Substrate assembly and method of manufacturing a substrate assembly

Abstract

This application provides a substrate assembly and a method for fabricating the substrate assembly. The substrate assembly includes: a glass substrate, which includes: a through-hole, the inner diameter of which gradually decreases from its two openings towards the interior along its extension direction to create a necked structure; the inner wall of the through-hole is a smooth, continuous curved surface with a roughness Ra ≤ 100 nm; an electroplated metal layer disposed within the through-hole; and a circuit layer disposed on the surface of the glass substrate and electrically connected to the electroplated metal layer. The geometric relationship between the minimum inner diameter of the through-hole and the inner diameter at the opening of the through-hole satisfies the condition that vapor-phase sputtered particles incident at a preset tilt angle from one side of the opening edge of the through-hole can be deposited at the minimum inner diameter of the through-hole. The substrate assembly and its fabrication method disclosed in this application achieve effective particle delivery to the bottom of the hole, avoiding poor physical vapor deposition caused by hole wall obstruction.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging technology, and in particular to a substrate assembly and a method for preparing the substrate assembly. Background Technology

[0002] Through-Glass Via (TGV) technology, leveraging the advantages of glass materials such as low dielectric loss, low coefficient of thermal expansion, and high insulation, has become a core interconnection solution in fields such as 5G radio frequency, silicon photonics modules, and high-end chip 3D integration. In the TGV process, a through-hole is typically fabricated on a glass substrate first, and then a physical vapor deposition (PVD) layer is deposited on the inner wall of the through-hole using a physical vapor deposition (PVD) magnetron sputtering process, providing a conductive path for subsequent copper plating.

[0003] Currently, all TGV vias on glass substrates in existing technologies are linear through-hole structures, meaning the inner diameter of the via remains constant along its depth, and the via wall extends in a straight line. However, this linear through-hole structure has significant technical drawbacks when performing physical vapor deposition (PVD) sputtering under high aspect ratio conditions. Because sputtered particles are injected from the via opening at a certain angle, the geometry of the linear via determines that the incident angle of the sputtered particles reaching various points on the via wall is relatively fixed. The sputtered particle flux is lower in the middle section of the via wall, resulting in a weak PVD layer in this area, leading to breaks and discontinuities. These discontinuities in the PVD layer directly affect the quality of subsequent copper plating, causing defects such as voids and incomplete filling within the via, thus impacting the conductivity and long-term reliability of the TGV interconnect. Summary of the Invention

[0004] This application discloses a substrate assembly and a method for fabricating the substrate assembly. By defining the geometric relationship between the minimum inner diameter of the through-hole necking structure and the inner diameter of the opening, as well as the roughness of the inner wall of the through-hole, the effective transport of particles to the bottom of the hole is achieved, the diffuse scattering when particles collide with the inner wall is suppressed, and the poor deposition of the physical vapor deposition layer caused by the blockage of the hole wall is avoided.

[0005] To achieve the above objectives, a first aspect of this application discloses a substrate assembly, the substrate assembly comprising: Glass substrate, the glass substrate includes: The through-hole penetrates the glass substrate in a direction perpendicular to the glass substrate. Along the extension direction of the through-hole, the inner diameter of the through-hole gradually decreases from the two openings at both ends into the through-hole to make the through-hole have a necking structure. The inner wall of the through-hole is a smooth and continuous curved surface with a roughness Ra≤100nm. The curved surface is recessed into the central axis of the through-hole to form a necking structure. Physical vapor deposition layer, which is deposited on the inner wall of the through hole; An electroplated metal layer is attached to the physical vapor deposition layer. The circuit layer is disposed on the surface of the glass substrate and is electrically connected to the electroplated metal layer; The geometric relationship between the minimum inner diameter of the through hole and the inner diameter at the opening of the through hole satisfies the following condition: gaseous sputtered particles incident from one side of the opening edge of the through hole at a preset tilt angle can be deposited at the minimum inner diameter of the through hole.

[0006] As an alternative implementation, the ratio between the depth of the through hole and the inner diameter at the opening of the through hole is less than or equal to 10:1.

[0007] By limiting the depth-to-diameter ratio to below 10:1, the longitudinal extension of the via can be controlled within the effective transport distance of the sputtered particles. This allows the sputtered particles entering from the via opening to reach the minimum inner diameter of the via and form an effective adhesion on the sidewall before they lose significant kinetic energy due to multiple collisions. This ensures that the physical vapor deposition layer can be fully covered from the via opening to the depth of the via.

[0008] As an alternative implementation, the inner diameter of the through hole gradually decreases from the openings at both ends toward the interior of the through hole, and the decrease in the inner diameter of the through hole first increases and then decreases.

[0009] In this way, the change in the inner diameter of the through hole first increases and then decreases, making the minimum inner diameter region present as a smooth arc-shaped transition zone. Sputtered particles can adhere uniformly in this transition zone with gradually changing incident conditions. The physical vapor deposition layer forms a continuous and uniformly thick coverage on both sides of the minimum inner diameter, avoiding the risk of deposition layer fracture caused by geometric peaks.

[0010] As an alternative implementation, the minimum inner diameter of the through hole is located at the midpoint of the through hole in its own extension direction, and the minimum inner diameter of the through hole is 65% to 75% of the inner diameter at the opening of the through hole.

[0011] Thus, a shrinkage ratio of 65% to 75% establishes a balance between particle capture efficiency and particle transport smoothness between the sidewall inclination angle and the channel cross-sectional size.

[0012] As an alternative implementation, the opening of the through hole is formed with a rounded chamfer, the radius of which is 3μm to 5μm.

[0013] In this way, the rounded chamfer can smoothly transition the geometric transition of the opening edge without having a substantial impact on the opening size of the through hole.

[0014] As an alternative implementation, the physical vapor deposition layer includes a barrier layer covering the inner wall and a conductive layer covering the barrier layer, with an electroplated metal layer filling the through-holes in which the physical vapor deposition layer is deposited.

[0015] Thus, the presence of the physical vapor deposition layer transforms the inner wall of the via from an insulating surface to a conductive surface. Electroplating current can be conducted through the physical vapor deposition layer to all parts of the inner wall of the via, guiding metal ions in the plating solution to deposit uniformly inside the via and gradually fill the entire via space. The physical vapor deposition layer consists of a barrier layer covering the inner wall of the via and a conductive layer covering the barrier layer; this dual-layer structure is designed to address different functional requirements.

[0016] As an alternative implementation, the barrier layer is made of chromium, titanium, or tantalum, and has a thickness of 400 nm to 600 nm; and / or, the conductive layer is made of copper, and has a thickness of 0.5 μm to 1 μm.

[0017] Thus, the 400nm to 600nm thickness range of the barrier layer achieves a reasonable balance between sufficient diffusion blocking and preservation of via filling space. Within this thickness range, the barrier layer provides a reliable diffusion barrier without excessively encroaching on the filling space of the electroplated metal layer. The 0.5μm to 1μm thickness range of the conductive layer achieves a reasonable balance between conductivity continuity, axial voltage drop control, and preservation of via filling space.

[0018] The second aspect of this application discloses a method for preparing a substrate assembly, the method comprising: Provide glass substrate body; Through holes are formed on the glass substrate body; The glass substrate is placed in the cavity of the ionization physical vapor deposition equipment, and a physical vapor deposition layer is sputtered and deposited on the inner wall of the through hole. During the sputtering and deposition of the physical vapor deposition layer, the glass substrate moves back and forth and deflects at an angle relative to the cavity so that the sputtered particles uniformly cover the inner wall of the through hole. The deposited glass substrate is cooled in a vacuum environment to obtain the glass substrate. An electroplated metal layer and a circuit layer are formed on a glass substrate to create a substrate assembly.

[0019] As an optional implementation, the step of forming a through hole on a glass substrate specifically includes: irradiating a predetermined position on the glass substrate with a laser to form a laser-modified channel penetrating the glass substrate; placing the laser-treated glass substrate in an etching solution and using the etching solution to chemically etch the hole wall of the laser-modified channel to form a through hole.

[0020] Thus, by controlling the concentration of the etching solution, the etching temperature, and the etching time, the evolution of the inner diameter of the through hole along the axial direction can be adjusted, so that the inner diameter of the through hole gradually decreases from the openings at both ends into the through hole, forming a necked structure with a smooth transition of the inner wall.

[0021] As an optional implementation, the steps of the glass substrate performing reciprocating movement and angular deflection movement during the sputtering deposition of the physical vapor deposition layer specifically include: the reciprocating movement is a linear reciprocating motion along a direction parallel to the surface of the glass substrate and perpendicular to the axis of the via; while performing the reciprocating movement, the glass substrate performs angular deflection movement, which is a periodic oscillation around the axis of the via.

