WO2016112773A1 - 一种半导体器件的三维电极结构及其制备方法和应用 - Google Patents

一种半导体器件的三维电极结构及其制备方法和应用 Download PDF

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WO2016112773A1
WO2016112773A1 PCT/CN2015/098138 CN2015098138W WO2016112773A1 WO 2016112773 A1 WO2016112773 A1 WO 2016112773A1 CN 2015098138 W CN2015098138 W CN 2015098138W WO 2016112773 A1 WO2016112773 A1 WO 2016112773A1
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electrode
single crystal
metal
crystal diamond
dimensional
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French (fr)
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王宏兴
刘璋成
王玮
李奉南
张景文
卜忍安
侯洵
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Xian Jiaotong University
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F71/00—Manufacture or treatment of devices covered by this subclass
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/20—Electrodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
    • H10F30/10—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices being sensitive to infrared radiation, visible or ultraviolet radiation, and having no potential barriers, e.g. photoresistors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • the invention belongs to the technical field of photoelectric detection, and relates to a three-dimensional electrode structure of a semiconductor device, a preparation method thereof and an application thereof.
  • Ultraviolet photodetection technology is a very important technology, which can be widely used in space flame detection, smoke alarm, space communication and other fields. Due to the complex working environment, the material requirements of the detector are very high. As a wide bandgap semiconductor, diamond has a cut-off wavelength of 225 nm and has natural visible light filtering properties, making it ideal for preparing solar blind UV detectors. At the same time, diamond has many excellent properties, high thermal conductivity, good thermal stability, good chemical stability and good radiation resistance. These make diamonds a huge advantage in the field of UV detectors.
  • the electrode structure of the conventional diamond ultraviolet photodetector is mainly a coplanar interdigitated electrode structure and a vertical sandwich structure.
  • the electric field uniformity is good, which is beneficial to the drift motion of the photogenerated carriers, so that the sensitivity and the collection efficiency are high.
  • the diamond film is required to be thin, and the defect density of the nucleation surface is as small as possible, so that the photogenerated electron-hole pairs are as far as possible during the drift between the electrodes. Less recombination, so that more carriers are reached at the electrode, contributing a great deal to charge collection efficiency and sensitivity.
  • the overall thickness is thick, which is disadvantageous for carrier drift and collection.
  • the coplanar interdigitated electrode structure is an improvement over the vertical sandwich structure. Since the ultraviolet light penetrates less deeply in the diamond film and mainly concentrates on the surface, the interdigital electrode is prepared on the diamond surface. Photogenerated electron-hole pairs near the surface can be better collected. Since the ultraviolet light attenuates rapidly in the material, the contribution to the current is small after penetrating a certain depth, so the collection efficiency of the interdigitated electrode is also relatively high. And the interdigital electrodes are interlaced, so that the effective detection area of the detector increases, which greatly contributes to the responsiveness of the detector. However, the electric field uniformity of the interdigital electrodes is not as good as that of the vertical structure. When the ultraviolet light power is large, the uneven distribution of the electric field will affect the collection of photogenerated electron-hole pairs.
  • Diamond has good radiation resistance and can maintain the normal operation of the device under irradiation. Diamond also has a high thermal conductivity, and the heat in the high-energy particle experiment is transmitted to the unit in a timely and effective manner. At the same time, the dielectric coefficient of diamond is small, and the noise current of the device does not change under irradiation, so that the device has high resolution, which is what the particle detector needs.
  • the structure of the diamond particle detector is a vertical electrode structure, that is, a sandwich structure.
  • the early diamond particle detector was made of polycrystalline diamond film and belonged to heteroepitaxial on silicon. The separation of diamond and silicon was very simple.
  • the sandwich structure was basically in a uniform diamond film. However, due to the influence of polycrystalline diamond grain boundaries, defects, and the like, the structure has problems such as long collection time of carriers and low collection efficiency.
  • An object of the present invention is to provide a three-dimensional electrode structure of a semiconductor device, which solves the problem of small effective effective detection area, long carrier collection time, and low collection efficiency when a vertical sandwich electrode structure is used, and electric field uniformity when a coplanar interdigital electrode structure is used. Poor question.
  • the three-dimensional electrode structure of the semiconductor device of the present invention comprises a single crystal diamond wafer material.
  • the single crystal diamond wafer material is provided with two metal electrode pads respectively serving as a positive electrode and a negative electrode, and each metal electrode pad is connected to one or more equidistant intervals.
  • the interdigital electrodes are each connected with one or more columnar metal electrodes arranged in parallel with each other and disposed in the single crystal diamond wafer material.
  • the columnar metal electrode is disposed through the single crystal diamond wafer material, or only extends to a certain depth.
  • columnar metal electrodes are arranged vertically or obliquely.
  • each of the interdigital electrodes is a parallel electrode or a ring electrode, and each of the interdigital electrodes is located on the surface or inside of the single crystal diamond wafer material.
  • metal electrode pad and the interdigital electrode are bridged or directly covered.
  • the materials of the metal electrode pad, the interdigital electrode and the columnar metal electrode are the same or different, but are required to be a metal capable of forming an ohmic contact with diamond or a metal capable of forming a conductive carbide with diamond.
  • the single crystal diamond wafer material is a self-supporting single crystal diamond film, or a single crystal diamond epitaxial layer comprising a single crystal diamond substrate.
  • the shape of the single crystal diamond wafer material is rectangular, circular, elliptical or other shapes, and the two metal electrode pads are disposed on the side, the top or the bottom surface of the single crystal diamond wafer material, and between the two metal electrode pads Set for coplanar or different faces.
  • an ohmic contact is formed between each of the columnar metal electrodes and the single crystal diamond wafer material by annealing.
  • the three-dimensional electrode structure of the above semiconductor device of the present invention is suitable for a diamond ultraviolet photodetector or a particle detector.
  • the method for preparing a three-dimensional electrode structure of the above semiconductor device of the present invention comprises the following steps:
  • Step 1 etching a three-dimensional hole array on the single crystal diamond wafer material by using a diamond etching technique
  • Step 2 filling each of the three-dimensional holes with a metal to form a columnar metal electrode, and performing annealing treatment;
  • Step 3 Connect the corresponding three-dimensional hole to the metal electrode pad through the interdigital electrode.
  • the invention has the advantages that the body electrode is introduced into the self-supporting single crystal diamond film or the single crystal diamond epitaxial layer containing the single crystal diamond wafer substrate in combination with the advantages of the planar electrode structure and the vertical electrode structure, thereby realizing ultraviolet light or particles.
  • the efficient and rapid collection of electron-hole pairs excited by the beam enhances the response time and sensitivity of the detector.
  • the body electrode structure can avoid the complexity of the surface of the single crystal diamond wafer and increase the stability of the device.
  • the anti-irradiation performance can also be improved.
