Single-sided minimum coherence full-penetration three-dimensional winding type groove electrode detector

Abstract

The invention discloses a single-sided minimum coherence full-penetration three-dimensional winding type trench electrode detector, which comprises a silicon substrate, and the silicon substrate is of a cuboid structure. The center of the silicon substrate is provided with a central anode, and the periphery of the silicon substrate is provided with a trench cathode; a cathode aluminum electrode contact layer covers the outer side surface of the upper part of the trench cathode; an anode aluminum electrode contact layer covers the outer side surface of the upper part of the central anode; except a groove cathode etching area, a cathode aluminum electrode contact layer and an anode aluminum electrode contact layer covering area, the upper surface of the silicon substrate is covered with an upper surface SiO2 layer. The lower surface of the silicon substrate is covered with a lower surface SiO2 layer except a groove cathode etching area and a central anode area which is not covered with the anode aluminum electrode contact layer. The problems that polycrystalline silicon filling is complex, the double-face etching difficulty is large, and a single-face structure is prone to falling off are solved, cost is reduced by simplifying manufacturing, dead zones are reduced through self-supporting design, and the charge collection efficiency and the response speed are improved by optimizing an electric field through the fully-penetrating electrodes.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon detectors and relates to a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector. Background Art

[0002] In 1997, Parker et al. developed a detector with a three-dimensional electrode structure, which was etched and doped with N along the thickness of the detector. + and P + The complete depletion voltage depends only on the N + and P + The electrode spacing of the column is insensitive to the detector thickness. With the further development of HL-LHC technology, some variants have been proposed, such as single-type column (3D-STC), single-sided 3D detector, double-sided dual-type column detector, hybrid pixel detector, three-dimensional SINTE active edge silicon detector, and small-pitch 3D pixel detector. In 2020, a three-dimensional microstrip detector was characterized, with a neutron irradiation flux of up to 3×1017 n eq / cm 2 .

[0003] In 2009, Brookhaven National Laboratory in the United States proposed the concept of a three-dimensional trench electrode silicon detector. The trench-shaped peripheral electrodes address the low electric field problem existing between columnar electrodes, isolate the cells, and provide a more uniform internal electric field distribution. Chinese scientists and research institutions have actively participated in the research and development of silicon detectors. Institutions such as the Institute of High Energy Physics of the Chinese Academy of Sciences, Peking University, and Tsinghua University have made significant contributions to the research and application of silicon detectors. Currently, researchers are developing a new generation of high-performance silicon detectors that require higher spatial resolution, faster temporal response, and enhanced radiation hardness. Silicon detectors are primarily used in high-energy physics, astrophysics, nuclear medicine, X-ray imaging, national defense, and industry, and are of great value in many fields, including high-energy particle detection. Therefore, researching and developing detectors with even higher performance is a critical task in current scientific research.

[0004] Compared to two-dimensional silicon detector structures, three-dimensional silicon detector electrodes are embedded within the silicon substrate. This means that the full depletion voltage no longer depends on the thickness of the silicon body, but only on the distance between the electrodes. Traditional three-dimensional trench electrode detectors achieve improved electric field distribution and charge collection efficiency by embedding the electrodes within the silicon substrate. However, this requires ensuring that the detector body does not detach from the substrate during the etching process. After etching, due to the thin thickness of the silicon substrate, the trench electrodes cannot completely penetrate the entire silicon substrate and can only be etched to approximately 90% of the substrate depth. In addition, the double-sided etching process requires photolithography, etching, and polysilicon filling operations on both the front and back sides of the silicon substrate to form the through-hole trench electrodes. Although this design can partially address the high depletion voltage and uneven electric field distribution caused by the thickness limitations of the silicon wafer in two-dimensional detectors, its manufacturing process is complex and costly. First, the double-sided photolithography process requires extremely high alignment accuracy. Any slight misalignment will cause the trench electrodes to shift position, resulting in electric field distortion and reduced charge collection efficiency. Actual production data shows that the yield of double-sided lithography is typically less than 70%, significantly increasing manufacturing costs. Secondly, after double-sided etching, the trench structure needs to be reinforced with polysilicon filling to prevent the silicon substrate from falling off due to insufficient mechanical strength. However, polysilicon filling not only increases material costs but also introduces additional thermal stress, potentially causing interface defects between the silicon substrate and the filling material, affecting the long-term stability of the detector. Summary of the Invention

