Transmission line structure, preparation method and application thereof

Abstract

The invention provides a transmission line structure, a preparation method and application thereof, the transmission line structure comprises a substrate, an insulating medium layer and a conductive wiring layer, the substrate is provided with a plurality of through holes penetrating through the substrate, the inner walls of the through holes are arranged in an inclined manner, the insulating medium layer covers the first surface and the second surface of the substrate and the inner walls of the through holes, and the conductive wiring layer covers the first surface and the second surface of the substrate. The conductive wiring layer is located on the surface of the insulating dielectric layer and comprises a center wire which serves as a signal wire. According to the invention, by directly forming the central lead (namely the in-hole transmission line) on the inner wall of the through hole, the consistency of the structural design of the central lead (planar transmission line) on the first surface and the second surface is realized, so that impedance matching is ensured; signal loss caused by impedance mismatching when signals are transmitted between the in-hole transmission line and the planar transmission line is avoided, so that the integrity and efficiency of signal transmission are remarkably improved, and stable transmission of higher-frequency signals is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of chip packaging and relates to a transmission line structure, a preparation method and application thereof. Background Art

[0002] Through Silicon Via (TSV) technology is a packaging technology that realizes vertical interconnection between chips. With the advantage of vertical interconnection, it has become an important technology for realizing three-dimensional chip packaging. However, when realizing the longitudinal transmission of signals through TSV, an unavoidable problem is the impedance transformation that occurs when the signal transitions from the planar transmission line structure to the through-hole structure. In order to solve this problem, a quasi-coaxial structure combined with a planar transmission line on the surface is usually used for signal transmission. However, this non-uniform transmission structure often brings many unexpected losses, which becomes a difficulty that limits TSV to realize high-frequency signal transmission. In addition, since the quasi-coaxial structure often needs to be realized by dry etching, it is expensive and the yield rate is not high, the process consistency is poor, and it is difficult to guarantee the quality.

[0003] Therefore, how to provide a transmission line structure, preparation method and application thereof to achieve effective transmission of high-frequency signals while reducing production costs, simplifying manufacturing processes and improving process consistency has become an important technical problem that technical personnel in this field need to solve urgently.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the object of the present invention is to provide a transmission line structure, a preparation method and its application, which are used to solve the problems of the signal transmission method combining a quasi-coaxial structure with a planar transmission line in the prior art, which is difficult to achieve effective transmission of high-frequency signals, high production costs, complex manufacturing processes and poor process consistency.

[0006] To achieve the above objectives and other related objectives, the present invention provides a transmission line structure, comprising:

[0007] A substrate, the substrate comprising a first surface and a second surface arranged opposite to each other, the substrate being provided with a plurality of through holes penetrating the substrate, and inner walls of the through holes being arranged obliquely;

[0008] an insulating dielectric layer, covering the first surface, the second surface and the inner wall of the through hole;

[0009] A conductive wiring layer is located on the surface of the insulating dielectric layer, the conductive wiring layer includes a center conductor, and the center conductor includes a first section, a second section, and a third section connected in sequence, wherein the first section is located on the first surface, the second section is located on the inner wall of the through hole, the third section is located on the second surface, and the center conductor serves as a signal line.

[0010] Optionally, the transmission line structure comprises a first through hole and a second through hole which are spaced apart from each other, wherein the central conductor passing through the first through hole and the central conductor passing through the second through hole are arranged opposite to each other on the first surface and are spaced apart by a preset distance.

[0011] Optionally, the central conductor passing through the first through hole is connected to the central conductor passing through the second through hole on the second surface.

[0012] Optionally, the line width of the second segment changes gradually along the extension direction of the inner wall of the through hole.

[0013] Optionally, the material of the conductive wiring layer includes a superconducting material or a non-superconducting metal material, the superconducting transition temperature of the superconducting material ranges from 0 to 300K, and the superconducting material includes any one of niobium, niobium nitride, aluminum, and titanium nitride, and the non-superconducting metal material includes any one of copper, gold, silver, nickel, palladium and platinum.

[0014] Optionally, the conductive wiring layer further includes side wires spaced apart on both sides of the central wire, and the side wires serve as ground wires.

[0015] Optionally, any two or more of the through holes are combined and arranged in the substrate according to a preset rule to form a specific geometric shape.

[0016] Optionally, it also includes a bottom structural layer located below the insulating dielectric layer, the bottom structural layer includes a bottom insulating dielectric layer and a bottom metal layer located above the bottom insulating dielectric layer, the bottom insulating dielectric layer covers the first surface, the second surface and the inner wall of the through hole, the bottom metal layer serves as a ground plane, and the insulating dielectric layer covers the surface of the bottom metal layer.

[0017] To achieve the above object and other related objects, the present invention also provides a method for preparing a transmission line structure, comprising the following steps:

[0018] Providing a substrate, the substrate comprising a first surface and a second surface arranged opposite to each other, and etching at least one of the first surface and the second surface to form a plurality of through holes penetrating the substrate and having inclined inner walls;

[0019] forming an insulating dielectric layer covering the first surface, the second surface and the inner wall of the through hole;

[0020] forming a conductive layer on the insulating dielectric layer;

[0021] A shielding layer is formed on the conductive layer, the shielding layer is patterned to form an opening exposing the conductive layer, and the conductive layer is etched based on the opening, wherein the unetched portion of the conductive layer forms the conductive wiring layer, the conductive wiring layer includes a center conductor, the center conductor includes a first segment, a second segment, and a third segment connected in sequence, wherein the first segment is located on the first surface, the second segment is located on the inner wall of the through hole, the third segment is located on the second surface, and the center conductor serves as a signal line.

[0022] Optionally, while forming the central conductive line, side conductive lines are also formed in the conductive wiring layer on both sides of the central conductive line, and the side conductive lines serve as grounding lines.

[0023] Optionally, after forming the through hole and before forming the insulating dielectric layer, a step of forming an underlying structural layer is further included.

