Photodetector, semiconductor integrated circuit, and integrated chip

Abstract

The present invention relates to the technical field of semiconductors, and in particular to a photodetector, a semiconductor integrated circuit, and an integrated chip. The photodetector comprises a detector, a detector waveguide, and a converter. An output end of the detector waveguide is connected to an input end of the detector; an input end of the converter is connected to a device waveguide, and an output end of the converter is connected to an input end of the detector waveguide; the height of the device waveguide is greater than the height of the detector waveguide; and the height of the converter or the width of a preset area of the converter is gradually reduced in a light transmission direction. Therefore, the high-speed and high-response detection function of the detector can be achieved.

Description

Photodetector, semiconductor integrated circuit and integrated chip

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application with application number 202311452986.1 filed with the Chinese Patent Office on November 2, 2023, entitled “A photodetector, semiconductor integrated circuit and integrated chip”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present invention relates to the field of semiconductor technology, and in particular to a photoelectric detector, a semiconductor integrated circuit and an integrated chip. Background Art

[0004] With the increasing demand for information transmission, high-speed photodetectors have become essential components in communication integrated chip systems. Photodetectors can be classified according to the direction of light incidence, including horizontal photodetectors and vertical photodetectors.

[0005] In order to meet the performance requirements of passive devices, including but not limited to polarization dependence or process tolerance capabilities, the waveguide of the photodetector needs to be designed so that the photodetector can achieve a higher response bandwidth, but existing horizontal detectors cannot achieve the response bandwidth requirement greater than 50 GHz.

[0006] Summary of the Invention

[0007] To solve the above technical problems, the present application discloses, in one aspect, a photodetector comprising:

[0008] detector;

[0009] a detector waveguide, wherein an output end of the detector waveguide is connected to an input end of the detector;

[0010] A converter, wherein the input end of the converter is connected to the device waveguide, and the output end of the converter is connected to the input end of the detector waveguide; the height of the device waveguide is greater than the height of the detector waveguide; the height of the converter or the width of the preset area of ​​the converter gradually decreases along the light transmission direction.

[0011] In an exemplary embodiment, the converter includes a plurality of sub-regions sequentially arranged and connected along the light transmission direction;

[0012] Among the plurality of sub-regions, a sub-region closer to the detector waveguide has a lower height.

[0013] In an exemplary embodiment, the height of the converter varies continuously.

[0014] In an exemplary embodiment, the converter includes a plurality of sub-layers stacked along a first direction; the first direction is a direction from the bottom of the converter toward the top of the converter;

[0015] Among the multiple sub-layers, the width of the sub-layer closer to the top of the converter is smaller.

[0016] In an exemplary embodiment, the width of a target sublayer among the multiple sublayers gradually narrows along the light transmission direction; the target sublayer is a sublayer among the multiple sublayers except the bottommost sublayer.

[0017] In an exemplary embodiment, the height of the detector is smaller than the height of the device waveguide.

[0018] In an exemplary embodiment, the height of the detector waveguide is 0.1 to 0.9 times the height of the device waveguide.

[0019] In an exemplary embodiment, the height of the detector waveguide is 0.5 to 0.7 times the height of the device waveguide;

[0020] The height of the detector waveguide ranges from 0.1 to 3 microns;

[0021] The height of the device waveguide ranges from 0.1 to 5 microns.

[0022] In another aspect, the present application discloses a semiconductor integrated circuit comprising a device, a device waveguide, and the above-mentioned photodetector;

[0023] The output end of the device is connected to the input end of the device waveguide.

[0024] In another aspect, the present application discloses an integrated chip, which includes the above-mentioned semiconductor integrated circuit.

[0025] By adopting the above technical solution, the photoelectric detector provided by this application has the following beneficial effects:

[0026] The photodetector provided in the present application is connected to the detector waveguide and the device waveguide respectively through a set converter, and the height of the device waveguide is greater than the height of the detector waveguide; through the set converter, the height of the converter or the width of the preset area of ​​the converter gradually decreases along the direction of light transmission, thereby realizing the high-speed and high-response detection function of the detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. 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 any creative work.

