Double-sided etching and double-sided filling trench electrode silicon detector
Through double-sided etching and double-sided filling trench electrode technology, the dead-zone problem of traditional detectors is solved, uniform electric field distribution and efficient charge collection are achieved, and the performance and stability of the detector are improved.
Patent Information
- Application Number
- CN202422185921.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-06
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-09-06
AI Technical Summary
The traditional three-dimensional trench electrode silicon detector has dead zones, resulting in low charge collection efficiency and uneven electric field, which affects the detector performance.
Double-sided etching double-sided filling trench electrode technology is used to ensure that the electrode penetrates the entire silicon matrix, eliminates dead zones, and achieves uniform distribution of the electric field.
It improves the charge collection rate and detection efficiency, enhances the sensitivity and position resolution of the detector, reduces the total depletion voltage, and avoids the risk of electrode breakdown.
Smart Images
Figure CN223080429U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of silicon detectors, and relates to a double-sided etched and double-sided filled trench electrode silicon detector. Background Technique
[0002] At present, the research on silicon-based semiconductor detection materials at home and abroad mostly focuses on high-purity silicon-based materials. As the basic material of silicon-based photodetectors, the high-purity silicon layer is directly related to the performance of the device. Silicon materials are widely used in silicon semiconductor detectors and microelectronic integrated circuits. In the past decade, great improvements have been made in the technology of making high-purity silicon, resulting in a significant improvement in its performance. At present, the research focus of silicon-based semiconductor detectors in China is how to improve the purity of single-crystalline silicon and how to effectively control its impurities and defects.
[0003] For traditional three-dimensional trench electrode silicon detectors, it is necessary to ensure that the detector body does not fall off the substrate during the etching process. After the etching is completed, due to the relatively thin thickness of the silicon substrate, the trench electrodes cannot completely penetrate the entire silicon substrate, and can only be etched to about 90% of the depth of the silicon substrate. Therefore, in order to ensure good mechanical stability of the detector structural unit or array, a certain thickness of the substrate needs to be retained on the silicon wafer. Therefore, the first disadvantage of traditional three-dimensional trench electrode silicon detectors is the existence of dead zones in the unetched areas. The dead zone refers to the weak electric field or zero electric field area in the unetched part of the detector. If the dead zone occupies a large part of the detector volume, the electrical characteristics of the detector will be seriously affected, thereby reducing the charge collection efficiency. Secondly, the electrode spacings of traditional three-dimensional trench electrode detectors are different, which is also a key factor leading to the reduction of the charge collection rate. At the maximum electrode spacing, the electric field strength is the lowest, the drift force of electrons and holes is insufficient, and the probability of being captured increases, which leads to the reduction of the charge collection rate of the detector. The difference in electrode spacing has a great impact on the stability of the detector performance.
[0004] Therefore, there is an urgent need for a simple and effective three-dimensional trench electrode silicon detector to eliminate the dead zone problem existing in traditional detectors and have excellent performance. Content of the Utility Model
[0005] In order to achieve the above object, the utility model provides a double-sided etched and double-sided filled trench electrode silicon detector, which solves the problems of traditional silicon detectors that cannot eliminate dead zones and have poor stability, and at the same time realizes the penetration of the electrodes and has excellent performance.
[0006] The technical solution adopted by the utility model is
[0007] Double-sided etched and double-sided filled trench electrode silicon detector, comprising: a silicon substrate, the shape of the silicon substrate being a cube; a central anode is arranged on both sides of the center of the silicon substrate along the vertical direction; trench cathodes are arranged on both sides of the silicon substrate; adjacent silicon substrates share the same trench cathode; an anode aluminum electrode contact layer is covered under the central anode; a cathode aluminum electrode contact layer is covered outside the upper part of the trench cathode; the lower surface of the silicon substrate is covered with a lower surface SiO2 layer except for the parts on both sides of the trench cathode where the anode aluminum electrode contact layer is not covered; the upper surface of the silicon substrate is covered with an upper surface SiO2 layer except for the part above the central anode where the cathode aluminum electrode contact layer is not covered.
[0008] Further, the diameter of the central anode is: 5 - 20 μm; the distance between the trench cathodes of adjacent silicon substrates is: 5 - 20 μm.
