WO2015102517A1 - Matrix sensor of ionizing radiation - Google Patents

Matrix sensor of ionizing radiation Download PDF

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Publication number
WO2015102517A1
WO2015102517A1 PCT/RU2014/000526 RU2014000526W WO2015102517A1 WO 2015102517 A1 WO2015102517 A1 WO 2015102517A1 RU 2014000526 W RU2014000526 W RU 2014000526W WO 2015102517 A1 WO2015102517 A1 WO 2015102517A1
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WIPO (PCT)
Prior art keywords
sensor
region
regions
substrate
active region
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PCT/RU2014/000526
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French (fr)
Inventor
Vladimir Aleksandrovich ELIN
Mikhail Moiseevich MERKIN
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Otkrytoe Aktsionernoe Obschestvo "Intersoft Evraziya"
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Publication of WO2015102517A1 publication Critical patent/WO2015102517A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/24—Measuring radiation intensity with semiconductor detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
    • H01L31/115—Devices sensitive to very short wavelength, e.g. X-rays, gamma-rays or corpuscular radiation

Definitions

  • the invention pertains to semiconductor devices for conversion of the ionizing radiation into an electrical signal, measuring of which enables the determination of the radiation level and absorbed dose of gamma, proton, electronic and alpha radiations.
  • the invention pertains to semiconductor sensing elements (sensors or detectors) representing a p-i-n diode, intended for the use in various radiation measuring systems, dosimeters, high background radiation indicators and radiometers, including those for individual control of radioactive radiation and for warning of a radiation hazard.
  • sensors based on p-i-n diodes continue being improved with allowance for the modern developments in the microelectronics technology.
  • Semiconductor sensors based on p-i-n diodes have been widely adopted as particle counters and as particle energy measuring devices (spectrometers) with a high resolution. Their operating principle is based on the fact that a charge induced in the counter's substance is collected on the electrodes when an ionizing particle is passing through the sensor (sensing element).
  • a p-i-n-diode silicon, low-noise detector by the planar technology Keremmer J. Fabrication of low noise silicon radiation detectors by the planar process/VNuclear Instruments and Methods. - 1980.-V.169. - P.499 - 502.
  • patent for invention US4442592 discloses the methods for manufacture of detectors by the planar technology for radiation detection, which have semiconductor p-n junctions.
  • the disclosed embodiments of the planar semiconductor diodes are different.
  • a semiconductor detector for X-ray and low-energy gamma radiation detection (patent for invention of the Russian Federation No.2248012, IPC: G01T1/24, H01L31/115), made of monocrystalline silicon and containing a flat signal p +-n junction, around which there are circular guard p+-n junctions with electrodes and a preamplifier, the electrode of the flat signal p+-n junction being connected to the preamplifier input, and the electrode of the inner circular guard p+-n junction being connected to the zero potential bus of the preamplifier is the closest to the technical solution applied for.
  • the invention resolves the problem of improvement in the overall performance of the device by draining the stray current of the guard ring for improvement of the energy resolution and contrast range of the measured energy spectrum.
  • the apparatus is intended for detection of the X-ray and low- energy gamma radiation only.
  • sensitivity enhancement and high rate of detection of the whole spectrum of the ionizing radiation except for the neutron one
  • Object of the invention is to develop a matrix sensor (sensing element) to detect the ionizing radiation of all types of the charged particles and gamma-quanta in a wide range of energies and fluxes.
  • N a + b*C
  • N ⁇ ⁇ T ⁇ ( N, 2 ).
  • noise reduction enables a decrease of the energy threshold detection and increase of the sensitivity of a sensor-amplifier system.
  • the sensor applied for is sensitive to all types of ionizing radiation except for neutrons; lower limit of the detected particles is not more 1 ,000 eV and is practically determined by the noise level of the detecting electronics. There is no upper limit of the energy detection range; release of energy in the sensor becomes for high-energy (relativistic) particles virtually independent on the energy and average value of ionization loss is 388 eV/ ⁇ , or 194 keV for a sensor with the thickness of 500 ⁇ . Detection of a signal at this level is not a problem for up-to-date electronics.
  • the ionizing radiation sensor represents a p-i-n structure by the planar technology, containing a high-resistance silicon substrate of the n-type conductivity, on the front (working) side of which there are:
  • At least two p-regions are located in the central part of the substrate and occupy the most surface area, forming an active region of the sensor and at least two p- regions are in the form of circular elements (guard rings) and are concentrically located in the inactive region on the substrate perimeter with the possibility of a decrease in the surface current value and smooth voltage drop from the active region to the device perimeter.
  • the Si0 2 layer there are windows to ensure the contact between the metal (aluminum metallization) and the p-region; in the passivating layer over the p-region, there are windows for connection of the leads.
  • Windows for connection of the leads are located along the edges of the substrate, in the inactive region of the substrate.
  • P-regions, forming the active region of the sensor have shaped sections along the edges in the form of grooves ensuring the formation of inactive zones for location of the windows for connection of the leads.
