An integrated device of a gan laser and a gan hemt and a method of manufacturing the same

Abstract

The embodiment of the application discloses an integrated device of GaN laser and GaN HEMT and a preparation method thereof. The integrated device comprises a substrate, a laser layer structure and a HEMT layer structure formed on the substrate, an isolation groove arranged between the laser layer structure and the HEMT layer structure, a passivation layer covering the laser layer structure, the HEMT layer structure and the isolation groove, and a planarization layer formed on the passivation layer. The laser layer structure comprises an N-type GaN contact layer, a multilayer InGaN quantum well active region and a P-type GaN contact layer formed in sequence. The HEMT layer structure comprises a doped GaN buffer layer, a GaN channel layer and an AlGaN barrier layer formed in sequence. The laser layer structure further comprises a step formed by the N-type GaN contact layer, an N-type electrode formed on the step, and a P-type electrode formed on the P-type GaN contact layer. The HEMT layer structure further comprises a drain electrode and a source electrode formed on the AlGaN barrier layer, and a gate electrode formed between the drain electrode and the source electrode. The surface of the planarization layer is electrically connected to an N-type electrode wiring through a via, and a connection wiring electrically connected to the P-type electrode of the laser and the source electrode of the HEMT.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microelectronics. More particularly, it relates to an integrated device of GaN laser and GaN HEMT and a preparation method thereof. BACKGROUND

[0002] Gallium nitride (GaN) is a typical representative of the third generation of semiconductor materials, which has the characteristics of wide band gap, high breakdown field strength, fast saturated electron drift speed, large thermal conductivity, small dielectric constant, strong radiation resistance and good chemical stability, and is very suitable for the preparation of ultraviolet detector devices, light-emitting devices, high-power devices and microwave power devices. GaN electronic devices are mainly high electron mobility transistors (HEMTs). In the heterojunction formed by GaN and aluminum gallium nitride (AlGaN) with a wider band gap, the polarization electric field significantly modulates the distribution of energy bands and charges, forming a two-dimensional electron gas (2DEG) with high mobility characteristics at the AlGaN / GaN interface. The 2DEG channel is more conducive to obtaining strong current driving capability and microwave power amplification capability than the bulk electron channel. Therefore, using GaN HEMT as a driving switch device not only has the advantage of extremely high switching speed of about several nanoseconds, but also has the advantages of large power capacity, high thermal conductivity, strong high-temperature resistance and radiation resistance.

[0003] GaN laser is an important optoelectronic device. Laser based on GaN material system (GaN, InGaN and AlGaN) expands the wavelength of semiconductor laser to the visible and ultraviolet spectral range, which has great application prospects in the fields of display, lighting, medical treatment, communication and military. Among them, blue-green light with a wavelength between 470nm and 540nm has a low absorption coefficient in seawater, so it has a large penetration ability, and its propagation distance can reach more than 600 meters. In addition, GaN laser can realize Gbps level data transmission rate, and this high speed advantage will ensure many real-time applications, and has wide application prospects in deep sea exploration, submarine communication and detection, etc.

[0004] Using the method of hetero-integration, GaN HEMT and GaN laser are monolithically integrated, and the high voltage and high speed characteristics of HEMT are used to control the switching of the laser to realize high-speed signal modulation of the laser. This integration method not only effectively reduces the system size and process cost, but also improves the voltage resistance and response performance of the system, and is also beneficial to the stability and safety of the overall system.

[0005] The existing monolithic integrated III-nitride HEMT and GaN laser fabrication method has obvious disadvantages. The GaN HEMT and GaN laser are vertically monolithically integrated on the same substrate by epitaxial growth, so the thermal effects of the HEMT and the laser will affect each other, which is very unfavorable for heat dissipation. Moreover, the GaN laser and the HEMT device are very sensitive to thermal effects, and such an integrated structure cannot exert the maximum performance of the two devices. In addition, there is no effective electrical isolation between the two devices, which further affects the stability and reliability of the integrated device.

