SiC-based GaN high-power on-chip longitudinal microfluidic device and preparation method and application thereof
By designing longitudinal microflowers and dorsal holes in SiC-based GaN high-power in-chip, the thermal accumulation effect and reliability problems of GaN devices are solved, and higher performance and reliability are achieved, suitable for high-power microwave device applications.
Patent Information
- Application Number
- CN202411848931.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-16
- Publication Date
- 2025-03-28
AI Technical Summary
The thermal accumulation effect of GaN devices in high power and high frequency applications leads to increased device junction temperature, which in turn affects material and electrical characteristics, and thermal stress may cause damage to the metal wires of the device to the external electrodes, resulting in performance and lifetime attenuation.
A SiC-based GaN high-power on-chip longitudinal microfluidic device is designed, and the heat dissipation ability and reliability of the device are improved by providing longitudinal microfluidic channels and co-designed background holes on the SiC substrate.
It effectively solves the heat dissipation and reliability problems of GaN devices, improves the performance and reliability of the devices, and is suitable for high-power microwave devices such as radar detection and other fields.
Smart Images
Figure CN119725274A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of GaN devices, and in particular relates to a SiC-based GaN high-power on-chip longitudinal microfluidic device and a preparation method and application thereof. Background Art
[0002] As a representative of the new generation of solid-state microwave power devices, gallium nitride (GaN) semiconductors feature high two-dimensional electron gas concentration, high breakdown field strength, and high electron saturation velocity. They hold promising application prospects in high-temperature, high-power devices, high-frequency microwave power devices, and optoelectronic devices. In particular, in the field of microwave high-power devices, they offer significant performance advantages over first- and second-generation semiconductor materials. Their output power density can be several or even dozens of times greater than that of GaAs microwave power FETs, meeting the requirements of the new generation of electronic products for higher power, higher frequency, and smaller microwave power devices. They are widely used in military and civilian applications such as radar systems and communications systems.
[0003] The development of high-power, high-integration GaN devices is hampered by the problem of increased junction temperature caused by heat accumulation, which reduces the mobility of electrons in the active region and, in turn, affects the device's material and electrical properties. As device power density continues to increase, the self-heating effect of GaN devices not only accelerates device degradation but also creates thermal stress that can easily damage and fracture the metal connections between the device and external electrodes. This severely degrades device performance and lifespan, preventing the high-power performance advantages of GaN devices from being fully realized. Summary of the Invention
[0004] In response to the shortcomings of the existing technology, the present invention provides a SiC-based GaN high-power on-chip longitudinal microfluidic device, its preparation method and application. By covering the longitudinal on-chip microchannels in the active area and the co-designed back-ground holes, the heat dissipation and device reliability problems of high-power GaN devices are effectively solved, thereby improving the device performance and reliability.
[0005] The present invention is achieved through the following technical solutions:
[0006] A SiC-based GaN high-power on-chip longitudinal microfluidic device comprises, from bottom to top, a SiN passivation layer, an AlGaN barrier layer, a GaN buffer layer, and a SiC substrate. An active region is embedded in the SiN passivation layer, and the active region comprises source, drain, and gate functional layers. A microfluidic structure is provided on the SiC substrate, comprising a fixed groove and a plurality of microchannels arranged parallel to the fixed groove. The fixed groove is a recessed structure that penetrates the SiC substrate and extends into the GaN buffer layer. The direction of the microchannels is parallel to the gate length direction of the active region.
[0007] Preferably, the area of the microfluidic structure covers the entire active area.
[0008] Preferably, a row of source back holes is provided at the bottom of the SiC substrate, and the source back holes penetrate the entire device and are located on one side of the long side of the microfluidic structure.
[0009] Preferably, the diameter of the source back hole is 75 μm.
[0010] Preferably, the SiC-based GaN high-power on-chip longitudinal microfluidic device has a length of 6800 μm and a width of 3800 μm.
