Patent Publication Number: US-2022240375-A1

Title: Co-axial via structure and manufacturing method of the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application Ser. No. 63/142,994, filed Jan. 28, 2021 and Taiwan Application Series 110137649, filed Oct. 8, 2021, which are herein incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     Field of Invention 
     The present invention relates to a co-axial via structure and a manufacturing method of the co-axial via. 
     Description of Related Art 
     It is required to add extra dielectric layers between a grounding line and a signal line by a compression process for manufacture a conventional co-axial via structure which may cause greater budget consumption. In addition, inner circuits and outer lines within a via structure are located at different levels, and therefore impedance mismatch problem may occur. The dielectric layer deposited between the grounding line and the signal line may also have shielding notch which may cause poor magnetic shielding efficiency. 
     Accordingly, it is still a development direction for the industry to provide a co-axial via structure which can improve impedance match efficiency and magnetic shielding efficiency. 
     SUMMARY 
     One aspect of the present disclosure is a co-axial structure. 
     In some embodiments, the co-axial structure includes a substrate, a first conductive structure, a second conductive structure, and an insulating layer. The substrate includes a first surface. The first conductive structure includes a first circuit deposited on the first surface and a first via penetrating the substrate. The second conductive structure includes a second circuit deposited on the first surface and a second via penetrating the substrate. The first via and the second via extend along a first direction. The first circuit and the second circuit extend along a second direction, and the second direction is perpendicular to the first direction. The insulating layer is located between the first via and the second via. The first conductive structure and the second conductive structure are electrically insulated. The first circuit and the second circuit are coplanar. 
     In some embodiments, the first via of the first conductive structure surrounds the second via of the second conductive structure and the insulating layer. 
     In some embodiments, the insulating layer, the first via, and the second via are co-axial. 
     In some embodiments, the insulating layer includes a protruding portion located at an end of the insulating layer close to the first surface. 
     In some embodiments, the protruding portion of the insulating layer protrudes away from the second through hole along the second direction. 
     In some embodiments, the first via of the first conductive structure, the protruding portion of the insulating layer, and the second circuit of the second conductive structure overlap along the first direction. 
     In some embodiments, the substrate further includes a second surface opposite to the first surface, the co-axial structure further includes a dielectric layer located between the first surface and the second surface, and the protruding portion of the insulating layer is in contact with the dielectric layer. 
     Another aspect of the present disclosure is a manufacturing method of a co-axial structure. 
     In some embodiments, the manufacturing method of a co-axial structure includes forming a first through hole in a substrate; forming a first conductive material on a first surface of the substrate and in the first through hole; forming a trench recessed from the first surface such that the trench communicates with the first through hole; forming an insulating layer in the first through hole and the trench; forming a second conductive material on the first surface of the substrate and in the first through hole; and pattering the first conductive material and the second conductive material so as to form a first circuit and a second circuit on the first surface such that the first conductive material remained and the second conductive material remained are electrically insulated through the insulating layer in the trench, and the first circuit and the second circuit are coplanar. 
     In some embodiments, the co-axial structure further includes a second surface opposite to the first surface, and forming the trench further includes drilling from the first surface along the first direction. 
     In some embodiments, the co-axial structure further includes a dielectric layer located between the first surface and the second surface, and forming the trench further includes exposing the dielectric layer from the first conductive material. 
     In some embodiments, forming the insulating layer in the first through hole and the trench further includes forming an insulating layer material in the first through hole and the trench such that the insulating layer material is in contact with the dielectric layer; and forming a second through hole in the insulating layer material so as to form the insulating layer, wherein the insulating layer includes a protruding portion located in the trench. 
     In some embodiments, forming the second conductive material on the first surface of the substrate and in the first through hole such that the insulating layer, the first conductive material in the first via, and the second conductive material in the second via are co-axial. 
