Epitaxial method and device of double-sided metal polarity III-group nitride material

Abstract

The invention discloses a double-sided metal polarity III-group nitride material epitaxy method and device, and belongs to the technical field of semiconductors. According to the method, after the N polar surface of the III-group nitride material substrate is subjected to oxygen treatment, the AlN is deposited through PVD, oxygen can be introduced in the deposition process, and high-quality metal polar AlN is obtained on the N polar surface; and then in-situ high-temperature low-pressure nitrogen treatment is carried out on the PVD-AlN, so that the quality of the PVD-AlN layer is improved, impurities on a growth interface are reduced, an N vacancy is filled, and high-temperature decomposition of the PVD-AlN layer is inhibited, thereby improving the crystal quality and the electrical property of a subsequently grown III-group nitride material. By fully utilizing the two metal polar surfaces of the front surface and the back surface, high-performance III-nitride devices with metal polarity can be prepared on the two surfaces respectively, the integration level of the devices is improved, the cost is reduced, and the III-nitride devices with full-vertical structures can be prepared by developing processes on the two surfaces respectively.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a double-sided metal polarity III-group nitride material epitaxial growth method and device. Background Art

[0002] Group III nitride materials have many advantages such as large bandgap, high breakdown field strength, large electron saturation drift rate, high temperature and radiation resistance, etc., and have important applications in power electronics, radio frequency electronics and optoelectronic devices. However, since the lattice structure of group III nitrides lacks inversion symmetry in the c-axis direction, it often exhibits nitrogen (N) polarity on one side and metal polarity on the other side. At present, the research and products on the epitaxy and devices of group III nitride materials are mainly planar structure devices or quasi-vertical structure devices on the metal polarity surface. There are few studies on the epitaxy and devices of materials on the N polarity surface, and the difficulty of material growth and device processing is also higher than that of the metal polarity surface.

[0003] With the deepening of research on epitaxy and devices of III-nitride materials, fully vertical III-nitride devices have to use both the metal polarity surface and the N-side of III-nitride materials, which exposes problems such as low ohmic contact quality of the N-polarity surface and high roughness of the N-polarity surface. On the other hand, with the popularization of the application of epitaxy and devices of III-nitride materials, high cost is a major bottleneck restricting the industrialization of epitaxy and devices of III-nitride materials. The main reason for this problem is that the integration of III-nitride devices is low, and the cost of epitaxy and device processes is high, resulting in high cost of a single chip. Summary of the invention

[0004] In order to solve the N-polarity problem of the above-mentioned fully vertical III-nitride device and reduce the cost of the III-nitride device, the present invention provides a double-sided metal polarity III-nitride material epitaxy method, which can realize the preparation of double-sided metal polarity devices and fully vertical III-nitride devices. The present invention is achieved through the following technical solutions: A double-sided metal polarity III-nitride material epitaxy method is firstly selected. For a III-nitride material substrate with N polarity on the front side, steps A1 to A7 are performed; for a III-nitride material substrate with metal polarity on the front side, steps B1 to B7 are performed.

[0005] A1. Oxygen treatment of the front side (N polar side) of the III-nitride material substrate; A2. Deposition of AlN on the front side using physical vapor deposition (PVD); A3. Treat the sample with in-situ high temperature and low pressure nitrogen; A4. Growing a metal-polarity III-nitride material on the front side to prepare a metal-polarity III-nitride device; A5. Bond a temporary carrier to the front of the sample; A6. Growing metal-polarity III-nitride material on the back side (metal-polarity side) of the sample to prepare metal-polarity III-nitride devices; A7. Remove the bonded temporary carrier.

[0006] B1. growing a metal polarity III-nitride material on the front side (metal polarity side) of the III-nitride material substrate to prepare a metal polarity III-nitride device; B2. Bonding a temporary carrier to the front of the sample; B3. Treat the back side (N polar side) of the sample with oxygen; B4. Depositing AlN on the back of the sample using physical vapor deposition (PVD); B5. Perform in-situ high temperature and low pressure nitrogen treatment on the samples; B6. Growing a metal-polarity III-nitride material on the back of the sample to prepare a metal-polarity III-nitride device; B7. Remove the bonded temporary carrier.

