Method for determining process window of nanolithography

Abstract

The application provides a method for determining a process window of nanolithography technology, which comprises the following steps: imaging according to a single-groove or single-line imaging model of a predetermined first critical dimension to obtain a first light intensity distribution curve corresponding to a plurality of focus values; imaging according to a multi-line imaging model of a predetermined second critical dimension to obtain a second light intensity distribution curve corresponding to the plurality of focus values; obtaining a first Poisson curve and a second Poisson curve respectively according to the first light intensity distribution curve and the second light intensity distribution curve; obtaining a first process window and a second process window respectively according to the first Poisson curve and the second Poisson curve; and determining an intersection part of the first process window and the second process window as a target process window. The method for determining the process window of nanolithography technology can obtain an applicable process window through a light intensity curve with a small amount of calculation, and effectively verifies the process window.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for determining a process window of nanolithography technology. BACKGROUND

[0002] For three key patterns of single line, single trench and parallel dense lines, under the same exposure imaging model condition, the line width of the parallel dense lines is more sensitive to the change of the focus value than the width of the independent lines and the trench. The line width of various patterns also varies with the exposure energy, and the selection of the best exposure energy and focus value must ensure that all patterns can achieve the target line width. There is a certain instability in the actual process, such as the fluctuation of the exposure energy and the focus value range, so it is difficult to obtain an accurate process window, and it is more difficult to verify the usability of the process window. SUMMARY

[0003] The method for determining a process window of nanolithography technology provided by the present application can obtain an applicable process window through a light intensity curve with less calculation amount, and effectively verify the process window.

[0004] The present application provides a method for determining a process window of nanolithography technology, the method comprising:

[0005] imaging according to a single trench or single line imaging model of a predetermined first critical dimension to obtain a first light intensity distribution curve corresponding to a plurality of focus values;

[0006] imaging according to a multi-line imaging model of a predetermined second critical dimension to obtain a second light intensity distribution curve corresponding to a plurality of focus values;

[0007] According to the first light intensity distribution curve and the second light intensity distribution curve, a first Poisson curve and a second Poisson curve are obtained respectively;

[0008] According to the first Poisson curve and the second Poisson curve, a first process window and a second process window are obtained respectively;

[0009] The intersection part of the first process window and the second process window is determined as a target process window.

[0010] Optionally, imaging according to a single trench or single line imaging model of a predetermined first critical dimension to obtain a first light intensity distribution curve corresponding to a plurality of focus values comprises:

[0011] Adjusting the focus value according to a predetermined step;

[0012] Irradiate the imaging model with the nanometer light each time the focus value is adjusted, and obtain a light intensity distribution curve corresponding to the current focus value in a direction perpendicular to the line or groove of the imaging model; when the imaging model is a single-line imaging model, the light intensity distribution curve corresponding to the current focus value has one peak; when the imaging model is a single-groove imaging model, the light intensity distribution curve corresponding to the current focus value has two peaks.

[0013] The light intensity distribution curves under the plurality of focus values are taken as a first light intensity distribution curve.

[0014] Optionally, obtaining a first Poisson curve according to the first light intensity distribution curve comprises:

[0015] Construct straight lines perpendicular to the light intensity coordinate axis along a plurality of target light intensity coordinates;

[0016] Determine the line width value according to the distance between the intersection of each peak in the curve corresponding to each focus value and each straight line;

[0017] Construct a Poisson curve corresponding to a target light intensity according to the line width value and the focus value;

[0018] Take the Poisson curves under a plurality of target light intensities as a first Poisson curve.

[0019] Optionally, obtaining a second light intensity distribution curve corresponding to a plurality of focus values according to a plurality-line imaging model of a predetermined second critical dimension comprises:

[0020] Adjust the focus value in steps according to a predetermined step;

[0021] Irradiate the imaging model with the nanometer light each time the focus value is adjusted, and obtain a light intensity distribution curve corresponding to the current focus value in a direction perpendicular to the line or groove of the imaging model; when the imaging model is a single-line imaging model, the light intensity distribution curve corresponding to the current focus value has one peak; when the imaging model is a single-groove imaging model, the light intensity distribution curve corresponding to the current focus value has two peaks.

[0022] The light intensity distribution curves under the plurality of focus values are taken as a second light intensity distribution curve.

