Ga2o3 / sic composite substrate and method for manufacturing the same

Abstract

The application relates to a Ga2O3 / SiC composite substrate and a preparation method thereof, and belongs to the technical field of semiconductor device manufacturing, and solves the problems of high peeling temperature and long peeling time in the prior art. The preparation method comprises the following steps: injecting ions from the surface of bulk Ga2O3 inwards; performing thermal annealing on the bulk Ga2O3 after the ion injection; re-injecting ions from the surface of the bulk Ga2O3 inwards to a specified depth; performing surface activation treatment on the ion injection surface of the bulk Ga2O3 and the bonding surface of SiC, then bonding the ion injection surface of the bulk Ga2O3 and the bonding surface of SiC to obtain a bulk Ga2O3 / SiC composite material; performing high-temperature reinforcement thermal annealing on the bulk Ga2O3 / SiC composite material; annealing the bulk Ga2O3 / SiC composite material to realize peeling of a Ga2O3 film from the bulk Ga2O3; and smoothing the surface of the Ga2O3 film on the SiC.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device manufacturing technology, and in particular to a Ga2O3 / SiC composite substrate and its preparation method. Background Technology

[0002] Gallium oxide, as a wide bandgap semiconductor material with ultra-wide bandgap (~4.8 eV) and ultra-high field strength (theoretically ~8 MV / cm), has the potential to withstand breakdown and low loss, and is expected to be used in the field of power electronics.

[0003] However, Ga2O3 has excessively low thermal conductivity, leading to severe self-heating effects in power devices and causing reliability issues. Against this backdrop, silicon carbide-based Ga2O3 devices can effectively address the problems of severe self-heating and performance degradation, gradually becoming one of the key technologies being developed internationally. However, due to the significant difference between the lattice constant of SiC and Ga2O3, their vastly different coefficients of thermal expansion, and the need for high-quality silicon carbide substrates for heteroepitaxial growth, which is costly, directly growing gallium oxide on silicon carbide substrates is extremely difficult and results in low-quality materials. By using Smart-cut technology combined with bonding technology to transfer gallium oxide films to high thermal conductivity silicon carbide substrates, atomic-level bonding interfaces are obtained with extremely low interfacial thermal resistance, which can solve the problem of severe self-heating effects in devices.

[0004] However, smart-cut typically uses hydrogen ion implantation, which involves high-energy ion implantation. As the implantation depth increases, the peak concentration decreases significantly, resulting in excessively high peeling temperatures, excessive thermal stress, debonding, and peeling difficulties. Furthermore, the higher the implanted ion energy, the greater the damage, leading to low-quality transferred gallium oxide films and severe leakage current in subsequent devices. Additionally, during the peeling process, a small portion of the film transfers to silicon carbide, leaving the entire bonded area unpeeled. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a Ga2O3 / SiC composite substrate and its preparation method, which can at least solve one of the following technical problems: (1) high peeling temperature and long peeling time, and easy debonding of composite substrate; (2) large implantation damage; (3) incomplete peeling.

[0006] The objective of this invention is mainly achieved through the following technical solutions: In a first aspect, the present invention provides a method for preparing a Ga2O3 / SiC composite substrate, comprising the following steps: Step 1: Inject ions from the surface of the bulk Ga2O3 to a specified depth to form a pre-embedded layer at a certain depth from the surface of the bulk Ga2O3; Step 2: Heat-anneal the ion-implanted bulk Ga2O3; Step 3: Re-inject ions from the surface of the bulk Ga2O3 to the specified depth; Step 4: Perform ion beam smoothing on the ion implantation surface of the bulk Ga2O3 and the bonding surface of the SiC substrate, and then bond the ion implantation surface of the bulk Ga2O3 to the bonding surface of the SiC substrate to obtain the bulk Ga2O3 / SiC composite material. Step 5: Perform reinforcement heat annealing on the bulk Ga2O3 / SiC composite material; Step 6: Anneal the bulk Ga2O3 / SiC composite material to achieve the peeling of the Ga2O3 thin film layer from the bulk Ga2O3; Step 7: Smooth the surface of the Ga2O3 thin film layer on the SiC substrate.

[0007] Optionally, in step 1, the implanted ion is a deuterium ion or a hydrogen ion with a mass of 2.

[0008] Optionally, in step 3, the injected ion is a hydrogen ion.

[0009] Optionally, in step 2, the annealing temperature is 200~300℃ and the annealing time is 5-15min.

[0010] Optionally, in step 5, the heat annealing temperature is 200℃~300℃, and the annealing time is 1h~72h.