[0011] Preferably, the fixing groove has a length of 4200 μm and a width of 1600 μm.
[0012] Preferably, the length of the microchannel is 800 μm, and the width is 225 μm or 337.5 μm; the distance between two adjacent microchannels is 150 μm.
[0013] Preferably, the thickness of the AlGaN barrier layer is 20-25 nm, the thickness of the GaN buffer layer is 1.5-2 μm, and the thickness of the SiC substrate layer is 130 μm.
[0014] The method for preparing the SiC-based GaN high-power on-chip longitudinal microfluidic device comprises the following steps:
[0015] Step 1) Isolating the active area of the device based on conventional technology;
[0016] Step 2) preparing the source and drain functional areas using a conventional evaporation process;
[0017] Step 3) using a conventional CVD process to perform a SiN passivation process;
[0018] Step 4) using evaporation technology to grow and prepare the gate functional area;
[0019] Step 5) coating the front of the device with paraffin for protection and thinning the SiC substrate on the back of the device;
[0020] Step 6) Use multi-step etching technology and electroplating technology to prepare microchannels and source back holes on the SiC substrate. First, the SiC substrate source back hole is etched, and then the GaN layer is etched to complete the penetration of the back hole. Then, the through hole is filled by electroplating copper. Next, the microchannel is etched. Finally, the back of the device is subjected to full-sheet seed layer metal WTi / Au / Ti evaporation and Ni / Au metal electroplating to complete the overall back gold on the back of the device.
[0021] Application of the above-mentioned SiC-based GaN high-power on-chip longitudinal microfluidic device, or the SiC-based GaN high-power on-chip longitudinal microfluidic device prepared by the above-mentioned preparation method in the field of radar detection.
[0022] The beneficial effects of the present invention are as follows:
[0023] In the SiC-based GaN high-power on-chip longitudinal microfluidic device of the present invention, the SiC substrate contains a heat dissipation microfluidic structure that is in direct contact with the GaN buffer layer. Simultaneously, the design of multiple sets of longitudinal microchannels increases the heat exchange area between the cooling medium and the device, improving the heat dissipation capacity of the near-junction region within the chip and further enhancing the heat dissipation capacity of the GaN high-power device. A row of source back-ground holes is designed next to the microchannels to replace gold wires to complete the grounding of the device source, avoiding the need for some bonding wire connections on the front of the device and effectively improving the reliability of the GaN high-power device. The SiC-based GaN high-power on-chip longitudinal microfluidic device of the present invention has the advantages of efficient heat dissipation and high reliability, and can be used in high-power microwave devices such as radar detection, especially phased array radar, electronic countermeasures, and missile-borne applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 Schematic diagram of the cross-sectional structure of a high-power GaN on-chip longitudinal microfluidic device on SiC;
[0025] Figure 2 Schematic diagram of the backside structure of the SiC-based GaN high-power on-chip longitudinal microfluidic device;
[0026] Figure 3 Backside microscope image of a high-power GaN on-chip vertical microfluidic device on SiC;
[0027] Figure 4 Schematic diagram of the dimensions of the SiC-based GaN high-power on-chip longitudinal microfluidic device in Example 1: A is the SiC substrate, B is the microfluidic structure;
[0028] In the figure: 1. Source; 2. Drain; 3. Gate; 4. SiN passivation layer; 5. AlGaN barrier layer; 6. GaN buffer layer; 7. SiC substrate; 8. Microfluidic structure; 9. Fixed groove; 10. Microchannel; 11. Source back ground hole. DETAILED DESCRIPTION
[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0030] Example 1
[0031] A SiC-based GaN high-power on-chip longitudinal microfluidic device, such as Figure 1-3As shown, from bottom to top, it includes a SiN passivation layer 4, an AlGaN barrier layer 5, a GaN buffer layer 6, and a SiC substrate 7. The SiN passivation layer 4 is embedded with an active region, which comprises the source 1, drain 2, and gate 3 functional layers. A microfluidic structure 8 is provided on the SiC substrate 7. The microfluidic structure 8 includes a fixed groove 9 and several microchannels 10 arranged parallel to the fixed groove 9. The fixed groove 9 is a recessed structure that extends through the SiC substrate 7 and into the GaN buffer layer 6. The direction of the microchannels 10 is parallel to the length of the gate 3 in the active region. The area of the microfluidic structure 8 covers the entire active region.
