Developing method and apparatus based on mask pattern density

Abstract

The application provides a developing method and device based on mask pattern density, and relates to the field of semiconductors. The method comprises the following steps: obtaining mask pattern density of a plurality of preset regions in each layer of mask of a wafer to be developed, wherein the preset regions at least represent regions with the densest pattern distribution in each layer of mask; in the case that the mask pattern density of any of the preset regions is not less than a preset threshold, developing the wafer to be developed by using a first developing mode; otherwise, developing the wafer to be developed by using a second developing mode, wherein the developing effect of the first developing mode is better than that of the second developing mode. The application designs a developing mode selection method based on mask pattern density, so that the appropriate developing mode can be accurately selected by simple calculation before semiconductor production, and the product quality is ensured while the cost is optimized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a development method and apparatus based on mask pattern density. Background Technology

[0002] In semiconductor manufacturing processes, the exposed wafers that have been coated with photoresist need to undergo a development process. This process dissolves and removes the photoresist in areas that do not need to be covered, resulting in the desired pattern. This allows for selective processing of specific areas of the wafer in subsequent processes.

[0003] During this process, the developing ability of the developing method affects the resulting pattern. Specifically, if the developing ability of the selected developing method is insufficient, it can easily lead to residual photoresist defects, affecting the uniformity of critical dimensions.

[0004] However, directly choosing the development method with the best development effect will lead to a higher semiconductor production cost. Therefore, how to balance the development effect and production cost of the development method selected in semiconductor process is still an urgent problem to be solved. Summary of the Invention

[0005] This invention provides a development method and apparatus based on mask pattern density to address the shortcomings of existing technologies in balancing development effect and production cost in semiconductor processes, and to achieve a development method that can optimize production costs while ensuring development quality.

[0006] This invention provides a development method based on mask pattern density, comprising:

[0007] Obtain the mask pattern density of several preset regions in each mask layer of the wafer to be developed, wherein the preset regions at least represent the regions with the densest pattern distribution in each mask layer;

[0008] If the mask pattern density in any of the preset regions is not less than a preset threshold, the first type of development method is selected to develop the wafer to be developed.

[0009] Otherwise, the second type of development method is selected to develop the wafer to be developed, wherein the development effect of the first type of development method is better than that of the second type of development method.

[0010] According to the present invention, a development method based on mask pattern density is provided, wherein the preset area includes a measurement area and a key area for each mask layer, wherein the key area is the area with the densest pattern distribution in each mask layer.

[0011] According to a development method based on mask pattern density provided by the present invention, the step of obtaining the mask pattern density of several preset regions in each mask layer of the wafer to be developed specifically includes:

[0012] Determine the center coordinates of the measurement area of ​​each mask layer on the wafer to be developed;

[0013] Calculate the mask pattern density of the first preset range region centered on the central coordinates, and use it as the mask pattern density of the measurement region.

[0014] According to a development method based on mask pattern density provided by the present invention, before the step of calculating the mask pattern density of a first preset range region centered on the center coordinates, the method further includes:

[0015] Multiple preparation ranges of different sizes are predetermined. The center coordinates are used as the regional center of the preparation range. The mask pattern density of each mask layer of the wafer to be developed is calculated in each preparation range region. The first mask pattern density sequence and the second mask pattern density sequence corresponding to each preparation range and each mask layer are obtained respectively.

[0016] Multiple preparatory ranges with similar values ​​are obtained by filtering from the second mask pattern density sequence, and a first mask pattern density sequence of the filtered multiple preparatory ranges is determined.

[0017] The set of the least numerically fluctuating groups in the first mask pattern density sequence is determined as the first preset range.

[0018] According to the present invention, a development method based on mask pattern density is provided, wherein the first preset range is a square region with a side length greater than or equal to 500 micrometers and less than or equal to 1000 micrometers.

[0019] According to a development method based on mask pattern density provided by the present invention, the step of obtaining the mask pattern density of several preset regions in each mask layer of the wafer to be developed specifically includes:

[0020] Several key coordinates are observed and determined in each mask layer of the wafer to be developed, wherein the key coordinates represent the positions where the pattern distribution is most dense in each mask layer;

[0021] Calculate the mask pattern density of a second preset range region centered on the key coordinates;

[0022] The mask pattern density with the highest calculated value is taken as the mask pattern density of the key region.

[0023] According to a development method based on mask pattern density provided by the present invention, the mask pattern density is the ratio of the area of ​​the light-transmitting area in the preset region to the total area of ​​the preset region multiplied by an adjustment coefficient, wherein the adjustment coefficient is determined based on the target critical dimension and the actual critical dimension of the mask of the wafer to be developed.

[0024] According to a development method based on mask pattern density provided by the present invention, before the step of developing the wafer to be developed using a first type of development method when the mask pattern density in any of the preset regions is not less than a preset threshold, the method further includes:

[0025] Obtain a test wafer, and develop multiple layers of the test wafer using a second type of development method;

[0026] The mask pattern density of a preset region in multiple layers whose development effect does not meet the preset standard is calculated, and the preset threshold is determined based on the minimum mask pattern density obtained from the calculation.

