Single-carrier photodiode, preparation method thereof and detection chip

Abstract

The invention provides a photodiode and a preparation method thereof, and a detection chip, and the photodiode of one embodiment comprises a substrate which is made of SiC; the epitaxial layer is combined with the substrate in a bonding mode; the electrode is formed on one side, far away from the substrate, of the epitaxial layer; and the heat dissipation substrate is bound with the electrode. According to the photodiode provided by the embodiment of the invention, the substrate which is bonded with the epitaxial layer and made of the SiC material is provided and is matched with the inverted heat dissipation substrate, so that the heat dissipation capability of the single-carrier photodiode is effectively improved, and the output radio frequency power is improved.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology. More specifically, it relates to a single-carrier photodiode, a method for fabricating the same, and a detection chip. Background Technology

[0002] A photodiode is a semiconductor optical device that converts input light into electric current using the photoelectric effect. Based on their operating wavelength, photodiodes are primarily made of materials such as silicon (Si), germanium (Ge), and indium gallium arsenide (InGaAs). The common communication windows in fiber optic communication systems are the O-band (corresponding to wavelengths of 1260nm-1360nm) and the C-band (1530nm-1565nm). Indium gallium arsenide has a spectral sensing range that covers the common wavelengths of fiber optic communication systems and exhibits high absorption. Therefore, photodiodes based on indium gallium arsenide are widely used in fiber optic communication systems. Furthermore, because only lattice-matched materials can be epitaxially grown, and because the lattice matching between indium gallium arsenide and indium phosphide (InP) can be achieved by adjusting the proportion of indium in the indium material, the epitaxial layer of indium gallium arsenide photodiodes is generally grown on an InP substrate.

[0003] Commonly used epitaxial layer structures for photodiodes include PIN, avalanche, single-carrier, and improved single-carrier structures (hereinafter collectively referred to as single-carrier structures). Compared to the traditional PIN structure, the single-carrier structure significantly improves the bandwidth and output RF power of the photodiode. The main factors affecting the output power of a single-carrier photodiode are the magnitude of the applied reverse bias voltage, the space charge effect, and the chip's own heat dissipation capability.

[0004] When light is incident, a single-carrier photodiode with an externally reverse-biased voltage generates a photocurrent, thus continuously producing Joule heat. The higher the voltage, the stronger the output current, and the greater the heat generated. Typically, to achieve high output RF power, the single-carrier photodiode needs to operate in a higher reverse-bias region. High bias voltage and high output current cause the single-carrier photodiode to generate a significant amount of heat. The operating temperature of a single-carrier photodiode directly affects its lifespan. Prolonged overheating can even damage the chip, shortening its lifespan and reducing its reliability. Therefore, effective heat dissipation is indispensable for maintaining chip stability and improving its output RF power.

[0005] To improve the heat dissipation capability of single-carrier photodiodes, a common approach is to flip-chip bond the single-carrier photodiode chip to a high thermal conductivity heat dissipation substrate using metal bonding. However, the thermal conductivity of the InP substrate material is only 0.68 W·cm⁻¹. -1 ·k -1 InP is a material with poor heat dissipation capabilities. Although some of the Joule heat generated by the applied bias voltage and illumination can dissipate through the heat dissipation substrate, some still enters the InP substrate. Due to the insufficient thermal conductivity of InP, this heat cannot diffuse rapidly within the InP material. This inability to diffuse rapidly has become a significant factor limiting further improvements in the output RF power of single-carrier photodiodes. Summary of the Invention

[0006] To solve the above problems, the present disclosure adopts the following technical solution: The first aspect of this disclosure provides a single-carrier photodiode, comprising: The substrate is made of SiC. Epitaxial layer bonded to the substrate via bonding method; Electrodes formed on the side of the epitaxial layer away from the substrate; and A heat dissipation substrate bonded to the electrodes.

[0007] Optionally, the bonding method can be direct bonding or bonding via a transition layer.

[0008] Optionally, the epitaxial layer includes a P-type ohmic contact layer, a P-type absorber layer, an N-type collector layer, and an N-type ohmic contact layer sequentially stacked on the substrate; or the epitaxial layer includes an N-type ohmic contact layer, an N-type collector layer, a P-type absorber layer, and a P-type ohmic contact layer sequentially stacked on the substrate.

