Photoelectric detector and manufacturing method thereof
By using contact electrodes made of transparent conductive materials in the photodetector, the problems of metal electrode size limitations and the challenges of the light absorbing layer epitaxial process in the prior art are solved, and higher responsiveness and performance parameters are achieved.
Patent Information
- Application Number
- CN202311770259.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-20
- Publication Date
- 2025-06-27
AI Technical Summary
While improving the responsiveness, existing silicon-based germanium photodetectors face metal electrode size limitations and light absorption layer epitaxial process challenges.
The contact electrode made of transparent conductive material is in contact with the surface of the light absorbing layer, thereby improving the responsiveness of the photodetector and reducing the requirements for the contact electrode size and the epitaxial process of the light absorbing layer.
The responsiveness of the photodetector is improved, the requirements for contact electrode size and light absorption layer epitaxial process are reduced, and higher performance parameters are provided.
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Figure CN120224840A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and particularly to a photodetector and a manufacturing method thereof. Background Art
[0002] Silicon-based optoelectronic integration technology, with its advantages of high-density integration, low cost, and low power consumption, has become a promising solution for high-speed optical communication systems. As an indispensable component for converting received optical signals into electrical signals, silicon-based germanium photodetectors have received extensive attention.
[0003] In recent years, research institutions at home and abroad have reported many high-performance silicon-based germanium photodetectors by optimizing device structure design and fabrication processes, etc. However, since these performance parameters of the detector such as bandwidth and responsivity are mutually restrictive, in order to improve the responsivity of the device while ensuring the device bandwidth, generally two solutions can be adopted: The first solution is to make the size of the metal electrode above the germanium detector small, and place the metal electrode at an off-center position or make the metal electrode into a segmented structure, so as to reduce the absorption of the optical signal in germanium by the metal; The second solution is to directly remove the metal electrode above germanium and make the photodetector into a lateral PIN junction structure.
[0004] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solution of this application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art just because these solutions are described in the background art part of this application. Summary of the Invention
[0005] The inventors of this application have found that the above solutions for improving the responsivity of photodetectors have some limitations. For example: In the first solution, due to the limitations of the fabrication process of the photodetector (such as contact hole etching, etc.), the size of the metal electrode cannot be too small; In the second solution, in order to reduce the carrier transit time to ensure the bandwidth of the photodetector, the device width needs to be made very narrow (such as 0.5um), which is a challenge for the germanium epitaxial process.
[0006] An embodiment of this application provides a photodetector and a manufacturing method thereof. In this photodetector, the contact electrode in contact with the surface of the light absorption region is made of a transparent conductive material. Thus, the responsivity of the photodetector can be improved, and the requirements for the size of the contact electrode and the epitaxial process of the light absorption layer are less.
[0007] According to one aspect of the embodiments of this application, a photodetector is provided. The photodetector includes:
[0008] A first doped region, which is disposed on a substrate and has a first doping type;
[0009] A light absorption layer disposed on the surface of the first doped region; and
[0010] A contact electrode in contact with the surface of the light absorption layer, the contact electrode being made of a transparent conductive material.
[0011] In at least one embodiment, the transparent conductive material includes a transparent conductive oxide (TCO).
[0012] In at least one embodiment, a first contact region is formed on the upper portion of the light absorption layer, the top of the first contact region being in contact with the contact electrode, and the first contact region having a second doping type.
[0013] In at least one embodiment, the photodetector further includes:
[0014] A first electrode connected to the contact electrode.
[0015] In at least one embodiment, the first doped region includes:
[0016] A first doped sub-region whose surface is in contact with the light absorption layer; and
[0017] A second doped sub-region that is laterally connected to the first doped sub-region,
[0018] The doping concentration of the second doped sub-region is higher than that of the first doped sub-region.
[0019] In at least one embodiment, the photodetector further includes:
[0020] A second electrode connected to the second doped sub-region.
[0021] In at least one embodiment, the photodetector further includes:
[0022] An insulating protective layer covering the side surface of the light absorption layer and a part of the surface of the first doped region.
