Heterogeneous integrated device based on silicon-based 3C silicon carbide and preparation method thereof

Abstract

The invention provides a heterogeneous integrated device based on silicon-based 3C silicon carbide and a preparation method of the heterogeneous integrated device. The integrated device comprises a Si substrate, a BOX layer, a top Si layer, a 3C-SiC layer, a sensor, a GaN HEMT, a laser and an MEMS micro galvanometer. The top layer Si comprises a first top layer Si and a second top layer Si; the 3C-SiC layer comprises a first 3C-SiC layer, a second 3C-SiC layer, a third 3C-SiC layer, a fourth 3C-SiC layer and a fifth 3C-SiC layer; the sensor is arranged on the second top layer Si; the GaN HEMT is located on the third 3C-SiC layer; the laser is located on the first 3C-SiC layer; and the MEMS micro galvanometer is formed on the Si substrate. According to the invention, the 3C-SiC-on-Si substrate is used as a monolithic heterogeneous integration platform of the LiDAR, so that the miniaturization / light weight of the LiDAR device is realized.

Description

Technical Field

[0001] The present invention belongs to the field of compound semiconductor manufacturing, and in particular relates to a heterogeneous integrated device based on silicon-based 3C silicon carbide and a preparation method thereof. Background Art

[0002] The laser radar beam scanning method can be divided into mechanical scanning, hybrid solid-state scanning and all-solid-state scanning according to whether it contains mechanical components. Hybrid solid-state laser radars include microelectromechanical systems (MEMS) and prism types. MEMS laser radar uses smaller electromechanical devices instead of larger mechanical scanning devices to drive the tilt angle of the built-in reflector to change the pointing angle of the incident light beam and scan the scene with the laser beam. MEMS laser radar overcomes the shortcomings of traditional mechanical laser radar to a certain extent, and has the advantages of small size, low power consumption and easy integration.

[0003] At present, when integrating lasers, lidar manufacturers use the method of packaging the lasers independently and then coupling them to silicon photonic chips through optical fibers. This method is called "external lasers". Integrating lasers into silicon photonic chips to achieve "internal lasers" is the general trend. However, it is difficult to integrate III-V (semiconductor materials composed of group III and group V elements) with silicon heterogeneous lasers, and it is very difficult to further integrate MEMS mirrors, detectors, etc. Summary of the invention

[0004] In view of this, the present invention provides a heterogeneous integrated device based on silicon-based 3C silicon carbide and a preparation method thereof, adopts a 3C-SiC-on-Si substrate as a monolithic heterogeneous heterogeneous integration platform for LiDAR, performs heterogeneous heterogeneous integration of different materials and different devices, and realizes the miniaturization / lightweighting of the LiDAR device.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: On the one hand, the present invention provides a heterogeneous integrated device based on silicon-based 3C silicon carbide, including a Si substrate, a BOX layer, a top Si, a 3C-SiC layer, a sensor, a GaN HEMT, laser and MEMS micro-vibration mirror; the BOX layer is laid on the Si substrate, and the BOX layer includes a first BOX layer and a second BOX layer arranged at intervals; the top Si includes a first top Si and a second top Si, and the first top Si and the second top Si are laid one-to-one with the first BOX layer and the second BOX layer; the 3C-SiC layer includes a first 3C-SiC layer, a second 3C-SiC layer, a third 3C-SiC layer, a fourth 3C-SiC layer and a fifth 3C-SiC layer, the first 3C-SiC layer is laid on the first top Si, the second 3C-SiC layer and the third 3C-SiC layer are laid on the second top Si at intervals, the fourth 3C-SiC layer and the fifth 3C-SiC layer are laid on the Si substrate at intervals, and the fourth 3C-SiC layer and the fifth 3C-SiC layer are located between the first BOX layer and the second BOX layer; the sensor is arranged on the second top Si and is located between the second 3C-SiC layer and the third 3C-SiC layer; the GaN The HEMT is located on the third 3C-SiC layer; the laser is located on the first 3C-SiC layer; the MEMS micro-vibration mirror is formed on the Si substrate and is located between the fourth 3C-SiC layer and the fifth 3C-SiC layer.

