Light source determination method and device, medium and product

Abstract

The invention discloses a light source determination method and device, a medium and a product, and is applied to the technical field of photoetching. According to the method, a plurality of target areas are generated on a light source plane, and a light source of each target area is utilized to perform imaging simulation on a target mask pattern under a preset process condition to obtain a target imaging performance index of each local part. Then, on the basis of the local data, generating an overall imaging performance index; and determining a final target light source through the overall imaging performance index. According to the scheme, the final target light source is determined by obtaining the imaging performance index of the light source plane, so that the light source can be adjusted according to actual requirements in combination with the imaging performance index. The light source is determined by simulating the imaging performance index, and the light source conforming to the actual demand can be accurately obtained according to more and more accurate information, so that the production efficiency is improved. In addition, whether conflicts exist in mask pattern design or not can be judged through simulation, and unnecessary debugging iteration is avoided.

Description

Technical Field

[0001] The present application belongs to the field of photolithography technology, and in particular, relates to a light source determination method, device, medium and product. Background Art

[0002] Photolithography is the process of transferring the pattern on the mask to the wafer through a photolithography machine. Before actually performing photolithography, the initial light source needs to be determined first; the initial light source has a certain influence on the light source optimization process, and setting different initial light sources may result in different optimization routes. Obtaining a better initial light source may increase the convergence efficiency of the optimization; in some cases, there is no need for optimization, and the light source obtained only through theoretical calculations can have good imaging capabilities.

[0003] In the traditional scheme for determining the initial light source, data such as the wavelength of the light source, the numerical aperture of the lithography machine lens, and the repetition period of the mask pattern are input into an empirical formula, and then the energy center of the light source is constructed, and the required light source is determined based on this energy center. However, the traditional method mainly relies on experience, but the actual process conditions change at any time, so the light source obtained by the traditional method may deviate from the actual light source required, which in turn increases the complexity of subsequent corrections to the light source. Summary of the invention

[0004] The embodiments of the present application provide a light source determination method, device, medium and product, which can accurately determine the required light source and improve production efficiency.

[0005] On the one hand, an embodiment of the present application provides a method for determining a light source, including:

[0006] Acquire multiple target points on the light source plane;

[0007] Based on each of the target points, a corresponding target area is generated on the light source plane;

[0008] Using the light sources of each of the target areas, imaging simulation is performed on the target mask pattern under preset process conditions to obtain corresponding target imaging performance indicators;

[0009] Based on the target imaging performance index and the corresponding position of the target area on the light source plane, an overall imaging performance index of the entire light source plane is generated to determine the target light source.

[0010] On the other hand, the step of acquiring a plurality of target points on the light source plane includes:

[0011] Dividing the light source plane into a plurality of cells;

[0012] Downsampling is performed in each of the cells to select a plurality of target cells;

[0013] The center point of each target cell is determined as the target point.

[0014] On the other hand, downsampling is performed in each of the cells to select multiple target cells, including:

[0015] Sampling each of the cells at equal intervals to obtain a plurality of cells to be determined;

[0016] Based on the undetermined cell, the target cell is determined.

[0017] On the other hand, the sampling of each of the cells at equal intervals to obtain a plurality of pending cells includes:

[0018] Based on the constraints, determine the sampling interval;

[0019] Based on the sampling interval, each of the cells is sampled at equal intervals to obtain a plurality of cells to be determined.

[0020] On the other hand, determining the target cell based on the undetermined cell includes:

[0021] Acquiring a symmetric structure of the light source plane;

[0022] Based on the symmetric structure, each of the cells to be determined is divided into a plurality of cell groups; each of the cells to be determined in the same cell group has the same imaging performance index;

[0023] One of the pending cells is selected from each of the cell groups and determined as the target cell.

[0024] On the other hand, the light sources of each target area are used to perform imaging simulation on the target mask pattern under preset process conditions to obtain corresponding target imaging performance indicators, including:

[0025] Obtaining the preset process conditions;

[0026] The preset process conditions, the target area and the target mask pattern are input into an imaging simulation tool to obtain the target imaging performance index.

[0027] On the other hand, after generating the overall imaging performance index of the entire light source plane based on the target imaging performance index and the corresponding position of the target area on the light source plane, the method further includes:

[0028] Based on the value of the overall imaging performance index, drawing an imaging performance index image on the light source plane;

[0029] The imaging performance index image is displayed.

[0030] In yet another aspect, an embodiment of the present application provides a light source determination device, comprising: a processor and a memory storing computer program instructions;

[0031] When the processor executes the computer program instructions, the light source determination method as described above is implemented.

