Mask plate and method for calibrating a photolithography machine

Abstract

The application provides a mask plate and a calibration method of a photoetching machine. The measurement mark on the mask plate comprises a first pattern and a second pattern, the first pattern and the second pattern have a common point, and the first pattern and the second pattern are provided with scale patterns. In the calibration process, the standard photoetching machine is taken as a reference, the measurement mark is exposed on the standard photoetching machine and the photoetching machine to be calibrated respectively, the deviation of the common point is directly read and the parameter is corrected, the calibration of the field center is realized, the error of the exposure field size and the wafer placement error can be obtained through direct reading and calculation. The measurement mark can not only obtain the two-degree-of-freedom position deviation, but also obtain the rotation deviation, and the measurement precision of the wafer placement error is improved. In addition, the photoetching machine to be calibrated can be taken as a reference datum, and the relative displacement of the wafer placement under different wafer placement angles can be calibrated. Therefore, the application not only improves the calibration efficiency and guarantees the precision of photoetching, but also has diversified application scenes, good universality and wide application range.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing technology, and in particular to a calibration method for a photomask and a photolithography machine. Background Technology

[0002] As lithography nodes continue to advance, the requirements for various performance indicators of lithography technology are also becoming increasingly stringent, especially the requirements for lithography precision. However, many factors affect lithography precision, such as the wafer mounting angle, alignment, and field of view, all of which can cause a series of errors, resulting in low precision. Furthermore, since the size of the pattern formed on the silicon wafer is mainly determined by the variable slit in the lithography machine, certain errors can occur in the control of the variable slit during the actual lithography machine debugging stage and chip manufacturing process. Therefore, to avoid the impact of these errors on lithography, necessary calibration checks need to be performed at each stage of the lithography process.

[0003] In the lithography machine debugging phase, small field-of-view apertures (1mm*1mm, 0.5mm*0.5mm) are often used for image quality data testing and experiments. Engineers need to spend a significant amount of time repeatedly calibrating and verifying the accuracy of the small field-of-view aperture to ensure accurate data measurement. However, existing detection techniques are limited and cannot verify from multiple angles. During chip mass production, to improve yield, a wafer is densely packed with chips arranged in a grid pattern. This requires the lithography machine to have not only precise positioning but also extremely precise opening accuracy and center position of the variable slit during exposure. From the perspective of the lithography machine subsystem, the field of view size describes the motion accuracy of the variable blades in the exposure system. Ideally, when each blade moves to a designated position, its opening size should match the set value. However, in actual debugging, hardware processing and installation issues often lead to deviations in actual motion. Towards the end of lithography machine development, tests such as pupil and wavelet aberration are frequently performed, and the accuracy of the field of view aperture size determines the validity of these test results. When test results are abnormal, simulation methods can be used to simulate the situation and then check each case one by one, resulting in a large consumption of manpower and material resources and seriously affecting process efficiency.

[0004] Therefore, a new calibration method for lithography machines is needed to achieve rapid and accurate measurement of field error and overlay error, so as to ensure the accuracy of lithography. Summary of the Invention

[0005] The purpose of this invention is to provide a calibration method for a photomask and a lithography machine to solve the problems of how to accurately calibrate the center of the exposure field of view and measure at least one of the field of view size error and the loading error.

[0006] To solve the above-mentioned technical problems, the present invention provides a mask template, including a body and measurement marks formed on the body;

[0007] The measurement mark includes: a first graphic and a second graphic; the first graphic extends along a first direction, and the second graphic extends along a second direction; and the first graphic and the second graphic have a common point, which is located at the midpoint of the first graphic; and both the first graphic and the second graphic are provided with scale graphics.

[0008] The common point of the measurement mark is located at the center of the body, and the two ends of the first graphic are located at the edges of the body, and at least one end of the second graphic is located at the edge of the body.

[0009] Optionally, in the photomask, the scale pattern is comb-shaped, including multiple serrations; the multiple serrations are arranged at equal intervals along the extension direction of the first pattern and at equal intervals along the extension direction of the second pattern.

[0010] Optionally, in the mask template, all the serrations provided on the first pattern divide the first pattern into multiple equal parts; and all the serrations provided on the second pattern divide the second pattern into multiple equal parts.

[0011] Optionally, in the mask template, a number of consecutively arranged saw teeth form a scale unit, and the height of the first or last saw tooth in a scale unit is greater than the height of the remaining saw teeth.

[0012] Optionally, in the mask template, the measurement mark further includes a digital graphic to identify the corresponding scale unit.

[0013] Optionally, in the mask template, one of the scale units includes ten of the serrations.

[0014] Optionally, in the mask template, the shape of the serrations includes rectangles.

[0015] Optionally, in the mask template, each of the serrations has the same width.