  • FIG. 1 is a schematic view showing the structure of a three-dimensional electrode structural material of a semiconductor device of the present invention, which is a single crystal diamond substrate and an epitaxial growth film thereof;
  • FIG. 2 is a schematic structural view of a three-dimensional electrode structure substrate of a semiconductor device of the present invention, which is a self-supporting single crystal diamond film;
  • FIG. 3 is a schematic structural view of the metal electrode pad of FIG. 1 disposed on a different surface
  • FIG. 4 is a schematic structural view of the metal electrode pad of FIG. 2 disposed on a different surface
  • Figure 5 is a schematic view showing the structure of the metal electrode pad of Figure 2 disposed on the side;
  • Figure 6 is a schematic view showing the structure of the columnar metal electrode of Figure 1;
  • Figure 7 is a schematic view showing the structure of the interdigital electrode of the present invention.
  • FIGS. 8(a) and 8(b) are schematic views showing a three-dimensional aperture array method in a method for fabricating a three-dimensional electrode structure of a semiconductor device according to the present invention
  • 9(a) to 9(d) are schematic diagrams showing three three-dimensional hole penetration depths in a method for fabricating a three-dimensional electrode structure of a semiconductor device according to the present invention.
  • FIGS. 10(a) to 10(c) are schematic views showing the formation of an evaporation coating metal filling and a surface electrode in a method for fabricating a three-dimensional electrode structure of a semiconductor device according to the present invention
  • 11(a) to 11(d) are schematic views showing the formation of a molten metal flow and surface electrode formation in a method of fabricating a three-dimensional electrode structure of a semiconductor device of the present invention.
  • metal electrode pad 2. interdigital electrode, 3. columnar metal electrode, 4. self-supporting single crystal diamond film, 5. single crystal diamond substrate, 6. single crystal diamond epitaxial growth film, 7. Filling metal, 8. molten metal flow, 9. oxygen plasma, 10. mask.
  • the present invention provides a three-dimensional electrode structure of a semiconductor device, comprising a single crystal diamond wafer material.
  • the single crystal diamond wafer material is provided with two metal electrodes pad1 as positive and negative electrodes, respectively, and each metal electrode pad1 is connected to one or more
  • the interdigital electrodes 2 are equally spaced, and each of the interdigital electrodes 2 is connected with one or more columnar metal electrodes 3 which are parallel to each other and disposed in the single crystal diamond wafer material, and each of the columnar metal electrodes 3 and the single crystal diamond An ohmic contact is formed between the wafer materials by annealing.
  • the invention processes a three-dimensional parallel hole array on a single crystal diamond wafer material by a plasma etching technique, and then fills the hole array with a metal to form a three-dimensional body electrode.
  • these three-dimensional body electrodes are connected to each other by an interdigital electrode to form a semiconductor.
  • the three-dimensional electrode structure of the device is not limited to a plasma etching technique.
  • the single crystal diamond wafer material is a self-supporting single crystal diamond film, or a single crystal diamond epitaxial film containing a single crystal diamond substrate.
  • the shape of the single crystal diamond wafer material is rectangular, circular, elliptical or other shape.
  • the columnar metal electrode 3 is disposed through the single crystal diamond wafer material, or only extends to a certain depth.
  • the position of the columnar metal electrode 3 may be in the epitaxial layer only, or may extend into the substrate, or may penetrate the substrate. Similarly, it can be in the self-supporting diamond film or through the self-supporting diamond film.
  • the columnar metal electrode 3 is disposed vertically or obliquely.
  • the columnar metal electrode 3 is not limited to the surface of the vertical single crystal diamond wafer material, but may be disposed at a certain angle with the surface of the single crystal diamond wafer material, but the columnar metal electrode 3 is satisfied. Parallel to each other.
  • the shape of the columnar metal electrode 3 may be any shape such as a cylinder or a square column.
  • the interdigital electrodes 2 are parallel electrodes or ring electrodes; and each of the interdigital electrodes 2 is located on the surface or inside of the single crystal diamond wafer material. That is, the interdigital electrode 2 can also be realized in the substrate body, and the interdigital electrode 2 can be realized in the epitaxial single crystal diamond layer, and can also be applied to various wafer shapes and various metal electrode pad methods. It is only necessary to ensure that the positive and negative electrodes of the interdigital electrode 2 are not in contact with each other, and the interdigital electrodes 2 must be arranged at equal intervals to ensure the uniformity of the electric field. The interdigital electrodes 2 may not be in the same plane.
  • the interdigital electrodes 2 and the columnar metal electrodes 3 have a one-to-one correspondence, and a row of columnar metal electrodes 3 or a group of annular columnar metal electrode arrays must be connected by a pair of interdigital electrodes 2.
  • the array of columnar metal electrodes 3 is a complex array of positive and negative spacings, at least two parallel or two concentric annular arrays to form positive and negative electrodes.
  • the materials of the metal electrode pad 1, the interdigital electrode 2 and the columnar metal electrode 3 are the same or different, but both are A metal that can form an ohmic contact with diamond or a metal that can form a conductive carbide with diamond is required.
  • the metal material must satisfy one of the following two points: 1. It can form an ohmic contact with diamond, such as Pd, Au; 2. It can form conductive carbides with diamond, such as Ti, W. Generally, Pd has good adhesion to diamond, and Ti and diamond tend to form titanium carbide with good electrical conductivity, which is a commonly used metal.
  • the two metal electrodes pad1 may be disposed on the side, the top or the bottom surface of the single crystal diamond wafer material, and the two metal electrodes pad1 may be disposed in a coplanar or different plane. Specifically, the metal electrode pad1 may be located at any position of the single crystal diamond wafer material, disposed on the side surface, the bottom surface or the upper surface and the lower surface, and the position of the metal electrode pad1 is not limited thereto, and the required installation position may be selected according to specific conditions. As long as it can be ensured that the metal electrode pad1 and the interdigital electrode 2 are connected together.
  • the metal electrode pad1 is for connecting the interdigital electrodes 2 belonging to the positive electrode or the negative electrode.
  • connection between the metal electrode pad1 and the interdigital electrode 2 may be directly connected to one end of the interdigital electrode 2 belonging to the positive electrode or the negative electrode, or may be bridged, that is, between adjacent two-finger electrodes of the same positive electrode or negative electrode. In the bridging mode, across the interdigitated electrode strips of different poles, it is necessary to ensure that the positive and negative poles are not connected.
  • a three-dimensional electrode structure of a semiconductor device is a single crystal diamond substrate 5 in which a single crystal diamond epitaxial growth film 6 is rectangularly grown, and two metal electrodes pad1 of a positive electrode and a negative electrode are disposed on the surface of the epitaxial film.
  • the two metal electrode pads 1 are connected to two equally spaced apart and vertically disposed interdigital electrodes 2, and each of the interdigital electrodes 2 is connected to a plurality of mutually parallel and arranged in single crystal gold.
  • the interdigital electrodes 2 are straight-shaped parallel electrodes, and the columnar metal electrodes are vertically disposed.