[0009] Optionally, the P-type absorber layer is a P-type doped InGaAs material or a material that matches the InP lattice.

[0010] Optionally, the substrate material is selected from one of 3C-type SiC, 4H-type SiC, and 6H-type SiC, and / or The material of the heat dissipation substrate is selected from diamond, SiC and AlN.

[0011] Optionally, the thermal conductivity of the substrate at room temperature is greater than 1 W·cm. -1 ·k -1 .

[0012] A second aspect of this disclosure provides a method for fabricating the single-carrier photodiode described above, comprising: An epitaxial material layer is formed on a temporary substrate, the material of which is InP; The epitaxial material layer is bonded to the substrate from the surface away from the temporary substrate by a bonding method; Remove the temporary substrate; Patterning the epitaxial material layer to form an epitaxial layer; An electrode is formed on the side of the epitaxial layer away from the substrate; and Electrodes are bonded to a heat dissipation substrate to form a single-carrier photodiode.

[0013] Optionally, forming an epitaxial material layer on a temporary substrate further includes: Forming a blocking layer for removing the temporary substrate; An epitaxial material layer is formed on the blocking layer. Removing the temporary substrate further includes: The temporary substrate is removed by etching, based on the blocking effect of the blocking layer.

[0014] A third aspect of this disclosure provides a method for fabricating a single-carrier photodiode as described above, comprising: The temporary substrate is bonded to the substrate by bonding, and the material of the temporary substrate is InP. Thinning of the temporary substrate; An epitaxial material layer is grown on the surface of the thinned temporary substrate away from the substrate; An epitaxial layer is formed by patterning an epitaxial material layer and a thinned temporary substrate; An electrode is formed on the side of the epitaxial layer away from the substrate; and Electrodes are bonded to a heat sink substrate to form a single-carrier photodiode.

[0015] A fourth aspect of this disclosure provides a detector chip, comprising: A single-carrier photodiode as described above, or At least two single-carrier photodiodes as described above, with the epitaxial layers of each single-carrier photodiode formed on the same substrate and electrically isolated, and an electrode of one of the at least two single-carrier photodiode devices serving as an electrode of a detector chip.

[0016] The beneficial effects of this disclosure are as follows: This disclosure addresses existing problems by providing a single-carrier photodiode, its fabrication method, and a detection chip. The photodiode chip provided in this application utilizes a SiC substrate bonded to an epitaxial layer, coupled with a flip-chip bonding heat dissipation substrate bonded by metal. This creates a highly efficient bidirectional heat dissipation structure between the high thermal conductivity substrate and the heat dissipation substrate, effectively improving the heat dissipation capacity of the single-carrier photodiode and thus increasing its output RF power, demonstrating broad application prospects. Attached Figure Description

[0017] The specific embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0018] Figure 1 A schematic cross-sectional view of a single-carrier photodiode according to an embodiment of the present disclosure is shown; Figure 2 A schematic cross-sectional view of a single-carrier photodiode according to another embodiment of the present disclosure is shown; Figure 3 A schematic cross-sectional view of a single-carrier photodiode according to another embodiment of the present disclosure is shown; Figure 4 This diagram shows a thermal power simulation comparison between a single-carrier photodiode according to an embodiment of the present disclosure and a photodiode device of the related art; and Figures 5 to 9 A schematic process flow diagram illustrating a method for fabricating a single-carrier photodiode device according to an embodiment of the present disclosure is shown. Detailed Implementation

[0019] To more clearly illustrate this disclosure, the following description, in conjunction with embodiments and accompanying drawings, further clarifies the subject matter. Similar components in the drawings are indicated by the same or similar reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of this disclosure. It should be noted that the ordinal numbers such as “first,” “second,” and “third” in this disclosure are not intended to specify a specific order, but only to distinguish the various parts.

[0020] In this disclosure, expressions such as “on…”, “formed on…”, and “set on…” can indicate that one layer is directly formed or set on another layer, or that one layer is indirectly formed or set on another layer, meaning that there are other layers between the two layers.

