An embedded on-chip micro-channel Si-based GaN HEMT device and its preparation method

Abstract

The present invention relates to an embedded on-chip microchannel Si-based GaN HEMT device and a preparation method thereof, and belongs to the field of thermal management technology of new semiconductor devices. The device includes a gate functional layer, a source functional layer, a drain functional layer, a SiN passivation layer, an AlGaN barrier layer, a GaN buffer layer and a microfluidic structure Si substrate from top to bottom; the microfluidic structure Si substrate includes a manifold heat dissipation microfluidic structure, which is divided into a microfluidic structure heat transfer area and a drainage structure area. The microfluidic structure heat transfer area is in direct contact with the GaN buffer layer, and the microchannels of the drainage structure area are perpendicular to and interconnected with the microchannels of the microfluidic structure heat transfer area to form a manifold microfluidic heat dissipation structure. The embedded on-chip microchannel Si-based GaN HEMT device of the present invention has the advantage of efficient heat dissipation capability and can be used for ultra-high power microwave power devices.

Description

Technical Field

[0001] The invention relates to an embedded on-chip microchannel Si-based GaN HEMT device and a preparation method thereof, belonging to the technical field of thermal management of novel semiconductor devices. Technical Background

[0002] The new third-generation semiconductor materials represented by GaN have unique advantages such as wide bandgap, high breakdown field strength, high electron saturation velocity, and resistance to high voltage and high temperature. The characteristics in all aspects are far higher than those of the first and second generation semiconductor materials represented by GaAs and Si. They are extremely suitable for high-power and high-frequency devices. They have attracted widespread attention in the military fields represented by radar and electronic countermeasures and the civilian fields represented by 5G base stations and fast charging. AlGaN / GaN high electron mobility transistors (HEMT) are currently developing towards a smaller size and higher power mode. However, with the reduction in size and the further increase in power density, the heat accumulation effect of GaN devices has increased significantly, resulting in a sharp deterioration in the electrical performance of GaN devices. Limited by the thermal properties of GaN devices and the heat dissipation structure, the power density of GaN devices currently used in product work is generally 3-5w / mm, which is far from the power density verified in experimental research. The heat accumulation problem has become one of the main technical bottlenecks restricting the application and development of GaN devices at this stage, resulting in the increase in power density and limited device reliability. Therefore, it is urgent to improve the heat dissipation capacity of GaN devices. At present, the chip-level heat dissipation of GaN devices is mainly divided into two types: passive heat dissipation technology and active heat dissipation technology. Passive heat dissipation technology is to integrate high thermal conductivity materials with the heat source area inside the chip to increase the heat transfer capacity inside the chip and effectively inhibit heat accumulation, such as diamond substrate GaN technology, diamond embedded heat dissipation column technology and high thermal conductivity passivation layer heat dissipation technology; active heat dissipation technology is to introduce liquid into the vicinity of the heat source area inside the chip, exchange heat to the liquid, and effectively take away the heat from the heat source area, such as on-chip microfluidic cooling and heat dissipation technology, which is further divided into on-chip microfluidic heat dissipation technology based on SiC substrate, on-chip microfluidic heat dissipation technology based on diamond substrate and on-chip microfluidic heat dissipation technology based on heat dissipation column. However, the existing technology, even the on-chip microfluidic technology with better effect, its microchannel is realized by back etching. Due to the limited thickness of the material itself and the etching depth ratio, the microchannel is still a certain distance away from the heat source, so it is still limited by the thermal conductivity of the substrate material itself to a certain extent. Therefore, a structure and process design scheme in which the microchannel directly contacts the heat source and can efficiently dissipate heat is needed to prepare embedded on-chip microchannel Si-based GaN devices. Summary of the invention

[0003] In order to solve the heat accumulation inside the GaN power device chip, develop chip-level thermal management technology, and improve the output characteristics and reliability of GaN devices, the present invention proposes an embedded on-chip microchannel Si-based GaN HEMT device and a preparation method thereof.

