CN114284377A

CN114284377A - Double-sided Si-based AlGaN detector and preparation method thereof

Info

Publication number: CN114284377A
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: 2022-04-05
Anticipated expiration: 2041-12-31
Also published as: CN114284377B

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 non-doped layer, a BOX buried layer, a top Si-based 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 expanded 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

The electromagnetic wave with the wavelength ranging from 10nm to 400nm is called ultraviolet ray, and is divided into four subsections in the wave band: long wave ultraviolet (UV-A), medium wave ultraviolet (UV-B), short wave ultraviolet (UV-C), and vacuum ultraviolet (vacuum UV). The corresponding wavelength ranges of the ultraviolet light and the ultraviolet light are 400-320 nm, 320-280 nm, 280-200 nm and 200-10 nm respectively. At the earth's surface, solar radiation is the most dominant radiation source, where ultraviolet radiation with wavelengths less than 200nm is absorbed by gas molecules and free atoms in the atmosphere, making it completely absent at the earth's surface. Ultraviolet radiation having a wavelength below 300nm is absorbed by the earth's surrounding ozone layer. This means that when sunlight is emitted to the earth surface, only ultraviolet solar radiation with a wavelength of 300 to 400nm exists on the earth surface, while radiation with a wavelength in the range of 200 to 280nm cannot reach the earth surface due to absorption, and this wavelength is called the solar blind area. 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 alarm with extremely low false alarm rate, and has great strategic significance. The AlGaN-based material belongs to a direct band gap wide band gap semiconductor, the band gap can be continuously adjusted from 3.4eV to 6.2eV through the adjustment of Al components, the intrinsic cut-off wavelength covers the ultraviolet band of 200nm to 365nm, and the AlGaN-based material is an ideal material for preparing an intrinsic cut-off 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 size, small mass and capability of working in extreme environments.

In addition, among all photodetectors, the Si-based photodetector is the device that has been developed for the longest time and is the most mature in process technology. This is not only because Si is one of the earliest semiconductor materials discovered, but also because Si has the advantages of easy production, abundant resources, low cost, easy doping, etc., and with the development of microelectronic technology, the related technology also leads the preparation process of Si photodetectors 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 application requirements of different application fields, the Si photoelectric detector develops diversified structures 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 photodetector and the Si-based photodetector can be combined to form the double-sided Si-based AlGaN detector, the detection wavelength can be enlarged, the size occupied by the device can be reduced, and the mixed integration of the multi-wavelength detector can be realized.

Based on the above problems, there is a need to provide a new double-sided Si-based AlGaN detector to achieve better combination of the AlGaN-based solar blind ultraviolet photodetector and the Si-based photodetector.

Disclosure of Invention

The invention mainly aims to provide a double-sided Si-based AlGaN detector and a preparation method thereof, and aims to solve the problem that an AlGaN-based solar blind ultraviolet photodetector and a Si-based photodetector are difficult to be well combined 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 non-doping layer is arranged on the surface of one side of the buffer layer, which is far away from the Si-based substrate; the BOX buried layer is arranged 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 non-doped layer, which is far away from the buffer layer; and the second electrode is arranged on one side of the top Si-based film layer far 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 non-doped layer.

Further, the AlGaN non-doped layer is made of Al_xGa_1-xN, wherein x is more than 0 and less than 1; the Si-based substrate and the top Si-based thin film layer are both Si or both SiC.

Furthermore, the thickness of the buffer layer is 1-10 microns, the thickness of the GaN strain layer is 20-200 nm, the thickness of the AlGaN non-doped layer is 50-500 nm, the thickness of the BOX buried layer is 1-20 microns, 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.

Furthermore, the top Si-based thin film layer is provided with an N-type doped region, a P-type doped region and a neutral region, 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.

Furthermore, 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 double-sided Si-based AlGaN detector, including the following steps: 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, growing a buffer layer on the first surface of the Si-based substrate of the composite wafer by using a first plasma sputtering or a first MOCVD epitaxial growth method; step S3, forming an AlGaN non-doping layer on the surface of the buffer layer on the side 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 the side of the AlGaN non-doped layer far away from the buffer layer; and forming a second electrode on the side, far away from the BOX buried layer, of the top Si-based thin film layer so as to form 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 the ZnO target material in a cathode shielding case, placing the 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 then vacuumizing until the vacuum degree in the chamber is less than 1 x 10^-5Pa, then filling argon to make the air pressure reach 1-10 MPa; applying 380-1000V voltage to the ZnO target to perform a first plasma sputtering to form a buffer layer; when the buffer layer is an AlN layer, the buffer layer is formed by adopting a first MOCVD epitaxial growth mode, and the buffer layer comprises: 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 using trimethylaluminum as a base materialGrowing an AlN nucleating layer on the first surface of the Si-based substrate by using an aluminum source and ammonia gas as a nitrogen source; and continuously heating the composite wafer to 1180-1250 ℃ to perform recrystallization treatment on the AlN nucleating layer so as to form a buffer layer.

Further, the second plasma sputtering process comprises: by using Al_xGa_1-xThe alloy target material, wherein x is more than 0 and less than 1; vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10^-5Pa, then filling a mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of argon to nitrogen is 1: 7-8; to Al_xGa_1-xApplying 220-1000V voltage to the alloy target material to perform a second plasma sputtering process to form an AlGaN non-doped layer; the second MOCVD epitaxial growth process comprises the following steps: and performing MOCVD epitaxial growth on the surface of the buffer layer, which is far away from the Si-based substrate, by taking trimethyl gallium as a gallium source, trimethyl aluminum as an aluminum source and ammonia as a nitrogen source to form the AlGaN non-doping layer.