[0021] To solve the above technical problems, refer to Figure 1 As shown, an embodiment of this disclosure provides a single-carrier photodiode, comprising: Substrate 101, the material of substrate 101 is SiC; Epitaxial layer 103 bonded to substrate 101 by bonding method; An electrode 105 is formed on the side of the epitaxial layer 103 away from the substrate 101; and A heat dissipation substrate 107 is bonded to the electrode 105.

[0022] It should be noted that in this article, when there is no need to distinguish, the designation "105" is used to refer to the general term for electrodes.

[0023] certainly, Figure 1 This application is not intended to limit the specific shape or number of the first electrode 105-1, but rather to illustrate the functional difference between it and the second electrode 105-2. Other forms of electrode structures are also protected under this application.

[0024] In this embodiment, a single-carrier photodiode is provided. By providing a substrate of SiC material bonded to the epitaxial layer and flip-chip bonding it to a heat dissipation substrate, a highly thermally conductive substrate and a heat dissipation substrate are formed to form an efficient bidirectional heat dissipation structure, which effectively improves the heat dissipation capability of the single-carrier photodiode and thus improves the output RF power.

[0025] The structural advantages of the single-carrier photodiode in this disclosure will be described in detail below with specific examples.

[0026] In a specific example, refer to Figure 2 As shown in the figure, a single-carrier photodiode 1 according to an embodiment of the present disclosure is illustrated.

[0027] It should be noted that the thickness of the epitaxial layer has been exaggerated in this figure to illustrate the layer structure and improve visibility. In actual device structures, the thickness of the epitaxial layer should be as shown. Figure 1 The thickness shown is generally much smaller than that of the substrate 101 and the heat dissipation substrate 107. Furthermore, those skilled in the art will understand that the epitaxial layer can be a single film or a composite film composed of multiple film layers.

[0028] like Figure 2 As shown, the single-carrier photodiode 1 includes a substrate 101, an epitaxial layer 103-1, an electrode 105 formed on the side of the epitaxial layer 103-1 away from the substrate 101, and a heat dissipation substrate 107 bonded to the electrode 105. The substrate 101 is made of SiC, and the substrate 101 and the epitaxial layer 103-1 are bonded together.

[0029] The inventors discovered in their experiments that when using conventional deposition processes to bond high thermal conductivity materials to epitaxial wafers, the desired high thermal conductivity heat dissipation effect cannot be achieved, and the thermal conductivity at room temperature is typically far below 1 W·cm⁻¹. -1 ·k -1 However, when using direct material growth processes, the growth temperature of materials with high thermal conductivity typically exceeds 1000℃, which is beyond the temperature tolerance range of InP and InGaAs materials.

[0030] However, bonding methods, especially direct bonding, have high requirements for the coefficient of thermal expansion between the bonding materials. When materials with large differences in the coefficient of thermal expansion are bonded together, cracking will always occur in subsequent high-temperature processing, thus affecting the overall yield of the process.

[0031] After extensive research, simulation, and experimentation, the inventors discovered that among many high thermal conductivity substrate materials, the thermal expansion coefficient of SiC is close to that of InP and InGaAs. Therefore, when the SiC substrate 101 is bonded to the epitaxial layer 103-1 of InP and InGaAs using a bonding method, the wafer will not break due to the large difference in thermal expansion coefficients during subsequent high-temperature processes, such as high-temperature annealing and flip-chip bonding, thus ensuring yield.

[0032] In other words, by using bonding to combine the SiC substrate 101 with the epitaxial layer 103-1, there is no need to worry about the thermal mismatch between the substrate material and the epitaxial layer material, thus ensuring the product yield; at the same time, it ensures that the formed device can achieve high thermal conductivity.

[0033] Optionally, the bonding method includes direct bonding and bonding via a transition layer. That is, the epitaxial layer 103-1 can be bonded to the substrate 101 by direct bonding, or the epitaxial layer 103-1 can be bonded to the substrate 101 via a transition layer.

[0034] When a transition layer is used to bond the SiC substrate 101 to the epitaxial layer 103-1, the thickness of the transition layer should be in the nanometer range. This allows for the utilization of the advantages of SiC material to achieve high thermal conductivity and high product yield. The transition layer can be made of silicon or alumina, which are commonly used transparent materials in the O-band and C-band optical communication fields.

