Patent Publication Number: US-2022223432-A1

Title: Conductive wire structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of and claims the priority benefit of U.S. application Ser. No. 16/903,382, filed on Jun. 17, 2020. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a semiconductor device and a manufacturing method thereof, and particularly relates to a conductive wire structure and a manufacturing method thereof. 
     Description of Related Art 
     With the advancement of semiconductor technology, the size of device has also continued to shrink. As the integrity of the integrated circuit increases, the critical dimension of the conductive wire and the distance between the conductive wires will decrease accordingly. When the critical dimension of the conductive wire is reduced, it will make it difficult to align the subsequently formed contact with the conductive wire, thereby reducing the alignment margin between the contact and the conductive wire. In addition, when the distance between the conductive wires is shortened, the contact is easily connected to two adjacent conductive wires simultaneously to cause the problem of short circuit. 
     SUMMARY OF THE INVENTION 
     The invention provides a conductive wire structure and a manufacturing method thereof, which can increase the alignment margin between the contact and the conductive wire, and can prevent the problem of short circuit between two adjacent conductive wires. 
     The invention provides a method of manufacturing a conductive wire structure, which includes the following steps. A substrate is provided. A conductive layer is formed on a substrate. A rectangular ring spacer is formed on the conductive layer by a self-aligned double patterning (SADP) process. A patterned photoresist layer is formed. The patterned photoresist layer exposes a first portion and a second portion of the rectangular ring spacer. The first portion and the second portion are located at two corners on a diagonal of the rectangular ring spacer. The first portion and the second portion are removed by using the patterned photoresist layer as a mask to form a first spacer and a second spacer. The first spacer and the second spacer are L-shaped. The patterned photoresist layer is removed. A pattern of the first spacer and a pattern of the second spacer are transferred to the conductive layer to form an L-shaped first conductive wire and an L-shaped second conductive wire. 
     The invention provides a conductive wire structure, which includes a first conductive wire and a second conductive wire. The second conductive wire is located on one side of the first conductive wire. The first conductive wire includes a first conductive wire portion and a first pad portion. The first conductive wire portion extends in a first direction and has a first end and a second end. The first pad portion is connected to the first end of the first conductive wire portion. The second conductive wire includes a second conductive wire portion and a second pad portion. The second conductive wire portion extends in a second direction and has a third end and a fourth end. The third end is adjacent to the first end, and the fourth end is adjacent to the second end. The second direction is an opposite direction of the first direction. The second pad portion is connected to the fourth end of the second conductive wire portion. A first imaginary extension portion extends from the second end of the first conductive wire portion in the first direction away from the first end of the first conductive wire portion. A second imaginary extension portion extends from the third end of the second conductive wire portion in the second direction away from the fourth end of the second conductive wire portion. The first pad portion extends toward the second imaginary extension portion but does not intersect the second imaginary extension portion. The second pad portion extends toward the first imaginary extension portion but does not intersect the first imaginary extension portion. 
     Based on the above description, in the manufacturing method of the conductive wire structure according to the invention, the L-shaped first conductive wire and the L-shaped second conductive wire are formed by the self-aligned double patterning process, the patterning process, and the pattern transfer process, so that the process can be effectively simplified to reduce the complexity of the process. In addition, the L-shaped first conductive wire and the L-shaped second conductive wire manufactured by the above method can increase the area for electrically connecting with the subsequently formed contact, so that the alignment margin between the contact and the first conductive wire and the alignment margin between the contact and the second conductive wire can be effectively increased. Furthermore, the distance between the first conductive wire and the second conductive wire can be flexibly adjusted by the above method, thereby preventing the problem of short circuit caused by the contact simultaneously connected to the first conductive wire and the second conductive wire. 
     Moreover, in the conductive wire structure according to the invention, since the first conductive wire and the second conductive wire respectively have a first pad portion and a second pad portion, the alignment margin between the contact and the first conductive wire and the alignment margin between the contact and the second conductive wire can be effectively increased. In addition, since the first pad portion extends toward the second imaginary extension portion but does not intersect the second imaginary extension portion, and the second pad portion extends toward the first imaginary extension portion but does not intersect the first imaginary extension portion, the problem of short circuit caused by the contact being simultaneously connected to the first conductive wire and the second conductive wire can be prevented. 
     In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, several exemplary embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1A  to  FIG. 1G  are top views illustrating a manufacturing process of a conductive wire structure according to an embodiment of the invention. 
         FIG. 1H  to  FIG. 1I  are top views illustrating a manufacturing process of a contact according to an embodiment of the invention. 
         FIG. 2A  to  FIG. 2I  are cross-sectional views taken along a section line I-I′ and a section line II-II′ in  FIG. 1A  to  FIG. 1I . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIG. 1A  and  FIG. 2A , a substrate  100  is provided. The substrate  100  may be a semiconductor substrate, such as a silicon substrate. Furthermore, one of ordinary skill in the art may form a semiconductor device (e.g., a transistor) (not shown) and a dielectric layer (not shown) on the substrate  100  according to product requirements, and the description thereof is omitted herein. 
