Nitride semiconductor device and method of manufacturing same
By introducing a transition substrate during the production of nitride semiconductor devices, the device is transferred to a heat dissipation substrate with high thermal conductivity, the heat dissipation problem caused by low thermal conductivity of traditional substrates is solved, and the performance and reliability of the device are significantly improved.
Patent Information
- Application Number
- CN202510030502.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-08
- Publication Date
- 2025-05-06
AI Technical Summary
Nitride semiconductor devices are poor in high voltage and high power applications due to the low thermal conductivity of the substrate material, resulting in poor heat dissipation effect, which affects the performance and reliability of the device.
By introducing a transition substrate during the fabrication of nitride semiconductor devices, the device is transferred from a conventional low thermal conductivity substrate to a high thermal conductivity heat dissipation substrate, thereby achieving efficient heat dissipation.
It effectively solves the heat dissipation problem of nitride devices in high-frequency, high-voltage, and high-power applications, and improves the performance and reliability of the devices.
Smart Images
Figure CN119943674A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of semiconductor devices, and in particular to a nitride semiconductor device and a method for manufacturing the same. Background Art
[0002] Nitride semiconductor devices have developed rapidly in recent years and are increasingly widely used in lighting, optical communications, power semiconductor devices, and medium and high frequency wireless communications. Its main advantage is the wide bandgap. Wide bandgap (bandgap width> 2.3eV) semiconductors have broad application prospects in the development of high-temperature, high-frequency, high-power microwave devices, radiation-resistant devices, ultraviolet detectors, short-wave light-emitting diodes, etc. They are urgently needed electronic devices in the fields of wireless communications, new energy, and autonomous driving.
[0003] A key factor affecting the efficiency and stability of nitride power devices is the device operating temperature. If the thermal conductivity of the substrate material used is low, the heat flow generated by the device cannot be well discharged in high-voltage and high-power devices, which will seriously reduce the performance of the device.
[0004] The fabrication of nitride semiconductor devices usually uses sapphire or silicon materials as substrates. However, the thermal conductivity of sapphire and silicon substrates is relatively low, and the heat dissipation effect is poor, which makes it difficult to meet the heat dissipation requirements of devices in high-voltage, high-frequency, and high-power applications. Therefore, in order to prepare high-performance nitride high-power devices, it is urgent to transfer nitride semiconductor devices to substrates with high thermal conductivity to improve the heat dissipation of the chip and enhance the performance and reliability of the device. Summary of the invention
[0005] The present application provides a nitride semiconductor device and a method for manufacturing the same, which can solve the heat dissipation problem existing in existing power devices. The technical solution is as follows:
[0006] A method for manufacturing a nitride semiconductor device, comprising:
[0007] Providing a first transition semiconductor device, the first transition semiconductor device comprising an original substrate, an epitaxial layer and an electrode layer stacked in sequence along a positive direction of a first direction;
[0008] providing a transition substrate, the transition substrate comprising a first bonding surface;
[0009] Bonding the first transition semiconductor device to the transition substrate; wherein the electrode layer corresponds to the first bonding surface;
[0010] Stripping the original substrate to obtain a second transition semiconductor device, wherein the second transition semiconductor device comprises the transition substrate, the electrode layer and the epitaxial layer which are sequentially stacked along the positive direction of the first direction;
[0011] Providing a heat dissipation substrate, the heat dissipation substrate comprising a second bonding surface;
[0012] Bonding the second transition semiconductor device to the heat dissipation substrate; wherein the epitaxial layer corresponds to the second bonding surface;
[0013] The transition substrate is peeled off to obtain the nitride semiconductor device.
[0014] In one embodiment, the specific steps of providing a first transition semiconductor device include:
[0015] providing an original substrate;
[0016] forming an epitaxial layer on the original substrate;
[0017] forming a cap layer on the epitaxial layer;
[0018] The electrode layer is formed on the cap layer.
[0019] In one of the embodiments, when the original substrate is configured as either silicon or sapphire, before forming the epitaxial layer on the original substrate, the method further includes:
[0020] A first buffer layer is formed on the original substrate.
[0021] In one embodiment, forming an electrode layer on the cap layer comprises:
[0022] forming a cathode metal layer on the cap layer;
[0023] An anode metal layer is formed on the cap layer; wherein,
[0024] The cathode metal layer and the anode metal layer are arranged on the cap layer at intervals.
[0025] In one embodiment, forming an anode metal layer on the cap layer comprises:
[0026] The side of the anode metal layer close to the original substrate contacts the surface of the epitaxial layer through the cap layer; or
[0027] The side of the anode metal layer close to the original substrate passes through the cap layer and at least partially extends into the epitaxial layer.
[0028] In one embodiment, providing the first transition semiconductor device further comprises:
[0029] A passivation layer is formed on the electrode layer; wherein the passivation layer exposes at least a portion of the electrode layer.
[0030] In one embodiment, after peeling off the original substrate, the method comprises:
[0031] A first metal layer is formed on the exposed surface of the epitaxial layer.