[0022] Thus, the simultaneous reciprocating motion and angular deflection motion cause the particle incident conditions at any position on the inner wall of the through-hole to continuously change and tend to homogenize over time. The front and rear sidewalls along the reciprocating motion direction achieve uniform coverage through position scanning, while the different circumferential sidewalls around the axis achieve uniform coverage through angular oscillation. The synergistic effect of these two motions ensures that the entire inner wall of the through-hole receives a sufficient and uniform sputtered particle flow during the physical vapor deposition process, thereby achieving continuous and uniform deposition of the physical vapor deposition layer on the inner wall of the necked through-hole from a process perspective.

[0023] As an optional implementation, the reciprocating movement speed is 10 mm / min, and the movement range is 2 m to 4 m; and / or, the angular deflection movement has a deflection speed of 1° / min and a deflection angle range of ±9°.

[0024] Thus, the two motion modes work together to ensure that different axial sections along the direction of movement and different circumferential sections around the axis of movement on the inner wall of the through hole can obtain sufficient and uniform particle coverage during the sputtering deposition process. This ensures the continuity and thickness uniformity of the physical vapor deposition layer on the entire inner wall of the necked through hole from the perspective of process motion parameters.

[0025] Compared with the prior art, the beneficial effects of this application are: The substrate assembly disclosed in this application, by designing the vias as a necked structure with a gradually changing inner diameter, alters the receiving angle of the sidewalls relative to the incident direction of sputtered particles. This allows sputtered particles to be effectively captured and adhered to the sidewalls, overcoming the inherent defect of straight-hole structures where particles penetrate along the axis and cannot be effectively deposited on the hole walls. This ensures that the inner walls of the vias are fully and continuously covered by the physical vapor deposition (PVD) layer. Consequently, without the need for additional etching steps or significant modifications to existing PVD equipment, the risk of missing PVD layers or electroplating voids due to improper via design is reduced. The inner wall roughness Ra≤100nm of the vias ensures the adhesion and coverage continuity of the PVD layer on the inner walls of the vias from a microscopic surface quality perspective. This prevents the particle capture advantage of the vias in terms of macroscopic geometry from being weakened by microscopic defects on the inner wall surface, thus guaranteeing a uniform deposition effect of the PVD layer across the entire via wall. This provides a highly reliable and process-compatible interconnect solution for high-density glass-based 3D packaging.

[0026] The substrate assembly fabrication method disclosed in this application combines the static necking via structure with dynamic substrate movement by simultaneously moving the glass substrate body back and forth and deflecting its angle during the sputtering deposition of physical vapor deposition layer. This allows sputtered particles to enter the via at constantly changing angles and positions and effectively impact the necking sidewalls, overcoming the defect of insufficient particle coverage in the deep part of the via or the waisted recess area under single static sputtering conditions. This achieves uniform and continuous deposition of physical vapor deposition layer on the entire inner wall of the via. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is one of the structural schematic diagrams of the substrate assembly provided in the embodiments of this application; Figure 2 A schematic diagram of the incident angle of the substrate assembly provided in the embodiments of this application; Figure 3 This is a second schematic diagram of the structure of the substrate assembly provided in the embodiments of this application; Figure 4 This is the third schematic diagram of the structure of the substrate assembly provided in the embodiments of this application; Figure 5 for Figure 1 A magnified view of a section at point A in the middle; Figure 6 A flowchart illustrating the substrate assembly fabrication method provided in this application embodiment; Figure 7 This is a flowchart illustrating step S2 in the substrate assembly fabrication method provided in the embodiments of this application.

[0029] Explanation of reference numerals in the attached figures: 100-Substrate assembly; 1-Glass substrate; 11-Through hole; L-Axis of the through hole; 2-Electroplated metal layer; 3-Rounded chamfer; 4-Physical vapor deposition layer; R1-Inner diameter at the opening of the through hole; R2-Minimum inner diameter of the through hole. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] In this application, the terms "upper," "lower," "top," "bottom," "inner," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0032] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0033] Furthermore, the terms "set up," "equipped with," and "connected" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0034] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0035] Through-Glass Via (TGV) technology, leveraging the advantages of glass materials such as low dielectric loss, low coefficient of thermal expansion, and high insulation, has become a core interconnection solution in fields such as 5G radio frequency, silicon photonics modules, and high-end chip 3D integration. In the TGV process, a through-hole is typically fabricated on a glass substrate first, and then a physical vapor deposition (PVD) layer is deposited on the inner wall of the through-hole using a physical vapor deposition (PVD) magnetron sputtering process, providing a conductive path for subsequent copper plating.

[0036] Currently, all TGV vias on glass substrates in existing technologies are linear through-hole structures, meaning the inner diameter of the via remains constant along its depth, and the via wall extends in a straight line. However, this linear through-hole structure has significant technical drawbacks when performing physical vapor deposition (PVD) sputtering under high aspect ratio conditions. Because sputtered particles are injected from the via opening at a certain angle, the geometry of the linear via determines that the incident angle of the sputtered particles reaching various points on the via wall is relatively fixed. The sputtered particle flux is lower in the middle section of the via wall, resulting in a weak PVD layer in this area, leading to breaks and discontinuities. These discontinuities in the PVD layer directly affect the quality of subsequent copper plating, causing defects such as voids and incomplete filling within the via, thus impacting the conductivity and long-term reliability of the TGV interconnect.

[0037] Based on this, this application discloses a substrate assembly and a method for fabricating the substrate assembly. By defining the geometric relationship between the minimum inner diameter and the inner diameter of the through-hole necking structure, it adapts to the incident path of sputtered particles, thereby achieving effective delivery of particles to the bottom of the hole and avoiding poor physical vapor deposition caused by the hole wall blocking.

[0038] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0039] Please see Figures 1 to 4 , Figure 1 This is one of the structural schematic diagrams of the substrate assembly 100 provided in the embodiments of this application; Figure 2 A schematic diagram of the incident angle of the substrate assembly provided in the embodiments of this application; Figure 3 This is a second schematic diagram of the structure of the substrate assembly 100 provided in the embodiments of this application; Figure 4 This is the third schematic diagram of the structure of the substrate assembly 100 provided in the embodiments of this application. The embodiments of this application disclose a substrate assembly 100, which includes a glass substrate 1. The glass substrate 1 includes a through-hole 11, which penetrates the glass substrate 1 along a direction perpendicular to the glass substrate 1. Along the extending direction of the through-hole 11, the inner diameter of the through-hole 11 gradually decreases from its two openings towards its interior, so that the through-hole 11 has a necked structure. The inner wall of the through-hole 11 is a smooth, continuous curved surface with a roughness Ra ≤ 100 nm. The curved surface is recessed towards the central axis of the through-hole 11. To form a necked structure; physical vapor deposition layer 4, which is deposited on the inner wall of the through hole 11; electroplated metal layer 2, which is attached to the physical vapor deposition layer 4; a circuit layer, which is disposed on the surface of the glass substrate 1 and electrically connected to the electroplated metal layer 2; wherein, the geometric relationship between the minimum inner diameter R2 of the through hole and the inner diameter R1 at the opening of the through hole satisfies that: vapor sputtering particles incident from one side opening edge of the through hole 11 at a preset tilt angle can be deposited at the minimum inner diameter R2 of the through hole.

[0040] The substrate assembly 100 is a glass-based interposer structure used in the field of semiconductor three-dimensional packaging. Its function is to provide high-density vertical electrical interconnect channels between chips and substrates, or between chips. The substrate assembly 100 uses glass as a substrate. Through-holes 11 are formed inside the substrate, and conductive material is filled into the holes to form an electroplated metal layer 2. This enables electrical signal conduction between the upper and lower surfaces of the glass substrate 1. At the same time, the electrical signals are laterally led out or redistributed by the circuit layer disposed on the glass surface, thereby achieving multi-channel, low-latency, and high-reliability interconnection functions within a limited area.

[0041] In display panel applications, the aforementioned substrate assembly 100 is typically used as a driving backplane or transition interlayer for LED direct-view modules. The display panel can be a light-emitting diode (LED) display panel, for example, it can be one of a micro light-emitting diode (Micro LED) display panel or a mini light-emitting diode (Mini LED) display panel. Understandably, Mini LED and Micro LED display panels have advantages such as self-illumination, high brightness, high contrast, high resolution, high color saturation, long lifespan, and fast response speed.

[0042] The display panel includes multiple light-emitting units arranged in an array and a driver chip for driving each light-emitting unit. The substrate assembly 100 is disposed between the driver chip and the light-emitting units, or between the driver chip and the system motherboard. Through its internal electroplated metal layer 2 and surface circuit layer, the electrical signals output by the driver chip are vertically transmitted to the corresponding light-emitting unit electrodes, thereby achieving independent addressing and driving of each pixel. Compared with traditional lateral lead or silicon-based interconnection solutions, the glass substrate 1, with its low dielectric loss and high insulation properties, can effectively reduce signal attenuation and crosstalk in high-frequency drive signal transmission. At the same time, its matching with the light-emitting units in terms of thermal expansion coefficient helps to improve the structural reliability of the display panel under thermal cycling conditions.

