Film thickness standard sheet and preparation method thereof, and calibration method of film thickness measuring equipment

Abstract

The invention provides a film thickness standard sheet, a preparation method thereof and a calibration method of film thickness measuring equipment. According to the film thickness standard sheet, the groove and / or the bulge is formed on the substrate, and the thin film layer covers the groove and / or the bulge, so that the thickness value of the thin film layer on the standard sheet can be accurately obtained according to the size change of the groove and / or the bulge before and after the thin film layer is covered, and the requirement of the standard sheet is met. The film thickness standard sheet provided by the invention can be directly prepared by using existing equipment, so that the cost of the standard sheet is greatly reduced. Besides, under the condition that at least two calibration areas with different thickness grades are formed on the standard sheet at the same time, the same standard sheet can be used for calibrating a plurality of different thicknesses, so that the expenditure of the standard sheet is further saved, the sheet replacement process of a plurality of standard sheets is avoided, the calibration efficiency of the equipment is improved, and the calibration cost of the equipment is reduced. And the chip breaking risk easily caused in the chip changing process can be reduced.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a film thickness standard sheet and a preparation method thereof, and a calibration method for film thickness measuring equipment. Background Art

[0002] In the field of semiconductor processing, thin film layers can be deposited on substrates by physical or chemical methods, and processes such as photolithography and etching can be performed on the thin film layers to form circuit structures of various layers. After thin film deposition, the substrate with thin film deposition generally needs to be transferred to a film thickness measuring device for testing to measure the thickness of the thin film layer formed on the substrate. Therefore, film thickness measuring equipment plays an important role in this process, and it is extremely important to ensure the measurement accuracy of film thickness measuring equipment, and the measurement accuracy of film thickness measuring equipment can generally be guaranteed by regular calibration of the equipment.

[0003] Specifically, when calibrating the film thickness measuring device, it is necessary to use a standard film for calibration. A thin film layer of predetermined thickness is formed on the standard film. The film thickness measuring device is used to measure the thickness of the thin film layer on the standard film, and the measured value is compared with the thickness standard value of the thin film layer to determine whether the device has a high measurement accuracy. The standard films currently used generally need to be purchased separately, and they are expensive. In addition, a plurality of standard films of different thickness grades are usually provided so that the film thickness measuring device has corresponding standard films for calibration when performing a plurality of different thickness calibration processes, thereby ensuring the accuracy of the measuring device. However, when using multiple standard films for calibration, not only does it cost a high fee, but it also requires multiple loading and unloading of each standard film, which wastes time, reduces the output rate of the machine, and increases the risk of damage to the standard film during the transmission process. Summary of the invention

[0004] The object of the present invention is to provide a film thickness standard sheet and a preparation method thereof, so as to solve the problem that the film thickness standard sheet currently used is expensive.

[0005] In this regard, the present invention provides a film thickness standard sheet, comprising: a substrate and a thin film layer formed on the substrate, the substrate having at least one calibration area, and the thin film layer at least covering the calibration area. Wherein, at least one groove is formed in the calibration area of ​​the substrate, the groove has a first opening size, the thin film layer covers the groove and the top surface of the substrate, the thin film layer covers the groove and reduces the opening area of ​​the groove to a second opening size, and the thickness value of the thin film layer is obtained according to the difference between the first opening size and the second opening size; and / or, at least one protrusion is formed in the calibration area of ​​the substrate, the protrusion has a first width size, the thin film layer covers the protrusion and the top surface of the substrate, the thin film layer covers the protrusion to form a second width size, and the thickness value of the thin film layer is obtained according to the difference between the second width size and the first width size.

[0006] Optionally, at least two grooves are formed in the calibration area of ​​the substrate, and a first protrusion among the at least one protrusion is formed in a portion of the substrate corresponding to a portion between two adjacent grooves.

[0007] Optionally, the groove and the protrusion are formed in the calibration area of ​​the substrate, a first thickness value is obtained according to the first opening size and the second opening size, a second thickness value is obtained according to the first width size and the second width size, and the thickness value of the thin film layer is obtained based on the average value of the first thickness value and the second thickness value.

[0008] Optionally, an absolute value of a difference between the first thickness value and the second thickness value is less than or equal to a preset threshold.

[0009] Optionally, the at least one protrusion includes a second protrusion protruding from the top surface of the substrate.

[0010] Optionally, the inclination of the side wall of the groove is 85°-95°; and / or the inclination of the side wall of the protrusion is 85°-95°.

[0011] Optionally, the substrate has at least two calibration areas, and the thicknesses of the thin film layers formed in at least some of the calibration areas are different from each other.

[0012] Optionally, the substrate has at least two calibration areas, wherein a portion of the calibration areas is arranged in a central area of ​​the substrate, and another portion of the calibration areas is arranged in an edge area of ​​the substrate.

[0013] The present invention also provides a method for preparing a film thickness standard sheet, comprising the following steps. The first step is to provide a substrate, on which at least one calibration area is defined. The second step is to form at least one groove in the calibration area of ​​the substrate and obtain the first opening size of the groove; and / or, to form at least one protrusion in the calibration area of ​​the substrate and obtain the first width size of the protrusion. The third step is to form a thin film layer on the substrate, the thin film layer at least covers the calibration area; wherein, when a groove is formed in the calibration area, the second opening size of the opening area of ​​the groove after covering the thin film layer is obtained; when a protrusion is formed in the calibration area, the second width size of the protrusion after covering the thin film layer is obtained. The fourth step is to obtain the thickness value of the thin film layer according to the difference between the first opening size and the second opening size, and / or, the difference between the second width size and the first width size.

[0014] Optionally, at least two grooves are formed in the substrate, and a portion of the substrate corresponding to between adjacent grooves forms a first protrusion of the at least one protrusion.

[0015] Optionally, the groove and the protrusion are formed in the calibration area of ​​the substrate, and after obtaining the first thickness value according to the first opening size and the second opening size and obtaining the second thickness value according to the first width size and the second width size, it also includes: judging whether the absolute value of the difference between the first thickness value and the second thickness value is less than or equal to a preset threshold value; if so, the formed thin film layer meets the requirements of the standard film, and the thickness value of the thin film layer is obtained according to the first thickness value and the second thickness value; if not, rework is performed to reform the thin film layer until the absolute value of the difference between the first thickness value and the second thickness value obtained is less than or equal to the preset threshold value.

