Solution for contact plug bridging
By adjusting the size of the contact plug and reducing the overlap area, the problem of adjacent contact plug bridge in SRAM is solved and the yield of the memory is improved.
Patent Information
- Application Number
- CN202510216561.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2025-05-23
AI Technical Summary
In static random access memory (SRAM), there is a bridge between adjacent shared contact plugs (SCTs), resulting in short circuit conditions and severe leakage of P-channel metal oxide semiconductor current, affecting the yield of the memory cell.
By adjusting the size of adjacent first and second contact plugs, their overlap area area in certain directions is reduced, thereby avoiding bridging. Specific methods include reducing the size of certain ends or sides of the contact plug and adjusting by optical proximity correction (OPC) technology.
It effectively avoids bridging between adjacent contact plugs, reduces current leakage, and improves the yield of static random access memory.
Smart Images
Figure CN120033144A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a solution to contact plug bridging. Background Art
[0002] As the size of process nodes decreases, the area of static random access memory (SRAM) decreases accordingly. In the process of improving yield in the R&D stage, single bit (SB) failure is the key to improving yield. In the SB Fail case, the roundness (Distortion) of the contact plug (CT) is a major factor in improving yield. The contact plug is a channel connecting the front-end transistor and the back-end metal wiring. In order to store more data and save chip space, shared contact plugs (Share CT, SCT) have been widely used in SRAM production.
[0003] However, there is a bridge between adjacent SCTs, which causes a short circuit, resulting in serious current leakage of the P-channel metal oxide semiconductor (PMOS) in the memory cell (BitCell). Summary of the invention
[0004] Based on this, it is necessary to provide a solution to the contact plug bridging problem in view of the above-mentioned background technology, which can at least avoid the bridging of adjacent shared contact plugs and improve the yield of static random access memory.
[0005] To achieve the above-mentioned and other related purposes, one aspect of the present application provides a solution for contact plug bridging, comprising the following steps:
[0006] The contact plug layer includes at least a first contact plug and a second contact plug adjacent to each other, wherein the first contact plug and the second contact plug are arranged in parallel in a first direction, and the first contact plug and the second contact plug have an overlapping area in a second direction;
[0007] The size of the first contact plug and / or the second contact plug is adjusted to reduce the area of the overlapping region.
[0008] In one embodiment, adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region includes: reducing the size of the first end of the first contact plug in the first direction, and / or reducing the size of the second end of the second contact plug in the first direction, wherein the first end of the first contact plug and the second end of the second contact plug are both located in the overlapping region.
[0009] In one embodiment, adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region includes: reducing the size of a first side of the first contact plug in the second direction, and / or reducing the size of a second side of the second contact plug in the second direction, wherein the first side of the first contact plug is adjacent to the second side of the second contact plug.
[0010] In one embodiment, the solution to the contact plug bridging further includes a third direction, the first direction is perpendicular to the second direction, and the third direction intersects both the first direction and the second direction.
[0011] In one embodiment, adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region also includes: reducing the size of the first contact plug and / or the second contact plug in the third direction to increase the spacing between the first contact plug and the second contact plug in the third direction.
[0012] In one embodiment, adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region further includes: obtaining a minimum spacing between the first contact plug and the second contact plug; and adjusting the size of the first contact plug and / or the second contact plug to increase the minimum spacing between the first contact plug and the second contact plug.
[0013] In one embodiment, the solution to the contact plug bridging further includes: determining the third direction based on the wiring with the minimum pitch.
[0014] In one embodiment, optical proximity correction is performed to adjust the size of the first contact plug and / or the second contact plug.
[0015] In one embodiment, a size of the first contact plug in the first direction is larger than a size of the first contact plug in the second direction, and a size of the second contact plug in the second direction is larger than a size of the first contact plug in the second direction.
[0016] In one embodiment, the first contact plug and the second contact plug each include a shared contact plug.
[0017] According to the solution to the contact plug bridging provided by the present invention, for two adjacent contact plugs that are parallel in a first direction and overlap in a second direction, the area of the overlapping region is reduced by adjusting the sizes of the two contact plugs, thereby avoiding bridging of adjacent contact plugs and improving the yield of the static random access memory. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to better describe and illustrate the embodiments and / or examples of those applications disclosed herein, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the embodiments and / or examples currently described, and the best modes of these applications currently understood.
