CN115616873A

CN115616873A - Method, device and equipment for monitoring exposure focal length and offset and exposure method

Info

Publication number: CN115616873A
Application number: CN202211350109.9A
Authority: CN
Inventors: 张宇
Original assignee: Changxin Memory Technologies Inc
Current assignee: Changxin Memory Technologies Inc
Priority date: 2022-10-31
Filing date: 2022-10-31
Publication date: 2023-01-17

Abstract

The embodiment of the application provides a method, a device and equipment for monitoring an exposure focal length and an offset and an exposure method, wherein the method comprises the following steps: acquiring a first difference value between the top size and the bottom size of a target pattern, wherein the target pattern is a pattern formed on a wafer after photoresist is exposed at a first exposure focal length with an offset to be determined; determining the difference between the top size and the bottom size of a reference pattern and the linear relation between the exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to a target pattern; determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of a pattern formed on the wafer by the mask pattern; an offset between the first exposure focus distance and the second exposure focus distance is determined based on the first difference value, the reference difference value, and the linear relationship.

Description

Method, device and equipment for monitoring exposure focal length and offset and exposure method

Technical Field

The present application relates to the field of semiconductor technology, and relates to, but is not limited to, a method, an apparatus, and a device for monitoring an exposure focal length and an offset, and an exposure method.

Background

In the semiconductor industry, a lithography machine exposes a wafer, and the focal length is a very important parameter. If the focus is greatly deviated and is not detected in time, the product can generate defocusing (De-focus), and further the Yield is reduced (Yield Loss). In the related art, determining whether the focal length of the lithography machine is stable generally includes the following two methods: exposing a bare wafer by using a specific photomask, measuring an overlay error of a pattern formed on the bare wafer, and finally obtaining a focal length value through the overlay error conversion; and secondly, judging whether the optimal exposure focal length of the layer structure deviates or not by making a focal length energy matrix for the layer structure in the wafer.

However, both of the above methods for monitoring the focal length have long periods and are long in time for one time. Therefore, not only the photoresist is consumed and the productivity of the machine is affected, but also the focus of the layer structure in the exposed wafer cannot be monitored in real time.

Disclosure of Invention

In view of this, the present disclosure provides a method, an apparatus, and a device for monitoring an exposure focal length and an offset, and an exposure method.

In a first aspect, an embodiment of the present application provides a method for monitoring an exposure focus offset, where the method includes: acquiring a first difference value between the top size and the bottom size of a target graph; the target pattern is a pattern formed on a wafer after photoresist is exposed at a first exposure focal length with an offset to be determined; determining a difference value between the top size and the bottom size of a reference pattern and a linear relation between exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to the target pattern; determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of a pattern formed on a wafer by the mask pattern; determining an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship.

In some embodiments, determining an offset between the first exposure focus distance and the second exposure focus distance based on the first difference value, the reference difference value, and the linear relationship comprises: determining a third difference value between the first difference value and the reference difference value, and determining a ratio of the third difference value to the slope corresponding to the linear relationship; determining the ratio as an offset between the first exposure focal length and the second exposure focal length.

In some embodiments, further comprising: outputting first prompt information under the condition that the offset meets a first preset range, wherein the first prompt information is used for prompting a user to adjust an exposure focal length to a third exposure focal length, and the third exposure focal length is equal to the sum of the second exposure focal length and the offset; and under the condition that the offset exceeds the first preset range, outputting second prompt information, wherein the second prompt information is used for prompting a user to re-determine the second exposure focal length and setting the exposure focal length as the updated second exposure focal length.

In some embodiments, further comprising: acquiring a difference value between the top dimension and the bottom dimension of each transfer pattern in a transfer pattern set, wherein the transfer patterns are formed on a wafer after photoresist is exposed under the first exposure focal length, and the transfer patterns are the same as mask patterns corresponding to the target patterns; determining an average difference between the top and bottom dimensions of the transfer pattern based on the difference between the top and bottom dimensions of each transfer pattern; and determining the average difference value of the transfer patterns as a first difference value between the top size and the bottom size of the target pattern.

In some embodiments, the determining a linear relationship between a difference between a top dimension and a bottom dimension of a reference pattern and a corresponding exposure focus of the reference pattern comprises: determining a difference value between the top size and the bottom size of the reference pattern and an exposure focal length corresponding to the reference pattern; determining discrete data points on coordinate axes by taking the difference value between the top size and the bottom size of the reference pattern as a vertical coordinate and taking the exposure focal length corresponding to the reference pattern as a horizontal coordinate; and fitting the discrete data points to obtain the linear relation.

In some embodiments, determining the difference between the top dimension and the bottom dimension of the reference pattern comprises: determining the top size and the bottom size of the reference pattern based on the acquired image comprising the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed by adopting different exposure focal lengths under the same second exposure energy; determining the difference between the top and bottom dimensions of the reference pattern.

In some embodiments, further comprising: acquiring a focal length energy matrix of the bottom size of the reference pattern; the focal length energy matrix comprises at least two groups of exposure data, and each group of exposure data comprises exposure energy, an exposure focal length and the bottom size of the reference pattern; acquiring a target size of the reference pattern; determining a second exposure parameter for the reference pattern based on the target size and each set of the exposure data; wherein: the second exposure parameter includes the second exposure energy and the second exposure focal length.

In some embodiments, determining a second exposure parameter for the reference pattern based on the target size and each set of the exposure data comprises: determining a poisson curve for a bottom dimension of the reference pattern based on the target dimension and each set of the exposure data; determining a target point which is closest to a straight line where the target size is located in the Poisson curve; and determining the exposure parameter at the target point as a second exposure parameter of the reference pattern.

In some embodiments, further comprising: outputting third prompt information under the condition that a first difference value between the top size and the bottom size of the target graph meets a second preset range, wherein the third prompt information is used for prompting a user to continue exposure through the first exposure focal length; determining an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference and the linear relationship when the first difference between the top dimension and the bottom dimension of the target pattern exceeds the second preset range.

In a second aspect, an embodiment of the present application provides a method for monitoring an exposure focus, where the method includes: acquiring a first difference value between the top size and the bottom size of a target graph; the target pattern is a pattern formed on a wafer after exposure is carried out on the photoresist under a first exposure focal length of the offset to be determined; determining a difference value between the top size and the bottom size of a reference pattern and a linear relation between exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to the target pattern; determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of a pattern formed on a wafer by the mask pattern; determining an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship; determining the first exposure focal length based on the offset and the second exposure focal length.

