阅读说明：本技术 一种同心环型大面积硅漂移探测器、设计方法及应用 (Concentric ring type large-area silicon drift detector, design method and application ) 是由 李正 母恒恒 刘曼文 于 2019-11-01 设计创作，主要内容包括：本发明属于探测器技术领域,公开了一种同心环型大面积硅漂移探测器、设计方法及应用,计算探测器的电极和电阻的宽度分布；计算硅漂移探测器电场电压分布；确定漂移电场和漂移时从点S1到点S2的最佳漂移路径；确定硅漂移探测器后表面的设计；漂浮电极的设计。本发明对SDD载流子漂移行为规律与重掺杂电极生长的分析。设计具有双面相关的既保持均匀电子漂移电场又提供平滑漂移轨迹的双面电极,建立强度在0.5～15keV软X射线粒子的高能量分辨率、高效收集SDD的创新设计制作方式。在同心圆型的硅漂移探测器电极之间利用ALD技术沉积一层分压电阻,使同心圆型的探测器在不需要外加分压器的情况下可正常工作。(The invention belongs to the technical field of detectors, and discloses a concentric ring type large-area silicon drift detector, a design method and application, wherein the width distribution of electrodes and resistors of the detector is calculated; calculating the electric field voltage distribution of the silicon drift detector; determining an optimal drift path from point S1 to point S2 in the drift electric field and drift; determining the design of the rear surface of the silicon drift detector; design of floating electrode. The invention analyzes the SDD carrier drift behavior rule and the growth of the heavily doped electrode. Designing a double-sided electrode which has double-sided correlation, not only keeps a uniform electron drift electric field, but also provides a smooth drift track, and establishing an innovative design and manufacturing mode for efficiently collecting SDD with high energy resolution and high-efficiency of soft X-ray particles with the intensity of 0.5-15 keV. A layer of voltage dividing resistor is deposited between the electrodes of the concentric circular silicon drift detector by using the ALD technology, so that the concentric circular detector can normally work without an additional voltage divider.)

1. A design method of a concentric ring type large-area silicon drift detector is characterized by comprising the following steps:

firstly, calculating the width distribution of electrodes and resistors of a detector;

secondly, calculating the electric field voltage distribution of the silicon drift detector;

thirdly, determining the optimal drift path from the point S1 to the point S2 when the drift electric field and the drift are performed;

fourthly, determining the design of the rear surface of the silicon drift detector;

and fifthly, designing a floating electrode.

2. The method of claim 1, wherein the first step calculates the width distribution of the electrodes and resistors of the detector, the voltage distribution is provided by a heavily doped P-type cathode passing through the concentric circle, the heavily doped P-type cathode is formed by ion implantation, and the width of the ion implantation region at the radial r point is

the distance between the concentric circles is as follows:

P₀＝W_i ^cath+2G₀+W_i ^R；

the resistance value of the resistor is;

where i is denoted as the ith turn, α is associated with the shape of the figure, denotes the perimeter of the figure, and in this configuration it denotes a circular arc

obtaining;

r₁radius of first ring resistance, W₁ ^RIs the width of the first ring of resistors;

the radius of the collecting anode is:

r_iradius representing the i-th turn resistance:

obtaining;

obtaining:

and calculating the resistance width and the cathode width of any circle.

3. The method of claim 1, wherein the second step calculates the electric field voltage distribution of the silicon drift detector, the internal drift electric field of the cylindrical silicon drift detector is related to the upper and lower surface potential distributions of the detector, and the negative potential at any point (r, x, θ) inside the cylindrical silicon drift detector satisfies the following condition:

wherein x is the coordinate of the thickness direction of the detector, r is the coordinate along the radius direction of the cylinder, and theta is an angular coordinate;

and Φ (r) are the potentials of the front and rear surfaces (x ═ 0 and x ═ d), respectively:

since the voltage dividing resistance between the cathode rings is constant in this design, Δ V is constant, Δ V_ARepresenting the potential difference of the front surface, Δ V_BRepresents a negative potential difference:

t represents the thickness of atomic layer deposition:

ρ_ssquare resistivity for resistance:

the voltage Δ V between adjacent cathode rings is;

ΔV＝RI＝EP₀＝constant；

IR (r) from ohm's LawOut, EP₀From the electric field integral, where I is the current of the cathode and E is the surface electric field;

the geometry and current of the resistive ring are related to the surface electric field of the SDD:

