Method for correcting overlay accuracy based on a carrier table

Abstract

The application provides a kind of overlay accuracy correction method based on bearing table, comprising: obtaining the historical warping data of bearing table surface and the historical overlay accuracy data of substrate after lithography on bearing table corresponding thereto;Mapping relationship of historical warping data and historical overlay accuracy data is constructed, and the mapping relationship includes that different overlay accuracy is obtained by the warping of bearing table in different areas of substrate;The warping of bearing table is detected, and according to the mapping relationship, the predicted overlay accuracy of the different areas of substrate placed on bearing table is obtained, and the corresponding overlay accuracy compensation is selected based on the different areas of preset overlay accuracy on substrate.The application, by detecting the warping of bearing table, uses the mapping relationship to compensate the overlay accuracy of different areas of substrate during lithography, not only improves the overlay accuracy during lithography process, but also prolongs the service life of the object table relatively, so as to reduce the cost and improve the utilization rate of machine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a method for correcting overlay accuracy based on a carrier table. BACKGROUND

[0002] Overlay accuracy refers to the position accuracy of a layer pattern and a previous layer pattern in a photolithography manufacturing process, which is one of the key parameters for measuring photolithography process, and with the improvement of product manufacturing process, the requirement for overlay accuracy between different layers of devices is getting higher and higher.

[0003] The carrier table is used to carry a substrate in a photolithography process (exposure process). In the exposure process, the edge of the carrier table gradually appears a certain amount of warping, so that the substrate adsorbed on the carrier table also appears a similar warping. The warping will cause the overlay accuracy of the substrate after exposure to be different, which may cause poor focusing or even yield loss. That is, the carrier table is a kind of consumable, and its service life is limited.

[0004] At present, the carrier table with a service life close to the end is usually replaced to ensure the photolithography yield, but frequent replacement of the carrier table not only consumes machine time, but also is not conducive to cost reduction. SUMMARY

[0005] The present application aims to provide a method for correcting overlay accuracy based on a carrier table, which prolongs the service life of the carrier table.

[0006] To solve the above technical problems, the present application provides a method for correcting overlay accuracy based on a carrier table, which comprises:

[0007] Obtaining historical warping data of the surface of the carrier table and historical overlay accuracy data of the substrate after photolithography on the carrier table corresponding to the historical warping data;

[0008] Constructing a mapping relationship between the historical warping data and the historical overlay accuracy data, wherein the mapping relationship includes that different overlay accuracies are obtained by the warping degree of the carrier table in different areas of the substrate;

[0009] Detecting the warping degree of the carrier table, obtaining the predicted overlay accuracy of the substrate in different areas of the carrier table according to the mapping relationship, and selecting the corresponding overlay accuracy compensation in different areas of the substrate based on the preset overlay accuracy.

[0010] Optionally, the historical overlay accuracy data of the substrate after photolithography on the carrier table corresponding to the historical warping data includes the overlay accuracy data of each at least two substrates passing through the carrier table before and after the historical warping data is measured.

[0011] Optionally, the historical overlay accuracy data is obtained by using a first-order linear compensation.

[0012] Optionally, the historical overlay accuracy data is obtained by using a first-order linear compensation.

[0013] Optionally, the historical overlay accuracy data is obtained by using a first-order linear compensation.

[0014] Optionally, the historical overlay accuracy data is obtained by using a first-order linear compensation.

[0015] Optionally, the historical overlay accuracy data is obtained by using a first-order linear compensation.

[0016] Optionally, the historical overlay accuracy data is obtained by using a first-order linear compensation.

[0017] Optionally, the historical overlay accuracy data is obtained by using a first-order linear compensation.

[0018] Optionally, the historical overlay accuracy data is obtained by using a first-order linear compensation.

