CN114284377B

CN114284377B - Double-sided Si-based AlGaN detector and preparation method thereof

Info

Publication number: CN114284377B
Application number: CN202111679021.7A
Authority: CN
Inventors: 张怡静; 陈明; 王建明; 闫大鹏
Original assignee: Wuhan Raycus Fiber Laser Technologies Co Ltd
Current assignee: Wuhan Raycus Fiber Laser Technologies Co Ltd
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2023-07-28
Anticipated expiration: 2041-12-31
Also published as: CN114284377A

Abstract

The invention provides a double-sided Si-based AlGaN detector and a preparation method thereof. The double-sided Si-based AlGaN detector comprises a Si-based substrate, a buffer layer, an AlGaN undoped layer, a BOX buried layer, a top Si-based thin film layer, a first electrode and a second electrode. Through the buffer layer, the combination effect of the AlGaN detector structure and the Si detector structure is improved, the double-sided Si-based AlGaN detector is realized, and the detection wavelength range is enlarged compared with a single Si detector or a single AlGaN solar blind detector. The real-time detection of the mixed wavelength is realized, the cost is saved, and the development of Si-based integration is facilitated.

Description

Double-sided Si-based AlGaN detector and preparation method thereof

Technical Field

The invention relates to the technical field of ultraviolet detectors, in particular to a double-sided Si-based AlGaN detector and a preparation method thereof.

Background

Electromagnetic waves in the wavelength range of 10 to 400nm are called ultraviolet rays and are divided into four sub-portions in this band: long wave ultraviolet (UV-Sup>A), medium wave ultraviolet (UV-B), short wave ultraviolet (UV-C) and vacuum ultraviolet (vacuum UV). Their corresponding wavelength ranges in the ultraviolet spectrum are 400-320 nm, 320-280 nm, 280-200 nm and 200-10 nm, respectively. Solar radiation is the predominant source of radiation at the earth's surface, where ultraviolet radiation having a wavelength less than 200nm is absorbed by gaseous molecules and free atoms in the atmosphere, leaving them completely absent at the earth's surface. Ultraviolet radiation having a wavelength below 300nm is absorbed by the ozone layer surrounding the earth. This means that when sunlight is directed onto the earth's surface, there is only solar radiation in the ultraviolet band with wavelengths between 300 and 400nm, whereas radiation in the range of 200-280 nm cannot reach the earth's surface due to absorption, this band being called solar dead zone. The plume sprayed by the missile propelled by the solid fuel has strong solar blind ultraviolet radiation, and the solar blind ultraviolet photoelectric detector with reliable performance can realize the warning of extremely low false alarm rate, so that the strategic significance is very great. AlGaN-based materials belong to direct band gap wide forbidden band semiconductors, the forbidden band width can be continuously adjusted from 3.4eV to 6.2eV through Al component adjustment, and the intrinsic cutoff wavelength covers the ultraviolet band of 200nm to 365nm, so that the AlGaN-based materials are ideal materials for preparing the intrinsic cutoff spectral response solar blind ultraviolet detector. In addition, the AlGaN-based solar blind ultraviolet photoelectric detector has the advantages of no need of filtering, small volume, small mass and capability of working in extreme environments.

In addition, the Si-based photodetector is the device with the longest development time and the most mature process technology in all photodetectors. Not only is Si one of the earliest semiconductor materials discovered, but also Si has the advantages of easy production, rich resources, low cost, easy doping and the like, and along with the development of microelectronic technology, the related technology also leads the preparation process of the Si photoelectric detector to be in the leading position. The energy of the absorption band gap of Si is 1.12eV, and the corresponding absorption band is 300 nm-1100 nm. Aiming at the application requirements of different application fields, the Si photoelectric detector develops a diversified structure and mainly comprises a SiPN junction photoelectric detector, a SiMSM photoelectric detector, a SiAPD and a Si-based PIN photoelectric detector.

Based on the method, if the AlGaN-based solar blind ultraviolet photoelectric detector and the Si-based photoelectric detector can be combined to form the double-sided Si-based AlGaN detector, not only can the expansion of detection wavelength be realized, but also the size occupied by devices can be reduced, and the hybrid integration of the multi-wavelength detector is facilitated.

Based on the above problems, it is necessary to provide a new double-sided Si-based AlGaN detector to achieve better combination of AlGaN-based solar blind uv photodetectors and Si-based photodetectors.

Disclosure of Invention

The invention mainly aims to provide a double-sided Si-based AlGaN detector and a preparation method thereof, which are used for solving the problem that an AlGaN-based solar blind ultraviolet photoelectric detector and an Si-based photoelectric detector are difficult to combine well in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a double-sided Si-based AlGaN detector including: a Si-based substrate having opposing first and second surfaces; the buffer layer is arranged on the first surface of the Si-based substrate and is a ZnO layer or an AlN layer; the AlGaN undoped layer is arranged on one side surface of the buffer layer, which is far away from the Si base substrate; a BOX buried layer disposed on the second surface of the Si-based substrate; the top Si-based film layer is arranged on the surface of one side, far away from the Si-based substrate, of the BOX buried layer; the first electrode is arranged on one side of the AlGaN undoped layer, which is far away from the buffer layer; and a second electrode disposed on a side of the top Si-based thin film layer away from the BOX buried layer.

Further, the double-sided Si-based AlGaN detector further includes: and the GaN strain layer is arranged between the buffer layer and the AlGaN undoped layer.

Further, the material of the AlGaN undoped layer is Al _x Ga _1-x N, wherein 0 < x < 1; the Si-based substrate and the top Si-based thin film layer are simultaneously Si or simultaneously SiC.

Further, the thickness of the buffer layer is 1-10 μm, the thickness of the GaN strain layer is 20-200 nm, the thickness of the AlGaN undoped layer is 50-500 nm, the thickness of the BOX buried layer is 1-20 μm, and the thickness of the top Si-based thin film layer is 50-1000 nm.

Further, the first electrode comprises a first N-type electrode and a first P-type electrode, and the first N-type electrode and the first P-type electrode form an interdigital electrode; the second electrode comprises a second N-type electrode and a second P-type electrode, and the second N-type electrode and the second P-type electrode form an interdigital electrode.

Further, the top Si-based film layer is provided with an N-type doped region, a P-type doped region and a neutral region, wherein the N-type doped region and the P-type doped region form an interdigital structure, and the N-type doped region and the P-type doped region are arranged at intervals through the neutral region; the second N-type electrode is arranged on one side, far away from the BOX buried layer, of the N-type doped region, and the second P-type electrode is arranged on one side, far away from the BOX buried layer, of the P-type doped region.

Further, the first N-type electrode, the first P-type electrode, the second N-type electrode and the second P-type electrode are all made of Ti/Al/Ti/Au materials.

According to another aspect of the present invention, there is provided a method for manufacturing the above-mentioned double-sided Si-based AlGaN detector, comprising the steps of: step S1, providing a composite wafer, which comprises a Si-based substrate, a BOX buried layer and a top Si-based film layer which are sequentially stacked; step S2, a buffer layer grows on the first surface of the Si-based substrate of the composite wafer by adopting a first plasma sputtering or first MOCVD epitaxial growth mode; s3, forming an AlGaN undoped layer on the surface of one side of the buffer layer, which is far away from the Si-based substrate, by adopting a second plasma sputtering or second MOCVD epitaxial growth mode; step S4, forming a first electrode on one side of the AlGaN undoped layer, which is far away from the buffer layer; and forming a second electrode on one side of the top Si-based film layer far away from the BOX buried layer, thereby forming the double-sided Si-based AlGaN detector.

Further, when the buffer layer is a ZnO layer, the buffer layer is formed by a first plasma sputtering method, which includes: providing a plasma sputtering apparatus; placing a ZnO target in a cathode shielding cover, placing a composite wafer on a base station, and enabling the first surface of the Si-based substrate to face upwards; closing the chamber of the plasma sputtering equipment, and vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10 ^-5 Pa, and then filling argon gas to make the air pressure reach 1-10 MPa; applying 380-1000V voltage to ZnO target material to make first plasma sputtering so as to form buffer layer; when the buffer layer is an AlN layer, the buffer layer is formed by using a first MOCVD epitaxial growth method, which includes: heating the composite wafer to 1200-1300 ℃, and then placing the composite wafer in a hydrogen environment for 10-60 min; cooling the composite wafer to 700-900 ℃, and then growing an AlN nucleation layer on the first surface of the Si-based substrate by taking trimethylaluminum as an aluminum source and ammonia as a nitrogen source; and continuously heating the composite wafer to 1180-1250 ℃ to recrystallize the AlN nucleation layer so as to form a buffer layer.