[0027] The present invention also provides a developing apparatus based on mask pattern density, comprising:

[0028] The acquisition module is used to acquire the mask pattern density of several preset regions in each mask layer of the wafer to be developed, wherein the preset regions at least represent the regions with the densest pattern distribution in each mask layer;

[0029] The determination module is used to select a first type of development method to develop the wafer to be developed when the mask pattern density in any of the preset areas is not less than a preset threshold.

[0030] Otherwise, the second type of development method is selected to develop the wafer to be developed, wherein the development effect of the first type of development method is better than that of the second type of development method.

[0031] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the development method based on mask pattern density as described above.

[0032] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the development method based on mask pattern density as described above.

[0033] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the development method based on mask pattern density as described above.

[0034] The developing method and apparatus based on mask pattern density provided by this invention calculates the mask pattern density of the wafer to be developed in a preset area, and selects an appropriate developing method based on the mask pattern density to achieve a balance between developing effect and production cost. It achieves the lowest possible production cost while ensuring developing effect. In addition, an unexpected effect is that by designing a developing method based on mask pattern density, the appropriate developing method can be accurately selected through simple calculation before semiconductor production, ensuring product quality while achieving optimal cost. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic flowchart of the development method based on mask pattern density provided by the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of the developing apparatus based on mask pattern density provided by the present invention;

[0038] Figure 3 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] The following is combined Figure 1 This invention introduces a development method based on mask pattern density, such as... Figure 1 As shown, it includes:

[0041] Step 101: Obtain the mask pattern density of several preset regions in each mask layer of the wafer to be developed, wherein the preset regions at least represent the regions with the densest pattern distribution in each mask layer;

[0042] To determine the appropriate development method for wafers before semiconductor production, in order to balance development effect and semiconductor production cost, analysis of wafers with poor development effect in historical production processes revealed that the mask pattern density of the wafer affects the development effect.

[0043] Specifically, when the mask pattern density of each layer of a wafer is higher, it is easy to have photoresist residue when using a development method with slightly lower development capability. However, for the same mask, using a development method with better development capability can ensure the uniformity of its critical dimension (CD) after development.

[0044] Based on the above findings, alternatively, the mask pattern density of each mask layer on the wafer to be developed can be calculated before semiconductor production, and a suitable development method can be determined based on the mask pattern density of the wafer to be developed.

[0045] The mask pattern density refers to the density of the mask pattern. In one feasible implementation, it can be obtained by calculating the ratio of the area of ​​the light-transmitting region of the mask to the total area of ​​the mask.

[0046] It is understood that in other feasible implementations, the density of the mask pattern can be characterized by calculating the ratio of the area of ​​the light-transmitting region of the mask to the area of ​​the opaque region of the mask, or by first calculating the ratio of the area of ​​the light-transmitting region of the mask to the total area of ​​the mask, and then multiplying it by an adjustment coefficient determined based on the semiconductor manufacturing process.

[0047] Furthermore, since the mask is relatively large and the light-transmitting area of ​​the mask is usually unevenly distributed, the development method that directly calculates the mask pattern density of the entire mask may still result in poor development effect.

[0048] Therefore, in this embodiment, several preset regions are determined in the mask of each layer of the wafer to be developed, and the mask pattern density of the preset regions is calculated to characterize the pattern density of the mask layer.

[0049] The preset region at least represents the region with the densest pattern distribution in each mask layer of the wafer to be developed, so as to better select the development method according to the mask pattern density of the fixed region, thereby better developing the wafer.

[0050] In one feasible implementation, the mask layout information of the wafer to be developed is obtained, and by observing the pattern distribution in the mask layout, several regions with relatively concentrated pattern distribution are directly selected as preset regions.

[0051] In other feasible implementations, the preset area may also include areas that require special attention during semiconductor manufacturing, such as areas where high CD accuracy is required after development, so as to take into account the mask pattern density of such areas when selecting the development method.

[0052] Optionally, the size and shape of the preset area can be determined based on the mask layout information of the wafer to be developed, or it can be determined based on experience.

[0053] Using the above method, the mask pattern density of several preset areas of the wafer to be developed can be calculated, so as to determine the development method of the wafer to be developed based on this.

[0054] Step 102: If the mask pattern density in any of the preset regions is not less than a preset threshold, the first type of development method is selected to develop the wafer to be developed.

[0055] Otherwise, the second type of development method is selected to develop the wafer to be developed, wherein the development effect of the first type of development method is better than that of the second type of development method.

[0056] Optionally, the preset threshold is predefined empirically based on the calculation method of the defined mask pattern density.

[0057] Optionally, the first and second development methods are predefined based on the development methods achievable in the semiconductor manufacturing process. The first development method should have a better development effect than the second, enabling better development of wafers for which the second method is difficult to achieve optimal development. It is understood that, generally, the development cost of the first type of development method, which offers better development results, is higher than that of the second type. This development cost can be the cost of developer usage and / or the cost of development time.

