Beta-ga2o3 epitaxial structure and method for manufacturing the same, and semiconductor device
By alternating growth of In-doped and non-In-doped β-Ga2O3 layers, the problems of low crystal quality and high surface roughness of β-Ga2O3 epitaxial thick film structures were solved, achieving the growth of high-quality β-Ga2O3 epitaxial layers and improving device performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUXI CHINA RESOURCES MICROELECTRONICS
- Filing Date
- 2024-12-03
- Publication Date
- 2026-06-05
AI Technical Summary
In the prior art, the β-Ga2O3 epitaxial thick film structure has problems of low crystal quality and high surface roughness. In particular, when homoepitaxially grown on (001) Ga2O3 substrate, the problems of step aggregation and trench undulation are serious, which affect the device performance.
A stacked structure with alternating growth of In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers was adopted. By controlling the growth temperature, pressure and VI/III ratio, a β-Ga2O3 epitaxial layer was formed, the growth process was optimized, the formation and desorption of Ga2O were suppressed, the step flow growth mode was promoted, and the defect propagation was prevented.
This improved the crystal quality and growth rate of the β-Ga2O3 epitaxial structure, reduced surface roughness, and enhanced device performance.
Smart Images
Figure CN122161345A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and more specifically to a β-Ga2O3 epitaxial structure, its manufacturing method, and semiconductor devices. Background Technology
[0002] As a novel ultrawide semiconductor material, Ga2O3 achieves a bandgap of 4.9 eV and possesses a bandgap of 8 mV·cm⁻¹. -1 With its theoretical electric field strength of 3444 and a Baliga figure of merit of 3444, Ga2O3-based devices can achieve both higher voltage withstand capability and lower power consumption, resulting in a significant improvement in energy conversion efficiency. Ga2O3-based devices have broad application prospects in the field of high-power device fabrication.
[0003] Among them, β-Ga2O3 with a monoclinic phase is the most stable thermodynamic crystal structure, and high-quality β-Ga2O3 epitaxial thick film structures are essential for realizing the characteristics of Ga2O3-based devices. However, β-Ga2O3 epitaxial thick film structures in related technologies suffer from low crystal quality and high surface roughness.
[0004] Therefore, improvements are needed to at least partially address the aforementioned problems. Summary of the Invention
[0005] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.
[0006] To at least partially solve the above-mentioned technical problems, this application provides a β-Ga2O3 epitaxial structure, comprising:
[0007] Substrate;
[0008] A β-Ga2O3 epitaxial layer is located on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures, each of which includes stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers.
[0009] For example, each of the stacked structures includes, from bottom to top, the In-doped β-Ga2O3 layer and the non-In-doped β-Ga2O3 layer; or,
[0010] Each of the stacked structures includes, from bottom to top, the non-In-doped β-Ga2O3 layer and the In-doped β-Ga2O3 layer.
[0011] For example, the In-doped β-Ga2O3 layer is formed at a first temperature, a first pressure, and a first VI / III ratio, wherein the first temperature ranges from 780°C to 880°C, the first pressure ranges from 15 mbar to 40 mbar, the first VI / III ratio ranges from 300 to 420, and the growth time of each In-doped β-Ga2O3 layer is 3 s to 8 s.
[0012] The non-In-doped β-Ga2O3 layer is formed at a second temperature, a second pressure, and a second VI / III ratio, wherein the second temperature ranges from 885℃ to 1000℃, the second pressure ranges from 45mbar to 100mbar, the second VI / III ratio ranges from 160 to 295, and the growth time of each non-In-doped β-Ga2O3 layer is 6s to 16s.
[0013] For example, the first temperature is 850°C, the first pressure is 35 mbar, the first VI / III ratio is 320, and the growth time of each In-doped β-Ga2O3 layer is 6 s;
[0014] The second temperature is 930°C, the second pressure is 55 mbar, the second VI / III ratio is 220, and the growth time of each layer of the non-In-doped β-Ga2O3 layer is 12 s.
[0015] This application also provides a method for manufacturing a β-Ga2O3 epitaxial structure, comprising:
[0016] Provide substrate;
[0017] A β-Ga2O3 epitaxial layer is formed on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures, each of which includes stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers.
[0018] For example, the In-doped β-Ga2O3 layer is grown and formed in an MOCVD reaction chamber. The In-doped β-Ga2O3 layer is formed at a first temperature, a first pressure, and a first VI / III ratio, wherein the first temperature ranges from 780°C to 880°C, the first pressure ranges from 15 mbar to 40 mbar, the first VI / III ratio ranges from 300 to 420, and the growth time of each In-doped β-Ga2O3 layer is 3 s to 8 s.
