Photoelectric detector structure and forming method thereof

Abstract

A photoelectric detector structure and a forming method thereof, the structure comprising: a substrate comprising a first semiconductor layer, a buried oxide layer located on the first semiconductor layer and a second semiconductor layer located on the buried oxide layer, the second semiconductor layer comprising a first contact region and a second contact region, the doping type of the first contact region being different from the doping type of the second contact region; and a light absorption layer between the first contact region and the second contact region, wherein the light absorption layer is respectively adjacent to the second semiconductor layer of the first contact region and the second semiconductor layer of the second contact region. The size of the light absorption layer in the direction from the first contact area to the second contact area is small, so that the transit time of the photoelectric detector structure is short, the 3dB bandwidth of the photoelectric detector is increased, the signal output capability of the photoelectric detector is improved, the thickness of the light absorption layer can be regulated and controlled, and the transit time of the photoelectric detector structure can be adjusted. And the 3dB bandwidth of the photoelectric detector structure is regulated and controlled, so that the photoelectric detector structure is suitable for functional modules with different bandwidth requirements.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a photodetector structure and a forming method thereof. Background Art

[0002] Photons, as a carrier of information, are playing an increasingly important role in science and technology. Photodetectors are crucial components for achieving this function and represent a crucial technological fortress for all optoelectronic chips. The development of new technologies such as remote sensing, fiber-optic communications, and optical interconnects has led to a growing interest in photodetectors. To date, the introduction of III-V main-group materials, primarily IV, into silicon photonics platforms to create silicon-based photodetectors has effectively overcome the limitations of silicon's bandgap structure, hindering the realization of effective photodetectors based on pure silicon in the communications band. Germanium-based photodetectors are currently the best choice.

[0003] However, germanium photodetectors still have problems. Summary of the Invention

[0004] The problem solved by the present invention is to provide a germanium photodetector structure to reduce the transit time of carriers, increase the 3dB bandwidth of the germanium photodetector, and improve the signal output capability of the photodetector.

[0005] To solve the above problems, the present invention provides a photodetector structure, comprising: a substrate, the substrate comprising a first semiconductor layer, a buried oxide layer located on the first semiconductor layer, and a second semiconductor layer located on the buried oxide layer, the second semiconductor layer comprising a first contact region and a second contact region, the doping type of the first contact region being different from the doping type of the second contact region; a light absorption layer located between the first contact region and the second contact region, the light absorption layer being adjacent to the second semiconductor layer of the first contact region and the second semiconductor layer of the second contact region, respectively.

[0006] Optionally, the material of the light absorbing layer is intrinsic germanium; and the material of the second semiconductor layer includes silicon.

[0007] Optionally, the thickness of the light absorbing layer ranges from 20 nm to 1000 nm.

[0008] Optionally, the second semiconductor layer includes two horizontal portions, the two horizontal portions are located on both sides of the light absorption structure, and the first contact region and the second contact region are respectively located in the two horizontal portions.

[0009] Optionally, the sidewall of the second semiconductor layer in the first contact area adjacent to the light absorbing layer is not smaller than the sidewall of the light absorbing layer; the sidewall of the second semiconductor layer in the second contact area adjacent to the light absorbing layer is not smaller than the sidewall of the light absorbing layer.

[0010] Optionally, the second semiconductor layer further includes two vertical portions, wherein one vertical portion is located between a horizontal portion and the light absorbing layer, and the sidewall of the vertical portion is adjacent to the sidewall of the light absorbing layer; the first contact area and the second contact area respectively extend into the corresponding vertical portions.

[0011] Optionally, the height of the vertical portion is not less than the height of the light absorbing layer.

[0012] Optionally, the second semiconductor layer further includes a first external contact region and a second external contact region, the first external contact region is located on a side of the first contact region away from the light absorption layer, the second external contact region is located on a side of the second contact region away from the light absorption layer, the doping type of the first external contact region is the same as the doping type of the first contact region, and the doping type of the second external contact region is the same as the doping type of the second contact region.

[0013] Optionally, the photodetector structure further includes: conductive plugs located on the first external connection area and the second external connection area.

[0014] Correspondingly, the technical solution of the present invention further provides a method for forming a photodetector structure, and the method for forming a photodetector structure forms the photodetector structure as described in any of the above technical solutions.

