Rigid-flexible hybrid three-dimensional wafer architecture millimeter wave on-crystal array

Abstract

The invention discloses a rigid-flexible hybrid three-dimensional wafer architecture millimeter wave on-crystal array which comprises a plurality of rigid silicon-based wafers, a middle layer flexible material wafer is arranged between every two adjacent rigid silicon-based wafers, a rigid glass-based wafer is arranged on the upper end face of the rigid silicon-based wafer on the uppermost layer, and a rigid glass-based wafer is arranged on the upper end face of the rigid glass-based wafer on the uppermost layer. An upper layer flexible material wafer is arranged on the upper end face of the rigid glass-based wafer, and a lower layer flexible material wafer is arranged on the lower end face of the rigid silicon-based wafer on the lowermost layer. According to the invention, an engineering technical route of a large-scale millimeter wave front-end array is evolved from a layer-by-layer stacking type to a splicing assembly type which is formed by heterogeneous integration of various chips made of heterogeneous materials and manufactured by different manufacturing processes, so that the defect that a flexible conformal antenna cannot be realized by a traditional rigid silicon-based wafer is overcome; the thermal mismatch pain point during direct interconnection of the traditional silicon-based wafer and the PCB and the pain point of large millimeter wave radio frequency signal transmission loss of the traditional three-dimensional stacked silicon-based wafer are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wafer-on-wafer systems, and in particular relates to a rigid-flexible hybrid three-dimensional wafer-structured millimeter-wave wafer-on-wafer array. Background Art

[0002] As integrated circuit lithography technology enters the 5 nm and below process nodes, transistor size miniaturization is gradually approaching the physical limit, and Moore's Law seems to be coming to an end. The traditional technical path of improving chip performance by improving semiconductor process technology is difficult, which forces the industry to explore new and more cost-effective technical routes to meet the growing demand for chip performance, including various "Beyond Moore" technical routes.

[0003] System-on-wafer technology is one of the most popular "More Than Moore" technology routes in the industry. It integrates computing, sensing, storage, communication and other functional prefabricated components (unpackaged bare chips) on the same silicon-based wafer according to application scenario requirements to form one or more physical systems. It also achieves an order of magnitude improvement in overall performance through system architecture innovation, ultra-high density interconnection integration, software-defined and other enabling technologies.

[0004] The millimeter-wave on-chip system is mainly aimed at the application requirements of miniaturization, lightness and multi-function such as integrated RF front-end and active array in frontier fields such as 5G communication and phased array radar. It is based on electronic components such as microelectronics, optoelectronics, MEMS, etc., and adopts micro-system heterogeneous and heterogeneous integration process technology represented by micro-nano processing technology. It combines architecture, software and algorithms to integrate RF, digital, optoelectronic, energy and other subsystems with high density, so as to greatly reduce the volume and power consumption of RF system and greatly improve performance and reliability. The millimeter-wave on-chip system has a wide range of applications in frontier fields such as information technology, industrial control, and consumer electronics.

[0005] Traditional millimeter-wave front-end arrays use a layer-by-layer stacking engineering technology route of chip → module → component → array, which faces development bottlenecks in performance, power consumption, latency, reliability, and other aspects. Originally, the chip could exert 100% of its power. When the system is built according to the existing "stacking" engineering technology route, the power has been reduced to only 10% at the system level. In view of the defects of the existing engineering technology route, the present invention provides a rigid-flexible hybrid three-dimensional wafer architecture millimeter-wave on-wafer array. Summary of the invention

[0006] Technical problems solved: In response to the above technical problems, the present invention provides a rigid-flexible hybrid three-dimensional wafer architecture millimeter-wave on-wafer array, which evolves the engineering technology route of large-scale millimeter-wave front-end arrays from "layer-by-layer stacking" to "splicing and assembling" of heterogeneous integration of various chips made of heterogeneous materials and different process technologies, solving the defect that traditional rigid silicon-based wafers cannot realize flexible conformal antennas, solving the pain point of thermal mismatch when traditional silicon-based wafers and PCBs are directly interconnected, and solving the pain point of large millimeter-wave RF signal transmission loss in traditional three-dimensional stacked silicon-based wafers.