[0058] In this embodiment, the first type of development method is determined to be dynamic development, and the second type of development method is determined to be static development.

[0059] Static development involves spraying developer and then immersing the wafer in it. This method uses less developer and is low-cost, but its developing ability is poor and it is prone to incomplete development. Dynamic development involves spraying developer and then rotating the wafer on the worktable to accelerate the flow of developer and fully cover the wafer surface to ensure the developing effect. This method has a better developing effect and can achieve full development, but it uses more developer and has a higher developing cost.

[0060] Based on this, if the mask pattern density in any preset area is not less than a preset threshold, it is considered that the pattern density in the mask of this layer of the wafer to be developed is relatively large, and the first type of development method with better development effect needs to be used to develop this layer.

[0061] Otherwise, if the mask pattern density of all preset areas is less than the preset threshold, it is considered that the mask pattern density of this layer of the wafer to be developed is small, and a good development effect can be achieved without using a high-cost development method. Therefore, the lower-cost second type of development method is used to develop this layer.

[0062] It should be noted that although some studies have focused on the relationship between the mask pattern density of wafers and the development effect, they have focused more on the mask pattern design process. That is, by calculating whether the critical dimensions of the wafer meet the preset production standards after development, the mask pattern design is adjusted if it does not meet the standards, so as to make the distribution of the mask pattern more uniform and thus obtain more accurate critical dimensions after development. However, the process of resetting the mask pattern is relatively cumbersome, and adjusting the mask pattern based on the critical dimensions after development also requires a longer process and testing time.

[0063] This invention calculates the mask pattern density of the wafer to be developed in a preset area and selects an appropriate development method based on the mask pattern density to achieve a balance between development effect and production cost. It ensures the development effect while achieving the lowest possible production cost. In addition, an unexpected effect is that by designing a development method selection method based on mask pattern density, the appropriate development method can be accurately selected through simple calculations before semiconductor production, ensuring product quality while achieving optimal cost.

[0064] In the development method based on mask pattern density of the present invention, the preset area includes a measurement area and a key area for each mask layer, wherein the key area is the area with the densest pattern distribution in each mask layer.

[0065] In order to enable the mask pattern density calculated based on the preset area to be better used to select the appropriate development method, in this embodiment, the preset area includes the measurement area and the key area of ​​each mask layer.

[0066] The measurement area is a specific pattern or region on the mask used for measurement and verification. The pattern of the measurement area is usually used to evaluate the quality of the mask, the accuracy of the photolithography process, and key parameters in the chip manufacturing process.

[0067] It is understandable that, since the measurement area itself is the area that needs to be evaluated in the semiconductor manufacturing process, the measurement area of ​​each mask layer is used as the preset area, and the pattern density of the measurement area is used as the criterion for selecting the development method. If the mask pattern density calculated by the measurement area is greater than or equal to the preset threshold, then the first type of development method must be used for development to ensure the development effect.

[0068] Optionally, the mask layout information of the wafer to be developed is obtained, and the measurement area of ​​each mask layer is determined based on the mask layout information. The overall mask pattern density of the measurement area is directly calculated, and the mask pattern density of the measurement area is compared with a preset threshold for judgment.

[0069] The critical region is the area with the densest pattern distribution in each mask layer of the wafer to be developed. Optionally, the shape, position and area of ​​the critical region can be directly defined by observing the mask layout information.

[0070] One or more key regions can be identified based on the pattern design of each mask layer. The mask pattern density of each selected key region is calculated separately, and the obtained mask pattern density is compared with a preset threshold for judgment.

[0071] In the mask pattern density-based development method of the present invention, the step of obtaining the mask pattern density of several preset regions in each mask layer of the wafer to be developed specifically includes:

[0072] Determine the center coordinates of the measurement area of ​​each mask layer on the wafer to be developed;

[0073] Calculate the mask pattern density of the first preset range region centered on the central coordinates, and use it as the mask pattern density of the measurement region.

[0074] The center coordinates of the measurement area are the coordinates of the geometric center of the measurement area of ​​each mask layer on the wafer to be developed.

[0075] In one implementation, the center coordinates of the measurement area of ​​each mask layer are read directly based on the mask layout information of the wafer to be developed.

[0076] In other feasible implementations, if the center coordinates of the measurement area cannot be directly obtained, when the measurement area is a regular geometric area, the coordinates of the intersection of its multiple diagonals are used as the center coordinates of the measurement area; when the measurement area is an irregular geometric area, the smallest bounding rectangle of the measurement area can be determined, and the coordinates of the intersection of its diagonals are used as the center coordinates of the measurement area.

[0077] A first preset range is predetermined, and the mask pattern density of the region centered on the center coordinates of the measurement area and within the first preset range is calculated. This density is used as the mask pattern density of the measurement area to achieve a standardized process while accurately reflecting the pattern density of the measurement area.