  • the metal electrode pad1 and the two metal electrode pads 1 are connected to a plurality of equally spaced interdigital electrodes 2, and each of the interdigital electrodes 2 is connected to a plurality of columnar metal electrodes 3 which are parallel to each other and disposed in the single crystal diamond wafer.
  • the interdigital electrodes 2 are straight-shaped parallel electrodes, and the columnar metal electrodes are vertically disposed.
  • a three-dimensional electrode structure of a semiconductor device wherein a single crystal diamond substrate 5 on which a single crystal diamond epitaxial growth film 6 is grown is used as a material, and positive and negative metal electrodes are disposed on the upper surface and the lower surface of the epitaxial film.
  • Pad1 two metal electrode pads1 are connected to two equally spaced interdigital electrodes 2, and each of the interdigital electrodes 2 is connected with a plurality of columnar metal electrodes 3 which are parallel to each other and disposed in the single crystal diamond wafer.
  • a three-dimensional electrode structure of a semiconductor device with a self-supporting single crystal diamond film 4 as a material, a positive electrode and a negative electrode metal electrode pad1 are disposed on the upper surface and the lower surface of the material, and two metal electrodes pad1 are connected to each other.
  • the interdigital electrodes 2 are disposed at equal intervals, and each of the interdigital electrodes 2 is connected to a plurality of columnar metal electrodes 3 which are parallel to each other and disposed in the single crystal diamond wafer.
  • a three-dimensional electrode structure of a semiconductor device with a self-supporting single crystal diamond film 4 as a material, on the opposite sides of the material, a positive electrode and a negative electrode metal electrode pad1 are disposed on opposite sides of the material,
  • the metal electrode pads 1 are connected to two equally spaced interdigital electrodes 2, and the interdigital electrodes 2 are located on the other two opposite surfaces of the self-supporting single crystal diamond film 4, and each of the interdigital electrodes 2 is connected with a plurality of mutual electrodes.
  • Columnar metal electrodes 3 arranged in parallel and in a single crystal diamond wafer.
  • a three-dimensional electrode structure of a semiconductor device is made of a single crystal diamond material 5 on which a single crystal diamond epitaxial growth film 6 is grown, and two positive and negative electrodes are disposed on the surface of the single crystal diamond epitaxial growth film 6.
  • the metal electrode pad1 and the two metal electrode pads 1 are connected to two equally spaced interdigital electrodes 2, and each of the interdigital electrodes 2 is connected with a plurality of columns arranged obliquely and parallel to each other and disposed in the single crystal diamond wafer.
  • Metal electrode 3 is
  • a three-dimensional electrode structure of a semiconductor device is made of a single crystal diamond epitaxial film 6 of a single crystal diamond substrate, and two metal electrodes pad1 and two metal electrodes pad1 of a positive electrode and a negative electrode are disposed on the surface of the wafer.
  • a plurality of annular interdigital electrodes 2 are disposed at equal intervals, and each of the interdigital electrodes 2 is connected to a plurality of columnar metal electrodes 3 which are parallel to each other and disposed in the single crystal diamond wafer.
  • the three-dimensional electrode structure of the above semiconductor device of the present invention is applied to an ultraviolet photodetector and a particle detector using a single crystal diamond wafer as a material.
  • the single crystal diamond wafer is made of a material including a single crystal diamond epitaxial layer including a single crystal diamond substrate and a self-supporting single crystal diamond film.
  • the epitaxial layer is a MPCVD homoepitaxial single crystal diamond film by microwave plasma chemical vapor deposition.
  • the substrate is of the Ib or IIa type of single crystal diamond, and Ib and IIa are type marks of single crystal diamond, depending on the impurity content in the crystal.
  • the present invention also provides a method for preparing a three-dimensional electrode structure of the above semiconductor device, comprising the following steps:
  • Step 1 etching a three-dimensional hole array on the single crystal diamond wafer material by using a diamond etching technique
  • Step 2 filling each of the three-dimensional holes with metal to form a columnar metal electrode 3, and performing annealing treatment;
  • Step 3 Connect the corresponding three-dimensional hole to the metal electrode pad through the interdigital electrode 2.
  • a three-dimensional microchannel array structure is etched by oxygen plasma, and then a resistive evaporation coating technique and a magnetron sputtering coating are employed.
  • the metal or electron beam evaporation coating technique, the molten metal flow backfilling technique, and the molten filling technique after the filling of the nano metal powder fill the small holes and form the columnar metal electrode 3.
  • the metal-to-diamond interface properties are then improved by an annealing process to form a good ohmic contact.
  • the interdigital electrode 2 and the metal electrode pad1 are processed by a standard photolithography process, and the columnar metal electrodes 3 are connected to form a three-dimensional electrode structure of a semiconductor device.
  • a specific method for preparing an epitaxial single crystal diamond wafer is that the single crystal diamond epitaxial layer is grown on a single crystal diamond Ib and IIa substrate by an MPCVD technique.
  • the thickness can be made very thin, about a few hundred nanometers.
  • the thickness of the epitaxial layer needs to be tens of microns or even hundreds of microns. Since the surface of the epitaxial diamond layer which is initially grown is hydrogen termination, it is not suitable for the preparation of the detector. Therefore, the diamond sample needs to be treated, and the hydrogen terminal of the surface can be removed by a typical concentrated acid treatment or ultraviolet light combined with ozone treatment.
  • a specific method for preparing a self-supporting single crystal diamond film wafer is to first grow a thick single crystal diamond film on a single crystal diamond Ib and IIa substrate by a thickness of several hundred micrometers, and then use ion implantation or femtosecond.
  • the laser is stripped off by electrochemical etching to form a self-supporting single crystal diamond film.
  • the surface of the self-supporting single crystal diamond film is flattened. Also, the hydrogen terminal and the non-diamond phase are removed by concentrated acid treatment.
  • the processing of 3D hole arrays requires the use of diamond etching techniques.
  • the etching of diamond is generally etched in an oxygen plasma, and carbon tetrafluoride can be added to the atmosphere to increase the etching rate and smoothness.
  • the etching technique there are RIE etching technology, ICP etching technology, and the like.
  • oxygen plasma is taken as an example.
  • a circular array pattern is formed by photolithography, the mask is a photoresist, and then a three-dimensional channel array is etched in an oxygen plasma environment by an RIE technique, and the etching power is 100W-300W.
  • the oxygen flow rate is 30-60 sccm and the pressure is 4-10 Pa.
  • the etching time By controlling the etching time, small holes of different depths can be etched.
  • the penetration depth of the small holes may be three in the epitaxial layer, through the epitaxial layer into the substrate, and through the substrate.
  • self-supporting single crystal diamond films there are two types of self-supporting diamond films and self-supporting diamond films.
  • Fig. 8(a) and Fig. 8(b) are schematic views of a three-dimensional aperture array method.