[0007] Technical solution: A rigid-flexible hybrid three-dimensional wafer architecture millimeter-wave wafer array, including a plurality of rigid silicon-based wafers, an intermediate flexible material wafer is arranged between two adjacent rigid silicon-based wafers, a rigid glass-based wafer is arranged on the upper end surface of the topmost rigid silicon-based wafer, an upper flexible material wafer is arranged on the upper end surface of the rigid glass-based wafer, and a lower flexible material wafer is arranged on the lower end surface of the bottommost rigid silicon-based wafer; Any one or several layers of the rigid silicon-based wafer are provided with bare chips inside, and the positions of the bare chips are arranged according to the design requirements of the millimeter-wave on-wafer array; TSVs are provided inside the rigid silicon-based wafer, and the positions and number of the TSVs are designed according to the vertical transmission requirements of the millimeter-wave on-wafer array; RDLs are provided on the upper and lower end surfaces of the rigid silicon-based wafer, and the number and positions of the RDLs are designed according to the planar transmission requirements of the millimeter-wave on-wafer array; IPDs are provided inside the rigid silicon-based wafer, and the positions and number of the IPDs are arranged according to the circuit design of the millimeter-wave on-wafer array; the upper flexible material wafer or the lower flexible material wafer The upper end surface, the lower end surface and the interior of the material wafer are provided with metallization structures, and the positions and the number of the metallization structures are arranged according to the circuit design of the upper flexible material wafer or the lower flexible material wafer; the lower end surface of the lower flexible material wafer is provided with an interconnection structure, and the positions and the number of the interconnection structures are designed according to the interconnection transmission requirements of the lower flexible material wafer; the interior of the middlemost rigid silicon-based wafer is provided with a cantilever structure transmission line, which together with the upper flexible material wafer and the lower flexible material wafer constitutes a cantilever structure strip line, and the position and the size of the cantilever structure transmission line are designed according to the planar transmission requirements inside the rigid silicon-based wafer.

[0008] Preferably, the rigid silicon-based wafer realizes stacking of multiple layers of silicon-based wafers in the Z direction through wafer-level bonding.

[0009] Preferably, the rigid glass-based wafer is stacked on the upper end surface of the uppermost rigid silicon-based wafer by wafer-level bonding.

[0010] Preferably, the upper flexible material wafer and the lower flexible material wafer are stacked on the upper end surface of the rigid glass-based wafer and the lower end surface of the lowest rigid silicon-based wafer respectively through wafer-level bonding.

[0011] Preferably, the interconnect structure includes a solder ball, a solder column or a bump.

[0012] Preferably, the rigid glass-based wafer is provided with an air cavity structure, which, combined with the upper flexible material wafer, can realize an ultra-thin flexible conformal antenna with a low dielectric constant and low loss in the air cavity structure.

[0013] Preferably, the thermal expansion coefficient of the lower flexible material wafer is between that of silicon and PCB.