[0023] In at least one embodiment, the material of the light absorption layer includes germanium.
[0024] According to an embodiment of another aspect of the present application, there is provided a method for manufacturing a photodetector for manufacturing the photodetector according to any one of the above embodiments, the manufacturing method including:
[0025] Doping the top layer silicon of a silicon substrate on insulator to form a first doped region;
[0026] Growing a light absorption layer on the surface of the first doped region;
[0027] Dope the upper part of the light absorption layer to form a first contact region; and
[0028] Form a contact electrode on the surface of the first contact region, the contact electrode being made of a transparent conductive material.
[0029] In at least one embodiment, the manufacturing method further includes:
[0030] Deposit an insulating protective layer to cover the surface of the first doping region, the surface of the contact electrode, and the side surface of the light absorption layer;
[0031] Etch the insulating protective layer to form an opening; and
[0032] Deposit electrode material in the opening to form a first electrode connected to the contact electrode and a second electrode connected to a second doping sub-region of the first doping region.
[0033] The beneficial effect of the present application is that in a photodetector, the contact electrode in contact with the surface of the light absorption region is made of a transparent conductive material. Thus, the responsivity of the photodetector can be improved, and the requirements for the size of the contact electrode and the epitaxial process of the light absorption layer are less.
[0034] Referring to the following description and the drawings, specific embodiments of the present application are disclosed in detail, indicating the ways in which the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope thereby. Within the spirit and terms of the appended claims, the embodiments of the present application include many changes, modifications, and equivalents.
[0035] Features described and / or illustrated for one embodiment can be used in the same or similar way in one or more other embodiments, combined with features in other embodiments, or substitute for features in other embodiments.
[0036] It should be emphasized that the term "comprising / including" when used herein refers to the presence of features, wholes, steps, or components, but does not exclude the presence or addition of one or more other features, wholes, steps, or components. Description of the Drawings
[0037] The accompanying drawings included are used to provide a further understanding of the embodiments of the present application, which form a part of the specification, are used to illustrate the embodiments of the present application, and together with the written description are used to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. In the drawings:
[0038] Figure 1It is a schematic cross-sectional view of the photodetector according to Embodiment 1 of the present application;
[0039] Figure 2 It is a schematic view of a method for manufacturing a photodetector. Specific embodiments
[0040] Referring to the accompanying drawings and through the following description, the foregoing and other features of the present application will become apparent. In the description and drawings, specific embodiments of the present application are specifically disclosed, which show some embodiments in which the principles of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the present application includes all modifications, variations, and equivalents falling within the scope of the appended claims.
[0041] In the description of the embodiments of the present application, for convenience of description, the direction parallel to the surface of the substrate is referred to as "lateral", and the direction perpendicular to the surface of the substrate is referred to as "longitudinal". Among them, the "thickness" of each component refers to the dimension of the component in the "longitudinal" direction. In the "longitudinal" direction, the direction from the buried oxide layer of the substrate to the top silicon is referred to as the "up" direction, and the direction opposite to the "up" direction is the "down" direction.
[0042] Embodiment 1
[0043] The embodiment of the present application provides a photodetector.
[0044] Figure 1 It is a schematic cross-sectional view of the photodetector according to Embodiment 1 of the present application, showing the structure of the photodetector in a cross-section perpendicular to the surface of the substrate.
[0045] As Figure 1 shown, the photodetector 100 includes: a first doped region 1, a light absorption layer 2, and a contact electrode 3.
[0046] The first doped region 1 can be disposed on the substrate 10. The first doped region 1 can have a first doping type. For example, the first doping type can be a P-type. The light absorption layer 2 is disposed on the surface of the first doped region 1. The contact electrode 3 is in contact with the surface of the light absorption layer 2. Among them, the contact electrode 3 is made of a transparent conductive material. In the present application, the transparent conductive material can be a transparent conductive oxide (TCO), etc. For example, indium tin oxide (ITO), etc.