[0032] On the other hand, an embodiment of the present application provides a computer-readable storage medium, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the light source determination method described above is implemented.

[0033] On the other hand, an embodiment of the present application provides a computer program product. When instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the light source determination method as described above.

[0034] A method for determining a light source provided in an embodiment of the present application generates corresponding target areas based on multiple target points on a light source plane, and uses the light sources of each target area to perform imaging simulation on the target mask pattern under preset process conditions to obtain corresponding target imaging performance indicators. Then, the overall imaging performance index of the entire light source plane is generated based on the above-obtained data; the final target light source is determined by the overall imaging performance index. This scheme determines the final target light source by obtaining the imaging performance index of the light source plane, so the light source can be adjusted according to actual needs in combination with the imaging performance index. Compared with the traditional method of simply relying on empirical formulas to roughly derive the light source, the present application determines the light source by simulating the imaging performance index, and can accurately obtain a light source that meets actual needs based on more and more accurate information, thereby improving production efficiency. In addition, simulation can also determine whether there is a conflict in the mask graphic design, avoiding unnecessary debugging iterations. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] Figure 1 A schematic diagram of a flow chart of a light source determination method provided by an embodiment of the present application is shown;

[0037] Figure 2 A light source energy distribution diagram provided in an embodiment of the present application is shown;

[0038] Figure 3A schematic diagram of a cell division method of a light source plane provided in an embodiment of the present application is shown;

[0039] Figure 4 A schematic diagram showing the symmetry of the light source plane arrangement provided by one embodiment of the present application is shown;

[0040] Figure 5 This is one of the imaging performance indicator images shown in one embodiment of the present application;

[0041] Figure 6 A normalized slope logarithmic distribution diagram of vertical lines with a period of 100 nm provided in an embodiment of the present application;

[0042] Figure 7 A normalized slope logarithmic distribution diagram of a vertical line with a period of 140 nm provided in an embodiment of the present application;

[0043] Figure 8 A normalized slope logarithmic distribution diagram of a vertical line with a period of 220 nm provided in an embodiment of the present application;

[0044] Fig. 9 A normalized slope logarithmic distribution diagram of a vertical line with a period of 300nm provided in an embodiment of the present application;

[0045] Fig.10 A schematic diagram of the structure of a light source determination device provided in an embodiment of the present application is shown;

[0046] Fig.11 A schematic diagram of the hardware structure of a light source determination device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0047] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating the examples of the present application.

[0048] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "include..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0049] Photolithography is the process of transferring the pattern on the mask to the wafer through a photolithography machine. The light source used in photolithography has gone through on-axis illumination, off-axis illumination, and free-form pixelated illumination. This application scheme is mainly aimed at free-form pixelated illumination. Free-form light source optimization is based on the light source grid, and its hardware condition is a pixel-based lighting system. The light source plane is divided into two-dimensional grid points, and each light source grid point corresponds to a reflective sub-mirror controlled by a computer program. The array of multiple sub-mirrors reflects light to a fixed area to form an arbitrary form of light intensity distribution.

[0050] Light source and mask joint optimization is the main means to obtain free-form light sources under specific model conditions, and is also an important resolution enhancement technology for advanced semiconductor process nodes. After using the optimized light source, the focal depth, mask error enhancement factor, and normalized slope logarithm of the imaging pattern may be improved. In order to obtain a light source suitable for the photolithography process or an initial light source for light source and mask joint optimization, traditional solutions usually obtain a usable light source by referring to experience or making rough calculations based on some simplified formulas. For example, for dense line graphics, there is an empirical formula:

[0051] sigma_center = λ / (2*NA*P) (1)

[0052] Among them, λ is the wavelength of the light source, NA is the numerical aperture of the lithography machine lens, and P is the repetition period of the mask pattern. The light source center sigma_center calculated in this way can determine the center point of the off-axis illumination light source that is empirically suitable for imaging of this type of pattern. However, the calculation based on the empirical formula cannot take into account the impact of actual process factors on the results, and the obtained light source may deviate from the actual requirements, which will increase the complexity of subsequent corrections to the light source and increase the number of steps for subsequent optimization and debugging.

[0053] In order to solve the problems of the traditional solution, the embodiment of the present application provides a light source determination method, device, medium and product. The light source determination method provided by the embodiment of the present application is first introduced below. Figure 1 A schematic flow chart of a light source determination method provided in one embodiment of the present application is shown.