[0024] Optionally, forming the underlying structural layer comprises the following steps:

[0025] forming a bottom insulating dielectric layer covering the first surface, the second surface and the inner wall of the through hole;

[0026] A bottom metal layer is formed on the insulating dielectric layer, and the insulating dielectric layer covers the surface of the bottom metal layer.

[0027] To achieve the above objectives and other related objectives, the present invention also provides an application of a transmission line structure, wherein the application applies the above transmission line structure to high-frequency signal transmission in superconducting integrated circuits, high-frequency signal transmission in semiconductor integrated circuits, or high-frequency signal transmission in non-superconducting integrated circuits.

[0028] As described above, the present invention provides a transmission line structure, a preparation method and an application thereof, wherein the transmission line structure includes a substrate, an insulating dielectric layer and a conductive wiring layer, wherein the substrate includes a first surface and a second surface arranged opposite to each other, a plurality of through holes penetrating the substrate are provided in the substrate, and the inner wall of the through hole is arranged obliquely, the insulating dielectric layer covers the first surface, the second surface and the inner wall of the through hole, the conductive wiring layer is located on the surface of the insulating dielectric layer, and the conductive wiring layer includes a center conductor, and the center conductor serves as a signal line. The present invention achieves consistency with the structure design of the center conductor (planar transmission line) on the first surface and the second surface by directly forming the center conductor (i.e., the transmission line in the hole) on the inner wall of the through hole, thereby ensuring impedance matching, avoiding signal loss caused by impedance mismatch when the signal is transmitted between the transmission line in the hole and the planar transmission line, thereby significantly improving the integrity and efficiency of signal transmission, and helping to achieve stable transmission of higher frequency signals. At the same time, the size design of the transmission line in the hole and the through hole is flexible, and through holes of different sizes can be made according to requirements, thereby supporting the design of a transmission line structure with a smaller line width and a higher density. By increasing the number of transmission lines in the hole, the interconnection density can be further improved and the signal loss can be reduced. The types of through-silicon transmission line structures formed by the present invention include coplanar waveguides and microstrip lines, and support expansion into other types of transmission line structures such as grounded coplanar waveguides, differential lines and strip lines, providing a flexible basis for a variety of design requirements. In addition, the present invention uses a wet etching process with crystal plane selectivity to process the inner wall of the through hole, so that the inner wall is inclined. This process method has strong processing capabilities and process consistency, and the process flow is simple, easy to operate, and low in cost, which can significantly improve manufacturing efficiency. The through-silicon transmission line structure of the present invention not only effectively solves the problem of possible loss when the signal is transmitted between the horizontal and vertical directions, but also improves the stability of high-frequency signal transmission. It has broad application prospects in the field of high-frequency signal transmission and silicon through-hole interconnection technology, and can provide important technical support for the design of high-density packaging and multi-layer integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic cross-sectional structure diagram of an example of a transmission line structure according to the first embodiment of the present invention is shown.

[0030] Figure 2 A schematic cross-sectional structure diagram of another example of the transmission line structure according to the first embodiment of the present invention is shown.

[0031] Figure 3 It is a top view schematic diagram of a transmission line structure according to the first embodiment of the present invention.

[0032] Figure 4 It is a bottom schematic diagram of the transmission line structure according to the first embodiment of the present invention.

[0033] Figure 5Shown is a schematic diagram of the wiring of the inner wall of the double trapezoidal through hole in the transmission line structure of the first embodiment of the present invention.

[0034] Figure 6 Another schematic diagram showing the wiring of the inner wall of the double trapezoidal through hole in the transmission line structure of the first embodiment of the present invention.

[0035] Figure 7 Shown is a schematic diagram of the wiring of the inner wall of a single trapezoidal through hole in the transmission line structure of the first embodiment of the present invention.

[0036] Figure 8 Another schematic diagram showing the wiring of the inner wall of a single trapezoidal through hole in the transmission line structure of the first embodiment of the present invention.

[0037] Fig. 9 It is a schematic top view showing an L-shape formed by arranging any two through-hole combinations in the transmission line structure of the first embodiment of the present invention.

[0038] Fig.10 It is a schematic diagram showing the top surface of an n-type structure formed by arbitrarily arranging a combination of three through holes in the transmission line structure of the first embodiment of the present invention.

[0039] Fig.11 A schematic cross-sectional structure diagram of an example of a transmission line structure according to the second embodiment of the present invention is shown.

[0040] Fig.12 A schematic cross-sectional structure diagram of another example of a transmission line structure according to the second embodiment of the present invention is shown.

[0041] Fig.13 It shows a process flow chart of a method for preparing a transmission line structure according to the third embodiment of the present invention.

[0042] Fig.14 It is a schematic diagram of the cross-sectional structure after forming a plurality of double trapezoidal through holes in a substrate in the method for preparing a transmission line structure according to the third embodiment of the present invention.

[0043] Fig.15 It is a schematic diagram of a cross-sectional structure after forming a plurality of single trapezoidal through holes in a substrate in the method for preparing a transmission line structure according to the third embodiment of the present invention.

[0044] Fig.16 It is a schematic diagram of a cross-sectional structure after forming an insulating dielectric layer on a substrate having double trapezoidal through holes in a method for preparing a transmission line structure according to a third embodiment of the present invention.

[0045] Fig.17 It is a schematic diagram of a cross-sectional structure after a conductive layer is formed on a substrate having double trapezoidal through holes in a method for preparing a transmission line structure according to a third embodiment of the present invention.

[0046] Fig.18 It is a schematic diagram of a cross-sectional structure after a conductive wiring layer is formed on a substrate having double trapezoidal through holes in a method for preparing a transmission line structure according to a third embodiment of the present invention.

[0047] Fig.19 It is a schematic diagram of a cross-sectional structure after a conductive wiring layer is formed on a substrate having a single trapezoidal through hole in a method for preparing a transmission line structure according to a third embodiment of the present invention.

[0048] Fig. 20 It is a schematic cross-sectional structure diagram after forming a bottom structural layer covering the first surface, the second surface and the inner wall of the through hole on a substrate having a double trapezoidal through hole in the method for preparing the transmission line structure according to the fourth embodiment of the present invention.