[0016] Optionally, in the mask template, the first direction and the second direction are perpendicular to each other.

[0017] Optionally, in the mask template, the shape of the measuring mark includes a cross shape or a T shape.

[0018] Optionally, in the photomask, the length of the first pattern along the first direction is greater than or equal to 26 mm; and the length of the second pattern along the second direction is greater than or equal to 33 mm.

[0019] Optionally, in the mask template, at least one alignment mark is also formed on the mask template, and the at least one alignment mark is distributed along the edge of the body.

[0020] Optionally, in the mask template, the body is rectangular, and at least one alignment mark is formed at each of the four corners of the body.

[0021] Optionally, in the mask template, the alignment mark includes at least one alignment pattern, and all the alignment patterns on the body are separated by a set rotation angle.

[0022] Optionally, in the mask template, the rotation angle includes at least one of 0°, 90°, 180°, and 270°.

[0023] Based on the same inventive concept, the present invention also provides a calibration method for a lithography machine, comprising:

[0024] Step 1: Place the photomask into a standard photolithography machine, expose at least one first test piece, and use at least one exposure field of view to expose and form at least one first measurement mark;

[0025] Step 2: Place the photomask into the lithography machine to be calibrated, and expose at least one first test piece simultaneously using the same exposure field of view to form a second measurement mark on each first test piece;

[0026] Step 3: Based on the scale pattern, read the deviation value of the common point of the second measurement mark relative to the common point of the first measurement mark in the first direction and the second direction;

[0027] Step 4: Determine whether the deviation value is within the threshold range. If yes, complete the exposure field center calibration of the lithography machine to be calibrated. If no, modify the parameters of the lithography machine to be calibrated and execute Step 2 until the deviation value converges to the threshold range.

[0028] Optionally, in the calibration method of the lithography machine, in step three, the average value of the differences between the common points of all the second measurement marks and the corresponding common points of the first measurement marks in the first direction and the second direction is calculated as the deviation value.

[0029] Optionally, in the calibration method of the lithography machine, the same loading angle is used in both step one and step two.

[0030] Based on the same inventive concept, the present invention also provides a calibration method for a lithography machine, comprising:

[0031] The photomask is placed in the lithography machine to be calibrated, and at least one second test piece is exposed simultaneously. At least one exposure field of view is used to expose and form at least one third measurement mark.

[0032] Based on the scale pattern, read the values ​​at the opposite ends of the first and second patterns in all the third measurement marks to obtain the size of the exposure field of view;

[0033] The size of the obtained exposure field of view is compared with the size set before exposure to obtain the exposure field of view error.

[0034] Optionally, in the calibration method of the lithography machine, the average value of the values ​​of the first and second patterns at opposite ends in all the third measurement marks is calculated as the size of the exposure field of view.

[0035] Optionally, in the lithography machine calibration method, the size of the photomask is greater than or equal to the exposure field of view.

[0036] Optionally, in the lithography machine calibration method, the two ends of the first pattern on the photomask are located at the edges of the body, and the two ends of the second pattern are located at the edges of the body.

[0037] Optionally, in the calibration method of the lithography machine, the shape of the measurement mark on the photomask is cross-shaped.

[0038] Based on the same inventive concept, the present invention also provides a calibration method for a lithography machine, comprising:

[0039] The photomask is placed in a standard lithography machine, at least one third test piece is exposed simultaneously, and at least one exposure field of view is used to expose and form at least one fourth measurement mark;

[0040] The photomask is placed in the lithography machine to be calibrated, and the same exposure field of view and the same loading angle are used to expose at least one third test piece at the same time to form a fifth measurement mark on each of the third test pieces;

[0041] Based on the scale pattern, the deviation values ​​between the common points on all the fourth measurement marks and the corresponding common points on the fifth measurement marks are read, and the wafer offset of the lithography machine to be calibrated is calculated.

[0042] Optionally, in the lithography machine calibration method, the wafer offset includes an offset along a first direction, an offset along a second direction, and a rotational offset.

[0043] Optionally, in the calibration method of the lithography machine, the rotation offset θ satisfies the following formula: tanθ=(a 2 -b 2 ) / 2ab;

[0044] Where a is the offset along the first direction, b is the offset along the second direction, and the first direction and the second direction are perpendicular to each other.

[0045] Optionally, in the calibration method of the lithography machine, the deviation value includes a deviation value in a first direction and a deviation value in a second direction; the average value of all deviation values ​​in the first direction is calculated as the offset along the first direction, and the average value of all deviation values ​​in the second direction is calculated as the offset along the second direction.

[0046] Optionally, in the calibration method of the lithography machine, the loading angle of the third test wafer includes 0°, 90°, 180° and 270°.

