Patent Publication Number: US-2023154853-A1

Title: Semiconductor structure and semiconductor device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of International Application No. PCT/CN2022/110344, filed on Aug. 4, 2022, which claims the priority to Chinese Patent Application No. 202111042445.2, titled “SEMICONDUCTOR STRUCTURE AND SEMICONDUCTOR DEVICE” and filed on Sep. 7, 2021. The entire contents of International Application No. PCT/CN2022/110344 and Chinese Patent Application No. 202111042445.2 are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the technical field of semiconductors, and in particular, to a semiconductor structure and a semiconductor device. 
     BACKGROUND 
     An insulating layer covers a surface of a top conductive layer of a semiconductor structure, and the insulating layer fills a recess in the top conductive layer and forms an air gap. However, the existing semiconductor structure is prone to defects during or after formation of the insulating layer. Consequently, the insulating layer does not cover the top conductive layer tightly, resulting in instability of the semiconductor structure. 
     SUMMARY 
     According to one aspect of the present disclosure, a semiconductor structure is provided, including a first conductive layer, a first barrier layer, and an insulating layer, where the first conductive layer includes at least two first traces, and a recess is formed between two adjacent ones of the first traces; the first barrier layer is provided on a sidewall of the recess; and the insulating layer fills the recess, and an air gap is formed in the insulating layer located in the recess. 
     According to another aspect of the present disclosure, a semiconductor device is provided, where the semiconductor device includes the semiconductor structure described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic layer diagram of a semiconductor structure according to an exemplary embodiment; 
         FIG.  2    to  FIG.  5    are each a schematic layer diagram of a semiconductor structure according to a plurality of other exemplary embodiments; 
         FIG.  6    is a schematic flowchart of a method of manufacturing a semiconductor structure according to an exemplary embodiment; 
         FIG.  7    to  FIG.  10    are each a schematic layer diagram of a semiconductor structure in a plurality of steps of the method of manufacturing a semiconductor structure shown in  FIG.  6   ; and 
         FIG.  11    to  FIG.  15    are each a schematic layer diagram of a semiconductor structure in a plurality of steps of a method of manufacturing a semiconductor structure according to another exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments will be described below comprehensively with reference to the drawings. The exemplary embodiments may be implemented in various forms, and may not be construed as being limited to those described herein. On the contrary, these exemplary embodiments are provided to make the present disclosure comprehensive and complete and to fully convey the concept manifested therein to those skilled in the art. The same reference numerals in the figures indicate the same or similar structures, and thus their detailed descriptions will be omitted. 
       FIG.  1    representatively illustrates a schematic layer diagram of a semiconductor structure provided in the present disclosure in a first embodiment. In this exemplary embodiment, the semiconductor structure provided in the present disclosure is described by using an example in which the semiconductor structure is applied to a dynamic random access memory (DRAM). It is understandable for those skilled in the art that, in order to apply the relevant design of the present disclosure to other types of semiconductor structures, various modifications, additions, substitutions, deletions, or other changes may be made to the following specific embodiments, but such changes still fall within the scope of the principle of the semiconductor structure proposed by the present disclosure. 
     As shown in  FIG.  1   , in this embodiment, the semiconductor structure provided in the present disclosure includes at least a first conductive layer M 2 , a first barrier layer  120 , and an insulating layer  130 . Specifically, the first conductive layer M 2  is provided on a device layer  110  and is electrically connected to a device in the device layer  110 , to transmit a signal for the device in the device layer  110 . In addition, the first conductive layer M 2  includes at least two first traces m, and a recess Via 0  is formed between two adjacent ones of the first traces m. The first barrier layer  120  is provided on a sidewall of the recess Via 0 . The insulating layer  130  fills the recess Via 0 , and an air gap G is formed in the insulating layer  130  located in the recess Via 0 . Through the foregoing design, the present disclosure can use the first barrier layer  120  to effectively prevent external water vapor from penetrating the first conductive layer M 2  and other structures through the insulating layer  130 , and an electromigration phenomenon between adjacent first traces m of the first conductive layer M 2  can be effectively prevented by using the first barrier layer  120 . It should be noted that, the first conductive layer M 2  may be in direct contact with, or may be electrically connected, through another conductive layer, to the device layer  110 . 