[0006] In addition, in the prior art of GaN HEMT and GaN laser, the two devices are bonded on the same substrate by an adhesive material, which solves the technical problems of poor isolation and low safety between the two devices. However, the disadvantage of this technology is that the height difference of the back surface of the laser and the HEMT after bonding is too large, and the epitaxial structure of the laser is much higher than the HEMT structure, which is not conducive to the subsequent gate process of the HEMT, and greatly affects the performance of the HEMT device. In addition, since the bonding scheme is used, this method cannot reduce the cost of the substrate and is not conducive to large-scale manufacturing. SUMMARY

[0007] The purpose of the present application is to provide an integrated device of GaN laser and GaN HEMT and a preparation method thereof, so as to solve at least one of the problems existing in the prior art.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] The present application provides an integrated device of GaN laser and GaN HEMT in the first aspect, which comprises

[0010] a substrate;

[0011] a GaN laser layer structure formed on the substrate and a GaN HEMT layer structure formed on the substrate, and an isolation groove is arranged therebetween;

[0012] a passivation layer covering the GaN laser layer structure, the GaN HEMT layer structure and the isolation groove; and

[0013] a planarization layer formed on the surface of the passivation layer, wherein

[0014] the GaN laser layer structure comprises an N-type GaN contact layer, a multilayer InGaN quantum well active region and a P-type GaN contact layer formed on the substrate in sequence;

[0015] the GaN HEMT layer structure comprises a doped GaN buffer layer, a GaN channel layer and an AlGaN barrier layer formed on the substrate in sequence;

[0016] the GaN laser layer structure further comprises a step formed by the N-type GaN contact layer, an N-type electrode formed on the surface of the step, and a P-type electrode formed on the surface of the P-type GaN contact layer;

[0017] the GaN HEMT layer structure further comprises a drain electrode and a source electrode formed on the surface of the AlGaN barrier layer, and a gate electrode formed therebetween;

[0018] the surface of the planarization layer is electrically connected to the N-type electrode wiring of the N-type electrode of the GaN laser through a via, and the connection wiring electrically connecting the P-type electrode of the GaN laser and the source electrode of the GaN HEMT.

[0019] Optionally, the substrate comprises a substrate and a GaN buffer layer formed on the substrate, and the substrate is preferably silicon, SOI, SiC, sapphire, diamond, or a self-supporting GaN.

[0020] Optionally, the GaN laser is a ridge waveguide laser or a microcavity laser.

[0021] Optionally, the GaN laser layer structure further comprises an N-type AlGaN light confinement layer between the N-type GaN contact layer and the multi-layer InGaN quantum well active region, and a P-type AlGaN light confinement layer between the multi-layer InGaN quantum well active region and the P-type GaN contact layer.

[0022] Optionally, the GaN HEMT is an enhancement-mode GaN HEMT.

[0023] Optionally, the doped GaN buffer layer is a C- or Fe-doped GaN buffer layer, and the doping concentration is preferably greater than 1018cm-3. 18 cm -3 .

[0024] Optionally, the GaN HEMT further comprises a P-type GaN cap layer formed between the surface of the AlGaN barrier layer and the HEMT gate electrode.

[0025] Optionally, the thickness of the doped GaN buffer layer is such that the upper surfaces of the GaN laser layer structure and the GaN HEMT layer structure are substantially flush.