[0016] Optionally, the at least one protrusion includes a second protrusion protruding from the top surface of the substrate.

[0017] Optionally, the substrate has at least two calibration areas, and the thicknesses of the thin film layers formed in at least some of the calibration areas are different from each other.

[0018] Optionally, the at least two calibration areas include a first calibration area and a second calibration area, and the method for forming a first thin film layer in the first calibration area and a second thin film layer in the second calibration area includes: forming at least one groove and / or at least one protrusion in each calibration area of ​​the substrate; forming a first thin film layer in the first calibration area and obtaining a thickness value of the first thin film layer; and forming a second thin film layer in the second calibration area and obtaining a thickness value of the second thin film layer.

[0019] Optionally, the inclination of the side wall of the groove is 85°-95°; and / or the inclination of the side wall of the protrusion is 85°-95°.

[0020] The present invention also provides a calibration method for a film thickness measuring device, comprising: providing a film thickness standard sheet as described above; using a film thickness measuring device to measure the thickness of a thin film layer on the film thickness standard sheet to obtain a thickness measurement value of the thin film layer on the standard sheet; and comparing the thickness measurement value of the thin film layer with the thickness standard value of the thin film layer to determine whether the film thickness measuring device is abnormal.

[0021] Optionally, the film thickness standard sheet has at least two calibration areas; the film thickness measuring device preferentially measures the thickness of the thin film layer in one of the calibration areas, and then moves the measuring point to another calibration area and performs thickness measurement to achieve a calibration process for different thicknesses.

[0022] The present invention also provides a method for obtaining the thickness of a film layer, comprising the following steps. Step 1, forming at least one groove on a substrate, and obtaining a first opening size of the groove; and / or, forming at least one protrusion on a substrate, and obtaining a first width size of the protrusion. Step 2, forming a thin film layer on the substrate, when a groove is formed on the substrate, the thin film layer covers the groove, and obtaining a second opening size of the opening area of ​​the groove after covering the thin film layer; and, when a protrusion is formed on the substrate, the thin film layer covers the protrusion, and obtaining a second width size of the protrusion after covering the thin film layer. Step 3, obtaining the thickness value of the thin film layer according to the difference between the first opening size and the second opening size, and / or the difference between the second width size and the first width size.

[0023] Optionally, at least two grooves are formed in the substrate, and a portion of the substrate corresponding to between adjacent grooves forms a first protrusion of the at least one protrusion.

[0024] Optionally, the groove and the protrusion are formed on the substrate, and after obtaining the first thickness value according to the first opening size and the second opening size and obtaining the second thickness value according to the first width size and the second width size, it also includes: judging whether the absolute value of the difference between the first thickness value and the second thickness value is less than or equal to a preset threshold; if so, obtaining the thickness value of the thin film layer according to the average value of the first thickness value and the second thickness value.

[0025] Optionally, the inclination of the side wall of the groove is 85°-95°; and / or the inclination of the side wall of the protrusion is 85°-95°.

[0026] In the film thickness standard sheet provided by the present invention, by forming grooves and / or protrusions on the substrate and making the film layer cover the grooves and / or protrusions, the thickness value of the film layer on the standard sheet can be accurately obtained according to the size change of the grooves and / or protrusions before and after covering the film layer, so as to meet the requirements of the standard sheet. In addition, in the present invention, the longitudinal thickness value of the film layer is converted into the change in the lateral size of the grooves and / or protrusions before and after covering the film layer. Compared with the traditional film thickness measurement method, the film thickness measurement method provided by the present invention can not only accurately obtain the thickness value of the film layer, but also reduce the difficulty of thickness measurement. In addition, the film thickness standard sheet provided by the present invention can be directly prepared using existing equipment, which greatly reduces the cost of the standard sheet.

[0027] Furthermore, at least two calibration areas of different thickness levels can be set on the same standard sheet, so that when the film thickness measuring equipment is calibrated, multiple calibration processes of different thicknesses can be performed based on the same standard sheet. Compared with the traditional calibration process of different thicknesses that requires the use of multiple standard sheets, the present invention only requires the use of one standard sheet, which can effectively save the cost of standard sheets. At the same time, it also avoids the sheet replacement process of loading and unloading multiple standard sheets one by one, thereby improving the calibration efficiency of the equipment and reducing the risk of breakage that is easily caused during the sheet replacement process.

[0028] In addition, the technical concept provided by the present invention of obtaining the thickness value of the thin film layer based on the size change of the groove and / or protrusion before and after covering the thin film layer can also be directly applied to semiconductor processing to accurately obtain the thickness of the thin film layer when preparing the thin film layer. Furthermore, the thickness difference of the thin film layer covering the groove and the protrusion can be used to achieve real-time monitoring of the thickness uniformity of the currently formed thin film layer, and on this basis, the performance of the thin film deposition equipment used can be further reflected and whether it is abnormal can be judged. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of a film thickness standard sheet in one embodiment of the present invention.

[0030] Figure 2 FIG. 4 is a schematic diagram showing the distribution of multiple calibration areas of a film thickness standard sheet in an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of the process of preparing a film thickness standard sheet in one embodiment of the present invention.

[0032] Figure 4-Figure 5 Schematic diagram of the structure of a film thickness standard sheet during its preparation process in one embodiment of the present invention. DETAILED DESCRIPTION

[0033] The core idea of ​​the present invention is to provide a film thickness standard sheet, the thickness of the thin film layer in the standard sheet can be accurately obtained to meet the requirements of the standard sheet, and the standard sheet can be directly prepared using existing equipment to reduce the cost of the standard sheet.

[0034] Specifically, the film layer standard sheet provided by the present invention includes a substrate and a thin film layer formed on the substrate, the substrate has at least one calibration area, and the thin film layer at least covers the calibration area of ​​the substrate. Among them, at least one groove is formed in the calibration area of ​​the substrate, the groove has a first opening size, the thin film layer covers the groove and the top surface of the substrate, the thin film layer covers the groove and reduces the opening area of ​​the groove to a second opening size, and the thickness value of the thin film layer is obtained according to the difference between the first opening size and the second opening size. And / or, at least one protrusion is formed in the calibration area of ​​the substrate, the protrusion has a first width size, the thin film layer covers the side wall of the protrusion and the top surface of the substrate, the thin film layer covers the protrusion to form a second width size, and the thickness value of the thin film layer is obtained according to the difference between the second width size and the first width size.