[0047] In the photodetector 100 of the present application, the contact electrode in contact with the surface of the light absorption layer 2 is made of a transparent conductive material. The transparent conductive material not only realizes the conductive property but also can avoid the absorption of the optical signal in the light absorption layer 2 by directly using a metal, thereby reducing the optical loss, improving the responsivity of the photodetector, and having less requirements for the size of the contact electrode and the epitaxial process of the light absorption layer.
[0048] As Figure 1 shown, the substrate 10 of the present application has a top silicon layer 101, a buried oxide layer 102, and a support layer 103. Among them, the buried oxide layer 102 is an oxide, for example, silicon oxide; the buried oxide layer 102 is located on the surface of the support layer 103, and the support layer 103 can be silicon; the top silicon layer 101 is located on the surface of the buried oxide layer 102, and the top silicon layer 101 can be, for example, single crystal silicon, etc. The substrate 10 can be a silicon-on-insulator (SOI) wafer, or the substrate 10 can be a substrate formed by substrate transfer technology and / or bonding technology.
[0049] In the present application, the first doping region 1 can be formed in the top silicon layer 101. For example, the top silicon layer 101 can be doped (in addition, the top silicon layer 101 can also be further patterned) to form the first doping region 1. The first doping region 1 can include: a first doped sub-region 11 and a second doped sub-region 12. Among them, the surface of the first doped sub-region 11 is in contact with the light absorption layer 2, that is, the light absorption layer 2 is disposed on the surface of the first doped sub-region 11; the second doped sub-region 12 can be laterally connected to the first doped sub-region 11. For example, the second doped sub-region 12 is located on one side or both sides in the lateral direction of the first doped sub-region 11.
[0050] Both the first doped sub-region 11 and the second doped sub-region 12 have the first doping type (for example, both are P-type doping), and the doping concentration of the second doped sub-region 12 can be higher than that of the first doped sub-region 11.
[0051] In the present application, the material of the light absorption layer 2 can include germanium. For example, the material of the light absorption layer 2 can be germanium, germanium silicon, or germanium tin, etc. In the present application, germanium is taken as an example for illustration. The light absorption layer 2 can be formed on the surface of the first doped sub-region 11 by means of epitaxy or the like.
[0052] As Figure 1 shown, a first contact region 21 is formed on the upper part of the light absorption layer 2, and the top of the first contact region 21 is in contact with the contact electrode 3. The first contact region 21 has a second doping type, and the second doping type is different from the first doping type. For example, the second doping type is N-type. In some examples, the first contact region 21 is N-type heavily doped.
[0053] In addition, in the light absorption layer 2, other regions except the first contact region 21 can be undoped, that is, these other regions are undoped intrinsic materials, for example, intrinsic germanium.
[0054] As Figure 1As shown, the photodetector 100 of the present application may further include a first electrode 4 and a second electrode 5. Among them, the first electrode 4 is connected to the contact electrode 3. For example, the first electrode 4 is in surface contact with the contact electrode 3. The second electrode 5 may be connected to the second doped sub-region 12. For example, the second electrode 5 may be in surface contact with the second doped sub-region 12. In addition, the first electrode 4 and the second electrode 5 may be made of a metal material. For example, aluminum or copper, etc.
[0055] As Figure 1 shown, the photodetector 100 further includes: an insulating protective layer 6. The insulating protective layer 6 may cover the side surface of the light absorption layer 2 and a part of the surface of the first doped region 1. For example, the insulating protective layer 6 may be made of materials such as silicon oxide, silicon nitride, or silicon oxynitride.
[0056] An opening may be formed in the insulating protective layer 6 in the regions corresponding to the contact electrode 3 and the second doped sub-region 12 through an etching process, and a metal material may be disposed in the opening to form the first electrode 4 and the second electrode 5.
[0057] According to the embodiments of the present application, when the size of the light absorption layer remains unchanged, the responsivity of the silicon-based germanium photodetector 100 (for example, the silicon-based germanium photodetector) provided by the present application is greatly improved compared with traditional detectors, providing new possibilities for comprehensively improving the performance parameters of the device.
