CN113488557B - Silicon-based detector with gradually-changed width and preparation method thereof - Google Patents

Silicon-based detector with gradually-changed width and preparation method thereof Download PDF

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CN113488557B
CN113488557B CN202110764252.1A CN202110764252A CN113488557B CN 113488557 B CN113488557 B CN 113488557B CN 202110764252 A CN202110764252 A CN 202110764252A CN 113488557 B CN113488557 B CN 113488557B
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CN113488557A (en
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刘智
成步文
郑军
薛春来
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Institute of Semiconductors of CAS
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Abstract

The invention discloses a silicon-based detector with gradually changed width, which comprises: the SOI substrate comprises a bottom silicon material layer, a silicon dioxide filling layer, top silicon and a waveguide layer formed on the top silicon; the n-type lightly doped region is formed on the waveguide layer; the n-type heavily doped region is formed at two sides of the n-type lightly doped region; the light absorption layer is formed on the n-type lightly doped region, and a light absorption layer p-type heavily doped region is formed on part of the upper surface of the light absorption layer; the silicon dioxide window layer is formed on the top silicon and the waveguide layer, and an epitaxial window is formed on the silicon dioxide window layer corresponding to the waveguide layer; a first electrode window is arranged on the silicon dioxide window layer and the insulating medium layer corresponding to the n-type heavily doped region; a second electrode window is formed on the insulating medium layer corresponding to the p-type heavily doped region of the light absorption layer; an n electrode formed on the first electrode window; a p-electrode formed on the second electrode window; the light absorbing layer has a width closer to the light incident end larger than a width farther from the light incident end.

Description

Silicon-based detector with gradually-changed width and preparation method thereof
Technical Field
The invention relates to the field of optical interconnection, in particular to a silicon-based detector with gradually-changed width and a preparation method thereof.
Background
The high-frequency photonic link has the advantages of wide bandwidth, low transmission loss, small size, low weight, strong anti-electromagnetic interference capability and the like, can effectively improve the transmission capacity and transmission rate of a communication system, and is widely favored in many microwave and millimeter wave applications, such as microwave photonic radar, phased array antenna, ROF (radio over fiber) and the like. Low dark current, high speed, high responsivity and high saturation power photodetectors are of paramount importance in RF (radio frequency) photonic links. Due to the limitation of the band gap width of the silicon material, the operating wavelength of the silicon detector is below 1100nm, and the silicon detector cannot be used for optical detection in a near infrared band. Germanium materials which are also elements of the four groups have higher light absorption efficiency in near infrared bands, silicon-based germanium materials have higher heat conductivity and are completely compatible with a silicon CMOS (complementary metal oxide semiconductor) process, so the silicon-based germanium material is suitable for manufacturing a high saturation power photoelectric detector.
There are two common methods for increasing the saturation optical power of the sige detector. The first is to divide light into two parts through an on-chip optical splitter, and then the two parts enter from two ends of a germanium-silicon detector respectively, so that the gathering of photon-generated carriers at one end of the detector is reduced, and the saturation optical power of the device is improved. The second is to gradually couple the optical signal into the detector through a gradual change waveguide on one side of the detector, so that the light is distributed relatively uniformly in the detector, thereby improving the saturation optical power of the device. The first method needs to adopt an on-chip waveguide optical splitter for splitting, the processing precision of the on-chip waveguide optical splitter is higher, the overall size of the device is relatively larger, and the optical splitter has certain optical loss, so that the responsivity is lower (Optics Express,23 (2015)) 2285722866 ℃; the main problem of the second method is that although the side waveguide can homogenize the optical field intensity in the detector, it is difficult to satisfy the effective light absorption length at the same time, and thus the light responsivity is also low. The lateral waveguide and the occupation of the lower electrode area of the probe lead to a large series resistance and limited bandwidth of the device (Optics Letter,42(2017) 851854.).
Therefore, designing a silicon-based detector with simple process, high responsivity, high speed and high saturation optical power is an important research subject.
Disclosure of Invention
In view of this, the present invention provides a silicon-based detector with gradually changing width and a method for manufacturing the same, in order to obtain a silicon-based detector with high saturation optical power.
