Method for obtaining key size of photoetching pattern

Abstract

The invention provides a method for acquiring the critical dimension of a photoetching pattern. The method comprises the steps that a wafer is provided, a patterned photoresist layer is formed on the surface of the wafer, the patterned photoresist layer comprises a photoresist pattern and a gap pattern which are complementary, and the key sizes of mask plate patterns corresponding to the photoresist pattern and the gap pattern are equal; scanning the photoresist pattern and the gap pattern for multiple times by using an electron beam of a scanning electron microscope measuring machine to obtain a plurality of image frames of the photoresist pattern and a plurality of image frames of the gap pattern; overlapping a plurality of image frames of the photoresist pattern to obtain a first picture, and overlapping a plurality of image frames of the gap pattern to obtain a second picture; measuring the key size of the photoresist pattern based on the first picture to obtain a first key size, and measuring the key size of the gap pattern based on the second picture to obtain a second key size; and calculating a mean value of the first critical dimension and the second critical dimension as a pattern critical dimension measurement value. The pattern critical dimension measurement value obtained in this way is high in precision.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a method for obtaining a critical dimension of a photolithography pattern. Background Art

[0002] In the semiconductor manufacturing process, the critical dimension scanning electron microscope (CDSEM) measuring machine is used to measure parameters such as the characteristic dimension (Critical Dimension, CD) of the pattern in the nanoscale of the semiconductor structure. Usually, after each photolithography and etching process, the wafer needs to enter the CDSEM measuring machine. The CDSEM measuring machine uses an electron beam to scan the pattern on the wafer to measure the critical dimension of the pattern. The measured critical dimension of the pattern is handed over to the process end to observe the process window, check the process stability, and modify the process parameters. Therefore, it is required that the measured critical dimension of the pattern can stably and accurately reflect the critical dimension of the actual graphic.

[0003] Since the high-energy electron beam scanning bombardment will cause the photoresist in the photolithography pattern to shrink, and the CDSEM measurement machine needs to scan multiple frames successively and then superimpose the signals to reduce the image signal-to-noise ratio when measuring the post-photolithography wafer in daily life, it is difficult to avoid the situation that the photoresist shrinks in the next frame after a single-frame electron beam scan, and the accuracy of the key dimensions of the measured photolithography pattern is not high. In order to improve the accuracy of the key dimensions of the obtained photolithography pattern, the post-development inspection often uses a smaller number of overlapping frames and energy (landing energy), which makes the post-development inspection (After Development Inspection, ADI) more difficult than the post-etching inspection (After Etch Inspection, AEI), and in actual operation, this operation cannot significantly reduce the deviation between the measured value and the actual value of the key dimensions of the photolithography pattern, and the accuracy of the measured key dimensions of the photolithography pattern is not high. Summary of the invention

[0004] One of the purposes of the present invention is to make the key dimension measurement value of the pattern obtained by measuring with a scanning electron microscope close to the actual value before the photoresist shrinks, thereby improving the accuracy of the key dimension measurement value of the lithography pattern obtained, which is conducive to accurately observing the lithography process window, checking the stability of the lithography process, and modifying the lithography process parameters.

[0005] In order to achieve the above object, the present invention provides a method for obtaining the critical size of a photolithography pattern. The method for obtaining the critical size of a photolithography pattern comprises:

[0006] A wafer is provided, wherein a patterned photoresist layer is formed on the surface of the wafer, and a mask is used for exposure during the patterning process of the photoresist layer, wherein the patterned photoresist layer comprises at least one photoresist pattern and at least one gap pattern, wherein the photoresist pattern is formed by retaining a portion of the photoresist during the patterning process of the photoresist layer, and the gap pattern is formed by removing a portion of the photoresist during the patterning process of the photoresist layer, and the critical dimensions of the mask patterns corresponding to the photoresist pattern and the gap pattern are equal;

[0007] Scanning the photoresist pattern and the gap pattern multiple times using an electron beam of a scanning electron microscope measuring machine to obtain multiple image frames of the photoresist pattern and multiple image frames of the gap pattern, wherein the scanning conditions for scanning the photoresist pattern and the gap pattern are the same;

[0008] Overlaying a plurality of image frames of the photoresist pattern to obtain a first image including the photoresist pattern image, and overlaying a plurality of image frames of the gap pattern to obtain a second image including the gap pattern image;

[0009] Measuring a critical dimension of the photoresist pattern based on the first picture to obtain a first critical dimension, and measuring a critical dimension of the gap pattern based on the second picture to obtain a second critical dimension; and

[0010] An average of the first critical dimension and the second critical dimension is calculated as a pattern critical dimension measurement value of the patterned photoresist layer.