[0035] That is, the film layer standard sheet provided by the present invention utilizes the size change of the grooves and / or protrusions before and after covering the film layer to accurately obtain the thickness value of the film layer on the standard sheet, so that the standard sheet meets the requirements for equipment calibration.

[0036] The following is a further detailed description of the film thickness standard sheet and its preparation method, and the calibration method of the film thickness measuring device proposed in the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It should be recognized that relative terms such as "above", "below", "top", "bottom", "above" and "below" shown in the drawings can be used to describe the relationship between various elements. These relative terms are intended to cover different orientations of elements other than the orientations depicted in the drawings. For example, if the device is inverted relative to the view in the drawing, an element described as "above" another element will now be below the element.

[0037] Figure 1 FIG. 1 is a schematic diagram of the structure of a film thickness standard sheet in one embodiment of the present invention. Figure 1 As shown, the film thickness standard sheet includes a substrate 100 and a thin film layer 200 formed on the substrate 100. The substrate 100 has at least one calibration area, and the thin film layer at least covers the calibration area of ​​the substrate 100, for example Figure 2Schematically, nine calibration areas are formed on the substrate 100. Also, the thin film layer 200 may be an insulating dielectric layer (eg, a silicon nitride layer or a silicon oxide layer), or a conductive layer (eg, a metal layer).

[0038] In an optional solution, at least one groove 110 is formed in the calibration area of ​​the substrate 100, and the groove 110 has a first opening size SCD1. In addition, the thin film layer 200 covers the groove 110 and the top surface of the substrate 100, and the opening size of the groove 110 is reduced to the second opening size SCD2 after covering the thin film layer 200, so that the thickness value THK of the thin film layer 200 can be obtained according to the difference between the first opening size SCD1 and the second opening size SCD2. Specifically, the thin film layer 200 covers the bottom surface and sidewall of the groove 110 in accordance with the inner surface of the groove 110, and the thickness of the thin film layer 200 covering the sidewall of the groove is the same as the thickness of the thin film layer 200 covering the top surface of the substrate, so the thickness value THK of the thin film layer 200 can be obtained according to the first opening size SCD1 and the second opening size SCD2 of the groove 110 before and after covering the thin film layer 200, specifically THK=(SCD1-SCD2) / 2.

[0039] That is, in this solution, by obtaining the difference in the opening size of the groove 110 before and after the groove 110 is covered with the thin film layer 200, the thickness value of the thin film layer 200 can be accurately obtained, so as to be used as a standard sheet of film thickness, and then the standard sheet can be used to monitor and calibrate the film thickness measurement equipment. Further, the thin film layer 200 at least covers the top surface of the substrate at the periphery of the groove 110, and the portion of the thin film layer 200 covering the top surface of the substrate can be used as a thickness measurement point during the calibration process of the film thickness measurement equipment.

[0040] In another optional solution, at least one protrusion 120 is formed in the calibration area of ​​the substrate 100, and the protrusion 120 has a first width dimension LCD1. The thin film layer 200 covers the protrusion 120 and the top surface of the substrate 100. The thin film layer 200 covers the protrusion 120 to increase the width dimension to a second width dimension LCD2. The thickness value THK of the thin film layer 200 is obtained according to the difference between the second width dimension LCD2 and the first width dimension LCD1. Specifically, the thin film layer 200 covers the top surface and side wall of the protrusion 120 in accordance with the outer surface of the protrusion 120, and the thickness of the thin film layer 200 covering the side wall of the protrusion is the same as the thickness of the thin film layer 200 covering the top surface of the substrate. Therefore, the thickness value THK of the thin film layer 200 can be obtained according to the first width dimension LCD1 and the second width dimension LCD2 of the protrusion 120 before and after covering the thin film layer 200, specifically THK=(LCD2-LCD1) / 2.

[0041] That is, in this solution, by obtaining the difference in the width of the protrusion 120 before and after it covers the thin film layer 200, the thickness of the thin film layer 200 can be accurately obtained, so as to be used as a standard sheet for film thickness, and then the standard sheet can be used to monitor and calibrate the film thickness measurement equipment. Furthermore, the thin film layer 200 at least covers the top surface of the substrate around the protrusion 120, and the portion of the thin film layer 200 covering the top surface of the substrate can be used as a thickness measurement point during the calibration process of the film thickness measurement equipment.

[0042] In a specific example, only the groove 110 may be formed in the same calibration area of ​​the same standard sheet, or only the protrusion 120 may be formed, or both the protrusion 120 and the groove 110 may be formed. The protrusion 120 may be formed in the substrate 100 (for example, the portion between adjacent grooves 110 constitutes the protrusion 120), and the protrusion formed in the substrate 100 may be defined as a first protrusion; or the protrusion 120 may also protrude from the top surface of the substrate 100, and the protrusion protruding from the top surface of the substrate may be defined as a second protrusion.

[0043] When a groove 110 and a protrusion 120 are simultaneously formed in the same calibration area, the first opening dimension SCD1 and the second opening dimension SCD2 of the groove 110 before and after the covering film layer 200, as well as the first width dimension LCD1 and the second width dimension LCD2 of the protrusion 120 before and after the covering film layer 200 can be obtained at the same time. At this time, the first thickness value THK1 can be obtained according to the first opening dimension SCD1 and the second opening dimension SCD2, and the second thickness value THK2 can be obtained according to the first width dimension LCD1 and the second width dimension LCD2. On this basis, the thickness of the film layer 200 can be obtained based on the first thickness value THK1 and the second thickness value THK2.

