Planar relaxation germanium sensor

Abstract

The utility model discloses a planar relaxation germanium sensor, which can be used in the field of semiconductors, and comprises an ion-doped germanium substrate, an intrinsic relaxation germanium / germanium-silicon multi-quantum well layer, an intrinsic relaxation germanium layer and an ion-doped mask layer which are sequentially stacked, the ion doping mask layer is discontinuously distributed on one side, deviating from the germanium substrate, of the intrinsic relaxation germanium layer; the intrinsic relaxation germanium layer comprises an ion doped region and a non-ion doped region; a first electrode is also arranged on one side, deviating from the germanium substrate, of the ion doping region; a second electrode is further arranged on the side, away from the ion doping area, of the germanium substrate. Therefore, on one hand, by adopting the germanium substrate, the quality of the intrinsic relaxation germanium / germanium-silicon multi-quantum well layer and the intrinsic relaxation germanium layer can be improved, so that the performance of the germanium sensor is improved; and on the other hand, each pixel has no exposed side wall, and the ion doped regions of different pixels are isolated through the non-ion doped regions, so that the problem of current leakage on the surfaces and the side walls of the pixels can be reduced or even thoroughly avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, in particular to a planar relaxor germanium sensor. Background Art

[0002] InGaAs short-wave infrared sensors are widely used in machine vision, laser communication, astronomy, life sciences, semiconductor detection, security, medical diagnosis, low-altitude technology and automotive assisted driving, but they have technical bottlenecks such as small wafer size, incompatibility with CMOS manufacturing process, low yield and inability to mass produce. As a result, germanium sensors that are more compatible with CMOS manufacturing process and also have photoelectric response in the short-wave infrared band are attracting more and more attention.

[0003] At present, germanium sensors are considered to be one of the most promising technology routes. However, almost all germanium-on-insulator sensors currently use a table structure, with exposed ion-doped layer sidewalls on the pixel sidewalls. The surface of the ion-doped layer is in contact with an electrode. For germanium sensors with small pixel spacing, the sidewalls of the ion-doped layer will contact another electrode, resulting in large leakage currents on the pixel surface and sidewalls, which will have a serious impact on the sensitivity, power consumption, reliability and other performance of the germanium sensor.

[0004] Therefore, how to reduce the leakage current of germanium-based sensors has become a problem that needs to be solved. Utility Model Content

[0005] Based on the above problems, the utility model provides a planar relaxation germanium sensor, which can reduce the leakage current of the germanium sensor.

[0006] The utility model embodiment discloses the following technical solution:

[0007] The present invention provides a planar relaxor germanium sensor, the planar relaxor germanium sensor comprising:

[0008] An ion-doped germanium substrate, an intrinsic relaxed germanium / germanium silicon multi-quantum well layer, an intrinsic relaxed germanium layer and an ion-doped mask layer are stacked in sequence; the ion-doped mask layer is discontinuously distributed on a side of the intrinsic relaxed germanium layer away from the ion-doped germanium substrate;

[0009] The intrinsic relaxed germanium layer comprises an ion-doped region and a non-ion-doped region, wherein the ion-doped region is located in a region of the intrinsic relaxed germanium layer that is not covered by the ion-doping mask layer;

[0010] The side of the ion-doped region away from the ion-doped germanium substrate also has a first electrode; the side of the ion-doped germanium substrate away from the ion-doped region also has a second electrode.

[0011] Optionally, the first electrode is a transparent electrode.

[0012] Optionally, the thickness of the intrinsic relaxed germanium layer is in the range of 100 to 3000 nm, the thickness of the ion-doped region is in the range of 100 to 500 nm, and the ion-doped region is located on a side of the intrinsic relaxed germanium layer away from the ion-doped germanium substrate.

[0013] Optionally, the intrinsic relaxed germanium / germanium silicon multi-quantum well layer comprises alternately stacked relaxed germanium layers and relaxed germanium silicon layers;

[0014] The relaxed germanium layer is a barrier layer with a thickness ranging from 10 to 100 nm; the relaxed germanium silicon layer is a potential well layer with a thickness ranging from 10 to 100 nm; and the content of silicon in the relaxed germanium silicon layer is 0 to 30%.

[0015] Optionally, the intrinsic relaxed germanium / germanium silicon multi-quantum well layer includes 2 to 10 quantum wells.

[0016] Optionally, the thickness of the intrinsic relaxed germanium / germanium silicon multiple quantum well layer is in the range of 200 to 1000 nm.