  • Total area of the windows for the contact between the metal (aluminum metallization) and the p-region doesn't exceed 1% of the surface area of the active region of the detector in order to prevent the diffusion of aluminum into silicon.
  • a high-purity, floating-zone silicon wafer with a specific resistance of 3 ⁇ 12 kOhm cm and thickness of 250-1000 ⁇ is used as a silicon substrate.
  • Number of circular elements (guard rings), located at a distance from each other, which is increasing from the substrate center to the perimeter, can be equal to 4.
  • the width of the circular elements is equal to 25 ⁇ , the distance between the first and the second element being equal to 40 ⁇ , that between the second and the third being 50 ⁇ , between the third and the fourth being 70 ⁇ , wherein the first element is at a distance of 40 ⁇ from the boundary of the sensitive p-region.
  • the substrate can be selected with the working surface dimensions of up to 102x102 mm , the dimensions of the active region being equal to 100x100 mm 2 , the sensor thickness being equal to 250 ⁇ 1,000 ⁇ (determined by the wafer thickness), and the area occupied by the circular elements being equal to no more than 1 mm on the substrate perimeter.
  • the planar technology method for manufacturing of the ionizing radiation sensor comprises manufacturing of a set of 4 working mask plates for contact photolithography, the first of which is a mask plate for formation of a p+-region, the second is for formation of contacts to the p +-region of the diode and to guard rings on the perimeter of the wafer front side; the third is for Al- metallization; and the fourth is for formation of contacts to metallization.
  • Fig.l schematically shows the device applied for - top view, embodiment of the sensor with two sensitive p-regions, forming the active region of the sensor
  • Figs. 2 and 3 show sections A-A and B-B of Fig. 1 respectively
  • Fig. 4 shows detail C of Fig. 1
  • Fig. 5 shows section D-D of Fig. 4
  • Fig.6 shows a sensor embodiment, in which the active region of the sensor is formed by 8 p-regions, top view
  • Fig. 7 shows section E-E of Fig. 6.
  • the ionizing radiation sensor (sensing element) applied for is a p-i-n structure fabricated by the planar technology.
  • the sensor contains a high-resistance high- purity, floating-zone melting silicon substrate of n-type conductivity 1 (see Fig.1-7), on the front (working) side of which there are p-regions 2, 3; Si0 2 layer (coating) 4; aluminum metallization 5; and passivating (protective) layer 6 from phosphate- silicate glass (Si0 2 +P 2 0 5 ). Thickness of the layers is determined by their manufacturing process and is as a rule not more than 0.5 ⁇ 1.1 ⁇ .
  • P-regions 2 located in the central part of the substrate and occupying the most surface area, form an active region of the sensor. Number of these p-regions can vary from 2 to 128. This number of independent active regions can be more and their number is determined by the reasonableness of the noise reduction only and accordingly by the increase in the number of reading channels. It is evident that increase in the number of reading channels results in increase in the power consumption by the dosimeter-radiometer in general and is reasonably limited by a small number of matrix elements (4 or 8) for domestic appliances and the number of channels can be significantly increased for professional or fixed apparatuses with a large total area of the sensor, where a high measurement accuracy is required. Modern electronics market offers monocrystalline amplifiers with up to 128 channels.
  • At least two p-regions 3 are in the form of circular elements (guard rings) are located in the inactive region on the substrate perimeter around p-regions 2 ensuring a decrease in the surface current value and smooth voltage drop from the active region to the device perimeter.
  • Si0 2 layer 4 there are windows 7 for the contact between the metal (aluminum metallization) and the p-region; in the passivating layer over the p-region, located in the central part of the substrate, there is window 8 for contacting with the p-n-region in the process of testing and window 9 for connection of leads.
  • n + -layer 10 layer with a thickness of 2 ⁇ 4 ⁇ , doped with up to 10 19 atoms of the donor impurity per cm , and aluminum metallization layer 1 1 with a thickness of 0.9 ⁇ 1.1 ⁇ .
  • Total area of windows 7 for the contact between the metal (aluminum metallization) and the p-region doesn't exceed 1% of the surface area of the active region of the detector for prevention of diffusion of aluminum into silicon.
  • Windows 9 for connection of leads are located in the inactive region of the substrate, wherein p-regions 2 have shaped sections along the edges in the form of grooves 12 (see Fig.l) ensuring the formation of inactive regions for the location of windows 9 for connection of leads.
  • a high-purity, floating-zone silicon wafer with a specific resistance of 3 ⁇ 12 kOhnrcm and thickness of 250-1,000 ⁇ is used as a silicon substrate.
  • Number of circular elements (guard rings) 2 located at a distance from each other, which is increasing from the substrate center to the perimeter, is equal to 4. Number and configuration of the guard rings is determined considering the manufacturing process specifics. The system of guard rings must ensure smooth voltage drop from the active region to the sensor edge.