  • Fig. 9(a) is a small hole located in the epitaxial layer
  • Fig. 9(b) is a small hole penetrating into the substrate
  • Fig. 9(c) is a through hole
  • Fig. 9(d) is small Top view of the array of holes.
  • the metal filling may be carried out by evaporation coating or by sputtering, or by a molten metal filling and a powder filling.
  • FIG. 10 shows the electrode filling and joining process for the evaporation coating.
  • Fig. 10(a) is a schematic view showing the deposition of a metal thin film
  • Fig. 10(b) is a schematic view showing the removal of the photoresist
  • Fig. 10(c) is a schematic view showing the connection of the surface electrodes.
  • the melt filling method after filling with a molten metal stream and powder filling is to separate the metal filling and the interdigitated electrode.
  • molten metal flow after etching the array of small holes, place In a vacuum environment, molten metal is directly applied to the entire surface of the diamond to fill the pores.
  • the nano metal particles are first filled into small holes, and then heated to melt the metal particles to form a molten metal flow to achieve filling.
  • the top ends of the metal columnar electrodes are in the same plane as the diamond surface, independent of each other, which requires the preparation of the interdigital electrodes to connect them.
  • the preparation of the interdigital electrode is similar to that in the evaporation coating method.
  • FIG. 11 shows the electrode filling and joining process for molten metal backfilling.
  • the electrodes may also be connected by using the opposite-sided interdigital electrodes.
  • Fig. 11(a) is a schematic view showing the filling of the molten metal flow
  • Fig. 11(b) is a schematic view showing the mask removal and planarization treatment
  • Fig. 11(c) is a schematic view showing the preparation of the surface metal thin film
  • Fig. 11(d) is a schematic view. The schematic of the mask electrode formation is removed.
  • metal to diamond contact is typically ohmic contact.
  • ohmic contact In order to form a good ohmic contact, there are two methods.
  • the first is to select a metal with a small difference between the work function and the diamond, such as Au and Pd. After the metal is filled, the device is annealed to improve the contact performance between the metal and the diamond.
  • the second is the use of metals to form carbides with C, such as Ti.
  • the metal is a nano metal particle, and includes nano copper, nano tin, nano carbon, and the like.
  • the device is still annealed to form titanium carbide at the interface between Ti and C, thereby achieving ohmic contact.
  • the substrate is made of Ib single crystal diamond made by high temperature and high pressure method and has a size of 3 ⁇ 3 ⁇ 0.3 mm.
  • a single crystal diamond film having a thickness of 1 ⁇ m was epitaxially grown on the substrate by an MPCVD method.
  • Epitaxy The layer was subjected to CL, Raman test and optical microscope surface observation.
  • the CL spectrum showed obvious peaks around 235 nm and no other stray peaks.
  • the Raman half-height width was about 2/cm, and the surface was flat, indicating the quality of single crystal diamond film. high.
  • a circular aperture array is formed on the surface of the diamond by photolithography, and the mask directly utilizes the photoresist, and no additional metal is used as a mask.
  • the circular hole has a diameter of 10 ⁇ m and a hole center pitch of 40 ⁇ m.
  • the lithographic diamond sample is placed in a reactive ion etching machine and etched using an oxygen plasma. The oxygen flow rate was 40 sccm, the etching power was 200 W, and the etching time was 3 min. After the etching is completed, the photoresist is removed. The depth test for the small holes was 120 nm.
  • the interdigital electrode has a finger width of 20 ⁇ m, a finger pitch of 20 ⁇ m, and a finger length of 600 ⁇ m.
  • the interdigitated electrode strip covers all the small holes.
  • the metal is plated by electron beam evaporation, which is Ti/Al/Ni/Au, and the thickness of each layer is 20 nm, 160 nm, 120 nm, and 120 nm, respectively. After the evaporation is completed, the photoresist is removed and the surface electrode structure is intact.
  • the sample is annealed to form an ohmic contact. Annealing in an Ar gas atmosphere at 600 ° C for 30 min. After natural cooling, the sample was subjected to a voltage-current characteristic test, and the obtained characteristics were ohmic contact characteristics.
  • the three-dimensional columnar body electrode structure can combine the advantages of high sensitivity of the coplanar interdigital electrode structure and uniform electric field uniformity of the vertical electrode structure.
  • the surface electric field which is originally uneven can be uniformly propelled into the body to realize lateral collection of carriers.
  • the electrode pitch can be made smaller to resemble a vertical structure.
  • ultraviolet light is incident on the diamond path, the photogenerated electron-hole pairs can be quickly collected by the internal electrodes, and more electron-hole pairs are collected, which can improve the responsiveness and response time of the detector.
  • a three-dimensional array of holes is etched by plasma etching, and then metal backfilling is used, and the interdigital electrodes are connected to each other to prepare a comparison. Good three-dimensional columnar metal electrode structure.
  • Radiation impedance is an important parameter of particle detectors. Although diamond has excellent anti-irradiation properties, when applied to particle detectors, the collection efficiency will also decrease due to the existence of radiation damage and polarization over time. Therefore, a three-dimensional electrode structure can be employed, the carrier collection path can be shortened, and the control ability of the electric field to the device can be increased, thereby improving the performance of the device.
  • the particle beam injection method is partially doped in the electrode to achieve electrical conductivity, but it is difficult to achieve high doping of diamond, and the cost is high, and the doping atom also destroys the diamond lattice. In the high-energy particle detector, the electrode will affected.
  • the lattice constant of graphite and diamond differs greatly, and stress is generated at the interface between the two, which also affects device performance. Therefore, plasma selective etching of small holes and metal backfilling to form metal columnar electrodes, and then annealing to improve the contact characteristics of metal and diamond, is a better electrode fabrication method.

