A three-dimensional epitaxial implanted hexagonal electrode silicon detector

Abstract

The present invention discloses a three-dimensional epitaxially implanted hexagonal electrode silicon detector, comprising a silicon detector array composed of a plurality of silicon detector units, wherein the silicon detector unit comprises an N-type lightly doped silicon substrate, a cathode aluminum electrode contact layer, a cathode aluminum electrode contact layer, an upper surface SiO2, an N-type heavily doped anode and a P-type heavily doped cathode, wherein the N-type lightly doped silicon substrate is first grown by an epitaxial process, and then a P-type heavily doped cathode is doped by ion implantation, and the process is repeated 30 times, wherein the outer side of the P-type heavily doped cathode is covered with a cathode aluminum electrode contact layer, and the top of the N-type lightly doped silicon substrate is embedded with an N-type heavily doped anode. The detector array of the present invention adds an anode at the lower connection of the unit, thereby avoiding the existence of a dead zone in terms of structural design, and thus has a more uniform potential and electric field distribution, a higher charge collection rate, and a more stable performance of the detector.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor detectors, and in particular to a three-dimensional epitaxially implanted hexagonal electrode silicon detector. Background Art

[0002] Semiconductor detectors are solid-state radiation detectors. The most commonly used semiconductor materials are silicon and germanium. Silicon detectors are radiation detectors that use silicon as the detection medium. They have the characteristics of high sensitivity, small size, and easy integration. They are widely used due to their strong practicality and mature technology. They have gradually developed into the most mature radiation detectors and are widely used in many fields such as medical treatment, military, aerospace, and high-energy physics experiments.

[0003] Since the silicon detector was first proposed, it can be roughly divided into two categories based on the process methods: 1. Two-dimensional silicon detectors based on two-dimensional planar technology, whose electrodes are generally located on the surface of the detector, represented by silicon microstrips, silicon pixel detectors and silicon drift detectors (SDD). 2. Three-dimensional silicon detectors based on three-dimensional deep etching, ion implantation and other processes, whose electrodes extend from the surface of the detector to the inside of the substrate, represented by three-dimensional columnar electrode silicon detectors and three-dimensional trench electrode silicon detectors. The three-dimensional epitaxial implanted hexagonal electrode silicon detector is a silicon detector with a more uniform electric field, smaller leakage current and higher energy resolution based on the three-dimensional trench silicon detector.

[0004] The basic principle of the three-dimensional epitaxial injection hexagonal electrode silicon detector can be simplified as a PN junction or a PIN junction. The interaction between the silicon detector and the incident particles is the basis for the operation of the silicon detector. The energy carried by the incident particles is transmitted to the electrons at the top of the full band in the medium, so that the electrons gain energy and break free from the constraints of the nucleus, cross the forbidden band and jump to the conduction band to form electron-hole pairs. Under the action of appropriate reverse bias, the silicon detector can be completely exhausted, the built-in electric field in the detector increases, and the free carriers in the matrix drift toward the electrode under the action of the electric field and are collected by the electrode, thereby generating a response current. At the same time, the signal pulse generated in the detector is output through the peripheral electronic readout device, thereby obtaining data information related to the incident particles.

[0005] The three-dimensional epitaxial implanted hexagonal electrode silicon detector mainly adopts epitaxy and ion implantation process, by epitaxially growing the upper silicon substrate on the lower substrate, and then doping by ion implantation process, using different doping positions at different levels during doping, repeating the above steps, and generating a metal layer on the heavily doped outer side of the top and bottom of the entire silicon body, and an oxide layer on the lightly doped outer side, and then through the steps of slicing, wiring, packaging, etc., the production of the three-dimensional epitaxial implanted hexagonal electrode silicon detector can be completed. Due to the epitaxy and ion implantation process of the three-dimensional epitaxial implanted hexagonal electrode silicon detector, compared with the three-dimensional trench electrode silicon detector, the electrode spacing is more uniform, so the potential distribution and electric field distribution are also more uniform.

[0006] The weak electric field area or zero electric field area in the detector is called the "dead zone". When the detector is working, a large number of electron-hole pairs will be generated when particles enter the dead zone. Because the electric field in the dead zone is extremely weak, the electron-hole pairs cannot drift to the electrode in time to be collected. They can only be collected in time after they diffuse to the working area of ​​the detector with a stronger electric field. Therefore, the existence of the dead zone greatly increases the charge collection rate and response speed of the detector, and the dead zone has a very negative impact on the working performance of the detector.

[0007] Due to process limitations, traditional three-dimensional trench electrode silicon detectors need to retain about 10% of the substrate during etching to prevent the silicon body in the middle of the three-dimensional trench electrode silicon detector from falling off the wafer due to lack of support. The etching process that does not penetrate the entire silicon body is very difficult during the manufacturing process, and the electric field strength in the unetched area is extremely low, resulting in a large dead zone. In addition, when the three-dimensional trench electrode silicon detector is arranged in an array, the bottom substrates of each unit are interconnected, so the electrical signals between units will interfere with each other, greatly affecting the performance of the detector.