[0035] When the SiC substrate 101 is bonded to the epitaxial layer 103-1 using a direct bonding method, the SiC substrate 101 and the epitaxial layer 103-1 can directly form contact, thereby achieving a good heat dissipation effect. At the same time, it can effectively take advantage of the fact that the thermal expansion coefficient of SiC material is close to that of InP and InGaAs materials. In subsequent high-temperature processes, wafer breakage will not occur due to excessive differences in thermal expansion coefficients, thus ensuring yield.

[0036] Optionally, the thermal conductivity of the single-carrier photodiode in this embodiment of the present disclosure is greater than 1 W·cm at room temperature. -1 ·k -1 .

[0037] Furthermore, the thermal conductivity of SiC materials is significantly higher than that of InP materials. For example, the thermal conductivity of 3C-type SiC material is 3.6 W·cm⁻¹. -1 ·k -1 The thermal conductivity of 4H-type SiC material is 3.7 W·cm. -1 ·k -1 The thermal conductivity of 6H-type SiC material is 4.9 W·cm. -1 ·k -1 Regardless of which type of SiC material is chosen as the substrate 101, its thermal conductivity is far higher than that of the material with a thermal conductivity of only 0.68 W·cm. -1 ·k -1 The InP material is used. Of course, those skilled in the art will understand that this disclosure is not intended to limit the types of SiC materials. Other types of high thermal conductivity materials besides those listed above are also possible. As long as the material has a coefficient of thermal expansion close to that of InP, thus enabling it to be bonded to the epitaxial layer 103-1 by direct bonding, and simultaneously has a thermal conductivity much higher than that of InP.

[0038] Continue to refer to Figure 2 As shown, the single-carrier photodiode 1 includes an electrode 105 disposed on the side of the epitaxial layer 103-1 away from the substrate 101, and a heat dissipation substrate 107 disposed on the side of the electrode 105 away from the substrate 101 and bonded to the electrode 105. The heat dissipation substrate 107 and the electrode 105 can be connected by metal flip-chip bonding. Those skilled in the art will understand that the heat dissipation substrate 107 is also provided with metal pads corresponding one-to-one with the electrode 105, thereby enabling the connection between the electrode 105 and the metal pads.

[0039] The heat dissipation substrate 107 is made of a material with high thermal conductivity. For example, the material of the heat dissipation substrate 107 can be selected from diamond, SiC, and AlN. Of course, this disclosure is not limited to this; other materials with high thermal conductivity are also acceptable, as long as they can achieve electrical connection with the electrode 105 and excellent heat dissipation performance through a bonding process.

[0040] With the above configuration, the single-carrier photodiode 1 of this embodiment has a high thermal conductivity substrate 101 bonded to the epitaxial layer 103 on one side, while the electrode 105 on the other side is flip-chip bonded to the heat dissipation substrate 107. When the photodiode 1 operates under a reverse bias voltage, part of the heat generated can be diffused away through the heat dissipation substrate 107 via the outer casing, and the other part can be rapidly diffused within the high thermal conductivity substrate, thereby achieving good heat dissipation and significantly improving the heat dissipation capability of the single-carrier photodiode 1, thereby increasing its output RF power.

[0041] Furthermore, it should be noted that the direct contact heat conduction achieved by bonding the SiC substrate 101 to the epitaxial layer 103-1 is significantly better than the heat conduction effect achieved by bonding through a transition layer.

[0042] Continue to refer to Figure 2 As shown, in this example, the epitaxial layer 103-1 includes: a P-type ohmic contact layer 113-1, a P-type absorber layer 123, an N-type collector layer 133, and an N-type ohmic contact layer 143-1 sequentially stacked on the substrate 101.

[0043] The material of the p-type ohmic contact layer 113-1 can be p-type doped InGaAs, and the doping concentration can be, for example, [missing information]. The order of magnitude; the material of the p-type absorber layer 123 can be p-type doped InGaAs, with a doping concentration, for example, of [missing information]. The material of the N-type collector layer 133 can be an N-type doped InP material, with a doping concentration of, for example, . The material for the N-type ohmic contact 143-1 can be N-type doped InP material, with a doping concentration of, for example, Order of magnitude. P-type doped materials can be, for example, Zn, and N-type doped materials can be, for example, Si.

