Photoelectric detector and manufacturing method thereof
By setting a doped region on the first optical waveguide of the photodetector and optimizing its width structure, the problem of difficulty in taking into account the responsiveness and bandwidth of the existing silicon photodetector is solved, and the effects of high responsiveness and high bandwidth are achieved.
Patent Information
- Application Number
- CN202311316878.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-11
- Publication Date
- 2025-04-15
AI Technical Summary
Existing silicon photodetectors have difficulties in taking into account both responsiveness and bandwidth, mainly due to the blocky germanium waveguide structure.
A photodetector is designed with an upper width of the first optical waveguide smaller than a lower width and by providing first and second doped regions on a first optical waveguide extending in a first direction on the substrate surface to improve the responsiveness and bandwidth of the device.
By optimizing the structure of the photodetector, high responsiveness and bandwidth are achieved, meeting the improvement of data capacity requirements of optical communication technology.
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Figure CN119836016A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor technology, and in particular to a photodetector and a method for manufacturing the same. Background Art
[0002] The photodetector is a device responsible for photoelectric conversion in the silicon photonic transceiver module. It absorbs incident light and converts it into an electrical signal output. Both responsiveness and bandwidth are core performance indicators of the detector.
[0003] At present, the main bands used by silicon photonic integrated chips are 1310nm and 1550nm, and the active area material is mainly germanium. With the continuous development of optical communication technology, the demand for data capacity has increased. How to further improve the integration and device response speed (i.e., bandwidth) is an issue that must be considered.
[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention
[0005] For laterally doped photodetectors, on the one hand, the increase in the width of the germanium waveguide will reduce the response speed (i.e., bandwidth) of the device, but on the other hand, the increase in the size of the germanium waveguide will help to increase the amount of light entering the germanium waveguide to a certain extent, thereby improving the responsivity.
[0006] The inventors of the present application have discovered that the current mainstream silicon photodetectors mainly rely on bulk germanium waveguides for light absorption. Under this structure, it is difficult to balance the responsiveness and bandwidth of the photodetector.
[0007] An embodiment of the present application provides a photodetector and a method for manufacturing the same. In the photodetector, the upper width of a first optical waveguide serving as an active region is smaller than the lower width, thereby enabling the photodetector to have higher responsiveness and bandwidth.
[0008] According to one aspect of an embodiment of the present application, a photodetector is provided, the photodetector comprising:
[0009] A first optical waveguide, which is disposed on a surface of the substrate and extends along a first direction;
[0010] A first doping region having a first doping type and located on one side of the first optical waveguide in a second direction; and
[0011] a second doping region having a second doping type different from the first doping type and located on the other side of the first optical waveguide in the second direction,
[0012] The first direction and the second direction are parallel to the surface of the substrate, and the first direction intersects the second direction,
[0013] The first optical waveguide comprises a first portion and a second portion,
[0014] In a third direction perpendicular to the surface of the substrate, the first portion is closer to the surface of the substrate than the second portion,
[0015] A dimension of at least a portion of the second portion in the second direction is smaller than a dimension of at least a portion of the first portion in the second direction.
[0016] According to another aspect of the embodiment of the present application, the first optical waveguide has a bottom surface close to the surface of the substrate and a top surface far from the surface of the substrate.
[0017] A size of the top surface in the second direction is smaller than a size of the bottom surface in the second direction.
[0018] According to another aspect of the embodiment of the present application, on a cross section perpendicular to the first direction,
[0019] The second portion is a quadrilateral, and the first portion is a quadrilateral.
[0020] According to another aspect of the embodiment of the present application, on a cross section perpendicular to the first direction,
[0021] A side wall of the first portion and / or the second portion is parallel to the third direction.
[0022] According to another aspect of the embodiment of the present application, on a cross section perpendicular to the first direction,
[0023] A center of the first portion in the second direction is aligned with a center of the second portion in the second direction.
[0024] According to another aspect of the embodiment of the present application, the photodetector further includes:
[0025] A second optical waveguide extends along the first direction, wherein a top surface of the second optical waveguide contacts the bottom surface of the first optical waveguide.
[0026] According to another aspect of the embodiment of the present application, a size of a bottom surface of the first optical waveguide in the second direction is greater than or equal to a size of a top surface of the second optical waveguide in the second direction.