[0023] Optionally, obtaining a second Poisson curve according to the second light intensity distribution curve comprises:

[0024] Construct straight lines perpendicular to the light intensity coordinate axis along a plurality of target light intensity coordinates;

[0025] Determine the line width value according to the distance between the intersection of a plurality of peaks in the curve corresponding to each focus value and each straight line;

[0026] Construct a Poisson curve corresponding to a target light intensity according to the line width value and the focus value;

[0027] Take the Poisson curves under a plurality of target light intensities as a second Poisson curve.

[0028] Optionally, determining the line width value according to the distance between the intersection points of the plurality of peaks in the curve corresponding to each focus value and each straight line comprises:

[0029] determining a plurality of to-be-processed line width values according to the distance between the intersection points of each peak of the curve corresponding to each focus value and each straight line;

[0030] determining an average value according to the plurality of to-be-processed line width values, and determining the average value as the line width value.

[0031] Optionally, obtaining the first process window according to the first Poisson curve comprises:

[0032] determining a first line width range according to the target line width value of the single line or single channel imaging model and the predetermined error range;

[0033] constructing a straight line perpendicular to the coordinate axis direction of the line width value according to the maximum value and the minimum value of the first line width range;

[0034] constructing the first process window according to the target light intensity corresponding to the intersection point of the straight line and the first Poisson curve.

[0035] Optionally, obtaining the second process window according to the second Poisson curve comprises:

[0036] determining a second line width range according to the target line width value of the multi-line imaging model and the predetermined error range;

[0037] constructing a straight line perpendicular to the coordinate axis direction of the line width value according to the maximum value and the minimum value of the second line width range;

[0038] constructing the second process window according to the target light intensity corresponding to the intersection point of the straight line and the second Poisson curve.

[0039] Optionally, determining the intersection part of the first process window and the second process window as the target process window comprises:

[0040] when the minimum value of the first process window is within the range of the second process window, and the maximum value of the second process window is within the range of the first process window;

[0041] determining the part above the minimum value of the first process window and below the maximum value of the second process window as the process window;

[0042] when the minimum value of the second process window is within the range of the first process window, and the maximum value of the first process window is within the range of the second process window;

[0043] determining the part below the maximum value of the first process window and below the minimum value of the second process window as the process window.

[0044] Optionally, determining the intersection part of the first process window and the second process window as the target process window comprises:

[0045] when the maximum value and the minimum value of the first process window are both within the range of the second process window;

[0046] determining the first process window as the target process window;

[0047] when the maximum value and the minimum value of the second process window are both within the range of the first process window;

[0048] determining the second process window as the target process window.

[0049] In the technical scheme provided by the present application, through the collection of light intensity, the process window required in the nanolithography technology can be finally obtained through very little calculation amount. For the collection of light intensity, the collection method is simple and fast, which is beneficial to improve the efficiency of obtaining the process window. The acquisition of the process window is the premise of the judgment of the imaging resolution capability in the photolithography process, therefore, the technical scheme provided by the present application can quickly and accurately verify the photolithography resolution capability. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 the flow chart of the method for determining the nanolithography technology process window of an embodiment of the present application;

[0051] Figure 2 the flow chart of the method for forming the first light intensity distribution curve of another embodiment of the present application;

[0052] Figure 3 the flow chart of the method for forming the first Poisson curve of another embodiment of the present application;

[0053] Figure 4 the flow chart of the method for forming the second light intensity distribution curve of another embodiment of the present application;

[0054] Figure 5 the flow chart of the method for forming the second Poisson curve of another embodiment of the present application;

[0055] Figure 6 the flow chart of the method for obtaining the line width value of another embodiment of the present application;

[0056] Figure 7 the flow chart of the method for forming the first process window of another embodiment of the present application;

[0057] Figure 8 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a flow chart of the second process window;

[0058] Figure 9 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a structure diagram of the Hyperlens imaging model;

[0059] Figure 10 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a diagram of the first light intensity distribution curve;

[0060] Figure 11 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a diagram of the second light intensity distribution curve;

[0061] Figure 12 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a diagram of the second Poisson curve;

[0062] Figure 13 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a diagram of the process window;

[0063] Figure 14 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a structure diagram of the Hyperlens imaging model;

[0064] Figure 15 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a diagram of the first light intensity distribution curve;

[0065] Figure 16 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a diagram of the second light intensity distribution curve;

[0066] Figure 17 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a diagram of the second Poisson curve;

[0067] Figure 18 The method for determining the process window of nano-lithography technology of another embodiment of the present application forms a diagram of the process window. DETAILED DESCRIPTION

[0068] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0069] The embodiments of the present application provide a method for determining a process window of a nano-lithography technology, as shown in the accompanying drawings, Figure 1 The method comprises the following steps:

[0070] In step 100, a first light intensity distribution curve corresponding to a plurality of focus values is obtained according to a single-trench or single-line imaging model of a predetermined first critical dimension.