[0004] The present invention adopts the following technical solutions to solve the technical problems:

[0005] An embedded on-chip microfluidic Si-based GaN HEMT device comprises, from top to bottom, a gate functional layer, a source functional layer, a drain functional layer, a SiN passivation layer, an AlGaN barrier layer, a GaN buffer layer and a microfluidic structure Si substrate; the microfluidic structure Si substrate comprises a manifold heat dissipation microfluidic structure, which is divided into a microfluidic structure heat transfer area and a drainage structure area; the microfluidic structure heat transfer area is in direct contact with the GaN buffer layer; the microfluidic channels in the drainage structure area are perpendicular to and interconnected with the microfluidic channels in the microfluidic structure heat transfer area, forming a manifold microfluidic heat dissipation structure.

[0006] The depth of the manifold heat dissipation microfluidic structure is 80um--200um, and the width of the microchannel in the drainage structure area and the microchannel in the microfluidic structure heat transfer area are both 20--100um; the microchannel in the microfluidic structure heat transfer area is located at the lower end of the source functional layer or the leakage functional layer, and the depth is 40--100um; the width of the liquid inlet and the liquid outlet in the drainage structure area are both 0.5--1mm.

[0007] The manifold type heat dissipation microfluidic structure is formed by an integrated Si substrate process.

[0008] A method for preparing an embedded on-chip microchannel Si-based GaN HEMT device comprises the following steps:

[0009] 1) Isolate the active area of ​​the device based on traditional technology;

[0010] 2) Use multi-step etching technology to realize the microfluidic channel preparation of the microfluidic structure heat transfer area of ​​the Si substrate;

[0011] 3) Use traditional evaporation process to prepare source and drain functional areas;

[0012] 4) The electroplating process is used to seal the front side of the microfluidic channel in the heat transfer area of ​​the microfluidic structure of the Si substrate;

[0013] 5) Using evaporation technology to grow and prepare the gate functional area;

[0014] 6) ICP etching technology is used to realize the microfluidic channel preparation in the drainage structure area of ​​the Si substrate, and the preparation of Si-based GaN HEMT devices based on embedded on-chip microfluidic channel structure is completed.

[0015] The multi-step etching technology described in step 2) is to first use CHF3 / C4F8 gas to perform ICP directional etching of the main channel from the front side of the Si substrate, and then use XeF2 gas to etch the microchannel width expansion to achieve the microchannel preparation of the microfluidic structure heat transfer area.

[0016] The beneficial effects of the present invention are as follows:

[0017] The present invention introduces fluid into the GaN device chip and designs a manifold microchannel structure, which improves the heat dissipation capacity of the near-junction area in the chip, reduces flow resistance, and improves reliability. Compared with traditional GaN devices, the device thermal resistance can be reduced by more than 70%, which solves the internal heat accumulation of GaN devices and greatly improves the reliability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention provides a schematic diagram of the structure of an embedded on-chip microfluidic Si-based GaN HEMT device, wherein: 1. Si substrate drainage structure region; 2. microfluidic channel in the drainage structure region; 2-a. liquid inlet in the drainage structure region; 2-b. liquid inlet in the drainage structure region; 3. Si substrate microfluidic structure heat transfer region; 4. microfluidic channel in the microfluidic structure heat transfer region; 5. GaN buffer layer; 6. AlGaN barrier layer; 7. SiN passivation layer; 8. source functional layer; 9. drain functional layer; 10. gate functional layer.

