Mask, mask heat effect analysis and compensation method and device and photoetching system

Abstract

The invention relates to a mask, a mask heat effect analysis and compensation method and device, a photoetching system and computer equipment. The mask comprises a mask body, a rigid frame and a stress adjusting module. A mask pattern is arranged on the mask plate body. The rigid frame is located on the periphery of the mask body. The stress adjusting module is located between the mask plate body and the rigid frame and comprises a plurality of stress adjusting structures arranged along at least one side edge of the mask plate body. According to the invention, the overlay precision of the photoetching system can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of photolithography technology, and in particular to a photomask, a method and apparatus for analyzing and compensating the thermal effects of a photomask, a photolithography system, and computer equipment. Background Technology

[0002] In integrated circuit photolithography, the intermittent illumination of the photolithography system's light source on the mask during the wafer exposure cycle causes severe thermal effects on the mask. These thermal effects lead to the mask's expansion and contraction, affecting the overlay accuracy between the imaged pattern and the previous layer, and consequently impacting device performance. Summary of the Invention

[0003] Based on this, it is necessary to provide a mask, a method and apparatus for analyzing and compensating thermal effects of the mask, a lithography system, and computer equipment that can improve the overlay accuracy of the lithography system, in response to the above-mentioned technical problems.

[0004] A mask, comprising:

[0005] A mask version body, wherein a mask pattern is provided on the mask version body;

[0006] A rigid frame is located on the periphery of the mask version body;

[0007] A stress adjustment module is located between the mask version body and the rigid frame, and includes a plurality of stress adjustment structures arranged along at least one side of the mask version body.

[0008] In one embodiment, the stress-adjusting structure includes a piezoelectric structure.

[0009] In one embodiment, the piezoelectric structure includes a piezoelectric actuator.

[0010] In one embodiment,

[0011] The mask body includes two first sides extending along a first direction and two second sides extending along a second direction. The first direction intersects the second direction, and the second direction is the light source scanning direction when the photolithography system performs exposure based on the mask.

[0012] The stress adjustment module includes a plurality of stress adjustment structures arranged along at least one of the first sides.

[0013] In one embodiment, the rigid frame surrounds the mask version body.

[0014] In the aforementioned photomask, a rigid frame, less susceptible to deformation due to thermal effects, is positioned around the outer periphery of the photomask body. A stress adjustment module is then positioned between the two. Therefore, the force generated by the stress adjustment module effectively acts on the photomask body, thus offsetting the stress generated by thermal effects during exposure. Furthermore, the deformation correction requirements may differ at different locations on the photomask body. Therefore, arranging multiple stress adjustment structures on the same side of the photomask body allows for different stress compensations at different locations during exposure. This enables stress compensation based on the deformation correction requirements at each location. Thus, this application can effectively compensate for the deformation of the photomask body caused by exposure thermal effects, thereby improving the overlay accuracy of the lithography system.

[0015] A method for analyzing and compensating for thermal effects of photomasks, comprising:

[0016] Obtain n sets of data by continuously exposing n test wafers using the mask described in any of the above claims, wherein when continuously exposing n test wafers, the stress adjustment module of the mask is not stressed, and a set of measurement data is obtained for each pair of test wafers exposed. Each set of data includes measurement data of several exposure fields on the wafer. The measurement data of each exposure field includes overlay error data measured by several pairs of overlay marks. The overlay error data measured by each pair of overlay marks includes overlay error measurement values ​​of a first preset direction and a second preset direction. The second preset direction intersects with the first preset direction, and n is a positive integer greater than 1.

[0017] Based on the n sets of overlay error measurement data, solve the 3rd or higher order polynomial model of the i-th set of data in the exposure field, obtain the correspondence between the overlay error caused by the thermal effect of the mask and a specific term of the polynomial when the i-th wafer is exposed based on the mask, and the correspondence between the deformation of the mask body in the second preset direction and the position in the first preset direction, 1≤i≤n;

[0018] According to the correspondence, when exposing the i-th wafer based on the mask, the deformation of the mask at different target positions in the first preset direction along the second preset direction is obtained, and the stress adjustment structure is provided at the target position;

[0019] Based on the deformation along the second preset direction at different target positions in the first preset direction, the adjustment parameter values ​​of the stress adjustment structure at different target positions in the first preset direction are obtained when the i-th wafer is exposed based on the mask.

[0020] In one embodiment, the first preset direction intersects with the light source scanning direction when the lithography system exposes the mask.

[0021] In one embodiment, the stress adjustment structure includes a piezoelectric structure, and the adjustment parameter value includes the voltage signal value of the piezoelectric structure.

[0022] The step of obtaining adjustment parameter values ​​of the stress adjustment structure at different target positions in the first preset direction based on the deformation along the second preset direction at different target positions in the first preset direction, when exposing the i-th wafer based on the mask, includes:

[0023] Based on the deformation along the second preset direction at different target positions in the first preset direction, obtain the stress compensation value corresponding to different target positions in the first preset direction when exposing the i-th wafer based on the mask.

