Methods for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy

Abstract

The application provides a method for verifying whether compensation of overlay accuracy by AEI OVL is effective, comprising: if there is a compensation deviation between the post-development overlay mark pattern and the post-etching overlay mark pattern, then the overlay deviation; obtaining feature pattern deviation; according to the overlay deviation and the feature pattern deviation, point-to-point modeling is performed to obtain a fitting curve, and a K value and a correlation coefficient R of the fitting curve are obtained 2 ; according to the correlation coefficient R 2 and the K value, it is judged whether the way of compensating overlay accuracy by AEI OVL is effective. The application obtains a fitting curve through modeling of the overlay deviation and the feature pattern deviation, and judges whether the way of compensating overlay accuracy by AEI OVL is effective through the correlation coefficient R 2 and the K value of the fitting curve, ensures the accuracy and reliability of feedback based on AEI OVL measurement, and thus improves the final real overlay accuracy of the layer.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and specifically to a method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy. Background Technology

[0002] With the continuous improvement of IC chip manufacturing processes, the requirements for overlay accuracy (OVL) are becoming increasingly stringent, especially for advanced processes below 28nm. Generally, after exposure and development, ADI (Advanced Difference Indication) OVL measurement is performed on the wafer. However, certain special etching processes can significantly affect the AEI (Advanced Etching Indication) OVL. In actual production, AEI OVL compensation feedback can be used to improve the deviation between ADI OVL and AEI OVL (ADI OVL minus AEI OVL). Therefore, verifying the accuracy of overlay accuracy based on AEI OVL compensation is particularly important. Summary of the Invention

[0003] This application provides a method for verifying the effectiveness of AEI OVL compensation for overlay accuracy, which can solve the problem of how to verify the accuracy of overlay accuracy based on AEI OVL compensation.

[0004] This application provides a method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, including:

[0005] Wafers with acceptable overlay deviations after development were selected as wafers to be verified.

[0006] The wafer to be verified is exposed and developed to obtain a developed overlay marking pattern;

[0007] The wafer to be verified is etched to obtain an etched overlay marking pattern, wherein AEI OVL is used to compensate for the overlay accuracy during the photolithography process;

[0008] Based on the overlay marking pattern after development and the overlay marking pattern after etching, determine whether there is a compensation deviation;

[0009] If the aforementioned compensation deviation exists, the overlay deviation is obtained based on the overlay marking patterns after etching of different layers;

[0010] The key dimensions of the AEI feature pattern on the wafer to be verified were obtained by electron beam scanning and electron microscopy.

[0011] Based on the key dimensions of the AEI feature images of different layers, obtain the feature image deviation;

[0012] Based on the overlay deviation and the feature pattern deviation, point-to-point modeling is performed to obtain a fitting curve, and the K value and correlation coefficient R of the fitting curve are obtained. 2 ;as well as

[0013] According to the correlation coefficient R 2 And the K value, to determine whether the method of using AEI OVL to compensate for overlay accuracy is effective.

[0014] Optionally, in the method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, the step of using the correlation coefficient R... 2 The steps for determining whether using AEI OVL to compensate for overlay accuracy, and the aforementioned K value, include:

[0015] If the correlation coefficient R 2 If the value is greater than 0.7 and the K value is close to 1, then the method of using AEI OVL to compensate for overlay accuracy is deemed effective.

[0016] Optionally, in the method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, the step of obtaining the overlay deviation based on the overlay mark pattern after etching of different layers if the compensation deviation exists includes:

[0017] If the compensation deviation exists, the overlay deviation in the X direction and the overlay deviation in the Y direction are obtained according to the overlay marking pattern after etching of different layers.

[0018] Optionally, in the method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, the step of obtaining the feature pattern deviation based on the key dimensions of the AEI feature patterns of different layers includes:

[0019] Based on the key dimensions of the AEI feature images of different layers, the deviation of the feature images in the X direction and the deviation of the feature images in the Y direction are obtained respectively.

[0020] Optionally, in the method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, the step of performing point-to-point modeling based on the overlay deviation and the feature pattern deviation to obtain a fitting curve, and obtaining the K value and correlation coefficient R of the fitting curve. 2 The steps include:

[0021] Based on the overlay deviation in the X direction and the deviation of the feature pattern in the X direction, point-to-point modeling is performed to obtain the first fitting curve;

[0022] Based on the overlay deviation in the Y direction and the deviation of the feature pattern in the Y direction, point-to-point modeling is performed to obtain the second fitting curve;

[0023] Obtain the K value and correlation coefficient R of the first fitted curve respectively. 2 The K value and correlation coefficient R of the second fitted curve 2 .

[0024] Optionally, in the method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, the step of using the correlation coefficient R... 2 The steps for determining whether using AEI OVL to compensate for overlay accuracy, and the aforementioned K value, include:

[0025] If the correlation coefficient R of the first fitted curve 2 A value greater than 0.7 and a K value close to 1, and the K value and correlation coefficient R of the second fitted curve are... 2 If the value of K is greater than 0.7 or close to 1, then the method of using AEI OVL to compensate for overlay accuracy is deemed effective; otherwise, the method of using AEI OVL to compensate for overlay accuracy is deemed invalid.

