Film thickness measurement calibration sheet and manufacturing and monitoring method thereof

Abstract

The invention discloses a film thickness measurement calibration sheet and a manufacturing and monitoring method thereof. The manufacturing method of the calibration sheet comprises the following steps: providing a wafer; defining a plurality of calibration areas on the wafer; a plurality of calibration units with the same number are formed in each calibration area, so that each calibration unit is formed by a homogeneous film formed on the wafer, and the surface height of gradient change corresponding to the thickness of the film at the position between the calibration units in each calibration area is formed between the calibration units in each calibration area. According to the invention, the film thickness measuring equipment can be accurately calibrated, the utilization rate of the equipment is obviously improved, and daily real-time monitoring can be carried out, so that the film thickness measuring precision of a product can be improved, the high accuracy of data during calibration and measurement is ensured, and meanwhile, the related cost is saved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor testing technology, and in particular to a calibration sheet for film thickness measurement, a calibration sheet manufacturing method, and a film thickness measurement and monitoring method. Background Art

[0002] In the process of making chips on wafers, it is necessary to transfer the wafers to film thickness measurement equipment for film thickness testing after the film deposition is completed. Films of different thicknesses have different effects on chip performance, so the thickness measurement of the film after deposition is of great significance, and the measurement equipment plays a very important role in it.

[0003] When measuring the thickness of a film on a wafer, the measuring equipment needs to be calibrated. The current calibration sheets (usually made of wafers) used to calibrate the measuring equipment are expensive, and each sheet corresponds to a different film thickness level (gear). During the calibration process, multiple loading and unloading are required, which is time-consuming, reduces the machine output rate, and easily increases the risk of damage to the calibration sheet during the transmission process.

[0004] Moreover, since the thickness of thin film deposition in different areas on the product wafer often has a certain degree of non-uniformity, the film thickness value measured by the measuring equipment calibrated with a calibration sheet of uniform thickness is difficult to accurately reflect the actual thickness of the film in different areas on the wafer, thus lacking precise guidance for process monitoring during chip manufacturing.

[0005] In addition, the measuring equipment generally needs to perform mobile multi-point measurements on different areas on the chip. It is also very important to better monitor the accuracy of the measuring equipment during testing and the test accuracy after movement on a daily basis so that the measuring equipment can maintain normal working status in real time. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects in the prior art and to provide a film thickness measurement calibration sheet and a manufacturing and monitoring method.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] The present invention provides a method for manufacturing a film thickness measurement calibration sheet, comprising:

[0009] Providing wafers;

[0010] defining a plurality of calibration areas on the wafer;

[0011] A plurality of calibration units of the same number are formed in each of the calibration areas, so that each of the calibration units is formed by a homogeneous thin film formed on the chip, and the calibration units in each of the calibration areas have a surface height with a gradient change corresponding to the thickness of the thin film at the location.

[0012] Further, forming a plurality of calibration units of the same number in each calibration region, so that each calibration unit is formed by a homogeneous thin film formed on the wafer, and so that the calibration units in each calibration region have a surface height with a gradient change corresponding to the thickness of the thin film at the location, specifically includes:

[0013] forming a thin film of a preset thickness on the wafer to cover each of the defined calibration areas;

[0014] Selecting a plurality of calibration unit selected areas of the same number in each of the calibration areas;

[0015] Part of the thickness of the film is removed in an increasing thickness gradient manner between the calibration unit selection areas other than one of the calibration unit selection areas selected in each of the calibration areas, so as to form a plurality of calibration units of the same number in each of the calibration areas, so that each of the calibration units is formed by the homogeneous thin film formed on the chip, and the calibration units in each of the calibration areas have a surface height with a gradient change corresponding to the thickness of the film at the location.

[0016] Further, forming a plurality of calibration units of the same number in each calibration region, so that each calibration unit is formed by a homogeneous thin film formed on the wafer, and so that the calibration units in each calibration region have a surface height with a gradient change corresponding to the thickness of the thin film at the location, specifically includes:

[0017] Selecting a plurality of calibration unit selected areas of the same number in each of the calibration areas;

[0018] Between the selected areas of each of the calibration units, a thin film stack composed of homogeneous thin films with successively increasing numbers of layers is formed, so as to form a plurality of calibration units of the same number in each of the calibration areas, so that each of the calibration units is formed by the homogeneous thin film formed on the chip, and the calibration units in each of the calibration areas have a surface height with a gradient variation corresponding to the thickness of the thin film stack at the location.