[0044] It should be noted that the above doping concentrations are merely illustrative and not intended to be limiting; the specific doping concentration depends on the design specifications of the specific device. The P-type absorber layer 123 can also be a material that matches the InP lattice, which will not be elaborated here.

[0045] Optionally, refer to Figure 2As shown, electrode 105 includes a first electrode 105-1 and a second electrode 105-2. The epitaxial layer 103-1 is as follows... Figure 2 In the structure shown, the first electrode 105-1, located on the side of the P-type ohmic contact layer 113-1 away from the substrate 101, is the anode. A P-type ohmic contact layer 113-1 can be disposed between the epitaxial layer 103-1 and the first electrode 105-1. The second electrode 105-2 is located on the side of the epitaxial layer 103-1 away from the substrate 101. An N-type ohmic contact layer 143-1 can be disposed between the epitaxial layer 103-1 and the second electrode 105-2, which is the cathode. Although not shown, the first electrode 105-1 can form an ohmic contact with the P-type ohmic contact layer 113-1 through a metal conductive structure extending to the P-type ohmic contact layer 113-1, and the second electrode 105-2 can form an ohmic contact with the N-type ohmic contact layer 143-1 through a metal conductive structure extending to the N-type ohmic contact layer 143-1. The metal conductive structure can be, for example, a metal pillar or a metal plating, etc., and is not limited here.

[0046] In order to ensure good ohmic contact between the P-type ohmic contact layer 113-1 and the N-type ohmic contact layer 143-1 and the corresponding electrode, an ohmic contact metal layer may also be formed between the P-type ohmic contact layer 113-1 and the N-type ohmic contact layer 143-1 and the corresponding electrode, which will not be elaborated here.

[0047] In another alternative embodiment, refer to Figure 3 As shown in the figure, another specific example of a single-carrier photodiode 1' is illustrated. The main difference between single-carrier photodiode 1' and single-carrier photodiode 1 lies in the epitaxial layer and electrodes; other device structures are similar. Figure 2 The structures and functions of the embodiments shown are similar, and similar parts will not be described again here.

[0048] Reference Figure 3 As shown, the epitaxial layer 103-2 includes: an N-type ohmic contact layer 113-2, an N-type collection layer 133, a P-type absorption layer 123, and a P-type ohmic contact layer 143-2, which are sequentially stacked on the substrate 101.

[0049] It should be noted that the thickness of the epitaxial layer has been exaggerated in this figure to illustrate the layer structure and improve visibility. In actual device structures, the thickness of the epitaxial layer should be as shown. Figure 1 The thickness shown is much smaller than that of the substrate 101 and the heat dissipation substrate 107.

[0050] The material of the N-type ohmic contact 113-2 can be N-type doped InP material, with a doping concentration of, for example, . Order of magnitude; the material of the N-type collector layer 133 can be N-type doped InP material, with a doping concentration of, for example, The material of the p-type absorber layer 123 can be p-type doped InGaAs, with a doping concentration of, for example, [missing information]. The material of the p-type ohmic contact layer 143-2 can be p-type doped InGaAs, with a doping concentration of, for example, [missing information]. Order of magnitude. P-type doped materials can be, for example, Zn, and N-type doped materials can be, for example, Si.

[0051] It should also be noted that the doping concentrations mentioned above are merely illustrative and not intended to be limiting; the specific doping concentration depends on the design specifications of the specific device. The p-type absorber layer 123 can also be a material that matches the InP lattice, which will not be elaborated here.

[0052] Specifically, electrode 105 includes a first electrode 105-1' and a second electrode 105-2'. The epitaxial layer 103-1 is as follows... Figure 2 In the structure shown, the first electrode 105-1' disposed on the side of the N-type ohmic contact layer 113-2 away from the substrate 101 is the cathode. Although not shown, the second electrode 105-2' can contact the P-type ohmic contact layer through a metal conductive structure extending to the P-type ohmic contact layer 143-2, thereby the second electrode 105-2' is the anode.

