Geometric mask rule checking using favorable and unfavorable areas

Abstract

The present disclosure generally relates to geometric mask rule checking using favorable regions and unfavorable regions. A method includes: generating a diffraction pattern according to a plurality of target patterns; generating a favorable region and an unfavorable region according to the diffraction pattern; placing a plurality of sub-resolution patterns in the favorable region; and performing a plurality of geometric operations on the plurality of sub-resolution patterns to generate a modified sub-resolution pattern. The modified sub-resolution pattern extends to the favorable region and away from the unfavorable region.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductors, and more particularly, to geometric mask rule checking utilizing favorable regions and unfavorable regions. Background Art

[0002] In the formation process of the photolithography mask (which is used to form the pattern of the integrated circuit), the first-order diffraction pattern (FODM) is used to generate the seeds of the scattering pattern bar and other sub-resolution auxiliary features (SRAF). In order to pass the mask rule check (MRC) standard, the seeds can be modified by repositioning, resizing, merging or separating. This ensures that the pattern meets the manufacturability requirements of the mask making process and tools (such as minimum width, minimum space, minimum area, no sharp corners, etc.), so that the photolithography mask can be manufactured. Summary of the invention

[0003] According to one embodiment of the present disclosure, a method for forming sub-resolution auxiliary features is provided, comprising: generating a diffraction pattern according to a target pattern, wherein the diffraction pattern comprises a bright pattern and a dark pattern; generating a favorable area and an unfavorable area according to the bright pattern and the dark pattern; placing a first plurality of sub-resolution patterns in the favorable area; performing operations that comply with mask rules on the first plurality of sub-resolution patterns to generate a second plurality of sub-resolution patterns, wherein a first group of sub-resolution patterns in the first plurality of sub-resolution patterns is magnified; performing an unfavorable area inspection process to find unfavorable patterns, wherein the unfavorable patterns are the magnified first group of sub-resolution patterns extending into the unfavorable area; and performing geometric operations on the second plurality of sub-resolution patterns to generate a third plurality of sub-resolution patterns, wherein the unfavorable patterns are separated from the unfavorable area.

[0004] According to another embodiment of the present disclosure, a method for forming a sub-resolution auxiliary feature is provided, comprising: generating a diffraction pattern based on a plurality of target patterns; generating a favorable region and an unfavorable region based on the diffraction pattern; placing a plurality of sub-resolution patterns in the favorable region; and performing a plurality of geometric operations on the plurality of sub-resolution patterns to generate a modified sub-resolution pattern, wherein the modified sub-resolution pattern extends into the favorable region and away from the unfavorable region.

[0005] According to another embodiment of the present disclosure, a method for forming a sub-resolution auxiliary feature is provided, comprising: generating an unfavorable region and a scattering pattern; determining whether the scattering pattern overlaps with the unfavorable region; modifying the scattering pattern to generate a modified scattering pattern, wherein the modified scattering pattern is separated from the unfavorable region; forming a photolithography mask including the modified scattering pattern; and performing an exposure process on a photoresist using the photolithography mask. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] When read in conjunction with the accompanying drawings, various aspects of the present disclosure can be best understood from the following detailed description. It is worth noting that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the sizes of various features may be arbitrarily increased or reduced for clarity of discussion.

[0007] Figures 1 to 8 An intermediate stage in generating a pattern for a photolithography mask is shown in accordance with some embodiments.

[0008] Figures 9 to 12 A cross-sectional view is shown of intermediate stages in forming some patterns on an integrated circuit component in accordance with some embodiments.

[0009] Fig.13 A process flow for forming a photolithography mask according to some embodiments is shown. DETAILED DESCRIPTION

[0010] The following disclosure provides many different embodiments or examples for implementing the different features of the present invention. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are just examples and are not intended to be limiting. For example, in the following description, forming a first feature on or on a second feature may include an embodiment in which the first feature and the second feature are formed in direct contact, and may also include an embodiment in which additional features may be formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. In addition, the present disclosure may repeat reference numerals and / or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0011] Additionally, spatially relative terms (e.g., "below," "beneath," "below," "above," "upper," etc.) may be used herein to facilitate describing the relationship of one element or feature illustrated in the figures relative to another element(s) or feature(s). Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0012] A method for forming a sub-resolution assist feature (SRAF) (also known as a scattering strip) is provided. The method includes: arranging a target pattern to be implemented on a wafer; generating a diffraction pattern according to the target pattern; determining a favorable area and an unfavorable area according to the diffraction pattern; generating an initial pattern (seed) in the favorable area; and enlarging the initial pattern so that the enlarged pattern can pass the minimum width or / and minimum area constraint checked by the mask rule. Since enlargement may cause degradation of optical performance, it is necessary to perform a pattern modification process to modify the pattern so that the resulting pattern no longer extends into the unfavorable area. By keeping the pattern separated from the unfavorable area, the modified pattern produces better optical performance and the target pattern can be better implemented on the photoresist. The purpose of the embodiments discussed herein is to provide the following examples for enabling the subject matter of the present disclosure to be made or used, and a person of ordinary skill in the art will easily understand the modifications that can be made while remaining within the intended scope of the different embodiments. In the various views and illustrative embodiments, the same figure numbers are used to represent the same elements. Although the method embodiments may be discussed as being performed in a particular order, other method embodiments may be performed in any logical order.

[0013] Figures 1 to 8 1 shows an intermediate stage of generating a pattern of a photolithography mask according to some embodiments of the present disclosure. The corresponding process is also schematically reflected in Fig.13 In the process flow 200 shown.

[0014] refer to Figure 1 , generate / layout the target pattern 20. The corresponding process is Fig.13 The process flow 200 is shown as process 202. Throughout the specification, the term "target pattern" refers to a pattern of target features to be implemented on an integrated circuit component, including but not limited to a device wafer, an interposer wafer, a package substrate, and a reconstructed wafer. The target feature can be any feature to be formed, including but not limited to a dielectric region, a semiconductor region, or a metal region. In addition, the target pattern can be formed on an etch mask such as a photoresist, and then the target pattern on the etch mask can be transferred to the integrated circuit component.