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Abstract

一种半导体器件的三维电极结构，包括单晶金刚石晶片材料，单晶金刚石晶片材料上设置有分别作为正极和负极的两个金属电极pad（1），各个金属电极pad（1）均连接一个或多个等距间隔设置的叉指电极（2），各叉指电极（2）上均连接有一个或多个相互平行、且设置在单晶金刚石晶片材料内的柱状金属电极（3）。还公开了一种半导体器件的三维电极结构的制备方法及其应用，结合平面电极结构和垂直电极结构的优点，在单晶金刚石晶片内引入体电极，实现紫外光或者粒子束激发的电子-空穴对的高效快速收集，提高探测器的响应时间和灵敏度；同时可以避开单晶金刚石晶片表面的复杂性，增加了器件的稳定性；且提高了粒子探测器的抗辐照性能。

Description

一种半导体器件的三维电极结构及其制备方法和应用 技术领域
本发明属于光电探测技术领域，涉及一种半导体器件的三维电极结构及其制备方法和应用。
背景技术
紫外光电探测技术是一种十分重要的技术，可广泛应用于空间火焰检测、烟雾报警、空间通信等领域。由于工作环境复杂恶劣，因此对探测器的材料要求很高。金刚石作为一种宽禁带半导体，截止波长在225纳米，具有天然的可见光滤光性，十分适合制备日盲紫外探测器。同时，金刚石具有很多优异的性能，其热导率高，热稳定性好，化学稳定性好，具有良好的抗辐照性能。这些都使得金刚石在紫外探测器领域具有巨大的优势。
目前有许多人对金刚石紫外光电探测器做了研究。但是，传统金刚石紫外光电探测器电极结构主要是共平面叉指电极结构和垂直三明治结构。对垂直结构来说，电场均匀性好，有利于光生载流子的漂移运动，使得灵敏度和收集效率较高。由于紫外光在金刚石材料中穿透深度有限，于是需要金刚石薄膜做到很薄，并且成核面缺陷密度尽可能少，这样，光生电子-空穴对在电极间的漂移过程中才会尽可能少地复合，从而使得到达电极处的载流子多，对电荷收集效率和灵敏度贡献大。但是，对于金刚石外延薄膜和自支撑单晶金刚石膜，整体厚度较厚，对载流子的漂移和收集不利。
共平面叉指电极结构是对垂直三明治结构的改进。由于紫外光在金刚石膜中穿透深度比较小，主要集中于表面，因此在金刚石表面上制备叉指电极， 可以较好地收集表面附近的光生电子-空穴对。由于紫外光在材料中衰减迅速，穿透一定深度后，对电流的贡献很小，因此叉指电极的收集效率也是比较高的。并且叉指电极相互交错，使得探测器有效探测面积增大，对探测器的响应度有很大的贡献。但是，叉指电极的电场均匀性不如垂直结构，在紫外光功率较大时，电场分布的不均匀将会对光生电子-空穴对的收集产生影响。
粒子探测技术在核技术领域也是非常重要的技术。金刚石具有良好的抗辐照性能，在辐照下仍能保持器件的正常运行。金刚石也具有很高的热导率，将高能粒子实验中的热量及时有效地传到出去。同时，金刚石的介电系数小，在辐照下，器件的噪声电流不会变化，从而使得器件具有很高的分辨力，而这正是粒子探测器所需要的。
由于粒子的能量很高，与金刚石的相互作用要比紫外光的作用强烈，所以金刚石粒子探测器的结构是垂直电极结构，也就是三明治结构。早期的金刚石粒子探测器是以多晶金刚石薄膜为材料，属于硅上的异质外延，金刚石与硅的分离十分简单，采用三明治结构基本是在均匀的金刚石薄膜中。尽管如此，受到多晶金刚石晶界、缺陷等的影响，该结构存在着载流子的收集时间长和收集效率低等问题。
随着CVD单晶金刚石外延生长技术的突破，对金刚石粒子探测器的研究转向了单晶金刚石膜上，既有应用于包含单晶金刚石衬底的单晶金刚石外延生长层，也有应用于自支撑单晶金刚石膜。此时，存在着和金刚石紫外光电探测器相同的问题。金刚石粒子探测器采用三明治结构时，存在有效探测面积少、载流子漂移路径长和收集效率低等问题。采用共平面结构时，由于高能粒子的能量高，穿透深度大，电场的不均匀分布对器件性能影响也大。
发明内容
本发明的目的是提供一种半导体器件的三维电极结构，以解决采用垂直三明治电极结构时有效探测面积小、载流子收集时间长和收集效率低，采用共平面叉指电极结构时电场均匀性不佳的问题。
本发明半导体器件的三维电极结构，包括单晶金刚石晶片材料，单晶金刚石晶片材料上设置有分别作为正极和负极的两个金属电极pad，各个金属电极pad均连接一个或多个等距间隔设置的叉指电极，各叉指电极上均连接有一个或多个相互平行、且设置在单晶金刚石晶片材料内的柱状金属电极。
进一步的，柱状金属电极贯穿单晶金刚石晶片材料设置、或仅延伸一定深度设置。
进一步的，柱状金属电极为竖直设置或者倾斜设置。
进一步的，各叉指电极为平行电极或环形电极，且各叉指电极位于单晶金刚石晶片材料的表面或者内部。
进一步的，金属电极pad和叉指电极之间为桥接方式或者直接覆盖式连接。
进一步的，金属电极pad、叉指电极和柱状金属电极的材质相同或不同，但均要求为能与金刚石形成欧姆接触的金属或者能与金刚石形成导电碳化物的金属。
进一步的，单晶金刚石晶片材料为自支撑单晶金刚石膜，或者包含单晶金刚石衬底的单晶金刚石外延层。
进一步的，单晶金刚石晶片材料的形状为矩形、圆形、椭圆形或者其他形状，两个金属电极pad设置在单晶金刚石晶片材料的侧面、顶面或底面、且两个金属电极pad之间为共面或异面设置。
进一步的，各柱状金属电极与单晶金刚石晶片材料之间通过退火形成欧姆接触。
本发明上述半导体器件的三维电极结构适用于金刚石紫外光电探测器或者粒子探测器。
本发明上述半导体器件的三维电极结构的制备方法，包括以下步骤：
步骤1、采用金刚石刻蚀技术在单晶金刚石晶片材料上刻蚀三维孔阵列；
步骤2、用金属填充各个三维孔形成柱状金属电极，进行退火处理；
步骤3、再将对应的三维孔通过叉指电极与金属电极pad连接。
本发明的有益效果是，结合平面电极结构和垂直电极结构的优点，在自支撑单晶金刚石膜，或者包含单晶金刚石晶片衬底的单晶金刚石外延层内引入体电极，实现紫外光或者粒子束激发的电子-空穴对的高效、快速收集，从而提高探测器的响应时间和灵敏度。同时，采用体电极结构，可以避开单晶金刚石晶片表面的复杂性，可以增加器件的稳定性。并且，对粒子探测器来说，还能够提高抗辐照性能。
附图说明
图1是本发明一种半导体器件的三维电极结构材料为单晶金刚石衬底与其外延生长薄膜的结构示意图；
