Zero position sensor measuring system and photoetching machine workpiece table

Abstract

The utility model provides a zero-position sensor measuring system and a photoetching machine workpiece table, three zero-position sensors in the zero-position sensor measuring system are fixed at the bottom of a metering frame, corresponding pyramidal mirrors are fixed on the top surface or the side surface of the photoetching machine workpiece table, and the zero-position sensors are in one-to-one correspondence with the pyramidal mirrors; the positions of the three zero position sensors are not in the same straight line; the zero position sensor acquisition card is respectively connected with the three zero position sensors and is connected with the field programmable gate array, the field programmable gate array is connected with the digital signal processor, and the digital signal processor is connected with the upper computer. According to the embodiment of the utility model, measurement is carried out between the zero position sensor and the pyramid lens through laser, and the six-degree-of-freedom displacement of the workpiece table of the photoetching machine is obtained by carrying out settlement on data acquired by the zero position sensor, and finally, an accurate zero point can be provided for a relative displacement measurement system of the workpiece table.

Description

Technical Field

[0001] The utility model relates to the technical field of displacement measurement, in particular to a zero position sensor measurement system and a photolithography machine workpiece stage. Background Art

[0002] In the semiconductor manufacturing industry, photolithography is one of the most important equipment used to produce high-precision and high-performance semiconductor chips. In the photolithography, the displacement of the workpiece stage needs to be accurately measured to ensure the accuracy and quality of chip processing. In the prior art, interferometers and plane gratings are usually used to measure the displacement of the workpiece stage. However, since interferometer measurement and plane grating measurement are relative displacement sensors, and a precise six-degree-of-freedom absolute coordinate is required for the initialization of the workpiece stage motion control, the above measurement method alone cannot obtain an accurate zero point. Utility Model Content

[0003] To solve the above problems, an embodiment of the utility model provides a zero position sensor measurement system for determining the zero position of a grating interferometer, comprising a metrology frame, three zero position sensors and corresponding corner cubes, a zero position sensor acquisition card, a digital signal processor and a field programmable gate array; the three zero position sensors are fixed to the bottom of the metrology frame, the corresponding corner cubes are fixed to the top surface or side surface of the workpiece table of the lithography machine, and the zero position sensors correspond to the corner cubes one by one; the positions of the three zero position sensors are not in the same straight line; the zero position sensor acquisition card is connected to the three zero position sensors respectively, and to the field programmable gate array, the field programmable gate array is connected to the digital signal processor, and the digital signal processor is connected to a host computer.

[0004] Optionally, the three zero position sensors are distributed in a triangle at the bottom of the metering frame.

[0005] Optionally, the zero position sensor includes a two-dimensional position sensitive detector, a collimator and an optical fiber, the optical fiber is connected to a laser, the laser output by the collimator is incident on the bottom surface of the corresponding corner cube, and the two-dimensional position sensitive detector receives the laser reflected by the corner cube.

[0006] Optionally, the working light surface of each of the corner cubes corresponds to a light-sensitive surface of a two-dimensional position sensitive detector of each corresponding zero position sensor at a certain angle.

[0007] Optionally, it also includes a laser; the laser is connected to the optical fibers of the three zero position sensors respectively through a beam splitter element.

[0008] Optionally, the metrology frame is opposite to the workpiece stage of the lithography machine and is arranged above the workpiece stage of the lithography machine.

[0009] Optionally, the zero position sensor acquisition card includes an analog-to-digital conversion unit; the analog-to-digital conversion unit is used to convert the analog voltage signal of the two-dimensional position sensitive detector into a digital signal.

[0010] Optionally, the zero-position sensor acquisition card further includes a signal preprocessing unit; the signal preprocessing unit is used to preprocess the digital signal, and the preprocessing includes: data denoising, data normalization, and data transformation.

[0011] Optionally, the digital signal processor includes a signal processing unit; the signal processing unit is used to process the preprocessed data and solve the six-degree-of-freedom coordinates of the workpiece stage based on a coordinate transformation algorithm.