[0005] In order to achieve the above objectives, the present invention provides a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector, which solves the problems of high complexity of polysilicon filling, difficult double-sided etching process and easy falling off of single-sided etching structure in the prior art.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector, including a silicon substrate, which is a rectangular structure; a central anode is arranged in the center of the silicon substrate, and a groove cathode is arranged on the periphery of the silicon substrate; the upper outer surface of the groove cathode is covered with a cathode aluminum electrode contact layer; the upper outer surface of the central anode is covered with an anode aluminum electrode contact layer; the upper surface of the silicon substrate is covered with an upper surface SiO2 layer except for the groove cathode etched area, the cathode aluminum electrode contact layer and the anode aluminum electrode contact layer covered area; the lower surface of the silicon substrate is covered with a lower surface SiO2 layer except for the groove cathode etched area and the central anode area not covered with the anode aluminum electrode contact layer.

[0007] Furthermore, the length, width and height of the silicon substrate are all set to be 50 μm to 300 μm.

[0008] Furthermore, the silicon substrate has a length of 115 μm, a width of 115 μm, and a height of 100 μm.

[0009] Furthermore, the interior of the silicon substrate is lightly N-type doped.

[0010] Furthermore, the doping concentration of the N-type lightly doped silicon substrate is 4×10 11 / cm 3 ~ 2×10 12 / cm 3 .

[0011] Furthermore, a P-type heavily doped layer is provided on the outer surface of the silicon substrate.

[0012] Furthermore, the doping concentration of the silicon substrate P-type heavily doped layer is 1×10 18 / cm 3 ~ 2×10 20 / cm 3 , the thickness of P-type heavy doping is 0.2μm to 2μm.

[0013] Furthermore, the diameter of the central anode is in the range of 5-20 μm; and the central anode is heavily doped with N-type; the width of the trench cathode is in the range of 2-10 μm; and the trench cathode is heavily doped with P-type.

[0014] Furthermore, the doping concentration of the central anode N-type heavy doping is 1×10 18 / cm 3 ~ 2×10 20 / cm 3 The doping concentration of the P-type heavy doping of the trench cathode is in the range of 1×10 18 / cm 3 ~ 2×10 20 / cm 3 .

[0015] Furthermore, the width of the isolation groove between adjacent detector units is 2μm to 10μm, and adjacent detector units share the isolation groove; the spacing between the grooves inside a single detector unit is 2μm to 10μm; the thickness of the upper surface SiO2 layer and the lower surface SiO2 layer are both 1μm; the thickness of the cathode aluminum electrode contact layer and the anode aluminum electrode contact layer are both 1μm.

[0016] The beneficial effects of the present invention are: 1. The present invention's single-sided minimum coherence, full-through, three-dimensional, wound trench electrode detector utilizes a single-sided process, eliminating the need for double-sided etching and polysilicon filling. This significantly simplifies the manufacturing process and reduces manufacturing costs. Compared to double-sided structures, it offers greater process compatibility, making it particularly suitable for large-scale array production. It also avoids the alignment errors associated with double-sided photolithography, improving process stability and yield.

[0017] 2. This invention utilizes single-sided etching combined with a self-supporting silicon substrate design. The detector maintains structural stability during the etching process without the need for external filler materials, significantly reducing dead zones. Adjacent cells are naturally connected through the silicon substrate, ensuring mechanical strength while achieving good isolation between cells and significantly improving charge collection efficiency.

[0018] 3. The fully penetrating electrodes of this invention ensure a more uniform electric field distribution within the detector, further reducing the full depletion voltage, lowering energy consumption, and accelerating response speed. Simulation results demonstrate efficient charge collection at low operating voltages, with superior sensitivity and position resolution compared to conventional three-dimensional trench electrode detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a structural diagram of the single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector unit of the present invention.

[0021] Figure 2 This is a top view of a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector unit.

[0022] Figure 3 It is a cross-sectional view along the X-axis of a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector unit.

[0023] Figure 4 It is a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector array.

[0024] Figure 5 It is a mask pattern for a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector array.

[0025] Figure 6 It is the electron concentration curve of a unit cell in the X-axis cross section of a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector.

[0026] Figure 7 yes Figure 6 A local enlarged view shows that the depletion voltage of the detector is 1.6V.

[0027] Figure 8This is a simulation diagram of the electric field of a unit cell along the X-axis of a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector at a voltage of 1.6V.

