Mask secondary exposure automatic alignment method and device
By setting the alignment mark array and engraving icon on the mask plate, the grid intersection points are captured to obtain machine coordinates and match the design pattern coordinates, the difficulty of alignment marks under medium and high-power lenses of the photolithographic mask plate is solved. The problem found achieves high-precision secondary exposure alignment.
Patent Information
- Application Number
- CN202311484285.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-08
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2043-11-08
AI Technical Summary
During the secondary exposure of the lithographic mask version, it is difficult to quickly find the required alignment mark under high-power lenses, resulting in low alignment accuracy and difficult operation.
Set up a alignment mark array on the mask design pattern, including the grid area and the engraved icon, obtain the machine coordinates by capturing the intersection of the grid, and match and align with the coordinates of the design pattern, and perform secondary exposure to achieve alignment accuracy. promote.
Through automatic alignment methods and devices, the alignment marks are quickly found, which improves the alignment accuracy of secondary exposure, ensures the best placement of the graphics in the lithography machine, and achieves rapid positioning and accurate alignment of the alignment under high-power lenses Bit.
Smart Images
Figure CN117452778B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor production technology, and in particular to a method and device for automatic alignment of a mask secondary exposure. Background Art
[0002] The photolithography mask (also known as the mask, in English, Mask Reticle), referred to as the mask, is a graphic master used in the photolithography process commonly used in micro-nano processing technology. The mask pattern structure is formed on the transparent substrate by an opaque light-shielding film, and then the graphic information is transferred to the product substrate through the exposure process. The mask to be processed is composed of a glass / quartz substrate, a chrome layer and a photoresist layer. Its graphic structure can be obtained through plate making technology, and the commonly used processing equipment is direct writing photolithography equipment, such as laser direct writing photolithography machine, electron beam photolithography machine, etc. Masks are widely used. Masks are needed in fields involving photolithography, such as IC (Integrated Circuit), FPD (Flat Panel Display), PCB (Printed Circuit Boards), MEMS (Micro Electro Mechanical Systems), etc.
[0003] The production of masks often uses secondary or multiple exposure technologies to achieve the mutual superposition and optimization of different substrates and to meet various customer needs such as HTM and PSM. Generally, secondary exposure has very high requirements for secondary alignment, and the accuracy is generally at the micron level or even at the ten-nanometer level. Therefore, a higher-power microscope lens is used for alignment and exposure. The ordinary alignment method is generally manual. First, use a low-power lens to find the alignment mark, and then use a high-power lens for precise alignment. However, the lithography machine generally has only one high-power exposure lens, or changing the lens will affect the actual exposure effect. Therefore, it is not possible to use a low-power lens to find the alignment mark first, and then switch to a high-power lens; because the field of view of the high-power lens is too small, generally only one hundred microns or tens of microns, and the width of the alignment mark used for alignment is only one-tenth of the field of view. It will be very difficult to use a high-power lens to find these alignment marks on a 100mm or even 1m large mask, and the alignment accuracy obtained by this static alignment is not high. Summary of the invention
[0004] The main purpose of the present invention is to provide a method and device for automatic alignment of a mask secondary exposure, aiming to solve the technical problem that it is difficult to quickly find the required alignment marks under a high-magnification lens during secondary exposure alignment.
[0005] In order to solve the above technical problems, the present invention provides a first aspect of a mask secondary exposure automatic alignment method, the method comprising:
[0006] An alignment mark array consisting of a plurality of alignment marks is arranged on the mask design pattern, each of the alignment marks comprises a grid area and an overlay icon, and the grid intersections in the grid area have unique identification parameters; the grid area is large enough to cover the centering error of the upper plate or the photolithography pattern, the grid is used to locate the machine coordinates of the alignment mark, and the overlay icon is used to measure the position deviation of two exposures; the mask design pattern with the alignment mark array is subjected to a secondary glue coating process after a single exposure;
[0007] Move the high-power microscope so that the crosshairs reach the grid area, capture the three nearest grid intersections T1, T2, and T3 in the grid area along the X and Y directions, and obtain the vector and calculating and obtaining the coordinates of the center point of the grid bar area, that is, the machine coordinates of the alignment mark;
[0008] The machine coordinates of all the alignment marks in the alignment mark array are obtained in sequence, the machine coordinates of all the alignment marks are matched and aligned with the corresponding design coordinates on the mask design pattern, and secondary exposure is performed according to the aligned parameters.