[0026] The second aspect of the present application provides a method for preparing an integrated device of a GaN laser and a GaN HEMT, which comprises

[0027] forming a GaN laser layer structure on a substrate;

[0028] etching the laser layer structure to expose the substrate to form a region for GaN HEMT;

[0029] forming a GaN HEMT layer structure on the exposed substrate by epitaxy;

[0030] forming an isolation groove between the GaN laser layer structure and the GaN HEMT layer structure and exposing the substrate, and forming a step on the side of the GaN laser layer structure away from the isolation groove to expose the surface of the N-type GaN contact layer of the GaN laser;

[0031] forming a passivation layer on the surface of the resulting structure;

[0032] forming an N-type electrode and a P-type electrode of the GaN laser, and a source electrode, a drain electrode and a gate electrode of the GaN HEMT;

[0033] forming a planarization layer;

[0034] forming a patterned wiring layer, including an N-type electrode wiring electrically connected to the N-type electrode of the GaN laser through a via, and a connection wiring electrically connected to the P-type electrode of the GaN laser and the source electrode of the GaN HEMT.

[0035] Optionally, the forming of the GaN HEMT layer structure comprises

[0036] forming a doped GaN buffer layer on the substrate;

[0037] forming a GaN channel layer on the doped GaN buffer layer; and

[0038] forming an AlGaN barrier layer on the GaN channel layer; wherein

[0039] the doped GaN buffer layer is a C or Fe doped GaN buffer layer, preferably with a doping concentration greater than 10 18 cm -3 , and preferably with a thickness such that the upper surfaces of the GaN laser layer structure and the GaN HEMT layer structure are substantially flush.

[0040] The beneficial effects of the present application are as follows:

[0041] The integrated device of GaN laser and GaN HEMT provided by the present application integrates the GaN laser and GaN HEMT laterally on the same substrate by using the secondary epitaxial selective growth technology, and keeps the overall thickness of the epitaxial structures of the two devices uniform, which effectively reduces the subsequent process difficulty; at the same time, the GaN laser and GaN HEMT are independently heat-dissipated and electrically isolated, which improves the efficiency and stability of the whole chip system. BRIEF DESCRIPTION OF DRAWINGS

[0042] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0043] Figure 1 A flow chart of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0044] Figure 2 A structure obtained in S1 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0045] Figure 3 A structure obtained in S2 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0046] Figure 4 A structure obtained in S3 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0047] Figure 5 A structure obtained in S4 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0048] Figure 6 A structure obtained in S5 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0049] Figure 7 A structure obtained in S6 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0050] Figure 8 A structure obtained in S7 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0051] Figure 9 A structure obtained in S8 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0052] Figure 10 A structure obtained in S9 of a method for manufacturing an integrated device of a GaN laser and a GaN HEMT is shown.

[0053] In the figure: 100. Substrate, 101. GaN buffer layer, 110. Laser N-type GaN contact layer, 111. Laser N-type AlGaN optical confinement layer, 112. Laser InGaN quantum well active region, 113. Laser P-type AlGaN optical confinement layer, 114. Laser P-type GaN contact layer, 115. Laser P-type ohmic electrode, 116. Laser N-type ohmic electrode, 120. High resistance C or Fe doped GaN buffer layer, 121. HEMT GaN channel layer, 122. HEMT AlGaN barrier layer, 123. HEMT P-type GaN cap layer, 124. HEMT source ohmic electrode, 125. HEMT drain ohmic electrode, 126. HEMT gate Schottky electrode, 102. Passivation layer, 103. Planarization material, 104. Laser P-type electrode and HEMT source connecting electrode, 105. Laser N-type electrode electroplated thick gold, 106. HEMT drain electrode electroplated thick gold, 107. HEMT gate electrode electroplated thick gold. DETAILED DESCRIPTION

[0054] In order to more clearly illustrate the application, the application will be further described below with reference to the embodiments and the accompanying drawings. Like components are denoted by the same reference signs in the accompanying drawings. It should be understood by those skilled in the art that the specific description below is illustrative rather than limiting, and should not limit the scope of protection of the application.

[0055] The existing monolithic integrated III-nitride HEMT and GaN laser fabrication method has obvious disadvantages. The GaN HEMT and GaN laser are vertically monolithically integrated on the same substrate by epitaxial growth, so the thermal effects of the GaN HEMT and GaN laser will affect each other, which is very unfavorable for heat dissipation. Moreover, both the GaN laser and the HEMT device are very sensitive to thermal effects, and such an integrated structure cannot maximize the performance of the two devices. In addition, there is no effective electrical isolation between the two devices, which further affects the stability and reliability of the integrated device.