[0019] Furthermore, the calibration areas are arranged on the wafer in an array covering the surface of the wafer.

[0020] Furthermore, the calibration units with consistent surface heights in each of the calibration areas have corresponding positions in the calibration areas.

[0021] Furthermore, the film is located on the wafer at a corresponding process level when the corresponding film to be measured for film thickness is manufactured, and the material and manufacturing process conditions of the film are consistent with those of the film to be measured for film thickness.

[0022] The present invention also provides a film thickness measurement calibration sheet, comprising:

[0023] a plurality of calibration regions formed on the wafer;

[0024] A plurality of calibration units of the same number are formed in each of the calibration areas, and each of the calibration units is formed by a homogeneous thin film formed on the chip. A surface height with a gradient variation corresponding to the thickness of the thin film at the location exists between each of the calibration units in each of the calibration areas, so as to form a plurality of calibration positions defined by the surface height.

[0025] Furthermore, the calibration sheet includes a first calibration sheet and a second calibration sheet that are consistent with each other, the first calibration sheet is used to calibrate the film thickness measuring device, and the second calibration sheet is used to verify the calibration result of the first calibration sheet.

[0026] Furthermore, the first calibration sheet and the second calibration sheet are produced in the same batch.

[0027] The present invention also provides a film thickness measurement and monitoring method, which uses a calibration piece made by any of the above-mentioned film thickness measurement calibration piece making methods or any of the above-mentioned film thickness measurement calibration pieces to calibrate a film thickness measurement device, and uses the film thickness measurement device to measure the film thickness of a thin film that is a film thickness measurement object.

[0028] Furthermore, the calibrating of the film thickness measuring device and using the film thickness measuring device to measure the film thickness of the film to be measured specifically include:

[0029] Provide calibration sheets;

[0030] Selecting calibration areas located at different positions on the calibration sheet, and using a film thickness measuring device to measure the film thickness of each calibration unit in the calibration area to obtain measurement data;

[0031] Inputting the measurement data into the film thickness measuring device, updating the measurement standard of the film thickness measuring device, and completing calibration;

[0032] Use the updated measurement standard to measure the film thickness of the thin film to be measured.

[0033] Furthermore, the measurement standard includes a plurality of sub-measurement standards corresponding to the calibration areas at different positions, and when measuring the film thickness of the film to be measured, one of the sub-measurement standards corresponding to the measurement position is called to perform the film thickness measurement.

[0034] Furthermore, it also includes: using a consistent first calibration piece and a second calibration piece as the calibration piece, and using the first calibration piece to perform an initial calibration on the film thickness measurement device, using the second calibration piece to verify the initial calibration result of the first calibration piece, and when the verification result meets the threshold requirement, the calibration is completed.

[0035] Furthermore, it also includes: after calibrating the film thickness measuring device, using the calibration sheet, and selecting the calibration area and the calibration unit on the calibration sheet, using the film thickness measuring device to measure the film thickness, comparing the acquired measurement data with the measurement standard, and monitoring the accuracy of the film thickness measuring device for real-time monitoring.

[0036] The present invention has the following advantages:

[0037] (1) By forming multiple calibration areas at different positions on the calibration sheet, and forming multiple calibration units with gradient surface height in each calibration area, multiple calibration positions are formed, which can avoid the problem of multiple loading and unloading of calibration sheets of different film thickness levels during the calibration process. This not only saves time and improves productivity, but also effectively reduces the risk of damage to the calibration sheet during transportation. Especially for the measurement of key film layers, the utilization rate of film thickness measurement equipment can be significantly improved, and the cost of purchasing calibration sheets can be saved.

[0038] (2) By selecting calibration areas at different positions on the calibration sheet to calibrate the film thickness measurement device, multiple sub-measurement standards corresponding to the calibration areas at different positions can be established. When measuring the film thickness of the film to be measured, the film thickness can be measured by calling a sub-measurement standard corresponding to the measurement position, thereby further improving the measurement accuracy. Therefore, the actual thickness of the film at different areas on the product wafer can be accurately reflected, thereby playing an accurate guiding role in process monitoring during chip manufacturing.

