阅读说明：本技术 激光干涉光刻系统 (Laser interference photoetching system ) 是由 王磊杰 朱煜 张鸣 徐继涛 李鑫 成荣 杨开明 胡金春 于 2019-10-31 设计创作，主要内容包括：本发明属于光学仪器仪表设备技术领域,公开了一种激光干涉光刻系统,包括激光器、第一反射镜、光栅分束器、第二反射镜、第一万向反射镜、第一透镜、第二万向反射镜、第二透镜、分光棱镜、控制模块、角度测量模块、第三透镜和基底；所述控制模块包括信号处理端、控制器和驱动器,信号处理端与角度测量模块连接,控制器分别与信号处理端和驱动器连接,驱动器分别与第一万向反射镜和第二万向反射镜连接；激光器发出光源经过该系统分成两束光聚焦在基底上曝光；通过调节曝光的角度,实现渐变周期大面积光栅的制作。本发明以扫描干涉光刻方式制作的光栅尺寸不会受到曝光光斑大小的限制,可制造出大尺寸的渐变周期光栅。(The invention belongs to the technical field of optical instrument and meter equipment, and discloses a laser interference lithography system which comprises a laser, a first reflector, a grating beam splitter, a second reflector, a first universal reflector, a first lens, a second universal reflector, a second lens, a beam splitter prism, a control module, an angle measurement module, a third lens and a substrate; the control module comprises a signal processing end, a controller and a driver, the signal processing end is connected with the angle measuring module, the controller is respectively connected with the signal processing end and the driver, and the driver is respectively connected with the first universal reflector and the second universal reflector; the laser emits light which is divided into two beams by the system and focused on the substrate for exposure; and the manufacturing of the large-area grating with the gradually-changed period is realized by adjusting the exposure angle. The size of the grating manufactured by the scanning interference photoetching method is not limited by the size of the exposure facula, and the large-size gradient period grating can be manufactured.)

1. A laser interference lithography system, comprising: the device comprises a laser, a first reflector, a grating beam splitter, a second reflector, a first universal reflector, a first lens, a second universal reflector, a second lens, a beam splitter prism, a control module, an angle measurement module, a third lens and a substrate; the control module comprises a signal processing end, a controller and a driver, the signal processing end is connected with the angle measuring module, the controller is respectively connected with the signal processing end and the driver, and the driver is respectively connected with the first universal reflector and the second universal reflector; the optical path structure of the system is as follows:

a light source emitted by the laser is reflected to the grating beam splitter through the first reflecting mirror and is divided into a first beam of light and a second beam of light through the grating beam splitter;

the first beam of light is reflected by the second reflecting mirror, reflected by the first universal reflecting mirror and transmitted to the beam splitting prism by the first lens in sequence, the reflected light passing through the beam splitting prism is sent to the angle measuring module, and the transmitted light passing through the beam splitting prism is sent to the third lens to be focused on the substrate for exposure;

the second beam of light is reflected by a second universal reflector and transmitted to the beam splitting prism through a second lens in sequence, the transmitted light passing through the beam splitting prism is sent to the angle measuring module, and the reflected light passing through the beam splitting prism is sent to a third lens for transmission and focusing and is exposed on the substrate;

the angle measurement module measures the angle of the input first beam of light and the second beam of light, the measurement end information is transmitted to the signal processing end, the signal processing end processes the information and transmits the information to the controller, the controller generates a control command according to the received information and transmits the control command to the driver, the driver adjusts the angles of the first universal reflector and the second universal reflector according to the control command, the angle of the first beam of light and the second beam of light focused and exposed on the substrate is changed, and the substrate is manufactured into a grating through focused exposure.

2. The laser interference lithography system of claim 1, wherein: the device also comprises a phase measurement interferometer, a third reflector, a fourth reflector, a third universal reflector, a fourth lens, a light beam extraction mirror, a first phase modulator, a second phase modulator and a third phase modulator; the third universal reflector is connected with the driver, the control module further comprises a phase modulation actuator, and the phase modulation actuator is respectively connected with the controller, the first phase modulator, the second phase modulator and the third phase modulator; the phase measurement interferometer is connected with the signal processing end;

the first phase modulator is arranged between the laser and the first reflector, the laser emits light source, the first phase modulator separates zero-order diffraction light and first-order diffraction light, the zero-order diffraction light is transmitted to the first reflector, and the first-order diffraction light sequentially passes through the third reflector, the fourth reflector, the third universal reflector and the fourth lens to become third input light beams of the phase measurement interferometer;