[0049] Fig.21 It is a schematic cross-sectional structure diagram after forming a bottom structural layer covering the first surface, the second surface and the inner wall of the through hole on a substrate having a single trapezoidal through hole in the method for preparing the transmission line structure according to the fourth embodiment of the present invention.

[0050] Fig. 22 It is a schematic diagram of a cross-sectional structure after an insulating dielectric layer and a conductive wiring layer are formed on a substrate having double trapezoidal through holes in a method for preparing a transmission line structure according to a fourth embodiment of the present invention.

[0051] Fig.23 It is a schematic diagram of a cross-sectional structure after an insulating dielectric layer and a conductive wiring layer are formed on a substrate having a single trapezoidal through hole in a method for preparing a transmission line structure according to a fourth embodiment of the present invention.

[0052] Component number description

[0053] 11 Substrate

[0054] 111 First Surface

[0055] 112 Second Surface

[0056] 12 Through Holes

[0057] 121 Inner wall

[0058] 122 Double trapezoidal through hole

[0059] 1221 Upper trapezoidal through hole

[0060] 1222 Lower trapezoidal through hole

[0061] 1223 Slope Junction

[0062] 123 Single trapezoidal through hole

[0063] 124 First through hole

[0064] 125 Second through hole

[0065] 13 Insulation dielectric layer

[0066] 14 Conductive layer

[0067] 15 Conductive wiring layer

[0068] 151 Center conductor

[0069] 1511 First paragraph

[0070] 1512 Second paragraph

[0071] 1513 The third paragraph

[0072] 152 Side wire

[0073] 16. Bottom Structure Layer

[0074] 161 Bottom insulating dielectric layer

[0075] 162 bottom metal layer

[0076] Steps S1 to S4 DETAILED DESCRIPTION

[0077] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0078] See also Figures 1 to 23 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0079] Embodiment 1

[0080] This embodiment provides a transmission line structure. Figure 1, which is a schematic cross-sectional structure diagram of an example of the transmission line structure, includes a substrate 11, an insulating dielectric layer 13 and a conductive wiring layer 15, wherein the substrate 11 includes a first surface 111 and a second surface 112 arranged opposite to each other, a plurality of through holes 12 penetrating the substrate 11 are provided in the substrate 11, and the inner wall 121 of the through hole 12 is inclined, the insulating dielectric layer 13 covers the first surface 111, the second surface 112 and the inner wall 121 of the through hole 12, the conductive wiring layer 15 is located on the surface of the insulating dielectric layer 13, the conductive wiring layer 15 includes a central conductor 151, and the central conductor 151 includes a first segment 1511, a second segment 1512 and a third segment 1513 connected in sequence, wherein the first segment 1511 is located on the first surface 111, the second segment 1512 is located on the inner wall 121 of the through hole 12, the third segment 1513 is located on the second surface 112, and the central conductor 151 serves as a signal line.

[0081] Specifically, the substrate 11 may be a silicon substrate, a germanium silicon substrate, a III-V group element compound substrate, or other semiconductor material substrates known to those skilled in the art. In this embodiment, the substrate 11 is an N-type silicon substrate with a (100) crystal plane.

[0082] As an example, the angle between the inner wall 121 of the through hole 12 and at least one of the first surface 111 or the second surface 112 is in the range of 50° to 60°.

[0083] As an example, the through hole 12 includes a double trapezoidal through hole 122 , a single trapezoidal through hole 123 , or a through hole of other suitable shapes.

[0084] Specifically, Figure 1 As shown, in one example, the through hole 12 is a double trapezoidal through hole 122, and the double trapezoidal through hole 122 includes an upper trapezoidal through hole 1221 and a lower trapezoidal through hole 1222, the top surface openings of the upper trapezoidal through hole 1221 and the lower trapezoidal through hole 1222 are both larger than the bottom surface openings, and the upper trapezoidal through hole 1221 and the lower trapezoidal through hole 1222 are connected through their bottom surface openings to form a through hole.

[0085] In another example, if Figure 2 As shown, it is a schematic cross-sectional structure diagram of another example of the transmission line structure of this embodiment, the through hole 12 is a single trapezoidal through hole 123, and the top surface opening of the single trapezoidal through hole 123 is larger than the bottom surface opening of the single trapezoidal through hole 123.

[0086] As an example, the material of the conductive wiring layer 15 includes a superconducting material or a non-superconducting metal material, the superconducting transition temperature of the superconducting material is in the range of 0 to 300 K, and the superconducting material includes but is not limited to any one of niobium, niobium nitride, aluminum, and titanium nitride, and the non-superconducting metal material includes but is not limited to any one of copper, gold, silver, nickel, palladium, and platinum. In this embodiment, the material of the conductive wiring layer 15 is preferably a superconducting material.

[0087] Specifically, in this embodiment, the center conductor 151 extends from the first surface 111 to the inner wall 121 of the through hole, and further extends to the second surface 112. The second section 1512 located on the inner wall 121 of the through hole serves as an in-hole transmission line, the first section 1511 located on the first surface 111 and the third section 1513 located on the second surface 112 serve as a planar transmission line, and the in-hole transmission line is connected to the planar transmission line to form a continuous signal transmission path. At the same time, since the second section 1512 has the same structure as the first section 1511 and the third section 1513, the impedance uniformity of the center conductor 151 is ensured, and the additional signal loss caused by the impedance change or mismatch of the transmission line when the signal is transmitted between the planar transmission line and the in-hole transmission line is greatly reduced. In addition, the material of the center conductor 151 is made of superconducting material, which can further reduce the possibility of signal attenuation, thereby ensuring the integrity and transmission efficiency of higher frequency signal transmission.

[0088] As an example, Figure 3 and Figure 4 As shown, the transmission line structure includes a first through hole 124 and a second through hole 125 that are spaced apart, wherein the center conductor 151 passing through the first through hole 124 and the center conductor 151 passing through the second through hole 125 are disposed opposite to each other on the first surface 111 and are spaced apart by a preset distance.