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

Further, the third plasma sputtering process comprises: the method comprises the following steps of (1) adopting a metal Ga target, and simultaneously controlling the temperature of the metal Ga target by using a water cooling device, wherein the temperature control range of the water cooling device is 1-20 ℃; vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10^- ⁵Pa, then filling a mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of argon to nitrogen is 1: 6-8; applying a voltage of 220-1000V to the metal Ga target to perform a third plasma sputtering process to form a GaN strained layer; the third MOCVD epitaxial growth process comprises the following steps: and performing 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 gas as a nitrogen source to form a GaN strain layer.

Further, Al_xGa_1-xThe alloy target is prepared by the following method: according to Al_xGa_1-xThe ratio of Al to Ga in the alloy target material is that metal Ga and Al powder are placed in a crucible; heating the crucible to 660-800 ℃ under the protection of argon gas, and melting metal Ga and Al powder to form Al_xGa_1-xAn alloy melt; with Al fixed to one end_xGa_1-xSeed rod of seed crystal is immersed in Al_xGa_1-xAlloy melt, then gradually pulling up the seed rod and making Al_xGa_1-xThe crystal forms grow to Al around the seed crystal_xGa_1-xAn alloy target material.

Further, step S4 includes: depositing SiO on the side of the top Si-based film layer far away from the BOX buried layer₂A layer; to SiO₂Photoetching the layers to expose the top Si-based thin film layer corresponding to the N-type doped region and the P-type doped region to be formed, and then performing phosphorus ion implantation on the exposed top Si-based thin film layer to perform the N-type doped region and perform boron ion implantation to form the P-type doped region; annealing the device with the N-type doped region and the P-type doped region; after the annealing treatment is finished, forming a first N-type electrode and a first P-type electrode on one side of the AlGaN non-doped layer, which is far away from the buffer layer, so as to form a first electrode with an interdigital structure; and forming a second N-type electrode on the side of the N-type doped region far away from the BOX buried layer, and forming a second P-type electrode on the 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 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 and are prepared by the following preparation method: covering patterned mask layers on the upper surface and the lower surface in the period after the annealing treatment; a Ti layer, an Al layer, a Ti layer and an Au layer which are arranged in a stacked mode are sequentially formed at corresponding positions in a sputtering mode, then the mask layer is stripped, annealing is carried out for 30-60 s at the temperature of 300-500 ℃, and a first N-type electrode, a first P-type electrode, a second N-type electrode and a second P-type electrode are formed.

The invention provides a double-sided Si-based AlGaN detector which comprises a Si-based substrate, an AlGaN detector structure and a Si detector structure, wherein the AlGaN detector structure and the Si detector structure are respectively positioned on two sides of the Si-based substrate. The AlGaN detector structure comprises a buffer layer and an AlGaN non-doped 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 expanded 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 incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic structural diagram of a double-sided Si-based AlGaN detector in accordance with an embodiment of the present invention;

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

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

FIG. 4 is a schematic diagram showing a plasma sputtering process of a GaN strained layer during the preparation of the double-sided Si-based AlGaN detector according to the present invention;

FIG. 5 shows Al in the process of preparing a double-sided Si-based AlGaN detector according to the present invention_xGa_1-xSchematic diagram of the alloy target material 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 is a schematic structural diagram of the present invention after a P-type doped region is further formed on the top Si-based thin film layer.

Wherein the figures include the following reference numerals:

1. a Si-based substrate; 2. a buffer layer; 3. a GaN strained 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 2₂A 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. compounding a wafer; 300. depositing a layer; 101. ga atoms; 110. a plasma cloud;

10. a crucible; 20. a reaction chamber; 30. a heating coil; 40. rotating the rod; 50. a seed rod; 60. a seed holder; 11. al (Al)_xGa_1-xAn alloy melt; 201. an observation window; 501. and (5) seed crystal.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The present invention will be further explained with reference to the accompanying drawings, wherein the terms "longitudinal", "radial", "width", "up", "down", "front", "back", "left", "right", "vertical", and the like, refer to an orientation or positional relationship indicated in the drawings, which are for convenience of description and simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. In addition, the description of "a plurality" in the present invention generally refers to two or more, unless otherwise specified.

As described in the background section, AlGaN-based solar blind ultraviolet 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, which includes a Si-based substrate, and an AlGaN detector structure and a Si detector structure respectively located on both sides of the Si-based substrate.

In an exemplary embodiment, as shown in fig. 1, the 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), a top Si-based thin film layer 6, a first electrode 7, and a second electrode 8, the Si-based substrate 1 having a first surface and a second surface opposite to each other; 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 non-doping layer 4 is arranged on the surface of one side of the buffer layer 2, which is far away from the Si-based substrate 1; the BOX buried layer 5 is arranged on the second surface of the Si-based substrate 1; the top Si-based film layer 6 is arranged on the surface of one side, far away from the Si-based substrate 1, of the BOX buried layer 5; the first electrode 7 is arranged on one side of the AlGaN non-doped layer 4 far away from the buffer layer 2; the second electrode 8 is disposed on the side of the top Si-based thin film layer 6 remote from the buried BOX layer 5.

According to the double-sided Si-based AlGaN detector, the AlGaN detector is combined with the Si-based detector in an organic manner. The AlGaN detector structure comprises a buffer layer and an AlGaN non-doped 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 expanded 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 beneficial to improving the stability of the combination of the two types of detectors in the double-sided Si-based AlGaN detector, because the ZnO and the Si-based substrate have a better lattice matching degree, a ZnO buffer layer with a more complete crystal structure can be grown.