[0019] In summary, the present application obtains historical warping data of a bearing table surface and corresponding historical overlay accuracy data to construct a mapping relationship therebetween, and the overlay accuracy of different regions of a substrate can be obtained from the warping of the bearing table by using the mapping relationship. The warping of the bearing table is detected, the predicted overlay accuracy of the substrate in different regions on the bearing table is obtained according to the above mapping relationship, and corresponding overlay accuracy compensation is selected for different regions of the substrate when performing a photolithography process based on a preset overlay accuracy. This not only improves the overlay accuracy during the photolithography process, but also ensures the overlay accuracy through corresponding overlay accuracy compensation when the warping of the bearing table is slightly over-standard, thereby relatively prolonging the service life of the bearing table, reducing costs, and improving machine utilization. BRIEF DESCRIPTION OF DRAWINGS

[0020] Those skilled in the art will understand that the provided drawings are for the purpose of better illustrating the present application and do not constitute any limitation on the scope of the present application.

[0021] Figure 1 A flowchart of the overlay accuracy correction method based on a bearing table provided by the embodiment of the present application is shown. DETAILED DESCRIPTION

[0022] To make the objectives, advantages and features of the present application clearer, the following further describes the present application in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are very simplified and not drawn to scale, and are only used to facilitate and clarify the purpose of assisting the description of the embodiment of the present application. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis shown in each drawing is different, and sometimes different scales are used.

[0023] As used in the present application, the singular forms "a", "an" and "the" include plural referents, the term "or" is generally used in the sense of "and / or", the term "several" is generally used in the sense of "at least one", the term "at least two" is generally used in the sense of "two or more", and in addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first", "second", "third" can explicitly or implicitly include one or at least two features, unless the content clearly indicates otherwise.

[0024] Figure 1 A flowchart of the overlay accuracy correction method based on a bearing table provided by the embodiment of the present application is shown.

[0025] As Figure 1 shown, the overlay accuracy correction method based on a bearing table provided by the embodiment of the present application comprises:

[0026] S01: Obtain historical warping degree data of a bearing table surface and historical overlay accuracy data of a substrate after lithography on the bearing table corresponding to the historical warping degree data;

[0027] S02: Construct a mapping relationship between the historical warping degree data and the historical overlay accuracy data, the mapping relationship comprising that different overlay accuracies are obtained by warping degrees of the bearing table in different regions of the substrate;

[0028] S03: Detect the warping degree of the bearing table, obtain the predicted overlay accuracy of the substrate in different regions placed on the bearing table according to the mapping relationship, and select the corresponding overlay accuracy compensation in different regions on the substrate based on the preset overlay accuracy.

[0029] The lithography machine performing the lithography process in the embodiment can be any suitable lithography machine, such as a stepper or a scanner, and the substrate can be any suitable material, such as silicon, quartz, glass, or ceramic. The following will be described in combination with Figure 1 The overlay accuracy correction method based on the carrier table is described in detail.

[0030] First, step S01 is performed to obtain historical warping data of the carrier table surface and historical overlay accuracy data of the substrate after lithography on the carrier table corresponding to the historical warping data.

[0031] In the historical point inspection data of the lithography machine carrier table, different warping data of the carrier table surface is obtained, and according to the time point of measuring the warping of the carrier table (measuring time point), the overlay accuracy data of at least two substrates before and after the corresponding measuring time point is obtained from the overlay accuracy measurement data of the substrate; the overlay accuracy of at least two substrates at the measuring time point is averaged to obtain the overlay accuracy data of the measuring time point. Of course, before averaging, outliers in the overlay accuracy data can also be removed to improve the credibility of the data.

[0032] In addition, in some examples, as many overlay accuracy data as possible can also be collected for all exposure regions of the substrate before and after the warping measurement time point of the carrier table to specifically accumulate historical overlay accuracy data for subsequent mapping relationship construction.

[0033] Next, step S02 is performed to construct a mapping relationship between the historical warping data and the historical overlay accuracy data, and the mapping relationship includes different overlay accuracies obtained by the warping of the carrier table in different regions of the substrate.