[0011] Optionally, the patterned photoresist layer includes a plurality of the photoresist patterns and a plurality of the gap patterns; the first picture includes images of a plurality of the photoresist patterns, and the second picture includes images of a plurality of the gap patterns; when measuring the critical dimension of the photoresist pattern based on the first picture to obtain a first critical dimension, the critical dimensions of the plurality of the photoresist patterns are measured and obtained, and an average value of the critical dimensions of the plurality of the photoresist patterns is used as the first critical dimension; when measuring the critical dimension of the gap pattern based on the second picture to obtain a second critical dimension, the critical dimension of the plurality of the gap patterns is measured and obtained, and an average value of the critical dimensions of the plurality of the gap patterns is used as the second critical dimension.

[0012] Optionally, the photoresist pattern and the gap pattern are both in strip shape; the photoresist pattern and the gap pattern are extended in parallel; a plurality of the photoresist patterns are arranged in a row and extended in parallel, and a plurality of the gap patterns are arranged in a row and extended in parallel.

[0013] Optionally, at least two of the photoresist patterns and at least one of the gap patterns are arranged in the same row, and two adjacent photoresist patterns define one gap pattern.

[0014] Optionally, both the photoresist pattern and the gap pattern are circular.

[0015] Optionally, the wafer has a test area, and the photoresist pattern and the gap pattern are formed in the same test area.

[0016] Optionally, the first image and the second image are obtained by superimposing the same number of image frames using the same superposition method; and the same measurement algorithm is used to measure the critical dimension of the photoresist pattern based on the first image and the critical dimension of the gap pattern based on the second image.

[0017] Optionally, after the photoresist pattern and the gap pattern are scanned multiple times by an electron beam of a scanning electron microscope measuring machine, a shrinkage amount of a critical dimension of the photoresist pattern is equal to an expansion amount of a critical dimension of the gap pattern.

[0018] Optionally, the method for obtaining the critical dimension of a photolithography pattern further includes: calculating a difference between the first critical dimension and a measured value of a pattern critical dimension of the patterned photoresist layer, and using the difference as a correction value to correct critical dimension measurements of other photoresist patterns to be measured.

[0019] Optionally, multiple pattern groups are set, one pattern group includes the photoresist pattern and the gap pattern with equal critical dimensions, and the photoresist patterns in different pattern groups have different critical dimensions; multiple correction values ​​corresponding to the multiple pattern groups are obtained to form a database, and when performing critical dimension detection on other photoresist patterns to be measured, the correction value corresponding to the photoresist pattern to be measured in the database is called to correct the critical dimension measurement value of the photoresist pattern to be measured, wherein the correction value whose first critical dimension corresponding to the correction value in the database is closest to the critical dimension measurement value of the photoresist pattern to be measured is the correction value corresponding to the photoresist pattern to be measured.