[0044] Specifically, in an ideal state, the first thickness value THK1 obtained according to the difference between the first opening size SCD1 and the second opening size SCD2 is equal to the second thickness value THK2 obtained according to the difference between the second width size LCD2 and the first width size LCD1. However, in actual applications, the thin film layer 200 on the substrate 100 can be formed by a thin film deposition device, and the process and the equipment may have a certain allowable error, so that there is a slight difference in the coverage performance for the groove 110 and the protrusion 120, so that the difference between the thickness of the deposited thin film layer 200 when covering the groove 110 and the thickness when covering the protrusion 120 is within the allowable error range, that is, the first thickness value THK1 obtained according to the difference between the first opening size SCD1 and the second opening size SCD2, and the second thickness value THK2 obtained according to the difference between the second width size LCD2 and the first width size LCD1, there is a difference between the two, the absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 is less than or equal to the preset threshold (that is, │THK1-THK2│≤spec), at this time, the thickness value of the thin film layer 200 can be obtained according to the average value of the first thickness value THK1 and the second thickness value THK2, that is, THK=(THK1+THK2) / 2.

[0045] Of course, if the thin film deposition equipment is abnormal or the process precision is poor, the thickness of the deposited thin film layer 200 when covering the groove 110 and the thickness when covering the protrusion 120 will be greatly different, so that the absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 obtained is greater than the preset threshold value (i.e., |THK1-THK2|>spec). Therefore, the thickness measurement can be performed based on the groove 110 and the protrusion 120, and the two can be mutually verified to further ensure the accuracy of the thickness of the obtained thin film layer 200. Specifically, when the difference between the first thickness value THK1 obtained based on the groove 110 and the second thickness value THK2 obtained based on the protrusion 120 is still within the threshold range, it means that the coverage performance of the deposited thin film layer 200 on different patterns is uniform. At this time, the first thickness value THK1 and the second thickness value THK2 can more accurately reflect the actual thickness of the thin film layer 200; conversely, when the difference between the first thickness value THK1 and the second thickness value THK2 exceeds the threshold range, it means that there is an abnormality in the coverage uniformity of the deposited thin film layer 200. At this time, it can also be used to determine whether there is an abnormality in the thin film deposition equipment used.

[0046] exist Figure 1In the example shown, at least two grooves 110 are formed in the same calibration area of ​​the substrate 100, and a protrusion 120 is formed in the portion of the substrate 100 corresponding to the portion between the two adjacent grooves 110. The protrusion 120 can be defined as a first protrusion. The thin film layer 200 covers the sidewalls and bottom surface of the groove 110, and covers the sidewalls and top surface of the protrusion 120, wherein part of the sidewall of the groove 110 corresponds to the sidewall of the protrusion 120. Among them, the first thickness value THK1 is obtained according to the first opening size SCD1 and the second opening size of the groove 110 before and after the covering film layer 200, and the second thickness value THK2 is obtained according to the first width size LCD1 and the second width size LCD2 of the protrusion 120 before and after the covering film layer 200. The absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 is within the area range of the preset threshold (i.e., │THK1-THK2│≤spec), and the thickness value of the film layer 200 can be obtained according to the average value of the first thickness value THK1 and the second thickness value THK2, i.e., THK=(THK1+THK2) / 2.

[0047] It should be noted that the first opening dimension SCD1 and the second opening dimension SCD2 of the groove 110, and the first width dimension LCD1 and the second width dimension LCD2 of the protrusion 120 can be obtained specifically by using a scanning electron microscope (SEM), and more specifically by using a critical dimension scanning electron microscope (CD-SEM) to more accurately measure the above dimensions.

[0048] Furthermore, when a groove 110 is formed in the calibration area of ​​the substrate 100, the inclination of the side wall of the groove 110 can be set to 85°-95° ​​(i.e., the angle between the side wall of the groove and the bottom surface of the groove is 85°-95°), so that the side wall of the groove 110 is a vertical side wall or a nearly vertical side wall. Similarly, when a protrusion 120 is formed in the calibration area of ​​the substrate 100, the inclination of the side wall of the protrusion 120 can be set to 85°-95° ​​(i.e., the angle between the side wall of the protrusion and the top surface of the substrate is 85°-95°), so that the side wall of the protrusion 120 is a vertical side wall or a nearly vertical side wall. In this way, it is convenient to more accurately measure the opening size of the groove 110 before and after the covering film layer 200, and the width size of the protrusion 120 before and after the covering film layer 200.

[0049] In an optional solution, at least two calibration areas may be defined on the substrate 100, for example Figure 2 9 calibration areas are shown in FIG. 1 , wherein the thickness of the thin film layer 200 formed in at least some of the calibration areas is different from each other. In a specific example, the standard sheet may have calibration areas with different thicknesses, such as Figure 2 The thickness of the thin film layer in the calibration area 2 and the calibration area 6 in the example is different. Figure 2The thickness of the thin film layer in the calibration area 4 and the calibration area 8 in the example is different, which can realize the calibration process of the film thickness measuring device for different thicknesses based on the same standard film; and the standard film can also have calibration areas with the same thickness, which can be distributed in the central area and the edge area of ​​the substrate, so that the thickness calibration can be performed for the central area and the edge area of ​​the standard film, for example, the thickness of the thin film layer in the calibration area 5 and the calibration area 6 is the same. Alternatively, part of the calibration area on the standard film is set in the central area of ​​the substrate 100, and the other part of the calibration area is set in the edge area of ​​the substrate 100, wherein the thickness of the thin film layer 200 of the calibration area set in the central area of ​​the substrate 100 can be different or the same; similarly, the thickness of the thin film layer 200 of the calibration area set in the edge area of ​​the substrate 100 can be different or the same. In addition, each calibration area is formed with the groove 110 and / or the protrusion 120 as described above, so that the thickness value of the thin film layer 200 in the corresponding area can be obtained based on the size change of the groove 110 and / or the protrusion 120 in each calibration area before and after covering the thin film layer 200.

[0050] That is, in this scheme, multiple calibration areas with different thicknesses can be set on the same standard film at the same time, so that the same standard film can be used to calibrate the film thickness measuring equipment at different thickness levels, overcoming the problem of the prior art that multiple standard films need to be used to calibrate different thicknesses, which is expensive. At the same time, it can also avoid the film replacement process of loading and unloading multiple standard films one by one, greatly reducing the cost of standard films, improving the calibration efficiency of the equipment, and preventing the problem of standard films being easily broken during the film replacement process.