[0008] The proposal of a perfect spherical three-dimensional detector is too idealistic. Although its internal electric field is very uniform, it is a hypothetical model and is only in the theoretical stage. Summary of the invention

[0009] 1. Technical problems to be solved

[0010] The purpose of the present invention is to solve the problems in the prior art that the dead zone of traditional silicon detectors accounts for too large a proportion and the perfect spherical electrode is too idealized and cannot be realized in the process. On the basis of the existing process, a three-dimensional epitaxially implanted hexagonal electrode silicon detector is proposed to eliminate the dead zone and improve the detector performance.

[0011] 2. Technical solution

[0012] In order to achieve the above object, the present invention adopts the following technical solutions:

[0013] A three-dimensional epitaxially implanted hexagonal electrode silicon detector comprises a silicon detector array composed of a plurality of silicon detector units, wherein the silicon detector unit comprises an N-type lightly doped silicon substrate, a cathode aluminum electrode contact layer, a cathode aluminum electrode contact layer, an upper surface SiO2, an N-type heavily doped anode and a P-type heavily doped cathode. The N-type lightly doped silicon substrate is first grown by an epitaxial process, and then a P-type heavily doped cathode is doped by ion implantation, and the process is repeated 30 times, the outer side of the P-type heavily doped cathode is covered with a cathode aluminum electrode contact layer, an N-type heavily doped anode is embedded on the top of the N-type lightly doped silicon substrate, the upper side of the N-type lightly doped silicon substrate is covered with an upper surface SiO2, and the outer side of the N-type heavily doped anode is covered with an anode aluminum electrode contact layer.

[0014] Preferably, the cathode aluminum electrode contact layer includes an upper surface cathode aluminum electrode contact layer and a lower surface cathode aluminum electrode contact layer.

[0015] Preferably, the N-type heavily doped anode in the silicon detector array includes an upper surface N-type heavily doped anode and a lower surface N-type heavily doped anode.

[0016] Preferably, the anode aluminum electrode contact layer in the silicon detector array comprises an upper surface anode aluminum electrode contact layer and a lower surface anode aluminum electrode contact layer.

[0017] Preferably, the exterior of the lower surface anode aluminum electrode contact layer is covered with a lower surface SiO2 anode protection ring.

[0018] Preferably, the exterior of the lower surface N-type heavily doped anode is covered with a lower surface N-type lightly doped anode protection ring.

[0019] Preferably, the bottom of the N-type lightly doped silicon substrate is covered with a lower surface P-type heavily doped cathode.

[0020] Preferably, the doping concentration of the P-type heavily doped cathode is 1×10 18 / cm 3 The doping concentration of the N-type lightly doped silicon substrate is 1×10 12 / cm 3 .

[0021] Preferably, the doping concentration of the N-type heavily doped anode is 1×10 18 / cm 3 .

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] 1. In the present invention, the detector is a hexagonal design, and can also be a circular or square design. The square design is simpler to arrange, but the distance between the hexagonal anode and cathode is more uniform and more symmetrical; compared with the array composed of circular units, the array composed of hexagonal units can achieve a tight connection without gaps;

[0025] 2. Compared with the three-dimensional groove detector, this detector array adds an anode at the connection point on the lower side of the unit, avoiding the existence of dead zone from the structural design, so it has a more uniform potential and electric field distribution, a higher charge collection rate, a larger sensitive area, better unit independence, less mutual influence between units, while retaining the advantage of greatly reducing dead zone, and the performance of the detector is more stable;

[0026] 3. Compared with the two-dimensional detector, the depletion voltage of this detector is no longer limited by the thickness of the detector silicon wafer, but only related to the electrode spacing;

[0027] 4. Compared with the spherical three-dimensional detector, this detector can realize a hemispherical heavily doped cathode in a lightly doped silicon substrate by combining epitaxy and ion implantation based on the existing process, making the electric field distribution more uniform;

[0028] 5. Compared with the three-dimensional groove detector, the depletion voltage of this detector is smaller. In the absence of irradiation, the depletion voltage of the detector unit is only 2.7V, with lower energy consumption and stronger radiation resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a cross-sectional view along the X-axis of a three-dimensional epitaxial implanted hexagonal electrode silicon detector unit.

[0030] Figure 2 It is the overall structural diagram of the three-dimensional epitaxial implanted hexagonal electrode silicon detector unit.

[0031] Figure 3 is a three-dimensional perspective view of a three-dimensional epitaxially implanted hexagonal electrode silicon detector unit.