[0015] In order to realize a pattern on an integrated circuit component, a target pattern is formed on a photolithography mask, e.g. Fig. 9 and Fig.1040 is shown in FIG. The photolithography mask includes a transparent portion and an opaque portion, wherein either the transparent portion or the opaque portion includes a target pattern. The photolithography mask is used in a photolithography process, wherein a light beam is projected onto the photolithography mask, thereby exposing the underlying photosensitive material (e.g., photoresist). After exposure and subsequent development processes, the target pattern is transferred to the photosensitive material, which can then be used as an etching mask to form target features on an integrated circuit component.

[0016] Due to optical effects, especially as integrated circuits become smaller and smaller, it may not be possible to accurately realize the target features on the integrated circuit components. For example, the shape, size, spacing, etc. may be distorted. Sub-resolution assist features (SRAFs) can be used to help realize the target features on the integrated circuit components more accurately. SRAFs are formed on the photolithography mask and their size is smaller than the resolution of the corresponding photolithography tools and processes. For example, when a 193nm beam is used for exposure (numerical aperture (NA) equal to 0.9 and combined with appropriate illumination shapes), the minimum resolution may have a spacing equal to 107nm and a width equal to about 40nm, and at least one of the length and width is less than about 20nm. Features are sub-resolution features. Although sub-resolution assist features are formed on the photolithography mask, the photoresist obtained after development will not have these patterns. On the other hand, with the help of sub-resolution assist features, the target pattern will be formed on the photoresist with better accuracy. In other words, although the sub-resolution assist features are not on the photoresist, the pattern in the photoresist is closer to the pattern on the photolithography mask due to the help of sub-resolution assist features.

[0017] Reference again Figure 1 , two example target patterns 20 having a square shape are shown as examples. However, in an actual circuit, the pattern may have any shape, including but not limited to a rectangle, a hexagon, an octagon, a circle, an ellipse, etc., or a combination of these shapes. There may also be a much greater number of target patterns in the circuit. However, a simple target pattern may be used to explain the concept of the embodiment.

[0018] When a target pattern 20 is provided, a diffraction map is generated according to a specific illumination shape for the photolithography process. Fig.13 This is shown as process 204 in the illustrated process flow 200. Figure 2 2 shows a portion of an example diffraction pattern 22. Diffraction pattern 22 includes a unique pattern of light and dark stripes, rings, etc. formed due to diffraction from target pattern 20. For example, if a hole is formed in an opaque plate, and the hole has the shape and size of the target pattern, when a light beam (having a specific wavelength) is projected onto the opaque plate, diffraction pattern 22 may be formed on another plate behind the opaque plate.

[0019] According to some embodiments of the present disclosure, the diffraction pattern 22 is generated by simulation, for example, using a computer with software configured to simulate the diffraction pattern. Depending on the requirements, the simulation may have different levels of accuracy. A more accurate simulation takes longer to complete, and the resulting simulated refraction map is closer to the actual diffraction map (e.g., the diffraction map obtained by the hole on the opaque plate). According to some embodiments, the simulation may be a first-order simulation with relatively low accuracy but requiring a shorter time to complete. The first-order diffraction map obtained still has a certain difference from the actual diffraction map, but it is still accurate enough for implementing the embodiments of the present disclosure. If a first-order simulation is performed, the resulting diffraction map may therefore be referred to as a first-order diffraction map (first-order Diffraction Map, FODM). According to other embodiments, the diffraction map may be generated with a higher order of accuracy, and therefore it may be a second-order diffraction map or a third-order diffraction map, etc. According to other embodiments, the diffraction map may be obtained by other methods, such as forming an actual pattern on an opaque plate, and projecting a light beam on the opaque plate to directly obtain the diffraction map. All of these methods for generating diffraction patterns are within the scope of the present disclosure.

[0020] like Figure 2 As shown, the diffraction pattern 22 includes a bright pattern 24, and the bright pattern 24 includes bright patterns 24A, 24B and 24C and more bright patterns not shown. Bright pattern 24A is a pattern in which the target pattern 22 is distorted due to optical effects, and the embodiments of the present disclosure are to correct the distortion. Bright patterns 24B and 24C are interference patterns. There may be more bright patterns outside the bright pattern 24C. From the internal bright pattern 24A to the external bright patterns 24B and 24C, the brightness gradually decreases. However, the pattern outside the bright pattern 24C may be too dark to be distinguished. In addition, the external bright pattern is closer to other adjacent patterns (not shown) and may be affected by the bright patterns of the adjacent patterns. Therefore, according to some embodiments, the embodiments of the present disclosure may adopt bright patterns 24A and 24B (sometimes bright patterns 24A, 24B and 24C may be adopted), and according to some embodiments of the present disclosure, the remaining external bright patterns are ignored.

[0021] The diffraction pattern 22 also includes dark patterns 26, which include dark patterns 26A, 26B, 26C, etc. between the bright patterns 24. It can be understood that although Figure 2 It is shown that there is a clear boundary between the bright pattern 24 and the dark pattern 26, but Figure 2 It is schematic, and in an actual diffraction pattern, the middle portion of the bright pattern 24 is brightest, and the middle portion of the dark pattern 26 is darkest. The transition from the bright pattern 24 to the dark pattern 26 is gradual, with no clear boundary therebetween.

[0022] Figure 3 The generation of a region map 32 including (one or more) favorable regions 30 and unfavorable regions 28 (including 28A and 28B) according to some embodiments is shown. Fig.13 The process flow 200 is shown as process 206. It is understood that although one favorable region 30 and two unfavorable regions 28 are shown as an example, the total number of favorable regions 30 can be any number equal to or greater than one, and the total number of unfavorable regions 28 can be any number equal to or greater than one. The favorable region 30 is based on the bright pattern 24 ( Figure 2 ) and may include portions of the bright pattern 24 where the brightness value exceeds a first predetermined brightness value (discussed in subsequent paragraphs). The unfavorable region 28 is based on the dark pattern 26 ( Figure 2 ) and may include a portion of the dark pattern 26 having a brightness value lower than a second predetermined brightness value (discussed in subsequent paragraphs).

[0023] The favorable regions 30 are preferred regions for placing subsequently formed subthreshold assist features, and forming subthreshold assist features in these regions facilitates the formation of target features and reduces undesirable optical effects. The unfavorable regions 28 are regions where placing subsequently formed subthreshold assist features in these regions would worsen undesirable optical effects. Therefore, the unfavorable regions 28 are also prohibited regions where formation of subthreshold assist features is prohibited.