     In some embodiments, as shown in  FIG.  1   , in this embodiment, the first barrier layer  120  may alternatively be provided on a bottom wall of the recess Via 0 . Through the foregoing design, the semiconductor structure can use the first barrier layer  120  provided on the bottom wall of the recess Via 0  to further prevent the external water vapor from penetrating the device layer  110  through the recess Via 0 . 
     As shown in  FIG.  2   , in some embodiments, the semiconductor structure provided in the present disclosure includes at least a first conductive layer M 2 , a first barrier layer  220 , and an insulating layer  231 . Specifically, the first conductive layer M 2  is provided on a device layer  210  and is electrically connected to a device in the device layer  210 , to transmit a signal for the device in the device layer  210 . In addition, the first conductive layer M 2  includes at least two first traces m, and a recess Via 0  is formed on a top surface between two adjacent ones of the first traces m. The first barrier layer  220  is provided on a sidewall of the recess Via 0 . The insulating layer  231  fills the recess Via 0 , and an air gap G is formed in the insulating layer  231  located in the recess Via 0 . Through the foregoing design, the present disclosure can use the first barrier layer  220  to effectively prevent external water vapor from penetrating the first conductive layer M 2  and other structures through the insulating layer  231 , and an electromigration phenomenon between adjacent first traces m of the first conductive layer M 2  can be effectively prevented by using the first barrier layer  220 . It should be noted that, the first conductive layer M 2  may be in direct contact with, or may be electrically connected, through another conductive layer, to the device layer  210 . 
     In some embodiments, as shown in  FIG.  2   , the first barrier layer  220  is alternatively provided on the top surface of the first conductive layer M 2 . The semiconductor structure can use the first barrier layer  220  provided on the top surface of the first conductive layer M 2  to further prevent the external water vapor from penetrating through the top surface of the first conductive layer M 2 . 
     In some embodiments, as shown in  FIG.  1    and  FIG.  2   , a reference direction is defined, and the reference direction is from the top surface of the first conductive layer M 2  to a bottom surface of the first conductive layer M 2 . In the reference direction, an extension length of the air gap G is less than a thickness of the first conductive layer M 2 . For example, a ratio of the extension length of the air gap G to the thickness of the first conductive layer M 2  may be ½ to ⅘, for example ½, 4/7, ⅗, or ⅘. In some embodiments, the ratio of the extension length of the air gap G to the thickness of the first conductive layer M 2  may alternatively be less than ½ or greater than ⅘, for example, may be ⅜ or ⅞, which is not limited thereto. In addition, as shown in  FIG.  1   , in some embodiments, the air gap G may extend from the top of the recess Via 0  to the bottom of the recess Via 0 . In other words, in the reference direction, the extension length of the air gap G may be slightly less than (approximately equal to) the thickness of the first conductive layer M 2 , and a size difference therebetween may be 1 nm to 100 nm. 
     As shown in  FIG.  3   , in some embodiments, the semiconductor structure includes a first dielectric layer  310 , the first conductive layer M 2 , a first barrier layer  320 , an insulating layer, a second dielectric layer  340 , a second barrier layer  350 , and a second conductive layer M 1 . Specifically, the first conductive layer M 2  is provided on a top surface of the first dielectric layer  310 , the first conductive layer M 2  includes at least two first traces m, and a recess Via 2  is formed between two adjacent ones of the first trace m. The first barrier layer  320  is provided on a sidewall of the recess Via 2 . The insulating layer may include a first insulating layer  331  and a second insulating layer  332 . The first insulating layer  331  is provided on a top surface of the first conductive layer and fills the recess Via 2 , and an air gap G is formed in the first insulating layer  331  located in the recess Via 2 . The second insulating layer  332  is provided on a top surface of the first insulating layer  331 . The second dielectric layer  340  is located below the first dielectric layer  310 . The second barrier layer  350  is provided between a bottom surface of the first dielectric layer  310  and a top surface of the second dielectric layer  340 . The second conductive layer M 1  is provided in the second dielectric layer  340 . The second conductive layer M 1  includes at least two second traces, and each of the second traces of the second conductive layer M 1  is connected to each of the first traces m of the first conductive layer M 2  by a first interconnect structure Via 1  running through the second barrier layer  350  and the first dielectric layer  310 . 