[0032] Figure 4 This is a top surface structural diagram of a three-dimensional epitaxially implanted hexagonal electrode silicon detector array.

[0033] Figure 5 This is a bottom structural diagram of a three-dimensional epitaxially implanted hexagonal electrode silicon detector array.

[0034] Figure 6 A 3D perspective view of a 3D epitaxially implanted hexagonal electrode silicon detector array.

[0035] Figure 7 It is a cross-sectional view along the X-axis of a three-dimensional epitaxially implanted hexagonal electrode silicon detector array.

[0036] Figure 8 It is a cross-sectional view along the Y axis of a three-dimensional epitaxially implanted hexagonal electrode silicon detector array.

[0037] Fig. 9 This is a perspective view of the three-dimensional structure of a three-dimensional epitaxial implanted hexagonal electrode silicon detector array.

[0038] Fig.10 This is the electron concentration diagram of a three-dimensional epitaxially implanted hexagonal electrode silicon detector unit under different reverse bias voltages.

[0039] Fig.11 yes Fig.10 A partial enlarged view of .

[0040] Fig.12This is a simulation diagram of the electric field distribution of a three-dimensional epitaxially implanted hexagonal electrode silicon detector unit under depletion voltage.

[0041] Fig.13 This is a simulation diagram of the potential distribution of a three-dimensional epitaxially implanted hexagonal electrode silicon detector unit under depletion voltage.

[0042] Fig.14 This is a simulation diagram of the electron concentration distribution of a three-dimensional epitaxially implanted hexagonal electrode silicon detector unit under depletion voltage.

[0043] In the figure, 1: upper surface anode aluminum electrode contact layer; 2: upper surface SiO2; 3: upper surface cathode aluminum electrode contact layer; 4: P-type heavily doped cathode; 5: N-type lightly doped silicon substrate; 6: upper surface N-type heavily doped anode; 7: lower surface SiO2 anode protection ring; 8: lower surface anode aluminum electrode contact layer; 9: lower surface cathode aluminum electrode contact layer; 10: lower surface N-type lightly doped anode protection ring; 11: lower surface N-type heavily doped anode; 12: lower surface P-type heavily doped cathode. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0045] Embodiment 1:

[0046] Reference Figure 1-14 A three-dimensional epitaxial implanted hexagonal electrode silicon detector includes a silicon detector array composed of multiple silicon detector units, wherein the silicon detector unit includes an N-type lightly doped silicon substrate 5, a cathode aluminum electrode contact layer, a cathode aluminum electrode contact layer, an upper surface SiO22, an N-type heavily doped anode and a P-type heavily doped cathode 4. The N-type lightly doped silicon substrate 5 is first grown by an epitaxial process, and then the P-type heavily doped cathode 4 is doped by ion implantation, and the process is repeated 30 times. The outer side of the P-type heavily doped cathode 4 is covered with a cathode aluminum electrode contact layer, an N-type heavily doped anode is embedded on the top of the N-type lightly doped silicon substrate 5, the upper surface SiO22 is covered on the top of the N-type lightly doped silicon substrate 5, and the outer side of the N-type heavily doped anode is covered with an anode aluminum electrode contact layer.

[0047] In the present invention, the cathode aluminum electrode contact layer includes an upper surface cathode aluminum electrode contact layer 3 and a lower surface cathode aluminum electrode contact layer 9, the N-type heavily doped anode in the silicon detector array includes an upper surface N-type heavily doped anode 6 and a lower surface N-type heavily doped anode 11, and the anode aluminum electrode contact layer in the silicon detector array includes an upper surface anode aluminum electrode contact layer 1 and a lower surface anode aluminum electrode contact layer 8.

[0048] In the present invention, the upper surface of the N-type lightly doped silicon substrate 5 is covered with an upper surface SiO2, the outer surface of the lower surface anode aluminum electrode contact layer 8 is covered with a lower surface SiO2 anode protection ring 7, the outer surface of the lower surface N-type heavily doped anode 11 is covered with a lower surface N-type lightly doped anode protection ring 10, and the bottom of the N-type lightly doped silicon substrate 5 is covered with a lower surface P-type heavily doped cathode 12, and the doping concentration of the P-type heavily doped cathode 4 is 1×10 18 / cm 3 , the doping concentration of the N-type lightly doped silicon substrate 5 is 1×10 12 / cm 3 , the N-type heavily doped anode doping concentration is 1×10 18 / cm 3 .

[0049] In the present invention, the entire silicon body is 60 μm thick and is composed of 30 layers of 2 μm thick silicon thin layers. The 2 μm silicon thin layers are first grown into a silicon substrate by an epitaxial process and then doped by ion implantation. The specific doping position and width can be calculated by the following formula.