[0047] Based on the same inventive concept, the present invention also provides a calibration method for a lithography machine, comprising:

[0048] The photomask is placed in the lithography machine to be calibrated, and at least one exposure field of view and the loading angle are set. At the same time, at least one fourth test piece is exposed to form at least one sixth measurement mark.

[0049] Multiple film loading angles are selected, and at each film loading angle, the same exposure field of view is used to expose at least one of the fourth test films to form at least one corresponding seventh measurement mark.

[0050] Based on the scale pattern, the deviation value between the common point on all the sixth measurement marks and the common point on the corresponding seventh measurement mark is read at each of the above-mentioned loading angles, and the loading offset of each loading angle of the lithography machine to be calibrated relative to the set loading angle is calculated.

[0051] Optionally, in the lithography machine calibration method, the wafer offset includes an offset along a first direction, an offset along a second direction, and a rotational offset.

[0052] Optionally, in the calibration method of the lithography machine, the rotation offset θ satisfies the following formula: tanθ=(a 2 -b 2 ) / 2ab;

[0053] Where a is the offset along the first direction, b is the offset along the second direction, and the first direction and the second direction are perpendicular to each other.

[0054] Optionally, in the calibration method of the lithography machine, the deviation value includes a deviation value in a first direction and a deviation value in a second direction; the average value of all deviation values ​​in the first direction at each of the above-mount angles is calculated as the offset along the first direction, and the average value of all deviation values ​​in the second direction at each of the above-mount angles is calculated as the offset along the second direction.

[0055] Optionally, in the calibration method of the lithography machine, the setting of the wafer loading angle includes 0°.

[0056] Optionally, in the calibration method of the lithography machine, the various loading angles include 90°, 180° and 270°.

[0057] In summary, this invention provides a photomask and a calibration method for a lithography machine. The photomask includes a body and measurement marks formed on the body. The measurement marks include a first pattern and a second pattern. The first pattern extends along a first direction, and the second pattern extends along a second direction. The first and second patterns share a common point located at the midpoint of the first pattern. Both the first and second patterns are provided with scale patterns for direct reading of deviation values. The common point of the measurement marks is located at the center of the body, and the opposite ends of the first pattern are located at the edges of the body, while at least one end of the second pattern is located at the edge of the body, thus identifying the size of the photomask and consequently the size of the exposure field of view.

[0058] Therefore, during the calibration of a lithography machine, a standard lithography machine can be used as a reference. Measurement marks are exposed on both the standard and the lithography machine to be calibrated. By directly reading the offset of the common point and correcting the lithography machine parameters, the center of the field of view can be calibrated. Alternatively, the size of the exposure field of view can be obtained by directly reading the values ​​at the opposite ends of the first and second patterns, and then the accurate exposure field of view size error can be calculated. Furthermore, the wafer loading error can be obtained by directly reading the deviation between the two common points. Moreover, the measurement marks not only allow for the direct acquisition of the two-degree-of-freedom positional deviation within the same plane but also the rotational deviation, improving the measurement accuracy and efficiency of wafer loading error. In addition, the lithography machine to be calibrated can be used as a reference to calibrate the relative offset of the wafer loading at different loading angles. Therefore, this invention not only improves calibration efficiency and ensures lithography accuracy but also has diverse applications, good versatility, and a wide range of applicability. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structure of a mask template in an embodiment of the present invention;

[0060] Figure 2 This is a schematic diagram of the first and second measurement marks in an embodiment of the present invention;

[0061] Figure 3 This is a schematic diagram of an exposure field distribution in an embodiment of the present invention;

[0062] Figure 4 This is a schematic diagram of an exposure field distribution in an embodiment of the present invention;

[0063] Figure 5 This is a schematic diagram illustrating the measurement of the exposure field size in an embodiment of the present invention.

[0064] Figure 6 This is a schematic diagram showing that there is a rotational deviation between the two measuring marks in an embodiment of the present invention. Detailed Implementation

[0065] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clearly illustrate the objectives of the embodiments of the present invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and sometimes use different scales. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate the logical or sequential relationships between the various components, elements, steps, etc.

[0066] To address the aforementioned technical problems, this embodiment provides a mask template. Please refer to [link / reference]. Figure 1 The mask template includes a body 100 and at least one measurement mark formed on the body 100. The measurement mark includes a first shape Lx and a second shape Ly. The first shape Lx extends along a first direction, and the second shape Ly extends along a second direction; wherein the first shape Lx and the second shape Ly have a common point O, and the common point O is located at the midpoint of the first shape Lx. In other words, the first shape Lx and the second shape Ly are two line segments that intersect perpendicularly or at an angle, and the intersection point is the midpoint of the first shape Lx. Preferably, the first direction and the second direction are perpendicular to each other, then the shape of the measurement mark includes a cross shape or a T-shape. Furthermore, both the first shape Lx and the second shape Ly are provided with scale patterns for measuring the size of the object to be measured.