[0020] In the method for obtaining the critical dimension of a photolithography pattern provided by the present invention, since the critical dimensions of the mask patterns corresponding to the photoresist pattern and the gap pattern are equal, that is, the design values ​​of the critical dimensions of the photoresist pattern and the gap pattern are the same, after multiple electron beam scannings in sequence, the contraction amount of the critical dimension of the photoresist pattern and the expansion amount of the critical dimension of the gap pattern are the same, and then multiple image frames of the photoresist pattern and multiple image frames of the gap pattern obtained by multiple scannings of the electron beam of the scanning electron microscope measuring machine are superimposed to obtain a first picture including the photoresist pattern image and a second picture including the gap pattern image, and the critical dimension of the photoresist pattern is measured based on the first picture to obtain A first critical dimension is obtained, and a second critical dimension is obtained by measuring the critical dimension of the gap pattern based on the second image. Then, an average of the first critical dimension and the second critical dimension is calculated as a pattern critical dimension measurement value of the patterned photoresist layer. In this way, the shrinkage error of the first critical dimension and the expansion error of the second critical dimension can offset each other, thereby avoiding the problem that the photoresist shrinks due to electron beam bombardment and affects the pattern critical dimension measurement value. The pattern critical dimension measurement value is closer to the real value before the photoresist shrinks, thereby improving the accuracy of the photolithography pattern critical dimension measurement value, and facilitating accurate observation of the photolithography process window, inspection of the photolithography process stability, and modification of the photolithography process parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flow chart of a method for obtaining a critical dimension of a photolithography pattern provided by an embodiment of the present invention.

[0022] Figure 2 A top view of a photoresist pattern provided according to an embodiment of the present invention.

[0023] Figure 3 A cross-sectional view of a photoresist pattern provided in accordance with an embodiment of the present invention.

[0024] Figure 4 A top view of a gap pattern provided in accordance with an embodiment of the present invention.

[0025] Figure 5 A cross-sectional view of a gap pattern provided in accordance with an embodiment of the present invention.

[0026] Figure 6 A schematic diagram of a gap pattern provided by an embodiment of the present invention being located between photoresist patterns.

[0027] Figure 7 A schematic diagram of a photoresist pattern and a gap pattern provided according to another embodiment of the present invention. DETAILED DESCRIPTION

[0028] The method for obtaining the critical dimension of the photolithography pattern proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0029] As used in this application, the term "several" is generally used to include the meaning of "at least one", and the terms "at least two" and "plurality" are generally used to include the meaning of "two or more". In addition, the terms "first", "second", and "third" are used only for descriptive purposes 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", and "third" may explicitly or implicitly include one or at least two of the features, unless the content clearly indicates otherwise.

[0030] Figure 1 Flow chart of a method for obtaining a critical dimension of a photolithography pattern provided by an embodiment of the present invention. Figure 1 As shown, the method for obtaining the critical dimension of the photolithography pattern includes:

[0031] S1, providing a wafer, a patterned photoresist layer is formed on the surface of the wafer, a mask is used for exposure during the patterning process of the photoresist layer, the patterned photoresist layer includes at least one photoresist pattern and at least one gap pattern, the photoresist pattern is formed by retaining a portion of the photoresist during the patterning process of the photoresist layer, the gap pattern is formed by removing a portion of the photoresist during the patterning process of the photoresist layer, and the critical dimensions of the mask patterns corresponding to the photoresist pattern and the gap pattern are equal;

[0032] S2, scanning the photoresist pattern and the gap pattern multiple times using an electron beam of a scanning electron microscope measuring machine to obtain multiple image frames of the photoresist pattern and multiple image frames of the gap pattern, wherein the scanning conditions for scanning the photoresist pattern and the gap pattern are the same;

[0033] S3, superimposing a plurality of image frames of the photoresist pattern to obtain a first image including a photoresist pattern image, and superimposing a plurality of image frames of the gap pattern to obtain a second image including a gap pattern image;

[0034] S4, measuring a critical dimension of the photoresist pattern based on the first image to obtain a first critical dimension, and measuring a critical dimension of the gap pattern based on the second image to obtain a second critical dimension; and

[0035] S5, calculating an average of the first critical dimension and the second critical dimension as a pattern critical dimension measurement value of the patterned photoresist layer.

[0036] Figure 2A top view of a photoresist pattern provided according to an embodiment of the present invention. Figure 3 A cross-sectional view of a photoresist pattern provided in accordance with an embodiment of the present invention. Figure 4 A top view of a gap pattern provided in accordance with an embodiment of the present invention. Figure 5 A cross-sectional view of a gap pattern provided in accordance with an embodiment of the present invention.