[0015] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0016] In the photodetector structure of the technical solution of the present invention, the light absorption layer is located between the first contact area and the second contact area, and the light absorption layer is adjacent to the second semiconductor layer of the first contact area and the second semiconductor layer of the second contact area, respectively. The size of the light absorption layer along the direction from the first contact area to the second contact area is relatively small, so that the transit time of the photodetector structure is relatively small, the 3dB bandwidth of the photodetector is increased, and the signal output capability of the photodetector is improved. In addition, the size of the light absorption layer along the direction from the first contact area to the second contact area can be regulated, and the transit time of the photodetector structure can be adjusted, thereby regulating the 3dB bandwidth of the photodetector structure, so that the photodetector structure is suitable for functional modules with different bandwidth requirements.

[0017] In an optional embodiment of the present invention, the sidewalls of the second semiconductor layer in the first contact region adjacent to the light absorbing layer are no smaller than the sidewalls of the light absorbing layer; and the sidewalls of the second semiconductor layer in the second contact region adjacent to the light absorbing layer are no smaller than the sidewalls of the light absorbing layer. The contact area between the light absorbing layer and the first and second contact regions is large, thereby improving the responsivity of the photodetector structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the cross-sectional structure of a photodetector structure.

[0019] Figure 2 FIG. 4 is a schematic cross-sectional view of a photodetector structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] As can be seen from the background art, existing photodetector structures suffer from long carrier transit times, small 3dB bandwidths of germanium photodetectors, and insufficient signal output capabilities. This article analyzes the causes of this small 3dB bandwidth using a specific photodetector structure.

[0021] Please refer to Figure 1 The photodetector structure includes: a substrate, the substrate including a first semiconductor layer 100, a buried oxide layer 101 located on the first semiconductor layer 100, and a second semiconductor layer 102 located on the buried oxide layer 101, the second semiconductor layer 102 including a first contact region I, an intrinsic region III, and a second contact region II, the doping type of the first contact region I is different from the doping type of the second contact region II; a light absorption layer 103 located on the first contact region I, the intrinsic region III, and the second contact region II.

[0022] The material of the first semiconductor layer 100 includes silicon; the material of the second semiconductor layer 102 includes silicon; and the material of the light absorbing layer 103 includes germanium.

[0023] The light absorbing layer 103 has a large width, that is, the light absorbing layer 103 has a large dimension parallel to the substrate surface, which increases the carrier transit time, reduces the 3dB bandwidth of the germanium photodetector, and makes the signal output capability of the photodetector insufficient.

[0024] In order to solve the technical problem, the present invention provides a photodetector structure, including: a substrate, the substrate including a first semiconductor layer, a buried oxide layer located on the first semiconductor layer, and a second semiconductor layer located on the buried oxide layer, the second semiconductor layer including a first contact area and a second contact area, the doping type of the first contact area is different from the doping type of the second contact area; a light absorption layer located between the first contact area and the second contact area, the light absorption layer being adjacent to the second semiconductor layer of the first contact area and the second semiconductor layer of the second contact area, respectively.

[0025] In the photodetector structure of the technical solution of the present invention, the light absorption layer is located between the first contact area and the second contact area, and the light absorption layer is adjacent to the second semiconductor layer of the first contact area and the second semiconductor layer of the second contact area, respectively. The size of the light absorption layer along the direction from the first contact area to the second contact area is relatively small, so that the transit time of the photodetector structure is relatively small, the 3dB bandwidth of the photodetector is increased, and the signal output capability of the photodetector is improved. In addition, the size of the light absorption layer along the direction from the first contact area to the second contact area can be regulated, and the transit time of the photodetector structure can be adjusted, thereby regulating the 3dB bandwidth of the photodetector structure, so that the photodetector structure is suitable for functional modules with different bandwidth requirements.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] Please refer to Figure 2 The photodetector structure includes: a substrate, the substrate including a first semiconductor layer 200, a buried oxide layer 201 located on the first semiconductor layer 200, and a second semiconductor layer 202 located on the buried oxide layer 201, the second semiconductor layer 202 including a first contact region I and a second contact region II, and the doping type of the first contact region I is different from the doping type of the second contact region II.