[0067] Furthermore, the common point O of the measurement marks is located at the center of the body 100, and the two opposite ends of the first graphic Lx are located at the edge of the body 100, while at least one end of the second graphic Ly is located at the edge of the body 100. That is, the first graphic Lx extends along the first direction, and both ends reach the edge of the body 100. Similarly, the second graphic Ly extends along the second direction, and at least one end reaches the edge of the body 100. That is, when the measurement mark is cross-shaped, the second graphic Ly intersects with the first graphic Lx, and the two opposite ends of the second graphic Ly, like the two opposite ends of the first graphic Lx, both extend to the edge of the body 100. In addition, for ease of reading the scale, the common point O is the midpoint of the first graphic Lx and the second graphic Ly. When the measurement mark is T-shaped, one end of the second graphic Ly connects to the midpoint of the first graphic Lx, and the other end extends to the edge of the body 100.

[0068] Furthermore, such as Figure 1 As shown in the enlarged view of the dashed circle, the scale pattern is comb-shaped, including multiple serrations. These serrations are evenly spaced along the extension direction of the first pattern Lx and the second pattern Ly. Furthermore, all the serrations on the first pattern Lx divide it into multiple equal parts; and all the serrations on the second pattern Ly divide it into multiple equal parts. That is, the first pattern Lx and the second pattern Ly resemble a ruler, with multiple serrations marking predetermined graduation values. The graduation value X2 of the first pattern Lx and the graduation value of the second pattern Ly can be the same or different. Preferably, the graduation value X2 of the first pattern Lx and the second pattern Ly are the same, and the width X1 of the serrations is also the same. Preferably, X1 = X2 = 2 micrometers. Of course, the size of the graduation value needs to be determined according to the accuracy requirements of different manufacturing processes. Furthermore, the shape of the sawtooth includes, but is not limited to, a rectangle, and is disposed on one or both sides of the first graphic Lx and the second graphic Ly.

[0069] Furthermore, a series of consecutively arranged saw teeth form a scale unit P, and the height of the first or last saw tooth in a scale unit P is greater than the height of the remaining saw teeth. For example... Figure 1 As shown in the enlarged view of the dashed circle, one scale unit P includes ten serrations. Therefore, when X1 = X2 = 2 micrometers, P = 40 micrometers. Of course, it can also have three, five, six, eight, nine, fifteen, or twenty serrations, etc., and this embodiment does not limit this. Furthermore, Figure 1The height of the last serration of a scale unit P is greater than that of the remaining serrations for ease of identification. Preferably, the height of the last or first serration is twice that of the remaining serrations. The measurement mark also includes a numerical graphic to identify the corresponding scale unit P. Figure 1 As shown, the digital graphics 0, 40, 80, 120, etc. are respectively set at the first and last positions near each of the scale units P to further facilitate the reading of the measurement values.

[0070] Furthermore, the length of the first pattern Lx along the first direction is greater than or equal to 26 mm; the length of the second pattern Ly along the second direction is greater than or equal to 33 mm. The purpose is to ensure that the dimensions of the first pattern Lx and the second pattern Ly are greater than or equal to the field of view of a typical photolithography image, thereby enabling the measurement of the field of view.

[0071] Furthermore, at least one alignment mark 101 is formed on the photomask, and the at least one alignment mark 101 is distributed along the edge of the body 100. When the body 100 is rectangular, at least one alignment mark 101 is formed at each of the four corners of the body 100 for pre-exposure alignment. The alignment mark 101 includes at least one alignment pattern 1011, and all alignment patterns 1011 on the body 100 are separated by a set rotation angle. The rotation angle can be 0°, 90°, 180°, or 270°, or other set angles. In this embodiment, the alignment mark 101 and the alignment pattern 1011 are not limited, and their values ​​can be determined as needed.

[0072] Based on the same inventive concept, this embodiment also provides a calibration method for a lithography machine, used to calibrate the center of the exposure field of view. Please refer to [link to relevant documentation]. Figure 2-4 Using the above-mentioned mask template, the method includes:

[0073] Step 1: Place the photomask into a standard lithography machine, that is, use the standard lithography machine as a reference standard, and expose at least one first test piece, optionally ten or more, and use at least one exposure field of view to expose and form at least one first measurement mark (Lx1, Ly1).

[0074] Specifically, a photoresist layer is coated on the first test wafer. Through photolithography, measurement marks from the photomask are imprinted onto the photoresist layer. Then, through an etching process, using the photoresist layer as a barrier, the first measurement marks (Lx1, Ly1) are formed on at least one first test wafer. That is, the first measurement marks from the photomask are imprinted on each of the first test wafers, forming the first measurement marks (Lx1, Ly1) on the test wafer. The selected first test wafer can be a standard test wafer or a non-standard process wafer. Preferably, the wafer mounting angle is 0 degrees.