[0032] In one embodiment, before forming the first metal layer on the exposed surface of the epitaxial layer, the method includes:
[0033] A first adhesion layer is formed on the surface of the epitaxial layer, and the first metal layer is formed on the first adhesion layer.
[0034] In one embodiment, providing a heat dissipation substrate specifically includes:
[0035] A second metal layer is formed on the second bonding surface of the heat dissipation substrate.
[0036] In one embodiment, before forming the second metal layer on the second bonding surface, the method includes:
[0037] A second adhesive layer is formed on the second bonding surface of the heat dissipation substrate, and the second metal layer is formed on the second adhesive layer.
[0038] In one embodiment, bonding the first transition semiconductor device to the transition substrate specifically includes:
[0039] A first adhesive layer is prepared on the first bonding surface of the transition substrate, and the electrode layer and the epitaxial layer on the original substrate are bonded to the transition substrate through the first adhesive layer.
[0040] The present application also provides a nitride semiconductor device, which includes a heat dissipation substrate, a bonding layer, an epitaxial layer, a cap layer, an electrode layer and a passivation layer which are sequentially stacked in a direction perpendicular to the device.
[0041] In one embodiment, the bonding layer includes a second adhesion layer, a second metal layer, a first metal layer and a first adhesion layer stacked in sequence in a direction perpendicular to the device, wherein:
[0042] The first metal layer and the second metal layer are made of the same material.
[0043] In one embodiment, the first metal layer and the second metal layer can be configured as a single-layer structure or a multi-layer structure; and / or
[0044] The thickness of the first metal layer and the second metal layer are both in the range of 1-5 μm; and / or
[0045] The thickness range of the first adhesive layer and the second adhesive layer is
[0046] In one embodiment, the first metal layer and the second metal layer are both made of any one or more metals selected from titanium, titanium-tungsten alloy, nickel, silver, aluminum, and gold; and / or
[0047] The first adhesion layer and the second adhesion layer are both made of any one metal selected from titanium and titanium-tungsten alloy.
[0048] In one embodiment, the heat dissipation substrate is made of metal or ceramic; and / or
[0049] The thickness of the heat dissipation substrate ranges from 50 to 2000 μm.
[0050] The technical solution provided by the embodiments of the present application may include the following beneficial effects: the present application introduces a transition substrate in the process of manufacturing nitride devices, and uses the transition substrate to transfer the semiconductor device from the original substrate to the heat dissipation substrate, so that the device can directly use the heat dissipation substrate with higher thermal conductivity as a substrate for heat dissipation, thereby meeting the heat dissipation requirements of nitride devices in high-frequency, high-voltage, and high-power applications, and improving the performance and reliability of the chip.
[0051] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0053] Figure 1 FIG. 4 is a schematic diagram of a method for manufacturing a nitride semiconductor device according to an embodiment of the present application.
[0054] Figure 2 It is a partial structural schematic diagram of a first transition semiconductor device according to an embodiment of the present application at a certain viewing angle.
[0055] Figure 3 It is a structural schematic diagram of the preparation process of the cathode metal layer according to one embodiment of the present application.
[0056] Figure 4 It is a structural schematic diagram of the preparation process of the anode metal layer according to one embodiment of the present application.
[0057] Figure 5 It is a schematic structural diagram of an electrode layer of an embodiment of the present application at a certain viewing angle.
[0058] Figure 6It is a structural schematic diagram of the preparation process of the passivation layer according to one embodiment of the present application.
[0059] Figure 7 This is a structural schematic diagram of the bonding process between the second semiconductor device and the transition substrate according to an embodiment of the present application.
[0060] Figure 8 This is a diagram showing the preparation state of the first metal layer according to an embodiment of the present application.
[0061] Fig. 9 This is a diagram showing the preparation state of the second metal layer according to an embodiment of the present application.
[0062] Fig.10 It is a structural schematic diagram of the preparation process of a nitride semiconductor device according to an embodiment of the present application.
[0063] Description of reference numerals:
[0064] 1. First transition semiconductor device; 10. Original substrate; 11. Epitaxial layer; 12. Electrode layer; 120. Cathode metal layer; 121. Anode metal layer; 13. Cap layer; 14. First buffer layer; 15. Passivation layer; 16. First metal layer;
[0065] 2. A second transition semiconductor device; 20. A transition substrate;
[0066] 30. heat dissipation substrate; 31. second metal layer;
[0067] 40. First adhesive layer. DETAILED DESCRIPTION
[0068] Compared with the bandgap width of silicon of 1.12eV, the bandgap widths of commonly used compound semiconductors are: gallium arsenide 1.43eV, indium phosphide 1.35eV, silicon carbide 3.25eV, gallium nitride 3.44eV, gallium oxide 4.8eV, diamond 5.57eV, aluminum nitride 6.2eV. Among them, aluminum nitride material has the largest bandgap width and direct band gap in III-V compound semiconductors. With the progress of aluminum nitride material growth and doping technology, aluminum nitride materials with excellent properties such as high thermal conductivity, high resistivity, strong breakdown field, and small dielectric constant will be used in high-temperature, high-frequency and high-power semiconductor devices.