the second phase modulator is arranged between the grating beam splitter and the second reflecting mirror; the third phase modulator is connected between the grating beam splitter and the second universal reflector;

the beam extraction mirror is arranged between the beam splitter prism and the third lens; the first beam of light is reflected by the light beam extraction mirror to be a second input light beam of the phase measurement interferometer; the second beam of light is reflected by the beam extraction mirror to be the first input beam of the phase measurement interferometer;

the first input beam, the second input beam and the third input beam are subjected to phase measurement interferometer to obtain two interference measurement electric signals, the two interference measurement electric signals are transmitted to a signal processing end, the signal processing end is used for resolving to obtain exposure fringe phase drift information, a compensation instruction is generated and transmitted to a phase modulation actuator, and the phase modulation actuator transmits the compensation instruction to a first phase modulator, a second phase modulator and a third phase modulator for phase modulation so as to complete locking of the exposure fringe phase drift; and the driver adjusts the angles of the first universal reflector, the second universal reflector and the third universal reflector according to the control instruction.

3. The laser interference lithography system of claim 2, wherein: the phase measurement interferometer comprises a first wave plate, a first polarization beam splitter prism, a second wave plate, a second polarization beam splitter prism, a polarizing plate, a first photoelectric detector, a second photoelectric detector, a third polarization beam splitter prism, a reflector, a third wave plate, a backward reflector and a fourth wave plate; the optical path structure of the phase measurement interferometer is as follows:

the third input light beam is input from the first wave plate, is changed into a circular polarization state through the first wave plate and enters the first polarization beam splitter prism, the reflected light of the first polarization beam splitter prism passes through the fourth wave plate to the backward reflector, is reflected by the backward reflector and turns back to the fourth wave plate to be changed into a p polarization state, and then is transmitted through the first polarization beam splitter prism and the second polarization beam splitter prism in sequence to form first reference light through the polaroid; the transmitted light passing through the first polarization beam splitter prism passes through the third wave plate to the reflector, is reflected back to the third wave plate by the reflector and then is changed into an s-polarization state to the first polarization beam splitter prism, is reflected to the second wave plate by the first polarization beam splitter prism and then is changed into a p-polarization state, and then is transmitted by the second polarization beam splitter prism and forms a second piece of reference light by the polaroid;

the first input light beam is input from a third polarization beam splitter prism in an s-polarization state, reflected to a second polarization beam splitter prism through the third polarization beam splitter prism and reflected to a polaroid through the second polarization beam splitter prism to form first path of measuring light;

the second input beam is parallel to the first input beam, is input from a third polarization beam splitter prism in an s-polarization state, is reflected to a second polarization beam splitter prism through the third polarization beam splitter prism, and is reflected to a polarizer through the second polarization beam splitter prism to form a second path of measuring light;

the first path of measuring light and the first reference light are combined to form one interference measuring signal to be incident to the first photoelectric detector, and the second path of measuring light and the second reference light are combined to form another interference measuring signal to be incident to the second photoelectric detector;

the first photoelectric detector and the second photoelectric detector respectively convert the received interference measurement signals into electric signals and then transmit the electric signals to the signal processing end.

4. The laser interference lithography system of claim 2, wherein: the first lens, the second lens, the third lens and the fourth lens are all convex lenses.

5. The laser interference lithography system of claim 2, wherein: the second phase modulator and the third phase modulator adopt acousto-optic modulators.

6. The laser interference lithography system of claim 3, wherein: the first wave plate is a quarter wave plate.

7. The laser interference lithography system of claim 3, wherein: the second wave plate is a half wave plate.

8. The laser interference lithography system of claim 3, wherein: the third wave plate is a quarter wave plate.

9. The laser interference lithography system of claim 3, wherein: the fourth wave plate is a quarter wave plate.

10. The laser interference lithography system according to any one of claims 2 to 9, wherein: the control module further comprises a display screen, and the display screen is connected with the controller to realize data visualization.

Technical Field

The invention belongs to the technical field of optical instrument and meter equipment, and particularly relates to a laser interference lithography system which can be used for manufacturing large-size gradient period gratings.

Background

The laser interference photoetching technology is an important technology for manufacturing micro-nano array devices by exposing a photosensitive substrate with a periodic pattern generated by two or more beams of laser interference, is mainly applied to manufacturing devices such as a column array, a grating, a hole array, a dot matrix, a micro-lens array and the like with characteristic dimensions lower than sub-wavelength, and is widely applied to the fields of national defense, civil science, scientific research and the like.