[0078] Optionally, the first preset range can be an empirical value.

[0079] In the development method based on mask pattern density of the present invention, before the step of calculating the mask pattern density of a first preset range region centered on the center coordinates, the method further includes:

[0080] Multiple preparation ranges of different sizes are predetermined. The center coordinates are used as the regional center of the preparation range. The mask pattern density of each mask layer of the wafer to be developed is calculated in each preparation range region. The first mask pattern density sequence (sequence elements correspond to columns in Table 1) and the second mask pattern density sequence (sequence elements correspond to elements in each row of Table 1) corresponding to each preparation range are obtained respectively.

[0081] Multiple preparatory ranges with similar values ​​are obtained by filtering from the second mask pattern density sequence, and a first mask pattern density sequence of the filtered multiple preparatory ranges is determined.

[0082] The set of the least numerically fluctuating groups in the first mask pattern density sequence is determined as the first preset range.

[0083] In order to obtain a first preset range that can accurately reflect the mask pattern density of the measurement area, in this embodiment, multiple preset ranges of different sizes are determined in advance based on experience.

[0084] For example, five preliminary ranges are selected in advance: 100×100 micrometers, 300×300 micrometers, 500×500 micrometers, 700×700 micrometers, and 1000×1000 micrometers, and the complete range of the measurement area is used as a comparison.

[0085] Multiple different layers of the wafer to be developed are predetermined for the comparison calculation. For each selected layer, the center coordinates of its corresponding measurement area are taken as the area center, and the five preparatory ranges are taken as the area range. The mask pattern density corresponding to each of the five preparatory ranges is calculated, and the mask pattern density of the entire measurement area is calculated as a comparison.

[0086] Based on this, taking the selection of 1D layer (first diffusion layer) and 3L layer (third metal layer) as an example, the second mask pattern density sequence {A1, A2, A3, A4, A5, A6} calculated for each preparatory range of 1D layer is obtained, and the second mask pattern density sequence {B1, B2, B3, B4, B5, B6} calculated for each preparatory range of 3L layer is obtained.

[0087] Simultaneously, the first mask pattern density sequence corresponding to all layer masks for each preparatory range is obtained, {A1, B1}, {A2, B2}, A3, B3}, {A4, B4}, {A5, B5} and {A6, B6}.

[0088] It is understandable that selecting a preparatory range that is too large or too small will result in limitations in the calculated mask pattern density. Therefore, multiple preparatory ranges with similar values ​​are selected in the second mask pattern density sequence corresponding to each mask layer, as it is believed that similar values ​​can accurately characterize the mask pattern density of that layer.

[0089] For example, in the second mask pattern density sequence corresponding to the 1D layer, the values ​​of {A2, A3, A4} corresponding to the three preparatory ranges of 300×300 μm, 500×500 μm, and 700×700 μm are similar; in the second mask pattern density sequence corresponding to the 3L layer, the values ​​of {B3, B4} corresponding to the two preparatory ranges of 500×500 μm and 700×700 μm are similar.

[0090] Therefore, two preliminary ranges of 500×500 μm and 700×700 μm were obtained through screening. Based on this, the numerical fluctuations of the first mask pattern density sequences {A3, B3} and {A4, B4} corresponding to these two preliminary ranges were further calculated.

[0091] In this embodiment, since each first mask pattern density sequence contains only two numbers, the difference between them is directly calculated as the degree of fluctuation of the sequence, and the first mask pattern density sequence with the smallest difference is considered to have the smallest numerical fluctuation. In other feasible embodiments, if the first mask pattern density sequence contains multiple numbers, the first mask pattern density sequence with the smallest standard deviation is considered to have the smallest numerical fluctuation by calculating the standard deviation of each set of values.

[0092] The range of the first set of mask pattern density sequences with the smallest numerical fluctuations is taken as the first preset range to accurately reflect the mask pattern density of each measurement area of ​​the wafer to be developed.

[0093] In other feasible implementations, multiple preparatory ranges with similar values ​​can be selected from the second mask pattern density sequence, and the preparatory range with the smallest area can be used as the first preset range to minimize the computational cost of the mask pattern density.

[0094] In the development method based on mask pattern density of the present invention, the first preset range is a square region with a side length greater than or equal to 500 micrometers and less than or equal to 1000 micrometers.

[0095] In this embodiment, five pre-selected ranges of 100×100 μm, 300×300 μm, 500×500 μm, 700×700 μm, and 1000×1000 μm are selected in advance, and the complete range of the measurement area is used as a comparison; the mask pattern density of each pre-selected range is calculated using 1D and 3D layers, as shown in Table 1 below:

[0096] Table 1

[0097]

[0098] It can be observed that if the first preset range is large, for example, if the mask pattern density of the entire complete measurement area is directly calculated, the calculated mask pattern density value will be too small because the selected area covers a large portion of the edge of the measurement area.