[0069] Traditional aluminum nitride (AlN) epitaxial layers can be made on different substrates. Sapphire is a widely used substrate material based on crystal quality and cost considerations. However, the thermal conductivity of sapphire is very low, between 25-40W / mK. In comparison, the thermal conductivity of AlN material can reach more than 300W / mK. The thermal conductivity of aluminum nitride ceramic substrates ranges from 170-320W / m·K. Common metal thermal conductivities are: copper 400W / mk, silver 430W / mk, gold 300W / mk, aluminum 240W / mK, all of which are much higher than the thermal conductivity of sapphire.
[0070] As described in the background art, the traditional substrate cannot meet the heat dissipation requirements, which will cause the internal temperature of the device to rise, which not only affects the stability and reliability of the device, but also limits the further improvement of the output power of the device.
[0071] Based on this, the present application provides a nitride semiconductor device and a method for manufacturing the same, which can effectively solve the heat dissipation problem of the nitride device by transferring the device from a traditional substrate to a substrate with high thermal conductivity. It should be noted that the present application uses a method for manufacturing a semiconductor device based on aluminum nitride material, such as a Schottky barrier diode, as an example.
[0072] Reference Figure 1 The method for manufacturing a nitride semiconductor device provided in the present application includes steps S10 to S70.
[0073] Step S10: providing a first transition semiconductor device 1 .
[0074] Step 110: Reference Figure 2 , providing an original substrate 10. The original substrate 10 is generally made of any one of silicon or sapphire. When the original substrate 10 is silicon or sapphire, the thermal conductivity of the material is low and cannot meet the heat dissipation requirements of the semiconductor device.
[0075] The embodiment of the present application does not limit the size, shape and thickness of the original substrate 10, and can be designed according to actual needs. For example, the size of the original substrate 10 can be 2 to 8 inches.
[0076] Step 120: Continue to refer to Figure 2 , an epitaxial layer 11 is prepared on the original substrate 10.
[0077] In the embodiment of the present application, the material of the epitaxial layer 11 is aluminum nitride. Specifically, the preparation methods of the epitaxial layer 11 may include the following:
[0078] The first method is direct nitridation of aluminum, which is to prepare AlN single crystal by high-temperature reaction of Al and N2, or by vaporizing metal Al in N2 atmosphere.
[0079] The second method is the high nitrogen pressure solution growth method (HNPSG), which is to dissolve N atoms into liquid Al at a temperature of 1800-2000°C and a N2 pressure of about 2GPa. When the solution has a high degree of supersaturation, single crystal AlN with a wurtzite structure will be obtained.
[0080] The third method is hydride vapor phase epitaxy growth (HVPE). The main chemical reaction equation is: AlCl3+NH3=AlN+3HCl. The reaction temperature is 600-1100℃. HVPE has the advantages of fast growth rate.
[0081] The fourth method is metal organic chemical vapor deposition (MOCVD-Metal Organic Chemical Vapor Deposition), also known as metal organic vapor phase epitaxy (MOVPE-Metal Organic Vapor Phase Epitaxy). The preparation of A1N film is to use hydrogen to send metal organic compound vapor (such as trimethylaluminum) and gaseous non-metal hydride (NH3) into the reaction chamber, and then heat to decompose the compound. The overall reaction formula is as follows: Al(CH3)3+NH3=AIN+3CH4. The advantage of this method is that it can control the synthesis of atomic-level thickness films, that is, new nanomaterial films.
[0082] The fifth method is physical vapor transport growth (PVT). Also known as sublimation recondensation, the reaction process is: AlN powder is first heated and sublimated at the bottom of the crucible with a higher temperature to become gas phase AlN or Al and N2. Then, it reaches the top of the crucible with a lower temperature through gas phase transmission, and recrystallizes in N2 atmosphere to form AlN single crystal. The temperature range of the reaction process is 2100-2500℃.
[0083] In some embodiments, when the original substrate 10 is configured as either silicon or sapphire, step 120 includes the following steps.
[0084] Step 121: Continue to refer to Figure 2, a first buffer layer 14 is prepared on the original substrate 10. Preferably, the first buffer layer 14 is made of undoped high-resistance aluminum nitride. Preferably, the thickness of the first buffer layer 14 is in the range of 0.2-2 μm.
[0085] The provision of the first buffer layer 14 can reduce the influence of dislocation defects caused by lattice mismatch due to the large difference in lattice constants between the original substrate 10 and the epitaxial layer 11 (aluminum nitride), thereby ensuring the performance, yield and stability of the device.
[0086] Step 122: Continue to refer to Figure 2 , an epitaxial layer 11 is prepared on the first buffer layer 14. The material of the epitaxial layer 11 is n-type aluminum nitride. The n-type aluminum nitride can be prepared by any of the above-mentioned methods of growing single crystal aluminum nitride, and then performing n-type doping.