ρ_sαr_iI＝P₀EW_i ^R。

4. the method of claim 1, wherein the third step determines the optimal drift path from point S1 to point S2 for drift electric field and drift according to the equation

obtaining;

the corresponding distribution of the reverse voltage is determined by the distribution of the front voltage, and the distribution of the reverse electric field is as follows:

wherein V₁ ^BThe voltage is applied to the first ring of cathode rings on the reverse side, and gamma is a constant;

the drift electric field in the SDD electron drift channel is;

or:

e (r) is represented by the equation ρ_sαr_iI＝P₀EW_i ^RIt is determined that,

5. The method of claim 1, wherein the fourth step determines the design of the back surface of the silicon drift detector by the equation

a back surface electric field;

the remaining back surface parameters were the same as for the front surface.

6. The method of claim 1, wherein the fifth step floating electrode is a floating electrode

P₀＝G(r)+W_i ^cath；

Has P₀＝W_i ^cath+2G₀+W_i ^RAnd P₀＝G(r)+W_i ^cathObtaining;

G(r)＝2G₀+W_i ^R。

7. a concentric ring-shaped large-area silicon drift detector obtained by the design method of the concentric ring-shaped large-area silicon drift detector as claimed in any one of claims 1 to 5, wherein the concentric ring-shaped large-area silicon drift detector comprises: the cathode structure comprises an anode electrode, a front cathode electrode, a front divider resistor, a front protection ring, a back cathode electrode, a back divider resistor, a front protection ring, a back protection ring, a substrate, a floating electrode on the upper surface, a floating electrode on the lower surface, an upper surface silicon dioxide layer and a lower surface silicon dioxide layer.

8. The concentric ring type large area silicon drift detector of claim 7, wherein said anode electrode is heavily doped N-type semiconductor silicon.

9. The concentric ring type large area silicon drift detector of claim 7 wherein said front cathode electrode is heavily doped P-type semiconductor silicon;

and the reverse cathode electrode is made of heavily doped P-type semiconductor silicon.

10. An X-ray detector using the concentric ring-shaped large-area silicon drift detector as claimed in any one of claims 7 to 9.

Technical Field

The invention belongs to the technical field of detectors, and particularly relates to a concentric ring type large-area silicon drift detector, a design method and application.

Background

Currently, the closest prior art: at present, the research work of a high-energy resolution unit and an SDD array SDD, which are core technologies in the aspect of pulsar navigation in China, is seriously lagged. Domestic research is mainly focused on the aspect of the manufacturing process of a single SDD with a small area. The international research on the X-ray detector is developed towards the technical direction of a silicon drift chamber detector with low power consumption and high energy resolution, so that the important technical requirements of high performance, large area coverage and high availability of an X-ray pulsar autonomous navigation time service system are met. In the family of detectors, concentric ring type detectors have been used for a long time and have excellent performance, but the concentric ring type detectors have the characteristics of small area and need external resistors for voltage division. At present, the international SDD has small area and high price, and no mature technology exists in China.

In view of the above, there are problems at present;

(1) there is a need in the art to improve the construction of a detector so that it does not require an external voltage divider.

(2) At present, domestic SDD research still stays at the stage of small unit area, the research in research colleges and universities and enterprises are highly dependent on import, and once the design and manufacturing technical bottleneck of a large-area SDD unit is broken, the SDD unit plays an important role in the development of Chinese detectors and various fields applying the detectors.

(3) Although the small-area concentric annular cylindrical detector has high symmetry and good electrical performance, the dead zone of the array formed by the small-area concentric annular cylindrical detector is too large, and the performance is reduced.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a concentric ring type large-area silicon drift detector, a design method and application.

The invention is realized in this way, a design method of a concentric ring type large area silicon drift detector, which comprises the following steps:

firstly, calculating the width distribution of electrodes and resistors of a detector;

secondly, calculating the electric field voltage distribution of the silicon drift detector;

thirdly, determining the optimal drift path from the point S1 to the point S2 when the drift electric field and the drift are performed;

fourthly, determining the design of the rear surface of the silicon drift detector;

and fifthly, designing a floating electrode.