[0056] In addition, in the existing technology of GaN HEMT and GaN laser, the two devices are bonded on the same substrate by an adhesive material, which solves the technical problems of poor isolation and low safety between the two devices. However, the disadvantage of this technology is that the height difference of the back surface of the GaN laser and the GaN HEMT after bonding is too large, and the epitaxial structure of the GaN laser is much higher than that of the GaN HEMT, which is not conducive to the subsequent gate process of the GaN HEMT, and greatly affects the performance of the GaN HEMT device. In addition, since the bonding scheme is used, this method cannot reduce the cost of the substrate, and is not conducive to large-scale manufacturing.

[0057] In view of this, one embodiment of the present invention provides a method comprising forming a GaN laser layer structure on a substrate; etching the laser layer structure until the substrate exposes a region for forming a GaN HEMT; epitaxially forming a GaN HEMT layer structure on the exposed substrate; forming an isolation trench located between the GaN laser layer structure and the GaN HEMT layer structure and exposing the substrate; forming a step on the side of the GaN laser layer structure away from the isolation trench to expose the surface of the N-type GaN contact layer of the GaN laser; forming a passivation layer on the surface of the resulting structure; forming an N-type electrode and a P-type electrode of the GaN laser; forming a source, drain, and gate electrode of the GaN HEMT; forming a planarization layer; and forming a patterned wiring layer including N-type electrode wiring electrically connected to the N-type electrode of the GaN laser through vias, and connection wiring electrically connecting the P-type electrode of the GaN laser and the source electrode of the GaN HEMT.

[0058] Specifically, the substrate includes a substrate and a GaN buffer layer formed on the substrate.

[0059] In a specific example, such as Figure 1 As shown, the method includes:

[0060] S1: Epitaxial growth of GaN laser heterostructures on a substrate via molecular beam epitaxy or metal-organic vapor deposition (MBE or MOCVD);

[0061] Furthermore, such as Figure 2 As shown, S1 includes directly growing a GaN quantum well laser epitaxial structure layer (GaN laser layer structure) on an N-type doped GaN buffer layer 101 formed on the surface of a substrate 100 using MBE and MOCVD. The substrate material includes, but is not limited to, silicon, silicon-on-insulator (SOI), SiC, sapphire, diamond, self-supporting GaN, etc. The epitaxial structure layer includes, from bottom to top: an N-type GaN contact layer 110, an N-type doped AlGaN optical confinement layer 111, a multilayer InGaN quantum well active region 112, a P-type doped AlGaN optical confinement layer 113, and a P-type highly doped GaN contact layer 114.

[0062] It should be noted that, Figure 2 The epitaxial structure layer shown is a typical GaN blue-green quantum well laser structure, which serves as an example in this scheme.

[0063] S2: Photolithography and etching techniques are used to etch part of the epitaxial layer to the GaN buffer layer to expose the epitaxial window generated in a secondary selective manner;

[0064] Furthermore, such as Figure 3As shown, a 150-200 nm layer of silicon dioxide (SiO2) is deposited on the surface of the p-type highly doped GaN contact layer 114 as a mask for selective growth. The SiO2 is patterned using photolithography and reactive ion etching (RIE) techniques. Then, inductively coupled plasma (ICP) etching is used to etch the epitaxial layer down to the N-type doped GaN buffer layer 101, thereby fabricating the epitaxial window 200 required for secondary epitaxy.

[0065] In one possible implementation, forming the GaN HEMT layer structure includes forming a doped GaN buffer layer on the substrate; forming a GaN channel layer on the doped GaN buffer layer; and forming an AlGaN barrier layer on the GaN channel layer; wherein the doped GaN buffer layer is a C or Fe doped GaN buffer layer, preferably with a doping concentration greater than 10. 18 cm -3 Preferably, the thickness is such that the upper surfaces of the GaN laser layer structure and the GaN HEMT layer structure are substantially flush.

