CN211125665U - Hexagonal mutual buckling type electrode three-dimensional silicon detector - Google Patents

Abstract

The utility model discloses a hexagonal interlocking electrode three-dimensional silicon detector, which comprises a hexagonal column-shaped isolation silicon body, a central electrode is arranged in the central axis of the isolation silicon body, and upper and lower sides of the isolation silicon body are provided with upper and lower sides. The first trench electrode and the second trench electrode are spliced together. The first trench electrode is formed by snapping two C-shaped trench electrodes. The top of the first trench electrode and the center electrode is provided with a metal contact layer. The top of the isolation silicon body between the layers is provided with a silicon dioxide protective layer, and the second trench electrode, the center electrode and the bottom of the isolated silicon body are provided with a silicon dioxide protection layer; the hexagonal interlocking electrode prepared by the utility model The three-dimensional silicon detector has small dead zone, uniform internal electric field distribution, good charge collection performance, good unit independence between detection units, high detection efficiency, and high utilization rate of silicon wafers.

Description

Hexagonal Interlocking Electrode 3D Silicon Detector

technical field

The utility model belongs to the technical field of high-energy physics and astrophysics, and relates to a three-dimensional silicon detector with hexagonal interlocking electrodes.

Background technique

In 1997, S. Parker et al. took the lead in proposing the first generation of three-dimensional cylindrical electrode silicon detector. The detector has a high electric field area near the electrode and a low electric field area in the electrode symmetry center. The uneven distribution of the electric field makes the silicon detector in high radiation. In order to further enhance the radiation resistance of silicon detectors, in 2009, scientists from Brookhaven National Laboratory in the United States proposed a new type of three-dimensional silicon detectors, namely three-dimensional trench electrode silicon detectors. The columnar electrode silicon detector and the three-dimensional trench electrode silicon detector have more independent detection units, more uniform electric field distribution, and improved radiation resistance.

However, due to the "dead zone" of the unetched electrode with a thickness of 10% to 30% at the bottom of the three-dimensional trench electrode silicon detector, the electric field in the "dead zone" is extremely low, the electric field distribution is uneven, and the voltage cannot be depleted. The holes move slowly or even cannot move in the "dead zone", which leads to a longer movement time of electrons and holes. Under strong radiation conditions, electrons and holes are easily captured by traps, which makes the electrical signal attenuate; the "dead zone" cannot be oriented. Collecting electrons and holes, this area basically loses the detection function. When the three-dimensional trench electrode silicon detector works, the particles can only be incident on one side. The detection efficiency of the silicon detector is low. When the detection units form an array, the "dead zone" makes the silicon detector The independence of the unit becomes worse.

SUMMARY OF THE INVENTION

In order to achieve the above purpose, the present invention provides a three-dimensional silicon detector with hexagonal interlocking electrodes, which eliminates the "dead zone" at the bottom of the three-dimensional trench electrode silicon detector through a double-sided etching process, so that the silicon detector can The particles are collected on both sides, which improves the unit independence and detection efficiency of the silicon detector.

The technical scheme adopted by the utility model is that the hexagonal interlocking electrode three-dimensional silicon detector comprises a hexagonal-shaped isolated silicon body, the central axis of the isolated silicon body is etched with a central electrode, and the The six sides are etched with a first trench electrode from top to bottom, the six sides of the isolation silicon body are etched with a second trench electrode from bottom to top, the first trench electrode and the second trench electrode splicing, the first trench electrode is formed by snapping two C-shaped trench electrodes, and an unetched S-shaped isolation silicon body is left at the snap joint of the two C-shaped trench electrodes;

The bottom surfaces of the second trench electrode, the isolation silicon body, and the center electrode are covered with a silicon dioxide protective layer;

The top surfaces of the first trench electrode and the center electrode are covered with a metal contact layer, the isolation silicon body between the first trench electrode and the center electrode is covered with a silicon dioxide protective layer, and the silicon dioxide protects The layer is the same height as the metal contact layer.

Further, the total height of the isolation silicon body is 300 μm˜500 μm, the height of the first trench electrode is 10% of the total height of the isolation silicon body, and the height of the second trench electrode is the total height of the isolation silicon body 90%, the wall thickness of the first trench electrode and the second trench electrode are both 10 μm, the wall thickness of the S-shaped isolation silicon body is 3 μm to 4 μm, the silicon dioxide protective layer and the metal contact layer The thickness is 1 μm.

Further, the side length of the cross-section of the center electrode is 5 μm, the side of the cross-section of the center electrode is parallel to the side of the top surface of the first trench electrode, and the corner of the center electrode is spaced from the corner of the first trench electrode. is 50 μm.