[0024] Based on the stress compensation value, the voltage signal values ​​of the piezoelectric structures at different target positions of the mask in the first preset direction are obtained.

[0025] In one embodiment, based on the deformation along the second preset direction at different target positions in the first preset direction, when exposing the i-th wafer based on the mask, the stress compensation value corresponding to the different target positions in the first preset direction is obtained, including:

[0026] Establish a mechanical simulation analysis model for the aforementioned mask;

[0027] Based on the target deformation at different target positions in the first preset direction and the mechanical simulation analysis model, the stress compensation value corresponding to different target positions in the first preset direction is obtained when the i-th wafer is exposed based on the mask.

[0028] The aforementioned mask thermal effect analysis and compensation method obtains a mathematical model of the mask thermal effect through overlay error data. It then establishes the correspondence between the deformation in the second preset direction and the position in the first preset direction of the mask body during exposure of the i-th wafer based on the mask. Based on this correspondence, it obtains the target deformation at different target positions in the first preset direction where stress adjustment structures are located, and obtains the adjustment parameter values ​​of the stress adjustment structures based on the target deformation. Therefore, when exposing each wafer in a multi-wafer array based on the mask, the stress adjustment structures can be controlled according to their adjustment parameter values, thereby effectively compensating for the deformation in the second preset direction.

[0029] A photolithography system, comprising:

[0030] Exposure apparatus;

[0031] Masks as described in any of the above;

[0032] A mask thermal effect analysis and compensation device is used to obtain, according to any one of the above methods, the adjustment parameter values ​​of the stress adjustment structure at different target positions in the first preset direction when exposing the i-th wafer based on the mask;

[0033] A control device, electrically connected to the mask thermal effect analysis and compensation device and the exposure device, is used to control the stress adjustment structure at different target positions in the first preset direction of the mask to perform stress compensation on the mask body according to the adjustment parameter value when the exposure device is performing exposure.

[0034] In one embodiment, the stress adjustment structure includes a piezoelectric structure, the adjustment parameter value includes the voltage signal value of the piezoelectric structure, and the control device applies voltage to the corresponding piezoelectric structure according to the voltage signal value of the piezoelectric structure at different target positions of the mask in the first preset direction.

[0035] In one embodiment, the device includes:

[0036] The first acquisition module is used to acquire n sets of data obtained by continuously exposing n test wafers using the mask described in any of the above claims, wherein when continuously exposing n test wafers, the stress adjustment module of the mask is not stressed, and a set of data is acquired for each pair of test wafers exposed, each set of data includes measurement data of several exposure fields on the wafer, the measurement data of each exposure field includes overlay error data measured by several pairs of overlay marks, the overlay error data measured by each pair of overlay marks includes overlay error measurement values ​​of a first preset direction and a second preset direction, the second preset direction intersects with the first preset direction, and n is a positive integer greater than 1;

[0037] The model solving module is used to solve the mathematical model of the thermal effect of the mask based on the n sets of data, and to obtain the correspondence between the deformation of the mask body in the second preset direction and the position in the first preset direction when the i-th wafer is exposed based on the mask, where 1≤i≤n;

[0038] The second acquisition module is used to acquire, according to the correspondence, the deformation of the mask at different target positions in the first preset direction and along the second preset direction when the i-th wafer is exposed based on the mask, wherein the stress adjustment structure is provided at the target position;

[0039] The analysis module obtains the adjustment parameter values ​​of the stress adjustment structure at different target positions in the first preset direction when exposing the i-th wafer based on the mask, according to the deformation along the second preset direction at different target positions in the first preset direction.

[0040] In one embodiment, the stress adjustment structure includes a piezoelectric structure, and the adjustment parameter value includes the voltage signal value of the piezoelectric structure.

[0041] A computer device includes a memory and a processor, the memory storing a computer program, characterized in that the processor executes the computer program to implement the steps of any of the methods described above.

[0042] A computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of any of the methods described above. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the mask structure in one embodiment;

[0045] Figure 2 This is a schematic diagram of the mask structure in another embodiment;

[0046] Figure 3 This is a flowchart illustrating the mask thermal effect analysis and compensation method in one embodiment;

[0047] Figure 4 This is a flowchart illustrating the mask thermal effect analysis and compensation method in another embodiment;

[0048] Figure 5 This is a structural block diagram of a photolithography system in one embodiment;

[0049] Figure 6 This is a structural block diagram of a mask thermal effect analysis and compensation device in one embodiment.