[0075] Furthermore, such as Figure 3-4 As shown, the exposure field of view M is preferably located near the center of the wafer. To ensure calibration accuracy, multiple exposure fields of view M of different sizes can be used, with each field of view using two or more identical sizes. Alternatively, multiple identical exposure sizes can be set. Furthermore, the size of the exposure field of view M can be: 26mm*33mm, 22mm*22mm, 26mm*15mm, 10mm*10mm, 1mm*1mm, or 0.5mm*0.5mm, etc.

[0076] Step 2: Place the photomask into the lithography machine to be calibrated, and expose at least one first test piece simultaneously under the same exposure field of view and the same loading angle, i.e., under the same exposure conditions, so as to form a second measurement mark (Lx2, Ly2) on each first test piece.

[0077] That is, by coating a photoresist layer, the second measurement marks (Lx2, Ly2) are formed by exposing the photoresist layer under the same exposure conditions in the lithography machine to be calibrated.

[0078] Step 3: Based on the scale pattern, read the deviation value of the common point O' of the second measurement mark (Lx2, Ly2) relative to the common point O of the first measurement mark (Lx1, Ly1) in the first direction and the second direction.

[0079] like Figure 2 As shown, by observing with an optical microscope and using the scale patterns on the first measurement marks (Lx1, Ly1) and the second measurement marks (Lx2, Ly2), the common point O' and the deviation values ​​(Tx1, Ty1) of the common point O in the first direction and the second direction can be directly read. The first direction and the second direction are perpendicular to each other. Further, the average value of all deviation values ​​in the first direction and the average value of all deviation values ​​in the second direction are calculated as the deviation values ​​used for judgment in step four.

[0080] Step 4: Determine whether the deviation value is within the threshold range. If yes, the exposure field center calibration of the lithography machine to be calibrated is completed; that is, the exposure field center of the lithography machine to be calibrated is close to the exposure field center of the standard lithography machine, and no parameter correction is required. If not, modify the parameters of the lithography machine to be calibrated and execute Step 2 until the deviation value converges to the threshold range. That is, after correcting the parameters, recoat the photoresist layer, expose to form the second measurement marks (Lx2, Ly2) and observe until the deviation value converges to the threshold range, thus completing the exposure field center calibration of the lithography machine to be calibrated. Note that this embodiment does not limit the threshold range and can be determined according to the requirements of lithography accuracy.

[0081] Therefore, the calibration method for the lithography machine provided in this embodiment can calibrate the center of the exposure field of view of the lithography machine to be calibrated, which is beneficial to improving the lithography accuracy of the lithography machine and increasing the product yield.

[0082] Based on the same inventive concept, this embodiment also provides a calibration method for a lithography machine, used to measure the exposure field size error. Please refer to [link to relevant documentation]. Figure 5 The method includes:

[0083] Step 1: Place the photomask into the lithography machine to be calibrated, simultaneously expose at least one second test wafer, and use at least one exposure field of view to form at least one third measurement mark (Lx3, Ly3); wherein, the exposure field of view M is preferably located near the center of the wafer, such as... Figure 3-4 The first step, namely forming the third measurement mark (Lx3, Ly3) on each of the second test pieces, can be understood by referring to the above description of the exposure process.

[0084] Step 2: According to the scale pattern, read the values ​​at both ends of the first and second graphics in all the third measurement marks (Lx3, Ly3), and calculate the average value of the values ​​at both ends of the first and second graphics in all the third measurement marks (Lx3, Ly3) as the size of the exposure field of view; compare the obtained size of the exposure field of view with the size set before exposure to obtain the exposure field of view error.

[0085] The size of the photomask is greater than or equal to the exposure field of view to ensure that the entire exposure field of view passes through the photomask. Furthermore, the measurement marks on the photomask are cross-shaped. The opposite ends of the first graphic on the photomask are located at the edges of the main body, and the opposite ends of the second graphic are also located at the edges of the main body. This ensures that readings can be obtained for the horizontal left (Lx-left), horizontal right (Lx-right), vertical upper (Ly-up), and vertical lower (Ly-down) dimensions of the exposure field of view, allowing for clear and convenient acquisition of the exposure field of view's size. Figure 5 The measurement marks represented by the black lines in the image represent the exposed pattern within the field of view, while the white measurement marks represent the unexposed portion of the photomask. The boundary between these two marks represents the readings of the exposure field of view Lx-left, Lx-right, Ly-up, and Ly-down. Therefore, using the photomask provided in this embodiment, the size of the exposure field of view of the lithography machine to be calibrated can be directly obtained, thereby acquiring the error value of the exposure field of view. This not only improves detection efficiency but also ensures error detection accuracy.