[0066] In a specific example, such as Figure 1 As shown, the method includes:

[0067] S3: Selectively grow enhanced AlGaN / GaN HEMT epitaxial structures within the epitaxial window and strip away the area outside the window;

[0068] Furthermore, such as Figure 4 As shown, an enhanced HEMT epitaxial structure (GaN HEMT layer structure) is epitaxially grown in epitaxial window 200 using MBE / MOCVD. The enhanced HEMT epitaxial structure includes, but is not limited to, a high-resistivity C or Fe-doped GaN buffer layer 120, a GaN channel layer 121, an AlGaN barrier layer 122, and a p-type GaN capping layer 123. After epitaxy, a wet stripping technique is used to etch away the SiO2 growth mask, thereby removing excess epitaxial material outside the epitaxial window 200, achieving selective growth.

[0069] It is important to note that the thickness of the C or Fe heavily doped GaN buffer layer 120 needs to be adjusted according to the thickness of the GaN laser epitaxial layer to ensure that the overall epitaxial layer thickness of the laser is consistent with the thickness of the HEMT epitaxial layer, which facilitates subsequent device fabrication.

[0070] Preferably, the doping concentration of C or Fe should be greater than 10. 18 cm -3 This effectively reduces the leakage current of the HEMT and ensures effective electrical isolation from the laser.

[0071] S4: Mesa etching of GaN laser and GaN HEMT is performed using ICP technology;

[0072] Furthermore, such as Figure 5 As shown, photolithography and ICP etching techniques are used to etch the laser and HEMT epitaxial layers down to the GaN buffer layer 101, thereby removing non-uniform material at the laser and HEMT epitaxial interface and reducing electrical leakage. Then, mesa etching is performed on the laser and HEMT separately, with the laser mesa etched down to the N-type contact layer 110.

[0073] S5: Etch the P-type GaN capping layer of the GaN laser ridge waveguide and the GaN HEMT respectively;

[0074] Furthermore, such as Figure 6 As shown, the ridge waveguide of the laser is etched using photolithography and ICP etching. The etched AlGaN light confinement layer 113 and the P-type highly doped GaN contact layer 114 form the ridge waveguide of the laser. The etching depth should be controlled to 100-200 nm above the quantum well active region 112, and the width of this ridge waveguide is 1-3 μm. Subsequently, the P-type gate capping layer 123 of the HEMT device is etched using ICP. The length of the GaN capping layer 123 is consistent with the HEMT gate length, and the etching depth should be precisely controlled to the thickness of the capping layer 123 to reduce damage to the underlying AlGaN barrier layer 122.

[0075] S6: Deposit passivation layers on GaN lasers and GaN HEMT devices, and perform windowing treatment on the P-type and N-type electrodes of GaN lasers and the source and drain regions of GaN HEMTs.

[0076] Furthermore, such as Figure 7 As shown, SiO2 was deposited on the sample surface as a passivation layer 102 using PECVD technology, with a thickness of 100-200 nm. Patterning and windowing were then performed using photolithography and RIE etching techniques to remove the passivation layers from the P-type and N-type electrode contact layers in the laser region, and the source and drain regions in the HEMT region.

[0077] S7: P-type electrode, N-type electrode, and source and drain of GaN HEMT for vapor-deposited GaN lasers;

[0078] Furthermore, such as Figure 8 As shown, a P-type electrode 115 is deposited on the P-type GaN contact layer 114 of the laser by photolithography, electron beam sputtering or magnetron sputtering, an N-type electrode 116 is deposited on the N-type GaN contact layer 110, and an HEMT source electrode 124 and a drain electrode 125 are deposited on the AlGaN barrier layer 122. Then, RTP treatment is performed to form a low-resistance ohmic contact electrode.