[0019] The undoped β-Ga2O3 layer is grown in the MOCVD reaction chamber. The undoped β-Ga2O3 layer is formed at a second temperature, a second pressure, and a second VI / III ratio. The second temperature ranges from 885℃ to 1000℃, the second pressure ranges from 45mbar to 100mbar, the second VI / III ratio ranges from 160 to 295, and the growth time of each undoped β-Ga2O3 layer is 6s to 16s.
[0020] For example, the first temperature is 850°C, the first pressure is 35 mbar, the first VI / III ratio is 320, and the growth time of each In-doped β-Ga2O3 layer is 6 s;
[0021] The second temperature is 930°C, the second pressure is 55 mbar, the second VI / III ratio is 220, and the growth time of each layer of the non-In-doped β-Ga2O3 layer is 12 s.
[0022] For example, when the In-doped β-Ga2O3 layer is grown in the MOCVD reaction chamber, the Ga source is TEGa and the flow rate of the Ga source is 700 sccm-1000 sccm, the In source is TMI and the flow rate of the In source is 2 sccm-10 sccm.
[0023] When the undoped β-Ga2O3 layer is grown in the MOCVD reaction chamber, the Ga source is TMGa and the Ga source flow rate is 300 sccm-700 sccm.
[0024] For example, before forming the β-Ga2O3 epitaxial layer, the substrate is further subjected to annealing and desorption treatment.
[0025] In another aspect, this application provides a semiconductor device comprising the aforementioned β-Ga2O3 epitaxial structure, or comprising a β-Ga2O3 epitaxial structure manufactured using the aforementioned manufacturing method.
[0026] The β-Ga2O3 epitaxial structure, its manufacturing method, and semiconductor device disclosed in this application include a β-Ga2O3 epitaxial layer comprising multiple stacked structures, each stacked structure comprising stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers. This method can improve the crystal quality and growth rate of the β-Ga2O3 epitaxial structure while reducing the surface roughness of the β-Ga2O3 epitaxial structure, thereby obtaining a β-Ga2O3 epitaxial structure with a certain thickness. Attached Figure Description
[0027] The following drawings, which are incorporated herein by reference and are used to understand this application, illustrate embodiments of the invention and their descriptions to explain the principles of the invention.
[0028] In the attached image:
[0029] Figure 1 A cross-sectional schematic diagram of a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application is shown;
[0030] Figure 2 A cross-sectional schematic diagram of a β-Ga2O3 epitaxial structure according to another exemplary embodiment of this application is shown;
[0031] Figure 3 A flowchart illustrating a method for manufacturing a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application is shown. Detailed Implementation
[0032] The present application will now be described more fully with reference to the accompanying drawings, in which embodiments of the present application are illustrated. However, the present application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present application to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.
[0033] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.
[0034] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “under” the other element or feature will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.
[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.
[0036] Embodiments of the application are described herein with reference to cross-sectional views illustrating ideal embodiments (and intermediate structures). Thus, variations from the shapes shown can be anticipated due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of the application should not be limited to the specific shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing processes. For example, implantation regions shown as rectangular typically have rounded or curved features at their edges and / or implantation concentration gradients, rather than a binary change from implantation regions to non-implantation regions. Similarly, buried regions formed by implantation can result in some implantation in the region between the buried region and the surface traversed during implantation. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to show the actual shapes of the regions of the device and are not intended to limit the scope of the application.
[0037] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms as defined in commonly used dictionaries shall be construed as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and not as interpreted in an ideal or overly formal sense, unless expressly defined herein.
[0038] To fully understand this application, a detailed structure will be presented in the following description to illustrate the technical solutions proposed in this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.
[0039] Among related technologies, metal-organic chemical vapor deposition (MOCVD) has become one of the main methods for homoepitaxial growth of β-Ga2O3 due to its advantages such as high quality, large size, low cost, and easy doping. Currently, β-Ga2O3 homoepitaxial growth utilizes four different Ga2O3 substrates with different crystal planes: (100), (010), (001), and (-201) plane Ga2O3 substrates. Among them, the (001) plane Ga2O3 substrate has relatively balanced properties in all aspects, with lower dislocation density and larger size. However, during the homoepitaxial growth of β-Ga2O3 thick film structures (e.g., β-Ga2O3 epitaxial structures with a thickness greater than 3 μm) on the (001) plane Ga2O3 substrate, there are problems of step coalescence and trench undulation, resulting in high surface roughness of the β-Ga2O3 thick film structure. At the same time, the crystal quality of the β-Ga2O3 thick film structure is also poor.