[0050] In the present invention, the cathode aluminum electrode contact layer is covered on the outside of the P-type heavily doped cathode, the anode aluminum electrode contact layer is covered on the outside of the N-type heavily doped anode, and the SiO2 is covered on the outside of the N-type lightly doped silicon substrate to prevent the silicon substrate from being oxidized in the air. The thickness of the aluminum electrode contact layer on the upper and lower surfaces of the silicon detector is 1 μm, and the thickness of the SiO2 layer on the upper and lower surfaces is 0.5 μm.

[0051] In the present invention, the lower silicon body width of the silicon detector unit is 120 μm, the upper silicon body width is 124 μm, and there are 2 μm more P-type heavily doped cathode regions on the left and right sides, which will be shared with adjacent units when forming an array, such as Figure 6 shown.

[0052] In the present invention, the specific structure of the three-dimensional epitaxial implanted hexagonal electrode silicon detector unit and array can be calculated by the following formula:

[0053] Given d=R,Epi-Si thicknessΔd,Number of layers N=R / Δd

[0054] y i =iΔd(i=1,....,N)

[0055]

[0056]

[0057] SinceΔx N =0, we can let Δx N =ΔxN-1 .

[0058] If Δx N-1 is too small, we can let Δx N-1 =Δx N-2 ,and so on,until we find a large enoughΔx N-m

[0059] Where d is the thickness of the silicon body of the detector, R is the radius of the hexagonal circumscribed circle of the detector unit, Δd is the thickness of each layer of epitaxially grown silicon substrate, N is the number of epitaxial layers of the silicon body, and y is i is the distance between the upper surface of the i-th silicon substrate and the bottom surface of the silicon substrate, x i is the distance from the center of the hexagonal P-type heavily doped region in the i-th silicon substrate to the center of the silicon substrate, Δx i is the horizontal width of the hexagonal P-type heavily doped silicon substrate in the i-th layer. Due to design requirements and process limitations, when Δx i When Δx is less than 4μm, i =4μm.

[0060] In the present invention, the shape, number of layers, doping concentration and other data of the silicon detector structure are all variable. The embodiments of this article are based on cases where R = 60 μm and Δd = 2 μm. The light doping and heavy doping concentrations in the examples can be adjusted as needed.

[0061] In the present invention, the array of three-dimensional epitaxially implanted hexagonal electrode silicon detectors adds an anode at the junction of the bottom units, and adds an N-type lightly doped anode protection ring area between the anode and the cathode to avoid direct contact between the anode and the heavily doped cathode area. The three-dimensional trench electrode silicon detector array avoids the existence of dead zones in design, increases the sensitive area of ​​the detector, and greatly optimizes the performance of the silicon detector.

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A three-dimensional epitaxial implanted hexagonal electrode silicon detector, comprising a silicon detector array composed of a plurality of silicon detector units, characterized in that: The silicon detector unit comprises an N-type lightly doped silicon substrate (5) and a P-type heavily doped cathode (4) ， The N-type lightly doped silicon substrate (5) covers the inside and outside of the P-type heavily doped cathode (4); the outside of the P-type heavily doped cathode (4) is covered with a cathode aluminum electrode contact layer; an N-type heavily doped anode is embedded on the top of the N-type lightly doped silicon substrate (5); the outside of the N-type heavily doped anode is covered with an anode aluminum electrode contact layer; the cathode aluminum electrode contact layer includes an upper surface cathode aluminum electrode contact layer (3) and a lower surface cathode aluminum electrode contact layer (9); the N-type heavily doped anode in the silicon detector array includes an upper surface N-type heavily doped anode The silicon detector array comprises an upper surface anode (6) and a lower surface N-type heavily doped anode (11), the anode aluminum electrode contact layer in the silicon detector array comprises an upper surface anode aluminum electrode contact layer (1) and a lower surface anode aluminum electrode contact layer (8), the upper surface SiO2 (2) is covered on the N-type lightly doped silicon substrate (5), the outer portion of the lower surface anode aluminum electrode contact layer (8) is covered with a lower surface SiO2 anode protection ring (7), and the outer portion of the lower surface N-type heavily doped anode (11) is covered with a lower surface N-type lightly doped anode protection ring (10).

2. A three-dimensional epitaxial implanted hexagonal electrode silicon detector according to claim 1, characterized in that: The bottom of the N-type lightly doped silicon substrate (5) is covered with a lower surface P-type heavily doped cathode (12).

3. The three-dimensional epitaxial implanted hexagonal electrode silicon detector according to claim 1, characterized in that: The doping concentration of the P-type heavily doped cathode (4) is 1×10 18 / cm 3 The doping concentration of the N-type lightly doped silicon substrate (5) is 1×10 12 / cm 3 .

4. The three-dimensional epitaxial implanted hexagonal electrode silicon detector according to claim 1, characterized in that: The doping concentration of the N-type heavily doped anode is 1×10 18 / cm 3 .

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