Method for improving straightness of metal mask

Abstract

The invention relates to the technical field of display, and provides a method for improving the straightness of a metal mask, which comprises the following steps: measuring the pixel position precision deviation of a plurality of specified point positions of a plurality of sample masks; selecting the X coordinates of the plurality of specified points as an independent variable and the sum of the Y coordinates and the Y-direction deviation as a dependent variable for fitting, or selecting the Y coordinates of the plurality of specified points as an independent variable and the sum of the X coordinates and the X-direction deviation as a dependent variable for fitting to obtain a fitting expression; when a target product is manufactured, a compensation value required by a theoretical coordinate value of a pixel opening point location of the target product is calculated, the theoretical coordinate value of the pixel opening point location in a photomask design layout of the target product is replaced by a compensated actual coordinate value, and the compensated photomask design layout is adopted to expose and manufacture a metal mask plate. The technical problems that the straightness of the metal mask plate is poor, the product yield is poor and the cost is wasted due to the fact that the raw material type is poor are solved.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a method for improving the straightness of a fine metal mask (FMM). Background Art

[0002] In the field of display technology, a fine metal mask (FMM) is a key material used in the manufacturing of OLED (organic light-emitting diode) panels. It is mainly used in the vacuum evaporation process to define RGB (red, green, blue) sub-pixels through a fine metal mask, thereby achieving high-resolution display.

[0003] The straightness of the FMM reflects the relevant elements on the mask, such as whether the pixel opening area can remain flat after processing, without bending, distortion, or other shape deviations. The level of straightness directly affects the accuracy and performance of the FMM. For example, in the evaporation process, a mask with good straightness can more accurately deposit materials in the specified pixel area. If the straightness of the FMM is poor, it will affect the effect of the tension adjustment of the FMM mesh stretching, resulting in the pixel position accuracy during evaporation exceeding the specification, affecting the evaporation use.

[0004] Currently, the straightness of the mask mainly depends on the quality of the raw material. After the Invar alloy film is manufactured, the force of the entire roll of film is not completely uniform, which is reflected in the poor straightness of the raw material pattern or the mask. If this leads to a poor yield of FMM products, the entire roll of material will be directly discarded. If one wants to ensure the straightness of the FMM by improving the straightness of the raw material, the existing method is to perform a modification treatment on the essence of the raw material, such as annealing treatment, but this will undoubtedly increase the process cost. Therefore, there is a need for a method that can improve the straightness of the fine metal mask, so that even if the raw material pattern is poor, the processed FMM can still maintain good straightness, ensure the product yield, and reduce cost waste. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for improving the straightness of a fine metal mask, which solves the technical problems of poor straightness of the fine metal mask, poor product yield, and cost waste caused by the poor pattern of the raw material in the prior art.

[0006] An embodiment of the present invention provides a method for improving the straightness of a metal mask, including: measuring the pixel position accuracy deviation of multiple specified points on multiple sample masks, where the pixel position accuracy deviation includes an X-direction deviation and a Y-direction deviation; selecting the X coordinates of the multiple specified points as independent variables, and the sum of the Y coordinates and the Y-direction deviation as the dependent variable for fitting, or selecting the Y coordinates of the multiple specified points as independent variables, and the sum of the X coordinates and the X-direction deviation as the dependent variable for fitting, to obtain a fitting expression; substituting the theoretical coordinate value in the first direction of the pixel opening point in the reticle design layout of the target product into the fitting expression to obtain the fitting coordinate value in the second direction, and obtaining a compensation value by subtracting the theoretical coordinate value in the second direction from the fitting coordinate value, where when the first direction is the X direction, the second direction is the Y direction, and when the first direction is the Y direction, the second direction is the X direction; taking the negative value of the compensation value of the pixel opening point and adding the theoretical coordinate value in the second direction to obtain the actual coordinate value, and replacing the theoretical coordinate value in the second direction in the reticle design layout with the actual coordinate value.

[0007] Further, the X-direction deviation of the specified point is the average value of the X-direction deviations of the same specified points on the multiple sample masks, and the Y-direction deviation of the specified point is the average value of the Y-direction deviations of the same specified points on the multiple sample masks.

[0008] Further, if the average value of the X-direction deviations of the multiple specified points is less than or equal to the first deviation threshold, and the average value of the Y-direction deviations of the multiple specified points is greater than the first deviation threshold, select the X coordinates of the multiple specified points as independent variables; if the average value of the Y-direction deviations of the multiple specified points is less than or equal to the first deviation threshold, and the average value of the X-direction deviations of the multiple specified points is greater than the first deviation threshold, select the Y coordinates of the multiple specified points as independent variables.

[0009] Further, when the average X - direction deviation of the multiple specified points is greater than the first deviation threshold, and the average Y - direction deviation of the multiple specified points is greater than the first deviation threshold; if the average X - direction deviation of the multiple specified points is less than the average Y - direction deviation, the X - coordinates of the multiple specified points are used as independent variables for the first fitting. After compensating the Y - coordinates of the pixel opening points of the mask design layout of the sample mask, a new sample mask is manufactured, and the multiple specified points of the new sample mask are measured. Based on the measurement results of the new sample mask, the Y - coordinates of the multiple specified points are used as independent variables for the second fitting; if the average Y - direction deviation of the multiple specified points is less than the average X - direction deviation, the Y - coordinates of the multiple specified points are used as independent variables for the first fitting. After compensating the X - coordinates of the pixel opening points of the mask design layout of the sample mask, a new sample mask is manufactured, and the multiple specified points of the new sample mask are measured. Based on the measurement results of the new sample mask, the X - coordinates of the multiple specified points are used as independent variables for the second fitting.