[0039] (3) When making the calibration sheet, the thin film serving as the calibration unit is formed on the chip at a corresponding process level when the thin film to be measured for film thickness is made, and the material and manufacturing process conditions of the thin film are made consistent with the material and manufacturing process conditions of the thin film to be measured for film thickness, and the thickness range (measuring range) of the thin film on the calibration sheet includes the normal production thickness range of the thin film to be measured for film thickness, thereby minimizing the difference between the calibration sheet and the thin film to be measured for film thickness. Compared with the existing calibration sheet, the calibration sheet of the present invention, which is closer to the actual product, is used for calibration, and the data entered into the database of the film thickness measurement equipment will be more accurate.

[0040] (4) By using the calibration sheet of the present invention, after calibrating the film thickness measuring device, the film thickness measuring device can be used to measure the film thickness by selecting calibration areas and calibration units at different positions (e.g., the center and edge of the wafer) on the calibration sheet, and the acquired measurement data can be compared with the measurement standard, so as to conduct daily real-time monitoring of the accuracy of the film thickness measuring device during film thickness testing and the test accuracy after stepping movement. When the film thickness is abnormal, the state of the film thickness measuring device can be checked in time, so that the film thickness measuring device can be kept in a normal working state in real time, thereby improving the measurement utilization rate and the work efficiency.

[0041] (5) A first calibration piece and a second calibration piece that are consistent are used as calibration pieces, and the first calibration piece is used to perform an initial calibration on the film thickness measurement device, and the second calibration piece is used to verify the initial calibration result of the first calibration piece, thereby forming a dual calibration mechanism, thereby ensuring the high accuracy of the data during calibration piece calibration and product measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flow chart of a method for making a film thickness measurement calibration sheet according to a preferred embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the structure of a calibration sheet according to a preferred embodiment of the present invention;

[0044] Figure 3 A top view of the structure of a calibration area of ​​a calibration sheet according to a preferred embodiment of the present invention;

[0045] Figure 4 for Figure 3 Right view of;

[0046] Figure 5 The present invention is a flowchart of a film thickness measurement and monitoring method according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0048] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0049] refer to Figure 1 The present invention provides a method for manufacturing a film thickness measurement calibration sheet, comprising the following steps:

[0050] Step S1: providing a wafer.

[0051] like Figure 2 As shown, a conventional product wafer, such as a silicon wafer, can be used as a substrate for making the calibration sheet 10, so as to be consistent with the product wafer used as the substrate of the thin film to be measured for film thickness in production. In addition, the calibration sheet wafer substrate 11 used to make the calibration sheet 10 can have a process level and structure consistent with that of the product wafer used to form the thin film to be measured for film thickness, so as to improve the pertinence of the calibration sheet 10.

[0052] Step S2: defining a plurality of calibration areas on the wafer.

[0053] like Figure 2 As shown, a plurality of calibration regions 12 may be defined on the calibration wafer substrate 11. For example, a center 1 (eg, Figure 2 The area with vertical parallel lines in the grid display) and edge 2 (such as Figure 2 One or more rectangular areas are defined as calibration areas 12 on the calibration wafer substrate 11. In addition, the calibration areas 12 can be arranged in sequence on the calibration wafer substrate 11 to form a plurality of rows and columns of calibration areas 12 in the form of an array covering the surface of the calibration wafer substrate 11 (e.g. Figure 2 Among them, one or more calibration areas 12 which are usually used as calibration fixed point positions can be specified in each calibration area 12, and the positions of these calibration areas 12 on the calibration sheet wafer substrate 11 correspond to the measurement positions of the thin film to be measured on the product wafer.

[0054] Step S3: forming a plurality of calibration units of the same number in each calibration region, so that each calibration unit is formed by a homogeneous thin film formed on the wafer, and each calibration unit in each calibration region has a surface height with a gradient change corresponding to the thickness of the thin film at the location.

[0055] like Figure 3 As shown, it shows a plurality of calibration unit arrangement structures selected and expected to be formed in a defined calibration area 12. It can be understood that the number of calibration units selected and expected to be formed in each calibration area 12 can correspond to the number of process setting gears for different thicknesses of the film to be measured on the product wafer according to the film thickness measurement object to be measured. In this embodiment, for example, assuming that the number of process setting gears includes 10000 angstroms, 5000 angstroms, 1000 angstroms, 500 angstroms, 100 angstroms, and 50 angstroms (each thickness value is only for the convenience of example and should not be used as a limitation of the present invention, the same below), the number of calibration units in each calibration area 12 can be defined and formed accordingly, that is, each calibration area 12 has 6 film thickness calibration gears. For the arrangement form of each calibration unit in the calibration area 12, according to the film thickness of the calibration unit, it can be arranged in sequence in the counterclockwise direction shown in the figure to form a regular row and column structure. A regular row and column structure can also be formed, but the thickness is not arranged in sequence. Other combinations can also be formed. It is preferred that the calibration units with the same surface height in each calibration area 12 correspond to each other in their respective calibration areas 12 .