[0050] Explanation of reference numerals in the attached drawings: 110 - Mask body, 120 - Rigid frame, 130 - Stress adjustment structure, 100 - Mask, 200 - Mask thermal effect analysis and compensation device, 300 - Exposure device, 400 - Control device, 210 - First acquisition module, 220 - Model solving module, 230 - Second acquisition module, 240 - Analysis module. Detailed Implementation

[0051] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0053] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

[0054] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. Furthermore, in the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if there is transmission of electrical signals or data between the connected objects.

[0055] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0056] In one embodiment, see Figure 1 A mask 100 is provided, including a mask body 110, a rigid frame 120, and a stress adjustment module.

[0057] The mask body 110 has a mask pattern (not shown), which includes overlay marks for the current layer. After exposing and developing a wafer using the mask, the mask pattern on the mask body 110 can be transferred to the photoresist on the wafer. Then, the wafer is etched based on the patterned photoresist, thereby transferring the mask pattern on the mask body 110 to the wafer.

[0058] The mask pattern can be used to form lines, grooves, or vias on the film layer to be processed. The mask pattern can correspond to the light-transmitting area of ​​the mask body 110 or the non-light-transmitting area of ​​the mask body 110.

[0059] The material of the mask version 110 may include, but is not limited to, quartz, chromium, chromium oxide and molybdenum silicide.

[0060] The rigid frame 120 is located on the periphery of the mask body 110. The rigid frame 120 can be made of a material with high hardness and low coefficient of thermal expansion, so that it is not easily affected by thermal effects and is not easily deformed by heat during the wafer exposure cycle.

[0061] The stress adjustment module includes a plurality of stress adjustment structures 130 arranged along at least one side of the mask body 110.

[0062] Specifically, multiple stress adjustment structures 130 can be arranged around one side of the mask body 110. Alternatively, multiple stress adjustment structures 130 can be arranged around multiple sides of the mask body 110.

[0063] The stress adjustment module is located between the mask body 110 and the rigid frame 120. The stress adjustment module, mask body 110, and rigid frame 120 can be assembled to form a single mask structure. Furthermore, the assembly method of the stress adjustment module, mask body 110, and rigid frame 120 is not limited. For example, the stress adjustment module can be inserted between the mask body 110 and the rigid frame 120 to complete the mask assembly. Alternatively, the stress adjustment module can be first installed onto the rigid frame 120 and then assembled with the mask body 110.

[0064] The stress adjustment structure 130 can be used to adjust the stress in the mask version body 110.

[0065] In this embodiment of the photomask, a rigid frame 120, which is not easily deformed by thermal effects, is provided on the outer periphery of the photomask body 110, which is susceptible to deformation due to thermal effects. A stress adjustment module is then positioned between the two. Therefore, the force generated by the stress adjustment module can effectively act on the photomask body 110, thereby offsetting the stress generated by thermal effects during exposure. Furthermore, the deformation correction requirements at different locations of the photomask body 110 may differ. Therefore, arranging multiple stress adjustment structures 130 on the same side of the photomask body 110 allows for different stress compensations at different locations during exposure. This enables stress compensation of the photomask body 110 based on the deformation correction requirements at each location. Therefore, this embodiment can effectively compensate for the deformation of the photomask body 110 caused by exposure thermal effects, thereby improving the overlay accuracy of the lithography system.

[0066] In one embodiment, the stress-adjusting structure 130 includes a piezoelectric structure.

[0067] After receiving a voltage signal, the piezoelectric structure can convert the electrical signal into mechanical stress. Then, by adjusting the voltage applied to the piezoelectric structure, the deformation of the mask body caused by thermal effects can be effectively corrected.

[0068] As an example, a piezoelectric structure may include a piezoelectric actuator. Alternatively, the piezoelectric structure may also take other forms, such as a structure formed of piezoelectric material. This application does not limit the specific form of the piezoelectric structure.

[0069] In other embodiments, the stress adjustment structure 130 may also take other structural forms, such as microelectromechanical systems (MEMS).

[0070] In one embodiment, see Figure 1 The mask version 110 includes two first sides 111 extending along a first direction and two second sides 112 extending along a second direction, the first direction and the second direction intersecting.

[0071] As an example, the outer contour of the mask version 110 can be rectangular. The direction of the shorter side of the rectangle can be a first direction, and the direction of the longer side of the rectangle can be a second direction.

[0072] The second direction is the direction of light source scanning when the lithography system performs exposure based on the mask.

[0073] The first direction can be the x-axis, and the second direction can be the y-axis. During photolithography exposure of each wafer, the wafer is divided into multiple rows and columns of rectangular exposure fields. The width of the exposure field is the same as the width of the light source in the photolithography system. Starting from the initial position, the light source of the photolithography system scans the mask body 110 along the y-axis, completing the exposure of a single exposure field. Subsequently, the wafer advances one exposure field width along the x-axis, and the light source scans the mask body 110 in reverse along the y-axis, continuing until one row of exposure fields is completed. After one row of exposure fields is completed, the wafer is moved to the initial position of the next row of exposure fields, and the remaining rectangular exposure fields are exposed sequentially, thus completing the exposure of the entire wafer.