[0012] An embodiment of the utility model provides a workpiece stage of a photolithography machine, comprising the above-mentioned zero position sensor measurement system for determining the zero position of an interferometer of the photolithography machine.

[0013] The zero position sensor measurement system and the lithography machine worktable provided by the embodiment of the utility model perform measurement between the zero position sensor located on the metrology frame and the corner cone mirror located on the lithography machine worktable by laser, and settle the data collected by the zero position sensor by the digital signal processor to obtain the six-degree-of-freedom displacement of the lithography machine worktable, and finally provide an accurate zero point for the relative displacement measurement system of the worktable. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0015] Figure 1 This is a schematic diagram of the structure of the zero position sensor measurement system in the embodiment of the utility model;

[0016] Figure 2 This is a distribution diagram of the zero position sensor and the corner cube in the embodiment of the utility model. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific embodiments of the utility model are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0018] Since interferometer measurement and plane grating measurement belong to relative displacement sensors, the embodiment of the utility model provides an accurate zero point for the relative displacement measurement system based on an additional zero position sensor.

[0019] The embodiment of the utility model provides a zero position sensor measurement system using three zero position sensors, which is used to determine the zero point of the interferometer displacement measurement system of the workpiece stage of the lithography machine and can realize the six-degree-of-freedom displacement measurement of the workpiece stage of the lithography machine.

[0020] Exemplarily, the system includes three position sensitive detectors (PSD), which are arranged at three corners of the workpiece stage of the lithography machine to achieve accurate zero point measurement. In addition, the data processing module of the system adopts the digital signal processing (DSP) and field programmable gate array (FPGA) hardware architecture. The FPGA is responsible for collecting the data after AD conversion from the zero-position data acquisition card and sending the digital quantity to the DSP. The DSP uses the original voltage data to solve the six-degree-of-freedom displacement of the workpiece stage of the lithography machine and finally determines the zero point of the workpiece stage displacement measurement system.

[0021] The embodiment of the utility model provides a zero position sensor measurement system for determining the zero position of an interferometer of a lithography machine, comprising a metrology frame, three zero position sensors and corresponding conic mirrors, a zero position sensor acquisition card, a digital signal processor DSP and a field programmable gate array FPGA.

[0022] The three zero position sensors are fixed at the bottom of the measurement frame, and the corresponding corner cubes are fixed at the top or side of the workpiece table of the lithography machine, and the zero position sensors correspond to the corner cubes one by one. Among them, the positions of the three zero position sensors are not in the same straight line.

[0023] Exemplarily, the three zero position sensors are distributed in a triangle at the bottom of the metering frame. For example, the three zero position sensors are respectively located at any three of the four corners of the metering frame.

[0024] Specifically, the zero position sensor may include a two-dimensional position sensitive detector, a collimator and an optical fiber, the optical fiber is connected to the laser, the laser output by the collimator is incident on the bottom surface of the corresponding corner cube, and the two-dimensional position sensitive detector can receive the laser reflected by the corner cube. The two-dimensional position sensitive detector PSD has a PIN photodiode composed of a uniform impedance surface, and the laser spot reflected by the corner cube is irradiated in the measurement area of ​​the PSD.

[0025] The zero position sensor acquisition card is connected to the three zero position sensors respectively, and is connected to a digital signal processor, the digital signal processor is connected to a field programmable gate array, and the field programmable gate array is connected to a host computer.

[0026] The digital signal processor includes a signal processing unit, which is used to process the pre-processed data and solve the six-degree-of-freedom coordinates of the workpiece stage based on the coordinate transformation algorithm. The six-degree-of-freedom coordinates include the three degrees of freedom of translation XYZ and R x R y R z Rotational three degrees of freedom.