[0010] Further, the first deviation threshold is less than or equal to 20 microns.

[0011] Further, the sample mask includes a pixel region, the shape of the pixel region is rectangular, and the multiple specified points at least include the pixel opening points at the four corners of the rectangle of the pixel region, the mid - points of the four sides of the rectangle, and the center of the rectangle.

[0012] Further, multiple pixel regions are arranged along the X - direction of the sample mask. The multiple specified points of the multiple pixel regions are connected along the X - direction to form a first line, a second line, and a third line respectively. The X - coordinates of the specified points on the first line, the second line, and the third line are used as independent variables, and the sum of the Y - coordinates and the Y - direction deviations is used as the dependent variable for fitting to obtain a first fitting expression, a second fitting expression, and a third fitting expression.

[0013] Further, the first fitting expression, the second fitting expression, and the third fitting expression are monomial fitting, or binomial fitting, or trinomial fitting.

[0014] Further, if a monomial is selected for fitting, when the first-degree term coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the calculation of the compensation value is performed; if a binomial is selected for fitting, when the second-degree term coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same and the numerical difference between the first-degree term coefficients is less than 0.000001, the calculation of the compensation value is performed; if a trinomial is selected for fitting, when the third-degree term coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the second-degree term coefficients are the same, and the numerical difference between the first-degree term coefficients is less than 0.000001, the calculation of the compensation value is performed.

[0015] Further, if the fitting curve of the first fitting expression and the fitting curve of the third fitting expression are symmetric about the fitting curve of the second fitting expression, a partition compensation is performed on the Y coordinates of the pixel opening positions of the photomask design layout of the target product.

[0016] Further, the R-squared values of the first fitting expression, the second fitting expression, and the third fitting expression are greater than or equal to 0.99.

[0017] The embodiments of the present invention at least have the following technical effects: A method for improving the straightness of a metal mask provided by an embodiment of the present invention. Each specified position on the sample mask corresponds to a pixel opening position. Pixel opening positions are densely distributed on the entire metal mask, and the specified positions are only a few selected from all pixel opening positions. The straightness of the metal mask includes the straightness in the X direction and the straightness in the Y direction. The straightness in the X direction characterizes the degree of bending of the curve of the Y-direction deviation values of the pixel opening positions on a line along the X direction of the metal mask with respect to the X coordinate, and the straightness in the Y direction characterizes the degree of bending of the curve of the X-direction deviation values of the pixel opening positions on a line along the Y direction of the metal mask with respect to the Y coordinate. Therefore, first, it is necessary to measure the pixel position accuracy deviations of multiple specified positions on multiple sample masks to obtain the X-direction deviations and Y-direction deviations of multiple specified positions.

[0018] After measuring the accuracy deviation of pixel positions, if multiple specified X coordinates of points are selected as independent variables, that is, the X coordinates of multiple specified points on a line along the X direction of the sample mask are used as independent variables, then the sum of the Y coordinates and Y-direction deviations of multiple specified points on this line should be used as the dependent variable for fitting. Or, if multiple specified Y coordinates of points are selected as independent variables, that is, the Y coordinates of multiple specified points on a line along the Y direction of the sample mask are used as independent variables, then the sum of the X coordinates and X-direction deviations of multiple specified points on this line should be used as the dependent variable for fitting to obtain a fitting expression.

[0019] After obtaining the fitting expression, then perform compensation on the photomask design layout of the target product. It is necessary to obtain the theoretical X coordinates and theoretical Y coordinates of all pixel opening points in the photomask design layout of the target product. If the fitting expression uses the X coordinate as the independent variable, select the theoretical X coordinates of the pixel opening points in the photomask design layout of the target product, substitute the theoretical X coordinates into the fitting expression, solve to obtain the fitting Y coordinates, and subtract the theoretical Y coordinates of the pixel opening points from the fitting Y coordinates to obtain the compensation value; if the fitting expression uses the Y coordinate as the independent variable, select the theoretical Y coordinates of the pixel opening points in the photomask design layout of the target product, substitute the theoretical Y coordinates into the fitting expression, solve to obtain the fitting X coordinates, and subtract the theoretical X coordinates of the pixel opening points from the fitting X coordinates to obtain the compensation value. The compensation value here can be understood as the deviation between the actual coordinate value and the theoretical coordinate value of the pixel opening points obtained after exposure.