In a third aspect, an embodiment of the present application provides an exposure method applied to a lithography machine, where the method includes: exposing the photoresist layer on the substrate by adopting the first exposure focal length with the offset to be determined so as to form the photoresist layer with the target pattern; etching the etching layer in the substrate by taking the target pattern as a mask so as to form the target pattern in the etching layer; monitoring the offset between the first exposure focal length and the second exposure focal length by adopting the method under the condition that the first difference value between the top size and the bottom size of the target graph exceeds a second preset range; adjusting the exposure focal length to a third exposure focal length when the offset meets a first preset range, wherein the third exposure focal length is equal to the sum of the second exposure focal length and the offset; and under the condition that the offset exceeds the first preset range, outputting second prompt information, wherein the second prompt information is used for prompting a user to re-determine the second exposure focal length and setting the exposure focal length as the updated second exposure focal length.

In some embodiments, further comprising: and under the condition that a first difference value between the top size and the bottom size of the target graph meets the second preset range, outputting third prompt information, wherein the third prompt information is used for prompting a user to continue exposure through the first exposure focal length.

In a fourth aspect, an embodiment of the present application further provides an apparatus for monitoring an exposure focus offset, including: the first obtaining module is used for obtaining a first difference value between the top size and the bottom size of the target graph; the target pattern is a pattern formed on a wafer after exposure is carried out on the photoresist under a first exposure focal length of the offset to be determined; the first determining module is used for determining the difference value between the top size and the bottom size of a reference pattern and the linear relation between the exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to the target pattern; the second determining module is used for determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of a pattern formed on a wafer by the mask pattern; a third determining module, configured to determine an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship.

In a fifth aspect, an embodiment of the present application further provides an apparatus for monitoring an exposure focal length, including: the first obtaining module is used for obtaining a first difference value between the top size and the bottom size of the target graph; the target pattern is a pattern formed on a wafer after exposure is carried out on the photoresist under a first exposure focal length of the offset to be determined; the first determining module is used for determining the difference value between the top size and the bottom size of a reference pattern and the linear relation between the exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to the target pattern; the second determining module is used for determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of a pattern formed on a wafer by the mask pattern; a third determining module, configured to determine an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship; an eighth determining module, configured to determine the first exposure focal length based on the offset and the second exposure focal length.

In a sixth aspect, the present application further provides a computer device, including a memory and a processor, where the memory stores a computer program that is executable on the processor, and the processor implements some or all of the steps of the above method when executing the program.

In a seventh aspect, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored, and the computer program, when executed by a processor, implements part or all of the steps of the above method.

In the embodiment of the application, a first difference value between the top size and the bottom size of a target graph is obtained; then determining the difference value between the top size and the bottom size of the reference pattern and the linear relation between the corresponding exposure focal lengths of the reference pattern; then determining a second exposure focal length and a reference difference value under the second exposure focal length; and finally, determining the offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference and the linear relation.

The linear relation is determined by one reference pattern and the exposure focal distance corresponding to the reference pattern under different exposure focal distances. In the actual production process, a plurality of patterns are formed on the wafer under one exposure focal length, and considering that different patterns may have certain deviation due to process reasons, the exposure focal length has certain deviation determined by using a linear relation obtained by one reference pattern, but the slope in the linear relation is relatively accurate, namely the ratio of the variation of the exposure focal length to the variation of the difference between the top dimension and the bottom dimension is a constant value. Therefore, the slope in the obtained linear relationship is skillfully used in the embodiment of the application, then a known second exposure focal length and a reference difference under the second exposure focal length are determined, and finally, the offset between the first exposure focal length and the second exposure focal length is obtained through the first difference, the reference difference and the linear relationship by taking the ratio of the variation of the exposure focal length to the variation of the difference between the top dimension and the bottom dimension as a fixed value.

Therefore, the process of determining the linear relation is simple and easy to implement, and the accuracy of the finally obtained exposure focal length offset is improved. In addition, because the linear relation, the reference difference value and the second exposure focal length can be predetermined, the scheme provided by the embodiment of the application can monitor the offset of the exposure focal length on line in the production process of a product on the premise of not occupying the capacity of a machine table and not wasting photoresist, and the problems of long monitoring period and long consumed time of the exposure focal length in the related technology are solved. Therefore, once problems are found, the problems can be solved in time, the phenomenon of defocusing of a large number of products is prevented, the cost is reduced, and the production efficiency is improved.

Drawings

Fig. 1A is a schematic flowchart of a method for monitoring exposure focus offset according to an embodiment of the present disclosure;

FIG. 1B is a schematic diagram illustrating an optimal exposure focus according to an embodiment of the present disclosure;

FIG. 1C is a schematic diagram of a wafer with different exposure focal lengths for forming a pattern on the wafer with energy distribution on the photoresist layer according to an embodiment of the present disclosure;

FIG. 1D is a graph illustrating the relationship between the variation of the exposure focus and the variation of the difference between the top dimension and the bottom dimension of the pattern formed on the wafer according to an embodiment of the present disclosure;

FIG. 2A is a schematic flowchart illustrating a method for compensating an exposure focus according to an embodiment of the present disclosure;

FIG. 2B is a diagram showing the relationship between the difference between the top dimension and the bottom dimension of a reference pattern and the exposure focus according to an embodiment of the present application;

FIG. 3 is a Poisson's plot of the bottom dimension of a reference pattern provided in an embodiment of the present application;

fig. 4 is a schematic flowchart illustrating a method for monitoring an exposure focus according to an embodiment of the present disclosure;

fig. 5 is a schematic flowchart of an exposure method according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of a device for monitoring an exposure focus according to an embodiment of the present disclosure;

fig. 7 is a hardware entity diagram of a computer device according to an embodiment of the present application.

Detailed Description

Exemplary embodiments disclosed in the present application will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art, that the present application may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the present application; that is, not all features of an actual embodiment are described herein, and well-known functions and structures are not described in detail.

In the drawings, the size of layers, regions, elements, and relative sizes may be exaggerated for clarity. Like reference numerals refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on … …," "adjacent … …," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on … …," "directly adjacent … …," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application. And the discussion of a second element, component, region, layer or section does not imply that a first element, component, region, layer or section is necessarily present in the application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

The embodiment of the application provides a method for monitoring exposure focus offset, which can be executed by a processor of computer equipment. The computer device refers to a device with data processing capability, such as a server, a notebook computer, a tablet computer, a desktop computer, an intelligent television, a set-top box, a photoetching machine and the like.

In some embodiments, the server may be an independent physical server, or may be a server cluster or a distributed system formed by a plurality of physical servers, or may be a cloud server that provides basic cloud computing services such as a cloud service, a cloud database, cloud computing, a cloud function, cloud storage, a Network service, cloud communication, a middleware service, a domain name service, a security service, a Content Delivery Network (CDN), a big data and artificial intelligence platform, and the like.

