Lithography machine alignment method and device and lithography machine

Abstract

The embodiment of the invention provides a photoetching machine alignment method, a photoetching machine alignment device and a photoetching machine, and relates to the technical field of integrated circuit equipment manufacturing. According to the alignment method of the photoetching machine, the gap and the alignment deviation between the wafer and the mask plate are monitored in real time, the real-time gap and the real-time alignment deviation serve as feedback information, and the position of the workpiece table is adjusted through a closed-loop control algorithm, so that errors caused by relative free vibration between the wafer and the mask plate are reduced, and the alignment accuracy of the photoetching machine is improved. And the alignment precision between the wafer and the mask plate is improved. Besides, a plurality of piezoelectric motors are adopted to adjust the movement of the workpiece table in different directions, so that the movement of the workpiece table can be more accurately controlled, and the alignment precision between the wafer and the mask plate is improved.

Description

Technical Field

[0001] The present application relates to the technical field of integrated circuit equipment manufacturing, and more specifically, to a lithography machine alignment method, device and lithography machine. Background Art

[0002] In the integrated circuit manufacturing process, the photolithography process is used to transfer graphic information from the mask to the semiconductor material substrate. The success or failure of the photolithography process directly affects the performance and cost of the final chip. However, in a split-type photolithography machine, since the workpiece table and the main frame are separated, there may be a certain degree of free vibration between the two, resulting in low alignment accuracy between the wafer and the mask. Summary of the invention

[0003] In order to at least overcome the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a lithography machine alignment method, device and lithography machine.

[0004] In a first aspect, an embodiment of the present application provides a method for aligning a lithography machine, the method comprising:

[0005] Placing a wafer and a mask on a work stage and a main frame respectively, and adjusting the work stage until the surface of the wafer is parallel to the surface of the mask, wherein the movement of the work stage in different directions is driven by different piezoelectric motors;

[0006] Detecting in real time the gap between the wafer and the mask and the alignment deviation of the exposure field alignment mark, adjusting the horizontal posture of the workpiece stage based on the alignment deviation, and adjusting the vertical posture of the workpiece stage based on the gap;

[0007] Detect whether the gap and the alignment deviation meet the exposure condition. If the gap and the alignment deviation meet the exposure condition, start the exposure task. If the gap and the alignment deviation do not meet the exposure condition, the exposure task fails to start and the workpiece stage is realigned.

[0008] In a possible implementation, the steps of detecting the gap and alignment deviation between the wafer and the mask in real time, adjusting the horizontal posture of the workpiece stage based on the alignment deviation, and adjusting the vertical posture of the workpiece stage based on the gap include:

[0009] Detecting the alignment deviation between the wafer and the exposure field alignment mark on the mask in real time, and adjusting the control amount of the horizontal piezoelectric motor based on the alignment deviation, so that the workpiece stage is driven by the horizontal piezoelectric motor to move on the plane where the wafer is located, and adjusting the alignment deviation to a preset tolerance range;

[0010] The gap between the wafer and the mask is detected in real time, and the control amount of the vertical piezoelectric motor is adjusted based on the gap. The vertical piezoelectric motor drives the worktable to move in a vertical direction perpendicular to the plane where the wafer is located, so as to adjust the gap to a preset gap range.

[0011] In a possible implementation, the step of detecting the alignment deviation between the wafer and the exposure field alignment mark on the mask in real time, adjusting the control amount of the horizontal piezoelectric motor based on the alignment deviation, and driving the workpiece stage to move on the plane where the wafer is located by the horizontal piezoelectric motor to adjust the alignment deviation to a preset tolerance range includes:

[0012] Detecting a coarse alignment deviation between the wafer and the exposure field alignment mark on the mask, adjusting a control amount of a horizontal piezoelectric motor based on the alignment deviation, and driving the workpiece stage to move in a horizontal direction of the plane where the wafer is located through a coarse moving stage by the horizontal piezoelectric motor to adjust the coarse alignment deviation to within a coarse alignment tolerance range;

[0013] The precise alignment deviation between the wafer and the exposure field alignment mark on the mask is detected in real time, and the control amount of the horizontal piezoelectric motor is adjusted based on the precise alignment deviation. The horizontal piezoelectric motor drives the workpiece stage to move in the horizontal direction of the plane where the wafer is located through the micro-motion stage, and the alignment deviation value is adjusted to a preset tolerance range.