The invention provides a silicon-based detector with gradually changed width, which comprises: an SOI substrate comprising: a bottom silicon material layer; a silicon dioxide buried layer formed on the bottom silicon material layer; and the top silicon formed on the silicon dioxide filling layer, a waveguide layer is formed on the top silicon; the n-type lightly doped region is formed on the waveguide layer; the n-type heavily doped region is formed at two sides of the n-type lightly doped region; the light absorption layer is formed on the n-type lightly doped region, and a light absorption layer p-type heavily doped region is formed on part of the upper surface of the light absorption layer; the silicon dioxide window layer is formed on the top silicon layer and the waveguide layer, and an epitaxial window matched with the bottom edge of the light absorption layer in size is formed on the silicon dioxide window layer corresponding to the waveguide layer; the insulating medium layer is formed on the light absorption layer and the silicon dioxide window layer; wherein, a first electrode window is arranged on the silicon dioxide window layer and the insulating medium layer corresponding to the n-type heavily doped region; a second electrode window is formed on the insulating medium layer corresponding to the p-type heavily doped region of the light absorption layer; the n electrode is formed on the first electrode window and is electrically connected with the n-type heavily doped region; the p electrode is formed on the second electrode window and is electrically connected with the p-type heavily doped region of the light absorption layer; the width of the light absorption layer close to the light incidence end is larger than that of the light absorption layer far away from the light incidence end, and the width of the light absorption layer is smoothly changed gradually.
In the embodiment of the present invention, the width of the light absorbing layer is smoothly graded according to the light absorption coefficient of the light absorbing layer.
In the embodiment of the invention, the width of the light absorption layer close to the light incidence end is 8-10 μm, and the width of the light absorption layer far away from the light incidence end is 2-4 μm; the length of the light absorption layer is 8 to 15 μm. In an embodiment of the invention, the waveguide layer is a strip waveguide or a ridge waveguide.
In an embodiment of the present invention, the width of the n-type lightly doped region is greater than the width of the epitaxial window.
In the embodiment of the invention, the n-type lightly doped region and the n-type heavily doped region are positioned on the same plane; the doping concentration of the n-type lightly doped region is more than 1x1017/cm3(ii) a The doping concentration of the n-type heavily doped region is more than 5x1018/cm3。
In an embodiment of the present invention, the material of the light absorption layer is one of: pure germanium, germanium-tin alloy, InGaAs.
In an embodiment of the invention, the light absorbing layer is obtained for selective epitaxy on an epitaxy window.
In the embodiment of the invention, the doping concentration of the p-type heavily doped region of the light absorption layer is 1x1019/cm3～1x1020/cm3And the doping depth is less than 150 nm.
In the embodiment of the invention, the n-type lightly doped region, the light absorption layer and the light absorption layer p-type heavily doped region form a longitudinal PIN junction.
In an embodiment of the present invention, the insulating dielectric layer is used to electrically isolate the covered material from the external environment.
The invention also provides a preparation method of the silicon-based detector, which comprises the following steps: providing an SOI substrate, the SOI substrate comprising: a bottom silicon material layer; a silicon dioxide buried layer formed on the bottom silicon material layer; and a top silicon layer formed on the silicon dioxide buried layer; making the top layer silicon into a table-board to form a waveguide layer; forming an n-type lightly doped region on the waveguide layer; forming n-type heavily doped regions on two sides of the n-type lightly doped region; forming a silicon dioxide window layer on the top silicon and the waveguide layer, and arranging an epitaxial window on the silicon dioxide window layer corresponding to the waveguide layer; the width of the epitaxial window close to the light incidence end is larger than that of the epitaxial window far away from the light incidence end, and the width of the epitaxial window is smoothly and gradually changed; selecting an epitaxial light absorption layer in the epitaxial window; forming a light absorption layer p-type heavily doped region on the upper surface of the light absorption layer; forming an insulating medium layer on the light absorption layer and the silicon dioxide window layer; a first electrode window is arranged on the silicon dioxide window layer and the insulating medium layer corresponding to the n-type heavily doped region; a second electrode window is arranged on the insulating medium layer corresponding to the p-type heavily doped region of the light absorption layer; forming an n electrode on the first electrode window, wherein the n electrode is electrically connected with the n-type heavily doped region; and forming a p electrode on the second electrode window, wherein the p electrode is electrically connected with the p-type heavily doped region of the light absorption layer.