Further, the second plasma sputtering process includes: by Al _x Ga _1-x An alloy target, wherein x is more than 0 and less than 1; vacuumizing until the vacuum degree in the cavity is less than 1×10 ^-5 Pa, and then filling mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of the argon to the nitrogen is 1:7-8; to Al _x Ga _1-x Applying 220-1000V voltage to the alloy target material to perform second plasma sputtering so as to form an AlGaN undoped layer; second MOCVD epitaxial growthThe process of (1) comprises: and carrying out MOCVD epitaxial growth on the surface of one side of the buffer layer, which is far away from the Si-based substrate, by taking trimethyl gallium as a gallium source and trimethyl aluminum as an aluminum source and ammonia as a nitrogen source to form an AlGaN undoped layer.

Further, before forming the AlGaN undoped layer, step S3 further includes: and forming a GaN strain layer on the surface of one side of the buffer layer, which is far away from the Si-based substrate, by adopting third plasma sputtering or third MOCVD epitaxial growth.

Further, the third plasma sputtering process includes: adopting a metal Ga target, and simultaneously controlling the temperature of the metal Ga target by utilizing a water cooling device, wherein the temperature control range of the water cooling device is 1-20 ℃; vacuumizing until the vacuum degree in the cavity is less than 1×10 ^- ⁵ Pa, and then filling mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of the argon to the nitrogen is 1:6-8; applying 220-1000V voltage to the metal Ga target material to perform third plasma sputtering to form a GaN strain layer; the third MOCVD epitaxial growth process comprises the following steps: and carrying out MOCVD epitaxial growth on the surface of one side of the buffer layer, which is far away from the Si-based substrate, by taking trimethyl gallium as a gallium source and ammonia as a nitrogen source to form a GaN strain layer.

Further, al _x Ga _1-x The alloy target is prepared by the following method: according to Al _x Ga _1-x The alloy target material is prepared by mixing Al and Ga, and placing metal Ga and Al powder into a crucible; heating the crucible to 660-800 ℃ under the protection of argon gas to melt metal Ga and Al powder to form Al _x Ga _1-x Alloy melt; with one end fixed with Al _x Ga _1-x Seed rod of seed crystal immersed in Al _x Ga _1-x The alloy melt is then gradually pulled up to seed rod and Al _x Ga _1-x Gradually growing around the seed crystal to form Al _x Ga _1-x An alloy target.

Further, step S4 includes: depositing SiO on the side of the top Si-based thin film layer away from the BOX buried layer ₂ A layer; for SiO ₂ Photoetching the layer to expose the top Si-based thin film layer corresponding to the N-type doped region and the P-type doped region, and then implanting phosphorus ions at the exposed top Si-based thin film layer to perform N-type doped region and boronIon implantation is carried out to form a P-type doped region; annealing the device after the N-type doped region and the P-type doped region are formed; after the annealing treatment is finished, forming a first N-type electrode and a first P-type electrode on one side of the AlGaN undoped layer far away from the buffer layer to form a first electrode with an interdigital structure; and forming a second N-type electrode on one side of the N-type doped region far away from the BOX buried layer, and forming a second P-type electrode on one side of the P-type doped region far away from the BOX buried layer, thereby forming a second electrode with an interdigital structure.

Further, the materials of the first N-type electrode, the first P-type electrode, the second N-type electrode and the second P-type electrode are all Ti/Al/Ti/Au materials, and the materials are prepared by the following preparation method: covering the upper and lower surfaces of the substrate with patterned mask layers during the annealing treatment; and sequentially forming a Ti layer, an Al layer, a Ti layer and an Au layer which are stacked at corresponding positions by adopting a sputtering mode, stripping the mask layer, and annealing for 30-60 s at the temperature of 300-500 ℃ to form a first N-type electrode, a first P-type electrode, a second N-type electrode and a second P-type electrode.

The invention provides a double-sided Si-based AlGaN detector, which comprises a Si-based substrate, and AlGaN detector structures and Si detector structures which are respectively positioned on two sides of the Si-based substrate. The AlGaN detector structure comprises a buffer layer and an AlGaN undoped layer, the buffer layer is a ZnO layer or an AlN layer, the combination effect of the AlGaN detector structure and the Si detector structure is improved through the buffer layer, the double-sided Si-based AlGaN detector is realized, and the detection wavelength range is enlarged compared with a single Si detector or a single AlGaN solar blind detector. The real-time detection of the mixed wavelength is realized, the cost is saved, and the development of Si-based integration is facilitated.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:

FIG. 1 shows a schematic structure of a double-sided Si-based AlGaN detector in accordance with one embodiment of the invention;

FIG. 2 shows a schematic top view of the dual-sided Si-based AlGaN detector of FIG. 1;

FIG. 3 shows a schematic bottom view of the dual-sided Si-based AlGaN detector of FIG. 1;

FIG. 4 is a schematic diagram showing a GaN strain layer plasma sputtering process during the fabrication of the double-sided Si-based AlGaN detector of the invention;

FIG. 5 shows Al in the process of preparing the double-sided Si-based AlGaN detector of the invention _x Ga _1-x Schematic diagram of alloy target preparation process;

FIG. 6 is a schematic diagram showing the structure of the present invention after forming an N-type doped region on the top Si-based thin film layer;

fig. 7 shows a schematic structure of the present invention after further forming P-type doped regions on the top Si-based thin film layer.

Wherein the above figures include the following reference numerals:

1. a Si-based substrate; 2. a buffer layer; 3. a GaN strain layer; 4. an AlGaN undoped layer; 5. a BOX buried layer; 6. a top Si-based thin film layer; 7. a first electrode; 8. a second electrode; 8', a first patterned photoresist; 8", a second patterned photoresist; 9. SiO (SiO) ₂ A layer; 701. a first N-type electrode; 702. a first P-type electrode; 801. a second N-type electrode; 802. a second P-type electrode; 601. an N-type doped region; 602. a P-type doped region; 603. a neutral zone;

100. a metal Ga target; 200. a composite wafer; 300. depositing a layer; 101. ga atoms; 110. a plasma cloud;

10. a crucible; 20. a reaction chamber; 30. a heating coil; 40. a rotating rod; 50. seed rods; 60. a seed holder; 11. al (Al) _x Ga _1-x Alloy melt; 201. an observation window; 501. and (5) seed crystal.

Detailed Description

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.

The invention will be further described with reference to the accompanying drawings, wherein it is to be understood that the terms "longitudinal," "radial," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," and the like are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and to simplify the description, and do not denote or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the term "plurality" as used herein generally refers to two or more, unless otherwise indicated.

As described in the background section, alGaN-based solar blind uv photodetectors are difficult to combine well with Si-based photodetectors. In order to solve the above problems, the present invention provides a double-sided Si-based AlGaN detector including a Si-based substrate and AlGaN detector structures and Si detector structures respectively located on both sides thereof.

In an exemplary embodiment, as shown in fig. 1, the above-mentioned double-sided Si-based AlGaN detector includes a Si-based substrate 1, a buffer layer 2, an AlGaN undoped layer 4, a BOX Buried layer 5 (Buried Oxide layer), a top Si-based thin film layer 6, a first electrode 7, and a second electrode 8, the Si-based substrate 1 having opposite first and second surfaces; the buffer layer 2 is arranged on the first surface of the Si-based substrate 1, and the buffer layer 2 is a ZnO layer or an AlN layer; the AlGaN undoped layer 4 is arranged on the surface of one side of the buffer layer 2 away from the Si-based substrate 1; the BOX buried layer 5 is provided on the second surface of the Si-based substrate 1; the top Si-based thin film layer 6 is arranged on the surface of one side of the BOX buried layer 5, which is far away from the Si-based substrate 1; the first electrode 7 is arranged on the side of the AlGaN undoped layer 4 away from the buffer layer 2; the second electrode 8 is arranged on the side of the top Si-based thin film layer 6 remote from the BOX buried layer 5.