[0017] Optionally, the thickness of the ion doping mask layer ranges from 100 to 500 nm.

[0018] Optionally, if the ion-doped germanium substrate is an N-type germanium substrate, the ion-doped region is a P-type ion-doped region; if the ion-doped germanium substrate is a P-type germanium substrate, the ion-doped region is an N-type ion-doped region.

[0019] Optionally, the ion doping mask layer and the exposed surface of the ion doping region further have a passivation layer.

[0020] Optionally, the germanium-based sensor further includes a readout circuit, and the second electrode is electrically connected to the readout circuit.

[0021] Compared with the prior art, the utility model has the following beneficial effects:

[0022] The utility model provides a planar relaxed germanium sensor, which comprises: an ion-doped germanium substrate, an intrinsic relaxed germanium / germanium silicon multi-quantum well layer, an intrinsic relaxed germanium layer and an ion-doped mask layer stacked in sequence; the ion-doped mask layer is discontinuously distributed on the side of the intrinsic relaxed germanium layer away from the ion-doped germanium substrate; the intrinsic relaxed germanium layer comprises an ion-doped region and a non-ion-doped region, wherein the ion-doped region is located in a region of the intrinsic relaxed germanium layer that is not covered by the ion-doped mask layer; the side of the ion-doped region away from the ion-doped germanium substrate further comprises a first electrode; the side of the ion-doped germanium substrate away from the ion-doped region further comprises a second electrode. Therefore, on the one hand, by using a germanium substrate, an intrinsic relaxed germanium / germanium silicon multi-quantum well layer and an intrinsic relaxed germanium layer can be formed by homoepitaxial growth on the germanium substrate, thereby reducing the defect density of the intrinsic relaxed germanium / germanium silicon multi-quantum well layer and the intrinsic relaxed germanium layer, improving the crystal quality of the two, and further improving the performance of the germanium-based sensor; on the other hand, the ion-doped region of each pixel is wrapped by the non-ion-doped region in the vertical direction of the film stacking direction, forming a planar structured germanium-based sensor, in which each pixel has no exposed sidewalls, and the ion-doped regions of different pixels are isolated by the non-ion-doped region, thereby reducing or even completely avoiding the leakage current on the pixel surface and sidewalls. The problem can be solved, and the electrical crosstalk between adjacent pixels can be reduced, so as to obtain a germanium sensor with small pixel spacing, low leakage current and low dark current; on the other hand, there are two photoelectric sensing layers, namely, the intrinsic relaxed germanium / germanium silicon multi-quantum well layer and the intrinsic relaxed germanium layer, wherein the intrinsic relaxed germanium / germanium silicon multi-quantum well layer is an infrared band sensing layer, and the intrinsic relaxed germanium layer is a visible light and short-wave infrared sensing layer. In practical applications, the external light signal will enter the germanium sensor from the first electrode side, first enter the intrinsic relaxed germanium layer, and then enter the intrinsic relaxed germanium / germanium silicon multi-quantum well layer. The combined structure of the intrinsic relaxed germanium / germanium silicon multi-quantum well layer and the intrinsic relaxed germanium layer can significantly expand the spectral response range of the germanium sensor. In addition, the structure of the germanium sensor is simple, the production cost required is low, and it can be manufactured through a production process that is highly compatible with the CMOS process, which is conducive to promoting the application of germanium sensors in the civilian field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 A structural diagram of a planar relaxor germanium sensor provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0025] As described above, germanium sensors are considered to be one of the most promising technology routes. However, almost all germanium sensors currently use a table structure, with exposed ion-doped layer sidewalls on the pixel sidewalls, and the surface of the ion-doped layer is in contact with an electrode. For germanium sensors with large pixel sizes and large spacing between pixels, table-structured germanium sensors can meet the needs of most application scenarios; but in order to meet more application scenarios, it is necessary to make the pixel spacing and pixel size of germanium sensors smaller, so as to obtain focal plane array germanium sensors with higher resolution, larger array specifications, higher fill factor and lower cost.

[0026] For germanium sensors with smaller pixel pitch and pixel size, the sidewall of the ion-doped layer will contact another electrode, resulting in large leakage current on the pixel surface and sidewall, which will have a serious impact on the sensitivity, power consumption, reliability and other performance of the germanium sensor. In addition, the electrical crosstalk between adjacent small pixels of the mesa-structured germanium sensor is more serious, resulting in higher dark current, which is not conducive to improving the performance of the focal plane array.