[0032] like Figure 2 、 3 As shown, a row of back-source holes 11 is provided at the bottom of the SiC substrate 7. These holes extend through the entire device and are located on one side of the long side of the microfluidic structure 8. The microfluidic structure 8 is in direct contact with the GaN buffer layer 6. Multiple groups of longitudinal microchannels 10 increase the heat exchange area. Furthermore, a row of back-source holes 11 adjacent to the microchannels 10 extends through the SiC substrate 7, enhancing the reliability of the high-power device.
[0033] A preferred solution, such as Figure 4 As shown in A and B, the length of the device in this embodiment is 6800 μm and the width is 3800 μm; the length of the fixed groove 9 is 4200 μm and the width is 1600 μm; the length of the microchannel 10 is 800 μm and the width is 225 μm (middle area) or 337.5 μm (side areas); the distance between two adjacent microchannels 10 is 150 μm.
[0034] In a preferred solution, the diameter of the source back hole 11 is 75 μm, the thickness of the AlGaN barrier layer 5 is 20-25 nm, the thickness of the GaN buffer layer 6 is 1.5-2 μm, and the thickness of the SiC substrate layer 7 is 130 μm.
[0035] The method for preparing the SiC-based GaN high-power on-chip longitudinal microfluidic device comprises the following specific steps:
[0036] (1) Based on the traditional process, the active area of the device is first isolated.
[0037] (2) The source and drain functional areas are prepared using traditional evaporation technology.
[0038] (3) Use traditional CVD process for SiN passivation process.
[0039] (4) Evaporation technology is used to grow and prepare the gate functional area.
[0040] (5) The front of the device is protected by paraffin coating and the SiC substrate on the back of the device is thinned.
[0041] (6) Multi-step etching technology and electroplating technology are used to prepare microchannels and source back holes on the SiC substrate. First, the SiC substrate source back hole is etched, and then the GaN layer is etched to complete the penetration of the back hole. Then, the through hole is filled by electroplating copper. Next, the microchannel is etched, and finally, the seed layer metal WTi / Au / Ti is evaporated and Ni / Au metal is electroplated on the back of the device to complete the overall back gold on the back of the device. At the same time, the metal can effectively protect the channel and delay the channel from being corroded by the heat dissipation medium (water, alcohol, etc.). The specific process is as follows:
[0042] (6-1) Etching of back hole:
[0043] (a) Back hole area photolithography: including spin coating of photoresist, pre-bake, exposure, development, hardening and other processes to pattern the back hole area on the surface of SiC substrate;
[0044] (b) Seed layer sputtering: sputtering WTi / Au seed layer metal, stripping with acetone, and ultrasonic cleaning with acetone and ethanol respectively;
[0045] (c) Mask layer electroplating: Spin-coat multiple layers of AZ701 photoresist to a thickness greater than 6 μm, and complete pre-baking, exposure, development, and hardening processes. Electroplating thick Ni is performed on the Au layer to a thickness greater than 12 μm to meet the etching mask requirements.
[0046] (d) RIE etching: The SiC substrate is deep-etched using a SF6 / O2 gas atmosphere using RIE technology. The etching depth penetrates the entire SiC substrate, and the remaining metal Ni is removed by wet etching after etching.
[0047] (e) ICP etching: The back of the device is evenly sprayed with a photoresist 7908 having a thickness of 1.0 μm. The process steps of pre-baking, exposure, development, and hardening are completed. The photoresist 7908 is used as a mask. The GaN buffer layer is etched using ICP technology using BCl3 / Cl2 to the back of the source metal. After etching, the photoresist is removed to complete the back hole penetration.