The double-sided Si-based AlGaN detector provided by the invention organically combines the AlGaN detector with the Si-based detector. The AlGaN detector structure comprises a buffer layer and an AlGaN undoped layer, the buffer layer is a ZnO layer or an AlN layer, the combination effect of the AlGaN detector structure and the Si detector structure is improved through the buffer layer, the double-sided Si-based AlGaN detector is realized, and the detection wavelength range is enlarged compared with a single Si detector or a single AlGaN solar blind detector. The real-time detection of the mixed wavelength is realized, the cost is saved, and the development of Si-based integration is facilitated.

It should be noted that, compared with the AlN layer, the use of the ZnO layer as the buffer layer is more advantageous for improving the bonding stability of the two types of detectors in the double-sided Si-based AlGaN detector, because ZnO has a better lattice matching degree with the Si-based substrate, and a ZnO buffer layer with a more complete crystal structure can be grown.

In a preferred embodiment, as shown in fig. 1, the above-mentioned double-sided Si-based AlGaN detector further comprises a GaN strained layer 3, which is arranged between the buffer layer 2 and the AlGaN undoped layer 4. The addition of the GaN strained layer 3 is advantageous to further improve the overall device performance.

The above GaN strained layer and AlGaN undoped layer may be prepared by plasma sputtering or MOCVD epitaxial growth, and more preferably, both the above GaN strained layer and AlGaN undoped layer are formed by a plasma sputtering process, because: the preparation method adopts a plasma sputtering mode, and can grow at a lower temperature (500-700 ℃) under the condition of non-hydrogen (hydrogen is unstable and the safety factor of the working environment is high). On one hand, the ZnO buffer layer has better lattice matching degree with the Si substrate, and can grow high-quality crystals on the Si substrate; on the other hand, the etching damage of the ZnO buffer layer is not caused in the plasma sputtering process. A similar situation exists for AlN buffer layers. The two reasons are further beneficial to the growth of the GaN strain layer and the AlGaN undoped layer, and the double-sided Si-based AlGaN detector with better combination is finally obtained.

Meanwhile, the GaN strain layer and the AlGaN undoped layer are grown in a plasma sputtering mode, so that the preparation of a large-size wafer of 4-12 inches is facilitated, the growth speed is high, no environmental pollution is caused, the required cost is reduced, and the industrialized mass production and manufacturing are facilitated.

In one embodiment, the material of the AlGaN undoped layer 4 is Al _x Ga _1-x N, wherein 0 < x < 1; the Si-based substrate 1 and the top Si-based thin film layer 6 are simultaneously Si or simultaneously SiC.

In order to provide the AlGaN detector with better overall properties such as structural stability, in a preferred embodiment, the buffer layer 2 has a thickness of 1 to 10 μm, the GaN strained layer 3 has a thickness of 20 to 200nm, the AlGaN undoped layer 4 has a thickness of 50 to 500nm, the box buried layer 5 has a thickness of 1 to 20 μm, and the top Si-based thin film layer 6 has a thickness of 50 to 1000nm.

The structures of the first electrode 7 and the second electrode 8 may be conventional structures in the art, and more preferably an interdigital structure is adopted, and as shown in fig. 2, the first electrode 7 includes a first N-type electrode 701 and a first P-type electrode 702, and the first N-type electrode 701 and the first P-type electrode 702 form an interdigital electrode; as shown in fig. 3, the second electrode 8 includes a second N-type electrode 801 and a second P-type electrode 802, and the second N-type electrode 801 and the second P-type electrode 802 constitute an interdigital electrode.

In a preferred embodiment, as shown in fig. 1 and 3, the top Si-based thin film layer 6 has an N-type doped region 601, a P-type doped region 602, and a neutral region 603, where the N-type doped region 601 and the P-type doped region 602 form an interdigital structure and are spaced apart from each other by the neutral region 603; the second N-type electrode 801 is disposed on a side of the N-type doped region 601 away from the BOX buried layer 5, and the second P-type electrode 802 is disposed on a side of the P-type doped region 602 away from the BOX buried layer 5.

The electrode materials may be materials commonly used in the art, and in a preferred embodiment, the materials of the first N-type electrode 701, the first P-type electrode 702, the second N-type electrode 801, and the second P-type electrode 802 are all Ti/Al/Ti/Au materials. The first N-type electrode 701, the first P-type electrode 702, the second N-type electrode 801 and the second P-type electrode 802 include an Au layer, a Ti layer, an Al layer and a Ti layer, which are stacked in this order from top to bottom, wherein Ti is used to enhance metal adhesion and prevent oxidation of the surface.

According to another aspect of the present invention, there is also provided a method for manufacturing the above-mentioned double-sided Si-based Al GaN detector, comprising the steps of:

step S1, providing a composite wafer, which comprises a Si-based substrate 1, a BOX buried layer 5 and a top Si-based film layer 6 which are sequentially stacked;

Step S2, a buffer layer 2 is grown on one side surface of the Si-based substrate 1 of the composite wafer by adopting a first plasma sputtering or a first MOCVD epitaxial growth mode;

step S3, forming an AlGaN undoped layer 4 on the surface of one side of the buffer layer 2, which is far away from the Si-based substrate 1, by adopting a second plasma sputtering or a second MOCVD epitaxial growth mode;

step S4, forming a first electrode 7 on a side of the AlGaN undoped layer 4 away from the buffer layer 2; a second electrode 8 is formed on the side of the top Si-based thin film layer 6 remote from the BOX buried layer 5, thereby forming a double-sided Si-based AlGaN detector.

In the preparation method, firstly, a buffer layer 2 and an AlGaN undoped layer 4 are sequentially grown on one side of a Si-based substrate 1 of a composite wafer, then electrodes are formed on one side of a top Si-based thin film layer 6 and an AlGaN undoped layer 4 of the composite wafer, and finally the double-sided Si-based AlGaN detector is obtained. In the preparation method, the ZnO buffer layer or the AlN buffer layer is formed in advance before the AlGaN undoped layer 4, so that the combination performance of the Si detector and the AlGaN detector is improved.

It should be noted that, regarding the plasma sputtering, the beneficial effects are explained as follows:

the difference between the ZnOa axis and the gallium nitride a axis is smaller than the difference between AlN and gallium nitride, so that gallium nitride with better quality can be grown, and the gallium nitride material and the AlGaN material are lattice matched. In addition, alN is difficult to grow with good quality on Si wafers because the Si wafer lattice structure is not hexagonal, and thus it is quite difficult to grow a good quality gallium nitride epitaxial layer on Si wafers using MOCVD techniques. In addition, when the MOCVD technique is used for growth, the epitaxy temperature is 1200 ℃ and a large amount of hydrogen is introduced during the growth process. The ZnO material can be etched by hydrogen at high temperature to cause defects, and a gallium nitride film with good quality can not be grown on the ZnO material. The AlN material also has the above-described problems.

Plasma sputtering, in which all substances are ionized at high temperature, is called plasma (plasma) or ion gas (ionized gas). Basically, plasma is an aggregate of ion gases, and more hundred molecules, ninety-five, are in a plasma state in space. The plasma is composed of ions, electrons, and neutral particles, and is also referred to as the "fourth state". Electrons in the gas are promoted to obtain energy by the energy of an external electric field and are accelerated to collide with uncharged neutral particles, ions and accelerated electrons with other energy are generated after the uncharged neutral particles are impacted by the accelerated electrons, and the released electrons are accelerated to collide with other neutral particles by the electric field. The process is repeated to generate a breakdown effect (gas break down) to form a plasma state. Plasma sputtering mainly uses inert gas atoms to collide with electrons moving at high speed, positive ions collide with the surface of a cathode or a target by the action of an electric field and a magnetic field, the target atoms are impacted and deposited on a substrate, and taking Ar gas as an example, the empirical formula of plasma collision is as follows:

Ar+e ^- →Ar ⁺ +e ^- (slow)+e ^- (slow) (1)

and thereby generate a large amount of plasma to strike the target for deposition on the substrate.