[0020] Therefore, after obtaining the compensation value, if the compensation value was previously obtained by subtracting the theoretical Y coordinates of the pixel opening points from the fitting Y coordinates, then use the negative value of the compensation value plus the theoretical Y coordinates to obtain the actual Y coordinates, and replace the theoretical Y coordinates in the photomask design layout with the actual Y coordinates; if the compensation value was previously obtained by subtracting the theoretical X coordinates of the pixel opening points from the fitting X coordinates, then use the negative value of the compensation value plus the theoretical X coordinates to obtain the actual X coordinates, and replace the theoretical X coordinates in the photomask design layout with the actual X coordinates. Then use the compensated photomask design layout for exposure to manufacture the metal mask.

[0021] In this embodiment, by using the pixel position accuracy deviation of the specified points on the sample mask plate of non-conforming products, fitting is performed in the X direction or the Y direction to obtain the variation law of the pixel position accuracy deviation in the X direction or the Y direction. When manufacturing the target product, the compensation value required for calculating the theoretical coordinate value of the pixel opening point of the target product is calculated, and the theoretical coordinate value of the pixel opening point in the photomask design layout of the target product is replaced with the compensated actual coordinate value. The metal mask plate is manufactured by exposing the compensated photomask design layout, which solves the problem of poor straightness of the metal mask plate caused by the poor straightness of the raw material itself, improves the straightness of the metal mask plate, ensures that the pixel position accuracy deviation of the pixel opening point is within the specification, and guarantees the product yield; even if the raw material pattern is poor, a qualified metal mask plate can be manufactured by the method of the present invention, reducing the scrapping of the material roll and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a schematic flowchart of a method for improving the straightness of a metal mask plate provided by an embodiment of the present invention; Figure 2 It is a top view structural schematic diagram of a sample mask plate provided by an embodiment of the present invention; Figure 3 It is a top view structural schematic diagram of a pixel region provided by an embodiment of the present invention.

[0024] Reference numerals: 1 - sample mask plate; 10 - pixel region; 101 to 115, 201 to 215, 301 to 315 - specified points. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the described embodiments are some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0026] Those skilled in the art of the present technology can understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0027] Those skilled in the art of the present technology can understand that, unless specifically stated, the singular forms "a", "an", "the", and "said" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present invention means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. The phrase "and / or" used herein includes all or any unit and all combinations of one or more of the associated listed items.

[0028] In a first aspect, please refer to Figure 1 and Figure 2 , an embodiment of the present invention provides a method for improving the straightness of a metal mask, including: S100: Measure the pixel position accuracy deviation of multiple specified points on multiple sample masks 1, and the pixel position accuracy deviation includes the X-direction deviation and the Y-direction deviation.

[0029] S200: Select the X coordinates of multiple specified points as independent variables, and the sum of the Y coordinates and the Y-direction deviation as the dependent variable for fitting, or select the Y coordinates of multiple specified points as independent variables, and the sum of the X coordinates and the X-direction deviation as the dependent variable for fitting, to obtain a fitting expression.

[0030] S300: Substitute the theoretical coordinate value in the first direction of the pixel opening point in the photomask design layout of the target product into the fitting expression to obtain the fitting coordinate value in the second direction, and obtain the compensation value by subtracting the theoretical coordinate value in the second direction from the fitting coordinate value. Wherein, when the first direction is the X direction, the second direction is the Y direction; when the first direction is the Y direction, the second direction is the X direction.

[0031] S400: Obtain the actual coordinate value by taking the negative value of the compensation value of the pixel opening point and adding the theoretical coordinate value in the second direction, and replace the theoretical coordinate value in the second direction in the photomask design layout with the actual coordinate value.

[0032] In this embodiment, the designated points on the sample mask plate 1, such as 101 - 115, 201 - 215, 301 - 315, each correspond to a pixel opening point. The entire metal mask plate is densely covered with pixel opening points, and the designated points are just a few selected points from all the pixel opening points. The straightness of the metal mask plate includes the straightness in the X direction and the straightness in the Y direction. The straightness in the X direction characterizes the degree of bending of the curve of the Y - direction deviation values of the pixel opening points on a line of the metal mask plate in the X direction with respect to the X - coordinate. The straightness in the Y direction characterizes the degree of bending of the curve of the X - direction deviation values of the pixel opening points on a line of the metal mask plate in the Y direction with respect to the Y - coordinate. Therefore, first, it is necessary to measure the pixel position accuracy deviations of multiple designated points on multiple sample mask plates 1 to obtain the X - direction deviations and Y - direction deviations of multiple designated points. The number of sample mask plates here should be as large as possible, preferably more than 10.

[0033] After measuring the pixel position accuracy deviations, if the X - coordinates of multiple designated points are selected as independent variables, that is, the X - coordinates of multiple designated points on a line in the X direction of the sample mask plate 1 are used as independent variables, then the sum of the Y - coordinates and Y - direction deviations of multiple designated points on this line should be used as the dependent variable for fitting. Or, if the Y - coordinates of multiple designated points are selected as independent variables, that is, the Y - coordinates of multiple designated points on a line in the Y direction of the sample mask plate 1 are used as independent variables, then the sum of the X - coordinates and X - direction deviations of multiple designated points on this line should be used as the dependent variable for fitting to obtain the fitting expression.