[0027] According to another aspect of the embodiment of the present application, the first optical waveguide and the first doping region and the second doping region are made of different materials.
[0028] According to another aspect of the embodiments of the present application, a method for manufacturing a photodetector is provided, for manufacturing the photodetector as described in any one of the above embodiments, the manufacturing method comprising:
[0029] doping a top layer of silicon of a silicon-on-insulator substrate to form a first doped region and a second doped region;
[0030] Etching the top silicon between the first doping region and the second doping region to a predetermined depth to form a groove, wherein the top silicon remaining undoped at the bottom of the groove serves as a second optical waveguide;
[0031] Depositing a predetermined thickness of waveguide material on the top silicon surface; and
[0032] The waveguide material is etched to form a first optical waveguide extending along a first direction, wherein the first doped region and the second doped region are located on both sides of the first optical waveguide in a second direction,
[0033] in,
[0034] The first optical waveguide comprises a first portion and a second portion,
[0035] In a third direction perpendicular to the surface of the silicon-on-insulator substrate, the first portion is closer to the surface of the silicon-on-insulator substrate than the second portion,
[0036] A dimension of at least a portion of the second portion in the second direction is smaller than a dimension of at least a portion of the first portion in the second direction.
[0037] The beneficial effect of the present application is that in the photodetector, the upper width of the first optical waveguide as the active region is smaller than the lower width, thereby enabling the photodetector to have higher responsiveness and bandwidth.
[0038] With reference to the following description and accompanying drawings, the specific embodiments of the present application are disclosed in detail, indicating the way 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. Within the scope of the spirit and clauses of the appended claims, the embodiments of the present application include many changes, modifications and equivalents.
[0039] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.
[0040] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] The included drawings are used to provide a further understanding of the embodiments of the present application, which constitute a part of the specification, are used to illustrate the implementation methods of the present application, and together with the text description, explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:
[0042] Figure 1 is a cross-sectional schematic diagram of the photodetector of Example 1 of the present application;
[0043] Figure 2 is an enlarged schematic diagram of the first optical waveguide 1;
[0044] Figure 3 is another enlarged schematic diagram of the first optical waveguide 1;
[0045] Figure 4 A schematic diagram of the manufacturing method of the photodetector. DETAILED DESCRIPTION
[0046] With reference to the accompanying drawings, the above and other features of the present application will become apparent through the following description. In the description and the accompanying 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 attached claims.
[0047] In the description of each embodiment of the present application, for the convenience of description, the direction parallel to the surface of the substrate is called "lateral", and the direction perpendicular to the surface of the substrate is called "longitudinal", wherein the "thickness" of each component refers to the size 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 called the "up" direction, and the direction opposite to the "up" direction is the "down" direction.
[0048] In various embodiments of the present application, the first direction D1 and the second direction D2 may be parallel to the above-mentioned transverse direction, and the first direction D1 and the second direction D2 may intersect, for example, the first direction D1 may be the length direction of the first optical waveguide, and the second direction D2 may be the width direction of the first optical waveguide. The third direction D3 may be the thickness direction of the first optical waveguide (i.e., the above-mentioned longitudinal direction).
[0049] Example 1
[0050] An embodiment of the present application provides a photoelectric detector.
[0051] Figure 1 It is a cross-sectional schematic diagram of the photodetector of Example 1 of the present application, showing the structure of the photodetector in a cross section perpendicular to the first direction.
[0052] like Figure 1 As shown, the photodetector 100 includes: a first optical waveguide 1 , a first doping region 2 and a second doping region 3 .
[0053] The first optical waveguide 1 is disposed on the surface of the substrate 200 and extends along a first direction D1;
[0054] The first doping region 2 has a first doping type and is located at one side of the first optical waveguide 1 in the second direction D2;
[0055] The second doping region 3 has a second doping type different from the first doping type, and is located at the other side of the first optical waveguide 1 in the second direction D2.
[0056] For example, the first doping type is P type, and the second doping type is N type. For another example, the first doping type is N type, and the second doping type is P type.
[0057] Thus, the first doping region 2 and the second doping region 3 are respectively located on both sides of the first optical waveguide 1 in the width direction, and the photodetector 100 is formed as a laterally doped photodetector.