[0006] Preferably, it further comprises an optical waveguide located in the BOX layer.

[0007] Preferably, the material used to make the optical waveguide is silicon or silicon nitride.

[0008] Preferably, the thickness of the BOX layer is 1-3 μm.

[0009] Preferably, the thickness of the top Si layer is 100-400 nm.

[0010] Preferably, the thickness of the 3C-SiC layer is 500 nm to 1 μm.

[0011] Preferably, the laser is a III-V Laser.

[0012] Preferably, it further comprises a controller, which is arranged on the 3C-SiC layer.

[0013] On the other hand, the present invention also provides a method for preparing the integrated device, comprising the following steps: S1, laying BOX layer and top Si layer on Si substrate in sequence; S2, laying the first 3C-SiC layer, the second 3C-SiC layer and the third 3C-SiC layer on the top Si layer, and laying the fourth 3C-SiC layer and the fifth 3C-SiC layer on the Si substrate; S3, disposing the GaN HEMT on the third 3C-SiC layer; S4, etching to form the MEMS micro-mirror on the Si substrate; S5, forming the sensor on the second top layer Si; S6. Form the laser on the first 3C-SiC layer.

[0014] Preferably, in step S2 , 3C—SiC in the 3C—SiC layer is synthesized at a temperature lower than 1400° C. and is grown directly on Si by a chemical deposition method or a physical deposition method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts 3C-SiC-on-Si substrate as a monolithic heterogeneous integration platform of LiDAR, performs heterogeneous integration of different materials and different devices, integrates the detection part of the LiDAR system: laser output part, scanning part, sensor part and other devices on a single chip, and realizes the miniaturization / lightweight of the LiDAR device. 3C-SiC belongs to the cubic crystal system like Si, and can be synthesized at a lower temperature (lower than the melting point of Si). It is the only SiC crystal form that can grow on a Si substrate and has excellent performance. Therefore, 3C-SiC / Si substrate is more suitable to replace Si substrate as a monolithic integration platform. As one of the crystal structures of the third-generation semiconductor SiC, 3C-SiC has improved mismatch problems with other compound semiconductors such as InP, GaAs, GaN, Ga2O3, etc. compared with Si, and is suitable for integrating multi-materials. 3C-SiC has high thermal conductivity. The thermal management capability of the integrated chip can be improved through the layout design of 3C-SiC. In addition, 3C-SiC can inhibit atomic diffusion and can be used to design a monolithic integrated crosstalk isolation solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a heterogeneous integrated device based on silicon-based 3C silicon carbide provided in an embodiment of the present invention; Figure 2 A schematic diagram of the preparation process of a heterogeneous integrated device based on silicon-based 3C silicon carbide provided in an embodiment of the present invention.

[0017] Figure numerals: heterogeneous integrated device based on silicon-based 3C silicon carbide 100, Si substrate 1, BOX layer 2, first BOX layer 21, second BOX layer 22, top layer Si 3, first top layer Si 31, second top layer Si 32, 3C-SiC layer 4, first 3C-SiC layer 41, second 3C-SiC layer 42, third 3C-SiC layer 43, fourth 3C-SiC layer 44, fifth 3C-SiC layer 45, sensor 5, GaN HEMT6, laser 7, MEMS micro-vibration mirror 8, optical waveguide 9. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0019] At present, when integrating lasers, lidar manufacturers use the method of packaging the lasers independently and then coupling them to silicon photonic chips through optical fibers. This method is called "external lasers". Integrating lasers into silicon photonic chips to achieve "internal lasers" is the general trend. However, it is difficult to integrate III-V (semiconductor materials composed of group III and group V elements) with silicon heterogeneous lasers, and it is very difficult to further integrate MEMS mirrors, detectors, etc.