[0009] When in use, the array with alignment marks is added to the first layer of the mask design pattern, and then exposed, developed, etched, cleaned, and then coated with glue for the second time, and then the second exposure is started. When performing the second exposure, first load the mask into the lithography machine, focus and start the alignment program, the high-power mirror will move to a certain place on the grid area of the first alignment mark on the mask, and the lithography machine will capture the three nearest grid intersections T1, T2, and T3 in the grid area along the x and y directions to obtain the vector , the center point of the grid can be calculated, that is, the machine coordinate value of this alignment mark. Then move to the next alignment mark of the alignment array in turn, and use the same procedure as above to obtain the machine coordinates of this alignment mark. After the entire array is measured, we can get a whole column of machine coordinates, match this array with the design coordinates, calculate the inclination of the coordinates, the shrinkage ratio and the coordinate center, and even calculate the coordinate distortion of the mask, so as to compensate and ensure that the graphics can be well positioned in the two exposures. Since the mask needs a certain temperature stabilization time to be placed in the lithography machine, the above alignment process can be repeated many times to obtain the best alignment accuracy; then the second exposure can be started.
[0010] Furthermore, the grid intersections within the grid bar area have unique identification parameters specifically including:
[0011] The grid bar area is based on the center point and increases or decreases in the positive and negative directions of X and Y according to a preset proportional relationship.
[0012] Furthermore, the method further comprises:
[0013] The overlay icons of the first exposure and the second exposure are arranged on both sides of the grid area and mirror-imaged so that the overlay icon of the second exposure does not cover the overlay icon of the first exposure.
[0014] Furthermore, the matching and aligning of the machine coordinates of all the alignment marks with the corresponding design coordinates on the mask design pattern and performing secondary exposure according to the aligned parameters includes:
[0015] The machine coordinates of all alignment marks are matched with the corresponding design coordinates on the mask design pattern, and the rotation angle, coordinate offset, zoom factor, and orthogonality of the high-power mirror are corrected, and then passed to the secondary exposure expodie program for secondary exposure.
[0016] Furthermore, before the step of performing secondary exposure according to the aligned parameters, the method further includes:
[0017] The machine coordinates of all the alignment marks in the alignment mark array are repeatedly acquired multiple times, and the machine coordinates of all the alignment marks are matched and aligned multiple times with the corresponding design coordinates on the mask design pattern.
[0018] Furthermore, the performing secondary exposure according to the aligned parameters specifically includes:
[0019] Double-exposure the mask design with the double-exposure overlay icon.
[0020] Furthermore, after performing secondary exposure according to the aligned parameters, the method further includes:
[0021] The secondary exposure alignment result is detected based on the primary exposure overlay icon and the secondary exposure overlay icon. After the secondary exposure is completed, the alignment mark array can be measured again to judge the position drift generated during the exposure process.
[0022] A second aspect of an embodiment of the present invention provides a mask secondary exposure automatic alignment device, the device comprising: a memory, a pattern capturer, a graphics processor, and a computer program stored in the memory and executable on the processor, and a communication interface with a lithography machine, wherein when the computer program is executed by the processor, the following is achieved:
[0023] An alignment mark array consisting of a plurality of alignment marks is arranged on the mask design pattern, each of the alignment marks comprises a grid area and an overlay icon, and the grid intersections in the grid area have unique identification parameters; the mask design pattern with the alignment mark array is subjected to a secondary glue coating process after a primary exposure;
[0024] Move the high-power microscope so that the crosshairs reach the grid area, capture the three nearest grid intersections T1, T2, and T3 in the grid area along the X and Y directions, and obtain the vector and calculating and obtaining the coordinates of the center point of the grid bar area, that is, the machine coordinates of the alignment mark;
[0025] The machine coordinates of all the alignment marks in the alignment mark array are obtained in sequence, the machine coordinates of all the alignment marks are matched and aligned with the corresponding design coordinates on the mask design pattern, and secondary exposure is performed according to the aligned parameters.