[0024] According to some embodiments, the determination / generation of the favorable region 30 and the unfavorable region 28 is based on absolute (threshold) brightness values. For example, two brightness values ​​B1 and B2 may be predetermined, wherein the brightness value B2 is greater than or equal to the brightness value B1. When the brightness values ​​of certain positions of the diffraction pattern 22 are lower than the brightness value B1, these corresponding positions belong to the unfavorable region 28. When the brightness values ​​of certain positions of the diffraction pattern 22 are higher than the brightness value B2, these corresponding positions belong to the favorable region 30. According to some embodiments, the brightness value B1 is lower than the brightness value B2. In the resulting region map, the favorable region 30 is spaced apart from the adjacent unfavorable region 28, such as Figure 3 The difference (B2-B1) determines the spacing between adjacent favorable regions 30 and unfavorable regions 28 (e.g. Figure 3 The spacings S1 and S2 in the image are determined by the brightness values ​​B1 and B2, respectively, and the widths of the unfavorable region 28 and the favorable region 30 (e.g. Figure 3 According to an alternative embodiment, the values ​​B1 and B2 are equal to each other. Therefore, the favorable area 30 touches the corresponding adjacent unfavorable area 28. The brightness value B1 is generally set to be no greater than the brightness value B2 to avoid ambiguity when a certain position belongs to the unfavorable area 28 or the favorable area 30.

[0025] According to an alternative embodiment, the determination of the favorable region 30 and the unfavorable region 28 is based on relative brightness values. It is understood that there may be a variety of methods for determining the relative brightness values, which are within the scope of the present disclosure. The relative brightness value may be determined based on the highest brightness value of the bright pattern, or based on both the highest brightness value of (one or more) bright patterns and the lowest brightness value of (one or more) dark patterns. According to some example embodiments, the brightness value BBrig of the brightest point of the bright pattern 24 is used as a criterion for generating the favorable region 30 and the unfavorable region 28. (Threshold) relative brightness values ​​F1 and F2 are also predetermined, wherein the relative brightness values ​​F1 and F2 are both between 0 and 1, but not including 0 and 1. According to some embodiments, when the brightness values ​​of certain positions of the diffraction pattern 22 are lower than F1*BBrig, these corresponding positions are in the unfavorable region 28. Conversely, when the brightness values ​​of certain positions of the diffraction pattern 22 are higher than F2*BBrig, these corresponding positions are in the favorable region 30. According to some embodiments, the relative brightness value F1 is lower than the relative brightness value F2. The difference (B2-B1) determines the spacing between adjacent favorable regions 30 and unfavorable regions 28 (e.g. Figure 3 The relative brightness values ​​F1 and F2 determine the widths of the unfavorable region 28 and the favorable region 30, respectively (e.g. Figure 3 According to an alternative embodiment, the relative brightness values ​​F1 and F2 are equal to each other. Accordingly, the favorable area 30 contacts the corresponding adjacent unfavorable area 28. The relative brightness value F1 is generally set to be no greater than the relative brightness value F2 to avoid ambiguity when a certain position belongs to the unfavorable area 28 or the favorable area 30.

[0026] refer to Figure 4 , the target pattern 20 and the initial sub-resolution assist feature (SRAF) 34 are added to the area map 32. The corresponding process Fig.13The process flow 200 shown is shown as process 208. The initial SRAF 34 is also a pattern that is intended to be formed on the lithography mask together with the target pattern 20. In the subsequent discussion, the initial SRAF 34 is referred to as a scattering bar because they are generally formed in a bar shape. The length and / or width of the initial scattering bar 34 is less than the resolution of the lithography tool and process (so the initial scattering bar 34 is a sub-resolution feature). Therefore, the scattering bar 34 (even after subsequent modification) will not be transferred to the resulting integrated circuit component (e.g., wafer, package, package substrate, etc.). In comparison, the target features 20 have a lateral dimension greater than the resolution, and therefore their pattern will be transferred to the resulting integrated circuit component. Although the pattern of the initial scattering bars 34 is not transferred, their presence on the lithography mask affects the optical effect in the exposure process, and the transferred pattern on the integrated circuit component is closer in shape and size to the target pattern 20 on the lithography mask.

[0027] In the subsequent discussion, reference numeral 34 is used to denote both the initial scattering strips and the scattering strips after the modification process. The letters "M" and "MM" may also be added after reference numeral "34" to identify the stage of modification.

[0028] When the initial scattering strip 34 is in the bright pattern 24 ( Figure 2 ), the initial scattering strips 34 have a beneficial effect on the transfer of the target pattern 20. Therefore, the initial scattering strips 34 are added to the favorable area 30 ( Figure 4 ), the favorable area 30 is determined based on the brightness of the bright pattern 24. According to some embodiments, the initial scattering bars 34 are rectangular bars, and some of the initial scattering bars 34 may be square bars. According to alternative embodiments, the initial scattering bars 34 may have any other shape, including but not limited to polygons (e.g., hexagons or octagons, etc.), circles, or ellipses, etc. The initial scattering bars 34 may also have irregular shapes, including combinations of curves and / or straight lines, etc. In addition, one initial scattering bar 34 may be different from or the same as another initial scattering bar 34 in terms of shape, width, length, etc.

[0029] According to some embodiments, all of the initial scattering bars 34 are completely within the favorable region 30. According to alternative embodiments, some of the initial scattering bars 34 may extend slightly out of the favorable region 30, and no scattering bars 34 extend into the unfavorable region 28. The scattering bars 34 may be placed to fit the shape and extension direction of the corresponding portion of the favorable region 30. Thus, the length direction of some of the initial scattering bars 34 may be in the X direction, while the length direction of some other scattering bars 34 may be in the Y direction.