In a preferred embodiment, as shown in fig. 1, the double-sided Si-based AlGaN detector further comprises a GaN strained layer 3 disposed between the buffer layer 2 and the AlGaN undoped layer 4. The GaN strain layer 3 is added, so that the overall performance of the device is further improved.

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

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

In one embodiment, the material of the AlGaN undoped layer 4 is Al_xGa_1-xN, wherein x is more than 0 and less than 1; the Si-based substrate 1 and the top Si-based thin film layer 6 are both Si or both SiC.

In order to enable the AlGaN detector to have better comprehensive performance such as structural stability, in a preferred embodiment, the thickness of the buffer layer 2 is 1-10 μm, the thickness of the GaN strain layer 3 is 20-200 nm, the thickness of the AlGaN non-doping layer 4 is 50-500 nm, the thickness of the BOX buried layer 5 is 1-20 μm, and the thickness of the top Si-based thin film layer 6 is 50-1000 nm.

The structure of the first electrode 7 and the second electrode 8 is common in the art, and more preferably, an interdigital structure is adopted, for example, 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 constitute 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 fig. 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, wherein the N-type doped region 601 and the P-type doped region 602 form an interdigital structure and are spaced by the neutral region 603; wherein, the second N-type electrode 801 is disposed on the side of the N-type doped region 601 far away from the buried BOX layer 5, and the second P-type electrode 802 is disposed on the side of the P-type doped region 602 far away from the buried BOX layer 5.

The above electrode materials can 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 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 sequentially include an Au layer, a Ti layer, an Al layer and a Ti layer from top to bottom, wherein Ti is used for enhancing metal adhesion and preventing the surface from being oxidized.

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 thin film layer 6 which are sequentially stacked;

step S2, growing a buffer layer 2 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 non-doping layer 4 on the surface of the buffer layer 2 on the side far away from the Si-based substrate 1 by adopting a second plasma sputtering or second MOCVD epitaxial growth mode;

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

In the preparation method, the buffer layer 2 and the AlGaN non-doping layer 4 are sequentially grown on one side of the Si-based substrate 1 of the composite wafer, and then electrodes are formed on the top Si-based thin film layer 6 and one side of the AlGaN non-doping layer 4 of the composite wafer, so that the double-sided Si-based AlGaN detector is finally obtained. In the preparation method, the ZnO buffer layer or the AlN buffer layer is formed in advance before the AlGaN non-doping 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 specifically explained as follows:

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

In plasma sputtering, at high temperature, all the material is ionized, which is called plasma (plasma) or ionized gas (ionized gas). The plasma is basically an aggregate of ionic gases, and in terms of space, ninety-five percent of all appear in a plasma state. The plasma is composed of ions, electrons, and neutrals, and is also referred to as the "fourth state". Electrons in the gas are excited by the applied electric field energy to gain energy and accelerate to impact the neutral particles, and the neutral particles impact the accelerated electrons to generate ions and accelerated electrons with other energy, so that the released electrons collide with other neutral particles after being accelerated by the electric field. This is repeated to generate a gas breakdown effect (gas breakdown) to form a plasma state. Plasma sputtering mainly utilizes inert gas atoms to collide with electrons moving at high speed, positive ions collide with the surface of a cathode or a target under the action of an electric field and a magnetic field, target atoms are collided and deposited on a substrate, and the empirical formula of plasma collision is as follows by taking Ar gas as an example:

Ar+e^-→Ar⁺+e^-(slow)+e^-(slow) (1)

thereby generating a large amount of plasma to impact the target material and deposit it on the substrate.

The sputtering method basically utilizes glow discharge to generate plasma, which can be divided into DC plasma and AC RF plasma. When sputtering is performed by using DC plasma, the sputtering yield is higher, i.e. the deposition rate is higher than that of AC RF, but the material of the electrode plate (sputtering target) must be conductor, otherwise the charge accumulation effect will occur. The use of an ac rf plasma does not have this limitation, but the deposition rate is slow.

For the strained GaN layer and the undoped AlGaN layer described below, the phasesMore preferably, the method is prepared by plasma sputtering compared with the MOCVD growth method, and the method is characterized in that: the plasma sputtering can be performed at a lower temperature (500-700 ℃) under a non-hydrogen condition (hydrogen is unstable, and the safety factor of the working environment is high). For the ZnO buffer layer, on one hand, the lattice matching degree of ZnO and the Si substrate is better, and high-quality crystals can grow on the Si substrate; on the other hand, the etching damage of the ZnO buffer layer can not be caused in the plasma sputtering process. Similar situation exists for the AlN buffer layer. The above two reasons further favor GaN strained layer and AlG_aAnd growing the N non-doped layer, and finally obtaining the double-sided Si-based AlGaN detector with better combination. Meanwhile, the GaN strain layer and the AlGaN non-doping layer are grown in a plasma sputtering mode, so that the preparation of large-size wafers is facilitated by 4-12 inches, the growth speed is high, no environmental pollution is caused, the required cost is reduced, and the industrial large-scale production and manufacturing are facilitated.