Fig. 1A is a schematic flow chart illustrating an implementation of a method for monitoring an exposure focus offset according to an embodiment of the present application, as shown in fig. 1A, the method includes the following steps S101 to S104:

step S101: acquiring a first difference value between the top size and the bottom size of a target graph; the target pattern is a pattern formed on the wafer after the photoresist is exposed under the first exposure focal length of the offset to be determined;

here, the target pattern may be a pattern formed on a wafer by exposure on a product being produced on the production line, or may be a pattern formed on a wafer by exposure on an already produced product.

In some embodiments, the method for forming the target pattern may include the following steps S201 and S202:

step S201: exposing the photoresist layer on the substrate by adopting a first exposure focal length with the offset to be determined so as to form the photoresist layer with a target pattern;

here, the photoresist layer is a layer formed by coating photoresist, which is classified into positive photoresist and negative photoresist according to polarity, with the difference that: the exposed areas of the negative photoresist become hard and remain after exposure and development, and the unexposed parts are dissolved by a developer; after the positive photoresist is exposed, the connected polymers in the exposed area can be broken and softened due to the photo-dissolution effect and are finally dissolved by a developer, and the unexposed part is remained.

In some embodiments, the photoresist layer is exposed and developed to dissolve a portion of the photoresist layer to form a photoresist layer having a target pattern.

Step S202: and etching the etching layer in the substrate by taking the target pattern as a mask so as to form the target pattern in the etching layer.

Here, the etching may include dry etching and wet etching, so as to obtain a target pattern on the wafer, and the etching process is not limited in this embodiment of the application.

In some embodiments, the implementation of "obtaining a first difference between the top dimension and the bottom dimension of the target pattern" in step S101 may include steps S1011 and S1012 as follows:

step S1011: determining a top size and a bottom size of the target figure based on the acquired image including the target figure;

here, the image including the target graphic may be: a Two-dimensional (2D) image or a Three-dimensional (3D) image, wherein the 2D image may include: red Green Blue (RGB) images collected by monocular or monocular cameras, and the like. In some implementations, the image including the target pattern can be an image captured in real time by an image capture module disposed on a computer device (e.g., a lithography machine), such as a camera module; in other implementations, the image including the target pattern may be an image that is transmitted by other devices to the computer device in an instant messaging manner and requires exposure focus offset monitoring; in some implementations, the image including the target graphic may also be a captured image that is obtained by the computer device by calling the local album through the server in response to the task processing instruction, which is not limited in this embodiment of the application.

In some embodiments, the computer device may further include a measurement module to measure a top dimension and a bottom dimension of the target feature based on the acquired image including the target feature.

Step S1012: a first difference between a top dimension and a bottom dimension of the target feature is determined.

Here, the implementation of step S1012 may obtain the first difference by subtracting the bottom size of the target pattern from the top size of the target pattern.

Step S102: determining the difference value between the top size and the bottom size of a reference pattern and the linear relation between the exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to a target pattern;

here, the reference pattern is the same as the mask pattern corresponding to the target pattern, that is, the reference pattern and the target pattern are patterns formed on the wafer using the same mask pattern. The reference pattern can be a pattern formed on a wafer after exposure by adopting a mask pattern which is the same as the mask pattern corresponding to the target pattern in the previous production process; or the mask patterns which are specially used for determining the linear relation and have different exposure focal lengths and the same mask pattern corresponding to the target pattern are adopted, and the photoresist is exposed to form patterns on the wafer, namely a batch of prefabricated reference patterns.

In some embodiments, in determining the linear relationship, while the reference pattern is formed by exposure using different exposure focal lengths, other exposure parameters, such as exposure energy, may be fixed to determine a single variable exposure focal length in relation to the difference between the top and bottom dimensions of the reference pattern.

In some embodiments, the implementation of step S102 may include: firstly, adopting mask patterns with different exposure focal lengths and the same mask pattern corresponding to a target pattern to expose photoresist and then form a reference pattern on a wafer; wherein, the number of the reference patterns under one exposure focal length can be one, and then the difference value between the top size and the bottom size of the reference patterns is determined; and finally, determining the difference between the top size and the bottom size of the reference pattern and the linear relation between the corresponding exposure focal lengths of the reference pattern through relational fitting.

Since the lithography machine is in the process of exposure (taking positive photoresist as an example), there is an optimal exposure focal length below the lens as shown in fig. 1B. At this time, the top energy and the bottom energy of the photoresist layer have the smallest deviation. Correspondingly, the difference between the top size and the bottom size of the pattern formed on the wafer at the optimal exposure focal distance is also the smallest and is a fixed value. When the exposure focal length is in the direction close to the lens and deviates from the optimal exposure focal length, the optimal exposure focal length is located at the position which is lower than the center of the photoresist layer, so that the energy at the top of the photoresist layer is smaller than the energy at the bottom of the photoresist layer, and therefore, the top size of the pattern formed in the photoresist layer is smaller than the bottom size, and the difference between the top size and the bottom size of the pattern formed in the photoresist layer is larger (the difference is negative) as the exposure focal length is in the direction close to the lens and is farther from the optimal exposure focal length; when the exposure focal length deviates from the optimal exposure focal length in the direction away from the lens, the optimal exposure focal length is located at a position above the center of the photoresist layer, resulting in that the energy at the top of the photoresist layer is greater than the energy at the bottom, and therefore, the top size of the pattern formed in the photoresist layer is greater than the bottom size. Also, the farther from the optimum exposure focal length, the larger the difference between the top dimension and the bottom dimension of the pattern formed in the photoresist layer (the difference is positive), as the exposure focal length is in the direction away from the lens.

For further illustration, see FIG. 1C,201 for an energy distribution in a photoresist layer at an optimal exposure focus, wherein the top energy and the bottom energy of the photoresist layer are substantially equal, and the top dimension and the bottom dimension of the formed pattern are substantially equal after transfer to the wafer. The portion indicated by 202 is the energy distribution in the photoresist layer in the case where the exposure focal length deviates from the optimum exposure focal length in the direction close to the lens. Wherein the top energy of the photoresist layer is less than the bottom energy. After transfer to the wafer, the top dimension of the formed pattern is smaller than the bottom dimension. The portion indicated by 203 is the energy distribution in the photoresist layer in the case where the exposure focal length deviates from the optimal exposure focal length in the direction away from the lens, wherein the top energy of the photoresist layer is greater than the bottom energy. After transfer to the wafer, the top dimension of the formed pattern is larger than the bottom dimension.