[0028] The material of the first semiconductor layer 200 includes silicon; the material of the buried oxide layer 201 includes silicon oxide; and the material of the second semiconductor layer 202 includes silicon.

[0029] The doping ion concentration range of the first contact region I is: 1.0×10 11 atom / cm 3 to 1.0×10 17 atom / cm 3 .

[0030] The doping ion concentration range of the second contact region II is: 1.0×10 11atom / cm 3 to 1.0×10 17 atom / cm 3 .

[0031] Specifically, in this embodiment, the doping type of the doping ions in the first contact region I is P-type doping; the doping type of the doping ions in the second contact region II is N-type doping.

[0032] Please continue to refer to Figure 2 The photodetector structure includes: a light absorption layer 203 located between the first contact area I and the second contact area II, and the light absorption layer 203 is adjacent to the second semiconductor layer 202 of the first contact area I and the second semiconductor layer 202 of the second contact area II respectively.

[0033] The material of the light absorption layer 203 is intrinsic germanium. The thickness of the light absorption layer 203 ranges from 20 nm to 1000 nm. The thickness of the light absorption layer 203 is the dimension along the direction from the first contact region I to the second contact region II. The dimension of the light absorption layer 203 along the direction from the first contact region I to the second contact region II can be controlled to adjust the transit time of the photodetector structure, thereby adjusting the 3 dB bandwidth of the photodetector structure, making the photodetector structure suitable for functional modules with different bandwidth requirements.

[0034] The size of the light absorbing layer 203 in a direction perpendicular to the surface of the buried oxide layer 201 ranges from 20 nm to 1000 nm. If the size of the light absorbing layer 203 in a direction perpendicular to the buried oxide layer 201 is too large, the overall device structure will be too large, the process cost will be high, and the device performance improvement will be minimal, making it unfeasible.

[0035] The sidewalls of the second semiconductor layer 202 in the first contact region I adjacent to the light absorbing layer 203 are no smaller than the sidewalls of the light absorbing layer 203, and the sidewalls of the second semiconductor layer 202 in the second contact region II adjacent to the light absorbing layer 203 are no smaller than the sidewalls of the light absorbing layer 203. The contact area between the light absorbing layer 203 and the sidewalls of the second semiconductor layer 202 in the first contact region I and the second semiconductor layer 202 in the second contact region II is large, thereby improving the responsivity of the photodetector structure.

[0036] The second semiconductor layer 202 includes two horizontal portions, the two horizontal portions are located on both sides of the light absorption structure, and the first contact region I and the second contact region II are respectively located in the two horizontal portions.

[0037] In some embodiments, the side walls of the light absorption layer 203, the side walls of the second semiconductor layer 202 in the first contact area I, the side walls of the second semiconductor layer 202 in the second contact area II, the side walls of the second semiconductor layer 202 in the first external contact area III, and the side walls of the second semiconductor layer 202 in the second external contact area IV are the same height.

[0038] In other embodiments, the side walls of the light absorption layer 203, the side walls of the second semiconductor layer 202 in the first contact area I, and the side walls of the second semiconductor layer 202 in the second contact area II are the same height and greater than the side walls of the second semiconductor layer 202 in the first external contact area III and the side walls of the second semiconductor layer 202 in the second external contact area IV.

[0039] In this embodiment, the sidewall heights of the second semiconductor layer 202 in the first contact region I and the sidewall heights of the second semiconductor layer 202 in the second contact region II are the same and greater than the sidewall heights of the light absorption layer 203, and the sidewall heights of the light absorption layer 203 are greater than the sidewall heights of the second semiconductor layer 202 in the first external contact region III and the sidewall heights of the second semiconductor layer 202 in the second external contact region IV.

[0040] The second semiconductor layer 202 further includes two vertical portions, wherein one vertical portion is located between a horizontal portion and the light absorbing layer 203 , and the sidewall of the vertical portion is adjacent to the sidewall of the light absorbing layer 203 ; the first contact region I and the second contact region II respectively extend into the corresponding vertical portions.

[0041] The height of the vertical portion is not less than the height of the light absorbing layer 203. The height of the vertical portion is not less than the height of the light absorbing layer 203, thereby ensuring the absorption efficiency of the photodetector structure.

[0042] In some embodiments, the height of the vertical portion is equal to the height of the light absorbing layer 203 .