[0007] The III-nitride material substrate selected by the above method can be a GaN substrate with Ga polarity or N polarity on the front side, or an AlN substrate with Al polarity or N polarity on the front side; it can also be a bonded substrate with a bonded functional layer, wherein the functional layer is a GaN layer with Ga polarity or N polarity on the front side, or an AlN layer with Al polarity or N polarity on the front side.

[0008] In the above steps A1 and B3, the method of oxygen treatment on the N-polar surface can be one of the following methods or a combination thereof: ① Oxygen plasma treatment: The gas introduced into the oxygen plasma treatment can be oxygen (O2) or a mixed gas containing oxygen, the treatment time can be 10 seconds to 10 minutes, and the treatment power can be 50 W to 3000 W. W, wherein the oxygen-containing mixed gas contains at least one of oxygen and ozone, and contains at least one of nitrogen, inert gas, halogen gas, and halogen compound gas; ② Gas oxidation: The atmosphere of gas oxidation can be oxygen (O2), ozone (O3) or an oxygen-containing mixed gas, the temperature can be room temperature to 2000°C, and the oxidation time can be 10 seconds to 1 month, wherein the oxygen-containing mixed gas contains at least one of oxygen and ozone, and contains at least one of nitrogen and inert gas, preferably, the volume proportion of oxygen or ozone is greater than 20%; ③ Chemical solution oxidation: The solution of chemical solution oxidation can be hydrogen peroxide (H2O2), deionized water (H2O) or other oxygen-containing solutions, the temperature can be room temperature to 300°C, and the time can be 10 seconds to 1 hour, wherein the other oxygen-containing solutions can be aqueous solutions of oxygen, aqueous solutions of ozone, etc.

[0009] In the above steps A2 and B4, AlN is deposited by PVD. Specifically, the Al source used is an Al target, the N source is nitrogen (N2), the deposition temperature is from room temperature to 1000° C., and the deposition thickness is 10 nm to 10 μm.

[0010] In the above steps A2 and B4, oxygen can be introduced during the deposition of AlN. The flow rate of the introduced oxygen can be 0.1 sccm to 10 sccm. The oxygen can be introduced during the entire deposition process or during part of the deposition process.

[0011] In the above steps A2 and B4, the sample may be subjected to high temperature annealing after depositing AlN, and the annealing temperature may be 100° C. to 2000° C.

[0012] In the above steps A3 and B5, the sample is subjected to in-situ high-temperature low-pressure nitrogen treatment. In-situ means that the high-temperature low-pressure nitrogen treatment is carried out in the chamber of the equipment used in the subsequent growth process, and the growth is carried out immediately after the treatment. The high temperature can be 100°C to 1500°C, preferably 800°C to 1300°C; the low pressure can be 10 -11 mbar ~ 10 2 mbar; nitrogen treatment means that the chamber atmosphere can be nitrogen (N2), ammonia (NH3) or a nitrogen-containing mixed gas, and the treatment time can be 5 min~300 min, wherein the nitrogen-containing mixed gas is a mixed gas of nitrogen and / or ammonia and hydrogen, and the volume proportion of nitrogen and / or ammonia is greater than 40%.

[0013] In the above steps A4, A6, B1 and B6, the method for growing the metal-polarity III-group nitride material can be metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE) or a combination thereof. The metal-polarity III-group nitride material includes GaN with a Ga surface, AlN with an Al surface, InN with an In surface, and a ternary or quaternary compound composed of the above three binary compounds, as well as a stacked combination of the above compounds, and the above compounds and compound stacked combinations with other element doping (such as Si, C, Fe, Mg).

[0014] In the above steps A4, A6, B1 and B6, metal-polarity III-nitride devices are prepared, including power electronic devices, radio frequency electronic devices, optoelectronic devices and other semiconductor devices, and also include the device structure of a fully vertical device on this side.

[0015] In the above steps A5 and B2, after the temporary carrier is bonded to the front side of the sample, the back side may be thinned and polished. Specifically, the bonded temporary carrier may be a silicon (Si) wafer, a sapphire wafer, a quartz wafer, etc. The back side thinning method may be mechanical grinding, and the polishing method may be mechanical polishing (MP) first, followed by chemical mechanical polishing (CMP).