     In some embodiments, as shown in  FIG.  3   , the first barrier layer  320  may alternatively be provided on a bottom wall of the recess Via 2 . Through the foregoing design, the semiconductor structure can use the first barrier layer  320  provided on the bottom wall of the recess Via 2  to further prevent the external water vapor from penetrating through the top surface of the first dielectric layer  310 . 
     As shown in  FIG.  4   , in some embodiments, a first barrier layer  420  may be further provided on a top surface of the first conductive layer M 2 . Through the foregoing design, the semiconductor structure can use the first barrier layer  420  provided on the top surface of the first conductive layer M 2  to further prevent the external water vapor from penetrating through the top surface of the first conductive layer M 2 . 
     As shown in  FIG.  3    and  FIG.  4   , orthographic projection of the recess Via 2  on the top surface of the first conductive layer M 2  and orthographic projection of the first interconnect structure Via 1  on the top surface of the first conductive layer M 2  are arranged in a staggered manner. 
     As shown in  FIG.  3   , the recess Via 2  may run through the first dielectric layer  310 , and the recess Via 2  extends to the second barrier layer  350 . A top surface of the second barrier layer  350  exposed in the recess Via 2  defines a bottom wall of the recess Via 2 , that is, the first barrier layer  320  is provided on the top surface of the second barrier layer  350  exposed in the recess Via 2 . On this basis, a reference direction is defined, and the reference direction is a direction from the top surface of the first conductive layer M 2  to a bottom surface of the first conductive layer M 2 . In the reference direction, an extension length of the air gap G is greater than a thickness of the first conductive layer M 2  and less than a sum of thicknesses of the first conductive layer M 2  and the first dielectric layer  310 . Through the foregoing design, the air gap G can extend to the first dielectric layer  310  in the reference direction, such that the dielectric property between the first conductive layer M 2  and the first dielectric layer  310  can be effectively reduced, thereby helping reduce an RC delay. 
     In some embodiments, as shown in  FIG.  3   , in the reference direction, on the basis that the extension length of the air gap G is greater than the thickness of the first conductive layer M 2 , a ratio of the extension length of the air gap G to the sum of the thicknesses of the first conductive layer M 2  and the first dielectric layer  310  may be ½ to ⅘, for example, ½, 4/7, ⅗, or ⅘, such that an electromigration phenomenon between first traces m of the first conductive layer M 2  can be further well prevented. 
     In some embodiments, the ratio of the extension length of the air gap G to the sum of the thicknesses of the first conductive layer M 2  and the first dielectric layer  310  may alternatively be less than ½ or greater than ⅘, for example, may be ⅜ or ⅞, which is not limited thereto. 
     In some embodiments, as shown in  FIG.  3   , the air gap G may extend from the top of the recess Via 2  to the bottom of the recess Via 2 . In other words, in the reference direction, the extension length of the air gap G may be slightly less than (approximately equal to) the thickness of the first conductive layer M 2 , and a size difference therebetween may be 1 nm to 100 nm. 
     In addition, as shown in  FIG.  5   , in some embodiments, on the basis that the semiconductor structure further includes a second dielectric layer  540 , a second barrier layer  550 , and the second conductive layer M 1 , the recess Via 2  may alternatively extend only to a top surface of a first dielectric layer  510 , that is, the recess Via 2  does not run through the first dielectric layer  510 . In this case, the top surface of the first dielectric layer  510  is partially exposed in the recess Via 2 , that is, part of the top surface of the first dielectric layer  510  exposed in the recess Via 2  defines a bottom wall of the recess Via 2 . On this basis, in the reference direction, the extension length of the air gap G is less than the thickness of the first conductive layer M 2 . 
     Optionally, the first barrier layer  320  is made of a same material as the second barrier layer  350 , for example, silicon nitride. 
     Optionally, a material of the interconnect structure Via 1  may include tungsten (W). 
     Optionally, in this embodiment, a material of the first barrier layer  120  may include silicon nitride (Si 3 N 4 ). 
     Optionally, as shown in  FIG.  1   , in this embodiment, the insulating layer  130  may alternatively cover the top surface of the first conductive layer M 2 . 