[0043] In this embodiment, the height of the vertical portion is greater than the height of the light absorbing layer 203 .

[0044] Please continue to refer to Figure 2 The second semiconductor layer 202 further includes a first external region III and a second external region IV, the first external region III being located on a side of the first contact region I away from the light absorption layer 203, the second external region IV being located on a side of the second contact region II away from the light absorption layer 203, the doping type of the first external region III being the same as the doping type of the first contact region I, and the doping type of the second external region IV being the same as the doping type of the second contact region II.

[0045] The horizontal portion includes a first contact region I, a first circumscribed region III, a second contact region II, and a second circumscribed region IV.

[0046] The doping ion concentration range of the first external region III is: 1.0×10 12 atom / cm 3 to 1.0×10 20 atom / cm 3 .

[0047] The doping ion concentration range of the second external region IV is: 1.0×10 12 atom / cm 3 to 1.0×10 20 atom / cm 3 .

[0048] Specifically, in this embodiment, the doping type of the doping ions in the first external region III is P-type doping; the doping type of the doping ions in the second external region IV is N-type doping.

[0049] Please continue to refer to Figure 2 The photodetector structure includes a conductive plug 204 located on the first external connection area III and the second external connection area IV. The conductive plug 204 is made of tungsten, aluminum, and copper. The conductive plug 204 is used to electrically connect the first external connection area III, the second external connection area IV, a signal electrode, and a ground electrode.

[0050] The photodetector structure further includes an interlayer dielectric layer 205. The interlayer dielectric layer 205 is located on the second semiconductor layer 202, and the conductive plug 204 is located in the interlayer dielectric layer 205. The material of the interlayer dielectric layer 205 includes silicon oxide.

[0051] Correspondingly, an embodiment of the present invention further provides a method for forming the above-mentioned photodetector structure, which will not be described in detail here.

[0052] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A photodetector structure, characterized in that: include: a substrate comprising a first semiconductor layer, a buried oxide layer on the first semiconductor layer, and a second semiconductor layer on the buried oxide layer, wherein the second semiconductor layer comprises a first contact region and a second contact region, wherein the doping type of the first contact region is different from the doping type of the second contact region; A light absorbing layer is located between the first contact region and the second contact region, and the light absorbing layer is adjacent to the second semiconductor layer in the first contact region and the second semiconductor layer in the second contact region respectively.

2. The photodetector structure according to claim 1, wherein: The material of the light absorbing layer is intrinsic germanium; the material of the second semiconductor layer includes silicon.

3. The photodetector structure according to claim 1, wherein: The thickness of the light absorbing layer ranges from 20 nm to 1000 nm.

4. The photodetector structure according to claim 1, wherein: The second semiconductor layer includes two horizontal portions, the two horizontal portions are located on both sides of the light absorption structure, and the first contact region and the second contact region are respectively located in the two horizontal portions.

5. The photodetector structure according to claim 4, wherein: The sidewall of the second semiconductor layer in the first contact region adjacent to the light absorbing layer is not smaller than the sidewall of the light absorbing layer; the sidewall of the second semiconductor layer in the second contact region adjacent to the light absorbing layer is not smaller than the sidewall of the light absorbing layer.

6. The photodetector structure according to claim 5, wherein: The second semiconductor layer further includes two vertical portions, wherein one vertical portion is located between a horizontal portion and the light absorbing layer, and a sidewall of the vertical portion is adjacent to a sidewall of the light absorbing layer; The first contact area and the second contact area respectively extend into the corresponding vertical portion.

7. The photodetector structure according to claim 6, wherein: The height of the vertical portion is not less than the height of the light absorbing layer.

8. The photodetector structure according to claim 1, wherein: The second semiconductor layer also includes a first external contact region and a second external contact region, the first external contact region is located on a side of the first contact region away from the light absorption layer, and the second external contact region is located on a side of the second contact region away from the light absorption layer, the doping type of the first external contact region is the same as the doping type of the first contact region, and the doping type of the second external contact region is the same as the doping type of the second contact region.

9. The photodetector structure according to claim 8, wherein: The photodetector structure further includes a conductive plug located on the first external connection region and the second external connection region.

10. A method for forming a photodetector structure, characterized in that: The method for forming a photodetector structure forms the photodetector structure according to any one of claims 1 to 9.

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