[0034] After obtaining the fitting expression, then proceed with the compensation for the photomask design layout of the target product. It is necessary to obtain the theoretical X - coordinates and theoretical Y - coordinates of all pixel opening points in the photomask design layout of the target product. If the fitting expression uses the X - coordinate as the independent variable, select the theoretical X - coordinates of the pixel opening points in the photomask design layout of the target product, substitute the theoretical X - coordinates into the fitting expression, solve to obtain the fitting Y - coordinate, and subtract the theoretical Y - coordinate of the pixel opening point from the fitting Y - coordinate to obtain the compensation value; if the fitting expression uses the Y - coordinate as the independent variable, select the theoretical Y - coordinates of the pixel opening points in the photomask design layout of the target product, substitute the theoretical Y - coordinates into the fitting expression, solve to obtain the fitting X - coordinate, and subtract the theoretical X - coordinate of the pixel opening point from the fitting X - coordinate to obtain the compensation value. The compensation value here can be understood as the deviation between the actual coordinate value and the theoretical coordinate value of the pixel opening point obtained after exposure.

[0035] Therefore, after obtaining the compensation value, if the compensation value was previously obtained by subtracting the theoretical Y coordinate of the pixel opening position from the fitted Y coordinate, then the actual Y coordinate is obtained by adding the negative value of the compensation value to the theoretical Y coordinate, and the theoretical Y coordinate in the reticle design layout is replaced with the actual Y coordinate; if the compensation value was previously obtained by subtracting the theoretical X coordinate of the pixel opening position from the fitted X coordinate, then the actual X coordinate is obtained by adding the negative value of the compensation value to the theoretical X coordinate, and the theoretical X coordinate in the reticle design layout is replaced with the actual X coordinate. After that, the compensated reticle design layout is used for exposure to manufacture the metal mask.

[0036] In this embodiment, by using the pixel position accuracy deviation of the specified points of the sample mask 1 of non-conforming products, fitting is performed in the X direction or the Y direction to obtain the variation law of the pixel position accuracy deviation in the X direction or the Y direction. When manufacturing the target product, the compensation value required for the theoretical coordinate value of the pixel opening position of the target product is calculated, the theoretical coordinate value of the pixel opening position in the reticle design layout of the target product is replaced with the compensated actual coordinate value, and the compensated reticle design layout is used for exposure to manufacture the metal mask, so as to solve the problem of poor straightness of the metal mask caused by the poor straightness of the raw material itself, improve the straightness of the metal mask, ensure that the pixel position accuracy deviation of the pixel opening position is within the specification, and guarantee the product yield; even if the raw material pattern is poor, a qualified metal mask can be manufactured by the method of the present invention, reducing the scrap of the material roll and saving costs.

[0037] In addition, it should be noted that the layout of the target product can be different from that of the sample mask, that is, the target product can be the same type of product as the sample mask or different types of products.

[0038] Optionally, the X-direction deviation of the specified point is the mean value of the X-direction deviations of the same specified points of multiple sample masks 1, and the Y-direction deviation of the specified point is the mean value of the Y-direction deviations of the same specified points of multiple sample masks 1.

[0039] In this embodiment, since the data of multiple sample masks 1 are collected, there are also multiple X-direction deviations and Y-direction deviations for each specified position. Taking the specified point 101 as an example, the theoretical X coordinates at the 101 point of each sample mask among multiple sample masks are the same, and the theoretical Y coordinates are the same, but the X-direction deviations at the 101 point of each sample mask are not necessarily the same, and the Y-direction deviations are not necessarily the same. Therefore, the X-direction deviation of the 101 point is the mean value of the X-direction deviations of multiple sample masks at the a1 point, and the Y-direction deviation of the 101 point is the mean value of the X-direction deviations of multiple sample masks at the a1 point. Similarly, the X-direction deviations and Y-direction deviations of other specified points can also be obtained, which will not be elaborated here.

[0040] Optionally, if the average value of the X-direction deviations of multiple specified points is less than or equal to the first deviation threshold, and the average value of the Y-direction deviations of multiple specified points is greater than the first deviation threshold, select the X coordinates of multiple specified points as the independent variable; if the average value of the Y-direction deviations of multiple specified points is less than or equal to the first deviation threshold, and the average value of the X-direction deviations of multiple specified points is greater than the first deviation threshold, select the Y coordinates of multiple specified points as the independent variable.

[0041] In this embodiment, the first deviation threshold can be understood as the allowable deviation of the pixel opening points on the metal mask plate. That is, if the X-direction deviation and the Y-direction deviation of the pixel opening points are both within the first deviation threshold, it means that the metal mask plate is qualified after the exposure process. The average value of the X-direction deviations of multiple specified points refers to the average value of all X-direction deviations of points 101 - 115, 201 - 215, and 301 - 315. The average value of the Y-direction deviations of multiple specified points refers to the average value of all Y-direction deviations of points 101 - 115, 201 - 215, and 301 - 315. Here, comparing the average value of the X-direction deviations and the average value of the Y-direction deviations of multiple specified points with the first deviation threshold can better reflect the deviation situation of the pixel opening points on the metal mask plate.