[0027] The embodiment of the utility model provides a zero position sensor measurement system for determining the zero position of an interferometer of a lithography machine. Laser measurement is performed between a zero position sensor located on a metrology frame and a conic mirror located on a worktable of the lithography machine. The data collected by the zero position sensor is settled by a digital signal processor to obtain the six-degree-of-freedom displacement of the worktable of the lithography machine, and finally an accurate zero point can be provided for the relative displacement measurement system of the worktable.

[0028] Optionally, the metrology frame is opposite to the workpiece stage of the lithography machine and is arranged above the workpiece stage of the lithography machine.

[0029] Figure 1 Figure 2 shows the schematic diagram of the zero position sensor measurement system. Figure 1 As shown in the figure, the zero position sensor measurement system includes a workbench frame, a measurement frame and a control cabinet. Figure 1 The solid line represents the circuit, and the dotted line represents the optical path.

[0030] The zero position sensor measurement system includes: three zero position sensors, a zero position sensor acquisition card, an FPGA processor and a DSP processor.

[0031] The laser emits laser light, which is reflected by the conic mirror on the workpiece table and finally irradiated on the PSD detector of the zero position sensor. The laser is connected to the optical fibers of the three zero position sensors through the beam splitter. The PSD detector can output four voltage signals, which are related to the positions of the light spots on the PSD. The three sensors measure the positions of the three light spots on the PSD respectively.

[0032] Figure 2 The zero position sensor and the corner cube mirror distribution diagram are shown. Figure 2 2 shows three two-dimensional zero position sensors PSD1 , PSD2 , and PSD3 located on the metrology frame 21 , and three cube corner mirrors 23 corresponding to the workpiece stage 22 .

[0033] The laser outputs 3 laser beams which are distributed to the collimators inside the 3 zero position sensors. The laser beam passes through the collimator and irradiates the corner cube. After being parallelized by the corner cube, it irradiates the 2D PSD. Under the action of the laser spot, the 2D PSD sends out current signals through the four pins X1, X2, Y1, and Y2. After the current signals are converted by IV and amplified, 4 differential voltage signals are output. The 12 voltage signals of the 3 zero position sensors are transmitted to the data acquisition card. After addition, subtraction, and division operations, the x and y coordinates of the 3 sets of light spots on the PSD are obtained.

[0034] The above-mentioned zero position sensor adopts a two-dimensional PSD sensor with high precision and good stability. Figure 1 The solid lines 1, 2, and 3 in the middle indicate that the zero position sensor acquisition card supplies power to the PSD detector, the solid line 4 indicates that the PSD sensor transmits an analog voltage signal to the zero position sensor acquisition card, and the solid line 5 indicates that the zero position sensor acquisition card controls the laser switch.

[0035] The zero-position data acquisition card includes an analog-to-digital AD conversion unit and a signal preprocessing unit. The AD conversion unit uses a high-precision 16-bit analog-to-digital converter. The AD conversion part is used to convert the analog voltage signal of the PSD into a digital signal.

[0036] The signal preprocessing unit is used to preprocess the received data, including data denoising, data normalization, data transformation, etc.; the signal preprocessing unit adopts a variety of data preprocessing algorithms, including Gaussian filtering, normalization processing, wavelet transform, etc.

[0037] The signal processing unit is used to process the pre-processed data, including signal filtering, signal enhancement, signal recognition, etc. The signal processing unit uses a coordinate transformation algorithm to solve a set of six-degree-of-freedom coordinates of the workpiece table through three sets of two-dimensional two-degree-of-freedom PSD coordinates. And, using these six degrees of freedom as the position feedback of the table, the table is controlled to approach the zero position where each degree of freedom is zero. This zero position is the unified zero point of the relative displacement measurement system.

[0038] The clock and synchronization unit is used to ensure the accuracy and synchronization of signal processing. The clock and synchronization unit is used to ensure the synchronization of this data processing module with other subsystems. Exemplarily, the clock and synchronization part adopts high-precision clock synchronization technology, which can ensure the accuracy and synchronization of signal processing.