Further, the first step calculates the width distribution of the electrode and the resistor of the detector, the voltage distribution is provided by a heavily doped P-type cathode passing through a concentric circle, the heavily doped P-type cathode is formed by ion implantation, and the width of an ion implantation area in the radial direction r is W_r ^cathDefining the width of the concentric circular cathode in the radial direction r; the width of the resistor at the radial r point is W_i ^R，P₀Is the spacing between adjacent cathode rings to a constant value, G (r) is the gap between adjacent implanted regions, G₀The width between the adjacent electrode and the resistor is a certain value;

the distance between the concentric circles is as follows:

P₀＝W_i ^cath+2G₀+W_i ^R；

the resistance value of the resistor is;

where i is denoted as the ith turn, α is associated with the shape of the figure, denotes the perimeter of the figure, and in this configuration it denotes a circular arc

ρ is the resistivity of the resistance;

obtaining;

r₁radius of first ring resistance, W₁ ^RFor the first turn of electricityThe width of the resistor;

the radius of the collecting anode is:

r_iradius representing the i-th turn resistance:

obtaining;

obtaining:

and calculating the resistance width and the cathode width of any circle.

Further, the second step calculates the electric field voltage distribution of the silicon drift detector, the internal drift electric field of the cylindrical silicon drift detector is related to the upper and lower surface potential distributions of the detector, and the negative potential of any point (r, x, theta) in the cylindrical silicon drift detector should satisfy the following conditions:

and

or

wherein x is the coordinate of the thickness direction of the detector, r is the coordinate along the radius direction of the cylinder, and theta is an angular coordinate;

and Φ (r) are the potentials of the front and rear surfaces (x ═ 0 and x ═ d), respectively:

and φ(r)＝φ(r,x＝d)；

since the voltage dividing resistance between the cathode rings is constant in this design, Δ V is constant, Δ V_ARepresenting the potential difference of the front surface, Δ V_BRepresents a negative potential difference:

t represents the thickness of atomic layer deposition:

ρ_ssquare resistivity for resistance:

the voltage Δ V between adjacent cathode rings is;

ΔV＝RI＝EP₀＝constant；

IR (r) is given by ohm's law, EP₀From the electric field integral, where I is the current of the cathode and E is the surface electric field;

the geometry and current of the resistive ring are related to the surface electric field of the SDD:

ρ_sαr_iI＝P₀EW_i ^R。

further, the third step determines the optimum drift path from the point S1 to the point S2 in the drift electric field and drift, according to the equation

The obtained surface electric field distribution is;

obtaining;

the corresponding distribution of the reverse voltage is determined by the distribution of the front voltage, and the distribution of the reverse electric field is as follows:

wherein V₁ ^BThe voltage is applied to the first ring of cathode rings on the reverse side, and gamma is a constant;

the drift electric field in the SDD electron drift channel is;

or:

e (r) is represented by the equation ρ_sαr_iI＝P₀EW_i ^RIt is determined that,is formed by the equation

And (4) determining.

Further, the fourth step determines the design of the rear surface of the silicon drift detector by the equationThe back surface potential was calculated:

a back surface electric field;

the remaining back surface parameters were the same as for the front surface.

Further, the fifth step of floating the electrode

P₀＝G(r)+W_i ^cath；

Has P₀＝W_i ^cath+2G₀+W_i ^RAnd P₀＝G(r)+W_i ^cathObtaining;

G(r)＝2G₀+W_i ^R。

another object of the present invention is to provide a concentric ring-type large-area silicon drift detector obtained by the method for designing the concentric ring-type large-area silicon drift detector, wherein the concentric ring-type large-area silicon drift detector comprises: the cathode structure comprises an anode electrode, a front cathode electrode, a front divider resistor, a front protection ring, a back cathode electrode, a back divider resistor, a front protection ring, a back protection ring, a substrate, a floating electrode on the upper surface, a floating electrode on the lower surface, an upper surface silicon dioxide layer and a lower surface silicon dioxide layer.

Further, the anode electrode is heavily doped N-type semiconductor silicon.

Further, the front cathode electrode is heavily doped P-type semiconductor silicon;

and the reverse cathode electrode is made of heavily doped P-type semiconductor silicon.

Another object of the present invention is to provide an X-ray detector using the concentric ring type large area silicon drift detector.

In summary, the advantages and positive effects of the invention are: the invention starts from a novel structure, novel process integrated design and a particle theory calculation method of light, and solves the problem that concentric ring work needs to be externally connected with electricity through the ALD technologyThe problem of blocking the voltage. The invention is a large-area concentric ring type silicon drift detector, and the radius of the design is larger than 1cm, so the area of the design is larger than 314mm²The area of the array is far larger than that of a small-area detector, and the cost performance of the unit area of the array is higher than that of the small-area detector. The electrical property is better because of the highest symmetry of the circle, the electric field potential distribution in the structure is more uniform, the radius of the small-area concentric ring-shaped detector is about 300 mu m, so the small-area concentric ring-shaped detector needs to be formed into an array for use, but the structure designs the large-area concentric ring-shaped over-drift detector, the radius is more than 1cm, and the area is more than 314mm²The area of the detector is far larger than that of a small-area detector, the detector does not need to be used for forming an array, and the problem that the dead zone is too large when the concentric annular cylindrical detectors form the array is solved.