The silicon-based detector with the gradually-changed width and the preparation method thereof have the following beneficial effects:
(1) the n-type lightly doped region, the light absorption layer and the light absorption layer p-type heavily doped region form a longitudinal PIN junction, the light absorption layer has a larger width close to a light incidence end and a smaller width far away from the light incidence end, and the width of the light absorption layer is smoothly and gradually changed, so that the light intensity and the distribution uniformity of photo-generated carriers in the whole detector are ensured, the saturation effect caused by the aggregation of the photo-generated carriers is remarkably reduced, and the saturation light power of the device is improved.
(2) The obtained detector device has high responsivity because the optical light splitter does not need to be prepared.
(3) The resulting detector device has a high bandwidth due to the elimination of waveguide side coupling.
(4) The process flow for preparing the silicon-based detector is simple, and the preparation difficulty is low.
Drawings
Fig. 1 is a schematic structural diagram of a silicon-based detector with gradually changed width according to an embodiment of the present invention;
fig. 2 is a schematic three-dimensional structure diagram of a silicon-based detector with gradually changed width according to an embodiment of the present invention;
fig. 3 is a flowchart of a manufacturing process of a silicon-based detector with a gradually-varied width according to an embodiment of the present invention.
[ description of reference ]
A 100-SOI substrate; 110-top silicon; 120-silica buried layer; 130-a bottom layer of silicon material; 111-a waveguide layer; 112-n type lightly doped region; a 113-n type heavily doped region; 200-a light absorbing layer; 210-a p-type heavily doped region of the light absorbing layer; 300-a silicon dioxide window layer; 400-insulating dielectric layer; 510-n electrodes; 520-p electrode.
Detailed Description
In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.
The saturation characteristics of the photodetector are affected by thermal effects, space charge effects and series resistance voltage division. The thermal effect is determined by the structure of the device and the heat dissipation characteristic of the material, and the space charge effect and the series resistance voltage division can change the saturation characteristic of the device by changing the electric field intensity of the depletion layer of the photoelectric detector. The series resistance is determined by the device material and the fabrication process. The space charge effect depends mainly on the structure of the photodetector. On one hand, the device structure needs to be optimized, and the electric field intensity of the photoelectric detector is improved; on the other hand, the distribution of light absorbed by the photodetector needs to be optimized, so that the photon-generated carriers are uniformly distributed in the photodetector, and the electric field generated by the photon-generated carriers is reduced. Therefore, the main approach for improving the saturation optical power of the silicon-based germanium photoelectric detector is to design a reasonable structure, optimize light absorption distribution and reduce space charge effect.
The invention aims to provide a silicon-based detector with gradually-changed width and a preparation method thereof. In the detector, due to the absorption of the material to light, in the light absorption region with the same width, the light intensity is rapidly reduced along with the increase of the distance of the light absorption region, so that the distribution of photon-generated carriers in the light absorption region is uneven, and the photon-generated carriers are mainly concentrated in the front of the light absorption region. The width of the width gradual change detector gradually changes according to the absorption coefficient and the light intensity of the material, the width of the light incidence end close to the detector is larger, the width of the light incidence end far away from the detector is smaller, and the width gradual change is smoothly carried out in the middle. The well-designed gradient structure can ensure the light intensity and the distribution uniformity of the photon-generated carriers in the whole detector, and obviously reduce the saturation effect caused by the aggregation of the photon-generated carriers, thereby improving the saturation luminous power of the detector device.
Fig. 1 is a schematic structural diagram of a silicon-based detector with a gradually-changed width according to an embodiment of the present invention.
Fig. 2 is a schematic three-dimensional structure diagram of a silicon-based detector with gradually changed width according to an embodiment of the present invention.
Referring to fig. 1 and 2, the present invention provides a silicon-based detector with gradually-changed width, which includes: the SOI substrate 100, a waveguide layer 111, an n-type lightly doped region 112, an n-type heavily doped region 113, a light absorption layer 200, a light absorption layer p-type heavily doped region 210, a silicon dioxide window layer 300, an insulating medium layer 400, an n electrode 510 and a p electrode 520.