[0058] like Figure 1 As shown, the first doping region 2 may include a first lightly doped region 21 and a first heavily doped region 22 distributed in the second direction D2, wherein the doping concentration of the first heavily doped region 22 is higher than that of the first lightly doped region 21, and the first lightly doped region 21 is in contact with the first optical waveguide 1. The second doping region 3 may include a second lightly doped region 31 and a second heavily doped region 32 distributed in the second direction D2, wherein the doping concentration of the second heavily doped region 32 is higher than that of the second lightly doped region 31, and the second lightly doped region 31 is in contact with the first optical waveguide 1.
[0059] The first heavily doped region 22 may be in contact with the first electrode 41, and the second heavily doped region 32 may be in contact with the second electrode 42. The first electrode 41 and the second electrode 42 may be a conductive material, for example, aluminum (Al) or the like.
[0060] In the present application, the materials of the first optical waveguide 1 and the first doping region 2 and the second doping region 3 may be different. For example, the material of the first optical waveguide 1 includes germanium (Ge), for example, the material of the first optical waveguide 1 is Ge, Ge-Si or GeSn. The material of the second doping region 2 and the third doping region 3 may be silicon, for example, single crystal silicon, polycrystalline silicon or amorphous silicon.
[0061] like Figure 1 As shown, the first optical waveguide 1 includes a first portion 11 and a second portion 12. In a third direction D3 perpendicular to the surface of the substrate 200, the first portion 11 is closer to the surface of the substrate 200 than the second portion 12, that is, the first portion 11 is located below the second portion 12. The size of at least a portion of the second portion 12 in the second direction D2 is smaller than the size of at least a portion of the first portion 11 in the second direction D2.
[0062] According to the present application, the width of at least a portion of the first portion 11 of the first optical waveguide 1 is relatively large, thereby facilitating more light coupling into the first optical waveguide 1, thereby improving the responsiveness of the photodetector 100; and, according to the theoretical bandwidth formula of the laterally doped photodetector, the width of at least a portion of the second portion 12 of the first optical waveguide 1 is relatively small, and the bandwidth dominated by the transit time will be larger, thereby improving the bandwidth of the photodetector 100. In addition, the width of at least a portion of the second portion 12 is relatively small, which can still ensure that the light is confined to the interior of the first optical waveguide.
[0063] Through the embodiments of the present application, the photodetector 100 can have both good responsivity and bandwidth.
[0064] like Figure 1 As shown, the photodetector 100 further includes: a second optical waveguide 5. The second optical waveguide 5 extends along the first direction D1, and the top surface 51 of the second optical waveguide 5 contacts the bottom surface 111 of the first optical waveguide 1. Thus, the light guided by the second optical waveguide 5 can be coupled into the first optical waveguide 1 for absorption.
[0065] In the present application, the second optical waveguide 5 and the first doping region 2 and the second doping region 3 may be made of the same material. For example, the second optical waveguide 5, the second doping region 2 and the third doping region 3 may all be made of silicon.
[0066] The size of the bottom surface 111 of the first optical waveguide 1 in the second direction D2 is greater than or equal to the size of the top surface 51 of the second optical waveguide 5 in the second direction D2, that is, the width of the bottom surface 111 of the first optical waveguide 1 is greater than or equal to the width of the top surface 51 of the second optical waveguide 5. Thus, as much light as possible can be coupled into the first optical waveguide 1, thereby improving the responsivity.
[0067] like Figure 1 As shown, the photodetector 100 further includes: a passivation layer 6, an isolation layer 7 and a support layer 8. The passivation layer 6 can cover the first optical waveguide 1, the first doping region 2 and the second doping region 3, so as to protect the device. The material of the passivation layer 6 is, for example, silicon oxide or silicon nitride.
[0068] The isolation layer 7 may be located below the second optical waveguide 5, the first doping region 2, and the second doping region 3. For example, the isolation layer 7 may be a buried oxide layer of a silicon on insulator (SOI) substrate, or the like.
[0069] The support layer 8 may be located below the isolation layer 7 to support the isolation layer 7. The material of the support layer 8 may be silicon. For example, the support layer 8 may be substrate silicon of a silicon on insulator (SOI) substrate, etc.
[0070] In addition, the second optical waveguide 5, the first doped region 2 and the second doped region 3 of the present application can be formed by etching and / or ion implanting the top silicon of the silicon on insulator (SOI) substrate. The first optical waveguide 1 can be formed by epitaxially growing a material containing Ge on the top silicon surface of the silicon on insulator (SOI) substrate and etching the material containing Ge.