Since the focal length of exposure close to the lens is positive and the focal length of exposure far from the lens is negative, the difference between the top dimension and the bottom dimension of the pattern formed on the wafer changes from positive to negative as the focal length of exposure changes from negative to positive, as shown in fig. 1D. Therefore, the direction of the exposure focus offset can also be determined by the positive or negative of the difference between the top dimension and the bottom dimension of the pattern formed on the wafer. For example, if the difference between the top size and the bottom size of the pattern formed on the wafer increases, the exposure focus shifts in the negative direction; when the difference between the top dimension and the bottom dimension of the pattern formed on the wafer is reduced, the exposure focus is shifted in the positive direction.

In summary, it can be seen that the difference between the top dimension and the bottom dimension of the pattern formed on the wafer is linear with the exposure focus. I.e. the difference between the top dimension and the bottom dimension of the reference pattern, and the corresponding exposure focus of the reference pattern.

Step S103: determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of the pattern formed on the wafer by the mask pattern;

here, the second exposure focal length refers to an optimum exposure focal length of the mask pattern, i.e., the second exposure focal length is generally an inflection point on the poisson curve.

In some embodiments, the method of determining the second exposure focus distance may include: the bottom sizes of patterns formed on the wafer under different exposure energies (Dose) and different exposure focal lengths (Focus) are determined through the focal length energy matrix, the bottom size closest to a target size (the target size of the mask pattern transferred to the wafer under an ideal condition) is determined in the bottom sizes, and the exposure focal length corresponding to the bottom size is the second exposure focal length.

In some embodiments, determining the reference difference value at the second exposure focus distance may include: setting the exposure focal length to a second exposure focal length; then, exposing and developing the photoresist layer by adopting a mask pattern, and transferring the photoresist layer to a wafer to form a pattern; and determining a second difference value between the top dimension and the bottom dimension of the pattern formed on the wafer, namely the reference difference value under the second exposure focal length.

Step S104: an offset between the first exposure focus distance and the second exposure focus distance is determined based on the first difference value, the reference difference value, and the linear relationship.

Here, the equation of the linear relationship can be assumed to be: y = aX + b, where X is an exposure focal length, Y is a difference between a bottom dimension and a top dimension of a pattern formed on the wafer, a is a slope of a linear relationship, and b is a constant term.

Since the linear relationship obtained in step S102 is determined by one reference pattern and the exposure focal length corresponding to the reference pattern at different exposure focal lengths. In the actual production process, a plurality of patterns are formed on the wafer under one exposure focal length, and considering that different patterns may have certain deviation due to process reasons, therefore, the exposure focal length may have certain deviation by using a linear relation obtained by one reference pattern, but the slope in the linear relation indicates the direction and speed of the difference along with the change of the exposure focal length, which is relatively accurate, that is, the ratio of the change of the exposure focal length to the change of the difference between the top dimension and the bottom dimension should be a fixed value.

The above conclusions are further illustrated mathematically by the linear relationship obtained below:

and respectively substituting the known second exposure focal length, the reference difference value and the first difference value under the second exposure focal length into the linear relation to obtain:

Y1＝aX1+b (1)；

Y2＝aX2+b (2)；

wherein, X1 is the second exposure focal length, Y1 is the reference difference, X2 is the first exposure focal length, and Y2 is the first difference. Equations (1) and (2) are combined, and equation (1) is subtracted from equation (2) to obtain: Y2-Y1= a (X2-X1), i.e.:

X2-X1＝(Y2-Y1)/a (3)；

that is, the ratio of the amount of change in the exposure focal length to the amount of change in the difference between the top dimension and the bottom dimension is a constant value, i.e., the slope a. The offset between the first exposure focus and the second exposure focus is equal to the difference between the first difference and the reference difference, divided by the slope of the linear equation.

Correspondingly, the implementation of the step S104 "determining the offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference and the linear relationship" may include the following steps S1041 to S1043:

step S1041: determining a third difference between the first difference and the reference difference;

here, the third difference is Y2-Y1.

Step S1042: determining the ratio of the third difference value to the slope corresponding to the linear relation;

here, the ratio of the third difference to the slope corresponding to the linear relationship is (Y2-Y1)/a.

Step S1043: the ratio is determined as the offset between the first exposure focus and the second exposure focus.

I.e., X2-X1= (Y2-Y1)/a, and as such, determination of the offset between the first exposure focal length and the second exposure focal length is achieved.

Therefore, the process of determining the linear relation is simple and easy to implement, and the accuracy of the finally obtained exposure focal length offset is improved. In addition, the linear relation, the reference difference value and the second exposure focal length can be predetermined, so that the scheme provided by the embodiment of the application can monitor the offset of the exposure focal length on line in the production process of a product on the premise of not occupying the capacity of a machine and not wasting photoresist, and the problems of long exposure focal length monitoring period and long consumed time in the related technology are solved. Therefore, once problems are found, the problems can be solved in time, defocusing of a large number of products is prevented, cost is reduced, and production efficiency is improved.

In some embodiments, as shown in fig. 2A, after step S104, the method further includes steps S105 and S106 as follows:

step S105: outputting first prompt information under the condition that the offset meets a first preset range, wherein the first prompt information is used for prompting a user to adjust the exposure focal length to a third exposure focal length, and the third exposure focal length is equal to the sum of the second exposure focal length and the offset;

here, the first preset range refers to a maximum range of the offset amount, which is a range of the offset amount that needs to be controlled in a process established when designing a product, and beyond this range, there is a great risk of the size exceeding.

The implementation of step S105 is directed to the case that the offset does not exceed the first preset range, at this time, the exposure focal length may be automatically compensated, and since the second exposure focal length is known, the exposure focal length is adjusted to the sum of the second exposure focal length and the offset according to the obtained offset.

Step S106: and under the condition that the offset exceeds the first preset range, outputting second prompt information, wherein the second prompt information is used for prompting a user to re-determine the second exposure focal length and setting the exposure focal length as the updated second exposure focal length.

Here, the step S106 is performed for the case that the offset amount exceeds the first preset range, and at this time, the offset amount is too much, which indicates that the previously determined optimal exposure focal length (i.e., the second exposure focal length) may have been inaccurate, and therefore, it is necessary to re-determine the optimal exposure focal length and set the exposure focal length to the updated optimal exposure focal length (i.e., the second exposure focal length).

In the embodiment of the application, after obtaining the offset of exposure focus, according to the size of offset, carry out the compensation of pertinence to the exposure focus to realize quick accurate compensation exposure focus, thereby prevent that defocus phenomenon from appearing in a large amount of products, and reduce the defective rate and the reduce cost of product.