[0074] Therefore, the mask version 110 has different thermal deformation characteristics in the first direction and the second direction. Furthermore, the deformation in the second direction is more difficult to adjust.

[0075] Meanwhile, in this embodiment, the stress adjustment module includes a plurality of stress adjustment structures 130 arranged along at least one first side 111.

[0076] Multiple stress adjustment structures 130 can be arranged around one of the first sides 111 of the mask body 110, or multiple stress adjustment structures 130 can be arranged around both first sides 111 of the mask body 110. The stress adjustment structures 130 arranged around the two first sides 111 can be arranged relative to each other or staggered, and there is no restriction on this.

[0077] The first side 111 extends along a first direction. Therefore, each stress adjustment structure 130 located on the periphery of the first side 111 can provide stress compensation for the mask body 110 in a second direction. Simultaneously, multiple stress adjustment structures 130 are arranged around each first side 111, allowing stress compensation for the mask body 110 in the second direction at different x-coordinate positions as needed, thereby compensating for deformation in the second direction at different x-coordinate positions as required.

[0078] Therefore, this embodiment can effectively adjust the deformation in the second direction, which is difficult to adjust.

[0079] As an example, deformation in the first direction can be effectively compensated by a compensation mechanism within the photolithography system. In this case, the stress adjustment module may consist only of multiple stress adjustment structures 130 arranged along the first side of the mask body 110.

[0080] Of course, as yet another example, please refer to Figure 2The stress adjustment module may also include multiple stress adjustment structures 130 arranged along one or two second sides 112 of the mask body 110. In this case, the deformation in the first direction can also be adjusted by the stress adjustment module.

[0081] In one embodiment, see Figure 1 or Figure 2 , Rigid frame 120 surrounds mask version 110.

[0082] At this point, it is easy to assemble the rigid frame 120, the stress adjustment module, and the mask version body 110 into a single structure.

[0083] Meanwhile, the rigid frame 120 surrounds the mask version body 110, which also facilitates the setting of stress adjustment structure 130 along any side of the mask version body 110.

[0084] In one embodiment, see Figure 3 It also provides a method for analyzing and compensating for thermal effects of photomasks, including:

[0085] Step S10: Obtain n sets of data obtained by continuously exposing n test wafers using the above-mentioned mask. When continuously exposing n test wafers, no stress is applied to the stress adjustment module of the mask, and one set of data is obtained for each pair of test wafers exposed. Each set of data includes measurement data of several exposure fields on the wafer. The measurement data of each exposure field includes overlay error data measured by several pairs of overlay marks. The overlay error data measured by each pair of overlay marks includes overlay error measurement values ​​of a first preset direction and a second preset direction. The second preset direction intersects with the first preset direction, and n is a positive integer greater than 1.

[0086] Test wafers are wafers used for testing experiments to collect overlay error data.

[0087] Each test wafer has multiple exposure fields, each with pre-etched overlay marks. When exposing the test wafer using a photomask, each exposure field can be exposed sequentially. During exposure of each field, the optical image of the photomask covers the field. Then, the light source of the lithography system scans the photomask body 110 gradually along the y-direction from the initial position, completing the exposure of a single field. Subsequently, the wafer advances one exposure field width along the x-direction, and the light source scans the photomask body 110 in the reverse y-direction, continuing until one row of exposure fields is exposed. After one row of exposure fields is completed, the wafer is moved to the initial position of the next row of exposure fields, and the remaining rectangular exposure fields are exposed sequentially, thus completing the exposure of the entire wafer.

[0088] When the mask continuously exposes each test wafer, no stress is applied to the stress adjustment module of the mask. As an example, when the stress adjustment structure 130 includes a piezoelectric structure, no voltage is applied to the piezoelectric structure.

[0089] When n test wafers are continuously exposed using a photomask, the light source of the photolithography system illuminates the photomask multiple times, causing thermal effects to accumulate on the photomask body 110. As the number of test wafers exposed increases, the thermal effect becomes more severe, resulting in increasingly larger overlay errors on each sequentially exposed test wafer. Once the thermal effect accumulates to a certain level, it reaches a relatively stable state, after which the overlay errors on each test wafer do not change significantly. The number of test wafers n can be determined based on the number of wafers required for the thermal effect to stabilize.

[0090] After each test wafer has undergone one exposure, the overlay error data of that test wafer can be obtained by measuring the overlay marks between the current layer and the previous layer.

[0091] In this step, a set of data is acquired for each pair of test wafers exposed. Each set of data includes measurement data from several exposure fields on the wafer. The measurement data for each exposure field includes overlay error data obtained from several pairs of overlay marks. The overlay error data obtained from each pair of overlay marks includes overlay error measurement values ​​for a first preset direction and a second preset direction. Here, "several" can mean one or more.