[0089] As an example, the central conductive line 151 passing through the first through hole 124 and the central conductive line 151 passing through the second through hole 125 are connected on the second surface 112 .

[0090] As an example, the conductive wiring layer 15 further includes side wires 152 spaced apart on both sides of the central wire 151 , and the side wires 152 serve as ground wires.

[0091] Specifically, by adjusting the spacing between the side wires 152 and the center wire 151, an impedance transformation of 1 to 100 ohms can be achieved. In this embodiment, the specific spacing between the side wires 152 and the center wire 151 can be flexibly adjusted according to the impedance matching requirements to ensure that when the signal is transmitted between the planar transmission line and the transmission line in the hole, the impedance of the transmission line remains continuous, avoiding problems such as signal loss and reduced transmission efficiency caused by impedance mutation.

[0092] As an example, the line width of the central conductor 151 is greater than the line width of the side conductors 152. The specific line width of the central conductor 151 can be flexibly determined according to actual needs and is not specifically limited here.

[0093] As an example, the line width of the second segment 1512 changes in a gradient (linear gradient change and nonlinear gradient change) along the extension direction of the inner wall 121 of the through hole.

[0094] As an example, Figure 5 and Figure 6 As shown, when the through hole 12 is a double trapezoidal through hole 122 , the line width of the second section 1512 first increases and then decreases along the extension direction of the through hole inner wall 121 .

[0095] Specifically, the line width of the second section 1512 gradually increases from the top surface to the bottom surface of the upper trapezoidal through hole 1221 on the through hole inner wall 121, and reaches a maximum value when reaching the connection area between the upper trapezoidal through hole 1221 and the lower trapezoidal through hole 1222 (i.e., the inclined surface intersection 1223). Subsequently, the line width of the second section 1512 gradually decreases from the bottom surface to the top surface of the lower trapezoidal through hole 1222.

[0096] As an example, Figure 7 and Figure 8 As shown, when the through hole 12 is a single trapezoidal through hole 123 , the line width of the second section 1512 gradually increases along the extension direction of the inner wall 121 of the through hole.

[0097] Specifically, the line width of the second section 1512 shows a trend of gradually increasing along the top surface to the bottom surface of the single trapezoidal through hole 123 on the through hole inner wall 121 .

[0098] Specifically, whether in the double trapezoidal through hole 122 or the single trapezoidal through hole 123, the line width of the second section 1512 is designed to change in a gradient in this embodiment, so that the impedance change of the transmission line in the hole can be smoother, thereby effectively avoiding the problem of discontinuous impedance change of the transmission line in the hole caused by the change in the thickness of the substrate 11, and reducing the loss caused by the sudden change in the impedance of the center conductor 151.

[0099] Of course, in other examples, the line width of the second section 1512 can be fixed, or can present various changing trends along the extension direction of the through hole inner wall 121, such as first decreasing and then increasing, gradually decreasing, or other preset changing forms. Specific optimization and adjustment can be performed according to actual needs.

[0100] As an example, any two or more of the through holes 12 are combined and arranged in the substrate 11 according to a preset rule to form a specific geometric shape.

[0101] Specifically, Fig. 9 and Fig.10 As shown, the geometric shapes include but are not limited to L-shape, n-shape, M-shape, rectangle or other regular or irregular shapes.

[0102] Specifically, by arranging any two or more of the through holes 12 in combination, the overall layout of the center conductor 151 in the first surface 111, the second surface 112 and the through hole 12 can be optimized, thereby helping to meet the signal interconnection requirements under different structural designs, while facilitating the connection of different functional modules on the first surface 111 and the second surface 112 to achieve partitioning and integration of functional areas.

[0103] As an example, the transmission line structure further includes an adhesion layer (not shown) located between the insulating dielectric layer 13 and the conductive wiring layer 15 .

[0104] Specifically, the adhesion layer can be formed of titanium, copper, or a metal material having a similar lattice structure to the conductive wiring layer 15 , so as to ensure that the conductive wiring layer 15 is stably attached to the insulating dielectric layer 13 .

[0105] As an example, a barrier layer (not shown) is further provided between the adhesion layer and the conductive wiring layer 15 .

[0106] Specifically, the material of the barrier layer includes titanium, tungsten or other suitable metal materials.

[0107] This embodiment provides a coplanar waveguide type transmission line structure, in which the center conductor located on the first surface and the second surface serves as a planar transmission line, and the center conductor located on the inclined inner wall of the through hole serves as an in-hole transmission line, forming a through-silicon transmission line structure. The in-hole transmission line in the through-silicon transmission line structure is connected to the planar transmission line to form a continuous signal transmission path, ensuring efficient transmission of signals in the through-silicon transmission line structure. At the same time, since the structures of the two are the same, the consistency of the impedance of the through-silicon transmission line is guaranteed, thereby effectively avoiding the signal loss problem caused by impedance mismatch when the signal is transmitted between the in-hole transmission line and the planar transmission line, thereby effectively improving the integrity and efficiency of signal transmission, and helping to achieve stable transmission of higher-frequency signals.

[0108] Embodiment 2

[0109] This embodiment provides a transmission line structure, which is mainly different from the first embodiment in that side conductors 152 (grounding wires) are not formed on both sides of the center conductor 151 described in this embodiment, but a grounding plane is formed in the bottom structural layer 16, while side conductors 152 are provided on both sides of the center conductor 151 described in the first embodiment.

[0110] As an example, see Fig.11 and Fig.12 The transmission line structure also includes a bottom structural layer 16 located below the insulating dielectric layer 13, the bottom structural layer 16 includes a bottom insulating dielectric layer 161 and a bottom metal layer 162 located above the bottom insulating dielectric layer 161, the bottom insulating dielectric layer 161 covers the first surface 111, the second surface 112 and the inner wall 121 of the through hole 12, the bottom metal layer 162 serves as a ground plane, and the insulating dielectric layer 13 covers the surface of the bottom metal layer 162.