  • the width of the circular elements 3 is equal to 25 ⁇ , the distance between the first and the second element being equal to 40 ⁇ , that between the second and the third being 50 ⁇ , between the third and the fourth being 70 ⁇ , wherein the first element is at a distance of 40 ⁇ from the boundary of the sensitive p-region.
  • These parameters can vary in a range of ⁇ 20%. Accuracy of the said dimensions during fabrication of the sensor is determined by the accuracy of mask plate fabrication and is ⁇ 0.1 ⁇ .
  • the substrate can be selected with the working surface dimensions of up to 102x102 mm , the dimensions of the active region being equal to 100x100 mm , the sensor thickness being equal to 250 ⁇ 1 ,000 ⁇ (determined by the wafer thickness), and the area occupied by the circular elements being equal to no more than 1 mm on the substrate perimeter.
  • the sensors applied for are fabricated by the planar technology, which is a set of manufacturing operations, by means of which the structures of planar semiconductor sensors are formed on one side of a wafer cut from a silicon monocrystal of up to 150 mm in diameter.
  • the invention can be embodied by a technology close to that presented in publications of Kemmer (Kemmer J. Fabrication of low noise silicon radiation detectors by the planar process // Nuclear Instruments and Methods. - 1980. -V.169. - P.499 - 502.).
  • the planar technology is based on creation of regions with different types of conductivity or with different concentrations of the same impurity, together forming the sensor's structure, in the near-surface layer of the substrate. Regions of the structures are formed by local introduction of impurities in the substrate (by means of gas phase diffusion or ion implantation) through a mask (typically from a Si0 2 film), formed by photolithography. By successive conduction of oxidizing (creation of a Si0 2 film), photolithography and doping processes, a doped region of any required configuration is obtained, as well as regions with other type of conductivity (or other impurity concentration).
  • the planar technology enables simultaneous manufacturing of a great number (up to several hundreds and even thousands) of identical discrete semiconductor devices (e.g. sensors) or integrated circuits on one wafer in a single process. Batch processing ensures a good repeatability of the devices parameters and high efficiency at relatively low unit cost.
  • the ionizing radiation sensor works as follows. Quanta of the X-ray and low- energy gamma radiation, entering the sensor's material, react with it that results in the production - depending on the incident quantum energy - of a photoelectron, Compton electron or an electron-positron pair. Probability of this process is 1 ⁇ 3%, but taking into account that the probability of detection of a charged particle (electron, positron, proton, alpha-particle etc.) is equal to 1, this is quite enough for consistent detection of the ionizing gamma radiation, even at the background level, with an accuracy of not less than 20% for 1 ⁇ 2 minutes of measuring. Charged particles penetrate into the active region of the sensor and generate electron-hole pairs in it.
  • Charge carriers disperse under the action of the electric field applied to the semiconductor sensor and move to the electrodes.
  • an electrical impulse in the external circuit of the semiconductor detector, which is detected by a charge-sensitive preamplifier, converted into a voltage drop at its output and then transmitted to a signal processor.
  • Flat signal p +-n junction represents an ion-implanted p+- region with an increased concentration of boron atoms.
  • Circular guard p+-n junctions by the same method as flat signal p+-n junction, located in the central part of the substrate, are arranged around the flat signal p +-n junction, occupying the most part of the substrate (size of the active region was 10 x 10 mm and size of each p-region was 50, 25 and 12.5 mm 2 respectively). Area of the region, occupied with the guard rings on the perimeter, was not more than 1 mm.
  • Metal electrodes were made of aluminum.
  • n + -layer 10 On the substrate side opposite to the front surface, there is high-doped (with up to 10 19 atoms of the donor impurity per cm 3 ) n + -layer 10 with a thickness of 2 ⁇ 4 ⁇ and aluminum metallization layer 11 with a thickness of 0.9 ⁇ 1.1 ⁇ .
  • the minimum width of the perimeter rings was 25 ⁇ in the first m/p; the minimum contact size in the second m p for the formation of contacts to the p+-diode and guard rings on the perimeter of the front side of the wafer was 25 ⁇ 25 ⁇ 2 ; on the perimeter to the guard rings - 10x40 and 40 10 ⁇ ; the minimum width of the rings on the diode perimeter in the third m/p for Al-metallization was 20 ⁇ ; dimensions of the fourth m/p for the formation of contacts to the central region of metallization are not critical.
  • Breakdown voltage not less than - 2 ⁇ VFD
  • Test structures for determination of the specific resistance of the p-region by the four-point method are located on the wafer. Connection of the guard rings was not provided for.
  • the invention thus provides a sensor, which can be used in various devices intended for detection and/or measurement of the ionizing radiation.
  • the sensor applied for has small dimensions - possibility of use in portable, self-contained devices; reliable detection of any ionizing radiation in combination with a wide operating temperature range; high sensitivity (possibility of operation in a gamma- quants counting mode); high radiation resistance of the detector material; wide measuring range; elimination of the necessity for periodic servicing; low power consumption; low-voltage power supply; and low noise characteristics.