[0026] The technical solution of this application has at least the following advantages:

[0027] This application provides a method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, comprising: if there is a compensation deviation between the overlay mark pattern after development and the overlay mark pattern after etching, then the overlay deviation is identified; the feature pattern deviation is obtained; based on the overlay deviation and the feature pattern deviation, point-to-point modeling is performed to obtain a fitting curve, and the K value and correlation coefficient R of the fitting curve are obtained. 2 According to the correlation coefficient R 2 And the K value, to determine whether the method of using AEI OVL to compensate for overlay accuracy is effective. This application obtains a fitting curve by modeling overlay deviation and feature pattern deviation, and uses the correlation coefficient R of the fitting curve to determine the effectiveness. 2 The K value is used to determine whether the method of using AEI OVL to compensate for overlay accuracy is effective, ensuring the accuracy and reliability of measurement feedback based on AEI OVL, thereby improving the final true overlay accuracy of the layer. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a flowchart of a method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, according to an embodiment of the present invention. Detailed Implementation

[0030] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0033] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0034] This application provides a method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, referencing... Figure 1 The method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy includes:

[0035] Step S10: Select wafers with acceptable overlay deviations after development as wafers to be verified.

[0036] Step S20: Expose and develop the wafer to be verified to obtain a developed overlay marking pattern;

[0037] Step S30: Etch the wafer to be verified to obtain an etched overlay marking pattern, wherein AEI OVL is used to compensate for overlay accuracy during the photolithography process.

[0038] It is worth noting that, in this embodiment of the application, after using AEI OVL to compensate for over-overlay accuracy, the wafer to be verified is subjected to a series of processes such as exposure, development and etching.

[0039] Step S40: Determine whether there is a compensation deviation based on the overlay marking pattern after development and the overlay marking pattern after etching.

[0040] Step S50: If the compensation deviation exists, the overlay deviation is obtained based on the overlay marking pattern after etching of different layers; if there is no compensation deviation, it is not necessary to execute steps S60-S90 to determine that the method of using AEI OVL to compensate for overlay accuracy is effective.

[0041] Preferably, step S50 can be specifically as follows: if the compensation deviation exists, then according to the overlay marking pattern after etching of different layers, the overlay deviation ΔX in the X direction and the overlay deviation ΔY in the Y direction are obtained respectively.

[0042] Step S60: Obtain the key dimensions of the AEI feature pattern on the wafer to be verified by electron beam scanning and electron microscopy scanning;

[0043] Step S70: Obtain the feature image deviation based on the key dimensions of the AEI feature images of different layers;

[0044] Preferably, step S70 can be specifically as follows: based on the key dimensions of the AEI feature graphics of different layers, obtain the deviation Overlay shift_X of the feature graphics in the X direction and the deviation Overlay shift_Y of the feature graphics in the Y direction.

[0045] Furthermore, the formula for calculating the overlay shift_X, the deviation of the feature pattern in the X direction, can be:

[0046] Overlay shift_X=(CD_X1-CD_X2) / 2;

[0047] Wherein, Overlay shift_X is the offset of the feature pattern in the X direction, CD_X1 is the critical dimension of the previous layer ADI feature pattern in the X direction, and CD_X2 is the critical dimension of the current layer ADI feature pattern in the X direction.

[0048] Furthermore, the formula for calculating the overlay shift_X, the deviation of the feature graphic in the Y direction, can be:

[0049] Overlay shift_Y=(CD_Y1-CD_Y2) / 2;

[0050] Wherein, Overlay shift_Y is the offset of the feature pattern in the Y direction, CD_Y1 is the critical dimension of the previous layer ADI feature pattern in the Y direction, and CD_Y2 is the critical dimension of the current layer ADI feature pattern in the Y direction.

[0051] Step S80: Based on the overlay deviation and the feature pattern deviation, perform point-to-point modeling to obtain a fitting curve, and obtain the K value and correlation coefficient R of the fitting curve. 2 .

[0052] Preferably, step S80 can specifically be as follows:

[0053] Step S80.1: Based on the overlay deviation in the X direction and the deviation of the feature pattern in the X direction, point-to-point modeling is performed to obtain the first fitting curve. Specifically, linear fitting is performed with the overlay deviation in the X direction as the abscissa and the deviation of the feature pattern in the X direction as the ordinate to establish the first fitting curve, and the first fitting function is obtained based on the first fitting curve.

[0054] Step S80.2: Based on the overlay deviation in the Y direction and the deviation of the feature pattern in the Y direction, point-to-point modeling is performed to obtain a second fitting curve. Specifically, linear fitting is performed with the overlay deviation in the Y direction as the abscissa and the deviation of the feature pattern in the Y direction as the ordinate to establish a second fitting curve, and a second fitting function is obtained based on the second fitting curve; wherein, both the first fitting function and the second fitting function are linear functions.