[0028] FIG1 is a partial cross-sectional view of a conventional integrated chip provided in an embodiment of the present application;

[0029] FIG2 is a cross-sectional view corresponding to the AA′ cross-sectional line of FIG1 provided in an embodiment of the present application;

[0030] FIG3 is a cross-sectional view corresponding to the BB' cross-sectional line of FIG1 provided in an embodiment of the present application;

[0031] FIG4 is a mode field distribution diagram of a TE mode in a polarization-insensitive device waveguide provided in an embodiment of the present application;

[0032] FIG5 is a mode field distribution diagram of a TM mode in a polarization-insensitive device waveguide provided in an embodiment of the present application;

[0033] FIG6 is a mode field distribution diagram of a TE mode in a polarization sensitive device waveguide provided in an embodiment of the present application;

[0034] FIG7 is a mode field distribution diagram of a TM mode in a polarization sensitive device waveguide provided in an embodiment of the present application;

[0035] FIG8 is a partial side view of a first photodetector provided in an embodiment of the present application;

[0036] FIG9 is a side view of a semiconductor integrated circuit corresponding to FIG8 provided in an embodiment of the present application;

[0037] FIG10 is a top view of a structure corresponding to FIG9 provided in an embodiment of the present application;

[0038] FIG11 is a side view of a second photodetector provided in an embodiment of the present application;

[0039] FIG12 is a top view of a structure corresponding to FIG11 provided in an embodiment of the present application;

[0040] FIG13 is a side view of a third photodetector provided in an embodiment of the present application;

[0041] FIG14 is a side view of a fourth photodetector provided in an embodiment of the present application;

[0042] FIG15 is a top view of a structure corresponding to FIG14 provided in an embodiment of the present application.

[0043] The following is a supplementary description of the drawings: 1 - detector waveguide; 2 - converter; 201 - sub-region; 202 - sub-layer; 3 - device waveguide. DETAILED DESCRIPTION

[0044] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0045] References to "one embodiment" or "embodiment" herein refer to specific features, structures, or characteristics that may be included in at least one implementation of the present application. Throughout the description of this application, it should be understood that the terms "upper," "lower," "top," and "bottom," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplification. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, a feature designated "first" or "second" may explicitly or implicitly include one or more of such features. Furthermore, the terms "first," "second," etc. are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential sequence. It should be understood that such terms are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0046] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein. For example, a specified range from "1 to 10" should be considered to include any and all subranges between a minimum of 1 and a maximum of 10. Exemplary subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0047] Example 1:

[0048] Please refer to Figure 1, which shows a partial cross-sectional view of an existing integrated chip provided in an embodiment of the present application. For an integrated chip that integrates a device and a detector, the device and the detector are usually connected through a device waveguide and a detector waveguide to achieve optical transmission. It can be seen from Figures 2 and 3 that the heights of the device waveguide and the detector waveguide are equal, which makes the integrated chip unable to meet the performance of passive devices and the performance of photodetectors with a high speed response greater than 50GHz. Figures 4 to 7 are all mode field distribution diagrams in the device waveguide, and the x and y axes correspond to the horizontal and vertical coordinates on the waveguide cross section, respectively. Figures 4 and 5 are the mode field distributions of the TE and TM modes in the polarization-insensitive device waveguide. Figures 6 and 7 are the mode field distributions of the TE and TM modes in the polarization-sensitive device waveguide. It can be seen from the comparison of Figures 4-7 that in order to achieve polarization-insensitive performance, the device waveguide size requirement cannot be too small.

[0049] To this end, an embodiment of the present application provides a photodetector. See FIG8 , which shows a partial side view of a first photodetector according to an embodiment of the present application. The photodetector comprises a detector, a detector waveguide 1, and a converter 2. The output of the detector waveguide 1 is connected to the input of the detector; the input of the converter 2 is connected to the device waveguide 3, and the output of the converter 2 is connected to the input of the detector waveguide 1. The height of the device waveguide 3 is greater than that of the detector waveguide 1. The height of the converter 2 gradually decreases along the direction of light transmission. Specifically, the height of the converter 2 changes continuously, so that light energy can enter from the left side as shown in FIG8 and be transmitted to the detector waveguide 1 through the converter 2. By designing the height of the detector waveguide 1 to be less than that of the device waveguide 3, this lower height of the detector waveguide 1 reduces the detector capacitance, thereby achieving high-speed detection capabilities. Furthermore, the photodetector provided in this embodiment of the present application can be used in conjunction with passive components, thereby achieving high-speed photodetector performance exceeding 50 GHz while meeting the performance requirements of passive components. Furthermore, the converter 2 disposed between the device waveguide 3 and the detector waveguide 1 can achieve the maximum possible responsivity.