[0028] Figure 9 This is a potential simulation diagram of a unit cell along the X-axis of a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector at a voltage of 1.6V.

[0029] Figure 10 This is a simulation diagram of the electron concentration of a unit cell along the X-axis of a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector at a voltage of 1.6V.

[0030] Figure 11 It is the specific gravity field distribution of the single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector.

[0031] Figure 12 This is the potential distribution diagram between the two electrodes of the traditional three-dimensional columnar electrode silicon detector.

[0032] Figure 13 This is a structural diagram of a traditional three-dimensional cylindrical electrode detector.

[0033] Figure 14 This is a diagram of the structure of a traditional three-dimensional trench electrode silicon detector.

[0034] In the figure, 1. silicon substrate, 2. cathode aluminum electrode contact layer, 3. upper surface SiO2 layer, 4. anode aluminum electrode contact layer, 5. central anode, 6. groove cathode, 7. lower surface SiO2 layer. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] A single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector unit structure, such as Figure 1-Figure 3 shown.

[0037] In this embodiment, each detector unit includes a silicon substrate 1; the silicon substrate 1 is a rectangular parallelepiped structure, and its length, width, and height are set within the range of 50 μm to 300 μm; the exemplary dimensions here are 115 μm (length) × 115 μm (width) × 100 μm (height). When the dimensions are scaled proportionally, the scaling ratio is 0.5 to 3 times based on the exemplary dimensions; the interior of the silicon substrate 1 is lightly N-type doped, with a doping concentration of 4×10 11 / cm 3 ~ 2×10 12 / cm 3 , the preferred doping concentration is 1×10 12 / cm 3 The central anode 5 is set in the center of the silicon substrate 1, and the diameter of the central anode 5 is in the range of 5-20μm; the central anode 5 is N-type heavily doped 5, and the doping concentration is 1×10 18 / cm 3 ~ 2×10 20 / cm 3 , the preferred doping concentration is 1×10 19 / cm 3 The outer surface of the silicon substrate 1 is provided with a P-type heavily doped layer with a doping concentration of 1×10 18 / cm 3 ~ 2×10 20 / cm3, and the thickness of P-type heavy doping is 0.2μm to 2μm.

[0038] Excessively high N-type doping concentrations can damage the lattice structure of the silicon substrate 1 and introduce excessive lattice defects, thereby reducing the material's stability and reliability. Excessive impurities and defects can act as charge traps or scattering centers, increasing detector noise and reducing the signal-to-noise ratio. Excessively high free electron concentrations in the N-type material can increase the electron-hole recombination rate, affecting the detector's response speed and sensitivity. Excessively low N-type doping concentrations can lead to insufficient conductivity in the silicon substrate 1 and excessively low free electron concentrations, affecting charge transfer efficiency and the detector's response speed. During detection, excessively low electron concentrations can cause charge to accumulate near the anode, preventing timely transfer to the cathode and reducing detector performance.

[0039] In each detector unit, a trench cathode 6 is provided on the periphery of the silicon substrate 1; the width of the trench cathode 6 is 2-10 μm; the trench cathode 6 is heavily doped with P-type, and the doping concentration range is 1×10 18 / cm 3 ~ 2×10 20 / cm 3 , the preferred doping concentration is 1×10 19 / cm 3 ; The width of the isolation trench between adjacent detector units is 2-10μm, the minimum lower limit of the width is determined by the limit of the lithography process, and the upper limit is constrained by the total size of the unit, and the isolation trenches are shared between adjacent units; the groove spacing inside the unit is 2-10μm, the minimum lower limit of the spacing is determined by the limit of the lithography process, and the upper limit is constrained by the total size of the unit.

[0040] Excessively high P-type doping concentrations can damage the lattice structure of the silicon substrate 1 and introduce excessive lattice defects, thereby reducing the material's stability and reliability. Due to the excessively high doping concentration, the hole concentration in the P-type material can also be excessively high, potentially increasing leakage current and impacting detector performance. Excessive impurities and defects can act as charge traps or scattering centers, increasing detector noise and reducing the signal-to-noise ratio. Excessively low P-type doping concentrations can lead to insufficient conductivity in the silicon substrate 1 and excessively low hole concentrations, impacting charge transfer efficiency and the detector's response speed. During detection, excessively low hole concentrations can cause charge to accumulate near the cathode, preventing it from being transferred to the anode in a timely manner, thus reducing detector performance.

