Through-type three-dimensional quasi-hemispherical electrode detector based on SOI substrate
Through the design of the through-type three-dimensional quasi-hemispherical electrode detector based on SOI substrate, the problems of low electric field and zero electric field regions in the three-dimensional detector are solved, and more efficient charge collection and larger effective volume are achieved, reducing energy consumption and crosstalk.
Patent Information
- Application Number
- CN202422085017.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-27
- Publication Date
- 2025-07-11
- Estimated Expiration
- 2034-08-27
AI Technical Summary
The existing three-dimensional detectors have low electric field areas and zero electric field areas in unetched areas, resulting in reduced effective volume of the detector and reduced charge collection performance.
A through-type three-dimensional quasi-spherical electrode detector based on SOI substrate is designed as a cube structure. The central anode covers the anode aluminum electrode contact layer, and a trench wall is formed between the four sides of the substrate and the adjacent substrate. The cathode is composed of a heavily doped layer and a trench wall of the SOI substrate, combining a simple etching and ion implantation process.
The uniform distribution of electric field is achieved, the zero electric field area is avoided, the effective volume of the detector is increased, the charge collection performance is improved, the leakage current and energy consumption is reduced, and the crosstalk effect is reduced.
Smart Images
Figure CN223094119U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of silicon detectors, and relates to a through-type three-dimensional quasi-hemispherical electrode detector based on an SOI substrate. Background Art
[0002] Silicon detectors are widely used in aerospace, medical, industrial flaw detection, safety detection, nuclear radiation monitoring, and large scientific device research and development due to their excellent performance and mature manufacturing processes. Its basic principle is to use particles or other radiation to generate electron-hole pairs in the silicon matrix, and the generated electron-hole pairs drift under the action of an external electric field to excite electrical signals. Internationally, the manufacturing technology of silicon semiconductor detectors has been quite mature. The manufacturing processes mainly include ion implantation, chemical vapor deposition (CVD), physical vapor deposition (PVD), magnetron sputtering, electron beam evaporation, and lithography. In terms of subsequent processes, foreign countries have also formed relatively mature process flows, such as chemical cleaning, annealing, and encapsulation. These processes can make silicon semiconductor detectors have better stability and reliability.
[0003] Compared with two-dimensional planar detectors, three-dimensional detectors have obvious advantages in information acquisition, spatial positioning, depth perception, visualization and analysis capabilities, and automation efficiency, which has led to their wide application and promotion in many fields. First, in terms of charge collection performance, the research on charge collection performance has important manifestations in high-energy particle detection, X-ray detection, low-light imaging, etc. The quality of charge collection performance also determines the detection efficiency and accuracy. Secondly, there will be low electric field areas or zero electric field areas in the unetched areas of traditional three-dimensional trench electrode detectors, which reduces the effective volume of the detector. Avoiding the dead zones inside the detector has also become one of the key points in the research of three-dimensional trench detectors.
[0004] Therefore, there is an urgent need for a simple and effective three-dimensional detector to improve charge collection performance and increase the effective volume of the detector. Summary of the Utility Model
[0005] In order to achieve the above object, the utility model provides a through-type three-dimensional quasi-hemispherical electrode detector based on an SOI substrate, which solves the problems of low electric field areas and zero electric field areas existing in the unetched areas of the prior art, improves the charge collection performance, and increases the effective volume of the detector.
[0006] The technical solution adopted by the utility model is
[0007] The through-type three-dimensional quasi-hemispherical electrode detector based on an SOI substrate includes: a substrate with a cubic shape, and a central anode at the center of the upper surface of the substrate; an anode aluminum electrode contact layer covers the upper surface of the central anode; an upper surface SiO2 layer covers the area on the upper surface of the substrate where the anode aluminum electrode contact layer is not covered; an SOI substrate heavily doped layer is provided at the bottom of the substrate, and a substrate is provided below the SOI substrate heavily doped layer; an intermediate SiO2 layer is provided between the SOI substrate heavily doped layer and the substrate; the grooves between the four side surfaces of the substrate and the adjacent substrates form groove walls; the SOI substrate heavily doped layer and the groove walls form a cathode; a cathode aluminum electrode contact layer covers the surface of the grooves between adjacent substrates; a bottom surface SiO2 layer covers the bottom surface of the substrate.