[0050] In the disclosed embodiment, please refer to FIG9 , which shows a side view of a semiconductor integrated circuit corresponding to FIG8 provided in the embodiment of the present application. The cross-section of the converter 2 can be trapezoidal. The converter 2 includes a first side surface and a second side surface opposite each other. The first side surface is connected to the device waveguide 3, and the second side surface is connected to the input end face of the detector waveguide 1. The height of the first side surface is less than the height of the second side surface. Optionally, the height of the first side surface can be equal to the height of the device waveguide 3, and the height of the second side surface can be equal to the height of the detector waveguide 1. The converter 2 also includes an upper surface, which can be a flat slope or a rough slope, so that the height of the converter 2 continuously decreases along the direction of light transmission (i.e., from the first side surface to the second side surface). The width of the converter 2 can be constant as shown in FIG10 , or it can be designed to vary as needed. Specifically, the width of the converter 2 can be narrowed along the direction of light transmission, with the height of the detector waveguide 1 being 0.5 to 0.7 times the height of the device waveguide 3. This allows for adiabatic conversion of the light field energy within the waveguide from the mode within the device waveguide 3 to the mode within the detector waveguide 1, achieving high-speed detection.

[0051] In the embodiment of the present disclosure, the height of the detector waveguide 1 ranges from 0.1 to 3 microns, and specific embodiments of the height of the detector waveguide 1 may be 0.1 micron, 0.5 micron, 1 micron, 1.5 microns, 2 microns, 2.5 microns, and 3 microns.

[0052] In the embodiment of the present disclosure, the height of the device waveguide 3 ranges from 0.1 to 5 microns, and specific embodiments of the height of the device waveguide 3 can be 0.1 micron, 0.5 micron, 1 micron, 1.5 micron, 2 microns, 2.5 microns, 3 microns, 3.5 microns, 4 microns, 4.5 microns and 0.5 micron.

[0053] It will be appreciated that the photodetector provided herein, when combined with appropriate process flow adjustments, can achieve a structure in which the height of the detector waveguide 1 is smaller than the height of the device waveguide 3. This smaller detector waveguide 1 height results in smaller detector capacitance, enabling the detector's high-speed detection capabilities. In practice, the optimal ratio of the detector waveguide 1 height to the device waveguide 3 height varies for different device waveguide 3 heights. The overall detector waveguide 1 height ranges from approximately 10% to 90% of the device waveguide 3 height. Specifically, the detector waveguide 1 height can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of the device waveguide 3 height. The detector waveguide 1 height can be set within a range of 40% to 80% of the device waveguide 3 height. By varying the device waveguide 3 height and the detector waveguide 1 height in an integrated chip, a detector with a bandwidth greater than 50 GHz can be achieved.

[0054] The material platform of the photodetector provided in the embodiment of the present application can be an integrated optical platform such as silicon-on-insulator (SOI), silicon nitride, silicon oxide, or polymer.

[0055] Example 2:

[0056] Referring to Figures 11-12, the photodetector provided in embodiments of the present application includes a detector, a detector waveguide 1, and a converter 2. The output of the detector waveguide 1 is connected to the input of the detector; the input of the converter 2 is connected to the device waveguide 3, and the output of the converter 2 is connected to the input of the detector waveguide 1. The device waveguide 3 is taller than the detector waveguide 1. The converter 2 includes multiple subregions 201 arranged sequentially along the direction of light transmission. The subregions 201 closer to the detector waveguide 1 have lower heights, resulting in a gradually decreasing height of the converter 2 along the direction of light transmission. This allows light energy to enter from the left side of Figure 11 and be transmitted through the converter 2 to the detector waveguide 1. By designing the height of the detector waveguide 1 to be smaller than that of the device waveguide 3, this smaller height results in a smaller detector capacitance, thereby enabling high-speed detection. Furthermore, the photodetector provided in embodiments of the present application can be used in conjunction with passive components, achieving photodetector performance with a high speed response exceeding 50 GHz while meeting the performance requirements of passive components. In addition, the converter 2 provided between the device waveguide 3 and the detector waveguide 1 can achieve the maximum possible responsivity.

[0057] In the disclosed embodiment, referring to FIG11 , the height of the converter 2 varies discretely. The converter 2 includes a first side surface and a second side surface opposite each other. The first side surface is connected to the device waveguide 3, and the second side surface is connected to the input end face of the detector waveguide 1. The height of the first side surface is less than the height of the second side surface. Optionally, the height of the first side surface can be equal to the height of the device waveguide 3, and the height of the second side surface can be equal to the height of the detector waveguide 1. The converter 2 also includes an upper surface, which can be a stepped downwardly inclined surface, such that the height of the converter 2 decreases nonlinearly along the direction of light transmission (i.e., from the first side surface to the second side surface). The width of the converter 2 can be constant, as shown in FIG12 , or can be designed to vary as needed. Specifically, the width of the converter 2 can be narrowed along the direction of light transmission, with the height of the detector waveguide 1 being 0.5 to 0.7 times the height of the device waveguide 3. By designing the converter 2 as a multi-layer waveguide structure along the height direction, it is possible to convert the light field energy within the waveguide from the mode within the device waveguide 3 to the mode of the detector waveguide 1 with minimal loss, thereby achieving high-speed detection.