[0079] S8: Windowing and electrode deposition are performed on the gate of the GaN HEMT;

[0080] Furthermore, such as Figure 9 As shown, a window is created in the gate region of the HEMT using photolithography and etching techniques, and then the gate Schottky electrode 126 is fabricated using photolithography, evaporation and lift-off techniques.

[0081] S9: The device is planarized and thick electrode is plated. The GaN laser P-type electrode is connected to the GaN HEMT source by electroplating the thick electrode.

[0082] Furthermore, such as Figure 10 As shown, the sample after S8 treatment undergoes spin-coating of planarization material, curing and baking, and planarization etching, ensuring that the planarization material 103 does not exceed the P-type electrode of the laser and the electrode of the HEMT device. Using photolithography and etching techniques, a window is etched into the N-type electrode 116 of the laser. Using electroplating techniques, thick gold plating is performed on the P-type and N-type electrodes of the laser, and the source, drain, and gate of the HEMT. The P-type electrode 115 of the laser is connected to the source 124 of the HEMT via metal 104, thereby realizing the modulation and switching function of the HEMT on the laser.

[0083] S10: Performs back-end chip thinning, laser cleaving, and end-face coating.

[0084] Furthermore, the S9-processed chip undergoes post-processing, including thinning the substrate to 100-120µm using a polishing machine to reduce the impact of thermal effects on the device. Subsequently, the thinned chip undergoes laser end face cleaving, and high-reflectivity and anti-reflection films are deposited on the cleaved surfaces to increase the laser's output power.

[0085] This embodiment uses a secondary epitaxial selective growth technique to laterally integrate a GaN laser and a GaN HEMT on the same substrate, while maintaining a uniform overall thickness of the epitaxial structures of the two devices, effectively reducing the difficulty of subsequent processes. At the same time, the GaN laser and GaN HEMT are independently cooled and electrically isolated, improving the efficiency and stability of the entire chip system.

[0086] Another embodiment of the present application provides the integrated device comprising a substrate; a GaN laser layer structure formed on the substrate and a GaN HEMT layer structure formed on the substrate, with an isolation groove disposed therebetween; a passivation layer covering the GaN laser layer structure, the GaN HEMT layer structure and the isolation groove; and a planarization layer formed on the surface of the passivation layer, wherein the GaN laser layer structure comprises an N-type GaN contact layer, a multi-layer InGaN quantum well active region and a P-type GaN contact layer formed on the substrate in sequence; the GaN HEMT layer structure comprises a doped GaN buffer layer, a GaN channel layer and an AlGaN barrier layer formed on the substrate in sequence; the GaN laser layer structure further comprises a step formed by the N-type GaN contact layer, an N-type electrode formed on the surface of the step, and a P-type electrode formed on the surface of the P-type GaN contact layer; the GaN HEMT layer structure further comprises a drain electrode and a source electrode formed on the surface of the AlGaN barrier layer, and a gate electrode formed therebetween; the surface of the planarization layer is electrically connected to an N-type electrode wiring of the N-type electrode of the GaN laser through a via, and a connection wiring electrically connecting the P-type electrode of the GaN laser and the source electrode of the GaN HEMT.

[0087] The present embodiment effectively reduces the subsequent process difficulty by using the secondary epitaxial selective growth technology to laterally integrate the GaN laser and the GaN HEMT on the same substrate, and keeping the overall thickness of the epitaxial structures of the two devices uniform; meanwhile, the GaN laser and the GaN HEMT are independently heat-dissipated and electrically isolated, thereby improving the efficiency and stability of the entire chip system.

[0088] In a possible implementation, the substrate comprises a substrate and a GaN buffer layer formed on the substrate, and the substrate is preferably silicon, SOI, SiC, sapphire, diamond or self-supporting GaN.

[0089] In a specific example, as shown in Figure 1 the substrate comprises a substrate 100 and an N-type doped GaN buffer layer 101.