Further, the central electrode is formed through the following process: firstly, the hexagonal prism is etched from top to bottom at the central axis of the isolated silicon body, then the inner sidewalls of the hexagonal prism are diffused and doped with boron, and finally the hexagonal prism is filled. polysilicon.

Further, the first trench electrode and the second trench electrode are formed by the following process: firstly etching trenches on the six sides of the isolated silicon body, then diffusing and doping phosphorus on the inner walls of the trenches, and finally in the trenches. Filled with polysilicon.

Further, the heavily doped concentrations of the central electrode, the first trench electrode and the second trench electrode are all 1×10 ¹⁹ cm ^-3 , the isolation silicon body is made of lightly doped boron silicon base, and the isolation silicon body is The light doping concentration is 1×10 ¹² cm ^-3 .

The beneficial effects of the present utility model are as follows: 1. The utility model adopts the double-sided etching process to make the trench electrodes penetrate the entire silicon detector, eliminating the dead zone, making the electric field distribution inside the silicon detector uniform, and improving the performance of the silicon detector. Charge collection performance; 2. The trench electrode covers the entire silicon detector unit, which improves the unit independence when the silicon detector unit forms an array; 3. The utility model can receive particles on both sides during operation, the detection efficiency is improved, and the composition During the array, the silicon detector units can be seamlessly connected, and adjacent silicon detector units can share a peripheral groove edge, which improves the utilization rate of silicon wafers, saves costs and improves production efficiency.

Description of drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are just some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

FIG. 1 is a structural diagram of a silicon detector unit of the present invention.

FIG. 2 is a top view of the silicon detector unit of the present invention.

FIG. 3 is a bottom view of the silicon detector unit of the present invention.

FIG. 4 is an arrangement diagram of the silicon detector unit of the present invention.

FIG. 5 is an effect diagram of an embodiment of the present invention.

FIG. 6 is a comparison diagram of the effect of the embodiment of the present invention.

In the figure, 1. First trench electrode, 2. S-shaped isolation silicon body, 3. Second trench electrode, 4. Center electrode, 5. Isolated silicon body, 6. Metal contact layer, 7. Silicon dioxide protection Floor.

Detailed ways

The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to 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 implementations. example. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

The hexagonal interlocking electrode three-dimensional silicon detector includes a hexagonal column-shaped isolated silicon body 5 , and a central electrode 4 is etched through a single side from top to bottom at the central axis of the isolated silicon body 5 . The side faces are etched with a first trench electrode 1 from top to bottom, the six sides of the isolated silicon body 5 are etched with a second trench electrode 3 from bottom to top, and the first trench electrode 1 is spliced with the second trench electrode 3 , the first trench electrode 1 is formed by snapping two C-shaped trench electrodes, and there is an unetched S-shaped isolation silicon body 2 at the clamping place of the two C-shaped trench electrodes; the second trench electrode 3 , The bottom surface of the center electrode 4 and the isolation silicon body 5 is covered with a silicon dioxide protective layer 7, the top surface of the first trench electrode 1 and the center electrode 4 is covered with a metal contact layer 6, and the gap between the first trench electrode 1 and the center electrode 4 is The isolated silicon body 5 is covered with a silicon dioxide protective layer 7, the metal contact layer 6 covered on the top surface of the first trench electrode 1 and the central electrode 4 is an aluminum electrode contact layer, and the aluminum electrode contact layer and the silicon dioxide protective layer 7 The thickness is 1 μm.

When preparing the central electrode 4, firstly, a hexagonal column is etched through the central axis of the isolated silicon body 5, and boron is diffused and doped in the inner sidewall of the hexagonal column, and then polysilicon is filled in the hexagonal column; the first trench electrode 1 and the second trench electrode are prepared. When the trench electrode 3 is used, trenches are first etched on the six sides of the isolated silicon body 5 , and phosphorus is diffused and doped on the inner wall of the trench, and then polysilicon is filled.

The center electrode 4 serves as the cathode of the silicon detector, collecting holes during the detection process, the first trench electrode 1 and the second trench electrode 3 serve as the anode of the silicon detector, collecting electrons during the detection process, the center electrode 4, the first trench electrode 3 The doping concentration of the first trench electrode 1 and the second trench electrode 3 is the same, and the heavy doping concentration of the central electrode 4, the first trench electrode 1 and the second trench electrode 3 are all 1×10 ¹⁹ cm ⁻³ . The isolation silicon body 5 is composed of a lightly doped boron silicon base, and the lightly doped concentration of the isolation silicon body 5 is 1×10 ¹² cm ⁻³ .