[0019] Figure 1 An electron microscope image of a contact plug bridge in a static random access memory is shown;
[0020] Figure 2 A flow chart showing a solution to contact plug bridging according to an embodiment of the present invention is shown;
[0021] Figure 3 A schematic diagram showing a design layout of a contact plug layer according to an embodiment of the present invention;
[0022] Figure 4 An electron microscope image of a contact plug in a static random access memory according to an embodiment of the present invention is shown;
[0023] Figure 5 A schematic diagram showing the yield of a static random access memory according to an embodiment of the present invention is shown.
[0024] Description of reference numerals:
[0025] 301, a first contact plug; 302, a second contact plug. DETAILED DESCRIPTION
[0026] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.
[0028] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part.
[0029] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.
[0030] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.
[0031] Embodiments of the application are described herein with reference to cross-sectional views that are schematic diagrams of ideal embodiments (and intermediate structures) of the application. Thus, variations from the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the application should not be limited to the specific shapes of the zones shown herein, but rather include shape deviations due to, for example, manufacturing, and the zones shown in the figures are schematic in nature, and their shapes are not intended to display the actual shapes of the zones of the device and are not intended to limit the scope of the application.
[0032] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present application in a schematic manner. Although the illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation, the type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the component layout type may also be more complicated.
[0033] Figure 1 Figure 2 shows an electron microscope image of a contact plug bridge in a static random access memory. Figure 1 As shown, a bridge occurs between adjacent SCTs, which will cause a short circuit (Short) and lead to serious current leakage (Leakage) of the P-channel metal oxide semiconductor (PMOS) in the memory cell (Bit Cell).
[0034] In order to solve the problem of poor roundness of contact plugs in static random access memory, the present application provides a solution for contact plug bridging, such as Figure 2 As shown, the following steps are included:
[0035] Step S210: The contact plug layer includes at least a first contact plug and a second contact plug that are adjacent to each other, wherein the first contact plug and the second contact plug are arranged in parallel in a first direction, and the first contact plug and the second contact plug have an overlapping area in a second direction;
[0036] Step S220: adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region.
[0037] In step S210, firstly, a design layout of the contact plug layer is obtained, such as Figure 3 The contact plug (CT) of the static random access memory is made by filling metal in the normal contact hole between the metal layer and the active area or polysilicon, so as to form a contact between the metal layer and the active area or polysilicon. The filled metal can be tungsten, copper, aluminum, molybdenum, etc. In the embodiments of the present application, reference is made to Figure 3 and Figure 1The contact plug layer of SRAM includes two types of contact plugs. One is a conventional metal plug, which is usually used as a contact plug of a single component and has substantially the same length in different directions. Figure 3 Usually designed as a circle, Figure 1 The other is a shared contact plug (Share CT, SCT), which can be used for contact plugs shared by two or more components (such as gate and source or gate and drain), and has different lengths in different directions. Figure 3 The designs are usually ellipses, combinations of rectangles and circles, combinations of rectangles and ellipses, etc. Figure 1 In the diagram, the contact plugs are long strips or ovals. When the spacing between the contact plugs is too small, the photoresist of the contact holes may be reversed during the etching process, which further leads to contact plug bridges. Through statistical analysis of poor contact plug bridges, it is found that poor bridges mainly occur between adjacent shared contact plugs (SCTs). Therefore, the main target for solving contact plug bridges is the shared contact plugs.
[0038] In one embodiment, for two adjacent shared contact plugs, such as the first contact plug 301 and the second contact plug 302, the two are arranged in parallel in the first direction, have an overlapping area in the second direction, and the lengths of the first contact plug 301 and the second contact plug 302 in the first direction are greater than the lengths in the second direction. For ease of description, in the following embodiments, the first direction is the X-axis direction in a Cartesian coordinate system, and the second direction is the Y-axis direction in a Cartesian coordinate system.
[0039] Exemplarily, adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region includes: reducing the size of the first end of the first contact plug in the first direction, and / or reducing the size of the second end of the second contact plug in the first direction, wherein the first end of the first contact plug and the second end of the second contact plug are both located in the overlapping region.