[0092] It should be noted that, on the one hand, for each test wafer, some (or all) of the multiple exposure fields on the wafer can be selected for overlay error measurement; and the number and location of the selected exposure fields can be different on different test wafers. On the other hand, within each selected exposure field on the same test wafer, some (or all) of the overlay marks within the multiple pairs of overlay marks in the exposure field can be selected for overlay error measurement; and the number and location of the selected overlay marks in different exposure fields can be different.

[0093] As an example, the first preset direction can intersect with the light source scanning direction (y-direction) when the lithography system exposes based on the mask. In this case, the first preset direction can be the x-direction, and the second preset direction can be the y-direction. Each pair of test wafers exposed yields a set of data, which can include overlay error data measured from multiple pairs of overlay marks within multiple exposure fields. The overlay error in the x and y directions at each pair of overlay marks can be measured.

[0094] Of course, the first preset direction is not limited to this. For example, the first preset direction can also be the y-direction, and the second preset direction can also be the x-direction. In this case, a set of data is obtained for each pair of test wafers exposed, which can include overlay error data measured by multiple pairs of overlay marks in multiple exposure fields. The overlay error in the x and y directions at each pair of overlay marks can be measured.

[0095] Step S20: Based on n sets of data, solve the mathematical model of the thermal effect of the mask, and obtain the correspondence between the deformation of the mask body 110 in the second preset direction and the position in the first preset direction when exposing the i-th wafer based on the mask, 1≤i≤n.

[0096] Multiple sets of data represent the overlay error data on n test wafers that are exposed sequentially. Based on this, a mathematical model of the mask thermal effect can be calculated using methods known to those skilled in the art.

[0097] Exposure of the i-th wafer based on a mask refers to the exposure of the i-th wafer out of the n wafers in a cycle of sequentially exposing n wafers based on a mask in its original state. It can be understood that the mask in its original state is a mask that has not undergone thermal effect accumulation.

[0098] For each test wafer, data from all selected exposure fields within the wafer can be synthesized to solve a mathematical model of the mask's thermal effect, yielding n sets of mathematical expressions. These expressions are used to simulate the sequential exposure of n wafers based on a mask in its original state. Each set of mathematical expressions corresponds to one wafer. Each set of data expressions can be a functional expression relating the overlay error in a second preset direction (e.g., the y-direction) to the position coordinates in a first preset direction (e.g., the x-direction) within the same exposure field.

[0099] The function expression can include first-order, third-order, or fifth-order polynomials, etc. Different terms of the polynomial can represent different meanings. For example, different terms can respectively reflect the overlay errors caused by mask thermal effect deformation, mask translation, mask rotation, etc. Furthermore, the polynomial must include at least one term related to mask thermal effect deformation.

[0100] Therefore, when the second preset direction is the y-direction and the first preset direction is the x-direction, based on the above function expression, the correspondence between the y-direction deformation of the mask version body 110 and the position in the x-direction can be obtained, that is, the correspondence between the deformation in the second preset direction and the position in the first preset direction of the mask version body 110 can be obtained.

[0101] Taking a third-order polynomial model as an example, with the center of the exposure field as the origin of the coordinate system, the mathematical model of the overlay error of the i-th wafer within the exposure field can be calculated based on the i-th set of data:

[0102] dx = k1 + k3*x + k5*y + k7*x 2 +k9*xy+k 11 *y 2 +k 13 *x 3 +k 15 *x 2 y+k 17 *xy 2 +k 19 *y 3

[0103] dy = k2 + k4*y + k6*x + k8*y 2 +k 10 *yx+k 12 *x 2 +k 14 *y 3 +k 16 *y 2 x+k 18 *yx 2 +k 20 *x 3

[0104] Where dx and dy represent the overlay errors in the x and y directions at the (x,y) coordinates, respectively. Terms that may be introduced by mask thermal effects include, but are not limited to, k. 17 k 18 Etc. Integrating the above terms along the y-direction yields the deformation in the y-direction at coordinate x of the mask caused by thermal effects.

[0105] Therefore, when exposing the i-th wafer based on the mask, the correspondence between the deformation in the second preset direction and the position in the first preset direction of the mask body 110 can be obtained, 1≤i≤n.

[0106] It can be understood that 1≤i≤n, which means that n correspondences can be obtained for exposing n wafers based on the mask.

[0107] Step S30: According to the correspondence, when exposing the i-th wafer based on the mask, the target deformation of the mask at different target positions in the first preset direction is obtained, and a stress adjustment structure 130 is provided at the target position.

[0108] It can be understood that the target deformation is the deformation in the second preset direction.

[0109] Based on the correspondence and the coordinates of different target positions, a set of target deformations for different target positions in the first preset direction can be obtained.

[0110] For n wafers, n sets of target deformations can be obtained.