The grating device is used as a key device in a large-scale astronomical telescope, an inertial confinement nuclear fusion laser ignition system, a photoetching system and other heavy engineering systems, requirements on size, grating line density, precision and the like are continuously improved in recent years, and meanwhile, the application type of the grating is not limited to one-dimensional gratings, but also comprises two-dimensional gratings, curved gratings, variable-period gratings and the like. The manufacture of the grating is advancing to the magnitude of meter-scale size, nanometer-scale precision and sub-ten thousand-level grid line density, and the manufacture of diversified large-size gratings with high-precision grid lines is a hot point problem which needs to be solved urgently in the field of grating manufacture. The traditional grating manufacturing technologies such as mechanical scribing, laser direct writing and mechanical splicing have different technical defects, the main defects of the mechanical scribing comprise low large-area manufacturing precision, long processing period, ghost lines in manufactured gratings and the like, the main defects of the laser direct writing comprise low large-area manufacturing precision, long processing period and the like, and the defects of poor splicing precision, complex splicing process, high cost and the like exist in the mechanical splicing. Therefore, the manufacturing of the grating with the above magnitude is difficult to be realized by the conventional technology, the manufacturing of the grating with the dense grating lines with high precision and the large area with short processing period can be realized by the laser interference lithography technology or the holographic lithography technology, and the laser interference lithography technology also gradually becomes the mainstream of the manufacturing technology of the grating with the large area and the high precision. The main difficulty of the interference lithography technology in the application of large-area high-precision grating manufacturing is the research and development of an interference lithography system, and the high-precision interference lithography system has great research and development difficulty. A series of researches on the development of high-precision interference lithography systems are conducted by a plurality of famous grating manufacturing system companies and research institutions in the world, the researches mainly focus on the high-precision interference lithography systems, and research results are disclosed in a plurality of patents.

The Massachusetts institute of technology in United states patent US6,882,477B1 discloses a scanning laser interference lithography system, which utilizes two collimated small-sized light beams to interfere to form an interference pattern and expose a substrate which makes step-by-step scanning movement to realize large-area grating manufacturing, and the collimated small-sized light beams interfere to effectively eliminate the phase nonlinear error of the interference pattern; meanwhile, in order to prevent the system interference pattern from generating phase drift relative to a moving substrate platform to cause errors, the photoetching system lists a pattern locking device based on the heterodyne measurement principle, the device generates frequency difference of heterodyne phase measurement by arranging three acousto-optic modulators in an interference light path, a beam sampler is utilized to sample interference beams to a heterodyne phase meter to carry out pattern phase detection, and the detected phases are fed back to a control module to control the modulation phases of the acousto-optic modulators to realize pattern locking.

The national academy of sciences of China, Changchun optical precision machinery and the institute of physics, China patent CN103698835A, discloses a lithography system, which realizes the manufacture of a holographic grating by using a holographic exposure method and locks the phase of interference fringes relative to a grating substrate at a certain fixed value by using a heterodyne measurement method. The photoetching system can well inhibit the dithering of high-frequency stripes in the exposure process, but cannot realize the manufacture of large-area variable-period gratings. The study of chinese patents such as CN1544994A, CN101718884A, and CN101793988A only discloses methods for adjusting the optical path and the gate line density of the holographic lithography system, and no discussion about the interference system and the pattern locking is found. Suzhou Suda Viger optoelectronic technology corporation, China patent publication No. CN101846890 discloses a parallel interference lithography system, which uses grating light splitting and lens light combining, but the interference lithography system does not have an interference pattern phase locking device, so that the laser interference lithography system is difficult to realize the manufacture of large-area high-precision gratings.

Therefore, the manufacture of large-size gradient period gratings, especially the manufacture of high-precision large-size gradient period gratings, has been an industry problem.

Disclosure of Invention

In order to solve the manufacturing problem of the large-area grating with the gradually-changed period, the invention provides a laser interference lithography system, which comprises a laser, a first reflector, a grating beam splitter, a second reflector, a first universal reflector, a first lens, a second universal reflector, a second lens, a beam splitter prism, a control module, an angle measuring module, a third lens and a substrate; the control module comprises a signal processing end, a controller and a driver, the signal processing end is connected with the angle measuring module, the controller is respectively connected with the signal processing end and the driver, and the driver is respectively connected with the first universal reflector and the second universal reflector; the optical path structure of the system is as follows:

a light source emitted by the laser is reflected to the grating beam splitter through the first reflecting mirror and is divided into a first beam of light and a second beam of light through the grating beam splitter;