     Optionally, in this embodiment, a material of the insulating layer  130  may include silicon oxide (SiO 2 ). 
     Optionally, a material of the first conductive layer M 2  may include aluminum. 
     As shown in  FIG.  2   , in some embodiments, the insulating layer may include a first insulating layer  231  and a second insulating layer  232 . Specifically, the first insulating layer  231  covers the first conductive layer M 2  and fills the recess Via 0 , and an air gap G is formed in the first insulating layer  231  located in the recess Via 0 . The second insulating layer  232  is provided on a top surface of the first insulating layer  231 . In other embodiments, the first insulating layer  231  may alternatively only fill the recess Via 0 , and the second insulating layer  232  may cover a top surface of the first insulating layer  231  and a top surface of the first conductive layer M 2 . 
     Further, a material of the first insulating layer  231  may include silicon oxide. 
     Further, a material of the second insulating layer  232  may include silicon nitride. 
     In some embodiments, the semiconductor structure of the present disclosure further includes at least one third conductive layer and at least one third barrier layer. The third conductive layer includes a plurality of third traces and a third dielectric layer. The third dielectric layer is provided between two adjacent ones of the third traces. The third barrier layer and the third conductive layer are sequentially laminated on one side of the second dielectric layer away from the second conductive layer. 
     The third conductive layer closest to the second dielectric layer is connected to the second conductive layer by a second interconnect structure running through the second dielectric layer and the third barrier layer. Two adjacent ones of the third conductive layer are connected by a third interconnect structure running through the third barrier layer and the third dielectric layer. 
     It should be noted herein that the semiconductor structure shown in the drawings and described in this specification only show a few examples of many semiconductor structures that can adopt the principle of the present disclosure. It should be clearly understood that the principle of the present disclosure is by no means limited to any details or any structures of the semiconductor structure shown in the drawings or described in this specification. 
     Based on the semiconductor structure described above, the present disclosure further provides a semiconductor device. The semiconductor device includes the semiconductor structure described above. For example, the semiconductor device is a memory. The memory includes a memory cell array and a peripheral circuit. The peripheral circuit may include the semiconductor structure for leading out a corresponding signal. An RC delay in the semiconductor structure is reduced, such that it correspondingly helps improve overall performance of the memory. 
     Based on the foregoing detailed description of the semiconductor structure provided in the present disclosure, the following describes an exemplary embodiment of a method of manufacturing a semiconductor structure provided in the present disclosure. 
       FIG.  6    representatively illustrates a schematic flowchart of a method of manufacturing a semiconductor structure according to the present disclosure. In the exemplary embodiment, the manufacturing method provided in the present disclosure is described by using an example in which it is applied to a DRAM. It is understandable for those skilled in the art that, in order to apply the relevant design of the present disclosure to other types of semiconductor structures, various modifications, additions, substitutions, deletions, or other changes may be made to the following specific embodiments, but such changes still fall within the scope of the principle of the method of manufacturing a semiconductor structure provided in the present disclosure. 
     As shown in  FIG.  6   , the method of manufacturing a semiconductor structure provided in the present disclosure includes: 
     Step S 1 : Provide a device layer, and form a first conductive layer on the device layer. 
     Step S 2 : Form a recess on a top surface of the first conductive layer, where the recess divides the first conductive layer into at least two traces. 
     Step S 3 : Form a first barrier layer on a sidewall of the recess. 
     Step S 4 : Fill the recess with an insulating layer, and form an air gap in the insulating layer located in the recess. 
     Using the semiconductor structure shown in  FIG.  1    as an example, referring to  FIG.  7    to  FIG.  10   ,  FIG.  7    to  FIG.  10    and  FIG.  1    each representatively illustrate a schematic layer diagram of a semiconductor structure in a plurality of steps of a method of manufacturing a semiconductor structure. 
     Specifically,  FIG.  7    specifically illustrates a schematic layer diagram of a semiconductor structure in step S 1 . In this embodiment, in step S 1 , the semiconductor structure includes the device layer  110  and the first conductive layer M 2 . The first conductive layer M 2  is provided on a top surface of the device layer  110 . 