[0030] Next, a first mask rule check is performed on the pattern to be formed into the photolithography mask. Fig.13 The process flow 200 shown is shown as process 210. The first mask rule check is based on geometry and can therefore be performed in a short time. The first mask rule check ensures that the manufacturing tool used to form the lithography mask is able to form the scattering bars 34 and the target pattern 20 on the lithography mask. For example, a pattern that is too small, too close to each other, or too small in area cannot be successfully formed on the lithography mask. Therefore, the mask rule check checks the pattern including the initial scattering bars 34 and the target pattern 20 to ensure that all mask rules are followed. Since the initial scattering bars 34 are formed as sub-resolution features, some of the initial scattering bars 34 may violate the mask rules and therefore fail to pass the mask rule check. The scattering bars 34 that fail to pass the mask rule check are hereinafter referred to as scattering bars that violate the mask rules. Figure 4 Some examples of scatter bars 34 that violate the mask rules are shown and are labeled using the symbol 34F. The scatter bars 34F that violate the mask rules are also numbered by adding a number after the letter "F" to distinguish them from each other.

[0031] Figure 5 FIG. 1 shows a first scattering strip modification process (also referred to as a mask rule compliance operation), in which the scattering strips 34F that violate the mask rule are enlarged to form modified scattering strips 34M (including 34M1 to 34M6), so that the modified scattering strips 34M can pass the mask rule inspection. The corresponding process is Fig.13 This is shown as process 212 in the illustrated process flow 200. Although enlargement is used as an example of an operation that complies with mask rules, operations that comply with mask rules may also include repositioning and / or merging. Figure 5 All scatter bars 34 in the image are identified by the letter "M" to distinguish them from the Figure 4 The initial scatter bars in the image are distinguished, regardless of whether these scatter bars are relative to Figure 4 The scattering strips shown in FIG. 3 are modified. The first scattering strip modification process is based on geometry. The modification may include enlarging the initial scattering strips 34 in the X direction, the Y direction, or both the X direction and the Y direction. The modification may also include replacing the small scattering strips 34 with larger scattering strips 34. Figure 5 An example modification process is shown in which the scattering bars 34F that violate the mask rules extend in the +X and -X directions, although they may also extend in the +Y direction and / or the -Y direction. In addition, the scattering bars 34F that violate the mask rules may also be relocated, for example, when the failure to pass the mask rule check is due to too small a spacing between the scattering bars 34F that violate the mask rules. The scattering bar modification process may be performed by software executed in a computer.

[0032] The scattering strip modification process is performed to pass the mask rule check without considering the effect of the scattering strip modification process on the optical performance. The effect of the modified scattering strip 34M on the optical performance can be determined by simulation. However, the simulation takes a long time to complete, especially when simulating a large integrated circuit component with a complex pattern. According to some embodiments of the present disclosure, the unfavorable region 28 is used to at least limit the adverse effect of the scattering strip modification process on the optical performance, or significantly improve the optical performance.

[0033] Figure 5 Some examples of modified scattering bars 34M are shown. For example, modified scattering bars 34M1, 34M2, 34M3, 34M4, and 34M6 extend into (and overlap) unfavorable region 28A, and modified scattering bar 34M5 extends into (and overlaps) unfavorable region 28B. After the first scattering bar modification process, there may also be some modified scattering bars 34M that do not extend into unfavorable regions 28A and 28B.

[0034] Since the unfavorable region 28 is determined to be included in the dark pattern 26 in the diffraction pattern, when the modified scattering strip 34M extends into the unfavorable region 28, the optical performance may be adversely affected. Therefore, the unfavorable region inspection process is performed to identify the scattering strip 34M extending into the unfavorable region 28. The corresponding process is Fig.13 This is shown as process 214 in the illustrated process flow 200. The identified scattering strips 34M extending into the undesirable region 28 are referred to as undesirable patterns or undesirable scattering strips.

[0035] When one or more modified scattering strips 34M are identified as unfavorable scattering strips, a second scattering strip modification process is performed to modify the unfavorable scattering strips again and keep the resulting scattering strips 34 outside the unfavorable region 28. Fig.13 This is shown as process 216 in the illustrated process flow 200 .

[0036] It should be understood that the unfavorable area inspection process 214 is a geometric inspection process that can be performed quickly. In comparison, if the optical performance of the modified scattering strip 34M is determined by simulation, the simulation will take a long time. Therefore, the optical performance determination process according to the embodiment of the present disclosure is much more efficient.

[0037] The second scattering strip modification process may include multiple geometry-based operations, including but not limited to shrinking, repositioning, merging, removing, etc., and / or combinations thereof. The resulting modified scattering strips are referred to as 34MM, which include 34MM1 to 34MM5. Figure 6 All scattered bars in the are marked as including "MM" to distinguish them from Figure 5 , regardless of whether these scatter bars are relative to Figure 5 The scatter bars shown in have been modified.

[0038] According to some embodiments, the modified scattering strip 34M1 ( Figure 5 ) extends into the unfavorable region 28A, and shrinks in a direction away from the unfavorable region 28A in the second scattering strip modification process. The modified scattering strip 34MM1 ( Figure 6 ) no longer extends into the unfavorable region 28A. The modified scattering strips 34M2 and 34M3 ( Figure 5 ) also extends into the unfavorable region 28A and shrinks in the direction away from the unfavorable region 28A. The modified scattering strips 34MM2 and 34MM3 ( Figure 6 ) no longer extends into the unfavorable region 28A. The modified scattering strip 34M4 ( Figure 5 ) extends into the unfavorable region 28A and merges with the scattering strip 34M7 (which may violate the mask rule or comply with the mask rule) to form a new modified scattering strip 34MM8 ( Figure 6 ). According to some embodiments, the merging can be achieved by resizing (enlarging or reducing) and / or repositioning one or both of the merged scattering strips 34M4 and 34M7. The merging results in a larger merged size, and thus the merged pattern can pass the minimum area constraint of the mask rule check. Modified scattering strip 34M5 ( Figure 5 ) extends into the unfavorable region 28B, and it shrinks in the direction away from the unfavorable region 28B. The modified scattering strip 34MM5 ( Figure 6 ) no longer extends into the unfavorable region 28B. The modified scattering strip 34M6 ( Figure 5 ) extends into the unfavorable area 28A and is removed. Figure 6 Dashed lines are used to show where the removed scattering strip 34M6 is.