Abstract

The sensor contains a high-resistance high-purity, floating-zone melting silicon substrate of n-type conductivity; on whose front side there are p-regions; SiO2 layer; aluminum metallization; and a passivating layer. P-regions, occupying the most surface area, form the active region of the sensor. At least two p-regions in the form of circular elements are located in the inactive region on the perimeter of the substrate around the active region, formed by p-regions, and ensure a decrease in the surface current value and smooth voltage drop from the active region to the device perimeter. In SiO2 layer of, there are windows to ensure the contact between the metal and the p-region; in the passivating layer over the p-region, located in the central part of the substrate, there are window for contacting with the p-n region in the process of testing and windows for connection of the leads.

Description

MATRIX SENSOR OF IONIZING RADIATION
Technical field of the invention
The invention pertains to semiconductor devices for conversion of the ionizing radiation into an electrical signal, measuring of which enables the determination of the radiation level and absorbed dose of gamma, proton, electronic and alpha radiations. In particular, the invention pertains to semiconductor sensing elements (sensors or detectors) representing a p-i-n diode, intended for the use in various radiation measuring systems, dosimeters, high background radiation indicators and radiometers, including those for individual control of radioactive radiation and for warning of a radiation hazard. Currently, sensors based on p-i-n diodes continue being improved with allowance for the modern developments in the microelectronics technology.
Background art
Semiconductor sensors based on p-i-n diodes have been widely adopted as particle counters and as particle energy measuring devices (spectrometers) with a high resolution. Their operating principle is based on the fact that a charge induced in the counter's substance is collected on the electrodes when an ionizing particle is passing through the sensor (sensing element).
Important feature of semiconductor counters is their small size. It has strongly extended the possibilities for application of these detectors not only in the field of experimental physics but also in the engineering - in the devices for process control and in medicine.
A p-i-n-diode silicon, low-noise detector by the planar technology (Kemmer J. Fabrication of low noise silicon radiation detectors by the planar process/VNuclear Instruments and Methods. - 1980.-V.169. - P.499 - 502.) and its further development (patent for invention US4442592) is known in the state-of-the-art. These papers disclose the methods for manufacture of detectors by the planar technology for radiation detection, which have semiconductor p-n junctions. However, the disclosed embodiments of the planar semiconductor diodes are different. A semiconductor detector for X-ray and low-energy gamma radiation detection (patent for invention of the Russian Federation No.2248012, IPC: G01T1/24, H01L31/115), made of monocrystalline silicon and containing a flat signal p +-n junction, around which there are circular guard p+-n junctions with electrodes and a preamplifier, the electrode of the flat signal p+-n junction being connected to the preamplifier input, and the electrode of the inner circular guard p+-n junction being connected to the zero potential bus of the preamplifier is the closest to the technical solution applied for.
The invention resolves the problem of improvement in the overall performance of the device by draining the stray current of the guard ring for improvement of the energy resolution and contrast range of the measured energy spectrum. However, the apparatus is intended for detection of the X-ray and low- energy gamma radiation only. For sensitivity enhancement and high rate of detection of the whole spectrum of the ionizing radiation (except for the neutron one), it is necessary to increase the volume of a semiconductor in order to boost the probability of hitting and dispersion, for example, a gamma-quantum in it and accordingly to increase the rate of counting the radiation flux particles.
Disclosure of the invention
Object of the invention is to develop a matrix sensor (sensing element) to detect the ionizing radiation of all types of the charged particles and gamma-quanta in a wide range of energies and fluxes.
Technical effect, to achieve which the applied patent is aimed at, is the reduction in the time for radiation background measurement, considerable reduction in the size and weight of the sensor, extension of the detected energy range and possibility to detect various types of ionizing radiation while reducing the noise level and increasing the sensor's sensitivity.
It is known that the noise of the charge-sensitive detecting electronics linearly depends on the capacity connected to the amplifier's inputs:
N = a + b*C,
where N - noise level, a and b - constants depending on the amplifier's parameters, C - capacitive input load, wherein b*C > a as a rule. It is also known that the total noise value when adding n-signals is determined by the following expression:
N∑= ^T∑( N,2 ).
Using n-channel detecting electronics, it is thus possible to achieve the reduction in the total noise by up to Vn times. In turn, noise reduction enables a decrease of the energy threshold detection and increase of the sensitivity of a sensor-amplifier system.
The sensor applied for is sensitive to all types of ionizing radiation except for neutrons; lower limit of the detected particles is not more 1 ,000 eV and is practically determined by the noise level of the detecting electronics. There is no upper limit of the energy detection range; release of energy in the sensor becomes for high-energy (relativistic) particles virtually independent on the energy and average value of ionization loss is 388 eV/μπι, or 194 keV for a sensor with the thickness of 500 μπι. Detection of a signal at this level is not a problem for up-to-date electronics.