[0043] The glass substrate 1 serves as the foundation for structural support and electrical insulation in the substrate assembly 100. The use of glass material can take advantage of its low dielectric constant and low coefficient of thermal expansion to provide a low-loss environment for the transmission of high-frequency and high-speed signals. At the same time, it enables the substrate assembly 100 to have good thermomechanical matching with the chips or circuit boards connected later under temperature change scenarios, reducing the risk of deformation or failure caused by thermal stress.

[0044] Optionally, the glass substrate 1 may be made of borosilicate glass, quartz glass, aluminosilicate glass, or other transparent amorphous insulating materials with similar electrical and mechanical properties.

[0045] The via 11 penetrates the glass substrate 1 along a direction perpendicular to the glass substrate 1. The via 11 can establish a vertical physical channel from one surface of the glass substrate 1 to the other surface, providing space for subsequent filling with conductive material to form interlayer interconnects. The extension direction and penetration characteristics of the via 11 determine that the interconnect path has the shortest physical distance, which is beneficial to reducing interconnect resistance and signal transmission delay.

[0046] In the extending direction of the through-hole 11, the inner diameter of the through-hole 11 gradually decreases from its two openings towards the interior, thus giving the through-hole 11 an overall necked structure. This necking structure alters the geometric angle of the sidewall of the through-hole 11 relative to the perpendicular incident direction, making the sidewall an effective receiving surface for sputtered particles to adhere. Compared to a straight-hole structure where the inner diameter remains constant along the extending direction, the sidewall of a straight-hole is almost parallel to the incident direction of the sputtered particles. Most sputtered particles would pass directly through the through-hole 11 along the central axis of the straight-hole without colliding with and adhering to the sidewall. The necking structure, by adjusting the sidewall surface from a nearly parallel direction to form an effective angle with the particle incident direction, increases the probability of sputtered particles colliding with and adhering to the sidewall, allowing the sputtered particles to be effectively captured by the sidewall rather than directly penetrating the through-hole 11. Optionally, the necking structure can be a symmetrical waisted shape, or it can be adjusted to an asymmetrical tapering shape according to the distribution characteristics of the sputtered particle source.

[0047] The inner wall of the through hole 11 is configured to have a smooth transition, which can eliminate abrupt steps or sharp corners on the surface of the hole wall, reduce the scattering or particle bounce phenomenon caused by sputtered particles impacting the local abrupt structure during the incident process, and also facilitate the formation of a continuous and unbroken thin film coverage of the subsequent physical vapor deposition layer 4 on the hole wall.

[0048] A physical vapor deposition layer 4 is deposited on the inner wall of the through-hole 11, providing a continuous and conductive substrate for the electroplating of the metal layer 2. Since the glass substrate 1 itself is an insulating material, it cannot be directly used as the electroplating cathode for filling the metal layer 2. The presence of the physical vapor deposition layer 4 transforms the inner wall of the through-hole 11 from an insulating surface to a conductive surface. The electroplating current can be conducted through the physical vapor deposition layer 4 to all parts of the inner wall of the through-hole 11, guiding metal ions in the electroplating solution to be uniformly deposited inside the through-hole 11 and gradually filling the entire space of the through-hole 11. If there are discontinuous or missing areas of the physical vapor deposition layer 4 on the inner wall of the through-hole 11, metal deposition will not occur in these areas during the electroplating process, resulting in voids or incomplete filling inside the electroplated metal layer 2.

[0049] An electroplated metal layer 2 is disposed within the via 11, filling the internal space of the via 11 to form a solid vertical conductive path from one surface of the glass substrate 1 to the other, thereby achieving electrical connection between upper and lower layer circuits. The electroplated metal layer 2 is typically made of a good conductor such as copper to provide a low-resistance interconnect channel. It is understood that the electroplated metal layer 2 can be formed of copper or a copper alloy to enhance the bonding force between the conductive material and the glass substrate and prevent the diffusion of metal atoms into the glass interior. The electroplated metal layer 2 provides a low-impedance vertical interconnect path for the substrate assembly 100, capable of carrying high current densities, while the solid-filled structure also helps improve the structural integrity and long-term service reliability of the via 11 after filling.

[0050] A circuit layer is disposed on the surface of the glass substrate 1 and electrically connected to the electroplated metal layer 2. The circuit layer forms patterned conductive wiring on the horizontal plane of the glass substrate 1, electrically interconnecting multiple electroplated metal layers 2 according to the circuit design requirements, and can further transmit signals or power from the interconnected vias 11 to other functional areas or bonding pads on the surface of the glass substrate 1. The circuit layer provides horizontal electrical interconnection capability on the substrate surface, and together with the electroplated metal layer 2, forms a complete three-dimensional interconnection network, enabling the substrate assembly 100 to serve as a transition platform for adapting different chips or panel interfaces.

[0051] Optionally, the circuit layer can be a single-layer metal wiring or it can be extended to a multi-layer stacked redistribution layer structure. The material of the circuit layer can be copper, aluminum or other conductive materials suitable for integrated circuit wiring.

[0052] A geometric constraint is established between the minimum inner diameter R2 of the through-hole and the inner diameter at the opening of the through-hole 11. This means that sputtered particles incident at a preset tilt angle from one side opening edge of the through-hole 11 can reach the minimum inner diameter R2 of the through-hole. The purpose of this geometric constraint is to establish a correspondence between the inclination of the sidewall of the necking structure and the incident angle condition of the sputtered particles. This ensures that the necking slope of the sidewall of the through-hole 11 can effectively impact and adhere to the inner wall of the necking when sputtered particles are incident at a given angle, rather than directly penetrating the through-hole 11 along the axial direction.

[0053] Specifically, please refer to Figure 2 Let R1 represent the inner diameter at the opening of the through hole, R2 represent the minimum inner diameter of the through hole, H represent the depth of the through hole 11, and θ represent the maximum incident angle of sputtered particles at the opening edge on one side of the through hole 11. Then the structural parameters of the through hole 11 satisfy the following conditions:

[0054] The physical principles underlying this geometric relationship will be explained in detail below: The left side of the inequality, tanθ, represents the degree of inclination of the incident direction of sputtered particles at the edge of the via 11 opening relative to the axis of the via 11. During physical vapor deposition, not all sputtered particles are incident perpendicularly along the axis of the via 11; some particles enter the via 11 from the opening at a certain angle, resulting in a maximum incident angle θ under actual process conditions. The right side of the inequality characterizes the geometric ratio between the radial available space and the axial depth of the via 11 at half its depth.

[0055] Wherein, 1 / 2(R1-R2) is the difference between the radius at the opening of the through hole 11 and the minimum radius, which reflects the radial change in the sidewall of the through hole 11 as it contracts inward from the opening; 1 / 2(R1-R2)+R2 is the radial distance from the central axis of the through hole 11 to the sidewall of the through hole at half the hole depth; 1 / 2H is half the hole depth. This ratio essentially defines the effective half-angle of the necking structure of the through hole 11 at the middle position of the hole depth, that is, the slope of the sidewall of the through hole 11 relative to the central axis of the through hole 11 at the midpoint of the hole depth.

[0056] When the above inequality holds, sputtered particles entering the through-hole 11 from one side opening edge at the maximum incident angle θ will not directly pass through the through-hole 11 to reach the other side opening. Due to the inclined sidewall and the inclined incident particles, an effective impact angle is formed between them, and once the particles collide with the sidewall, they can be effectively captured by the sidewall and adhere to the sidewall surface. If the inequality does not hold, i.e., the contraction of the sidewall of the through-hole 11 is insufficient or the depth of the through-hole 11 is too small, even inclined particles with the maximum incident angle may pass directly through the through-hole 11 along the central axis without colliding with the sidewall. As a result, the central region of the sidewall, especially the hole wall near the minimum inner diameter of the through-hole 11, cannot be covered by a physical vapor deposition layer.

[0057] It is understandable that this approximate triangle provides a simplified geometric model basis for deriving the quantitative conditions between the through-hole structure parameters and the maximum incident angle. The area enclosed by the incident trajectory of the sputtered particles and the contour of the through-hole sidewall can be approximated as a triangle. This triangle is not a strictly precise geometric triangle, but an engineering approximation based on the particle motion path and the morphology of the through-hole inner wall in actual physical processes.

[0058] The inner diameter difference of the through-hole 11 refers to the difference between the inner diameter of the through-hole 11 at its opening and the minimum inner diameter of the through-hole 11. The thickness of the substrate is the extension length of the through-hole 11 through the glass substrate 1 along the direction perpendicular to the glass substrate 1. The ratio formed by dividing the inner diameter difference of the through-hole 11 by the thickness of the substrate is geometrically equivalent to the degree of inclination of the necked sidewall of the through-hole 11 relative to the vertical direction. The value of this ratio is equal to the tangent of the angle between the necked sidewall and the vertical direction. The angle corresponding to the tangent value is the inclination angle of the necked sidewall relative to the vertical direction. This angle characterizes the geometric steepness of the contraction of the sidewall of the through-hole 11 from the opening to the inside. The larger the angle, the more significant the contraction of the sidewall and the smaller the angle between the sidewall surface and the horizontal plane.