[0019] Figure 2 The present invention is a schematic diagram of the process flow of a method for preparing an embedded on-chip microchannel Si-based GaN HEMT device. DETAILED DESCRIPTION

[0020] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0021] Reference Figure 1The present invention proposes a design and manufacturing method of an embedded on-chip microfluidic Si-based GaN HEMT device. The structure design of the high-efficiency heat dissipation GaN HEMT device of the present invention includes, from top to bottom, a gate functional layer 10, a source functional layer 8, a drain functional layer 9, a SiN passivation layer 7, an AlGaN barrier layer 6, a GaN buffer layer 5 and a microfluidic structure Si substrate (composed of a Si substrate microfluidic structure heat transfer area 3 and a Si substrate drainage structure area 1). The microfluidic structure Si substrate has a high heat transfer effect and effectively reduces the junction temperature of the GaN HEMT device. The Si substrate contains a manifold heat dissipation microfluidic structure (composed of a microfluidic channel 2 in the drainage structure area and a microfluidic channel 4 in the microfluidic structure heat transfer area). The microfluidic structure is in direct contact with the buffer GaN layer 5, which effectively increases the heat dissipation capacity and reduces the flow resistance of the fluid. At the same time, the Si substrate contains a manifold structure (composed of a microfluidic channel 2 in the drainage structure area and a microfluidic channel 4 in the microfluidic structure heat transfer area) formed by an integrated Si substrate (composed of a Si substrate microfluidic structure heat transfer area 3 and a Si substrate drainage structure area 1) process. The embedded on-chip micro-channel Si-based GaN HEMT device of the present invention has the advantage of high-efficiency heat dissipation capability and can be used for ultra-high-power microwave power devices.

[0022] Reference Figure 1 The Si substrate of the present invention contains a manifold heat dissipation microfluidic structure, which is divided into two parts: the Si substrate microfluidic structure heat transfer area 3 and the Si substrate drainage structure area 1. The Si substrate microfluidic structure heat transfer area 3 is in direct contact with the GaN buffer layer 5. The microchannels 2 in the drainage structure area and the microchannels 4 in the microfluidic structure heat transfer area are perpendicular to each other, forming a manifold microfluidic heat dissipation structure. This structure effectively increases the heat dissipation capacity and reduces the flow resistance of the microfluid.

[0023] The implementation principle of the present invention: The present invention designs a manifold microfluidic structure of a Si substrate, introduces a multi-step etching technology, first uses CHF3 / C4F8 gas to perform ICP directional etching of the main channel from the front of the Si substrate, and then uses XeF2 gas to perform microchannel width expansion etching to realize the microchannel in the heat transfer area of ​​the microfluidic structure; at the same time, the ICP etching technology is used to realize the preparation of the microchannel in the drainage structure area of ​​the Si substrate; the microchannel in the drainage structure area is perpendicular to the microchannel in the heat transfer area of ​​the microfluidic structure, forming a manifold microfluidic heat dissipation structure. This structure can improve the heat dissipation capacity inside the GaN device chip and solve its heat accumulation problem.

[0024] Reference Figure 1The manifold microfluidic structure design of the Si substrate of the present invention includes a depth of 80um--200um, and the width of the microchannel in the drainage structure area and the microchannel in the microfluidic structure heat transfer area are both 20--100um; wherein the microchannel 4 in the microfluidic structure heat transfer area is located at the lower end of the source functional layer or the drain functional layer, and the depth is designed to be 40--100um; wherein the liquid inlet 2-a in the drainage structure area and the liquid inlet 2-b in the drainage structure area are designed to be 0.5--1mm in width, and the length direction is consistent with the length of the active area of ​​the device chip.

[0025] Reference Figure 2 The present invention proposes a method for manufacturing an embedded on-chip microchannel Si-based GaN HEMT device. The compatibility of the device preparation process is solved by the following steps:

[0026] 1) Device active area isolation: Use traditional ion implantation technology to isolate the active area and define the functional area.

[0027] 2) Preparation of microchannels in the heat transfer area of ​​the microfluidic structure of the Si substrate: First, use SiO2 medium as an etching mask, such as Figure 2 a1; then, photolithography combined with ICP dry etching technology is used to etch SiO2 medium, AlGaN layer and GaN layer; secondly, CHF3 / C4F8 gas is used to perform directional dry etching of Si to achieve preliminary etching of the microchannel in the heat transfer area of ​​the microfluidic structure, and the etching depth meets the requirement of 40--100um, such as Figure 2 a2; finally, using XeF 2 The gas is used to etch the microchannel width, with 1 minute as a cycle, and multiple cycles are performed until the etching width is 20-100um. Figure 2 In b1, the SiO2 dielectric mask is removed by wet etching to complete the preparation of the microchannel in the heat transfer area of ​​the microfluidic structure.