[0071] In an example of the present application, the substrate 200 may include an isolation layer 7 and a support layer 8 .
[0072] Figure 2 is an enlarged schematic diagram of the first optical waveguide 1. Figure 2 As shown, the first optical waveguide 1 has a top surface 121 and a bottom surface 111, wherein the top surface 121 is far away from the surface of the substrate, and the bottom surface 111 is close to the surface of the substrate. For example, the bottom surface 111 contacts the top surface 51 of the second optical waveguide 5 (as shown in FIG. Figure 1 shown).
[0073] like Figure 2 As shown, the size of the top surface 121 in the second direction D2 is smaller than the size of the bottom surface 111 in the second direction D2, that is, the width of the top surface 121 is smaller than the width of the bottom surface 111. Therefore, the bottom surface 111 of the first optical waveguide 1 has a larger width, which can improve the responsivity; the top surface 121 of the first optical waveguide 1 has a smaller width, which can improve the bandwidth.
[0074] like Figure 2 As shown, in at least one embodiment, in a cross section perpendicular to the first direction D1, the second portion 12 is a quadrilateral, and the first portion 11 is a quadrilateral.
[0075] For example, in a cross section perpendicular to the first direction D1, the sidewall 11a of the first portion 11 and / or the sidewall 12a of the second portion 12 are parallel to the third direction D3, that is, the cross section of the first portion 11 is rectangular, and the cross section of the second portion 12 is rectangular, wherein the width of the second portion 12 is less than the width of the first portion 11, and the width of the second portion 12 is greater than or equal to 1 / 2 of the width of the first portion 11, the height of the first portion 11 may be, for example, 130nm, and the height of the second portion 12 may be, for example, 100nm to 300nm. In addition, the above dimensions are only examples, and the above dimensions may be adjusted as needed to adjust the performance of the device.
[0076] In addition, the present application may not be limited to this. For example, the side wall 11a of the first part 11 and / or the side wall 12a of the second part 12 may also be inclined relative to the third direction D3, that is, the cross-section of the first part 11 may be a trapezoid, and the cross-section of the second part 12 may be a trapezoid or a triangle.
[0077] like Figure 2 As shown, in a cross section perpendicular to the first direction D1, the center O1 of the first portion 11 in the second direction D2 is aligned with the center O2 of the second portion 12 in the second direction D2 (i.e., O1 and O2 are located at the same position in the second direction). Thus, the first optical waveguide 1 has a bilaterally symmetrical structure.
[0078] In addition, the present application may not be limited thereto. For example, the center O1 of the first portion 11 in the second direction D2 may not be aligned with the center O2 of the second portion 12 in the second direction D2. Figure 3 shown.
[0079] exist Figure 2 In the embodiment, the cross section of the first optical waveguide 1 is a ridge shape, but the present application is not limited thereto, and the cross section of the first optical waveguide 1 may also be other shapes.
[0080] According to the present application, at least a portion of the first portion 11 of the first optical waveguide 1 has a larger width, thereby facilitating more light coupling into the first optical waveguide 1, thereby improving the responsiveness of the photodetector 100; and at least a portion of the second portion 12 of the first optical waveguide 1 has a smaller width, which can improve the bandwidth of the photodetector 100; in addition, at least a portion of the second portion 12 has a smaller width, which can still ensure that the light is confined to the interior of the first optical waveguide.
[0081] Example 2
[0082] The embodiment of the present application provides a method for manufacturing a photodetector, which is used to manufacture the photodetector 100 described in Embodiment 1.
[0083] Figure 4 is a schematic diagram of the method for manufacturing a photodetector, such as Figure 4 As shown, the manufacturing method includes:
[0084] Operation 401, doping a top layer of silicon on an insulator (SOI) substrate to form a first doping region 2 and a second doping region 3;
[0085] Operation 402, etching the top silicon between the first doping region 2 and the second doping region 3 to a predetermined depth to form a groove, and the undoped top silicon remaining at the bottom of the groove is formed into a second optical waveguide 5;
[0086] Operation 403, depositing a waveguide material of a predetermined thickness on the surface of the top silicon layer, wherein the waveguide material is deposited by, for example, epitaxy; and
[0087] Operation 404 : Etching the waveguide material to form a first optical waveguide 1 extending along the first direction D1 , wherein the first doping region 2 and the second doping region 3 are located at two sides of the first optical waveguide 1 in the second direction D2 .