[0059] During sputtering deposition, not all sputtered particles enter the via 11 perpendicular to the glass substrate 1; instead, they exhibit a certain angular distribution range. The maximum angle deviating from the vertical direction is defined as the maximum incident angle of the sputtered particle. When a sputtered particle enters the via 11 from the opening edge at this maximum incident angle, a geometric correspondence is formed between the particle's trajectory and the necked sidewall of the via 11. If the tilt angle of the necked sidewall is greater than the maximum incident angle of the sputtered particle, it means that the tilt of the necked sidewall relative to the vertical direction exceeds the maximum extent to which the sputtered particle may deviate from the vertical direction. In this case, the sputtered particle entering the via 11 at the maximum incident angle will inevitably collide with the necked sidewall and be captured by it on its straight-line motion path.

[0060] Conversely, if the tilt angle of the necked sidewall is equal to or less than the maximum incident angle of the sputtered particles, the sputtered particles incident from the opening edge of the through hole 11 at the maximum incident angle will not touch the necked sidewall on their straight motion path, but may pass directly through the through hole 11 along the axial space of the through hole 11, thus failing to achieve effective adhesion on the sidewall.

[0061] In this embodiment, by setting the angle corresponding to the tangent value formed by the ratio of the inner diameter difference of the through hole 11 to the substrate thickness to be greater than the maximum incident angle of the sputtered particles, it is geometrically guaranteed that all sputtered particles entering the through hole 11 cannot penetrate the through hole 11 directly in a straight path, but will inevitably collide with the necked sidewall at a certain position inside the through hole 11 and be captured and attached, thereby providing structural protection for the complete and continuous coverage of the physical vapor deposition layer 4 on the sidewall of the through hole 11.

[0062] Thus, the substrate assembly 100 disclosed in this application, by designing the via 11 as a necked structure with a gradually changing inner diameter, changes the receiving angle of the sidewall relative to the incident direction of sputtered particles, enabling the sputtered particles to be effectively captured and attached by the sidewall. This overcomes the inherent defect of particles penetrating along the axis in a straight hole structure from the structural source, which prevents effective deposition on the hole wall. It ensures that the inner wall of the via 11 can be fully and continuously covered by the physical vapor deposition layer 4. In this way, without adding an additional etching step or significantly modifying the existing physical vapor deposition equipment, the risk of missing physical vapor deposition layer 4 or electroplating filling voids caused by improper hole design is reduced. This provides a highly reliable interconnection solution with good process compatibility for high-density glass-based three-dimensional packaging.

[0063] In some embodiments, the ratio between the depth of the via 11 and the inner diameter R1 at the opening of the via is less than or equal to 10:1. This ratio is the depth-to-diameter ratio of the via 11, and the upper limit constraint of the depth-to-diameter ratio is directly related to the particle transport efficiency and filling feasibility of the via 11 during the sputtering deposition process. When the depth of the via 11 is too large relative to the inner diameter at the opening, even if the via 11 has the sidewall receiving angle advantage provided by the necking structure, the longitudinal distance that sputtered particles need to travel after entering the via 11 will increase. The probability of random scattering of particles colliding with the sidewall before reaching the depth of the via 11 will increase, and the number and energy of particles reaching the minimum inner diameter of the via 11 will decrease, making it difficult to guarantee the continuity and uniformity of the physical vapor deposition layer 4 throughout the entire depth range of the via 11.

[0064] By limiting the depth-to-diameter ratio to below 10:1, the longitudinal extension of the through-hole 11 can be controlled within the effective transport distance of the sputtered particles. This allows the sputtered particles entering from the opening of the through-hole 11 to reach the minimum inner diameter R2 of the through-hole and form an effective attachment on the sidewall before they lose significant kinetic energy due to multiple collisions. This ensures that the physical vapor deposition layer 4 can be fully covered from the opening of the through-hole 11 to the depth of the through-hole 11.

[0065] Optionally, the ratio between the depth of the via 11 and the inner diameter R1 at the via opening can be further reduced based on the actual thickness of the glass substrate 1 and the particle energy conditions of the sputtering process. For example, the ratio can be limited to below 8:1 or 6:1 to accommodate different sputtering equipment parameters and particle incident energy levels. When the ionization rate of the sputtered particles is high or the substrate bias is large, resulting in increased particle incident energy, the upper limit of this ratio can be appropriately relaxed, but it still needs to be kept within a range where the particle energy is sufficient to support full-depth coverage.

[0066] Please see Figure 1In some embodiments, the inner wall of the through hole 11 is a smooth and continuous curved surface, and the curved surface is concave to the central axis of the through hole 11, so that the inner diameter of the through hole 11 gradually decreases from the opening at both ends to the interior of the through hole 11, and the change in the inner diameter of the through hole 11 increases first and then decreases.

[0067] The inner wall of the through-hole 11 is constructed as a smooth and continuous curved surface, which is concave towards the central axis of the through-hole 11, so that the inner diameter of the through-hole 11 gradually decreases from the two openings towards the interior of the through-hole 11. The smooth and continuous curved surface causes the incident angle of sputtered particles to gradually change along the curved surface when they hit the inner wall, the momentum transfer of the particles is smoother, and the directional distribution of the rebounding particles is more concentrated and controllable, thereby reducing the probability of particle bounce and desorption, which is conducive to the formation of a dense and continuous physical vapor deposition layer 4.

[0068] In one possible embodiment, the inner wall of the through hole 11 can be a smooth and continuous arc-shaped surface, and the specific curvature of the arc-shaped surface can be adjusted according to the incident angle distribution of the sputtered particles.

[0069] The rate of change of the inner diameter refers to the degree of contraction of the inner diameter of the through-hole 11 per unit length along the extension direction of the through-hole 11. This rate of change gradually increases with the increase of hole depth in a region near the opening of the through-hole 11, meaning that the sidewall of the through-hole 11 tilts towards the central axis at an increasingly faster rate in this section. This trend allows the sidewall of the through-hole 11 to quickly obtain a receiving surface that forms an effective angle with the incident direction of sputtered particles at a position close to the opening end. After entering the through-hole 11, sputtered particles can contact and be captured by the sidewall earlier, avoiding the situation where particles penetrate too far along the axial direction and still cannot reach the sidewall. At the same time, the design of gradually increasing rate of change rather than a sudden change at the opening makes the curvature transition of the sidewall surface smooth near the opening. When sputtered particles impact this area, they will not produce uncontrollable rebound due to geometrical abrupt changes, thus establishing a continuous physical vapor deposition layer 4 covering base in the region near the opening.

[0070] As the depth of the through-hole 11 increases further and approaches the minimum inner diameter, the rate of change of the inner diameter decreases after reaching a peak. This causes the rate of increase in the inclination of the sidewall of the through-hole 11 near the minimum inner diameter to slow down, and the sidewall surface gradually becomes smoother in this region. This prevents the through-hole 11 from forming sharp corners or peaks near the minimum inner diameter. If the through-hole 11 has a peak structure at the minimum inner diameter, the deposition thickness and continuity of the physical vapor deposition layer 4 on both sides of the peak are difficult to maintain. Furthermore, during subsequent use, the physical vapor deposition layer 4 at the peak position is prone to fracture due to stress concentration, which in turn leads to the interruption of the conductive path during electroplating filling, forming voids or incomplete filling defects.

[0071] Thus, the change in the inner diameter of the through hole 11 first increases and then decreases, making the minimum inner diameter region present as a smooth arc-shaped transition zone. Sputtered particles can adhere uniformly in this transition zone with gradually changing incident conditions. The physical vapor deposition layer 4 forms a continuous and uniformly thick cover on both sides of the minimum inner diameter, avoiding the risk of deposition layer fracture caused by geometric peaks.

[0072] In some embodiments, the minimum inner diameter R2 of the through hole is located in the middle region of the through hole 11 in its own extending direction, and the minimum inner diameter R2 of the through hole is 65% to 75% of the inner diameter at the opening of the through hole 11.

[0073] The minimum inner diameter R2 of the through-hole is limited to the middle region of the through-hole 11 along its extension direction, making the necking structure of the through-hole 11 symmetrically distributed in the axial direction, with the sidewall inclination from the two openings to the minimum inner diameter being consistent on both sides. The symmetrical necking structure ensures that sputtered particles incident from the two openings of the through-hole 11 can obtain equivalent sidewall trapping conditions, avoiding the problem of insufficient sidewall inclination on one side and excessive sidewall contraction on the other side due to the offset of the minimum inner diameter position, thereby ensuring the consistency of the physical vapor deposition layer 4 near the two openings of the through-hole 11.

[0074] It is understood that the minimum inner diameter of the through-hole 11 is located at the midpoint of the through-hole 11 along its own extension direction. However, in the actual manufacturing process, due to factors such as the distribution of laser drilling energy, the convection conditions of the chemical etching solution, and the local material uniformity of the glass substrate 1, the final forming position of the necked structure of the through-hole 11 may shift within the neighborhood of the preset midpoint. Therefore, the minimum inner diameter of the through-hole 11 is not strictly limited to an absolute geometric midpoint, but rather allows for positional fluctuation within a preset tolerance range near the midpoint of the extension direction of the through-hole 11.