[0011] Optionally, in step 4, the bonding method is room temperature surface activation bonding, hot-press bonding, hydrophilic bonding, anodic bonding, or epitaxial liftoff.

[0012] Optionally, in step 1, the implantation depth is 100 nm to 1 μm.

[0013] Optionally, in step 3, the injection dose is 1×10 16 ~6×10 16 ions·cm -2 .

[0014] Optionally, in step 7, chemical mechanical polishing and ion beam smoothing techniques are used sequentially for smoothing.

[0015] Secondly, the present invention also provides a Ga2O3 / SiC composite substrate, prepared using the above-described preparation method. The composite substrate comprises a SiC substrate and a Ga2O3 thin film layer bonded to the SiC substrate. The thickness of the Ga2O3 thin film layer is 0.1-1 µm. Gallium oxide lateral power devices fabricated on this composite substrate exhibit good heat dissipation and high power density.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) The ion implantation technology in the prior art uses H ions for implantation.+ Furthermore, for a one-step implantation, this invention optimizes the implantation process (i.e., employs segmented ion implantation) and uses a specific combination of implanted ions (the first segment of ion implantation uses deuterium ions or hydrogen ions H2 with a mass of 2). + The second stage of ion implantation uses hydrogen ions (H+). + This effectively reduces the peeling temperature (the peeling temperature of the prior art is above 450°C, while the peeling temperature of the present invention is only 300-430°C) and significantly shortens the peeling time (the peeling time of the prior art is about 30 minutes, while the peeling time of the present invention is less than 1 minute).

[0017] Furthermore, since this invention uses deuterium ions or hydrogen ions with a mass of 2 for gallium oxide implantation in the first stage, compared to the existing method which uses hydrogen ions with a mass of 1... + In comparison, at the same peel-off film depth, the implantation energy is reduced, thus reducing channel layer implantation damage, minimizing device channel layer defects, and improving the performance and reliability of power devices. Simultaneously, during high-energy ion implantation, using deuterium ions or hydrogen ions with a mass of 2 to implant gallium oxide significantly increases the peak implantation concentration while increasing the implantation depth, making peeling easier, reducing peeling temperature, and shortening peeling time.

[0018] (2) The annealing (preheating) process used in the first stage of ion implantation in this invention causes the implanted ions to generate bubbles. At this temperature, the bubbles do not aggregate or crack, but can promote the formation of cracks between grain boundaries, which is beneficial to the complete separation of the film, thereby making it easier to completely peel off gallium oxide.

[0019] (3) In the second stage of ion implantation, the present invention selects a hydrogen ion supplement dose of mass 1. After ion implantation of gallium oxide, it converges into a thin layer at a certain depth. This layer is called the ion convergence layer. The hydrogen ion mass is 1. The ion convergence layer formed after implantation is thinner, so it can be implanted more accurately into the cracked area between grain boundaries and more efficiently supplement the implanted ion dose.

[0020] (4) The present invention attaches a micro-nano-sized gallium oxide thin film to a thick silicon carbide film, which solves the problems that micro-nano-sized gallium oxide thin films cannot be self-supporting and have difficulty in heat dissipation.

[0021] (5) The composite substrate prepared by the ion implantation process of the present invention makes the subsequent device preparation process simple, the performance is greatly improved, the thermal management is easy, the yield is high, the cost is drastically reduced, and it is suitable for mass production of devices, thus promoting industrialization.

[0022] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or may be learned by practicing the invention. Attached Figure Description

[0023] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0024] Figure 1 This is a flowchart illustrating the preparation of the Ga2O3 / SiC composite substrate according to the present invention.

[0025] Figure label: 1-Bulk Ga2O3; 2-Embedded layer; 3-SiC substrate; 4-Ga2O3 thin film layer. Detailed Implementation

[0026] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention. Unless otherwise specified, some processes of the present invention employ existing processes.

[0027] In a first aspect, the present invention provides an ion implantation process and a method for preparing composite substrates that reduces the smart-cut stripping temperature. For example... Figure 1 As shown, the ion implantation process of the present invention includes the following steps: Step 1: Inject ions into the Ga2O31 body to a specified depth to form a pre-embedded layer 2 with a certain depth from the surface of the Ga2O31 body; Step 2: Rapidly thermally anneal the ion-implanted bulk Ga2O31; Step 3: Re-inject ions into the surface of the bulk Ga2O31 to the specified depth; Step 4: The ion implantation surface of bulk Ga2O31 and the bonding surface of SiC substrate 3 are subjected to ion beam smoothing treatment and X element implantation. Then, the ion implantation surface of bulk Ga2O31 is bonded to the bonding surface of SiC substrate 3 to obtain bulk Ga2O3 / SiC composite material. Step 5: Perform high-temperature hardening annealing on the bulk Ga2O3 / SiC composite material; Step 6: Anneal the bulk Ga2O3 / SiC composite material to achieve the peeling of the Ga2O3 thin film layer 4 from the bulk Ga2O3. After the Ga2O3 thin film layer 4 is successfully transferred to the SiC substrate 3, the bulk Ga2O3 enters the recycling process in Step 1. Step 7: Smooth the surface of the Ga2O3 thin film layer 4 on the SiC substrate 3.

