An NV color center sensor hetero-integrated packaging structure and a preparation method thereof

Abstract

The application discloses a kind of NV color center sensor hetero-integrated packaging structure and preparation method thereof, hetero-integrated structure includes top optical component, microwave drive chip, diamond sensing chip, photoelectric detection chip, micro-bump interconnection layer, packaging substrate and heat management layer, packaging substrate is provided with vertical interconnection through-hole, RDL rewiring layer and surface microwave excitation structure are provided above packaging substrate, surface microwave excitation structure is independent of the embedding interconnection area of RDL rewiring layer, heat management layer is set below packaging substrate.Preparation method includes top optical component preparation, packaging substrate interconnection structure formation, multi-chip hetero-pasting, top optical component alignment integration and heat management layer formation and the like steps.The application realizes the layered construction and collaborative integration of optical path, microwave path, electrical signal path and heat diffusion path, and can provide packaging implementation scheme for miniaturization, modularization and engineering application of NV color center sensor.

Description

Technical Field

[0001] This invention relates to the field of quantum sensor packaging and advanced packaging integration technology, specifically to a heterogeneous integrated packaging structure for an NV color center sensor and its fabrication method. Background Technology

[0002] NV (Nitrogen-Vacancy) color center sensors are a class of quantum sensors based on the sensitive response of the electron spin states of NV color centers in diamond to external physical fields (such as magnetic, electrical, and thermal fields). Due to their advantages such as room-temperature optical initialization and spin state readout, high magnetic field sensitivity, nanometer-scale spatial resolution, and excellent chemical stability, they have significant application value in fields such as weak magnetic field detection, intracellular biophysical quantity detection, non-destructive testing of materials, and high-precision inertial navigation. As quantum sensing technology moves towards practical integration, developing a highly integrated, miniaturized, and highly reliable NV color center sensor packaging architecture has become a core issue that the industry urgently needs to address.

[0003] In existing technologies, NV color center (NV) sensing systems mostly employ a discrete component layout, consisting of a diamond chip, laser source, microwave radiation unit, fluorescence collection optical path, and signal processing module assembled through mechanical supports. While this approach has achieved functional verification, it suffers from drawbacks such as large size, difficulty in optical path collimation, high RF transmission loss, and high parasitic parameters, severely limiting its application in complex portable scenarios. To improve integration, some research attempts to leverage micro-nano fabrication and MEMS integration processes, aiming to integrate microwave antennas, micro-filters, or photodetector units into a single package. However, NV color center sensors differ fundamentally from traditional microelectronic devices; their performance is highly dependent on efficient coupling of excitation light, uniform excitation of the microwave field, lossless readout of the fluorescence signal, and precise control of the operating temperature. Simply pursuing miniaturization of physical dimensions often leads to severe electromagnetic interference or optical obstruction between functional units. Furthermore, the mechanical stress and thermal mismatch strain introduced by traditional packaging processes directly disturb the diamond lattice environment, inducing NV color center energy level drift, which in turn leads to decreased sensitivity and signal distortion.

[0004] Therefore, the advanced packaging of NV color center sensors is not a simple "device stacking," but a complex engineering project involving the coupling of multiple fields such as light, electricity, magnetism, heat, and force. Although advanced heterogeneous integration technology has made some progress in multi-chip co-packaging, for quantum materials such as diamond, which are extremely hard, brittle, and highly sensitive to strain, maintaining stress balance and signal channel transparency in the diamond sensitive area while achieving high-density integration (such as high-density redistribution and interlayer interconnection) remains a key bottleneck restricting the development of quantum sensor chipization.

[0005] Therefore, there is an urgent need to propose a heterogeneous integrated packaging structure for NV color center sensors and its fabrication method, so as to improve the packaging integration and miniaturization level, achieve high-density integration between the diamond chip containing the NV color center layer and the microwave driving unit, optical coupling unit, signal readout unit and thermal management unit, and ensure that the NV color center sensing function is effectively realized under integrated packaging conditions. Summary of the Invention

[0006] To overcome the problems of low integration, large module size, and long interconnection paths in the discrete construction method of NV color center sensors in the prior art, as well as the difficulty of simultaneously taking into account the functions of excitation light input, microwave drive, fluorescence readout and thermal management in conventional integration methods, this invention provides a heterogeneous integrated packaging structure for NV color center sensors and its preparation method. While improving the packaging integration and miniaturization level, it realizes the effective construction of NV color center sensing function under high-density packaging conditions.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A heterogeneous integrated packaging structure for an NV color center sensor includes a top optical component, a microwave driver chip, a diamond sensor chip containing an NV color center layer, a photodetector chip, a micro-bump interconnect layer, a packaging substrate, and a thermal management layer.