[0054] like Figure 1 As shown, the method comprises the following steps:

[0055] S101: Acquire multiple target points on the light source plane.

[0056] It should be noted that the specific number of target points selected here is not required. Selecting too many target points will increase the calculation time, while reducing the number of target points may reduce the calculation accuracy. Therefore, it can be determined based on the actual calculation time and the constraints of calculation accuracy.

[0057] In addition, the specific position of the target point on the light source plane is also not limited. Generally, the selected target points are evenly distributed on the light source plane, so that the local target imaging performance index corresponding to the target point can better reflect the overall imaging performance index of the entire light source plane. When obtaining the target point, the overall imaging performance index of the entire light source plane can be divided into multiple cells, and then the target cell is selected, and the center point of the target cell is used as the target point. The center coordinates of the light source can also be set to (0, 0), and a coordinate axis can be established. The length unit of the coordinate axis can be determined based on the width of the cell, which is convenient for locating the center point of each cell.

[0058] S102: Based on each target point, a corresponding target area is generated on the light source plane.

[0059] The above steps only take a coordinate point on the light source plane, and the light source needs a surface for illumination. Therefore, when generating the light source corresponding to the simulation, it is necessary to determine a surface for the selected target points in turn as the light source for illuminating the mask pattern.

[0060] The specific operation method is: generate the pole of the light source (i.e. the target area) with the target point as the center; the shape of the pole can be specified in advance, usually circular, fan-shaped, elliptical, leaf-shaped, etc.; these poles are used as the light source in the subsequent imaging simulation process, and the light intensity of the pole can be set to a uniform value, usually with the energy fill ratio (Fill Ratio) meeting the production requirements as the minimum standard.

[0061] S103: Using the light sources in each target area, imaging simulation is performed on the target mask pattern under preset process conditions to obtain corresponding target imaging performance indicators.

[0062] In the above steps, multiple target areas have been determined. In the imaging simulation process of this embodiment, a corresponding local light source needs to be generated for each target area, and imaging simulation needs to be performed for the local light source corresponding to each target area.

[0063] For one of the local light sources, it is necessary to perform imaging simulation on the target mask pattern under the preset process conditions, that is, to simulate the wafer pattern corresponding to the target mask pattern illuminated by this local light source, and then compare the target mask pattern and the wafer pattern to obtain the target imaging performance index. The imaging performance index may include depth of focus, mask error enhancement factor, normalized slope logarithm, etc.

[0064] As an optional implementation, the preset process conditions may include focal length, exposure energy, mask offset, measurement plane, etc.

[0065] In practical applications, the number of target mask patterns is not limited, and one or more can be selected according to actual conditions. In the case of multiple target mask patterns, a round of imaging simulation is required for each target mask pattern, and finally the results corresponding to all target mask patterns are summarized and analyzed to obtain the target imaging performance index.

[0066] S104: Based on the target imaging performance index and the position of the corresponding target area on the light source plane, generate an overall imaging performance index of the entire light source plane to determine the target light source.

[0067] The above steps obtain the local target imaging performance index of each target area. Based on the local information and the corresponding position, the overall imaging performance index of the entire light source plane can be derived. Finally, it is necessary to determine the final target light source based on the overall imaging performance index of the entire light source plane. As a feasible implementation method, based on the overall imaging performance index of the entire light source plane, the energy distribution area on the light source plane can be determined based on experience, and light sources are set in these suitable areas (i.e., areas where light source energy exists), and the energy intensity of the remaining areas is 0, thereby obtaining the final target light source.

[0068] As a feasible embodiment, the light source plane can be divided into multiple cells, and the imaging performance index of the local cell can be obtained through the local target imaging performance index, and the imaging performance index of all cells can be derived based on this, and then drawn accordingly on the light source plane, so as to generate the overall imaging performance index of the entire light source plane.

[0069] The drawn imaging performance index image can also be displayed, so that the user can intuitively understand the distribution of the imaging performance index on the light source plane, and thus determine the final target light source based on the distribution.

[0070] In this embodiment, the light source plane is divided into a plurality of cells, and when the target light source is finally determined, the specific energy intensity (the value is 0 or 1) of each cell is determined, so as to obtain the target light source. Figure 2 FIG. 4 shows a light source energy distribution diagram provided in an embodiment of the present application; Figure 2 As shown in the figure, it is an example of a light source distribution diagram of a 201*201 cell. Inside the light source plane, black indicates that the cell energy is 0, and white indicates that the cell energy is normalized to 1. The center coordinate of the light source is (0, 0), and the scale of the coordinate axis is [-1, 1]. In this example, there are four local light source areas (areas with light source energy) in the light source plane, all of which are fan-shaped and symmetrical to each other.