[0040] In one embodiment, referring to Figure 3As shown, the left end of the first contact plug 301 and the right end of the second contact plug 302 have an overlapping area in the Y direction, so the overlapping area of the first contact plug 301 and the second contact plug 302 reduces the design size in the X direction. Specifically, optical proximity correction (OPC) is performed to reduce the design size of the left end of the first contact plug 301, and the reduced size can be set as needed, preferably 5nm~15nm, such as 5nm, 10nm, 15nm. OPC is performed to reduce the design size of the right end of the second contact plug 302, and the reduced size can be set as needed, preferably 5nm~15nm, such as 5nm, 10nm, 15nm. It should be noted that only the size of the first contact plug 301 and the second contact plug 302 can be reduced, or the sizes of both the first contact plug 301 and the second contact plug 302 can be reduced at the same time. Further, the first contact plug 301 and the second contact plug 302 can be reduced in the same size at the same time or in different sizes at the same time.
[0041] Exemplarily, adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region includes: reducing the size of the first side of the first contact plug in the second direction, and / or reducing the size of the second side of the second contact plug in the second direction, wherein the first side of the first contact plug is adjacent to the second side of the second contact plug.
[0042] In one embodiment, referring to Figure 3 As shown, the first contact plug 301 and the second contact plug 302 have an overlapping area in the Y direction, and the lower side of the first contact plug 301 is adjacent to the upper side of the second contact plug 302. Therefore, the design size of the first contact plug 301 and the second contact plug 302 is reduced in the Y direction. Specifically, OPC is performed to reduce the design size of the lower side of the first contact plug 301, and the reduced size can be set as needed, preferably 3nm~10nm, such as 3nm, 5nm, 10nm. OPC is performed to reduce the design size of the upper side of the second contact plug 302, and the reduced size can be set as needed, preferably 3nm~10nm, such as 3nm, 5nm, 10nm. It should be noted that the size of only one of the first contact plug 301 and the second contact plug 302 can be reduced, or the sizes of both the first contact plug 301 and the second contact plug 302 can be reduced at the same time. Further, the first contact plug 301 and the second contact plug 302 can be reduced in the same size at the same time, or different sizes can be reduced at the same time.
[0043] exist Figure 3In the illustrated embodiment, the spacing between the first contact plug 301 and the second contact plug 302 is represented by R1, and specifically, R1 is 87 nm. The line representing R1 is neither parallel to the first direction (X direction) nor to the second direction (Y direction), and the direction where R1 is located is the third direction, which intersects both the first direction and the second direction. Preferably, the angle between the third direction and the second direction is less than 40°, such as 5°, 15°, or 30°.
[0044] Exemplarily, adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region also includes: reducing the size of the first contact plug and / or the second contact plug in the third direction to increase the spacing between the first contact plug and the second contact plug in the third direction.
[0045] In one embodiment, referring to Figure 3 As shown, the intersection point of the first contact plug 301 and R1 in the third direction is A, and the intersection point of the second contact plug 302 and R1 in the third direction is B. Reducing the size of the first contact plug 301 in the third direction includes: moving point A along the third direction away from the second contact plug 302, or moving point A in a direction close to the center point O1 of the first contact plug. In the present embodiment, point A is moved to the upper right. Similarly, reducing the size of the second contact plug 302 in the third direction includes: moving point B along the third direction away from the first contact plug 301, or moving point B in a direction close to the center point O2 of the second contact plug. In the present embodiment, point B is moved to the lower left. In this way, the curvature of the curve where point A or point B is located can be changed to make the curve where point A or point B is located inward, thereby increasing the distance between the first contact plug 301 and the second contact plug 302 in the third direction, as shown in FIG. Figure 4 shown.
[0046] Exemplarily, adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region also includes: obtaining a minimum spacing between the first contact plug and the second contact plug; adjusting the size of the first contact plug and / or the second contact plug to increase the minimum spacing between the first contact plug and the second contact plug.
[0047] In one embodiment, the minimum spacing between the first contact plug 301 and the second contact plug 302 is first determined, for example, the minimum spacing is R1. The line of the minimum spacing is the line of R1, and the direction in which it is located is determined as the third direction. Similar to the above method, the intersection point of the first contact plug 301 and R1 in the third direction is A, and the intersection point of the second contact plug 302 and R1 in the third direction is B. Move point A along the third direction away from the second contact plug 302, or move point A in a direction close to the center point O1 of the first contact plug. Move point B along the third direction away from the first contact plug 301, or move point B in a direction close to the center point O2 of the second contact plug. In this way, the minimum spacing between the first contact plug 301 and the second contact plug 302 can be increased by changing the curvature of the curve where point A or point B is located, so that the curve where point A or point B is located is retracted, such as Figure 4 shown.