[0039] According to some embodiments, the second scattering strip modification process may or may not be performed with consideration of mask rules. For example, shrinking may be performed so that the resulting shrunken scattering strips 34M1 and 34M2 are still large enough for the minimum width and / or minimum area constraints that pass the mask rule check. According to some embodiments, the modification is based on certain predetermined rules, such as shrinking to a certain percentage of the original length (e.g., between about 70% and about 90%). According to these embodiments, the resulting modified scattering strips 34MM may or may not pass the mask rule check, and may require further mask rule checks, adverse area checks, and corresponding modification processes.

[0040] As a result of the second scattering strip modification process, a portion or all of the modified scattering strips 34MM1 may be completely within the favorable region 30. According to an alternative embodiment, some of the modified scattering strips 34MM are completely within the favorable region 30, while some other scattering strips 34MM (e.g., 34MM2 and 34MM3) are partially inside the favorable region 30 and partially outside the favorable region 30. However, these scattering strips 34MM are outside the unfavorable region 28.

[0041] refer to Fig.13 In the process flow 200 shown, a rework process may be performed. The rework process may include processes 218 to 224, and if the process loops back to processes 212 and 214, it may also include processes 212 and 214. The rework process is discussed below.

[0042] According to some embodiments, after the second scattering strip modification process 216, a second mask rule check process may be performed to ensure that the twice modified scattering strips do not violate the mask rules. Fig.13 This is shown as process 218 in the process flow 200 shown. For example, the reduction of the scattering strips may cause the scattering strips 34MM to be too small again. If the second mask rule check is passed without the scattering strips 34MM failing, as shown in process 220 in process flow 200, the process flow can proceed to Fig.13 Otherwise, the process loops back to Fig.13 The process flow 200 shown in FIG. 21 is followed by process 212 , and another scattering stripe enlargement process 212 , a subsequent unfavorable area inspection process 214 , a scattering stripe modification process 216 , and so on are performed again.

[0043] According to some embodiments, after the second scattering strip modification process, a second unfavorable region inspection process 222 may be performed to ensure that the scattering strips modified twice will not fall into the unfavorable region again. Fig.13 This is shown as process 222 in the illustrated process flow 200. For example, when relocating the scattering bars away from the unfavorable area 28A, the scattering bars may extend into the unfavorable area 28B. The scattering bars that fall into the unfavorable area again will be marked and modified again. As shown in process 224, if all scattering bars 34 pass the second unfavorable area inspection process 222, the pattern generated in the previous process can be used to form a photolithography mask. Otherwise, if one or more scattering bars 34 fail to pass the second unfavorable area inspection process 222, the process loops back to Fig.13 The process flow 200 shown in FIG. 216 is followed by another scattering stripe modification process and subsequent processes.

[0044] Figure 7 and Figure 8Scattering strips in a rework process are shown as an example. Figure 7 In the modified scattering strip 34MM3, the modified scattering strip 34MM3 extends into the unfavorable area 28B. Therefore, another modification process is performed to shrink the scattering strip 34MM3 and generate a scattering strip 34MM3', such as Figure 8 shown.

[0045] It should be understood that if the previous process is not performed correctly, the rework process may be performed endlessly. For example, repositioning the scattering strip away from the unfavorable area 28A causes it to extend into the unfavorable area 28B, and repositioning during rework may cause it to extend back into the unfavorable area 28A again. To prevent this from happening, some factors may be considered in the scattering strip modification process during rework. For example, assuming that the previously modified scattering strip still fails the unfavorable area inspection process 224, in the resulting re-execution of the scattering strip modification process 216, a new modification operation different from the previous modification operation will be performed. For example, if the previous modification operation is a reduction operation, the newly performed modification operation can be a reposition or a merge, etc. Alternatively, the same operation can be performed but with different parameters. For example, the reduction rate can be changed from 20% to 15%, or the reduction value can be changed from 2.0nm to 1.5nm. This can prevent cyclic operations. According to some embodiments, a predetermined number of reworks (e.g., 1, 2, or 3, or more times) may be allowed to be performed, where the operations in these reworks are different from the previous operations. If there are still (one or more) scattering bars 34 that fail the adverse area inspection process and / or the mask rule inspection process after reaching the predetermined number, these scattering bars will be removed to end the cycle, or marked and reported as errors for further processing.

[0046] According to some embodiments, if one or more previously modified scattering strips still fail the mask rule check process 220 or the adverse area check process 224, the failed scattering strips are removed to prevent further rework and prevent cyclic rework without further attempts, or may be marked and reported as errors for further handling.

[0047] In the above process, a two-step scattering bar modification process is performed, including enlarging scattering bars 34, and then performing a modification process so that the resulting modified scattering bars 34 are kept outside the unfavorable region. According to an alternative embodiment, a one-step scattering bar modification process is performed, wherein the unfavorable region 28 is taken into account in the enlargement of the scattering bars that violate the mask rules, and the enlargement is in a selected direction away from the nearest unfavorable region 28. The enlargement ratio in the selected direction is also controlled so that the resulting enlarged scattering bars do not extend into the unfavorable region 28. A subsequent mask rule check may be performed or may be skipped. A subsequent unfavorable region check is no longer required.

[0048] According to some embodiments, as shown in reference Figures 1 to 8 As discussed, the pattern generation process includes generating a diffraction pattern including both unfavorable regions 28A and 28B, and performing a rework process. It should be understood that unfavorable region 28A has a greater impact on optical performance than unfavorable region 28B. This means that the adverse effect of the scattering strip on the optical performance extending into the unfavorable region 28B is less than the adverse effect extending into the unfavorable region 28A. Therefore, according to some embodiments, in order to improve the efficiency of pattern generation, unfavorable region 28A is generated, and unfavorable region 28B is not generated, to compromise efficiency and accuracy. According to these embodiments, rework may or may not be performed. According to alternative embodiments, both unfavorable regions 28A and 28B are generated, and the rework process is not performed. Alternatively, after a certain number of rework iterations (e.g., 5 times), the scattering strips will be marked and reported as errors for further processing.

[0049] Then use the target pattern 20 and the scattering pattern 34MM ( Figure 6 or Figure 8 ) to form Fig. 9 and Fig.10 The photolithography mask 40 is shown. It should be understood that a photolithography mask different from that shown may be used. For example, an extreme ultraviolet (EUV) mask may be used. The corresponding process is Fig.13 This is shown as process 226 in the illustrated process flow 200 . Fig. 9 A top view of a portion of a photolithography mask 40 is shown, in which scattering strips 34MM (also scattering patterns 34) and a target pattern 20 are formed. The favorable region 30 and the unfavorable region are used to assist in the generation of the scattering strips 34, and the favorable region 30 and the unfavorable region are not formed in the photolithography mask 40.