[0071] In some embodiments, the first critical dimension refers to the size of a trench or a line in the single-trench or single-line imaging model. The first critical dimension is related to a verification target, and in general, the first critical dimension is the same as the line width or the trench width of the verification target. In the coordinate system in which the first light intensity distribution curve is located, one of the coordinate axes is the distance perpendicular to the direction of the line or the groove, and the other coordinate axis is the light intensity. That is, the first light intensity distribution curve refers to the change curve formed by the change of the light intensity along the distance perpendicular to the direction of the line or the groove.

[0072] In step 200, a second light intensity distribution curve corresponding to a plurality of focus values is obtained according to a multi-line imaging model of a predetermined second critical dimension.

[0073] In some embodiments, the second critical dimension refers to the line width dimension in the multi-trench imaging model. The second critical dimension is related to a verification target, and in general, the second critical dimension is the same as the line width or the trench width of the verification target. In the coordinate system in which the second light intensity distribution curve is located, one of the coordinate axes is the distance perpendicular to the direction of the line or the groove, and the other coordinate axis is the light intensity. That is, the second light intensity distribution curve refers to the change curve formed by the change of the light intensity along the distance perpendicular to the direction of the line or the groove.

[0074] In step 300, a first Poisson curve and a second Poisson curve are respectively obtained according to the first light intensity distribution curve and the second light intensity distribution curve.

[0075] In some embodiments, the Poisson curve refers to a curve formed by taking the focus value and the exposure energy as the independent variable and taking the lithography line width as the dependent variable. In the first light intensity curve and the second light intensity curve, the peak value of the curve of one kind of focus value is taken with sufficient exposure energy, and the coordinates corresponding to the exposure energy can be obtained. The difference between the coordinates on both sides of the peak value can obtain the line width.

[0076] Step 400, according to the first Poisson curve and the second Poisson curve, respectively, obtaining the first process window and the second process window;

[0077] In some embodiments, since the Poisson curve is with exposure energy and focus value as independent variables, and with lithography line width as dependent variable. When verifying the resolution capability of lithography, the lithography line width is usually known as the verification target. Therefore, a line width available range can be determined according to the selected lithography line width. Then, according to the corresponding relationship of the exposure energy and the focus value included in the range, the first process window and the second process window are constructed.

[0078] Step 500, determining the intersection part of the first process window and the second process window as the target process window.

[0079] In some embodiments, since in actual lithography, there can be single line lithography, single trench lithography, and multiple line lithography, the first process window and the second process window need to be intersected to meet single line lithography and multiple line lithography, or single trench lithography and multiple line lithography.

[0080] In the technical scheme provided by the embodiment of the present application, through the collection of light intensity, the process window required in nanolithography technology can be finally obtained through very little calculation. The collection of light intensity is simple and fast, which is beneficial to improve the efficiency of obtaining the process window. The acquisition of the process window is the premise of the judgment of the imaging resolution capability in the lithography process, therefore, the technical scheme provided by the embodiment of the present application can quickly and accurately verify the lithography resolution capability.

[0081] As an optional implementation manner, as shown in Figure 2 According to the predetermined single-trench or single-line imaging model of the first critical dimension, the first light intensity distribution curve corresponding to the plurality of focus values is obtained by imaging.

[0082] Step 110, adjusting the focus value according to a predetermined step;

[0083] As an optional implementation manner, in the process of obtaining the light intensity curve of the plurality of focus values, the light intensity curve of each focus value needs to be obtained, therefore, in the present embodiment, the focus value is adjusted according to a predetermined step, so as to obtain the light intensity curve of the plurality of focus values.

[0084] Step 120, irradiate the imaging model with nanometer light after adjusting the focus value each time, and obtain the light intensity distribution curve corresponding to the current focus value along the direction perpendicular to the line or groove of the imaging model; wherein, when the imaging model is a single line imaging model, the light intensity distribution curve corresponding to the current focus value has one peak; when the imaging model is a single groove imaging model, the light intensity distribution curve corresponding to the current focus value has two peaks.