[0008] Further, the length and width of the substrate are both 80 - 100 um, and the height is both 40 - 50 um; the groove spacing between adjacent substrates is 10 - 20 um.
[0009] Further, the doping type of the substrate is N-type lightly doped, and the substrate doping concentration is 4×10 11 -1×10 12 / cm 3 。
[0010] Further, the central anode is circular.
[0011] Further, the doping type of the central anode is N-type heavily doped, the doping depth is 0.5 - 1 um, and the central anode doping concentration is 4×10 18 -1×10 19 / cm 3 。
[0012] Further, the doping type of the groove wall is P-type heavily doped, and the doping depth is 0.5 - 1 um.
[0013] Further, the doping concentration of the groove wall is 4×10 18 -1×10 19 / cm 3 。
[0014] Further, the doping type of the SOI substrate heavily doped layer is P-type heavily doped.
[0015] Further, the doping concentration of the SOI substrate heavily doped layer is 4×10 18 -1×10 19 / cm 3 。
[0016] Further, the electrode spacing between each groove wall and the central anode is equal, being 40 - 50 um.
[0017] The beneficial effects of the present utility model:
[0018] 1. The electric field distribution of the detector of the present utility model is quasi-hemispherical, with a more uniform electric field distribution, not affected by angles, and at the same time capable of further reducing the readout capacitance and the fully depleted voltage.
[0019] 2. The traditional three-dimensional trench electrodes cannot be fully etched, which results in the existence of dead zones in the unetched part, leading to a reduction in the effective volume of the detector and a decrease in the charge collection efficiency. Compared with the traditional three-dimensional trench electrode detector, the unit structure design of the quasi-hemispherical electrode of the present utility model theoretically avoids the existence of dead zones, thereby improving the charge collection rate of the new detector unit. There is almost no zero electric field region inside the detector of the present utility model.
[0020] 3. Due to the small electrode distance between the cathode and anode of the present utility model, the fully depleted voltage of the detector is greatly reduced. The depletion voltage of the detector is only 2.4V without irradiation. At the same time, the leakage current is reduced, so the energy consumption is lower and the radiation resistance is stronger.
[0021] 4. Since there is a trench spacing of 10 - 20um between each cuboid unit, it plays a good isolation role for the detector units, reducing the interference between detector units. Therefore, the detector units are effectively isolated, thereby reducing the crosstalk effect between detector units.
[0022] 5. The detector of the present utility model achieves the electrical performance of a spherical detector and does not involve complex process flows. It only requires processes such as etching trenches and ion implantation to form electrodes. Compared with the spherical detector, the detector of the present utility model has a simpler process and is easier to implement. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0024] Figure 1 It is the overall structure diagram of the detector of the present utility model.
[0025] Figure 2 It is the top view of the detector of the present utility model.
[0026] Figure 3 It is the left view of the detector of the present utility model.
[0027] Figure 4 It is the cross-sectional view of the detector of the present utility model along the X-axis.
[0028] Figure 5 is the electron concentration of the detector of the present utility model along the Z-axis.
[0029] Figure 6 is Figure 5 the partial enlarged view of
[0030] Figure 7 is the leakage current curve diagram of the detector of the present utility model.
[0031] Figure 8 is the leakage current curve diagram of the traditional three-dimensional detector.
[0032] Figure 9 is the electric field simulation diagram of the cross-section of the detector of the present utility model along the X-axis at a voltage of 2.4V.
[0033] Figure 10 is the electric potential simulation diagram of the cross-section of the detector of the present utility model along the X-axis at a voltage of 2.4V.