[0088] In the present application, the first optical waveguide 1 includes a first portion 11 and a second portion 12. In a third direction D3 perpendicular to the surface of the silicon-on-insulator substrate, the first portion 11 is closer to the surface of the silicon-on-insulator substrate than the second portion 12. A size of at least a portion of the second portion 12 in the second direction D2 is smaller than a size of at least a portion of the first portion 11 in the second direction D2.
[0089] In the photodetector obtained by the manufacturing method of the present application, at least a portion of the first part 11 of the first optical waveguide 1 has a larger width, thereby facilitating more light coupling into the first optical waveguide 1, thereby improving the responsiveness of the photodetector 100; and, at least a portion of the second part 12 of the first optical waveguide 1 has a smaller width, which can improve the bandwidth of the photodetector 100; in addition, at least a portion of the second part 12 has a smaller width, which can still ensure that the light is confined to the interior of the first optical waveguide.
[0090] The present application is described above in conjunction with specific implementation methods, but it should be clear to those skilled in the art that these descriptions are exemplary and are not intended to limit the scope of protection of the present application. Those skilled in the art can make various modifications and variations to the present application based on the spirit and principles of the present application, and these modifications and variations are also within the scope of the present application.
Claims
1. A photoelectric detector, characterized in that: The photodetector comprises: A first optical waveguide, which is disposed on a surface of the substrate and extends along a first direction; A first doping region having a first doping type and located on one side of the first optical waveguide in a second direction; and a second doping region having a second doping type different from the first doping type and located on the other side of the first optical waveguide in the second direction, in, The first direction and the second direction are parallel to the surface of the substrate, and the first direction intersects the second direction, The first optical waveguide comprises a first portion and a second portion, In a third direction perpendicular to the surface of the substrate, the first portion is closer to the surface of the substrate than the second portion, A dimension of at least a portion of the second portion in the second direction is smaller than a dimension of at least a portion of the first portion in the second direction.
2. The photodetector according to claim 1, wherein: The first optical waveguide has a bottom surface close to the surface of the substrate and a top surface far from the surface of the substrate, A size of the top surface in the second direction is smaller than a size of the bottom surface in the second direction.
3. The photodetector according to claim 1, wherein: On a cross section perpendicular to the first direction, The second portion is a quadrilateral, and the first portion is a quadrilateral.
4. The photodetector according to claim 1, wherein: On a cross section perpendicular to the first direction, A side wall of the first portion and / or the second portion is parallel to the third direction.
5. The photodetector according to claim 1, wherein: On a cross section perpendicular to the first direction, A center of the first portion in the second direction is aligned with a center of the second portion in the second direction.
6. The photodetector according to claim 2, wherein: The photodetector further comprises: A second optical waveguide extends along the first direction, wherein a top surface of the second optical waveguide contacts the bottom surface of the first optical waveguide.
7. The photodetector according to claim 6, wherein: A dimension of a bottom surface of the first optical waveguide in the second direction is greater than or equal to a dimension of a top surface of the second optical waveguide in the second direction.
8. The photodetector according to claim 1, wherein: The first optical waveguide and the first doping region and the second doping region are made of different materials.
9. A method for manufacturing a photodetector, for manufacturing the photodetector according to any one of claims 1 to 8, characterized in that: The manufacturing method comprises: doping a top layer of silicon of a silicon-on-insulator substrate to form a first doped region and a second doped region; Etching the top silicon between the first doping region and the second doping region to a predetermined depth to form a groove, wherein the undoped top silicon remaining at the bottom of the groove serves as a second optical waveguide; Depositing a predetermined thickness of waveguide material on the top silicon surface; and The waveguide material is etched to form a first optical waveguide extending along a first direction, wherein the first doped region and the second doped region are located on both sides of the first optical waveguide in a second direction, in, The first optical waveguide comprises a first portion and a second portion, In a third direction perpendicular to the surface of the silicon-on-insulator substrate, the first portion is closer to the surface of the silicon-on-insulator substrate than the second portion, A dimension of at least a portion of the second portion in the second direction is smaller than a dimension of at least a portion of the first portion in the second direction.