[0099] If the first preset range is small, such as 100×100μm, the results will be limited due to the small selected area, making it difficult to accurately measure the mask pattern density of the measurement area.

[0100] When the prepared range is 500×500μm, 700×700μm and 1000×1000μm, the calculated mask pattern density is relatively similar. Therefore, it is believed that this value can reflect the mask pattern density of the measurement area more realistically. At the same time, it also shows that the mask pattern density calculated in the range of 500×500μm to 1000×1000μm can reflect the mask pattern density of the measurement area.

[0101] Therefore, the first preset range is considered to be a square region with a side length within [500μm, 1000μm].

[0102] Based on this, the preliminary range of 500×500μm, which has the smallest difference between the calculation results of the 1D layer and the 3L layer, is selected as the first preset range, so that the calculation results based on this range can accurately reflect the mask pattern density of each layer of the wafer to be developed.

[0103] Meanwhile, in a large number of experiments, it was determined that the 500×500μm pre-set range can be applied to various wafers with different mask layouts. Therefore, as a preferred option, a rectangular area with a length and width of 500 micrometers is used directly as the first preset range. This eliminates the need for extensive calculations based on different wafers to be developed before production, and allows for the direct calculation of the accurate mask pattern density of the measurement area using this range.

[0104] In the mask pattern density-based development method of the present invention, the step of obtaining the mask pattern density of several preset regions in each mask layer of the wafer to be developed specifically includes:

[0105] Several key coordinates are observed and determined in each mask layer of the wafer to be developed, wherein the key coordinates represent the positions where the pattern distribution is most dense in each mask layer;

[0106] Understandably, although it is possible to determine a general preliminary area with a relatively dense pattern distribution in each corresponding mask layer by observation, it is difficult to further determine which part of the pattern is denser in a large preliminary area by the naked eye, so as to obtain the most accurate key area.

[0107] Therefore, it is still necessary to identify the key regions that can better characterize the densest areas of the mask pattern from the initial regions that are easy to observe directly.

[0108] Therefore, we first selected several key coordinates that can characterize the locations where the pattern distribution is densest in each mask layer by observation.

[0109] Optionally, several locations may be randomly selected within the defined initial area, and their coordinates may be determined as key coordinates.

[0110] Calculate the mask pattern density of a second preset range region centered on the key coordinates;

[0111] Calculate the mask pattern density of the region centered at each key coordinate and within a second preset range in the mask.

[0112] Optionally, the second preset range is an empirical value.

[0113] Optionally, the second preset range may be the same as or different from the first preset range.

[0114] Optionally, the second preset range can be determined based on the measurement area of ​​the mask.

[0115] Optionally, the second preset range is a rectangular area of ​​500×500μm.

[0116] In one specific implementation, based on the center coordinates of the measurement area of ​​the mask, a first preset range is determined in a plurality of preset pre-defined areas, and this range is used as a second preset range, which is considered to be able to accurately reflect the mask pattern density of common mask layouts in production.

[0117] The mask pattern density with the highest calculated value is taken as the mask pattern density of the key region.

[0118] Based on several selected key coordinates, several mask pattern densities are calculated. The mask pattern density with the highest calculated value is taken as the mask pattern density of the key region. The region centered on the key coordinates and within the second preset range is the key region with the highest pattern density in each mask layer of the wafer to be developed.

[0119] The above method achieves a way to determine the key region and the mask pattern density of the key region based on a fixed point. In other feasible implementations, a second preset range of sliding windows can be constructed based on a fixed region, that is, by observing and determining the preliminary region of pattern concentration in the mask. The sliding windows are then slid in the preliminary region with a fixed step size. By calculating the mask pattern density of each sliding window, the mask pattern density with the highest calculated value is taken as the mask pattern density of the key region, and the region to which the corresponding sliding window belongs is taken as the key region.

[0120] In the mask pattern density-based development method of the present invention, the mask pattern density is the ratio of the area of ​​the light-transmitting area in the preset region to the total area of ​​the preset region multiplied by an adjustment coefficient, wherein the adjustment coefficient is determined based on the target critical dimension and the actual critical dimension of the mask of the wafer to be developed.

[0121] Although the mask pattern density of the preset area can be reflected by directly calculating the ratio of the area of ​​the light-transmitting area (i.e. the corresponding development reaction area) in the preset area of ​​the mask to the total area of ​​the preset area in the mask.

[0122] However, since there is a discrepancy between the target critical size of the mask and the actual critical size of the mask, an adjustment coefficient is defined in this embodiment to better reflect the pattern density of the preset area of ​​the mask. K It is the ratio of the target critical dimension (Target CD) to the actual critical dimension (Mask CD) of the mask.

[0123] Based on this, the mask pattern density N can be calculated using the following formula:

[0124]

[0125] In the formula, S c This indicates the area of ​​the light-transmitting region of the mask. S T This represents the total area of ​​the mask region. It can be understood that when the above formula is used to calculate the area of ​​the mask pattern for a preset area, S c That is, the area of ​​the light-transmitting region within the preset area. S T That is, the total area of ​​the preset region.