[0027] In order to solve the above problems, the utility model provides a planar relaxed germanium sensor, which comprises: an ion-doped germanium substrate, an intrinsic relaxed germanium / germanium silicon multi-quantum well layer, an intrinsic relaxed germanium layer and an ion-doped mask layer stacked in sequence; the ion-doped mask layer is discontinuously distributed on the side of the intrinsic relaxed germanium layer away from the ion-doped germanium substrate; the intrinsic relaxed germanium layer comprises an ion-doped region and a non-ion-doped region, wherein the ion-doped region is located in the region of the intrinsic relaxed germanium layer not covered by the ion-doped mask layer; the ion-doped region is further provided with a first electrode on the side away from the ion-doped germanium substrate; the ion-doped germanium substrate is further provided with a second electrode on the side away from the ion-doped region.

[0028] Therefore, the intrinsic relaxed germanium layer of the planar relaxed germanium sensor includes an ion-doped region and a non-ion-doped region, each pixel does not have an exposed sidewall, and the ion-doped regions of different pixels are isolated by the non-ion-doped region. The planar PIN structure composed of the ion-doped germanium substrate, the intrinsic relaxed germanium / germanium silicon multi-quantum well layer and the ion-doped region can reduce or even completely avoid the leakage current problem on the pixel surface and sidewall, and can also reduce the electrical crosstalk between adjacent pixels, thereby obtaining a germanium sensor with small pixel spacing, low leakage current and low dark current.

[0029] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] See also Figure 1 , which is a structural diagram of a planar relaxor germanium sensor provided by an embodiment of the utility model, and the planar relaxor germanium sensor comprises:

[0031] An ion-doped germanium substrate 101 , an intrinsic relaxed germanium / silicon germanium multi-quantum well layer 102 , an intrinsic relaxed germanium layer 103 , and an ion-doped mask layer 104 are stacked in sequence.

[0032] The ion-doped mask layer 104 is intermittently distributed on a side of the intrinsic relaxed germanium layer 103 away from the ion-doped germanium substrate 101 .

[0033] As an example, an intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 and an intrinsic relaxed germanium layer 103 can be first formed by directly performing homoepitaxial growth on an ion-doped germanium substrate 101; then an ion-doping mask layer is formed on the side of the intrinsic relaxed germanium layer 103 away from the ion-doped germanium substrate 101 by processes such as chemical vapor deposition, and the ion-doping mask layer can be a film layer with good ion blocking effect such as a silicon oxide layer or a silicon nitride layer, and the thickness ranges from 100 to 500 nm; finally, the ion-doping mask layer 104 is etched to open holes by, for example, a reactive ion etching (RIE) process, thereby forming an ion-doping mask layer 104 discontinuously distributed on the side of the intrinsic relaxed germanium layer 103 away from the ion-doped germanium substrate 101.

[0034] The intrinsic relaxed germanium layer 103 includes an ion-doped region 1031 and a non-ion-doped region 1032 , wherein the ion-doped region 1031 is located in a region of the intrinsic relaxed germanium layer 103 that is not covered by the ion-doping mask layer 104 .

[0035] Specifically, the intrinsic relaxed germanium layer 103 may be ion-doped under the mask of the ion-doping mask layer 104 by, for example, an ion-doping process such as ion implantation or diffusion, so as to form an ion-doped region 1031 with ion doping and a non-ion-doped region 1032 without ion doping. It is understandable that, on the surface of the intrinsic relaxed germanium layer 103 away from the ion-doped germanium substrate 101, the range of the ion-doped region 1031 will be slightly larger than the region of the intrinsic relaxed germanium layer 103 not covered by the ion-doping mask layer 104, and the range of the non-ion-doped region 1032 will be slightly smaller than the region of the intrinsic relaxed germanium layer 103 covered by the ion-doping mask layer 104. The ion doping type of the ion doping region 1031 is different from that of the ion doped germanium substrate 101. For example, if the ion doped germanium substrate 101 is an N-type germanium substrate, the ion doping region 1031 is a P-type ion doping region; if the ion doped germanium substrate 101 is a P-type germanium substrate, the ion doping region 1031 is an N-type ion doping region. Thus, the ion doped germanium substrate 101, the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102, and the ion doping region 1031 can form a planar PIN structure.