[0034] The historical overlay accuracy data can include overlay accuracy distributed in each exposure region of the substrate, that is, it includes the overlay accuracy data of the entire surface (close to) of the substrate. If the substrate is considered to have uniform thickness and is adsorbed on the carrier table, the surface warping of the substrate can be approximated to the warping of the carrier table surface. In the center of the substrate, the warping height is small (which can be approximated to 0), and the warping height gradually increases from the center of the substrate to the edge of the substrate. Therefore, it can be understood that if the lithography process is performed according to the overlay accuracy requirement of the middle region of the substrate, the overlay accuracy gradually decreases from the center of the substrate to the edge of the substrate, in other words, the corresponding overlay accuracy requirement gradually increases from the center of the substrate to the edge of the substrate. Therefore, in the embodiment, according to the warping height of different regions of the carrier table, that is, the overlay accuracy requirement of different regions, the corresponding overlay accuracy compensation is performed through the establishment of the mapping relationship, thereby improving the overlay accuracy during lithography.

[0035] For example, when the substrate and the carrier are both circular, the surface of the substrate can be divided into a central region and N annular regions arranged around the central region, the first to the Nth annular regions being arranged concentrically from the center of the substrate to the edge of the substrate, the substrate having different overlay accuracies (i.e., overlay accuracy requirements) in the first to the Nth annular regions, N being an integer greater than or equal to 1. The overlay accuracy data of the substrate can include the overlay accuracies and corresponding widths (annular ring widths) of the first to the Nth annular regions. In practice, the overlay accuracy and width of the Nth annular region (the annular region closest to the edge) can be preferably represented for ease of calculation.

[0036] Specifically, the least square method can be used to fit the historical warping data and the corresponding historical overlay accuracy data to construct a mapping relationship therebetween. The mapping relationship can be used to obtain the overlay accuracy data corresponding to the warping data of the carrier. The overlay accuracy data at least includes the overlay accuracy and width of the Nth annular region.

[0037] In addition, the overlay accuracy compensation relationship is also established. The compensation mode matching the overlay accuracy is obtained from the overlay accuracy compensation relationship, i.e., the compensation mode corresponding to the overlay accuracy of different regions of the substrate is provided to meet the overlay accuracy requirement thereof. The compensation mode provided includes a first-order linear compensation mode and a high-order nonlinear compensation mode. The high-order nonlinear compensation mode can include, for example, a third-order nonlinear compensation, a fifth-order nonlinear compensation, etc. In an example, the first-order linear compensation mode can be used for the central region of the substrate, and the corresponding high-order nonlinear compensation mode can be used for the first to the Nth annular regions.

[0038] It should be noted that as the photolithography process continues, the warping of the carrier also gradually increases. If the warping of the surface of the carrier is less than or equal to a first preset value, the first-order linear compensation mode can be used for the substrate to simplify the setting and improve the execution efficiency. If the warping of the surface of the carrier is greater than the first preset value and less than a second preset value (the second preset value being greater than the first preset value), the first-order linear compensation mode or the high-order nonlinear compensation mode can be used for different regions for compensation. If the warping of the surface of the carrier is greater than or equal to the second preset value, it indicates that the warping of the carrier exceeds the compensation range of the overlay accuracy, and the carrier needs to be replaced. The first preset value can be the warping of the carrier at the end of the designed service life, and the second preset value can be the maximum warping that can be compensated by using the high-order nonlinear compensation mode. In a specific example, taking a substrate with a diameter of 300 mm as an example, the first preset value of the carrier can be 100 microns, and the second preset value can be 110 microns. It can be seen that the service life of the carrier can be extended from the warping of 100 microns to the warping of 110 microns by using the overlay accuracy correction method provided in the embodiment, which can extend the service life of the carrier by about 10% to 20%.

[0039] In addition, the overlay accuracy correction method provided by the embodiment can also improve overlay accuracy, reduce poor focus and reduce yield loss.

[0040] Then, the warping degree of the bearing table is detected in step S03, the predicted overlay accuracy of different regions of the substrate on the bearing table is obtained according to the mapping relationship, and the corresponding overlay accuracy compensation is selected for different regions of the substrate based on the preset overlay accuracy.

[0041] The warping degree of the bearing table of the photolithography machine can be measured in a direct or indirect manner, for example, the warping degree of the bearing table is directly measured by using an optical surface measuring instrument, or a standard substrate is placed on the bearing table, and then the height of the standard substrate in the vertical direction is detected to indirectly measure the warping degree of the bearing table. It can be understood that the method for obtaining the warping degree of the bearing table can be the same as the method for obtaining the historical warping degree data of the bearing table as described above, so as to improve the matching degree of the two.