[0111] Specifically, the material of the bottom insulating dielectric layer 161 includes silicon dioxide or other suitable dielectric materials. The material of the bottom metal layer 162 includes copper, aluminum, gold, silver, titanium or other suitable metal materials.

[0112] In the transmission line structure of this embodiment, a bottom structural layer is provided at the bottom of the insulating dielectric layer, and the bottom metal layer in the bottom structural layer serves as a ground plane, and forms a microstrip line type transmission line structure with the insulating dielectric layer and the conductive wiring layer. In the transmission line structure, the in-hole transmission line (center conductor) located on the inclined inner wall of the through hole is connected to the planar transmission line (center conductor) located on the first surface and the second surface of the substrate, forming a continuous signal transmission path, ensuring efficient transmission of the signal in the through-silicon transmission line structure. At the same time, the two have the same structure, ensuring the consistency of the impedance of the through-silicon transmission line, so that the signal can effectively overcome the signal loss problem caused by impedance mismatch when the signal is transmitted between the in-hole transmission line and the planar transmission line, thereby significantly improving the integrity and efficiency of signal transmission, and facilitating the stable transmission of higher-frequency signals.

[0113] Embodiment 3

[0114] This embodiment provides a method for preparing a transmission line structure, which can be used to prepare the transmission line structure described in Embodiment 1. Fig.13 , shown as a process flow chart of the preparation method, comprising the following steps:

[0115] S1: providing a substrate, the substrate comprising a first surface and a second surface arranged opposite to each other, and etching at least one of the first surface and the second surface to form a plurality of through holes penetrating the substrate and having inclined inner walls;

[0116] S2: forming an insulating dielectric layer covering the first surface, the second surface and the inner wall of the through hole;

[0117] S3: forming a conductive layer on the insulating dielectric layer;

[0118] S4: forming a shielding layer on the conductive layer, patterning the shielding layer to form an opening exposing the conductive layer, and etching the conductive layer based on the opening, wherein the unetched portion of the conductive layer forms the conductive wiring layer, the conductive wiring layer includes a center conductor, the center conductor includes a first segment, a second segment, and a third segment connected in sequence, wherein the first segment is located on the first surface, the second segment is located on the inner wall of the through hole, the third segment is located on the second surface, and the center conductor serves as a signal line.

[0119] The method for preparing the transmission line structure of this embodiment is described in detail below with reference to the specific drawings.

[0120] First, see Fig.14 and Fig.15 , perform the step S1: provide a substrate 11, the substrate 11 includes a first surface 111 and a second surface 112 arranged opposite to each other, and etch at least one side of the first surface 111 and the second surface 112 to form a plurality of through holes 12 penetrating the substrate 11 and having inclined inner walls 121.

[0121] As an example, the substrate 11 may be a silicon substrate, a germanium silicon substrate, a III-V group element compound substrate or other semiconductor material substrates known to those skilled in the art. In this embodiment, the substrate 11 is an N-type silicon substrate with a (100) crystal plane.

[0122] As an example, the formation of the through hole 12 includes the following steps:

[0123] (1) forming a mask layer covering the first surface 111 and the second surface 112, and patterning the mask layer to form a mask opening, wherein the mask opening is located on at least one side of the first surface 111 and the second surface 112 (not shown);

[0124] (2) The substrate 11 is etched based on the mask opening to form the through hole 12 (not shown).

[0125] Specifically, the mask layer may be formed by coating, chemical vapor deposition, physical vapor deposition or other suitable methods, and the mask layer may be patterned by photolithography and etching processes to form the mask opening.

[0126] Specifically, the substrate 11 can be etched by a single dry etching process, a wet etching process, or a combination of the two to form the through hole 12. In this embodiment, it is preferred to form the through hole 12 by a wet etching process, and potassium hydroxide solution is particularly selected as the etching solution. Since the corrosion rate of the potassium hydroxide solution on the (100) crystal plane of the N-type silicon substrate is much higher than that on the (111) crystal plane, a through hole 12 with an inclined inner wall can be formed on the N-type silicon substrate 11. In addition, by precisely controlling the concentration and etching time of the potassium hydroxide solution, the inclination angle of the through hole 12 can be adjusted and optimized, and the smoothness of the inner wall 121 can be improved. The process of forming the through hole 12 by wet etching with crystal plane selectivity in this embodiment has strong processability and process consistency, and the process steps are simple and the cost is low.

[0127] As an example, the angle between the inner wall 121 of the through hole 12 and at least one of the first surface 111 or the second surface 112 is in the range of 50° to 60°.

[0128] As an example, the through hole 12 includes a double trapezoidal through hole 122 , a single trapezoidal through hole 123 , or a through hole of other suitable shapes.

[0129] Specifically, Fig.14 As shown, when the first surface 111 and the second surface 112 are etched simultaneously (i.e., double-sided wet etching is performed), the through hole formed is a double trapezoidal through hole 122, and the double trapezoidal through hole 122 includes an upper trapezoidal through hole 1221 and a lower trapezoidal through hole 1222. The top surface openings of the upper trapezoidal through hole 1221 and the lower trapezoidal through hole 1222 are larger than the bottom surface openings, and the upper trapezoidal through hole 1221 and the lower trapezoidal through hole 1222 are connected through their bottom surface openings to form a through hole. Fig.15 As shown, when etching is performed on any one side of the first surface 111 or the second surface 112 (i.e., single-sided wet etching is performed), the through hole 12 formed is a single trapezoidal through hole 123, and the top surface opening of the single trapezoidal through hole 123 is larger than the bottom surface opening of the trapezoidal through hole.

[0130] It should be noted that the shape of the through hole 12 in this embodiment is not fixed, but can be flexibly adjusted according to specific application requirements and process conditions, which can be achieved by changing the graphic design of the mask opening or selecting different etching solutions. For example, in some embodiments, the through hole 12 formed can also be an inverted pyramid shape, and is not limited to the shape of the through hole 12 mentioned above.

[0131] As an example, any two or more through holes 12 are arranged in combination in the substrate 11 according to a preset rule to form a specific geometric shape, which includes but is not limited to L-shaped, n-shaped, M-shaped, rectangular or other regular or irregular shapes.