[0075] Optionally, the tolerance range for the minimum inner diameter position can be considered to meet the minimum inner diameter position requirement within a range of 5% or 10% of the depth of the via 11 offset above and below the midpoint. For vias of different thicknesses or opening sizes, the specific value of this tolerance range can be adjusted accordingly to adapt to the process characteristics and performance requirements of substrate assemblies 100 of different specifications.

[0076] The minimum inner diameter R2 of the via is limited to 65% to 75% of the inner diameter at the opening of via 11. This range directly defines the degree of shrinkage of the necking structure. If the minimum inner diameter is greater than 75% of the inner diameter at the opening, the inclination angle of the sidewall is too small, and the sidewall surface remains close to the vertical direction. This reduces the probability of sputtered particles being captured by the sidewall, and the effect of the necking structure in improving particle adhesion will be significantly weakened. If the minimum inner diameter is less than 65% of the inner diameter at the opening, the sidewall shrinkage is too drastic, and the channel cross-section of via 11 at the minimum inner diameter is too narrow. When sputtered particles reach this area, they may be over-scattered or unable to pass through smoothly due to space constraints, which is also detrimental to the continuous coverage of the physical vapor deposition layer 4 throughout the via wall. The shrinkage ratio of 65% to 75% establishes a balance between particle capture efficiency and particle transport smoothness between the sidewall inclination angle and the channel cross-sectional size.

[0077] It is understandable that the specific ratio between the minimum inner diameter R2 of the via and the inner diameter of the opening can be selected in the range of 65% to 75% according to the thickness of the glass substrate 1, the distribution range of the incident angle of sputtered particles and the opening size of the via 11, so as to adapt to the process window of different specifications of substrate assembly 100.

[0078] In some embodiments, the inner wall roughness Ra of the through-hole 11 is ≤100nm. During the sputtering deposition process, sputtered particles impact the inner wall of the through-hole 11 with high kinetic energy. If there are obvious microscopic protrusions or depressions on the inner wall surface, the particles will be uncontrollably scattered when they impact these microstructures. Some particles may be bounced back into the internal space of the through-hole 11 and fail to adhere effectively, resulting in local thinning or absence of the physical vapor deposition layer 4 in this area.

[0079] Meanwhile, excessively rough inner wall surfaces increase the nucleation inhomogeneity of sputtered particles in the early stages of adhesion. Particles tend to preferentially accumulate in microscopic depressions, while insufficient deposition occurs at microscopic protrusions, resulting in an uneven thickness morphology of the physical vapor deposition layer 4 at the microscopic scale. By controlling the inner wall roughness within the range of Ra≤100nm, the amplitude of microscopic undulations on the inner wall surface can be limited to a scale that sputtered particles can compensate for through surface migration. This allows sputtered particles to make limited short-range movements along the surface after impacting the inner wall, filling microscopic depressions and forming a uniform and continuous thin film coverage, thereby ensuring the dense adhesion and uniform thickness of the physical vapor deposition layer 4 on the entire inner wall of the via 11.

[0080] Optionally, when the physical vapor deposition layer 4 is designed to be thin, the upper limit of the inner wall roughness can be tightened accordingly, for example, limiting the Ra value to below 50 nm or 30 nm, to prevent the peak-to-valley difference of microscopic undulations from exceeding the thickness of the physical vapor deposition layer 4 and causing local discontinuities in coverage. When the incident energy of sputtered particles is high or the substrate is subjected to auxiliary heating during the deposition process, the surface migration ability of the particles is enhanced, and the upper limit of the inner wall roughness can be appropriately relaxed, but it still needs to be kept within a range that does not affect the continuity of the physical vapor deposition layer 4.

[0081] The roughness Ra≤100nm of the inner wall of the through hole 11 ensures the adhesion and coverage continuity of the physical vapor deposition layer 4 on the inner wall of the through hole 11 from the perspective of microscopic surface quality. This ensures that the particle capture advantage of the through hole 11 in macroscopic geometry is not weakened by the microscopic defects on the inner wall surface, thereby ensuring the uniform deposition effect of the physical vapor deposition layer 4 throughout the hole wall.

[0082] Please see Figure 5 , Figure 5 for Figure 1 A magnified view of a portion at point A. In some embodiments, a rounded chamfer 3 is formed at the opening of the via 11, with a radius of 3 μm to 5 μm. The opening of the via 11 is the first contact area for sputtered particles entering the via 11, and also the starting point for the deposition of the physical vapor deposition layer 4. The rounded chamfer 3 at the opening of the via 11 first eliminates any sharp edges that might otherwise exist at the opening edge. If the opening of the via 11 has an acute angle, the incident path of sputtered particles near the opening will be partially blocked by the acute angle, forming a small shadow area on the side of the acute angle facing away from the sputtered particle source, where particles cannot directly reach, resulting in a weak or absent physical vapor deposition layer 4 in that area.

[0083] Meanwhile, at the sharp-angled edge, the physical vapor deposition layer 4 may experience local electric field concentration or preferential particle aggregation due to the tip effect during deposition, resulting in a deposition morphology with abrupt thickness changes. This morphology may cause uneven advancement of the filling front during subsequent electroplating, increasing the risk of internal void formation. The rounded chamfer 3 replaces the sharp angle transition with a smooth curved surface, making the geometry at the opening of the via 11 gradually change from the surface of the glass substrate 1 to the inner wall of the via 11. The incident path of sputtered particles near the opening is not interrupted due to local geometric abrupt changes, and the particle reception conditions in various regions around the opening tend to be consistent, enabling the physical vapor deposition layer 4 to form a uniform and continuous coverage at the opening of the via 11.

[0084] The radius of the chamfer 3 is set within the range of 3μm to 5μm, a range that matches the opening size of the via 11 and the designed thickness of the physical vapor deposition layer 4. If the radius of the chamfer 3 is less than 3μm, the radius of curvature of the chamfered region is too small, geometrically approaching the state of an un-chamfered acute angle, which cannot effectively eliminate the particle shadow area and tip deposition effect at the opening edge. If the radius of the chamfer 3 is greater than 5μm, the chamfered region will extend excessively towards the surface of the glass substrate 1 and the inner wall of the via 11, occupying the limited area at the opening of the via 11, which may reduce the effective cross-sectional area at the opening of the via 11 for receiving sputtered particles, thus affecting the initial flux of particles entering the via 11. The radius range of 3μm to 5μm strikes a proper balance between eliminating the acute angle effect and maintaining the effective cross-sectional area of ​​the opening. The chamfer 3 can smoothly transition the geometric transition of the opening edge without substantially affecting the opening size of the via 11.

[0085] Please see Figure 3 and Figure 4 In some embodiments, the physical vapor deposition layer 4 includes a barrier layer covering the inner wall and a conductive layer covering the barrier layer, and the electroplated metal layer 2 fills the through-hole 11 in which the physical vapor deposition layer 4 is deposited.

[0086] The electroplated metal layer 2 fills the through-hole 11 into which the physical vapor deposition layer 4 is deposited. Specifically, the physical vapor deposition layer 4 is located between the inner wall of the through-hole 11 and the electroplated metal layer 2. The electroplated metal layer 2 does not directly contact the glass substrate 1, but rather achieves indirect bonding through the physical vapor deposition layer 4 to the inner wall of the through-hole 11. In this structure, the physical vapor deposition layer 4 simultaneously functions as a transition layer and an adhesion layer. On one hand, it provides a uniform electroplating starting surface for the filling of the electroplated metal layer 2; on the other hand, it transforms the weak bonding between the electroplated metal layer 2 and the glass substrate 1 from direct contact to a strong bonding transmitted through the physical vapor deposition layer 4, reducing the risk of the electroplated metal layer 2 peeling off from the inner wall of the through-hole 11 under subsequent thermal cycling or mechanical stress.

[0087] The physical vapor deposition layer 4 includes a barrier layer covering the inner wall of the via 11 and a conductive layer covering the barrier layer. This dual-layer structure is designed to meet different functional requirements. The barrier layer directly covers the inner wall of the via 11, and its function is to prevent metal atoms in the conductive layer and the electroplated metal layer 2 from diffusing into the glass substrate 1. Conductive metals such as copper tend to migrate into the glass under the long-term influence of electric and temperature fields. Once metal atoms enter the glass matrix, they will reduce the insulation performance of the glass, which may lead to leakage or short circuit between adjacent vias 11. The barrier layer is composed of chemically stable refractory metals or metal nitrides, forming a diffusion barrier between the glass and the conductive metal. At the same time, the adhesion between the barrier layer and the glass substrate 1 is usually better than the direct adhesion between the conductive metal and the glass, which can improve the overall adhesion strength of the physical vapor deposition layer 4. The conductive layer covers the barrier layer and its function is to provide a low resistivity current conduction path. The conductive layer is usually made of highly conductive metals such as copper, which makes the potential distribution from the substrate surface to the depth of the via 11 more uniform during the electroplating process. This is conducive to the uniform growth of the electroplated metal layer 2 from the bottom of the via 11 upwards, and avoids the filling rate of the depth of the via 11 being lower than that of the opening due to potential decay, thus preventing premature sealing and the formation of internal voids.