[0009] The lower end face of the packaging substrate is mounted on the thermal management layer, and the upper end face is provided with an RDL redistribution layer and a surface microwave excitation structure. The surface microwave excitation structure is independent of the buried interconnect area of ​​the RDL redistribution layer. Vertical interconnect vias are formed along the height direction of the packaging substrate. The upper end of the vertical interconnect via is electrically connected to the RDL redistribution layer, and the lower end is electrically connected to an external lead-out terminal or a lower layer interconnect terminal on the lower surface of the packaging substrate.

[0010] The microwave driver chip and the photoelectric detection chip are electrically and mechanically connected to the packaging substrate through a microbump interconnect layer. The diamond sensing chip is connected to the packaging substrate through at least one of the following: mechanical connection, thermal connection, or electrical connection, through the microbump interconnect layer.

[0011] The RDL redistribution layer includes a microwave RDL path and a readout RDL path. The surface microwave excitation structure is located below the NV working area of ​​the diamond sensor chip and is electrically connected to the microwave driver chip through the microwave RDL path in the RDL redistribution layer. The photodetector chip is electrically connected to an external pin through the readout RDL path in the RDL redistribution layer.

[0012] The top optical assembly includes an excitation light input section and a fluorescence collection and guiding section. The excitation light input section is located above the diamond sensor chip, and the fluorescence collection and guiding section is located above the photodetector chip. The excitation light input section includes an excitation light input window and a focusing microlens. The excitation light input window is vertically aligned with the NV working area of ​​the diamond sensor chip. The focusing microlens is located between the excitation light input window and the NV working area of ​​the diamond sensor chip. The NV color center layer of the diamond sensor chip generates fluorescence after being excited by excitation light. The fluorescence collection and guiding section includes a collecting lens, a filter, a 45° reflecting surface, and a coupling lens. The collecting lens, filter, and 45° reflecting surface are sequentially arranged on the fluorescence light propagation path. The coupling lens is arranged on the fluorescence propagation path after reflection by the 45° reflecting surface, and the light output direction or focusing area of ​​the coupling lens corresponds to the light-receiving area of ​​the photodetector chip.

[0013] As a preferred embodiment of the present invention: the photoelectric detection chip and the microwave driving chip are respectively disposed on both sides of the diamond sensing chip, and the microwave driving chip, the diamond sensing chip and the photoelectric detection chip are arranged in parallel partitions on the packaging substrate.

[0014] As a preferred technical solution of the present invention: the surface microwave excitation structure forms an alternating microwave magnetic field near the NV working area of ​​the diamond sensor chip after a radio frequency signal is introduced.

[0015] As a preferred technical solution of the present invention, the surface microwave excitation structure is a microstrip line structure, a coplanar waveguide structure, or a local ring microwave line structure.

[0016] As a preferred embodiment of the present invention, the micro-bump interconnect layer is respectively disposed on the bottom of the microwave driver chip, the diamond sensor chip and the photoelectric detection chip and is connected to the pad area on the upper surface of the packaging substrate.

[0017] As a preferred technical solution of the present invention, the microbump interconnect layer adopts one of copper pillar solder bumps, tin-based solder bumps, or gold-tin microbump structures.

[0018] As a preferred technical solution of the present invention: the thermal management layer includes a thermal diffusion layer and a heat dissipation base plate, the thermal diffusion layer is connected to the bottom of the packaging substrate, and the heat dissipation base plate is disposed below the thermal diffusion layer.

[0019] As a preferred technical solution of the present invention: the chip layer, the packaging substrate and the thermal management layer formed by the top optical component, the microwave driving chip and the diamond sensing chip and the photoelectric detection chip are arranged in layers along the packaging thickness direction.

[0020] A method for heterogeneous integration fabrication of an NV color center sensor includes the following steps:

[0021] S1. Fabrication of the top optical assembly:

[0022] The top optical assembly uses a transparent optical substrate, on which the excitation light input section and the fluorescence collection and light guiding section are formed, as detailed below:

[0023] An excitation light input window and a focusing microlens are formed in the excitation light input section. The excitation light input window is formed by photolithography and etching processes, so that external excitation light can be coupled into the NV working area of ​​the diamond sensor chip in a vertical direction through the excitation light input window and the focusing microlens.

[0024] In the fluorescence collection and light guiding section, a collecting lens, a filter, a 45° reflecting surface, and a coupling lens are formed sequentially. The collecting lens and the coupling lens are formed by microlens molding or micro-nano fabrication processes. The filter is formed by dielectric thin film deposition process. The 45° reflecting surface is formed by bevel processing and then coated with a high-reflectivity film layer. The fluorescence is focused by the collecting lens, then filtered by the filter to remove residual excitation light, then reflected by the 45° reflecting surface to change the propagation direction, and finally coupled to the photodetector chip by the coupling lens.

[0025] S2. Fabrication of openings and vertical interconnect vias on the packaging substrate:

[0026] First, a deep reactive ion etching process is used to create vertical interconnect vias along the height direction of the packaging substrate. Then, an insulating layer, a barrier layer, and a seed layer are formed in sequence. Subsequently, a metal filling process is used to complete the conductive filling. Finally, a planarization process is used to make the upper and lower surfaces of the packaging substrate meet the requirements for redistribution and chip mounting.

