A silicon-based high-saturation detector and a method for preparing the same

Abstract

The present invention discloses a silicon-based high saturation detector and a preparation method thereof, wherein an n-type lightly doped region is arranged on the upper side of an SOI substrate, n-type heavily doped regions are formed on both sides of the n-type lightly doped region, a light absorbing layer is arranged on the upper side of the n-type lightly doped region, a light absorbing layer p-type heavily doped region is arranged on the upper surface of the light absorbing layer, a silicon dioxide window layer is arranged on the upper side of the SOI substrate and a gradient window matching the light absorbing layer is opened on the silicon dioxide window layer, an insulating medium layer is arranged on the upper side of the light absorbing layer and the silicon dioxide window layer, a plurality of electrodes are respectively connected to the n-type heavily doped region or the p-type heavily doped region of the light absorbing layer, a hole is opened at the bottom of the SOI substrate, and a reflective heat-conducting metal is arranged in the hole at the bottom of the SOI substrate and on the bottom surface of the SOI substrate. The present invention has the advantages of high responsiveness, high saturated optical power and stable mechanical structure.

Description

Technical Field

[0001] The invention relates to a detector and a preparation method thereof, in particular to a silicon-based high-saturation detector and a preparation method thereof, belonging to the technical field of semiconductor chips. Background Art

[0002] High-frequency photonic links have the advantages of wide bandwidth, low transmission loss, small size, low weight and strong anti-electromagnetic interference ability. They can effectively improve the transmission capacity and transmission rate of communication systems and are widely favored in many microwave and millimeter wave applications, such as microwave photonic radar, phased array antenna and ROF optical carrier communication. Low dark current, high speed, high response and high saturation power photodetectors are crucial in RF photonic links. Due to the limitation of its bandgap width, the working wavelength of silicon detectors is below 1100nm, which is not competent for light detection in the near-infrared band. Germanium materials, which are also group IV elements, have high light absorption efficiency in the near-infrared band. Silicon-based germanium materials have high thermal conductivity and are fully compatible with silicon CMOS processes, so they are suitable for making high saturation power photodetectors.

[0003] The saturation characteristics of photodetectors are affected by thermal effects, space charge effects, and series resistance voltage dividers. The thermal effect is determined by the structure of the device and the heat dissipation characteristics of the material, so it can be improved through the structure, thereby effectively improving the saturation characteristics of the detector. The conventional heat dissipation structure is to flip the chip upside down on a specific traveling wave electrode in the form of flip-chip soldering, use the traveling wave electrode and its substrate for heat dissipation, and introduce the optical signal from the back of the device. However, this structure requires a complex flip-chip soldering structure, has high requirements for chip alignment, and is relatively expensive. Another common structure is to thin the substrate as much as possible and prepare metal on the back of the substrate to improve thermal conductivity. However, when the thickness of the substrate is thinned to 100μm or less, it becomes extremely fragile and difficult to use. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a silicon-based high-saturation detector and a preparation method thereof, so as to improve the responsiveness of the device and improve the high-saturation characteristics of the device.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A silicon-based high-saturation detector comprises an SOI substrate, an n-type lightly doped region, a light absorption layer, a silicon dioxide window layer, an insulating dielectric layer, electrodes and a reflective heat-conducting metal, wherein the n-type lightly doped region is arranged on the upper side of the SOI substrate, n-type heavily doped regions are formed on both sides of the n-type lightly doped region, the light absorption layer is arranged on the upper side of the n-type lightly doped region, a light absorption layer p-type heavily doped region is arranged on the upper surface of the light absorption layer, the silicon dioxide window layer is arranged on the upper side of the SOI substrate and a gradient window matching the light absorption layer is opened on the silicon dioxide window layer, the insulating dielectric layer is arranged on the upper side of the light absorption layer and the silicon dioxide window layer, a plurality of electrodes are respectively connected to the n-type heavily doped region or the p-type heavily doped region of the light absorption layer, the bottom of the SOI substrate has an opening, and the reflective heat-conducting metal is arranged in the opening at the bottom of the SOI substrate and on the bottom surface of the SOI substrate.

[0007] Furthermore, the SOI substrate comprises a bottom Si material layer, a silicon dioxide buried layer and a top silicon layer, which are arranged in sequence from bottom to top, the top silicon layer adopts lightly doped or intrinsic material, and the resistivity of the top silicon layer is greater than 1 ohm / cm.