The set problem is resolved by that the ionizing radiation sensor represents a p-i-n structure by the planar technology, containing a high-resistance silicon substrate of the n-type conductivity, on the front (working) side of which there are:
• p-regions formed by the ion implantation method;
• masking Si02 layer grown;
· aluminum metallization applied; and
• passivating (protective) layer applied.
Thus, at least two p-regions are located in the central part of the substrate and occupy the most surface area, forming an active region of the sensor and at least two p- regions are in the form of circular elements (guard rings) and are concentrically located in the inactive region on the substrate perimeter with the possibility of a decrease in the surface current value and smooth voltage drop from the active region to the device perimeter. In the Si02 layer, there are windows to ensure the contact between the metal (aluminum metallization) and the p-region; in the passivating layer over the p-region, there are windows for connection of the leads. On the substrate side opposite to the front surface, there is an n-region layer and a metal layer. Number of p-regions forming the active region of the sensor is equal to 2", where n = 1 ÷ 8, p-regions advantageously having a rectangular shape and being galvanically isolated from each other and equal in the area. Number of windows for connection of the leads corresponds to the number of these p-regions.
Windows for connection of the leads are located along the edges of the substrate, in the inactive region of the substrate. P-regions, forming the active region of the sensor, have shaped sections along the edges in the form of grooves ensuring the formation of inactive zones for location of the windows for connection of the leads.
Total area of the windows for the contact between the metal (aluminum metallization) and the p-region doesn't exceed 1% of the surface area of the active region of the detector in order to prevent the diffusion of aluminum into silicon.
A high-purity, floating-zone silicon wafer with a specific resistance of 3 ÷ 12 kOhm cm and thickness of 250-1000 μπι is used as a silicon substrate. Number of circular elements (guard rings), located at a distance from each other, which is increasing from the substrate center to the perimeter, can be equal to 4. In one embodiment, the width of the circular elements is equal to 25 μπι, the distance between the first and the second element being equal to 40 μηι, that between the second and the third being 50 μηι, between the third and the fourth being 70 μηι, wherein the first element is at a distance of 40 μηι from the boundary of the sensitive p-region. These parameters can vary in a wide range. Accuracy of the said dimensions during fabrication of the sensor is determined by the accuracy of mask plate fabrication and is ±0.1 μηι. The substrate can be selected with the working surface dimensions of up to 102x102 mm , the dimensions of the active region being equal to 100x100 mm2, the sensor thickness being equal to 250 ÷ 1,000 μηι (determined by the wafer thickness), and the area occupied by the circular elements being equal to no more than 1 mm on the substrate perimeter. This embodiment of the sensor ensures the achievement of the following electrical characteristics: value of the reverse bias of 40 ÷ 200V until the achievement of a full depletion mode depending on the specific resistance and thickness of the sensor; operating mode characterized by the reverse bias at the full depletion; operating voltage determined from the full depletion voltage value (VFD) of Vop =VFD+20V; breakdown voltage of not less than 2-VFD; dark current of no more than 200 nA/cm2 at the operating voltage; the measurements of the said parameters being taken at a temperature of 20±2°C.
The planar technology method for manufacturing of the ionizing radiation sensor comprises manufacturing of a set of 4 working mask plates for contact photolithography, the first of which is a mask plate for formation of a p+-region, the second is for formation of contacts to the p +-region of the diode and to guard rings on the perimeter of the wafer front side; the third is for Al- metallization; and the fourth is for formation of contacts to metallization.
Brief description of the drawings
The invention is further explained with the drawings, where Fig.l schematically shows the device applied for - top view, embodiment of the sensor with two sensitive p-regions, forming the active region of the sensor; Figs. 2 and 3 show sections A-A and B-B of Fig. 1 respectively; Fig. 4 shows detail C of Fig. 1 ; Fig. 5 shows section D-D of Fig. 4; Fig.6 shows a sensor embodiment, in which the active region of the sensor is formed by 8 p-regions, top view; Fig. 7 shows section E-E of Fig. 6.
The following is designated by items on the figures: 1 - high-resistance silicon substrate of n-type conductivity; 2 - p-region, located in the central part of the substrate, forming an active region of the sensor; 3 - p-regions being guard rings; 4 - Si02 layer (coating); 5 - aluminum metallization forming one of the sensor electrodes; 6 - passivating (protective) layer; 7 - windows for the contact between the metal (aluminum metallization) and the p-region, formed in the Si02 layer; 8 - window for contacting with the p-n-region in the process of testing, located in the passivating layer over the p-region in the central part of each matrix element; 9 - windows for connection of leads; 10 - n-region, located on the back side of the substrate; 1 1 - aluminum metallization on back side of the substrate forming the second electrode of the sensor, 12 - shaped sections along the substrate edges in the form of grooves ensuring the formation of the inactive regions for location of windows 9 for connection of leads.
