A method for improving the straightness of metal mask

Abstract

The present invention relates to the field of display technology and provides a method for improving the straightness of a metal mask, comprising: measuring pixel position accuracy deviations of a plurality of designated points on a plurality of sample masks; selecting the X coordinates of the plurality of designated points as independent variables and the sum of the Y coordinates and the Y-direction deviations as dependent variables for fitting, or selecting the Y coordinates of the plurality of designated points as independent variables and the sum of the X coordinates and the X-direction deviations as dependent variables for fitting to obtain a fitting expression; and when manufacturing a target product, calculating compensation values required for theoretical coordinate values of pixel opening points of the target product, replacing the theoretical coordinate values of the pixel opening points in a photomask design layout of the target product with compensated actual coordinate values, and using the compensated photomask design layout for exposure to manufacture the metal mask, thereby solving the technical problems of poor straightness of the metal mask, poor product yield, and cost waste caused by poor original material pattern.

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 metal mask. Background Art

[0002] In the field of display technology, FMM (Fine Metal Mask) is a key material used in the manufacture of OLED (Organic Light-Emitting Diode) panels. It is primarily used in the vacuum evaporation process, defining RGB (red, green, and blue) sub-pixels through a fine metal mask, thereby achieving high-resolution displays.

[0003] The straightness of an FMM reflects relevant elements on the mask, such as whether the pixel opening area remains straight after processing, without bending, twisting, or other shape deviations. The level of straightness directly affects the accuracy and performance of the FMM. For example, in the vapor deposition process, a mask with good straightness can more accurately deposit material in the specified pixel area. If the FMM has poor straightness, it will affect the effectiveness of the FMM's stretching adjustment, resulting in the pixel position accuracy of the vapor deposition exceeding the specification, affecting the performance of the vapor deposition.

[0004] Currently, the straightness of the mask depends mainly 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 original material pattern or straightness. If it leads to poor FMM product yield, the roll will be directly discarded. If you want to ensure the straightness of the FMM by improving the straightness of the raw material, the existing method is to modify the raw material itself, such as annealing, but this will undoubtedly increase the process cost. Therefore, there is a need for a method to improve the straightness of the metal mask. Even if the raw material pattern is poor, the processed FMM can still maintain good straightness, ensure 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 metal mask, which solves the technical problems in the prior art of poor straightness of the metal mask caused by poor original material shape, poor product yield and cost waste.

[0006] An embodiment of the present invention provides a method for improving the straightness of a metal mask, comprising: measuring pixel position accuracy deviations of multiple specified points on multiple sample masks, the pixel position accuracy deviations including X-direction deviations and Y-direction deviations; selecting the X coordinates of the multiple specified points as independent variables and the sum of the Y coordinates and the Y-direction deviations as dependent variables 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 deviations as dependent variables for fitting to obtain a fitting expression; substituting theoretical coordinate values of pixel opening points in a mask design layout of a target product in a first direction into the fitting expression to obtain fitting coordinate values in a second direction, and subtracting the theoretical coordinate values in the second direction from the fitting coordinate values to obtain compensation values, wherein 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 it to the theoretical coordinate value in the second direction to obtain an actual coordinate value, and replacing the theoretical coordinate value in the second direction in the mask design layout with the actual coordinate value.

[0007] Furthermore, the X-direction deviation of the designated point is the average of the X-direction deviations of the same designated point on the multiple sample masks, and the Y-direction deviation of the designated point is the average of the Y-direction deviations of the same designated point on the multiple sample masks.

[0008] Furthermore, if the average X-direction deviation of the multiple designated points is less than or equal to a first deviation threshold, and the average Y-direction deviation of the multiple designated points is greater than the first deviation threshold, the X coordinates of the multiple designated points are selected as independent variables; if the average Y-direction deviation of the multiple designated points is less than or equal to the first deviation threshold, and the average X-direction deviation of the multiple designated points is greater than the first deviation threshold, the Y coordinates of the multiple designated points are selected as independent variables.