[0027] S3 and RDL rewiring layers are formed:

[0028] After completing the fabrication of the vertical interconnect vias, a dielectric insulating layer is first formed on the upper surface of the packaging substrate. Then, photolithography, electroplating and etching processes are used to form the RDL redistribution layer, and pad areas suitable for subsequent microbump interconnects are formed on its surface.

[0029] S4, Surface Microwave Excitation Structure Integration:

[0030] A surface microwave excitation structure is formed on the upper surface of the packaging substrate, below the NV working area corresponding to the diamond sensor chip, using a metal patterning process.

[0031] S5. Fabrication of functional chip interconnect terminals:

[0032] Microwave driver chip, diamond sensor chip and photoelectric detection chip are prepared respectively, and copper pillar solder bumps, tin-based solder bumps or gold-tin micro-bump structures are used on the bottom of them to form pads and micro-bump interconnection layers suitable for advanced packaging interconnection.

[0033] S6. Complete multi-chip heterogeneous integration and mounting:

[0034] The prepared microwave driver chip, diamond sensor chip, and photodetector chip are respectively aligned and mounted on a predetermined area on the upper surface of the packaging substrate. Electrical and mechanical connections are achieved through a microbump interconnect layer and an RDL redistribution layer. The microwave driver chip is located in the left area of ​​the upper surface of the packaging substrate, the diamond sensor chip is located in the middle area, and the photodetector chip is located in the right area. The NV working area of ​​the diamond sensor chip is aligned with the surface microwave excitation structure in the vertical direction. The microwave driver chip is connected to the microwave RDL path, and the photodetector chip is connected to the readout RDL path.

[0035] S7, Top optical components aligned and integrated:

[0036] After completing the multi-chip heterogeneous integration, the excitation light input section and the fluorescence collection and light guide section are precisely aligned and integrated with the diamond sensor chip and the photodetector chip, respectively. During alignment, the excitation light input window is aligned with the NV working area in the diamond sensor chip in the vertical direction, and the relative positions of the fluorescence collection and light guide section with the diamond sensor chip and the photodetector chip are matched. After alignment, the excitation light input section and the fluorescence collection and light guide section are fixed above the diamond sensor chip and the photodetector chip, thereby forming a complete top light-incident and side light-collecting structure.

[0037] S8. Formation of the thermal management layer and external interface exposure:

[0038] A thermal management layer is formed below the packaging substrate, so that the thermal diffusion layer is in contact with the bottom of the packaging substrate, and a heat dissipation base plate is disposed below the thermal diffusion layer.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] This invention constructs an advanced packaged heterogeneous integration structure for NV color center sensors, integrating a diamond chip containing an NV color center layer with a microwave driver chip, a photodetector chip, a top optical component, a surface microwave excitation structure, an RDL redistribution layer, and a thermal management layer at high density. This effectively shortens the interconnection path, reduces the module size, and improves the integration density. Furthermore, it enables the synergistic construction of excitation light input, microwave driving, fluorescence readout, and thermal management functions under high-density packaging conditions, thus providing a feasible packaging implementation path for the miniaturization, modularization, and engineering applications of NV color center sensors. Attached Figure Description

[0041] Figure 1 An overall structural diagram of a heterogeneous integrated structure for an NV color center sensor is shown.

[0042] Figure 2A flowchart of a heterogeneous integration fabrication method for an NV color center sensor is shown;

[0043] Figure 3 A schematic diagram of the product structure in the fabrication method of heterogeneous integration of NV color center sensors is shown;

[0044] Figure 4 A schematic diagram of the hierarchical layout of functional paths is shown.

[0045] List of reference numerals in the attached diagram:

[0046] 1. Top optical components; 101. Excitation light input window; 102. Focusing microlens; 103. Collecting lens; 104. Filter; 105. 45° reflective surface; 106. Coupler lens; 2. Microwave driver chip; 3. Diamond sensor chip; 4. Photodetector chip; 5. Microbump interconnect layer; 6. Packaging substrate; 601. RDL redistribution layer; 602. Vertical interconnect via; 603. Surface microwave excitation structure; 7. Thermal management layer. Detailed Implementation

[0047] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] like Figure 1 As shown, the present invention proposes a heterogeneous integrated packaging structure for an NV color center sensor, comprising a top optical component 1, a microwave driving chip 2, a diamond sensing chip 3, a photoelectric detection chip 4, a micro-bump interconnect layer 5, a packaging substrate 6, and a thermal management layer 7.

[0049] The top optical component 1 is positioned above the diamond sensing chip 3 and the photoelectric detection chip 4, and is used to realize excitation light input, fluorescence collection, filtering, folding and coupling.

[0050] The top optical component 1 includes an excitation light input section and a fluorescence collection and light guiding section, wherein:

[0051] The excitation light input section is provided with an excitation light input window 101 and a focusing microlens 102. External excitation light enters the NV working area of ​​the diamond sensor chip 3 vertically through the excitation light input window 101 and the focusing microlens 102.