图2是本发明一种半导体器件的三维电极结构衬底为自支撑式单晶金刚石膜的结构示意图；
图3是图1中金属电极pad为异面设置的结构示意图；
图4是图2中金属电极pad为异面设置的结构示意图；
图5是图2中金属电极pad设置在侧面的结构示意图；
图6是图1中柱状金属电极倾斜设置的结构示意图；
图7是本发明叉指电极为环形的结构示意图；
图8(a)和图8(b)是本发明一种半导体器件的三维电极结构制备方法中三维孔阵列方法的示意图；
图9(a)至图9(d)是本发明一种半导体器件的三维电极结构制备方法中三种三维孔穿入深度的示意图；
图10(a)至图10(c)是本发明一种半导体器件的三维电极结构制备方法中蒸发镀膜金属填充与表面电极形成的示意图；
图11(a)至图11(d)是本发明一种半导体器件的三维电极结构制备方法中熔融金属流填充与表面电极形成的示意图。
图中，1.金属电极pad，2.叉指电极，3.柱状金属电极，4.自支撑式单晶金刚石膜，5.单晶金刚石衬底，6.单晶金刚石外延生长薄膜，7.填充金属，8.熔融金属流，9.氧等离子体，10.掩膜。
具体实施方式
下面结合附图和具体实施方式对本发明进行详细说明。
本发明提供了一种半导体器件的三维电极结构，包括单晶金刚石晶片材料，单晶金刚石晶片材料上设置有分别作为正极和负极的两个金属电极pad1，各个金属电极pad1均连接一个或多个等距间隔设置的叉指电极2，各叉指电极2上均连接有一个或多个相互平行、且设置在单晶金刚石晶片材料内的柱状金属电极3，各柱状金属电极3与单晶金刚石晶片材料之间通过退火形成欧姆接触。
本发明在单晶金刚石晶片材料上，通过等离子体刻蚀技术，加工出三维平行孔阵列，然后利用金属填充孔阵列，形成三维体电极。在单晶金刚石晶片表面或者体内，用叉指电极将这些三维体电极相互连接，构成一种半导体 器件的三维电极结构。
单晶金刚石晶片材料为自支撑单晶金刚石膜，或者包含单晶金刚石衬底的单晶金刚石外延薄膜。单晶金刚石晶片材料的形状为矩形、圆形、椭圆形或者其他形状。
其中，柱状金属电极3贯穿单晶金刚石晶片材料设置、或仅延伸一定深度设置。柱状金属电极3的位置，可以仅在外延层内，或延伸到衬底中，还可以贯穿衬底。同样的，也可以在自支撑金刚石膜内，也可以贯穿自支撑金刚石膜。
柱状金属电极3为竖直设置或者倾斜设置，柱状金属电极3不仅限于垂直单晶金刚石晶片材料表面，也可以是与单晶金刚石晶片材料表面形成一定的角度倾斜设置，但要满足柱状金属电极3之间相互平行。柱状金属电极3的形状可以是圆柱、方柱等任意形状。
叉指电极2为平行电极或者环形电极；并且各叉指电极2位于单晶金刚石晶片材料的表面或者内部。即叉指电极2还可以做到衬底体内，叉指电极2可以在外延单晶金刚石层内实现，也能应用于多种晶片形状、多种金属电极pad方式。只需保证叉指电极2的正负极之间不接触，且叉指电极2之间必须等间距设置，以保证电场的均匀性。叉指电极2之间可以不在同一个平面内。
叉指电极2与柱状金属电极3是一一对应的关系，一排柱状金属电极3或者一组环形排列的柱状金属电极阵列，必须用一条叉指电极2连接。柱状金属电极3阵列是正负相互间隔的复式阵列，数量至少为两个平行或者两个同心圆环阵列，以形成正负极。
金属电极pad1、叉指电极2和柱状金属电极3的材质相同或不同，但均 要求为能与金刚石形成欧姆接触的金属或者能与金刚石形成导电碳化物的金属。具体的，该金属材质必须满足以下两个条之一：1、能与金刚石形成欧姆接触，如Pd，Au；2、能与金刚石形成导电碳化物，如Ti，W。一般来说，Pd与金刚石黏附性好，Ti与金刚石易形成良好导电能力的钛化碳，为比较常用的金属。
两个金属电极pad1可以设置在单晶金刚石晶片材料的侧面、顶面或底面、且两个金属电极pad1之间可以为共面或异面设置。具体的，金属电极pad1可以位于单晶金刚石晶片材料的任何位置，在侧面、底面或者结合上表面和下表面布置等，金属电极pad1的位置并不仅限于此，可以根据具体情况选择需要的设置位置，只要能够保证将金属电极pad1与叉指电极2连接在一起就行。金属电极pad1是为了将同属于正极或者负极的叉指电极2连接，一般有两个即可，分正、负极，但是其形状、位置无固定，可以有多种形式，例如圆形、矩形、多边形等，可以在上下表面，也可以在侧面，还可以上下表面与侧面结合。
金属电极pad1与叉指电极2的连接可以是将同属于正极或者负极的叉指电极2的一端直接覆盖连接在一起，也可以是桥接，即同属正极或者负极的相邻两指电极之间采用桥接方式，跨过不同极的叉指电极条，需要保证正负极之间不接通。
实施例1
如图1，一种半导体器件的三维电极结构，以矩形生长有单晶金刚石外延生长薄膜6的单晶金刚石衬底5为材料，在该外延薄膜表面上设置正极和负极的两个金属电极pad1，两个金属电极pad1均连接两个等距间隔竖直设置的叉指电极2，各叉指电极2上均连接有多个相互平行、且设置在单晶金 刚石晶片内的柱状金属电极3。叉指电极2为直条形状平行电极，柱状金属电极为竖直设置。
实施例2
如图2，一种半导体器件的三维电极结构，以矩形自支撑单晶金刚石膜4为单晶金刚石晶片材料，在该自支撑单晶金刚石膜4同一表面上设置分别作为正极和负极的两个金属电极pad1，两个金属电极pad1均连接多个等距间隔设置的叉指电极2，各叉指电极2上均连接有多个相互平行、且设置在单晶金刚石晶片内的柱状金属电极3。叉指电极2为直条形状平行电极，柱状金属电极为竖直设置。
实施例3
如图3，一种半导体器件的三维电极结构，以生长有单晶金刚石外延生长薄膜6的单晶金刚石衬底5为材料，在该外延薄膜上表面和下表面异面设置正极和负极金属电极pad1，两个金属电极pad1均连接两个等距间隔设置的叉指电极2，各叉指电极2上均连接有多个相互平行、且设置在单晶金刚石晶片内的柱状金属电极3。
实施例4
如图4，一种半导体器件的三维电极结构，以自支撑单晶金刚石膜4为材料，在该材料上表面和下表面异面设置正极和负极金属电极pad1，两个金属电极pad1均连接两个等距间隔设置的叉指电极2，各叉指电极2上均连接有多个相互平行、且设置在单晶金刚石晶片内的柱状金属电极3。
实施例5
如图5，一种半导体器件的三维电极结构，以自支撑单晶金刚石膜4为材料，在该材料的相对两个侧面上异面设置正极和负极金属电极pad1，两 个金属电极pad1均连接两个等距间隔设置的叉指电极2，叉指电极2位于自支撑单晶金刚石膜4的另外两个相对表面上，各叉指电极2上均连接有多个相互平行、且设置在单晶金刚石晶片内的柱状金属电极3。