[0048] Reference Figure 4 As shown, after reducing the size of adjacent shared contact plugs in the first direction, the second direction and / or the third direction, the spacing between adjacent shared contact plugs is increased, and the area of the overlapping region is reduced, thereby avoiding bridging between adjacent shared contact plugs, improving leakage, and improving the yield of SRAM.
[0049] In one embodiment, referring to Figure 5 As shown, when executing OPC to Figure 3 Before the design size of the shared contact plug in was modified (#0), the yield of SRAM was about 32.9%. When the overlapping area of the shared contact plug was reduced by 10nm in the X direction (#1), the yield of SRAM was about 35.17%. When the overlapping area of the shared contact plug was reduced by 5nm in the X direction and by 5nm in the Y direction (#2), the yield of SRAM was about 42.25%. When the overlapping area of the shared contact plug was reduced by 10nm in the X direction and by 5nm in the Y direction (#3), the yield of SRAM was about 39.92%. When the overlapping area of the shared contact plug was reduced by 15nm in the X direction and by 5nm in the Y direction (#4), the yield of SRAM was about 33.58%. According to Figure 5 The results show that, for the shared contact plug bridging problem, the preferred solution is to reduce the shared contact plug in both the X and Y directions, by 5nm-10nm in the X direction and by about 5nm in the Y direction, so as to significantly improve the yield of the SRAM.
[0050] According to the solution to the contact plug bridging provided by the present invention, for two adjacent contact plugs that are parallel in a first direction and overlap in a second direction, the area of the overlapping region is reduced by adjusting the sizes of the two contact plugs, thereby avoiding bridging of adjacent contact plugs and improving the yield of the static random access memory.
[0051] Please note that the above embodiments are for illustrative purposes only and are not intended to limit the present application.
[0052] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.
[0053] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0054] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.
Claims
1. A solution to contact plug bridging, characterized in that: The following steps are involved: The contact plug layer includes at least a first contact plug and a second contact plug adjacent to each other, wherein the first contact plug and the second contact plug are arranged in parallel in a first direction, and the first contact plug and the second contact plug have an overlapping area in a second direction; The size of the first contact plug and / or the second contact plug is adjusted to reduce the area of the overlapping region.
2. The solution to the contact plug bridging according to claim 1, characterized in that: The adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region includes: The first end of the first contact plug is reduced in size in the first direction, and / or the second end of the second contact plug is reduced in size in the first direction, wherein the first end of the first contact plug and the second end of the second contact plug are both located in the overlapping region.
3. The solution to the contact plug bridging according to claim 1, characterized in that: The adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region includes: The first side of the first contact plug is reduced in size in the second direction, and / or the second side of the second contact plug is reduced in size in the second direction, wherein the first side of the first contact plug is adjacent to the second side of the second contact plug.
4. The solution to the contact plug bridging according to claim 1, characterized in that: A third direction is also included, the first direction is perpendicular to the second direction, and the third direction intersects both the first direction and the second direction.
5. The solution to the contact plug bridging according to claim 4, characterized in that: The adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region further comprises: The size of the first contact plug and / or the second contact plug in the third direction is reduced to increase the distance between the first contact plug and the second contact plug in the third direction.
6. The solution to the contact plug bridging according to claim 4, characterized in that: The adjusting the size of the first contact plug and / or the second contact plug to reduce the area of the overlapping region further comprises: obtaining a minimum spacing between the first contact plug and the second contact plug; The size of the first contact plug and / or the second contact plug is adjusted to increase a minimum distance between the first contact plug and the second contact plug.
7. The solution to the contact plug bridging according to claim 6, characterized in that: Also includes: The third direction is determined based on the line with the minimum spacing.
8. The solution to the contact plug bridging according to any one of claims 1 to 7, characterized in that: Optical proximity effect correction is performed to adjust the size of the first contact plug and / or the second contact plug.
9. The solution to the contact plug bridging according to claim 1, characterized in that: A size of the first contact plug in the first direction is larger than a size of the first contact plug in the second direction, and a size of the second contact plug in the first direction is larger than a size of the second contact plug in the second direction.
10. The solution to the contact plug bridging according to claim 1, characterized in that: The first contact plug and the second contact plug each include a shared contact plug.