[0053] In order to ensure good ohmic contact between the N-type ohmic contact layer 113-2 and the P-type ohmic contact layer 143-2 and the corresponding electrode, an ohmic contact metal layer may also be formed between the N-type ohmic contact layer 113-2 and the P-type ohmic contact layer 143-2 and the corresponding electrode, which will not be elaborated here.

[0054] Figure 4 The diagram shows a thermal power simulation comparison between a single-carrier photodiode according to an embodiment of this disclosure and a single-carrier photodiode of the related art. The photodiode used for comparison is also an InGaAs-based single-carrier photodiode.

[0055] The simulation uses Ansys Lumerical software. Figure 4 As can be seen, the horizontal axis represents the chip area, with units of µm. 2 The vertical axis represents the maximum thermal power of the photodiode at thermal failure, in watts (W). The triangular dotted line in the coordinate system represents a single-carrier photodiode with an InP substrate flip-chip bonded to an AlN material heat dissipation substrate in the related art; the circular dotted line represents a single-carrier photodiode with an InP substrate flip-chip bonded to a diamond material heat dissipation substrate in the related art; and the square dotted line represents a single-carrier photodiode according to embodiments of this disclosure, where the InP substrate is replaced with a SiC material substrate by direct bonding and flip-chip bonded to a diamond material heat dissipation substrate.

[0056] In all the examples constructed in this simulation experiment, all parameters except for the structural materials of the device are the same, such as the thickness of the corresponding layer, the specific doping type and concentration, and the applied light intensity and bias voltage. In addition, based on previous test results, the thermal failure temperature of the single-carrier photodiode of the InP / InGaAs material system is set to 480K, and the thermal conductivity of the diamond heat dissipation substrate in the simulation is 15W·cm. -1 ·k -1 .

[0057] Under the above experimental conditions, simulations were conducted to compare the maximum input thermal power that each single-carrier photodiode could withstand under thermal failure conditions. (Refer to...) Figure 4 As shown, at the thermal failure temperature, the maximum thermal power capacity of the photodiode in this embodiment is significantly improved compared to conventional structures. Furthermore, the larger the chip area, i.e., the larger the substrate area, the more significant the improvement. The single-carrier photodiode in this embodiment effectively improves the heat dissipation capability of single-carrier photodiodes in the InP / InGaAs material system, thereby further enhancing its output RF power.

[0058] Another aspect of this disclosure provides a method for fabricating a photodiode according to the above embodiments, comprising: S1. An epitaxial material layer is formed on a temporary substrate, wherein the material of the temporary substrate is InP; S2. The surface of the epitaxial material layer away from the temporary substrate is bonded to the substrate by bonding method; S3, Remove the temporary substrate; S4. Patterning the epitaxial material layer to form an epitaxial layer; S5. Form the electrode on the side of the epitaxial layer away from the substrate; and S6. Bond the electrodes to the heat dissipation substrate to form a single-carrier photodiode.

[0059] The following reference Figures 5 to 9 ,by Figure 2 The fabrication method of the single-carrier photodiode shown is illustrated in detail below.

[0060] Reference Figure 5 As shown, in step S1, an epitaxial material layer 103-3 is grown on a temporary substrate 111. The material of the temporary substrate 111 is InP, and the epitaxial material layer 103-3 includes: an N-type ohmic contact material layer 143-3, an N-type collecting material layer 133-3, a P-type absorbing material layer 123-3, and a P-type ohmic contact material layer 113-3 sequentially stacked on the temporary substrate 111.

[0061] Optionally, although not shown, this step may also include forming a barrier layer on the temporary substrate; forming an epitaxial material layer on the barrier layer. This step can prevent corrosion damage to the epitaxial material layer during subsequent etching to remove the temporary substrate. The etching to remove the temporary substrate can be performed using wet etching or dry etching.