[0014] In a possible implementation, the step of detecting the gap between the wafer and the mask in real time, adjusting the control amount of the vertical piezoelectric motor based on the gap, and driving the workpiece stage to move in a vertical direction perpendicular to the plane where the wafer is located by the vertical piezoelectric motor to adjust the gap to a preset gap range includes:

[0015] The real-time gap between the wafer and the mask is detected in real time, and the step control amount of the vertical piezoelectric motor is linearly adjusted based on the real-time gap. The vertical piezoelectric motor drives the workpiece table to move in a direction perpendicular to the plane where the wafer is located through the micro-motion table, and the gap is adjusted to a preset gap range, wherein the step control amount of the vertical piezoelectric motor decreases as the real-time gap decreases.

[0016] In a possible implementation, the step of detecting whether the gap and the alignment deviation meet the exposure condition, and starting the exposure task if the gap and the alignment deviation meet the exposure condition, and failing to start the exposure task and re-adjusting the workpiece stage if the gap and the alignment deviation do not meet the exposure condition, includes:

[0017] Detecting whether the phase difference of the alignment deviation is within a moiré fringe period range, and if the phase difference of the alignment deviation is not within a moiré fringe period range, determining that the exposure task startup fails;

[0018] Based on the alignment deviation, determine whether the wafer and the mask are in close contact with each other, and if the wafer and the mask are in close contact with each other, determine that the exposure task fails to start;

[0019] Determine whether the gap is within the exposure gap range and whether the alignment deviation is within the exposure tolerance range. If the gap is not within the exposeable gap range and / or the alignment deviation value is not within the exposure tolerance range, determine that the exposure task has failed to start, and realign the workpiece stage.

[0020] In a possible implementation, the step of determining whether the alignment deviation is within a cycle range includes:

[0021] Detect whether the phase difference of the moiré fringes generated by the alignment mark during the alignment process of the wafer and the mask is within a period range. If the phase difference of the moiré fringes is within a period range, detect whether the wafer and the mask are tightly attached. If the phase difference of the moiré fringes is not within a period range, determine that the exposure task fails to start.

[0022] In a possible implementation, the step of judging whether the wafer and the mask are in close contact based on the alignment deviation includes:

[0023] Within a preset time, the alignment deviation values ​​of the exposure field alignment marks on the wafer and the mask are periodically detected. If the alignment deviation values ​​within the preset time are equal, it is determined that the wafer and the mask are in close contact.

[0024] In a second aspect, an embodiment of the present application further provides a lithography machine alignment device, the device comprising:

[0025] A placement module, used to place a wafer and a mask on a work stage and a main frame respectively, and to adjust the work stage until the surface of the wafer is parallel to the surface of the mask, wherein the movement of the work stage in different directions is driven by different piezoelectric motors;

[0026] An adjustment module, used for detecting in real time the gap between the wafer and the mask and the alignment deviation of the exposure field alignment mark, adjusting the horizontal posture of the workpiece stage based on the alignment deviation, and adjusting the vertical posture of the workpiece stage based on the gap;

[0027] The detection module is used to detect whether the gap and the alignment deviation meet the exposure conditions. If the gap and the alignment deviation meet the exposure conditions, the exposure task is started; if the gap and the alignment deviation do not meet the exposure conditions, the exposure task fails to start and the workpiece stage is realigned.

[0028] In a possible implementation manner, the adjustment module is specifically used to:

[0029] Detecting the alignment deviation between the wafer and the exposure field alignment mark on the mask in real time, and adjusting the control amount of the horizontal piezoelectric motor based on the alignment deviation, so that the workpiece stage is driven by the horizontal piezoelectric motor to move on the plane where the wafer is located, and adjusting the alignment deviation to a preset tolerance range;

[0030] The gap between the wafer and the mask is detected in real time, and the control amount of the vertical piezoelectric motor is adjusted based on the gap. The vertical piezoelectric motor drives the worktable to move in a vertical direction perpendicular to the plane where the wafer is located, so as to adjust the gap to a preset gap range.

[0031] In a second aspect, an embodiment of the present application further provides a lithography machine, comprising an embedded control system, wherein the embedded control system is used to execute the method described in any one of the first aspects.