     In some embodiments, forming the second conductive material on the first surface of the substrate and in the first through hole further includes forming the second conductive material in the second through hole such that the first conductive material in the first through hole surrounds the insulating material and the second conductive material in the second through hole. 
     In some embodiments, patterning the first conductive material and the second conductive material so as to form the first circuit and the second circuit such that the first conductive material in the first via, the protruding portion of the insulating layer, and the second circuit overlap along the first direction. 
     In the aforementioned embodiments, since the first circuit and the second circuit of the co-axial via structure are coplanar and the first conductive structure and the second conductive structure are electrically insulated through the insulating layer, the co-axial via structure of the present disclosure can have better magnetic noise shielding efficiency and impedance match efficiency that can improve high frequency signal integrality. In addition, the number of the dielectric layers can be reduced so as to reduce the thickness of the co-axial structure. Therefore, manufacture cost of the co-axial via structure of the present disclosure can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
         FIG. 1  is a three-dimensional view of the co-axial via structure according to one embodiment of the present disclosure; 
         FIG. 2  is a cross-sectional view taken along line  2 - 2  in  FIG. 1 ; 
         FIGS. 3A to 11A  are top views of intermediate steps of a manufacturing method of a co-axial via structure according to another embodiment of the present disclosure; and 
         FIGS. 3B to 11B  are cross-sectional views taken along line  3 B- 3 B to line  11 B- 11 B in  FIGS. 3A to 11A , respectively. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG. 1  is a three-dimensional view of the co-axial via structure  100  according to one embodiment of the present disclosure.  FIG. 2  is a cross-sectional view taken along line  2 - 2  in  FIG. 1 . Reference is made to  FIG. 1  and  FIG. 2  simultaneously. The co-axial via structure  100  includes a substrate  110 , a first conductive structure  120 , a second conductive structure  130 , and an insulating layer  140 . 
     The substrate  110  includes a first surface  112  and a second surface  114  opposite to each other. The first conductive structure  120  includes a first circuit  122  and a first via  124 , and the second conductive structure  130  includes a second circuit  132  and a second via  134 . The first circuit  122  and the second circuit  132  are deposited on the first surface  112 . The first via  124  and the second via  134  penetrate the substrate  110 . The first via  124  and the second via  134  extend along a first direction D 1 . The first circuit  122  and the second circuit  132  extend along a second direction D 2  perpendicular to the first direction D 1 . The first circuit  122  of the first conductive structure  120  and the second circuit  132  of second conductive structure  130  are coplanar. In other words, the first circuit  122  and the second circuit  132  are located at the same horizontal plane. 
     In the present embodiment, the first direction D 1  is the vertical direction herein. That is, the first direction D 1  is a direction from the first surface  112  to the second surface  114 . The second direction D 2  can be arbitrary horizontal direction that is perpendicular to the first direction D 1 . In the present embodiment, the first circuit  122  and the third circuit  126  can be ground lines, and the second circuit  132  and the fourth circuit  136  can be signal lines, but the present disclosure is not limited in those regards. 
     As shown in  FIG. 2 , the first conductive structure  120  further includes a third circuit  126  located on the second surface  114 , and the second conductive structure  130  further includes a fourth circuit  136  located on the second surface  114 . Two ends of the first via  124  are connected with the first circuit  122  and the third circuit  126  respectively. Two ends of the second via  134  are connected with the second circuit  132  and the fourth circuit  136  respectively. The third circuit  126  and the fourth circuit  136  extend along the second direction D 2 , and the third circuit  126  and the fourth circuit  136  are coplanar. In other words, the third circuit  126  and the fourth circuit  136  are located at the same horizontal plane. 
     The insulating layer  140  is located between the first via  124  and the second via  134 , and the insulating layer  140  extend along the first direction D 1 . The first via  124  surrounds the second via  134  and the insulating layer  140 , and the insulating layer  140  surrounds the second via  134 . As shown in  FIG. 2 , the insulating layer  140 , the first via  124 , and the second via  134  are co-axial relative to an axis A. 