[0062] Reference Figure 6 As shown, in step S2, the surface of the epitaxial material layer 103-3 away from the temporary substrate 111 is bonded to the substrate 101 by bonding. The material of the substrate 101 is SiC. Optionally, the thickness of the substrate 101 is 500µm. Of course, this disclosure is not intended to limit it to this, and it should be understood that the larger the size of the substrate 101, the better the thermal conductivity. Optionally, the bonding method can be direct bonding or bonding via a transition layer. That is, in this step, the surface of the epitaxial material layer 103-3 away from the temporary substrate 111 is directly bonded to the substrate 101, or the surface of the epitaxial material layer 103-3 away from the temporary substrate 111 is bonded to the substrate 101 via a transition layer. The material of the transition layer can be silicon or alumina, which are transparent materials commonly used in the field of optical communication, such as O-band and C-band transparent materials. The thickness of the transition layer is on the nanometer scale, and the thinner the thickness, the better the heat dissipation effect.

[0063] Reference Figure 7 As shown, in step S3, the temporary substrate 111 is removed. Specifically, the temporary substrate 111 can be removed by wet etching or dry etching based on the blocking effect of the blocking layer.

[0064] Reference Figure 8 As shown, in step S4, an epitaxial layer 103-1 is formed by patterning the epitaxial material layer 103-3, and the epitaxial layer 103-1 constitutes the active region of a single photodiode 1.

[0065] Reference Figure 9 As shown, in step S5, an electrode 105 is formed on the epitaxial layer 103-1 away from the substrate 101. The electrode 105 includes a first electrode 105-1 and a second electrode 105-2. The first electrode 105-1 is the anode and the second electrode 105-2 is the cathode.

[0066] Then, in step S6, the electrode 105 is flip-chip bonded to the heat sink substrate 107 to form Figure 2 The single-carrier photodiode 1 shown is illustrated.

[0067] Another embodiment of the present disclosure uses a different process flow to prepare the photodiode described above, including: An epitaxial material layer is formed on a temporary substrate, the material of which is InP; Thinning of the temporary substrate; The surface of the thinned temporary substrate away from the epitaxial material layer is bonded to the substrate by a bonding method. An epitaxial layer is formed by patterning an epitaxial material layer and a thinned temporary substrate; An electrode is formed on the side of the epitaxial layer away from the substrate; and Electrodes are bonded to a heat dissipation substrate to form a single-carrier photodiode.

[0068] The difference between this method and the methods described above lies in the fact that the epitaxial layer of InP material is retained through a thinning process and used as a buffer layer in the subsequently formed epitaxial layer, which is then bonded to the SiC substrate. Optionally, the bonding method can be direct bonding or bonding via a transition layer. The transition layer material can be silicon or alumina, or other O-band and C-band transparent materials commonly used in optical communication. The thickness of the transition layer is on the nanometer scale. This application does not limit the thickness of the transition layer, but the thinner the thickness, the better the heat dissipation effect.

[0069] Optionally, this disclosure also provides another preparation scheme, which differs from the above-mentioned thinning scheme in that a mixed substrate layer of SiC and InP materials is first formed, then the InP substrate layer is thinned to form a mixed substrate, and then an epitaxial material layer is formed on the mixed substrate by epitaxial growth.

[0070] The above method, by forming a SiC material substrate bonded to the epitaxial layer and using a flip-chip heat dissipation substrate, enables the substrate with high thermal conductivity and the heat dissipation substrate to form an efficient bidirectional heat dissipation structure, effectively improving the heat dissipation capability of the single-carrier photodiode, thereby increasing the output RF power.

[0071] Based on the above combination Figure 4 The simulation results take into account that the substrate area significantly affects the heat dissipation capability of the device.

[0072] Based on the same inventive concept, embodiments of the present invention also provide a detector chip, comprising: At least two single-carrier photodiodes as described above, wherein the epitaxial layers of each single-carrier photodiode are formed on the same substrate and are electrically isolated. At least one electrode of one of the two single-carrier photodiodes described above is used as an electrode of the detector chip.

[0073] The above detector chips do not require additional manufacturing processes. During wafer dicing, each detector chip only needs to include multiple electrically isolated, independent active regions. This configuration allows for the use of active regions with excellent test output performance as functional chip pins in subsequent packaging, while others are used to increase substrate area. This approach ensures product yield and improves heat dissipation without increasing manufacturing costs, thereby enhancing the detector chip's output RF power.

[0074] The principle behind this detector chip for solving the problem is similar to that of the aforementioned single-carrier photodiode. Therefore, the implementation of this detector chip can be found in the implementation of the aforementioned single-carrier photodiode, and the repetitions will not be repeated here.

