarizing beam splitter PBS11, the twelfth polarizing beam splitter PBS12, the thirteenth polarizing beam splitter PBS13 and the fourteenth polarizing beam splitter PBS14 is mirror-symmetrical to that of the first embodiment and the second embodiment. The detection unit (not shown) comprises a seventh detection lens group, a thirteenth detector and a fourteenth detector which correspond to the seventh spectroscope group, and an eighth detection lens group, a fifteenth detector and a sixteenth detector.

The specific optical path is as follows:

part of the diffracted light is split into fifteenth diffracted light having the first polarization direction and sixteenth diffracted light having the second polarization direction by the eleventh polarization splitting prism PBS 11. The fifteenth diffracted light is reflected by the eleventh PBS11, then sequentially transmitted by the thirteenth wave plate 2062, reflected by the sixth reflector 2063, transmitted by the thirteenth wave plate 2602 again, changed in polarization direction to the second polarization direction, transmitted by the eleventh PBS11, transmitted by the twelfth wave plate 2061, changed in polarization direction to the first polarization direction, reflected by the twelfth PBS12, transmitted by the fifteenth wave plate 2066, changed in polarization direction to the second polarization direction, to form seventeenth diffracted light, which exits the sixth mirror group 206 and enters the seventh mirror group 207.

The sixteenth diffracted light passes through the eleventh polarization beam splitter PBS11, and then passes through the fifteenth wave plate 2066, and the polarization direction is changed to the first polarization direction, so as to form eighteenth diffracted light, which exits the sixth beam splitter set 206 and enters the seventh beam splitter set 207.

Part of the diffracted light is split into nineteenth diffracted light having the first polarization direction and twentieth diffracted light having the second polarization direction by the twelfth polarization splitting prism PBS 12. The nineteenth diffraction light is reflected by the twelfth PBS12, then sequentially transmitted by the fourteenth wave plate 2064 and reflected by the seventh mirror 2065, and then transmitted by the fourteenth wave plate 2064 again, changed in polarization direction to the second polarization direction, then transmitted through the twelfth PBS12, transmitted through the twelfth wave plate 2061, changed in polarization direction to the first polarization direction, then reflected by the eleventh PBS11, and then transmitted through the fifteenth wave plate 2066, changed in polarization direction to the second polarization direction, to form twenty-first diffraction light, and then exits the sixth lens group 206 and enters the seventh lens group 207.

The twentieth diffracted light passes through the twelfth polarization beam splitter PBS12, and then passes through the fifteenth wave plate 2066, and the polarization direction is changed to the first polarization direction, so as to form a twenty-second diffracted light, which exits the sixth optical splitter group 206 and enters the seventh optical splitter group 207.

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.

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 are superposed to form a twenty-third diffracted light, and the twenty-third diffracted light enters the seventh mirror group 207.

Part of the twenty-third diffracted light enters the thirteenth polarization beam splitter PBS13, and part of the twenty-third diffracted light with the first polarization direction enters the seventh detection mirror group after passing through the thirteenth polarization beam splitter reflective PBS 13. The twenty-third diffracted light with the second polarization direction passes through the thirteenth PBS13, then sequentially passes through the seventeenth wave plate 2072 for transmission and reflection, then passes through the seventeenth wave plate 2072 again for transmission, changes the polarization direction to the first polarization direction, then passes through the thirteenth PBS13 for reflection, passes through the sixteenth wave plate 2071 for transmission, changes the polarization direction to the second polarization direction, then passes through the fourteenth PBS14, and enters the eighth detection mirror group.

The remaining part of the twenty-third diffracted light enters the fourteenth polarization splitting prism PBS 14. And the twenty-three diffracted lights with the first polarization direction are reflected by the fourteenth polarization beam splitter PBS14 and enter the eighth detection mirror group. The twenty-three diffracted lights with the second polarization direction penetrate through the fourteenth polarization beam splitter PBS14, then sequentially pass through the seventeenth wave plate 2072 for transmission and reflection, the eighth reflector 2073 for transmission again, pass through the seventeenth wave plate 2072 for transmission, change the polarization direction to the first polarization direction, then pass through the fourteenth polarization beam splitter PBS14 for reflection, pass through the sixteenth wave plate 20721 for transmission, change the polarization direction to the second polarization direction, pass through the thirteenth polarization beam splitter PBS13, and enter the seventh detection mirror group.

Further, the sixteenth wave plate is a half wave plate; the seventeenth wave plate is a quarter wave plate.

Thus, the alignment device provided by this example splits the light field of the diffracted light into two sub-light fields. Only two beam splitting mirror groups are needed, namely, the interference of the diffracted light in the two sub-light fields in the first polarization direction and the second polarization mode is realized, the error is reduced, the alignment precision is improved, and compared with the alignment device shown in the figure 3, the cost is low, and the operation is convenient.