[0087] Specifically, doping can be accomplished by implanting oxygen or silicon atoms at a doping concentration of 10 13 -10 21 atoms / cm3. Specifically, doping can also be performed simultaneously during the growth of aluminum nitride. Exemplarily, when growing single-crystalline aluminum nitride by MOCVD, monosilane gas (SiH4) can be added to the reaction, and Si atoms are introduced into the AlN crystal to replace Al atoms to form n-type aluminum nitride. Preferably, the thickness of the n-type aluminum nitride epitaxial layer 11 ranges from 20nm to 500nm.
[0088] Step 130: Continue to refer to Figure 2 , a cap layer 13 is prepared on the epitaxial layer 11.
[0089] Exemplarily, the cap layer 13 is configured as a layer of gallium nitride (GaN). Exemplarily, the cap layer 13 is configured as an N-type doped GaN film. Preferably, the thickness of the cap layer 13 is in the range of 2-5 nm. The provision of the cap layer 13 has the advantages of preventing aluminum nitride oxidation, improving ohmic contact, reducing current collapse effect, and increasing breakdown voltage.
[0090] Step 140: preparing an electrode layer 12 on the cap layer 13. The steps specifically include the following.
[0091] Step 141 : preparing a cathode metal layer 120 on the cap layer 13 .
[0092] First, if Figure 3 As shown in part b in FIG. 8 , a photoresist 100 is coated on the cap layer 13 .
[0093] Secondly, if Figure 3 As shown in part c in FIG. 1 , the photoresist 100 is exposed and developed to form an opening area on the photoresist 100 for preparing the cathode metal layer 120 .
[0094] Then, if Figure 3 As shown in part d in FIG. 1 , metal is deposited on the photoresist 100 , the metal in the opening area is retained, and the metal outside the opening area is stripped off.
[0095] Finally, if Figure 3 As shown in part e of FIG. 1 , after the operations of degumming / cleaning / annealing, the cathode metal layer 120 is formed. The detailed steps are conventional operations in the art and will not be described in detail here.
[0096] Furthermore, during the metal deposition process, the cathode metal layer 120 is generally a combination of several metals, and an alloy is formed by high temperature annealing to reduce resistance. These metals include Ti (titanium), Al (aluminum), Ni (nickel), Pt (platinum), Au (gold) or others, which can be a single metal or a combination of multiple metals, and are usually deposited layer by layer on the cap layer 13 by metal evaporation.
[0097] Exemplarily, the cathode metal layer 120 is composed of 4 metal layers. The thickness ranges of Ti, Al, Ti, and Au are: 2-25nm, 30-300nm, 20-100nm, and 50-500nm, respectively. Preferably, the thickness of the Ti metal layer can be 25nm, the thickness of the Al metal layer can be 50nm, the thickness of the Ti metal layer can be 100nm, and the thickness of the Au metal layer can be 250nm, and the total thickness of the cathode metal layer 120 is 450nm. The cathode metal layer 120 can also be a combination and thickness of other metals, which are not specifically limited here.
[0098] Specifically, during the annealing process, the cathode metal layer 120 is annealed in an RTA (rapid thermal annealing furnace) at a temperature range of 700-900° C., preferably 800° C., in an argon or nitrogen environment for 30 seconds to 90 seconds, in order to form an ohmic contact to reduce resistance.
[0099] Specifically, the shape of the electrode in the cathode metal layer 120 can be circular, square, rectangular or other shapes. The size of the electrode can be 10 μm-500 μm. They are not listed here one by one.
[0100] Step 142 : preparing an anode metal layer 121 on the cap layer 13 .
[0101] First, if Figure 4 As shown in part a of FIG. 8 , a photoresist 100 is coated on the cap layer 13 .
[0102] Secondly, if Figure 4 As shown in part b, the photoresist 100 is exposed and developed to form an opening region for preparing an anode metal layer 121 on the photoresist 100.
[0103] Then, if Figure 4 As shown in part c in FIG. 1 , metal is deposited on the photoresist 100 , the metal in the opening area is retained, and the metal outside the opening area is stripped off.
[0104] Finally, if Figure 4 As shown in part d of FIG. 1 , after the operations of degumming / cleaning / annealing, the anode metal layer 120 is formed. The detailed steps are conventional operations in the art and will not be described in detail here.
[0105] Specifically, the anode metal layer 121 is generally made of metal with high work function, such as Pt, Ni, Au, and Ti. The work functions thereof are 5.65 eV, 5.15 eV, 5.1 eV, and 4.33 eV, respectively, in order to form a Schottky contact with the epitaxial layer 11.