[0032] Based on any of the above aspects, the lithography machine alignment method, lithography machine alignment device and lithography machine provided in the embodiments of the present application detect the gap between the wafer and the mask and the alignment deviation of the alignment mark in real time, and use the real-time gap and real-time alignment deviation as feedback information, and control the coarse motion stage and fine motion stage movement of the workpiece stage to adjust the posture of the workpiece stage, thereby gradually reducing the gap between the wafer and the mask and the alignment deviation of the alignment mark, and start the exposure program at the time point when the exposure conditions are met, so as to improve the overlay alignment accuracy of the proximity lithography machine. In addition, by using multiple high-precision piezoelectric motors to dynamically adjust the posture of the workpiece stage in the horizontal and vertical directions, the posture of the workpiece stage can be controlled more accurately, and the overlay alignment accuracy of the exposure field between the wafer and the mask can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 A schematic diagram of a process flow of a photolithography machine alignment method provided in an embodiment of the present application;

[0035] Figure 2 It is a placement diagram in a specific use process;

[0036] Figure 3 for Figure 1 Schematic diagram of the sub-step flow chart of step S120;

[0037] Figure 4 for Figure 1 Schematic diagram of the sub-step flow chart of step S130;

[0038] Figure 5 Functional module diagram of the lithography machine for aligning and loading paper provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0041] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0042] In the description of this application, it should be noted that the terms "upper", "lower", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0043] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] It should be noted that the alignment deviation between the wafer and the mask actually refers to the alignment deviation between the wafer and the alignment marks of the exposure field on the mask.

[0045] It should be noted that, in the absence of conflict, different features in the embodiments of the present application may be combined with each other.

[0046] Combine the following Figure 1 The flow chart shown in the figure is used to exemplarily illustrate the alignment method of the photolithography machine provided in the embodiment of the present application. Figure 1 The detailed steps of the lithography machine alignment method provided in the embodiment of the present application are introduced as follows.

[0047] Step S110: placing the wafer and the mask on the work stage and the main frame respectively, and adjusting the work stage until the surface of the wafer is parallel to the surface of the mask.

[0048] Please refer to Figure 2 , the wafer 120 and the mask 130 can be placed on the work stage 110 and the main frame respectively, and the wafer 120 and the mask 130 are provided with an alignment mark A of the exposure field, and the movement of the work stage 110 in different directions is driven by a plurality of different piezoelectric motors. Specifically, the work stage 110 may include a horizontal piezoelectric motor (X / Y1 / Y2) and a vertical piezoelectric motor (Z1 / Z2 / Z3), and the horizontal piezoelectric motor can adjust the horizontal posture of the work stage 110 (i.e., the degree of freedom X / Y / Rz), and the vertical piezoelectric motor can adjust the vertical posture of the work stage 110 (i.e., the degree of freedom Z / Rx / Ry). In this step, the vertical piezoelectric motor (Z1 / Z2 / Z3) can be used to adjust the movement of the work stage in the Z / Rx / Ry direction.

[0049] Step S120: Detect the gap and alignment deviation between the wafer and the mask in real time, adjust the horizontal posture of the workpiece stage based on the alignment deviation, and adjust the vertical posture of the workpiece stage based on the gap.

[0050] In this step, based on the real-time detection of the alignment deviation (ΔX / ΔY / Δθz) between the alignment marks on the wafer and the mask, the horizontal posture of the work stage (i.e., the degree of freedom X / Y / Rz) is adjusted until the alignment marks of the exposure field between the wafer and the mask are aligned and overlapped in the horizontal direction. The horizontal posture of the work stage (i.e., the degree of freedom X / Y / Rz) is finely adjusted by the horizontal piezoelectric motor (X / Y1 / Y2) pushing the work stage to move in the X / Y / Rz direction.

[0051] Step S130: Detect whether the gap and the alignment deviation meet the exposure conditions. If the gap and the alignment deviation meet the exposure conditions, start the exposure task. If the gap and the alignment deviation do not meet the exposure conditions, the exposure task fails to start and the workpiece stage is realigned.

[0052] In this step, if the real-time gap and alignment deviation between the wafer and the mask meet the exposure conditions (i.e., the gap is less than the preset gap, and the alignment deviation is less than the preset alignment deviation), the exposure task is started; if the real-time gap and alignment deviation between the wafer and the mask do not meet the exposure conditions (i.e., the real-time gap is greater than or equal to the preset gap, and the alignment deviation is greater than or equal to the preset alignment deviation), and the workpiece stage cannot be moved, the exposure task fails to start and the workpiece stage needs to be recalibrated.