In summary, in each embodiment, the light splitting unit 20 is arranged to achieve compatibility of diffracted lights arranged in multiple directions, the light field of the diffracted lights is divided into at least two sub-light fields, interference of the diffracted lights in each sub-light field in the first polarization direction and the second polarization mode is achieved through the detection unit 30, and detection is performed by using a plurality of detectors, so that alignment accuracy is greatly improved, and errors are reduced. And the position alignment can be realized without using a self-reference interference prism, so that the cost is reduced, and the operation is simple.

It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, similar parts between the embodiments may be referred to each other, and different parts between the embodiments may also be used in combination with each other, which is not limited by the present invention.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims

1. An alignment device, comprising: the device comprises an illumination unit, a light splitting unit and a detection unit;

the light splitting unit comprises at least one light splitting mirror group and is used for splitting the light field of the diffracted light into at least two sub light fields, and each sub light field comprises the diffracted light with a first polarization direction and the diffracted light with a second polarization direction;

2. The alignment device of claim 1, wherein the first polarization direction and the second polarization direction are perpendicular to each other.

3. The alignment device of claim 1, wherein 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, wherein when the diffracted lights are arranged in one direction, the splitting unit includes a first splitting mirror group including a second polarization splitting prism, a third polarization splitting prism, a second wave plate, a third wave plate, and a first mirror; the detection unit comprises a first detection mirror group, a first detector, a second detection mirror group, a third detector and a fourth detector; wherein the content of the first and second substances,

the negative order diffraction light in the diffraction light is divided into first diffraction light with a first polarization direction and second diffraction light with a second polarization direction after passing through the second polarization light splitting prism; after the first diffracted light is reflected by the second polarization beam splitter prism, the first diffracted light is transmitted by the second wave plate, changes the polarization direction into a second polarization direction, and then enters the first detection mirror group through the third polarization beam splitter prism;

5. The alignment device of claim 4, wherein the second wave plate is a half wave plate and the third wave plate is a quarter wave plate.

6. The alignment apparatus of claim 4, wherein the first diffracted light and the fourth diffracted light entering the first set of detector mirrors constitute a first sub-optical field; the second diffracted light and the third diffracted light entering the second detection mirror group form a second sub-optical field; the optical energy of the first sub-optical field and the second sub-optical field is the same.

7. The alignment device according to claim 1, wherein when the diffracted light is arranged in a plurality of directions, the splitting unit includes a second splitting mirror group including a plurality of fourth polarization splitting prisms, a fourth wave plate, a fifth wave plate, and a second mirror;

the plurality of fourth polarization splitting prisms are arranged in a ring shape corresponding to the plurality of arrangement directions of the diffracted light to form a fourth polarization splitting prism ring, the fourth wave plate is arranged at the position of the center of the fourth polarization splitting prism ring, the first surface of the fifth wave plate covers the surface, opposite to the fourth polarization splitting prism ring, of the diffracted light, and the second reflector covers the second surface, opposite to the first surface of the fifth wave plate; one side of each fourth polarization beam splitter prism, which is far away from the fourth wave plate, corresponds to one detection mirror group;

8. The alignment device of claim 7, wherein the fourth wave plate is a half wave plate and the fifth wave plate is a quarter wave plate.

9. The alignment apparatus of claim 1, wherein the light splitting unit includes a third light splitting lens group when the diffracted lights are arranged in a plurality of directions; the third beam splitter group comprises a fifth polarization beam splitter prism, a sixth wave plate, a seventh wave plate and a third reflector;

10. The alignment device of claim 9, wherein the sixth wave plate is a half wave plate and the seventh wave plate is a quarter wave plate.

11. The alignment device of claim 9, wherein the light splitting unit further comprises a fourth light splitting group; the fourth light splitting lens group comprises a seventh polarization light splitting prism, an eighth wave plate, a ninth wave plate and a fourth reflector; the detection unit comprises 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 content of the first and second substances,

the ninth diffraction light with the second polarization direction is superposed with the fourteenth diffraction light with the first polarization direction and enters the fourth spectroscope group;

after part of the fourteenth diffraction light is reflected by the eighth polarization beam splitter prism, the fourteenth diffraction light is transmitted by the eighth wave plate, changes the polarization direction into a second polarization direction, and then enters the third detection mirror group through the seventh polarization beam splitter prism;

12. The alignment device of claim 11, wherein the eighth wave plate is a half wave plate and the nine wave plate is a quarter wave plate.