[0085] In some embodiments, when the single line model is used for photolithography, a single line is used for light transmission, and the two sides of the line are light shielding parts. When the single groove is used for photolithography, a single light shielding part is used, and the two sides of the light shielding part are light transmission parts. Therefore, when the single line is used, the light intensity distribution curve forms one peak, and when the single groove is used, the light intensity distribution curve forms two peaks.

[0086] Step 130, the light intensity distribution curves under the plurality of focus values are taken as the first light intensity distribution curve.

[0087] In some embodiments, there is a curve under each focus value, and a plurality of curves are formed under a plurality of focus values. Therefore, in the present embodiment, the first light intensity distribution curve is a cluster of curves, each corresponding to a different focus value.

[0088] As an optional embodiment, as shown in Figure 3 According to the first light intensity distribution curve, the first Poisson curve is obtained, which includes:

[0089] Step 310, constructing a straight line perpendicular to the light intensity coordinate axis along a plurality of target light intensity coordinates;

[0090] In some embodiments, the plurality of target light intensities can be a plurality of target light intensities uniformly distributed, and the light intensity corresponding to each straight line is the same after constructing a plurality of straight lines.

[0091] Step 320, determining the line width value according to the distance between the intersection of the peak in the curve corresponding to each focus value and each straight line;

[0092] In some embodiments, the coordinate value at the intersection of the straight line and the light intensity distribution curve corresponds to the position of the light intensity in the photolithography process. According to the distance between the two focus points on both sides of the peak of the curve, the line width obtained by photolithography at the light intensity can be determined.

[0093] Step 330, constructing the Poisson curve corresponding to the target light intensity according to the line width value and the focus value;

[0094] In some embodiments, under the same target light intensity, the line width obtained by photolithography will change with the change of the focus value. During the change process, the corresponding relationship between the focus value and the line width constitutes the Poisson curve corresponding to the target light intensity.

[0095] Step 340, the Poisson curve under the plurality of target light intensities is taken as a first Poisson curve.

[0096] In some embodiments, after the Poisson curves under the plurality of target light intensities are obtained, the curves under the plurality of target light intensities are constructed in the same coordinate system, so as to determine and verify the subsequent process window.

[0097] As an optional implementation, as shown in Figure 4 According to the second critical dimension imaging model, the second light intensity distribution curve corresponding to the plurality of focus values is obtained, including:

[0098] Step 140, the focus value is adjusted according to the predetermined step;

[0099] As an optional implementation, in the process of obtaining the light intensity curves of the plurality of focus values, the light intensity curves of the plurality of focus values are obtained one by one, therefore, in the embodiment, the focus value is adjusted according to the predetermined step, so as to obtain the light intensity curves of the plurality of focus values.

[0100] Step 150, after adjusting the focus value once, the imaging model is irradiated with nanometer light, and the light intensity distribution curve corresponding to the current focus value is obtained along the direction perpendicular to the line or groove of the imaging model; wherein the light intensity distribution curve corresponding to the current focus value has a plurality of peaks, and each peak corresponds to a line of the mask;

[0101] In some embodiments, in the multi-line model, since the light-transmitting part and the shielding part are periodically arranged, when irradiation imaging is performed, the change of light intensity will also present periodic arrangement and change, so that the light intensity distribution curve has a plurality of peaks.

[0102] Step 160, the light intensity distribution curves under the plurality of focus values are taken as second light intensity distribution curves.

[0103] In some embodiments, there is a curve under each focus value, and the plurality of focus values form a plurality of curves, therefore, in the embodiment, the second light intensity distribution curve is a cluster of curves, respectively corresponding to different focus values.

[0104] As an optional implementation, as shown in Figure 5 According to the second light intensity distribution curve, the second Poisson curve is obtained, including:

[0105] Step 350, a straight line perpendicular to the light intensity coordinate axis is constructed along the plurality of target light intensity coordinates;

[0106] In some embodiments, the plurality of target light intensities can be a plurality of target light intensities uniformly distributed, and after the plurality of straight lines are constructed, the corresponding light intensity on a single straight line is the same.