[0040] In related technologies, thick film growth is generally achieved by increasing the growth rate of the epitaxial layer by lowering the epitaxial growth temperature, so as to obtain the β-Ga2O3 epitaxial thick film structure; or, the surface roughness of the β-Ga2O3 epitaxial thick film structure is improved by continuous In-assisted epitaxial growth.
[0041] However, low epitaxial growth temperature will lead to poor crystal quality and a significant increase in defect density of the epitaxial layer, thus affecting device performance; continuous In-assisted epitaxial growth will lead to an increase in In concentration in the epitaxial layer, resulting in the growth of InGaO structure instead of the designed β-Ga2O3 structure.
[0042] Therefore, in view of the aforementioned technical problems, this application proposes a β-Ga2O3 epitaxial structure, comprising:
[0043] Substrate;
[0044] The β-Ga2O3 epitaxial layer is located on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures, each of which includes stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers.
[0045] The β-Ga2O3 epitaxial structure of this application includes multiple stacked structures, each stacked structure including stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers. This structure can improve the crystal quality and growth rate of the β-Ga2O3 epitaxial structure while reducing the surface roughness of the β-Ga2O3 epitaxial structure, thus obtaining a β-Ga2O3 epitaxial structure with a certain thickness.
[0046] Example 1
[0047] Below, for reference Figure 1 and Figure 2 The β-Ga2O3 epitaxial structure in the embodiments of this application is described. Figure 1 This paper shows a schematic cross-sectional view of a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application. Figure 2 A cross-sectional schematic diagram of a β-Ga2O3 epitaxial structure according to another exemplary embodiment of this application is shown.
[0048] In one example, such as Figure 1 and Figure 2 As shown, the β-Ga2O3 epitaxial structure of this application includes a substrate 100 and a β-Ga2O3 epitaxial layer 110 located on the substrate 100. The β-Ga2O3 epitaxial layer 110 includes a plurality of stacked structures 111, each stacked structure 111 including an In-doped β-Ga2O3 layer 1111 and a non-In-doped β-Ga2O3 layer 1112. Exemplarily, the β-Ga2O3 epitaxial layer 110 of this application may also be referred to as an HT-Ga2O3 (High Temperature-Ga2O3) epitaxial layer.
[0049] In one example, such as Figure 1 As shown, each stacked structure includes, from bottom to top, an In-doped β-Ga₂O₃ layer 1111 and a non-In-doped β-Ga₂O₃ layer 1112; or, as shown... Figure 2 As shown, each stacked structure includes a non-In-doped β-Ga2O3 layer 1112 and an In-doped β-Ga2O3 layer 1111 stacked sequentially from bottom to top.
[0050] In one example, substrate 100 includes a Sn-doped β-Ga2O3 substrate. Specifically, substrate 100 can be a Sn-doped (100), (010), (001) or (-201) plane Ga2O3 substrate. The β-Ga2O3 epitaxial structure of this application is a homogeneous epitaxial structure.
[0051] In one example, during the epitaxial growth of β-Ga2O3, the anisotropy of surface energy and atomic diffusion ability, as well as the competition between the film growth and etching reactions (Ga2O desorption), lead to step coalescence and trench undulation problems, resulting in significant surface undulations and a sharp increase in surface roughness of the β-Ga2O3 epitaxial layer. The β-Ga2O3 epitaxial layer 110 of this application includes an In-doped β-Ga2O3 layer 1111. The In doping in the In-doped β-Ga2O3 layer 1111 can suppress the formation and desorption of Ga2O during epitaxial growth and enhance the adsorption capacity of Ga atoms on the surface, optimizing the β-Ga2O3 growth process. The co-adsorption of Ga atoms and In atoms can promote the transformation of the epitaxial film growth mode from an island-like growth mode to a step-flow growth mode, stabilizing surface thermal fluctuations during epitaxial film growth, suppressing trench morphology, effectively solving the problems of step coalescence and trench undulation, reducing surface roughness, and increasing the growth rate.