[0088] In some embodiments, the barrier layer is made of chromium, titanium, or tantalum, and its thickness is 400 nm to 600 nm. Chromium, titanium, and tantalum are all refractory metals with high chemical stability and good diffusion barrier properties. During long-term operation of the substrate assembly 100, copper atoms in the conductive layer and the electroplated metal layer 2 tend to diffuse into the glass substrate 1 under the influence of current and thermal excitation. Once copper atoms penetrate the physical vapor deposition layer 4 and enter the glass matrix, they will form deep-level impurities or conductive pathways in the glass, reducing the insulation performance between adjacent vias 11, and in severe cases, leading to short-circuit failure. Chromium, titanium, or tantalum, as barrier layer materials, have a dense atomic structure and a low grain boundary diffusion coefficient, which can form an effective diffusion barrier between the glass substrate 1 and the copper conductive layer, preventing the migration of copper atoms into the glass.

[0089] Meanwhile, chromium, titanium, or tantalum exhibits good chemical affinity with the silicon-oxygen structure in the glass substrate 1, enabling them to form a certain degree of chemical bonding or tight physical adsorption with the glass surface during sputtering deposition. This enhances the bonding strength between the barrier layer and the inner wall of the via 11, thereby improving the peel resistance of the physical vapor deposition layer 4 during subsequent electroplating. Furthermore, chromium, titanium, and tantalum all possess excellent sputtering film-forming characteristics in physical vapor deposition processes, allowing them to form a dense and uniformly thick continuous film on the inner wall of the via 11. Combined with the aforementioned necking structure of the via 11, this ensures the continuity of the barrier layer's coverage across the entire inner wall of the via 11.

[0090] The thickness of the barrier layer is limited to 400 nm to 600 nm. If the thickness of the barrier layer is less than 400 nm, it may fail to form a completely continuous coverage in certain micro-rough areas or sections with heavy sputtering shadows on the inner wall of the via 11, posing a risk of localized insufficient thickness or even micro-pinholes. Copper atoms can penetrate the barrier layer and enter the glass substrate 1 through these weak points, thus partially weakening the diffusion barrier function of the barrier layer. If the thickness of the barrier layer is greater than 600 nm, it will occupy too much radial space on the inner wall of the via 11, reducing the effective cross-sectional area of ​​the via 11 for filling the electroplated metal layer 2. This effect is particularly pronounced at the minimum inner diameter of the via 11, which may lead to increased resistance of the electroplated metal layer 2 in the necking region or cross-sectional blockage during electroplating. The thickness range of 400 nm to 600 nm establishes a reasonable balance between sufficient diffusion barrier and preservation of the filling space of the via 11. Within this thickness range, the barrier layer can provide a reliable diffusion barrier without excessively encroaching on the filling space of the electroplated metal layer 2.

[0091] In some embodiments, the conductive layer is made of copper, and its thickness is 0.5 μm to 1 μm. Copper has low resistivity, and its bulk resistivity is second only to silver among commonly used conductive metals. It can provide a low-impedance current conduction path for electroplating filling within a limited film thickness. During the electroplating process of the electroplated metal layer 2, the electroplating current needs to be conducted from the electrodes on the surface of the substrate assembly 100 through the physical vapor deposition layer 4 to various regions of the inner wall of the via 11. If the resistance of the conductive layer of the physical vapor deposition layer 4 is too high, the potential in the depth of the via 11 will be lower than that near the opening of the via 11. The electroplating rate will be unevenly distributed along the axial direction of the via 11. The opening will be preferentially deposited and sealed due to the concentration of current, while the depth of the via 11 will be filled slowly or even not filled at all due to insufficient current, ultimately forming voids inside the electroplated metal layer 2. Copper, as a conductive layer material, has a low resistivity that keeps the axial voltage drop of the physical vapor deposition layer 4 within a small range. The electroplating potential difference between the opening of the through hole 11 and the depth of the through hole 11 is reduced, and the electroplated metal layer 2 can grow uniformly from the bottom of the through hole 11 upwards, achieving complete filling without voids.

[0092] If the thickness of the conductive layer is less than 0.5 μm, the copper conductive layer may not form a completely continuous coverage in certain areas with large curvature on the inner wall of the via 11 or at the troughs of the microscopic undulations on the surface of the barrier layer, posing a risk of insufficient local thickness. These weak areas have limited current conduction capacity during electroplating, which may become a cause of uneven filling of the electroplated metal layer 2. If the thickness of the conductive layer is greater than 1 μm, the radial space occupied by the conductive layer on the inner wall of the via 11 increases, compressing the available filling cross-sectional area of ​​the electroplated metal layer 2, thus increasing the interconnection resistance of the necking region. At the same time, an excessively thick copper conductive layer requires a longer deposition time during sputtering deposition, increasing the heat accumulation of the substrate assembly 100, which may cause increased stress or abnormal grain growth in the physical vapor deposition layer 4, thereby affecting the density and uniformity of the physical vapor deposition layer 4. The thickness range of 0.5 μm to 1 μm achieves a reasonable balance between conductive continuity, axial voltage drop control, and retention of filling space in the via 11.

[0093] Please see Figure 6 , Figure 6 A flowchart illustrating a method for fabricating a substrate assembly 100 provided in this application embodiment. A second aspect of this application embodiment discloses a method for fabricating a substrate assembly 100, the method comprising: S1: Provides the glass substrate body.

[0094] In the step of providing the glass substrate body, a borosilicate glass sheet with a thickness and material that meet the preset requirements is selected as the glass substrate body, and the glass substrate body is cleaned and dried to remove surface oil, particles and adsorbed moisture, so as to provide a clean processing surface for the subsequent through hole 11 forming.

[0095] S2: Form a through hole 11 on the glass substrate body.

[0096] In the step of forming through-holes 11 on the glass substrate, an array of through-holes 11 is fabricated on the glass substrate using a combination of laser-induced and chemical etching. Laser-induced modification regions are formed inside the glass substrate along the predetermined path of the through-holes 11. The chemical etching solution selectively etches the glass material along the modified regions, causing the inner diameter of the through-holes 11 to gradually decrease from the two openings inwards, forming a necking structure. Simultaneously, the etching parameters are controlled to ensure that the inner wall roughness and morphology of the through-holes 11 meet predetermined requirements.

[0097] S3: The glass substrate body is placed in the cavity of the ionization physical vapor deposition equipment, and a physical vapor deposition layer 4 is sputtered and deposited on the inner wall of the through hole 11. During the sputtering and deposition of the physical vapor deposition layer 4, the glass substrate 1 moves back and forth and deflects at an angle relative to the cavity so that the sputtered particles uniformly cover the inner wall of the through hole 11.

[0098] Regarding the pretreatment and post-treatment processes, the multi-step cleaning process before the deposition of the physical vapor deposition layer 4 after the through-hole 11 is formed includes acetone ultrasonic cleaning, deionized water rinsing, and nitrogen drying. After entering the cavity, it undergoes in-situ etching cleaning for 5 to 10 minutes with argon plasma at a power of 300W to 500W to remove residual impurities and surface oxide layers from the inner wall of the through-hole 11 and activate surface chemical bonds to improve the adhesion strength of the physical vapor deposition layer 4. After the physical vapor deposition layer 4 is deposited, it is cooled to room temperature in a vacuum environment. The purpose of this step is to prevent the high-temperature copper conductive layer from oxidizing after being exposed to the atmosphere, thus ensuring the conductivity of the physical vapor deposition layer 4.

[0099] In the step of placing the glass substrate body in the cavity of the ionization physical vapor deposition equipment and sputtering and depositing the physical vapor deposition layer 4 on the inner wall of the through-hole 11, the glass substrate body is first fixed on the movable stage in the cavity. After the cavity is evacuated to a preset background vacuum level, working gas is introduced, and the ionization magnetron sputtering source is turned on to generate metal plasma. During the sputtering deposition process, the stage drives the glass substrate body to move back and forth relative to the cavity. At the same time, the stage drives the glass substrate body to perform left and right angle deflection motion. The back and forth movement ensures that the sputtered particles are fully incident at different depth positions along the axial direction of the through-hole 11. The angle deflection motion causes the sputtered particles to be incident at different tilt angles at the same depth position of the through-hole 11 to different sections of the necked sidewall. The combined effect of these two actions results in a uniform physical vapor deposition layer 4 covering the entire inner wall of the through-hole 11. The sputtering deposition of the physical vapor deposition layer 4 can be performed by sequentially sputtering a barrier layer and a conductive layer. By switching the target material or adjusting the process parameters, a barrier layer covering the inner wall of the through-hole 11 and a conductive layer covering the barrier layer are formed respectively.