In the actual manufacturing 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 the ZnO target material in a cathode shielding case, 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 then vacuumizing until the vacuum degree in the chamber is less than 1 × 10-⁵Pa, then filling argon to make the air pressure reach 1-10 MPa; applying 380-1000V voltage to the ZnO target to perform the first plasma sputtering to form the buffer layer 2. In order to enable the growth of the ZnO layer to be more complete and uniform, the ZnO target can be placed in the cathode shielding case in the specific operation process, the composite wafer is placed on the base station, and the chamber is closed after the placement is finished. The chamber is pumped to vacuum state with vacuum degree less than 1 × 10 by molecular pump^-5Pa. And when the air pressure in the cavity reaches the required condition, filling argon into the cavity to ensure that the air pressure in the cavity reaches 1-10 MPa. Connecting the upper and lower target materials in the cavity with a power supply to form an electric field. The natural electrons existing between the upper electric field and the lower electric field have certain kinetic energy under the action of the electric field and can collide with Ar atoms existing in the cavity. Ar atoms are ionized after being impacted by electrons, changed into argon ions and releasedAn electron is released. The argon ions are driven by the electric field to move towards the cathode. Impacting the target material on the cathode to impact the zinc atoms and the oxygen atoms on the target material 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 μm.

When the buffer layer 2 is an AlN layer, the buffer layer 2 is formed by a first MOCVD epitaxial growth method, including: 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 nucleating layer on the first surface of the Si-based substrate 1 by using 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 nucleating layer so as to form the buffer layer 2.

In a preferred embodiment, the second plasma sputtering process comprises: by using Al_xGa_1-xThe alloy target material, wherein x is more than 0 and less than 1; vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10^-5Pa, then filling a mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of argon to nitrogen is 1: 7-8; to Al_xGa_1-xApplying 220-1000V voltage to the alloy target for the second plasma sputtering to form an AlGaN non-doped layer 4; the second MOCVD epitaxial growth process comprises the following steps: and performing MOCVD epitaxial growth on the surface of the buffer layer 2 far away from the Si-based substrate 1 by taking trimethyl gallium as a gallium source, trimethyl aluminum as an aluminum source and ammonia as a nitrogen source to form the AlGaN non-doping layer 4.

In a preferred embodiment, before forming the AlGaN undoped layer 4, the step S3 further includes: and firstly, forming a GaN strain layer 3 on the surface of the buffer layer 2, which is far away from the Si-based substrate 1, by adopting third plasma sputtering or third MOCVD epitaxial growth.

The growth process of the GaN strained layer 3 is similar to the above buffer layer formation, and in a preferred embodiment, the third plasma sputtering process comprises: the method comprises the following steps of (1) adopting a metal Ga target, and simultaneously controlling the temperature of the metal Ga target by using a water cooling device, wherein the temperature control range of the water cooling device is 1-20 ℃; vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10^-5Pa, then filling a mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of argon to nitrogen is 1: 6-8; applying a voltage of 220-1000V to the metal Ga target for the third plasma sputtering to form the GaN strained layer 3. Specifically, in order to make the sputtering process more stable, after the growth of the ZnO layer is completed, the target in the cathode shield can be replaced by a metal Ga target. Since the melting point of metallic Ga targets is only 29 ℃, a water cooling device needs to be added behind 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 chamber after the metal Ga target is placed. Pumping the chamber to vacuum state with vacuum degree less than 1 × 10 by using molecular pump^-5Pa. 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 target materials in the cavity 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^-Driven by the electric field to impact argon (Ar) and nitrogen (N) in the chamber₂) So that the argon gas is ionized to form argon ions (Ar)⁺) The nitrogen gas ionizes to form nitrogen ions (N)⁺) Nitrogen atom (N) and release an 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 to form Ga atoms 101. A high concentration plasma cloud 110 is formed in 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 deposition thickness is 20 nm-200 nm.

Preferably, the third MOCVD epitaxial growth process comprises: and performing MOCVD epitaxial growth on the surface 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 gas as a nitrogen source to form a GaN strain layer 3.

In a preferred embodiment, the second plasma sputtering process comprises: by using Al_xGa_1-xThe alloy target material, wherein x is more than 0 and less than 1; vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10^-5Pa, then filling argonThe mixed gas of nitrogen and the nitrogen enables the air pressure to reach 2-5 MPa; wherein the volume ratio of argon to nitrogen is 1: 7-8; to Al_xGa_1-xApplying 220-1000V voltage to the alloy target for the second plasma sputtering to form the AlGaN non-doped layer 4. In order to ensure that the growth of the layer is more stable and complete, the target material in the cathode shielding case can be replaced by Al after the growth of the GaN strain layer 3 is finished_xGa_1-xAn alloy target material. Al (Al)_xGa_1-xAfter the alloy target material is placed, the chamber is closed, the gas in the chamber is pumped out by a molecular pump, and the vacuum degree in the chamber is less than 1 multiplied by 10^-5Pa. 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 target materials in the cavity with a power supply to form an electric field. Natural electrons exist in an electric field between the upper target and the lower target, the electrons are driven by the electric field to impact argon and nitrogen in the cavity, so that the argon is ionized to form argon ions, the nitrogen is ionized to form nitrogen ions, and nitrogen atoms release the electrons. The generated argon ions and nitrogen ions impact Al under the driving of an electric field_xGa_1-xAlloying of the target material to Al_xGa_1-xThe alloy target is detached to form Al and Ga atoms. A high concentration plasma cloud is formed in the chamber, including nitrogen ions, argon ions, nitrogen atoms, Al atoms and Ga atoms. As the concentration increases, nitrogen atoms, Al atoms and Ga atoms combine to form Al_xGa_1-xN is deposited on the strained layer of gallium nitride. The applied voltage is 220V-1000V, and the deposition thickness is 50 nm-500 nm.