According to the invention, ALD deposition resistance is utilized to ensure that the concentric ring-shaped detector does not need external resistance to divide voltage, and the spiral ring-shaped detector also has the function of internal voltage division, but the structural design is more excellent and different than the structure and performance of the spiral ring-shaped detector; (1) the spiral ring detector uses spiral ring type cathode ring partial pressure, while the concentric ring using ALD deposition resistance partial pressure uses resistance ring partial pressure, the cathode ring does not participate in the partial pressure. (2) The spiral ring detector utilizes the spiral cathode ring partial pressure to influence the electric field, the potential and the voltage in the collection, while the concentric ring detector utilizing ALD deposition resistance partial pressure uses the resistance ring partial pressure, and the resistance ring does not influence the electric field, the potential and the voltage in the collection (the potential is uniformly changed, the electric field is a fixed value, and the voltage between the cathode rings is a fixed value). The design method of the concentric annular large-area silicon drift detector with the ALD resistor and the floating electrode is as follows; determining the width distribution of the electrode and the resistor of the detector; determining electric fields and electric potentials of the front surface and the rear surface of the silicon drift detector; determining an optimal drift path from point S1 to point S2 in the drift electric field and drift; determining the design of the rear surface of the silicon drift detector; a floating electrode is defined. The structure is mainly based on a new structure and a new process, and the SDD carrier drift behavior rule and the growth of a heavily doped electrode are analyzed. Designing a double-sided electrode which has double-sided correlation, not only keeps a uniform electron drift electric field, but also provides a smooth drift track, and establishing an innovative design and manufacturing mode for efficiently collecting SDD with high energy resolution and high-efficiency of soft X-ray particles with the intensity of 0.5-15 keV.

The structure design of the invention is that a layer of resistance is deposited between the electrodes of the concentric circular silicon drift detector, so that the concentric circular detector can work normally without an additional voltage divider. In the design, the resistance value R of the resistors among all the electrodes is a fixed value, so that uniform voltage division, namely constant delta V, can be realized.

Drawings

FIG. 1 is a schematic structural diagram of a concentric ring-type large-area silicon drift detector provided by an embodiment of the invention;

FIG. 2 is a schematic structural diagram of the reverse side (i.e., the side without the anode) of a concentric ring-type large-area silicon drift detector provided by an embodiment of the invention;

FIG. 3 is a schematic cross-sectional view of a concentric ring-type large area silicon drift detector provided by an embodiment of the present invention;

in the figure: 1. an anode electrode; 2. a front cathode electrode; 3. a front divider resistor; 4. a front side guard ring; 5. a back cathode electrode; 6. a reverse side divider resistor; 7. front and back protection rings; 8. a substrate; 9. a floating electrode on the upper surface; 10. a floating electrode on the lower surface; 11. an upper surface silicon dioxide layer; 12. and a lower surface silicon dioxide layer.

Fig. 4 is a flowchart of a design method of a concentric ring-type large-area silicon drift detector according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Aiming at the problems in the prior art, the invention provides a concentric ring type large-area silicon drift detector, a design method and application thereof, and the invention is described in detail below with reference to the accompanying drawings.

As shown in fig. 1 to fig. 3, a concentric ring type large area silicon drift detector provided by the embodiment of the present invention includes: an anode electrode 1, a front cathode electrode 2, a front divider resistor 3, a front guard ring 4, a back cathode electrode 5, a back divider resistor 6, a front guard ring 7, a substrate 8, a floating electrode 9 on the upper surface, a floating electrode 10 on the lower surface, an upper surface silicon oxide layer 11, and a lower surface silicon oxide layer 12.

In a preferred embodiment of the present invention, the anode electrode 1 is heavily doped N-type semiconductor silicon.

In a preferred embodiment of the invention, the front cathode electrode 2 is heavily doped P-type semiconductor silicon.

In a preferred embodiment of the invention, the opposite cathode electrode 5 is heavily doped P-type semiconductor silicon.