[0008] Furthermore, the doping concentration of the n-type lightly doped region is greater than 1*10 17 / cm 3 , the doping concentration of the n-type heavily doped region is greater than 5*10 18 / cm 3 , the doping concentration of the p-type heavily doped region of the light absorption layer is greater than 1*10 18 / cm 3 .

[0009] Furthermore, the silicon dioxide window layer is manufactured by chemical vapor deposition, and the epitaxial window of the silicon dioxide window layer is manufactured by a hybrid etching valve of dry etching first and wet etching later.

[0010] Furthermore, an electrode window is opened on the insulating medium layer corresponding to the p-type heavily doped region of the light absorption layer, and an electrode window is opened on the insulating medium layer and the silicon dioxide window layer corresponding to the n-type heavily doped region.

[0011] Furthermore, the electrode includes an n-electrode and a p-electrode, the n-electrode passes through the electrode window on the insulating dielectric layer and the silicon dioxide window layer to connect to the n-type heavily doped region, and the p-electrode passes through the electrode window on the insulating dielectric layer to connect to the p-type heavily doped region of the light absorption layer.

[0012] Furthermore, a hole is opened in the middle of the bottom of the SOI substrate, and the hole penetrates from bottom to top to the top of the bottom Si material layer or the top of the silicon dioxide buried layer, and the cross-sectional area range of the hole is larger than the area range of the light absorption layer.

[0013] Furthermore, the reflective heat-conducting metal includes a heat dissipation bottom and a reflective heat-conducting portion, the heat dissipation bottom area matches the bottom surface of the SOI substrate, the reflective heat-conducting portion matches the bottom opening of the SOI substrate, and the reflective heat-conducting portion is inserted into the bottom opening of the SOI substrate.

[0014] A method for preparing a silicon-based high-saturation detector comprises the following steps:

[0015] Step 1: The top silicon of the SOI substrate is made into a mesa by etching or corroding; the thickness of the top silicon is 340nm, the crystal orientation is (001), the conductivity type is p-type, the resistivity is 10 ohms / cm, the thickness of the silicon dioxide buried layer is 2μm, and the top silicon is etched by photolithography and dry etching, and the etching depth is 340nm to form a top silicon mesa;

[0016] Step 2: Use ion implantation or diffusion to make n-type lightly doped regions and n-type heavily doped regions on the top silicon layer. Use photoresist as a mask and ion implantation to make n-type lightly doped regions and n-type heavily doped regions on the top silicon layer. The doping concentration of the n-type lightly doped regions is 1*10 17 / cm 3 ~1*10 18 / cm 3 , the doping depth is less than 150nm; the doping concentration of the n-type heavily doped region is 1*10 19 / cm 3 ~1*10 20 / cm 3 , doping depth is less than 150nm;

[0017] Step 3: a silicon dioxide window layer is formed around and on the top silicon layer, and an epitaxial window with a gradually varying width is formed on the silicon dioxide window layer on the top silicon layer; a silicon dioxide layer is grown by plasma enhanced chemical vapor deposition, and an epitaxial window is etched on the silicon dioxide window layer by photolithography and dry etching; the epitaxial window is circular in size with a diameter of 20-40 μm, and a part of the area of ​​the n-type lightly doped region is exposed in the epitaxial window, and the size of the n-type lightly doped region is larger than the epitaxial window;

[0018] Step 4: Select an epitaxial light absorption layer in the rectangular epitaxial window opened in the silicon dioxide window layer; after the substrate is cleaned, put it into an ultra-high vacuum chemical vapor deposition system, and select an epitaxial light absorption layer in the long strip epitaxial window of the silicon dioxide window layer, the material is pure germanium material, and the epitaxial thickness is 800~2000nm;

[0019] Step 5: Use ion implantation or diffusion to make a p-type heavily doped region of the light absorption layer on the light absorption layer; use photoresist as a mask and ion implantation to make a p-type heavily doped region of the light absorption layer on the light absorption layer. The p-type heavily doped region of the light absorption layer is located at the center of the light absorption layer, and the doping concentration of the p-type heavily doped region of the light absorption layer is 1*10 19 / cm 3 ~1*10 20 / cm 3 , doping depth is less than 150nm;