[0042] If the average value of the X-direction deviations of multiple specified points is less than or equal to the first deviation threshold, and the average value of the Y-direction deviations of multiple specified points is greater than the first deviation threshold, it means that the deviation of the pixel opening points of sample mask plate 1 in the X direction is within the specification, and the deviation in the Y direction exceeds the specification. At this time, take the X coordinates of multiple specified points on a line in the X direction as the independent variable, and the sum of the Y coordinates and the Y-direction deviations as the dependent variable for fitting; if the average value of the Y-direction deviations of multiple specified points is less than or equal to the first deviation threshold, and the average value of the X-direction deviations of multiple specified points is greater than the first deviation threshold, it means that the deviation of the pixel opening points of sample mask plate 1 in the Y direction is within the specification, and the deviation in the X direction exceeds the specification. At this time, take the Y coordinates of multiple specified points on a line in the Y direction as the independent variable, and the sum of the X coordinates and the X-direction deviations as the dependent variable for fitting.

[0043] Optionally, when the average X-direction deviation of multiple specified points is greater than the first deviation threshold, and the average Y-direction deviation of multiple specified points is greater than the first deviation threshold, if the average X-direction deviation of multiple specified points is less than the average Y-direction deviation, the X coordinates of multiple specified points are used as independent variables for the first fitting. After compensating the Y coordinates of the pixel opening points of the photomask design layout of the sample photomask 1, a new sample photomask is manufactured, and the multiple specified points are measured on the new sample photomask. Based on the measurement results of the new sample photomask, the Y coordinates of multiple specified points are used as independent variables for the second fitting; if the average Y-direction deviation of multiple specified points is less than the average X-direction deviation, the Y coordinates of multiple specified points are used as independent variables for the first fitting. After compensating the X coordinates of the pixel opening points of the photomask design layout of the sample photomask 1, a new sample photomask is manufactured, and the multiple specified points are measured on the new sample photomask. Based on the measurement results of the new sample photomask, the X coordinates of multiple specified points are used as independent variables for the second fitting.

[0044] In this embodiment, if the average X-direction deviation of multiple specified points is greater than the first deviation threshold, and the average Y-direction deviation of multiple specified points is greater than the first deviation threshold, it means that the deviations of the pixel opening points of the sample photomask 1 in the X direction and in the Y direction both exceed the specifications. That is to say, compensations need to be made in both directions. Considering the influence of the compensation in the direction with a larger deviation on the deviation in the direction with a smaller deviation, at this time, compare the magnitudes of the average X-direction deviation and the average Y-direction deviation, and select the coordinate value in the direction with a smaller deviation value as the independent variable. That is to say, first calculate the fitting expression for the direction with a larger deviation, manufacture a new sample photomask to be measured after compensating the direction with a larger deviation, and then use the new sample photomask to be measured to perform measurements again, and calculate the fitting expression for the direction with a smaller deviation before.

[0045] For example, if the average deviation in the X direction is less than the average deviation in the Y direction, at this time, first use the X coordinates of multiple specified points on a certain line in the X direction as the independent variable, and use the sum of the Y coordinates and the deviation in the Y direction as the dependent variable for the first fitting; after obtaining the fitting expression, select the theoretical coordinate values of the pixel opening points in the mask design layout of the initially measured sample mask 1 to obtain the compensation value in the Y direction. Add the negative value of the compensation value to the theoretical Y coordinate to obtain the actual Y coordinate, and replace the theoretical Y coordinate in the mask design layout of the initially measured sample mask 1 with the actual Y coordinate for exposure; obtain a new sample mask compensated in the Y direction, and measure the pixel position accuracy deviation of multiple specified points on multiple new sample masks again. Select the actual Y coordinates of multiple specified points as the independent variable, and use the sum of the X coordinates and the deviation in the X direction as the dependent variable for the second fitting. For subsequent target products, also substitute the theoretical X coordinate into the expression of the first fitting to obtain the fitted Y coordinate, calculate the compensation value in the Y direction of the pixel opening point, obtain the actual Y coordinate, then substitute the actual Y coordinate into the expression of the second fitting to obtain the fitted X coordinate, calculate the compensation value in the X direction of the pixel opening point, obtain the actual X coordinate, and finally replace the theoretical X coordinate and theoretical Y coordinate of the pixel opening point in the mask design layout of the target product with the actual X coordinate and actual Y coordinate.

[0046] Conversely, if the average deviation in the X direction is greater than the average deviation in the Y direction, at this time, first use the Y coordinates of multiple specified points on a certain line in the Y direction as the independent variable, and use the sum of the X coordinates and the deviation in the X direction as the dependent variable for the first fitting to obtain the actual X coordinate, and then perform subsequent exposure and measurement. Specifically, refer to the aforementioned steps and will not be elaborated here. Use the actual X coordinate as the independent variable, and use the sum of the Y coordinates and the deviation in the Y direction as the dependent variable for the second fitting. For subsequent target products, substitute the theoretical Y coordinate into the expression of the first fitting to obtain the fitted X coordinate, calculate the compensation value in the X direction of the pixel opening point, obtain the actual X coordinate, then substitute the actual X coordinate into the expression of the second fitting to obtain the fitted Y coordinate, calculate the compensation value in the Y direction of the pixel opening point, obtain the actual Y coordinate, and finally replace the theoretical X coordinate and theoretical Y coordinate of the pixel opening point in the mask design layout of the target product with the actual X coordinate and actual Y coordinate.