[0052] The fluorescence collecting and guiding section is provided with a collecting lens 103, a filter 104, a 45° reflecting surface 105, and a coupling lens 106 in sequence. The fluorescence generated by the NV color center layer in the diamond sensor chip 3 is first focused by the collecting lens 103, then filtered by the filter 104 to remove the residual excitation light, and then the propagation direction is changed by the 45° reflecting surface 105 and coupled to the photodetector chip 4 through the coupling lens 106.

[0053] The microwave driver chip 2, diamond sensor chip 3, and photoelectric detector chip 4 are arranged side by side on top of the packaging substrate 6, and are electrically and mechanically connected to the packaging substrate 6 through the micro-bump interconnect layer 5, wherein:

[0054] The diamond sensor chip 3 is the core sensitive unit, and it has an NV color center layer inside. The NV color center layer is set close to the top optical component 1 and forms the NV working area therein.

[0055] The microwave driver chip 2 is disposed on one side of the diamond sensor chip 3 and is used to receive external radio frequency input signals and output microwave drive signals.

[0056] The photoelectric detection chip 4 is located on the other side of the diamond sensor chip 3 and is used to receive fluorescence guided by the top optical component 1 and convert it into an electrical signal.

[0057] The packaging substrate 6 is located below the microbump interconnect layer 5 and is used to carry the microwave driver chip 2, the diamond sensor chip 3 and the photoelectric detection chip 4, and to provide high-density interconnect paths.

[0058] The packaging substrate 6 has vertical interconnect vias 602, and an RDL redistribution layer 601 is provided on the upper surface of the packaging substrate 6. The RDL redistribution layer 601 includes a microwave RDL path and a readout RDL path, wherein:

[0059] The microwave RDL path is used to transmit the radio frequency signal output by the microwave driver chip 2 to the surface microwave excitation structure 603 located in the corresponding area below the diamond sensor chip 3.

[0060] The readout RDL path is used to transmit the electrical signal output by the photodetector chip 4 to the external pin.

[0061] The vertical interconnect via 602 is used to vertically conduct electrical signals, power signals and ground lines on the RDL redistribution layer 601 to the lower interface area of ​​the packaging substrate 6.

[0062] The surface microwave excitation structure 603 is disposed on the upper surface of the packaging substrate 6 and is located below the NV working area of ​​the diamond sensor chip 3. The surface microwave excitation structure 603 is fed by a microwave RDL path and forms an alternating microwave magnetic field in its vicinity after an RF signal is applied, so as to drive the NV color center in the NV working area to resonate at ODMR.

[0063] The thermal management layer 7 is disposed below the packaging substrate 6 and is used to conduct heat generated by the chip layer during operation downwards. The thermal management layer 7 includes a heat diffusion layer and a heat dissipation base plate. The heat diffusion layer is connected to the bottom of the packaging substrate 6 and is used to diffuse heat from the microwave driver chip 2, the diamond sensor chip 3 and the photoelectric detection chip 4. The heat dissipation base plate is disposed below the heat diffusion layer and is used to further conduct heat to the external environment.

[0064] like Figure 4 As shown, a is the optical path, b is the microwave path, c is the readout electrical signal path, and d is the thermal diffusion path. The optical path includes the excitation light path of external excitation light and the fluorescence path of fluorescence. In this embodiment, the optical path, microwave path, readout electrical signal path, and thermal diffusion path are arranged in a top-bottom layered and left-right partitioned manner. The excitation light path and fluorescence path are mainly located in the corresponding area of ​​the top optical component 1, the microwave path and readout electrical signal path are mainly located in the RDL redistribution layer 601 and its related interconnection area in the packaging substrate 6, and the thermal diffusion path is mainly located in the downward thermally conductive area between the packaging substrate 6 and the thermal management layer 7.

[0065] The working principle of this invention is as follows:

[0066] Excitation light of a predetermined wavelength is perpendicularly irradiated onto the NV working area in the diamond sensor chip 3 through the excitation light input window 101 and the focusing microlens 102 to achieve optical excitation of the NV color center. The excited NV color center generates fluorescence. After being focused by the collecting lens 103, the fluorescence is filtered out by the excitation light background through the filter 104, then refracted by the 45° reflecting surface 105, and coupled to the photodetector chip 4 through the coupling lens 106.

[0067] Meanwhile, an external radio frequency signal is input to the microwave driver chip 2. After being processed by the microwave driver chip 2, it is transmitted to the surface microwave excitation structure 603 through the microwave RDL path. The surface microwave excitation structure 603 forms a local microwave near field below the diamond sensor chip 3 to drive the NV color center in the NV working area to resonate at ODMR.

[0068] After the received fluorescence signal is converted into an electrical signal, the photodetector chip 4 transmits it through the readout RDL path and outputs it to the outside of the package through the vertical interconnect via 602 and the external lead-out terminal.