[0106] It should be noted that the Schottky diode is a metal-semiconductor device made by using a noble metal as the positive electrode and an n-type semiconductor as the negative electrode, and utilizing the potential barrier formed on the contact surface of the two to have the rectifying property. Because there are a large number of electrons in the n-type semiconductor and only a very small number of free electrons in the noble metal, the electrons diffuse from the n-type semiconductor with a high concentration to the noble metal with a low concentration. As the electrons continue to diffuse from the semiconductor to the noble metal, the electron concentration on the surface of the n-type semiconductor gradually decreases, and the surface electrical neutrality is destroyed, so a potential barrier is formed, and the direction of the electric field points from the n-type semiconductor to the noble metal. However, under the action of the electric field, the electrons in the noble metal will also drift from the noble metal to the n-type semiconductor, thereby weakening the electric field formed by the diffusion motion. When a space charge region of a certain width is established, the electron drift motion caused by the electric field and the electron diffusion motion caused by different concentrations reach a relative balance, and a Schottky barrier is formed. Therefore, in this step, Pt, Ni, Au, and Ti are used as the positive electrode, and the epitaxial layer 11 is n-type aluminum nitride as the negative electrode, and the two are in contact to form a Schottky contact.
[0107] Specifically, the anode metal layer 121 may be composed of one metal layer or 2-4 metal layers. Exemplarily, the anode metal layer 121 is composed of two metal layers of Pt / Au, and the thickness of the anode metal layer 121 is in the range of 10-50nm. Exemplarily, the anode metal layer 121 is composed of two metal layers of Ni / Au, and the thickness of the anode metal layer 121 is in the range of 50-250nm.
[0108] Specifically, the anode metal layer 121 is usually made by depositing metal layer by layer on the epitaxial layer 11 (or the cap layer 13) by metal evaporation or sputtering. The shape of the electrode in the anode gold layer can be circular, square, rectangular or other shapes. The size of the electrode can be 10um-500μm. No specific limitation is given here.
[0109] In some embodiments, forming the anode metal layer 121 on the capping layer 13 may include two preparation methods.
[0110] The first type: the anode metal layer 121 is close to the original substrate 10 and contacts the surface of the epitaxial layer 11 through the cap layer 13. The specific manufacturing process is photolithography, etching the cap layer 13, degumming, photolithography, metal deposition, metal stripping, cleaning, etc. The structural diagram after the completion of the manufacturing is as follows Figure 5 As shown in part a of FIG.
[0111] The second type: the anode metal layer 121 near the original substrate 10 passes through the cap layer 13 and at least partially extends into the epitaxial layer 11. The specific manufacturing process is the same as above, except that the cap layer 13 and part of the epitaxial layer 11 need to be etched in this embodiment. The structural diagram after the manufacturing is completed is shown in FIG. Figure 5 As shown in part b.
[0112] In some embodiments, the first transition semiconductor device 1 further includes a passivation layer 15. For a specific preparation process, refer to Figure 6 .
[0113] Step 150: Reference Figure 6 In part a, a dielectric material for forming a passivation layer 15 is made on the electrode layer 12. The material of the passivation layer 15 can be any one of silicon oxide, silicon nitride or aluminum oxide. Exemplarily, the passivation layer 15 is made of silicon nitride, and the silicon nitride is prepared by PECVD (plasma enhanced chemical vapor deposition). Further, the thickness of the passivation layer 15 ranges from 10nm to 300nm.
[0114] It is worth noting that the passivation layer in this step completely covers the anode metal layer 121 and the cathode metal layer 120 .
[0115] Step 151: Figure 6 As shown in part b, a photoresist 100 is coated on the passivation layer 15 .
[0116] Step 152: Figure 6 As shown in part c, the positions where the passivation layer 15 needs to be etched are exposed and developed to form a plurality of opening areas.
[0117] Step 153: Figure 6 As shown in part d, the passivation layer 15 in the opening region is etched to expose at least a portion of the anode metal layer 121 and the cathode metal layer 120 .
[0118] Step 154: Figure 6As shown in the middle part e, the photoresist 100 is removed and cleaned. At this point, the preparation of the first transition semiconductor device 1 is completed, providing a foundation for the formation of a nitride semiconductor device with good heat dissipation effect.
[0119] Step S20: providing a transition substrate 20. The transition substrate 20 includes a first bonding surface (not shown in the figure).
[0120] Specifically, the transition substrate 20 can be configured as sapphire, glass or other materials. Further, the thickness of the transition substrate 20 ranges from 0.5 to 2 mm. Further, the size of the transition substrate 20 is the same as the size of the first transition semiconductor device 1. Alternatively, the size of the transition substrate 20 is larger than the size of the first transition semiconductor device 1.
[0121] Step S30: Figure 7 As shown in part a and part b of FIG. 1 , the first transition semiconductor device 1 is bonded to the transition substrate 20 , wherein the electrode layer 12 corresponds to the first bonding surface. Specifically, the steps are as follows.
[0122] Coating: Use a spin coater or spray coating equipment to uniformly coat the bonding glue on the first bonding surface of the transition substrate 20 to form a first glue layer 40 .
[0123] Glue baking: The glue-coated transition substrate 20 is placed in an oven or hot plate for pre-baking to remove the solvent and solidify the glue layer. After baking, the first glue layer 40 is cooled naturally or rapidly cooled using nitrogen.
[0124] Bonding: Align one side of the electrode layer 12 (also known as the passivation layer 15) of the first transition semiconductor device 1 with the first bonding surface of the transition substrate 20 to ensure accurate alignment, and then apply pressure or heat on the bonding machine to bond the first adhesive layer 40 to the first transition semiconductor device 1. The structural diagram after the completion is as follows Figure 7 As shown in part b.