[0020] Step 6: Make an insulating dielectric layer on the light absorption layer and the silicon dioxide window layer. Electrode windows are opened on the silicon dioxide window layer and the insulating dielectric layer on the n-type heavily doped region and the insulating dielectric layer on the p-type heavily doped region of the light absorption layer. SiO 2 or Si 3 N 4 , with a thickness of 300-1000nm; using a photoresist as a mask and dry etching, an electrode window is opened on the silicon dioxide window layer and the insulating dielectric layer on the n-type heavily doped region and the insulating dielectric layer on the p-type heavily doped region of the light absorption layer;

[0021] Step 7: On the n-type heavily doped region and the p-type heavily doped region of the light absorption layer, in the electrode windows of the silicon dioxide window layer and the insulating dielectric layer, respectively, an n-electrode and a p-electrode are made to achieve good ohmic contact;

[0022] Step 8: In the bottom Si material layer and the silicon dioxide buried layer, below the top silicon layer, the bottom Si material layer is thinned to 100-200 μm by mechanical grinding; the back side uses a photoresist as a mask layer, and the silicon deep etching process etches the remaining Si substrate material, and then silicon dioxide etching is used to completely or partially remove the silicon dioxide buried oxide layer to make a back through hole;

[0023] Step 9: In the back through-holes between the bottom Si material layer and the silicon dioxide buried layer, use magnetron sputtering and electroplating to make the back reflective thermal conductive metal. First, use magnetron sputtering to evaporate a thin layer of copper, and then use electroplating to fill the back through-holes to complete the detector preparation.

[0024] Compared with the prior art, the present invention has the following advantages and effects: the present invention etches a SOI substrate at the bottom of the detector to form a through hole, and prepares a metal material with high reflection and high thermal conductivity in the through hole. On the one hand, the high reflection effect of the metal can be used to reflect the optical signal that is not completely absorbed by the device back to the absorption area, thereby improving the responsiveness of the device; on the other hand, the high thermal conductivity of the metal can be used to effectively reduce the temperature of the device, thereby improving the high saturation characteristics of the device. The detector of the present invention has the advantages of high responsiveness, high saturation optical power and stable mechanical structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of Example 1 of a silicon-based high-saturation detector of the present invention.

[0026] Figure 2 It is a schematic diagram of Example 2 of a silicon-based high-saturation detector of the present invention.

[0027] Figure 3 The present invention is a flow chart of a method for preparing a silicon-based high-saturation detector. DETAILED DESCRIPTION

[0028] In order to elaborate on the technical scheme adopted by the present invention to achieve the predetermined technical purpose, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments, and the technical means or technical features in the embodiments of the present invention can be replaced without paying creative work. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0029] like Figure 1 and Figure 2 As shown, a silicon-based high-saturation detector comprises an SOI substrate 100, an n-type lightly doped region 111, a light absorbing layer 200, a silicon dioxide window layer 300, an insulating dielectric layer 400, electrodes and a reflective heat-conducting metal 600, wherein the n-type lightly doped region 111 is arranged on the upper side of the SOI substrate 100, and n-type heavily doped regions 112 are formed on both sides of the n-type lightly doped region 111, the light absorbing layer 200 is arranged on the upper side of the n-type lightly doped region 111, and a light absorbing layer p-type heavily doped region 210 is arranged on the upper surface of the light absorbing layer 200, the silicon dioxide window layer 300 is arranged on the upper side of the SOI substrate 100 and a gradient window matching the light absorbing layer 200 is opened on the silicon dioxide window layer 300, the insulating dielectric layer 400 is arranged on the upper sides of the light absorbing layer 200 and the silicon dioxide window layer 300, and a plurality of electrodes are respectively connected to the n-type heavily doped region 112 or the light absorbing layer p-type heavily doped region 210, The bottom of the SOI substrate 100 has an opening, and the reflective heat-conducting metal 600 is disposed in the opening of the bottom of the SOI substrate 100 and on the bottom surface of the SOI substrate 100 .