     A conductive layer  102  is formed on the substrate  100 . The conductive layer  102  may be a single-layer structure or a multi-layer structure. For example, the conductive layer  102  may be a multilayer structure including a conductive layer  104  and a conductive layer  106 , but the invention is not limited thereto. The conductive layer  104  is, for example, doped polysilicon. The conductive layer  106  is, for example, a metal or metal compound, such as tungsten, tungsten nitride, aluminum, titanium nitride, or copper. 
     A hard mask layer  108  may be formed on the conductive layer  102 . The hard mask layer  108  is, for example, silicon nitride or silicon oxide. 
     Referring to  FIG. 1A  to  FIG. 1D  and  FIG. 2A  to  FIG. 2D , a rectangular ring spacer  112   a  (referring to  FIGS. 1D and 2D ) may be formed on the conductive layer  102  by a self-aligned double patterning (SADP) process. For example, the rectangular ring spacer  112   a  may be formed on the hard mask layer  108  by the self-aligned double patterning process, as described below. 
     Referring to  FIG. 1A  and  FIG. 2A , a core pattern  110  having a rectangular shape may be formed on the conductive layer  102 . The material of the core pattern  110  is, for example, carbon, polysilicon, silicon oxide, or silicon nitride. The core pattern  110  may be formed by a deposition process, a lithography process, and an etching process. 
     Referring to  FIG. 1B  and  FIG. 2B , a spacer material layer  112  may be conformally formed on the core pattern  110 . The material of the spacer material layer  112  is, for example, silicon oxide or silicon nitride. The method of forming the spacer material layer  112  is, for example, a chemical vapor deposition method or an atomic layer deposition method. 
     Referring to  FIG. 1C  and  FIG. 2C , an etching process may be performed on the spacer material layer  112  to form a rectangular ring spacer  112   a  surrounding the sidewall of the core pattern  110 . The rectangular ring spacer  112   a  may include a long side portion LP 1 , a long side portion LP 2 , a short side portion SP 1 , and a short side portion SP 2 . The short side portion SP 1  is connected to an end of the long side portion LP 1  and an end of the long side portion LP 2 . The short side portion SP 2  is connected to the other end of the long side portion LP 1  and the other end of the long side portion LP 2 . The etching process is, for example, a dry etching process. 
     Referring to  FIG. 1D  and  FIG. 2D , the core pattern  110  may be removed. When the material of the core pattern  110  is carbon, the method of removing the core pattern  110  is, for example, ashing. When the material of the core pattern  110  is polysilicon, silicon oxide, or silicon nitride, the method of removing the core pattern  110  is, for example, a wet etching method. 
     In addition, although the self-aligned double patterning process is described using the above method as an example, the invention is not limited thereto. 
     Referring to  FIG. 1E  and  FIG. 2E , a patterned photoresist layer  114  is formed. The patterned photoresist layer  114  may be formed by a lithography process. The patterned photoresist layer  114  exposes a first portion P 1  and a second portion P 2  of the rectangular ring spacer  112   a . The first portion P 1  and the second portion P 2  are located at two corners on the diagonal of the rectangular ring spacer  112   a . The first portion P 1  may include a portion of the short side portion SP 1 , and the second portion P 2  may include a portion of the short side portion SP 2 . The length of the portion of the short side portion SP 1  in the first portion P 1  may be one-third to two-thirds of the total length of the short side portion SP 1 , and the length of the portion of the short side portion SP 2  in the second portion P 2  may be one-third to two-thirds of the total length of the short side portion SP 2 . That is, the patterned photoresist layer  114  may expose the portion of the short side portion SP 1  and the portion of the short side portion SP 2 , but the invention is not limited thereto. In other embodiments, the first portion P 1  may further include a portion of the long side portion LP 1 , and the second portion P 2  may further include a portion of the long side portion LP 2 . That is, the patterned photoresist layer  114  may further expose the portion of the long side portion LP 1  and the portion of the long side portion LP 2 . 