[0009] Further, the silicon substrate is N-type lightly doped, with a doping concentration of 4×10 11 / cm 3 -2×10 12 / cm 3 。
[0010] Further, the central anode is N-type heavily doped, with a doping concentration of 1×10 18 / cm 3 -2×10 20 / cm 3 。
[0011] Further, the trench cathode is P-type heavily doped, with a doping concentration of 1×10 18 / cm 3 ~2×10 20 / cm 3 。
[0012] Further, the thicknesses of both the upper surface SiO2 layer and the lower surface SiO2 layer are 1 μm.
[0013] Further, the thicknesses of both the anode aluminum electrode contact layer and the cathode aluminum electrode contact layer are 1 μm.
[0014] Further, the number of silicon substrates is n², forming an n×n array.
[0015] Further, in each silicon substrate, the distance between the trench cathode and the central anode is equal.
[0016] The beneficial effects of the present utility model are:
[0017] 1. There are many existing through-groove electrode detectors. Due to process technology limitations, electrode etching cannot completely penetrate the entire silicon body, and a certain thickness is retained as a substrate to prevent the silicon body from falling off, resulting in a part of the area in the detector that cannot be etched, namely the so-called "dead zone". Therefore, there is always a dead zone at the bottom of the traditional three-dimensional trench detector. The electric field in this part of the dead zone is weak and the charge distribution is uneven, seriously affecting the performance of the detector. The detector of the present utility model optimizes the etching process and performs etching and filling on both sides of the silicon detector. It can first perform etching and filling of the trenches in the upper half of the silicon body, and then perform etching and filling of the trenches in the remaining part of the silicon body, which ensures that the silicon body does not fall off during the etching process, so there is no need for a substrate as support. Therefore, the central anode and trench cathode of the present utility model penetrate the entire silicon substrate, ensuring that the electrodes can reach every corner of the substrate and completely pass through the silicon substrate. This design enables the electric field to be evenly distributed throughout the detector, eliminating the existence of the dead zone, thereby realizing the full utilization of the silicon body.
[0018] 2. The full depletion voltage of the detector of the present utility model is lower. In the case of no irradiation, the depletion voltage of the detector unit is only 1.8V, with low energy consumption and a faster charge collection rate.
[0019] 3. Since in the detector of the present utility model, the electric field can penetrate the entire silicon body without obstruction and is no longer restricted by the dead zone. Therefore, the detector of the present utility model provides the largest volume for charge collection, can distribute charges more evenly, and collect and transmit charges more quickly. Compared with traditional columnar electrode silicon detectors and traditional three-dimensional trench detectors, the present utility model improves the detection efficiency of the detector for particles or photons, increases the response speed of the detector, and thus improves the performance of the detector.
[0020] 4. Due to the use of double-sided etching and double-sided filling technology and the existence of through electrodes in the detector of the present utility model, its electric field and potential distribution are more uniform. Therefore, detectors with any different electrode spacings can be designed. Their full depletion voltages will increase with the increase of the electrode spacing, but the electric field and potential distributions are relatively uniform. At the same time, the sensitivity of the detector to particles or photons can be increased, which helps to further accurately locate the position of incident particles or photons and improve the position resolution of the detector.
[0021] 5. In the traditional three-dimensional trench electrode detector, the cathode aluminum electrode contact layer and the anode aluminum electrode contact layer are on the same plane, while in the present utility model, the cathode aluminum electrode contact layer and the anode aluminum electrode contact layer are separated. A bias voltage is applied to one side of the cathode aluminum electrode contact layer and read on the other side of the anode aluminum electrode contact layer, which can avoid the risk of electrode breakdown. Description of the Drawings
[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.
[0023] Figure 1 It is the structure diagram of the upper surface of the detector of the present invention.
[0024] Figure 2 It is the structure diagram of the lower surface of the detector of the present invention.
[0025] Figure 3 It is the top view of the detector of the present invention.
[0026] Figure 4 It is the cross-sectional view of a unit of the detector of the present invention along the X-axis.
[0027] Figure 5 It is the electron concentration curve at the cross-section of a unit of the detector of the present invention along the X-axis.
[0028] Figure 6 is Figure 5 the partial enlarged view of.