[0050] Figures 10 to 12 FIG. 4 is a cross-sectional view of an intermediate stage in the transfer of a pattern in a photolithography mask 40 into an integrated circuit component 44 in accordance with some embodiments. Fig.10 , the photolithography mask 40 includes an opaque portion and a transparent portion. According to some embodiments, the target pattern 20 and the scattering strips 34 are formed as opaque portions, which are located between the transparent portions 36, such as Fig.10 According to an alternative embodiment, the target pattern 20 and the scattering strips 34 may be formed as transparent portions of a photolithography mask, wherein opaque portions separate them from each other. Fig.10 Shows Fig. 9 Reference section 10–10 in.

[0051] An integrated circuit component 44 is placed under the photolithography mask 40. The integrated circuit component 44 may be a device wafer, an interposer wafer, a package substrate strip, or a reconstructed wafer, etc. The integrated circuit component 44 includes a target layer 46, which may be a dielectric layer, a semiconductor layer, or a conductive layer (e.g., a metal layer), etc. A photoresist 48 is applied over the target layer 46. Light 50 is projected onto the photolithography mask 40, thereby exposing the photoresist 48.

[0052] After the photoresist 48 is exposed, the photolithography mask 40 is removed. The photoresist 48 is baked and developed, and some portions are removed. The resulting photoresist 48 includes the pattern of the target pattern 20, but does not include the pattern of the scattering pattern 34, such as Fig.11 In a subsequent process, the photoresist 48 is used to etch the target layer 46 below. The resulting etch target layer 46 again includes the pattern of the target pattern 20 but does not include the pattern of the scattering pattern 34. The photoresist 48 is then removed and Fig.12 In the process discussed above, the scattering pattern 34 enables the target pattern 20 to be more accurately transferred into the target layer 46 , but the scattering pattern 34 is not formed in the target layer 46 .

[0053] In the processes discussed above, a computer with software (programming code) and hardware may be used to perform Figures 1 to 8 The software includes tools for performing tasks including, but not limited to, generating (laying out) a target pattern, simulating a diffraction pattern, generating favorable and unfavorable regions, generating an initial scattering pattern, performing a mask rule check, amplifying a scattering pattern, performing an unfavorable region check, and modifying a scattering region. The program code of the software and results such as diffraction patterns, favorable and unfavorable regions, target patterns, and scattering patterns can be embodied on a non-transitory storage medium (e.g., a hard disk or disk, etc.) and can be transported for manufacturing a photolithography mask.

[0054] In the above embodiments, the above advanced lithography processes, methods and materials can be used in many applications, including fin field effect transistors (FinFETs). For example, fins can be patterned to produce relatively tight spacing between features, and the above disclosure is well suited for these spacings. In addition, spacers (also known as mandrels) used to form fins of FinFETs can be processed according to the above disclosure.

[0055] Embodiments of the present disclosure have several advantageous features. By generating favorable and unfavorable regions, scattering strips are generated and separated from unfavorable regions. The optical effect is thus optimized. The optimization of the optical effect is done very quickly by geometrically checking the scattering strips to determine whether they extend into unfavorable regions. This saves time that would otherwise be spent performing time-consuming simulations to determine the optical effect of the scattering strips.

[0056] According to some embodiments of the present disclosure, a method includes: generating a diffraction pattern according to a target pattern, wherein the diffraction pattern includes a bright pattern and a dark pattern; generating a favorable area and an unfavorable area according to the bright pattern and the dark pattern; placing a first plurality of sub-resolution patterns in the favorable area; performing an operation (which may be an enlargement operation, a repositioning operation, or a merging operation) that complies with mask rules on the first plurality of sub-resolution patterns to generate a second plurality of sub-resolution patterns, wherein a first group of sub-resolution patterns in the first plurality of sub-resolution patterns is enlarged; performing an unfavorable area inspection process to find unfavorable patterns, wherein the unfavorable patterns are the enlarged first group of sub-resolution patterns extending into the unfavorable area; and performing a geometric operation on the second plurality of sub-resolution patterns to generate a third plurality of sub-resolution patterns, wherein the unfavorable patterns are separated from the unfavorable area. In one embodiment, the method further includes a mask rule inspection process, wherein the mask rule inspection process is used to find the first group of sub-resolution patterns from the first plurality of sub-resolution patterns, wherein the first group of sub-resolution patterns are patterns that violate mask rules. In one embodiment, the first plurality of sub-resolution patterns also includes a second group of sub-resolution patterns that comply with mask rules, and in the enlargement operation, the second group of sub-resolution patterns are not modified. In one embodiment, the geometric operation includes shrinking one of the unfavorable patterns. In one embodiment, the geometric operation includes repositioning one of the unfavorable patterns. In one embodiment, the geometric operation includes removing one of the unfavorable patterns. In one embodiment, the geometric operation includes merging one of the unfavorable patterns with another pattern of the plurality of sub-resolution patterns. In one embodiment, the method further includes: manufacturing a photolithography mask, wherein the target pattern and the third plurality of sub-resolution patterns are formed in the photolithography mask; and using the photolithography mask to form an integrated circuit component, wherein the target pattern is implemented on the integrated circuit component and the third plurality of sub-resolution patterns are not implemented on the integrated circuit component. In one embodiment, the method further includes: performing a mask rule check process on the third plurality of sub-resolution patterns. In one embodiment, the method further includes: amplifying additional scattering strips that violate mask rules in the third plurality of sub-resolution patterns to generate a fourth plurality of sub-resolution patterns. In one embodiment, the method further includes: performing additional unfavorable area checks on the fourth plurality of sub-resolution patterns.