[0069] The heat generated during device operation is conducted through the packaging substrate 6 to the heat diffusion layer and heat dissipation base plate, thereby achieving backside heat dissipation.

[0070] This invention achieves heterogeneous integration of the microwave driver chip 2, diamond sensor chip 3, and photodetector chip 4 on the same packaging platform by layering the chip layer, packaging substrate 6, and thermal management layer 7 formed by the top optical component 1, microwave driver chip 2, diamond sensor chip 3, and photodetector chip 4 along the packaging thickness direction. Furthermore, the top optical component 1, packaging substrate 6, and thermal management layer 7 are used to construct the optical path, electrical interconnection and microwave feeding, and thermal diffusion path, respectively, thereby forming a miniaturized, highly integrated advanced packaging heterogeneous integration structure suitable for NV color center sensors.

[0071] Based on the above heterogeneous integration structure, this embodiment also provides a method for fabricating heterogeneous integration of NV color center sensors, such as... Figures 2-3 As shown, it includes the following steps:

[0072] S1. Fabrication of the top optical component

[0073] The top optical components 1 are formed using transparent optical substrates, preferably quartz glass substrates in this embodiment. An excitation light input section and a fluorescence collection and guiding section are formed on the quartz glass substrate. Specifically, an excitation light input window 101 and a focusing microlens 102 are formed in the excitation light input section, allowing external excitation light to be coupled vertically into the NV working area of ​​the diamond sensor chip 3 via the excitation light input window 101 and the focusing microlens 102. In the fluorescence collection and guiding section, a collection lens 103, a filter 104, a 45° reflecting surface 105, and a coupling lens 106 are formed sequentially. The collection lens 103 is used to improve the fluorescence collection efficiency emitted from the NV working area, the filter 104 is used to filter out residual excitation light, the 45° reflecting surface 105 is used to change the fluorescence propagation direction, and the coupling lens 106 is used to couple the refracted fluorescence to the photodetector chip 4.

[0074] In one typical implementation, the excitation light input window 101 can be formed by photolithography and etching processes; the collecting lens 103 and the coupling lens 106 can be formed by microlens molding or micro / nano fabrication processes; the filter 104 can be formed by dielectric thin film deposition processes; and the 45° reflective surface 105 can be formed by beveling and then coating with a high-reflectivity film. After the above processes, a prefabricated top optical component 1 is obtained, such as... Figure 3 As shown in Figure a, the fabrication of the top optical component is illustrated.

[0075] S2. Fabrication of openings and vertical interconnect vias on the packaging substrate

[0076] A packaging substrate 6 is provided. In this embodiment, a high-resistivity silicon substrate is preferably used as the packaging substrate 6. The thickness of the high-resistivity silicon substrate is preferably 300-500 μm.

[0077] First, a vertical interconnect via 602 is formed in the packaging substrate 6. The vertical interconnect via 602 is used to realize the vertical conduction of subsequent electrical signals, power signals and ground lines.

[0078] As a typical implementation, deep reactive ion etching (DRIE) can be used to form vias in a high-resistivity silicon substrate, followed by the sequential formation of an insulating layer, a barrier layer, and a seed layer. A metal filling process is then used to complete the conductive filling, and finally, a planarization process is employed to ensure that the upper and lower surfaces of the packaging substrate 6 meet the requirements for subsequent redistribution and chip mounting. Figure 3 As shown in Figure b, the product structure after the vertical interconnect vias 602 are formed in the packaging substrate 6 is illustrated.

[0079] In this step, the vertical interconnect via 602 is part of the basic structure of the packaging substrate 6 and should be formed before the surface redistribution and chip mounting processes to ensure that the subsequent packaging interconnect network has complete vertical conductivity.

[0080] S3, RDL redistribution layer formation

[0081] After completing the vertical interconnect vias 602, an RDL redistribution layer 601 is formed on the upper surface of the packaging substrate 6. The RDL redistribution layer 601 is used to construct a horizontal interconnect network and provide corresponding interconnect pathways for the microwave driver chip 2, the diamond sensor chip 3, and the photodetector chip 4. As a typical implementation, a dielectric insulating layer can be formed first on the upper surface of the packaging substrate 6, followed by photolithography, electroplating, and etching processes to form a copper-based redistribution layer, and then forming pad areas suitable for subsequent micro-bump interconnection on its surface. The RDL redistribution layer 601 includes a microwave RDL path and a readout RDL path. The microwave RDL path is used to transmit the radio frequency signal output by the microwave driver chip 2 to the surface microwave excitation structure 603, and the readout RDL path is used to transmit the electrical signal output by the photodetector chip 4 to an external pin.

[0082] like Figure 3 As shown in Figure c, the product structure after an RDL redistribution layer 601 is formed on the upper surface of the packaging substrate 6 is illustrated.

[0083] It should be noted that the RDL rerouting layer 601 in this embodiment performs the function of horizontal high-density fan-out interconnection, which aims to shorten the signal path, reduce the complexity of external wiring, and provide a planar interconnection basis for subsequent multi-chip heterogeneous integration.