实施例6
如图6，一种半导体器件的三维电极结构，以生长有单晶金刚石外延生长薄膜6的单晶金刚石材料5为材料，在该单晶金刚石外延生长薄膜6表面上设置正极和负极的两个金属电极pad1，两个金属电极pad1均连接两个等距间隔设置的叉指电极2，各叉指电极2上均连接有多个倾斜设置、相互平行、且设置在单晶金刚石晶片内的柱状金属电极3。
实施例7
如图7，一种半导体器件的三维电极结构，以单晶金刚石衬底的单晶金刚石外延薄膜6为材料，在该晶片表面上设置正极和负极的两个金属电极pad1，两个金属电极pad1均连接多个等距间隔设置的环形叉指电极2，各叉指电极2上均连接有多个相互平行、且设置在单晶金刚石晶片内的柱状金属电极3。
本发明上述半导体器件的三维电极结构应用于以单晶金刚石晶片为材料的紫外光电探测器和粒子探测器上。其中，单晶金刚石晶片为材料包括包含单晶金刚石衬底的单晶金刚石外延层和自支撑单晶金刚石膜。外延层为利用微波等离子体化学气相沉积MPCVD同质外延单晶金刚石薄膜，衬底是单晶金刚石的Ⅰb或者Ⅱa类型，Ib和IIa是单晶金刚石的类型标记，取决于晶体内杂质含量。
本发明还提供了上述半导体器件的三维电极结构的制备方法，包括以下步骤：
步骤1、采用金刚石刻蚀技术在单晶金刚石晶片材料上刻蚀三维孔阵列；
步骤2、用金属填充各个三维孔形成柱状金属电极3，进行退火处理；
步骤3、再将对应的三维孔通过叉指电极2与金属电极pad连接。
在单晶金刚石晶片即包含单晶金刚石衬底的单晶金刚石外延层或者自支撑金刚石膜上，通过氧等离子体刻蚀出三维微通道阵列结构，然后采用电阻蒸发镀膜技术、磁控溅射镀膜技术或者电子束蒸发镀膜技术、熔融金属流回填技术、以及纳米金属粉末填充后的熔融填充技术等，将金属填满小孔，并形成柱状金属电极3。然后通过退火工艺，改善金属与金刚石界面性能，形成良好的欧姆接触。采用标准光刻工艺，加工出叉指电极2和金属电极pad1，将柱状金属电极3连接，形成一种半导体器件的三维电极结构。
一、制备单晶金刚石晶片材料
制备外延单晶金刚石晶片的具体方法为，单晶金刚石外延层是通过MPCVD技术，在单晶金刚石Ⅰb和Ⅱa衬底上生长得到的。对于紫外光电探测器，厚度可以做到很薄，约几百纳米。对于粒子探测器，外延层的厚度需要几十微米，甚至几百微米。由于初生长好的外延金刚石层表面是氢终端，不适合制备探测器，因此需要对金刚石样品进行处理，采用典型的浓酸处理或者紫外光结合臭氧的处理方法都能去除掉表面的氢终端。
制备自支撑单晶金刚石膜晶片的具体方法为，通过MPCVD技术，先在单晶金刚石Ⅰb和Ⅱa衬底上生长一层单晶金刚石厚膜，厚度为数百微米，然后采用离子注入或者飞秒激光加上电化学腐蚀方法剥离下来，形成自支撑单晶金刚石膜。经过研磨，使该自支撑单晶金刚石膜表面平整。并且也通过浓酸处理，去除氢终端和非金刚石相。
二、三维孔阵列的形成
三维孔阵列的加工需要用到金刚石的刻蚀技术。金刚石的刻蚀一般是在氧等离子体中刻蚀，并可以在气氛中添入四氟化碳，提高刻蚀速率和光滑度。关于该刻蚀技术，有RIE刻蚀技术，ICP刻蚀技术等。这里以氧等离子体为例。在单晶金刚石晶片上，利用光刻技术形成圆形阵列图案，掩膜为光刻胶，然后用RIE技术，在氧等离子体环境下刻蚀出三维通道阵列，刻蚀功率为100W-300W，氧气流量30-60sccm，压强为4-10Pa。通过控制刻蚀时间，可以刻蚀出不同深度的小孔。仅对单晶金刚石外延层来说，小孔的穿入深度可以是在外延层中、穿透外延层到衬底中和贯穿衬底三种。对于自支撑单晶金刚石膜，则包含自支撑金刚石膜内和贯穿自支撑金刚石膜两种。
加工示意图如图8所示，小孔在外延层中穿入深度如图9所示。图8中，图8(a)和图8(b)是三维孔阵列方法的示意图。图9中，图9(a)是位于外延层内的小孔，图9(b)是穿透到衬底内的小孔，图9(c)是通孔，图9(d)是小孔阵列的俯视图。
三、金属填充和电极连接
金属填充可以直接采用蒸发镀膜的方式或者溅射镀膜的方式，或者利用熔融金属流填充以及粉末填充后的熔融填充方法。
利用蒸发镀膜的方式，是同时完成金属填充和电极连接的方式。在刻蚀出小孔阵列后，去掉光刻胶，然后通过套刻，形成连接小孔的叉指电极图案。接着蒸镀上金属，既能填充小孔，又能完成叉指连接电极的制备。图10展示了蒸发镀膜的电极填充和连接过程。图10中，图10(a)是金属薄膜淀积示意图，图10(b)是去除光刻胶示意图，图10(c)是表面电极连接示意图。
利用熔融金属流填充以及粉末填充后的熔融填充法则是将金属填充和叉指连接电极分开制作。对于熔融金属流来说，在刻蚀出小孔阵列后，放在 真空环境中，直接将熔融金属流敷于整个金刚石表面，实现小孔的填充。对于粉末填充后熔融填充法，则是先将纳米金属颗粒填充到小孔中，然后加热，使金属颗粒熔化，形成熔融金属流，实现填充。填充结束之后，金属柱状电极的顶端与金刚石表面是处于同一个平面的，相互之间独立，这就需要再制备叉指电极将其连接。叉指电极的制备就与蒸发镀膜方式中类似，光刻出图形，蒸发上金属，再去掉光刻胶，电极就制备完成。图11展示了熔融金属回填法的电极填充和连接过程。当小孔贯穿金刚石衬底时，电极的连接还可以采用异面叉指电极来连接。图11中，图11(a)是熔融金属流填充示意图，图11(b)是去掉掩膜并平坦化处理的示意图，图11(c)是表面金属薄膜制备示意图，图11(d)是去掉掩膜电极成型的示意图。
四、金属－金刚石界面退火
对于金刚石紫外光电探测器和粒子探测器来说，金属与金刚石接触一般采用的是欧姆接触。为了形成良好的欧姆接触，有两种方法。
第一种是选择功函数与金刚石差距较小的金属，比如Au和Pd，完成金属的填充后，对器件进行退火处理，改善金属与金刚石的接触性能。
第二种是利用金属与C形成碳化物，如Ti。在熔融金属流和粉末填充后的熔融填充法中，金属为纳米金属颗粒，包含纳米铜、纳米锡和纳米碳等。完成金属填充后，仍是对器件进行退火处理，使得Ti与C界面形成碳化钛，从而实现欧姆接触。
实施例8
将一种半导体器件的三维电极结构应用在探测器中：
衬底选用高温高压法制成的Ib单晶金刚石，尺寸为3×3×0.3mm。通过MPCVD法，在衬底上外延生长一层厚度为1μm的单晶金刚石薄膜。对外延 层进行CL、拉曼测试和光学显微镜表面观察，CL谱显示在235纳米附近有明显峰值且无其他杂散峰，拉曼半高宽为2/cm左右，表面平整，表示单晶金刚石薄膜质量高。