[0071] In order to quickly and accurately obtain a light source suitable for a lithography process or an initial light source for joint optimization of a light source and a mask, an embodiment of the present application provides a method that analyzes the imaging performance (depth of focus, logarithm of normalized slope, mask error enhancement factor, etc.) of a specific mask pattern based on the principle of partial coherence of a lithography light source and based on light source cells, thereby providing reference information for obtaining an adapted initial light source.

[0072] The scheme proposed in the embodiment of the present application can predict the gain effect (i.e., imaging performance index) of each point on the light source plane on the provided target mask pattern imaging under specific process conditions, and can complete the following tasks based on this: illumination light source selection under simple process, initial light source selection for light source and mask joint optimization, and judgment of whether there is a situation where the provided mask samples cannot converge together; thereby improving the execution efficiency of process research and development and light source optimization.

[0073] In addition, under the traditional scheme, when there are many mask target graphics based on the joint optimization of light source and mask and there may be process conflicts, the possibility of such conflicts is currently considered by evaluating the process simulation results after the optimization process. That is, it is impossible to scientifically and accurately evaluate the complexity of light source mask optimization caused by the number of mask samples before light source optimization. This will result in the inability to determine whether it has converged to the optimal solution after multiple rounds of optimization. However, this application can determine whether there is a conflict in mask design and avoid unnecessary debugging iterations.

[0074] A method for determining a light source provided in an embodiment of the present application generates corresponding target areas based on multiple target points on a light source plane, and uses the light sources of each target area to perform imaging simulation on the target mask pattern under preset process conditions to obtain corresponding target imaging performance indicators. Then, the overall imaging performance index of the entire light source plane is generated based on the above-obtained data; the final target light source is determined by the overall imaging performance index. This scheme determines the final target light source by obtaining the imaging performance index of the light source plane, so the light source can be adjusted according to actual needs in combination with the imaging performance index. Compared with the traditional method of simply relying on empirical formulas to roughly derive the light source, the present application determines the light source by simulating the imaging performance index, and can accurately obtain a light source that meets actual needs based on more and more accurate information, thereby improving production efficiency. In addition, simulation can also determine whether there is a conflict in the mask graphic design, avoiding unnecessary debugging iterations.

[0075] In the above embodiment, it is mentioned that it is necessary to obtain multiple target points on the light source plane, and then generate a target area and obtain a local target imaging performance index, and finally generate an overall imaging performance index based on the local target imaging performance index and the position of the target area. Therefore, the local target imaging performance index needs to be sufficiently representative, and the selection of target points is particularly important. For example, multiple target points that are evenly distributed can be selected on the light source plane to obtain a more accurate overall imaging performance index.

[0076] The embodiment of the present application provides a specific method for selecting a target point. First, a light source plane is divided into a plurality of cells. Then, downsampling is performed in each cell, a plurality of target cells are selected, and the center point of each target cell is determined as the target point.

[0077] It should be noted that the embodiments of the present application do not limit the division method of cells, and the light source plane is usually evenly divided into grids such as 32*32 (considering computational efficiency) or 201*201 (considering the physical structure of the light source). Figure 3 A schematic diagram of a cell division method of a light source plane provided in an embodiment of the present application is shown; Figure 3 As shown in the figure, the light source plane is a circular plane, which is divided into a series of equally spaced grid points (i.e., cells). Since the grid points are usually square, there are some incomplete grid points at the edge of the light source plane. These incomplete grid points can be ignored when selecting the target points later. Each grid point in the light source plane can be set with different energy intensities, which are usually normalized to a range of 0 to 1. The number of grid points is determined by the physical structure of the light source and the computational efficiency.

[0078] After the light source plane is gridded, the cell coordinates can be expressed in Cartesian coordinate axes or polar coordinates. The coordinates of the center point of the light source are generally set to (0, 0); the minimum value of the X and Y coordinates of the light source cell is generally set to -1, and the maximum value is generally set to 1; according to the number of cells, the center coordinates of each cell are obtained. Taking 201*201 as an example, the X coordinates of each cell are as follows: -1, -0.99, -0.98, ..., -0.01, 0, 0.01, ..., 0.98, 0.99, 1, and the Y coordinates are the same; cells with a distance from the center less than or equal to 1 are valid cells, and invalid cells do not physically exist, so invalid cells are not considered in subsequent steps.