In some embodiments, the method further comprises steps S301 to S303 as follows:

step S301: acquiring a difference value between the top size and the bottom size of each transfer pattern in the transfer pattern set, wherein the transfer patterns are patterns formed on a wafer after photoresist is exposed under a first exposure focal length, and the transfer patterns are the same as mask patterns corresponding to target patterns;

in some embodiments, since the amount of change in the exposure focal length per unit time is small, the exposure focal length per unit time may be regarded as one exposure focal length, i.e., the first exposure focal length. In the implementation process, the production line circulation speed is high in the actual production process, so that the exposure focal lengths corresponding to several batches of products can be regarded as the same exposure focal length. The number of batches is not limited in the embodiment of the application. In this case, the transfer pattern may be a pattern formed by using the same mask pattern as that of the target pattern in the several lots.

Step S302: determining an average difference between the top and bottom dimensions of the transferred patterns based on the difference between the top and bottom dimensions of each transferred pattern;

here, the implementation of step S302 is to determine an average value of the difference between the top dimension and the bottom dimension of the transfer patterns in the transfer pattern set, so as to reduce the difference between the top dimension and the bottom dimension of the transfer patterns formed at the same exposure focus due to process variation, which is too large, thereby causing the accuracy of the finally determined offset amount to be lowered.

Step S303: the average difference of the transferred patterns is determined as a first difference between the top and bottom dimensions of the target pattern.

That is, the first difference between the top size and the bottom size of the target pattern may be a difference between the top size and the bottom size of one pattern; the average value of the difference between the top dimension and the bottom dimension of a plurality of patterns (a plurality of patterns formed using the same mask pattern as that of the target pattern) may be used.

In the embodiment of the application, firstly, the average difference value between the top size and the bottom size of each transfer pattern in the transfer pattern set is determined; the average difference is then taken as the first difference between the top and bottom dimensions of the target feature. The average difference value of the transfer pattern set is combined with the size difference values of the plurality of transfer patterns, so that the instability of the process is considered, the obtained average difference value can reflect the real condition of the exposure focal length more accurately, and the accuracy of the finally determined exposure focal length offset can be improved.

In some embodiments, the implementation of step S102 "determining the difference between the top dimension and the bottom dimension of the reference pattern, and the linear relationship between the exposure focal distance corresponding to the reference pattern" may include steps S1021 to S1023 as follows:

step S1021: determining the difference value between the top size and the bottom size of the reference pattern and the exposure focal length corresponding to the reference pattern;

in some embodiments, the implementation of "determining the difference between the top dimension and the bottom dimension of the reference pattern" in step S1021 may include steps S12a and S12b as follows:

step S12a: determining the top size and the bottom size of a reference pattern based on the acquired image comprising the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed by adopting different exposure focal lengths under the same second exposure energy;

here, step S12a is performed in step S1011.

Wherein the second exposure energy may be an optimal exposure energy, i.e. a linear relationship between the reference pattern and the different exposure focal lengths is determined at the optimal exposure energy. The second exposure energy may be determined by referring to the second exposure focal length determination method, and similarly, the focal length energy matrix is adopted, and the exposure energy corresponding to the bottom size closest to the target size is the second exposure energy.

The forming of the reference pattern may first determine a second exposure energy; then setting exposure parameters, wherein the exposure parameters comprise second exposure energy and different exposure focal lengths; and finally, respectively carrying out exposure and development on the photoresist layer by adopting second exposure energy and different exposure focal lengths to form a mask pattern, and transferring the mask pattern onto the wafer to form a reference pattern.

Step S12b: the difference between the top and bottom dimensions of the reference pattern is determined.

Here, the step S12b may be performed by subtracting the bottom size of the reference pattern from the top size of the reference pattern to obtain a difference between the top size and the bottom size of the reference pattern.

Step S1022: determining discrete data points on the coordinate axes by taking the difference value between the top size and the bottom size of the reference pattern as a vertical coordinate and taking the exposure focal length corresponding to the reference pattern as a horizontal coordinate;

step S1023: and fitting the discrete data points to obtain a linear relation.

Fig. 2B shows the linear relationship obtained by fitting discrete data points. Wherein, the equation of the linear relation is: y = -129.05x +10.365, correlation coefficient R ² Is 0.9845. It can be seen that the correlation of the obtained linear relationship is high, which means that the reliability of the linear relationship between the difference between the top dimension and the bottom dimension of the reference pattern and the corresponding exposure focal length of the reference pattern is high.

In some embodiments, the implementation of the method for determining the second exposure energy and the second exposure focal length may include the following steps S401 to S403:

step S401: acquiring a focal length energy matrix of the bottom size of the reference pattern; the focal length energy matrix comprises at least two groups of exposure data, and each group of exposure data comprises exposure energy, an exposure focal length and the bottom size of a reference pattern;

here, the focus energy matrix is a test method used to check the lithography process window and determine the optimal exposure conditions. By using different focal lengths and energies of exposure in different areas on a silicon wafer, patterns under different combinations of process conditions can be produced. By the method, the optimal exposure focal length (namely the second exposure focal length) and the optimal exposure energy (namely the second exposure energy) can be determined by testing on a silicon wafer. Wherein, a group of exposure data comprises an exposure energy, an exposure focal length and a bottom size of a reference pattern, and the three data jointly form a group of exposure data. The focal length energy matrix has a test result of the bottom size of how many reference patterns there are how many sets of exposure data.

In some embodiments, since the reference pattern is already formed in the process of performing step S401, while the focal length energy matrix of the bottom size of the reference pattern is acquired, the focal length energy matrix of the top size of the reference pattern may also be acquired for determining the difference between the top size and the bottom size of the reference pattern.

In some embodiments, after acquiring the second exposure energy, the difference between the top dimension and the bottom dimension of the reference pattern may be determined by a focal length energy matrix of the bottom dimension of the reference pattern and a focal length energy matrix of the top dimension of the reference pattern.

Step S402: acquiring a target size of a reference graph;

here, the target size is a target size for transferring a mask pattern to a wafer in an ideal case, and is a size requirement in designing a product.

Step S403: determining a second exposure parameter of the reference pattern based on the target size and each set of exposure data; wherein: the second exposure parameters include a second exposure energy and a second exposure focal length.

Here, the implementation of step S403 may include: and determining the bottom size closest to the target size in the bottom sizes in each group of exposure data, wherein the exposure focal length and the exposure energy corresponding to the bottom size are second exposure parameters.

In some embodiments, the implementation of determining the second exposure parameter of the reference pattern in step S403 may further include steps S4031 to S4033 as follows:

step S4031: determining a poisson curve of the bottom dimension of the reference pattern based on the target dimension and each set of exposure data;

here, the poisson curve is a variation in the bottom dimension of the reference pattern with exposure energy and exposure focal length. Each exposure energy corresponds to one poisson curve, and a plurality of exposure energies correspond to a plurality of poisson curves.