[0037] refer to Figures 2 to 5 As shown, the method of providing a wafer with a patterned photoresist layer formed on the surface in step S1 may include: providing a mask, in which a mask pattern corresponding to a photoresist pattern 11 and a gap pattern 12 is formed, and the key dimensions of the mask patterns corresponding to the photoresist pattern 11 and the gap pattern 12 are equal; forming a photoresist layer on a wafer 10; exposing the photoresist layer using the mask; developing the photoresist layer to obtain a patterned photoresist layer, the patterned photoresist layer including at least one photoresist pattern 11 and at least one gap pattern 12, the photoresist pattern 11 is formed by retaining a portion of the photoresist during the patterning of the photoresist layer, and the gap pattern is formed by removing a portion of the photoresist during the patterning of the photoresist layer.

[0038] In the present application, the critical dimensions of the mask patterns corresponding to the photoresist pattern 11 and the gap pattern 12 are equal, which can also be understood as the design critical dimensions of the photoresist pattern 11 and the gap pattern 12 are equal.

[0039] In the present application, the photoresist pattern 11 and the gap pattern 12 have the same shape, which facilitates the subsequent measurement of the critical dimensions of the photoresist pattern 11 and the gap pattern 12 .

[0040] For example, in some embodiments, Figure 2 and Figure 4 As shown, the photoresist pattern 11 and the gap pattern 12 are both strip-shaped, and the key dimensions of the photoresist pattern 11 and the gap pattern 12 are both widths, that is, Figure 2 and Figure 4 The horizontal dimension of the center.

[0041] Figure 7 A schematic diagram of a photoresist pattern and a gap pattern provided by another embodiment of the present invention. Figure 7 As shown, in some embodiments, the photoresist pattern 11 and the gap pattern 12 may be circular, but not limited thereto. The critical dimensions of the photoresist pattern 11 and the gap pattern 12 may refer to the diameter of the circle, and the diameters of the photoresist pattern 11 and the gap pattern 12 are the same.

[0042] The following description will be made by taking the case where both the photoresist pattern 11 and the gap pattern 12 are in strip shape as an example.

[0043] refer to Figure 2 and Figure 4As shown, the photoresist pattern 11 and the gap pattern 12 can be extended in parallel, but not limited thereto. The photoresist pattern 11 and the gap pattern 12 can also be arranged vertically.

[0044] refer to Figure 2 and Figure 4 As shown, the patterned photoresist layer may include a plurality of photoresist patterns 11 and a plurality of gap patterns 12. The plurality of photoresist patterns 11 may be arranged in a row and extend in parallel, and the plurality of gap patterns 12 may be arranged in a row and extend in parallel, so as to facilitate subsequent measurement of the critical dimensions of the plurality of photoresist patterns 11 and the plurality of gap patterns 12. The plurality of photoresist patterns 11 and the plurality of gap patterns 12 may also be arranged in other suitable ways. The spacing between the plurality of photoresist patterns 11 and the spacing between the plurality of gap patterns 12 may be designed according to actual conditions.

[0045] Figure 6 A schematic diagram of a gap pattern provided in an embodiment of the present invention is located between photoresist patterns. Figure 6 As shown, at least two of the photoresist patterns 11 and at least one gap pattern 12 are arranged in the same row, for example, a plurality of photoresist patterns 11 and a plurality of gap patterns 12 are arranged in a row, and two adjacent photoresist patterns 11 define a gap pattern 12, wherein the design critical dimensions of the photoresist pattern 11 and the gap pattern 12 are equal, and when normal exposure deviation is ignored, the width of the photoresist pattern 11 is equal to the spacing between two adjacent photoresist patterns 11, and the spacing between two adjacent photoresist patterns 11 is the width of the gap pattern 12. In this case, after electron beam scanning, the critical dimension shrinkage of the photoresist pattern 11 will be completely equal to the critical dimension expansion of the gap pattern 12, and the critical dimensions of the photoresist pattern 11 and the gap pattern 12 have a good complementary effect, and an image frame including the photoresist pattern 11 and the gap pattern 12 can be obtained subsequently, simplifying the overlay step.

[0046] After the photoresist pattern 11 and the gap pattern 12 are formed on the wafer, step S2 is executed to scan the photoresist pattern 11 and the gap pattern 12 multiple times using the electron beam of a scanning electron microscope measuring machine to obtain multiple image frames of the photoresist pattern 11 and multiple image frames of the gap pattern 12, wherein the scanning conditions for scanning the photoresist pattern 11 and the gap pattern 12 are the same.