[0009] Furthermore, when the mean X-direction deviation of the plurality of designated points is greater than a first deviation threshold, and the mean Y-direction deviation of the plurality of designated points is greater than the first deviation threshold; if the mean X-direction deviation of the plurality of designated points is less than the mean Y-direction deviation, a first fitting is performed with the X coordinates of the plurality of designated points as independent variables, and 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 plurality of designated points are measured on the new sample mask, and the measurement results of the new sample mask are used to calculate the pixel opening points. If the result is less than the average value of the Y-direction deviation of the multiple designated points, a second fitting is performed using the Y coordinates of the multiple designated points as independent variables; if the average value of the Y-direction deviation of the multiple designated points is less than the average value of the X-direction deviation, a first fitting is performed using the Y coordinates of the multiple designated points as independent variables, the X coordinates of the pixel opening points of the mask design layout of the sample mask are compensated, a new sample mask is manufactured, the multiple designated points are measured on the new sample mask, and a second fitting is performed using the X coordinates of the multiple designated points as independent variables based on the measurement results of the new sample mask.

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

[0011] Furthermore, the sample mask includes a pixel area, the shape of the pixel area is rectangular, and the multiple designated points include at least the four corners of the rectangle, the midpoints of the four sides of the rectangle and the pixel opening point at the center of the rectangle.

[0012] Furthermore, the plurality of pixel areas are arranged along the X direction of the sample mask, and the plurality of designated points of the plurality of pixel areas are connected along the X direction to form a first line, a second line, and a third line respectively. The X coordinates of the designated points on the first line, the second line, and the third line are respectively used as independent variables, and the sum of the Y coordinate and the Y-direction deviation is used as the dependent variable for fitting to obtain a first fitting expression, a second fitting expression, and a third fitting expression.

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

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

[0015] Furthermore, if the fitting curve of the first fitting expression and the fitting curve of the third fitting expression are symmetrical about the fitting curve of the second fitting expression, partition compensation is performed on the Y coordinates of the pixel opening points of the mask design layout of the target product.

[0016] Furthermore, 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 have at least the following technical effects:

[0018] An embodiment of the present invention provides a method for improving the straightness of a metal mask. Each designated point on a sample mask corresponds to a pixel opening. The entire metal mask is densely covered with pixel openings, and the designated points are only selected from a few of these pixel openings. The straightness of the metal mask includes straightness in the X direction and straightness in the Y direction. The X-direction straightness characterizes the degree of curvature of the curve showing the Y-direction deviation values of the pixel opening points along a line of the metal mask along the X direction as the X coordinates change. The Y-direction straightness characterizes the degree of curvature of the curve showing the X-direction deviation values of the pixel opening points along a line of the metal mask along the Y direction as the Y coordinates change. Therefore, it is necessary to first measure the pixel position accuracy deviations of multiple designated points on multiple sample masks to obtain the X-direction deviations and Y-direction deviations of the multiple designated points.

[0019] After measuring the pixel position accuracy deviation, if the X coordinates of multiple specified 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 Y coordinates of the multiple specified points on this line and the sum of the Y-direction deviations are used as dependent variables for fitting. Alternatively, if the Y coordinates of multiple specified 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 X coordinates of the multiple specified points on this line and the sum of the X-direction deviations are used as dependent variables for fitting to obtain a fitting expression.

[0020] After obtaining the fitting expression, compensation is then performed on the target product's mask design layout. This requires obtaining the theoretical X and Y coordinates of all pixel openings in the target product's mask design layout. If the fitting expression uses the X coordinate as the independent variable, the theoretical X coordinate of the pixel opening in the target product's mask design layout is selected, the theoretical X coordinate is substituted into the fitting expression, the fitted Y coordinate is obtained, and the theoretical Y coordinate of the pixel opening is subtracted from the fitted Y coordinate to obtain the compensation value. If the fitting expression uses the Y coordinate as the independent variable, the theoretical Y coordinate of the pixel opening in the target product's mask design layout is selected, the theoretical Y coordinate is substituted into the fitting expression, the fitted X coordinate is obtained, and the theoretical X coordinate of the pixel opening is subtracted from the fitted X coordinate to obtain the compensation value. The compensation value here can be understood as the deviation between the actual coordinate value of the pixel opening obtained after exposure and the theoretical coordinate value.

[0021] Therefore, after obtaining the compensation value, if the compensation value was previously obtained by subtracting the theoretical Y coordinate of the pixel opening point from the fitted Y coordinate, then the negative value of the compensation value is added to the theoretical Y coordinate to obtain the actual Y coordinate, and the theoretical Y coordinate in the mask 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 point from the fitted X coordinate, then the negative value of the compensation value is added to the theoretical X coordinate to obtain the actual X coordinate, and the theoretical X coordinate in the mask design layout is replaced with the actual X coordinate, and the compensated mask design layout is then used for exposure to manufacture the metal mask.