The height of the isolation silicon body 5 is 300 μm˜500 μm, the height of the first trench electrode 1 is 10% of the height of the isolation silicon body 5 , the height of the second trench electrode 3 is 90% of the height of the isolation silicon body 5 , the first trench The wall thickness of the trench electrode 1 and the second trench electrode 3 are both 10 μm, and the wall thickness of the S-shaped isolation silicon body 2 is 3 μm to 4 μm; the first trench electrode 1 and the S-shaped isolation silicon body 2 have the same height, and the S-shaped isolation The height of the silicon body 2 increases, which will increase the side area of the two C-shaped trench electrodes that do not cover the isolation silicon body 5. However, the S-shaped isolation silicon body 2 is not etched and heavily doped, and the charge collection efficiency is not high, so The height of the S-shaped isolation silicon body 2 should be minimized; the height and width of the S-shaped isolation silicon body 2 are too small to support the isolation silicon body 5 between adjacent silicon detector units, resulting in mechanical instability of the silicon detector. It affects the use of the silicon detector; therefore, the height of the S-shaped isolation silicon body 2 is set to 10% of the height of the isolation silicon body 5, and the width is set to 3 μm to 4 μm, which can ensure the mechanical stability of the silicon detector. It is possible to reduce the contact area of the S-shaped isolation silicon body 2 between adjacent silicon detector units, and to improve the charge collection capability and unit independence of the silicon detectors; The body is arranged in an S-shaped buckle instead of a straight connection. The S-shaped buckle makes the carriers excited by the high-energy particles incident hardly generate induced charges on the adjacent unit electrodes, that is, interfere with the induced charges, and improve the The unit independence of the silicon detector makes the detection result more accurate.

The side length of the cross-section of the center electrode 4 is 5 μm, the side of the cross-section of the center electrode 4 is parallel to the side of the top surface of the first trench electrode 1 , and the distance between the corner of the center electrode 4 and the corner of the first trench electrode 1 is 50 μm , the reduction of the center distance between the center electrode 4 and the trench electrode will reduce the area ratio of the effective detection area of the silicon detector, and the increase of the center distance will correspondingly increase the drift distance of the carriers excited by the incident particles in the silicon detector, The carrier is easily captured by the defect energy level generated by irradiation during drift, which reduces the charge collection rate, thereby reducing the radiation resistance performance of the silicon detector, and reducing the reliability of the silicon detector in a high radiation environment; In the present invention, the distance between the center electrode 4 and the corner of the first trench electrode 1 is set to 50 μm. Under the condition of ensuring the effective detection area of the silicon detector, the drift distance of carriers is reduced, and the silicon detector is improved. The charge collection efficiency and radiation resistance performance.

There is a "dead zone" in the three-dimensional trench electrode silicon detector because the isolation silicon body 5 between the trench electrode and the center electrode 4 will fall off after the peripheral trench electrode and the center electrode are etched from top to bottom. The etching process fails, so only part of the peripheral trench electrodes and the center electrode can be etched, and the etching cannot be penetrated in the height direction, and there is a "dead zone" at the bottom of the silicon detector. The embodiment of the present invention adopts a double-sided etching process , an S-shaped isolation silicon body 2 is arranged between the C-shaped trench electrodes to connect the silicon bodies of adjacent detector units or silicon wafers to prevent the intermediate isolation silicon body 5 from falling off, eliminating the three-dimensional trench electrode silicon detection The "dead zone" at the bottom of the silicon detector makes the electric field distribution inside the silicon detector uniform, the movement time of electrons and holes in the silicon detector is shortened, the probability of being trapped by defects is reduced, and the charge collection performance and radiation resistance of the silicon detector are improved. At the same time, when the silicon detector is working, the particles can be incident on both sides, so that the detection efficiency of the silicon detector is improved.

Example 1

The structure of the hexagonal interlocking electrode silicon detector is shown in Figures 1 to 3, including a hexagonal isolated silicon body 5. The central axis of the isolated silicon body 5 is etched through a single side from the top to the bottom. Prism, the inner sidewall of the hexagonal prism is filled with polysilicon to form a central electrode 4 after boron is diffused and doped, the six sides of the isolated silicon body 5 are etched with trenches, and the inner wall of the trench is filled with polysilicon after doping with phosphorus to form a first trench electrode 1 and the second trench electrode 3, the bottom surface of the isolation silicon body 5, the center electrode 4, and the second trench electrode 3 is covered with a silicon dioxide protective layer 7, and the top surface of the first trench electrode 1 and the center electrode 4 is covered with The metal contact layer 6, the isolation silicon body 5 between the metal contact layers 6 is covered with a silicon dioxide protective layer 7; the first trench electrode 1 is formed by snapping two C-shaped trench electrodes, and the two C-shaped trenches An unetched S-shaped isolation silicon body 2 is left at the connection of the groove electrode, and the size of the S-shaped isolation silicon body 2 is 3 μm.