在外延层生长结束后，通过光刻技术，在金刚石表面形成圆孔阵列，掩膜直接利用光刻胶，不再额外的用金属做掩膜。圆孔宽直径为10μm，孔中心间距为40μm。将光刻好的金刚石样品置于反应离子刻蚀机中，利用氧等离子体刻蚀。氧气流量为40sccm，刻蚀功率为200W，刻蚀时间为3min。刻蚀结束后，去掉光刻胶。对小孔的深度测试为120nm。
接下来，去掉光刻胶，再次利用光刻技术，重新在金刚石表面形成叉指电极图案。叉指电极指宽为20μm，指间距为20μm，指长为600μm，叉指电极条覆盖所有的小孔。采用电子束蒸发的方式镀金属，分别为Ti/Al/Ni/Au，各层厚度分别为20nm、160nm、120nm、120nm。蒸镀结束后，去除光刻胶，表面电极结构完整。
最后，对样品进行退火以形成欧姆接触。在Ar气气氛、600℃条件下退火30min。自然冷却后，对样品进行电压-电流特性测试，所得特性为欧姆接触特性。
采用三维柱状体电极结构可以结合共平面叉指电极结构灵敏度高和垂直电极结构电场均匀性好的优点。在单晶金刚石膜体内引入电场，可以将原本不均匀的表面电场向体内均匀推进，实现载流子的侧向收集。此时，可以将电极间距做得比较小，从而类似于垂直结构。紫外光入射到金刚石的路径中，光生电子-空穴对可以迅速被体内电极收集，并且收集到的电子-空穴对较多，可以提高探测器的响应度和响应时间。利用等离子体刻蚀技术刻蚀出三维孔阵列，再利用金属回填，并采用叉指电极相互连接，可以制备出比较 好的三维柱状金属电极结构。
辐射阻抗是粒子探测器的一个重要参数。金刚石虽然有优异的抗辐照性能，但是应用于粒子探测器时，随着时间的延长，由于辐照损伤和极化等现象的存在，还是会使得收集效率也会下降。因此，可以采用三维电极结构，缩短载流子收集路径，增大电场对器件的控制能力，从而改善器件的性能。
对于柱状金属电极的制作，可以有粒子束注入、激光加工等方式。粒子束注入方式是在电极部分掺杂，实现导电能力，但是金刚石很难实现高掺杂，并且成本很高，加之掺杂原子也会破坏金刚石晶格，在高能粒子探测器中，其电极会受到影响。对于激光加工来说，是将电极部分变成石墨后，石墨与金刚石的晶格常数相差较大，在两者的界面处会产生应力，这对器件性能也会有影响。因此，采用等离子选择性刻蚀出小孔，并利用金属回填，形成金属柱状电极，然后退火改善金属与金刚石的接触特性，是一种比较好的电极制作方式。

Claims (11)

  1. 一种半导体器件的三维电极结构，其特征在于，包括单晶金刚石晶片材料，所述单晶金刚石晶片材料上设置有分别作为正极和负极的两个金属电极pad(1)，所述的各个金属电极pad(1)均连接一个或多个等距间隔设置的叉指电极(2)，所述各叉指电极(2)上均连接有一个或多个相互平行、且设置在所述单晶金刚石晶片材料内的柱状金属电极(3)。
  2. 如权利要求1所述的一种半导体器件的三维电极结构，其特征在于，所述柱状金属电极(3)贯穿所述单晶金刚石晶片材料设置、或仅延伸一定深度设置。
  3. 如权利要求1或2所述的一种半导体器件的三维电极结构，其特征在于，所述柱状金属电极(3)为竖直设置或者倾斜设置。
  4. 如权利要求1或2所述的一种半导体器件的三维电极结构，其特征在于，所述各叉指电极(2)为平行电极或环形电极，且所述各叉指电极(2)位于所述单晶金刚石晶片材料的表面或者内部。
  5. 如权利要求4所述的一种半导体器件的三维电极结构，其特征在于，所述金属电极pad(1)和叉指电极(2)之间为桥接方式或者直接覆盖式连接。
  6. 如权利要求1或2所述的一种半导体器件的三维电极结构，其特征在于，所述金属电极pad(1)、叉指电极(2)和柱状金属电极(3)的材质相同或不同，但均要求为能与金刚石形成欧姆接触的金属或者能与金刚石形成导电碳化物的金属。
  7. 如权利要求1或2所述的一种半导体器件的三维电极结构，其特征在于，所述单晶金刚石晶片材料为自支撑单晶金刚石膜，或者包含单晶金刚石 晶片衬底的单晶金刚石外延层。
  8. 如权利要求1或2所述的一种半导体器件的三维电极结构，其特征在于，所述单晶金刚石晶片材料的横截面为矩形、圆形、椭圆形或者其他形状，所述两个金属电极pad(1)设置在所述单晶金刚石晶片材料的侧面、顶面或底面、且两个金属电极pad(1)之间为共面或异面设置。
  9. 如权利要求1或2所述的一种半导体器件的三维电极结构，其特征在于，所述各柱状金属电极(3)与单晶金刚石晶片材料之间通过退火形成欧姆接触。
  10. 如权利要求1至9中任意一项所述的一种半导体器件的三维电极结构，其特征在于，适用于金刚石紫外光电探测器或者粒子探测器。
  11. 如权利要求1至10中任意一项所述的一种半导体器件的三维电极结构的制备方法，其特征在于，包括以下步骤：
    步骤1、采用金刚石刻蚀技术在单晶金刚石晶片材料上刻蚀三维孔阵列；
    步骤2、用金属填充所述各个三维孔形成柱状金属电极(3)，进行退火处理；
    步骤3、再将对应的三维孔通过叉指电极(2)与金属电极pad(1)连接。
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CN109994454B (zh) * 2019-04-01 2023-10-24 李正 六边形盒状三维探测器及其制备方法
CN112909155A (zh) * 2021-01-20 2021-06-04 中国科学院工程热物理研究所 一种直接测量微纳材料热电优值的探测器及制备工艺
CN114063140A (zh) * 2021-11-16 2022-02-18 郑州工程技术学院 一种消除极化效应的金刚石中子探测器的制备方法
CN114063140B (zh) * 2021-11-16 2023-12-05 郑州工程技术学院 一种消除极化效应的金刚石中子探测器的制备方法
CN117245238A (zh) * 2023-09-21 2023-12-19 哈尔滨工业大学 金刚石微流道加工方法

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