The second MOCVD epitaxial growth process comprises: performing MOCVD epitaxial growth on the surface of the buffer layer 2 far away from the Si-based substrate 1 by using trimethyl gallium as a gallium source, trimethyl aluminum as an aluminum source and ammonia as a nitrogen source to form the AlGaN non-doping layer 4.

The above-mentioned Al of the present invention_xGa_1-xThe alloy target can be prepared by the following method: according to Al_xGa_1-xThe ratio of Al to Ga in the alloy target material is that metal Ga and Al powder are placed in a crucible; heating the crucible to 660-800 ℃ under the protection of argon gas, and melting metal Ga and Al powder to form Al_xGa_1-xAn alloy melt;with Al fixed to one end_xGa_1-xSeed rod of seed crystal is immersed in Al_xGa_1-xAlloy melt, then gradually pulling up the seed rod and making Al_xGa_1-xThe crystal forms grow to Al around the seed crystal_xGa_1-xAn alloy target material.

Specifically, as shown in fig. 5, first, Al powder having a purity of 99.999% and metal Ga are prepared and placed in a crucible 10 in this order, and a small piece of metal Ga is placed on the bottom, and then the Al powder is scattered on the small piece of metal Ga, so that the Al powder leaks into the gap of the small piece of Ga, 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 the Ga is x: (1-x), wherein the value of x is more than 0 and less than 1. After the material is placed, the reaction chamber 20 is closed, the reaction chamber 20 is vacuumized, and the vacuum degree is reduced to 1 × 10^-5Pa or less. Then, a 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 to heat the crucible 10, and the temperature in the crucible 10 is raised to 660 ℃. When the melting of Al powder and Ga block in the crucible 10 is seen through the observation window 201 of the reaction chamber 20, the rotating rod 40 at the bottom of the crucible 10 is rotated, so that Al in the crucible 10 is formed_xGa_1-xThe alloy melt 11 is sufficiently fused. Al is fixed on the seed crystal rod 50_xGa_1-xThe small alloy block (seed crystal 501), the seed crystal holder 60 controls the seed crystal rod to slowly pull Al_xGa_1-xAlloy bits, influenced by temperature gradients, Al_xGa_1-xThe alloy small blocks gradually coarsen to form cylindrical Al_xGa_1-xAnd (3) alloying. When the crucible 10 is pulled to a certain length, the heating of the crucible by the coil is stopped. Naturally cooling the temperature in the reaction chamber 20 to room temperature, and taking out Al_xGa_1-xAlloy pillar to remain as Al_xGa_1-xThe alloy target material is used.

In a preferred embodiment, step S4 includes: SiO is deposited on the side of the top Si-based film layer 6 far away from the BOX buried layer 5₂A layer 9; to SiO₂Photoetching the layers 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 carrying out phosphorus ion treatment on the exposed top Si-based thin film layer 6Implanting to form an N-type doped region 601 and boron ion implantation to form a P-type doped region 602; annealing the device formed with the N-type doped region 601 and the P-type doped region 602; 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 non-doped layer 4, which is far away from the buffer layer 2, so as to form a first electrode 7 with an interdigital structure; a second N-type electrode 801 is formed on the side of the N-type doped region 601 far away from the buried BOX layer 5, and a second P-type electrode 802 is formed on the side of the P-type doped region 602 far away from the buried BOX layer 5, so as to form a second electrode 8 with an interdigital structure. Deposition of SiO₂The layer 9 is beneficial to protecting a non-injection region (the neutral region 603) in the subsequent ion injection process, prevents high-energy ions from damaging the surface of the Si-based film, and increases surface electric leakage. Specific SiO₂The thickness of the layer 9 is preferably 10 to 20 nm. The annealing treatment is beneficial to activating ions, and can further eliminate dislocation and repair injection damage. Specifically, the rapid annealing may be performed at 1000 ℃. The above processes of 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 can be performed by means existing in the art, for example, as shown in fig. 6, first covering the top Si-based thin film layer 6 outside the N-type doped region 601 with the first patterned photoresist 8', and then performing phosphorus ion implantation to form the N-type doped region 601; as shown in fig. 7, the photoresist is removed, the top Si-based thin film layer 6 and the N-type doped region 601 except for the P-type doped region 602 are covered by the second patterned photoresist 8 ", and then boron ion implantation is performed to form the P-type doped region 602, which is not described herein again.

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 Ti/Al/Ti/Au materials, which are prepared by the following preparation methods: covering patterned mask layers on the upper surface and the lower surface in the period after the annealing treatment; a Ti layer, an Al layer, a Ti layer and an Au layer which are arranged in a stacked mode are sequentially formed at corresponding positions in a sputtering mode, then the mask layer is stripped, annealing is carried out for 30-60 s at the temperature of 300-500 ℃, and 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 are formed. The function of Ti is to enhance the adhesion of metal and to prevent the surface from being oxidized.

