A spiral ring electrode pixel silicon detector array with isolation trench structure

Abstract

The application provides a spiral ring electrode pixel silicon detector array with an isolation groove structure, comprising a semiconductor substrate, a spiral ring electrode and a center electrode embedded in the top of each detector unit in the semiconductor substrate, the spiral ring electrode and the center electrode connected to form a cathode, and the center electrode located at the middle position of the spiral ring electrode; a first aluminum electrode contact layer is arranged on the center electrode; a second aluminum electrode contact layer is arranged on the spiral ring electrode; a silicon dioxide insulating layer is filled in the top of the semiconductor substrate except the first aluminum electrode contact layer and the second aluminum electrode contact layer; an anode layer is embedded in the bottom of the semiconductor substrate, and a third aluminum electrode contact layer is arranged below the anode layer; and an isolation groove is connected with the silicon dioxide insulating layer. The problems of large silicon pixel detector capacitance and signal mutual interference between pixel units in the prior art are solved. The application further provides a replacement scheme of the spiral ring electrode pixel silicon detector array with the isolation groove structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-energy physics and astrophysics, and relates to a spiral ring electrode pixel silicon detector array with an isolated trench structure. BACKGROUND

[0002] In today's high-energy physics experiments, such as experiments in the Large Hadron Collider, silicon microstrip detectors and pixel detectors are widely used. In order to achieve two-dimensional position resolution, using double-sided (or back-to-back single-sided) silicon strip detectors and pixel detectors has always been a conventional method. It also has very wide application in many fields with scientific applications, including space satellites, medical imaging, and nuclear security guards.

[0003] Pixel detectors have strong advantages in position resolution, and silicon detectors have high energy resolution, fast response time, and easy large-scale integration (VLSI) advantages. Gradually mature manufacturing technology, easier manufacturing process, and relatively low cost of pixel detectors.

[0004] The anode and cathode of the conventional silicon pixel detector are covered with metal electrodes, and the larger effective electrode area makes the capacitance of the detector larger. The larger the capacitance, the more the leakage current and noise during the operation of the detector, which ultimately reduces the position resolution and energy resolution of the detector. The existing silicon detector unit obtains a large-area silicon pixel detector by being arranged in an array, but there is signal interference between the pixel units.

[0005] Based on this, the present application provides a spiral ring electrode silicon array pixel detector, which has small capacitance, small noise, and does not affect each other between the pixel units. SUMMARY

[0006] In order to achieve the above purpose, the present application provides a spiral ring electrode pixel silicon detector array with an isolated trench structure, which solves the problems of large capacitance of the silicon pixel detector and signal interference between the pixel units in the prior art.

[0007] To solve the above technical problems, the technical scheme adopted by the present application is a spiral ring electrode pixel silicon detector array with an isolation trench structure, comprising a semiconductor substrate, a spiral ring electrode and a center electrode embedded on the top of the semiconductor substrate, the spiral ring electrode and the center electrode connected to form a cathode, and the center electrode located at the middle position of the spiral ring electrode; a first aluminum electrode contact layer is arranged on the center electrode; a second aluminum electrode contact layer is arranged on the spiral ring electrode; a silicon dioxide insulating layer is filled in the semiconductor substrate on the top of the semiconductor substrate except the first aluminum electrode contact layer and the second aluminum electrode contact layer; an anode layer is embedded at the bottom of the semiconductor substrate, and a third aluminum electrode contact layer is arranged below the anode layer; an isolation trench is located between each unit in the semiconductor substrate, and the isolation trench is connected with the silicon dioxide insulating layer.

[0008] The present application also provides an alternative solution, comprising a semiconductor substrate, a spiral ring electrode and a center electrode embedded on the top of the semiconductor substrate, the center electrode located at the middle position of the spiral ring electrode and not connected with the spiral ring electrode, the center electrode serving as a readout electrode, and the spiral ring electrode serving as a floating electrode; a first aluminum electrode contact layer is arranged on the center electrode; a silicon dioxide insulating layer is filled in the semiconductor substrate on the top of the semiconductor substrate except the first aluminum electrode contact layer; an anode layer is embedded at the bottom of the semiconductor substrate, and a third aluminum electrode contact layer is arranged below the anode layer; an isolation trench is located between each unit in the semiconductor substrate, and the isolation trench is connected with the silicon dioxide insulating layer.