[0030] The SOI substrate 100 includes a bottom Si material layer 130, a silicon dioxide buried layer 120 and a top silicon layer 110. The bottom Si material layer 130, the silicon dioxide buried layer 120 and the top silicon layer 110 are arranged in sequence from bottom to top. The top silicon layer 110 is made of lightly doped or intrinsic material, and the resistivity of the top silicon layer 110 is greater than 1 ohm / cm.

[0031] The n-type lightly doped region 111 may be implanted by ion implantation or impurity diffusion, preferably by ion implantation, such as phosphorus, arsenic ions, and then activated by annealing. The doping concentration of the n-type lightly doped region 111 is greater than 1*10 17 / cm 3 , the doping concentration of the n-type heavily doped region 112 is greater than 5*10 18 / cm 3 , achieving excellent ohmic contact.

[0032] The n-type lightly doped region 111, the light absorbing layer 200 and the p-type heavily doped region 210 of the light absorbing layer form a longitudinal PIN junction. By applying an external voltage to control the electric field in the light absorbing layer 200, the extraction of photogenerated carriers in the light absorbing layer 200 can be achieved. The light absorbing layer 200 can be realized by selective epitaxy or etching. Preferably, selective epitaxy is used. Its shape is controlled by the epitaxial window of the silicon dioxide window layer 300 and the epitaxial process. There is no need to change its shape through subsequent etching or corrosion. The p-type heavily doped region 210 of the light absorbing layer is made on the upper surface of the light absorbing layer 200. It can be made by ion implantation or impurity diffusion. Preferably, ion implantation is used to implant ions such as boron and gallium, and then activated by annealing. Its doping concentration usually needs to be greater than 1*10 18 / cm 3 The n-type heavily doped region 112, the n-type lightly doped region 111, the light absorbing layer 200 and the p-type heavily doped region 210 of the light absorbing layer form a longitudinal PIN junction. Therefore, it can be foreseen that a similar longitudinal NIP structure can be realized by using opposite doping types. The structure can also control the electric field in the light absorbing layer 200 by applying an external voltage to realize the same light detection function.

[0033] The silicon dioxide window layer 300 is made by chemical vapor deposition. The epitaxial window of the silicon dioxide window layer 300 is made by a mixed etching method of dry etching first and wet etching later. The epitaxial window of the silicon dioxide window layer 300 can be formed by wet etching or dry etching. The use of wet etching can avoid the surface roughness and defects introduced by dry etching, thereby improving the quality of the subsequent epitaxial light absorption layer 200, but the pattern transfer accuracy is not good; while dry etching has high pattern transfer accuracy, but will introduce etching defects. Therefore, the present invention adopts a mixed etching method of dry etching first and wet etching later, which not only ensures the pattern transfer accuracy, but also avoids the surface roughness and defects introduced by dry etching.

[0034] The insulating dielectric layer 400 is formed on the light absorbing layer 200 and the silicon dioxide window layer 300 to protect the covered material from electrical isolation from the external environment and from contamination by foreign objects or damage by external forces. The insulating dielectric layer 400 has an electrode window corresponding to the p-type heavily doped region 210 of the light absorbing layer, and the insulating dielectric layer 400 and the silicon dioxide window layer 300 have an electrode window corresponding to the n-type heavily doped region 112.

[0035] The electrodes include an n-electrode 510 and a p-electrode 520. The n-electrode 510 is connected to the n-type heavily doped region 112 through the electrode windows on the insulating dielectric layer 400 and the silicon dioxide window layer 300. The p-electrode 520 is connected to the p-type heavily doped region 210 of the light absorption layer through the electrode windows on the insulating dielectric layer 400.

[0036] The bottom middle of the SOI substrate 100 has a hole, which penetrates from bottom to top to the top 110 of the bottom Si material layer ( Figure 2 ) or the silicon dioxide buried layer 120 ( Figure 1 ) top, the cross-sectional area of ​​the hole is greater than the area of ​​the light absorbing layer 200. The reflective heat conductive metal 600 comprises a heat dissipation bottom and a reflective heat conductive portion, the heat dissipation bottom area matches the bottom surface of the SOI substrate 100, the reflective heat conductive portion matches the bottom opening of the SOI substrate 100, and the reflective heat conductive portion is inserted into the bottom opening of the SOI substrate 100.