[0022] In this embodiment, the pixel position accuracy deviation of the designated points of the sample mask of the non-qualified product is used to perform fitting in the X direction or the Y direction to obtain the variation pattern 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 point of the target product is calculated, the theoretical coordinate value of the pixel opening point in the mask design layout of the target product is replaced with the compensated actual coordinate value, and the compensated mask design layout is used to expose and manufacture the metal mask. This solves the problem of poor straightness of the metal mask caused by poor straightness of the raw material itself, improves the straightness of the metal mask, 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 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

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A schematic flow chart of a method for improving the straightness of a metal mask provided by an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of a top view of a sample mask provided in an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of a top view of the pixel area provided in an embodiment of the present invention.

[0027] Icon: 1-sample mask; 10-pixel area; 101~115, 201~215, 301~315-specified points. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Those skilled in the art will understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which this invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless specifically defined as such, will not be interpreted in an idealized or overly formal sense.

[0030] It will be understood by those skilled in the art that, unless otherwise stated, the singular forms "a," "an," "said," and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. The term "and / or" used herein includes all or any one of the associated listed items and all combinations thereof.

[0031] For the first aspect, see Figure 1 and Figure 2 , an embodiment of the present invention provides a method for improving the straightness of a metal mask, comprising:

[0032] S100: measuring pixel position accuracy deviations of a plurality of designated points of a plurality of sample masks 1, where the pixel position accuracy deviations include X-direction deviations and Y-direction deviations.

[0033] S200: Selecting the X coordinates of multiple specified points as independent variables and the sum of the Y coordinates and the Y deviation as the dependent variable for fitting, or selecting the Y coordinates of multiple specified points as independent variables and the sum of the X coordinates and the X deviation as the dependent variable for fitting, to obtain a fitting expression.

[0034] S300: Substitute the theoretical coordinate value of the first direction of the pixel opening point in the mask design layout of the target product into the fitting expression to obtain the fitting coordinate value of the second direction, and subtract the theoretical coordinate value of the second direction from the fitting coordinate value to obtain the compensation value, wherein 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.

[0035] S400: taking the negative value of the compensation value of the pixel opening point and adding the theoretical coordinate value of the second direction to obtain the actual coordinate value, and replacing the theoretical coordinate value of the second direction in the mask design layout with the actual coordinate value.

[0036] In this embodiment, designated points on sample reticle 1, such as 101-115, 201-215, and 301-315, each correspond to a pixel opening. The entire metal reticle is densely covered with pixel openings, and designated points merely select a few of these pixel openings. The straightness of the metal reticle includes both X-direction straightness and Y-direction straightness. X-direction straightness characterizes the degree of curvature of the curve showing the Y-direction deviation of the pixel opening points along a line of the metal reticle along the X direction as a function of the X coordinate. Y-direction straightness characterizes the degree of curvature of the curve showing the X-direction deviation of the pixel opening points along a line of the metal reticle along the Y direction as a function of the Y coordinate. Therefore, it is necessary to first measure the pixel position accuracy deviation of multiple designated points on multiple sample reticles 1 to obtain the X-direction deviation and Y-direction deviation of the multiple designated points. The number of sample reticles should be as large as possible, preferably at least 10.

[0037] After measuring the pixel position accuracy deviation, if the X coordinates of multiple specified 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 1 are selected as independent variables, then the sum of the Y coordinates and the Y-direction deviations of the multiple specified points on this line is used as the dependent variable for fitting. Alternatively, if the Y coordinates of multiple specified 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 selected as independent variables, then the sum of the X coordinates and the X-direction deviations of the multiple specified points on this line is used as the dependent variable for fitting to obtain a fitting expression.