[0075] Of course, those skilled in the art should understand that the detection chip may also include a single-carrier photodiode as described above. In this case, the heat dissipation effect is reduced compared to a chip with multiple single-carrier photodiodes, which will not be elaborated here.

[0076] This disclosure addresses existing problems by providing a single-carrier photodiode, its fabrication method, and a detection chip. The single-carrier photodiode provided in this application provides a SiC substrate bonded to an epitaxial layer, which is then flip-chip bonded to a heat dissipation substrate. This allows the high thermal conductivity substrate and the heat dissipation substrate to form an efficient bidirectional heat dissipation structure, effectively improving the heat dissipation capacity of the single-carrier photodiode and thus increasing the output RF power, demonstrating broad application prospects.

[0077] Obviously, the above embodiments of this disclosure are merely examples for clearly illustrating this disclosure, and are not intended to limit the implementation of this disclosure. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all implementation methods here. Any obvious variations or modifications derived from the technical solutions of this disclosure are still within the protection scope of this disclosure.

Claims

1. A single-carrier photodiode, characterized in that, include: The substrate is made of SiC. An epitaxial layer bonded to the substrate by a bonding method; An electrode is formed on the side of the epitaxial layer away from the substrate; as well as A heat dissipation substrate bonded to the electrode.

2. The single-carrier photodiode according to claim 1, characterized in that, The bonding method is either direct bonding or bonding via a transition layer.

3. The single-carrier photodiode according to claim 1, characterized in that, The epitaxial layer includes a P-type ohmic contact layer, a P-type absorber layer, an N-type collector layer, and an N-type ohmic contact layer sequentially stacked on the substrate; or The epitaxial layer includes an N-type ohmic contact layer, an N-type collecting layer, a P-type absorbing layer, and a P-type ohmic contact layer, which are sequentially stacked on the substrate.

4. The single-carrier photodiode according to claim 3, characterized in that, The P-type absorber layer is a P-type doped InGaAs material or a material that matches the InP lattice.

5. The single-carrier photodiode according to claim 1, characterized in that, The substrate material is selected from one of 3C-type SiC, 4H-type SiC, and 6H-type SiC, and / or The material of the heat dissipation substrate is selected from diamond, SiC and AlN.

6. The single-carrier photodiode according to claim 1, characterized in that, The thermal conductivity of the substrate is greater than 1 W·cm at room temperature. -1 ·k -1 .

7. A method for fabricating a single-carrier photodiode according to any one of claims 1-6, characterized in that, include: An epitaxial material layer is formed on a temporary substrate, wherein the material of the temporary substrate is InP; The surface of the epitaxial material layer away from the temporary substrate is bonded to the substrate by a bonding method; Remove the temporary substrate; The epitaxial layer is formed by patterning the epitaxial material layer; The electrode is formed on the epitaxial layer on the side away from the substrate; as well as The electrode is bonded to the heat dissipation substrate to form the single-carrier photodiode.

8. The preparation method according to claim 7, characterized in that, The formation of the epitaxial material layer on the temporary substrate further includes: Form a blocking layer for removing the temporary substrate; The epitaxial material layer is formed on the blocking layer. The removal of the temporary substrate further includes: The temporary substrate is removed by etching, based on the blocking effect of the blocking layer.

9. A method for fabricating a single-carrier photodiode according to any one of claims 1-6, characterized in that, include: The temporary substrate is bonded to the substrate by a bonding method, and the material of the temporary substrate is InP. The temporary substrate is thinned; An epitaxial material layer is grown on the surface of the thinned temporary substrate away from the substrate; The epitaxial layer is formed by patterning the epitaxial material layer and the thinned temporary substrate; The electrode is formed on the epitaxial layer on the side away from the substrate; as well as The electrode is bonded to the heat dissipation substrate to form the single-carrier photodiode.

10. A detector chip, characterized in that, include: A single-carrier photodiode as described in any one of claims 1-6, or At least two single-carrier photodiodes as described in any one of claims 1-6, wherein the epitaxial layers of each single-carrier photodiode are formed on the same substrate and electrically isolated, and an electrode of one of the at least two single-carrier photodiodes serves as an electrode of the detector chip.

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