[0090] In a possible implementation, the GaN laser is a ridge waveguide laser, a vertical cavity surface emitting laser or a microcavity laser.

[0091] It should be noted that the epitaxial layer structure as shown in Figure 2 is a typical GaN blue-green quantum well laser structure, which is only a demonstration example in this scheme.

[0092] In a possible implementation, the GaN laser layer structure further comprises an N-type AlGaN optical confinement layer between the N-type GaN contact layer and the multi-layer InGaN quantum well active region, and a P-type AlGaN optical confinement layer between the multi-layer InGaN quantum well active region and the P-type GaN contact layer.

[0093] In a specific example, as shown in FIG. 1, the GaN laser layer structure comprises, from bottom to top, a laser N-type GaN contact layer 110, an N-type doped AlGaN optical confinement layer 111, a multi-layer InGaN quantum well active region 112, and a P-type doped AlGaN optical confinement layer 113. Figure 2

[0094] Further, as shown in FIG. 1, a P-type highly doped GaN contact layer 114 is formed on the P-type doped AlGaN optical confinement layer 113. Figure 2

[0095] In a possible implementation, the GaN HEMT is an enhancement-mode GaN HEMT.

[0096] The embodiment can realize large-scale hetero-integration on GaN, and by using secondary selective growth epitaxy technology, two devices are laterally integrated on a substrate, thereby realizing a GaN laser direct modulation integrated chip that is resistant to high frequency, high voltage, and high stability.

[0097] In a possible implementation, the doped GaN buffer layer is a C or Fe doped GaN buffer layer, and preferably, the doping concentration is greater than 10 18 cm -3 .

[0098] In a specific example, as shown in FIG. 2, the enhancement-mode HEMT epitaxial structure comprises, but is not limited to, a high-resistance C or Fe doped GaN buffer layer 120. The embodiment can effectively reduce the leakage current of the GaN HEMT and ensure effective electrical isolation with the GaN laser. Figure 4

[0099] In a possible implementation, the GaN HEMT further comprises a P-type GaN cap layer formed between the surface of the AlGaN barrier layer and the HEMT gate electrode.

[0100] In a specific example, as shown in FIG. 3, the enhancement-mode HEMT epitaxial structure comprises, but is not limited to, a P-type GaN cap layer 123. Figure 4

[0101] ​​​​Further, the enhanced GaN HEMT structure uses a P-type GaN cap layer to deplete the 2DEG in the GaN HEMT structure, enabling the normally-off GaN HEMT device.

[0102] In some alternative examples, an alternative enhanced GaN HEMT implementation includes a method of recessed gate or F implantation.

[0103] In one possible implementation, the thickness of the doped GaN buffer layer is such that the upper surfaces of the GaN laser layer structure and the GaN HEMT layer structure are substantially flush.

[0104] In one specific example, as shown in FIG. 1, a C or Fe heavily doped GaN buffer layer 120 is used to deplete the 2DEG in the GaN HEMT structure. Figure 4 The thickness of the C or Fe heavily doped GaN buffer layer 120 is adjusted according to the thickness of the laser epitaxial layer to achieve a consistent overall epitaxial layer thickness for both the laser and the HEMT.

[0105] The present embodiment effectively reduces the subsequent process difficulty by using a secondary epitaxial growth technique to laterally integrate the GaN laser and the GaN HEMT on the same substrate while maintaining the overall thickness of the two device epitaxial structures uniform. At the same time, the GaN laser and the GaN HEMT are independently heat-dissipated and electrically isolated, improving the efficiency and stability of the entire chip system.

[0106] In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise expressly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0107] It is further noted that the terminology "first", "second" and the like used in the description of the application is merely intended to differentiate one entity or operation from another, without necessarily requiring or implying any actual such relationship or order between such entities or operations. Moreover, the use of the term "including", "containing" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or even inherent to such process, method, article or apparatus. An element proceeded by "comprises... a", "has... a", "includes... a" or "contains... a", does not, without more constraints, preclude the existence of additional identical elements in the process, method, article or apparatus that comprises the element.