[0052] In one example, TEGa (triethylgallium) can be used as the Ga source during the growth of the In-doped β-Ga2O3 layer 1111 to reduce the C concentration, thereby improving the decrease in crystal quality caused by In doping and obtaining an In-doped β-Ga2O3 layer 1111 with higher crystal quality.
[0053] In one example, the undoped β-Ga2O3 layer 1112 can be formed at a high growth temperature, for example, it can be formed at 885℃-1000℃, thereby reducing defect density and improving crystal quality; at the same time, the undoped β-Ga2O3 layer 1112 has a high crystal quality because it is not doped with In.
[0054] In one example, alternating growth of In-doped β-Ga₂O₃ layers 1111 and non-In-doped β-Ga₂O₃ layers 1112 effectively prevents defects from extending upwards from the substrate 100. For instance, when a device layer is formed on the β-Ga₂O₃ epitaxial structure, the alternating growth of In-doped β-Ga₂O₃ layers 1111 and non-In-doped β-Ga₂O₃ layers 1112 effectively prevents defects from extending from the substrate 100 towards the device layer, thereby improving the crystal quality of the β-Ga₂O₃ epitaxial structure. Simultaneously, the alternating growth of In-doped β-Ga₂O₃ layers 1111 and non-In-doped β-Ga₂O₃ layers 1112 also effectively prevents the problem of increased defect density due to lattice distortion.
[0055] In one example, an In-doped β-Ga2O3 layer 1111 is formed at a first temperature, a first pressure, and a first VI / III ratio, wherein the first temperature ranges from 780°C to 880°C, for example, the first temperature can be 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, or 880°C; the first pressure ranges from 15 mbar to 40 mbar, for example, the first pressure can be 15 mbar, 20 mbar, 25 mbar, 30 mbar, 35 mbar, or 40 mbar; and the first VI / III ratio ranges from 300 to 420, for example, the first VI / III ratio can be 300, 310, 320, 330, 340, 450, 360, 370, 380, 390, 400, 410, or 420. By forming the In-doped β-Ga2O3 layer 1111 at the first temperature, first pressure, and first VI / III ratio within the aforementioned range, the crystal quality of the In-doped β-Ga2O3 layer 1111 can be improved and its surface roughness reduced. Preferably, the first temperature is 850°C, the first pressure is 35 mbar, and the first VI / III ratio is 320.
[0056] In one example, a non-In-doped β-Ga2O3 layer 1112 is formed at a second temperature, a second pressure, and a second VI / III ratio. The second temperature ranges from 885°C to 1000°C, for example, it can be 885°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, or 1000°C. The second pressure ranges from 45 mbar to 100 mbar. The second pressure can be 45 mbar, 55 mbar, 60 mbar, 70 mbar, 80 mbar, 90 mbar, or 100 mbar, and the second VI / III ratio can be in the range of 160-295, for example, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 295. By forming the undoped β-Ga2O3 layer 1112 at the second temperature, second pressure, and second VI / III ratio within the above range, the crystal quality of the undoped β-Ga2O3 layer 1112 can be improved and its surface roughness reduced. Preferably, the second temperature is 930°C, the second pressure is 55 mbar, and the second VI / III ratio is 220.
[0057] In one example, the growth time of each In-doped β-Ga2O3 layer 1111 is 3s-8s, for example, the growth time of each In-doped β-Ga2O3 layer 1111 can be 3s, 4s, 5s, 6s, 7s, or 8s; the growth time of each non-In-doped β-Ga2O3 layer 1112 is 6s-16s, for example, the growth time of each non-In-doped β-Ga2O3 layer 1112 can be 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, or 16s. Exemplarily, by controlling the growth time of each In-doped β-Ga2O3 layer 1111 to 3s-8s, In can be sufficiently diffused, preventing the problem of increased defect density due to insufficient In diffusion. For example, by controlling the growth time of each In-doped β-Ga2O3 layer 1111 to be 3s-8s and the growth time of each non-In-doped β-Ga2O3 layer 1112 to be 6s-16s, the thickness of each In-doped β-Ga2O3 layer 1111 and each non-In-doped β-Ga2O3 layer 1112 can be controlled within a certain thickness range. This ensures that, with a fixed total thickness of the β-Ga2O3 epitaxial layer 110, the β-Ga2O3 epitaxial layer 110 has a sufficient number of alternating interfaces between In-doped β-Ga2O3 layers 1111 and non-In-doped β-Ga2O3 layers 1112, thereby effectively preventing defects from extending upward from the substrate 100 and preventing defect density caused by lattice distortion. Preferably, the growth time of each In-doped β-Ga2O3 layer 1111 is 6 s, and the growth time of each non-In-doped β-Ga2O3 layer 1112 is 12 s.