In the first plasma sputtering process, the second plasma sputtering process and the third plasma sputtering process, the power source can be a direct current 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 with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

Example 1

Step 1: preparation of the material. First, a Si-on-insulator (SOI) substrate is provided, the top Si thin film is a neutral layer with a thickness of 200nm, the buried layer thickness of the middle BOX is 2 μm, and the bottom Si substrate is a neutral layer and is of conventional thickness. Next, ZnO and metallic Ga targets with a purity of 99.999% were prepared to be left for use. Next, an algaam alloy target is prepared. Firstly, preparing Al powder with the purity of 99.999 percent and metal Ga to be sequentially placed in a crucible, placing small metal Ga blocks at the bottom, then scattering the Al powder on the small metal Ga blocks, wherein the Al powder can leak into gaps of the small metal Ga blocks, the melting point of the Al powder is 660 ℃, and the melting point of the Ga is 29.8 ℃. The ratio of 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 × 10^- ⁵Pa. Then, protective gas argon is filled into the reaction chamber, so that the pressure in the reaction chamber reaches 1 MPa. The heating coil around the crucible was connected to a power supply to heat the crucible, and the temperature in the crucible was raised to 700 ℃. When the Al powder and the Ga blocks in the crucible are melted through the observation window of the reaction chamber, the rotating rod at the bottom of the crucible is rotated, so that the Al in the crucible is_0.4Ga_0.6The alloy melt is fully fused. The seed crystal rod is fixed with AlGa alloy small blocks, the seed crystal holder controls the seed crystal rod to slowly lift the AlGa alloy small blocks, and the AlGa alloy small blocks slowly become thick to form a cylindrical Al under the influence of temperature gradient_0.4Ga_0.6And (3) alloying. 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, and taking out Al_0.4Ga_0.6Alloy pillar to remain as Al_0.4Ga_0.6The alloy target material is used.

Step 2: and (4) preparing a buffer layer. And growing a buffer layer above the Si substrate of the SOI composite wafer, wherein the buffer layer is made of ZnO material. The ZnO target was placed in a cathode shield. And placing the SOI substrate on the base station, and closing the cavity after the placing is finished. The chamber is pumped into a vacuum state with a vacuum degree of 5 × 10 by a molecular pump^-6Pa. When the air pressure in the cavity reaches the required condition, argon is filled into the cavity, so that the air pressure in the cavity reaches 2 MPa. Connecting the upper and lower target materials in the cavity with a power supply to form an electric field. One side of the target material is connected with the cathode of the power supply, and natural electrons existing between the upper electric field and the lower electric field have certain kinetic energy under the action of the electric field and impact 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 towards the cathode. Impacting the target material on the cathode to impact the zinc atoms and the oxygen atoms on the target material 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 deposit grown was 2 μm.

And step 3: and preparing a gallium nitride strained layer. And after the growth of ZnO is finished, replacing the target in the cathode shielding case with a metal Ga target. Since the melting point of metallic Ga targets is only 29 ℃, a water cooling device needs to be added behind the target. The temperature of the water cooling device was maintained at 5 ℃ to ensure solidification of the metal Ga during sputtering. And closing the chamber after the metal Ga target is placed. Pumping the chamber to vacuum state with vacuum degree less than 1 × 10 by using molecular pump^-5Pa. 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 target materials in the cavity with a power supply to form an electric field. Natural electrons exist in an electric field between the upper target and the lower target, the electrons are driven by the electric field to impact argon and nitrogen in the cavity, so that the argon is ionized to form argon ions, the nitrogen is ionized to form nitrogen ions, and nitrogen atoms release the electrons. 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 separatedTo form Ga atoms. A high concentration plasma cloud is formed in 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 to be deposited on the ZnO buffer layer. Applied voltage 880V, deposited to a thickness of 20 nm;

and 4, step 4: al (Al)_0.4Ga_0.6And preparing an N device layer. After the growth of the GaN strain layer is finished, the target material in the cathode shielding case is replaced by Al_0.4Ga_0.6An alloy target material. Al (Al)_0.4Ga_0.6After the alloy target material is placed, the chamber is closed, the gas in the chamber is pumped out by a molecular pump, and the vacuum degree in the chamber is 1 multiplied by 10^-5Pa. 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 target materials in the cavity with a power supply to form an electric field. Natural electrons exist in an electric field between the upper target and the lower target, the electrons are driven by the electric field to impact argon and nitrogen in the cavity, so that the argon is ionized to form argon ions, the nitrogen is ionized to form nitrogen ions, and nitrogen atoms release the electrons. The generated argon ions and nitrogen ions impact Al under the driving of an electric field_0.4Ga_0.6Alloying of the target material to Al_0.4Ga_0.6The alloy target is detached to form Al and Ga atoms. A high concentration plasma cloud is formed in the chamber, including nitrogen ions, argon ions, nitrogen atoms, Al atoms and Ga atoms. As the concentration increases, nitrogen atoms, Al atoms and Ga atoms combine to form Al_0.4Ga_0.6N is deposited on the strained layer of gallium nitride. The applied voltage is 1000V, and the deposition thickness is 300 nm;

and 5: and (5) preparing a Si detector. When Al is present_0.4Ga_0.6And after the N device layer is prepared, taking out the substrate on the base station. And preparing a device on the top layer Si film in the SOI substrate on the other side of the substrate. Firstly, a layer of SiO with the thickness of 20nm is deposited on the top layer Si film₂Layer of SiO₂The layer is used for protecting the subsequent ion implantation, so that the damage of high-energy ions to the Si surface is prevented, and the surface electric leakage is increased;

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

And 7: and (6) performing rapid annealing. Annealing rapidly at 1000 deg.C to activate ions, and can further eliminate dislocation and repair implantation damage;

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

Example 2:

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

Step 1: preparation of the material. First, a Si-on-insulator (SOI) substrate is provided, the top Si thin film is a neutral layer with a thickness of 250nm, the buried layer thickness of the middle BOX is 2 μm, and the bottom Si substrate is a neutral layer and is of conventional thickness. Next, ZnO and metallic Ga targets with a purity of 99.999% were prepared to be left for use. Next, an algaam alloy target is prepared. Firstly, preparing Al powder with the purity of 99.999 percent and metal Ga to be sequentially placed in a crucible, placing small metal Ga blocks at the bottom, then scattering the Al powder on the small metal Ga blocks, wherein the Al powder can leak into gaps of the small metal Ga blocks, the melting point of the Al powder is 660 ℃, and the melting point of the Ga is 29.8 ℃. The ratio of 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^- ⁶Pa. Then, protective gas argon is filled into the reaction chamber, so that the pressure in the reaction chamber reaches 1 MPa. The heating coil around the crucible was connected to a power supply to heat the crucible, and the temperature in the crucible was raised to 700 ℃. When the Al powder and the Ga blocks in the crucible are melted through the observation window of the reaction chamber, the rotating rod at the bottom of the crucible is rotated, so that the Al in the crucible is_0.3Ga_0.7The alloy melt is fully fused. The seed crystal rod is fixed with AlGa alloy small blocks, the seed crystal holder controls the seed crystal rod to slowly lift the AlGa alloy small blocks, and the AlGa alloy small blocks slowly become thick to form a cylindrical Al under the influence of temperature gradient_0.3Ga_0.7And (3) alloying. When the pulling is carried out to a certain length, the operation is stoppedAnd heating the crucible by the stop coil. Naturally cooling the temperature in the reaction chamber to room temperature, and taking out Al_0.3Ga_0.7Alloy pillar to remain as Al_0.3Ga_0.7The alloy target material is used.

And step 3: al (Al)_0.3Ga_0.7And preparing a device layer. After the growth of the GaN strain layer is finished, the target material in the cathode shielding case is replaced by Al_0.3Ga_0.7An alloy target material. Al (Al)_0.3Ga_0.7After the alloy target material is placed, the chamber is closed, the gas in the chamber is pumped out by a molecular pump, and the vacuum degree in the chamber is 1 multiplied by 10^-5Pa. 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 target materials in the cavity with a power supply to form an electric field. Natural electrons exist in an electric field between the upper target and the lower target, the electrons are driven by the electric field to impact argon and nitrogen in the cavity, so that the argon is ionized to form argon ions, the nitrogen is ionized to form nitrogen ions, and nitrogen atoms release the electrons. The generated argon ions and nitrogen ions are driven by an electric fieldImpact Al_0.3Ga_0.7Alloying of the target material to Al_0.3Ga_0.7The alloy target is detached to form Al and Ga atoms. A high concentration plasma cloud is formed in the chamber, including nitrogen ions, argon ions, nitrogen atoms, Al atoms and Ga atoms. As the concentration increases, nitrogen atoms, Al atoms and Ga atoms combine to form Al_0.3Ga_0.7N is deposited on the strained layer of gallium nitride. The applied voltage is 1000V, and the deposition thickness is 300 nm;

and 4, step 4: and (5) preparing a Si detector. When Al is present_0.3Ga_0.7And after the N device layer is prepared, taking out the substrate on the base station. And preparing a device on the top layer Si film in the SOI substrate on the other side of the substrate. Firstly, a layer of SiO with the thickness of 20nm is deposited on the top layer Si film₂Layer of SiO₂The layer is used for protecting the subsequent ion implantation, so that the damage of high-energy ions to the Si surface is prevented, and the surface electric leakage is increased;

and 5: and (5) ion implantation. M2 reverse photoetching, and phosphorus ion implantation to form N-type doping. M3 reverse photoetching, and boron ion implantation to form P type doping.

Step 6: and (6) performing rapid annealing. Annealing rapidly at 1000 deg.C to activate ions, and can further eliminate dislocation and repair implantation damage;

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

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 the material. First, a Si-on-insulator (SOI) substrate is provided, the top Si thin film is a neutral layer with a thickness of 300nm, the buried layer thickness of the middle BOX is 5 μm, and the bottom Si substrate is a neutral layer and is of conventional thickness.

Step 2: production of AlN buffer layerAnd (4) preparing. And growing a buffer layer above the Si substrate of the SOI composite wafer, 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, low oxygen purity grade). The substrate is heated to 1200 ℃ and treated in hydrogen environment for 10min before epitaxial growth. The high temperature treatment has two functions, namely, removing residual pollution on the surface of the substrate and desorbing oxygen atoms forming the surface of the crystal lattice. Then, the substrate temperature was lowered to about 700 ℃, and a low-temperature AlN nucleation layer of about 200nm was grown, and then the substrate was heated to 1180 ℃ to perform recrystallization on the AlN nucleation layer. The flow rate of ammonia gas is 1000sccm, the carrier gas is a 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, and the gas pressure in the reaction chamber is 2X 10³Pa；

And step 3: and preparing a gallium nitride strained layer. And after the AlN buffer layer is grown, growing a gallium nitride strain layer with the thickness of about 50nm by using MOCVD. The flow rate of ammonia gas is 1000sccm, the carrier gas is a 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 10³Pa；

And 4, step 4: al (Al)_0.2Ga_0.8And preparing an N device layer. After the growth of the GaN strain layer is finished, Al with the thickness of about 300nm is grown by using MOCVD_0.2Ga_0.8And N device layers. The flow rate of ammonia gas is 1000sccm, the carrier gas is a 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 gas pressure in the reaction chamber is 2.5 multiplied by 10³Pa；

And 5: and (5) preparing a Si detector. When Al is present_0.2Ga_0.8And after the N device layer is prepared, taking out the substrate on the base station. And preparing a device on the top layer Si film in the SOI substrate on the other side of the substrate. Firstly, a layer of SiO with the thickness of 20nm is deposited on the top layer Si film₂Layer of SiO₂The layer is used for protecting the subsequent ion implantation to prevent the high-energy ions from causing the Si surfaceDamage, increase surface leakage;

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement 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 opposing first and second surfaces;

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

the AlGaN undoped layer (4) is arranged on the surface of one side, far away from the Si-based substrate (1), of the buffer layer (2);

a BOX buried layer (5) disposed at 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, far away from the Si-based substrate (1), of the BOX buried layer (5);

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

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

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

3. The double-sided Si-based AlGaN detector according to claim 1, wherein the material of the AlGaN non-doped layer (4) is Al_xGa_1-xN, wherein x is more than 0 and less than 1; the Si-based substrate (1) and the top Si-based thin film layer (6) are both Si or both SiC.