[0058] Embodiment 2
[0059] The embodiments of the present application provide a manufacturing method of a photodetector for manufacturing the photodetector 100 described in Embodiment 1.
[0060] Figure 2 is a schematic diagram of the manufacturing method of the photodetector. As Figure 2 shown, the manufacturing method includes:
[0061] Operation 201: Dope the top silicon of the silicon substrate on insulator to form the first doped region 1;
[0062] Operation 202: Grow a light absorption layer 2 on the surface of the first doped region 1;
[0063] Operation 203: Dope the upper part of the light absorption layer 2 to form the first contact region 21;
[0064] Operation 204: Form a contact electrode 3 on the surface of the first contact region 21, and the contact electrode 3 is made of a transparent conductive material.
[0065] As Figure 2 shown, the manufacturing method further includes:
[0066] Operation 205: Deposit an insulating protective layer 6 to cover the surface of the first doped region 6, the surface of the contact electrode 3, and the side surfaces of the light absorption layer 2;
[0067] Operation 206: Etch the insulating protective layer 6 to form an opening;
[0068] Operation 207: Deposit electrode material in the opening to form a first electrode 4 connected to the contact electrode 3 and a second electrode 5 connected to the second doped sub-region 12 of the first doped region 1.
[0069] According to the embodiments of the present application, without changing the size of the light absorption layer, the responsivity of the silicon germanium photodetector 100 (e.g., silicon germanium photodetector) provided by the present application is greatly improved compared with traditional detectors, providing new possibilities for comprehensively improving the performance parameters of the device.
[0070] The above description has been made in combination with specific embodiments of the present application. However, those skilled in the art should understand that these descriptions are exemplary and not limitations on the protection scope of the present application. Those skilled in the art can make various variations and modifications to the present application according to the spirit and principle of the present application, and these variations and modifications are also within the scope of the present application.
Claims
1. A photodetector, characterized in that, The photodetector includes: A first doped region, which is disposed on a substrate and has a first doping type; A light absorption layer, which is disposed on the surface of the first doped region; and A contact electrode, which is in contact with the surface of the light absorption layer, and the contact electrode is made of a transparent conductive material.
2. The photodetector according to claim 1, wherein The transparent conductive material includes transparent conductive oxide (TCO).
3. The photodetector according to claim 1, wherein A first contact region is formed on the upper portion of the light absorption layer, and the top of the first contact region is in contact with the contact electrode, The first contact region has a second doping type.
4. The photodetector according to claim 1, wherein The photodetector further includes: A first electrode, which is connected to the contact electrode.
5. The photodetector according to claim 1, wherein The first doped region includes: A first doped sub-region, whose surface is in contact with the light absorption layer; and A second doped sub-region, which is laterally connected to the first doped sub-region, The doping concentration of the second doped sub-region is higher than that of the first doped sub-region.
6. The photodetector according to claim 5, wherein The photodetector further includes: A second electrode, which is connected to the second doped sub-region.
7. The photodetector according to claim 1, wherein The photodetector further includes: An insulating protective layer, which covers the side surface of the light absorption layer and a part of the surface of the first doped region.
8. The photodetector according to claim 1, wherein The material of the light absorption layer includes germanium.
9. A manufacturing method of a photodetector for manufacturing the photodetector according to any one of claims 1 to 8, characterized in that, The manufacturing method includes: Doping the top silicon of a silicon-on-insulator substrate to form a first doped region; Growing a light absorption layer on the surface of the first doped region; Doping the upper portion of the light absorption layer to form a first contact region; and Forming a contact electrode on the surface of the first contact region, and the contact electrode is made of a transparent conductive material.
10. The manufacturing method of the photodetector according to claim 9, wherein The manufacturing method further includes: Depositing an insulating protective layer to cover the surface of the first doped region, the surface of the contact electrode, and the side surface of the light absorption layer; Etching the insulating protective layer to form an opening; and Depositing electrode material in the opening to form a first electrode connected to the contact electrode and a second electrode connected to the second doped sub-region of the first doped region.