[0125] Step S40: Figure 7 As shown in part c in FIG. 1 , the original substrate 10 is peeled off to obtain the second transition semiconductor device 2 .
[0126] The original substrate 10 and the epitaxial layer 11 are peeled off. Exemplarily, if the original substrate is sapphire, laser peeling technology is used for peeling, that is, a technology of using laser to peel off between the original substrate 10 and the epitaxial layer 11. This technology controls the energy and irradiation time of the laser to transmit the laser energy to the interface between the original substrate 10 and the aluminum nitride epitaxial film, causing thermal stress, thereby causing peeling between the original substrate 10 and the epitaxial layer 11. Exemplarily, if the substrate is silicon, thinning, dry or wet etching technology is used for peeling, or different combinations of thinning, dry and wet methods are used, that is, the substrate is first thinned to a certain thickness, such as 10-100um, and then the remaining silicon material is removed by dry or wet etching.
[0127] As mentioned above, for the convenience of description and understanding, the epitaxial layer 11, the cap layer 13, the electrode layer 12, the passivation layer 15 and other layers can be collectively referred to as semiconductor layers. Figure 7 In part c, the semiconductor layer is transferred from the original substrate 10 to the transition substrate 20 through steps S30 and S40 to form a second transition semiconductor device 2. Specifically, the second transition semiconductor device 2 includes a transition substrate 20, a first glue layer 40, a passivation layer 15, an electrode layer 12, a cap layer 13, an epitaxial layer 11 and a first buffer layer 14 which are sequentially stacked along the positive direction of the first direction.
[0128] In some implementations, the following steps are also included after step S40.
[0129] Step S41: Refer to Figure 8 , forming a first metal layer 16 on the surface of the exposed epitaxial layer 11. Specifically, the AlN film (epitaxial layer 11) exposed after being peeled off from the original substrate 10 is metallized.
[0130] The first metal layer 16 may be composed of one or more metals, such as Ti, TiW, Ni, Ag, Al, Au, etc. The first metal layer 16 is usually prepared by depositing metal layer by layer on the epitaxial layer 11 of the second transition semiconductor by metal evaporation or sputtering. Furthermore, before preparing the first metal layer 16, the surface of the exposed epitaxial layer 11 is treated to remove particles, contaminants, oxide layers, etc. on the surface of the epitaxial layer 11. Specifically, the surface treatment process includes plasma cleaning, ion bombardment, wet cleaning, etc., which will not be described in detail here.
[0131] In some implementations, the following steps are also included before step S41.
[0132] Step S42: Form a first adhesion layer (not shown) on the surface of the epitaxial layer 11, and form a first metal layer 16 on the first adhesion layer. Specifically, the first adhesion layer can be made of any one of Ti and TiW. The provision of the first adhesion layer can effectively prevent the first metal layer 16 from being separated from the aluminum nitride film layer (epitaxial layer 11). Specifically, the thickness of the first adhesion layer is in units of between.
[0133] In some embodiments, the total thickness of the first metal layer 16 and the first adhesion layer is in the range of 1-5 μm.
[0134] Step S50: providing a heat dissipation substrate 30, wherein the heat dissipation substrate 30 comprises a second bonding surface.
[0135] Specifically, the heat dissipation substrate 30 can be configured as a metal with a relatively high thermal conductivity such as copper, aluminum, silver, or a ceramic with a relatively high thermal conductivity. Specifically, the size of the heat dissipation substrate 30 is consistent with the size of the transition substrate 20. Specifically, the thickness of the heat dissipation substrate 30 ranges from 50 μm to 2000 μm. The specific thickness can be selected according to actual needs and is not limited here.
[0136] In some embodiments, providing the heat dissipation substrate 30 further includes the following steps.
[0137] Step S51: Refer to Fig. 9 , a second metal layer 31 is formed on the second bonding surface of the heat dissipation substrate 30. The preparation of the second metal layer 31 is roughly the same as the preparation of the first metal layer 16 in step S41, that is, the second metal layer 31 can be composed of one or more metals, such as Ti, TiW, Ni, Ag, Al, Au, etc. The second metal layer 31 is usually prepared by metal evaporation or sputtering layer by layer onto the heat dissipation substrate 30. Before preparing the second metal layer 31, the surface of the heat dissipation substrate 30 is generally treated to remove particles, contaminants, oxide layers, etc. on the surface. Surface treatment processes include plasma cleaning, ion bombardment, wet cleaning, etc.
[0138] In some implementations, the following steps are also included before step S51.
[0139] Step S52: Form a second adhesion layer on the surface (second bonding surface) of the heat dissipation substrate 30, and form a first metal layer 16 on the second adhesion layer. Specifically, the first adhesion layer can be made of any one of Ti and TiW. The second adhesion layer can effectively prevent the first metal layer 16 from being separated from the aluminum nitride film layer (epitaxial layer 11). Specifically, the thickness of the first adhesion layer is in units of between.