[0029] Figure 7 It is the electric field simulation diagram at the cross-section of a unit of the detector of the present invention along the X-axis under a voltage of 1.8V.
[0030] Figure 8 It is the electric potential simulation diagram at the cross-section of a unit of the detector of the present invention along the X-axis under a voltage of 1.8V.
[0031] Figure 9 It is the electron concentration simulation diagram at the cross-section of a unit of the detector of the present invention along the X-axis under a voltage of 1.8V.
[0032] Figure 10 It is the electric potential distribution diagram between the two electrodes of a traditional three-dimensional columnar electrode silicon detector.
[0033] Figure 11 It is the structure diagram of a traditional three-dimensional columnar electrode detector.
[0034] Figure 12 It is the structure diagram of a traditional three-dimensional trench electrode silicon detector.
[0035] In the figure, 1. Upper surface SiO2 layer, 2. Central anode, 3. Cathode aluminum electrode contact layer, 4. Trench cathode, 5. Silicon substrate, 6. Lower surface SiO2 layer, 7. Anode aluminum electrode contact layer. Detailed implementation manners
[0036] Next, in combination with the drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.
[0037] See Figures 1-4 , the double-sided etching and double-sided filling trench electrode detector structure is an n×n array,
[0038] In this embodiment, it is a 3×3 array, and the detector includes a total of 9 detector units. In this embodiment, each detector unit is a cube with a side length of 120 μm.
[0039] Each detector unit includes a silicon substrate 5. The silicon substrate 5 is lightly doped with N-type, and the doping concentration is 4×10 11 / cm 3 -2×10 12 / cm 3 ;
[0040] Too high doping concentration may damage the lattice structure of the silicon substrate, resulting in a decrease in the stability and reliability of the material. It may also introduce too many impurities and defects, and these impurities and defects may become charge traps or scattering centers, affecting the sensitivity and response speed of the detector. In addition, too high doping concentration may also lead to an increase in the noise of the detector, reducing its signal-to-noise ratio and detection accuracy. If the doping concentration is too low, it cannot significantly improve the conductivity of the silicon substrate, resulting in the detector not meeting the expected performance indicators.
[0041] In each detector unit, a central anode 2 is provided on both sides along the center of the silicon substrate 5. The diameter range of the central anode 2 is: 5 - 20 μm; the central anode 2 is heavily doped with N-type, and the doping concentration is 1×10 18 / cm 3 -2×10 20 / cm 3; An excessively high N-type doping concentration can cause damage to the lattice structure of the silicon substrate, introducing too many lattice defects, thereby reducing the stability and reliability of the material; too many impurities and defects may become charge traps or scattering centers, increasing the noise of the detector and reducing the signal-to-noise ratio; an excessively high concentration of free electrons in the N-type material may lead to an increase in the recombination rate of electrons and holes, affecting the response speed and sensitivity of the detector. An excessively low N-type doping concentration may result in insufficient conductivity of the silicon substrate and an excessively low concentration of free electrons, affecting the charge transport efficiency and the response speed of the detector; during the detection process, an excessively low electron concentration may cause charges to accumulate near the anode and cannot be transmitted to the cathode in time, reducing the performance of the detector. The lower part of the central anode 2 is covered with an anode aluminum electrode contact layer 7,
[0042] Groove cathodes 4 are provided on both sides of the silicon substrate 5, and adjacent detector units share the same groove cathode 4,
[0043] The groove cathode 4 is P-type heavily doped, with a doping concentration of 1×10 18 / cm 3 ~2×10 20 / cm 3 . An excessively high P-type doping concentration may cause damage to the lattice structure of the silicon substrate, introducing too many lattice defects, thereby reducing the stability and reliability of the material; due to the excessively high doping concentration, the concentration of holes (positive charge carriers) in the P-type material will also be excessively high, which may lead to an increase in leakage current and affect the performance of the detector; too many impurities and defects may become charge traps or scattering centers, increasing the noise of the detector and reducing the signal-to-noise ratio. An excessively low P-type doping concentration may result in insufficient conductivity of the silicon substrate and an excessively low concentration of holes, affecting the charge transport efficiency and the response speed of the detector; during the detection process, an excessively low hole concentration may cause charges to accumulate near the cathode and cannot be transmitted to the anode in time, reducing the performance of the detector. The outer side of the upper part of the groove cathode 4 is covered with a cathode aluminum electrode contact layer 3;