Embodiment of the invention The ionizing radiation sensor (sensing element) applied for is a p-i-n structure fabricated by the planar technology. The sensor contains a high-resistance high- purity, floating-zone melting silicon substrate of n-type conductivity 1 (see Fig.1-7), on the front (working) side of which there are p-regions 2, 3; Si02 layer (coating) 4; aluminum metallization 5; and passivating (protective) layer 6 from phosphate- silicate glass (Si02+P205). Thickness of the layers is determined by their manufacturing process and is as a rule not more than 0.5 ÷ 1.1 μηι.
P-regions 2, located in the central part of the substrate and occupying the most surface area, form an active region of the sensor. Number of these p-regions can vary from 2 to 128. This number of independent active regions can be more and their number is determined by the reasonableness of the noise reduction only and accordingly by the increase in the number of reading channels. It is evident that increase in the number of reading channels results in increase in the power consumption by the dosimeter-radiometer in general and is reasonably limited by a small number of matrix elements (4 or 8) for domestic appliances and the number of channels can be significantly increased for professional or fixed apparatuses with a large total area of the sensor, where a high measurement accuracy is required. Modern electronics market offers monocrystalline amplifiers with up to 128 channels.
At least two p-regions 3 are in the form of circular elements (guard rings) are located in the inactive region on the substrate perimeter around p-regions 2 ensuring a decrease in the surface current value and smooth voltage drop from the active region to the device perimeter. In Si02 layer 4, there are windows 7 for the contact between the metal (aluminum metallization) and the p-region; in the passivating layer over the p-region, located in the central part of the substrate, there is window 8 for contacting with the p-n-region in the process of testing and window 9 for connection of leads. On the substrate side opposite to the front surface, there is high- doped n+-layer 10 layer with a thickness of 2 ÷ 4 μη , doped with up to 1019 atoms of the donor impurity per cm , and aluminum metallization layer 1 1 with a thickness of 0.9 ÷ 1.1 μιη. Total area of windows 7 for the contact between the metal (aluminum metallization) and the p-region doesn't exceed 1% of the surface area of the active region of the detector for prevention of diffusion of aluminum into silicon.
Windows 9 for connection of leads are located in the inactive region of the substrate, wherein p-regions 2 have shaped sections along the edges in the form of grooves 12 (see Fig.l) ensuring the formation of inactive regions for the location of windows 9 for connection of leads. A high-purity, floating-zone silicon wafer with a specific resistance of 3 ÷ 12 kOhnrcm and thickness of 250-1,000 μηι is used as a silicon substrate. Number of circular elements (guard rings) 2, located at a distance from each other, which is increasing from the substrate center to the perimeter, is equal to 4. Number and configuration of the guard rings is determined considering the manufacturing process specifics. The system of guard rings must ensure smooth voltage drop from the active region to the sensor edge.
In one embodiment, the width of the circular elements 3 is equal to 25 μπι, the distance between the first and the second element being equal to 40 μηι, that between the second and the third being 50 μιη, between the third and the fourth being 70 μπι, wherein the first element is at a distance of 40 μιη from the boundary of the sensitive p-region. These parameters can vary in a range of ±20%. Accuracy of the said dimensions during fabrication of the sensor is determined by the accuracy of mask plate fabrication and is ±0.1 μηι. The substrate can be selected with the working surface dimensions of up to 102x102 mm , the dimensions of the active region being equal to 100x100 mm , the sensor thickness being equal to 250 ÷ 1 ,000 μηι (determined by the wafer thickness), and the area occupied by the circular elements being equal to no more than 1 mm on the substrate perimeter. This embodiment of the sensor ensures the achievement of the following electrical characteristics: value of the reverse bias of 40 ÷ 200V for the achievement of a full depletion mode depending on the specific resistance and thickness of the sensor; operating mode characterized by the reverse bias at the full depletion; operating voltage determined from the full depletion voltage value (VFD) of Vop =VFD+20V; breakdown voltage of not less than 2-VFD; dark current of no more than 200 nA/cm at the operating voltage; the measurements of the said parameters being taken at a temperature of 20±2°C. The sensors applied for are fabricated by the planar technology, which is a set of manufacturing operations, by means of which the structures of planar semiconductor sensors are formed on one side of a wafer cut from a silicon monocrystal of up to 150 mm in diameter. Specifically, the invention can be embodied by a technology close to that presented in publications of Kemmer (Kemmer J. Fabrication of low noise silicon radiation detectors by the planar process // Nuclear Instruments and Methods. - 1980. -V.169. - P.499 - 502.).
The planar technology is based on creation of regions with different types of conductivity or with different concentrations of the same impurity, together forming the sensor's structure, in the near-surface layer of the substrate. Regions of the structures are formed by local introduction of impurities in the substrate (by means of gas phase diffusion or ion implantation) through a mask (typically from a Si02 film), formed by photolithography. By successive conduction of oxidizing (creation of a Si02 film), photolithography and doping processes, a doped region of any required configuration is obtained, as well as regions with other type of conductivity (or other impurity concentration). The planar technology enables simultaneous manufacturing of a great number (up to several hundreds and even thousands) of identical discrete semiconductor devices (e.g. sensors) or integrated circuits on one wafer in a single process. Batch processing ensures a good repeatability of the devices parameters and high efficiency at relatively low unit cost.