[0051] The following is an explanation of the preparation method of the film thickness standard sheet as described above. Figure 1As shown, the preparation method of the film thickness standard sheet may include: providing a substrate 100, on which at least one calibration area is defined; then, forming at least one groove 110 in the calibration area of ​​the substrate 100, and obtaining a first opening size SCD1 of the groove 110, and / or, forming at least one protrusion 120 in the calibration area of ​​the substrate 100, and obtaining a first width size LCD1 of the protrusion 120; then, forming a thin film layer 200 on the substrate 100, wherein the thin film layer 200 at least covers the calibration area, wherein, When a groove 110 is formed in the calibration area, a second opening size SCD2 of the opening area of ​​the groove 110 after covering the thin film layer 200 is obtained; when a protrusion 120 is formed in the calibration area, a second width size LCD2 of the protrusion 120 after covering the thin film layer 200 is obtained; thereafter, a thickness value THK of the thin film layer 200 is obtained according to a difference between the first opening size SCD1 and the second opening size SCD2, and / or a difference between the second width size LCD2 and the first width size LCD1.

[0052] Specifically, when a groove 110 is formed in the calibration area, the first opening size SCD1 and the second opening size SCD2 of the groove 110 before and after the covering film layer 200 are obtained, and the thickness value THK of the film layer 200 is obtained according to the difference between the first opening size SCD1 and the second opening size SCD2, that is, THK = (SCD1-SCD2) / 2. Among them, the side wall inclination of the formed groove 110 can be between 85°-95° ​​(that is, the angle between the side wall of the groove and the bottom surface of the groove is 85°-95°), so that the side wall of the groove 110 is a vertical side wall or a nearly vertical side wall, so as to facilitate more accurate measurement of the opening size of the groove 110 before and after the covering film layer 200.

[0053] And, when a protrusion 120 is formed in the calibration area, the first width dimension LCD1 and the second width dimension LCD2 of the protrusion 120 before and after the covering film layer 200 are obtained, and the thickness value THK of the film layer 200 is obtained according to the difference between the second width dimension LCD2 and the first width dimension LCD1, that is, THK = (LCD2-LCD1) / 2. Wherein, the side wall inclination of the formed protrusion 120 is 85°-95° ​​(that is, the angle between the side wall of the protrusion and the top surface of the substrate is between 85°-95°), so that the side wall of the protrusion 120 is a vertical side wall or a nearly vertical side wall, so as to facilitate more accurate measurement of the width dimension of the protrusion 120 before and after the covering film layer 200.

[0054] Furthermore, when a groove 110 and a protrusion 120 are simultaneously formed in the calibration area, the first opening size SCD1 and the second opening size SCD2 of the groove 110 before and after the covering film layer 200, and the first width size LCD1 and the second width size LCD2 of the protrusion 120 before and after the covering film layer 200 can be obtained. At this time, the first thickness value THK1 can be obtained according to the first opening size SCD1 and the second opening size SCD2, and the second thickness value THK2 can be obtained according to the first width size LCD1 and the second width size LCD2. Then, the thickness value THK of the film layer 200 can be obtained based on the average value of the first thickness value THK1 and the second thickness value THK2, that is, THK=(THK1+THK2) / 2.

[0055] Among them, when the groove 110 and the protrusion 120 are formed in the calibration area at the same time, it also includes: judging whether the absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 is less than or equal to the preset threshold value spec; if so, it means that the formed thin film layer 200 has a higher coverage performance, and on this basis, the thickness value of the thin film layer 200 is obtained according to the average value of the first thickness value THK1 and the second thickness value THK2; if not, rework can be performed to re-form the thin film layer 200 until the absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 is less than or equal to the preset threshold value spec. By comparing the first thickness value THK1 obtained based on the groove 110 and the second thickness value THK2 obtained based on the protrusion 120, the uniformity of the coverage of the formed thin film layer 200 is further verified, so that the formed standard film can reach a higher specification and ensure the quality of the standard film.

[0056] In a specific example, at least two grooves 110 may be formed in the calibration region of the substrate 100, and a protrusion 120 (the protrusion formed in the substrate may constitute a first protrusion) may be formed in the portion of the substrate 110 corresponding to the portion between two adjacent grooves 110. In addition, the protrusion 120 in the calibration region may also be a second protrusion protruding from the top surface of the substrate.

[0057] In order to explain more clearly the preparation method of the film thickness standard sheet provided in this embodiment, the following is combined with Figure 3 and Figure 4-Figure 5 An example is given to illustrate the preparation of Figure 1 The standard film shown is used as an example for explanation. Figure 3 FIG. 1 is a schematic flow chart of a method for preparing a film thickness standard sheet in one embodiment of the present invention. Figure 4-Figure 5 FIG. 1 is a schematic diagram of the structure of a film thickness standard sheet in an embodiment of the present invention during its preparation process. It can be considered that: Figure 4 and Figure 5 Only the structure of one calibration area is schematically shown.

[0058] First reference Figure 3 and Figure 4 As shown, a substrate 100 is provided, and at least one calibration area is defined on the substrate 100. In a specific example, at least two calibration areas may be defined on the substrate 100, wherein at least part of the calibration areas are used to prepare thin film layers with different thicknesses. The substrate 100 is, for example, a wafer.

[0059] Continue to refer Figure 3 and Figure 4 As shown, at least two grooves 110 are formed in the calibration area of ​​the substrate 100, and a protrusion 120 is formed in the portion of the substrate 100 corresponding to the portion between the adjacent grooves 110, and the protrusion 120 can constitute a first protrusion. And, a first opening size SCD1 of the groove 110 and a first width size LCD1 of the protrusion 120 are obtained, wherein the first opening size of the groove 110 and the second opening size of the protrusion 120 can be measured using a scanning electron microscope to improve the measurement accuracy.

[0060] Next reference Figure 3 and Figure 5 As shown, a thin film layer 200 is formed on the substrate 100, and the thin film layer 200 covers at least the top surface of the substrate in the calibration area and conformally covers the groove 110 and the protrusion 120. The thin film layer 200 can be formed by a thin film deposition process.

[0061] Continue to refer Figure 3 and Figure 5 As shown, the second opening size SCD2 of the opening area of ​​the groove 110 after the cover film layer 200 is obtained, and the second width size LCD2 of the protrusion 120 after the cover film layer 200 is obtained. Similarly, the second opening size SCD2 and the second width size LCD2 can be measured using a scanning electron microscope to improve the measurement accuracy.