[0079] The embodiment of the present application divides the cells, selects the target cell from multiple cells by downsampling, and further uses the center point of the target cell as the target point, thereby improving the rationality of the selected point, selecting a more representative target point, and ensuring the accuracy of the calculation result.

[0080] In practical applications, target cells can be selected according to specific circumstances. Selecting too many target cells will increase the amount of calculation, but it is necessary to ensure that the target area can represent the information of the entire light source plane. In this case, the target cells are preferably evenly distributed on the light source plane.

[0081] Therefore, in the solution provided in the embodiment of the present application, each divided cell is sampled at equal intervals to obtain multiple pending cells; then based on the pending cells, the target cell is determined. It should be noted that the specific size of the sampling interval is not limited here, and it is subject to actual needs. And the sampled pending cells can be directly used as target cells, or they can be further streamlined to select appropriate cells from the pending cells as target cells, thereby reducing the amount of calculation.

[0082] The embodiment of the present application selects cells by sampling at equal intervals, so that the selected cells are evenly distributed on the light source plane, which can reduce the number of selections to reduce the amount of calculation. At the same time, it ensures that the points are representative, and improves the accuracy of the subsequent generation of imaging performance indicators of the entire light source plane.

[0083] As mentioned above, the specific size of the sampling interval is not limited in actual applications, and a suitable sampling interval can ensure that both the calculation duration and the calculation accuracy meet the requirements. Therefore, in the scheme proposed in the embodiment of the present application, each cell is sampled at equal intervals to obtain multiple cells to be determined, including:

[0084] Based on the constraint conditions, the sampling interval is determined; based on the sampling interval, each cell is sampled at equal intervals to obtain multiple pending cells. The constraint conditions here may be a preset maximum calculation time and a minimum calculation accuracy, etc.

[0085] Specifically, the number of cells can be sampled at equal intervals according to the requirements of calculation time and calculation accuracy. For example, for a 201*201 cell, one point can be selected every 5 points in the X and Y directions as an evaluation point for simulation, and the cell coordinates in the evaluation group are -1, -0.95, -0.9, ..., 0.9, 0.95, 1.

[0086] The embodiment of the present application determines the sampling interval by constraints such as calculation time and calculation accuracy, which can minimize the calculation time while ensuring the actuarial accuracy and meet actual production needs.

[0087] As mentioned above, the determined pending cells can be further streamlined to determine fewer target cells. The present application embodiment proposes an implementation scheme:

[0088] First, the symmetry structure of the light source plane is obtained; then, based on the symmetry structure, each undetermined cell is divided into multiple cell groups. In the same cell group, each undetermined cell has the same imaging performance index; therefore, one undetermined cell can be selected from each cell group and determined as the target cell. Then one target cell can represent all undetermined cells in the same cell group.

[0089] The embodiment of the present application further simplifies the target cells according to the symmetry requirements of the light source plane setting. Figure 4 FIG. 2 shows a schematic diagram of the symmetry of the light source plane arrangement provided by an embodiment of the present application; Figure 4As shown, there is a target cell 401 in the light source plane, and the coordinates are (0.3, 0.7), and the cells that have equivalent effects to the target cell (0.3, 0.7) are also different when the light source plane has different symmetries. For example, symmetry generally includes DX, DY, D45, R90, D135, and R180. For the target cell with coordinates (0.3, 0.7), when the light source plane has different symmetries on the coordinate axis, the coordinates of the cells that have equivalent effects to the target cell (0.3, 0.7) are listed as: DX: (-0.3, 0.7); DY: (0.3, -0.7); D45: (0.7, 0.3); R90: (-0.7, 0.3) and (0.7, -0.3); D135: (-0.7, -0.3); R180: (-0.3, -0.7). In addition, the following symmetry descriptions are equivalent: D2 is equivalent to DX and DY; D4: is equivalent to DX, DY, D45 and D135.

[0090] The embodiment of the present application determines cells having the same imaging performance index through the symmetrical structure of the light source plane, thereby reducing the number of selected points and thus reducing the amount of calculation.

[0091] In a specific implementation, there is no limitation on how to perform imaging simulation. The preset process conditions can be obtained first; then the preset process conditions, the target area and the target mask pattern are input into the imaging simulation tool. The imaging simulation tool simulates the light source plane at the target area, and illuminates the target mask pattern by simulating the light source plane at the target area, thereby obtaining a simulation pattern. Then, by comparing the simulation pattern with the target mask pattern, the target imaging performance index corresponding to the target area is obtained.