[0086] Based on the same inventive concept, this embodiment also provides a calibration method for a lithography machine, used to accurately measure the wafer loading error of the lithography machine. Please refer to [link to relevant documentation]. Figure 3-4 And 6, the method includes:

[0087] Step 1: Place the photomask into a standard lithography machine. Using the standard lithography machine as a reference, simultaneously expose at least one third test wafer and employ at least one exposure field of view to form at least one fourth measurement mark (Lx4, Ly4). Preferably, the exposure field of view M is located near the center of the wafer. Figure 3-4 The first step, namely forming the fourth measurement mark (Lx4, Ly4) on each of the third test pieces, can be understood by referring to the above description of the exposure process.

[0088] Step 2: Place the photomask into the lithography machine to be calibrated, using the same exposure field of view and the same loading angle, i.e. the same exposure conditions, and expose at least one third test piece at the same time to form a fifth measurement mark (Lx5, Ly5) on each of the third test pieces.

[0089] Step 3: Based on the scale pattern, read the deviation values ​​between the common point O on all the fourth measurement marks (Lx4, Ly4) and the common point O' on the corresponding fifth measurement marks (Lx5, Ly5), and calculate the wafer offset of the lithography machine to be calibrated. The wafer offset includes the offset along the first direction, the offset along the second direction, and the rotational offset.

[0090] Furthermore, through trigonometric function calculations, the rotational offset θ satisfies the following formula:

[0091] tanθ=(a 2 -b 2 ) / 2ab;

[0092] Where 'a' represents the offset along the first direction and 'b' represents the offset along the second direction, and the first and second directions are perpendicular to each other. Furthermore, the deviation value includes the deviation value in the first direction and the deviation value in the second direction; since the deviation values ​​in the first and second directions can be directly read, the average of all deviation values ​​in the first direction is calculated as the offset 'a' along the first direction, and the average of all deviation values ​​in the second direction is calculated as the offset 'b' along the second direction.

[0093] Furthermore, the upper angle of the second test piece in both step one and step two is the same, and is not limited to 0°, 90°, 180° or 270°.

[0094] Therefore, under the action of the mask template, the offset of two common points (O, O') can be conveniently read through the scale pattern. Not only can the positional deviation of two degrees of freedom in the same plane be directly obtained, but the rotational deviation can also be obtained, which improves the measurement accuracy of the film loading error.

[0095] Based on the same inventive concept, this embodiment also provides a calibration method for a lithography machine, used for self-checking wafer loading errors in the absence of a standard lithography machine. Please refer to [link to relevant documentation]. Figure 3-4 And 6, the method includes:

[0096] Step 1: Place the photomask into the lithography machine to be calibrated, use at least one exposure field of view and set the loading angle, and expose at least one fourth test piece at the same time to form at least one sixth measurement mark (Lx6, Ly6).

[0097] The preferred setting for the wafer loading angle is 0°. This is because, in actual process operations, a 0° loading angle is closer to the standard 0° loading angle of a lithography machine. Therefore, in the absence of a standard lithography machine for reference, using a 0° loading angle as the reference standard for detecting other loading angles is more accurate. Furthermore, the exposure field of view M is preferably located near the center of the wafer, such as... Figure 3-4 .

[0098] Step Two: Select multiple loading angles. Under each loading angle, use the same exposure field of view, i.e., under the same exposure conditions, expose at least one of the fourth test pieces to form at least one corresponding seventh measurement mark (Lx7, Ly7). Specifically, coat the fourth test piece with a photoresist layer and form the seventh measurement mark (Lx7, Ly7) on the photoresist layer. The multiple loading angles include, but are not limited to, 90°, 180°, and 270°. Before loading, a preliminary calibration can be performed by forming a pattern on the fourth test piece based on the alignment marks on the photomask. The alignment marks generally include 0°, 90°, 180°, and 270°, and can be modified as needed to ensure consistency with the loading angle.

[0099] Step 3: Based on the scale pattern, read the deviation value between the common point O on all the sixth measurement marks (Lx6, Ly6) and the common point O' on the corresponding seventh measurement marks (Lx7, Ly7) at each of the above-mentioned loading angles, and calculate the loading offset of the lithography machine to be calibrated relative to the set loading angle for each loading angle. For example, by reading the deviation value between the common point O on all the sixth measurement marks (Lx6, Ly6) and the common point O' on the corresponding seventh measurement marks (Lx7, Ly7) at a 90° loading angle, the loading offset of the lithography machine to be calibrated at a 90° loading angle relative to a 0° loading angle can be calculated.