the first beam of light is reflected by the second reflecting mirror, reflected by the first universal reflecting mirror and transmitted to the beam splitting prism by the first lens in sequence, the reflected light passing through the beam splitting prism is sent to the angle measuring module, and the transmitted light passing through the beam splitting prism is sent to the third lens to be focused on the substrate for exposure;

the second beam of light is reflected by a second universal reflector and transmitted to the beam splitting prism through a second lens in sequence, the transmitted light passing through the beam splitting prism is sent to the angle measuring module, and the reflected light passing through the beam splitting prism is sent to a third lens for transmission and focusing and is exposed on the substrate;

the angle measurement module measures the angle of the input first beam of light and the second beam of light, the measurement end information is transmitted to the signal processing end, the signal processing end processes the information and transmits the information to the controller, the controller generates a control command according to the received information and transmits the control command to the driver, the driver adjusts the angles of the first universal reflector and the second universal reflector according to the control command, the angle of the first beam of light and the second beam of light focused and exposed on the substrate is changed, and the substrate is manufactured into a grating through focused exposure.

Preferably, the laser interference lithography system further comprises a phase measurement interferometer, a third reflector, a fourth reflector, a third gimbal reflector, a fourth lens, a beam extraction mirror, a first phase modulator, a second phase modulator, and a third phase modulator; the third universal reflector is connected with the driver, the control module further comprises a phase modulation actuator, and the phase modulation actuator is respectively connected with the controller, the first phase modulator, the second phase modulator and the third phase modulator; the phase measurement interferometer is connected with the signal processing end;

the first phase modulator is arranged between the laser and the first reflector, the laser emits light source, the first phase modulator separates zero-order diffraction light and first-order diffraction light, the zero-order diffraction light is transmitted to the first reflector, and the first-order diffraction light sequentially passes through the third reflector, the fourth reflector, the third universal reflector and the fourth lens to become third input light beams of the phase measurement interferometer;

the second phase modulator is arranged between the grating beam splitter and the second reflecting mirror; the third phase modulator is connected between the grating beam splitter and the second universal reflector;

the beam extraction mirror is arranged between the beam splitter prism and the third lens; the first beam of light is reflected by the light beam extraction mirror to be a second input light beam of the phase measurement interferometer; the second beam of light is reflected by the beam extraction mirror to be the first input beam of the phase measurement interferometer;

the first input beam, the second input beam and the third input beam are subjected to phase measurement interferometer to obtain two interference measurement electric signals, the two interference measurement electric signals are transmitted to a signal processing end, the signal processing end is used for resolving to obtain exposure fringe phase drift information, a compensation instruction is generated and transmitted to a phase modulation actuator, and the phase modulation actuator transmits the compensation instruction to a first phase modulator, a second phase modulator and a third phase modulator for phase modulation so as to complete locking of the exposure fringe phase drift; and the driver adjusts the angles of the first universal reflector, the second universal reflector and the third universal reflector according to the control instruction.

Furthermore, the phase measurement interferometer comprises a first wave plate, a first polarization splitting prism, a second wave plate, a second polarization splitting prism, a polarizing plate, a first photoelectric detector, a second photoelectric detector, a third polarization splitting prism, a reflector, a third wave plate, a retro-reflector and a fourth wave plate; the optical path structure of the phase measurement interferometer is as follows:

the third input light beam is input from the first wave plate, is changed into a circular polarization state through the first wave plate and enters the first polarization beam splitter prism, the reflected light of the first polarization beam splitter prism passes through the fourth wave plate to the backward reflector, is reflected by the backward reflector and turns back to the fourth wave plate to be changed into a p polarization state, and then is transmitted through the first polarization beam splitter prism and the second polarization beam splitter prism in sequence to form first reference light through the polaroid; the transmitted light passing through the first polarization beam splitter prism passes through the third wave plate to the reflector, is reflected back to the third wave plate by the reflector and then is changed into an s-polarization state to the first polarization beam splitter prism, is reflected to the second wave plate by the first polarization beam splitter prism and then is changed into a p-polarization state, and then is transmitted by the second polarization beam splitter prism and forms a second piece of reference light by the polaroid;

the first input light beam is input from a third polarization beam splitter prism in an s-polarization state, reflected to a second polarization beam splitter prism through the third polarization beam splitter prism and reflected to a polaroid through the second polarization beam splitter prism to form first path of measuring light;

the second input beam is parallel to the first input beam, is input from a third polarization beam splitter prism in an s-polarization state, is reflected to a second polarization beam splitter prism through the third polarization beam splitter prism, and is reflected to a polarizer through the second polarization beam splitter prism to form a second path of measuring light;

the first path of measuring light and the first reference light are combined to form one interference measuring signal to be incident to the first photoelectric detector, and the second path of measuring light and the second reference light are combined to form another interference measuring signal to be incident to the second photoelectric detector;

the first photoelectric detector and the second photoelectric detector respectively convert the received interference measurement signals into electric signals and then transmit the electric signals to the signal processing end.