The ionizing radiation sensor works as follows. Quanta of the X-ray and low- energy gamma radiation, entering the sensor's material, react with it that results in the production - depending on the incident quantum energy - of a photoelectron, Compton electron or an electron-positron pair. Probability of this process is 1 ÷ 3%, but taking into account that the probability of detection of a charged particle (electron, positron, proton, alpha-particle etc.) is equal to 1, this is quite enough for consistent detection of the ionizing gamma radiation, even at the background level, with an accuracy of not less than 20% for 1 ÷ 2 minutes of measuring. Charged particles penetrate into the active region of the sensor and generate electron-hole pairs in it. Charge carriers (electrons and holes) disperse under the action of the electric field applied to the semiconductor sensor and move to the electrodes. As a result, there is an electrical impulse in the external circuit of the semiconductor detector, which is detected by a charge-sensitive preamplifier, converted into a voltage drop at its output and then transmitted to a signal processor.
Test specimens with 2, 4 and 8 elements, in which the semiconductor sensor (detector) is a high-voltage p-i-n diode in the form of a single-sided structure fabricated by the planar technology on a high-purity, floating-zone melting silicon substrate with a specific resistance of 3 ÷ 4 kOhm-cm, with the overall dimensions of 12 x 12mm and thickness of 450 μιη, were created to check the performance efficiency of the sensor. Flat signal p +-n junction represents an ion-implanted p+- region with an increased concentration of boron atoms. Circular guard p+-n junctions by the same method as flat signal p+-n junction, located in the central part of the substrate, are arranged around the flat signal p +-n junction, occupying the most part of the substrate (size of the active region was 10 x 10 mm and size of each p-region was 50, 25 and 12.5 mm2 respectively). Area of the region, occupied with the guard rings on the perimeter, was not more than 1 mm. Metal electrodes were made of aluminum. On the substrate side opposite to the front surface, there is high-doped (with up to 1019 atoms of the donor impurity per cm3) n+-layer 10 with a thickness of 2 ÷ 4 μιη and aluminum metallization layer 11 with a thickness of 0.9 ÷ 1.1 μιη.
Set of 4 working mask plates (m/p) for the contact photolithography was used in manufacturing of the sensor by the planar technology, the first of which is a mask plate for formation of a p+-region, the second is for formation of contacts to the p +- region of the diode and to guard rings on the perimeter of the wafer front side; the third is for Al- metallization; and the fourth is for formation of contacts to metallization. The masks are listed in the order of their use in the process. Thus, the minimum width of the perimeter rings was 25 μηι in the first m/p; the minimum contact size in the second m p for the formation of contacts to the p+-diode and guard rings on the perimeter of the front side of the wafer was 25χ25μπι2; on the perimeter to the guard rings - 10x40 and 40 10 μπι ; the minimum width of the rings on the diode perimeter in the third m/p for Al-metallization was 20 μιη; dimensions of the fourth m/p for the formation of contacts to the central region of metallization are not critical.
The manufactured devices had the following electrical characteristics:
Operating mode - reverse bias at the full depletion. Operating voltage is determined from the full depletion voltage value (V FD) - VOp. =VFD+20V;
Breakdown voltage, not less than - 2■ VFD;
Dark current at operating voltage, no more than - 200 nA/cm2;
All measurements were taken at a temperature of 20±2°C. Test structures for determination of the specific resistance of the p-region by the four-point method are located on the wafer. Connection of the guard rings was not provided for.
The invention thus provides a sensor, which can be used in various devices intended for detection and/or measurement of the ionizing radiation. The sensor applied for has small dimensions - possibility of use in portable, self-contained devices; reliable detection of any ionizing radiation in combination with a wide operating temperature range; high sensitivity (possibility of operation in a gamma- quants counting mode); high radiation resistance of the detector material; wide measuring range; elimination of the necessity for periodic servicing; low power consumption; low-voltage power supply; and low noise characteristics.

Claims

1. An ionizing radiation sensor in the form of a p-i-n structure, containing a high-resistance high-purity, floating-zone melting silicon substrate of n-type conductivity, on the front (working) side of which there are p-regions and a masking coating of Si02; aluminum metallization; passivating layer; on the back side of the substrate, there are a high-doped layer of the n-region and an aluminum metallization; wherein at least two p-regions, forming the active region of the sensor and occupying the most surface area of the substrate, are advantageously rectangular and galvanically isolated from each other; at least two p-regions are made in the form of circular elements and concentrically located in the inactive region on the perimeter of the substrate with a possibility to decrease the surface current value and ensure a smooth voltage drop from the active region to the substrate perimeter, there are windows in the Si02 layer, to ensure a contact between the metal and the p-region; there are windows in the passivating layer, for connection of the leads.