[0028] 3) Preparation of source and drain functional areas: The electron beam evaporation of ohmic metal is completed by traditional process to realize the preparation of source and drain functional areas, such as Figure 2 c1; and plasma evaporation of SiN is used to complete the passivation of GaN devices, such as Figure 2 Middle c2.

[0029] 4) Sealing of the front side of the microfluidic channel in the heat transfer area of ​​the microfluidic structure of the Si substrate: The front side of the microfluidic channel in the heat transfer area of ​​the microfluidic structure of the Si substrate is sealed by a process combining photolithography and electroplating. The electroplated metal is Au material, such as Figure 2 As shown in d1.

[0030] 5) Gate functional area growth preparation: Use processes such as photolithography, etching and electron beam evaporation to achieve the growth preparation of the device gate functional area, such as Figure 2 As shown in e1.

[0031] 6) Preparation of microfluidic channels in the drainage structure area of ​​the Si substrate: Photolithography and ICP (inductively coupled plasma) etching technology are used to perform directional etching from the back of the Si substrate using CHF3 / C4F8 gas to achieve the preparation of microfluidic channels in the drainage structure area of ​​the Si substrate, such as Figure 2 As shown in f1; finally, the mask layer is removed to complete the preparation of the Si-based GaN HEMT device based on the embedded on-chip microchannel structure. Example

[0032] A design and manufacturing method of an embedded on-chip microchannel Si-based GaN HEMT device, specifically comprising:

[0033] 1) Design a Si-based GaN HEMT device, with the source and drain spacing of the active area designed to be 50um, a 10-gate structure, and a Si substrate thickness of 100um. The microfluidic channel of the microfluidic structure heat transfer area is located directly below the source and drain, and its microfluidic structure width is designed to be 25um and its depth is designed to be 50um; the microfluidic channel of the drainage structure area is also 25um wide and 50um deep, and is perpendicular to the microfluidic channel of the microfluidic structure heat transfer area, and its liquid inlet and outlet width are designed to be 0.5mm.

[0034] 2) Design and fabrication of embedded on-chip microchannel Si-based GaN HEMT devices;

[0035] ① Device active area isolation: Use traditional ion implantation process to isolate the active area.

[0036] ② Preparation of microchannels in the microfluidic structure heat transfer area of ​​Si substrate: First, SiO2 medium is used as an etching mask with a thickness of 1um; then, photolithography combined with ICP dry etching technology is used to etch the SiO2 medium, AlGaN layer and GaN layer; secondly, CHF3 / C4F8 gas is used to perform directionally dry etching of Si to achieve preliminary etching of the microchannels in the microfluidic structure heat transfer area with an etching depth of 50um; finally, XeF2 gas is used to etch the microchannel width expansion, with 1min as a cycle, and multiple cycles of etching are performed until the etching width is 25um, and the SiO2 medium mask is removed by wet etching to complete the microchannel preparation in the microfluidic structure heat transfer area.

[0037] ③ Preparation of source and drain functional areas: The traditional process is used to complete the electron beam evaporation of ohmic metals, and the metal Ti / Al / Ni / Au=20 / 160 / 50 / 40nm is deposited to realize the preparation of source and drain functional areas; and plasma evaporation of 200nm SiN medium is used to complete the passivation of GaN devices.

[0038] ④ Sealing the front side of the microfluidic channel in the microfluidic structure heat transfer area of ​​the Si substrate: A combination of photolithography and electroplating is used to seal the front side of the microfluidic channel in the microfluidic structure heat transfer area of ​​the Si substrate. The source and drain areas are metal-thickened and electroplating is used. The electroplating process is used, and the electroplated metal is Au material to achieve sealing of the front side of the microfluidic channel in the microfluidic structure heat transfer area.