[0132] Specifically, when any two or more of the through holes 12 in the substrate are combined and arranged to form different geometric shapes, the overall layout of the center conductor 151 in the first surface 111, the second surface 112 and the through hole 12 can be optimized, thereby helping to meet the signal interconnection requirements under different structural designs, and at the same time facilitating the connection of different functional modules on the first surface 111 and the second surface 112 to achieve partitioning and integration of functional areas.

[0133] Please see again Fig.16 , perform the step S2: forming an insulating dielectric layer 13 covering the first surface 111, the second surface 112 and the inner wall 121 of the through hole.

[0134] Specifically, the method of forming the insulating dielectric layer 13 includes thermal oxidation, chemical vapor deposition or other suitable methods. The material of the insulating dielectric layer 13 includes silicon dioxide or other suitable dielectric materials.

[0135] Please see again Fig.17 , perform the step S3: forming a conductive layer 14 on the insulating dielectric layer 13 .

[0136] As an example, before forming the conductive layer 14 , an adhesion layer (not shown) is first formed on the insulating dielectric layer 13 .

[0137] Specifically, the adhesion layer may be made of titanium, copper, or a metal material having a similar lattice structure to the conductive layer 14 , so as to enhance the adhesion of the conductive layer 14 .

[0138] As an example, before forming the conductive layer 14, a step of forming a barrier layer covering the adhesion layer is further included.

[0139] Specifically, the barrier layer may be formed by magnetron sputtering, atomic layer deposition or other suitable methods. The barrier layer may be made of titanium, tungsten or other suitable metal materials.

[0140] Specifically, the method for forming the conductive layer 14 includes physical vapor deposition, chemical vapor deposition, or other suitable methods. In this embodiment, the conductive layer 14 is preferably formed by magnetron sputtering (ie, physical vapor deposition) or electroplating (ie, electrochemical deposition).

[0141] Specifically, the conductive layer 14 is made of a superconducting material or a non-superconducting metal material.

[0142] Please see again Fig.18 and Fig.19 , perform the step S4: form a shielding layer (not shown) on the conductive layer 14, pattern the shielding layer to form an opening exposing the conductive layer 14, and etch the conductive layer 14 based on the opening, wherein the unetched portion of the conductive layer 14 forms the conductive wiring layer 15, the conductive wiring layer 15 includes a central conductor 151, the central conductor 151 includes a first segment 1511, a second segment 1512 and a third segment 1513 connected in sequence, wherein the first segment 1511 is located on the first surface 111, the second segment 1512 is located on the inner wall 121 of the through hole 12, the third segment 1513 is located on the second surface 112, and the central conductor 151 serves as a signal line.

[0143] Specifically, a shielding layer is formed on the conductive layer 14 by spin coating, spray coating or other suitable methods. The shielding layer can be a photoresist layer or other suitable material layer.

[0144] Specifically, the shielding layer is patterned by semiconductor processes such as photolithography and development to form the opening.

[0145] Specifically, a dry etching process (such as a reactive ion etching process) or a wet etching process may be used to etch the conductive layer 14. During the etching process, the portion of the conductive layer 14 covered by the shielding layer will be protected and will not be etched, and the remaining portion of the conductive layer 14 that has not been etched constitutes the conductive wiring layer 15, and the conductive wiring layer 15 includes a central conductor 151.

[0146] As an example, the material of the conductive wiring layer 15 includes a superconducting material or a non-superconducting metal material, the superconducting transition temperature of the superconducting material is in the range of 0 to 300 K, and the superconducting material includes but is not limited to any one of niobium, niobium nitride, aluminum, and titanium nitride, and the non-superconducting metal material includes but is not limited to any one of copper, gold, silver, nickel, palladium, and platinum. In this embodiment, the material of the conductive wiring layer 15 is preferably a superconducting material.

[0147] Specifically, in this embodiment, the center conductor 151 extends from the first surface 111 to the inner wall 121 of the through hole, and further extends to the second surface 112. The second section 1512 located on the inner wall 121 of the through hole serves as an in-hole transmission line, the first section 1511 located on the first surface 111 and the third section 1513 located on the second surface 112 serve as a planar transmission line, and the in-hole transmission line is connected to the planar transmission line to form a continuous signal transmission path. At the same time, since the second section 1512 has the same structure as the first section 1511 and the third section 1513, the impedance uniformity of the center conductor 151 is ensured, and the additional signal loss caused by the impedance change or mismatch of the transmission line when the signal is transmitted between the planar transmission line and the in-hole transmission line is greatly reduced. In addition, the material of the center conductor 151 is made of superconducting material, which can further reduce the possibility of signal attenuation, thereby ensuring the integrity and transmission efficiency of higher frequency signal transmission.

[0148] As an example, the line width of the second segment 1512 changes gradually along the extension direction of the inner wall 121 of the through hole.

[0149] Specifically, when the through hole 12 is a double trapezoidal through hole 122, the line width of the second section 1512 increases first and then decreases along the extension direction of the through hole inner wall 121; when the through hole 12 is a single trapezoidal through hole 123, the line width of the second section 1512 gradually increases along the extension direction of the through hole inner wall 121. In this embodiment, the line width of the second section 1512 is designed to change in a gradient, which can make the impedance change of the transmission line in the hole smoother, thereby effectively avoiding the problem of discontinuous impedance change of the transmission line in the hole caused by the change in the thickness of the substrate 11, and reducing the loss caused by the sudden change in the impedance of the center conductor 151.

[0150] Of course, in other embodiments, the line width of the second section 1512 can be fixed, or can present a variety of changing trends along the extension direction of the through hole inner wall 121, such as first decreasing and then increasing, gradually decreasing, or other preset changes. The specific line width design can be selected according to actual needs to meet different design requirements.

[0151] Specifically, in one example, the transmission line structure formed by the method for preparing the transmission line structure includes a first through hole 124 (not shown) and a second through hole 125 (not shown) that are spaced apart, wherein the center conductor 151 passing through the first through hole 124 and the center conductor 151 passing through the second through hole 125 are arranged opposite to each other on the first surface 111 and are spaced apart by a preset distance.