[0036] Exemplarily, the thickness of the intrinsic relaxed germanium layer 103 ranges from 100 to 3000 nm, the thickness of the ion-doped region 1031 ranges from 100 to 500 nm, and the ion-doped region 1031 is located on a side of the intrinsic relaxed germanium layer 103 away from the ion-doped germanium substrate 101 .

[0037] For example, the thickness of the intrinsic relaxed germanium layer 103 can be 2500nm, and the thickness of the ion-doped region 1031 can be 500nm, that is, the ion-doping depth is 500nm. At this time, the side of the ion-doped region 1031 close to the ion-doped germanium substrate 101 is in contact with the non-ion-doped region 1031; or the thickness of the intrinsic relaxed germanium layer 103 is 400nm, and the thickness of the ion-doped region 1031 is also 400nm, that is, the ion-doping depth is 400nm. At this time, the side of the ion-doped region 1031 close to the ion-doped germanium substrate 101 is in contact with the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102. It can be understood that the above thicknesses are only examples, and the thicknesses of the intrinsic relaxed germanium layer 103 and the ion-doped region 1031 can be flexibly selected within the given thickness range according to actual needs.

[0038] The side of the ion-doped region 1031 facing away from the ion-doped germanium substrate 101 also has a first electrode 105 ; the side of the ion-doped germanium substrate 101 facing away from the ion-doped region 1031 also has a second electrode 106 .

[0039] Specifically, the second electrode 106 can cover the side of the ion-doped germanium substrate 101 away from the ion-doped region 1031; the first electrode 105 is preferably a transparent electrode. In practical applications, the germanium sensor provided by the embodiment of the utility model has an external light signal entering the germanium sensor from the side of the first electrode 105. Selecting a transparent electrode as the first electrode 105 can reduce the shielding of the first electrode 105 on the incident light and improve the responsiveness of the germanium sensor.

[0040] Therefore, on the one hand, by adopting a germanium substrate, an intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 and an intrinsic relaxed germanium layer 103 can be formed by homoepitaxial growth on the germanium substrate, thereby reducing the defect density of the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 and the intrinsic relaxed germanium layer 103, improving the crystal quality of the two, and further improving the performance of the germanium-based sensor; on the other hand, the ion-doped region 1031 of each pixel is wrapped by the non-ion-doped region 1032 in the vertical direction of the film stacking direction, forming a planar structured germanium-based sensor, in which no exposed sidewalls exist in each pixel, and the ion-doped regions of different pixels are isolated by the non-ion-doped region, forming a planar relaxed germanium-based sensor, thereby reducing or even completely avoiding the presence of defects on the pixel surface and sidewalls. The leakage current problem can be solved, and the electrical crosstalk between adjacent pixels can also be reduced, so as to obtain a germanium sensor with small pixel spacing, low leakage current and low dark current; on the other hand, there are two photoelectric sensing layers, namely, the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 and the intrinsic relaxed germanium layer 103, wherein the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 is an infrared band sensing layer, and the intrinsic relaxed germanium layer 103 is a visible light and short-wave infrared sensing layer. In practical applications, the external light signal will enter the germanium sensor from the first electrode 105 side, first enter the intrinsic relaxed germanium layer 103, and then enter the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102. The combined structure of the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 and the intrinsic relaxed germanium layer 103 can significantly expand the spectral response range of the germanium sensor. In addition, the germanium sensor has a simple structure, low production cost, and can be manufactured through a production process that is highly compatible with the CMOS process, which is conducive to promoting the application of germanium sensors in the civilian field.

[0041] Optionally, the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 includes a relaxed germanium layer and a relaxed germanium silicon layer, wherein the relaxed germanium layer is a barrier layer with a thickness range of 10 to 100 nm; the relaxed germanium silicon layer is a potential well layer with a thickness range of 10 to 100 nm, the silicon content in the relaxed germanium silicon layer is 0 to 30%, and the germanium content is not less than 70%; the total thickness range of the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 is 200 to 1000 nm, and can contain 2 to 10 quantum wells.