[0056] In some embodiments, this step can be performed and implemented as follows:

[0057] Step S311: forming a thin film of a preset thickness on the wafer to cover each defined calibration area.

[0058] The same formation process conditions (including material) as those of the film to be measured on the product wafer can be used to form the film thickness of the calibration wafer substrate 11 (reference Figure 2 ) to form a thin film 13 of a preset first thickness, and to cover each defined calibration area 12. For example, the first thickness may be

[0059] It can be understood that the film layer on the calibration wafer substrate 11 can be the same as or different from the film layer used on the actual product wafer, and can be one or more types, and the present invention is not limited thereto.

[0060] Preferably, the thin film 13 is located on the calibration wafer substrate 11 at a process level corresponding to the process level at which the thin film to be measured for film thickness is produced.

[0061] Step S312: selecting a plurality of calibration unit selection areas having the same number in each calibration area.

[0062] refer to Figure 3 and Figure 2 The same number of, for example, six calibration unit selection areas may be selected in each calibration area 12 to form six calibration units corresponding to the six calibration unit selection areas in each calibration area 12 .

[0063] Step S313: For the calibration unit selection areas other than one of the calibration unit selection areas selected in each calibration area, part of the thickness of the film is removed in an increasing thickness gradient manner to form a plurality of calibration units of the same number in each calibration area, so that each calibration unit is formed by a homogeneous thin film formed on the chip, and each calibration unit in each calibration area has a surface height with a gradient change corresponding to the thickness of the film at the location.

[0064] A first mask is formed on the film 13 of the selected area of ​​the first calibration unit 121 selected in each calibration area 12. Figure 3 As shown, for convenience of explanation, for example, the selected area of ​​the first calibration unit 121 selected from the six calibration units may be located at the first row and first column position in the calibration area 12, the selected area of ​​the second calibration unit 122 selected may be located at the second row and first column position in the calibration area 12, the selected area of ​​the third calibration unit 123 selected may be located at the third row and first column position in the calibration area 12, the selected area of ​​the fourth calibration unit 124 selected may be located at the third row and second column position in the calibration area 12, the selected area of ​​the fifth calibration unit 125 selected may be located at the second row and second column position in the calibration area 12, and the selected area of ​​the sixth calibration unit 126 selected may be located at the first row and second column position in the calibration area 12. A first mask may be formed on the thin film 13 having a thickness of 10,000 angstroms in the selected area of ​​the first calibration unit 121 selected in each calibration area 12 by using a photolithography process. The above row and column positions of each calibration unit in the calibration area 12 are only used to illustrate an embodiment of the present invention. During actual production, the specific position of each calibration unit in the calibration area 12 can be arbitrarily configured, as long as the relative position of each calibration unit in each calibration area 12 is fixed.

[0065] Then, the film 13 with a partial thickness outside the first mask is removed, and a film 13 with a second thickness less than the first thickness is formed outside the first mask, and a first calibration unit 121 formed by the film 13 with the first thickness is formed in the selected area of ​​the first calibration unit 121. That is, the partial thickness of the film 13 on the selected area of ​​the second calibration unit 122 to the selected area of ​​the sixth calibration unit 126 is removed, for example, a partial thickness of 5000 angstroms is removed, so that the remaining second thickness of the film 13 after removing 5000 angstroms outside the first mask is 5000 angstroms (the value is for illustration only, the same below), that is, half of the first thickness of 10000 angstroms is removed. Thus, the first calibration unit 121 formed by the film 13 with a first thickness of 10000 angstroms is formed in the selected area of ​​the first calibration unit 121 shielded by the first mask.

[0066] Next, a second mask is formed on the thin film 13 in the selected area of ​​the first calibration unit 121 and the selected area of ​​the second calibration unit 122 in each calibration area 12. Then, the thin film 13 with a thickness outside the second mask is removed, for example, a portion of the thickness of 4000 angstroms is removed, and a thin film 13 with a third thickness of 1000 angstroms, which is less than the second thickness (5000 angstroms), is formed outside the second mask. In this way, a second calibration unit 122 formed of the thin film 13 with a second thickness of 5000 angstroms is formed in the selected area of ​​the second calibration unit 122.