[0047] This can make the fitting expression in the direction with smaller deviation closer to the actual situation. For the entire metal mask with a thickness of only dozens of microns, a change in the pixel opening point in one direction will cause fluctuations in the deviation in the other direction. It is necessary to consider the impact of the compensation in the direction with larger deviation on the deviation in the direction with smaller deviation.

[0048] Optionally, the first deviation threshold is less than or equal to 20 microns. In this embodiment, according to the requirements of the metal mask plate for the deviation of the pixels on the display substrate, the X-direction deviation and the Y-direction deviation of the pixel opening points on the metal mask plate are both within 20 microns, ensuring that the pixel positions will not exceed the specifications during the subsequent evaporation process.

[0049] Optionally, the sample mask plate 1 includes a pixel area 10, the shape of the pixel area 10 is rectangular, and the multiple specified points at least include the pixel opening points at the four corners of the rectangle of the pixel area 10, the midpoints of the four sides of the rectangle, and the pixel opening point at the center of the rectangle.

[0050] In this embodiment, as Figure 2 and Figure 3 shown, the pixel area 10 is densely covered with pixel opening points. The specified points 101, 103, 301, and 303 are the pixel opening points at the four corners of the rectangle of the pixel area 10. The specified points 102, 201, 203, and 302 are the pixel opening points at the midpoints of the four sides of the rectangle of the pixel area 10. The specified point 202 is the pixel opening point at the center of the rectangle of the pixel area 10. The specified points 101 to 103, 201 to 203, and 301 to 303 are the specified points of a pixel area 10 on the sample mask plate 1. Therefore, the specified points 104 to 106, 204 to 206, and 304 to 306, 107 to 109, 207 to 209, and 307 to 309, 110 to 112, 210 to 212, and 310 to 312, 113 to 115, 213 to 215, and 313 to 315 are the specified points in the other four pixel areas 10 respectively. The data collected at the pixel opening points at the four corners of the rectangle, the midpoints of the four sides of the rectangle, and the center of the rectangle of the pixel area 10 can represent the basic distribution and trend of the pixel precision position deviation of the pixel opening points on the entire metal mask plate to the minimum extent. It should be noted that Figure 2 The size of the specified points in Figure 2 is only for schematic position demonstration and does not represent the actual size of the pixel opening points. The actual opening size of the pixel opening points is within 20 microns; Figure 3 The five pixel areas included in Figure 3 are not a limitation on the number of pixel areas on the mask plate. The number of pixel areas is greater than or equal to 1. It should be noted that Figure 3 The top view structure schematic diagram of the pixel area in Figure 3 is only for showing that the pixel area 10 is densely covered with pixel opening points, and does not mean that the pixel opening points can only be distributed in the pixel area according to the Figure 3 quantity or arrangement method in

[0051] Optionally, multiple pixel regions 10 are arranged along the X direction of the sample mask 1. The multiple specified points of the multiple pixel regions 10 are connected along the X direction to form a first line, a second line, and a third line respectively. Taking the X coordinates of the specified points on the first line, the second line, and the third line as independent variables, and the sum of the Y coordinates and the Y-direction deviation as the dependent variable for fitting, the first fitting expression, the second fitting expression, and the third fitting expression are obtained. In this embodiment, as Figure 2 shown, the multiple pixel regions 10 are arranged along the X direction of the sample mask 1, and the X direction is also the rolling extension direction of the metal thin film raw material roll. At this time, the specified points of the multiple pixel regions 10 are connected along the X direction to form a first line L1, a second line L2, and a third line L3 respectively. Taking the X coordinates of the specified points on the first line L1, the second line L2, and the third line L3 as independent variables, and the sum of the Y coordinates and the Y-direction deviation as the dependent variable for fitting, the first fitting expression, the second fitting expression, and the third fitting expression are obtained. If the arrangement direction of the pixel regions 10 is consistent with the rolling extension direction of the metal thin film raw material roll, then it is preferred to use the coordinate values in the extension direction as independent variables, and the sum of the coordinate values and the deviation values in the non-extension direction of the plane where the thin film is located as the dependent variable for fitting.

[0052] Optionally, the first fitting expression, the second fitting expression, and the third fitting expression are monomial fitting, binomial fitting, or trinomial fitting. In this embodiment, the first fitting expression, the second fitting expression, and the third fitting expression should all be selected as monomial fitting, or the first fitting expression, the second fitting expression, and the third fitting expression should all be selected as binomial fitting, or the first fitting expression, the second fitting expression, and the third fitting expression should all be selected as trinomial fitting according to the data distribution law. If the first fitting expression, the second fitting expression, and the third fitting expression adopt different fitting methods, it means that the straightness data of the entire sample mask 1 has no unified trend, and in this case, it is not suitable to directly perform subsequent compensation actions.

[0053] Optionally, if monomial fitting is selected, when the first-order coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the compensation value is calculated; if binomial fitting is selected, when the second-order coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same and the numerical difference of the first-order coefficients is less than 0.000001, the compensation value is calculated; if trinomial fitting is selected, when the third-order coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the second-order coefficients are the same, and the numerical difference of the first-order coefficients is less than 0.000001, the compensation value is calculated.