[0038] After obtaining the fitting expression, compensation is then performed on the target product's mask design layout. This requires obtaining the theoretical X and Y coordinates of all pixel openings in the target product's mask design layout. If the fitting expression uses the X coordinate as the independent variable, the theoretical X coordinate of the pixel opening in the target product's mask design layout is selected, the theoretical X coordinate is substituted into the fitting expression, the fitted Y coordinate is obtained, and the theoretical Y coordinate of the pixel opening is subtracted from the fitted Y coordinate to obtain the compensation value. If the fitting expression uses the Y coordinate as the independent variable, the theoretical Y coordinate of the pixel opening in the target product's mask design layout is selected, the theoretical Y coordinate is substituted into the fitting expression, the fitted X coordinate is obtained, and the theoretical X coordinate of the pixel opening is subtracted from the fitted X coordinate to obtain the compensation value. The compensation value here can be understood as the deviation between the actual coordinate value of the pixel opening obtained after exposure and the theoretical coordinate value.

[0039] Therefore, after obtaining the compensation value, if the compensation value was previously obtained by subtracting the theoretical Y coordinate of the pixel opening point from the fitted Y coordinate, then the negative value of the compensation value is added to the theoretical Y coordinate to obtain the actual Y coordinate, and the theoretical Y coordinate in the mask 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 point from the fitted X coordinate, then the negative value of the compensation value is added to the theoretical X coordinate to obtain the actual X coordinate, and the theoretical X coordinate in the mask design layout is replaced with the actual X coordinate, and the compensated mask design layout is then used for exposure to manufacture the metal mask.

[0040] In this embodiment, the pixel position accuracy deviation of the designated point of the sample mask 1 of the non-qualified product is used to perform fitting in the X direction or the Y direction to obtain the variation pattern 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 point of the target product is calculated, and the theoretical coordinate value of the pixel opening point in the mask design layout of the target product is replaced with the compensated actual coordinate value. The compensated mask design layout is used to expose and manufacture the metal mask, thereby solving the problem of poor straightness of the metal mask caused by poor straightness of the raw material itself, improving the straightness of the metal mask, ensuring that the pixel position accuracy deviation of the pixel opening point is within the specification, and ensuring 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 scrapping of the material roll and saving costs.

[0041] It should also be noted that the target product may have a different layout from the sample mask, that is, the target product may be the same model as the sample mask, or they may be different models.

[0042] Optionally, the X-direction deviation of the designated point is the average of the X-direction deviations of the same designated point on multiple sample masks 1 , and the Y-direction deviation of the designated point is the average of the Y-direction deviations of the same designated point on multiple sample masks 1 .

[0043] In this embodiment, since data from multiple sample reticles 1 is collected, there are multiple X- and Y-axis deviations for each designated location. Taking designated point 101 as an example, the theoretical X coordinates and Y coordinates at point 101 on each of the multiple sample reticles are the same, but the X- and Y-axis deviations at point 101 on each of the multiple sample reticles are not necessarily the same. Therefore, the X-axis deviation at point 101 is the average of the X-axis deviations at point a1 across the multiple sample reticles, and the Y-axis deviation at point 101 is the average of the X-axis deviations at point a1 across the multiple sample reticles. Similarly, the X- and Y-axis deviations for other designated locations can also be obtained, which will not be further detailed here.

[0044] Optionally, if the average X-direction deviation of multiple specified points is less than or equal to a first deviation threshold, and the average Y-direction deviation of multiple specified points is greater than the first deviation threshold, the X coordinates of multiple specified points are selected as independent variables; if the average Y-direction deviation of multiple specified points is less than or equal to the first deviation threshold, and the average X-direction deviation of multiple specified points is greater than the first deviation threshold, the Y coordinates of multiple specified points are selected as independent variables.

[0045] In this embodiment, the first deviation threshold can be understood as the allowable deviation of the pixel opening points on the metal mask. That is, if the X- and Y-direction deviations of the pixel opening points are both within the first deviation threshold, it means that the metal mask passes the exposure process. The mean X-direction deviation of multiple specified points refers to the average of all X-direction deviations of points 101-115, 201-215, and 301-315. The mean Y-direction deviation of multiple specified points refers to the average of all Y-direction deviations of points 101-115, 201-215, and 301-315. Comparing the mean X- and Y-direction deviations of multiple specified points with the first deviation threshold can better reflect the deviation of the pixel opening points on the metal mask.