[0058] In one example, TMGa (trimethylgallium) can be used as the Ga source in the growth process of a non-In-doped β-Ga2O3 layer 1112 to improve the growth rate.
[0059] In one example, the number of stacked structures 111 is greater than or equal to 800 to obtain a β-Ga2O3 epitaxial structure with a certain thickness, for example, a β-Ga2O3 epitaxial structure with a thickness greater than 3 μm. Exemplarily, the number of stacked structures 111 is also less than or equal to 1800 to prevent excessively long growth time.
[0060] In summary, the β-Ga2O3 epitaxial structure of this application comprises multiple stacked structures, each stacked structure including stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers. This structure can improve the crystal quality and growth rate of the β-Ga2O3 epitaxial structure while reducing the surface roughness of the β-Ga2O3 epitaxial structure, thus obtaining a β-Ga2O3 epitaxial structure with a certain thickness.
[0061] Example 2
[0062] In another embodiment of this application, a method for manufacturing a β-Ga2O3 epitaxial structure is provided, the method being used to manufacture the β-Ga2O3 epitaxial structure described in Embodiment 1.
[0063] The following reference Figure 1 , Figure 2 and Figure 3 The present application describes a method for manufacturing a β-Ga2O3 epitaxial structure, wherein... Figure 1 This paper shows a schematic cross-sectional view of a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application. Figure 2 A schematic cross-sectional view of a β-Ga2O3 epitaxial structure according to another exemplary embodiment of this application is shown. Figure 3 A flowchart illustrating a method for manufacturing a β-Ga2O3 epitaxial structure according to an exemplary embodiment of this application is shown. First, step S1 is performed, in which a substrate 100 is provided.
[0064] In one example, substrate 100 includes a Sn-doped β-Ga2O3 substrate. Specifically, substrate 100 can be a Sn-doped (100), (010), (001) or (-201) plane Ga2O3 substrate. The β-Ga2O3 epitaxial structure of this application is a homogeneous epitaxial structure.
[0065] Next, step S2 is performed to form a β-Ga2O3 epitaxial layer 110 on the substrate 100. The β-Ga2O3 epitaxial layer 110 includes a plurality of stacked structures 111, each stacked structure 111 including stacked In-doped β-Ga2O3 layers 1111 and non-In-doped β-Ga2O3 layers 1112.
[0066] In one example, an In-doped β-Ga2O3 layer 1111 is grown and formed in an MOCVD reaction chamber within a β-Ga2O3 epitaxial layer 110. The In-doped β-Ga2O3 layer 1111 is formed at a first temperature, a first pressure, and a first VI / III ratio. The first temperature (the temperature of the MOCVD reaction chamber) is in the range of 780℃-880℃, for example, it can be 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, or 860℃. The temperature range is 870°C or 880°C, and the first pressure range is 15 mbar-40 mbar. For example, the first pressure (pressure of the MOCVD reaction chamber) can be 15 mbar, 20 mbar, 25 mbar, 30 mbar, 35 mbar, or 40 mbar. The first VI / III ratio range is 300-420. For example, the first VI / III ratio can be 300, 310, 320, 330, 340, 450, 360, 370, 380, 390, 400, 410, or 420. By forming the In-doped β-Ga2O3 layer 1111 at the above-mentioned first temperature, first pressure, and first VI / III ratio, the crystal quality of the In-doped β-Ga2O3 layer 1111 can be improved and its surface roughness reduced. Preferably, the first temperature is 850°C, the first pressure is 35 mbar, and the first VI / III ratio is 320.
[0067] In one example, a non-In-doped β-Ga2O3 layer 1112 is grown in a β-Ga2O3 epitaxial layer 110 in an MOCVD reaction chamber. The non-In-doped β-Ga2O3 layer 1112 is formed at a second temperature, a second pressure, and a second VI / III ratio. The second temperature ranges from 885℃ to 1000℃, for example, the second temperature can be 885℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, or 990℃. Alternatively, the temperature can be 1000°C, and the second pressure range can be 45 mbar-100 mbar, for example, the second pressure can be 45 mbar, 55 mbar, 60 mbar, 70 mbar, 80 mbar, 90 mbar, or 100 mbar, and the second VI / III ratio range can be 160-295, for example, the second VI / III ratio can be 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 295. By forming the non-In-doped β-Ga2O3 layer 1112 at the second temperature, second pressure, and second VI / III ratio within the above range, the crystal quality of the non-In-doped β-Ga2O3 layer 1112 can be improved and its surface roughness reduced. Preferably, the second temperature is 930°C, the second pressure is 55 mbar, and the second VI / III ratio is 220.