[0009] Further, each unit in the semiconductor substrate is a cuboid, a cylinder or a hexagonal prism.

[0010] Further, the size of the cuboid semiconductor substrate is 240um in length, 240um in width and 300um in height.

[0011] Further, the semiconductor substrate is N-type doped, and the doping concentration is 8x1011 / cm 2 .

[0012] Further, the spiral ring electrode and the center electrode are P-type doped with a doping concentration of 1x1019 / cm 2 , and the embedding depth is 1um.

[0013] Further, the anode layer is N-type doped with a doping concentration of 1x1018 / cm 2 -1x1020 / cm 2 .

[0014] Further, the thickness of the isolation trench is 1um-10um, and the depth is 1um-290um; the isolation trench is made of silicon dioxide or polysilicon.

[0015] Further, the isolation groove has a thickness of 1-10 um and a depth of 1-290 um, and the isolation groove is formed by cutting the semiconductor substrate.

[0016] The present application has the following advantages:

[0017] 1. The detector unit is designed in a square shape, which is convenient for array arrangement and has no dead zone; the detector unit can also be designed in a circular shape, which has a more uniform electric field distribution inside the detector; the hexagonal design unit has the closest electric field to the circular shape, and can also realize the array arrangement without dead zone.

[0018] 2. Compared with the existing three-dimensional electrode silicon detector, the pixel detector has a more mature manufacturing process, lower cost, wider application, and very good position resolution, and is cost-effective.

[0019] 3. The capacitance of the square spiral electrode silicon detector unit is only related to the area of the electrode itself, and the electrode area of the square spiral electrode is smaller than that of the traditional full-surface electrode, so the capacitance is smaller, and the corresponding noise is also smaller.

[0020] 4. The study on the electrical performance of the square spiral electrode silicon detector array shows that the potential distribution is uniform, and the electric field distribution is roughly the same as that of the detector structure unit, and is not affected by adjacent units, and has good coherence.

[0021] 5. According to the existing process, the pixel can be made to be micro-nano level, and the position resolution is very high.

[0022] 6. The top center electrode of the detector is used as a readout electrode, and the surrounding spiral ring electrode is used as a floating electrode, which also has smaller capacitance. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0024] Figure 1 is a schematic diagram of a spiral ring electrode pixel silicon detector array structure with an isolation groove structure according to an embodiment of the present application.

[0025] Figure 2 is a top view of a spiral ring electrode pixel silicon detector array with an isolation groove structure according to an embodiment of the present application.

[0026] Figure 3 is Figure 2 A-A sectional view of

[0027] Figure 4 is a schematic diagram of an alternative embodiment of the present application.

[0028] Figure 5 is a top view of an alternative embodiment of the present application.

[0029] Figure 6 is a schematic diagram of a cathode structure of an alternative embodiment of the present application.

[0030] Figure 7 is a B-B sectional view of Figure 6

[0031] Figure 8 is a heavy ion incidence simulation result diagram of a common pixel detector array.

[0032] Figure 9 is a heavy ion incidence simulation result diagram of a spiral ring electrode pixel silicon detector array with an isolation trench structure and an alternative embodiment of the present application.

[0033] In the figure, 1. first aluminum electrode contact layer, 2. second aluminum electrode contact layer, 3. silicon dioxide insulation layer, 4. semiconductor substrate, 5. isolation trench, 6. anode layer, 7. third aluminum electrode contact layer, 8. center electrode, 9. spiral ring electrode. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0035] EMBODIMENT