Sputtering is basically a glow discharge method for generating plasma, which can be classified into direct current plasma and alternating current radio frequency plasma. When sputtering a film with a dc plasma, there is a higher sputter yield, i.e. a higher deposition rate than with an ac rf, but the material of the electrode plate (sputtering target) must be conductive or otherwise there is a charge accumulation effect. There is no such limitation in using an ac rf plasma, but the deposition rate is slow.

For the GaN strained layer and AlGaN undoped layer described below, it is more preferable to prepare them by plasma sputtering than by MOCVD growth: plasma sputtering can be performed at a relatively low temperature (500-700 ℃) under non-hydrogen conditions (hydrogen is unstable and the safety factor of the working environment is high). On one hand, the ZnO buffer layer has better lattice matching degree with the Si substrate, and can grow high-quality crystals on the Si substrate; on the other hand, the etching damage of the ZnO buffer layer is not caused in the plasma sputtering process. A similar situation exists for AlN buffer layers. The reasons for the above two aspects are further beneficial to the GaN strain layer and AlG _a And growing an N undoped layer, and finally obtaining the double-sided Si-based AlGaN detector with better combination. At the same time, the method comprises the steps of, The GaN strain layer and the AlGaN undoped layer are grown by adopting a plasma sputtering mode, which is beneficial to preparing large-size wafers of 4-12 inches, has high growth speed, does not pollute environment, reduces the required cost and is beneficial to industrialized mass production and manufacture.

In the actual preparation process, when the buffer layer 2 is a ZnO layer, the buffer layer 2 is formed by a first plasma sputtering method, which includes: providing a plasma sputtering apparatus; placing a ZnO target in a cathode shielding cover, placing a composite wafer on a base table and enabling the first surface of the Si-based substrate 1 to face upwards; closing the chamber of the plasma sputtering apparatus, and then vacuumizing until the vacuum degree in the chamber is less than 1×10- ⁵ Pa, and then filling argon gas to make the air pressure reach 1-10 MPa; a voltage of 380 to 1000V is applied to the ZnO target to perform a first plasma sputtering to form a buffer layer 2. In order to enable the ZnO layer to grow more completely and uniformly, in a specific operation process, a ZnO target can be placed in a cathode shielding cover, a composite wafer is placed on a base station, and after the placement is finished, the chamber is closed. The chamber is pumped into a vacuum state by a molecular pump, and the vacuum degree is less than 1 multiplied by 10 ^-5 Pa. And after the air pressure in the cavity reaches the required condition, filling argon into the cavity to enable the air pressure in the cavity to reach between 1 and 10 MPa. Connecting the upper and lower targets in the chamber with a power supply to form an electric field. Natural electrons existing between the upper electric field and the lower electric field can have certain kinetic energy under the action of the electric field and can strike Ar atoms existing in the cavity. The Ar atoms are ionized after being impacted by electrons, become argon ions and release one electron. The argon ions are driven by the electric field to move toward the cathode. Impacting the target on the cathode to impact zinc atoms and oxygen atoms on the target out of the original positions. A plasma is formed and then deposited on the underlying Si substrate. The applied voltage is 380-1000V, and the thickness of the deposition growth is 1-10 mu m.

When the buffer layer 2 is an AlN layer, the buffer layer 2 is formed by a first MOCVD epitaxial growth, which includes: heating the composite wafer to 1200-1300 ℃, and then placing the composite wafer in a hydrogen environment for 10-60 min; cooling the composite wafer to 700-900 ℃, and then growing an AlN nucleation layer on the first surface of the Si-based substrate 1 by taking trimethylaluminum as an aluminum source and ammonia as a nitrogen source; the composite wafer is continuously heated to 1180-1250 ℃ to perform recrystallization treatment on the AlN nucleation layer to form a buffer layer 2.

In a preferred embodiment, the second plasma sputtering process comprises: by Al _x Ga _1-x An alloy target, wherein x is more than 0 and less than 1; vacuumizing until the vacuum degree in the cavity is less than 1×10 ^-5 Pa, and then filling mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of the argon to the nitrogen is 1:7-8; to Al _x Ga _1-x Applying 220-1000V voltage to the alloy target material to perform second plasma sputtering so as to form an AlGaN undoped layer 4; the second MOCVD epitaxial growth process comprises the following steps: and carrying out MOCVD epitaxial growth on the surface of one side of the buffer layer 2, which is far away from the Si-based substrate 1, by taking trimethyl gallium as a gallium source and trimethyl aluminum as an aluminum source and ammonia as a nitrogen source to form the AlGaN undoped layer 4.

In a preferred embodiment, before forming the AlGaN undoped layer 4, step S3 further includes: a GaN strained layer 3 is formed on the surface of the buffer layer 2 on the side remote from the Si-based substrate 1 by a third plasma sputtering or a third MOCVD epitaxial growth.

The growth process of the GaN strained layer 3 is similar to the buffer layer formation process described above, and in a preferred embodiment, the third plasma sputtering process includes: adopting a metal Ga target, and simultaneously controlling the temperature of the metal Ga target by utilizing a water cooling device, wherein the temperature control range of the water cooling device is 1-20 ℃; vacuumizing until the vacuum degree in the cavity is less than 1×10 ^-5 Pa, and then filling mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of the argon to the nitrogen is 1:6-8; and applying 220-1000V voltage to the metal Ga target material to perform third plasma sputtering to form the GaN strain layer 3. Specifically, in order to make the sputtering process more stable, after the ZnO layer is grown, the target in the cathode shielding can be replaced by a metal Ga target. Since the melting point of the metal Ga target is only 29 ℃, a water cooling device needs to be added at the rear of the target. The temperature of the water cooling device is kept between 1 and 20 ℃ to ensure solidification of the metal Ga during sputtering. And closing the cavity after the metal Ga target is placed. The chamber is pumped to a vacuum state by a molecular pump, and the vacuum degree is less than 1 multiplied by 10 ^-5 Pa. Then, a mixed gas of argon (purity: 99.999%) and nitrogen (purity: 99.999%) was introduced into the chamber at a ratio of 1:6. Connecting the upper and lower targets in the chamber with a power supply to form an electric field. As shown in fig. 4, natural electrons e exist in the electric field between the metal Ga target 100 and the composite wafer 200 ^- Electron e ^- The electric field drives argon (Ar) and nitrogen (N) in the impinging chamber ₂ ) So that argon is ionized to form argon ions (Ar ⁺ ) Ionization of nitrogen gas to form nitrogen ions (N ⁺ ) Nitrogen atom (N) and release electron e ^- . The generated argon ions and nitrogen ions impact the metal Ga target 100 under the driving of the electric field, so that the metal Ga target 100 is separated from the Ga atoms 101. A highly concentrated plasma cloud 110 is formed within the chamber, including nitrogen ions, argon ions, nitrogen atoms, and Ga atoms. As the concentration increases, nitrogen atoms and Ga atoms combine to form GaN deposited on the buffer layer, forming the deposition layer 300. The applied voltage is 220V-1000V, and the thickness of the deposited film is 20 nm-200 nm.

Preferably, the third MOCVD epitaxial growth process includes: and carrying out MOCVD epitaxial growth on the surface of one side of the buffer layer 2, which is far away from the Si-based substrate 1, by taking trimethyl gallium as a gallium source and ammonia as a nitrogen source to form a GaN strain layer 3.

In a preferred embodiment, the second plasma sputtering process comprises: by Al _x Ga _1-x An alloy target, wherein x is more than 0 and less than 1; vacuumizing until the vacuum degree in the cavity is less than 1×10 ^-5 Pa, and then filling mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of the argon to the nitrogen is 1:7-8; to Al _x Ga _1-x The alloy target is subjected to second plasma sputtering by applying a voltage of 220-1000V to form an AlGaN undoped layer 4. In order to make the growth of the layer more stable and complete, the target material in the cathode shielding cover can be replaced by Al after the growth of the GaN strain layer 3 is completed _x Ga _1-x An alloy target. Al (Al) _x Ga _1-x After the alloy target is placed, the chamber is closed, and the gas in the chamber is pumped by a molecular pump, so that the vacuum degree in the chamber is less than 1 multiplied by 10 ^-5 Pa. Then, a mixed gas of argon (purity: 99.999%) and nitrogen (purity: 99.999%) is introduced into the chamber in a ratio of1:7. Connecting the upper and lower targets in the chamber with a power supply to form an electric field. Natural electrons exist in the electric field between the upper target and the lower target, and the electrons are driven by the electric field to strike argon and nitrogen in the cavity, so that argon ions are formed by ionization, nitrogen ions are formed by ionization of the nitrogen, and electrons are released. The generated argon ions and nitrogen ions impact Al under the drive of an electric field _x Ga _1-x Alloy target material, making Al _x Ga _1-x The alloy target is separated to form Al and Ga atoms. A highly concentrated plasma cloud is formed within the chamber, including nitrogen ions, argon ions, nitrogen atoms, al atoms, and Ga atoms. As the concentration increases, the nitrogen atoms, al atoms and Ga atoms combine to form Al _x Ga _1-x N is deposited on the gallium nitride strained layer. The applied voltage is 220V-1000V, and the thickness of the deposited film is 50 nm-500 nm.