     Referring to  FIG. 1F  and  FIG. 2F , the first portion P 1  and the second portion P 2  are removed by using the patterned photoresist layer  114  as a mask to form a spacer S 1  and a spacer S 2 . The spacer S 1  and the spacer S 2  are L-shaped. The method of removing the first portion P 1  and the second portion P 2  is, for example, a dry etching method. In some embodiments, since the thickness of the patterned photoresist layer  114  above the rectangular ring spacer  112   a  is thinner, the patterned photoresist layer  114  located above the rectangular ring spacer  112   a  may be removed to expose the rectangular ring spacer  112   a  in the process of removing the first portion P 1  and the second portion P 2 . In this way, in the process of removing the first portion P 1  and the second portion P 2 , a portion of the rectangular ring spacer  112   a  originally located under the patterned photoresist layer  114  may be simultaneously removed, so that the height of the spacer S 1  and the height of the spacer S 2  are lower than the height of the rectangular ring spacer  112   a  (referring to  FIG. 2E  and  FIG. 2F ), but the invention is not limited thereto. In other embodiments, during the process of removing the first portion P 1  and the second portion P 2 , if the patterned photoresist layer  114  located above the rectangular ring spacer  112   a  is not removed, the height of the spacer S 1  and the height of the spacer S 2  may be approximately equal to the height of the rectangular ring spacer  112   a.    
     The patterned photoresist layer  114  is removed. The method of removing the patterned photoresist layer  114  is, for example, dry stripping or wet stripping. 
     Referring to  FIG. 1G  and  FIG. 2G , the pattern of the spacer S 1  and the pattern of the spacer S 2  are transferred to the hard mask layer  108  and the conductive layer  102  to form an L-shaped hard mask layer  108   a , an L-shaped hard mask layer  108   b , an L-shaped conductive wire W 1 , and an L-shaped conductive wire W 2 . The conductive wire W 1  may include a conductive layer  104   a  and a conductive layer  106   a . The conductive wire W 2  may include a conductive layer  104   b  and a conductive layer  106   b . The method of transferring the pattern of the spacer S 1  and the pattern of the spacer S 2  to the hard mask layer  108  and the conductive layer  102  is, for example, removing a portion of the hard mask layer  108  and a portion of the conductive layer  102  by using the spacer S 1  and the spacer S 2  as a mask. The method of removing the portion of the hard mask layer  108  and the portion of the conductive layer  102  is, for example, a dry etching method. 
     The spacer S 1  and the spacer S 2  may be removed. In some embodiments, in the process of transferring the pattern of the spacer S 1  and the pattern of the spacer S 2  to the hard mask layer  108  and the conductive layer  102 , the spacer S 1  and the spacer S 2  may be gradually consumed and removed, but the invention is not limited thereto. In this case, because the hard mask layer  108   a  and the hard mask layer  108   b  are used as an etching mask, the hard mask layer  108   a  and the hard mask layer  108   b  may be partially removed, so that the height of the hard mask layer  108   a  and the height of the hard mask layer  108   b  are lower than the height of the hard mask layer  108 . For example, the height of the hard mask layer  108   a  and the height of the hard mask layer  108   b  may be lower than the height of the hard mask layer  108  by 20% or less. In other embodiments, after the pattern of the spacer S 1  and the pattern of the spacer S 2  are transferred to the hard mask layer  108  and the conductive layer  102 , if the spacer S 1  and the spacer S 2  are still remained, the spacer S 1  and the spacer S 2  may be removed by wet etching. In this case, the height of the hard mask layer  108   a  and the height of the hard mask layer  108   b  may be approximately equal to the height of the hard mask layer  108 . 
     Referring to  FIG. 1H  and  FIG. 2H , a dielectric layer  116  may be formed on the substrate  100  between the conductive wire W 1  and the conductive wire W 2 . The material of the dielectric layer  116  is, for example, silicon oxide. The dielectric layer  116  is formed by, for example, first forming a dielectric material layer (not shown) covering the hard mask layer  108   a  and the hard mask layer  108   b , and then performing a chemical mechanical polishing process on the dielectric material layer to expose the hard mask layer  108   a  and the hard mask layer  108   b.    
     Referring to  FIG. 1I  and  FIG. 2I , contacts  118  are formed. The contacts  118  are electrically connected to the conductive wire W 1  and the conductive wire W 2 , respectively. The material of the contacts  118  is, for example, a metal material, such as tungsten, aluminum, or copper. The contacts  118  may be formed by an interconnect process. In some embodiments, a barrier layer (not shown) may be formed between the contact  118  and the conductive wire W 1  and between the contact  118  and the conductive wire W 2 , respectively. 
     Based on the above embodiments, in the manufacturing method of the conductive wire structure  10  (referring to  FIG. 1G  and  FIG. 2G ), the L-shaped conductive wire W 1  and the L-shaped conductive wire W 2  are formed by the self-aligned double patterning process, the patterning process, and the pattern transfer process, so that the process can be effectively simplified to reduce the complexity of the process. In addition, the L-shaped conductive wire W 1  and the L-shaped conductive wire W 2  manufactured by the above method can increase the area for electrically connecting with the subsequently formed contacts  118 , so that the alignment margin between the contact  118  and the conductive wire W 1  and the alignment margin between the contact  118  and the conductive wire W 2  can be effectively increased. Furthermore, the distance between the conductive wire W 1  and the conductive wire W 2  can be flexibly adjusted by the above method, thereby preventing the problem of short circuit caused by the contact  118  being simultaneously connected to the conductive wire W 1  and the conductive wire W 2 . 