[0028] Existing ion implantation techniques use H+ as the implanted ion. +Furthermore, for a one-step implantation, this invention optimizes the implantation process (i.e., employs segmented ion implantation) and uses a specific combination of implanted ions (the first segment of ion implantation uses deuterium ions or hydrogen ions H2 with a mass of 2). + The second stage of ion implantation uses hydrogen ions (H+). + This effectively reduces the peeling temperature (the peeling temperature of the prior art is above 450°C, while the peeling temperature of the present invention is only 300-430°C) and significantly shortens the peeling time (the peeling time of the prior art is about 30 minutes, while the peeling time of the present invention is less than 1 minute).

[0029] Furthermore, since this invention uses deuterium ions or hydrogen ions with a mass of 2 for gallium oxide implantation in the first stage, compared to the existing method which uses hydrogen ions with a mass of 1... + In comparison, at the same peel-off film depth, the implantation energy is reduced, thus reducing channel layer implantation damage, minimizing device channel layer defects, and improving the performance and reliability of power devices. Simultaneously, during high-energy ion implantation, using deuterium ions or hydrogen ions with a mass of 2 to implant gallium oxide significantly increases the peak implantation concentration while increasing the implantation depth, making peeling easier, reducing peeling temperature, and shortening peeling time.

[0030] Specifically, in step 1, the implantation depth is 100nm to 1μm, for example, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, or 1μm. Studies have found that when the implantation depth exceeds 1μm, the surface roughness of the bonding surface increases, which is detrimental to bonding. Therefore, this invention controls the implantation depth to be 100nm to 1μm.

[0031] The implanted ion is either a deuterium ion with a mass of 2 or a hydrogen ion (H2). + The injection dose is 3×10 16 ~1×10 17 ions·cm -2 For example, 3×10 16 ions·cm -2 4×10 16 ions·cm -2 5×10 16 ions·cm -2 6×10 16 ions·cm -2 7×10 16 ions·cm -2 8×10 16 ions·cm -2 9×10 16 ions·cm -2 1×10 17ions·cm -2 .

[0032] Specifically, in step 2, the annealing temperature is 200~300℃, for example, 200℃, 220℃, 240℃, 250℃, 260℃, 280℃, 290℃, and 300℃. Studies have found that controlling the annealing temperature at 200~300℃ allows the implanted ions to generate bubbles. At this temperature, the bubbles do not aggregate or crack, but they do promote the formation of cracks at grain boundaries, which is beneficial for the complete separation of the film, thus making it easier to completely peel off gallium oxide.

[0033] Annealing time is 5-15 minutes, for example, 5 minutes, 7 minutes, 9 minutes, 10 minutes, 12 minutes, 14 minutes, and 15 minutes.

[0034] Specifically, in steps 1 and 3, the injection angle is a small angle, specifically 0°-30°, for example, 0°, 5°, 10°, 15°, 20°, 25°, and 30°.

[0035] It should be noted that the injection angle refers to the angle between the injected ion and the surface of the ion to be injected.

[0036] Specifically, in step 3, the injected ion is a hydrogen ion, and the injection dose is 1×10⁻⁶. 16 ~6×10 16 ions·cm -2 For example, 1×10 16 ions·cm -2 2×10 16 ions·cm -2 3×10 16 ions·cm -2 4×10 16 ions·cm -2 5×10 16 ions·cm -2 6×10 16 ions·cm -2 The injection depth is the same as in step 1, which is 100nm~1μm, for example, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm.

[0037] The purpose of the second ion implantation is to address the ion escape that occurred in step 2, and to replenish the dose by re-implanting hydrogen ions. After ion implantation into gallium oxide, the ions converge into a thin layer at a certain depth; this layer is called the ion aggregation layer. The mass of the hydrogen ions is 1. The ion aggregation layer formed after implantation is thinner, allowing for more precise implantation into the cracked areas between grain boundaries, and more efficient replenishment of the implanted ion dose. Specifically, in step 4, the preferred bonding methods are room temperature surface activation bonding, thermocompression bonding, hydrophilic bonding, anodic bonding, and epitaxial liftoff. Ion beam smoothing addresses the issues of high surface roughness and peak reduction, while X element implantation achieves elemental compensation or doping, and also enhances the bond energy of surface materials, thus activating the element.