[0053] In this embodiment, by detecting the gap between the wafer and the mask and the alignment deviation of the alignment mark in real time, and using the real-time gap and real-time alignment deviation as feedback information, the coarse and fine motion stages of the workpiece stage are controlled to adjust the posture of the workpiece stage, thereby gradually reducing the gap between the wafer and the mask and the alignment deviation of the alignment mark, and starting the exposure program at the time point when the exposure conditions are met, so as to improve the overlay alignment accuracy of the proximity lithography machine. In addition, by using multiple high-precision piezoelectric motors to dynamically adjust the posture of the workpiece stage in the horizontal and vertical directions, the posture of the workpiece stage can be controlled more accurately, and the overlay alignment accuracy of the exposure field between the wafer and the mask can be improved.

[0054] For further information, please refer to Figure 3 , step S120 can be implemented by the following method.

[0055] Step S121: Detect the alignment deviation between the wafer and the mask in real time, and adjust the control amount of the horizontal piezoelectric motor based on the alignment deviation, so that the horizontal piezoelectric motor drives the worktable to move on the plane where the wafer is located, and adjusts the alignment deviation to a preset tolerance range.

[0056] In this step, the coarse alignment deviation between the wafer and the mask can be detected first, and the control amount of the horizontal piezoelectric motor can be adjusted based on the coarse alignment deviation, and the horizontal piezoelectric motor can drive the worktable to move in the horizontal direction of the plane where the wafer is located, and the coarse alignment deviation can be adjusted to within the coarse alignment tolerance range. Specifically, the horizontal piezoelectric motor includes a worktable coarse motion motor and a worktable micro-motion motor, and the step amount of the worktable coarse motion motor is greater than the step amount of the worktable micro-motion motor. The control amount of the worktable coarse motion motor can be adjusted based on the coarse alignment deviation, and the coarse motion motor can drive the worktable to move in the horizontal direction of the plane where the wafer is located, and the coarse alignment deviation can be adjusted to within the coarse alignment tolerance range. Exemplarily, the coarse alignment tolerance range can be 450nm to 550nm.

[0057] Next, the fine alignment deviation between the wafer and the mask is detected in real time, and the control amount of the horizontal piezoelectric motor is adjusted based on the fine alignment deviation. The horizontal piezoelectric motor drives the worktable to move in the horizontal direction of the plane where the wafer is located, and the alignment deviation value is adjusted to a preset tolerance range. Specifically, the control amount of the worktable micro-motor can be adjusted based on the fine alignment deviation. The worktable micro-motor drives the worktable to move in the horizontal direction of the plane where the wafer is located, and the alignment deviation value is adjusted to a preset tolerance range.

[0058] In this step, the workpiece stage coarse motion motor drives the workpiece stage to perform coarse alignment adjustment, which can quickly narrow the range of the workpiece stage alignment adjustment and improve the alignment efficiency. Then the workpiece stage micro motion motor drives the workpiece stage to perform fine alignment adjustment, which can finely adjust the position of the workpiece stage, reduce the relative free vibration between the wafer and the mask, and improve the alignment accuracy between the wafer and the mask.

[0059] Step S122: Detect the gap between the wafer and the mask in real time, adjust the control amount of the vertical piezoelectric motor based on the gap, and drive the worktable to move in a vertical direction perpendicular to the plane where the wafer is located by the vertical piezoelectric motor to adjust the gap to a preset gap range.

[0060] Specifically, the real-time gap between the wafer and the mask can be detected in real time, and the step control amount of the vertical piezoelectric motor can be adjusted linearly based on the real-time gap. The vertical piezoelectric motor drives the worktable to move in a vertical direction perpendicular to the plane where the wafer is located, and adjusts the gap to a preset gap range, wherein the step control amount of the vertical piezoelectric motor decreases as the real-time gap decreases. Specifically, the vertical piezoelectric motor can first perform a relatively large stepping motion, adjust the worktable to a range close to the preset gap range, and then adjust the stepping motion of the worktable slightly, that is, use the real-time gap between the wafer and the mask as feedback information to gradually reduce the control amount of the vertical piezoelectric motor to prevent the wafer from being damaged during the adjustment process.

[0061] In this embodiment, by real-time monitoring of the gap and alignment deviation between the wafer and the mask and adjusting the control amount of the horizontal piezoelectric motor and the vertical piezoelectric motor, the horizontal and vertical postures of the worktable can be adjusted in real time, thereby reducing the error between the wafer and the mask caused by relative free vibration and improving the alignment accuracy between the wafer and the mask.

[0062] For further information, please refer to Figure 4 , step S130 can be implemented by the following method.