[0062] Then, the first thickness value THK1 can be obtained according to the first opening size SCD1 and the second opening size SCD2 , and the second thickness value THK2 can be obtained according to the first width size LCD1 and the second width size LCD2 .

[0063] Continue to refer Figure 3As shown, it is determined whether the absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 is less than or equal to the preset threshold value spec. When the absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 is less than or equal to the preset threshold value spec (│THK1-THK2│≤spec), it means that the coverage performance of the thin film layer 200 when covering the groove 110 and the protrusion 120 is similar, so it has a higher coverage uniformity, which can more accurately reflect the thickness of the thin film layer 200 covering the top surface of the substrate, and improve the quality of the prepared standard film; on the contrary, when the absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 is greater than the preset threshold value spec (│THK1-THK2│>spec), it means that the coverage performance of the thin film layer 200 for the groove 110 and the protrusion 120 is greatly different, and its coverage uniformity is not good. At this time, rework processing can be performed to re-form the thin film layer 200 until the thickness difference of the formed thin film layer 200 when covering the groove 110 and the protrusion 120 is less than or equal to the preset threshold value spec.

[0064] That is, in this example, the first thickness value THK1 corresponding to the groove 110 and the second thickness value THK2 corresponding to the protrusion 120 are used for mutual verification to further improve the thickness uniformity of the formed thin film layer 200, so that the thin film layer 200 reaching a higher specification can be further used as a film thickness standard sheet, thereby improving the quality of the standard sheet.

[0065] Afterwards, the thickness value THK of the thin film layer 200 can be obtained according to the average value of the first thickness value THK1 and the second thickness value THK2 , that is, THK=(THK1+THK2) / 2.

[0066] In addition, in one example, at least two calibration areas are provided on the substrate 100, and at least part of the calibration areas are used to prepare thin film layers 200 with different thicknesses, wherein thin film layers with different thicknesses are formed in the calibration areas with different thicknesses. The following is an example in which a first calibration area and a second calibration area are formed in the substrate 100, and the first calibration area and the second calibration area are used to form a first thin film layer and a second thin film layer with different thicknesses, respectively.

[0067] Specifically, the method for forming the first thin film layer and the second thin film layer of different thicknesses in the first calibration area and the second calibration area respectively includes: first, forming at least one groove 110 and / or at least one protrusion 120 in each calibration area of ​​the substrate 100; then, forming a first thin film layer in the first calibration area, and obtaining the thickness value of the first thin film layer, and the method for obtaining the thickness value of the first thin film layer can be obtained by the first thickness value THK1 and / or the second thickness value THK2 as described above; then, forming a second thin film layer in the second calibration area, and obtaining the thickness value of the second thin film layer, similarly, the method for obtaining the thickness value of the second thin film layer can also be obtained by the first thickness value THK1 and / or the second thickness value THK2 as described above.

[0068] It should be appreciated that when the substrate 100 further has calibration areas for forming other thicknesses, the deposition process of the thin film layer can be repeated, and this cycle of obtaining the thickness of the thin film layer in the corresponding area can be repeated.

[0069] This embodiment also provides a calibration method for a film thickness measuring device, which specifically includes the following steps.

[0070] The first step is to provide a film thickness standard sheet as described above, wherein the film thickness standard sheet has at least one calibration area, wherein a thin film layer is formed in the calibration area, and the thin film layer covers the top surface of the substrate, the grooves and / or the protrusions in the calibration area. As described above, the thickness of the thin film layer in the calibration area of ​​the film thickness standard sheet is specifically obtained based on the size change before and after the thin film layer covers the grooves and / or protrusions, and the obtained thickness of the thin film layer constitutes the standard value of the thickness of the thin film layer in the calibration area, which is used as a thickness reference object in the subsequent calibration process.

[0071] In the second step, the film layer on the film thickness standard sheet is measured by using a film thickness measuring device to obtain a thickness measurement value of the film layer on the standard sheet. The film thickness measuring device can specifically measure the thickness of the portion of the film layer covering the top surface of the substrate, for example, based on the optical path difference between the reflected light of the detection light on the top surface of the film layer to be measured and the reflected light of the detection light on the top surface of the substrate, to obtain the thickness measurement value of the film layer to be measured.

[0072] The third step is to compare the thickness measurement value of the thin film layer with the thickness standard value of the thin film layer to determine whether the film thickness measurement device is abnormal. Specifically, when the measured thickness measurement value is significantly different from the thickness standard value, it reflects that the measurement accuracy of the film thickness measurement device is poor and needs to be calibrated; conversely, when the difference between the measured thickness measurement value and the thickness standard value is within the allowable error range, it reflects that the measurement accuracy of the film thickness measurement device is normal and has a high measurement accuracy.

[0073] In a further solution, the provided film thickness standard sheet may have at least two calibration areas. In this case, during the calibration process of the film thickness measuring device, the thickness of the thin film layer in one of the calibration areas may be measured first, and then the measuring point may be moved to another calibration area and the thickness may be measured, so as to achieve the calibration process of different thickness levels. In other words, in this embodiment, the same standard sheet may be used to achieve the calibration process of multiple different thicknesses, and the standard sheet does not need to be replaced during the process, thus eliminating the sheet replacement process, greatly improving the calibration efficiency, saving calibration time, and effectively reducing the risk of damage to the standard sheet caused by frequent sheet replacement.

[0074] Based on the core concept provided by the present invention, this embodiment also provides a method for obtaining the thickness of the film layer, which specifically includes the following steps. Figure 4-Figure 5 The structure shown is used to illustrate the method for obtaining the film thickness.

[0075] Step 1: forming at least one groove 110 on the substrate 100 and obtaining a first opening size SCD1 of the groove 110 ; and / or forming at least one protrusion 120 on the substrate 100 and obtaining a first width size LCD1 of the protrusion 120 .

[0076] As described above, when a groove 110 is formed on the substrate 100, the sidewall inclination of the groove 110 can be set to 85°-95° ​​(i.e., the angle between the sidewall of the groove and the bottom surface of the groove is 85°-95°), so that the sidewall of the groove 110 is a vertical sidewall or a nearly vertical sidewall. Also, when a protrusion 120 is formed in the calibration area of ​​the substrate 100, the sidewall inclination of the protrusion 120 can be set to 85°-95° ​​(i.e., the angle between the sidewall of the protrusion and the top surface of the substrate is 85°-95°), so that the sidewall of the protrusion 120 is a vertical sidewall or a nearly vertical sidewall. In this way, the opening size of the groove 110 before and after the cover film layer 200 and the width size of the protrusion 120 before and after the cover film layer 200 can be measured more accurately.