[0140] In some embodiments, the total thickness of the second metal layer 31 and the second adhesion layer is in the range of 1-5 μm.
[0141] Step S60: Bond the second transition semiconductor device 2 to the heat dissipation substrate 30. The specific bonding process is as follows.
[0142] S61 : accurately aligning the surface of the first metal layer 16 on the second transition semiconductor device 2 and the surface of the second metal layer 31 on the heat dissipation substrate 30 .
[0143] S62: After alignment is completed, the second transition semiconductor device 2 and the heat dissipation substrate 30 to be bonded are placed in the bonding equipment. Metal bonding needs to be performed at a specific temperature. For common metal bonding, such as Au-Si, Au-Ge, Al-Ge, etc., the temperature range is usually between 300-500°C. This temperature range ensures that the metal layer can form a good metallurgical bond at the bonding interface.
[0144] S63: During the bonding process, a certain pressure needs to be applied to ensure that the surfaces of the first metal layer 16 and the second metal layer 31 are in close contact. For metal bonding, the applied pressure is usually between 1-5 kN. This pressure helps the diffusion and mutual melting between the metal layers, thereby forming a strong connection.
[0145] S64: The bonding process also takes a certain amount of time to complete. For metal bonding, this can range from 30 minutes to 200 minutes. This length of time depends on the type of bonding material, parameters such as temperature and pressure, and the required bond strength.
[0146] In some embodiments, the first metal layer 16 and the second metal layer 31 are made of the same metal material. For example, if the metal on the surface of the epitaxial layer 11 (the first metal layer 16) is copper, the metal on the surface of the heat dissipation substrate 30 (the second metal layer 31) is also copper to achieve Cu-Cu bonding. This arrangement can improve the bonding strength and heat dissipation capability, while also improving mechanical reliability.
[0147] It should be noted that in addition to the above steps, the bonding process may also include surface preparation, cleaning, pretreatment and other steps to ensure that the bonding surface is clean, flat, and has sufficient activity to promote bonding. After bonding is completed, post-treatment, such as additional heat treatment, may be required to enhance the bond strength and electrical properties. I will not go into details here.
[0148] Step S70: peeling off the transition substrate 20 to obtain a nitride semiconductor device.
[0149] Specifically, the bonded second transition semiconductor device 2 and the heat dissipation substrate 30 are placed in a debonding device, vacuum adsorption is performed, and the hot plate is heated to a certain temperature (e.g., 100° C.-300° C.) to melt the bonding glue (the first glue layer 40), and then the transition substrate 20 is separated from the nitride semiconductor device, the nitride semiconductor device is cleaned, and the bonding glue is removed from the nitride semiconductor device. Fig.10 At this point, the semiconductor device based on aluminum nitride material is transferred to the heat dissipation substrate 30 with high thermal conductivity, which solves the heat dissipation problem of the semiconductor device and enables the semiconductor device to fully exert its performance.
[0150] Furthermore, the steps of testing, cutting, packaging, etc. of nitride semiconductor devices are all conventional techniques in the art and will not be described in detail here.
[0151] The present application also provides a nitride semiconductor device, Fig.10 The nitride semiconductor device includes a heat dissipation substrate 30, a bonding layer, an epitaxial layer 11, a cap layer 13, an electrode layer 12 and a passivation layer 15 which are sequentially stacked in a direction perpendicular to the device. The heat dissipation substrate 30 is configured as a substrate with high thermal conductivity, such as copper, aluminum, silver and other metals with relatively high thermal conductivity, or a nitride semiconductor device formed by a ceramic substrate with relatively high thermal conductivity, which has good heat dissipation effect, and has higher stability and reliability. At the same time, it also effectively improves the output power of the device and improves the mechanical properties of the epitaxial wafer.
[0152] In some embodiments, continue to refer to Fig.10 The bonding layer includes a second adhesion layer (not shown in the figure), a second metal layer 31, a first metal layer 16 and a first adhesion layer (not shown in the figure) stacked in sequence along the positive direction of the first direction. The first metal layer 16 and the second metal layer 31 are made of the same material.
[0153] In some embodiments, the first metal layer 16 and the second metal layer 31 can be configured as a single layer structure or a multilayer structure. The thickness of the first metal layer 16 and the second metal layer 31 are both in the range of 1-5 μm. The thickness of the first adhesive layer and the second adhesive layer are both in the range of
[0154] In some embodiments, the thickness range of the first metal layer 16 includes the thickness of the first adhesive layer, that is, the total thickness range of the first metal layer 16 and the first adhesive layer is 1-5 μm.
[0155] Likewise, the thickness range of the second metal layer 31 includes the thickness of the second adhesive layer, that is, the total thickness range of the second metal layer 31 and the second adhesive layer is 1-5 μm.
[0156] In some embodiments, the first metal layer 16 and the second metal layer 31 are made of any one or more metals selected from titanium, titanium-tungsten alloy, nickel, silver, aluminum, and gold.
[0157] In some embodiments, the first adhesion layer and the second adhesion layer are both made of any one metal selected from titanium and titanium-tungsten alloy.