[0058] In the embodiment of the present disclosure, the height of the detector waveguide 1 ranges from 0.1 to 3 microns, and specific embodiments of the height of the detector waveguide 1 may be 0.1 micron, 0.5 micron, 1 micron, 1.5 microns, 2 microns, 2.5 microns, and 3 microns.

[0059] In the embodiment of the present disclosure, the height of the device waveguide 3 ranges from 0.1 to 5 microns, and specific embodiments of the height of the device waveguide 3 can be 0.1 micron, 0.5 micron, 1 micron, 1.5 micron, 2 microns, 2.5 microns, 3 microns, 3.5 microns, 4 microns, 4.5 microns and 0.5 micron.

[0060] Example 3:

[0061] Referring to FIG. 13 , a photodetector provided in an embodiment of the present application includes a detector, a detector waveguide 1, and a converter 2. The output of the detector waveguide 1 is connected to the input of the detector; the input of the converter 2 is connected to the device waveguide 3, and the output of the converter 2 is connected to the input of the detector waveguide 1. The device waveguide 3 is taller than the detector waveguide 1. The converter 2 includes multiple sublayers 202 stacked along a first direction, extending from the bottom of the converter 2 toward the top. The sublayers 202 closer to the top of the converter 2 have smaller widths, such that a predetermined width region of the converter 2 gradually narrows along the direction of light transmission. This allows light energy to enter from the left side of FIG. 13 and be transmitted through the converter 2 to the detector waveguide 1. By designing the height of the detector waveguide 1 to be smaller than that of the device waveguide 3, this smaller height results in a smaller detector capacitance, thereby enabling high-speed detection. Furthermore, the photodetector provided in an embodiment of the present application can be used in conjunction with passive components, achieving photodetector performance with a high speed response exceeding 50 GHz while meeting the performance requirements of passive components. In addition, the converter 2 provided between the device waveguide 3 and the detector waveguide 1 can achieve the maximum possible responsivity.

[0062] In the disclosed embodiment, please continue to refer to FIG13, which shows a side view of the integrated chip corresponding to FIG8 provided in the embodiment of the present application. The width of the converter 2 can vary linearly or nonlinearly, continuously or discretely. The converter 2 includes a first side surface and a second side surface opposite each other. The first side surface is connected to the device waveguide 3, and the second side surface is connected to the input end face of the detector waveguide 1. The height of the first side surface is less than the height of the second side surface. Alternatively, the height of the first side surface can be equal to the height of the device waveguide 3, and the height of the second side surface can be greater than the height of the detector waveguide 1. Alternatively, the height of the first side surface can be equal to the height of the device waveguide 3, and the height of the second side surface can be equal to the height of the detector waveguide 1. In this case, in addition to the width of the converter 2 gradually narrowing along the light transmission direction, the height of the converter 2 can also decrease along the light transmission direction, or the height of the portion of the converter 2 near the second side surface can gradually decrease along the light transmission direction. The height of the detector waveguide 1 is 0.5 to 0.7 times the height of the device waveguide 3. By designing the converter 2 as a multi-layer waveguide structure along the height direction, the light field energy in the waveguide can be converted from the mode loss in the device waveguide 3 to the detector waveguide 1 mode with as little loss as possible, thereby achieving high-speed detection.

[0063] In the embodiment of the present disclosure, the height of the detector waveguide 1 ranges from 0.1 to 3 microns, and specific embodiments of the height of the detector waveguide 1 may be 0.1 micron, 0.5 micron, 1 micron, 1.5 microns, 2 microns, 2.5 microns, and 3 microns.

[0064] In the embodiment of the present disclosure, the height of the device waveguide 3 ranges from 0.1 to 5 microns, and specific embodiments of the height of the device waveguide 3 can be 0.1 micron, 0.5 micron, 1 micron, 1.5 micron, 2 microns, 2.5 microns, 3 microns, 3.5 microns, 4 microns, 4.5 microns and 0.5 micron.