[0068] In one example, the growth time of each In-doped β-Ga2O3 layer 1111 is 3s-8s, for example, the growth time of each In-doped β-Ga2O3 layer 1111 can be 3s, 4s, 5s, 6s, 7s, or 8s; the growth time of each non-In-doped β-Ga2O3 layer 1112 is 6s-16s, for example, the growth time of each non-In-doped β-Ga2O3 layer 1112 can be 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, or 16s. Exemplarily, by controlling the growth time of each In-doped β-Ga2O3 layer 1111 to 3s-8s, In can be sufficiently diffused, preventing the problem of increased defect density due to insufficient In diffusion. For example, by controlling the growth time of each In-doped β-Ga2O3 layer 1111 to be 3s-8s and the growth time of each non-In-doped β-Ga2O3 layer 1112 to be 6s-16s, the thickness of each In-doped β-Ga2O3 layer 1111 and each non-In-doped β-Ga2O3 layer 1112 can be controlled within a certain thickness range. This ensures that, with a fixed total thickness of the β-Ga2O3 epitaxial layer 110, the β-Ga2O3 epitaxial layer 110 has a sufficient number of alternating interfaces between In-doped β-Ga2O3 layers 1111 and non-In-doped β-Ga2O3 layers 1112, thereby effectively preventing defects from extending upward from the substrate 100 and preventing defect density caused by lattice distortion. Preferably, the growth time of each In-doped β-Ga2O3 layer 1111 is 6 s, and the growth time of each non-In-doped β-Ga2O3 layer 1112 is 12 s.
[0069] In one example, when growing an In-doped β-Ga2O3 layer 1111 in a β-Ga2O3 epitaxial layer 110 in an MOCVD reaction chamber, the Ga source is TEGa, and the Ga source flow rate is 700 sccm-1000 sccm, for example, the Ga source flow rate can be 700 sccm, 800 sccm, 900 sccm, or 1000 sccm; the In source is TMI (trimethylindium), and the In source flow rate is 2 sccm-10 sccm, for example, the In source flow rate can be 2 sccm, 3 sccm, 4 sccm, 5 sccm, 6 sccm, 7 sccm, 8 sccm, 9 sccm, or 10 sccm; the carrier gas is N2; and the O source is O2. The VI / III ratio is the molar ratio of group VI sources and group III sources introduced into the MOCVD reaction chamber; in this embodiment, the VI / III ratio is the molar ratio of O2 to TEGa introduced into the MOCVD reaction chamber. For example, using TEGa as the Ga source can improve the problem of crystal quality degradation caused by In doping, so as to obtain an In-doped β-Ga2O3 layer with higher crystal quality.
[0070] In one example, when growing a non-In-doped β-Ga2O3 layer 1112 within a β-Ga2O3 epitaxial layer 110 in an MOCVD reaction chamber, the Ga source is TMGa, and the Ga source flow rate is 300 sccm-700 sccm, for example, the Ga source flow rate can be 300 sccm, 400 sccm, 500 sccm, 600 sccm, or 700 sccm; the carrier gas is N2; and the O source is O2. The VI / III ratio is the molar ratio of group VI sources and group III sources introduced into the MOCVD reaction chamber; in this embodiment, the VI / III ratio is the molar ratio of O2 to TMGa introduced into the MOCVD reaction chamber. Exemplarily, using TMGa as the Ga source can improve the growth rate of the non-In-doped β-Ga2O3 layer 1112. For example, growing a non-In-doped β-Ga2O3 layer 1112 at 800℃-1000℃ can reduce defect density and improve crystal quality; at the same time, the non-In-doped β-Ga2O3 layer 1112 has higher crystal quality because it is not doped with In.
[0071] In one example, before forming the β-Ga2O3 epitaxial layer 110, the substrate 100 is further subjected to annealing and desorption treatment. Taking the substrate 100 as a Sn-doped (001) Ga2O3 substrate as an example, the annealing and desorption treatment of the substrate 100 includes: placing the substrate 100 in the MOCVD reaction chamber, treating the substrate 100 in an oxygen atmosphere for 5 min-20 min, and controlling the temperature at 800℃-1000℃ for high-temperature in-situ annealing pretreatment; then, maintaining the temperature at 800℃-1000℃, the pressure at 100mbar-200mbar, and the time for 3 min-10 min to perform desorption treatment on the substrate 100 to remove impurities and organic contaminants from the surface of the substrate 100.