The second MOCVD epitaxial growth process comprises the following steps: and carrying out MOCVD epitaxial growth on the surface of one side of the buffer layer 2, which is far away from the Si-based substrate 1, by taking trimethylgallium as a gallium source and trimethylaluminum as an aluminum source, and taking ammonia gas as a nitrogen source to form the AlGaN undoped layer 4.

The above Al of the present invention _x Ga _1-x The alloy target material can be prepared by the following method: according to Al _x Ga _1-x The alloy target material is prepared by mixing Al and Ga, and placing metal Ga and Al powder into a crucible; heating the crucible to 660-800 ℃ under the protection of argon gas to melt metal Ga and Al powder to form Al _x Ga _1-x Alloy melt; with one end fixed with Al _x Ga _1-x Seed rod of seed crystal immersed in Al _x Ga _1-x The alloy melt is then gradually pulled up to seed rod and Al _x Ga _1-x Gradually growing around the seed crystal to form Al _x Ga _1-x An alloy target.

Specifically, as shown in fig. 5, first, al powder having a purity of 99.999% and metal Ga are prepared and placed in the crucible 10 in this order, metal Ga small pieces are placed at the bottom, and then Al powder is scattered on the metal Ga small pieces, which leak into gaps of the Ga small pieces, the melting point of the Al powder is 660 ℃, and the melting point of the Ga is 29.8 ℃. The ratio of the Al powder to Ga is x: (1-x), wherein the value of x is more than 0 and less than 1. After the material is placed, the reverse is closed The reaction chamber 20 is evacuated to a vacuum level of 1X 10 ^-5 Pa or below. Then, protective gas argon is filled into the reaction chamber 20, so that the pressure in the reaction chamber 20 reaches 1-5 MPa. The heating coil 30 around the crucible 10 is connected to a power source, and the crucible 10 is heated to raise the temperature in the crucible 10 to 660 ℃ or higher. When the melting of the Al powder and Ga blocks in the crucible 10 is seen through the observation window 201 of the reaction chamber 20, the rotary rod 40 at the bottom of the crucible 10 is rotated so that the Al in the crucible 10 _x Ga _1-x The alloy melt 11 is sufficiently fused. The seed rod 50 is fixed with Al _x Ga _1-x Alloy small block (seed crystal 501), the seed holder 60 controls the seed rod to slowly pull Al _x Ga _1-x Alloy small blocks, affected by temperature gradient, al _x Ga _1-x The alloy small blocks become thick slowly to form cylindrical Al _x Ga _1-x And (3) alloy. After being pulled to a certain length, the heating of the crucible 10 by the coil is stopped. Naturally cooling the temperature in the reaction chamber 20 to room temperature, and taking out Al _x Ga _1-x Alloy column to remain as Al _x Ga _1-x Alloy targets.

In a preferred embodiment, step S4 comprises: on the side of the top Si-based thin film layer 6 remote from the BOX buried layer 5 SiO is deposited ₂ Layer 9; for SiO ₂ Photoetching the layer to expose the top Si-based thin film layer 6 corresponding to the N-type doped region 601 and the P-type doped region 602 to be formed, and then performing phosphorus ion implantation at the exposed top Si-based thin film layer 6 to perform N-type doped region 601 and boron ion implantation to form P-type doped region 602; annealing the device after the N-type doped region 601 and the P-type doped region 602 are formed; after the annealing treatment is finished, forming a first N-type electrode 701 and a first P-type electrode 702 on one side of the AlGaN undoped layer 4 far from the buffer layer 2 to form a first electrode 7 with an interdigital structure; a second N-type electrode 801 is formed on a side of the N-type doped region 601 away from the BOX buried layer 5, and a second P-type electrode 802 is formed on a side of the P-type doped region 602 away from the BOX buried layer 5, thereby forming a second electrode 8 having an interdigital structure. Deposition of SiO ₂ Layer 9 facilitates protection of the non-implanted region (neutral region 603) from high energy ions during subsequent ion implantationThe surface of the Si-based film is damaged by the seeds, and surface leakage is increased. Specific SiO ₂ The thickness of layer 9 is preferably 10 to 20nm. The annealing treatment is favorable for activating ions, and dislocation can be further eliminated, so that implantation damage is repaired. Specifically, rapid annealing may be performed at 1000 ℃. The above process of performing phosphorus ion implantation at the exposed top Si-based thin film layer 6 to perform N-type doping region 601 and performing boron ion implantation to form P-type doping region 602 may be performed by conventional means in the art, for example, as shown in fig. 6, covering the top Si-based thin film layer 6 except the N-type doping region 601 with the first patterned photoresist 8', and then performing phosphorus ion implantation to form N-type doping region 601; as shown in fig. 7, the photoresist is removed, and the second patterned photoresist 8″ is used to cover the top Si-based thin film layer 6 and the N-doped region 601 outside the P-doped region 602, and then the boron ion implantation is performed to form the P-doped region 602, which will not be described herein.

In a preferred embodiment, the materials of the first N-type electrode 701, the first P-type electrode 702, the second N-type electrode 801 and the second P-type electrode 802 are all Ti/Al/Ti/Au materials, which are prepared by the following preparation methods: covering the upper and lower surfaces of the substrate with patterned mask layers during the annealing treatment; a Ti layer, an Al layer, a Ti layer and an Au layer which are stacked are sequentially formed at corresponding positions by adopting a sputtering mode, then the mask layer is peeled off, and the annealing is carried out for 30-60 s at the temperature of 300-500 ℃ to form a first N-type electrode 701, a first P-type electrode 702, a second N-type electrode 801 and a second P-type electrode 802.Ti serves to enhance metal adhesion and prevent oxidation of the surface.

In the first, second and third plasma sputtering processes, the power source may be a dc power source or a radio frequency power source, the frequency of the radio frequency power source is 5-20 MHz, and the voltage adjustable range is 0-1000V.

The present application is described in further detail below in conjunction with specific embodiments, which should not be construed as limiting the scope of the claims.

Example 1

Step 1: preparation of materials. First, a block of S-on-insulator is providedI (SOI) substrate, top Si film is neutral layer with thickness of 200nm, middle BOX buried layer with thickness of 2 μm, bottom Si substrate is neutral layer with conventional thickness. Next, znO and metal Ga targets with 99.999% purity were prepared for stay-on. Then, preparing an AlGa alloy target. Firstly, al powder with the purity of 99.999% and metal Ga are prepared and sequentially placed in a crucible, metal Ga small blocks are placed at the bottom, then the Al powder is scattered on the metal Ga small blocks, the Al powder leaks into gaps of the Ga small blocks, the melting point of the Al powder is 660 ℃, and the melting point of Ga is 29.8 ℃. The ratio of the Al powder to Ga is 4:6. after the material is placed, the reaction chamber is closed, the reaction chamber is vacuumized, and the vacuum degree is reduced to 1 multiplied by 10 ^- ⁵ Pa. Then, protective gas argon is filled into the reaction chamber to enable the pressure in the reaction chamber to reach 1MPa. The heating coil around the crucible is connected with a power supply to heat the crucible, so that the temperature in the crucible is raised to 700 ℃. When the Al powder and Ga blocks in the crucible are seen to be melted through the observation window of the reaction chamber, the rotary rod at the bottom of the crucible is rotated, so that the Al in the crucible _0.4 Ga _0.6 The alloy melt is fully fused. The seed rod is fixed with AlGa alloy small blocks, the seed crystal holder controls the seed rod to slowly lift the AlGa alloy small blocks, and the AlGa alloy small blocks slowly become thicker under the influence of temperature gradient to form cylindrical Al _0.4 Ga _0.6 And (3) alloy. When the crucible is pulled to a certain length, the heating of the crucible by the coil is stopped. Naturally cooling the temperature in the reaction chamber to room temperature, taking out Al _0.4 Ga _0.6 Alloy column to remain as Al _0.4 Ga _0.6 Alloy targets.