[0047] In this embodiment, the scanning electron microscope measuring machine can be a CDSEM measuring machine, but is not limited thereto. The electron beam used for scanning can be a high-energy electron beam. An image frame including the photoresist pattern 11 and / or the gap pattern 12 can be formed by collecting a secondary electron signal image generated after the electron beam scans the pattern.

[0048] After the electron beam scans the photoresist pattern 11 and the gap pattern 12, the photoresist will shrink, the photoresist pattern 11 will shrink, and the gap pattern 12 will expand. Figure 3 As shown, before the electron beam scanning, the real critical dimension of the photoresist pattern 11 is Real.CDA; after the electron beam scanning, the critical dimension of the photoresist pattern 11 is CDA, which is smaller than Real.CDA; Figure 5 As shown, before the electron beam scanning, the real critical dimension of the gap pattern 12 is Real.CDB; after the electron beam scanning, the critical dimension of the gap pattern 12 is CDB, and CDB is larger than Real.CDB.

[0049] It should be noted that, when the design critical dimensions of the photoresist pattern 11 and the gap pattern 12 are the same and the scanning conditions for scanning the photoresist pattern 11 and the gap pattern 12 are the same, after the photoresist pattern and the gap pattern are scanned multiple times using the electron beam of a scanning electron microscope measuring machine, the shrinkage amount of the critical dimension of the photoresist pattern 11 can be equal to the expansion amount of the critical dimension of the gap pattern 12, and the photoresist pattern 11 and the gap pattern 12 are complementary patterns.

[0050] In this embodiment, the wafer 10 has a test area, and the photoresist pattern 11 and the gap pattern 12 can be formed in the test area, so that the electron beam scanning can be prevented from affecting the photoresist in the effective area of ​​the wafer. The photoresist pattern 11 and the gap pattern 12 can be formed in the same test area, so that the image frames of the photoresist pattern 11 and the gap pattern 12 can be acquired at one time using a set scanning program.

[0051] Exemplarily, one scan may scan the photoresist pattern 11 and the gap pattern 12. The process of obtaining multiple image frames of the photoresist pattern 11 and multiple image frames of the gap pattern 12 may include: performing a first scan, scanning the photoresist pattern 11 and the gap pattern 12, obtaining one image frame of the photoresist pattern 11 and one image frame of the gap pattern 12; performing a second scan, scanning the photoresist pattern 11 and the gap pattern 12, obtaining one image frame of the photoresist pattern 11 and one image frame of the gap pattern 12; and then performing a third to nth scan to obtain multiple image frames of the photoresist pattern 11 and multiple image frames of the gap pattern 12.

[0052] The scanning conditions for scanning the photoresist pattern 11 and the gap pattern 12 are the same. Specifically, the scanning conditions for scanning the photoresist pattern 11 and the gap pattern 12 in the same time can be the same. In this way, after one scan, the key dimension shrinkage amount of the photoresist pattern 11 and the key dimension expansion amount of the gap pattern 12 are equal, and the image frame of the photoresist pattern 11 obtained corresponds to the image frame of the gap pattern 12, which is beneficial to improving the accuracy of the subsequent key dimension measurement values ​​of the pattern.

[0053] The same scanning conditions may include, but are not limited to, the same electron beam acceleration voltage, the same electron beam current and / or the same scanning speed.

[0054] In some embodiments, reference Figure 2 and Figure 4 As shown, in the step of scanning the photoresist pattern 11 and the gap pattern 12 multiple times using the electron beam of the scanning electron microscope measuring machine, multiple photoresist patterns 11 and multiple gap patterns 12 can be scanned to obtain image frames including multiple photoresist patterns 11 and image frames including multiple gap patterns 12.

[0055] Step S3 is executed to superimpose multiple image frames of the photoresist pattern 11 to obtain a first image including an image of the photoresist pattern 11 , and to superimpose multiple image frames of the gap pattern 12 to obtain a second image including an image of the gap pattern 12 .