[0111] Step S40: Based on the target deformation at different target positions in the first preset direction, obtain the adjustment parameter values ​​of the stress adjustment structure 130 at different target positions in the first preset direction when exposing the i-th wafer based on the mask.

[0112] At this point, the target deformation is converted into adjustment parameter values, so that the mask body 110 can be stress compensated through the stress adjustment structure 130.

[0113] For n sets of target deformations corresponding to n wafers, n sets of adjustment parameter values ​​can be obtained, and then the stress adjustment structure 130 can be used to effectively compensate for thermal stress on each wafer.

[0114] In this embodiment, a mathematical model of the thermal effect of the mask is obtained through overlay error data. This model establishes the correspondence between the deformation in the second preset direction and the position in the first preset direction of the mask body 110 during exposure of the i-th wafer based on the mask. Based on this correspondence, target deformation at different target positions in the first preset direction where the stress adjustment structure 130 is located is obtained, and the adjustment parameter values ​​of the stress adjustment structure are obtained based on the target deformation. Therefore, when exposing each wafer in a multi-wafer array based on the mask, the stress adjustment structure can be controlled according to the adjustment parameter values ​​of each stress adjustment structure, thereby effectively compensating for stress in the deformation in the second preset direction.

[0115] In one embodiment, the stress adjustment structure 130 includes a piezoelectric structure. The adjustment parameter value includes the voltage signal value of the piezoelectric structure.

[0116] Please also see Figure 4 Step S40 includes:

[0117] Step S41: Based on the target deformation at different target positions in the first preset direction, obtain the stress compensation value corresponding to the different target positions in the first preset direction when exposing the i-th wafer based on the mask.

[0118] The deformation of the mask body 110 is caused by the stress generated by its thermal effect. Accordingly, an opposite stress compensation value can be applied to counteract the thermal stress.

[0119] The stress compensation value can be obtained from simulation or from actual experimental data. There is no restriction on this.

[0120] Step S42: Based on the stress compensation value, obtain the voltage signal values ​​of the piezoelectric structures at different target positions of the mask in the first preset direction.

[0121] Piezoelectric structures can convert between electrical signals and force signals. Therefore, the voltage signal value of the piezoelectric structure can be obtained based on the stress compensation value. The voltage signal value of the piezoelectric structure is the voltage applied to it.

[0122] Therefore, when using a mask for exposure, different voltage values ​​can be applied to the piezoelectric structures at different target positions in the first preset direction, thereby generating different compensation stresses, which in turn counteract the thermal stress at different target positions, thereby reducing the overlay error in the second preset direction.

[0123] In one embodiment, step S41 may include:

[0124] Step S411: Establish a mechanical simulation analysis model for the mask.

[0125] The mechanical simulation analysis model can utilize models known to those skilled in the art, such as calculating the stress compensation value to be applied based on the target deformation in a second predetermined direction at different target positions in a first predetermined direction and the elastic modulus of the mask version body 110 material. Further details will not be elaborated here.

[0126] Step S412: Based on the target deformation at different target positions in the first preset direction and the mechanical simulation analysis model, obtain the stress compensation value corresponding to the different target positions in the first preset direction when exposing the i-th wafer based on the mask.

[0127] The target deformation at different target positions in the first preset direction can be input into the mechanical simulation analysis model to obtain the stress compensation value corresponding to the different target positions in the first preset direction.

[0128] In this embodiment, stress compensation values ​​are obtained through simulation, which can effectively reduce the research and development cycle and cost.

[0129] In one embodiment, see Figure 5 The system also provides a photolithography system, including an exposure device 300, the aforementioned mask 100, a mask thermal effect analysis and compensation device 200, and a control device 400.

[0130] Exposure apparatus 300 is used for exposure. Mask 100 includes mask body 110, rigid frame 120 and stress adjustment module 130.

[0131] The mask thermal effect analysis and compensation device 200 is used to obtain the adjustment parameter values ​​of the stress adjustment structure 130 at different target positions in a first preset direction when the i-th wafer is exposed based on the mask thermal effect analysis and compensation method described above.

[0132] Based on the mask in its original state, n wafers can be exposed sequentially. When exposing each wafer, the mask thermal effect analysis and compensation device 200 can obtain the adjustment parameter values ​​of the stress adjustment structure 130 at different target positions in a first preset direction.

[0133] It can be understood that a mask in its original state is a mask that has not undergone thermal effect accumulation.

[0134] The control device 400 is electrically connected to the mask thermal effect analysis and compensation device 200 and the exposure device 300. When the exposure device 300 is performing exposure, the control device 400 controls the stress adjustment structure 130 at different target positions in the first preset direction of the mask to perform stress compensation on the mask body 110 according to the adjustment parameter value.