Step 2: and (3) preparation of a buffer layer. And growing a buffer layer above the SOI composite wafer Si substrate, wherein the buffer layer is made of ZnO material. The ZnO target was placed in a cathode shield. The SOI substrate is placed on the base station, and after the placement is completed, the chamber is closed. The chamber is pumped into a vacuum state by a molecular pump, and the vacuum degree is 5 multiplied by 10 ^-6 Pa. And after the air pressure in the cavity reaches the required condition, filling argon into the cavity to enable the air pressure in the cavity to reach between 2 MPa. Connecting the upper and lower targets in the chamber with a power supply to form an electric field. One side of the target material is connected with the negative electrode of the power supply, and the natural exists between the upper electric field and the lower electric field Electrons have a certain kinetic energy under the action of an electric field and strike Ar atoms existing in the cavity. The Ar atoms are ionized after being impacted by electrons, become argon ions and release one electron. The argon ions are driven by the electric field to move toward the cathode. Impacting the target on the cathode to impact zinc atoms and oxygen atoms on the target out of the original positions. A plasma is formed and then deposited on the underlying Si substrate. The applied voltage was 1000V and the thickness of the deposited growth was 2 μm.

Step 3: and (3) preparing a gallium nitride strain layer. And after the ZnO grows, changing the target in the cathode shielding cover into a metal Ga target. Since the melting point of the metal Ga target is only 29 ℃, a water cooling device needs to be added at the rear of the target. The temperature of the water cooling device was kept at 5 ℃ to ensure solidification of the metal Ga during sputtering. And closing the cavity after the metal Ga target is placed. The chamber is pumped to a vacuum state by a molecular pump, and the vacuum degree is less than 1 multiplied by 10 ^-5 Pa. Then, a mixed gas of argon (purity: 99.999%) and nitrogen (purity: 99.999%) was introduced into the chamber at a ratio of 1:6. Connecting the upper and lower targets in the chamber with a power supply to form an electric field. Natural electrons exist in the electric field between the upper target and the lower target, and the electrons are driven by the electric field to strike argon and nitrogen in the cavity, so that argon ions are formed by ionization, nitrogen ions are formed by ionization of the nitrogen, and electrons are released. The generated argon ions and nitrogen ions impact the metal Ga target under the driving of an electric field, so that the Ga target is separated to form Ga atoms. A highly concentrated plasma cloud is formed within the chamber, including nitrogen ions, argon ions, nitrogen atoms, and Ga atoms. As the concentration increases, nitrogen atoms and Ga atoms combine to form GaN deposited on the ZnO buffer layer. The applied voltage was 880V and the deposited thickness was 20nm;

Step 4: al (Al) _0.4 Ga _0.6 And (3) preparing an N device layer. After the GaN strain layer grows, the target material in the cathode shielding cover is replaced by Al _0.4 Ga _0.6 An alloy target. Al (Al) _0.4 Ga _0.6 After the alloy target is placed, the chamber is closed, and the gas in the chamber is pumped by a molecular pump to ensure that the vacuum degree in the chamber is 1 multiplied by 10 ^-5 Pa. Then leading into the cavityArgon (99.999% purity) and nitrogen (99.999% purity) were introduced at a ratio of 1:7. Connecting the upper and lower targets in the chamber with a power supply to form an electric field. Natural electrons exist in the electric field between the upper target and the lower target, and the electrons are driven by the electric field to strike argon and nitrogen in the cavity, so that argon ions are formed by ionization, nitrogen ions are formed by ionization of the nitrogen, and electrons are released. The generated argon ions and nitrogen ions impact Al under the drive of an electric field _0.4 Ga _0.6 Alloy target material, making Al _0.4 Ga _0.6 The alloy target is separated to form Al and Ga atoms. A highly concentrated plasma cloud is formed within the chamber, including nitrogen ions, argon ions, nitrogen atoms, al atoms, and Ga atoms. As the concentration increases, the nitrogen atoms, al atoms and Ga atoms combine to form Al _0.4 Ga _0.6 N is deposited on the gallium nitride strained layer. The applied voltage is 1000V, and the thickness of the deposition is 300nm;

Step 5: preparation of Si detector. When Al is _0.4 Ga _0.6 And after the preparation of the N device layer is finished, taking out the substrate on the base station. And performing device preparation on the top Si film in the SOI substrate at the other side of the substrate. First, a layer of SiO of 20nm is deposited on the top Si film ₂ A layer of SiO ₂ The layer protects the subsequent ion implantation, prevents high-energy ions from damaging the Si surface and increases surface leakage;

step 6: and (5) ion implantation. M2 reverse photolithography, phosphorus ion implantation forms N-type doping. M3 reverse photolithography, boron ion implantation forms P-type doping.

Step 7: and (5) quick annealing. Rapidly annealing at 1000 ℃ to activate ions, and further eliminating dislocation and repairing implantation damage;

step 8: sputtering metal on the upper and lower surfaces, and stripping to form alloy. The materials of the metal electrode are Au/Ti/Al/Ti from top to bottom. Wherein Ti is used for enhancing metal adhesion and preventing surface oxidation. After stripping, the alloy was formed by annealing for 30s at 450 ℃.

Example 2:

the main difference from example 1 is that the GaN strained layer is removed and the AlGaN device layer is grown directly on the ZnO buffer layer.

Step 1: preparation of materials. First, a Silicon On Insulator (SOI) substrate was provided, the top Si film was a neutral layer, its thickness was 250nm, the thickness of the intermediate BOX buried layer was 2 μm, the bottom Si substrate was a neutral layer, and it was a conventional thickness. Next, znO and metal Ga targets with 99.999% purity were prepared for stay-on. Then, preparing an AlGa alloy target. Firstly, al powder with the purity of 99.999% and metal Ga are prepared and sequentially placed in a crucible, metal Ga small blocks are placed at the bottom, then the Al powder is scattered on the metal Ga small blocks, the Al powder leaks into gaps of the Ga small blocks, the melting point of the Al powder is 660 ℃, and the melting point of Ga is 29.8 ℃. The ratio of the Al powder to Ga is 3:7. after the material is placed, the reaction chamber is closed, the reaction chamber is vacuumized, and the vacuum degree is reduced to 5 multiplied by 10 ^- ⁶ Pa. Then, protective gas argon is filled into the reaction chamber to enable the pressure in the reaction chamber to reach 1MPa. The heating coil around the crucible is connected with a power supply to heat the crucible, so that the temperature in the crucible is raised to 700 ℃. When the Al powder and Ga blocks in the crucible are seen to be melted through the observation window of the reaction chamber, the rotary rod at the bottom of the crucible is rotated, so that the Al in the crucible _0.3 Ga _0.7 The alloy melt is fully fused. The seed rod is fixed with AlGa alloy small blocks, the seed crystal holder controls the seed rod to slowly lift the AlGa alloy small blocks, and the AlGa alloy small blocks slowly become thicker under the influence of temperature gradient to form cylindrical Al _0.3 Ga _0.7 And (3) alloy. When the crucible is pulled to a certain length, the heating of the crucible by the coil is stopped. Naturally cooling the temperature in the reaction chamber to room temperature, taking out Al _0.3 Ga _0.7 Alloy column to remain as Al _0.3 Ga _0.7 Alloy targets.