[0041] The upper outer surface of the groove cathode 6 is covered with the cathode aluminum electrode contact layer 2, and the upper outer surface of the central anode 5 is covered with the anode aluminum electrode contact layer 4; the upper surface of the silicon substrate 1 is covered with the upper surface SiO2 layer 3 except for the groove cathode 6 etched area, the cathode aluminum electrode contact layer 2 and the anode aluminum electrode contact layer 4 covered area; the lower surface of the silicon substrate 1 is covered with the lower surface SiO2 layer 7 except for the groove cathode 6 etched area and the central anode 5 area not covered with the anode aluminum electrode contact layer 4; the thickness of the upper surface SiO2 layer 3 and the lower surface SiO2 layer 7 are both 1μm; the thickness of the cathode aluminum electrode contact layer 2 and the anode aluminum electrode contact layer 4 are both 1μm.

[0042] The fully penetrating trench electrode surrounds the central electrode, making the detector's potential and electric field distribution more uniform. This helps form a uniform electric field distribution within the detector, improving the detector's sensitivity to particles or photons, further accurately determining the position of incident particles or photons, and improving the detector's position resolution. Adjacent detector units can share the same wrapped trench electrode, significantly reducing dead zones and significantly improving detector performance.

[0043] The top view of the detector array of the present invention is as follows Figure 4 As described above, it shows the situation of connecting the units before and after mirroring to form an array. The units are closely connected to each other, which ensures the stability of the silicon substrate 1 during the full etching process of the detector and reduces the dead zone. Traditional three-dimensional detector electrodes have no penetration and have dead zones. Compared with two-dimensional silicon detectors, three-dimensional silicon detectors have advantages in electrode spacing, radiation resistance, response speed, noise control and resolution. This application proposes a single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector with high detection efficiency, high sensitivity and good radiation resistance.

[0044] Figure 5 The three-layer pattern of the detector array mask is shown, marked in red, green and blue respectively: the red layer is P +The ion implantation area, the green layer is the etched groove and central pillar hole area, and the blue layer is the aluminum photolithography area. The three together present the detector unit layout and isolation structure.

[0045] Figure 6 In the figure, the applied bias voltage is 0.6 V-2.0 V. It can be seen that the electron concentration of the detector of the present invention decreases with the increase of the applied bias voltage. When the bias voltage increases to 1.6 V, the sensitive region of the detector reaches a fully depleted state, and its electron concentration no longer changes with the increase of the applied bias voltage. Therefore, the fully depleted voltage of this detector unit is 1.6 V. As the bias voltage continues to increase, the electron concentration in the depletion region becomes lower and lower, which indicates that the detector has reached a fully depleted state.

[0046] Figure 7 yes Figure 6 A partial enlarged view of the Figure 6 It can be seen that the depletion voltage of the detector is 1.6 V. This shows that as the bias voltage increases, the electron concentration in the depletion region continues to decrease. When it increases to 1.6 V, the electron concentration in 99% of the depletion region of the detector is lower than the matrix concentration, which indicates that the detector has reached a basic depletion state.

[0047] The depletion voltage formula of the 3D detector is as follows:

[0048] in, The effective doping concentration of silicon-based lightly doped ; is the charge of each electron, ; is the electrode spacing ; is the dielectric constant of vacuum, ; is the relative dielectric constant of silicon, ; is the built-in potential of the silicon-based PN junction, In this three-dimensional trench electrode detector structure, the full depletion voltage is low. Cannot be ignored and must be included in the calculation. If the full depletion voltage is much higher than When , ignore Contribution; The PN junction potential barrier of silicon material is about 0.75 V. The theoretical value of the depletion voltage of the detector is obtained by the depletion voltage formula. , which is consistent with Figure 6 , Figure 7 The depletion voltage of 1.6 V obtained in the simulation results is very close.

[0049] Figure 8 、 Figure 9The electric field and potential distribution inside the detector unit of a single-sided minimum coherence fully penetrating three-dimensional winding groove electrode at a voltage of 1.6 V. The fully penetrating three-dimensional winding groove electrode solves the low electric field problem between traditional columnar electrodes and isolates the detector units from each other, making the internal electric field and potential distribution more uniform, which helps electrons to be collected and transmitted more efficiently inside the detector.

[0050] Figure 10 This simulated plot shows the electron concentration of a detector cell along the X-axis at a voltage of 1.6V. This plot demonstrates that the electron concentration within the detector remains uniform during operation, indicating stable operation, which is crucial for detector performance and reliability, especially in applications requiring long-term stable operation. Furthermore, a uniform electron concentration distribution generally improves detector sensitivity and response speed.