[0020] In order to solve the above technical problems, combined Figure 1The present invention provides a heterogeneous integrated device 100 based on silicon-based 3C silicon carbide, comprising a Si substrate 1, a BOX layer 2, a top Si 3, a 3C-SiC layer 4, a sensor 5, a GaN HEMT 6, a laser 7 and a MEMS micro-vibration mirror 8; the BOX layer 2 is laid on the Si substrate 1, and the BOX layer 2 comprises a first BOX layer 21 and a second BOX layer 22 arranged at intervals; the top Si 3 comprises a first top Si 31 and a second top Si 32, and the first top Si 31 and the second top Si 32 are laid one-to-one with the first BOX layer 21 and the second BOX layer 22; the 3C-SiC layer 4 comprises a first 3C-SiC layer 41, a second 3C-SiC layer 42, a third 3C-SiC layer 43, a fourth 3C-SiC layer 44 and a fifth 3C-SiC layer 45, and the first 3C-SiC layer 41 is laid on the first top Si 31, the second 3C-SiC layer 42 and the third 3C-SiC layer 43 are alternately laid on the second top layer Si 32, the fourth 3C-SiC layer 44 and the fifth 3C-SiC layer 45 are alternately laid on the Si substrate 1, and the fourth 3C-SiC layer 44 and the fifth 3C-SiC layer 45 are located between the first BOX layer 21 and the second BOX layer 22; the sensor 5 is arranged on the second top layer Si 32 and is located between the second 3C-SiC layer 42 and the third 3C-SiC layer 43; the GaN HEMT 6 is located on the third 3C-SiC layer 43; the laser 7 is located on the first 3C-SiC layer 41; the MEMS micro-vibration mirror 8 is formed on the Si substrate 1 and is located between the fourth 3C-SiC layer 44 and the fifth 3C-SiC layer 45.

[0021] In the above technical solution, the Si substrate 1 is the basic platform of the entire device, which provides support and mechanical stability. Due to the high maturity of Si materials, mature manufacturing processes and low cost, the Si substrate 1 is often used as the basic material for integrated circuits and optoelectronic devices. In heterogeneous integration, the Si substrate 1 provides the basis for integration with other materials (such as 3C-SiC, GaN, etc.). The BOX layer 2 is located between the Si substrate 1 and the top layer Si 3, and is used as an electrical isolation layer to prevent parasitic currents and noise in the substrate from affecting the performance of the upper layer device. The BOX layer 2 is usually composed of silicon dioxide (SiO2) and has good electrical insulation. It is very important in the silicon-on-insulator (SOI) structure, which can enhance the performance of the device, reduce parasitic effects, and provide thermal isolation. The top layer Si 3 is located above the BOX layer 2 and is one of the main functional layers of the entire device. The top layer Si 3 is usually used to manufacture devices such as integrated circuits and sensors 5. It provides a silicon platform for integrated circuits (ICs), and is usually used to prepare functions such as logic circuits, signal processing circuits, and sensor arrays. The top layer Si 3 also provides integration support for other semiconductor materials (such as 3C-SiC, GaN, etc.). 3C-SiC is a silicon carbide material with high thermal conductivity, wide bandgap, and excellent electronic and optical properties. The 3C-SiC layer 4 is generally used to manufacture devices that work in high-frequency, high-power and high-temperature environments, such as high-efficiency sensors, optoelectronic devices and power devices. In this heterogeneous integrated device, the 3C-SiC layer 4 is used to integrate optoelectronic devices (such as lasers) or power devices (such as high-power sensors and amplifiers). The sensor 5 can use the electrical, optical or mechanical properties of silicon, 3C-SiC or other materials to sense changes in the external environment. The role of the sensor 5 in this integrated device is to detect temperature, pressure, light intensity or other physical quantities, and convert these signals into electrical signals. For example, the 3C-SiC-based sensor 5 may be used for detection in high-temperature, high-pressure or high-power environments, and is suitable for application scenarios that require high-temperature resistance and high-pressure resistance. The GaN HEMT 6 is a high electron mobility transistor that is widely used in high-frequency, high-power and high-efficiency applications. GaN has a wide bandgap and high electron mobility, and is suitable for use in power amplifiers, radio frequency (RF) amplifiers, etc. The GaN HEMT 6 is generally used in high-speed signal processing, power conversion, and radio frequency communications. In this integrated device, the GaN HEMT 6 may be used for power amplification, high-speed signal amplification, and radio frequency processing. The MEMS micro-vibration mirror 8 is a micro-electromechanical system (MEMS) device used to accurately control the reflection angle of a light beam. The MEMS micro-vibration mirror 8 uses a tiny mechanical structure to achieve fine-tuning of the mirror at the micron or nanometer level, which is used for scanning, positioning, or imaging of laser beams. They are widely used in laser scanning systems, optical communications, LiDAR, and other fields.In such a heterogeneous integrated device, the MEMS micro-vibration mirror 8 may be used for beam control in a laser 7 or sensor 5 system to ensure that the optical signal can be accurately directed.