[0077] The first opening dimension SCD1 of the groove 110 and the first width dimension LCD1 of the protrusion 120 can be obtained by using a scanning electron microscope (SEM), and more specifically, a critical dimension scanning electron microscope (CD-SEM) can be used to more accurately measure the above dimensions.

[0078] Step 2: forming a thin film layer 200 on the substrate 100 . Specifically, a thin film deposition device may be used to deposit the thin film layer 200 on the substrate 100 .

[0079] When a groove 110 is formed on the substrate 110, the thin film layer 200 covers the groove 110, and the second opening size SCD2 of the opening area of ​​the groove 110 after covering the thin film layer 200 is obtained; and when a protrusion 120 is formed on the substrate 100, the second width size LCD2 of the protrusion 120 after covering the thin film layer 200 is obtained. Similarly, in this step, a scanning electron microscope (SEM) can also be used to obtain, and more specifically, a critical dimension scanning electron microscope (CD-SEM) can be used to more accurately measure the second opening size SCD2 and the second width size LCD2.

[0080] Step three, obtaining the thickness value THK of the thin film layer 200 according to the difference between the first opening size SCD1 and the second opening size SCD2, and / or the difference between the second width size LCD2 and the first width size LCD1.

[0081] Specifically, when only the groove 110 is formed on the substrate 100, the thickness value THK of the thin film layer 200 can be obtained according to the difference between the first opening size SCD1 and the second opening size SCD2, that is, THK=(SCD1-SCD2) / 2. When only the protrusion 120 is formed on the substrate 100, the thickness value THK of the thin film layer 200 can be obtained according to the difference between the second width size LCD2 and the first width size LCD1, that is, THK=(LCD2-LCD1) / 2. When the groove 110 and the protrusion 120 are formed on the substrate at the same time, the first thickness value THK1 can be obtained based on the first opening size SCD1 and the second opening size SCD2, THK1 = (SCD1-SCD2) / 2, and the second thickness value THK2 can be obtained based on the first width size LCD1 and the second width size LCD2, THK2 = (LCD2-LCD1) / 2, and the thickness of the thin film layer 200 is obtained by the average value of the first thickness value THK1 and the second thickness value THK2, that is, THK = (THK1+THK2) / 2.

[0082] In this embodiment, taking the case where both the grooves 110 and the protrusions 120 are formed on the substrate 100 as an example, the actual thickness of the deposited thin film layer 200 can be more accurately obtained based on the thickness of the thin film layer on the grooves 110 and the protrusions 120. Specifically, at least two grooves 110 are formed in the substrate 100, and the protrusions 120 are formed by the portions of the substrate 100 corresponding to the portions between the adjacent grooves. In other examples, the protrusions may also protrude from the top surface of the substrate.

[0083] In addition, by simultaneously forming the groove 110 and the protrusion 120 on the substrate 100, the first thickness value THK1 and the second thickness value THK2 obtained can be mutually verified to determine the uniformity of the film thickness of the deposited thin film layer 200, which can further reflect the performance of the currently used thin film deposition equipment.

[0084] Specifically, after obtaining the first thickness value THK1 and the second thickness value THK2, determine whether the absolute value of the difference between the first thickness value THK1 and the second thickness value THK2 is less than or equal to the preset threshold value spec; if so (i.e., │THK1-THK2│≤spec), it means that the thin film layer 200 has a higher thickness uniformity, and the thin film deposition equipment used can achieve a higher process accuracy. At this time, the thickness value of the thin film layer 200 can be obtained according to the average value of the first thickness value THK1 and the second thickness value THK2, that is, THK=(THK1+THK2) / 2. If not, it means that the coverage uniformity of the thin film layer 200 is not good, reflecting that the thin film deposition equipment used may have an accuracy abnormality. At this time, rework can be performed on the current thin film layer 200, and the thin film layer 200 can be re-formed until the formed thin film layer 200 satisfies │THK1-THK2│≤spec. At the same time, the thin film deposition equipment can be shut down for inspection to avoid the subsequent formation of a large number of thin film layers that do not meet the thickness uniformity.

[0085] It can be seen that in the process of obtaining the film layer thickness provided in this embodiment, on the one hand, the thickness of the formed thin film layer can be accurately obtained; on the other hand, it is also beneficial to monitor the thickness uniformity of the formed thin film layer, and on this basis, further abnormal monitoring of the thin film deposition equipment can be realized.

[0086] It should be noted that, although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belongs to the scope of protection of the technical solution of the present invention.

[0087] It must be noted that as used herein and in the appended claims, the singular forms "a," "an," and "an" include plural references unless the context clearly indicates otherwise. For example, reference to "a step" or "a device" means reference to one or more steps or devices and may include secondary steps as well as secondary devices. All conjunctions used should be interpreted in the broadest sense. Also, the word "or" should be interpreted as having the definition of a logical "or" rather than a logical "exclusive or" unless the context clearly indicates otherwise.

Claims

1. A film thickness standard sheet, characterized in that: include: A substrate and a thin film layer formed on the substrate, the substrate having at least one calibration area, the thin film layer at least covering the calibration area; wherein, At least one groove is formed in the calibration area of ​​the substrate, the groove has a first opening size, the thin film layer covers the groove and the top surface of the substrate, the thin film layer covers the groove so that the opening area of ​​the groove is reduced to a second opening size, and the thickness value of the thin film layer is obtained according to the difference between the first opening size and the second opening size; and / or, At least one protrusion is formed in the calibration area of ​​the substrate, the protrusion has a first width dimension, the thin film layer covers the protrusion and the top surface of the substrate, the thin film layer covers the protrusion to form a second width dimension, and the thickness value of the thin film layer is obtained according to the difference between the second width dimension and the first width dimension.

2. The film thickness standard sheet according to claim 1, characterized in that: At least two grooves are formed in the calibration area of ​​the substrate, and a first protrusion among the at least one protrusion is formed on the substrate corresponding to a portion between two adjacent grooves.