[0108] Obviously, the above-described embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation manners of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art, and it is impossible to enumerate all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A method for fabricating an integrated device of a GaN laser and a GaN HEMT, the method comprising the integrated device comprising a substrate; a GaN laser layer structure formed on the substrate and a GaN HEMT layer structure formed on the substrate with an isolation trench disposed therebetween; a passivation layer covering the GaN laser layer structure, the GaN HEMT layer structure and the isolation trench; and a planarization layer formed on a surface of the passivation layer, wherein the GaN laser layer structure comprises an N-type GaN contact layer, a multi-layer InGaN quantum well active region and a P-type GaN contact layer formed on the substrate in sequence; the GaN HEMT layer structure comprises a doped GaN buffer layer, a GaN channel layer and an AlGaN barrier layer formed on the substrate in sequence, the doped GaN buffer layer having a thickness such that upper surfaces of the GaN laser layer structure and the GaN HEMT layer structure are substantially flush; the GaN laser layer structure further comprises a step formed by the N-type GaN contact layer, an N-type electrode formed on a surface of the step, and a P-type electrode formed on a surface of the P-type GaN contact layer; the GaN HEMT layer structure further comprises a drain electrode and a source electrode formed on a surface of the AlGaN barrier layer with a gate electrode formed therebetween; a patterned wiring layer on a surface of the planarization layer comprises an N-type electrode wiring electrically connected to the N-type electrode of the GaN laser through a via, and a connection wiring electrically connecting the P-type electrode of the GaN laser and the source electrode of the GaN HEMT. the method comprises forming the GaN laser layer structure on the substrate; performing etching on the laser layer structure to expose a region of the substrate for forming the GaN HEMT; forming the GaN HEMT layer structure epitaxially on the exposed substrate; forming the isolation trench between the GaN laser layer structure and the GaN HEMT layer structure and exposing the substrate, and forming a step exposing a surface of the N-type GaN contact layer of the GaN laser on a side of the GaN laser layer structure away from the isolation trench; forming the passivation layer on a surface of the resulting structure; forming the N-type electrode and the P-type electrode of the GaN laser, and forming the source electrode, the drain electrode and the gate electrode of the GaN HEMT; forming the planarization layer; forming the patterned wiring layer comprising the N-type electrode wiring electrically connected to the N-type electrode of the GaN laser through the via, and the connection wiring electrically connecting the P-type electrode of the GaN laser and the source electrode of the GaN HEMT. the forming the GaN HEMT layer structure comprises 2. The production method according to claim 1, characterized by, forming the doped GaN buffer layer on the substrate; forming the GaN channel layer on the doped GaN buffer layer; and forming the AlGaN barrier layer on the GaN channel layer, wherein the doped GaN buffer layer is a C- or Fe-doped GaN buffer layer. the substrate comprises a substrate and a GaN buffer layer formed on the substrate. the GaN laser is a ridge waveguide laser or a microcavity laser.

3. The preparation method according to claim 1, characterized in that, ​ 4. The method of claim 1, wherein, ​ 5. The preparation method according to claim 1, characterized in that, The GaN laser layer structure further includes an N-type AlGaN optical confinement layer between the N-type GaN contact layer and the multi-layer InGaN quantum well active region and a P-type AlGaN optical confinement layer between the multi-layer InGaN quantum well active region and the P-type GaN contact layer.

6. The method of claim 1, wherein, The GaN HEMT is an enhancement mode GaN HEMT.

7. The preparation method according to claim 1, characterized in that, The doped GaN buffer layer is a C or Fe doped GaN buffer layer.

8. The method of claim 1, wherein, The GaN HEMT further includes a P-type GaN cap layer formed between the surface of the AlGaN barrier layer and the HEMT gate electrode.

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