[0084] S4, Surface Microwave Excitation Structure Integration

[0085] A surface microwave excitation structure 603 is formed on the upper surface of the packaging substrate 6, below the NV working area corresponding to the diamond sensor chip 3. The surface microwave excitation structure 603 is fed by a microwave RDL path, and after an RF signal is applied, it can generate an alternating microwave magnetic field in its vicinity to drive the NV color center in the NV working area to undergo ODMR resonance. As a typical implementation, the surface microwave excitation structure 603 can be designed as a microstrip line structure, a coplanar waveguide structure, or a local ring microwave line structure, and formed on the upper surface of the packaging substrate 6 using a metal patterning process.

[0086] It should be noted that the surface microwave excitation structure 603 is located on the upper surface of the packaging substrate 6 and is not embedded inside the RDL redistribution layer 601. In other words, the microwave RDL path is responsible for transmitting the radio frequency signal to the target area, while the surface microwave excitation structure 603 located on the surface is the one that actually performs the local near-field microwave excitation function.

[0087] like Figure 3 As shown in Figure b, the relative positional relationship between the RDL redistribution layer 601 and the surface microwave excitation structure 603 is illustrated.

[0088] S5, Functional chip interconnect fabrication

[0089] A microwave driver chip 2, a diamond sensor chip 3, and a photodetector chip 4 are prepared, and pads and a microbump interconnect layer 5 suitable for advanced packaging interconnects are formed on their bottoms. The microwave driver chip 2 is used to receive external RF input signals and output microwave drive signals; the diamond sensor chip 3 is the core sensitive unit, and an NV color center layer and an NV working area are formed inside it; the photodetector chip 4 is used to receive guided fluorescence and output corresponding electrical signals. As a typical implementation, the microbump interconnect layer 5 can be formed using copper pillar solder bumps, tin-based solder bumps, or gold-tin microbump structures, and its size and spacing are designed according to the chip interconnect density requirements.

[0090] S6. Complete multi-chip heterogeneous integration and mounting.

[0091] The fabricated microwave driver chip 2, diamond sensor chip 3, and photodetector chip 4 are respectively aligned and mounted on predetermined areas on the upper surface of the packaging substrate 6, and electrically and mechanically connected to the RDL redistribution layer 601 through the microbump interconnect layer 5. Specifically, the microwave driver chip 2 is located in the left region of the upper surface of the packaging substrate 6, the diamond sensor chip 3 in the middle region, and the photodetector chip 4 in the right region. After mounting, the NV working area of ​​the diamond sensor chip 3 corresponds vertically to the surface microwave excitation structure 603, the microwave driver chip 2 is connected to the microwave RDL path, and the photodetector chip 4 is connected to the readout RDL path.

[0092] like Figure 3As shown in Figure c, the structural state of the three chips after heterogeneous integration with the packaging substrate 6 through the microbump interconnect layer 5 is illustrated.

[0093] In this state, the radio frequency signal output by the microwave driver chip 2 can be transmitted to the surface microwave excitation structure 603 via the microwave RDL path; the electrical signal output by the photoelectric detection chip 4 can be transmitted to the external lead-out terminal via the readout RDL path.

[0094] S7, Top optical components alignment and integration

[0095] After completing the multi-chip heterogeneous mounting, the top optical component 1 obtained in step S1 is precisely aligned and integrated with the chip layer. During alignment, the excitation light input window 101 is aligned vertically with the NV working area in the diamond sensor chip 3, and the relative positions of the fluorescence collection and light guide part with the diamond sensor chip 3 and the photodetector chip 4 are matched. After alignment, the top optical component 1 is fixed above the chip layer, thereby forming a complete top light-incident and side light-receiving structure.

[0096] In this step, the excitation light input unit is responsible for vertically introducing the excitation light of the predetermined wavelength into the NV working area; the fluorescence collection and light guiding unit is responsible for guiding the fluorescence emitted from the NV working area through the collection lens 103, the filter 104, the 45° reflective surface 105 and the coupling lens 106 in sequence into the photodetector chip 4.

[0097] S8, Formation of the thermal management layer and external interface lead-out

[0098] A thermal management layer 7 is formed beneath the packaging substrate 6. The thermal management layer 7 includes a heat diffusion layer and a heat dissipation base plate. The heat diffusion layer contacts the bottom of the packaging substrate 6 to uniformly diffuse heat from the microwave driver chip 2, the diamond sensor chip 3, and the photodetector chip 4. The heat dissipation base plate is disposed beneath the heat diffusion layer to further dissipate heat to the external environment. Simultaneously, external RF input and external electrical signal output connections are established, enabling the microwave driver chip 2 to receive external RF input signals and the photodetector chip 4 to output its output electrical signals to the outside of the package via the vertical interconnect via 602 and the external leads.