[0056] In this embodiment, the first image and the second image can be obtained by superimposing the same number of image frames using the same superposition method, which can avoid different quantitative deviations in the key dimensions of the photoresist pattern 11 and the gap pattern 12 due to different superposition numbers and superposition methods.

[0057] In some embodiments, when an image frame including a plurality of photoresist patterns 11 and an image frame including a plurality of gap patterns 12 are superimposed, a first image obtained includes images of the plurality of photoresist patterns 11 , and a second image includes images of the plurality of gap patterns 12 .

[0058] Step S4 is executed to measure the critical dimension of the photoresist pattern 11 based on the first image to obtain a first critical dimension, and to measure the critical dimension of the gap pattern 12 based on the second image to obtain a second critical dimension.

[0059] In this embodiment, the same measurement algorithm is used to measure the critical dimension of the photoresist pattern 11 based on the first image and the critical dimension of the gap pattern 12 based on the second image. Exemplarily, when measuring the critical dimension using an image, an edge of the photoresist pattern 11 and the gap pattern 12 corresponds to a signal peak, and the measurement algorithm includes fixing a position of the signal peak as the measurement position, for example, for a sinusoidal signal, confirming the peak position as the measurement position, and obtaining the critical dimensions of the photoresist pattern 11 and the gap pattern 12 by measuring the distance between two adjacent peaks.

[0060] In step S4, the key dimension of a photoresist pattern 11 in the first image can be measured as the first key dimension, and the key dimension of a gap pattern 12 in the second image can be measured as the second key dimension, so that the measurement amount is small and the measurement is simple. When the first image includes multiple images of photoresist patterns 11 and the second image includes multiple images of gap patterns 12, the key dimensions of the multiple photoresist patterns 11 can also be measured and obtained, and the average value of the key dimensions of the multiple photoresist patterns 11 is used as the first key dimension, and the key dimensions of the multiple gap patterns 12 are measured and obtained, and the average value of the key dimensions of the multiple gap patterns 12 is used as the second key dimension, which helps to improve the accuracy of the subsequently obtained pattern key dimension measurement values.

[0061] Step S5 is executed to calculate an average of the first critical dimension and the second critical dimension as a pattern critical dimension measurement value of the patterned photoresist layer.

[0062] It should be noted that there is a shrinkage error of the photoresist pattern 11 between the first key dimension and the real key dimension Real.CDA before the photoresist pattern 11 shrinks, and there is an expansion error of the gap pattern 12 between the second key dimension and the real key dimension Real.CDB before the gap pattern 12 expands. Since the design key dimensions of the photoresist pattern 11 and the gap pattern 12 are equal, the shrinkage amount of the key dimension of the photoresist pattern 11 can be approximately equal to the expansion amount of the key dimension of the gap pattern 12. Therefore, the shrinkage error of the first key dimension and the expansion error of the second key dimension can offset each other, so that the average of the first key dimension and the second key dimension is close to the real key dimension of the pattern before the photoresist shrinks. Using this average as the pattern key dimension measurement value of the patterned photoresist layer accurately reflects the real key dimension. Using this pattern key dimension measurement value, the photolithography process window can be accurately observed, the stability of the photolithography process can be checked, and the photolithography process parameters can be modified.

[0063] In some embodiments, the photoresist pattern 11 and the gap pattern 12 are arranged as follows: Figure 6 As shown, the images of the photoresist pattern 11 and the gap pattern 12 are located in the same picture, and the Pitch values ​​of the photoresist pattern 11 and the gap pattern 12 can be directly measured, that is, the sum of the widths of the adjacent photoresist patterns 11 and gap patterns 12 is measured, and half of the Pitch value is used as the pattern critical dimension measurement value of the patterned photoresist layer. Compared with measuring the critical dimensions of the photoresist pattern 11 and the gap pattern 12 separately, this can simplify the measurement steps.

[0064] The method for obtaining the critical dimension of a photolithographic pattern of the present application is suitable for post-development inspection, and can avoid the problem that electron beam bombardment during post-development inspection causes photoresist shrinkage and affects the measurement value of the critical dimension of the pattern.