FIG. 3 shows a Poisson plot of the bottom dimension of a reference pattern, where the left ordinate represents the bottom dimension of the reference pattern in nanometers (nm) and the right ordinate represents the exposure energy in millijoules per square centimeter (mJ/cm) ² ) And the abscissa represents the exposure focal length in micrometers (μm). Each curve 103 corresponds to the bottom size of the reference pattern with different exposure focal lengths under one exposure energy (A, B, C, D, E, F, G, H, I, respectively).

Step S4032: determining a target point closest to a straight line where the target size is located in the Poisson curve;

as shown in FIG. 3, the target size is 153nm, the straight line on which the target size is located is a straight line indicated by 102, and the target point closest to the straight line on which the target size is located is a point 101.

Step S4033: and determining the exposure parameter at the target point as a second exposure parameter of the reference pattern.

Here, the exposure parameters at the target point are: exposure energy 35.5mJ/cm ² The exposure focus is-0.1 μm, so the second exposure parameters are: second exposure energy 35.5mJ/cm ² And the second exposure focal length is-0.1 mu m.

In the embodiment of the application, the second exposure energy and the second exposure focal length are obtained by drawing the poisson curve of the bottom size of the reference graph.

In some embodiments, the method further comprises the following steps S501 and S502:

step S501: outputting third prompt information under the condition that a first difference value between the top size and the bottom size of the target graph meets a second preset range, wherein the third prompt information is used for prompting a user to continue exposure through the first exposure focal length;

here, the second preset range is a maximum allowable range of the first difference value. In some embodiments, the product is considered to be rejected if the first difference is outside of the range.

The implementation of step S501 is to prompt the user to continue exposing the next layer structure through the first exposure focal length when the first difference satisfies the second preset range, that is, the exposure focal length does not need to be adjusted.

Step S502: and determining the offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference and the linear relation under the condition that the first difference between the top size and the bottom size of the target graph exceeds a second preset range.

Here, step S502 is implemented such that, if the first difference exceeds the second preset range, the above steps S102 to S104 are performed to determine the offset between the first exposure focal length and the second exposure focal length. That is, in the case where the first difference does not exceed the second preset range, the determination of the focus offset amount is not performed. Therefore, unnecessary calculation can be reduced, and energy consumption can be saved.

The embodiment of the present application further provides a method for monitoring an exposure focal length, as shown in fig. 4, the method includes the following steps S601 to S605:

step S601: acquiring a first difference value between the top size and the bottom size of a target graph; the target pattern is a pattern formed on the wafer after the photoresist is exposed under the first exposure focal length of the offset to be determined;

step S602: determining the difference between the top size and the bottom size of a reference pattern and the linear relation between the exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to a target pattern;

step S603: determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of the pattern formed on the wafer by the mask pattern;

step S604: determining an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship;

here, steps S601 to S604 may refer to steps S101 to S104.

Step S605: based on the offset and the second exposure focal length, a first exposure focal length is determined.

Here, since the offset is an offset between the first exposure focal length and the second exposure focal length, the first exposure matrix may be obtained by adding the offset to the second exposure focal length, thereby providing a method of determining the first exposure focal length.

The embodiment of the present application further provides an exposure method applied to a lithography machine, as shown in fig. 5, the method includes the following steps S701 to S705:

step S701: exposing the photoresist layer on the substrate by adopting a first exposure focal length with the offset to be determined so as to form the photoresist layer with a target pattern;

step S702: etching the etching layer in the substrate by taking the target pattern as a mask so as to form a target pattern in the etching layer;

step S703: monitoring the offset between the first exposure focal length and the second exposure focal length by adopting the method under the condition that the first difference value between the top size and the bottom size of the target graph exceeds a second preset range;

step S704: under the condition that the offset meets a first preset range, the exposure focal length is adjusted to be a third exposure focal length, wherein the third exposure focal length is equal to the sum of the second exposure focal length and the offset;

step S705: and under the condition that the offset exceeds the first preset range, outputting second prompt information, wherein the second prompt information is used for prompting a user to re-determine the second exposure focal length and setting the exposure focal length as the updated second exposure focal length.

In some embodiments, the method further comprises: and under the condition that the first difference between the top size and the bottom size of the target graph meets a second preset range, outputting third prompt information, wherein the third prompt information is used for prompting the user to continue exposure through the first exposure focal length.

Based on the foregoing embodiments, the present application provides an apparatus for monitoring exposure focus offset, where the apparatus includes units and modules included in the units, and the apparatus can be implemented by a processor in a computer device; of course, the implementation can also be realized through a specific logic circuit; in the implementation process, the Processor may be a Central Processing Unit (CPU), a Microprocessor Unit (MPU), a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), or the like.

Fig. 6 is a schematic structural diagram of a component of a device for monitoring exposure focus offset according to an embodiment of the present application, and as shown in fig. 6, the device 600 for monitoring exposure focus offset includes: a first obtaining module 610, a first determining module 620, a second determining module 630, and a third determining module 640, wherein:

a first obtaining module 610, configured to obtain a first difference between a top size and a bottom size of a target pattern; the target pattern is a pattern formed on the wafer after the photoresist is exposed under the first exposure focal length of the offset to be determined;

a first determining module 620, configured to determine a linear relationship between a difference between a top size and a bottom size of a reference pattern and an exposure focal length corresponding to the reference pattern, where the reference pattern is a pattern formed on a wafer after exposure is performed on a photoresist at different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to a target pattern;

a second determining module 630, configured to determine a second exposure focal length and a reference difference value at the second exposure focal length, where the reference difference value is a second difference value between a top dimension and a bottom dimension of a pattern formed on the wafer by the mask pattern;

a third determining module 640, configured to determine an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship.

In some embodiments, the third determining module 640 includes: a first determination sub-module for determining a third difference between the first difference and the reference difference; the second determining submodule is used for determining the ratio of the third difference value to the slope corresponding to the linear relation; and the third determining submodule is used for determining the ratio as the offset between the first exposure focal length and the second exposure focal length.

In some embodiments, the apparatus further comprises: the first output module is used for outputting first prompt information under the condition that the offset meets a first preset range, wherein the first prompt information is used for prompting a user to adjust the exposure focal length to a third exposure focal length, and the third exposure focal length is equal to the sum of the second exposure focal length and the offset; and the second output module is used for outputting second prompt information under the condition that the offset exceeds the first preset range, wherein the second prompt information is used for prompting a user to re-determine the second exposure focal length and setting the exposure focal length as the updated second exposure focal length.