     The insulating layer  140  includes a first protruding portion  142 , and the first protruding portion  142  is located at one end of the insulating layer  140  close to the first surface  112 . The first protruding portion  142  protrudes away from the second via  134  along the second direction D 2 . As shown in  FIG. 2 , the substrate  110  further includes dielectric layers  150  located between the first surface  112  and the second surface  114 . In the present embodiment, the substrate  110  further includes multiple inner circuits  116  separated through the dielectric layers  150 , but the present disclosure is not limited in this regard. The first protruding portion  142  of the insulating layer  140  is in contact with the dielectric layers  150  close to the first surface  112 . In other words, the first protruding portion  142  penetrates through the first via  124  and extends to the dielectric layers  150 . 
     It is noted that, in order to describe the structural relation between the second circuit  132  and the first protruding portion  142 , only the first via  124 , the second circuit  132 , and the insulating layer  140  are illustrated in  FIG. 1 , and the first circuit  122  is omitted. 
     As shown in  FIG. 2 , the first via  124  of the first conductive structure  120 , the first protruding portion  142  of the insulating layer  140 , and the second circuit  132  of the second conductive structure  130  overlap along the first direction D 1 . The second circuit  132  of the second conductive structure  130  extends from the second via  134  and cross the first protruding portion  142 . In other words, the first via  124  and the second circuit  132  are electrically insulated through the first protruding portion  142 , and the first circuit  122  and the second circuit  132  which are co-axial are separated from each other. As such, the first conductive structure  120  and the second conductive structure  130  are electrically insulated. 
     Accordingly, since the first circuit  122  and the second circuit  132  of the co-axial via structure  100  are coplanar and the first conductive structure  120  and the second conductive structure  130  are electrically insulated, the step of forming extra dielectric layers to electrically insulate a first circuit and a second circuit located at different layers can be omitted. As such, the first via  124  and the second via  134  can have substantially the same height, and therefore the overall structure of the co-axial via structure  100  is more symmetrical so as to improve impedance match efficiency. In addition, since the dielectric layers located at different layers can be omitted, the second via  134  can be prevented from penetrating throughout the insulating layer. As such, the co-axial via structure  100  can avoid poor magnetic shielding due to notch of the shielding structure. 
     As shown in  FIG. 2 , the insulating layer  140  further includes a second protruding portion  144 , and the second protruding portion  144  is located at one end of the insulating layer  140  close to the second surface  114 . The second protruding portion  144  protrudes away from the second via  134  along the second direction D 2 . The second protruding portion  144  of the insulating layer  140  is in contact with the dielectric layers  150  close to the second surface  114 . In other words, the second protruding portion  144  penetrates through the first via  124  and extends to the dielectric layers  150 . 
     As shown in  FIG. 2 , the first via  124  of the first conductive structure  120 , the second protruding portion  144  of the insulating layer  140 , and the fourth circuit  136  of the second conductive structure  130  overlap along the first direction D 1 . The fourth circuit  136  of the second conductive structure  130  extends from the second via  134  and cross the second protruding portion  144 . In other words, the first via  124  and the fourth circuit  136  are electrically insulated through the second protruding portion  144 , and the third circuit  126  and the fourth circuit  136  are separated from each other. As such, the first conductive structure  120  and the second conductive structure  130  are electrically insulated. 
     As described above, the extension direction of the fourth circuit  136  can be arbitrary horizontal direction that is perpendicular to the first direction D 1 .  FIG. 2  is merely an example, and the present disclosure is not limited in this regard. 
     It is to be noted that the connection relationships, materials, and advantages of the elements described above will not be repeated. In the following description, a manufacturing method of the co-axial structure will be described. 