[0092] In practical applications, the specific imaging simulation tool to be used can be selected based on the needs. For example, an Abbe imaging simulation tool based on a light source can be used. The Abbe imaging simulation tool can quickly obtain the imaging performance index of the specified mask pattern simulation under preset process conditions through a given light source. Different tools can have different implementation methods.

[0093] Traverse each target area generated above, generate the corresponding local light source, perform imaging simulation on the specified target mask pattern under the preset process conditions, and obtain the imaging performance index. The key settings are as follows:

[0094] Preset process conditions: including but not limited to focal length, exposure energy, mask offset, measurement plane, etc.

[0095] Specified target mask pattern: can be a two-dimensional plane pattern that meets or is close to the design rules; can be a collection of multiple mask patterns; usually the position to be measured is specified in the mask pattern.

[0096] Specified imaging performance indicators: usually focal depth, mask error enhancement factor, normalized slope logarithm, etc., or some customized imaging performance indicators.

[0097] If necessary, the mask needs to be optimized during simulation to achieve imaging of the target size.

[0098] In addition, according to the symmetry of the light source plane mentioned above, points with equivalent effects will synchronously generate poles (i.e., target areas) and add them to the light source composition. The poles of the equivalent points also need to be considered when calculating the fill rate.

[0099] The embodiment of the present application can simulate and obtain accurate imaging performance indicators by inputting information such as lithography process conditions, target area, and mask graphics into a simulation tool.

[0100] In addition, in order to determine the required target light source, the overall imaging performance index can be directly analyzed by the processor to obtain the target light source. The overall imaging performance index can also be displayed to the corresponding user, and the user determines the corresponding target light source based on actual needs. Therefore, after generating the overall imaging performance index of the entire light source plane, an imaging performance index image can be drawn on the light source plane based on the value of the overall imaging performance index; and the imaging performance index image is displayed. That is, the corresponding relationship between the imaging performance index of the target mask pattern and each cell of the light source plane is visualized.

[0101] First, the imaging performance index of the target mask pattern generated by each cell is counted at the measurement position, and its value is plotted on the light source plane according to the cell coordinates. The equivalent cell can be equivalently expanded according to the symmetry set above, that is, the imaging index value of the equivalent cell is considered to be the same as that of the current cell.

[0102] Figure 5 This is one of the imaging performance indicator images shown in one embodiment of the present application; Figure 5 As shown, the light source plane is D4 symmetric, the period of the target mask pattern is 120nm, and the specific imaging index is the normalized slope logarithm; the figure includes a first area 501, a second area 502 and a light source plane 503; the first area 501 has a higher normalized slope logarithm, and the second area 502 has a lower normalized slope logarithm.

[0103] Users can intuitively understand the overall imaging performance index of the light source plane for the target mask pattern through the imaging performance index image, and thus design the target light source actually required.

[0104] A specific embodiment is provided below. The minimum value of the X and Y coordinates of the cell is set to -1, the maximum value is set to 1, the number of cells is set to 32*32, the grid spacing is set to 0.0625, the symmetry is set to D2, the shape of the pole is set to be square, and the size is set to be one cell. The process conditions are as follows: 193nm immersion lithography, NA=1.35; polarization is transverse electric field (TE); focal length (positive from the top layer of the film system downward) is 50nm, and the measurement plane is 65nm; the anchor pattern is a numerical line with a width of 50nm and a period of 100nm, and its mask anchor bias (Anchor Bias) is 1nm (i.e., the exposure imaging of a pattern with a mask width of 52nm is 50nm). A set of film system parameters (refractive index, extinction coefficient, and thickness) need to be provided.

[0105] Target mask pattern: vertical lines with a feature size width of 50nm and periods of 100, 140, 220 and 300nm. The measurement position is the line width. The evaluation index is the logarithm of the normalized slope of each pattern.

[0106] Figure 6 A normalized slope logarithmic distribution diagram of vertical lines with a period of 100 nm is provided in an embodiment of the present application; wherein the target mask pattern used for simulation imaging is a vertical line with a period of 100 nm. Figure 7 A normalized slope logarithmic distribution diagram of vertical lines with a period of 140nm is provided in an embodiment of the present application; wherein the target mask pattern used for simulation imaging is a vertical line with a period of 140nm. Figure 8 A normalized slope logarithmic distribution diagram of vertical lines with a period of 220nm is provided in an embodiment of the present application; wherein the target mask pattern used for simulation imaging is a vertical line with a period of 220nm. Fig. 9 A normalized slope logarithmic distribution diagram of a vertical line with a period of 300nm provided in an embodiment of the present application; Fig. 9 As shown, the target mask pattern used for simulation imaging is a vertical line with a period of 300nm. Figures 6 to 9 In the figure, the normalized slope logarithm distribution is drawn based on the light source plane, and the color depth represents the size of the normalized slope logarithm. The normalized slope logarithm distribution in each figure is symmetrical on the left and right.