[0036] A spiral ring electrode pixel silicon detector array with an isolation trench structure, as shown in Figures 1-3 ​As shown, including semiconductor base 4, the top of each unit embedded in the semiconductor base 4 spiral ring electrode 9 and center electrode 8, spiral ring electrode 9 and center electrode 8 connected to form a cathode, center electrode 8 is located in the middle of the spiral ring electrode 9; The center electrode 8 is provided with a first aluminum electrode contact layer 1; The spiral ring electrode 9 is provided with a second aluminum electrode contact layer 2, which is used to connect the external circuit as a readout electrode; The top of the semiconductor base 4 is filled with a silicon dioxide insulating layer 3 except the first aluminum electrode contact layer 1 and the second aluminum electrode contact layer 2; The bottom of the semiconductor base 4 is embedded with an anode layer 6, and the third aluminum electrode contact layer 7 is covered below the anode layer 6, which is the pressure point of the detector anode; The isolation trench 5 is located between each unit of the semiconductor base 4, and the remaining base between each unit of the semiconductor base is still considered as a whole after being separated by the isolation trench 5; The isolation trench 5 is connected with the silicon dioxide insulating layer 3 to form a whole, which can play a good isolation role and can ensure that the units do not interfere with each other.

[0037] As an alternative, as shown in Figures 4-7 The spiral ring electrode 9 and the center electrode 8 are no longer connected but are divided into two parts: the center electrode 8 is located in the middle of the spiral ring electrode 9 and the two are not connected, the center electrode 8 is a readout electrode, and the spiral ring electrode 9 is a floating electrode; Only the first aluminum electrode contact layer 1 is provided above the center electrode 8 and the rest is covered with a silicon dioxide insulating layer 3, which reduces the area of the readout electrode and in turn reduces the capacitance of the detector, while having the same electrical characteristics and performance as the spiral ring electrode silicon array pixel detector described before; The bottom of the semiconductor base 4 is embedded with an anode layer 6, and the third aluminum electrode contact layer 7 is covered below the anode layer 6; The isolation trench 5 is located between each unit of the semiconductor base 4, and the remaining base between each unit of the semiconductor base is still considered as a whole after being separated by the isolation trench 5; The isolation trench 5 is connected with the silicon dioxide insulating layer 3.

[0038] Further, each unit in the semiconductor base 4 is a rectangular cuboid, which is convenient for arraying and has no dead zone; Each unit in the semiconductor base 4 can also be a cylindrical shape, which can have a more uniform electric field distribution inside the detector; Each unit in the semiconductor base 4 can also be a hexagonal prism, which has a single unit electric field closest to circularity and can achieve an array arrangement without dead zones.

[0039] Further, the size of the rectangular cuboid semiconductor base 4 is 240 um long x 240 um wide x 300 um high.

[0040] Further, the semiconductor base 4 is N-type doped, that is, a pentavalent element such as phosphorus or arsenic is doped into silicon, and the doping concentration is 8 x 1011 / cm 2 .

[0041] Further, the spiral ring electrode 9 and the center electrode 8 are P-type doped with a doping concentration of 1x1018 / cm 2 -1x1020 / cm 2 , that is, boron is doped into silicon with an embedding depth of 1um.

[0042] Further, the anode layer 6 is N-type doped with a doping concentration of 1x1018 / cm 2 -1x1020 / cm 2 .

[0043] Further, the isolation trench 5 has a thickness of 1um-10um, and the thickness of the isolation trench is limited by the current process technology, and the thinner the process is required, and when the trench is too thick, the working area is reduced; the depth of the isolation trench 5 is 1um-290um, and the deeper the isolation trench 5 is, the better the isolation effect is, but the deeper the trench is, the mechanical integrity of the silicon substrate is affected; the isolation trench 5 is made of materials such as silicon dioxide and polycrystalline silicon with isolation characteristics or is a trench formed by cutting the semiconductor substrate 4, and the isolation trench 5 separates the semiconductor substrate 4, avoids the signal interference between the units of the semiconductor substrate 4, and reduces the coherence between the units.

[0044] The anode and cathode of the traditional pixel silicon detector are covered by metal electrodes, and the electrode area almost occupies the top surface of the detector, and the large effective electrode area will cause the large capacitance of the detector. The square spiral ring electrode design is adopted in the present application, the electrode area is small, and only the top surface area is about 40%, which can greatly reduce the capacitance of the detector, and the lower the capacitance of the detector is, the smaller the corresponding noise is, thereby improving the signal-to-noise ratio and improving the resolution.