[0152] As an example, the central conductive line 151 passing through the first through hole 124 and the central conductive line 151 passing through the second through hole 125 are connected on the second surface 112 .

[0153] As an example, while forming the center conductor 151, the conductive wiring layer 15 also forms side conductors 152 on both sides of the center conductor 151, and the side conductors 152 serve as ground wires. The spacing between the side conductors 152 and the center conductor 151 can be flexibly adjusted according to impedance matching requirements.

[0154] As an example, the line width of the central conductor 151 is greater than the line width of the side conductors 152. The specific line width of the central conductor 151 can be flexibly determined according to actual needs and is not specifically limited here.

[0155] As an example, after forming the conductive wiring layer 15 , the method further includes etching the barrier layer and the adhesion layer based on the opening to expose the insulating dielectric layer 13 .

[0156] Specifically, the barrier layer and the adhesion layer in the opening may be removed by a wet etching process, a dry etching process or other suitable methods.

[0157] Thus, a transmission line structure is obtained.

[0158] In the preparation method of the transmission line structure of the present embodiment, a through hole with an inclined inner wall is formed between the first surface and the second surface of the substrate by a wet etching process, and an insulating dielectric layer and a conductive layer are sequentially covered on the first surface, the second surface and the inner wall of the through hole, and a conductive wiring layer including a signal line and a ground line is formed based on the conductive layer, thereby forming a coplanar waveguide type transmission line structure. Among them, the conductive wiring layer located on the inner wall of the through hole serves as an in-hole transmission line, and the conductive wiring layer located on the first surface and the second surface serves as a planar transmission line, forming a through-silicon transmission line structure. The in-hole transmission line in the through-silicon transmission line structure has the same structural design as the planar transmission line, and can maintain the same impedance, thereby avoiding additional signal loss caused by impedance mismatch and ensuring stable transmission of high-frequency signals.

[0159] Embodiment 4

[0160] This embodiment provides a method for preparing a transmission line structure. The main difference from the third embodiment is that in this embodiment, no side conductors 152 (grounding wires) are formed on both sides of the center conductor 151, but a grounding plane is formed in the bottom structural layer 16, while in the third embodiment, side conductors 152 are provided on both sides of the center conductor 151.

[0161] Specifically, in this embodiment, Fig. 20and 21 As shown, after forming the through hole 12 and before forming the insulating dielectric layer 13 , a step of forming an underlying structural layer 16 is also included.

[0162] As an example, forming the underlying structural layer 16 includes the following steps:

[0163] (1) forming a bottom insulating dielectric layer 161 (not shown) covering the first surface 111, the second surface 112 and the inner wall 121 of the through hole 12 by thermal oxidation, chemical vapor deposition or other suitable methods;

[0164] (2) A bottom metal layer 162 is formed on the insulating dielectric layer 13 by magnetron sputtering, atomic layer deposition or other suitable methods. The bottom metal layer 162 serves as a ground plane, and the insulating dielectric layer 13 covers the surface of the bottom metal layer 162 (not shown).

[0165] Specifically, the material of the bottom insulating dielectric layer 161 includes silicon dioxide or other suitable dielectric materials.

[0166] Specifically, the material of the bottom metal layer 162 includes copper, aluminum, gold, silver, titanium or other suitable metal materials.

[0167] The subsequent process steps of this embodiment are basically the same as those of the third embodiment and will not be described again here.

[0168] At this point, a transmission line structure is obtained, such as Fig. 22 and 23 , which is a schematic cross-sectional structure diagram of the method for preparing the transmission line structure of this embodiment after forming an insulating dielectric layer and a conductive wiring layer on a substrate having double trapezoidal through holes and a single trapezoidal through hole respectively.

[0169] In the method for preparing the transmission line structure of the present embodiment, a bottom structural layer covering the first surface, the second surface and the inner wall of the through hole of the substrate is first formed, and the bottom metal layer in the bottom structural layer is used as a ground plane, and then an insulating dielectric layer covering the bottom structural layer and a conductive wiring layer located above the insulating dielectric layer are formed, and the conductive wiring layer includes a signal line, thereby forming a microstrip line type transmission line structure. In the transmission line structure, the in-hole transmission line (i.e., the conductive wiring layer located on the inner wall of the through hole) and the planar transmission line (i.e., the conductive wiring layer located on the first surface and the second surface) also have the same structural design, which can achieve impedance matching, thereby effectively avoiding problems such as signal transmission loss caused by inconsistent impedance.

[0170] Embodiment 5

[0171] This embodiment provides an application of a transmission line structure, which applies the transmission line structure in Embodiment 1 and Embodiment 2 to high-frequency signal transmission in superconducting integrated circuits, high-frequency signal transmission in semiconductor integrated circuits, or high-frequency signal transmission in non-superconducting integrated circuits.

[0172] Specifically, when the transmission line structure is applied to high-frequency signal transmission of superconducting integrated circuits, high-frequency signal transmission of semiconductor integrated circuits, high-frequency signal transmission of non-superconducting integrated circuits or other related high-frequency signal transmission fields, the transmission line structure forms a center conductor 151 on the inclined inner wall of the through hole 12. The center conductor 151, as an in-hole transmission line, can be connected to the planar transmission line (center conductor 151) located on the first surface 111 and the second surface 112 to form an impedance-matched transmission path, thereby effectively reducing the signal loss problem caused by impedance mismatch, and significantly improving the stability and transmission efficiency of high-frequency signal transmission, thereby meeting the high-frequency signal transmission requirements.