[0034] Figure 11 is the electron concentration simulation diagram of the cross-section of the detector of the present utility model along the X-axis at a voltage of 2.4V.
[0035] Figure 12 is the electric potential distribution diagram of the detector unit of the present utility model.
[0036] Figure 13 is the electric field distribution diagram of the traditional columnar electrode three-dimensional detector.
[0037] In the figure, 1. Anode aluminum electrode contact layer, 2. Central anode, 3. Upper surface SiO2 layer, 4. Substrate, 5. Groove wall, 6. Cathode aluminum electrode contact layer, 7. Intermediate SiO2 layer, 8. Bottom surface SiO2 layer, 9. SOI substrate heavily doped layer, 10. Substrate. Specific embodiments
[0038] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.
[0039] See Figures 1 - 4 , the detector structure of the present utility model is a 3×3 array. The detector includes a total of 9 cuboid units, with the length and width both being 80-100um and the height being 40-50um. The groove spacing between the cuboid units is 10-20um. Among them, each cuboid unit includes a substrate 4, and the substrate 4 is N-type lightly doped with a doping concentration of 4×10 11-1×10 12 / cm 3 ; An excessively high substrate doping concentration will result in: an increase in the conductivity of the device, generation of leakage current, and reduction of the insulation performance of the device; an excessively high doping concentration will increase the carrier lifetime and diffusion length, resulting in a decrease in the response speed of the device, and further affecting the cut-off frequency of the device. An excessively high doping concentration causes a decrease in the carrier collection efficiency, reducing the sensitivity and detection performance of the device. An excessively low doping concentration will result in: a decrease in the conductivity of silicon, leading to a decrease in the conductivity of the device and affecting the performance stability of the device; it will limit the carrier lifetime and diffusion length, resulting in a decrease in the device response speed and affecting the frequency response characteristics of the device; it causes a decrease in the carrier collection efficiency, reducing the signal sensitivity and detection performance of the device.
[0040] The center of the upper surface of the substrate 4 is the central anode 2. The doping type of the central anode 2 is N-type heavy doping, with a diameter of 10 μm and a depth of 0.5 - 1 μm, and the doping concentration is 4×10 18 -1×10 19 / cm 3 ; The heavy doping concentration is obtained by dividing the concentration of ion implantation by the implantation depth. If the doping concentration is too low, the performance of the silicon crystal obtained is not as good as that of a conductor, and an excessively high doping concentration makes it difficult to restore the silicon crystal and requires cumbersome operations such as cooling. A larger doping concentration makes it difficult to remove the photoresist and makes the process more difficult. Therefore, an excessively low doping concentration will not play the role of an electrode, and an excessively high doping concentration will make the subsequent process cumbersome.
[0041] The upper surface of the central anode 2 is covered with the anode aluminum electrode contact layer 1, and the thickness of the anode aluminum electrode contact layer 1 is 1 μm; the area on the upper surface of the substrate 4 that is not covered with the anode aluminum electrode contact layer 1 is covered with the upper surface SiO2 layer 3 to prevent the substrate 4 from oxidizing in the air; facing the silicon detector, the four side surfaces of each detector unit and the grooves between the cuboid units together form the groove wall 5. The doping type of the groove wall 5 is P-type heavy doping, with a depth of 0.5 - 1 μm and a doping concentration of 4×10 18 -1×10 19 / cm 3 ; If the doping of the groove wall is too high, the following problems may occur: an excessively high doping will cause a change in the electric field distribution between the groove wall and the bottom, increase the counterattack effect, and reduce the electron collection efficiency; an excessively high doping will increase the carrier concentration near the groove wall, extend the charge diffusion time, and affect the time resolution of the detector; an excessively high doping affects the energy deposition and resolution, reducing the energy resolution of the detector. If the doping of the groove wall is too low, it will result in: a weaker electric field near the groove wall, reducing the carrier collection efficiency in the groove and affecting the sensitivity of the detector; an excessively low doping reduces the amplification multiplication factor, reducing the gain performance of the device; an excessively low doping will also increase the charge diffusion time and affect the time resolution.