[0037] like Figure 3 As shown, a method for preparing a silicon-based high-saturation detector comprises the following steps:

[0038] Step 1: The top silicon 110 of the SOI substrate 100 is made into a mesa by etching or corrosion. The thickness of the top silicon 110 is 340nm, the crystal orientation is (001), the conductivity type is p-type, and the resistivity is 10 ohms / cm. The thickness of the silicon dioxide buried layer 120 is 2μm, and the top silicon 110 is etched by photolithography and dry etching, and the etching depth is 340nm to form a mesa of the top silicon 110.

[0039] Step 2: Use ion implantation or diffusion to form an n-type lightly doped region 111 and an n-type heavily doped region 112 on the top silicon 110. Use photoresist as a mask and ion implantation to form an n-type lightly doped region 111 and an n-type heavily doped region 112 on the top silicon 110. The doping concentration of the n-type lightly doped region 111 is 1*10 17 / cm 3 ~1*10 18 / cm 3 , the doping depth is less than 150nm; the doping concentration of the n-type heavily doped region 112 is 1*10 19 / cm 3 ~1*1020 / cm 3 The n-type heavily doped region 112 is located on both sides of the n-type lightly doped region 111 , and part of the n-type lightly doped region 111 and the n-type heavily doped region 112 have the same length, which is slightly longer than the length of the light absorbing layer 200 .

[0040] Step 3: A silicon dioxide window layer 300 is formed around and on the top silicon 110. The silicon dioxide window layer 300 on the top silicon 110 has an epitaxial window with a gradually varying width. A silicon dioxide layer is grown by plasma enhanced chemical vapor deposition (PECVD), and an epitaxial window is etched on the silicon dioxide window layer by photolithography and dry etching. The epitaxial window is circular with a diameter of 20-40 μm. Part of the area of ​​the n-type lightly doped region is exposed in the epitaxial window, and the size of the n-type lightly doped region is larger than the epitaxial window.

[0041] Step 4: Select an epitaxial light absorption layer 200 in the rectangular epitaxial window opened in the silicon dioxide window layer 300. After the substrate is cleaned, it is placed in an ultra-high vacuum chemical vapor deposition system (UHV-CVD), and an epitaxial light absorption layer 200 is selected in the long strip epitaxial window of the silicon dioxide window layer 300. The material is pure germanium. The material of the light absorption layer 200 is pure germanium or germanium-tin alloy, and the epitaxial thickness is 800~2000nm. When the material of the light absorption layer 200 is pure germanium, its operating wavelength is 1200~1630nm; when the material of the light absorption layer 200 is germanium-tin alloy, the operating wavelength can be achieved in 1200~2500nm by adjusting the tin component in the germanium-tin alloy; when the material of the light absorption layer 200 is InGaAs, the operating wavelength can be achieved in 1200~2500nm by adjusting the In component in InGaAs.

[0042] Step 5: Use ion implantation or diffusion to form a p-type heavily doped region 210 on the light absorbing layer 200. Use photoresist as a mask and ion implantation to form a p-type heavily doped region 210 on the light absorbing layer 200. The p-type heavily doped region 210 is located at the center of the light absorbing layer 200. The doping concentration of the p-type heavily doped region 210 is 1*10 19 / cm 3 ~1*10 20 / cm 3 , the doping depth is less than 150nm.

[0043] Step 6: An insulating dielectric layer 400 is formed on the light absorbing layer 200 and the silicon dioxide window layer 300. Electrode windows are formed on the silicon dioxide window layer 300 and the insulating dielectric layer 400 on the n-type heavily doped region 112 and the insulating dielectric layer 400 on the p-type heavily doped region 210 of the light absorbing layer. SiO is deposited by plasma enhanced chemical vapor deposition. 2 or Si 3 N 4 , with a thickness of 300-1000nm; using photoresist as a mask and dry etching, electrode windows are opened on the silicon dioxide window layer 300 and the insulating dielectric layer 400 on the n-type heavily doped region 112 and the insulating dielectric layer 400 on the p-type heavily doped region 210 of the light absorbing layer.

[0044] Step 7: On the n-type heavily doped region 112 and the light absorbing layer p-type heavily doped region 210, in the electrode windows of the silicon dioxide window layer 300 and the insulating dielectric layer 400, respectively, an n-electrode 510 and a p-electrode 520 are fabricated to achieve good ohmic contact.