13. The alignment device of claim 9, wherein the light splitting unit further comprises a fifth light splitting mirror group; the fifth beam splitter group comprises a ninth polarization beam splitter prism, a tenth wave plate, an eleventh wave plate and a fifth reflector; the detection unit further includes: the optical fiber laser comprises a fifth detection lens group, a ninth detector, a tenth detector, a sixth detection lens group, an eleventh detector and a twelfth detector; wherein, the first and the second end of the pipe are connected with each other,

after part of the tenth diffraction light is reflected by the tenth polarization beam splitter prism, the tenth diffraction light is transmitted by the tenth wave plate, the polarization direction is changed into a second polarization direction, and then the tenth diffraction light passes through the ninth polarization beam splitter prism and enters the fifth detection mirror group;

said ninth detector acquiring light energy of said first polarized light emitted by said fifth detector set and said tenth detector acquiring light energy of said second polarized light emitted by said fifth detector set; the eleventh detector acquires light energy of the first polarized light emitted by the sixth detector mirror group; the twelfth detector acquires light energy of the second polarized light emitted by the sixth set of detector mirrors.

14. The alignment device of claim 13, wherein the tenth wave plate is a half wave plate and the eleventh wave plate is a quarter wave plate.

15. The alignment apparatus as claimed in claim 1, wherein the light splitting unit includes a sixth light splitting lens group when the diffracted lights are arranged in a plurality of directions; the sixth beam splitting mirror group comprises an eleventh polarization beam splitting prism, a twelfth wave plate, a thirteenth wave plate, a fourteenth wave plate, a fifteenth wave plate, a sixth reflecting mirror and a seventh reflecting mirror; wherein the content of the first and second substances,

part of the diffracted light is divided into fifteenth diffracted light with a first polarization direction and sixteenth diffracted light with a second polarization direction through the eleventh polarization splitting prism; the fifteenth diffraction light is reflected by the eleventh polarization splitting prism, then sequentially transmitted by the thirteenth wave plate and reflected by the sixth reflector, then transmitted by the thirteenth wave plate again, changed in polarization direction into the second polarization direction, transmitted by the eleventh polarization splitting prism, transmitted by the twelfth wave plate, changed in polarization direction into the first polarization direction, reflected by the twelfth polarization splitting prism, transmitted by the fifteenth wave plate, changed in polarization direction into the second polarization direction, to form seventeenth diffraction light, and then emitted out of the sixth splitting mirror group;

the sixteenth diffraction light passes through the eleventh polarization beam splitter prism, then passes through the fifteenth wave plate, changes the polarization direction into the first polarization direction, forms eighteenth diffraction light and emits out of the sixth beam splitter group;

16. The alignment device of claim 15, wherein the twelfth wave plate and the fifteenth wave plate are each a half wave plate, and the thirteenth wave plate and the fourteenth wave plate are each a quarter wave plate.

17. The alignment device of claim 15, wherein the light splitting unit further comprises a seventh light splitting group; the seventh spectroscope group comprises a thirteenth polarizing spectroscope, a fourteenth polarizing spectroscope, a sixteenth wave plate, a seventeenth wave plate and an eighth reflector; the detection unit comprises 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 content of the first and second substances,

said thirteenth detector obtains the light energy of said first polarization from said seventh detector set and said fourteenth detector obtains the light energy of said second polarization from said seventh detector set; the fifteenth detector acquires light energy of the first polarized light emitted by the eighth set of detectors; the sixteenth detector acquires light energy of the second polarized light emitted by the eighth detector mirror group.

18. The alignment device of claim 17, wherein the sixteenth wave plate is a half wave plate; the seventeenth wave plate is a quarter wave plate.

19. The alignment device of claim 1, wherein the first wave plate is a half wave plate.

20. The alignment device of claim 1, wherein the illumination unit includes a light emitter and a ninth mirror; the light emitter is used for providing illumination, and the ninth reflector is used for changing the propagation direction of the illumination so that the illumination vertically irradiates on the grating mark.

21. The alignment device of claim 1, further comprising an objective lens and an eighteenth wave plate; the objective lens is used for converging and transmitting the illumination and the diffracted light; the eighteenth wave plate is used for changing the polarization direction of the diffracted light so that the diffracted light enters the light splitting unit in a 45-degree linearly polarized light mode.

22. The alignment device of claim 21, wherein the eighteenth wave plate is a half wave plate.

23. A lithography machine, characterized in that it comprises an alignment device according to any one of claims 1 to 22.

24. An alignment method using the lithography machine according to claim 23, said alignment method comprising:

the splitting unit splits the light field of the diffracted light into at least two sub-light fields, each of the sub-light fields including therein the diffracted light having the first polarization direction and the diffracted light having the second polarization direction;

the diffracted light in each sub-light field correspondingly enters one of the detecting lens groups in the detecting unit, and the diffracted light with the first polarization direction and the diffracted light with the second polarization direction change the polarization directions after being transmitted by the first wave plate, so that interference occurs in the first polarization direction and the second polarization direction respectively, and interference light is formed; the interference light enters the first polarization beam splitter prism and is divided into first polarized light and second polarized light by the first polarization beam splitter prism; one detector corresponding to the detection mirror group acquires light energy of first polarized light, and the other detector corresponding to the detection mirror group acquires light energy of second polarized light;