Further, the first lens, the second lens, the third lens and the fourth lens are all convex lenses.

Further, the second phase modulator and the third phase modulator adopt acousto-optic modulators.

Further, the first wave plate is a quarter wave plate.

Further, the second wave plate is a half wave plate.

Further, the third wave plate is a quarter wave plate.

Further, the fourth wave plate is a quarter wave plate.

Furthermore, the control module also comprises a display screen, and the display screen is connected with the controller to realize data visualization.

The laser interference photoetching system adopts the angle measuring module to measure the angle of the exposure light beam, when the system carries out interference photoetching of the variable-period grating, the controller sends an angle change control instruction to the driver according to the measuring result output by the angle measuring module and the period change requirement of the grating manufacture, and the driver carries out corresponding angle adjustment on the first universal reflector and the second universal reflector to complete the control of the angle of the exposure light beam. In the photolithography process, the grating substrate is moved in a scanning step along the exposure beam focal plane to complete the fabrication of the variable period grating. The size of the grating manufactured by the scanning interference photoetching mode is not limited by the size of the exposure facula, and the large-size gradient period grating can be manufactured.

Drawings

FIG. 1 is a schematic diagram of a laser interference lithography system according to an embodiment of the present invention;

FIG. 2 is a schematic view of a second embodiment of a laser interference lithography system according to the present invention;

fig. 3 is a schematic diagram of the optical path structure of the phase measurement interferometer.

In the figure: 1-laser, 2-first reflector, 3-grating beam splitter, 401-second reflector, 402-first universal reflector, 403-first lens, 501-second universal reflector, 502-second lens, 6-beam splitter prism, 7-phase measurement interferometer, 701-first wave plate, 702-first polarization beam splitter prism, 703-a second wave plate, 704-a second polarization splitting prism, 705-a polarizer, 706-a first photodetector, 707-a second photodetector, 708-a third polarization splitting prism, 709-a second input beam, 710-a first input beam, 711-a mirror, 712-a third wave plate, 713-a retro-mirror, 714-a fourth wave plate, 715-a third input beam; 8-control module, 801-signal processing terminal, 802-controller, 803-driver, 804-phase modulation actuator; 9-angle measuring module, 10-third lens, 11-substrate, 12-third mirror, 13-fourth mirror, 14-third universal mirror, 15-fourth lens, 16-beam extraction mirror, 17-first phase modulator, 18-second phase modulator, 19-third phase modulator.

Detailed Description

To further illustrate the technical means and effects of the present invention to solve the technical problems, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments, which are provided for illustrative purposes and are not drawn to scale or scale completely, and therefore, the accompanying drawings and specific embodiments are not limited to the protection scope of the present invention.

An alternative embodiment of the laser interference lithography system shown in fig. 1 comprises a laser 1, a first mirror 2, a grating beam splitter 3, a second mirror 401, a first universal mirror 402, a first lens 403, a second universal mirror 501, a second lens 502, a beam splitter prism 6, a control module 8, an angle measurement module 9, a third lens 10, and a substrate 11; the control module 8 comprises a signal processing end 801, a controller 802 and a driver 803, the signal processing end 801 is connected with the angle measuring module 9, the controller 802 is respectively connected with the signal processing end 801 and the driver 803, and the driver 803 is respectively connected with the first universal reflector 402 and the second universal reflector 501; the optical path structure of the system is as follows:

a light source emitted by the laser 1 is reflected to the grating beam splitter 3 through the first reflector 2 and is split into a first beam of light and a second beam of light through the grating beam splitter 3;

the first beam of light is reflected by the second reflector 401 and the first universal reflector 402 in sequence and is transmitted to the beam splitter prism 6 through the first lens 403, the reflected light passing through the beam splitter prism 6 is sent to the angle measuring module 9, and the transmitted light passing through the beam splitter prism 6 is sent to the third lens 10 to be focused on the substrate 11 for exposure;

the second beam of light is reflected by a second universal reflector 501 and transmitted to the beam splitter prism 6 through the second lens 502 in sequence, the transmitted light through the beam splitter prism 6 is sent to the angle measuring module 9, and the reflected light through the beam splitter prism 6 is sent to the third lens 10 to be focused on the substrate 11 for exposure;

the angle measuring module 9 measures the angle of the input first beam and second beam, and transmits the measurement end information to the signal processing terminal 801, the signal processing terminal 801 transmits the processed information to the controller 802, the controller 802 generates a control command according to the received information and transmits the control command to the driver 803, the driver 803 adjusts the angles of the first universal mirror 402 and the second universal mirror 501 according to the control command, changes the angle of the focus exposure of the first beam and the second beam on the substrate 11, and the substrate 11 is made into a grating by the scan lithography of the focus exposure.