[0107] Step 360, determining the line width value according to the distance between the intersection of each peak in the curve corresponding to each focus value and each straight line;

[0108] Step 370, constructing the Poisson curve corresponding to the target light intensity according to the line width value and the focus value;

[0109] In some embodiments, the coordinate value of the intersection of the straight line and the light intensity distribution curve corresponds to the position of the light intensity in the photolithography process. According to the distance between the two focus points on both sides of the peak of the curve, the line width obtained by photolithography at this light intensity can be determined.

[0110] Step 380, taking the Poisson curves at multiple target light intensities as the second Poisson curve.

[0111] In some embodiments, at the same target light intensity, the line width obtained by photolithography will change with the change of the focus value. During the change, the corresponding relationship between the focus value and the line width constitutes the Poisson curve corresponding to the target light intensity.

[0112] As an optional implementation, as shown in Figure 6 determining the line width value according to the distance between the intersection of each peak in the curve corresponding to each focus value and each straight line includes:

[0113] Step 361, determining multiple to-be-processed line width values according to the distance between the intersection of each peak on both sides of the curve corresponding to each focus value and each straight line;

[0114] In some embodiments, since the imaging process of the multi-line model has multiple peaks, in order to accurately determine the line width value, multiple line widths corresponding to the peaks can be obtained, and after processing and calculation, a more accurate line width value can be obtained.

[0115] Step 362, determining an average value according to the multiple to-be-processed line width values, and determining the average value as the line width value.

[0116] In some embodiments, averaging the multiple to-be-processed line width values can obtain a more accurate line width value. This is because the average of multiple line widths can effectively offset the size error and measurement error of the multi-line forming model.

[0117] In other embodiments, during the processing of the multiple line widths, the difference between each line width and the average value can also be calculated, and the line width value whose difference is significantly greater or smaller than other line width values is taken out, and then the remaining to-be-processed line width values are averaged to determine the line width value.

[0118] As an optional implementation, as shown in Figure 7 constructing the first process window according to the first Poisson curve includes:

[0119] Step 410, determining a first line width range according to the target line width value of the single line or single channel imaging model and a predetermined error range;

[0120] As an optional implementation, generally, when the target line width value is actually processed, an error is allowed, for example, the error can be ±10%, at this time, a line width range, i.e., the first line width range, can be determined.

[0121] Step 420, constructing a straight line perpendicular to the coordinate axis direction of the line width value according to the maximum value and the minimum value of the first line width range;

[0122] As an optional implementation, the coordinates corresponding to the maximum value and the minimum value of the first line width value are constructed into a straight line, and the line width corresponding to the straight line is consistent.

[0123] Step 430, constructing a first process window according to the target light intensity corresponding to the intersection of the straight line and the first Poisson curve.

[0124] In some embodiments, after the straight line is constructed, the straight line will intersect with the Poisson curve, the target light intensity and the focusing value corresponding to the intersection of the Poisson curve and the straight line are obtained; and then a curve is constructed according to the corresponding relationship between the target light intensity and the focusing value, i.e., the process window determined by the maximum value and the minimum value of the line width is obtained.

[0125] As an optional implementation, as shown in Figure 8 the second process window is obtained according to the second Poisson curve, which includes:

[0126] Step 440, determining a second line width range according to the target line width value of the multi-line imaging model and a predetermined error range;

[0127] As an optional implementation, generally, when the target line width value is actually processed, an error is allowed, for example, the error can be ±10%, at this time, a line width range, i.e., the first line width range, can be determined.

[0128] Step 450, constructing a straight line perpendicular to the coordinate axis direction of the line width value according to the maximum value and the minimum value of the second line width range;

[0129] As an optional implementation, the coordinates corresponding to the maximum value and the minimum value of the first line width value are constructed into a straight line, and the line width corresponding to the straight line is consistent.

[0130] Step 460, constructing a second process window according to the target light intensity corresponding to the intersection of the straight line and the second Poisson curve.

[0131] In some embodiments, after the straight line is constructed, the straight line will intersect with the Poisson curve, the intersection point of the Poisson curve and the straight line is obtained, and a target light intensity and a focusing value corresponding to the intersection point are obtained; then a curve is constructed according to the corresponding relationship between the target light intensity and the focusing value, that is, a process window determined by the maximum value and the minimum value of the line width is obtained.