The height of the isolation silicon body 5 is 300 μm, the height of the first trench electrode 1 and the S-shaped isolation silicon body 2 is 30 μm, the height of the second trench electrode 3 is 270 μm, the first trench electrode 1 and the second trench The wall thickness of the electrodes 3 is 10 μm, the first trench electrode 1 and the second trench electrode 3 are the anodes of the silicon detector, and electrons are collected during the detection process. The side length of the cross section of the center electrode 4 is 5 μm, and the center electrode 4 It is the cathode of the silicon detector, collects holes during the detection process, and the heavy doping concentration of the first trench electrode 1 and the second trench electrode 3 is both 1×10 ¹⁹ cm ⁻³ .

The isolation silicon body 5 between the trench electrode and the center electrode 4 separates the anode and cathode of the silicon detector, and the distance between the corner of the center electrode 4 and the corner of the first trench electrode 1 is 50 μm, which isolates the silicon body 5 and the S-shape. The isolation silicon bodies 2 are all composed of lightly doped boron-silicon bases, and the doping concentrations are all 1×10 ¹² cm ^-3 ; the trench electrodes, the isolation silicon bodies 5 and the center electrode 4 form a PIN-type homojunction, and the PN junction is located in the Near the trench electrode, the depletion voltage of the silicon detector is lower and it is not easy to be broken down.

The top of the first trench electrode 1 and the center electrode 4 is covered with a 1 μm thick aluminum electrode contact layer. The aluminum electrode contact layer connects the anode and cathode of the silicon detector to the bias voltage, the anode is connected to the positive electrode of the bias voltage, and the cathode is connected to the bias voltage. The voltage negative electrode, the isolation silicon body 5 between the aluminum electrode contact layers is covered with a silicon dioxide protective layer 7 with a thickness of 1 μm, and the center electrode 4, the second trench electrode 3, and the bottom surface of the isolation silicon body 5 are also covered with a 1 μm thick silicon dioxide protective layer 7. The silicon oxide protective layer 7 can isolate the anode and cathode to prevent short circuit.

As shown in FIG. 4 , when the detection units prepared in the embodiment of the present invention are arranged as silicon detectors, adjacent detection units share a trench electrode side wall, so that the detection units are seamlessly connected, and the silicon detectors have a compact structure. The utilization rate of silicon wafers is high, which can save costs.

Example 2

The following dimensions of the silicon detector are modified as follows: the height of the isolation silicon body 5 is 500 μm, the height of the first trench electrode 1 and the S-shaped isolation silicon body 2 is 50 μm, the height of the second trench electrode 3 is 450 μm, and the S-shaped The wall thickness of the isolation silicon body 2 is 4 μm, and other structures of the silicon detector are the same as those of the first embodiment.

The silicon detectors prepared in Examples 1 to 2 are used to detect incident particles. According to the detection results, it is known that enough carriers need to be excited after incident particles enter the silicon detector, and they can only be obtained when the influence of interface charges is small. Good electrical signal, the height of the silicon detector is too small, the carriers generated by the incident particles are easily affected by the upper and lower interface charges of the silicon detector, resulting in a weak electrical signal detected by the silicon detector, which is not conducive to the detection of incident particles. ; In order to improve the position resolution and energy resolution of the silicon detector, the height of the silicon detector needs to be adjusted appropriately. When the height of the silicon detector is 300 μm to 500 μm, the detection performance of the silicon detector is better.

Example 3

The size and position of each structure in the detection unit of Example 1 are not changed, only the notch of the two C-shaped groove electrodes is set as a straight line connecting the center electrode 4, and the junction of the two C-shaped groove electrodes is assembled. Leave a straight opening.

Example 4

The size and position of each structure in the detection unit of Example 1 are not changed, only the notch of the two C-shaped groove electrodes is set as an inclined linear notch, and the junction of the two C-shaped groove electrodes is left parallel after splicing. Sloped opening.