[0042] The groove surfaces between the cuboid units are covered with a cathode aluminum electrode contact layer 6, and the thickness of the cathode aluminum electrode contact layer 6 is 1 μm; the entire bottom surface of the detector is covered with a bottom surface SiO2 layer 8.
[0043] In each cuboid unit, an SOI substrate heavily doped layer 9 is provided at a distance of 40.5 - 51 μm from the top of the detector. An intermediate SiO2 layer 7 is provided between the SOI substrate heavily doped layer 9 and the substrate 10; the doping concentration of the SOI substrate heavily doped layer 9 is 4×10 18 -1×10 19 / cm 3 , too high doping will cause the electric field distribution to change, increase the back strike effect, and reduce the electron collection efficiency; too high doping will increase the carrier concentration, prolong the charge diffusion time, and affect the time resolution of the detector; too high doping affects energy deposition and resolution, and reduces the energy resolution of the detector. If the doping is too low, it will cause: the electric field nearby is weak, reducing the collection efficiency of carriers in the groove and affecting the sensitivity of the detector; too low doping reduces the amplification multiplication factor and the gain performance of the device; too low doping will also increase the charge diffusion time and affect the time resolution. The doping type is P-type heavy doping, which together with the groove wall 5 forms the cathode of the detector. Therefore, the groove wall 5 surrounds the central anode 2, and the electrode spacing between each groove wall 5 and the central anode 2 is equal. The spacing between the central anode 2 and the groove wall 5 is 40 - 50 μm. Therefore, the potential gradient after the detector is pressurized is quasi-hemispherical, as Figure 12 shown.
[0044] Figure 5 is the electron concentration of the detector of the present utility model along the Z-axis. The applied bias voltage is 1.0V - 2.5V. By changing the applied bias voltage of the detector, it can be seen that the electron concentration of the silicon detector of the present utility model decreases as the applied bias voltage increases.
[0045] Figure 6 is Figure 5 a partial enlarged view. It can be seen that when the sensitive area of the detector of the present utility model reaches the fully depleted state, its electron concentration no longer changes as the applied bias voltage increases. The depletion voltage is 2.4V, which has reached a relatively small magnitude; the fully depleted voltage refers to the minimum reverse bias voltage required to achieve complete depletion of the volume between the anode and cathode. After applying a reverse bias voltage to the detector, the depletion region will expand as the applied voltage increases until it reaches the fully depleted state. And compared with the traditional three-dimensional trench electrode detector, the detector of the present utility model has a dot-shaped central anode, so it has a lower capacitance.
[0046] Figure 7 is the leakage current curve graph of the detector of the present utility model. Figure 8is the leakage current curve of the traditional 3D detector, where the abscissa is the absolute value of the applied bias voltage. It can be seen that the leakage current of the traditional detector is at the order of 10 -8 magnitude, and the detector is at the order of 10 -9 magnitude. Therefore, at the same bias voltage, the leakage current of the detector of the present invention is smaller, and the low leakage current directly reduces the power consumption of the detector in the working state, making the detector of the present invention have lower power consumption.
[0047] Figure 9 is the electric field simulation diagram of the cross-section of the detector of the present invention along the X-axis at a voltage of 2.4V. It can be seen that an obvious electron drift channel is formed in the detector at a low voltage of 2.4V, and most of the detector area is a high electric field area, that is, the electric field strength is higher than 300 V / m. When the voltage reaches the full depletion voltage of 2.4V, the internal electric field reaches all parts of the detector, and the zero electric field area almost disappears. Figure 13 is a traditional columnar electrode 3D detector, and a saddle-shaped low electric field or zero electric field area, that is, a dead zone, will be formed inside the detector. There is almost no 0 electric field area inside the detector of the present invention.