[0065] In this embodiment, after step S5, the difference between the first critical dimension and the critical dimension measurement value of the pattern of the patterned photoresist layer may be calculated as a first correction value for correcting the critical dimension measurement values ​​of other photoresist patterns to be measured.

[0066] In step S1, a plurality of pattern groups may be set, wherein one pattern group includes at least one photoresist pattern and at least one gap pattern with equal critical dimensions, the photoresist patterns of different pattern groups have different critical dimensions, and the gap patterns of different pattern groups have different critical dimensions. The plurality of pattern groups may be set by setting a plurality of patterned photoresist layers, or the plurality of pattern groups may be set in one patterned photoresist layer.

[0067] Exemplarily, after step S5, multiple first correction values ​​corresponding to multiple pattern groups are obtained to form a database, and when performing critical dimension detection on other photoresist patterns to be measured, the first correction value corresponding to the photoresist pattern to be measured in the database is called to correct the critical dimension measurement value of the photoresist pattern to be measured, wherein the first correction value whose first critical dimension corresponding to the first correction value in the database is closest to the critical dimension measurement value of the photoresist pattern to be measured is the first correction value corresponding to the photoresist pattern to be measured.

[0068] After step S5, the difference between the second critical dimension and the critical dimension measurement value of the pattern of the patterned photoresist layer may be calculated as a second correction value for correcting the critical dimension measurement values ​​of other gap patterns to be measured.

[0069] Specifically, after step S5, multiple second correction values ​​corresponding to multiple pattern groups are obtained to form a database. When performing critical dimension detection on other gap patterns to be measured, the second correction value corresponding to the gap pattern to be measured in the database is called to correct the critical dimension measurement value of the gap pattern to be measured, wherein the second correction value whose second critical dimension corresponding to the second correction value in the database is closest to the critical dimension measurement value of the gap pattern to be measured is the second correction value corresponding to the gap pattern to be measured.

[0070] In the method for obtaining the critical dimensions of a photolithography pattern provided by the present invention, since the critical dimensions of the mask patterns corresponding to the photoresist pattern 11 and the gap pattern 12 are equal, that is, the critical dimension design values ​​of the photoresist pattern 11 and the gap pattern 12 are the same, after the electron beam is scanned multiple times in sequence, the critical dimension contraction amount of the photoresist pattern 11 and the critical dimension expansion amount of the gap pattern 12 are the same, and then multiple image frames of the photoresist pattern 11 and multiple image frames of the gap pattern 12 obtained by multiple scanning of the electron beam of the scanning electron microscope measuring machine are superimposed to obtain a first picture including the photoresist pattern image and a second picture including the gap pattern image, and the photoresist pattern 11 is measured based on the first picture. The first key dimension of the key dimension of the pattern is obtained, and the second key dimension is obtained by measuring the key dimension of the gap pattern based on the second image. Then, the average of the first key dimension and the second key dimension is calculated as the pattern key dimension measurement value of the patterned photoresist layer. In this way, the shrinkage error of the first key dimension and the expansion error of the second key dimension can offset each other, and the pattern key dimension measurement value is closer to the real value before the photoresist shrinks, avoiding the problem that the photoresist shrinks due to electron beam bombardment and affects the pattern key dimension measurement value, improving the accuracy of the photolithography pattern key dimension measurement value, and facilitating the accurate observation of the photolithography process window, the inspection of the photolithography process stability and the modification of the photolithography process parameters.

[0071] The above description is only a description of the preferred embodiment of the present invention, and is not any limitation on the scope of rights of the present invention. Any technical personnel in this field can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for obtaining a critical dimension of a photolithography pattern, characterized in that: include: A wafer is provided, wherein a patterned photoresist layer is formed on the surface of the wafer, and a mask is used for exposure during the patterning process of the photoresist layer, wherein the patterned photoresist layer comprises at least one photoresist pattern and at least one gap pattern, wherein the photoresist pattern is formed by retaining a portion of the photoresist during the patterning process of the photoresist layer, and the gap pattern is formed by removing a portion of the photoresist during the patterning process of the photoresist layer, and the critical dimensions of the mask patterns corresponding to the photoresist pattern and the gap pattern are equal; Scanning the photoresist pattern and the gap pattern multiple times using an electron beam of a scanning electron microscope measuring machine to obtain multiple image frames of the photoresist pattern and multiple image frames of the gap pattern, wherein the scanning conditions for scanning the photoresist pattern and the gap pattern are the same; Overlaying a plurality of image frames of the photoresist pattern to obtain a first image including the photoresist pattern image, and overlaying a plurality of image frames of the gap pattern to obtain a second image including the gap pattern image; Measuring a critical dimension of the photoresist pattern based on the first picture to obtain a first critical dimension, and measuring a critical dimension of the gap pattern based on the second picture to obtain a second critical dimension; and An average of the first critical dimension and the second critical dimension is calculated as a pattern critical dimension measurement value of the patterned photoresist layer.