[0126] In the mask pattern density-based development method of the present invention, before the step of selecting a first type of development method to develop the wafer to be developed when the mask pattern density in any of the preset regions is not less than a preset threshold, the method further includes:

[0127] Obtain a test wafer, and develop multiple layers of the test wafer using a second type of development method;

[0128] Calculate the mask pattern density of the preset regions of multiple layers where the development effect does not meet the preset standard, and determine the preset threshold based on the calculated minimum mask pattern density.

[0129] In order to determine a relatively accurate preset threshold, in this embodiment, first obtain multiple pieces of historical development data. The development data includes the mask density of the preset region, the development method, and the development effect.

[0130] Optionally, obtain a test wafer. First, develop each layer of the test wafer using a second type of development method and record the development effect.

[0131] Optionally, the development effect can be characterized by determining the uniformity of the critical dimension after development or development defects. For example, calculate CDU (Critical Dimension Uniformity), compare it with the target value. If the difference between the two is within the standard range, it is considered that the development effect is good; otherwise, it is considered that the development effect is poor.

[0132] Optionally, the preset standard can be determined according to the actual production standard.

[0133] Calculate the mask pattern density of multiple layers where the development effect does not meet the preset standard, that is, the development effect is poor, and determine the preset threshold based on the calculated minimum mask pattern density.

[0134] It can be understood that in a feasible embodiment, the calculated minimum value can be directly used as the preset threshold. In other feasible embodiments, in order to ensure the development effect, the minimum value can be rounded down, and the rounded result can be used as the preset threshold.

[0135] In this embodiment, a total of 123 layers of development data were obtained on two test wafers, WA01 and WA02, and part of it is shown in Table 2 below:

[0136] Table 2

[0137]

[0138] In Table 2, when the development effect is qualified, that is, in the test, after developing the two test wafers using the second type of development method, the development effect meets the preset standard. It is observed that among the layers with poor development effect after using the second type of development method, the minimum value of the mask pattern density of the preset region calculated is 20.2%.

[0139] In other words, if the mask pattern density of each mask layer in the test wafer is less than 20.2% in the preset area, the second type of development method can be used directly for development; otherwise, the first type of development method, which has better development effect, needs to be used. In subsequent tests, layers with unqualified development results were changed to the first type of development method, and the development results all met the preset standards. These results are recorded as qualified modifications in Table 2.

[0140] Therefore, in this embodiment, 20.2 is rounded down to determine 20% as the preset threshold used when determining the development method for the wafer to be developed.

[0141] It should be noted that, with the mask pattern density calculation method remaining unchanged, the preset threshold of 20% determined by the above method can be used in the development method selection process for different wafers to be developed without repeated calculation. This makes it easier to select the appropriate development method for the wafers to be developed before production, achieving optimal cost while ensuring development effect.

[0142] In a specific test, dynamic development was used as the first type of development method, and static development was used as the second type of development method. The difference in development cost is shown in Table 3 below:

[0143] Table 3

[0144]

[0145] As shown in Table 3, when the wafer to be developed contains layers that require the first type of development method to be fully developed, compared to using dynamic development method for all development, the dynamic and static mixed development method based on mask pattern density requires a shorter overall development time and less developer, thus optimizing the development cost while ensuring the development effect.

[0146] The developing apparatus based on mask pattern density provided by the present invention will be described below. The developing apparatus based on mask pattern density described below can be referred to in correspondence with the developing method based on mask pattern density described above.

[0147] like Figure 2 As shown, the developing apparatus based on mask pattern density includes an acquisition module 201 and a determination module 202;

[0148] The acquisition module 201 is used to acquire the mask pattern density of several preset regions in each mask layer of the wafer to be developed, wherein the preset regions at least represent the regions with the densest pattern distribution in each mask layer;

[0149] To determine the appropriate development method for wafers before semiconductor production, in order to balance development effect and semiconductor production cost, analysis of wafers with poor development effect in historical production processes revealed that the mask pattern density of the wafer affects the development effect.

[0150] Specifically, when the mask pattern density of each layer of a wafer is higher, it is easy to have photoresist residue when using a development method with slightly lower development capability. However, for the same mask, using a development method with better development capability can ensure the uniformity of its critical dimension (CD) after development.

[0151] Based on the above findings, alternatively, the mask pattern density of each mask layer on the wafer to be developed can be calculated before semiconductor production, and a suitable development method can be determined based on the mask pattern density of the wafer to be developed.

[0152] The mask pattern density refers to the density of the mask pattern. In one feasible implementation, it can be obtained by calculating the ratio of the area of ​​the light-transmitting region of the mask to the total area of ​​the mask.