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

5. The double-sided Si-based AlGaN detector according to any one of claims 1 to 4, wherein the first electrode (7) comprises 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) 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 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), and the N-type doped region (601) and the P-type doped region (602) form an interdigital structure and are arranged at intervals through the neutral region (603); wherein the second N-type electrode (801) is arranged on the side of the N-type doped region (601) far away from the BOX buried layer (5), and the second P-type electrode (802) is arranged on the side of the P-type doped region (602) far away from the BOX buried layer (5).

7. The double-sided Si-based AlGaN detector according to claim 5, wherein 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.

8. A method of fabricating a 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 thin film layer (6) which are sequentially stacked;

step S2, growing a buffer layer (2) 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;

step S3, forming an AlGaN non-doping 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 the side of the AlGaN non-doped layer (4) far away from the buffer layer (2); and forming a second electrode (8) on one side of the top Si-based thin film layer (6) far away from the BOX buried layer (5), thereby forming the double-sided Si-based AlGaN detector.

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

when the buffer layer (2) is a ZnO layer, the buffer layer (2) is formed by adopting the first plasma sputtering method, and the method comprises the following steps:

providing a plasma sputtering apparatus;

placing the ZnO target in a cathode shielding case, 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 then vacuumizing the chamberThe vacuum degree in the chamber is less than 1 x 10^-5Pa, then filling argon to make the air pressure reach 1-10 MPa;

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

when the buffer layer (2) is an AlN layer, the buffer layer (2) is formed by adopting the first MOCVD epitaxial growth mode, and the method comprises the following steps:

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 nucleating layer on the first surface of the Si-based substrate (1) by using 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 nucleating layer so as to form the buffer layer (2).

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

the second plasma sputtering process comprises: by using Al_xGa_1-xThe alloy target material, wherein x is more than 0 and less than 1; vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10^-5Pa, then filling a mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of argon to nitrogen is 1: 7-8; to the Al_xGa_1-xApplying a voltage of 220-1000V to the alloy target for the second plasma sputtering to form the AlGaN non-doping layer (4);

the second MOCVD epitaxial growth process comprises: and performing MOCVD epitaxial growth on the surface of one side, away from the Si-based substrate (1), of the buffer layer (2) by taking trimethyl gallium as a gallium source, trimethyl aluminum as an aluminum source and ammonia as a nitrogen source to form the AlGaN non-doping layer (4).

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

12. The method of fabricating a double-sided Si-based AlGaN detector according to claim 11,

the third plasma sputtering process comprises: the method comprises the following steps of (1) adopting a metal Ga target, and simultaneously controlling the temperature of the metal Ga target by using a water cooling device, wherein the temperature control range of the water cooling device is 1-20 ℃; vacuumizing until the vacuum degree in the chamber is less than 1 multiplied by 10^- ⁵Pa, then filling a mixed gas of argon and nitrogen to enable the air pressure to reach 2-5 MPa; wherein the volume ratio of argon to 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 strained layer (3);

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

13. The method of claim 10, wherein said Al is selected from the group consisting of_xGa_1-xThe alloy target is prepared by the following method:

according to said Al_xGa_1-xThe ratio of Al to Ga in the alloy target material is that metal Ga and Al powder are placed in a crucible;

heating the crucible to 660-800 ℃ under the protection of argon gas, and melting the metal Ga and the Al powder to form Al_xGa_1-xAn alloy melt;

with Al fixed to one end_xGa_1-xThe seed rod of the seed crystal is immersed in the Al_xGa_1-xAlloy melt, then gradually pulling up the seed rod and leading the Al to be_xGa_1-xThe crystal forms are gradually grown around the seed crystal to form the Al_xGa_1-xAn alloy target material.

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

depositing SiO on the side of the top Si-based thin film layer (6) far away from the BOX buried layer (5)₂A layer;

for the SiO₂Photoetching is carried out on the layers to expose the top layer 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 phosphorus ion implantation is carried out on the exposed top layer Si-based thin film layer (6) to carry out the N-type doped region (601) and 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 of the AlGaN non-doped layer (4) far away from the buffer layer (2) so as to form the first electrode (7) with an interdigital structure; and forming a second N-type electrode (801) on the side of the N-type doped region (601) far away from the BOX buried layer (5), and forming a second P-type electrode (802) on the side of the P-type doped region (602) far away from the BOX buried layer (5), thereby forming the second electrode (8) with an interdigital structure.

15. The method for preparing a double-sided Si-based AlGaN detector according to claim 14, wherein 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 Ti/Al/Ti/Au materials, and are prepared by the following preparation method:

covering patterned mask layers on the upper surface and the lower surface in the period after the annealing treatment;

sequentially forming a Ti layer, an Al layer, a Ti layer and an Au layer which are stacked at corresponding positions in a sputtering mode, then stripping the mask layer, and annealing at the temperature of 300-500 ℃ for 30-60 s 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).