[0014] Beneficial effects: 1) The rigid-flexible hybrid three-dimensional wafer millimeter-wave on-wafer array of the present invention has an upper flexible material wafer stacked on the upper end surface of a rigid glass-based wafer by wafer-level bonding. The rigid glass-based wafer has a cavity structure, and combined with the upper flexible material wafer, a low dielectric constant and low loss ultra-thin flexible conformal antenna with an air cavity structure can be realized, which solves the defect that traditional rigid silicon-based wafers cannot realize flexible conformal antennas; 2) In the rigid-flexible hybrid three-dimensional wafer millimeter-wave on-wafer array of the present invention, the lower flexible material wafer is stacked on the lower end surface of the rigid silicon-based wafer through wafer-level bonding. The thermal expansion coefficient of the lower flexible material wafer is between that of silicon and PCB, which can effectively buffer the thermal stress between the rigid silicon-based wafer and the PCB, solving the thermal mismatch pain point when the traditional silicon-based wafer and PCB are directly interconnected; 3) The rigid-flexible hybrid three-dimensional wafer millimeter-wave on-wafer array of the present invention realizes ultra-low loss millimeter-wave RF signal transmission through the cantilevered structure strip line inside the rigid silicon-based wafer. A layer of flexible material wafer is sandwiched between two adjacent layers of rigid silicon-based wafers. A cantilevered structure transmission line is arranged inside the rigid silicon-based wafer, and together with the adjacent upper and lower layers of flexible material wafers, a cantilevered structure strip line is formed to realize ultra-low loss millimeter-wave RF signal transmission, solving the pain point of high loss in millimeter-wave RF signal transmission of traditional three-dimensional stacked silicon-based wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an overall stereogram of a rigid-flexible hybrid three-dimensional wafer architecture millimeter-wave on-wafer array of the present invention; Figure 2 It is an overall top view of a rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array of the present invention; Figure 3 It is an overall bottom view of a rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array of the present invention; Figure 4 It is an overall side view of a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention; Figure 5 Schematic diagram of a rigid silicon-based wafer in a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention, wherein (a) is a top view and (b) is a side view; Figure 6 Schematic diagram of a rigid glass-based wafer in a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention, wherein (a) is a top view and (b) is a side view; Figure 7 Schematic diagram of an upper flexible material wafer in a rigid-flexible hybrid three-dimensional wafer architecture millimeter-wave on-wafer array of the present invention, wherein (a) is a top view and (b) is a side view; Figure 8 Schematic diagram of a lower flexible material wafer in a rigid-flexible hybrid three-dimensional wafer architecture millimeter-wave on-wafer array of the present invention, wherein (a) is a top view and (b) is a side view; Fig. 9 This is a schematic diagram of a flexible material wafer in the middle layer of a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention, wherein (a) is a top view and (b) is a side view; Fig.10 It is a schematic diagram of a bare chip in a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention; Fig.11 This is a schematic diagram of TSV in a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention; Fig.12 It is a schematic diagram of RDL in a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention; Fig.13 This is a schematic diagram of an IPD in a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention; Fig.14 It is a schematic diagram of the metallization structure in a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention; Fig.15 It is a schematic diagram of the interconnection structure in a millimeter-wave on-wafer array of a rigid-flexible hybrid three-dimensional wafer architecture of the present invention; Fig.16 Schematic diagram of a cantilever beam structure stripline in a rigid-flexible hybrid three-dimensional wafer architecture millimeter-wave on-wafer array of the present invention, wherein (a) is a top view and (b) is a side view; Fig.17 Schematic diagram of the air cavity structure in a rigid-flexible hybrid three-dimensional wafer architecture millimeter-wave on-wafer array of the present invention, wherein (a) is a top view and (b) is a side view; Serial numbers in the figure: 1. Rigid silicon-based wafer, 2. Rigid glass-based wafer, 3. Upper flexible material wafer, 4. Lower flexible material wafer, 5. Middle flexible material wafer, 6. Bare chip, 7. TSV, 8. RDL, 9. IPD, 10. Metallization structure, 11. Interconnection structure, 12. Cantilever structure transmission line, 13. Air cavity structure. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments: Example 1