[0016] Beneficial effects of the present invention: In the epitaxial method of the double-sided metal polarity III-nitride material provided by the present invention, the N-polarity surface of the III-nitride material is treated with oxygen before PVD deposition of AlN, oxygen can be introduced during the PVD deposition of AlN, and high-quality metal polarity AlN is obtained on the N-polarity surface; the PVD-AlN is treated with in-situ high-temperature and low-pressure nitrogen, which can not only improve the quality of the PVD-AlN layer, but also reduce impurities on the growth interface, fill N vacancies in the PVD-AlN layer, and inhibit the high-temperature decomposition of the PVD-AlN layer, thereby improving the crystal quality and electrical properties of the grown III-nitride material, and finally achieving the growth of high-quality metal polarity III-nitride material on the N-polarity surface III-nitride material. By making full use of the two metal polarity surfaces on the front and back sides, high-performance III-nitride devices with metal polarity can be prepared on both sides, improving the device integration and reducing costs, and processes can also be carried out on both sides to prepare a fully vertical structure III-nitride device. The double-sided metal polarity III-nitride material or device prepared by the method of the present invention, including the III-nitride device with a full vertical structure, is also within the protection scope of the present invention.

[0017] The present invention obtains a double-sided metal-polarity III-nitride material by using the technology of growing metal-polarity III-nitride material on the N-polarity surface, which not only solves the N-side problem faced by the III-nitride device with a full vertical structure, but also improves the integration of the III-nitride device and reduces the device cost by using the method of preparing the device on both sides of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic flow chart of a device preparation method for epitaxy of a III-nitride material with double-sided metal polarity according to a first embodiment of the present invention.

[0019] Figure 2 It is a schematic flow chart of a device preparation method for epitaxy of a III-nitride material with double-sided metal polarity according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0021] Embodiment 1 See also Figure 1 , the preparation of the double-sided metal polarity device is achieved according to the following steps 11-17: Step 11, select a bonding substrate whose front side of the bonding functional layer is N-polar AlN. Specifically, the bonding substrate is in the shape of a 2-inch wafer, the supporting layer material is ceramic AlN, the supporting layer thickness is 500 μm, the bonding dielectric layer material is SiO2, the bonding dielectric layer thickness is 200 nm, the functional layer material is AlN, the functional layer thickness is 500 nm, and the front side of the functional layer is an N-polar surface.

[0022] Step 12, oxygen treatment is performed on the sample surface, i.e., the front side of the functional layer of the bonding substrate. Specifically, the oxygen treatment method is oxygen plasma treatment, the gas introduced is a mixed gas of oxygen and argon, wherein the flow ratio of oxygen to argon is 5:2, the treatment time is 30 seconds, and the treatment power is 500W.

[0023] Step 13, deposit PVD-AlN on the sample surface and perform high temperature annealing on the sample. Specifically, the Al source used for PVD is Al target, the N source is nitrogen, the deposition temperature is 650°C, and the deposition thickness is 200 nm. Oxygen is introduced throughout the deposition process, and the oxygen flow rate is 1 sccm. The temperature of high temperature annealing is 850°C, the time is 30 minutes, and the atmosphere is nitrogen.

[0024] Step 14, the sample is subjected to in-situ high-temperature and low-pressure nitrogen treatment, and then a metal-polarity III-nitride material is grown on the front. Specifically, the sample is sent into the MOCVD chamber for in-situ high-temperature and low-pressure nitrogen treatment, the temperature is 1020°C, the pressure is 100 mbar, the chamber atmosphere is a mixture of ammonia and hydrogen, the volume ratio of ammonia to hydrogen is 1:1, and the treatment time is 10 minutes. The method for growing metal-polarity III-nitride materials on the surface is MOCVD, and the growth stacked structure is GaN buffer layer, n-GaN (Si-doped GaN) layer, superlattice layer, p-GaN (Mg-doped GaN) layer.

[0025] Step 15, preparing an LED (light emitting diode) on the front side of the sample. Specifically, using semiconductor processes such as photolithography, etching, and deposition, a quasi-vertical LED device is prepared on the front epitaxial layer.

[0026] Step 16, bonding a temporary carrier on the front side, removing the back-bonded substrate support layer and the bonding dielectric layer, and polishing the back side of the sample. Specifically, the temporary carrier bonded on the front side is a Si wafer with a thickness of 500 μm. The method for removing the back-bonded substrate support layer and the bonding dielectric layer is mechanical grinding. The method for polishing the back side of the sample is first mechanical polishing and then chemical mechanical polishing.