[0026] Beneficial effects of the technical solution of the present invention:
[0027] The automatic alignment method and device for the secondary exposure of the mask of the embodiment of the present invention, by setting an alignment mark array, the grid intersection points in the grid area of each alignment mark have unique identification parameters, such as the spacing that changes in a geometric progression, etc., detect the three grids near the high-power lens, and then locate the machine coordinates of the current alignment mark, and then move and obtain the machine coordinates of the entire alignment mark array in sequence, and then match and align with the design coordinates of the mask design pattern, so as to ensure that the graphics in the two exposures can be well aligned. The present application can quickly find the required alignment mark under the high-power lens during the secondary exposure alignment, quickly realize the secondary alignment of the lithography machine, and make a final confirmation of the effect of the secondary alignment. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 This is a flow chart of a mask secondary exposure automatic alignment method provided by an embodiment of the present invention;
[0029] Figure 2 is a schematic diagram of a grid region structure provided by an embodiment of the present invention;
[0030] Figure 3 is a schematic diagram of an alignment mark structure provided by an embodiment of the present invention;
[0031] Figure 4 It is a schematic diagram of setting an overlay icon on a mask design pattern provided by an embodiment of the present invention;
[0032] Figure 5 Schematic diagram of a single exposure overlay icon and a double exposure overlay icon provided by an embodiment of the present invention;
[0033] Figure 6 It is a cross mark viewing angle diagram for confirming the final exposure alignment effect provided by an embodiment of the present invention;
[0034] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0035] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.
[0036] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and have no specific meanings. Therefore, "module", "component" or "unit" can be used in a mixed manner.
[0037] The device can be implemented in various forms. For example, the device described in the present invention may include mobile terminals such as mobile phones, tablet computers, laptops, PDAs, portable media players (Personal Digital Assistants, PMPs), navigation devices, wearable devices, smart bracelets, pedometers, etc., as well as fixed terminals such as digital TVs, desktop computers, etc. Example
[0038] like Figure 1 As shown, an embodiment of the present invention provides a method for automatic alignment of a mask secondary exposure, the method comprising:
[0039] S101, setting a plurality of alignment mark arrays on the mask design pattern, each of the alignment marks comprising a grid area and an overlay icon, and the grid intersections in the grid area have unique identification parameters; performing a secondary gluing process on the mask design pattern with the alignment mark array after a primary exposure;
[0040] Among them, the grid intersections in the grid area have unique identification parameters, specifically including: setting the horizontal and vertical line widths of the alignment grid to be consistent, the program will automatically capture the grid center coordinate position, the grid spacing is set to be slightly smaller than the field of view of the lithography machine, and the grid spacing, based on the grid center point, increases or decreases along the positive and negative directions of X and Y according to a preset proportional relationship, such as Figure 2 shown.
[0041] An alignment mark array is set on the mask design pattern, and the alignment mark array is added to the first layer design pattern of the mask. Then, after exposure, development, etching and cleaning, a second coating of glue is performed, and then a second exposure is started.
[0042] S102, the high-power mirror will move to a certain place on the grid area of the first alignment mark on the mask, and capture the three nearest grid intersections T1, T2, and T3 in the X and Y directions in the grid area to obtain the vector and calculating and obtaining the coordinates of the center point of the grid bar area, that is, the machine coordinates of the alignment mark;
[0043] S103, then move to the next alignment mark of the alignment mark array in turn, and use the same procedure as above to obtain the machine coordinates of this alignment mark. After the entire array is measured, we can get a whole column of machine coordinates. Match and align the machine coordinates of all alignment marks with the corresponding design coordinates on the mask design pattern to ensure that the graphics in the two exposures can be well aligned, and perform secondary exposure according to the parameters after alignment.
[0044] like Figure 3 , 4 As shown, the method also includes:
[0045] The overlay icons of the first exposure and the second exposure are arranged on both sides of the grid area and mirror-imaged so that the overlay icon of the second exposure does not cover the overlay icon of the first exposure.
[0046] Specifically, the matching and aligning of the machine coordinates of all the alignment marks with the corresponding design coordinates on the mask design pattern, and performing secondary exposure according to the aligned parameters includes:
[0047] The machine coordinates of all alignment marks are matched with the corresponding design coordinates on the mask design pattern, and the rotation angle, coordinate offset, zoom factor, and orthogonality of the high-power mirror are corrected, and then passed to the secondary exposure expodie program for secondary exposure.
[0048] Optionally, before the step of performing secondary exposure according to the parameters after alignment, the method also includes: repeatedly acquiring the machine coordinates of all alignment marks in the alignment mark array, and matching and aligning the machine coordinates of all alignment marks with the corresponding design coordinates on the mask design pattern multiple times.