     Hereinafter, the conductive wire structure  10  of the present embodiment is described with reference to  FIG. 1G  and  FIG. 2G . In the present embodiment, although the method of forming the conductive wire structure  10  is described by taking the above method as an example, the invention is not limited thereto. 
     Referring to  FIG. 1G  and  FIG. 2G , the conductive wire structure  10  includes the conductive wire W 1  and the conductive wire W 2 . In the present embodiment, the conductive wire structure  10  is exemplified by including multiple pairs of the conductive wire W 1  and the conductive wire W 2 , but the invention is not limited thereto. As long as the conductive wire structure  10  includes at least one pair of the conductive wire W 1  and the conductive wire W 2 , it falls within the scope of the invention. The conductive wire W 2  is located on one side of the conductive wire W 1 . The shapes of the conductive wire W 1  and the conductive wire W 2  may be L-shapes. The conductive wire W 1  and the conductive wire W 2  may be a single-layer structure or a multi-layer structure. The conductive wire W 1  may include a conductive layer  104   a  and a conductive layer  106   a . The conductive wire W 2  may include a conductive layer  104   b  and a conductive layer  106   b.    
     The conductive wire W 1  includes a conductive wire portion WP 1  and a pad portion EP 1 . The conductive wire portion WP 1  extends in a first direction D 1  and has a first end T 1  and a second end T 2 . The pad portion EP 1  is connected to the first end T 1  of the conductive wire portion WP 1 . The pad portion EP 1  may be perpendicular to the conductive wire portion WP 1 . 
     The conductive wire W 2  includes a conductive wire portion WP 2  and a pad portion EP 2 . The conductive wire portion WP 2  extends in a second direction D 2  and has a third end T 3  and a fourth end T 4 . The third end T 3  is adjacent to the first end T 1 , and the fourth end T 4  is adjacent to the second end T 2 . The second direction D 2  is an opposite direction of the first direction D 1 . The pad portion EP 2  is connected to the fourth end T 4  of the conductive wire portion WP 2 . The pad portion EP 2  may be perpendicular to the conductive wire portion WP 2 . The pad portion EP 1  may be parallel to the pad portion EP 2 . 
     An imaginary extension portion IE 1  extends from the second end T 2  of the conductive wire portion WP 1  in the first direction D 1  away from the first end T 1  of the conductive wire portion WP 1 . An imaginary extension portion IE 2  extends from the third end T 3  of the conductive wire portion WP 2  in the second direction D 2  away from the fourth end T 4  of the conductive wire portion WP 2 . The pad portion EP 1  extends toward the imaginary extension portion IE 2  but does not intersect the imaginary extension portion IE 2 . The pad portion EP 2  extends toward the imaginary extension portion IE 1  but does not intersect the imaginary extension portion IE 1 . The imaginary extension portion IE 1  and the conductive wire portion WP 1  may have the same width. The imaginary extension portion IE 2  and the conductive wire portion WP 2  may have the same width. In addition, the imaginary extension portion IE 1  and the imaginary extension portion IE 2  are imaginary components and do not actually exist. The purpose of the imaginary extension portion IE 2  is to describe the arrangement relationship between the pad portion EP 1  and the conductive wire W 2 , and the purpose of the imaginary extension portion IE 1  is to describe the arrangement relationship between the pad portion EP 2  and the conductive wire W 1 . 
     In addition, the material, the forming method, and the arrangement of each component of the conductive wire structure  10  have been described in detail in the aforementioned embodiments, and the description thereof are not repeated here. 
     Based on the above embodiments, in the conductive wire structure  10 , since the conductive wire W 1  and the conductive wire W 2  respectively have the pad portion EP 1  and the pad portion EP 2 , the alignment margin between the contact  118  and the conductive wire W 1  and the alignment margin between the contact  118  and the conductive wire W 2  can be effectively increased. In addition, since the pad portion EP 1  extends toward the imaginary extension portion IE 2  but does not intersect the imaginary extension portion IE 2 , and the pad portion EP 2  extends toward the imaginary extension portion IE 1  but does not intersect the imaginary extension portion IE 1 , the problem of short circuit caused by the contact  118  being simultaneously connected to the conductive wire W 1  and the conductive wire W 2  can be prevented. 
     In summary, the conductive wire structure and its manufacturing method of the aforementioned embodiments can increase the alignment margin between the contact and the conductive wire and can prevent the problem of short circuit between adjacent two conductive wires. 
     Although the invention has been described with reference to the above embodiments, it will be apparent to one of ordinary skill in the art that modifications to the described embodiments may be made without departing from the spirit of the invention. Accordingly, the scope of the invention is defined by the attached claims not by the above detailed descriptions.