[0063] Step S131: Detect whether the phase difference of the alignment deviation is within a moiré fringe period range. If the phase difference of the alignment deviation is not within a moiré fringe period range, determine that the exposure task startup fails.

[0064] In this step, it is possible to detect whether the phase difference of the moiré fringes generated by the alignment mark during the wafer and mask alignment process is within a period range. If the phase difference of the moiré fringes is within a period range, it is detected whether the wafer and the mask are in close contact. If the phase difference of the moiré fringes is not within a period range, it is determined that the exposure task has failed to start. By detecting whether the phase difference of the moiré fringes is within a period range, it is possible to determine whether the wafer and the mask are correctly aligned, thereby ensuring that the pattern can be transferred to the wafer with high precision during the exposure process.

[0065] Step S132: judging whether the wafer and the mask are in close contact based on the alignment deviation; if the wafer and the mask are in close contact, judging that the exposure task fails to start.

[0066] In this step, since the machine has inevitable vibrations during movement, the alignment deviation between the wafer and the mask cannot be constant, so whether the wafer and the mask are in close contact can be judged by whether the alignment deviation fluctuates. Specifically, the alignment deviation value between the wafer and the mask can be periodically detected within a preset time. If the alignment deviation values ​​within the preset time are equal, it is judged that the wafer and the mask are in close contact, and it will be further judged whether the gap is within the exposure gap range and whether the alignment deviation is within the exposure tolerance range. If the gap is not within the exposable gap range, or the alignment deviation value is not within the exposure tolerance range, it is judged that the exposure task fails to start, and the workpiece stage is realigned. Exemplarily, the alignment deviation value between the wafer and the mask can be detected three times in a row. If the alignment deviation values ​​are equal for three consecutive times, it is judged that the wafer and the mask are in close contact.

[0067] It should be noted that in the photolithography process, the wafer and the mask need to maintain a certain attachment relationship, but not completely close. When the wafer and the mask are too close, it may not only cause focusing failure, but also damage the wafer.

[0068] Step S133: Determine whether the gap is within the exposure gap range and whether the alignment deviation is within the exposure tolerance range. If the gap is not within the exposure gap range and / or the alignment deviation value is not within the exposure tolerance range, determine that the exposure task fails to start and realign the workpiece stage.

[0069] In this step, when the gap between the wafer and the mask is less than 16.5nm (it should be noted that this value is related to the height of the bosses around the graphic area on the mask), and the alignment deviation between the wafer and the mask is less than 20nm, it can be judged that the wafer and the mask meet the exposure conditions at this time; otherwise, it is judged that the exposure task fails to start and the worktable must be realigned.

[0070] In this embodiment, whether the exposure conditions are met is automatically detected based on the real-time gap and alignment deviation between the wafer and the mask. When the exposure is judged to have failed, the workpiece stage can be recalibrated, which can reduce manual intervention and improve production efficiency.

[0071] Based on the same inventive concept, the present application also provides a photolithography machine alignment device, please refer to Figure 5 , Figure 5 A schematic diagram of a functional module of a photolithography machine alignment device provided in an embodiment of the present application. The present application embodiment can divide the functional modules of the photolithography machine alignment device 200 according to the method embodiment executed by the computer device, that is, the following functional modules corresponding to the photolithography machine alignment device 200 can be used to execute the above-mentioned method embodiments. Among them, the photolithography machine alignment device 200 may include a placement module, an adjustment module, and a detection module. The functions of each functional module of the photolithography machine alignment device 200 are described in detail below.

[0072] The placement module is used to place the wafer and the mask on the worktable and the main frame respectively, and adjust the worktable until the surface of the wafer is parallel to the surface of the mask.

[0073] Please refer again Figure 2 , the wafer 120 and the mask 130 can be placed on the work stage 110 and the main frame respectively, and the wafer 120 and the mask 130 are provided with an alignment mark A of the exposure field, and the movement of the work stage 110 in different directions is driven by a plurality of different piezoelectric motors. Specifically, the work stage 110 may include a horizontal piezoelectric motor (X / Y1 / Y2) and a vertical piezoelectric motor (Z1 / Z2 / Z3), and the horizontal piezoelectric motor can adjust the horizontal posture of the work stage 110 (i.e., the degree of freedom X / Y / Rz), and the vertical piezoelectric motor can adjust the vertical posture of the work stage 110 (i.e., the degree of freedom Z / Rx / Ry). In this step, the vertical piezoelectric motor (Z1 / Z2 / Z3) can be used to adjust the movement of the work stage in the Z / Rx / Ry direction.