[0046] If the mean X-direction deviation of the multiple specified points is less than or equal to the first deviation threshold, and the mean Y-direction deviation of the multiple specified points is greater than the first deviation threshold, it means that the deviation of the pixel opening point of the sample mask 1 in the X direction is within the specification, and the deviation in the Y direction exceeds the specification. At this time, the X coordinates of the multiple specified points on a line in the X direction 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. If the mean Y-direction deviation of the multiple specified points is less than or equal to the first deviation threshold, and the mean X-direction deviation of the multiple specified points is greater than the first deviation threshold, it means that the deviation of the pixel opening point of the sample mask 1 in the Y direction is within the specification, and the deviation in the X direction exceeds the specification. At this time, the Y coordinates of the multiple specified points on a line in the Y direction are used as independent variables, and the sum of the X coordinates and the X-direction deviations is used as the dependent variable for fitting.

[0047] Optionally, when the mean X-direction deviation of multiple designated points is greater than a first deviation threshold, and the mean Y-direction deviation of multiple designated points is greater than the first deviation threshold, if the mean X-direction deviation of the multiple designated points is less than the mean Y-direction deviation, a first fitting is performed using the X coordinates of the multiple designated points as independent variables, and after compensating the Y coordinates of the pixel opening points of the mask design layout of the sample mask 1, a new sample mask is manufactured, and the multiple designated points are measured on the new sample mask. Based on the measurement results of the new sample mask, a second fitting is performed using the Y coordinates of the multiple designated points as independent variables; if the mean Y-direction deviation of the multiple designated points is less than the mean X-direction deviation, a first fitting is performed using the Y coordinates of the multiple designated points as independent variables, and after compensating the X coordinates of the pixel opening points of the mask design layout of the sample mask 1, a new sample mask is manufactured, and the multiple designated points are measured on the new sample mask. Based on the measurement results of the new sample mask, a second fitting is performed using the X coordinates of the multiple designated points as independent variables.

[0048] In this embodiment, if the mean X-direction deviation of multiple designated points is greater than a first deviation threshold, and the mean Y-direction deviation of multiple designated points is greater than the first deviation threshold, then it means that the deviation of the pixel opening points of sample reticle 1 in both the X-direction and the Y-direction exceeds the specification, that is, compensation is required in both directions. Considering that compensation in the direction with larger deviation may affect the deviation in the direction with smaller deviation, the mean X-direction deviation is compared with the mean Y-direction deviation, and the coordinate value in the direction with smaller deviation is selected as the independent variable. In other words, the fitting expression for the direction with larger deviation is calculated first. After compensating for the direction with larger deviation, a new sample reticle to be measured is manufactured, and measurement is performed again using the new sample reticle to be measured, and the fitting expression for the direction with smaller deviation is calculated.

[0049] For example, if the mean X-direction deviation is less than the mean Y-direction deviation, the first fitting is performed using the X-coordinates of multiple specified points on a certain 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. After obtaining the fitting expression, the theoretical coordinate value of the pixel opening point in the mask design layout of the sample mask 1 measured initially is selected to obtain the compensation value in the Y-direction. The actual Y-coordinate is obtained by adding the negative value of the compensation value to the theoretical Y-coordinate. The theoretical Y-coordinate of the mask design layout of the sample mask 1 measured initially is replaced with the actual Y-coordinate for exposure. A new sample mask compensated in the Y-direction is obtained, and the pixel position accuracy deviations of multiple specified points on multiple new sample masks are measured again. The actual Y-coordinates of the multiple specified points are selected as the independent variable, and the sum of the X-coordinates and the X-direction deviations is selected as the dependent variable for a second fitting. For subsequent target products, the first fitting expression is also used to substitute the theoretical X coordinate to obtain the fitted Y coordinate, calculate the Y-direction compensation value of the pixel opening point, and obtain the actual Y coordinate. The actual Y coordinate is then substituted into the second fitting expression to obtain the fitted X coordinate, calculate the X-direction compensation value of the pixel opening point, and obtain the actual X coordinate. Finally, the theoretical X coordinate and theoretical Y coordinate of the pixel opening point in the mask design layout of the target product are replaced with the actual X coordinate and actual Y coordinate.

[0050] Conversely, if the mean X-direction deviation is greater than the mean Y-direction deviation, a first fit is performed using 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 to obtain the actual X coordinates. Subsequent exposure and measurement are then performed. The specific steps are referred to above and will not be repeated here. A second fit is performed using the actual X coordinates as the independent variable and the sum of the Y coordinates and the Y-direction deviations as the dependent variable. For the subsequent target product, the first fit expression is substituted into the theoretical Y coordinate to obtain the fitted X coordinate, and the X-direction compensation value of the pixel opening point is calculated to obtain the actual X coordinate. The actual X coordinate is then substituted into the second fit expression to obtain the fitted Y coordinate, and the Y-direction compensation value of the pixel opening point is calculated to obtain the actual Y coordinate. Finally, the theoretical X coordinates and theoretical Y coordinates of the pixel opening point in the mask design layout of the target product are replaced with the actual X coordinates and actual Y coordinates.