[0100] Similarly, the upper offset includes an offset along the first direction, an offset along the second direction, and a rotational offset. The rotational offset θ satisfies the following formula: tanθ=(a 2 -b 2 ) / 2ab;

[0101] Where 'a' represents the offset along the first direction and 'b' represents the offset along the second direction, and the first and second directions are perpendicular to each other. The deviation value includes the deviation value in the first direction and the deviation value in the second direction; since the deviation values ​​in the first direction and the deviation values ​​in the second direction can be directly read and obtained, the average value of all deviation values ​​in the first direction under each of the above-film angles is calculated as the offset along the first direction, and the average value of all deviation values ​​in the second direction under each of the above-film angles is calculated as the offset along the second direction.

[0102] In summary, the photomask and lithography machine calibration method provided in this embodiment allows for the calibration of the lithography machine by using a standard lithography machine as a reference. Measurement marks are exposed on both the standard and the lithography machine to be calibrated. The offset of the common point is directly read, and the lithography machine parameters are corrected to calibrate the center of the field of view. Alternatively, the size of the exposure field of view can be obtained by directly reading the values ​​at the opposite ends of the first and second patterns, thereby calculating the accurate exposure field of view size error. Furthermore, the deviation between the two common points can be directly read to obtain the wafer loading error. Moreover, the measurement marks not only directly provide the positional deviation of two degrees of freedom within the same plane but also the rotational deviation, improving the measurement accuracy and efficiency of the wafer loading error. Additionally, the lithography machine to be calibrated can be used as a reference to calibrate the relative offset of the wafer loading at different loading angles. Therefore, this embodiment not only improves calibration efficiency and ensures lithography accuracy but also has diverse application scenarios, good versatility, and a wide range of applications.

[0103] The preferred embodiments have been disclosed above; however, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A mask plate, characterized by, The measuring mark comprises a body and a measuring mark formed on the body; The measuring mark comprises a first pattern and a second pattern; the first pattern extends along a first direction, the second pattern extends along a second direction; and the first pattern and the second pattern have a common point, the common point is located at the midpoint of the first pattern; and the first pattern and the second pattern are provided with a scale pattern; The common point of the measuring mark is located at the center of the body, and the opposite ends of the first pattern are located at the edges of the body, and at least one end of the second pattern is located at the edge of the body; And the mask plate is further provided with at least one alignment mark, the at least one alignment mark is distributed along the edge of the body; the alignment mark comprises at least one alignment pattern, and all the alignment patterns on the body are different by a set rotation angle, which is used for aligning different upper sheet angles.

2. The mask plate according to claim 1, wherein The scale pattern is comb-shaped and comprises a plurality of sawteeth; the plurality of sawteeth are arranged at equal intervals along the extension direction of the first pattern and along the extension direction of the second pattern.

3. The mask plate according to claim 2, wherein All the sawteeth arranged on the first pattern divide the first pattern into a plurality of equal parts; and all the sawteeth arranged on the second pattern divide the second pattern into a plurality of equal parts.

4. The mask plate according to claim 2, wherein A set number of the sawteeth arranged continuously form a scale unit, and the height of the sawteeth in the first order or the last order in the scale unit is greater than the height of the remaining sawteeth.

5. The mask plate according to claim 4, wherein The measuring mark further comprises a digital pattern to identify the corresponding scale unit.

6. The mask plate according to claim 4, wherein One scale unit comprises ten sawteeth.

7. The reticle of claim 2, wherein, The shape of the sawteeth comprises a rectangle.

8. The mask plate of claim 2, wherein, The width of each sawtooth is the same.

9. The reticle of claim 1, wherein, The first direction and the second direction are perpendicular to each other.

10. The reticle of claim 1, wherein, The shape of the measuring mark comprises a cross or a T shape.

11. The reticle of claim 1, wherein, The length of the first pattern along the first direction is greater than or equal to 26 mm; and the length of the second pattern along the second direction is greater than or equal to 33 mm.

12. The reticle of claim 1, wherein, The body is rectangular, and at least one alignment mark is formed at each of the four corners of the body.

13. The reticle of claim 1, wherein, The rotation angle comprises at least one of 0°, 90°, 180° and 270°.

14. A method of calibrating a lithographic machine, characterized by, The mask plate according to any one of claims 1-13 is used, comprising: Step 1: placing the mask plate into a standard photolithography machine, exposing at least one first test sheet, and using at least one exposure field of view to form at least one first measuring mark; Step 2: placing the mask plate into a photolithography machine to be calibrated, using the same exposure field of view to expose the at least one first test sheet to form a second measuring mark on each first test sheet; Step 3: according to the scale pattern, reading the deviation value of the common point of the second measuring mark relative to the common point of the first measuring mark in the first direction and the second direction. Step four: judging whether the deviation value is within a threshold range, if yes, completing the exposure field center calibration of the to-be-calibrated lithography machine; if no, modifying the parameters of the to-be-calibrated lithography machine, executing step two until the deviation value converges to the threshold range.