[0173] In summary, the present invention provides a transmission line structure, a preparation method and an application thereof, wherein the transmission line structure comprises a substrate, an insulating dielectric layer and a conductive wiring layer, wherein the substrate comprises a first surface and a second surface arranged opposite to each other, a plurality of through holes penetrating the substrate are provided in the substrate, and the inner wall of the through hole is arranged obliquely, the insulating dielectric layer covers the first surface, the second surface and the inner wall of the through hole, the conductive wiring layer is located on the surface of the insulating dielectric layer, and the conductive wiring layer comprises a central conductor, and the central conductor serves as a signal line. The present invention achieves consistency with the structural design of the central conductor (planar transmission line) on the first surface and the second surface by directly forming the central conductor (i.e., the transmission line in the hole) on the inner wall of the through hole, thereby ensuring impedance matching, avoiding signal loss caused by impedance mismatch when the signal is transmitted between the transmission line in the hole and the planar transmission line, thereby significantly improving the integrity and efficiency of signal transmission, and helping to achieve stable transmission of higher frequency signals. At the same time, the size design of the transmission line in the hole and the through hole is flexible, and through holes of different sizes can be made according to requirements, thereby supporting the design of a transmission line structure with a smaller line width and a higher density. By increasing the number of transmission lines in the hole, the interconnection density can be further improved and the signal loss can be reduced. The types of through-silicon transmission line structures formed by the present invention include coplanar waveguides and microstrip lines, and support expansion into other types of transmission line structures such as grounded coplanar waveguides, differential lines and strip lines, providing a flexible basis for a variety of design requirements. In addition, the present invention uses a wet etching process with crystal plane selectivity to process the inner wall of the through hole, so that the inner wall is inclined. This process method has strong processing capabilities and process consistency, and the process flow is simple, easy to operate, and low in cost, which can significantly improve manufacturing efficiency. The through-silicon transmission line structure of the present invention not only effectively solves the problem of possible loss when the signal is transmitted between the horizontal and vertical directions, but also improves the stability of high-frequency signal transmission. It has broad application prospects in the field of high-frequency signal transmission and silicon through-hole interconnection technology, and can provide important technical support for the design of high-density packaging and multi-layer integrated circuits. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0174] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A transmission line structure, characterized in that: include: A substrate, the substrate comprising a first surface and a second surface arranged opposite to each other, the substrate being provided with a plurality of through holes penetrating the substrate, and inner walls of the through holes being arranged obliquely; an insulating dielectric layer, covering the first surface, the second surface and the inner wall of the through hole; A conductive wiring layer is located on the surface of the insulating dielectric layer, the conductive wiring layer includes a center conductor, and the center conductor includes a first section, a second section, and a third section connected in sequence, wherein the first section is located on the first surface, the second section is located on the inner wall of the through hole, the third section is located on the second surface, and the center conductor serves as a signal line.

2. The transmission line structure according to claim 1, characterized in that: The transmission line structure includes a first through hole and a second through hole that are spaced apart, wherein the center conductor passing through the first through hole and the center conductor passing through the second through hole are disposed opposite to each other on the first surface and are spaced apart by a preset distance.

3. The transmission line structure according to claim 2, characterized in that: The central conductive line passing through the first through hole and the central conductive line passing through the second through hole are connected on the second surface.

4. The transmission line structure according to claim 1, characterized in that: The line width of the second section changes gradually along the extension direction of the inner wall of the through hole.

5. The transmission line structure according to claim 1, characterized in that: The material of the conductive wiring layer includes a superconducting material or a non-superconducting metal material, the superconducting transition temperature of the superconducting material ranges from 0 to 300K, and the superconducting material includes any one of niobium, niobium nitride, aluminum, and titanium nitride, and the non-superconducting metal material includes any one of copper, gold, silver, nickel, palladium and platinum.

6. The transmission line structure according to claim 1, characterized in that: The conductive wiring layer further includes side wires spaced apart on both sides of the central wire, and the side wires serve as ground wires.

7. The transmission line structure according to claim 1, characterized in that: Any two or more of the through holes are combined and arranged in the substrate according to a preset rule to form a specific geometric shape.

8. The transmission line structure according to claim 1, characterized in that: It also includes a bottom structural layer located below the insulating dielectric layer, the bottom structural layer includes a bottom insulating dielectric layer and a bottom metal layer located above the bottom insulating dielectric layer, the bottom insulating dielectric layer covers the first surface, the second surface and the inner wall of the through hole, the bottom metal layer serves as a ground plane, and the insulating dielectric layer covers the surface of the bottom metal layer.

9. A method for preparing a transmission line structure, characterized in that: The following steps are involved: Providing a substrate, the substrate comprising a first surface and a second surface arranged opposite to each other, and etching at least one of the first surface and the second surface to form a plurality of through holes penetrating the substrate and having inclined inner walls; forming an insulating dielectric layer covering the first surface, the second surface and the inner wall of the through hole; forming a conductive layer on the insulating dielectric layer; A shielding layer is formed on the conductive layer, the shielding layer is patterned to form an opening exposing the conductive layer, and the conductive layer is etched based on the opening, wherein the unetched portion of the conductive layer forms the conductive wiring layer, the conductive wiring layer includes a center conductor, the center conductor includes a first segment, a second segment, and a third segment connected in sequence, wherein the first segment is located on the first surface, the second segment is located on the inner wall of the through hole, the third segment is located on the second surface, and the center conductor serves as a signal line.

10. The method for preparing a transmission line structure according to claim 9, characterized in that: While forming the central conductive line, side conductive lines are also formed in the conductive wiring layer on both sides of the central conductive line, and the side conductive lines serve as grounding lines.

11. The method for preparing a transmission line structure according to claim 9, characterized in that: After forming the through hole and before forming the insulating dielectric layer, the method further includes forming an underlying structural layer.

12. The method for preparing a transmission line structure according to claim 11, characterized in that: Forming the underlying structural layer comprises the following steps: forming a bottom insulating dielectric layer covering the first surface, the second surface and the inner wall of the through hole; A bottom metal layer is formed on the insulating dielectric layer, and the insulating dielectric layer covers the surface of the bottom metal layer.

13. An application of a transmission line structure, characterized in that: The application includes applying the transmission line structure according to any one of claims 1 to 8 to high-frequency signal transmission in superconducting integrated circuits, high-frequency signal transmission in semiconductor integrated circuits, or high-frequency signal transmission in non-superconducting integrated circuits.

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