3. The film thickness standard sheet according to claim 1 or 2, characterized in that: The groove and the protrusion are formed in the calibration area of ​​the substrate, a first thickness value is obtained according to the first opening size and the second opening size, a second thickness value is obtained according to the first width size and the second width size, and a thickness value of the thin film layer is obtained based on an average value of the first thickness value and the second thickness value.

4. The film thickness standard sheet according to claim 3, characterized in that: An absolute value of a difference between the first thickness value and the second thickness value is less than or equal to a preset threshold.

5. The film thickness standard sheet according to claim 1, characterized in that: The at least one protrusion includes a second protrusion protruding from a top surface of the substrate.

6. The film thickness standard sheet according to claim 1, characterized in that: The inclination of the side wall of the groove is 85°-95°; and / or the inclination of the side wall of the protrusion is 85°-95°.

7. The film thickness standard sheet according to claim 1, characterized in that: The substrate has at least two calibration areas, and the thicknesses of the thin film layers formed in at least some of the calibration areas are different from each other.

8. The film thickness standard sheet according to claim 1, characterized in that: The substrate has at least two calibration areas, wherein a portion of the calibration areas is arranged in the central area of ​​the substrate, and another portion of the calibration areas is arranged in the edge area of ​​the substrate.

9. A method for preparing a film thickness standard sheet, characterized in that: include: Providing a substrate having at least one calibration area defined thereon; forming at least one groove in a calibration area of ​​the substrate, and obtaining a first opening size of the groove; and / or, forming at least one protrusion in a calibration area of ​​the substrate, and obtaining a first width dimension of the protrusion; A thin film layer is formed on the substrate, wherein the thin film layer at least covers the calibration area; wherein when a groove is formed in the calibration area, a second opening size of an opening area of ​​the groove after covering the thin film layer is obtained; and when a protrusion is formed in the calibration area, a second width size of the protrusion after covering the thin film layer is obtained; as well as, The thickness value of the film layer is obtained according to the difference between the first opening size and the second opening size, and / or the difference between the second width size and the first width size.

10. The method for preparing a film thickness standard sheet according to claim 9, characterized in that: At least two grooves are formed in the substrate, and a first protrusion among the at least one protrusion is formed in a portion of the substrate corresponding to between adjacent grooves.

11. The method for preparing a film thickness standard sheet according to claim 9 or 10, characterized in that: The groove and the protrusion are formed in the calibration area of ​​the substrate, and after obtaining a first thickness value according to the first opening size and the second opening size and obtaining a second thickness value according to the first width size and the second width size, the substrate further includes: Determine whether the absolute value of the difference between the first thickness value and the second thickness value is less than or equal to a preset threshold; if so, the formed thin film layer meets the requirements of the standard film, and the thickness value of the thin film layer is obtained according to the first thickness value and the second thickness value; if not, rework is performed to reform the thin film layer until the absolute value of the difference between the first thickness value and the second thickness value obtained is less than or equal to the preset threshold.

12. The method for preparing a film thickness standard sheet according to claim 9, characterized in that: The at least one protrusion includes a second protrusion protruding from a top surface of the substrate.

13. The method for preparing a film thickness standard sheet according to claim 9, characterized in that: The substrate has at least two calibration areas, and the thicknesses of the thin film layers formed in at least some of the calibration areas are different from each other.

14. The method for preparing a film thickness standard sheet according to claim 13, characterized in that: The at least two calibration areas include a first calibration area and a second calibration area, and a method of forming a first thin film layer in the first calibration area and forming a second thin film layer in the second calibration area includes: forming at least one groove and / or at least one protrusion in each calibration area of ​​the substrate; forming a first thin film layer in the first calibration area, and obtaining a thickness value of the first thin film layer; and, A second thin film layer is formed in the second calibration area, and a thickness value of the second thin film layer is acquired.

15. The method for preparing a film thickness standard sheet according to claim 9, characterized in that: The inclination of the side wall of the groove is 85°-95°; and / or the inclination of the side wall of the protrusion is 85°-95°.

16. A method for calibrating a film thickness measuring device, characterized in that: include: Providing a film thickness standard sheet as described in any one of claims 1 to 8; Measuring the thickness of the thin film layer on the film thickness standard sheet by using a film thickness measuring device to obtain a thickness measurement value of the thin film layer on the standard sheet; as well as, The measured thickness value of the thin film layer is compared with the standard thickness value of the thin film layer to determine whether the film thickness measuring device is abnormal.

17. The calibration method of the film thickness measuring device according to claim 16, characterized in that: The film thickness standard sheet has at least two calibration areas; The film thickness measuring device preferentially measures the thickness of the thin film layer in one calibration area, and then moves the measuring point to another calibration area and performs thickness measurement to achieve a calibration process of different thicknesses.

18. A method for obtaining film thickness, characterized in that: include: forming at least one groove on a substrate, and obtaining a first opening size of the groove; and / or, forming at least one protrusion on the substrate, and obtaining a first width dimension of the protrusion; forming a thin film layer on the substrate, when a groove is formed on the substrate, the thin film layer covers the groove, and obtaining a second opening size of an opening area of ​​the groove after the groove is covered with the thin film layer; And, when a protrusion is formed on the substrate, the thin film layer covers the protrusion, and a second width dimension of the protrusion after being covered by the thin film layer is obtained; as well as, The thickness value of the film layer is obtained according to the difference between the first opening size and the second opening size, and / or the difference between the second width size and the first width size.

19. The method for obtaining film thickness according to claim 18, characterized in that: At least two grooves are formed in the substrate, and a first protrusion among the at least one protrusion is formed in a portion of the substrate corresponding to between adjacent grooves.

20. The method for obtaining film thickness according to claim 18 or 19, characterized in that: The substrate is formed with the groove and the protrusion, and after obtaining a first thickness value according to the first opening size and the second opening size, and obtaining a second thickness value according to the first width size and the second width size, the method further includes: Determine whether the absolute value of the difference between the first thickness value and the second thickness value is less than or equal to a preset threshold; if so, obtain the thickness value of the thin film layer according to the average value of the first thickness value and the second thickness value.

21. The method for obtaining film thickness according to claim 18, characterized in that: The inclination of the side wall of the groove is 85°-95°; and / or the inclination of the side wall of the protrusion is 85°-95°.

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