[0153] It is understood that in other feasible implementations, the density of the mask pattern can be characterized by calculating the ratio of the area of ​​the light-transmitting region of the mask to the area of ​​the opaque region of the mask, or by first calculating the ratio of the area of ​​the light-transmitting region of the mask to the total area of ​​the mask, and then multiplying it by an adjustment coefficient determined based on the semiconductor manufacturing process.

[0154] Furthermore, since the mask is relatively large and the light-transmitting area of ​​the mask is usually unevenly distributed, the development method that directly calculates the mask pattern density of the entire mask may still result in poor development effect.

[0155] Therefore, in this embodiment, several preset regions are determined in the mask of each layer of the wafer to be developed, and the mask pattern density of the preset regions is calculated to characterize the pattern density of the mask layer.

[0156] The preset region at least represents the region with the densest pattern distribution in each mask layer of the wafer to be developed, so as to better select the development method according to the mask pattern density of the fixed region, thereby better developing the wafer.

[0157] In one feasible implementation, the mask layout information of the wafer to be developed is obtained, and by observing the pattern distribution in the mask layout, several regions with relatively concentrated pattern distribution are directly selected as preset regions.

[0158] In other feasible implementations, the preset area may also include areas that require special attention during semiconductor manufacturing, such as areas where high CD accuracy is required after development, so as to take into account the mask pattern density of such areas when selecting the development method.

[0159] Optionally, the size and shape of the preset area can be determined based on the mask layout information of the wafer to be developed, or it can be determined based on experience.

[0160] Using the above method, the mask pattern density of several preset areas of the wafer to be developed can be calculated, so as to determine the development method of the wafer to be developed based on this.

[0161] The determining module 202 is used to select the first type of developing method to develop the wafer to be developed when the mask pattern density in any of the preset areas is not less than a preset threshold.

[0162] Otherwise, the second type of development method is selected to develop the wafer to be developed, wherein the development effect of the first type of development method is better than that of the second type of development method.

[0163] Optionally, the preset threshold is predefined empirically based on the calculation method of the defined mask pattern density.

[0164] Optionally, the first and second development methods are predefined based on the development methods achievable in the semiconductor manufacturing process. The first development method should have a better development effect than the second, enabling better development of wafers for which the second method is difficult to achieve optimal development. It is understood that, generally, the development cost of the first type of development method, which offers better development results, is higher than that of the second type. This development cost can be the cost of developer usage and / or the cost of development time.

[0165] In this embodiment, the first type of development method is determined to be dynamic development, and the second type of development method is determined to be static development.

[0166] Static development involves spraying developer and then immersing the wafer in it. This method uses less developer and is low-cost, but its developing ability is poor and it is prone to incomplete development. Dynamic development involves spraying developer and then rotating the wafer on the worktable to accelerate the flow of developer and fully cover the wafer surface to ensure the developing effect. This method has a better developing effect and can achieve full development, but it uses more developer and has a higher developing cost.

[0167] Based on this, if the mask pattern density in any preset area is not less than a preset threshold, it is considered that the pattern density in the mask of this layer of the wafer to be developed is relatively large, and the first type of development method with better development effect needs to be used to develop this layer.

[0168] Otherwise, if the mask pattern density of all preset areas is less than the preset threshold, it is considered that the mask pattern density of this layer of the wafer to be developed is small, and a good development effect can be achieved without using a high-cost development method. Therefore, the lower-cost second type of development method is used to develop this layer.

[0169] It should be noted that although some studies have focused on the relationship between the mask pattern density of wafers and the development effect, they have focused more on the mask pattern design process. That is, by calculating whether the critical dimensions of the wafer meet the preset production standards after development, the mask pattern design is adjusted if it does not meet the standards, so as to make the distribution of the mask pattern more uniform and thus obtain more accurate critical dimensions after development. However, the process of resetting the mask pattern is relatively cumbersome, and adjusting the mask pattern based on the critical dimensions after development also requires a longer process and testing time.

[0170] This invention calculates the mask pattern density of the wafer to be developed in a preset area and selects an appropriate development method based on the mask pattern density to achieve a balance between development effect and production cost. It ensures the development effect while achieving the lowest possible production cost. In addition, an unexpected effect is that by designing a development method selection method based on mask pattern density, the appropriate development method can be accurately selected through simple calculations before semiconductor production, ensuring product quality while achieving optimal cost.

[0171] Figure 3 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 3As shown, the electronic device may include a processor 310, a communication interface 320, a memory 330, and a communication bus 340, wherein the processor 310, the communication interface 320, and the memory 330 communicate with each other via the communication bus 340. The processor 310 can call logical instructions in the memory 330 to execute a development method based on mask pattern density. This method includes: obtaining the mask pattern density of several preset regions in each mask layer of the wafer to be developed, wherein the preset regions at least represent the regions with the densest pattern distribution in each mask layer; if the mask pattern density of any of the preset regions is not less than a preset threshold, selecting a first type of development method to develop the wafer to be developed; otherwise, selecting a second type of development method to develop the wafer to be developed, wherein the development effect of the first type of development method is better than that of the second type of development method.