[0048] Figure 10 is the electric potential simulation diagram of the cross-section of the detector of the present invention along the X-axis at a voltage of 2.4V. It can be seen that the electric potential distribution of the detector of the present invention at a bias voltage of 2.4V is very uniform and symmetric, and the gradient distribution is obvious. The uniform electric potential gradient is conducive to charge collection. In order to ensure that free electrons drift to the anode and are collected by the anode, the detector is reverse biased, so the electric potential of the central anode 2 is the highest.
[0049] Figure 11 is the electron concentration simulation diagram of the cross-section of the detector of the present invention along the X-axis at a voltage of 2.4V. It can be seen that when the bias voltage is applied to about 2.4V, the electron concentration in the depletion region hardly changes any more, forming an obvious electron movement trend orbit, corresponding to the carrier orbit formed by the electric field distribution in the above Figure 9 .
[0050] The invention points of the present invention:
[0051] 1. The detector area of the present invention realizes full penetration, that is, a heavily doped layer is formed from the top to the bottom of the detector unit, realizing full penetration of the entire height of the trench wall 5, and full penetration from the central anode 2 to the cathode region.
[0052] 2. The detector of the present invention adopts a detector unit in the shape of a cuboid. In each unit, the distance between the central anode 2 and the trench wall 5 is equal, achieving the electrical performance of a spherical detector.
[0053] 3. The present utility model combines SOI technology and does not involve complex process flows, only requiring processes such as etching grooves and ion implantation to form electrodes.
[0054] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments.
[0055] The above is only a preferred embodiment of the present utility model and is not intended to limit the protection scope of the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model are included in the protection scope of the present utility model.
Claims
1. Through-type three-dimensional quasi-hemispherical electrode detector based on SOI substrate, comprising: Substrate (4), characterized in that the substrate (4) is cube-shaped, and the center of the upper surface of the substrate (4) is the central anode (2); the upper surface of the central anode (2) is covered with an anodic aluminum electrode contact layer (1); the upper surface SiO2 layer (3) is covered at the place where the anodic aluminum electrode contact layer (1) is not covered on the upper surface of the substrate (4); an SOI substrate heavily doped layer (9) is provided at the bottom of the substrate (4), and a substrate (10) is provided below the SOI substrate heavily doped layer (9); an intermediate SiO2 layer (7) is provided between the SOI substrate heavily doped layer (9) and the substrate (10); the grooves between the four side surfaces of the substrate (4) and the adjacent substrates (4) form a groove wall (5); the SOI substrate heavily doped layer (9) and the groove wall (5) form a cathode; the surface of the groove between the adjacent substrates (4) is covered with a cathodic aluminum electrode contact layer (6); the bottom surface of the substrate (10) is covered with a bottom surface SiO2 layer (8).
2. The through-type three-dimensional quasi-hemispherical electrode detector based on an SOI substrate according to claim 1, wherein The length and width of the substrate (4) are both 80 - 100 um, and the height is both 40 - 50 um; the groove spacing between adjacent substrates (4) is 10 - 20 um.
3. The through-type three-dimensional quasi-hemispherical electrode detector based on an SOI substrate according to claim 1, characterized in that, The central anode (2) is circular.
4. The through-type three-dimensional quasi-hemispherical electrode detector based on an SOI substrate according to claim 1, characterized in that, The doping type of the groove wall (5) is P-type heavy doping, and the doping depth is 0.5 - 1 um.
5. The through-type three-dimensional quasi-hemispherical electrode detector based on an SOI substrate according to claim 1, characterized in that The doping type of the SOI substrate heavily doped layer (9) is P-type heavy doping.
6. The through-type three-dimensional quasi-hemispherical electrode detector based on an SOI substrate according to any one of claims 1-5, characterized in that, The electrode spacing between each groove wall (5) and the central anode (2) is equal, being 40 - 50 um.