[0022] The present invention adopts 3C-SiC-on-Si substrate as a monolithic heterogeneous integration platform of LiDAR, performs heterogeneous integration of different materials and different devices, integrates the detection part of LiDAR system: laser output part, scanning part, sensor part and control part and other devices on a single chip, and realizes miniaturization / lightweight of LiDAR device. As one of the crystal structures of the third generation semiconductor SiC, 3C-SiC has improved mismatch problems with other compound semiconductors such as InP, GaAs, GaN, Ga2O3, etc. compared with Si, and is suitable for integrating multi-materials. 3C-SiC has high thermal conductivity, and the thermal management capability of the integrated chip can be improved by the layout design of 3C-SiC. In addition, 3C-SiC can inhibit atomic diffusion, and 3C-SiC can be used to design a monolithic integrated crosstalk isolation solution.

[0023] It is particularly important to note that the 3C-SiC-on-Si substrate combines the advantages of large size and low cost of Si and the advantages of wide bandgap semiconductor 3C-SiC. 3C-SiC can be used as a functional layer of some devices, such as the thin film layer of the MEMS micro-mirror 8; it can also be used as a buffer layer for epitaxial growth of other materials, such as III-V group material GaN, to improve the stress and crystal quality of GaN epitaxial materials on Si; it can also be used as a bonding layer to improve the bonding strength between Si and other materials or devices.

[0024] Furthermore, it also includes an optical waveguide 9, which is located in the BOX layer 2. The optical waveguide 9 is arranged in the BOX layer 2, which helps to improve effective optical signal transmission, improve integration, reduce power consumption, reduce parasitic effects, increase bandwidth, improve compatibility and scalability, and is suitable for high-temperature decomposition and high-power applications, and is used for low-loss optical connections. In some embodiments, the material for making the optical waveguide 9 is silicon or silicon nitride.

[0025] Furthermore, the thickness of the BOX layer 2 is 1-3 μm, which provides a good balance for integrated circuits and optoelectronic devices, and can not only meet the requirements of electrical isolation, thermal management and signal transmission, but also simplify the manufacturing process and improve the comprehensive performance of the device.

[0026] Furthermore, the thickness of the top layer Si 3 is 100~400nm, which can optimize the electrical performance, optoelectronic performance, thermal management and reliability of the integrated circuit, adapt to a variety of high-performance applications, and is compatible with existing integrated manufacturing processes, providing a balanced design solution.

[0027] Furthermore, the thickness of the 3C-SiC layer 4 is 500nm~1μm. The 3C-SiC layer 4 of this thickness provides an ideal balance in a variety of high-performance applications. Combining its thermal, electrical, mechanical, optoelectronic and other characteristics, it can significantly improve the performance and reliability of the device. In some embodiments, the laser 7 is a III-V Laser. In some embodiments, a controller is also included, which is arranged on the 3C-SiC layer 4.