[0045] Step 8: In the bottom Si material layer 130 and the silicon dioxide buried layer 120, below the top silicon 110, the bottom Si material layer is thinned to 100-200 μm by mechanical grinding. The back side uses a photoresist as a mask layer, and the silicon deep etching process etches the remaining Si substrate material, and then silicon dioxide etching is used to completely or partially remove the silicon dioxide buried oxide layer to make a back through hole.

[0046] Step 9: In the back through-holes in the bottom Si material layer 130 and the silicon dioxide buried layer 120, a back reflective thermal conductive metal, such as copper, gold or aluminum, is made by magnetron sputtering and electroplating. First, a thin layer of copper is evaporated by magnetron sputtering, and then the back through-holes are filled by electroplating to complete the detector preparation.

[0047] The present invention etches a SOI substrate at the bottom of the detector to form a through hole, and prepares a metal material with high reflection and high thermal conductivity in the through hole. On the one hand, the high reflection effect of the metal can be used to reflect the optical signal that is not completely absorbed by the device back to the absorption area, thereby improving the responsiveness of the device; on the other hand, the high thermal conductivity of the metal can be used to effectively reduce the temperature of the device, thereby improving the high saturation characteristics of the device. The detector of the present invention has the advantages of high responsiveness, high saturation optical power and stable mechanical structure.

[0048] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A silicon-based high saturation detector, characterized in that: The invention comprises an SOI substrate, an n-type lightly doped region, a light absorbing layer, a silicon dioxide window layer, an insulating dielectric layer, an electrode and a reflective heat-conducting metal, wherein the n-type lightly doped region is arranged on the upper side of the SOI substrate, n-type heavily doped regions are formed on both sides of the n-type lightly doped region, the light absorbing layer is arranged on the upper side of the n-type lightly doped region, a light absorbing layer p-type heavily doped region is arranged on the upper surface of the light absorbing layer, the silicon dioxide window layer is arranged on the upper side of the SOI substrate and a gradient window matching the light absorbing layer is opened on the silicon dioxide window layer, the insulating dielectric layer is arranged on the upper side of the light absorbing layer and the silicon dioxide window layer, a plurality of electrodes are respectively connected to the n-type heavily doped region or the p-type heavily doped region of the light absorbing layer, a hole is opened at the bottom of the SOI substrate, and the reflective heat-conducting metal is arranged in the hole at the bottom of the SOI substrate and on the bottom surface of the SOI substrate; The SOI substrate comprises a bottom Si material layer, a silicon dioxide buried layer and a top silicon layer, which are arranged in sequence from bottom to top, the top silicon layer adopts lightly doped or intrinsic material, and the resistivity of the top silicon layer is greater than 1 ohm / cm; a hole is opened in the middle of the bottom of the SOI substrate, the hole penetrates from bottom to top to the top of the bottom Si material layer or the top of the silicon dioxide buried layer, and the cross-sectional area range of the hole is greater than the area range of the light absorption layer; the reflective heat-conducting metal comprises a heat dissipation bottom and a reflective heat-conducting part, the area of ​​the heat dissipation bottom matches the bottom surface of the SOI substrate, the reflective heat-conducting part matches the opening at the bottom of the SOI substrate, and the reflective heat-conducting part is inserted into the opening at the bottom of the SOI substrate.

2. The silicon-based high saturation detector according to claim 1, characterized in that: The doping concentration of the n-type lightly doped region is greater than 1*10 17 / cm 3 , the doping concentration of the n-type heavily doped region is greater than 5*10 18 / cm 3 , the doping concentration of the p-type heavily doped region of the light absorption layer is greater than 1*10 18 / cm 3 .

3. The silicon-based high saturation detector according to claim 1, characterized in that: The silicon dioxide window layer is manufactured by chemical vapor deposition, and the epitaxial window of the silicon dioxide window layer is manufactured by a mixed etching method of first dry etching and then wet etching.

4. The silicon-based high saturation detector according to claim 1, characterized in that: The insulating medium layer is provided with an electrode window corresponding to the p-type heavily doped region of the light absorption layer, and the insulating medium layer and the silicon dioxide window layer are provided with an electrode window corresponding to the n-type heavily doped region.