[0135] In application, the photolithography system first continuously exposes n test wafers using the exposure device 300 to obtain overlay error data for each test wafer. Then, the mask thermal effect analysis and compensation device 200 calculates a mathematical model based on the overlay error data for each test wafer and, based on the calculated mathematical model, analyzes and obtains the adjustment parameter values ​​of each stress adjustment structure 130 when exposing the i-th wafer using the mask. Subsequently, a new batch of wafers is sequentially exposed using the mask and the exposure device 300. When exposing each wafer, the control device 400 can control the stress adjustment structures 130 of the mask to perform stress compensation on the mask body 110 based on the adjustment parameter values ​​of each stress adjustment structure 130 obtained by the mask thermal effect analysis and compensation device 200.

[0136] As an example, the stress adjustment structure 130 includes a piezoelectric structure. The adjustment parameter values ​​include the voltage signal values ​​of the piezoelectric structure.

[0137] At this time, the control device 400 applies voltage to the corresponding piezoelectric structure according to the voltage signal value of the piezoelectric structure at different target positions of the mask in the first preset direction, thereby causing the piezoelectric structure to generate corresponding stress to compensate for the stress generated by the thermal effect in the mask body 110.

[0138] When exposing the same wafer, different voltages can be applied to the piezoelectric structures at different target locations. When exposing different wafers, different voltages can be applied to the stress adjustment structure 130 at the same target location. In this way, good stress compensation can be performed at each target location of each wafer, thereby effectively reducing the overlay error of each wafer exposed by the mask and improving the overlay accuracy.

[0139] It should be understood that, although Figures 3-4The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figures 3-4 At least some of the steps in the process may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but may be executed at different times. The execution order of these steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least some of the steps or stages in other steps.

[0140] In one embodiment, see Figure 6 A mask thermal effect analysis and compensation device 200 is provided, comprising: a first acquisition module 210, a model solving module 220, and a second acquisition module 230, wherein:

[0141] The first acquisition module 210 is used to acquire n sets of data obtained by continuously exposing n test wafers using the aforementioned mask.

[0142] During continuous exposure of n test wafers, no stress is applied to the stress adjustment module of the mask. A set of data is acquired for each pair of test wafers exposed. Each set of data includes measurement data from several exposure fields on the wafer. The measurement data for each exposure field includes overlay error data obtained from several pairs of overlay marks. The overlay error data obtained from each pair of overlay marks includes overlay error measurements for a first preset direction and a second preset direction, where the second preset direction intersects the first preset direction, and n is a positive integer greater than 1.

[0143] The model solving module 220 is used to solve the mathematical model of the thermal effect of the mask based on n sets of data, and to obtain the correspondence between the deformation of the mask body 110 in the second preset direction and the position in the first preset direction when the i-th wafer is exposed based on the mask, 1≤i≤n.

[0144] The second acquisition module 230 is used to acquire, according to the correspondence, the target deformation of the mask at different target positions in a first preset direction when the i-th wafer is exposed based on the mask. A stress adjustment structure 130 is provided at the target position.

[0145] The analysis module 240 obtains the adjustment parameter values ​​of the stress adjustment structure 130 at different target positions in the first preset direction when the i-th wafer is exposed based on the mask, according to the target deformation at different target positions in the first preset direction.

[0146] As an example, the stress adjustment structure 130 includes a piezoelectric structure, and the adjustment parameter values ​​include the voltage signal values ​​of the piezoelectric structure.

[0147] Specific limitations regarding the mask thermal effect analysis and compensation device can be found in the limitations of the mask thermal effect analysis and compensation method described above, and will not be repeated here. Each module in the aforementioned mask thermal effect analysis and compensation device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module. It should be noted that the module division in this embodiment is illustrative and only represents a logical functional division; other division methods may be used in actual implementation.

[0148] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0149] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0150] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0151] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0152] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0153] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A photomask, characterized in that, include: A mask version body, wherein a mask pattern is provided on the mask version body; A rigid frame is located on the periphery of the mask version body; A stress adjustment module is located between the mask version body and the rigid frame, and includes a plurality of stress adjustment structures arranged along at least one side of the mask version body.

2. The mask according to claim 1, characterized in that, The stress-regulating structure includes a piezoelectric structure.

3. The mask according to claim 2, characterized in that, The piezoelectric structure includes a piezoelectric actuator.

4. The mask according to claim 1, characterized in that, The mask body includes two first sides extending along a first direction and two second sides extending along a second direction. The first direction intersects the second direction, and the second direction is the light source scanning direction when the photolithography system performs exposure based on the mask. The stress adjustment module includes a plurality of stress adjustment structures arranged along at least one of the first sides.