[0051] This can make the fitting expression in the direction of smaller deviation closer to the actual situation. For an entire metal mask with a thickness of only tens of microns, changes in the pixel opening position in one direction will cause fluctuations in the deviation in another direction. It is necessary to consider the impact of compensation in the direction of larger deviation on the deviation in the direction of smaller deviation.

[0052] Optionally, the first deviation threshold is less than or equal to 20 microns. In this embodiment, based on the requirements of the metal mask for the deviation of pixels on the display substrate, the X-axis deviation and Y-axis deviation of the pixel opening position on the metal mask are both within 20 microns, ensuring that the pixel position does not exceed the specification during the subsequent evaporation process.

[0053] Optionally, the sample mask 1 includes a pixel area 10, which is rectangular in shape, and the multiple designated points include at least the four corners of the rectangle, the midpoints of the four sides of the rectangle, and the pixel opening point at the center of the rectangle.

[0054] In this embodiment, Figure 2 and Figure 3 As shown, the pixel area 10 is densely distributed with pixel opening points. The designated points 101, 103, 301 and 303 are the pixel opening points at the four corners of the rectangle of the pixel area 10. The designated 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 designated point 202 is the pixel opening point at the center of the rectangle of the pixel area 10. The designated points 101~103, 201~203, 303 are the pixel opening points at the midpoints of the four sides of the rectangle of the pixel area 10. 01~303 are the designated points of a pixel area 10 on the sample mask 1, so the designated points 104~106, 204~206, 304~306, 107~109, 207~209, 307~309, 110~112, 210~212, 310~312, 113~115, 213~215, 313~315 are the designated 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 at least represent the basic distribution and trend of the pixel accuracy position deviation of the pixel opening points on the entire metal mask. It should be noted that Figure 2 The sizes of the designated points are for illustration purposes only and do not represent the actual pixel opening sizes. The actual pixel opening sizes are within 20 microns. Figure 2 The inclusion of five pixel regions does not limit the number of pixel regions on the mask, as long as the number of pixel regions is greater than or equal to 1. Figure 3 The top view of the pixel area is only for showing that the pixel area 10 is densely populated with pixel openings, and does not mean that the pixel openings can only be arranged according to Figure 3 The number or arrangement of the pixels in the pixel area does not limit the pixel opening positions in the pixel area.

[0055] Optionally, multiple pixel regions 10 are arranged along the X direction of the sample mask 1, and multiple designated 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. The X coordinates of the designated 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 deviation is used as the dependent variable to perform fitting to obtain the first fitting expression, the second fitting expression, and the third fitting expression. In this embodiment, if Figure 2 As shown, multiple pixel regions 10 are arranged along the X-direction of the sample mask 1, which is also the rolling extension direction of the metal thin film raw material roll. In this case, the designated 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. Fitting is performed using the X coordinates of the designated points on the first line L1, the second line L2, and the third line L3 as independent variables, and the Y coordinates and the sum of the Y-direction deviations as dependent variables, to obtain the first, second, and third fitting expressions. If the arrangement direction of the pixel regions 10 coincides with the rolling extension direction of the metal thin film raw material roll, then the preferred fitting method is to use the coordinate values in the extension direction as the independent variable, and the coordinate values and the sum of the deviation values in the non-extension direction of the film plane as the dependent variable.

[0056] 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, based on the data distribution pattern, the first fitting expression, the second fitting expression, and the third fitting expression should all be monomial fitting, or the first fitting expression, the second fitting expression, and the third fitting expression should all be binomial fitting, or the first fitting expression, the second fitting expression, and the third fitting expression should all be trinomial fitting. If the first fitting expression, the second fitting expression, and the third fitting expression use different fitting methods, it means that the straightness data of the entire sample mask 1 does not have a unified trend, and in this case, it is not suitable to directly perform subsequent compensation actions.