     Optionally, in step S 2 , part of the first conductive layer may be removed through an etching process to form at least two traces, a recess is formed between two adjacent ones of the traces, and an etching stop location in the etching process defines a recess bottom location of the recess. For example, in a first embodiment of the semiconductor structure, when part of the first conductive layer is removed through an etching process to form a recess, an etching stop location of the etching process is the top surface of the device layer. For another example, in a second embodiment of the semiconductor structure, when part of the first conductive layer is removed through an etching process to form a recess, an etching stop location of the etching process is a top surface of a second barrier layer, that is, the etching process removes not only part of the first conductive layer but also part of the first dielectric layer. 
     Further, based on the process design of removing part of the first conductive layer through an etching process to form a recess, step S 2  may include the following steps: 
     S 21 : Provide a photoresist layer on the top surface of the first conductive layer. 
     S 22 : Pattern the photoresist layer to form a photolithography pattern opening. 
     S 23 : Etch the first conductive layer by using the patterned photoresist layer as a mask to form a recess, where a location of the recess corresponds to the photolithography pattern opening. 
     Specifically,  FIG.  8    specifically illustrates a schematic layer diagram of the semiconductor structure in step S 22 . In step S 22 , the semiconductor structure includes the device layer  110 , the first conductive layer M 2 , and a patterned photoresist layer  140 . The photoresist layer  140  is provided on the top surface of the first conductive layer M 2 , and the photoresist layer  140  is patterned to form a photolithography pattern opening  141 . 
     Specifically,  FIG.  9    specifically illustrates a schematic layer diagram of the semiconductor structure in step S 23  (or step  2 ). In step S 22 , the semiconductor structure includes the device layer  110  and the first trace m remaining after the first conductive layer M 2  is partially removed. A part of the first conductive layer M 2  exposed in the photolithography pattern opening  141  is removed by etching to form a plurality of first traces m, and a recess Via 0  is formed between two adjacent ones of the first traces m. 
     Specifically,  FIG.  10    specifically illustrates a schematic layer diagram of the semiconductor structure in step S 3 . In step S 3 , the semiconductor structure includes the device layer  110 , the first conductive layer M 2 , and the first barrier layer  120 . The first barrier layer  120  is provided on a sidewall of the recess Via 0 . On this basis, the first barrier layer  120  may alternatively be provided on a bottom wall of the recess Via 0 . 
     Optionally, in step S 3 , the first barrier layer may be formed through a deposition process, for example, but not limited to, an atomic layer deposition (ALD) process or a chemical vapor deposition (CVD) process. 
     Specifically,  FIG.  1    specifically illustrates a schematic layer diagram of the semiconductor structure in step S 4 . In step S 4 , the semiconductor structure includes the device layer  110 , the first conductive layer M 2 , the first barrier layer  120 , and the insulating layer  130 . The insulating layer  130  is provided on the top surface of the first conductive layer M 2 , and the insulating layer  130  fills the recess Via 0 . The air gap G is formed in the insulating layer  130  located in the recess Via 0 . 
     Optionally, in step S 4 , the insulating layer  130  may alternatively cover the top surface of the first conductive layer M 2 . 
     Optionally, in step S 4 , the insulating layer  130  may be formed through a deposition process, and a location and a size of the air gap G can be controlled by using high density plasma during the deposition. 
     Using the semiconductor structure shown in  FIG.  4    as an example, referring to  FIG.  11    to  FIG.  15   ,  FIG.  11    to  FIG.  15    and  FIG.  4    each representatively illustrate a schematic layer diagram of a semiconductor structure in a plurality of steps of a method of manufacturing a semiconductor structure. 
     As shown in  FIG.  11   , before the preparation of the first conductive layer M 2  in step S 1 , a second conductive layer M 1 , a second dielectric layer  440 , and a second barrier layer  450 , a first dielectric layer  410 , and a first interconnect structure Via 1  are first sequentially formed on the device layer  110 , and then steps S 1  to S 4  are performed on the first dielectric layer  410 . The first conductive layer M 2  is provided on a top surface of the first dielectric layer  410 . The second conductive layer M 1  includes a plurality of second traces. The second dielectric layer  440  is provided between two adjacent ones of the second traces and located below the first dielectric layer  410 . The second barrier layer  450  is provided between the second dielectric layer  440  and the first dielectric layer  410 . The second conductive layer M 1  is connected to the first conductive layer M 2  through the first interconnect structure Via 1  running through the first dielectric layer  410  and the second barrier layer  450 . 