An alternative embodiment of the laser interference lithography system shown in fig. 2 comprises a laser 1, a first mirror 2, a grating beam splitter 3, a second mirror 401, a first universal mirror 402, a first lens 403, a second universal mirror 501, a second lens 502, a beam splitter prism 6, a phase measurement interferometer 7, a control module 8, an angle measurement module 9, a third lens 10, a substrate 11, a third mirror 12, a fourth mirror 13, a third universal mirror 14, a fourth lens 15, a beam extraction mirror 16, a first phase modulator 17, a second phase modulator 18, and a third phase modulator 19; the control module 8 comprises a signal processing end 801, a controller 802, a driver 803 and a phase modulation actuator 804, wherein the signal processing end 801 is connected with the angle measuring module 9 and the phase measurement interferometer 7, the controller 802 is respectively connected with the signal processing end 801, the driver 803 and the phase modulation actuator 804, and the driver 803 is respectively connected with the first universal reflector 4002, the second universal reflector 501 and the third universal reflector 14; the phase modulation actuator 804 is respectively connected with the first phase modulator 17, the second phase modulator 18 and the third phase modulator 19; the first lens, the second lens, the third lens and the fourth lens are all convex lenses, and the second phase modulator 18 and the third phase modulator 19 can adopt acousto-optic modulators; the optical path structure of the system is as follows:

the laser 1 emits light source which is divided into zero-order diffraction light and first-order diffraction light through the first phase modulator 17; the zero-order diffraction light is reflected to the grating beam splitter 3 by the first reflector 2 and is split into first light and second light by the grating beam splitter 3;

the first beam of light is reflected by the second phase modulator 18, the second reflector 401 and the first universal reflector 402 in sequence and is transmitted to the beam splitter prism 6 through the first lens 403, the reflected light passing through the beam splitter prism 6 is sent to the angle measuring module 9, the transmitted light passing through the beam splitter prism 6 is sent to the beam extraction mirror 16, the split beam reflected by the beam extraction mirror 16 becomes the second input beam 709 of the phase measuring interferometer 7, and the second input beam 709 is transmitted by the beam extraction mirror 16 and is transmitted and focused on the substrate 11 through the third lens 10 for exposure;

the second beam of light is reflected by the third phase modulator 19 and the second universal reflector 501 in sequence and is transmitted to the beam splitter prism 6 through the second lens 502, the transmitted light passing through the beam splitter prism 6 is sent to the angle measuring module 9, the reflected light passing through the beam splitter prism 6 is sent to the beam extraction mirror 16, the split beam reflected by the beam extraction mirror 16 becomes the first input beam 710 of the phase measuring interferometer 7, and the first input beam is transmitted by the beam extraction mirror 16 and is focused on the substrate 11 through the third lens 10 for exposure;

the first-order diffracted light divided by the first phase modulator 17 is reflected by the third reflector 12, the fourth reflector 13 and the third universal reflector 14 in sequence, and then is transmitted by the fourth lens 15 to become a third input beam 715 of the phase measurement interferometer 7;

the structure of the phase measurement interferometer 7 is shown in fig. 3 in detail, and the phase measurement interferometer 7 includes a first wave plate 701, a first polarization splitting prism 702, a second wave plate 703, a second polarization splitting prism 704, a polarizing plate 705, a first photodetector 706, a second photodetector 707, a third polarization splitting prism 708, a reflecting mirror 711, a third wave plate 712, a retro-reflecting mirror 713, and a fourth wave plate 714; the signal processing terminal 801 is connected with the first photodetector 706 and the second photodetector 707 of the phase measurement interferometer 7; the first wave plate 701, the third wave plate 712 and the fourth wave plate 714 are all quarter wave plates, the second wave plate 703 is a half wave plate, and the optical path structure of the phase measurement interferometer 7 is as follows:

third input beam 715 has additional frequency f_s3The reference light is input from the first wave plate 701, changed into a circular polarization state by the first wave plate 701 in an s-polarization state and then enters the first polarization beam splitter 702, reflected light passing through the first polarization beam splitter 702 passes through the fourth wave plate 714 to the retro-reflector 713, is reflected by the retro-reflector 713 and turns back to the fourth wave plate 714 to be changed into a p-polarization state, and then is transmitted by the first polarization beam splitter 702 and the second polarization beam splitter 704 in sequence, and then passes through the polarizing plate 705 to form a first reference light; the transmitted light passing through the first polarization beam splitter 702 passes through the third wave plate 712 to the reflector 711, is reflected back to the third wave plate 712 by the reflector 711, is converted into an s-polarization state to the first polarization beam splitter 702, is reflected to the second wave plate 703 by the first polarization beam splitter 702, is converted into a p-polarization state, and is transmitted through the second polarization beam splitter 704 and the polarizer 705 in sequence to form a second piece of reference light;

additional frequency f of first input beam 710_s1The s-polarized light is input from the third polarization beam splitter 708, reflected to the second polarization beam splitter 704 by the third polarization beam splitter 708, and reflected to the polarizer 705 by the second polarization beam splitter 704Forming a first path of measuring light;

second input beam 709 is parallel to first input beam 710 at additional frequency f_s2The s-polarized light is input from the third polarization beam splitter prism 708, reflected to the second polarization beam splitter prism 704 through the third polarization beam splitter prism 708, and reflected to the polarizer 705 through the second polarization beam splitter prism 704 to form a second path of measurement light;

the first path of measurement light and the first reference light are combined to form one interference measurement signal and are incident to the first photoelectric detector 706, and the second path of measurement light and the second reference light are combined to form another interference measurement signal and are incident to the second photoelectric detector 707; the first photodetector 706 and the second photodetector 707 convert the received interferometric signals into electrical signals, respectively;

the first input light beam 710, the second input light beam 709 and the third input light beam 715 are subjected to phase measurement by the phase measurement interferometer 7 to obtain two interference measurement electrical signals, when the variable period grating interference lithography is performed, the two interference measurement electrical signals are transmitted to the signal processing end 801, the signal processing end 801 performs resolution on the controller 802 to obtain exposure fringe phase drift information, a compensation instruction is generated and transmitted to the phase modulation actuator 804, and the compensation instruction is transmitted to the first phase modulator 17, the second phase modulator 18 and the third phase modulator 19 by the phase modulation actuator 804 to perform phase modulation, so that the locking of the exposure fringe phase drift is completed; the angle information of the first beam and the second beam detected by the angle measurement module 9 is transmitted to the signal processing terminal 801, the signal processing terminal 801 is sent to the controller 802, the controller 802 calculates the adjustment amount required by the angle of the exposure beam, the angle adjustment amount information is transmitted to the driver 803 by combining the measurement result, the driver 803 controls the first universal mirror 402, the second universal mirror 501 and the third universal mirror 14 to adjust the angle, so as to achieve the purpose of adjusting the exposure angle, if the grating period is to be increased/decreased, the angle of the exposure beam is correspondingly decreased/increased, the interval between the exposure beams is also decreased/increased, the control module outputs an instruction through the driver thereof to adjust the first universal mirror 402 and the second universal mirror 501 to rotate counterclockwise/clockwise, and simultaneously adjusts the third universal mirror 14 to rotate clockwise/counterclockwise, so as to ensure that the interference measurement signal always keeps beam combination, the intensity of the measurement signal cannot be weakened, and the accurate fringe control in the exposure process is kept, so that the interference lithography precision of the large-area variable-period grating is improved.

The principle of the interferometric signal formation of the phase measuring interferometer used in the present invention is further explained below:

the light vector matrix of the first input light beam s1 can be expressed as:

in the formula:

E_s1a matrix of light vectors representing the first input light beam s 1;

E₁representing the amplitude of the first input beam s 1;

i represents an imaginary unit;

f_s1representing the vibration frequency of the first input beam s1 containing additional frequencies;

t represents the time of forward propagation of the laser in space;

indicating the initial phase of the first input beam s 1;

the light vector matrix of the second input light beam s2 can be expressed as:

in the formula:

E_s2a matrix of light vectors representing a second input light beam s 2;

E₂representing the amplitude of the second input beam s 2;

f_s2representing the frequency of vibration of the second input beam s2 containing additional frequencies;

indicating the initial phase of the second input beam s 2;

the third input beam s3 is a heterodyne measurement reference beam whose light vector matrix can be expressed as:

in the formula:

E_s3a matrix of light vectors representing a third input light beam s 3;