[0132] As an optional implementation, determining the intersection part of the first process window and the second process window as the target process window comprises:

[0133] When the minimum value of the first process window is within the range of the second process window, and the maximum value of the second process window is within the range of the first process window;

[0134] Determining the part above the minimum value of the first process window and below the maximum value of the second process window as the process window;

[0135] When the minimum value of the second process window is within the range of the first process window, and the maximum value of the first process window is within the range of the second process window;

[0136] Determining the part below the maximum value of the first process window and below the minimum value of the second process window as the process window.

[0137] As an optional implementation, determining the intersection part of the first process window and the second process window as the target process window comprises:

[0138] When the maximum value and the minimum value of the first process window are within the range of the second process window;

[0139] Determining the first process window as the target process window;

[0140] When the maximum value and the minimum value of the second process window are within the range of the first process window;

[0141] Determining the second process window as the target process window.

[0142] A specific implementation is provided as follows to exemplarily illustrate the technical solutions of the present application:

[0143] As shown in Figure 9 , a structural schematic diagram of a superlens multi-line imaging model is provided, and the imaging model of a single line is similar to the imaging model shown in Figure 9 , the difference is that the single-line imaging model is composed of two chrome strips and a light-transmitting part.

[0144] When the first light intensity distribution curve and the second light intensity distribution curve are formed, the thickness of the air layer is in the range of 10nm to 40nm, and the step is 1nm, wherein the thickness of the air layer is the focusing value.

[0145] The first light intensity distribution curve is shown in FIG. 3, where the vertical line L1 corresponds to the light intensity distribution curve when the focus value is 10 nm to 40 nm from top to bottom. Figure 10 The second light intensity distribution curve is shown in FIG. 4, where the vertical line L1 corresponds to the light intensity distribution curve when the focus value is 10 nm to 40 nm from top to bottom. Figure 11 The second light intensity distribution curve is shown in FIG. 4, where the vertical line L1 corresponds to the light intensity distribution curve when the focus value is 10 nm to 40 nm from top to bottom.

[0146] In the process of constructing the Poisson curve according to the second light intensity distribution curve, the horizontal line L2 in FIG. 5 is taken as an example, which corresponds to a light intensity coordinate. On both sides of each peak, the line L2 intersects with the curve, and the distance between the two intersection points of L2 and the curve corresponding to the same peak can be used to determine the corresponding line width. For multiple peaks, the line width can be obtained more accurately by averaging. Finally, the Poisson curve shown in FIG. 6 is formed. The horizontal coordinate of the Poisson curve is the focus value, and the vertical coordinate is the line width. Figure 11 In the process of constructing the Poisson curve according to the second light intensity distribution curve, the horizontal line L2 in FIG. 5 is taken as an example, which corresponds to a light intensity coordinate. On both sides of each peak, the line L2 intersects with the curve, and the distance between the two intersection points of L2 and the curve corresponding to the same peak can be used to determine the corresponding line width. For multiple peaks, the line width can be obtained more accurately by averaging. Finally, the Poisson curve shown in FIG. 6 is formed. The horizontal coordinate of the Poisson curve is the focus value, and the vertical coordinate is the line width. Figure 12 In the process of constructing the Poisson curve according to the second light intensity distribution curve, the horizontal line L2 in FIG. 5 is taken as an example, which corresponds to a light intensity coordinate. On both sides of each peak, the line L2 intersects with the curve, and the distance between the two intersection points of L2 and the curve corresponding to the same peak can be used to determine the corresponding line width. For multiple peaks, the line width can be obtained more accurately by averaging. Finally, the Poisson curve shown in FIG. 6 is formed. The horizontal coordinate of the Poisson curve is the focus value, and the vertical coordinate is the line width. Figure 11 In the process of constructing the Poisson curve according to the second light intensity distribution curve, the horizontal line L2 in FIG. 5 is taken as an example, which corresponds to a light intensity coordinate. On both sides of each peak, the line L2 intersects with the curve, and the distance between the two intersection points of L2 and the curve corresponding to the same peak can be used to determine the corresponding line width. For multiple peaks, the line width can be obtained more accurately by averaging. Finally, the Poisson curve shown in FIG. 6 is formed. The horizontal coordinate of the Poisson curve is the focus value, and the vertical coordinate is the line width. Figure 12 In the Poisson curve in FIG. 7, the curves arranged from top to bottom are the Poisson curves corresponding to the light intensity in the range of 4.1e-4 J / m2 to 4.8e-4 J / m2, with a step of 0.05e-4 J / m2. 4 4 3 4 3