[0074] In this embodiment, the placement module may be used to execute the above step S110. The detailed implementation of the placement module may refer to the above detailed description of step S110.

[0075] The adjustment module is used to detect the gap and alignment deviation between the wafer and the mask in real time, adjust the horizontal posture of the workpiece stage based on the alignment deviation, and adjust the vertical posture of the workpiece stage based on the gap.

[0076] Based on the real-time detection of the alignment deviation (ΔX / ΔY / Δθz) between the wafer and the alignment mark on the mask, the horizontal posture of the work stage (i.e., the degree of freedom X / Y / Rz) is adjusted until the wafer is aligned with the alignment mark between the mask in the horizontal direction. The horizontal posture of the work stage (i.e., the degree of freedom X / Y / Rz) is finely adjusted by the horizontal piezoelectric motor (X / Y1 / Y2) pushing the work stage to move in the X / Y / Rz direction.

[0077] In this embodiment, the adjustment module may be used to execute the above step S120. For the detailed implementation of the adjustment module, reference may be made to the above detailed description of step S120.

[0078] The detection module is used to detect whether the gap and the alignment deviation meet the exposure conditions. If the gap and the alignment deviation meet the exposure conditions, the exposure task is started; if the gap and the alignment deviation do not meet the exposure conditions, the exposure task fails to start and the workpiece stage is realigned.

[0079] If the real-time gap and alignment deviation between the wafer and the mask meet the exposure conditions (i.e., the gap is less than the preset gap, and the alignment deviation is less than the preset alignment deviation), the exposure task is started; if the real-time gap and alignment deviation between the wafer and the mask do not meet the exposure conditions (i.e., the real-time gap is greater than or equal to the preset gap, and the alignment deviation is greater than or equal to the preset alignment deviation), and the workpiece stage cannot be moved, the exposure task fails to start and the workpiece stage needs to be recalibrated.

[0080] In this embodiment, the detection module can be used to execute the above step S130. The detailed implementation of the detection module can refer to the above detailed description of step S130.

[0081] In this embodiment, the adjustment module monitors the gap and alignment deviation between the wafer and the mask in real time, and uses the real-time gap and real-time alignment deviation as feedback information to adjust the position of the workpiece stage through a closed-loop control algorithm to reduce the error caused by the relative free vibration between the wafer and the mask, thereby improving the alignment accuracy between the wafer and the mask. In addition, multiple piezoelectric motors are used to adjust the movement of the workpiece stage in different directions, so that the movement of the workpiece stage can be more accurately controlled, thereby improving the alignment accuracy between the wafer and the mask.

[0082] Furthermore, the adjustment module can also be used to implement the following functions.

[0083] The alignment deviation between the wafer and the mask is monitored in real time, and the control amount of the horizontal piezoelectric motor is adjusted based on the alignment deviation. The horizontal piezoelectric motor drives the worktable to move on the plane where the wafer is located, and the alignment deviation is adjusted to a preset tolerance range. Specifically, the horizontal piezoelectric motor includes a worktable coarse motion motor and a worktable fine motion motor. The step amount of the worktable coarse motion motor is greater than the step amount of the worktable fine motion motor. The control amount of the worktable coarse motion motor can be adjusted based on the coarse alignment deviation. The coarse motion motor drives the worktable to move in the horizontal direction of the plane where the wafer is located, and the coarse alignment deviation is adjusted to within the coarse alignment tolerance range. Exemplarily, the coarse alignment tolerance range can be 450nm to 550nm.

[0084] Next, the fine alignment deviation between the wafer and the mask is detected in real time, and the control amount of the horizontal piezoelectric motor is adjusted based on the fine alignment deviation. The horizontal piezoelectric motor drives the worktable to move in the horizontal direction of the plane where the wafer is located, and the alignment deviation value is adjusted to a preset tolerance range. Specifically, the control amount of the worktable micro-motor can be adjusted based on the fine alignment deviation. The worktable micro-motor drives the worktable to move in the horizontal direction of the plane where the wafer is located, and the alignment deviation value is adjusted to a preset tolerance range.