[0055] Step S80.3: Obtain the K value and correlation coefficient R of the first fitted curve (first fitting function) respectively. 2 The K value and correlation coefficient R of the second fitted curve (second fitted function) 2 .

[0056] Step S90: Based on the correlation coefficient R 2 And the K value, to determine whether the method of using AEI OVL to compensate for overlay accuracy is effective.

[0057] Preferably, step S90 can be specifically as follows:

[0058] If the correlation coefficient R of the first fitted curve 2 A value greater than 0.7 and a K value close to 1, and the K value and correlation coefficient R of the second fitted curve are... 2 If the value of K is greater than 0.7 and close to 1, then the method of using AEI OVL to compensate for overlay accuracy is deemed effective.

[0059] If the correlation coefficient R of the first fitted curve 2The K value is less than 0.7, or the K value is less than 0.85, or the K value and correlation coefficient R of the second fitted curve are less than 0.7. 2 If the value is less than 0.7 or the K value is less than 0.85, then the method of using AEI OVL to compensate for overlay accuracy is deemed invalid.

[0060] In this embodiment, a K value greater than or equal to 0.85 is considered to be a K value close to 1.

[0061] In this application, a first fitting curve is obtained by modeling the overlay deviation in the X direction and the deviation of the feature pattern in the X direction, and a second fitting curve is obtained by modeling the overlay deviation in the Y direction and the deviation of the feature pattern in the Y direction. The correlation coefficient R of the first fitting curve is then used to model the curve. 2 The correlation coefficient R between the K value and the second fitted curve 2 The K value is used to determine whether the method of using AEI OVL to compensate for overlay accuracy is effective, ensuring the accuracy and reliability of measurement feedback based on AEI OVL, thereby improving the final true overlay accuracy of the layer.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy, characterized in that, include: Wafers with acceptable overlay deviations after development were selected as wafers to be verified. The wafer to be verified is exposed and developed to obtain a developed overlay marking pattern; The wafer to be verified is etched to obtain an etched overlay marking pattern, wherein AEIOVL is used to compensate for the overlay accuracy during the photolithography process; Based on the overlay marking pattern after development and the overlay marking pattern after etching, determine whether there is a compensation deviation; If the aforementioned compensation deviation exists, the overlay deviation is obtained based on the overlay marking patterns after etching of different layers; The key dimensions of the AEI feature pattern on the wafer to be verified were obtained by electron beam scanning and electron microscopy. Based on the key dimensions of the AEI feature images of different layers, obtain the feature image deviation; Based on the overlay deviation and the feature pattern deviation, point-to-point modeling is performed to obtain a fitting curve, and the K value and correlation coefficient R of the fitting curve are obtained. 2 ;as well as According to the correlation coefficient R 2 And the K value, to determine whether the method of using AEI OVL to compensate for overlay accuracy is effective.

2. The method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy according to claim 1, characterized in that, The correlation coefficient R 2 The steps for determining whether using AEI OVL to compensate for overlay accuracy, and the aforementioned K value, include: If the correlation coefficient R 2 If the value is greater than 0.7 and the K value is greater than or equal to 0.85, then the method of using AEI OVL to compensate for overlay accuracy is deemed effective.

3. The method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy according to claim 1, characterized in that, If the compensation deviation exists, the step of obtaining the overlay deviation based on the overlay marking pattern after etching of different layers includes: If the compensation deviation exists, the overlay deviation in the X direction and the overlay deviation in the Y direction are obtained according to the overlay marking pattern after etching of different layers.

4. The method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy according to claim 3, characterized in that, The step of obtaining the feature image deviation based on the key dimensions of the AEI feature images of different layers includes: Based on the key dimensions of the AEI feature images of different layers, the deviation of the feature images in the X direction and the deviation of the feature images in the Y direction are obtained respectively.

5. The method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy according to claim 4, characterized in that, The process involves performing point-to-point modeling based on the overlay deviation and the feature pattern deviation to obtain a fitted curve, and then acquiring the K value and correlation coefficient R of the fitted curve. 2 The steps include: Based on the overlay deviation in the X direction and the deviation of the feature pattern in the X direction, point-to-point modeling is performed to obtain the first fitting curve; Based on the overlay deviation in the Y direction and the deviation of the feature pattern in the Y direction, point-to-point modeling is performed to obtain the second fitting curve; Obtain the K value and correlation coefficient R of the first fitted curve respectively. 2 The K value and correlation coefficient R of the second fitted curve 2 .

6. The method for verifying the effectiveness of using AEI OVL to compensate for overlay accuracy according to claim 5, characterized in that, The correlation coefficient R 2 The steps for determining whether using AEI OVL to compensate for overlay accuracy, and the aforementioned K value, include: If the correlation coefficient R of the first fitted curve 2 The K value is greater than 0.7 and the K value is greater than or equal to 0.85, and the K value and correlation coefficient R of the second fitted curve are... 2 If the value of K is greater than 0.7 and the value of K is greater than or equal to 0.85, then the method of using AEI OVL to compensate for overlay accuracy is determined to be effective; otherwise, the method of using AEI OVL to compensate for overlay accuracy is determined to be invalid.

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