As shown in fig. 4, the method for designing a concentric ring-shaped large-area silicon drift detector provided by the embodiment of the present invention includes the following steps:

s401: calculating the width distribution of the electrode and the resistor of the detector;

s402: calculating the electric field voltage distribution of the silicon drift detector;

s403: determining an optimal drift path from point S1 to point S2 in the drift electric field and drift;

s404: determining the design of the rear surface of the silicon drift detector;

s405: design of floating electrode.

The design method of the concentric ring type large-area silicon drift detector provided by the embodiment of the invention specifically comprises the following steps:

(1) the width distribution of the electrodes and resistors of the detector is calculated, and the voltage distribution is provided by a heavily doped P-type cathode passing through a concentric circle shape, and the P-type heavily doped cathode is formed by ion implantation. As shown in FIG. 1, the width of the ion implantation region at the radial r point is W_r ^cathWhich defines the width of the concentric circular cathode in the radial direction r. The width of the resistor at the radial r point is W_i ^R，P₀Is the spacing between adjacent cathode rings to a constant value, G (r) is the gap between adjacent implanted regions, G₀The width between the adjacent electrode and the resistor is a certain value;

the distance between the concentric circles is as follows:

P₀＝W_i ^cath+2G₀+W_i ^R(1)

the resistance value of the resistor is;

where i is denoted as the ith turn, α is associated with the shape of the figure, denotes the perimeter of the figure, and in this configuration it denotes a circular arc

ρ is the resistivity of the resistance.

Is obtained from the formula (3);

r₁radius of first ring resistance, W₁ ^RIs the width of the first ring of resistors.

The radius of the collecting anode is:

r_iradius representing the i-th turn resistance:

substituting the formula (5) into the formula (3);

substituting the formula (6) into the formula (1) to obtain:

the resistance width and the cathode width of any circle can be calculated by the above formulas.

(2) Calculating the electric field voltage distribution of the silicon drift detector, wherein the internal drift electric field of the cylindrical silicon drift detector is related to the upper surface potential distribution and the lower surface potential distribution of the detector, and the negative potential of any point (r, x, theta) in the cylindrical silicon drift detector satisfies the following conditions:

wherein x is the coordinate of the thickness direction of the detector, r is the coordinate along the radius direction of the cylinder, and theta is the angular coordinate.

And Φ (r) are the potentials of the front and rear surfaces (x ═ 0 and x ═ d), respectively:

since the voltage dividing resistance between the cathode rings is constant in this design, Δ V is constant, Δ V_ARepresenting the potential difference of the front surface, Δ V_BRepresents a negative potential difference:

t represents the thickness of atomic layer deposition:

ρ_ssquare resistivity for resistance:

the voltage (Δ V) between adjacent cathode rings is;

ΔV＝RI＝EP₀＝constant (14)

IR (r) is given by ohm's law, EP₀Derived from the electric field integration. Where I is the current of the cathode and E is the surface field.

Equations (13) and (14) relate the geometry and current of the resistive ring to the SDD surface electric field:

ρ_sαr_iI＝P₀EW_i ^R(15)

(3) determining the optimal drift path from the point S1 to the point S2 in the drift electric field and the drift, wherein the surface electric field distribution obtained according to the equation (12) is;

substituting the formula (15) into the formula (16);

the corresponding distribution of the reverse voltage is determined by the distribution of the front voltage, and the distribution of the reverse electric field is as follows:

wherein V₁ ^BIs the voltage applied to the first ring of cathodes on the opposite side, and gamma is a constant.

The drift electric field in the SDD electron drift channel is;

or:

e (r) is determined by equation (15),

is determined by equation (17).

(4) Design for determining back surface of silicon drift detector

The back surface potential can be calculated from equation (18):

a back surface electric field;

the other parameters of the back surface are the same as those of the front surface, (such as the width of the cathode ring, the width of the resistor, the distance between the cathode rings, the resistor and the distance between the cathode rings, etc. are all the same.

(5) Floating electrode

P₀＝G(r)+W_i ^cath(23)

Is available from (1) and (23);

G(r)＝2G₀+W_i ^R(24)

as can be seen from equation (5), since the resistance width is proportional to the radius, the resistance width increases as the radius increases, and G is also because of₀The value is constant, so G (r) is also proportional to the radius, and as G (r) is increased, a region with zero electric field appears in the center of the substrate, and a floating electrode is added to avoid the region. The floating electrode is an ion implantation region formed by implanting the same ions and concentration as the cathode ring.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.