[0044] The lower surface of the silicon substrate 5 is covered with a lower surface SiO2 layer 6 except at the positions where the anode aluminum electrode contact layer 7 is not covered on both sides of the groove cathode 4, to prevent the silicon substrate 5 from oxidizing in the air. The groove width between adjacent detector units, that is, the width of the cathode aluminum electrode contact layer 3 between adjacent detector units is: 5 - 20 μm;
[0045] The upper surface of the silicon substrate 5 is covered with an upper surface SiO2 layer 1 except at the position where the cathode aluminum electrode contact layer 3 is not covered on the upper part of the central anode 2, to prevent the silicon substrate 5 from oxidizing in the air; the thickness of both the upper surface SiO2 layer 1 and the lower surface SiO2 layer 6 is 1 μm; the thicknesses of both the anode aluminum electrode contact layer 7 and the cathode aluminum electrode contact layer 3 are 1 μm;
[0046] The peripheral trench cathode 4 surrounds the central anode 2. The distance between the trench cathode 4 and the central anode 2 in each detector unit is equal, making the potential and electric field distribution of the detector more uniform, which helps to form a uniform electric field distribution inside the detector, improve the sensitivity of the detector to particles or photons, further accurately locate the position of incident particles or photons, and improve the position resolution of the detector; in this embodiment, the distance between the trench cathode 4 and the central anode 2 is 50 μm. At the same time, adjacent detector units can share the same trench cathode 4, which greatly reduces the dead zone and significantly improves the detector performance.
[0047] The electrodes of traditional three-dimensional detectors are not penetrating and there are dead zones. The present utility model proposes a novel double-sided etched and double-sided filled trench electrode detector with high detection efficiency, high sensitivity, and good radiation resistance.
[0048] The doping concentration of the silicon substrate 5 is selected as , and the electrode spacing Perform simulation experiments.
[0049] Figure 5 is the electron concentration at the cross-section along the X-axis of a unit of the detector of the present utility model.
[0050] Figure 5 In , the applied bias voltage is 1V - 2.6V. It can be seen that the electron concentration of the detector of the present utility model decreases with the increase of the applied bias voltage. When the bias voltage increases to 1.8V, the sensitive region of the detector reaches the fully depleted state, and its electron concentration no longer changes with the increase of the applied bias voltage. Therefore, the full depletion voltage of this detector unit is 1.8V. As the bias voltage continues to increase, the concentration of electrons in the depletion region becomes lower and lower, indicating that the detector has reached the completely depleted state at this time.
[0051] Figure 6 is Figure 5 The partial enlarged view of Figure 6 It can be seen from that the depletion voltage of the detector is 1.8V. It shows that with the increase of the bias voltage, the electron concentration in the depletion region continuously decreases. When it increases to 1.8V, the electron concentration in 99% of the depletion region of the detector is lower than the substrate concentration, and it can be judged that the detector reaches the basic depletion state.
[0052] On the other hand, the detector depletion voltage formula is as follows:
[0053]
[0054] Among them, is the depletion voltage, is the effective doping concentration of the p-type lightly doped silicon substrate , = , is the electric charge of each electron, , is the vacuum permittivity, , is the relative permittivity of silicon, , is the electrode spacing, ; The potential barrier of the PN junction of the silicon material is about 0.75V, and the theoretical value of the depletion voltage of the detector is obtained through the depletion voltage formula , which is very close to the 1.8V depletion voltage obtained in the simulation results.
[0055] Figure 7 is the electric field simulation diagram of a unit of the detector of the present invention along the cross-section of the X-axis at a voltage of 1.8V. It shows that the full-through trench cathode 4 of the present invention solves the low electric field problem existing between traditional columnar electrodes, and isolates the detector units from each other, making the internal electric field distribution more uniform, which helps electrons to be collected and transmitted more effectively inside the detector.
[0056] Figure 11 is the structure diagram of a traditional three-dimensional columnar electrode detector. For a traditional three-dimensional columnar electrode detector, this structure embeds heavily doped P-type and N-type electrodes into the silicon substrate, and the electrode distribution is symmetrical, which leads to a saddle-shaped distribution of the electric field potential between the two electrodes. And in the central part between the two electrodes, no matter how large the bias voltage is applied, there will be a dead zone, and there is also a problem of too high electric field near the junction electrode.