[0085] The gap between the wafer and the mask is detected in real time, and the control amount of the vertical piezoelectric motor is adjusted based on the gap, and the vertical piezoelectric motor drives the workpiece stage to move in a vertical direction perpendicular to the plane where the wafer is located, and the gap is adjusted to a preset gap range, wherein the direction of the vertical piezoelectric motor is perpendicular to the plane where the wafer is located. Specifically, the real-time gap between the wafer and the mask can be detected in real time, and the step control amount of the vertical piezoelectric motor is linearly adjusted based on the real-time gap, and the vertical piezoelectric motor drives the workpiece stage to move in a direction perpendicular to the plane where the wafer is located, and the gap is adjusted to a preset gap range, wherein the step control amount of the vertical piezoelectric motor decreases as the real-time gap decreases.

[0086] The embodiment of the present application also provides a lithography machine, including an embedded real-time control system, which is used to execute any one of the methods in the above embodiments, by real-time monitoring of the gap and alignment deviation between the wafer and the mask, and using the real-time gap and real-time alignment deviation as feedback information, and adjusting the position of the workpiece stage through a closed-loop control algorithm to reduce the error caused by the relative free vibration between the wafer and the mask, and improve the alignment accuracy between the wafer and the mask. In addition, the use of a workpiece stage coarse motion motor and a workpiece stage fine motion motor to adjust the movement of the workpiece stage in the horizontal direction can more accurately control the movement of the workpiece stage and improve the alignment accuracy between the wafer and the mask.

[0087] In summary, the embodiments of the present application provide a method for aligning a photolithography machine, a device for aligning a photolithography machine, and a photolithography machine, which monitor the gap and alignment deviation between the wafer and the mask in real time, and use the real-time gap and real-time alignment deviation as feedback information, and adjust the position of the worktable through a closed-loop control algorithm to reduce the error caused by the relative free vibration between the wafer and the mask, thereby improving the alignment accuracy between the wafer and the mask. In addition, by using multiple piezoelectric motors to adjust the movement of the worktable in different directions, the movement of the worktable can be more accurately controlled, thereby improving the alignment accuracy between the wafer and the mask.

[0088] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for aligning a photolithography machine, characterized in that: The method comprises: Placing a wafer and a mask on a work stage and a main frame respectively, and adjusting the work stage until the surface of the wafer is parallel to the surface of the mask, wherein the movement of the work stage in different directions is driven by different piezoelectric motors; Detecting in real time the gap between the wafer and the mask and the alignment deviation of the exposure field alignment mark, adjusting the horizontal posture of the workpiece stage based on the alignment deviation, and adjusting the vertical posture of the workpiece stage based on the gap; Detect whether the gap and the alignment deviation meet the exposure condition. If the gap and the alignment deviation meet the exposure condition, start the exposure task. If the gap and the alignment deviation do not meet the exposure condition, the exposure task fails to start and the workpiece stage is realigned.

2. The method for aligning a photolithography machine according to claim 1, characterized in that: The steps of detecting the gap and alignment deviation between the wafer and the mask in real time, adjusting the horizontal posture of the workpiece stage based on the alignment deviation, and adjusting the vertical posture of the workpiece stage based on the gap include: Detecting the alignment deviation between the wafer and the exposure field alignment mark on the mask in real time, and adjusting the control amount of the horizontal piezoelectric motor based on the alignment deviation, so that the workpiece stage is driven by the horizontal piezoelectric motor to move on the plane where the wafer is located, and adjusting the alignment deviation to a preset tolerance range; The gap between the wafer and the mask is detected in real time, and the control amount of the vertical piezoelectric motor is adjusted based on the gap. The vertical piezoelectric motor drives the worktable to move in a vertical direction perpendicular to the plane where the wafer is located, so as to adjust the gap to a preset gap range.

3. The method for aligning a photolithography machine according to claim 2, characterized in that: The step of detecting the alignment deviation between the wafer and the exposure field alignment mark on the mask in real time, adjusting the control amount of the horizontal piezoelectric motor based on the alignment deviation, and driving the worktable to move on the plane where the wafer is located by the horizontal piezoelectric motor to adjust the alignment deviation to a preset tolerance range includes: Detecting a coarse alignment deviation between the wafer and the exposure field alignment mark on the mask, adjusting a control amount of a horizontal piezoelectric motor based on the alignment deviation, and driving the workpiece stage to move in a horizontal direction of the plane where the wafer is located through a coarse moving stage by the horizontal piezoelectric motor to adjust the coarse alignment deviation to within a coarse alignment tolerance range; The precise alignment deviation between the wafer and the exposure field alignment mark on the mask is detected in real time, and the control amount of the horizontal piezoelectric motor is adjusted based on the precise alignment deviation. The horizontal piezoelectric motor drives the workpiece stage to move in the horizontal direction of the plane where the wafer is located through the micro-motion stage, and the alignment deviation value is adjusted to a preset tolerance range.