[0048] (f) Backside hole electroplating filling: The backside of the device is evenly sprayed with a 1.0 μm thick photoresist 7908. The pre-baking, exposure, development, and hardening steps are completed. The photoresist 7908 is used as a mask to sputter the WTi / Au seed layer. After sputtering, the resist is removed and the backside holes are electroplated with copper.
[0049] (6-2) Etching of microchannels:
[0050] (g) Microfluidic area lithography: including spraying photoresist, pre-baking, exposure, development, hardening and other processes to pattern the back hole area on the surface of the SiC substrate;
[0051] (h) Seed layer sputtering: sputtering WTi / Au seed layer metal, stripping with acetone, and ultrasonic cleaning with acetone and ethanol respectively;
[0052] (i) Mask layer electroplating: Spin-coat multiple layers of AZ701 photoresist to a thickness greater than 6 μm, and complete pre-baking, exposure, development, and hardening processes. Electroplating thick Ni is applied to the Au layer to a thickness greater than 12 μm to meet the etching mask requirements.
[0053] (j) RIE etching: The SiC substrate is deep-etched using a SF6 / O2 gas atmosphere using RIE technology. The etching depth penetrates the entire SiC substrate, and the remaining metal Ni is removed by wet etching after etching.
[0054] (k) The entire back surface is sputtered with a WTi / Au seed layer metal, and then Ni / Au (1.6 μm / 3 μm) metal is electroplated. The paraffin wax protecting the front surface is wet cleaned to complete the preparation of the SiC-based GaN high-power on-chip longitudinal microfluidic device.
[0055] The implementation principle of the present invention: The present invention designs a longitudinal microchannel and a source backhole on the SiC substrate, introduces a multi-step etching technology to etch the SiC substrate backhole after photolithography, and then evenly coats the entire sheet with photoresist by spraying after etching to a certain depth, completing the evaporation of the seed layer metal (WTi / Au / Ti) and the electroplating of Ni metal. The metal Ni is used as a mask layer to simultaneously etch the backhole and the microchannel. Since there is less Ni metal in the backhole, the backhole etching depth will be greater than the microchannel depth. In this way, the backhole is connected to the source while the microchannel depth is in the GaN buffer layer in the device structure. In terms of the preparation process, the source backhole and the microchannel are compatible and prepared simultaneously. This structure can improve the heat dissipation capacity inside the GaN high-power device chip while taking into account the improvement of reliability, solving its heat accumulation problem.
[0056] Test Example 1
[0057] A device without a passive back-hole design (control device 1, i.e., no back-holes were etched, and other structures were the same as those of this embodiment) and a conventional sample without a microfluidic channel (control device 2, i.e., no microfluidic structure, and other structures were the same as those of this embodiment) were used as controls for testing. The test process is as follows:
[0058] (1) Sample assembly: The device of this embodiment, control device 1, and control device 2 are integrated with a test housing (the test housing of the sample with microfluidic channels contains a liquid channel, which is connected to an external pump area to provide microfluidic heat dissipation for the microfluidic device).
[0059] (2) Test system setup and connection: Connect the solid-state amplifier, vector network, power meter, and power supply in sequence to complete the test system connection.
[0060] (3) Place the device integrated with the test housing under the infrared thermal imager, connect the input and output terminals to the test system, and complete the calibration of the infrared thermal imager.
[0061] (4) Power-on test: Adjust the gate voltage to turn on the device, increase the drain voltage to 36V, adjust the input signal, and record the device drain voltage, leakage current, output power, and junction temperature.