[0028] Combination Figure 2 The present invention also provides a method for preparing the integrated device, comprising the following steps: S1, sequentially laying BOX layer 2 and top Si layer 3 on Si substrate 1; Specifically, a Si wafer including a buried oxide layer is taken, wherein the Si wafer includes the Si substrate 1, a buried oxide (SiO2) of 1 to 3 μm, the BOX layer 2, and the top Si 3 of 100 to 400 nm. The BOX layer 2 includes the first BOX layer 21 and the second BOX layer 22 arranged at intervals; the top Si 3 includes a first top Si 31 and a second top Si 32, and the first top Si 31 and the second top Si 32 are laid one-to-one in correspondence with the first BOX layer 21 and the second BOX layer 22. The top Si 3 is locally etched with different depths, and processes such as insulating layer deposition and planarization are performed to form a plurality of silicon waveguide structures with different etching depths; the upper part of the Si wafer is etched with different depths to form a device preparation window, a groove for placing a light source chip, etc.

[0029] S2, laying the first 3C-SiC layer 41, the second 3C-SiC layer 42 and the third 3C-SiC layer 43 on the top Si 3, and laying the fourth 3C-SiC layer 44 and the fifth 3C-SiC layer 45 on the Si substrate 1; Specifically, a layer of 3C-SiC with a thickness of 500nm~1μm is selectively deposited on a Si wafer by chemical or physical growth methods. As a subsequent integrated substrate, 3C-SiC can be used as an intermediate bonding layer for Si to bond other materials, a buffer layer for epitaxial III-V materials on Si, and a functional layer for power and MEMS devices. 3C-SiC can be synthesized at a relatively low temperature (below 1300°C) and belongs to the same cubic system as Si. Therefore, 3C-SiC can be grown on a Si substrate with better performance. 3C-SiC-on-Si is feasible as a heterogeneous integration platform.

[0030] S3, disposing the GaN HEMT 6 on the third 3C-SiC layer 43; Specifically, a GaN / AlGaN heterojunction is locally epitaxially grown on 3C-SiC and a GaN-based HEMT device is prepared to form a GaN HEMT 6 that can be turned on / off at high speed to drive the LiDAR laser diode. The lattice mismatch and thermal expansion coefficient mismatch between SiC and GaN are low, and the introduction of 3C-SiC can improve the stress and crystal quality of GaN materials grown directly on Si. At the same time, the 3C-SiC interlayer can inhibit the diffusion of gallium and / or aluminum atoms of group III nitrides into the substrate and the diffusion of Si atoms of the substrate into the GaN buffer layer. Therefore, 3C-SiC can effectively reduce the RF loss of GaN-based HEMTs and improve the crosstalk isolation capability between devices.

[0031] S4, etching to form the MEMS micro-mirror 8 on the Si substrate 1; Specifically, thin film deposition, patterning etching, coating, Si back etching and other processes are performed on Si and 3C-SiC in some areas to form the MEMS micro-vibration mirror 8, which serves as a scanning component of LiDAR to expand the scanning area of ​​the laser or change the scanning direction. 3C-SiC has good electrochemical and mechanical stability, high hardness and elastic modulus, high conductivity, and diverse surface chemical properties. 3C-SiC thin film is suitable for the functional layer of MEMS devices.

[0032] S5, forming the sensor 5 on the second top layer Si 32; Specifically, ion implantation, thermal oxidation, dry and wet etching, Ge selective epitaxy, annealing, electrode preparation and other processes are performed on the Si in some areas to prepare germanium PN diodes or PiN diodes or photosensitive device arrays to form Ge photodetectors, which serve as the sensor 5 of LiDAR to sense the laser reflected by the object located in the scanning area. The annealing process can adopt a laser annealing process, and the thermal isolation formed by local laser irradiation and 3C-SiC layout can effectively avoid the influence of high temperature annealing of Ge material on other materials and devices.

[0033] S6 . Form the laser 7 on the first 3C—SiC layer 41 .

[0034] Specifically, the laser chip is bonded to the above-mentioned groove in a coupon to wafer manner, and the position and direction of the laser 7 are precisely matched with the silicon waveguide. The laser chip can be a III-V InP, GaAs infrared laser (LD), VCSEL (vertical cavity surface emitting laser), GaSb infrared light source chip, etc. The laser chip is prepared on a separate III-V epitaxial wafer through quantum well growth, etching, coating and other processes, and then the wafer is thinned and cut into small pieces, and then the coupon containing the laser is integrated into the 3C-SiC / Si substrate. 3C-SiC, as an intermediate bonding layer, can improve the bonding strength between Si and other materials or devices. 3C-SiC has high thermal conductivity, which can improve the heat dissipation performance of the laser 7, or use the layout of 3C-SiC for thermal isolation.