[0057] According to some embodiments of the present disclosure, a method includes: generating a diffraction pattern according to a plurality of target patterns; generating a favorable region and an unfavorable region according to the diffraction pattern; placing a plurality of sub-resolution patterns in the favorable region; and performing a plurality of geometric operations on the plurality of sub-resolution patterns to generate a modified sub-resolution pattern, wherein the modified sub-resolution pattern extends into the favorable region and away from the unfavorable region. In one embodiment, the diffraction pattern includes a bright region and a dark region, and the favorable region includes a portion of the bright region, and the unfavorable region includes a portion of the dark region. In one embodiment, the method further includes determining a first brightness threshold and a second brightness threshold that is equal to or higher than the first brightness threshold, wherein a region in the diffraction pattern with a brightness value lower than the first brightness threshold is in the unfavorable region, and wherein a region in the diffraction pattern with a brightness value higher than the second brightness threshold is in the favorable region. In one embodiment, the plurality of geometric operations include: an amplification operation for amplifying some of the plurality of sub-resolution patterns and generating an amplified pattern; and an additional geometric operation for separating the amplified pattern from the unfavorable region. In one embodiment, the method further comprises performing a mask rule checking process for finding scattering strips violating mask rules in the plurality of sub-resolution patterns that have undergone some of the plurality of geometric operations. In one embodiment, the method further comprises an unfavorable region checking process for finding an unfavorable pattern in the plurality of sub-resolution patterns, wherein the unfavorable pattern extends into the unfavorable region.

[0058] According to some embodiments of the present disclosure, a method includes: generating an unfavorable area and a scattering pattern; determining whether the scattering pattern overlaps with the unfavorable area; modifying the scattering pattern to generate a modified scattering pattern, wherein the modified scattering pattern is separated from the unfavorable area; forming a photolithography mask including the modified scattering pattern; and performing an exposure process on a photoresist using the photolithography mask. In one embodiment, the method also includes: generating a diffraction pattern based on a target pattern, wherein the target pattern is also in the photolithography mask; and determining the unfavorable area and the favorable area based on the diffraction pattern, wherein the scattering pattern is placed in the favorable area. In one embodiment, modifying the scattering pattern includes amplifying the scattering pattern.

[0059] The features of several embodiments are summarized above so that those skilled in the art can better understand various aspects of the present disclosure. It should be appreciated by those skilled in the art that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or advantages as the embodiments introduced herein. It should also be recognized by those skilled in the art that these equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions and modifications without departing from the spirit and scope of the present disclosure.

[0060] Example 1 is a method for forming sub-resolution auxiliary features, comprising: generating a diffraction pattern according to a target pattern, wherein the diffraction pattern includes a bright pattern and a dark pattern; generating a favorable area and an unfavorable area according to the bright pattern and the dark pattern; placing a first plurality of sub-resolution patterns in the favorable area; performing an operation that complies with a mask rule on the first plurality of sub-resolution patterns to generate a second plurality of sub-resolution patterns, wherein a first group of sub-resolution patterns in the first plurality of sub-resolution patterns is magnified; performing an unfavorable area inspection process to find an unfavorable pattern, wherein the unfavorable pattern is an enlarged first group of sub-resolution patterns extending into the unfavorable area; and performing a geometric operation on the second plurality of sub-resolution patterns to generate a third plurality of sub-resolution patterns, wherein the unfavorable pattern is separated from the unfavorable area.

[0061] Example 2 is the method described in Example 1, further comprising: a mask rule checking process, wherein the mask rule checking process is used to find the first group of sub-resolution patterns from the first plurality of sub-resolution patterns, wherein the first group of sub-resolution patterns are patterns that violate mask rules.

[0062] Example 3 is the method of Example 2, wherein the first plurality of sub-resolution patterns further includes a second set of sub-resolution patterns that comply with mask rules, and in the operation of complying with mask rules, the second set of sub-resolution patterns is not modified.

[0063] Example 4 is the method of Example 1, wherein the operation that complies with the mask rule includes an operation selected from the group consisting of: enlarging, repositioning, and merging the first plurality of sub-resolution patterns.

[0064] Example 5 is the method of Example 1, wherein the geometric operation includes repositioning, reducing, merging, or removing one of the unfavorable patterns.

[0065] Example 6 is the method of Example 1, wherein the geometric operation includes removing one of the unfavorable patterns.

[0066] Example 7 is the method of Example 1, wherein the geometric operation includes merging one of the disadvantageous patterns with another pattern in the second plurality of sub-resolution patterns.

[0067] Example 8 is the method described in Example 1, further comprising: manufacturing a photolithography mask, wherein the target pattern and the third plurality of sub-resolution patterns are formed in the photolithography mask; and using the photolithography mask to form an integrated circuit component, wherein the target pattern is implemented on the integrated circuit component and the third plurality of sub-resolution patterns are not implemented on the integrated circuit component.

[0068] Example 9 is the method of Example 1, further comprising: performing a mask rule checking process on the third plurality of sub-resolution patterns.

[0069] Example 10 is the method of Example 9, further comprising: amplifying additional scattering strips that violate mask rules in the third plurality of sub-resolution patterns to generate a fourth plurality of sub-resolution patterns.

[0070] Example 11 is the method of Example 10, further comprising: performing an additional bad area check on the fourth plurality of sub-resolution patterns.

[0071] Example 12 is a method for forming a sub-resolution auxiliary feature, comprising: generating a diffraction pattern based on multiple target patterns; generating a favorable area and an unfavorable area based on the diffraction pattern; placing multiple sub-resolution patterns in the favorable area; and performing multiple geometric operations on the multiple sub-resolution patterns to generate a modified sub-resolution pattern, wherein the modified sub-resolution pattern extends into the favorable area and away from the unfavorable area.

[0072] Example 13 is the method described in Example 12, wherein the diffraction pattern includes a bright area and a dark area, and the favorable area includes a portion of the bright area, and the unfavorable area includes a portion of the dark area.

[0073] Example 14 is the method described in Example 12, further comprising: determining a first brightness threshold and a second brightness threshold that is equal to or higher than the first brightness threshold, wherein an area in the diffraction pattern having a brightness value lower than the first brightness threshold is in an unfavorable area, and wherein an area in the diffraction pattern having a brightness value higher than the second brightness threshold is in a favorable area.

[0074] Example 15 is the method of Example 12, wherein the plurality of geometric operations include: an upscaling operation for upscaling some of the plurality of sub-resolution patterns and generating upscaled patterns; and an additional geometric operation for separating the upscaled patterns from the unfavorable area.