[0042] In actual application, the germanium sensor provided by the embodiment of the utility model will enter the germanium sensor from the first electrode 105 side. When the external light signal enters the photoelectric sensing layer of the germanium sensor, it will cause the transition of the inter-band carriers in the intrinsic relaxed germanium layer 103 and the transition of the inter-band carriers in the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102. That is, there are two photoelectric sensing layers, namely, the intrinsic relaxed germanium layer 103 and the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102. Among them, the intrinsic relaxed germanium layer 103 is mainly used to sense the light signal in the visible light and short-wave infrared bands, and the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 is mainly used to sense the light signal in the short-wave infrared, medium-wave infrared and even long-wave infrared bands. Therefore, the combined structure of the second intrinsic germanium layer 104 and the intrinsic germanium / germanium silicon multi-quantum well layer 103 is used as the sensing layer, which significantly expands the spectral response range of the germanium sensor. In addition, by adjusting the silicon content in the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102, the thickness of the relaxed germanium layer and the relaxed germanium silicon layer, and the number of quantum wells, the energy level position in the potential well can be adjusted, so that the response band of the intrinsic relaxed germanium / germanium silicon multi-quantum well layer 102 is continuously adjustable.

[0043] In some other embodiments provided by the present invention, the germanium-based sensor further includes a passivation layer 107 . The passivation layer 107 is located on the exposed surfaces of the ion-doped mask layer 104 and the ion-doped region 1031 .

[0044] Specifically, after forming an ion-doped region 1031 and a non-ion-doped region 1032 in the intrinsic relaxed germanium layer 103, the ion-doped mask layer 104 and the exposed surface of the intrinsic relaxed germanium layer 103 are passivated to form a passivation layer 107; and then the passivation layer 107 on the surface of the ion-doped region 1031 is opened to facilitate the formation of a first electrode 105 in contact with the ion-doped region 1031.

[0045] In some other embodiments provided by the present invention, the germanium-based sensor further includes a readout circuit ROIC, and the second electrode 106 can be electrically connected to the readout circuit by bump bonding.

[0046] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0047] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A planar relaxor germanium sensor, characterized in that: The germanium sensor comprises: An ion-doped germanium substrate, an intrinsic relaxed germanium / germanium silicon multi-quantum well layer, an intrinsic relaxed germanium layer and an ion-doped mask layer are stacked in sequence; the ion-doped mask layer is discontinuously distributed on a side of the intrinsic relaxed germanium layer away from the ion-doped germanium substrate; The intrinsic relaxed germanium layer comprises an ion-doped region and a non-ion-doped region, wherein the ion-doped region is located in a region of the intrinsic relaxed germanium layer that is not covered by the ion-doping mask layer; The side of the ion-doped region away from the ion-doped germanium substrate also has a first electrode; the side of the ion-doped germanium substrate away from the ion-doped region also has a second electrode.

2. The planar relaxor germanium sensor according to claim 1, characterized in that: The first electrode is a transparent electrode.

3. The planar relaxor germanium sensor according to claim 1, characterized in that: The thickness of the intrinsic relaxed germanium layer is in the range of 100 to 3000 nm, the thickness of the ion-doped region is in the range of 100 to 500 nm, and the ion-doped region is located on a side of the intrinsic relaxed germanium layer away from the ion-doped germanium substrate.

4. The planar relaxor germanium sensor according to claim 1, characterized in that: The intrinsic relaxed germanium / germanium silicon multi-quantum well layer comprises alternately stacked relaxed germanium layers and relaxed germanium silicon layers; The relaxed germanium layer is a barrier layer with a thickness ranging from 10 to 100 nm; the relaxed germanium silicon layer is a potential well layer with a thickness ranging from 10 to 100 nm; the content of silicon in the relaxed germanium silicon layer is 0 to 30%.

5. The planar relaxor germanium sensor according to claim 1, characterized in that: The intrinsic relaxed germanium / germanium silicon multi-quantum well layer includes 2 to 10 quantum wells.

6. The planar relaxor germanium sensor according to claim 1, characterized in that: The thickness of the intrinsic relaxed germanium / germanium silicon multi-quantum well layer is in the range of 200 to 1000 nm.

7. The planar relaxor germanium sensor according to claim 1, characterized in that: The thickness of the ion doping mask layer ranges from 100 to 500 nm.

8. The planar relaxor germanium sensor according to claim 1, characterized in that: If the ion-doped germanium substrate is an N-type germanium substrate, the ion-doped region is a P-type ion-doped region; if the ion-doped germanium substrate is a P-type germanium substrate, the ion-doped region is an N-type ion-doped region.

9. The planar relaxor germanium sensor according to claim 1, characterized in that: The exposed surfaces of the ion doping mask layer and the ion doping region also have a passivation layer.

10. The planar relaxor germanium sensor according to claim 1, characterized in that: The germanium-based sensor further includes a readout circuit, and the second electrode is electrically connected to the readout circuit.

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