[0045] The detector unit (that is, each unit in the semiconductor substrate 4) of the embodiment of the present application is designed as a square, which is convenient for arraying and has no dead angle; the detector substrate can also be designed as a circle, so that the electric field distribution in the detector is more uniform; the hexagonal design unit has the closest electric field to the circularity, and the array arrangement without dead angle can also be realized.

[0046] Compared with the existing three-dimensional electrode silicon detector, the pixel detector has a more mature manufacturing process, a lower cost, a wider application, a very good position resolution, and a high cost performance.

[0047] Figure 8 The simulation result of the heavy ion incidence of the ordinary pixel detector array is shown in the following table, Figure 9 The simulation result of the heavy ion incidence of the embodiment and the alternative scheme of the embodiment is shown in the following table, Figure 9 The incidence points are in adjacent units, and the top cathode of the center unit is read out. Figure 9 and Figure 8Compared with the prior art, the response current ratio of the application is Figure 8 The response current of the common pixel detector array is reduced by 3 orders of magnitude, from 10A-6A to 10A-9A or even 10A-10A, the coherence between the detector units of the application is almost negligible, that is, there is no interference between the units; at the same time, it can be seen from the formula (1) that the response current of the pixel detector array with the floating electrode spiral ring electrode silicon array (that is, the alternative of the application) is relatively smaller. Figure 9

[0048] Each embodiment in the specification is described in a related manner, and the same and similar parts between each embodiment can be referred to each other, and each embodiment mainly explains the difference from other embodiments.

[0049] The above only describes the preferred embodiments of the application, and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.​

Claims

1. A spiral ring electrode pixel silicon detector array with an isolation trench structure, characterized in that, The semiconductor substrate (4) includes a helical ring electrode (9) and a central electrode (8) embedded on its top. The central electrode (8) is located in the center of the helical ring electrode (9) and the two are not connected. The central electrode (8) serves as a readout electrode, and the helical ring electrode (9) serves as a floating electrode. A first aluminum electrode contact layer (1) is provided on the central electrode (8). The top of the semiconductor substrate (4) is filled with a silicon dioxide insulating layer (3) in addition to the first aluminum electrode contact layer (1). An anode layer (6) is embedded at the bottom, and a third aluminum electrode contact layer (7) is covered below the anode layer (6); an isolation trench (5) is located between each unit in the semiconductor substrate (4), and the isolation trench (5) is connected to the silicon dioxide insulating layer (3); the thickness of the isolation trench (5) is 1um-10um, and the depth is 1um-290um; and the isolation trench (5) is made of silicon dioxide or polycrystalline silicon, or the isolation trench (5) is a trench formed by cutting the semiconductor substrate (4).

2. The spiral ring electrode pixel silicon detector array with an isolation trench structure according to claim 1, characterized in that, The detector unit inside the semiconductor substrate (4) is rectangular, cylindrical, or hexagonal.

3. The spiral ring electrode pixel silicon detector array with an isolation trench structure according to claim 1, characterized in that, The size of the cuboid semiconductor substrate (4) is 240um in length × 240um in width × 300um in height.

4. The spiral ring electrode pixel silicon detector array with an isolation trench structure according to claim 1, characterized in that, The semiconductor substrate (4) is N-type doped with a doping concentration of 8 × 10¹¹ / cm². 2 .

5. A spiral ring electrode pixel silicon detector array with an isolation trench structure according to claim 1, characterized in that, The spiral ring electrode (9) and the center electrode (8) are doped with a concentration of 1×10¹⁸ / cm². 2 -1×1020 / cm 2 It is P-type doped with an embedding depth of 1 μm.

6. The spiral ring electrode pixel silicon detector array with an isolation trench structure according to claim 1, characterized in that, The anode layer (6) has a doping concentration of 1×10¹⁸ / cm². 2 -1×1020 / cm 2 N-type doping.

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