[0017] like Figure 1-Figure 4 As shown, a rigid-flexible hybrid three-dimensional wafer architecture millimeter wave wafer array includes three layers of rigid silicon-based wafers 1, an intermediate layer of flexible material wafers 5 is arranged between two adjacent rigid silicon-based wafers 1, a rigid glass-based wafer 2 is arranged on the upper end surface of the uppermost rigid silicon-based wafer 1, an upper flexible material wafer 3 is arranged on the upper end surface of the rigid glass-based wafer 2, and a lower flexible material wafer 4 is arranged on the lower end surface of the rigid silicon-based wafer 1 of the lowermost layer. The middlemost rigid silicon-based wafer 1 is provided with a bare chip 6, and the position of the bare chip 6 is arranged according to the design requirements of the millimeter-wave on-wafer array; the rigid silicon-based wafer 1 is provided with a TSV 7, and the position and number of the TSV 7 are designed according to the vertical transmission requirements of the millimeter-wave on-wafer array; the upper and lower end surfaces of the rigid silicon-based wafer 1 are both provided with an RDL 8, and the number and position of the RDL 8 are designed according to the planar transmission requirements of the millimeter-wave on-wafer array; the rigid silicon-based wafer 1 is provided with an IPD 9, and the IPD 9 is arranged according to the circuit design of the millimeter wave wafer array; the upper end surface, lower end surface and interior of the upper flexible material wafer 3 or the lower flexible material wafer 4 are provided with a metallization structure 10, and the position and quantity of the metallization structure 10 are arranged according to the circuit design of the upper flexible material wafer 3 or the lower flexible material wafer 4; the lower end surface of the lower flexible material wafer 4 is provided with an interconnection structure 11, and the position and quantity of the interconnection structure 11 are designed according to the interconnection transmission requirements of the lower flexible material wafer 4; the interior of the middlemost rigid silicon-based wafer 1 is provided with a cantilever structure transmission line 12, which together with the upper flexible material wafer 3 and the lower flexible material wafer 4 constitute a cantilever structure strip line, and the position and size of the cantilever structure transmission line 12 are designed according to the planar transmission requirements inside the rigid silicon-based wafer 1.

[0018] like Figure 5 As shown, the rigid silicon-based wafer 1 is bonded at the wafer level to achieve stacking of multiple layers of silicon-based wafers in the Z direction.

[0019] like Figure 6 As shown, the above-mentioned rigid glass-based wafer 2 is stacked on the upper end surface of the uppermost rigid silicon-based wafer 1 through wafer-level bonding.

[0020] like Figure 7-Figure 8 As shown, the upper flexible material wafer 3 and the lower flexible material wafer 4 are stacked on the upper end surface of the rigid glass-based wafer 2 and the lower end surface of the bottommost rigid silicon-based wafer 1 respectively through wafer-level bonding.

[0021] like Fig. 9As shown, the intermediate layer flexible material wafer 5 is clamped by two adjacent layers of rigid silicon-based wafers 1 .

[0022] like Fig.10 As shown, the bare chip 6 is arranged inside any one or several layers of the rigid silicon-based wafer 1 .

[0023] like Fig.11 As shown, the TSV 7 is arranged inside each layer of the rigid silicon-based wafer 1 and serves as a vertical signal transmission medium in the Z direction.

[0024] like Fig.12 As shown, the RDL 8 is arranged on the upper end surface and the lower end surface of each layer of the rigid silicon-based wafer 1, and serves as a signal plane wiring medium in the X and Y directions.

[0025] like Fig.13 As shown, the above-mentioned IPD 9 is arranged inside each layer of rigid silicon-based wafer 1 to form an integrated passive device.

[0026] like Fig.14 As shown, the metallization structure 10 is disposed on the upper end surface, the lower end surface and the interior of the upper flexible material wafer 3 or the lower flexible material wafer 4 to serve as a signal transmission medium of the flexible material wafer.

[0027] like Fig.15 As shown, the interconnection structure 11 includes solder balls, solder pillars or bumps, which serve as the interconnection medium between the lower flexible material wafer 4 and the PCB.

[0028] like Fig.16 As shown, the cantilever structure transmission line 12 arranged inside the above-mentioned rigid silicon-based wafer 1, together with the upper flexible material wafer 3 and the lower flexible material wafer 4, constitutes a cantilever structure strip line to achieve ultra-low loss millimeter wave RF signal transmission.

[0029] like Fig.17 As shown, the above-mentioned rigid glass-based wafer 2 is provided with an air cavity structure 13, and combined with the upper flexible material wafer 3, a low dielectric constant and low loss ultra-thin flexible conformal antenna of the air cavity structure 13 can be realized.