[0042] After obtaining the warping degree of the bearing table, the overlay accuracy corresponding to the warping degree, i.e., the predicted overlay accuracy, can be obtained by using the mapping relationship between the historical warping degree data and the historical overlay accuracy data, including the overlay accuracy and the width of the ring-shaped regions (the first to the Nth ring-shaped regions).

[0043] After obtaining the overlay accuracy distribution of the first to the Nth ring-shaped regions, the corresponding overlay accuracy compensation mode is used for the first to the Nth ring-shaped regions according to the overlay accuracy compensation relationship established above, so as to meet the overlay accuracy requirement, and the photolithography process is performed, so as to achieve the effect of prolonging the service life of the bearing table and improving the overlay accuracy.

[0044] Of course, the photolithography process is performed by selecting the corresponding overlay accuracy compensation from the predicted overlay accuracy, and the overlay accuracy detection is performed on the substrate.

[0045] In summary, the historical warping degree data of the bearing table surface and the corresponding historical overlay accuracy data are obtained, the mapping relationship between the two is constructed, the overlay accuracy of different regions of the substrate can be obtained from the warping degree of the bearing table by using the mapping relationship, the warping degree of the bearing table is detected, the predicted overlay accuracy of the substrate on the bearing table in different regions is obtained according to the mapping relationship, and the corresponding overlay accuracy compensation is selected for different regions of the substrate based on the preset overlay accuracy when the photolithography process is performed. The overlay accuracy of the photolithography process can be improved, and when the warping degree of the bearing table is slightly over-standard, the overlay accuracy can be ensured by the corresponding overlay accuracy compensation, so that the service life of the bearing table is relatively prolonged, thereby reducing the cost and improving the utilization rate of the machine.

[0046] The above description is only the description of the preferred embodiments of the present application, and is not any limitation on the scope of the present application. Any change and modification made by the person skilled in the art according to the above disclosure is within the protection scope of the claims.

Claims

1. A method for overlay accuracy correction based on a carrier table, characterized in that, The method comprises: acquiring historical warping data of a surface of a carrier table and historical overlay accuracy data corresponding to the historical warping data after photolithography of a substrate on the carrier table, the historical overlay accuracy data comprising overlay accuracy data of each at least two substrates passing through the carrier table before and after the historical warping data is measured; fitting the historical warping data and the historical overlay accuracy data by using a least square method to construct a mapping relationship between the historical warping data and the historical overlay accuracy data, the mapping relationship comprising that different overlay accuracies are obtained by warping of the carrier table in different regions of the substrate; detecting warping of the carrier table, obtaining preset overlay accuracies of different regions of the substrate placed on the carrier table according to the mapping relationship, and selecting corresponding overlay accuracy compensation based on the preset overlay accuracies in different regions of the substrate.

2. The method of claim 1, wherein, The historical overlay accuracy data is obtained by using a first-order linear compensation.

3. The method of claim 1, wherein, According to the mapping relationship, widths of different annular regions of the substrate and overlay accuracies of the different annular regions are obtained by using warping of the carrier table.

4. The method of claim 1, wherein, After the mapping relationship is obtained, an overlay accuracy compensation relationship is also established, and a compensation mode matched with the overlay accuracy is obtained by using the overlay accuracy compensation relationship according to the overlay accuracy.

5. The method of claim 4, wherein, The compensation mode comprises a first-order linear compensation mode and a high-order nonlinear compensation mode.

6. The method of claim 1, wherein, The substrate is circular, warping of the surface of the carrier table is greater than a first preset value and less than a second preset value, a surface of the substrate is divided into a central region and N annular regions arranged around the central region, the first to Nth annular regions are concentrically arranged from the center to the edge of the substrate, the substrate has different overlay accuracies in the first to Nth annular regions, and N is an integer greater than or equal to 1.

7. The method of claim 6, wherein, The first-order linear compensation mode is used for the central region, and the high-order nonlinear compensation mode is used for the first to Nth annular regions.

8. The method of claim 6, wherein the method further comprises: Warping of the surface of the carrier table is less than or equal to the first preset value, and the first-order linear compensation mode is used for the substrate.

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