[0075] Example 16 is the method of Example 12, further comprising: performing a mask rule checking process for finding scattering strips violating mask rules in the plurality of sub-resolution patterns that have undergone some of the plurality of geometric operations.

[0076] Example 17 is the method described in Example 12, further comprising: an unfavorable area inspection process for finding an unfavorable pattern among the plurality of sub-resolution patterns, wherein the unfavorable pattern extends into the unfavorable area.

[0077] Example 18 is a method for forming a sub-resolution auxiliary feature, comprising: generating an unfavorable area and a scattering pattern; determining whether the scattering pattern overlaps with the unfavorable area; modifying the scattering pattern to generate a modified scattering pattern, wherein the modified scattering pattern is separated from the unfavorable area; forming a photolithography mask including the modified scattering pattern; and using the photolithography mask to perform an exposure process on a photoresist.

[0078] Example 19 is the method described in Example 18, further comprising: generating a diffraction pattern based on a target pattern, wherein the target pattern is also in the photolithography mask; and determining the unfavorable area and the favorable area based on the diffraction pattern, wherein the scattering pattern is placed in the favorable area.

[0079] Example 20 is the method of Example 18, wherein modifying the scattering pattern includes amplifying the scattering pattern.

Claims

1. A method for forming a sub-resolution auxiliary feature, comprising: generating a diffraction pattern according to the target pattern, wherein the diffraction pattern includes a bright pattern and a dark pattern; generating a favorable area and an unfavorable area according to the bright pattern and the dark pattern; placing a first plurality of sub-resolution patterns in the favorable region; performing a mask rule-compliant operation on the first plurality of sub-resolution patterns to generate a second plurality of sub-resolution patterns, wherein a first group of sub-resolution patterns in the first plurality of sub-resolution patterns is enlarged; performing an unfavorable area inspection process to find unfavorable patterns, wherein the unfavorable patterns are the enlarged first set of sub-resolution patterns extending into the unfavorable area; and A geometric operation is performed on the second plurality of sub-resolution patterns to generate a third plurality of sub-resolution patterns, wherein the unfavorable pattern is separated from the unfavorable region.

2. The method according to claim 1, further comprising: A mask rule checking process is used to find the first group of sub-resolution patterns from the first plurality of sub-resolution patterns, wherein the first group of sub-resolution patterns are patterns that violate mask rules.

3. The method according to claim 2, wherein: The first plurality of sub-resolution patterns further includes a second set of sub-resolution patterns that conform to mask rules, and the second set of sub-resolution patterns is not modified during the conforming to mask rules operation.

4. The method according to claim 1, wherein: The operations complying with the mask rules include operations selected from the group consisting of: enlarging, repositioning, and merging the first plurality of sub-resolution patterns.

5. The method according to claim 1, wherein: The geometric operation includes repositioning, reducing, merging, or removing one of the unfavorable patterns.

6. The method according to claim 1, wherein: The geometric operation includes removing one of the undesirable patterns.

7. The method according to claim 1, wherein: The geometric operation includes merging one of the unfavorable patterns with another pattern of the second plurality of sub-resolution patterns.

8. The method according to claim 1, further comprising: manufacturing a photolithography mask, wherein the target pattern and the third plurality of sub-resolution patterns are formed in the photolithography mask; and An integrated circuit component is formed using the photolithography mask, wherein the target pattern is implemented on the integrated circuit component and the third plurality of sub-resolution patterns are not implemented on the integrated circuit component.

9. The method according to claim 1, further comprising: A mask rule checking process is performed on the third plurality of sub-resolution patterns.

10. The method according to claim 9, further comprising: Additional scattering strips in the third plurality of sub-resolution patterns that violate mask rules are amplified to generate a fourth plurality of sub-resolution patterns.

11. The method according to claim 10, further comprising: An additional bad area check is performed on the fourth plurality of sub-resolution patterns.

12. A method for forming a sub-resolution assist feature, comprising: generating a diffraction pattern based on a plurality of target patterns; generating a favorable region and an unfavorable region according to the diffraction pattern; placing a plurality of sub-resolution patterns in the favorable region; as well as A plurality of geometric operations are performed on the plurality of sub-resolution patterns to generate modified sub-resolution patterns, wherein the modified sub-resolution patterns extend into the favorable region and away from the unfavorable region.

13. The method according to claim 12, wherein: The diffraction pattern includes a bright region and a dark region, and the favorable region includes a portion of the bright region and the unfavorable region includes a portion of the dark region.

14. The method according to claim 12, further comprising: Determine a first brightness threshold and a second brightness threshold that is equal to or higher than the first brightness threshold, wherein an area in the diffraction pattern having brightness values ​​lower than the first brightness threshold is in an unfavorable area, and wherein an area in the diffraction pattern having brightness values ​​higher than the second brightness threshold is in a favorable area.

15. The method according to claim 12, wherein: The plurality of geometric operations include: an upscaling operation for upscaling some of the plurality of sub-resolution patterns and generating upscaled patterns; and Additional geometric operations are used to separate the amplified pattern from the unfavorable area.

16. The method according to claim 12, further comprising: A mask rule checking process is performed for finding scattering strips violating mask rules in the plurality of sub-resolution patterns that have undergone some of the plurality of geometric operations.

17. The method according to claim 12, further comprising: The unfavorable region inspection process is used to find an unfavorable pattern among the plurality of sub-resolution patterns, wherein the unfavorable pattern extends into the unfavorable region.

18. A method for forming a sub-resolution assist feature, comprising: Generate unfavorable areas and scatter patterns; determining whether the scattering pattern overlaps with the unfavorable area; modifying the scattering pattern to generate a modified scattering pattern, wherein the modified scattering pattern is spaced apart from the disadvantageous region; forming a photolithographic mask including the modified scattering pattern; and An exposure process is performed on the photoresist using the photolithography mask.

19. The method according to claim 18, further comprising: generating a diffraction pattern according to a target pattern, wherein the target pattern is also in the lithography mask; and The unfavorable area and the favorable area are determined according to the diffraction pattern, wherein the scattering pattern is placed in the favorable area.

20. The method according to claim 18, wherein: Modifying the scattering pattern includes amplifying the scattering pattern.

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