2. The method for obtaining a critical dimension of a photolithography pattern according to claim 1, wherein: The patterned photoresist layer comprises a plurality of the photoresist patterns and a plurality of the gap patterns; The first picture includes a plurality of images of the photoresist patterns, and the second picture includes a plurality of images of the gap patterns; When measuring the critical dimension of the photoresist pattern based on the first image to obtain the first critical dimension, measuring and obtaining the critical dimensions of a plurality of the photoresist patterns, and taking the average of the critical dimensions of the plurality of the photoresist patterns as the first critical dimension; When the critical dimension of the gap pattern is measured based on the second image to obtain the second critical dimension, the critical dimensions of multiple gap patterns are measured and obtained, and the average value of the critical dimensions of the multiple gap patterns is taken as the second critical dimension.

3. The method for obtaining a critical dimension of a photolithography pattern according to claim 1, wherein: The photoresist pattern and the gap pattern are both in strip shape, and the photoresist pattern and the gap pattern are extended in parallel; a plurality of the photoresist patterns are arranged in a row and extended in parallel, and a plurality of the gap patterns are arranged in a row and extended in parallel.

4. The method for obtaining a critical dimension of a photolithography pattern according to claim 3, wherein: At least two of the photoresist patterns and at least one of the gap patterns are arranged in the same row, and two adjacent photoresist patterns define one gap pattern.

5. The method for obtaining a critical dimension of a photolithography pattern according to claim 1, wherein: The photoresist pattern and the gap pattern are both circular.

6. The method for obtaining a critical dimension of a photolithography pattern according to claim 1, wherein: The wafer has a test area, and the photoresist pattern and the space pattern are formed in the same test area.

7. The method for obtaining a critical dimension of a photolithography pattern according to claim 1, wherein: The first image and the second image are obtained by superimposing the same number of image frames using the same superposition method; the same measurement algorithm is used to measure the key size of the photoresist pattern based on the first image and the key size of the gap pattern based on the second image.

8. The method for obtaining a critical dimension of a photolithography pattern according to any one of claims 1 to 7, characterized in that: After the photoresist pattern and the gap pattern are scanned multiple times by an electron beam of a scanning electron microscope measuring machine, the critical dimension shrinkage amount of the photoresist pattern and the critical dimension expansion amount of the gap pattern are equal.

9. The method for obtaining a critical dimension of a photolithography pattern according to claim 1, wherein: Also includes: The difference between the first critical dimension and the critical dimension measurement value of the pattern of the patterned photoresist layer is calculated, and the difference is used as a correction value to correct the critical dimension measurement values ​​of other photoresist patterns to be measured.

10. The method for obtaining a critical dimension of a photolithography pattern according to claim 9, wherein: A plurality of pattern groups are provided, wherein one of the pattern groups includes at least one photoresist pattern and at least one gap pattern with equal critical dimensions, and the photoresist patterns in different pattern groups have different critical dimensions; a plurality of correction values ​​corresponding to the plurality of pattern groups are obtained to form a database, and when performing critical dimension detection on other photoresist patterns to be measured, the correction value corresponding to the photoresist pattern to be measured in the database is called to correct the critical dimension measurement value of the photoresist pattern to be measured, wherein the correction value whose first critical dimension corresponding to the correction value in the database is closest to the critical dimension measurement value of the photoresist pattern to be measured is the correction value corresponding to the photoresist pattern to be measured.

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