[0054] In this embodiment, when the first fitting expression, the second fitting expression, and the third fitting expression are all monomial fittings, the first fitting expression is y = A1x + B1, the second fitting expression is y = A2x + B2, and the third fitting expression is y = A3x + B3. When A1 = A2 = A3, it indicates that for the mask plate produced from this coil stock, with the X direction as the independent variable, the changing trend of the pixel position accuracy deviation in the Y direction is consistent. That is to say, after the raw material is manufactured into a mask plate, the straightness change rule of the entire mask plate is unified. In this case, subsequent compensation for the photomask design layout of the target product can be directly carried out.

[0055] When the first fitting expression, the second fitting expression, and the third fitting expression are all binomial fittings, the first fitting expression is y = A1x 2 + B1x + C1, the second fitting expression is y = A2x 2 + B2x + C2, and the third fitting expression is y = A3x 2 + B3x + C3. When A1 = A2 = A3 and the numerical difference between B1, B2, and B3 is less than 0.000001, it indicates that for the mask plate produced from this coil stock, with the X direction as the independent variable, the changing trend of the pixel position accuracy deviation in the Y direction is consistent. That is to say, after the raw material is manufactured into a mask plate, the straightness change rule of the entire mask plate is unified. In this case, subsequent compensation for the photomask design layout of the target product can be directly carried out.

[0056] When the first fitting expression, the second fitting expression, and the third fitting expression are all trinomial fittings, the first fitting expression is y = A1x 3 + B1x 2 + C1x + D1, the second fitting expression is y = A2x 3 + B2x 2 + C2x + D2, and the third fitting expression is y = A3x 3 + B3x 2 + C3x + D3. When A1 = A2 = A3, B1 = B2 = B3, and the numerical difference between C1, C2, and C3 is less than 0.000001, it indicates that for the mask plate produced from this coil stock, with the X direction as the independent variable, the changing trend of the pixel position accuracy deviation in the Y direction is consistent. That is to say, after the raw material is manufactured into a mask plate, the straightness change rule of the entire mask plate is unified. In this case, subsequent compensation for the photomask design layout of the target product can be directly carried out.

[0057] Optionally, if the fitting curves of the first fitting expression and the third fitting expression are symmetric about the fitting curve of the second fitting expression, perform zonal compensation on the Y coordinates of the pixel opening positions in the photomask design layout of the target product. In this embodiment, if the fitting curves of the first fitting expression and the third fitting expression are symmetric about the fitting curve of the second fitting expression, it indicates that the pixel position accuracy deviation on the sample photomask 1 gradually changes from the center line L2 to both sides. At this time, it is necessary to measure the pixel position accuracy deviations at multiple points on multiple straight lines along the X direction between L1 and L2 and between L2 and L3, and respectively fit the relationship between the Y coordinates and Y-direction deviations and the X coordinates of the multiple measurement points on each X-direction straight line. The entire photomask is divided into different regions by L1, L2, L3, and multiple straight lines parallel to L1, L2, L3 therebetween. Different fitting expressions are used for fitting and subsequent compensation for these different regions in the target product, so that the compensation can be more accurate.

[0058] Optionally, the R-squared values of the first fitting expression, the second fitting expression, and the third fitting expression are greater than or equal to 0.99. In this embodiment, the value of R-squared is used to evaluate the goodness of fit of the regression model. The value of R-squared ranges between 0 and 1. A higher R-squared value (close to 1) indicates that the model fits the data well, while a lower R-squared value (close to 0) indicates that the model fits the data poorly. When calculating R-squared ( ), it is necessary to calculate the total sum of squares (SST), the regression sum of squares (SSR), or the residual sum of squares (SSE). The calculation formulas are as follows:

[0059]

[0060]

[0061]

[0062] Among them, is the i-th observation value, that is, the sum of the Y coordinate and the Y-direction deviation of the i-th specified point; is the average value of the dependent variable y; n is the number of observation values; is the fitted value of the i-th observation value, that is, the y value calculated through the fitting expression. Taking Figure 2For example, when fitting the points at positions 101 - 115, 201 - 215, and 301 - 315 respectively, the value of n should be 15. Considering the deviation of the pixel opening positions on the entire metal mask, the R-squared values of the first fitting expression, the second fitting expression, and the third fitting expression all need to be greater than or equal to 0.99 to provide reliable data for subsequent compensation.

[0063] Those skilled in the art of this technology can understand that the various operations, methods, steps, measures, and solutions in the processes discussed in the present invention can be alternated, changed, combined, or deleted. Further, other steps, measures, and solutions in the various operations, methods, and processes discussed in the present invention can also be alternated, changed, rearranged, decomposed, combined, or deleted. Further, the steps, measures, and solutions in the prior art that are the same as those disclosed in the various operations, methods, and processes in the present invention can also be alternated, changed, rearranged, decomposed, combined, or deleted.