In some embodiments, the apparatus further comprises: the second acquisition module is used for acquiring the difference value between the top dimension and the bottom dimension of each transfer pattern in the transfer pattern set, wherein the transfer patterns are patterns formed on the wafer after the photoresist is exposed under the first exposure focal length, and the transfer patterns are the same as the mask patterns corresponding to the target patterns; a fourth determining module for determining an average difference between the top and bottom dimensions of the transferred patterns based on the difference between the top and bottom dimensions of each transferred pattern; and the fifth determining module is used for determining the average difference value of the transfer patterns as a first difference value between the top size and the bottom size of the target pattern.

In some embodiments, the first determining module 620 includes: the fourth determining submodule is used for determining the difference value between the top size and the bottom size of the reference pattern and the exposure focal length corresponding to the reference pattern; the fifth determining submodule is used for determining discrete data points on the coordinate axis by taking the difference value between the top size and the bottom size of the reference pattern as a vertical coordinate and taking the exposure focal length corresponding to the reference pattern as a horizontal coordinate; and the fitting module is used for fitting the discrete data points to obtain a linear relation.

In some embodiments, a fourth determination submodule, comprising: the first determining unit is used for determining the top size and the bottom size of a reference pattern based on the acquired image comprising the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed by adopting different exposure focal lengths under the same second exposure energy; a second determining unit for determining a difference between a top size and a bottom size of the reference pattern.

In some embodiments, the apparatus further comprises: the third acquisition module is used for acquiring a focal length energy matrix of the bottom size of the reference graph; the focal length energy matrix comprises at least two groups of exposure data, wherein each group of exposure data comprises exposure energy, an exposure focal length and the bottom size of a reference graph; the fourth acquisition module is used for acquiring the target size of the reference graph; a sixth determining module for determining a second exposure parameter of the reference pattern based on the target size and each set of exposure data; wherein: the second exposure parameters include a second exposure energy and a second exposure focal length.

In some embodiments, the sixth determining module comprises: a sixth determining submodule for determining a poisson curve of the bottom size of the reference pattern based on the target size and each set of exposure data; the seventh determining submodule is used for determining a target point which is closest to a straight line where the target size is located in the Poisson curve; and the eighth determining submodule is used for determining the exposure parameter at the target point as the second exposure parameter of the reference pattern.

In some embodiments, the apparatus further comprises: the third output module is used for outputting third prompt information under the condition that a first difference value between the top size and the bottom size of the target graph meets a second preset range, wherein the third prompt information is used for prompting a user to continue exposure through the first exposure focal length; and the seventh determining module is used for determining the offset between the first exposure focal length and the second exposure focal length on the basis of the first difference, the reference difference and the linear relation under the condition that the first difference between the top size and the bottom size of the target graph exceeds a second preset range.

The embodiment of the present application further provides a device for monitoring an exposure focal length, where the device includes a first obtaining module, a first determining module, a second determining module, a third determining module, and an eighth determining module, where:

the first obtaining module is used for obtaining a first difference value between the top size and the bottom size of the target graph; the target pattern is a pattern formed on the wafer after the photoresist is exposed under the first exposure focal length of the offset to be determined;

the first determining module is used for determining the difference value between the top size and the bottom size of a reference pattern and the linear relation between the exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to a target pattern;

the second determining module is used for determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of the pattern formed on the wafer by the mask pattern;

a third determining module, configured to determine an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship;

and the eighth determining module is used for determining the first exposure focal length based on the offset and the second exposure focal length.

The above description of the apparatus embodiments, similar to the above description of the method embodiments, has similar beneficial effects as the method embodiments. In some embodiments, functions of or modules included in the apparatuses provided in the embodiments of the present disclosure may be used to perform the methods described in the above method embodiments, and for technical details not disclosed in the embodiments of the apparatuses of the present disclosure, please refer to the description of the embodiments of the method of the present disclosure for understanding.

It should be noted that, in the embodiment of the present application, if the monitoring method of the exposure focal length offset and the monitoring method of the exposure focal length are implemented in the form of software functional modules, and are sold or used as independent products, they may also be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the embodiments of the present application may be essentially implemented or a part contributing to the related art may be embodied in the form of a software product stored in a storage medium, and including several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read Only Memory (ROM), a magnetic disk, or an optical disk. Thus, embodiments of the present application are not limited to any specific hardware, software, or firmware or any combination of hardware, software, and firmware.

The embodiment of the present application provides a computer device, which includes a memory and a processor, where the memory stores a computer program that can be executed on the processor, and the processor implements some or all of the steps in the above method when executing the program.

The embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored, and the computer program, when executed by a processor, implements some or all of the steps of the above method. The computer readable storage medium may be transitory or non-transitory.

Here, it should be noted that: the foregoing description of the various embodiments is intended to highlight various differences between the embodiments, which are the same or similar and all of which are referenced. The above description of the apparatus, storage medium embodiments is similar to the description of the method embodiments above, with similar beneficial effects as the method embodiments. For technical details not disclosed in the embodiments of the apparatus and storage medium of the present application, reference is made to the description of the embodiments of the method of the present application for understanding.

It should be noted that fig. 7 is a schematic hardware entity diagram of a computer device in an embodiment of the present application, and as shown in fig. 7, the hardware entity of the computer device 700 includes: a processor 701, a communication interface 702, and a memory 703, wherein:

the processor 701 generally controls the overall operation of the computer device 700.

The communication interface 702 may enable the computer device to communicate with other terminals or servers via a network.

The Memory 703 is configured to store instructions and applications executable by the processor 701, and may also buffer data (e.g., image data, audio data, voice communication data, and video communication data) to be processed or already processed by the processor 701 and modules in the computer device 700, and may be implemented by a FLASH Memory (FLASH) or a Random Access Memory (RAM). Data may be transferred between the processor 701, the communication interface 702, and the memory 703 via the bus 704.

It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be understood that, in the various embodiments of the present application, the sequence numbers of the above steps/processes do not mean the execution sequence, and the execution sequence of the steps/processes should be determined by their functions and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above-described device embodiments are merely illustrative, for example, the division of the unit is only a logical functional division, and there may be other division ways in actual implementation, such as: multiple units or components may be combined, or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the coupling, direct coupling or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between the devices or units may be electrical, mechanical or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units; can be located in one place or distributed on a plurality of network units; some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment. In addition, all functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be separately regarded as one unit, or two or more units may be integrated into one unit; the integrated unit may be implemented in the form of hardware, or in the form of hardware plus a software functional unit.

Those of ordinary skill in the art will understand that: all or part of the steps for realizing the method embodiments can be completed by hardware related to program instructions, the program can be stored in a computer readable storage medium, and the program executes the steps comprising the method embodiments when executed; and the aforementioned storage medium includes: various media that can store program codes, such as a removable Memory device, a Read Only Memory (ROM), a magnetic disk, or an optical disk.