[0067] By analogy, a third calibration unit 123 formed of a thin film 13 having a third thickness of 1000 angstroms can be formed in a selected area of ​​the third calibration unit 123, a fourth calibration unit 124 formed of a thin film 13 having a fourth thickness of 500 angstroms can be formed in a selected area of ​​the fourth calibration unit 124, a fifth calibration unit 125 formed of a thin film 13 having a fifth thickness of 100 angstroms can be formed in a selected area of ​​the fifth calibration unit 125, and a sixth calibration unit 126 formed of a thin film 13 having a sixth thickness of 50 angstroms can be formed in a selected area of ​​the sixth calibration unit 126. Thus, the same number of required six calibration units 121-126 are formed in each calibration area 12, so that each calibration unit is formed of a homogeneous thin film 13 formed on the calibration wafer substrate 11, and the six calibration units 121-126 in each calibration area 12 have six gradient decreasing surface heights from 10,000 angstroms to 50 angstroms corresponding to the thickness of the thin film 13 at the location, thereby forming six calibration levels defined by the surface height of the thin film 13 and distributed in a stepped manner, as shown in FIG. Figure 4 and Figure 3 shown.

[0068] In some embodiments, the thin film 13 may be formed by a chemical vapor deposition process.

[0069] In other embodiments, step S3 may also be performed and implemented in the following manner:

[0070] Step S321: selecting a plurality of calibration unit selection areas having the same number in each calibration area.

[0071] refer to Figure 3 , Figure 2 An equal number of selected areas, for example, six calibration units 121 - 126 , may be selected in each calibration area 12 to form six calibration units 121 - 126 in each calibration area 12 .

[0072] Step S322: A thin film stack composed of homogeneous thin films with increasing numbers of layers is formed between the selected areas of each calibration unit, so as to form a plurality of calibration units of the same number in each calibration area, so that each calibration unit is formed by a homogeneous thin film formed on the wafer, and each calibration unit in each calibration area has a surface height with a gradient variation corresponding to the thickness of the thin film stack at the location.

[0073] A thin film 13 of a first thickness is formed on the calibration sheet wafer substrate 11 to cover each defined calibration area 12 .

[0074] A first mask is formed on the film 13 of the first calibration unit 121 selected in each calibration area 12 to expose the surface of the film 13 of the second calibration unit 122 to the sixth calibration unit 126. Then, the film 13 other than the first mask is removed, and then the first mask is removed.

[0075] A thin film 13 of a second thickness is formed again on the calibration sheet wafer substrate 11 to cover each defined calibration area 12 .

[0076] A second mask is formed on the film 13 of the first calibration unit 121 selected area and the selected second calibration unit 122 selected area in each calibration area 12, exposing the surface of the film 13 of the third calibration unit 123 selected area to the sixth calibration unit 126 selected area. Then, the film 13 other than the second mask is removed, and then the second mask is removed.

[0077] And so on, until a film 13 of the sixth thickness is formed on the calibration wafer substrate 11 for the sixth time to cover each defined calibration area 12, a sixth calibration unit 126 selected in each calibration area 12 forms a sixth calibration unit 126 formed by a film 13 of the sixth thickness, and a plurality of calibration units formed by a stack of films 13 of corresponding thicknesses including a film 13 of the sixth thickness are correspondingly formed from the fifth calibration unit 125 selected area to the first calibration unit 121 selected area. That is, the fifth calibration unit 125 is formed by a stack of a film 13 having a sixth thickness and a film 13 having a fifth thickness, the fourth calibration unit 124 is formed by a stack of a film 13 having a sixth thickness to a film 13 having a fourth thickness, the third calibration unit 123 is formed by a stack of a film 13 having a sixth thickness to a film 13 having a third thickness, the second calibration unit 122 is formed by a stack of a film 13 having a sixth thickness to a film 13 having a second thickness, and the first calibration unit 121 is formed by a stack of a film 13 having a sixth thickness to a film 13 having a first thickness. Thereby, the required same number of six calibration units 121 to 126 are formed in each calibration area 12, and each calibration unit is formed by a homogeneous thin film 13 formed on the calibration wafer substrate 11, and the six calibration units 121 to 126 in each calibration area 12 have six gradient decreasing surface heights corresponding to the total thickness of the thin film 13 at their locations, for example, from 10,000 angstroms to 50 angstroms, thereby forming six calibration gears defined by the surface height of the thin film 13.