[0107] Figures 6 to 9 The two contour lines are the set normalized slope logarithm level dividing lines, and the values ​​of normalized slope logarithm are NILS = 1.2 and NILS = 2. It can be seen that the light source that meets the normalized slope logarithm requirements of the pattern with a period of 100nm can basically meet the normalized slope logarithm requirements of other pattern imaging.

[0108] In order to solve the above technical problems, the embodiment of the present application further provides a light source determination device, Fig.10 FIG. 1 shows a schematic diagram of the structure of a light source determination device provided in an embodiment of the present application. Fig.10 As shown, the device includes the following modules:

[0109] An acquisition module 1001 is used to acquire multiple target points on a light source plane;

[0110] The first generating module 1002 is used to generate corresponding target areas on the light source plane based on each target point;

[0111] The simulation module 1003 is used to use the light sources of each target area to perform imaging simulation on the target mask pattern under preset process conditions to obtain the corresponding target imaging performance index;

[0112] The second generating module 1004 is used to generate an overall imaging performance index of the entire light source plane based on the target imaging performance index and the position of the corresponding target area on the light source plane to determine the target light source.

[0113] In some embodiments, the acquisition module 1001 is specifically used to:

[0114] Divide the light source plane into a plurality of cells;

[0115] Downsample each cell and select multiple target cells;

[0116] The center point of each target cell is determined as the target point.

[0117] In some embodiments, the acquisition module 1001 is specifically used to:

[0118] Sampling each cell at equal intervals to obtain multiple pending cells;

[0119] Based on the pending cells, determine the target cells.

[0120] In some embodiments, the acquisition module 1001 is specifically used to:

[0121] Based on the constraints, determine the sampling interval;

[0122] Based on the sampling interval, each cell is sampled at equal intervals to obtain a plurality of pending cells.

[0123] In some embodiments, the acquisition module 1001 is specifically used to:

[0124] Obtaining the symmetric structure of the light source plane;

[0125] Based on the symmetric structure, each undetermined cell is divided into a plurality of cell groups; each undetermined cell in the same cell group has the same imaging performance index;

[0126] Select a pending cell in each cell group and determine it as the target cell.

[0127] In some embodiments, the simulation module 1003 is specifically used to:

[0128] Obtain preset process conditions;

[0129] The preset process conditions, target area and target mask pattern are input into the imaging simulation tool to obtain the target imaging performance index.

[0130] In some embodiments, the light source determination device further includes:

[0131] A drawing module, for drawing an imaging performance index image on the light source plane based on the value of the overall imaging performance index after generating the overall imaging performance index of the entire light source plane based on the target imaging performance index and the position of the corresponding target area on the light source plane;

[0132] The display module is used to display the imaging performance index image.

[0133] The device provided in the embodiment of the present application is the same as the method in the above embodiment, so both have the same embodiments and beneficial effects, which will not be repeated here.

[0134] Fig.11 FIG. 1 is a schematic diagram showing the hardware structure of a light source determination device provided in an embodiment of the present application. Fig.11 As shown, the light source determination device may include a processor 1101 and a memory 1102 storing computer program instructions.

[0135] Specifically, the processor 1101 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0136] The memory 1102 may include a large capacity memory for data or instructions. By way of example and not limitation, the memory 1102 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. In appropriate cases, the memory 1102 may include a removable or non-removable (or fixed) medium. In appropriate cases, the memory 1102 may be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 1102 is a non-volatile solid-state memory.

[0137] The memory 1102 may include a read-only memory (ROM), a random access memory (RAM), a magnetic disk storage medium device, an optical storage medium device, a flash memory device, an electrical, optical or other physical / tangible memory storage device. Thus, typically, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., a memory device) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to an aspect of the present disclosure.

[0138] The processor 1101 implements any one of the light source determination methods in the above embodiments by reading and executing computer program instructions stored in the memory 1102 .

[0139] In one example, the light source determination device may further include a communication interface 1103 and a bus 1104. The processor 1101, the memory 1102, and the communication interface 1103 are connected via the bus 1104 and communicate with each other.