5. The photomask according to claim 1, characterized in that, The rigid frame surrounds the mask version body.

6. A method for analyzing and compensating for thermal effects of a photomask, characterized in that, include: Obtain n sets of data by continuously exposing n test wafers using the mask as described in any one of claims 1-5, wherein when continuously exposing n test wafers, the stress adjustment module of the mask is not stressed, and a set of data is obtained for each pair of test wafers exposed, each set of data includes measurement data of several exposure fields on the wafer, the measurement data of each exposure field includes overlay error data measured by several pairs of overlay marks, the overlay error data measured by each pair of overlay marks includes overlay error measurement values ​​of a first preset direction and a second preset direction, the second preset direction intersects with the first preset direction, and n is a positive integer greater than 1; Based on the n sets of data, the mathematical model of the thermal effect of the mask is solved, and the correspondence between the deformation of the mask body in the second preset direction and the position in the first preset direction is obtained when the i-th wafer is exposed based on the mask, 1≤i≤n; According to the correspondence, when exposing the i-th wafer based on the mask, the target deformation of the mask at different target positions in the first preset direction is obtained, and the stress adjustment structure is provided at the target position; Based on the target deformation at different target positions in the first preset direction, the adjustment parameter values ​​of the stress adjustment structure at different target positions in the first preset direction are obtained when the i-th wafer is exposed based on the mask.

7. The method for analyzing and compensating for thermal effects of a photomask according to claim 6, characterized in that, The first preset direction intersects with the light source scanning direction when the photolithography system exposes the mask.

8. The method for analyzing and compensating for thermal effects of a photomask according to claim 6, characterized in that, The stress adjustment structure includes a piezoelectric structure, and the adjustment parameter value includes the voltage signal value of the piezoelectric structure. The step of obtaining adjustment parameter values ​​of the stress adjustment structure at different target positions in the first preset direction based on the target deformation at different target positions in the first preset direction during exposure of the i-th wafer based on the mask includes: Based on the target deformation at different target positions in the first preset direction, obtain the stress compensation value corresponding to the different target positions in the first preset direction when exposing the i-th wafer based on the mask. Based on the stress compensation value, the voltage signal values ​​of the piezoelectric structures at different target positions of the mask in the first preset direction are obtained.

9. The method for analyzing and compensating for thermal effects of a photomask according to claim 8, characterized in that, Based on the target deformation at different target positions in the first preset direction, obtain the stress compensation value corresponding to different target positions in the first preset direction when exposing the i-th wafer based on the mask, including: Establish a mechanical simulation analysis model for the aforementioned mask; Based on the target deformation at different target positions in the first preset direction and the mechanical simulation analysis model, the stress compensation value corresponding to different target positions in the first preset direction is obtained when the i-th wafer is exposed based on the mask.

10. A photolithography system, characterized in that, include: Exposure apparatus; The mask as described in any one of claims 1-5; A mask thermal effect analysis and compensation device is used to obtain the adjustment parameter values ​​of the stress adjustment structure at different target positions in the first preset direction when the i-th wafer is exposed based on the mask, according to the method of any one of claims 6-9. A control device, electrically connected to the mask thermal effect analysis and compensation device and the exposure device, is used to control the stress adjustment structure at different target positions in the first preset direction of the mask to perform stress compensation on the mask body according to the adjustment parameter value when the exposure device is performing exposure.

11. The photolithography system according to claim 10, characterized in that, The stress adjustment structure includes a piezoelectric structure, and the adjustment parameter value includes the voltage signal value of the piezoelectric structure. The control device applies voltage to the corresponding piezoelectric structure according to the voltage signal value of the piezoelectric structure at different target positions of the mask in the first preset direction.

12. A device for analyzing and compensating for thermal effects of a photomask, characterized in that, The device includes: The first acquisition module is used to acquire n sets of data obtained by continuously exposing n test wafers using the mask as described in any one of claims 1-5, wherein when continuously exposing n test wafers, the stress adjustment module of the mask is not stressed, and a set of data is acquired for each pair of test wafers exposed, each set of data includes measurement data of several exposure fields on the wafer, the measurement data of each exposure field includes overlay error data measured by several pairs of overlay marks, the overlay error data measured by each pair of overlay marks includes overlay error measurement values ​​of a first preset direction and a second preset direction, the second preset direction intersects with the first preset direction, and n is a positive integer greater than 1; The model solving module is used to solve the mathematical model of the thermal effect of the mask based on the n sets of data, and to obtain the correspondence between the deformation of the mask body in the second preset direction and the position in the first preset direction when the i-th wafer is exposed based on the mask, where 1≤i≤n; The second acquisition module is used to acquire, according to the correspondence, the target deformation of the mask at different target positions in the first preset direction when the i-th wafer is exposed based on the mask, wherein the stress adjustment structure is provided at the target position; The analysis module obtains the adjustment parameter values ​​of the stress adjustment structure at different target positions in the first preset direction when exposing the i-th wafer based on the mask, according to the target deformation at different target positions in the first preset direction.

13. The mask thermal effect analysis and compensation device according to claim 12, characterized in that, The stress adjustment structure includes a piezoelectric structure, and the adjustment parameter value includes the voltage signal value of the piezoelectric structure.

14. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 6 to 9.

15. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 6 to 9.

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