15. The method of claim 14, wherein: In the step three, the average value of the difference values of the common points of all the second measurement marks relative to the common points of the corresponding first measurement marks in the first direction and the second direction is calculated as the deviation value.

16. The method of claim 14, wherein The same upper sheet angle is used in the step one and the step two.

17. A method of calibrating a lithographic machine, characterized by, Using the mask plate according to any one of claims 1-13, comprising: Placing the mask plate into the to-be-calibrated lithography machine, exposing at least one second test sheet, and using at least one exposure field to expose and form at least one third measurement mark; According to the scale pattern, reading the values of the first pattern and the second pattern at the two ends of all the third measurement marks to obtain the size of the exposure field; Comparing the obtained size of the exposure field with the size set before exposure to obtain the exposure field error.

18. The method of claim 17, wherein: The average value of the values of the first pattern and the second pattern at the two ends of all the third measurement marks is calculated as the size of the exposure field.

19. The method of claim 17, wherein: The size of the mask plate is greater than or equal to the exposure field.

20. The method of claim 17, wherein: The two ends of the first pattern on the mask plate are located at the edges of the body, and the two ends of the second pattern are located at the edges of the body.

21. The method of claim 17, wherein: The shape of the measurement mark on the mask plate is a cross shape.

22. A method of calibrating a lithographic machine, characterized by, Using the mask plate according to any one of claims 1-13, comprising: Placing the mask plate into the to-be-calibrated lithography machine, exposing at least one second test sheet, and using at least one exposure field to expose and form at least one third measurement mark; Placing the mask plate into the to-be-calibrated lithography machine, using the same exposure field and the same upper sheet angle to expose the at least one third test sheet at the same time to form a fifth measurement mark on each third test sheet; According to the scale pattern, reading the deviation value between the common points of all the fourth measurement marks and the corresponding common points of the fifth measurement marks, and calculating the upper sheet offset of the to-be-calibrated lithography machine.

23. The method of claim 22, wherein: The upper sheet offset includes an offset in a first direction, an offset in a second direction, and a rotation offset.

24. The method of claim 23, wherein: The rotation offset θ satisfies the following equation: tan θ = (a 2 -b 2 ) / 2ab; Wherein, a is the offset in the first direction, b is the offset in the second direction, and the first direction and the second direction are perpendicular to each other.

25. The method of claim 24, wherein: The deviation value includes a deviation value in a first direction and a deviation value in a second direction; the average value of all the deviation values in the first direction is calculated as the offset in the first direction, and the average value of all the deviation values in the second direction is calculated as the offset in the second direction.

26. The method of claim 22, wherein: The upper sheet angle of the third test sheet includes 0°, 90°, 180°, and 270°.

27. A method of calibrating a lithographic machine, characterized by, Using the mask plate according to any one of claims 1-13, comprising: placing the mask plate into a lithography machine to be calibrated, exposing at least one fourth test sheet by using at least one exposure field of view and setting a sheet loading angle, and forming at least one sixth measurement mark by exposure; selecting a plurality of sheet loading angles, and exposing at least one fourth test sheet by using the same exposure field of view at each of the sheet loading angles to form at least one seventh measurement mark corresponding to each of the sheet loading angles; reading deviation values between common points on all of the sixth measurement marks and common points on the corresponding seventh measurement marks at each of the sheet loading angles according to the calibration pattern, and calculating sheet loading offset amounts of each of the sheet loading angles of the lithography machine to be calibrated relative to the set sheet loading angle.

28. The method of claim 27, wherein: The sheet loading offset amounts include an offset amount in a first direction, an offset amount in a second direction, and a rotation offset amount.

29. The method of claim 28, wherein: The rotation offset θ satisfies the following equation: tan θ = (a 2 -b 2 ) / 2ab; Wherein a is the offset amount in the first direction, b is the offset amount in the second direction, and the first direction and the second direction are perpendicular to each other.

30. The method of calibrating a lithography machine of claim 29, wherein, The deviation values include deviation values in the first direction and deviation values in the second direction; an average of all of the deviation values in the first direction at each of the sheet loading angles is calculated as the offset amount in the first direction, and an average of all of the deviation values in the second direction at each of the sheet loading angles is calculated as the offset amount in the second direction.

31. The method of calibrating a lithography machine of claim 27, wherein, The set sheet loading angle includes 0°.

32. The method of calibrating a lithography machine of claim 27, wherein, The plurality of sheet loading angles include 90°, 180°, and 270°.

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