[0039] The FPGA processor and DSP processor are used to implement different signal processing algorithms. Among them, the FPGA is mainly responsible for communicating with the zero-position data acquisition card and signal preprocessing; the DSP is mainly responsible for running the real-time operating system, achieving a stable servo cycle, realizing raw data calculation in the servo cycle, and outputting the six-degree-of-freedom position of the table. The DSP is also responsible for communicating with the host computer software, which is responsible for displaying raw data and displacement data, and is also responsible for realizing data recording functions and machine constant setting functions. At the same time, the FPGA processor and DSP processor also support online updates and iterations of the algorithm, ensuring the upgradeability and scalability of the data processing module.

[0040] In the embodiment of the utility model, the clock and synchronization unit adopts high-precision clock synchronization technology, which can ensure the synchronization of the data processing module and other subsystems. This technology uses a special clock synchronization bus and combines hardware and software implementation methods to ensure the accuracy and synchronization of data processing.

[0041] An embodiment of the utility model provides a workpiece stage of a photolithography machine, comprising the above-mentioned zero position sensor measurement system.

[0042] Although the utility model is disclosed as above, the utility model is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the utility model. Therefore, the protection scope of the utility model shall be subject to the scope defined by the claims.

[0043] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0044] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0045] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A zero position sensor measurement system, characterized in that: It includes a measurement frame, three zero position sensors and corresponding conic mirrors, a zero position sensor acquisition card, a digital signal processor and a field programmable gate array; The three zero position sensors are fixed at the bottom of the measurement frame, the corresponding corner cubes are fixed on the top surface or side surface of the workpiece table of the lithography machine, and the zero position sensors correspond to the corner cubes one by one; the positions of the three zero position sensors are not in the same straight line; The zero position sensor acquisition card is connected to the three zero position sensors respectively, and is connected to the field programmable gate array, the field programmable gate array is connected to the digital signal processor, and the digital signal processor is connected to the host computer.

2. The zero position sensor measurement system according to claim 1, characterized in that: The three zero position sensors are distributed in a triangle at the bottom of the metering frame.

3. The zero position sensor measurement system according to claim 1, characterized in that: The zero position sensor includes a two-dimensional position sensitive detector, a collimator and an optical fiber. The optical fiber is connected to a laser. The laser output by the collimator is incident on the bottom surface of the corresponding corner cube. The two-dimensional position sensitive detector receives the laser reflected by the corner cube.

4. The zero position sensor measurement system according to claim 3, characterized in that: The working light surface of each of the corner cubes corresponds to the light-sensitive surface of the two-dimensional position sensitive detector of each corresponding zero position sensor at a certain angle.

5. The zero position sensor measurement system according to claim 3, characterized in that: It also includes a laser; the laser is connected to the optical fibers of the three zero position sensors respectively through a light splitting element.

6. The zero position sensor measurement system according to claim 1, characterized in that: The metrology frame is opposite to the workpiece stage of the lithography machine and is arranged above the workpiece stage of the lithography machine.

7. The zero position sensor measurement system according to claim 3, characterized in that: The zero position sensor acquisition card comprises an analog-to-digital conversion unit; the analog-to-digital conversion unit is used to convert the analog voltage signal of the two-dimensional position sensitive detector into a digital signal.

8. The zero position sensor measurement system according to claim 7, characterized in that: The zero position sensor acquisition card also includes a signal preprocessing unit; The signal preprocessing unit is used to preprocess the digital signal, and the preprocessing includes: data denoising, data normalization, and data transformation.

9. The zero position sensor measurement system according to claim 1, characterized in that: The digital signal processor comprises a signal processing unit; The signal processing unit is used to process the preprocessed data and solve the six-degree-of-freedom coordinates of the workpiece platform based on a coordinate transformation algorithm.

10. A workpiece stage of a photolithography machine, characterized in that: A zero position sensor measurement system comprising any one of claims 1-9.

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