[0057] Optionally, if a monomial is selected for fitting, when the linear coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the compensation value is calculated; if a binomial is selected for fitting, when the quadratic coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, and the numerical difference between the linear coefficients is less than 0.000001, the compensation value is calculated; if a trinomial is selected for fitting, when the cubic coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the quadratic coefficients are the same, and the numerical difference between the linear coefficients is less than 0.000001, the compensation value is calculated.

[0058] In this embodiment, when the first fitting expression, the second fitting expression, and the third fitting expression are all monomial fits, 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 means that the mask produced by the material roll has a consistent trend of pixel position accuracy deviation in the Y direction with the X direction as the independent variable. That is to say, after the raw material is manufactured into the mask, the straightness change pattern of the entire mask is uniform. In this case, subsequent compensation of the mask design layout of the target product can be directly performed.

[0059] When the first fitting expression, the second fitting expression and the third fitting expression are all binomial fitting, the first fitting expression is y=A1x 2 +B1x+C1, the second fitting expression is y=A2x 2 +B2x+C2, 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 means that the mask produced by the reel has a consistent trend in pixel position accuracy deviation in the Y direction with the X direction as the independent variable. In other words, after the raw material is manufactured into a mask, the straightness variation pattern of the entire mask is uniform. In this case, subsequent compensation of the target product's mask design layout can be directly carried out.

[0060] When the first fitting expression, the second fitting expression and the third fitting expression are all trinomial fitting, the first fitting expression is y=A1x 3 +B1x 2 +C1x+D1, the second fitting expression is y=A2x 3 +B2x 2 +C2x+D2, the third fitting expression is y=A3x 3 +B3x 2 +C3x+D3, when A1= A2= A3, and B1=B2=B3, and the numerical difference between C1, C2, and C3 is less than 0.000001, it means that the mask produced by the reel has a consistent trend of pixel position accuracy deviation in the Y direction with the X direction as the independent variable. That is to say, after the raw material is made into a mask, the straightness change pattern of the entire mask is uniform. In this case, subsequent compensation of the target product's mask design layout can be directly carried out.

[0061] Optionally, if the fitting curves of the first fitting expression and the third fitting expression are symmetrical about the fitting curve of the second fitting expression, the Y coordinates of the pixel openings in the mask design layout of the target product are zoned for compensation. In this embodiment, if the fitting curves of the first fitting expression and the third fitting expression are symmetrical about the fitting curve of the second fitting expression, it indicates that the pixel position accuracy deviation on the sample mask 1 gradually varies toward both sides about the center line L2. In this case, it is necessary to measure the pixel position accuracy deviation at multiple points on multiple lines along the X-direction between L1 and L2 and between L2 and L3, and fit the Y coordinates of the multiple measured points on each X-direction line and the relationship between the Y deviation and the X coordinate. The entire mask is divided into different regions by L1, L2, L3, and the multiple lines parallel to L1, L2, and L3 in between. Different fitting expressions are used for fitting and subsequent compensation in these different regions of the target product, which can achieve more accurate compensation.

[0062] 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 R-squared value is used to evaluate the goodness of fit of the regression model. The R-squared value is between 0 and 1. A higher R-squared value (close to 1) indicates that the model fits the data better, while a lower R-squared value (close to 0) indicates that the model fits the data poorly. Calculate R-squared ( ), you need to calculate the total sum of squares (SST), regression sum of squares (SSR) or residual sum of squares (SSE), the calculation formula is as follows:

[0063]

[0064]

[0065]

[0066]

[0067] in, is the i-th observation value, that is, the sum of the Y coordinate and Y deviation of the i-th specified point; is the mean value of the dependent variable y; n is the number of observations; is the fitted value of the ith observation, that is, the y value calculated by the fitting expression. Figure 2For example, to fit the pixel positions 101-115, 201-215, and 301-315, respectively, the value of n should be 15. Considering the deviation of the pixel opening positions across the entire metal mask, the R-squared values of the first, second, and third fitting expressions must all be greater than or equal to 0.99 to provide reliable data for subsequent compensation.

[0068] Those skilled in the art will appreciate that the steps, measures, and schemes in the various operations, methods, and processes discussed in the present invention may be interchanged, modified, combined, or deleted. Furthermore, other steps, measures, and schemes in the various operations, methods, and processes discussed in the present invention may also be interchanged, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and schemes in the prior art that are similar to those disclosed in the present invention may also be interchanged, modified, rearranged, decomposed, combined, or deleted.