E₃representing the amplitude of the third input beam s 3;

f_s3representing the frequency of vibration of a third input beam s3 containing additional frequencies;

represents the initial phase of the third input beam s 3;

the first path of measuring light is transmitted by the first input light beam s1 via the optical path: s1 → PBSR3 (third polarization splitting prism reflection) → PBSR2 (second polarization splitting prism reflection) → PF (45 ° arrangement polarizer) are formed, so that the light vector of the first path of measurement light is:

in the formula:

E_S11an optical vector matrix representing the first path of measuring light;

J_PFa Jones matrix representing a transmission optical path of the polarizer;

J_PBSR2a Jones matrix representing a reflected light path of the second PBS;

J_PBSR3a Jones matrix representing a reflected light path of the second PBS;

the first reference beam is split by the third input beam s3 and passes through the following optical path: s3 → QW1 (first wave plate with 45 ° fast axis), → PBSR1 (first polarization splitting prism reflection) → QW4 (fourth wave plate with 45 ° fast axis), → RR (retro-reflector) → QW4 (fourth wave plate with 45 ° fast axis), PBST1 (first polarization splitting prism transmission) → PBST2 (second polarization splitting prism transmission) → PF (polarizing plate with 45 ° arrangement), so that the light vector of the first reference beam is:

in the formula:

E_S31a matrix of light vectors representing the first reference beam;

J_PBST1a Jones matrix representing a transmission light path of the first polarization splitting prism;

J_PBST2a Jones matrix representing a transmission light path of the second polarization splitting prism;

J_QW1a matrix representing the first wave plate transmission path;

J_QW4a matrix representing a transmission optical path of the fourth wave plate;

the first path of measurement light and the first reference beam are combined to form a beam of interference measurement signal to be incident on the first photodetector 706, so that the light intensity value of the interference measurement signal obtained by the first photodetector 706 can be obtained:

in the formula:

I₁the light intensity of an interference measurement light signal formed by combining the first path of measurement light and the first reference beam is represented;

Δf₁representing the vibration frequency of an interference measurement optical signal formed by combining the first path of measurement light and the first reference beam;

the phase of an interference measurement optical signal formed by combining the first path of measurement light and the first reference beam is represented;

the second measuring beam is formed by the second input beam s2 via the optical path: s2 → PBSR3 (third polarizing beam splitter reflection) → PBSR2 (second polarizing beam splitter reflection) → PF (45 ° arranged polarizing plate) are formed, so that the light vector of the second path of measurement light is:

in the formula:

E_S21an optical vector matrix representing the second path of measuring light;

the second reference beam is split by the third input beam s3 and passes through the optical path: s3 → QW1 (first wave plate with 45 ° fast axis arrangement) → PBST1 (first polarization splitting prism transmission) → QW3 (third wave plate with 45 ° fast axis arrangement) → R (mirror) → QW3 (third wave plate with 45 ° fast axis arrangement) → PBSR1 (first polarization splitting prism reflection) → HW (second wave plate with 45 ° arrangement) → PBST2 (second polarization splitting prism transmission) → PF (polarizing plate with 45 ° arrangement), so that the light vector of the second reference beam is:

in the formula:

E_S32a light vector matrix representing the second reference beam;

J_PBSR1a Jones matrix representing a reflected light path of the first PBS;

J_QW3a matrix representing a third wave plate transmission optical path;

J_HWa matrix representing the transmission path of the second wave plate;

the second path of measurement light and the second reference beam are combined to form another beam of interference measurement signal to be incident on the second photodetector 707, so that the light intensity value of the interference measurement signal obtained by the second photodetector 707 can be obtained:

in the formula:

I₂the light intensity of an interference measurement light signal formed by combining the second path of measurement light and the second reference beam is represented;

Δf₂the vibration frequency of an interference measurement optical signal formed by combining the second path of measurement light and the second reference beam is represented;

the phase of an interference measurement optical signal formed by combining the second path of measurement light and the second reference beam is represented;

two interference measurement optical signals formed by combining the light beams have the same frequency difference, and include phase information of the measurement input light beams s1 and s2 and the input heterodyne reference light s3, the phase information is converted into an electric signal and then transmitted to a controller through a signal processing end to be processed, the phase of the exposure light beam can be calculated, and the phase measurement of the exposure light beam is completed.

It should be noted that all the above parameters adopt international standard units.

Of course, the present invention may have other embodiments, for example, the control module may include a display screen, and the display screen is connected to the controller to realize data visualization. Various modifications and changes may be made by those skilled in the art without departing from the spirit and substance of the invention, and these modifications and changes are within the scope of the claims.