Alternatively, the integrated units described above in the present application may be stored in a computer-readable storage medium if they are implemented in the form of software functional modules and sold or used as independent products. Based on such understanding, the technical solutions of the present application may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media that can store program code, such as removable storage devices, ROMs, magnetic or optical disks, etc.

The above description is only for the embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application.

Claims

1. A method for monitoring exposure focus offset is characterized by comprising the following steps:

acquiring a first difference value between the top size and the bottom size of a target graph; the target pattern is a pattern formed on a wafer after exposure is carried out on the photoresist under a first exposure focal length of the offset to be determined;

determining a difference value between the top size and the bottom size of a reference pattern and a linear relation between exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to the target pattern;

determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of a pattern formed on a wafer by the mask pattern;

determining an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship.

2. The monitoring method of claim 1, wherein determining an offset between the first exposure focus distance and the second exposure focus distance based on the first difference value, the reference difference value, and the linear relationship comprises:

determining a third difference between the first difference and the reference difference;

determining the ratio of the third difference value to the slope corresponding to the linear relation;

determining the ratio as an offset between the first exposure focal length and the second exposure focal length.

3. The monitoring method of claim 1, further comprising:

outputting first prompt information under the condition that the offset meets a first preset range, wherein the first prompt information is used for prompting a user to adjust an exposure focal length to a third exposure focal length, and the third exposure focal length is equal to the sum of the second exposure focal length and the offset;

and under the condition that the offset exceeds the first preset range, outputting second prompt information, wherein the second prompt information is used for prompting a user to re-determine the second exposure focal length and setting the exposure focal length as the updated second exposure focal length.

4. The monitoring method according to any one of claims 1 to 3, further comprising:

acquiring a difference value between the top dimension and the bottom dimension of each transfer pattern in a transfer pattern set, wherein the transfer patterns are formed on a wafer after photoresist is exposed under the first exposure focal length, and the transfer patterns are the same as mask patterns corresponding to the target patterns;

determining an average difference between the top and bottom dimensions of the transferred patterns based on the difference between the top and bottom dimensions of each transferred pattern;

and determining the average difference value of the transfer patterns as a first difference value between the top size and the bottom size of the target pattern.

5. The method of claim 4, wherein determining a linear relationship between a difference between a top dimension and a bottom dimension of a reference pattern and a corresponding exposure focus of the reference pattern comprises:

determining a difference value between the top size and the bottom size of the reference pattern and an exposure focal length corresponding to the reference pattern;

determining discrete data points on coordinate axes by taking the difference value between the top size and the bottom size of the reference pattern as a vertical coordinate and taking the exposure focal length corresponding to the reference pattern as a horizontal coordinate;

and fitting the discrete data points to obtain the linear relation.

6. The method of claim 5, wherein determining a difference between a top dimension and a bottom dimension of the reference pattern comprises:

determining the top size and the bottom size of the reference pattern based on the acquired image comprising the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed by adopting different exposure focal lengths under the same second exposure energy;

determining the difference between the top dimension and the bottom dimension of the reference pattern.

7. The monitoring method of claim 6, further comprising:

acquiring a focal length energy matrix of the bottom size of the reference pattern; the focal length energy matrix comprises at least two groups of exposure data, and each group of exposure data comprises exposure energy, an exposure focal length and the bottom size of the reference pattern;

acquiring a target size of the reference pattern;

determining a second exposure parameter for the reference pattern based on the target size and each set of the exposure data;

wherein: the second exposure parameter includes the second exposure energy and the second exposure focal length.

8. The method of claim 7, wherein determining a second exposure parameter for the reference pattern based on the target size and each set of the exposure data comprises:

determining a poisson curve for a bottom dimension of the reference pattern based on the target dimension and each set of the exposure data;

determining a target point which is closest to a straight line where the target size is located in the Poisson curve;

and determining the exposure parameter at the target point as a second exposure parameter of the reference pattern.

9. The monitoring method according to any one of claims 1 to 3, further comprising:

outputting third prompt information under the condition that a first difference value between the top size and the bottom size of the target graph meets a second preset range, wherein the third prompt information is used for prompting a user to continue exposure through the first exposure focal length;

determining an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference and the linear relationship when the first difference between the top dimension and the bottom dimension of the target pattern exceeds the second preset range.

10. A method for monitoring exposure focus, comprising:

determining an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship;

determining the first exposure focal length based on the offset and the second exposure focal length.

11. An exposure method, applied to a lithography machine, the method comprising:

exposing the photoresist layer on the substrate by adopting the first exposure focal length with the offset to be determined so as to form the photoresist layer with the target pattern;

etching the etching layer in the substrate by taking the target graph pattern as a mask so as to form the target graph in the etching layer;

monitoring an offset between the first exposure focal length and the second exposure focal length using the method of any one of claims 1 to 9 in a case where a first difference between a top dimension and a bottom dimension of the target pattern is outside a second preset range;

adjusting the exposure focal length to a third exposure focal length when the offset meets a first preset range, wherein the third exposure focal length is equal to the sum of the second exposure focal length and the offset;

12. The method of claim 11, further comprising:

and under the condition that a first difference value between the top size and the bottom size of the target graph meets the second preset range, outputting third prompt information, wherein the third prompt information is used for prompting a user to continue exposure through the first exposure focal length.

13. An apparatus for monitoring exposure focus offset, comprising:

the first obtaining module is used for obtaining a first difference value between the top size and the bottom size of the target graph; the target pattern is a pattern formed on a wafer after exposure is carried out on the photoresist under a first exposure focal length of the offset to be determined;

the first determining module is used for determining the difference value between the top size and the bottom size of a reference pattern and the linear relation between the exposure focal lengths corresponding to the reference pattern, wherein the reference pattern is a pattern formed on a wafer after photoresist is exposed under different exposure focal lengths, and the reference pattern is the same as a mask pattern corresponding to the target pattern;

the second determining module is used for determining a second exposure focal length and a reference difference value under the second exposure focal length, wherein the reference difference value is a second difference value between the top size and the bottom size of a pattern formed on a wafer by the mask pattern;

a third determining module, configured to determine an offset between the first exposure focal length and the second exposure focal length based on the first difference, the reference difference, and the linear relationship.

14. An exposure focus monitoring apparatus, comprising:

an eighth determining module, configured to determine the first exposure focal length based on the offset and the second exposure focal length.

15. A computer device comprising a memory and a processor, the memory storing a computer program operable on the processor, wherein the processor implements the steps of the method of any one of claims 1 to 9 when executing the program.

16. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 9.