[0072] In one example, after forming the β-Ga2O3 epitaxial layer 110, a cooling process is included for the β-Ga2O3 epitaxial structure: the carrier gas is oxygen or oxygen plus nitrogen; the MOCVD reaction chamber temperature is controlled at 800℃-1000℃; the pressure is controlled at 20mbar-80mbar; and the duration is 3min-10min. Then, the MOCVD reaction chamber temperature is reduced to below 150℃. This cooling process alleviates the problem of increased roughness in the β-Ga2O3 epitaxial structure due to rapid cooling.
[0073] In one example, such as Figure 1As shown, each stacked structure includes, from bottom to top, an In-doped β-Ga₂O₃ layer 1111 and a non-In-doped β-Ga₂O₃ layer 1112; or, as shown... Figure 2 As shown, each stacked structure includes a non-In-doped β-Ga2O3 layer 1112 and an In-doped β-Ga2O3 layer 1111 stacked sequentially from bottom to top.
[0074] In one example, during the epitaxial growth of β-Ga2O3, the anisotropy of surface energy and atomic diffusion ability, as well as the competition between the film growth and etching reactions (Ga2O desorption), lead to step coalescence and trench undulation problems, resulting in significant surface undulations and a sharp increase in surface roughness of the β-Ga2O3 epitaxial layer. The β-Ga2O3 epitaxial layer 110 of this application includes an In-doped β-Ga2O3 layer 1111. The In doping in the In-doped β-Ga2O3 layer 1111 can suppress the formation and desorption of Ga2O during epitaxial growth and enhance the adsorption capacity of Ga atoms on the surface, optimizing the β-Ga2O3 growth process. The co-adsorption of Ga atoms and In atoms can promote the transformation of the epitaxial film growth mode from an island-like growth mode to a step-flow growth mode, stabilizing surface thermal fluctuations during epitaxial film growth, suppressing trench morphology, effectively solving the problems of step coalescence and trench undulation, reducing surface roughness, and increasing the growth rate.
[0075] In one example, alternating growth of In-doped β-Ga₂O₃ layers 1111 and non-In-doped β-Ga₂O₃ layers 1112 effectively prevents defects from extending upwards from the substrate 100. For instance, when a device layer is formed on the β-Ga₂O₃ epitaxial structure, the alternating growth of In-doped β-Ga₂O₃ layers 1111 and non-In-doped β-Ga₂O₃ layers 1112 effectively prevents defects from extending from the substrate 100 towards the device layer, thereby improving the crystal quality of the β-Ga₂O₃ epitaxial structure. Simultaneously, the alternating growth of In-doped β-Ga₂O₃ layers 1111 and non-In-doped β-Ga₂O₃ layers 1112 also effectively prevents the problem of increased defect density due to lattice distortion.
[0076] In one example, the number of stacked structures 111 is greater than or equal to 800 to obtain a β-Ga2O3 epitaxial structure with a certain thickness, for example, a β-Ga2O3 epitaxial structure with a thickness greater than 3 μm. Exemplarily, the number of stacked structures 111 is also less than or equal to 1800 to prevent excessively long growth time.
[0077] In summary, the method for manufacturing β-Ga2O3 epitaxial structures in this application forms β-Ga2O3 epitaxial layers comprising multiple stacked structures, each stacked structure including stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers. This method can improve the crystal quality and growth rate of β-Ga2O3 epitaxial structures while obtaining β-Ga2O3 epitaxial structures with a certain thickness, and reduce the surface roughness of β-Ga2O3 epitaxial structures.
[0078] Example 3
[0079] In another embodiment of this application, a semiconductor device is provided, which includes the β-Ga2O3 epitaxial structure described in Embodiment 1, or the β-Ga2O3 epitaxial structure manufactured using the manufacturing method described in Embodiment 2, wherein the semiconductor device can be a power semiconductor device.
[0080] Although several embodiments have been described herein, it should be understood that many other modifications and embodiments will arise in the mind of those skilled in the art, all of which will fall within the spirit and scope of the concept disclosed herein. More specifically, various modifications and changes may be made in terms of the arrangement and / or components of the subject matter within the scope of this disclosure, the drawings, and the appended claims. In addition to modifications and changes in the components and / or arrangement, the use of alternative methods will also be obvious to those skilled in the art.