[0099] like Figure 3 As shown in Figure d, the final heterogeneous integrated package structure is shown after the integration of the top optical component 1 and the formation of the thermal management layer 7 are completed.

[0100] In summary, this embodiment first completes the prefabrication of the top optical component 1, then sequentially completes the formation of the vertical interconnect vias 602, the RDL redistribution layer 601, and the surface microwave excitation structure 603 in the packaging substrate 6. Based on this, the microwave driver chip 2, the diamond sensor chip 3, and the photodetector chip 4 are mounted on the packaging substrate 6 via the microbump interconnect layer 5. Finally, the top optical component 1 and the thermal management layer 7 are integrated, thereby obtaining a complete heterogeneous integrated structure of the NV color center sensor based on advanced packaging. This method enables the coordinated construction of optical paths, microwave paths, electrical signal paths, and thermal diffusion paths on the same packaging platform, providing a reliable process foundation for the miniaturization, high integration, and modularization of NV color center sensors.

[0101] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A heterogeneous integrated packaging structure for an NV color center sensor, characterized in that, It includes a top optical assembly (1), a microwave driver chip (2), a diamond sensor chip containing an NV color center layer (3), a photodetector chip (4), a microbump interconnect layer (5), a packaging substrate (6), and a thermal management layer (7). The lower end face of the packaging substrate (6) is mounted on the thermal management layer (7), and the upper end face is provided with an RDL redistribution layer (601) and a surface microwave excitation structure (603). The surface microwave excitation structure (603) is independent of the buried interconnect area of ​​the RDL redistribution layer (601), and a vertical interconnect via (602) is formed along the height direction of the packaging substrate (6). The upper end of the vertical interconnect via (602) is electrically connected to the RDL redistribution layer (601), and the lower end is electrically connected to the external lead-out terminal or the lower interconnect terminal on the lower surface of the packaging substrate (6). The microwave driver chip (2) and the photoelectric detection chip (4) are electrically and mechanically connected to the packaging substrate (6) through the microbump interconnect layer (5), and the diamond sensor chip (3) is connected to the packaging substrate (6) through the microbump interconnect layer (5) through at least one of the following: mechanical connection, thermal connection, or electrical connection. The RDL redistribution layer (601) includes a microwave RDL path and a readout RDL path. The surface microwave excitation structure (603) is located below the NV working area of ​​the diamond sensing chip (3) and is electrically connected to the microwave driver chip (2) through the microwave RDL path in the RDL redistribution layer (601). The photoelectric detection chip (4) is electrically connected to an external lead-out terminal through the readout RDL path in the RDL redistribution layer (601). The top optical component (1) includes an excitation light input section and a fluorescence collection and guiding section. The excitation light input section is located above the diamond sensing chip (3), and the fluorescence collection and guiding section is located above the photodetector chip (4). The excitation light input section includes an excitation light input window (101) and a focusing microlens (102). The excitation light input window (101) and the NV working area of ​​the diamond sensing chip (3) are vertically aligned. The focusing microlens (102) is located between the excitation light input window (101) and the NV working area of ​​the diamond sensing chip (3). The NV color center layer of the sensor chip (3) generates fluorescence after being excited by excitation light. The fluorescence collection and light guiding part includes a collection lens (103), a filter (104), a 45° reflective surface (105), and a coupling lens (106). The collection lens (103), the filter (104), and the 45° reflective surface (105) are arranged sequentially on the fluorescence light propagation path. The coupling lens (106) is arranged on the fluorescence propagation path after being reflected by the 45° reflective surface (105), and the light output direction or focusing area of ​​the coupling lens (106) is corresponding to the light receiving area of ​​the photodetector chip (4).

2. The heterogeneous integrated packaging structure for an NV color center sensor according to claim 1, characterized in that, The photoelectric detection chip (4) and the microwave driving chip (2) are respectively disposed on both sides of the diamond sensing chip (3), and the microwave driving chip (2), the diamond sensing chip (3) and the photoelectric detection chip (4) are arranged in parallel partitions on the packaging substrate (6).

3. The heterogeneous integrated packaging structure for an NV color center sensor according to claim 1, characterized in that, The surface microwave excitation structure (603) forms an alternating microwave magnetic field near the NV working area of ​​the diamond sensing chip (3) after a radio frequency signal is introduced.

4. The heterogeneous integrated packaging structure for an NV color center sensor according to claim 3, characterized in that, The surface microwave excitation structure (603) is a microstrip line structure, a coplanar waveguide structure, or a local ring microwave line structure.

5. The heterogeneous integrated packaging structure for an NV color center sensor according to claim 1, characterized in that, The microbump interconnect layer (5) is respectively disposed at the bottom of the microwave driver chip (2), the diamond sensor chip (3) and the photoelectric detector chip (4) and is connected to the pad area on the upper surface of the packaging substrate (6).

6. The heterogeneous integrated packaging structure for an NV color center sensor according to claim 5, characterized in that, The microbump interconnect layer (5) adopts one of the following structures: copper pillar solder bump, tin-based solder bump, or gold-tin microbump.