[0172] Furthermore, the logical instructions in the aforementioned memory 330 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0173] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute the development method based on mask pattern density provided by the above methods. The method includes: obtaining the mask pattern density of a plurality of preset regions in each mask layer of the wafer to be developed, wherein the preset regions at least characterize the regions with the densest pattern distribution in each mask layer; if the mask pattern density of any preset region is not less than a preset threshold, developing the wafer to be developed using a first type of development method; otherwise, developing the wafer to be developed using a second type of development method, wherein the development effect of the first type of development method is better than that of the second type of development method.

[0174] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements a development method based on mask pattern density provided by the above methods. The method includes: obtaining the mask pattern density of a plurality of preset regions in each mask layer of a wafer to be developed, wherein the preset regions at least characterize the regions with the densest pattern distribution in each mask layer; if the mask pattern density of any of the preset regions is not less than a preset threshold, developing the wafer to be developed using a first type of development method; otherwise, developing the wafer to be developed using a second type of development method, wherein the development effect of the first type of development method is better than that of the second type of development method.

[0175] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0176] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0177] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A development method based on mask pattern density, characterized in that, include: Obtain the mask pattern density of several preset regions in each mask layer of the wafer to be developed, wherein the preset regions at least represent the regions with the densest pattern distribution in each mask layer; If the mask pattern density in any of the preset regions is not less than a preset threshold, the first type of development method is selected to develop the wafer to be developed. Otherwise, the second type of development method is selected to develop the wafer to be developed, wherein the development effect of the first type of development method is better than that of the second type of development method; The preset area includes a measurement area and a key area for each mask layer. The measurement area is the area on the mask used to evaluate the quality of the mask, the precision of the photolithography process, and key parameters in the chip manufacturing process. The step of obtaining the mask pattern density of several preset regions in each mask layer of the wafer to be developed specifically includes: In each mask layer of the wafer to be developed, a preliminary area with dense pattern distribution is observed and determined. Several positions are randomly selected in the preliminary area, and their coordinates are determined as key coordinates. Calculate the mask pattern density of a second preset range region centered on the key coordinates; The mask pattern density with the largest calculated value is taken as the mask pattern density of the key region; In this process, multiple preparation ranges of different sizes are predetermined, and the geometric center coordinates of the measurement area are used as the center of the preparation range. The mask pattern density of each mask layer of the wafer to be developed is calculated in each preparation range region, and the first mask pattern density sequence and the second mask pattern density sequence corresponding to each preparation range and each mask layer are obtained respectively. Multiple preparatory ranges with similar values ​​are obtained by filtering from the second mask pattern density sequence, and a first mask pattern density sequence of the filtered multiple preparatory ranges is determined. The set of the group with the smallest numerical fluctuation in the first mask pattern density sequence is determined as the first preset range, and the second preset range is the same as the first preset range.

2. The development method based on mask pattern density according to claim 1, characterized in that, The step of obtaining the mask pattern density of several preset regions in each mask layer of the wafer to be developed specifically includes: Determine the center coordinates of the measurement area of ​​each mask layer of the wafer to be developed, wherein the center coordinates of the measurement area are the coordinates of the geometric center of the measurement area of ​​each mask layer of the wafer to be developed; Calculate the mask pattern density of the first preset range region centered on the central coordinates, and use it as the mask pattern density of the measurement region.

3. The development method based on mask pattern density according to claim 1, characterized in that, The first preset range is a square area with a side length greater than or equal to 500 micrometers and less than or equal to 1000 micrometers.

4. The development method based on mask pattern density according to any one of claims 1-3, characterized in that, The mask pattern density is the ratio of the area of ​​the light-transmitting area in the preset region to the total area of ​​the preset region, multiplied by an adjustment coefficient, wherein the adjustment coefficient is the ratio of the target critical dimension of the mask to the actual critical dimension.

5. The development method based on mask pattern density according to any one of claims 1-3, characterized in that, Before the step of developing the wafer to be developed using the first type of development method when the mask pattern density in any of the preset regions is not less than a preset threshold, the method further includes: A test wafer is obtained, and multiple layers of the test wafer are developed using a second type of development method; The mask pattern density of a preset region in multiple layers whose development effect does not meet the preset standard is calculated, and the preset threshold is determined based on the minimum mask pattern density obtained from the calculation.

6. A developing apparatus based on mask pattern density, characterized in that, For implementing the development method based on mask pattern density as described in any one of claims 1 to 5, comprising: The acquisition module is used to acquire the mask pattern density of several preset regions in each mask layer of the wafer to be developed, wherein the preset regions at least represent the regions with the densest pattern distribution in each mask layer; The determination module is used to select a first type of development method to develop the wafer to be developed when the mask pattern density in any of the preset areas is not less than a preset threshold. Otherwise, the second type of development method is selected to develop the wafer to be developed, wherein the development effect of the first type of development method is better than that of the second type of development method.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the development method based on mask pattern density as described in any one of claims 1 to 5.

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