Compensation method for overlay error

Abstract

The invention discloses an overlay error compensation method which comprises the steps that a grinding difference value after a CMP technology is obtained through calculation, and the grinding difference value is the difference value between the actual grinding amount and the target grinding amount after a wafer is ground through the CMP technology; calculating an overlay deviation value according to the grinding difference value, wherein the overlay deviation value is an influence numerical value of the CMP process on the overlay deviation of the wafer; and according to the overlay deviation value, compensating an overlay error when photoetching alignment is carried out on the wafer. According to the method, the grinding difference value after the CMP process is obtained through calculation, the overlay deviation value is obtained through calculation according to the grinding difference value, and the overlay error is compensated when photoetching alignment is carried out on the wafer according to the overlay deviation value, so that the influence of the CMP process on the accuracy and accuracy of the overlay error is solved, the hidden danger of OOS is reduced, and the yield of the wafer is improved. And the production efficiency is improved to a certain extent.

Description

Technical Field

[0001] This application relates to the technical field of semiconductor devices and integrated circuits, and particularly to a method for compensating overlay error. Background Art

[0002] Chemical mechanical polishing (CMP) process is an important process in semiconductor device manufacturing. It uses the synergistic effect of chemical corrosion and mechanical polishing to planarize semiconductor wafers, effectively taking into account the local and global flatness of semiconductor devices.

[0003] However, the CMP process will affect the overlay error (OVL) of the subsequent lithography process, and there is a certain probability that it will cause rotation deviation of the OVL pattern in lithography alignment and even exceed the out-of-spec limit (OOS). Therefore, there is an urgent need to provide a method for compensating the overlay error after the CMP process to compensate for the influence of the CMP process on the overlay error. Summary of the Invention

[0004] This application provides a method for compensating overlay error, which can solve the problem that the CMP process will affect the overlay error of the subsequent lithography process. The method includes:

[0005] Calculating the grinding difference after the CMP process, where the grinding difference is the difference between the actual grinding amount and the target grinding amount after grinding the wafer by the CMP process;

[0006] Calculating an overlay deviation value according to the grinding difference, where the overlay deviation value is the influence value of the CMP process on the overlay deviation of the wafer;

[0007] Compensating the overlay error during lithography alignment of the wafer according to the overlay deviation value.

[0008] In some embodiments, the overlay deviation value is the rotation deviation value of the OVL pattern on the wafer.

[0009] In some embodiments, calculating the overlay deviation value according to the grinding difference includes:

[0010] Calculating the rotation deviation value of the OVL pattern according to the grinding difference based on a preset functional relationship, where the rotation deviation value of the OVL pattern is a quadratic function of the grinding difference.

[0011] In some embodiments, before calculating the grinding difference after the CMP process, it further includes:

[0012] Obtain historical data, where the historical data includes historical grinding difference values and historical rotation deviation values;

[0013] Fit the preset functional relationship according to the historical data.

[0014] In some embodiments, the lithography alignment is performed in the next process after the CMP process.

[0015] The technical solution of the present application has at least the following advantages:

[0016] By calculating the grinding difference value after the CMP process, calculating the overlay error value based on the grinding difference value, and compensating for the overlay error during the lithography alignment of the wafer according to the overlay error value, the influence of the CMP process on the accuracy and precision of the overlay error is solved, the hidden danger of OOS is reduced, and the production efficiency is improved to a certain extent. Description of the Drawings

[0017] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 is a flowchart of a method for compensating overlay error provided by an exemplary embodiment of the present application. Detailed Embodiments

[0019] The following will clearly and completely describe the technical solutions in the present application in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0020] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0021] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "linkage" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can also be the communication inside two components. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0022] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0023] Refer to Figure 1 , which shows a flowchart of a method for compensating overlay error provided by an exemplary embodiment of the present application. As Figure 1 shown, the method includes:

[0024] Step S1, calculate the grinding difference after the CMP process. The grinding difference is the difference between the actual grinding amount and the target grinding amount after grinding the wafer through the CMP process.

[0025] Exemplarily, the thickness H1 of the wafer before grinding and the thickness H2 after grinding can be measured, the difference between H1 and H2 is calculated to obtain the actual grinding amount, and the grinding difference is calculated according to the actual grinding amount and the preset target grinding amount. After the CMP process is performed on the wafer, lithography alignment is required in the next process.

[0026] Step S2, calculate the overlay deviation value according to the grinding difference. The overlay deviation value is the influence value of the CMP process on the overlay deviation of the wafer.

[0027] Among them, the overlay deviation value is the rotation deviation value of the OVL pattern on the wafer. Exemplarily, step S2 includes but is not limited to: calculating the rotation deviation value of the OVL pattern according to the grinding difference and a preset functional relationship. Among them, the rotation deviation value of the OVL pattern is a quadratic function of the grinding difference. For example, the rotation deviation value of the OVL pattern can be calculated through the following formula:

[0028] y = Ax 2 + Bx + C

[0029] Among them, y is the rotation deviation value of the OVL pattern, x is the grinding difference, and A, B, and C are constants that can be obtained by fitting historical data. Exemplarily, before step S1, it further includes: obtaining historical data, where the historical data includes historical grinding differences and historical rotation deviation values; and fitting the above quadratic function according to the historical data.

[0030] Step S3: Compensate for the overlay error during the lithography alignment of the wafer according to the overlay deviation value.

[0031] After calculating the rotation deviation value, the overlay error can be compensated during the lithography alignment of the wafer.

[0032] In summary, in the embodiment of the present application, by calculating the grinding difference value after the CMP process, obtaining the overlay deviation value according to the grinding difference value, and compensating for the overlay error during the lithography alignment of the wafer according to the overlay deviation value, the influence of the CMP process on the accuracy and precision of the overlay error is solved, the hidden danger of OOS is reduced, and the production efficiency is improved to a certain extent.

[0033] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for compensating overlay error, characterized in that, Comprising: Calculating the grinding difference after the CMP process, where the grinding difference is the difference between the actual grinding amount and the target grinding amount after grinding the wafer by the CMP process; Calculating the overlay deviation value according to the grinding difference, where the overlay deviation value is the influence value of the overlay deviation of the CMP process on the wafer; Compensating for the overlay error during lithography alignment of the wafer according to the overlay deviation value.

2. The method according to claim 1, wherein The overlay deviation value is the rotation deviation value of the OVL pattern on the wafer.

3. The method according to claim 2, wherein The calculating the overlay deviation value according to the grinding difference includes: Calculating the rotation deviation value of the OVL pattern according to the grinding difference based on a preset functional relationship, where the rotation deviation value of the OVL pattern is a quadratic function of the grinding difference.

4. The method according to claim 3, characterized in that, Before calculating the grinding difference after the CMP process, it further includes: Obtaining historical data, where the historical data includes historical grinding differences and historical rotation deviation values; Fitting the preset functional relationship according to the historical data.

5. The method according to any one of claims 1 to 4, characterized in that, Lithography alignment is performed in the next process after the CMP process.

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