5. The silicon-based high saturation detector according to claim 4, characterized in that: The electrodes include an n-electrode and a p-electrode. The n-electrode passes through the electrode window on the insulating dielectric layer and the silicon dioxide window layer to connect with the n-type heavily doped region. The p-electrode passes through the electrode window on the insulating dielectric layer to connect with the p-type heavily doped region of the light absorption layer.

6. A method for preparing a silicon-based high-saturation detector according to any one of claims 1 to 5, characterized in that The following steps are involved: Step 1: The top silicon of the SOI substrate is made into a mesa by etching or corroding; the thickness of the top silicon is 340nm, the crystal orientation is (001), the conductivity type is p-type, the resistivity is 10 ohms / cm, the thickness of the silicon dioxide buried layer is 2μm, and the top silicon is etched by photolithography and dry etching, and the etching depth is 340nm to form a top silicon mesa; Step 2: Use ion implantation or diffusion to make n-type lightly doped regions and n-type heavily doped regions on the top silicon layer. Use photoresist as a mask and ion implantation to make n-type lightly doped regions and n-type heavily doped regions on the top silicon layer. The doping concentration of the n-type lightly doped regions is 1*10 17 / cm 3 ~1*10 18 / cm 3 , the doping depth is less than 150nm; the doping concentration of the n-type heavily doped region is 1*10 19 / cm 3 ~1*10 20 / cm 3 , doping depth is less than 150nm; Step 3: a silicon dioxide window layer is formed around and on the top silicon layer, and an epitaxial window with a gradually varying width is formed on the silicon dioxide window layer on the top silicon layer; a silicon dioxide layer is grown by plasma enhanced chemical vapor deposition, and an epitaxial window is etched on the silicon dioxide window layer by photolithography and dry etching; a part of the area of ​​the n-type lightly doped region is exposed in the epitaxial window, and the size of the n-type lightly doped region is larger than the epitaxial window; Step 4: Select an epitaxial light absorption layer in the rectangular epitaxial window opened in the silicon dioxide window layer; after the substrate is cleaned, put it into an ultra-high vacuum chemical vapor deposition system, and select an epitaxial light absorption layer in the epitaxial window of the silicon dioxide window layer, the material is pure germanium material, and the epitaxial thickness is 800~2000nm; Step 5: Use ion implantation or diffusion to make a p-type heavily doped region of the light absorption layer on the light absorption layer; use photoresist as a mask and ion implantation to make a p-type heavily doped region of the light absorption layer on the light absorption layer. The p-type heavily doped region of the light absorption layer is located at the center of the light absorption layer, and the doping concentration of the p-type heavily doped region of the light absorption layer is 1*10 19 / cm 3 ~1*10 20 / cm 3 , doping depth is less than 150nm; Step 6: an insulating dielectric layer is fabricated on the light absorbing layer and the silicon dioxide window layer, and electrode windows are formed on the silicon dioxide window layer and the insulating dielectric layer on the n-type heavily doped region and the insulating dielectric layer on the p-type heavily doped region of the light absorbing layer; SiO2 or Si3N4 is deposited by plasma enhanced chemical vapor deposition with a thickness of 300-1000nm; a photoresist is used as a mask and dry etching is performed to form electrode windows on the silicon dioxide window layer and the insulating dielectric layer on the n-type heavily doped region and the insulating dielectric layer on the p-type heavily doped region of the light absorbing layer; Step 7: On the n-type heavily doped region and the p-type heavily doped region of the light absorption layer, in the electrode windows of the silicon dioxide window layer and the insulating dielectric layer, respectively, an n-electrode and a p-electrode are fabricated; Step 8: Thin the bottom Si material layer to 100-200 μm by mechanical grinding between the bottom Si material layer and the silicon dioxide buried layer and below the top silicon layer; The back side uses photoresist as a mask layer, and the remaining Si substrate material is etched by a silicon deep etching process, and then the silicon dioxide buried oxide layer is completely or partially removed by silicon dioxide etching to make a back side through hole; Step 9: In the back through-holes between the bottom Si material layer and the silicon dioxide buried layer, use magnetron sputtering and electroplating to make the back reflective thermal conductive metal. First, use magnetron sputtering to evaporate a thin layer of copper, and then use electroplating to fill the back through-holes to complete the detector preparation.

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