[0051] Figure 11 It is the specific gravity field distribution inside the single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector. The simulation results show that the weighted field between adjacent units is almost negligible, which indicates that the mutual interference between units is extremely small and the coherence between adjacent units is very weak.

[0052] Figure 13 This is a diagram of the structure of a traditional three-dimensional columnar electrode detector. For a traditional three-dimensional columnar electrode detector, the structure embeds heavily doped P-type and N-type electrodes into the silicon substrate 1. The electrodes are symmetrically distributed, which causes the electric field potential distribution between the two electrodes to be saddle-shaped. In addition, in the center part between the two electrodes, no matter how large the bias voltage is, there will be a dead zone (such as Figure 12 As shown in the figure, there is also the problem of excessively high electric fields near the junction electrodes.

[0053] Figure 14 This is a diagram of the structure of a traditional 3D trench electrode silicon detector. While traditional 3D trench electrode silicon detectors have trench electrodes, they retain a certain thickness at the bottom of the detector as a substrate. While these detectors perform better than 3D columnar electrode detectors, they can improve the saddle-shaped distribution of electric fields and potentials. However, the presence of the substrate results in uneven distribution of electric fields and potentials at the bottom of the detector. Therefore, the single-sided minimum coherence, full-through, 3D winding trench electrode detector of the present invention outperforms traditional detectors.

[0054] Each embodiment in this specification is described in a related manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector, comprising a silicon substrate (1), characterized in that: The silicon substrate (1) is a rectangular parallelepiped structure; a central anode (5) is provided at the center of the silicon substrate (1), and a groove cathode (6) is provided on the periphery of the silicon substrate (1); the outer surface of the upper portion of the groove cathode (6) is covered with a cathode aluminum electrode contact layer (2); the outer surface of the upper portion of the central anode (5) is covered with an anode aluminum electrode contact layer (4); the upper surface of the silicon substrate (1) is covered with an upper surface SiO2 layer (3) except for the groove cathode (6) etched area, the cathode aluminum electrode contact layer (2) and the anode aluminum electrode contact layer (4) covered area; the lower surface of the silicon substrate (1) is covered with a lower surface SiO2 layer (7) except for the groove cathode (6) etched area and the central anode (5) area not covered with the anode aluminum electrode contact layer (4).

2. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 1, characterized in that: The length, width and height of the silicon substrate (1) are all set to be between 50 μm and 300 μm.

3. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 2, characterized in that: The silicon substrate (1) has a length of 115 μm, a width of 115 μm, and a height of 100 μm.

4. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 1, characterized in that: The interior of the silicon substrate (1) is lightly N-type doped.

5. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 4, characterized in that: The silicon substrate (1) has an N-type lightly doped doping concentration of 4×10 11 / cm 3 ~ 2×10 12 / cm 3 .

6. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 1, characterized in that: A P-type heavily doped layer is provided on the outer surface of the silicon substrate (1).

7. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 6, characterized in that: The doping concentration of the P-type heavily doped layer of the silicon substrate (1) is 1×10 18 / cm 3 ~ 2×10 20 / cm 3 , the thickness of P-type heavy doping is 0.2μm to 2μm.

8. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 1, characterized in that: The diameter of the central anode (5) is in the range of 5-20 μm; and the central anode (5) is heavily N-type doped; the width of the trench cathode (6) is in the range of 2-10 μm; and the trench cathode (6) is heavily P-type doped.

9. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 8, characterized in that: The central anode (5) is heavily N-type doped with a doping concentration of 1×10 18 / cm 3 ~ 2×10 20 / cm 3 The doping concentration range of the P-type heavy doping of the trench cathode (6) is 1×10 18 / cm 3 ~ 2×10 20 / cm 3 .

10. The single-sided minimum coherence full-penetration three-dimensional winding groove electrode detector according to claim 1, characterized in that: The width of the isolation grooves between adjacent detector units is 2 μm to 10 μm, and the adjacent detector units share the isolation grooves; the spacing between the grooves inside a single detector unit is 2 μm to 10 μm; the thickness of the upper surface SiO2 layer (3) and the lower surface SiO2 layer (7) are both 1 μm; the thickness of the cathode aluminum electrode contact layer (2) and the anode aluminum electrode contact layer (4) are both 1 μm.

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