[0039] ⑤Gate functional area growth and preparation: Use processes such as photolithography, etching and electron beam evaporation to deposit metal Ni / Au to achieve the growth and preparation of the device gate functional area.

[0040] ⑥ Preparation of microchannels in the drainage structure area of ​​the Si substrate: Photolithography and ICP etching technology are used, SiO2 medium is used as an etching mask, and CHF3 / C4F8 gas is used to perform directional etching from the back of the Si substrate. The etching depth is 50um, so that the microchannels in the drainage structure area of ​​the Si substrate are connected with the microchannels in the heat transfer area of ​​the microfluidic structure, and the manifold microfluidic structure is realized in the Si substrate. Finally, the mask layer is removed to complete the preparation of Si-based GaN HEMT devices based on embedded on-chip microchannel structures.

[0041] Descriptions not involved in the specific embodiments of the present invention belong to the well-known technologies in the art and can be implemented with reference to the well-known technologies.

[0042] The invention has been verified through repeated experiments and has achieved satisfactory trial results.

[0043] The above specific implementation methods and examples are specific support for the technical idea of ​​the design and manufacturing method of an embedded on-chip microchannel Si-based GaN HEMT device proposed in the present invention, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or equivalent modifications made on the basis of this technical solution in accordance with the technical idea proposed in the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An embedded on-chip microchannel Si-based GaN HEMT device, characterized in that: The microfluidic structure includes a gate functional layer, a source functional layer, a drain functional layer, a SiN passivation layer, an AlGaN barrier layer, a GaN buffer layer and a microfluidic structure Si substrate from top to bottom; the microfluidic structure Si substrate includes a manifold heat dissipation microfluidic structure, which is divided into a microfluidic structure heat transfer area and a drainage structure area. The microfluidic structure heat transfer area is in direct contact with the GaN buffer layer, and the microchannels of the drainage structure area are perpendicular to and interconnected with the microchannels of the microfluidic structure heat transfer area, forming a manifold microfluidic heat dissipation structure; The depth of the manifold heat dissipation microfluidic structure is 80um--200um, and the width of the microchannel in the drainage structure area and the microchannel in the microfluidic structure heat transfer area are both 20--100um; the microchannel in the microfluidic structure heat transfer area is located at the lower end of the source functional layer or the drain functional layer, and the depth is 40--100um; the width of the liquid inlet and the liquid outlet in the drainage structure area are both 0.5--1mm; The method for preparing an embedded on-chip micro-channel Si-based GaN HEMT device comprises the following steps: 1) Isolate the active area of ​​the device based on the traditional process; 2) Using multi-step etching technology to realize the microfluidic channel preparation of the microfluidic structure heat transfer area of ​​the Si substrate; 3) Using traditional evaporation process to prepare source and drain functional areas; 4) Using electroplating process to seal the front side of the microfluidic channel in the heat transfer area of ​​the microfluidic structure of the Si substrate; 5) Using evaporation technology to grow and prepare the gate functional area; 6) ICP etching technology is used to realize the microchannel preparation of the drainage structure area of ​​the Si substrate, and the preparation of Si-based GaN HEMT devices based on embedded on-chip microchannel structure is completed.

2. The embedded on-chip microchannel Si-based GaN HEMT device according to claim 1, characterized in that: The manifold type heat dissipation microfluidic structure is formed by an integrated Si substrate process.

3. The embedded on-chip microchannel Si-based GaN HEMT device according to claim 1, characterized in that: A multi-step etching technology is adopted, that is, CHF3 / C4F8 gas is first used for ICP direction etching of the main channel from the front side of the Si substrate, and then XeF2 gas is used for etching to expand the width of the microchannel to realize the microchannel preparation of the heat transfer area of ​​the microfluidic structure.

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