       FIGS. 3A to 11A  are top views of intermediate steps of a manufacturing method of a co-axial via structure according to another embodiment of the present disclosure.  FIGS. 3B to 11B  are cross-sectional views taken along line  3 B- 3 B to line  11 B- 11 B in  FIGS. 3A to 11A , respectively. As shown in  FIG. 3A  and  FIG. 3B , the manufacturing method of the co-axial structure starts from formed the first through hole OP 1  in a substrate  110 . The first through hole OP 1  penetrates through the inner circuits  116  and the dielectric layers  150  of the substrate  110 . For example, the method of forming the first through hole OP 1  can be laser drilling. 
     As shown in  FIG. 4A  and  FIG. 4B , in the manufacturing method of the co-axial via structure, a first conductive material  120 M is subsequently formed on the first surface  112 , on the second surface  114 , and on an inner wall of the first through hole OP 1 . For example, the method of forming the first conductive material  120 M can be electroplating, and the first conductive material  120 M includes copper, but the present disclosure is not limited in these regards. A person having ordinary skill in the art can choose suitable method and materials based on practical condition. 
     As shown in  FIG. 5A  and  FIG. 5B , in the manufacturing method of the co-axial via structure, a first trench TR 1  is subsequently formed. The first trench TR 1  is recessed from the first surface  112 , and the first trench TR 1  and the first through hole OP 1  communicate with each other. The method of forming the first trench TR 1  includes drilling from the first surface  112  through the first direction D 1  such that the dielectric layer  150  close to the first surface  112  can be exposed from the first conductive material  120 M. 
     Reference is made to  FIG. 5B , this step further includes forming a second trench TR 2 . The second trench TR 2  is recessed from the second surface  114 , and the second trench TR 2  and the first through hole OP 1  communicate with each other. The method of forming the second trench TR 2  includes drilling from the second surface  114  through a reversed direction of the first direction D 1  such that the dielectric layer  150  close to the second surface  114  can be exposed from the first conductive material  120 M. The method of forming the first trench TR 1  and the second trench TR 2  can be laser drilling. 
     In a top view of  FIG. 5A , a distance between the first trench TR 1  and the first through hole OP 1  can be derived from the width of the second circuit  132  and an required interval between the first circuit  122  and the second circuit  132 . Similarly, in a bottom view (not shown), a distance between the second trench TR 2  and the first through hole OP 1  can be derived from the width of the fourth circuit  136  and an required interval between the third circuit  126  and the fourth circuit  136 . 
     As shown in  FIG. 6A  and  FIG. 6B , in the manufacturing method of the co-axial via structure, an insulating layer material  140 M is filled in the first through hole OP 1 , the first trench TR 1 , and the second trench TR 2  such that the insulating layer material  140 M is in contact with the dielectric layer  150  exposed form the first conductive material  120 M. In the present embodiment, the insulating layer material  140 M, for example, can include filling paste, but the present disclosure is not limited in this regard. After filling the insulating layer material  140 M, the portion of the insulating layer material  140 M protruding from the first surface  112  and the second surface  114  are polished such that a top surface and a bottom surface of the insulating layer  140 M are level with the first conductive material  120 M, respectively. 
     As shown in  FIG. 7A  and  FIG. 7B , in the manufacturing method of the co-axial via structure, a second through hole OP 2  is subsequently formed in the insulating layer material  140 M. In the present embodiment, the second through hole OP 2  and the first through hole OP 1  are concentric. For example, the method of forming the second through hole OP 2  can be laser drilling so as to remove a portion of the insulating layer material  140 M. After forming the second through hole OP 2 , the remained insulating layer material  140 M includes a portion that is located in the first through hole OP 1  (i.e., the insulating layer  140 ) and a first protruding portion  142  and a second protruding portion  144  that are respectively located at two opposites of the substrate  110 . 
     As shown in  FIG. 8A  and  FIG. 8B , in the manufacturing method of the co-axial via structure, a second conductive material  130 M is subsequently formed on the first surface  112 , on the second surface  114 , and on an inner wall of the second through hole OP 2 . For example, the method of forming the second conductive material  130 M can be electroplating, and the second conductive material  130 M includes copper, but the present disclosure is not limited in these regards. A person having ordinary skill in the art can choose suitable method and materials based on practical condition. 