[0064] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0065] The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0066] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] In the description of this specification, specific features, structures, materials, or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the straightness of a metal mask, characterized in that, Including: Measuring the pixel position accuracy deviation of multiple specified points on multiple sample masks, where the pixel position accuracy deviation includes the X-direction deviation and the Y-direction deviation; Selecting the X coordinates of the multiple specified points as the independent variable, and the sum of the Y coordinates and the Y-direction deviation as the dependent variable for fitting, or selecting the Y coordinates of the multiple specified points as the independent variable, and the sum of the X coordinates and the X-direction deviation as the dependent variable for fitting, to obtain a fitting expression; Substituting the theoretical coordinate value in the first direction of the pixel opening point in the photomask design layout of the target product into the fitting expression to obtain the fitting coordinate value in the second direction, and obtaining a compensation value by subtracting the theoretical coordinate value in the second direction from the fitting coordinate value, where when the first direction is the X direction, the second direction is the Y direction, and when the first direction is the Y direction, the second direction is the X direction; Taking the negative value of the compensation value of the pixel opening point plus the theoretical coordinate value in the second direction to obtain the actual coordinate value, and replacing the theoretical coordinate value in the second direction in the photomask design layout with the actual coordinate value.

2. The method for improving the straightness of a metal mask according to claim 1, wherein The X-direction deviation of the specified point is the mean value of the X-direction deviations of the same specified points on the multiple sample masks, and the Y-direction deviation of the specified point is the mean value of the Y-direction deviations of the same specified points on the multiple sample masks.

3. The method for improving the straightness of a metal mask according to claim 1, characterized in that, If the mean value of the X-direction deviations of the multiple specified points is less than or equal to the first deviation threshold, and the mean value of the Y-direction deviations of the multiple specified points is greater than the first deviation threshold, select the X coordinates of the multiple specified points as the independent variable; If the mean value of the Y-direction deviations of the multiple specified points is less than or equal to the first deviation threshold, and the mean value of the X-direction deviations of the multiple specified points is greater than the first deviation threshold, select the Y coordinates of the multiple specified points as the independent variable.

4. The method for improving the straightness of a metal mask according to claim 1, characterized in that, When the mean value of the X-direction deviations of the multiple specified points is greater than the first deviation threshold, and the mean value of the Y-direction deviations of the multiple specified points is greater than the first deviation threshold; If the mean value of the X-direction deviations of the multiple specified points is less than the mean value of the Y-direction deviations, perform a first fitting with the X coordinates of the multiple specified points as the independent variable, compensate the Y coordinates of the pixel opening points in the photomask design layout of the sample mask, manufacture a new sample mask, measure the multiple specified points on the new sample mask, and perform a second fitting with the Y coordinates of the multiple specified points as the independent variable based on the measurement results of the new sample mask; If the mean value of the Y-direction deviations of the multiple specified points is less than the mean value of the X-direction deviations, perform a first fitting with the Y coordinates of the multiple specified points as the independent variable, compensate the X coordinates of the pixel opening points in the photomask design layout of the sample mask, manufacture a new sample mask, measure the multiple specified points on the new sample mask, and perform a second fitting with the X coordinates of the multiple specified points as the independent variable based on the measurement results of the new sample mask.

5. The method for improving the straightness of a metal mask according to any one of claims 3 to 4, characterized in that, The first deviation threshold is less than or equal to 20 microns.

6. The method for improving the straightness of a metal mask according to claim 1, characterized in that The sample mask includes a pixel region, the shape of the pixel region is rectangular, and the multiple specified points at least include the four corners of the rectangle of the pixel region, the midpoints of the four sides of the rectangle, and the pixel opening points at the center of the rectangle.

7. The method for improving the straightness of a metal mask according to claim 6, wherein Multiple pixel regions are arranged along the X direction of the sample mask. The multiple specified points of the multiple pixel regions are connected along the X direction to respectively form a first line, a second line, and a third line. Taking the X coordinates of the specified points on the first line, the second line, and the third line as independent variables, and the sum of the Y coordinates and the Y-direction deviation as the dependent variable for fitting, a first fitting expression, a second fitting expression, and a third fitting expression are obtained.

8. The method for improving the straightness of a metal mask according to claim 7, characterized in that The first fitting expression, the second fitting expression, and the third fitting expression are monomial fitting, or binomial fitting, or trinomial fitting.

9. The method for improving the straightness of the metal mask according to claim 8, wherein If monomial is selected for fitting, when the first-order term coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the calculation of the compensation value is performed; If binomial is selected for fitting, when the second-order term coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same and the numerical difference of the first-order term coefficients is less than 0.000001, the calculation of the compensation value is performed; If trinomial is selected for fitting, when the third-order term coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the second-order term coefficients are the same, and the numerical difference of the first-order term coefficients is less than 0.000001, the calculation of the compensation value is performed.

10. The method for improving the straightness of a metal mask according to claim 7, characterized in that If the fitting curve of the first fitting expression and the fitting curve of the third fitting expression are symmetric about the fitting curve of the second fitting expression, the Y coordinates of the pixel opening points of the photomask design layout of the target product are compensated in zones.

11. The method for improving the straightness of a metal mask according to claim 7, characterized in that, The R-squared values of the first fitting expression, the second fitting expression, and the third fitting expression are greater than or equal to 0.99.

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