Claims
1. A β-Ga₂O₃ epitaxial structure, characterized in that, include: Substrate; A β-Ga2O3 epitaxial layer is located on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures, each of which includes stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers.
2. The β-Ga₂O₃ epitaxial structure according to claim 1, characterized in that, Each of the stacked structures comprises, from bottom to top, the In-doped β-Ga₂O₃ layer and the non-In-doped β-Ga₂O₃ layer; or, Each of the stacked structures includes, from bottom to top, the undoped β-Ga2O3 layer and the indoped β-Ga2O3 layer.
3. The β-Ga₂O₃ epitaxial structure according to claim 1, characterized in that, The In-doped β-Ga2O3 layer is formed under a first temperature, a first pressure, and a first VI / III ratio, wherein the first temperature ranges from 780°C to 880°C, the first pressure ranges from 15 mbar to 40 mbar, the first VI / III ratio ranges from 300 to 420, and the growth time of each In-doped β-Ga2O3 layer is 3 s to 8 s. The non-In-doped β-Ga2O3 layer is formed at a second temperature, a second pressure, and a second VI / III ratio, wherein the second temperature ranges from 885℃ to 1000℃, the second pressure ranges from 45mbar to 100mbar, the second VI / III ratio ranges from 160 to 295, and the growth time of each non-In-doped β-Ga2O3 layer is 6s to 16s.
4. The β-Ga2O3 epitaxial structure according to claim 3, characterized in that, The first temperature is 850°C, the first pressure is 35 mbar, the first VI / III ratio is 320, and the growth time of each In-doped β-Ga2O3 layer is 6 s. The second temperature is 930°C, the second pressure is 55 mbar, the second VI / III ratio is 220, and the growth time of each layer of the non-In-doped β-Ga2O3 layer is 12 s.
5. A method for manufacturing a β-Ga2O3 epitaxial structure, characterized in that, include: Provide substrate; A β-Ga2O3 epitaxial layer is formed on the substrate. The β-Ga2O3 epitaxial layer includes multiple stacked structures, each of which includes stacked In-doped β-Ga2O3 layers and non-In-doped β-Ga2O3 layers.
6. The manufacturing method according to claim 5, characterized in that, The In-doped β-Ga2O3 layer is grown in an MOCVD reaction chamber. The In-doped β-Ga2O3 layer is formed at a first temperature, a first pressure, and a first VI / III ratio, wherein the first temperature ranges from 780°C to 880°C, the first pressure ranges from 15 mbar to 40 mbar, the first VI / III ratio ranges from 300 to 420, and the growth time of each In-doped β-Ga2O3 layer is 3 s to 8 s. The undoped β-Ga2O3 layer is grown in the MOCVD reaction chamber. The undoped β-Ga2O3 layer is formed at a second temperature, a second pressure, and a second VI / III ratio. The second temperature ranges from 885℃ to 1000℃, the second pressure ranges from 45mbar to 100mbar, the second VI / III ratio ranges from 160 to 295, and the growth time of each undoped β-Ga2O3 layer is 6s to 16s.
7. The manufacturing method according to claim 6, characterized in that, The first temperature is 850°C, the first pressure is 35 mbar, the first VI / III ratio is 320, and the growth time of each In-doped β-Ga2O3 layer is 6 s. The second temperature is 930°C, the second pressure is 55 mbar, the second VI / III ratio is 220, and the growth time of each layer of the non-In-doped β-Ga2O3 layer is 12 s.
8. The manufacturing method according to claim 6, characterized in that, When the In-doped β-Ga2O3 layer is grown in the MOCVD reaction chamber, the Ga source is TEGa with a flow rate of 700 sccm-1000 sccm, and the In source is TMI with a flow rate of 2 sccm-10 sccm. When the undoped β-Ga2O3 layer is grown in the MOCVD reaction chamber, the Ga source is TMGa and the Ga source flow rate is 300 sccm-700 sccm.
9. The manufacturing method according to claim 5, characterized in that, Before forming the β-Ga2O3 epitaxial layer, the process further includes annealing and desorption treatment of the substrate.
10. A semiconductor device, characterized in that, It includes the β-Ga2O3 epitaxial structure according to any one of claims 1-4, or it includes the β-Ga2O3 epitaxial structure obtained by the manufacturing method according to any one of claims 5-9.