[0027] Step 17, grow metal polarity III group nitride material on the back of the sample to prepare HEMT (high mobility transistor), and remove the Si wafer temporarily bonded on the front. Specifically, the method for growing metal polarity III group nitride material on the back of the sample is MBE, and the growth stacked structure is GaN buffer layer, high resistance GaN layer, GaN channel layer, AlN insertion layer, AlGaN barrier layer, GaN cap layer. Then, use semiconductor processes such as lithography, etching, and deposition to prepare HEMT devices on the back. Finally, remove the Si wafer temporarily bonded on the front.

[0028] Through the above steps, an integrated chip with a metal polarity LED device on the front and a metal polarity HEMT device on the back is obtained. Both sides of this integrated chip are based on metal polarity materials, and have better device performance than N-polarity materials. In addition, the double-sided device improves the integration and reduces the chip cost.

[0029] Embodiment 2 See also Figure 2 , according to the following steps 21-27, the preparation of a double-sided metal polarity full vertical structure GaN device is achieved: Step 21, select a Ga-polarity GaN substrate. Specifically, the Ga-polarity GaN substrate has a size of 1 cm×1 cm square, a thickness of 350 μm, and a Ga surface on the front side.

[0030] Step 22, grow metal polarity III-nitride material on the front of the sample, and implement the front process of the vertical structure device. Specifically, the method of growing metal polarity III-nitride material on the front of the sample is MOCVD, and the growth stacked structure is n-GaN, GaN, and p-GaN in sequence. Then use semiconductor technology to prepare the front process of the vertical structure device such as the table and metal electrode.

[0031] Step 23, a temporary carrier is bonded on the front side, and the back side is thinned and polished. Specifically, the temporary carrier bonded on the front side is a sapphire sheet. The back side is thinned, and the substrate is thinned to 100 μm by mechanical grinding, and then mechanical polishing and chemical mechanical polishing are performed.

[0032] Step 24, oxygen treatment is performed on the back side. Specifically, the oxygen treatment method is chemical solution oxidation, and the sample is placed in a 5% concentration H2O2 aqueous solution and immersed at room temperature for 1 minute.

[0033] Step 25, PVD-AlN is deposited on the back side, and the sample is subjected to high temperature annealing. Specifically, the Al source used for PVD is an Al target, the N source is nitrogen, the deposition temperature is 500°C, and the deposition thickness is 100 nm. No oxygen is introduced during the deposition process. The temperature of the high temperature annealing is 800°C, the time is 10 minutes, and the atmosphere is nitrogen.

[0034] Step 26, the sample is subjected to in-situ high temperature and low pressure nitrogen treatment to grow metal polarity III group nitride material on the back. Specifically, the sample is sent into the MBE chamber for in-situ high temperature and low pressure nitrogen treatment at a temperature of 700°C and a pressure of 10 - 11 mbar, the chamber atmosphere is ammonia, and the processing time is 10 min. The method for growing the metal-polar III-nitride material on the back side is MBE, and the growth material is n-GaN.

[0035] Step 27, perform backside processing of the vertical structure device on the backside, and remove the temporarily bonded sapphire sheet. Specifically, perform backside processing of the vertical structure device such as isolation structure and metal electrode on the backside by using semiconductor process. Finally, remove the temporarily bonded sapphire sheet.

[0036] Through the above steps, a fully vertical structured GaN device with metal polarity on both sides is obtained, which avoids the N-polarity ohmic contact and roughness problems of traditional fully vertical structured GaN devices and improves the performance of the fully vertical structured GaN device.