[0049] Optionally, performing secondary exposure according to the aligned parameters specifically includes:
[0050] Double-exposure the mask design with the double-exposure overlay icon.
[0051] After performing the secondary exposure according to the aligned parameters, the method further comprises: detecting the secondary exposure alignment result according to the primary exposure overlay icon and the secondary exposure overlay icon.
[0052] Specifically, the area of the grid bar is large enough to cover the centering error of the upper plate or the photolithography pattern. The grid area is used to locate the machine coordinates of the alignment mark, and the overlay icon is used to measure the position deviation of the two exposures. The array with the alignment mark is added to the first layer design pattern of the mask, and then exposed, developed, etched, and cleaned, and then a second coating of glue is performed, and then the second exposure is started.
[0053] When performing secondary exposure, first load the mask into the lithography machine, focus and start the alignment program. The high-power microscope will move to a certain place in the grid area on the first alignment mark on the mask. The lithography machine will capture the three nearest grid intersections T1, T2, and T3 in the x and y directions in the grid area to obtain the vector , the center point of the grid can be obtained by calculation, that is, the machine coordinate value of the alignment mark.
[0054] Then move to the next alignment mark of the alignment array in turn, and use the same procedure as above to obtain the machine coordinates of this alignment mark. After the entire array is measured, we can get a machine coordinate array, match this machine coordinate array with the design coordinates, calculate the inclination of the coordinates, the shrinkage ratio and the coordinate center, and even calculate the coordinate distortion of the mask, so as to compensate and ensure that the graphics can be well positioned in the two exposures. Since the mask needs a certain temperature stabilization time when placed in the lithography machine, the above alignment process can be repeated many times to obtain the best alignment accuracy; then you can start the second exposure.
[0055] When in use, the first exposure pattern is processed with secondary glue and then loaded into the photolithography machine. After focusing, the alignment program is started. The lens automatically moves to a certain place in the grid area on the first alignment mark. The photolithography machine captures the three nearest grid intersections in the x and y directions in the grid area, and quickly calculates the coordinate position of the center of this grid according to the measured position. For example:
[0056] Set the grid to an array of 11x17, with a width of 5um, a center spacing of 100um, and a spacing increase of 0.2um from the center to the periphery. Figure 3 , 4 As shown, by randomly measuring the distances to the three nearest grid points, the orientation and coordinate information of the grid center point can be obtained.
[0057] For example, in the X direction, if the distance between the cross marks at any three points is measured to be T1T2=100.4um and T2T3=100.6um, it can be determined that the center of the grid is the third point on the left side of T2.
[0058] If the alignment array is set to 2X2, with a total of four points, as shown in the above procedure, after measuring the four alignment points, calculate the offset and rotation angle of the alignment, and inform the lithography machine of the information for parameter setting and actual secondary exposure. Note that the secondary exposure still needs to expose the overlay icon, but does not need to expose the grid area.
[0059] like Figure 5 , 6 As shown, after the secondary exposure, the secondary exposure alignment result is measured according to the overlay icon.
[0060] The embodiment of the present invention further provides a mask secondary exposure automatic alignment device, the device comprising: a memory, a pattern capturer, a graphics processor, and a computer program stored in the memory and executable on the processor, and a communication interface with a lithography machine. When the computer program is executed by the processor, the following is achieved:
[0061] An alignment mark array consisting of a plurality of alignment marks is arranged on the mask design pattern, each of the alignment marks comprises a grid area and an overlay icon, and the grid intersections in the grid area have unique identification parameters; the mask design pattern with the alignment mark array is subjected to a secondary glue coating process after a primary exposure;
[0062] Move the high-power microscope so that the crosshairs reach the grid area, capture the three nearest grid intersections T1, T2, and T3 in the grid area along the X and Y directions, and obtain the vector and calculating and obtaining the coordinates of the center point of the grid bar area, that is, the machine coordinates of the alignment mark;
[0063] The machine coordinates of all the alignment marks in the alignment mark array are obtained in sequence, the machine coordinates of all the alignment marks are matched and aligned with the corresponding design coordinates on the mask design pattern, and secondary exposure is performed according to the aligned parameters.