[0062] The test results are shown in Table 1 below:
[0063] Table 1 Test results
[0064] Group Leakage voltage (V) Output power (W) Junction temperature (℃) The device of this embodiment 36 158 160 Control device 1 36 89 160 Control device 2 36 60 160
[0065] As can be seen from Table 1, the SiC-based GaN high-power on-chip longitudinal microfluidic device of this embodiment is achieved through the coordinated design and process compatibility of the source back ground hole and the longitudinal microchannel. Under the same junction temperature, the output power is increased from 89 W to 158 W compared with the control device 1. The output power of the conventional sample without microchannel design (control device 2) is only 60 W, which is lower than the control device 1 and far lower than the microfluidic device of this embodiment.
[0066] The embodiments described above are only some of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but merely represents selected embodiments of the present invention. The scope of protection of the present invention shall be based on the scope required by the claims. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative efforts shall fall within the scope of protection of the present invention.
Claims
1. A SiC-based GaN high-power on-chip longitudinal microfluidic device, characterized in that: The device comprises, from bottom to top, a SiN passivation layer, an AlGaN barrier layer, a GaN buffer layer and a SiC substrate; an active region is embedded in the SiN passivation layer, and the active region is a source, drain and gate functional layer; a microfluidic structure is provided on the SiC substrate, and the microfluidic structure comprises a fixed groove and a plurality of microchannels arranged in parallel in the fixed groove, and the fixed groove is a recessed structure penetrating the SiC substrate to the GaN buffer layer, and the direction of the microchannel is parallel to the gate length direction of the active region.
2. A SiC-based GaN high-power on-chip vertical microfluidic device according to claim 1, characterized in that: The area of the microfluidic structure covers the entire active area.
3. The SiC-based GaN high-power on-chip vertical microfluidic device according to claim 1, characterized in that: A row of source back holes is arranged at the bottom of the SiC substrate, and the source back holes penetrate the entire device and are located on one side of the long side of the microfluidic structure.
4. A SiC-based GaN high-power on-chip vertical microfluidic device according to claim 3, characterized in that: The diameter of the source back ground hole is 75 μm.
5. The SiC-based GaN high-power on-chip vertical microfluidic device according to claim 1, characterized in that: The SiC-based GaN high-power on-chip longitudinal microfluidic device has a length of 6800 μm and a width of 3800 μm.
6. The SiC-based GaN high-power on-chip vertical microfluidic device according to claim 5, characterized in that: The fixing groove has a length of 4200 μm and a width of 1600 μm.
7. A SiC-based GaN high-power on-chip vertical microfluidic device according to claim 6, characterized in that: The length of the microchannel is 800 μm, and the width is 225 μm or 337.5 μm; the distance between two adjacent microchannels is 150 μm.
8. The SiC-based GaN high-power on-chip vertical microfluidic device according to claim 1, characterized in that: The thickness of the AlGaN barrier layer is 20-25 nm, the thickness of the GaN buffer layer is 1.5-2 μm, and the thickness of the SiC substrate layer is 130 μm.
9. A method for preparing a SiC-based GaN high-power on-chip longitudinal microfluidic device according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1) Isolating the active area of the device based on the traditional process; Step 2) preparing source and drain functional areas by conventional evaporation process; Step 3) using a conventional CVD process to perform a SiN passivation process; Step 4) using evaporation technology to grow and prepare the gate functional area; Step 5) coating the front of the device with paraffin for protection, and thinning the SiC substrate on the back of the device; Step 6) Use multi-step etching technology and electroplating technology to prepare microchannels and source back holes on the SiC substrate. First, the SiC substrate source back hole is etched, and then the GaN layer is etched to complete the penetration of the back hole. Then, the through hole is filled by electroplating copper, and then the microchannel is etched. Finally, the seed layer metal WTi / Au / Ti is evaporated and Ni / Au metal is electroplated on the back of the device to complete the overall back gold on the back of the device.
10. Application of the SiC-based GaN high-power on-chip longitudinal microfluidic device according to any one of claims 1 to 8, or the SiC-based GaN high-power on-chip longitudinal microfluidic device prepared by the preparation method according to claim 9 in the field of radar detection.