[0038] It should be noted that element X refers to the target element, such as Si, Ge, Fe, etc.

[0039] Specifically, in step 5, the heat annealing temperature is 200℃~300℃, for example, 200℃, 220℃, 240℃, 250℃, 270℃, 290℃, and 300℃. This temperature is beneficial for increasing the bonding strength of the bulk Ga2O3 / SiC composite material without causing excessive thermal stress that could lead to debonding.

[0040] Annealing times range from 1 hour to 72 hours, for example, 1 hour, 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, 15 hours, 17 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours, and 72 hours. Controlling the annealing time to 1 hour to 72 hours can increase the number of microbubbles, bringing gallium oxide to a high-stress critical state of bubble pre-polymerization or cracking.

[0041] Specifically, in step 6, the peeling temperature is 300-430℃, for example, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, and 430℃. The peeling time is less than 1 minute, ranging from 10-55 seconds, for example, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, and 55 seconds.

[0042] Specifically, in step 7, chemical mechanical polishing (CMP) and ion beam smoothing are performed sequentially. CMP reduces the roughness of the gallium oxide material at the micro-nano scale from 10 nm to 0.5 nm, while ion beam smoothing reduces the roughness from 0.5 nm to below 0.2 nm, addressing localized protrusions and particles, thus achieving a smooth and even surface across the entire gallium oxide film. Therefore, the final surface roughness of the gallium oxide film layer is below 0.2 nm.

[0043] Furthermore, the composite substrate prepared by the above-described ion implantation process exhibits good compatibility with semiconductor device fabrication processes. The gallium oxide device also includes a source electrode, a drain electrode, and a gate electrode disposed on the gallium oxide layer. Existing methods can be used to fabricate the source electrode, drain electrode, and gate electrode on the gallium oxide layer.

[0044] Secondly, the present invention also provides a composite substrate for semiconductor devices, which is prepared using the above-described process. The composite substrate includes a SiC substrate 3 and a Ga2O3 thin film layer 4 bonded to the SiC substrate 3. The thickness of the Ga2O3 thin film layer 4 is 0.1-1 µm. Gallium oxide lateral power devices fabricated on this composite substrate exhibit good heat dissipation and high power density.

[0045] Example 1 Step 1: Inject 2 deuterium ions into the surface of the bulk Ga2O31 at an injection angle of 0°, with an injection dose of 6 × 10⁻⁶. 16 ions·cm -2 The injection depth is 100nm, forming a pre-embedded layer 2 with a certain depth at a distance from the surface of the Ga2O31 body; Step 2: Anneal the ion-implanted bulk Ga2O31 at 200℃ for 15 min; Step 3: Inject hydrogen ions into the bulk Ga2O31 from the surface at an injection angle of 0°, with an injection dose of 1×10⁻⁶. 16 ions·cm -2 The injection depth is 100nm; Step 4: Surface activation treatment and Fe element implantation are performed on the ion implantation surface of bulk Ga2O31 and the bonding surface of SiC. Hot pressing bonding is used to bond the ion implantation surface of bulk Ga2O31 to the bonding surface of SiC to obtain bulk Ga2O3 / SiC composite material. Step 5: Anneal the bulk Ga2O3 / SiC composite material at 200℃ for 72h; Step 6: Anneal the bulk Ga2O3 / SiC composite material to achieve the peeling of the Ga2O3 thin film layer from the bulk Ga2O3, the peeling temperature is 350℃ and the peeling time is 55s; After the Ga2O3 thin film layer is successfully transferred to the silicon carbide substrate, the bulk Ga2O3 is recycled in Step 1; Step 7: The surface of the Ga2O3 thin film layer on SiC is smoothed by chemical mechanical polishing (CMP) and ion beam smoothing techniques in sequence.