A single MIP (Minimum Ionizing Particle) is vertically incident into one unit of the silicon detectors prepared in Example 1, Example 3 and Example 4, and the induced current is collected in the adjacent units of the detection unit, and the obtained induced current is the interference Current, the smaller the interference current, the better the energy resolution of the detector. The specific gravity distribution field and electric field distribution of the silicon detectors prepared in each embodiment are obtained through simulation. The simulation results are used to perform interpolation fitting, and program integral calculation to obtain the specific The size of the interference current, the it curve of the interference current is shown in Figure 5, in order to show the difference of each curve, the logarithm of the base 10 is taken as the ordinate of Figure 5, as shown in Figure 6, the silicon probe prepared in Example 1 The specific gravity distribution field of the device is much smaller than that prepared in Example 3 and Example 4, and there are several orders of magnitude difference between them; according to Ramo's theorem i = q v _dr · E _w , it can be known that the carrier charge q is a fixed value, The carrier drift velocity v _dr is related to the internal electric field strength of the silicon detector, and the internal electric field strength of the silicon detectors prepared in Example 1, Example 3 and Example 4 is not much different, so the magnitude of the interference current i is only the same as that of the silicon detector. The specific gravity distribution field inside the detector is related. It can be seen from Figure 6 that the silicon detector unit prepared in Example 1 has the smallest interference current detected by its adjacent units when the particle is incident, and the unit independence between the detection units is optimal.

Each embodiment in this specification is described in a related manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model are all included in the protection scope of the present utility model.

Claims (6)

1. A three-dimensional silicon detector with hexagonal interlocking electrodes, characterized in that it comprises an isolated silicon body (5) in the shape of a hexagonal prism, and a central electrode (4) is etched through the central axis of the isolated silicon body (5). , the six sides of the isolation silicon body (5) are etched with a first trench electrode (1) from top to bottom, and the six sides of the isolation silicon body (5) are etched with a second trench electrode from bottom to top (3), the first trench electrode (1) is spliced with the second trench electrode (3), and the first trench electrode (1) is formed by snapping two C-shaped trench electrodes. An unetched S-shaped isolation silicon body (2) is left at the clipping position of the C-shaped trench electrode; The bottom surfaces of the second trench electrode (3), the isolation silicon body (5) and the central electrode (4) are covered with a silicon dioxide protective layer (7); The top surfaces of the first trench electrode (1) and the central electrode (4) are covered with a metal contact layer (6), and an insulating silicon body is provided between the first trench electrode (1) and the central electrode (4). (5) is covered with a silicon dioxide protective layer (7), and the silicon dioxide protective layer (7) is the same height as the metal contact layer (6). 2 . The hexagonal interlocking electrode three-dimensional silicon detector according to claim 1 , wherein the total height of the isolation silicon body ( 5 ) is 300 μm˜500 μm, and the first trench electrode ( 1 ). ) is 10% of the total height of the isolation silicon body (5), the height of the second trench electrode (3) is 90% of the total height of the isolation silicon body (5), the first trench electrode (1) ) and the wall thickness of the second trench electrode (3) are both 10 μm, the wall thickness of the S-shaped isolation silicon body (2) is 3 μm to 4 μm, the silicon dioxide protective layer (7) and the metal contact layer ( 6) The thicknesses are all 1 μm. 3 . The three-dimensional silicon detector with hexagonal interlocking electrodes according to claim 1 , characterized in that, the side length of the cross section of the central electrode ( 4 ) is 5 μm, and the cross section of the central electrode ( 4 ) is 5 μm in length. The sides are parallel to the sides of the top surface of the first trench electrode (1), and the distance between the corner of the central electrode (4) and the corner of the first trench electrode (1) is 50 μm. 4. The hexagonal interlocking electrode three-dimensional silicon detector according to claim 1, characterized in that, the central electrode (4) is formed by the following process: first, at the central axis of the isolated silicon body (5) from The hexagonal prisms are etched from top to bottom, then boron is diffused and doped on the inner sidewalls of the hexagonal prisms, and finally polysilicon is filled in the hexagonal prisms. 5. The hexagonal interlocking electrode three-dimensional silicon detector according to claim 1, wherein the first trench electrode (1) and the second trench electrode (3) are formed by the following process: first A trench is etched on the six sides of the isolated silicon body (5), then phosphorus is diffused and doped on the inner wall of the trench, and finally polysilicon is filled in the trench. 6. The hexagonal interlocking electrode three-dimensional silicon detector according to claim 1, wherein the central electrode (4), the first trench electrode (1) and the second trench electrode (3) The heavy doping concentration of the isolating silicon body (5) is 1×10 ¹⁹ cm ^-3 , the isolation silicon body (5) is composed of a lightly doped boron silicon base, and the light doping concentration of the isolating silicon body (5) is 1×10 ¹² cm ^-3 .

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