Step 2: and (3) preparation of a buffer layer. And growing a buffer layer above the SOI composite wafer Si substrate, wherein the buffer layer is made of ZnO material. The ZnO target was placed in a cathode shield. The SOI substrate is placed on the base station, and after the placement is completed, the chamber is closed. The chamber is pumped into a vacuum state by a molecular pump, and the vacuum degree is 5 multiplied by 10 ^-6 Pa. And after the air pressure in the cavity reaches the required condition, filling argon into the cavity to enable the air pressure in the cavity to reach between 2 MPa. The chamber is provided with The upper and lower targets in the chamber are connected with a power supply to form an electric field. One side of the target material is connected with a negative electrode of a power supply, and natural electrons existing between an upper electric field and a lower electric field can have certain kinetic energy under the action of the electric field to strike Ar atoms existing in the cavity. The Ar atoms are ionized after being impacted by electrons, become argon ions and release one electron. The argon ions are driven by the electric field to move toward the cathode. Impacting the target on the cathode to impact zinc atoms and oxygen atoms on the target out of the original positions. A plasma is formed and then deposited on the underlying Si substrate. The applied voltage was 1000V and the thickness of the deposited growth was 2 μm.

Step 3: al (Al) _0.3 Ga _0.7 And (3) preparing a device layer. After the GaN strain layer grows, the target material in the cathode shielding cover is replaced by Al _0.3 Ga _0.7 An alloy target. Al (Al) _0.3 Ga _0.7 After the alloy target is placed, the chamber is closed, and the gas in the chamber is pumped by a molecular pump to ensure that the vacuum degree in the chamber is 1 multiplied by 10 ^-5 Pa. Then, a mixed gas of argon (purity: 99.999%) and nitrogen (purity: 99.999%) was introduced into the chamber at a ratio of 1:7. Connecting the upper and lower targets in the chamber with a power supply to form an electric field. Natural electrons exist in the electric field between the upper target and the lower target, and the electrons are driven by the electric field to strike argon and nitrogen in the cavity, so that argon ions are formed by ionization, nitrogen ions are formed by ionization of the nitrogen, and electrons are released. The generated argon ions and nitrogen ions impact Al under the drive of an electric field _0.3 Ga _0.7 Alloy target material, making Al _0.3 Ga _0.7 The alloy target is separated to form Al and Ga atoms. A highly concentrated plasma cloud is formed within the chamber, including nitrogen ions, argon ions, nitrogen atoms, al atoms, and Ga atoms. As the concentration increases, the nitrogen atoms, al atoms and Ga atoms combine to form Al _0.3 Ga _0.7 N is deposited on the gallium nitride strained layer. The applied voltage is 1000V, and the thickness of the deposition is 300nm;

step 4: preparation of Si detector. When Al is _0.3 Ga _0.7 And after the preparation of the N device layer is finished, taking out the substrate on the base station. And performing device preparation on the top Si film in the SOI substrate at the other side of the substrate.First, a layer of SiO of 20nm is deposited on the top Si film ₂ A layer of SiO ₂ The layer protects the subsequent ion implantation, prevents high-energy ions from damaging the Si surface and increases surface leakage;

step 5: and (5) ion implantation. M2 reverse photolithography, phosphorus ion implantation forms N-type doping. M3 reverse photolithography, boron ion implantation forms P-type doping.

Step 6: and (5) quick annealing. Rapidly annealing at 1000 ℃ to activate ions, and further eliminating dislocation and repairing implantation damage;

step 7: sputtering metal on the upper and lower surfaces, and stripping to form alloy. The materials of the metal electrode are Au/Ti/Al/Ti from top to bottom. Wherein Ti is used for enhancing metal adhesion and preventing surface oxidation. After stripping, the alloy was formed by annealing for 30s at 450 ℃.

Example 3

The main difference between this embodiment and embodiment 1 is that this embodiment mainly adopts the MOCVD epitaxial growth method to prepare the double-sided Si-based AlGaN detector. The intermediate buffer layer is made of AlN material instead of ZnO material.

Step 1: preparation of materials. First, a Silicon On Insulator (SOI) substrate was provided, the top Si film was a neutral layer, its thickness was 300nm, the thickness of the intermediate BOX buried layer was 5 μm, the bottom Si substrate was a neutral layer, and it was a conventional thickness.

Step 2: preparation of an AlN buffer layer. And growing a buffer layer above the SOI composite wafer Si substrate, wherein the buffer layer is made of AlN material. The nitrogen source used for epitaxial growth was ammonia gas with a purity of 99.999% and the aluminum source was trimethylaluminum (TMAl, purity grade hypoxia). The substrate is heated to 1200 ℃ before epitaxial growth and is treated for 10min in a hydrogen environment. The high temperature treatment has two effects, namely, removal of residual contamination on the surface of the substrate and desorption of oxygen atoms constituting the surface of the crystal lattice. Then, the substrate temperature was lowered to about 700 ℃ to start growing a low temperature AlN nucleation layer of about 200nm, and then the AlN nucleation layer was recrystallized at a high temperature by heating the substrate to 1180 ℃. The flow rate of the ammonia gas is 1000sccm, and the carrier gas adopts the mixture of hydrogen and nitrogen The total flow of hydrogen is 3450sccm, the total flow of nitrogen is 1050sccm, the flow of TMAL is 4.5 mu mol/min, and the gas pressure in the reaction chamber is 2X 10 ³ Pa；

Step 3: and (3) preparing a gallium nitride strain layer. After the AlN buffer layer is grown, a gallium nitride strain layer with the thickness of about 50nm is grown by MOCVD. The flow rate of ammonia gas is 1000sccm, the carrier gas is mixed gas of hydrogen and nitrogen, wherein the total flow rate of hydrogen is 3450sccm, the total flow rate of nitrogen is 1050s ccm, the flow rate of TMGa is 13.3 mu mol/min, and the air pressure in the reaction chamber is 2 multiplied by 10 ³ Pa；

Step 4: al (Al) _0.2 Ga _0.8 And (3) preparing an N device layer. After the GaN strain layer is grown, the MOCVD is utilized to grow Al with the thickness of about 300nm _0.2 Ga _0.8 An N device layer. The flow rate of ammonia gas is 1000sccm, the carrier gas is mixed gas of hydrogen and nitrogen, wherein the total flow rate of hydrogen is 3450sccm, the total flow rate of nitrogen is 1050sccm, the flow rate of TMAL is 4.5 mu mol/min, the flow rate of TMGa is 13.3 mu mol/min, and the air pressure in the reaction chamber is 2.5X10 ³ Pa；

Step 5: preparation of Si detector. When Al is _0.2 Ga _0.8 And after the preparation of the N device layer is finished, taking out the substrate on the base station. And performing device preparation on the top Si film in the SOI substrate at the other side of the substrate. First, a layer of SiO of 20nm is deposited on the top Si film ₂ A layer of SiO ₂ The layer protects the subsequent ion implantation, prevents high-energy ions from damaging the Si surface and increases surface leakage;

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A double-sided Si-based AlGaN detector, comprising:

A Si-based substrate (1) having opposite first and second surfaces;

a buffer layer (2) disposed on the first surface of the Si-based substrate (1), wherein the buffer layer (2) is a ZnO layer or an AlN layer;

an AlGaN undoped layer (4) provided on a surface of the buffer layer (2) on a side away from the Si-based substrate (1);

a BOX buried layer (5) provided on the second surface of the Si-based substrate (1);

a top Si-based thin film layer (6) arranged on the surface of one side of the BOX buried layer (5) far away from the Si-based substrate (1);

a first electrode (7) arranged on the side of the AlGaN undoped layer (4) away from the buffer layer (2); and

and a second electrode (8) arranged on the side of the top Si-based thin film layer (6) away from the BOX buried layer (5).

2. The dual sided Si-based AlGaN detector according to claim 1, further comprising: and a GaN strain layer (3) disposed between the buffer layer (2) and the AlGaN undoped layer (4).

3. The double-sided Si-based AlGaN detector according to claim 1, wherein the material of said AlGaN undoped layer (4) is Al _x Ga _1-x N, wherein 0 < x < 1; the Si-based substrate (1) and the top Si-based thin film layer (6) are simultaneously Si or simultaneously SiC.

4. The double-sided Si-based AlGaN detector according to claim 2, wherein said buffer layer (2) has a thickness of 1 to 10 μm, said GaN strained layer (3) has a thickness of 20 to 200nm, said AlGaN undoped layer (4) has a thickness of 50 to 500nm, said BOX buried layer (5) has a thickness of 1 to 20 μm, and said top Si-based thin film layer (6) has a thickness of 50 to 1000nm.