[0147] Taking the single-line and dense-line mask patterns with a line width of 45 nm as verification examples, the lithography process window of the two mask patterns in the imaging plane, i.e., the center CD of the photoresist ± 10%, is given, as shown in FIG. 8. In the process of obtaining the process window, the line width range is 45 nm ± 10%, and the corresponding relationship between the focus value and the light intensity is obtained on the first Poisson curve and the second Poisson curve. In FIG. 9, the four curves arranged from top to bottom are the maximum value of the second process window, the maximum value of the first process window, the minimum value of the first process window, and the minimum value of the second process window. Figure 13 Figure 12 As shown in FIG. 10, a structure diagram of a Hyperlens multi-line imaging model is provided. The imaging model of a single trench is similar to the imaging model shown in FIG. 11, and the difference is that the single trench imaging model is composed of a chromium strip and the transparent parts on both sides.

[0148] As shown in FIG. 10, a structure diagram of a Hyperlens multi-line imaging model is provided. The imaging model of a single trench is similar to the imaging model shown in FIG. 11, and the difference is that the single trench imaging model is composed of a chromium strip and the transparent parts on both sides. Figure 14 Figure 14 As shown in FIG. 10, a structure diagram of a Hyperlens multi-line imaging model is provided. The imaging model of a single trench is similar to the imaging model shown in FIG. 11, and the difference is that the single trench imaging model is composed of a chromium strip and the transparent parts on both sides.

[0149] ​​​​​​​When forming the first and second light intensity distribution curves, the thickness of the air layer is in the range of 10 nm to 40 nm, with a step of 1 nm. The thickness of the air layer is the focusing value.

[0150] The first light intensity distribution curve formed is as follows Figure 15 As shown, at the vertical line L1, each line corresponds from top to bottom to the light intensity distribution curves when the focusing values ​​are 10nm to 40nm. The resulting second light intensity distribution curve is as follows. Figure 16 As shown, at the vertical line L1, each line corresponds to the light intensity distribution curve when the focusing value is 10nm to 40nm, respectively, from top to bottom.

[0151] When constructing the Poisson curve based on the second light intensity distribution curve, Figure 16 Taking the horizontal line L2 as an example, the entire L2 line corresponds to a light intensity coordinate. On both sides of each peak, L2 intersects the curve. Based on the distance between the two intersection points of L2 and the curve for the same peak, the corresponding linewidth can be determined. For multiple peaks, a more accurate linewidth can be obtained by averaging. The final result is as follows: Figure 12 The Poisson curve is shown below. The horizontal axis of the Poisson curve represents the focal length in nm, and the vertical axis represents the line width in nm.

[0152] Similarly, it can also be done in Figure 15 Taking the horizontal line L2 as an example, the corresponding Poisson curve is obtained, which will not be elaborated here. 5. Figure 17 In the Poisson curves, the curves arranged from top to bottom correspond to light intensities ranging from 0.7 e... 4 ~1.2e 4 J / m 3

[0153] Within the range, at 0.025e 4 J / m 3 These are multiple Poisson curves obtained through stepping.

[0154] Using single-line and dense-line mask patterns with a linewidth of 45nm as verification examples, the photolithography process window for the two mask patterns within the imaging plane, i.e., the area of ​​the photoresist center CD ± 10%, is shown in the figure.

[0155] As shown in Figure 18. When obtaining the process window, a linewidth range of 75nm ± 10% was used, and the corresponding relationship between the focus value and the light intensity was obtained on the first Poisson curve and the second Poisson curve, respectively. Figure 18 The four curves in the middle are from top to bottom.

[0156] The following values ​​represent the maximum value of the second process window, the maximum value of the first process window, the minimum value of the first process window, and the minimum value of the second process window, respectively.