[0078] In some embodiments, when the thickness of the film 13 is above 1000 angstroms, a chemical vapor deposition process can be used to form a thicker film 13. When the thickness of the film 13 is below 1000 angstroms, a furnace process can be used to form a thinner film 13.

[0079] The thickness of the film 13 formed each time can be controlled and measured, so that the first calibration unit 121 to the sixth calibration unit 126 formed finally have a total thickness of the film 13 that decreases gradually, such as 10000 angstroms, 5000 angstroms, 1000 angstroms, 500 angstroms, 100 angstroms, and 50 angstroms. Figure 4 and Figure 3 shown.

[0080] Through the above method, calibration areas 12 arranged in an array can be formed on the calibration piece wafer substrate 11. Moreover, the positions of the calibration units with the same surface height in each calibration area 12 correspond to each other in the calibration area 12. At the same time, the film 13 is located on the calibration piece wafer substrate 11 at the corresponding process level when the film thickness measurement object film is made, and the material and manufacturing process conditions of the film 13 are consistent with the material and manufacturing process conditions of the film thickness measurement object film. Due to the thin film deposition process, there are certain differences in the thickness uniformity of the film layer on the entire silicon wafer, resulting in uneven film thickness at the center 1 and edge 2 positions. The calibration area 12 on the calibration piece 10 of the present invention is distributed on the entire wafer including the center 1 and edge 2 positions. Compared with the existing calibration piece with a single crystal silicon component having a uniform layer thickness, the data entered into the database of the film thickness measurement equipment using the calibration piece 10 of the present invention that matches the film layer characteristics of the actual product will be more accurate.

[0081] refer to Figure 2-Figure 4 A film thickness measurement calibration sheet 10 of the present invention comprises: a plurality of calibration areas 12 formed on a calibration sheet wafer substrate 11. For example, each calibration area 12 may be arranged in an array on the calibration sheet wafer substrate 11. A plurality of calibration units of the same number are formed in each calibration area 12, for example, six calibration units 121 to 126 of the same number are formed in each calibration area 12.

[0082] Each calibration unit is formed by a homogeneous thin film 13 formed on a calibration wafer substrate 11, and each calibration unit in each calibration area 12 (the first calibration unit 121 to the sixth calibration unit 126) has six gradient-varying surface heights corresponding to the thickness of the thin film 13 at the location, so as to form six calibration levels defined by surface heights.

[0083] In some embodiments, the calibration sheet 10 includes a first calibration sheet and a second calibration sheet, which are all consistent in material, size, calibration area 12, number and size of calibration units, etc. The first calibration sheet is used to calibrate the film thickness measuring device, and the second calibration sheet is used to verify the calibration result of the first calibration sheet.

[0084] In some embodiments, the first calibration patch and the second calibration patch are produced in the same batch.

[0085] The calibration sheet 10 of the present invention can be manufactured by using the above-mentioned method for manufacturing a film thickness measurement calibration sheet of the present invention, but is not limited thereto.

[0086] refer to Figure 5 Combined with reference Figure 2-Figure 4 The present invention provides a film thickness measurement and monitoring method, which is used to calibrate a film thickness measurement device and use the film thickness measurement device to measure the film thickness of a film to be measured. Specifically, it includes:

[0087] Step S11: providing a calibration sheet.

[0088] The calibration piece 10 made by the film thickness measurement calibration piece making method of the present invention or the film thickness measurement calibration piece 10 of the present invention can be used to calibrate a film thickness measuring device, and the film thickness measuring device can be used to measure the film thickness of a film to be measured.

[0089] Step S12: Select calibration areas located at different positions on the calibration sheet, use a film thickness measuring device to measure the film thickness of each calibration unit in the calibration area, and obtain measurement data.

[0090] like Figure 2 As shown, for example, according to the position requirement for measuring the film thickness of the film to be measured, a calibration area 12 located at different positions of the center 1 and the edge 2 can be selected, and a film thickness measuring device can be used to measure the film thickness of the six calibration units 121 to 126 in the calibration area 12 to obtain corresponding thickness measurement data.

[0091] Step S13: inputting the measurement data into the film thickness measurement device, updating the measurement standard of the film thickness measurement device, and completing calibration.