[0035] In some embodiments, the controller is integrated on the 3C-SiC / Si substrate, which can be achieved by bonding the control hardware DSP (digital signal processor) on the substrate, or by preparing a CMOS control circuit on Si or 3C-SiC or GaN, and then preparing a DSP. Finally, after completing the window filling and flattening process, the multi-layer metal layer of the chip is interconnected to complete the LiDAR based on the 3C-SiC / Si substrate.

[0036] Of course, in some embodiments, 3C-SiC can be grown on a Si substrate first, and then a thin film can be etched to make Si devices, and then subsequent processes can be performed. The order of the processes of each device is not fixed, and depends on the complexity of the process and the compatibility between processes, as well as the impact of the subsequent process on the current device.

[0037] The specific raw materials not described in the present invention are all existing materials and can be directly purchased from the market.

[0038] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A heterogeneous integrated device based on silicon-based 3C silicon carbide, characterized in that: include Si substrate; A BOX layer is laid on the Si substrate, and the BOX layer includes a first BOX layer and a second BOX layer that are spaced apart; A top Si layer, including a first top Si layer and a second top Si layer, wherein the first top Si layer and the second top Si layer are laid in one-to-one correspondence with the first BOX layer and the second BOX layer; 3C-SiC layer, including a first 3C-SiC layer, a second 3C-SiC layer, a third 3C-SiC layer, a fourth 3C-SiC layer and a fifth 3C-SiC layer, wherein the first 3C-SiC layer is laid on the first top Si layer, the second 3C-SiC layer and the third 3C-SiC layer are alternately laid on the second top Si layer, the fourth 3C-SiC layer and the fifth 3C-SiC layer are alternately laid on the Si substrate, and the fourth 3C-SiC layer and the fifth 3C-SiC layer are located between the first BOX layer and the second BOX layer; A sensor, disposed on the second top Si layer and located between the second 3C-SiC layer and the third 3C-SiC layer; A GaN HEMT located on the third 3C-SiC layer; A laser, located on the first 3C-SiC layer; The MEMS micro-vibration mirror is formed on the Si substrate and is located between the fourth 3C-SiC layer and the fifth 3C-SiC layer.

2. The integrated device according to claim 1, characterized in that: Also included is an optical waveguide located in the BOX layer.

3. The integrated device according to claim 2, characterized in that: The material used to prepare the optical waveguide is silicon or silicon nitride.

4. The integrated device according to claim 1, characterized in that: The thickness of the BOX layer is 1-3 μm.

5. The integrated device according to claim 1, characterized in that: The thickness of the top Si layer is 100-400 nm.

6. The integrated device according to claim 1, characterized in that: The thickness of the 3C-SiC layer is 500nm~1μm.

7. The integrated device according to claim 1, characterized in that: The laser is a III-V Laser.

8. The integrated device according to claim 1, characterized in that: The invention also includes a controller which is arranged on the 3C-SiC layer.

9. The method for preparing an integrated device according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, laying BOX layer and top Si layer on Si substrate in sequence; S2, laying the first 3C-SiC layer, the second 3C-SiC layer and the third 3C-SiC layer on the top Si layer, and laying the fourth 3C-SiC layer and the fifth 3C-SiC layer on the Si substrate; S3, disposing the GaN HEMT on the third 3C-SiC layer; S4, etching to form the MEMS micro-mirror on the Si substrate; S5, forming the sensor on the second top layer Si; S6. Form the laser on the first 3C-SiC layer.

10. The preparation method according to claim 9, characterized in that: In step S2 , 3C—SiC in the 3C—SiC layer is grown directly on Si by a chemical deposition method or a physical deposition method.

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