7. The heterogeneous integrated packaging structure for an NV color center sensor according to claim 1, characterized in that, The thermal management layer (7) includes a thermal diffusion layer and a heat dissipation base plate. The thermal diffusion layer is connected to the bottom of the packaging substrate (6), and the heat dissipation base plate is disposed below the thermal diffusion layer.

8. The heterogeneous integrated packaging structure for an NV color center sensor according to claim 1, characterized in that, The chip layer, packaging substrate (6), and thermal management layer (7) formed by the top optical component (1), microwave driving chip (2), diamond sensing chip (3), and photoelectric detection chip (4) are arranged in layers along the packaging thickness direction.

9. A method for heterogeneous integration fabrication of an NV color center sensor according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Preparation of the top optical component (1): The top optical component (1) uses a transparent optical substrate, on which an excitation light input section and a fluorescence collection and light guiding section are formed, as follows: An excitation light input window (101) and a focusing microlens (102) are formed in the excitation light input section. The excitation light input window (101) is formed by photolithography and etching processes, so that external excitation light can be coupled into the NV working area of ​​the diamond sensor chip (3) in the vertical direction through the excitation light input window (101) and the focusing microlens (102). In the fluorescence collection and light guide section, a collection lens (103), a filter (104), a 45° reflective surface (105), and a coupling lens (106) are formed in sequence. The collection lens (103) and the coupling lens (106) are formed by microlens molding or micro-nano fabrication process. The filter (104) is formed by dielectric thin film deposition process. The 45° reflective surface (105) is formed by bevel processing and then coated with a high reflective film layer. The fluorescence is focused by the collection lens (103), then filtered by the filter (104) to remove residual excitation light, then reflected by the 45° reflective surface (105) and the propagation direction is changed. Finally, it is coupled to the photodetector chip (4) by the coupling lens (106). S2, Preparation of openings and vertical interconnect vias (602) on the packaging substrate (6): First, a deep reactive ion etching process is used to open vertical interconnect vias (602) along the height direction of the packaging substrate (6). Then, an insulating layer, a barrier layer and a seed layer are formed in sequence. Subsequently, a metal filling process is used to complete the conductive filling. Finally, a planarization process is used to make the upper and lower surfaces of the packaging substrate (6) meet the requirements for redistribution and chip mounting. S3, RDL redistribution layer (601) is formed: After the vertical interconnect via (602) is fabricated, a dielectric insulating layer is first formed on the upper surface of the packaging substrate (6), and then the RDL redistribution layer (601) is formed by photolithography, electroplating and etching processes, and a pad area suitable for subsequent microbump interconnection is formed on its surface. S4, Integration of surface microwave excitation structure (603): A surface microwave excitation structure (603) is formed on the upper surface of the packaging substrate (6) below the NV working area of ​​the diamond sensor chip (3) by a metal patterning process. S5. Fabrication of functional chip interconnect terminals: Prepare a microwave driver chip (2), a diamond sensor chip (3) and a photoelectric detector chip (4) respectively, and form a pad and microbump interconnect layer (5) suitable for advanced packaging interconnection by using copper pillar solder bumps, tin-based solder bumps or gold-tin microbump structures on their bottom. S6. Complete multi-chip heterogeneous integration and mounting: The prepared microwave driver chip (2), diamond sensor chip (3) and photodetector chip (4) are respectively aligned and mounted on the predetermined area of ​​the upper surface of the packaging substrate (6), and are electrically and mechanically connected to the RDL redistribution layer (601) through the microbump interconnect layer (5). The microwave driver chip (2) is located in the left area of ​​the upper surface of the packaging substrate (6), the diamond sensor chip (3) is located in the middle area, and the photodetector chip (4) is located in the right area. The NV working area of ​​the diamond sensor chip (3) is aligned with the surface microwave excitation structure (603) in the vertical direction. The microwave driver chip (2) is connected to the microwave RDL path, and the photodetector chip (4) is connected to the readout RDL path. S7, Top optical assembly (1) alignment integration: After completing the multi-chip heterogeneous integration, the excitation light input section and the fluorescence collection and light guide section are precisely aligned and integrated with the diamond sensor chip (3) and the photodetector chip (4), respectively. During alignment, the excitation light input window (101) is aligned with the NV working area in the diamond sensor chip (3) in the vertical direction, and the relative positions of the fluorescence collection and light guide section with the diamond sensor chip (3) and the photodetector chip (4) are matched. After alignment, the excitation light input section and the fluorescence collection and light guide section are fixed above the diamond sensor chip (3) and the photodetector chip (4), thereby forming a complete top light-incident and side light-collecting structure. S8, Formation of the thermal management layer (7) and its external interface: A thermal management layer (7) is formed below the packaging substrate (6) so that the thermal diffusion layer contacts the bottom of the packaging substrate (6) and a heat dissipation base plate is disposed below the thermal diffusion layer.

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