[0046] Example 2 Step 1: Inject 2 hydrogen ions (H2) into the surface of the bulk Ga2O31 at an injection angle of 7°. + The injection dose is 1×10 17ions·cm -2 The injection depth is 1μm, forming a pre-embedded layer 2 with a certain depth at a distance from the surface of the Ga2O31 body; Step 2: Anneal the ion-implanted bulk Ga2O31 at 300℃ for 5 min; Step 3: Inject hydrogen ions into the bulk Ga2O31 from the surface at an injection angle of 7°, with an injection dose of 6 × 10⁻⁶. 16 ions·cm -2 The injection depth is 1 μm; Step 4: Perform surface activation treatment and Si element implantation on the ion implantation surface of bulk Ga2O31 and the bonding surface of SiC. Use room temperature surface activation method to bond the ion implantation surface of bulk Ga2O31 to the bonding surface of SiC to obtain bulk Ga2O3 / SiC composite material. Step 5: Anneal the bulk Ga2O3 / SiC composite material at 300℃ for 1 hour; Step 6: Anneal the bulk Ga2O3 / SiC composite material to achieve the peeling of the Ga2O3 thin film layer from the bulk Ga2O3. The peeling temperature is 430℃ and the peeling time is 10 seconds. After the Ga2O3 thin film layer is successfully transferred to the silicon carbide substrate, the bulk Ga2O3 is recycled in Step 1. Step 7: The surface of the Ga2O3 thin film layer on SiC is smoothed by chemical mechanical polishing (CMP) and ion beam smoothing techniques in sequence.

[0047] Example 3 Step 1: Inject 2 deuterium ions into the surface of the bulk Ga2O31 at an injection angle of 15°, with an injection dose of 8 × 10⁻⁶. 16 ions·cm -2 The injection depth is 500nm, forming a pre-embedded layer 2 with a certain depth at a distance from the surface of the Ga2O31 body; Step 2: Anneal the ion-implanted bulk Ga2O31 at 250℃ for 9 min; Step 3: Inject hydrogen ions into the bulk Ga2O31 from the surface at an injection angle of 15°, with an injection dose of 4 × 10⁻⁶. 16 ions·cm -2 The implantation depth is 500 nm; Step 4: Surface activation treatment and Ge element implantation are performed on the ion implantation surface of bulk Ga2O31 and the bonding surface of SiC. Hydrophilic bonding is used to bond the ion implantation surface of bulk Ga2O31 to the bonding surface of SiC to obtain bulk Ga2O3 / SiC composite material. Step 5: Anneal the bulk Ga2O3 / SiC composite material at 250℃ for 30h; Step 6: Anneal the bulk Ga2O3 / SiC composite material to achieve the peeling of the Ga2O3 thin film layer from the bulk Ga2O3, the peeling temperature is 380℃ and the peeling time is 25s; After the Ga2O3 thin film layer is successfully transferred to the silicon carbide substrate, the bulk Ga2O3 is recycled in Step 1; Step 7: The surface of the Ga2O3 thin film layer on SiC is smoothed by chemical mechanical polishing (CMP) and ion beam smoothing techniques in sequence.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a Ga2O3 / SiC composite substrate, characterized in that, Includes the following steps: Step 1: Inject ions from the surface of the bulk Ga2O3 to a specified depth to form a pre-embedded layer at a certain depth from the surface of the bulk Ga2O3; Step 2: Heat-anneal the ion-implanted bulk Ga2O3; Step 3: Re-inject ions from the surface of the bulk Ga2O3 to the specified depth; Step 4: Perform ion beam smoothing and X element implantation on the ion implantation surface of the bulk Ga2O3 and the bonding surface of the SiC substrate, and then bond the ion implantation surface of the bulk Ga2O3 to the bonding surface of the SiC substrate to obtain the bulk Ga2O3 / SiC composite material. Step 5: Perform reinforcement heat annealing on the bulk Ga2O3 / SiC composite material; Step 6: Anneal the bulk Ga2O3 / SiC composite material to achieve the peeling of the Ga2O3 thin film layer from the bulk Ga2O3; Step 7: Smooth the surface of the Ga2O3 thin film layer on the SiC substrate; In step 1, the injected ions are either deuterium ions or hydrogen ions with a mass of 2. In step 3, the injected ions are hydrogen ions; The element X includes one of Si, Ge, and Fe.

2. The preparation method according to claim 1, characterized in that, In step 2, the annealing temperature is 200~300℃ and the annealing time is 5-15min.

3. The preparation method according to claim 1, characterized in that, In step 5, the heat annealing temperature is 200℃~300℃, and the annealing time is 1h~72h.

4. The preparation method according to claim 1, characterized in that, In step 4, the bonding method is room temperature surface activation bonding, hot pressing bonding, hydrophilic bonding, anodic bonding, or epitaxial liftoff.

5. The preparation method according to claim 1, characterized in that, In step 1, the injection depth is 100nm~1μm.

6. The preparation method according to claim 1, characterized in that, In step 3, the injection dose is 1×10 16 ~6×10 16 ions·cm -2 .

7. The preparation method according to claim 1, characterized in that, In step 7, chemical mechanical polishing and ion beam smoothing techniques are used sequentially for smoothing.

8. A Ga2O3 / SiC composite substrate, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

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