[0057] Figure 12 is the structure diagram of a traditional three-dimensional trench electrode silicon detector. Although the traditional three-dimensional trench electrode silicon detector has trench electrodes, a certain thickness is reserved at the bottom of the detector as a substrate, and its performance is better than that of a three-dimensional columnar electrode detector, which can improve the saddle-shaped distribution of the electric field potential. However, due to the existence of the substrate, therefore, the performance of the full-through trench electrode detector of the present invention is better than that of the traditional detector.
[0058] Figure 8 is the potential simulation diagram of a unit of the detector of the present invention along the cross-section of the X-axis at a voltage of 1.8V. It shows that the full-through trench cathode 4 and the central anode 2 of the detector of the present invention optimize the potential distribution inside the detector. The detector body is surrounded by the trench cathode 4, and the potential value increases along the radius inside the detector body, and the potential is evenly and symmetrically distributed.
[0059] Figure 9It is the simulation diagram of the electron concentration at the cross-section along the X-axis of a unit of the detector of the present utility model under a voltage of 1.8V. It shows that when the detector is in the working state, the electron concentration inside the detector can maintain a uniform distribution, indicating that the working state of the detector is very stable. This stability is crucial for the performance and reliability of the detector, especially in application scenarios that require long-term stable operation. In addition, the uniformity of the electron concentration distribution usually helps to improve the sensitivity and response speed of the detector.
[0060] Figure 10 It is the potential distribution diagram between the two electrodes of a traditional three-dimensional columnar electrode silicon detector. In a traditional three-dimensional columnar electrode silicon detector, heavily doped P-type and N-type electrodes are embedded in the silicon matrix, and the electrode distribution is symmetric. This leads to a saddle-shaped potential distribution between the two electrodes. Moreover, in the central part between the two electrodes, there will be a zero electric field region regardless of how large the bias voltage is applied, which is not conducive to the collection and transmission of charges. And there is also a problem of excessive electric field near the interface where the electrode directly contacts the silicon matrix.
[0061] 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.
[0062] The above description is only for the preferred embodiments 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. Double-sided etched and double-sided filled trench electrode silicon detector, comprising: Silicon substrate (5), characterized in that the silicon substrate (5) is cube-shaped; a central anode (2) is provided on both sides of the center of the silicon substrate (5) along the vertical direction; groove cathodes (4) are provided on both sides of the silicon substrate (5); adjacent silicon substrates (5) share the same groove cathode (4); the lower part of the central anode (2) is covered with an anode aluminum electrode contact layer (7); the upper outer side of the groove cathode (4) is covered with a cathode aluminum electrode contact layer (3); the lower surface of the silicon substrate (5) is covered with a lower surface SiO2 layer (6) except for the areas on both sides of the groove cathode (4) where the anode aluminum electrode contact layer (7) is not covered; the upper surface of the silicon substrate (5) is covered with an upper surface SiO2 layer (1) except for the area above the central anode (2) where the cathode aluminum electrode contact layer (3) is not covered.
2. The double-sided etched and double-sided filled trench electrode silicon detector according to claim 1, wherein The diameter of the central anode (2) is: 5 - 20 μm; the distance between the groove cathodes (4) of adjacent silicon substrates (5) is: 5 - 20 μm.
3. The double-sided etched and double-sided filled trench electrode silicon detector according to claim 1, wherein The thicknesses of both the upper surface SiO2 layer (1) and the lower surface SiO2 layer (6) are 1 μm.
4. The double-sided etched and double-sided filled trench electrode silicon detector according to claim 1, characterized in that The thicknesses of both the anode aluminum electrode contact layer (7) and the cathode aluminum electrode contact layer (3) are 1 μm.
5. The double-sided etched and double-sided filled trench electrode silicon detector according to claim 1, characterized in that, The number of the silicon substrates (5) is n², forming an n×n array.
6. The double-sided etched and double-sided filled trench electrode silicon detector according to claim 5, wherein In each of the silicon substrates (5), the distance between the groove cathode (4) and the central anode (2) is equal.