[0030] The thermal expansion coefficient of the lower flexible material wafer 4 is between that of silicon and PCB, and can effectively buffer the thermal stress between the rigid silicon-based wafer and the PCB.

[0031] The present invention is applicable to on-chip arrays in the millimeter wave frequency band, which solves the pain points of the traditional millimeter wave front-end array layer-by-layer stacking engineering technology route in terms of performance, power consumption, latency, etc., and can realize a RF front-end array in the DC to 40 GHz frequency band.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array, characterized by: Comprising a plurality of layers of rigid silicon-based wafers (1), an intermediate layer of flexible material wafers (5) is provided between two adjacent rigid silicon-based wafers (1), a rigid glass-based wafer (2) is provided on the upper end surface of the uppermost rigid silicon-based wafer (1), an upper layer of flexible material wafer (3) is provided on the upper end surface of the rigid glass-based wafer (2), and a lower layer of flexible material wafer (4) is provided on the lower end surface of the lowermost rigid silicon-based wafer (1); A bare chip (6) is arranged inside any one or more layers of the rigid silicon-based wafer (1), and the position of the bare chip (6) is arranged according to the design requirements of the millimeter wave on-wafer array; The rigid silicon-based wafer (1) is provided with TSVs (7) inside, and the positions and number of the TSVs (7) are designed according to the vertical transmission requirements of the millimeter wave on-wafer array; The upper end surface and the lower end surface of the rigid silicon-based wafer (1) are both provided with RDL (8), and the number of layers and positions of the RDL (8) are designed according to the planar transmission requirements of the millimeter wave on-wafer array; An IPD (9) is provided inside the rigid silicon-based wafer (1), and the position and number of the IPD (9) are arranged according to the circuit design of the millimeter wave on-wafer array; The upper end surface, the lower end surface and the interior of the upper flexible material wafer (3) or the lower flexible material wafer (4) are provided with a metallized structure (10), and the position and quantity of the metallized structure (10) are arranged according to the circuit design of the upper flexible material wafer (3) or the lower flexible material wafer (4); The lower end surface of the lower flexible material wafer (4) is provided with an interconnection structure (11), and the position and number of the interconnection structure (11) are designed according to the interconnection transmission requirements of the lower flexible material wafer (4); A cantilever structure transmission line (12) is provided inside the middlemost rigid silicon-based wafer (1), which together with the upper flexible material wafer (3) and the lower flexible material wafer (4) form a cantilever structure strip line, wherein the position and size of the cantilever structure transmission line (12) are designed according to the planar transmission requirements inside the rigid silicon-based wafer (1).

2. The rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array according to claim 1, characterized in that: The rigid silicon-based wafer (1) achieves stacking of multiple layers of silicon-based wafers in the Z direction through wafer-level bonding.

3. The rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array according to claim 1, characterized in that: The rigid glass-based wafer (2) is stacked on the upper end surface of the uppermost rigid silicon-based wafer (1) through wafer-level bonding.

4. The rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array according to claim 1, characterized in that: The upper flexible material wafer (3) and the lower flexible material wafer (4) are respectively stacked on the upper end surface of the rigid glass-based wafer (2) and the lower end surface of the lowest rigid silicon-based wafer (1) through wafer-level bonding.

5. The rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array according to claim 1, characterized in that: The interconnection structure (11) includes a solder ball, a solder column or a bump.

6. The rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array according to claim 1, characterized in that: The rigid glass-based wafer (2) is provided with an air cavity structure (13), and combined with the upper flexible material wafer (3), a low dielectric constant, low loss ultra-thin flexible conformal antenna of the air cavity structure (13) can be realized.

7. The rigid-flexible hybrid three-dimensional wafer structure millimeter-wave on-wafer array according to claim 1, characterized in that: The thermal expansion coefficient of the lower flexible material wafer (4) is between that of silicon and PCB.

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