[0158] In some embodiments, the heat dissipation substrate 30 is made of metal or ceramic. The thickness of the heat dissipation substrate 30 is in the range of 50-2000 μm.
[0159] The words "first", "second" and similar terms used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, "multiple" or "several" means two or more. Unless otherwise specified, the words "top" and / or "bottom" and similar terms are only for convenience of description and are not limited to one position or one spatial orientation.
Claims
1. A method for manufacturing a nitride semiconductor device, characterized in that: include: Providing a first transition semiconductor device, the first transition semiconductor device comprising an original substrate, an epitaxial layer and an electrode layer stacked in sequence along a positive direction of a first direction; providing a transition substrate, the transition substrate comprising a first bonding surface; Bonding the first transition semiconductor device to the transition substrate; wherein the electrode layer corresponds to the first bonding surface; Stripping the original substrate to obtain a second transition semiconductor device, wherein the second transition semiconductor device comprises the transition substrate, the electrode layer and the epitaxial layer which are sequentially stacked along the positive direction of the first direction; Providing a heat dissipation substrate, the heat dissipation substrate comprising a second bonding surface; Bonding the second transition semiconductor device to the heat dissipation substrate; wherein the epitaxial layer corresponds to the second bonding surface; The transition substrate is peeled off to obtain the nitride semiconductor device.
2. The method according to claim 1, characterized in that: The specific steps of providing the first transition semiconductor device include: providing an original substrate; forming an epitaxial layer on the original substrate; forming a cap layer on the epitaxial layer; The electrode layer is formed on the cap layer.
3. The method according to claim 2, characterized in that: When the original substrate is configured as either silicon or sapphire, before forming an epitaxial layer on the original substrate, the method further includes: A first buffer layer is formed on the original substrate.
4. The method according to claim 2, characterized in that: Forming an electrode layer on the cap layer comprises: forming a cathode metal layer on the cap layer; An anode metal layer is formed on the cap layer; wherein, The cathode metal layer and the anode metal layer are arranged on the cap layer at intervals.
5. The manufacturing method according to claim 4, characterized in that: Forming an anode metal layer on the cap layer comprises: The side of the anode metal layer close to the original substrate contacts the surface of the epitaxial layer through the cap layer; or The side of the anode metal layer close to the original substrate passes through the cap layer and at least partially extends into the epitaxial layer.
6. The method according to claim 2, characterized in that: Providing the first transition semiconductor device specifically also includes: A passivation layer is formed on the electrode layer; wherein the passivation layer exposes at least a portion of the electrode layer.
7. The manufacturing method according to claim 2, characterized in that: After peeling off the original substrate, the method comprises: A first metal layer is formed on the exposed surface of the epitaxial layer.
8. The method according to claim 7, characterized in that: Before forming a first metal layer on the exposed surface of the epitaxial layer, the method comprises: A first adhesion layer is formed on the surface of the epitaxial layer, and the first metal layer is formed on the first adhesion layer.
9. The manufacturing method according to claim 1, characterized in that: Providing a heat dissipation substrate specifically includes: A second metal layer is formed on the second bonding surface of the heat dissipation substrate.
10. The manufacturing method according to claim 9, characterized in that: Before forming the second metal layer on the second bonding surface, the method comprises: A second adhesive layer is formed on the second bonding surface of the heat dissipation substrate, and the second metal layer is formed on the second adhesive layer.
11. The manufacturing method according to claim 1, characterized in that: Bonding the first transition semiconductor device on the transition substrate specifically includes: A first adhesive layer is prepared on the first bonding surface of the transition substrate, and the electrode layer and the epitaxial layer on the original substrate are bonded to the transition substrate through the first adhesive layer.
12. A nitride semiconductor device, characterized in that: The nitride semiconductor device comprises a heat dissipation substrate, a bonding layer, an epitaxial layer, a cap layer, an electrode layer and a passivation layer which are sequentially stacked in a direction perpendicular to the device.
13. The nitride semiconductor device according to claim 12, wherein: The bonding layer includes a second adhesion layer, a second metal layer, a first metal layer and a first adhesion layer which are sequentially stacked in a direction perpendicular to the device, wherein: The first metal layer and the second metal layer are made of the same material.
14. The nitride semiconductor device according to claim 13, characterized in that: The first metal layer and the second metal layer can be configured as a single-layer structure or a multi-layer structure; and / or The thickness of the first metal layer and the second metal layer are both in the range of 1-5 μm; and / or The thickness range of the first adhesive layer and the second adhesive layer is 15. The nitride semiconductor device according to claim 14, characterized in that: The first metal layer and the second metal layer are both made of any one or more metals selected from titanium, titanium-tungsten alloy, nickel, silver, aluminum, and gold; and / or The first adhesion layer and the second adhesion layer are both made of any one metal selected from titanium and titanium-tungsten alloy.
16. The nitride semiconductor device according to any one of claims 12 to 15, characterized in that: The heat dissipation substrate is made of metal or ceramic; and / or The thickness of the heat dissipation substrate ranges from 50 to 2000 μm.