An SOI substrate 100, comprising: a bottom layer of silicon material 130; a buried silicon dioxide layer 120 formed on the bottom silicon material layer 130; and a top silicon layer 110 formed on the silicon dioxide buried layer 120, a waveguide layer 111 being formed on the top silicon layer 110; an n-type lightly doped region 112 formed on the waveguide layer 111; an n-type heavily doped region 113 formed at both sides of the n-type lightly doped region 112; a light absorbing layer 200 formed on the n-type lightly doped region 112, wherein a light absorbing layer p-type heavily doped region 210 is formed on a portion of the upper surface of the light absorbing layer 200; the silicon dioxide window layer 300 is formed on the top layer silicon 110 and the waveguide layer 111, and an epitaxial window matched with the bottom edge of the light absorption layer 200 in size is formed on the silicon dioxide window layer 300 corresponding to the waveguide layer 111; an insulating dielectric layer 400 formed on the light absorbing layer 200 and the silicon dioxide window layer 300; wherein, a first electrode window is arranged on the silicon dioxide window layer 300 and the insulating medium layer 400 corresponding to the n-type heavily doped region 113; a second electrode window is arranged on the insulating medium layer 400 corresponding to the light absorption layer p-type heavily doped region 210; an n-electrode 510 formed on the first electrode window and electrically connected to the n-type heavily doped region 113; a p-electrode 520 formed on the second electrode window and electrically connected to the light absorption layer p-type heavily doped region 210; wherein, the width of the light absorption layer 200 near the light incidence end is larger than that far away from the light incidence end, and the width of the light absorption layer 200 is smoothly changed.
According to the embodiment of the present invention, the width of the light absorption layer 200 near the light incident end is 8 to 10 μm, for example, 8 μm, 9 μm, 10 μm; the width of the light source away from the light incident end is 2 to 4 μm, and may be, for example, 2 μm, 3 μm, or 4 μm.
According to the embodiment of the invention, when the length of the light absorption layer 200 is greater than 5 μm, a better detection effect can be achieved.
According to the embodiment of the invention, the length of the light absorption layer 200 may be 8 to 15 μm, for example, 8 μm, 10 μm, 12 μm, 14 μm, 15 μm.
According to an embodiment of the present invention, the top layer silicon 110 is a lightly doped or intrinsic material with a resistivity greater than 1 ohm/cm.
Waveguide layer 111 may be a strip waveguide or a ridge waveguide in accordance with embodiments of the present invention.
According to the embodiment of the present invention, when the waveguide layer 111 is a stripe waveguide, the top silicon 110 is fabricated by etching or etching to the silicon dioxide buried layer 120 except for the waveguide layer 111.
According to an embodiment of the present invention, the waveguide layer 111 satisfies a single mode condition.
According to an embodiment of the present invention, the width of the n-type lightly doped region 112 is greater than the width of the epitaxial window.
According to the embodiment of the invention, the n-type lightly doped region 112 and the n-type heavily doped region 113 are in the same plane; the doping concentration of the n-type lightly doped region 112 is greater than 1x1017/cm3(ii) a The doping concentration of the heavily n-doped region 113 is greater than 5x1018/cm3。
According to an embodiment of the present invention, the material of the light absorbing layer 200 is one of the following: pure germanium, germanium-tin alloy, InGaAs.
According to the embodiment of the invention, the doping concentration of the p-type heavily doped region 210 of the light absorption layer is 1x1019/cm3～1x1020/cm3And the doping depth is less than 150 nm.
According to the embodiment of the invention, the n-type lightly doped region 112, the light absorption layer 200 and the light absorption layer p-type heavily doped region 210 form a longitudinal PIN junction, and the extraction of photo-generated carriers can be realized by applying an external voltage to control an electric field in the light absorption layer 200, so that the detection of an optical signal is realized.
According to an embodiment of the present invention, the insulating dielectric layer 400 is used to electrically isolate the covered material from the external environment.
Fig. 3 is a flowchart of a manufacturing process of a silicon-based detector with a gradually-varied width according to an embodiment of the present invention.
As shown in fig. 3, the present invention further provides a method for manufacturing the silicon-based detector, which includes: operations S101 to S108.
In operation S101, an SOI substrate 100 is provided, the SOI substrate 100 including: a bottom layer of silicon material 130; a buried silicon dioxide layer 120 formed on the bottom silicon material layer 130; and a top layer of silicon 110 formed on the buried silicon dioxide layer 120.
According to an embodiment of the present invention, the top silicon 110 of the SOI substrate 100 has a thickness of 220nm, a (001) direction as a crystal orientation, a p-type conductivity, and a resistivity of 10 ohm/cm.