[0065] It should be noted that the aforementioned predetermined region of the width of the converter 2 gradually narrows along the direction of light transmission can refer to a target sublayer, which is a sublayer 202 other than the bottom layer. Referring to Figures 14-15 , the converter 2 may include two sublayers 202 arranged along a first direction. The height of the bottom sublayer 202 is equal to the height of the detector waveguide 1, and the width of the bottom sublayer 202 is equal to the width of the device waveguide 3, which is also equal to the width of the detector waveguide 1. The top sublayer 202 has a structure with a gradually narrowing width along the direction of light transmission, specifically a triangular prism as shown in Figure 15 . However, the cross-section of the top sublayer 202 is not limited to a trapezoidal shape. The surface of the top sublayer 202 can be flat or irregular, and this is not a limitation here. As can be seen from the above Examples 1-3, in the converter, whether it is the sublayers arranged along the first direction or the subregions arranged along the direction of light transmission, generally speaking, the closer the subregion or sublayer is to the detector waveguide, the closer its shape and size are to the detector waveguide. Optionally, the height range of the detector waveguide 1 can be set to 0.6 to 3 microns; the height range of the device waveguide 3 can be set to 1 to 5 microns, so that the photodetector has better device performance.

[0066] Example 4

[0067] An embodiment of the present application provides a semiconductor integrated circuit, as shown in Figures 8-15 , comprising a device, a device waveguide 3, and the aforementioned photodetector. The device output is connected to the device waveguide 3 input. In the photodetector, a converter 2 is provided to connect to the detector waveguide 1 and the device waveguide 3, respectively. The device waveguide 3 is taller than the detector waveguide 1. By providing the converter 2, and by gradually decreasing the height of the converter 2 or the width of a predetermined region of the converter 2 along the direction of light transmission, the detector can achieve high-speed, high-response detection capabilities. Therefore, this semiconductor integrated circuit also has similar advantages.

[0068] In the embodiment of the present disclosure, the change in the height or width of the waveguide involved in the device waveguide 3 and the converter 2 may be linear or nonlinear.

[0069] Example 5

[0070] An embodiment of the present application provides an integrated chip comprising the aforementioned semiconductor integrated circuit, which in turn comprises the aforementioned photodetector. In the photodetector, a converter 2 is provided, which is connected to the detector waveguide 1 and the device waveguide 3, respectively. The device waveguide 3 is taller than the detector waveguide 1. By providing the converter 2, and by gradually decreasing the height of the converter 2 or the width of a predetermined region of the converter 2 along the direction of light transmission, the detector can achieve high-speed, high-response detection capabilities. Therefore, this integrated chip also has similar advantages.

[0071] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A photoelectric detector, characterized in that: include: detector; a detector waveguide, wherein an output end of the detector waveguide is connected to an input end of the detector; A converter, wherein the input end of the converter is connected to the device waveguide, and the output end of the converter is connected to the input end of the detector waveguide; the height of the device waveguide is greater than the height of the detector waveguide; the height of the converter or the width of the preset area of ​​the converter gradually decreases along the light transmission direction.

2. The photodetector according to claim 1, characterized in that: The converter comprises a plurality of sub-regions sequentially arranged and connected along the light transmission direction; Among the plurality of sub-regions, a sub-region closer to the detector waveguide has a lower height.

3. The photodetector according to claim 1, characterized in that: The height variation of the converter is continuous.

4. The photodetector according to claim 1, characterized in that: The converter comprises a plurality of sub-layers stacked along a first direction; the first direction is a direction from the bottom of the converter toward the top of the converter; Among the plurality of sub-layers, a sub-layer closer to the top of the converter has a smaller width.

5. The photodetector according to claim 4, characterized in that: The width of a target sublayer among the multiple sublayers along the light transmission direction gradually narrows; the target sublayer is a sublayer among the multiple sublayers except the bottommost sublayer.

6. The photodetector according to claim 1, characterized in that: The height of the detector is smaller than the height of the device waveguide.

7. The photodetector according to claim 1, characterized in that: The height of the detector waveguide is 0.1 to 0.9 times the height of the device waveguide.

8. The photodetector according to claim 1, characterized in that: The height of the detector waveguide is 0.5 to 0.7 times the height of the device waveguide; The height of the detector waveguide ranges from 0.1 to 3 microns; The height of the device waveguide ranges from 0.1 to 5 microns.

9. A semiconductor integrated circuit, characterized in that: Comprising a device, a device waveguide and a photodetector as claimed in any one of claims 1 to 8; The output end of the device is connected to the input end of the device waveguide.

10. An integrated chip, characterized in that: Comprising the semiconductor integrated circuit as claimed in claim 9.

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