[0069] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are 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 cannot be understood as limiting the present invention.

[0070] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0071] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0072] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0073] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, 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: include: Measuring the pixel position accuracy deviation of multiple designated points on multiple sample masks, wherein the pixel position accuracy deviation includes X-direction deviation and 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 deviations as dependent variables 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 deviations as dependent variables for fitting to obtain a fitting expression; Substituting the theoretical coordinate value of the first direction of the pixel opening point in the mask design layout of the target product into the fitting expression to obtain the fitting coordinate value of the second direction, and subtracting the theoretical coordinate value of the second direction from the fitting coordinate value to obtain the compensation value, wherein 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; The negative value of the compensation value of the pixel opening point is added to the theoretical coordinate value of the second direction to obtain the actual coordinate value, and the theoretical coordinate value of the second direction in the mask design layout is replaced by 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 designated point is the average of the X-direction deviations of the same designated point on the multiple sample masks, and the Y-direction deviation of the designated point is the average of the Y-direction deviations of the same designated point on the multiple sample masks.

3. The method for improving the straightness of a metal mask according to claim 1, wherein: If the average X-direction deviations of the multiple designated points are less than or equal to a first deviation threshold, and the average Y-direction deviations of the multiple designated points are greater than the first deviation threshold, selecting the X coordinates of the multiple designated points as independent variables; If the mean Y-direction deviation of the multiple designated points is less than or equal to the first deviation threshold, and the mean X-direction deviation of the multiple designated points is greater than the first deviation threshold, the Y coordinates of the multiple designated points are selected as independent variables.

4. The method for improving the straightness of a metal mask according to claim 1, wherein: When the average value of the X-direction deviations of the plurality of designated points is greater than a first deviation threshold, and the average value of the Y-direction deviations of the plurality of designated points is greater than the first deviation threshold; If the mean X-direction deviations of the plurality of designated points are less than the mean Y-direction deviations, a first fitting is performed using the X-coordinates of the plurality of designated points as independent variables, the Y-coordinates of the pixel opening points of the photomask design layout of the sample mask are compensated, a new sample mask is manufactured, the plurality of designated points are measured on the new sample mask, and a second fitting is performed using the Y-coordinates of the plurality of designated points as independent variables based on the measurement results of the new sample mask; If the mean Y-direction deviations of the plurality of designated points are less than the mean X-direction deviations, a first fitting is performed using the Y coordinates of the plurality of designated points as independent variables, and after compensating the X coordinates of the pixel opening points of the photomask design layout of the sample mask, a new sample mask is manufactured, and the plurality of designated points are measured on the new sample mask. Based on the measurement results of the new sample mask, a second fitting is performed using the X coordinates of the plurality of designated points as independent variables.

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, wherein: The sample mask includes a pixel area, the shape of the pixel area is rectangular, and the multiple designated points include at least the four corners of the rectangle, the midpoints of the four sides of the rectangle and the pixel opening point at the center of the rectangle.

7. The method for improving the straightness of a metal mask according to claim 6, wherein: The plurality of pixel areas are arranged along the X direction of the sample mask, and the plurality of designated points of the plurality of pixel areas are connected along the X direction to form a first line, a second line, and a third line, respectively. The X coordinates of the designated points on the first line, the second line, and the third line are used as independent variables, and the sum of the Y coordinate and the Y-direction deviation is used as the dependent variable for fitting to obtain a first fitting expression, a second fitting expression, and a third fitting expression.

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

9. The method for improving the straightness of a metal mask according to claim 8, wherein: If a monomial is selected for fitting, when the linear term 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 quadratic 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 linear term coefficients is less than 0.000001, the compensation value is calculated; If the trinomial is selected for fitting, the compensation value is calculated when the cubic term coefficients of the first fitting expression, the second fitting expression, and the third fitting expression are the same, the quadratic term coefficients are the same, and the numerical difference between the linear term coefficients is less than 0.000001.

10. The method for improving the straightness of a metal mask according to claim 7, wherein: If the fitting curve of the first fitting expression and the fitting curve of the third fitting expression are symmetrical about the fitting curve of the second fitting expression, partition compensation is performed on the Y coordinates of the pixel opening points of the mask design layout of the target product.

11. The method for improving the straightness of a metal mask according to claim 7, wherein: 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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