[0140] The communication interface 1103 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0141] The bus 1104 includes hardware, software or both, and couples the components of the light source determination device to each other. For example, but not limitation, the bus may include an Accelerate Graphical Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnection, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnection, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or other suitable buses or a combination of two or more of these. Where appropriate, the bus 1104 may include one or more buses. Although embodiments of the present application describe and illustrate a particular bus, the present application contemplates any suitable bus or interconnect.

[0142] In addition, in combination with the light source determination method in the above embodiment, the embodiment of the present application can provide a computer storage medium for implementation. The computer storage medium stores computer program instructions; when the computer program instructions are executed by a processor, any one of the light source determination methods in the above embodiment is implemented.

[0143] An embodiment of the present application further provides a computer program product, including a computer program, and when the computer program is processed and executed, any one of the light source determination methods in the above embodiments is implemented.

[0144] It should be clear that the present application is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present application is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present application.

[0145] The functional blocks shown in the block diagram above can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an ASIC, appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present application are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (Erasable ROM, EROM), floppy disks, compact disc read-only memory (Compact Disc Read-Only Memory, CD-ROM), optical discs, hard disks, optical fiber media, radio frequency (Radio Frequency, RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0146] It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, this application is not limited to the order of the above steps, that is, the steps can be performed in the order mentioned in the embodiment, or in a different order from the embodiment, or several steps can be performed simultaneously.

[0147] Aspects of the present disclosure are described above with reference to the flowcharts and / or block diagrams of a method, device, medium, and product for determining a light source according to an embodiment of the present disclosure. It should be understood that each box in the flowchart and / or block diagram and the combination of each box in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine so that these instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the functions / actions specified in one or more boxes of the flowchart and / or block diagram. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field programmable logic circuit. It can also be understood that each box in the block diagram and / or flowchart and the combination of boxes in the block diagram and / or flowchart can also be implemented by dedicated hardware that performs a specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0148] The above contents are only specific implementation methods of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application.

Claims

1. A method for determining a light source, characterized in that: include: Acquire multiple target points on the light source plane; Based on each of the target points, a corresponding target area is generated on the light source plane; Using the light sources of each of the target areas, imaging simulation is performed on the target mask pattern under preset process conditions to obtain corresponding target imaging performance indicators; Based on the target imaging performance index and the corresponding position of the target area on the light source plane, an overall imaging performance index of the entire light source plane is generated to determine the target light source.

2. The light source determination method according to claim 1, characterized in that: The step of acquiring a plurality of target points on the light source plane includes: Dividing the light source plane into a plurality of cells; Downsampling is performed in each of the cells to select a plurality of target cells; The center point of each target cell is determined as the target point.

3. The light source determination method according to claim 2, characterized in that: The downsampling is performed in each of the cells, and a plurality of target cells are selected, including: Sampling each of the cells at equal intervals to obtain a plurality of cells to be determined; Based on the undetermined cell, the target cell is determined.

4. The light source determination method according to claim 3, characterized in that: The sampling of each of the cells is performed at equal intervals to obtain a plurality of cells to be determined, including: Based on the constraints, determine the sampling interval; Based on the sampling interval, each of the cells is sampled at equal intervals to obtain a plurality of cells to be determined.

5. The light source determination method according to claim 3, characterized in that: The step of determining the target cell based on the undetermined cell includes: Acquire the symmetric structure of the light source plane; Based on the symmetric structure, each of the cells to be determined is divided into a plurality of cell groups; each of the cells to be determined in the same cell group has the same imaging performance index; One of the pending cells is selected from each of the cell groups and determined as the target cell.

6. The light source determination method according to claim 1, characterized in that: The light sources of each target area are used to perform imaging simulation on the target mask pattern under preset process conditions to obtain corresponding target imaging performance indicators, including: Obtaining the preset process conditions; The preset process conditions, the target area and the target mask pattern are input into an imaging simulation tool to obtain the target imaging performance index.

7. The light source determination method according to any one of claims 1 to 6, characterized in that: After generating the overall imaging performance index of the entire light source plane based on the target imaging performance index and the corresponding position of the target area on the light source plane, the method further includes: Based on the value of the overall imaging performance index, drawing an imaging performance index image on the light source plane; The imaging performance index image is displayed.

8. A light source determination device, characterized in that: include: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, the light source determination method according to any one of claims 1 to 7 is implemented.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions, and when the computer program instructions are executed by a processor, the light source determination method according to any one of claims 1 to 7 is implemented.

10. A computer program product, characterized in that When the instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the light source determination method as described in any one of claims 1 to 7.

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