[0100] Ionization magnetron sputtering equipment requires the addition of a high aspect ratio collimator, located between the target and the glass substrate, with a target-to-substrate distance of 18cm to 22cm. The collimator uses physical filtration to allow only sputtered particles moving nearly perpendicular to the surface of the glass substrate to pass through, filtering out particles flying at large angles. This results in a higher directional concentration of the particle beam entering the via 11, allowing particles to enter the necked sidewall of the via 11 at a steeper angle, increasing the probability of particles reaching the minimum inner diameter of the via 11. The target-to-substrate distance affects the scattering loss and energy attenuation of particles as they travel from the target surface to the glass substrate; a target-to-substrate distance of 18cm to 22cm strikes a balance between particle transport efficiency and deposition uniformity.

[0101] Regarding process environment parameters, the cavity background vacuum level is less than or equal to 5 × 10⁻⁶. -6The values ​​for Torr and sputtering working pressure range from 0.2 mTorr to 0.4 mTorr. The low background vacuum reduces the contamination of the physical vapor deposition layer 4 by residual gas impurities within the cavity, while the low working pressure reduces collision and scattering between sputtered particles and working gas atoms during flight, maintaining high collimation of the particle incident direction. For barrier layer sputtering, the target power is 6 kW to 8 kW, the substrate negative bias is 80 V to 120 V, the deposition temperature is 80 °C to 100 °C, and the deposition rate is 0.6 Å / s to 0.8 Å / s; for conductive layer sputtering, the target power is 10 kW to 12 kW, the substrate negative bias is 120 V to 160 V, the deposition temperature is 100 °C to 120 °C, and the deposition rate is 1.0 Å / s to 1.5 Å / s, respectively adapting to the differences in sputtering yield and film formation characteristics between the barrier layer and conductive layer materials.

[0102] S4: Cool the deposited glass substrate body in a vacuum environment to obtain glass substrate 1.

[0103] In the step of cooling the deposited glass substrate in a vacuum environment, after the physical vapor deposition layer 4 is sputtered, the sputtering source and working gas are turned off, and the cavity is kept in a vacuum state, allowing the glass substrate to cool naturally to room temperature in a vacuum environment. Cooling in a vacuum environment avoids the high-temperature copper conductive layer from directly contacting oxygen in the atmosphere and causing surface oxidation, thus ensuring the conductivity and surface condition of the physical vapor deposition layer 4.

[0104] S5: An electroplated metal layer 2 and a circuit layer are formed on the glass substrate 1 to form a substrate assembly 100.

[0105] In the step of setting the electroplated metal layer 2 and the circuit layer on the glass substrate 1, the cooled glass substrate body is taken out from the cavity, and electroplating is performed using the physical vapor deposition layer 4 as a conductive substrate, so that the conductive metal grows uniformly from the bottom of the through hole 11 upward and fills the internal space of the through hole 11 to form the electroplated metal layer 2. Then, the excess conductive metal on the surface of the glass substrate body is removed by planarization treatment, and then a patterned circuit layer is formed on the surface of the glass substrate body by photolithography, etching or electroplating addition process, so that the circuit layer and the end of the electroplated metal layer 2 are electrically connected to obtain the substrate assembly 100.

[0106] The substrate assembly 100 preparation method disclosed in this application combines the static necked via 11 structure with dynamic substrate movement by simultaneously moving the glass substrate body back and forth and deflecting its angle during the sputtering deposition of the physical vapor deposition layer 4. This allows sputtered particles to enter the via 11 at constantly changing angles and positions and effectively impact the necked sidewalls, overcoming the defect of insufficient particle coverage in the deep part of the via 11 or the waisted recessed area under single static sputtering conditions. This achieves uniform and continuous deposition of the physical vapor deposition layer 4 on the entire inner wall of the via 11.

[0107] Please see Figure 7 , Figure 7 A detailed flowchart of step S2 in the method for fabricating the substrate assembly 100 provided in this application embodiment. In some embodiments, the step of forming a through hole 11 on the glass substrate 1 specifically includes: S21: A laser is used to irradiate a preset position on the glass substrate 1 to form a laser modification channel that penetrates the glass substrate 1.

[0108] In the step of forming through-holes 11 on the glass substrate 1, the cleaned and dried glass substrate is first fixed on a laser processing platform. Following a pre-defined pattern of through-holes 11, the glass substrate is irradiated at predetermined positions using a laser. The laser beam is focused on the interior or surface of the glass substrate. Utilizing the ultra-short duration and high peak power density of the laser pulse, a nonlinear absorption effect is induced in the glass material. At the laser focal point, the glass material undergoes chemical bond breakage and structural modification due to instantaneous energy deposition, forming laser-modified channels penetrating the upper and lower surfaces of the glass substrate. The material of the laser-modified channels differs from the original glass substrate that has not been irradiated by the laser in both physical structure and chemical composition. Its density is reduced, its microstructure is looser, and its chemical activity is increased, providing a preferential etching path for subsequent chemical etching.

[0109] S22: The laser-treated glass substrate 1 is placed in an etching solution, and the etching solution is used to chemically etch the hole wall of the laser-modified channel to form a through hole 11.

[0110] The laser-treated glass substrate is placed in an etching solution, typically an acidic solution that reacts chemically with the silica in the glass. The etching solution preferentially etches along the walls of the laser-modified channels. Because the chemical reactivity of the material in the laser-modified channel region is much higher than that of the unmodified glass substrate, the etching rate of the etching solution in the modified region is greater than that on the surface of the unmodified substrate, and the aperture of the laser-modified channel gradually increases during the etching process.

[0111] By controlling the concentration of the etching solution, the etching temperature, and the etching time, the axial evolution of the inner diameter of the through-hole 11 can be adjusted, causing the inner diameter of the through-hole 11 to gradually decrease from the two openings towards the interior, forming a necked structure with a smooth transition of the inner wall. During the etching process, the dissolving effect of the etching solution on the hole wall simultaneously eliminates the micro-cracks and surface protrusions on the laser-modified channel hole wall caused by laser impact, reducing the roughness of the inner wall of the through-hole 11 to a preset range. After etching, the glass substrate is removed from the etching solution, rinsed with deionized water, and dried with nitrogen to obtain the through-hole 11 with the preset necked morphology and surface quality.

[0112] In some embodiments, during the sputtering deposition of the physical vapor deposition layer 4, the glass substrate 1 performs reciprocating movement and angular deflection movement, specifically including: the reciprocating movement is a linear reciprocating motion along a direction parallel to the surface of the glass substrate 1 and perpendicular to the axis L of the through hole; while the reciprocating movement is performed, the glass substrate 1 performs angular deflection movement, which is a periodic oscillation around the axis L of the through hole.

[0113] During the sputtering deposition of the physical vapor deposition layer 4, the reciprocating movement of the glass substrate refers to the linear reciprocating motion of the glass substrate along a direction parallel to its surface, perpendicular to the axis L of the via. This linear reciprocating motion causes the planar position of the via 11 relative to the sputtering particle source to change periodically within the movement range, and the projection area of ​​the sputtering particle beam at the opening of the via 11 scans back and forth along the movement direction. When the glass substrate moves to different positions, the relative azimuth angle of particles emitted from the same sputtering source entering the via 11 changes, and the sidewall sections on both sides of the inner wall of the via 11 along the movement direction can take turns obtaining direct particle incident opportunities, avoiding the phenomenon that a certain sidewall is always in the particle incident shadow area due to the geometric offset between the sputtering source and the via 11 during fixed-position sputtering. The stroke and speed of the linear reciprocating motion can be set according to the inner diameter of the opening of the through hole 11 and the divergence angle range of the sputtered particle source, so that each area of ​​the inner wall of the through hole 11 along the direction of motion can obtain sufficient particle coverage in a single round trip cycle.

[0114] During the reciprocating motion, the glass substrate undergoes an angular deflection motion, which refers to the periodic oscillation of the glass substrate around the axis L of the through-hole. As the glass substrate moves, the axis L of the through-hole tilts relative to the incident direction of the sputtered particles in space due to the angular deflection of the substrate. Therefore, different circumferential positions on the inner wall of the through-hole 11 are sequentially included within the coverage range of the effective incident angle of the particles. The amplitude and rate of the periodic oscillation can be matched and set according to the shrinkage ratio of the necking structure of the through-hole 11 and the deposition rate of the physical vapor deposition layer 4. Within the oscillation amplitude range, similar particle accumulation deposition amounts can be obtained in each circumferential section of the inner wall of the through-hole 11.

[0115] The simultaneous reciprocating motion and angular deflection motion cause the particle incident conditions at any position on the inner wall of the through-hole 11 to continuously change over time and tend to homogenize. The front and rear sidewalls along the reciprocating motion direction achieve uniform coverage through position scanning, while the different circumferential sidewalls around the axis achieve uniform coverage through angular oscillation. The synergistic effect of the two motions ensures that the entire inner wall of the through-hole 11 receives a sufficient and uniform sputtered particle flow during the deposition of the physical vapor deposition layer 4, thus achieving continuous and uniform deposition of the physical vapor deposition layer 4 on the inner wall of the necked through-hole 11 from a process perspective.