[0092] The thickness measurement data of the six calibration units 121 to 126 in the calibration area 12 at each position are input into the database of the film thickness measuring device to be calibrated, so as to update the measurement standard (or threshold range) of the film thickness measuring device, obtain the updated new measurement standard, and complete the calibration.

[0093] Step S14: Using the updated measurement standard, the film thickness of the thin film to be measured is measured.

[0094] In some embodiments, the updated new measurement standard may include multiple sub-measurement standards corresponding to calibration areas 12 at different positions. For example, multiple sub-measurement standards may be formed for calibration areas 12 at different positions of the center 1 and the edge 2 to form a set of measurement standards.

[0095] When measuring the film thickness of a thin film to be measured, a sub-measurement standard corresponding to the measurement position can be called to perform the film thickness measurement.

[0096] In some embodiments, the aforementioned consistent first calibration piece and second calibration piece can be used together as the calibration piece 10, and the first calibration piece is used to perform an initial calibration on the film thickness measurement device, and the second calibration piece is used to verify the initial calibration result of the first calibration piece, and when the verification result meets the set threshold requirement, the calibration is completed.

[0097] In some embodiments, after calibrating the film thickness measuring device, the calibration sheet 10 can be used to select the calibration area 12 and the calibration unit on the calibration sheet 10, and the film thickness measuring device can be used to measure the film thickness. By comparing the acquired measurement data with the standard value of the new measurement standard in the database, the accuracy of the film thickness measuring device during film thickness testing and the test accuracy after stepping movement can be monitored daily for real-time monitoring. When the film thickness is abnormal, the state of the film thickness measuring device can be checked in time to keep the film thickness measuring device in a normal working state in real time.

[0098] The present invention can be applied to the precise measurement of the thickness of dielectric films (or films of other applicable materials) of various thicknesses and different process levels including oxides, and can be applied to the calibration and daily monitoring of various film thickness measurement equipment.

[0099] In summary, the present invention can avoid the problem of multiple loading and unloading of calibration pieces of different film thickness levels during the calibration process, thereby not only saving time and improving the output rate, but also effectively reducing the risk of damage to the calibration piece during the transmission process. In particular, for the measurement of key layer film layers, the utilization rate of the film thickness measurement equipment can be significantly improved. In addition, by calling the sub-measurement standard corresponding to the measurement position for film thickness measurement, the measurement accuracy can be further improved, so that the actual thickness of the film at different areas on the product wafer can be accurately reflected, thereby playing an accurate guiding role in the process monitoring during the chip manufacturing process. Moreover, the calibration piece made by the manufacturing method of the present invention can minimize the difference between the calibration piece and the film of the film thickness measurement object. Compared with the existing calibration piece, the calibration piece of the present invention that is closer to the actual product is used for calibration, and the data entered into the database of the film thickness measurement equipment will be more accurate. At the same time, using the calibration piece of the present invention, the accuracy of the film thickness measurement equipment during the precision test and the test accuracy after the stepping movement can also be monitored in real time on a daily basis. In addition, a consistent double calibration piece can be used to form a double calibration mechanism, thereby ensuring the high accuracy of the data during the calibration of the calibration piece and the product measurement, and saving the relevant costs.

[0100] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A method for making a film thickness measurement calibration sheet, characterized in that: include: Providing wafers; defining a plurality of calibration areas on the wafer; A plurality of calibration units of the same number are formed in each of the calibration areas, so that each of the calibration units is formed by a homogeneous thin film formed on the chip, and the calibration units in each of the calibration areas have a surface height with a gradient change corresponding to the thickness of the thin film at the location.

2. The method for making a film thickness measurement calibration sheet according to claim 1, characterized in that: The forming of a plurality of calibration units of the same number in each calibration region, wherein each calibration unit is formed by a homogeneous thin film formed on the wafer, and each calibration unit in each calibration region has a surface height with a gradient corresponding to the thickness of the thin film at the location, specifically includes: forming a thin film of a preset thickness on the wafer to cover each of the defined calibration areas; Selecting a plurality of calibration unit selected areas of the same number in each of the calibration areas; Part of the thickness of the film is removed in an increasing thickness gradient manner between the calibration unit selection areas other than one of the calibration unit selection areas selected in each of the calibration areas, so as to form a plurality of calibration units of the same number in each of the calibration areas, so that each of the calibration units is formed by the homogeneous thin film formed on the chip, and the calibration units in each of the calibration areas have a surface height with a gradient change corresponding to the thickness of the film at the location.