[0037] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for epitaxy of a double-sided metal-polarity III-nitride material, firstly selecting a III-nitride material substrate, characterized in that: For a III-nitride material substrate with N polarity on the front side, perform steps A1 to A7: A1. Oxygen treatment of the front side of the III-nitride material substrate; A2. Deposition of AlN on the front side using physical vapor deposition; A3. Treat the sample with in-situ high temperature and low pressure nitrogen; A4. Growing a metal-polarity III-nitride material on the front side to prepare a metal-polarity III-nitride device; A5. Bond a temporary carrier to the front of the sample; A6. Growing a metal-polarity III-nitride material on the back of the sample to prepare a metal-polarity III-nitride device; A7. Remove the bonded temporary carrier; For a III-nitride material substrate with a metal polarity on the front side, perform steps B1 to B7: B1. Growing a metal-polarity III-nitride material on the front side of the III-nitride material substrate to prepare a metal-polarity III-nitride device; B2. Bonding a temporary carrier to the front of the sample; B3. Oxygen treatment on the back of the sample; B4. Depositing AlN on the back of the sample using physical vapor deposition; B5. Perform in-situ high temperature and low pressure nitrogen treatment on the samples; B6. Growing a metal-polarity III-nitride material on the back of the sample to prepare a metal-polarity III-nitride device; B7. Remove the bonded temporary carrier.

2. The epitaxial method according to claim 1, characterized in that: The selected III-nitride material substrate is a GaN substrate with Ga polarity or N polarity on the front side, an AlN substrate with Al polarity or N polarity on the front side, or a bonded substrate with a bonded functional layer, wherein the functional layer is a GaN layer with Ga polarity or N polarity on the front side, or an AlN layer with Al polarity or N polarity on the front side.

3. The epitaxial method according to claim 1, characterized in that: In steps A1 and B3, the N-polar surface of the III-nitride material substrate is subjected to oxygen treatment by one or more of the following methods: oxygen plasma treatment, gas oxidation, and chemical solution oxidation.

4. The epitaxial method according to claim 3, characterized in that: The gas introduced into the oxygen plasma treatment is oxygen or a mixed gas containing oxygen, the treatment time is 10 seconds to 10 minutes, and the treatment power is 50 W to 3000 W, wherein the mixed gas containing oxygen contains at least one of oxygen and ozone, and contains at least one of nitrogen, an inert gas, a halogen gas, and a halogen compound gas; the atmosphere used for the gas oxidation is oxygen, ozone, or a mixed gas containing oxygen, the temperature is from room temperature to 2000°C, and the time is 10 seconds to 1 month, wherein the mixed gas containing oxygen contains at least one of oxygen and ozone, and contains at least one of nitrogen and an inert gas; the solution used for the chemical solution oxidation is hydrogen peroxide, deionized water, or other oxygen-containing solutions, the temperature is from room temperature to 300°C, and the time is 10 seconds to 1 hour, wherein the other oxygen-containing solutions include aqueous solutions of oxygen and aqueous solutions of ozone.

5. The epitaxial method according to claim 1, characterized in that: In steps A2 and B4, the Al source used for physical vapor deposition of AlN is an Al target, the N source is nitrogen, the deposition temperature is room temperature to 1000° C., and the deposition thickness is 10 nm to 10 μm.

6. The epitaxial method according to claim 1, characterized in that: In steps A2 and B4, oxygen is introduced during the entire or partial time of the physical vapor deposition of AlN, and / or, the sample is subjected to high temperature annealing after AlN deposition.

7. The epitaxial method according to claim 6, characterized in that: In steps A2 and B4, the flow rate of oxygen introduced during the physical vapor deposition of AlN is 0.1 sccm~10 sccm; the temperature of high-temperature annealing of the sample after AlN deposition is 100℃~2000℃.

8. The epitaxial method according to claim 1, characterized in that: In steps A3 and B5, the in-situ high temperature and low pressure nitrogen treatment of the sample refers to the high temperature and low pressure nitrogen treatment in the chamber of the equipment used in the subsequent growth process, the temperature is 100℃~1500℃, the pressure is 10 -11 mbar ~ 10 2 mbar, the chamber atmosphere is nitrogen, ammonia or a nitrogen-containing mixed gas, and the processing time is 5 min to 300 min, wherein the nitrogen-containing mixed gas is a mixed gas of nitrogen and / or ammonia and hydrogen, and the volume proportion of nitrogen and / or ammonia is greater than 40%.

9. The epitaxial method according to claim 1, characterized in that: In steps A4, A6, B1 and B6, the prepared metal-polarity III-nitride devices are semiconductor devices including power electronic devices, radio frequency electronic devices, optoelectronic devices, or are device structures of fully vertical devices on the surface.

10. A double-sided metallic polarity III-nitride material or device prepared by the epitaxial method according to any one of claims 1 to 9.

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