[0157] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited to

[0158] Any person skilled in the art can easily think of the changes or replacements of the above within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for determining the process window of nanolithography, characterized in that, The method includes: Imaging is performed based on a single groove or single line imaging model with a predetermined first key dimension to obtain the first light intensity distribution curves corresponding to multiple focus values; Imaging is performed based on a multi-line imaging model with a predetermined second key dimension to obtain second light intensity distribution curves corresponding to multiple focus values; Based on the first light intensity distribution curve and the second light intensity distribution curve, the first Poisson curve and the second Poisson curve are obtained respectively. The first process window and the second process window are obtained based on the first Poisson curve and the second Poisson curve, respectively. The intersection of the first process window and the second process window is determined as the target process window; The first process window is obtained based on the first Poisson curve, including: The first linewidth range is determined based on the target linewidth value and the predetermined error range of the single-line or single-channel imaging model; Based on the maximum and minimum values ​​of the first line width range, construct a straight line perpendicular to the line width value coordinate axis. Based on the target light intensity corresponding to the intersection point of the straight line and the first Poisson curve, a first process window is constructed; The second process window is obtained based on the second Poisson curve, including: Based on the target linewidth value of the multi-line imaging model and the predetermined error range, the second linewidth range is determined; Based on the maximum and minimum values ​​of the second line width range, construct a straight line perpendicular to the line width coordinate axis. A second process window is constructed based on the target light intensity corresponding to the intersection of the straight line and the second Poisson curve.

2. The method according to claim 1, characterized in that, Imaging is performed based on a single-groove or single-line imaging model with a predetermined first key dimension, and the first light intensity distribution curves corresponding to multiple focus values ​​are obtained, including: Adjust the focus value according to the predetermined steps; Each time the focus value is adjusted, the imaging model is illuminated with nano-light, and the light intensity distribution curve corresponding to the current focus value is obtained along the direction perpendicular to the lines or grooves of the imaging model; wherein, when the imaging model is a single-line imaging model, the light intensity distribution curve corresponding to the current focus value has one peak; when the imaging model is a single-groove imaging model, the light intensity distribution curve corresponding to the current focus value has two peaks. The light intensity distribution curves under multiple focus values ​​are used as the first light intensity distribution curve.

3. The method according to claim 2, characterized in that, Based on the first light intensity distribution curve, the first Poisson curve is obtained as follows: Construct straight lines perpendicular to the light intensity coordinate axes along multiple target light intensity coordinates; The line width value is determined based on the distance between the peak of the curve corresponding to each focus value and the intersection point of each straight line; Based on the linewidth and focus values, construct the Poisson curve for the corresponding target light intensity; The Poisson curves under multiple target light intensities are used as the first Poisson curve.

4. The method according to claim 1, characterized in that, Imaging is performed based on a multi-line imaging model with a predetermined second key dimension, and the second light intensity distribution curves corresponding to multiple focus values ​​are obtained, including: Adjust the focus value according to the predetermined steps; Each time the focus value is adjusted, the imaging model is illuminated with nano-light, and the light intensity distribution curve corresponding to the current focus value is obtained along the direction perpendicular to the lines or grooves of the imaging model; wherein, the light intensity distribution curve corresponding to the current focus value has multiple peaks, and each peak corresponds to a line of the mask. The light intensity distribution curves under multiple focus values ​​are used as the second light intensity distribution curve.

5. The method according to claim 4, characterized in that, Based on the second light intensity distribution curve, the second Poisson curve is obtained by: Construct straight lines perpendicular to the light intensity coordinate axes along multiple target light intensity coordinates; The line width value is determined based on the distance between the intersection points of each straight line and the two sides of the multiple peaks in the curve corresponding to each focus value; Based on the linewidth and focus values, construct the Poisson curve for the corresponding target light intensity; The Poisson curves under multiple target light intensities are used as the second Poisson curve.

6. The method according to claim 5, characterized in that, The linewidth value is determined based on the distance between the intersection points of multiple peaks in the curve corresponding to each focus value and each straight line, including: Based on the distance between the intersection points of each peak of the curve corresponding to each focus value and each straight line, multiple line width values ​​to be processed are determined; Based on the multiple line width values ​​to be processed, an average value is determined, and the average value is determined as the line width value.

7. The method according to claim 1, characterized in that, Determining the intersection of the first process window and the second process window as the target process window includes: When the minimum value of the first process window is within the range of the second process window, and the maximum value of the second process window is within the range of the first process window; The portion above the minimum value of the first process window and below the maximum value of the second process window is defined as the process window; When the minimum value of the second process window is within the range of the first process window, and the maximum value of the first process window is within the range of the second process window; The portion below the maximum value of the first process window and below the minimum value of the second process window is defined as the process window.

8. The method according to claim 1, characterized in that, Determining the intersection of the first process window and the second process window as the target process window includes: When both the maximum and minimum values ​​of the first process window are within the range of the second process window; The first process window is designated as the target process window; When both the maximum and minimum values ​​of the second process window are within the range of the first process window; The second process window is designated as the target process window.

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