3. The method for making a film thickness measurement calibration sheet according to claim 1, characterized in that: The forming of a plurality of calibration units of the same number in each calibration region, wherein each calibration unit is formed by a homogeneous thin film formed on the wafer, and each calibration unit in each calibration region has a surface height with a gradient corresponding to the thickness of the thin film at the location, specifically includes: Selecting a plurality of calibration unit selected areas of the same number in each of the calibration areas; Between the selected areas of each of the calibration units, a thin film stack composed of homogeneous thin films with successively increasing numbers of layers is formed, so as to form a plurality of calibration units of the same number in each of the calibration areas, so that each of the calibration units is formed by the homogeneous thin film formed on the chip, and the calibration units in each of the calibration areas have a surface height with a gradient variation corresponding to the thickness of the thin film stack at the location.

4. The method for making a film thickness measurement calibration sheet according to claim 1, characterized in that: The calibration areas are arranged on the wafer in an array covering the surface of the wafer.

5. The method for making a film thickness measurement calibration sheet according to claim 1, characterized in that: The calibration units in each calibration area with the same surface height have corresponding positions in the calibration area.

6. The method for making a film thickness measurement calibration sheet according to claim 1, characterized in that: The thin film is located on the wafer at a corresponding process level when the corresponding thin film to be measured for film thickness is manufactured, and the material and manufacturing process conditions of the thin film are consistent with those of the thin film to be measured for film thickness.

7. A film thickness measurement calibration sheet, characterized in that: include: a plurality of calibration regions formed on the wafer; A plurality of calibration units of the same number are formed in each of the calibration areas, and each of the calibration units is formed by a homogeneous thin film formed on the chip. A surface height with a gradient variation corresponding to the thickness of the thin film at the location exists between each of the calibration units in each of the calibration areas, so as to form a plurality of calibration positions defined by the surface height.

8. The film thickness measurement calibration sheet according to claim 7, characterized in that: The calibration sheet includes a first calibration sheet and a second calibration sheet that are consistent with each other. The first calibration sheet is used to calibrate the film thickness measuring device, and the second calibration sheet is used to verify the calibration result of the first calibration sheet.

9. The film thickness measurement calibration sheet according to claim 8, characterized in that: The first calibration sheet and the second calibration sheet are produced in the same batch.

10. A film thickness measurement and monitoring method, characterized in that: A film thickness measuring device is calibrated using a calibration sheet made by the method for making a film thickness measurement calibration sheet according to any one of claims 1 to 5 or a film thickness measurement calibration sheet according to any one of claims 6 to 8, and the film thickness measuring device is used to measure the film thickness of a thin film to be measured.

11. The film thickness measurement and monitoring method according to claim 10, characterized in that: The calibrating of the film thickness measuring device and using the film thickness measuring device to measure the film thickness of the film to be measured specifically include: Provide calibration sheets; Selecting calibration areas located at different positions on the calibration sheet, and using a film thickness measuring device to measure the film thickness of each calibration unit in the calibration area to obtain measurement data; Inputting the measurement data into the film thickness measuring device, updating the measurement standard of the film thickness measuring device, and completing calibration; Use the updated measurement standard to measure the film thickness of the thin film to be measured.

12. The film thickness measurement and monitoring method according to claim 11, characterized in that: The measurement standard includes a plurality of sub-measurement standards corresponding to the calibration areas at different positions. When measuring the film thickness of the film to be measured, one of the sub-measurement standards corresponding to the measurement position is called to perform the film thickness measurement.

13. The film thickness measurement and monitoring method according to claim 11, characterized in that: Also includes: A first calibration piece and a second calibration piece that are consistent are used as the calibration pieces, and the first calibration piece is used to perform an initial calibration on the film thickness measurement device, and the second calibration piece is used to verify the initial calibration result of the first calibration piece, and when the verification result meets the threshold requirement, the calibration is completed.

14. The film thickness measurement and monitoring method according to claim 11, characterized in that: Also includes: After calibrating the film thickness measuring device, use the calibration sheet, select the calibration area and the calibration unit on the calibration sheet, use the film thickness measuring device to measure the film thickness, compare the acquired measurement data with the measurement standard, and monitor the accuracy of the film thickness measuring device for real-time monitoring.

Images