     The second conductive material  130 M is in the second through hole OP 2 , and the first conductive material  120 M in the first through hole OP 1  (i.e., the first via  124 ) surrounds the insulating layer  140  and the second conductive material  130 M in the second through hole OP 2  (i.e., the second via  134 ) such that the insulating layer  140 , the first conductive material  120 M in the first through hole OP 1 , and the and the second conductive material  130 M in the second through hole OP 2  are co-axial relative to the axis A. 
     As shown in  FIG. 9A  and  FIG. 9B , in the manufacturing method of the co-axial via structure, a photomask  160  is subsequently formed on the first surface  112  and the second surface  114 . The photomask  160  includes patterns used to from the first circuit  122  and the second circuit  132  and patterns used to from the third circuit  126  and the fourth circuit  136 . 
     As shown in  FIG. 10A  and  FIG. 10B , in the manufacturing method of the co-axial via structure, the first conductive material  120 M and the second conductive material  130 M are subsequently patterned by using the photomask  160 . Subsequently, the first conductive material  120 M and the second conductive material  130 M exposed from the photomask  160  are continuously removed until the insulating layer  140  and the dielectric layer  150  are exposed from the photomask  160 . 
     Reference is made to  FIG. 10A ,  FIG. 10B ,  FIG. 11A , and  FIG. 11B . In the manufacturing method of the co-axial via structure, the photomask  160  is removed later so as to form a insulating protection layer  170 . The insulating protection layer  170  includes an opening for connecting with the conductive elements such as metal bump, bump, or solder ball (not shown). 
     As shown in  FIG. 11B , after those steps mentioned above, the first circuit  122  and the second circuit  132  separated from each other are formed, and the first circuit  122  and the second circuit  132  are coplanar. The first via  124  and the second circuit  132  are electrically insulated through the first protruding portion  142  of the first trench TR 1 . The first circuit  122  can include arbitrary circuit pattern as long as the first circuit  122  and the second circuit  132  can be electrically insulated. 
     Similarly, after those steps mentioned above, the third circuit  126  and the fourth circuit  136  separated from each other are formed, and the third circuit  126  and the fourth circuit  136  are coplanar. The first via  124  and the fourth circuit  136  are electrically insulated through the second protruding portion  144  of the second trench TR 2 . The third circuit  126  can include arbitrary circuit pattern (not shown) as long as the third circuit  126  and the fourth circuit  136  can be electrically insulated. 
     Reference is made to  FIG. 11A . In the present embodiment, the second circuit  132  has a width W 1 , and a junction between the insulating layer  140  and the first protruding portion  142  has a width W 2 . The width W 2  can be adjusted by changing the distance between the first trench TR 1  and the first through hole OP 1 , and the W 2  can be determined on the hole diameter of the first trench TR 1 . Therefore, based on the required width W 1 , a suitable distance between the first trench TR 1  and the first through hole OP 1  can be calculated in the step of forming the first trench TR 1 . As such, the width W 2  is guaranteed to be width enough to avoid broken of the second circuit  132 . The second circuit  132  and the adjacent first circuit  122  have an interval I therebetween. Under constraints for deriving specific impedance, the interval I can be determined according to a thickness and the width W 1  of the second circuit  132 , and parameters of the dielectric layer  150  so as to improve impedance match efficiency. 
     In summary, since the ground line and the signal line (first circuit and the second circuit) of the co-axial via structure are coplanar and the first conductive structure and the second conductive structure are electrically insulated through the insulating layer, the co-axial via structure of the present disclosure can have better magnetic noise shielding efficiency and impedance match efficiency that can improve high frequency signal integrality. In addition, the number of the dielectric layers can be reduced so as to reduce the thickness of the co-axial structure. Therefore, manufacture cost of the co-axial via structure of the present disclosure can be reduced. 
     Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.