5. The dual-sided Si-based AlGaN detector according to any one of claims 1 to 4, wherein said first electrode (7) comprises a first N-type electrode (701) and a first P-type electrode (702), and said first N-type electrode (701) and first P-type electrode (702) constitute an interdigital electrode; the second electrode (8) comprises a second N-type electrode (801) and a second P-type electrode (802), and the second N-type electrode (801) and the second P-type electrode (802) form an interdigital electrode.

6. The double-sided Si-based AlGaN detector according to claim 5, wherein said top Si-based thin film layer (6) has an N-type doped region (601), a P-type doped region (602) and a neutral region (603), said N-type doped region (601) and P-type doped region (602) forming an interdigital structure and being spaced apart by said neutral region (603); the second N-type electrode (801) is arranged on one side, far away from the BOX buried layer (5), of the N-type doped region (601), and the second P-type electrode (802) is arranged on one side, far away from the BOX buried layer (5), of the P-type doped region (602).

7. The dual sided Si-based AlGaN detector according to claim 5, wherein said first N-type electrode (701), first P-type electrode (702), said second N-type electrode (801) and said second P-type electrode (802) are all of Ti/Al/Ti/Au material.

8. A method of manufacturing the double-sided Si-based AlGaN detector according to any one of claims 1 to 7, comprising the steps of:

step S1, providing a composite wafer, which comprises a Si-based substrate (1), a BOX buried layer (5) and a top Si-based film layer (6) which are sequentially stacked;

step S2, a buffer layer (2) is grown on the first surface of the Si-based substrate (1) of the composite wafer by adopting a first plasma sputtering or a first MOCVD epitaxial growth mode;

s3, forming an AlGaN undoped layer (4) on the surface of one side, far away from the Si-based substrate (1), of the buffer layer (2) by adopting a second plasma sputtering or second MOCVD epitaxial growth mode;

step S4, forming a first electrode (7) on one side of the AlGaN undoped layer (4) far away from the buffer layer (2); and forming a second electrode (8) on one side of the top Si-based film layer (6) far away from the BOX buried layer (5), thereby forming the double-sided Si-based AlGaN detector.

9. The method for manufacturing a double-sided Si-based AlGaN detector according to claim 8, wherein,

when the buffer layer (2) is a ZnO layer, the buffer layer (2) is formed by the first plasma sputtering method, which comprises:

providing a plasma sputtering apparatus;

placing the ZnO target in a cathode shielding cover, placing the composite wafer on a base station and enabling the first surface of the Si-based substrate (1) to face upwards;

closing the chamber of the plasma sputtering equipment, and vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10 ^-5 Pa, and then filling argon gas to make the air pressure reach 1-10 MPa;

applying 380-1000V voltage to the ZnO target material to perform the first plasma sputtering so as to form the buffer layer (2);

when the buffer layer (2) is an AlN layer, the buffer layer (2) is formed by using the first MOCVD epitaxial growth, which includes:

heating the composite wafer to 1200-1300 ℃, and then placing the composite wafer in a hydrogen environment for 10-60 min;

cooling the composite wafer to 700-900 ℃, and then growing an AlN nucleation layer on the first surface of the Si-based substrate (1) by taking trimethylaluminum as an aluminum source and ammonia as a nitrogen source;

and continuously heating the composite wafer to 1180-1250 ℃ to perform recrystallization treatment on the AlN nucleation layer so as to form the buffer layer (2).

10. The method for manufacturing a double-sided Si-based AlGaN detector according to claim 8, wherein,

the second plasma sputtering process comprises: by Al _x Ga _1-x An alloy target, wherein x is more than 0 and less than 1; vacuumizing until the vacuum degree in the cavity is less than 1×10 ^-5 Pa, and then filling mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of the argon to the nitrogen is 1:7-8; to the Al _x Ga _1-x Applying 220-1000V voltage to the alloy target material to perform the second plasma sputtering so as to form the AlGaN undoped layer (4);

the second MOCVD epitaxial growth process comprises the following steps: and carrying out MOCVD epitaxial growth on the surface of one side of the buffer layer (2) away from the Si-based substrate (1) by taking trimethyl gallium as a gallium source and trimethyl aluminum as an aluminum source to form the AlGaN undoped layer (4).

11. The method of manufacturing a double-sided Si-based AlGaN detector according to claim 10, wherein said step S3 further comprises, before forming said AlGaN undoped layer (4): firstly, a GaN strain layer (3) is formed on the surface of one side of the buffer layer (2) far away from the Si-based substrate (1) by adopting third plasma sputtering or third MOCVD epitaxial growth.

12. The method for manufacturing a double-sided Si-based AlGaN detector according to claim 11, wherein,

The third plasma sputtering process comprises: adopting a metal Ga target, and simultaneously controlling the temperature of the metal Ga target by utilizing a water cooling device, wherein the temperature control range of the water cooling device is 1-20 ℃; vacuumizing until the vacuum degree in the cavity is less than 1×10 ^- ⁵ Pa, and then filling a mixed gas of argon and nitrogen to make the air pressure reach 2-to-ultra5MPa; wherein the volume ratio of the argon to the nitrogen is 1:6-8; applying a voltage of 220-1000V to the metal Ga target to perform the third plasma sputtering so as to form the GaN strain layer (3);

the third MOCVD epitaxial growth process comprises the following steps: and carrying out MOCVD epitaxial growth on the surface of one side of the buffer layer (2) far away from the Si-based substrate (1) by taking trimethyl gallium as a gallium source and ammonia as a nitrogen source to form the GaN strain layer (3).

13. The method for manufacturing a double-sided Si-based AlGaN detector according to claim 10, wherein said Al _x Ga _1-x The alloy target is prepared by the following method:

according to the Al _x Ga _1-x The alloy target material is prepared by mixing Al and Ga, and placing metal Ga and Al powder into a crucible;

heating the crucible to 660-800 ℃ under the protection of argon gas to enable the metal Ga and the Al powder to be melted to form Al _x Ga _1-x Alloy melt;

with one end fixed with Al _x Ga _1-x Immersing a seed rod of a seed crystal into the Al _x Ga _1-x The alloy melt is then gradually pulled up to the seed rod and the Al is then added to the alloy melt _x Ga _1-x Forming the Al around the seed crystal by gradually growing crystal _x Ga _1-x An alloy target.

14. The method of manufacturing a double-sided Si-based AlGaN detector according to any one of claims 8 to 13, wherein said step S4 includes:

on the side of the top Si-based thin film layer (6) remote from the BOX buried layer (5) SiO is deposited ₂ A layer;

for the SiO ₂ Exposing the top Si-based thin film layer (6) corresponding to the N-type doped region (601) and the P-type doped region (602) to be formed by photoetching, and then performing phosphorus ion implantation at the exposed top Si-based thin film layer (6) to perform the N-type doped region (601) and performing boron ion implantation to form the P-type doped region (602);

annealing the device after the N-type doped region (601) and the P-type doped region (602) are formed;

after the annealing treatment is finished, forming a first N-type electrode (701) and a first P-type electrode (702) on one side, far away from the buffer layer (2), of the AlGaN undoped layer (4) so as to form the first electrode (7) with an interdigital structure; a second N-type electrode (801) is formed on one side of the N-type doped region (601) far away from the BOX buried layer (5), and a second P-type electrode (802) is formed on one side of the P-type doped region (602) far away from the BOX buried layer (5), so that the second electrode (8) with an interdigital structure is formed.

15. The method for preparing the double-sided Si-based AlGaN detector according to claim 14, wherein the materials of said first N-type electrode (701), first P-type electrode (702), said second N-type electrode (801) and said second P-type electrode (802) are Ti/Al/Ti/Au materials, which are prepared by the following preparation method:

covering the upper and lower surfaces of the period after the annealing treatment with patterned mask layers;

sequentially forming a Ti layer, an Al layer, a Ti layer and an Au layer which are stacked at corresponding positions by adopting a sputtering mode, stripping the mask layer, and annealing for 30-60 s at the temperature of 300-500 ℃ to form the first N-type electrode (701), the first P-type electrode (702), the second N-type electrode (801) and the second P-type electrode (802).