According to an embodiment of the present invention, the thickness of the buried silicon dioxide layer 120 is 3 μm.
In operation S102, the top layer silicon 110 is fabricated as a mesa to form a waveguide layer 111.
According to the embodiment of the invention, the top silicon layer 110 is etched by adopting photoetching and dry etching methods, the etching depth is 60-220 nm, and the waveguide layer 111 is formed.
According to the embodiment of the present invention, when the etching depth is less than 220nm, the waveguide layer 111 is a ridge waveguide.
According to an embodiment of the present invention, when the etching depth reaches 220nm, the waveguide layer 111 is a stripe waveguide.
Waveguide layer 111 may be a strip waveguide or a ridge waveguide in accordance with embodiments of the present invention.
Forming an n-type lightly doped region 112 on the waveguide layer 111 in operation S103; n-type heavily doped regions 113 are formed on both sides of the n-type lightly doped region 112.
According to an embodiment of the present invention, the n-type lightly doped region 112 and the n-type heavily doped region 113 may be formed by means of ion implantation or impurity diffusion.
According to an embodiment of the present invention, ions such as phosphorous, arsenic, etc. may be implanted into the waveguide layer 111 by ion implantation, followed by annealing activation to form the n-type lightly doped region.
According to the embodiment of the invention, the n-type heavily doped region 113 is located at two sides of the n-type lightly doped region 112, and the n-type lightly doped region 112 and the n-type heavily doped region 113 have the same length.
According to the embodiment of the invention, the doping concentration of the n-type lightly doped region 112 is 1 × 1017/cm3～1x1018/cm3And the doping depth is less than 150 nm.
According to the embodiment of the invention, the doping concentration of the heavily n-type doped region 113 is 1 × 1019/cm3～1x1020/cm3And the doping depth is less than 150 nm.
In operation S104, a silicon dioxide window layer 300 is formed on the top silicon 110 and the waveguide layer 111, and an epitaxial window is opened on the silicon dioxide window layer 300 corresponding to the waveguide layer 111; the width of the epitaxial window close to the light incidence end is larger than that of the epitaxial window far away from the light incidence end, and the width of the epitaxial window is smoothly and gradually changed.
According to an embodiment of the present invention, a silicon dioxide layer is grown as the silicon dioxide window layer 300 by Plasma Enhanced Chemical Vapor Deposition (PECVD).
According to the embodiment of the invention, the epitaxial window with the gradually changed width is etched on the silicon dioxide window layer 300 by the photoetching and dry etching method, the width close to the light incidence end is larger than that far away from the light incidence end, and the width of the epitaxial window is smoothly and gradually changed.
According to the embodiment of the present invention, the width of the epitaxial window is 8 to 10 μm near the light incident end, and the width of the epitaxial window is 2 to 4 μm far from the light incident end, and the width of the epitaxial window is smoothly transited according to the light absorption coefficient of the light absorbing layer 200.
According to the embodiment of the invention, the length of the epitaxial window is 8-15 μm, so that a good light absorption effect can be ensured.
According to an embodiment of the present invention, the width of the n-type lightly doped region 112 is greater than the width of the epitaxial window.
According to the embodiment of the invention, the forming mode of the epitaxial window comprises wet etching, dry etching or a mixed etching method of firstly dry etching and then wet etching.
According to the embodiment of the invention, a hybrid etching method of firstly dry etching and then wet etching is adopted, so that the pattern transfer precision is ensured, and the surface roughness and defects caused by dry etching are avoided.
Selecting an epitaxial light absorption layer 200 in the epitaxial window in operation S105; a light absorbing layer p-type heavily doped region 210 is formed on the upper surface of the light absorbing layer 200.
According to an embodiment of the present invention, the epitaxial window may be rectangular, and the epitaxial light absorption layer 200 is selected in the rectangular epitaxial window of the silicon dioxide window layer 300 using an ultra high vacuum chemical vapor deposition system (UHV-CVD).
According to an embodiment of the present invention, the material of the light absorbing layer 200 is one of the following: pure germanium, germanium-tin alloy and InGaAs with a thickness of 400-800 nm, such as 400nm, 500nm, 600nm, 700nm and 800 nm.
According to the embodiment of the invention, when the light absorption layer 200 is made of pure germanium, the working wavelength is 1200-1630 nm.