4. The method for aligning a photolithography machine according to claim 2, characterized in that: The step of detecting the gap between the wafer and the mask in real time, adjusting the control amount of the vertical piezoelectric motor based on the gap, and driving the workpiece stage to move in a vertical direction perpendicular to the plane where the wafer is located by the vertical piezoelectric motor to adjust the gap to a preset gap range includes: The real-time gap between the wafer and the mask is detected in real time, and the step control amount of the vertical piezoelectric motor is linearly adjusted based on the real-time gap. The vertical piezoelectric motor drives the workpiece table to move in a direction perpendicular to the plane where the wafer is located through the micro-motion table, and the gap is adjusted to a preset gap range, wherein the step control amount of the vertical piezoelectric motor decreases as the real-time gap decreases.

5. The method for aligning a photolithography machine according to claim 1, characterized in that: The step of detecting whether the gap and the alignment deviation meet the exposure condition, starting the exposure task if the gap and the alignment deviation meet the exposure condition, and failing to start the exposure task if the gap and the alignment deviation do not meet the exposure condition, and re-adjusting the workpiece stage includes: Detecting whether the phase difference of the alignment deviation is within a moiré fringe period range, and if the phase difference of the alignment deviation is not within a moiré fringe period range, determining that the exposure task startup fails; Based on the alignment deviation, determine whether the wafer and the mask are in close contact with each other, and if the wafer and the mask are in close contact with each other, determine that the exposure task fails to start; Determine whether the gap is within the exposure gap range and whether the alignment deviation is within the exposure tolerance range. If the gap is not within the exposeable gap range and / or the alignment deviation value is not within the exposure tolerance range, determine that the exposure task has failed to start, and realign the workpiece stage.

6. The method for aligning a photolithography machine according to claim 5, characterized in that: The step of determining whether the alignment deviation is within a period range comprises: Detect whether the phase difference of the moiré fringes generated by the alignment mark during the alignment process of the wafer and the mask is within a period range. If the phase difference of the moiré fringes is within a period range, detect whether the wafer and the mask are tightly attached. If the phase difference of the moiré fringes is not within a period range, determine that the exposure task fails to start.

7. The method for aligning a photolithography machine according to claim 5, characterized in that: The step of judging whether the wafer and the mask are in close contact based on the alignment deviation comprises: Within a preset time, the alignment deviation values ​​of the exposure field alignment marks on the wafer and the mask are periodically detected. If the alignment deviation values ​​within the preset time are equal, it is determined that the wafer and the mask are in close contact.

8. A photolithography machine alignment device, characterized in that: The device comprises: A placement module, used to place a wafer and a mask on a work stage and a main frame respectively, and to adjust the work stage until the surface of the wafer is parallel to the surface of the mask, wherein the movement of the work stage in different directions is driven by different piezoelectric motors; An adjustment module, used for detecting in real time the gap between the wafer and the mask and the alignment deviation of the exposure field alignment mark, adjusting the horizontal posture of the workpiece stage based on the alignment deviation, and adjusting the vertical posture of the workpiece stage based on the gap; The detection module is used to detect whether the gap and the alignment deviation meet the exposure conditions. If the gap and the alignment deviation meet the exposure conditions, the exposure task is started; if the gap and the alignment deviation do not meet the exposure conditions, the exposure task fails to start and the workpiece stage is realigned.

9. The aligning device for a photolithography machine according to claim 8, characterized in that: The adjustment module is specifically used for: Detecting the alignment deviation between the wafer and the exposure field alignment mark on the mask in real time, and adjusting the control amount of the horizontal piezoelectric motor based on the alignment deviation, so that the workpiece stage is driven by the horizontal piezoelectric motor to move on the plane where the wafer is located, and adjusting the alignment deviation to a preset tolerance range; The gap between the wafer and the mask is detected in real time, and the control amount of the vertical piezoelectric motor is adjusted based on the gap. The vertical piezoelectric motor drives the worktable to move in a vertical direction perpendicular to the plane where the wafer is located, so as to adjust the gap to a preset gap range.

10. A photolithography machine, characterized in that: It comprises an embedded control system, wherein the embedded control system is used to execute the method described in any one of claims 1-8.

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