[0116] In some embodiments, the reciprocating movement speed is 10 mm / min, and the movement range is 2 m to 4 m. A movement speed of 10 mm / min is considered a low-speed uniform scan. At this speed, the displacement of the via 11 relative to the sputtering particle source per unit time is small, and each via 11 remains within the effective irradiation area of ​​the sputtering particle beam for a sufficiently long time, ensuring that sufficient sputtered particle deposition is received at all depths along the movement direction on the inner wall of the via 11 during a single scan. If the movement speed is too fast, the time the via 11 spends in the particle beam irradiation area is too short, resulting in insufficient particle accumulation in a single scan. This necessitates increasing the number of scans to achieve the preset physical vapor deposition layer 4 thickness, reducing process efficiency and potentially causing interlayer interfaces due to multiple intermittent depositions. If the movement speed is too slow, the via 11 remains within the particle beam irradiation area for too long, and the particle accumulation rate near the opening may exceed the deposition rate at the depth of the via 11, leading to excessive thickness of the physical vapor deposition layer 4 at the opening, which is detrimental to the uniformity of the physical vapor deposition layer 4 across the entire inner wall of the via 11. A moving speed of 10 mm / min establishes a suitable balance between deposition efficiency and thickness uniformity, resulting in a moderate deposition increment per scan. After multiple round-trip scans, the thickness distribution of the physical vapor deposition layer 4 along the axial direction of the via 11 tends to be uniform.

[0117] The movement range is limited to 2m to 4m, which refers to the path length range traversed by the glass substrate body in a single linear reciprocating motion. This 2m to 4m movement range is larger than the actual size of a single glass substrate body, meaning that the glass substrate body does not only vibrate within its own size range during sputtering deposition, but also performs a long-range back-and-forth scanning motion along a straight line. Different vias 11 on the glass substrate body, as well as different positional intervals of the same via 11 in the direction of movement, can all experience alternating irradiation of the high-density region at the center and the low-density region at the edge of the particle beam. In a long-term statistical sense, the total particle dose received by each via 11 tends to be consistent, thus ensuring the intra-sheet uniformity of the physical vapor deposition layer 4 thickness among vias 11 at different positions on the substrate assembly 100.

[0118] In some embodiments, the deflection rate of the angle deflection motion is 1° / min, and the deflection angle range is ±9°. The low deflection rate of 1° / min means that the angular orientation of the glass substrate changes slowly and steadily during the sputtering deposition process. Each circumferential segment of the inner wall of the via 11 has sufficient time to face the incident direction of the sputtered particle stream within a single deflection cycle. If the deflection rate is too high, the geometric orientation of the same circumferential position on the inner wall of the via 11 will change significantly before sufficient deposition is achieved, potentially weakening the continuity of the physical vapor deposition layer 4 at that position. If the deflection rate is too low, the time consumed in a single deflection cycle will be too long, significantly extending the process time required to achieve uniform coverage across the entire circumference, which is detrimental to mass production efficiency. The deflection rate of 1° / min establishes a reasonable balance between deposition quality and process efficiency, ensuring that the particle reception time of each circumferential segment of the inner wall of the via 11 meets the requirements for sufficient deposition without excessively prolonging the overall process cycle.

[0119] The deflection angle range is limited to ±9°, which limits the maximum amplitude of the glass substrate body's swing around the axis of the via 11. When the glass substrate body swings to the extreme position of ±9° or ±9°, the circumferential position of the inner wall of the via 11, which was initially horizontal, is in the particle incident shadow area. Due to the overall tilt of the axis of the via 11 relative to the incident direction of the sputtered particles, it is freed from the shadow obstruction, and the sputtered particles can directly reach these circumferential areas that were originally difficult to cover. If the deflection angle range exceeds ±9°, the tilt of the axis of the via 11 relative to the incident direction of the sputtered particles is too large. The opening edge on one side of the via 11 may form a new geometric obstruction inside the via 11, causing some areas deep in the via 11 to fall back into the incident shadow due to excessive tilting. At the same time, an excessively large deflection angle may cause the via 11 in the edge area of ​​the glass substrate body to deviate from the effective irradiation range of the sputtered particle source, affecting the deposition quality of the physical vapor deposition layer 4 of the via 11 at the edge of the substrate.

[0120] The coordinated operation of a deflection rate of 1° / min and a deflection angle range of ±9° allows the glass substrate to undergo a slow and limited circumferential scanning motion on top of its reciprocating movement. The combined effect of these two motion modes ensures sufficient and uniform particle coverage on different axial sections of the inner wall of the via 11 along the direction of movement and on different circumferential sections around the axis during sputtering deposition. This guarantees the continuity and uniformity of the physical vapor deposition layer 4 on the entire inner wall of the necked via 11 from the perspective of process motion parameters.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A substrate assembly, characterized in that, The substrate assembly includes: A glass substrate, the glass substrate comprising: A through-hole penetrates the glass substrate in a direction perpendicular to the glass substrate. Along the extension direction of the through-hole, the inner diameter of the through-hole gradually decreases from the two openings towards the interior of the through-hole, so that the through-hole has a necking structure. The inner wall of the through-hole is a smooth and continuous curved surface with a roughness Ra≤100nm. The curved surface is recessed into the central axis of the through-hole to form a necking structure. A physical vapor deposition layer is deposited on the inner wall of the through-hole; An electroplated metal layer, wherein the electroplated metal layer is attached to the physical vapor deposition layer; A circuit layer is disposed on the surface of the glass substrate and electrically connected to the electroplated metal layer; The geometric relationship between the minimum inner diameter of the through hole and the inner diameter at the opening of the through hole satisfies the following condition: gaseous sputtered particles incident from one side opening edge of the through hole at a preset tilt angle can be deposited at the minimum inner diameter of the through hole.

2. The substrate assembly according to claim 1, characterized in that, The ratio between the depth of the through hole and the inner diameter at the opening of the through hole is less than or equal to 10:

1.

3. The substrate assembly according to claim 2, characterized in that, The inner diameter of the through hole gradually decreases from the two ends of the opening towards the inside of the through hole, and the decrease in the inner diameter of the through hole first increases and then decreases.

4. The substrate assembly according to claim 3, characterized in that, The minimum inner diameter of the through hole is located in the middle region of the through hole in its own extension direction, and the minimum inner diameter of the through hole is 65% to 75% of the inner diameter at the opening of the through hole.

5. The substrate assembly according to any one of claims 1-4, characterized in that, The opening of the through hole is formed with a rounded chamfer, the radius of which is 3μm to 5μm.

6. The substrate assembly according to any one of claims 1-4, characterized in that, The physical vapor deposition layer includes a barrier layer covering the inner wall and a conductive layer covering the barrier layer, and the electroplated metal layer fills the through hole in which the physical vapor deposition layer is deposited; Wherein, the barrier layer is made of chromium, titanium, or tantalum, and the thickness of the barrier layer is 400 nm to 600 nm; and / or, The conductive layer is made of copper and has a thickness of 0.5 μm to 1 μm.

7. A method for preparing a substrate assembly, characterized in that, The method for preparing the substrate assembly includes: Provide glass substrate body; A through hole is formed on the glass substrate body; The glass substrate body is placed in the cavity of the ionization physical vapor deposition equipment, and a physical vapor deposition layer is sputtered and deposited on the inner wall of the through hole. During the sputtering and deposition of the physical vapor deposition layer, the glass substrate moves back and forth and deflects at an angle relative to the cavity so that the sputtered particles uniformly cover the inner wall of the through hole. The deposited glass substrate body is cooled in a vacuum environment to obtain a glass substrate; An electroplated metal layer and a circuit layer are formed on the glass substrate to form the substrate assembly.

8. The method for preparing a substrate assembly according to claim 7, characterized in that, The step of forming through holes on the glass substrate specifically includes: A laser is used to irradiate a predetermined position on the glass substrate to form a laser modification channel that penetrates the glass substrate. The laser-treated glass substrate is placed in an etching solution, and the etching solution is used to chemically etch the hole walls of the laser-modified channel to form the through hole.

9. The method for preparing a substrate assembly according to claim 7, characterized in that, The steps of reciprocating movement and angular deflection of the glass substrate during the sputtering deposition of the physical vapor deposition layer specifically include: The reciprocating movement is a linear reciprocating motion performed along a direction parallel to the surface of the glass substrate and perpendicular to the axis of the through hole; During the reciprocating motion, the glass substrate undergoes an angular deflection motion, which is a periodic oscillation around the axis of the through hole.

10. The method for preparing a substrate assembly according to claim 9, characterized in that, The reciprocating movement speed is 10 mm / min, and the movement range is 2 m to 4 m; and / or, The deflection speed of the angle deflection motion is 1° / min, and the deflection angle range is ±9°.

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