According to the embodiment of the invention, when the light absorption layer 200 is made of germanium-tin alloy, the working wavelength can be 1200-2500 nm by adjusting the tin component in the germanium-tin alloy.
According to the embodiment of the invention, when the material of the light absorption layer 200 is InGaAs, the working wavelength is 1200-2500 nm by adjusting the In component In the InGaAs.
According to an embodiment of the present invention, the light absorbing layer 200 may be implemented by selective epitaxy or etching.
According to the embodiment of the present invention, the light absorbing layer 200 is formed using selective epitaxy, the shape of which is controlled by the epitaxial window of the silicon dioxide window layer 300 and the epitaxial process together, without changing the shape thereof by etching or etching at a later stage.
According to an embodiment of the present invention, the light absorbing layer p-type heavily doped region 210 may be formed on the upper surface of the light absorbing layer 200 by means of ion implantation or impurity diffusion.
According to an embodiment of the present invention, ions such as boron and gallium are implanted into the upper surface of the light absorbing layer 200 by ion implantation, and then annealing is performed to form the p-type heavily doped region 210 of the light absorbing layer.
According to an embodiment of the present invention, the light absorbing layer p-type heavily doped region 210 is located at the center of the light absorbing layer 200.
According to the embodiment of the invention, the doping concentration of the p-type heavily doped region 210 of the light absorption layer is 1x1019/cm3～1x1020/cm3And the doping depth is less than 150 nm.
According to an embodiment of the present invention, the n-type lightly doped region 112, the light absorbing layer 200, and the light absorbing layer p-type heavily doped region 210 form a vertical PIN junction.
According to the embodiment of the invention, the p-type lightly doped region, the light absorption layer and the light absorption layer n-type heavily doped region form a longitudinal PIN junction by adopting opposite doping types, and the structure can also control the electric field in the light absorption layer by applying external voltage to realize the same light detection function.
In operation S106, an insulating dielectric layer 400 is formed on the light absorbing layer 200 and the silicon dioxide window layer 300.
According to an embodiment of the present invention, the insulating dielectric layer 400 may be SiO2Or Si3N4。
According to an embodiment of the invention, the SiO is deposited by plasma enhanced chemical vapor deposition2The thickness of the insulating dielectric layer 400 may be 300 to 1000nm, for example, 300nm, 500nm, 700nm, 800nm, or 1000 nm.
In operation S107, a first electrode window is formed on the silicon dioxide window layer 300 and the insulating dielectric layer 400 corresponding to the n-type heavily doped region 113; a second electrode window is formed on the insulating medium layer 400 corresponding to the p-type heavily doped region 210 of the light absorption layer.
According to the embodiment of the invention, the first electrode window and the second electrode window are formed in a dry etching mode by using the photoresist as a mask.
In operation S108, an n-electrode is formed on the first electrode window, and the n-electrode is electrically connected to the n-type heavily doped region; and forming a p electrode on the second electrode window, wherein the p electrode is electrically connected with the p-type heavily doped region of the light absorption layer.
According to the embodiment of the invention, the n-electrode 510 is electrically connected with the heavily doped n-type region 113, the p-electrode 520 is electrically connected with the heavily doped p-type region 210 of the light absorption layer, and good ohmic contact is realized.
In the embodiment of the invention, the n-type lightly doped region, the light absorption layer and the p-type heavily doped region of the light absorption layer form a longitudinal PIN junction, the width of the light absorption layer close to the light incidence end is larger, the width of the light absorption layer far away from the light incidence end is smaller, and the width of the light absorption layer is smoothly and gradually changed, so that the light intensity and the distribution uniformity of photon-generated carriers in the whole detector are ensured, the saturation effect caused by the aggregation of the photon-generated carriers is obviously reduced, and the saturation light power of the device is improved.
In the embodiment of the invention, the obtained detector device has high responsivity because an optical light splitter does not need to be prepared.
In embodiments of the present invention, the resulting detector device has a high bandwidth due to the elimination of waveguide side coupling.
In the embodiment of the invention, the process flow for preparing the silicon-based detector is simple, and the preparation difficulty is low.