[0064] The automatic alignment method and device for the secondary exposure of the mask of the embodiment of the present invention, by setting an alignment mark array, the grid intersection points in the grid area of each alignment mark have unique identification parameters, such as the spacing that changes in a geometric progression, etc., detect the three grids near the high-power lens, and then locate the machine coordinates of the current alignment mark, and then move and obtain the machine coordinates of the entire alignment mark array in sequence, and then match and align with the design coordinates of the mask design pattern, so as to ensure that the graphics in the two exposures can be well aligned. The present application can quickly find the required alignment mark under the high-power lens during the secondary exposure alignment, quickly realize the secondary alignment of the lithography machine, and make a final confirmation of the effect of the secondary alignment.
[0065] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. A method for automatic alignment of a mask secondary exposure, characterized in that: The method comprises: An alignment mark array consisting of a plurality of alignment marks is arranged on the mask design pattern, each of the alignment marks comprises a grid area and an overlay icon, and the grid intersections in the grid area have unique identification parameters; the mask design pattern with the alignment mark array is subjected to a secondary gluing process after a primary exposure; the grid area is based on the center point and increases or decreases in the positive and negative directions of X and Y in accordance with a preset proportional relationship. Move the high-power microscope so that the crosshairs reach the grid area, capture the three nearest grid intersections T1, T2, and T3 in the grid area along the X and Y directions, and obtain the vector and calculating and obtaining the coordinates of the center point of the grid bar area, that is, the machine coordinates of the alignment mark; Sequentially obtain the machine coordinates of all the alignment marks in the alignment mark array, match and align the machine coordinates of all the alignment marks with the corresponding design coordinates on the mask design pattern, and perform secondary exposure according to the aligned parameters; The overlay icons of the first exposure and the second exposure are arranged on both sides of the grid area and mirror-imaged so that the overlay icon of the second exposure does not cover the overlay icon of the first exposure.
2. The automatic alignment method for secondary exposure of a mask according to claim 1, characterized in that: The matching and aligning of the machine coordinates of all the alignment marks with the corresponding design coordinates on the mask design pattern and performing secondary exposure according to the aligned parameters comprises: The machine coordinates of all alignment marks are matched with the corresponding design coordinates on the mask design pattern, and the rotation angle, coordinate offset, zoom factor, and orthogonality of the high-power mirror are corrected, and then a second exposure is performed.
3. The automatic alignment method for secondary exposure of a mask according to claim 1, characterized in that: Before the step of performing secondary exposure according to the aligned parameters, the method further includes: The machine coordinates of all the alignment marks in the alignment mark array are repeatedly acquired multiple times, and the machine coordinates of all the alignment marks are matched and aligned multiple times with the corresponding design coordinates on the mask design pattern.
4. The method for automatic alignment of mask secondary exposure according to claim 1, characterized in that: The double exposure according to the aligned parameters specifically includes: Double-exposure the mask design with the double-exposure overlay icon.
5. The method for automatic alignment of mask secondary exposure according to claim 4, characterized in that: After performing the secondary exposure according to the aligned parameters, the method further comprises: detecting the secondary exposure alignment result according to the primary exposure overlay icon and the secondary exposure overlay icon.
6. A mask secondary exposure automatic alignment device, characterized in that: The device comprises: a memory, a pattern capturer, a graphics processor, a computer program stored in the memory and executable on the processor, and a communication interface with a lithography machine. When the computer program is executed by the processor, the following is achieved: An alignment mark array consisting of a plurality of alignment marks is arranged on the mask design pattern, each of the alignment marks comprises a grid area and an overlay icon, and the grid intersections in the grid area have unique identification parameters; the mask design pattern with the alignment mark array is subjected to a secondary glue coating process after a primary exposure; Move the high-power microscope so that the crosshairs reach the grid area, capture the three nearest grid intersections T1, T2, and T3 in the grid area along the X and Y directions, and obtain the vector and calculating and obtaining the coordinates of the center point of the grid bar area, that is, the machine coordinates of the alignment mark; Sequentially obtain the machine coordinates of all the alignment marks in the alignment mark array, match and align the machine coordinates of all the alignment marks with the corresponding design coordinates on the mask design pattern, and perform secondary exposure according to the aligned parameters; The overlay icons of the first exposure and the second exposure are arranged on both sides of the grid area and mirror-imaged so that the overlay icon of the second exposure does not cover the overlay icon of the first exposure.