     It should be noted that, in various possible embodiments meeting the design ideas of the present disclosure, the method of manufacturing a semiconductor structure is applicable to a semiconductor structure including one conductive layer or a semiconductor structure including two or more conductive layers. For example, when the semiconductor structure includes two or more conductive layers, a device layer including two or more conductive layers may be provided in step S 1 , and a recess may be provided on a conductive layer located on top in step S 2 . 
     Optionally, in step S 2 , part of the first conductive layer M 2  may be removed through an etching process to form a plurality of first traces m, and a recess Via 2  is formed between two adjacent ones of the first traces m. Specifically, an etching stop location in this embodiment is a top surface of the second barrier layer  450 , that is, the etching process removes not only part of the first conductive layer M 2  but also part of the first dielectric layer  410 . 
     Specifically, as shown in  FIG.  12   , in step S 22 , the semiconductor structure includes a device layer and a photoresist layer  460 . The photoresist layer  460  is provided on the top surface of the first conductive layer M 2 , and the photoresist layer  460  is patterned to form a photolithography pattern opening  461 . 
     Specifically, as shown in  FIG.  13   , in step S 23  (or step  2 ), a part of the first conductive layer M 2  exposed in the photolithography pattern opening  461  is removed by etching to form a plurality of first traces m, and a recess Via 2  is formed between two adjacent ones of the first traces m. 
     Specifically, as shown in  FIG.  14   , in step S 3 , the semiconductor structure includes a device layer and a first barrier layer  420 . The first barrier layer  420  is provided on a bottom wall and a sidewall of the recess Via 2 . 
     Specifically, as shown in  FIG.  15   , in step S 4 , the semiconductor structure includes a device layer, a first barrier layer  420 , and a first insulating layer  431 . The first insulating layer  431  fills the recess Via 2 , and an air gap G is formed in the first insulating layer  431  located in the recess Via 2 . 
     Optionally, in step S 4 , the first insulating layer  431  may alternatively cover the top surface of the first conductive layer M 2 . 
     Optionally, as shown in  FIG.  15   , in step S 4 , the first insulating layer  431  may be formed through a deposition process, and a location and a size of the air gap G can be controlled by using high density plasma during the deposition. For example, an extension length of the air gap G may be controlled to be slightly less than (approximately equal to) a thickness of the first conductive layer M 2  in a reference direction. Through the foregoing design, the air gap G can extend to the first dielectric layer  410  in the reference direction, such that the dielectric property between the first conductive layer M 2  and the first dielectric layer  410  can be effectively reduced, thereby helping reduce an RC delay. 
     Optionally, as shown in  FIG.  4   , after the step of providing the first insulating layer  431 , a second insulating layer  432  may be further provided on a top surface of the first insulating layer  431 . 
     It should be noted herein that the method of manufacturing a semiconductor structure shown in the drawings and described in this specification only show a few examples of many manufacturing methods that can adopt the principle of the present disclosure. It should be clearly understood that the principle of the present disclosure is by no means limited to any details or any steps of the method of manufacturing a semiconductor structure shown in the drawings or described in this specification. 
     In summary, the semiconductor structure provided in the present disclosure includes a first conductive layer, a first barrier layer, and an insulating layer, the first conductive layer includes at least two traces, and a recess is formed between two adjacent ones of the traces. In the present disclosure, the first barrier layer is provided on the sidewall of the recess, which can effectively prevent external water vapor from penetrating the first conductive layer and other structures through the insulating layer. In addition, an electromigration phenomenon between adjacent traces of the first conductive layer can be effectively prevented by using the first barrier layer. 
     The present disclosure is described above with reference to several typical implementations. It should be understood that the terms used herein are intended for illustration, rather than limiting. The present disclosure may be specifically implemented in many forms without departing from the spirit or essence of the present disclosure. Therefore, it should be understood that the above embodiments are not limited to any of the above-mentioned details, but should be broadly interpreted according to the spirit and scope defined by the appended claims. Therefore, any changes and modifications falling within the claims or the equivalent scope thereof should be covered by the appended claims.