It should be noted that while this patent may provide examples of parameters that include particular values, it should be appreciated that the parameters need not be exactly equal to the corresponding values, but may be approximated to the corresponding values within acceptable error tolerances or design constraints. Directional phrases used in the embodiments, such as "upper," "lower," "front," "rear," "left," "right," and the like, refer only to the orientation of the figure. Accordingly, the directional terminology used is intended to be in the nature of words of description rather than of limitation.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A silicon-based detector of gradually varying width, comprising:
an SOI substrate includes a bottom silicon material layer; a silicon dioxide buried layer formed on the bottom silicon material layer; and the top silicon layer is formed on the silicon dioxide filling layer, and a waveguide layer is formed on the top silicon layer;
the n-type lightly doped region is formed on the waveguide layer;
the n-type heavily doped region is formed at two sides of the n-type lightly doped region;
the light absorption layer is formed on the n-type lightly doped region, and a light absorption layer p-type heavily doped region is formed on part of the upper surface of the light absorption layer;
the silicon dioxide window layer is formed on the top layer silicon and the waveguide layer, and an epitaxial window matched with the bottom edge of the light absorption layer in size is formed on the silicon dioxide window layer corresponding to the waveguide layer;
an insulating dielectric layer formed on the light absorbing layer and the silicon dioxide window layer;
the silicon dioxide window layer corresponding to the n-type heavily doped region and the insulating medium layer are provided with first electrode windows;
a second electrode window is formed in the insulating medium layer corresponding to the p-type heavily doped region of the light absorption layer;
the n electrode is formed on the first electrode window and is electrically connected with the n-type heavily doped region;
the p electrode is formed on the second electrode window and is electrically connected with the p-type heavily doped region of the light absorption layer;
the width of the light absorption layer close to the light incidence end is larger than that of the light absorption layer far away from the light incidence end, and the width of the light absorption layer is smoothly gradually changed.
2. The silicon-based detector of claim 1, wherein the width of the light absorption layer is smoothly graded according to the light absorption coefficient of the light absorption layer.
3. The silicon-based detector of claim 1, wherein the waveguide layer is a slab waveguide or a ridge waveguide.
4. The silicon-based detector of claim 1, wherein the n-type lightly doped region has a width greater than a width of the epitaxial window.
5. The silicon-based detector of claim 1, wherein the n-type lightly doped region and the n-type heavily doped region are in a same plane.
6. The silicon-based probe of claim 1, wherein the light absorption layer is made of one of: pure germanium, germanium-tin alloy, InGaAs.
7. A silicon-based detector according to claim 1, wherein the light absorbing layer is obtained by selective epitaxy on the epitaxial window.
8. The silicon-based detector of claim 1, wherein the n-type lightly doped region, the light absorption layer, and the light absorption layer p-type heavily doped region form a longitudinal PIN junction.
9. The silicon-based probe of claim 1, wherein the dielectric layer is configured to electrically isolate the covered material from an external environment.
10. A method of fabricating a silicon-based detector as claimed in any one of claims 1 to 9, comprising:
providing an SOI substrate, the SOI substrate comprising: a bottom silicon material layer; a silicon dioxide buried layer formed on the bottom silicon material layer; and a top silicon layer formed on the silicon dioxide buried layer;
manufacturing the top layer silicon into a table top to form a waveguide layer;
forming an n-type lightly doped region on the waveguide layer;
forming n-type heavily doped regions on two sides of the n-type lightly doped region;
forming a silicon dioxide window layer on the top silicon layer and the waveguide layer, and arranging an epitaxial window on the silicon dioxide window layer corresponding to the waveguide layer;
the width of the epitaxial window close to the light incidence end is larger than that of the epitaxial window far away from the light incidence end, and the width of the epitaxial window is smoothly and gradually changed;
selecting an epitaxial light absorption layer in the epitaxial window;
forming a light absorption layer p-type heavily doped region on the upper surface of the light absorption layer;
forming an insulating medium layer on the light absorption layer and the silicon dioxide window layer;
a first electrode window is arranged on the silicon dioxide window layer and the insulating medium layer corresponding to the n-type heavily doped region;
a second electrode window is arranged on the insulating medium layer corresponding to the p-type heavily doped region of the light absorption layer;
forming an n electrode on the first electrode window, wherein the n electrode is electrically connected with the n-type heavily doped region;
and forming a p electrode on the second electrode window, wherein the p electrode is electrically connected with the p-type heavily doped region of the light absorption layer.
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