2. Sensor according to claim 1, wherein p-regions forming the active region of the sensor are equal in the area.
3. Sensor according to claim 1, wherein the number of p-regions forming the active region of the sensor is equal to 2", where n = 1 ÷ 8, the number of windows for connection of leads corresponding to the number of these p-regions.
4. Sensor according to claim 1, wherein the structural elements are fabricated by the planar technology with the use he contact photolithography.
5. Sensor according to claim 1, wherein the total area of the windows for ensuring of a contact between the metal and the p-region doesn't exceed 1% of the surface area of the active region of the detector in order to prevent the diffusion of aluminum into silicon.
6. Sensor according to claim 1 , wherein the windows for connection of leads are located along the edges of the inactive region of the substrate with the p- regions, which form the active region of the sensor, having shaped sections along the edges in the form of grooves ensuring the formation of the inactive regions for the location of the windows for connection of leads.
7. Sensor according to claim 1, wherein the number of circular elements (guard rings), located at a distance from each other, which is increasing from the substrate center to the perimeter, is equal to 4.
8. Sensor according to claim 1, wherein the width of the circular elements is equal to 25 μιη, the distance between the first and the second element being equal to 40 μπι, that between the second and the third being 50 μηι, between the third and the fourth being 70 μΐΉ, wherein the first element is at a distance of 40 μπι from the boundary of the sensitive p-region, the said values having a permissible tolerance of 20%.
9. Sensor according to claim 1, wherein the substrate has the working surface dimensions of up to 102x102 mm , the dimensions of the active region being up to 100x100 mm2, the sensor thickness being 250 ÷ 1 ,000 μιη (determined by the wafer thickness); and the area occupied by the circular elements being not more than 1 mm on the substrate perimeter.
10. Sensor according to claim 1, said sensor ensuring the achievement of the following electrical characteristics: value of the reverse bias of 40 ÷ 200V until the achievement of a full depletion mode depending on the specific resistance and thickness of the sensor; operating mode characterized by the reverse bias at the full depletion; operating voltage determined from the full depletion voltage value (VFD) of V0p =VFD+20V; breakdown voltage of not less than 2-VFD; dark current of no more than 200 nA/cm2 at the operating voltage; the measurements of the said parameters being taken at a temperature of 20±2°C.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109690356A (en) * 2016-05-18 2019-04-26 公共联合股份公司欧亚因特软件 The ionizing-radiation sensor of floating zone melting silicon based on p-type conductivity
JP2021528634A (en) * 2018-06-27 2021-10-21 プリズマティック、センサーズ、アクチボラグＰｒｉｓｍａｔｉｃ Ｓｅｎｓｏｒｓ Ａｂ An X-ray sensor, a method for constructing an X-ray sensor, and an X-ray imaging system including such an X-ray sensor.
CN115274912A (en) * 2022-08-01 2022-11-01 中国电子科技集团公司第四十四研究所 High spatial resolution X-ray detector unit, detector and manufacturing method thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4442592A (en) * 1980-01-31 1984-04-17 Josef Kemmer Passivated semiconductor pn junction of high electric strength and process for the production thereof
RU2248012C2 (en) * 2002-06-21 2005-03-10 Институт физико-технических проблем Low-energy gamma-ray emission and x-ray radiation registrar
US20090096046A1 (en) * 2006-03-15 2009-04-16 Koninklijke Philips Electronics N.V. Semiconductor device for radiation detection
RU87569U1 (en) * 2009-06-25 2009-10-10 Федеральное государственное унитарное предприятие "НПО "ОРИОН" GERMANIUM PLANAR PHOTODIOD
EP2535740A1 (en) * 2010-02-12 2012-12-19 Consejo Superior De Investigaciones Científicas (CSIC) Ionizing radiation detector sensitive to the 2d position

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007077286A1 (en) * 2006-01-05 2007-07-12 Artto Aurola Semiconductor radiation detector detecting visible light

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4442592A (en) * 1980-01-31 1984-04-17 Josef Kemmer Passivated semiconductor pn junction of high electric strength and process for the production thereof
RU2248012C2 (en) * 2002-06-21 2005-03-10 Институт физико-технических проблем Low-energy gamma-ray emission and x-ray radiation registrar
US20090096046A1 (en) * 2006-03-15 2009-04-16 Koninklijke Philips Electronics N.V. Semiconductor device for radiation detection
RU87569U1 (en) * 2009-06-25 2009-10-10 Федеральное государственное унитарное предприятие "НПО "ОРИОН" GERMANIUM PLANAR PHOTODIOD
EP2535740A1 (en) * 2010-02-12 2012-12-19 Consejo Superior De Investigaciones Científicas (CSIC) Ionizing radiation detector sensitive to the 2d position

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109690356A (en) * 2016-05-18 2019-04-26 公共联合股份公司欧亚因特软件 The ionizing-radiation sensor of floating zone melting silicon based on p-type conductivity
JP2021528634A (en) * 2018-06-27 2021-10-21 プリズマティック、センサーズ、アクチボラグＰｒｉｓｍａｔｉｃ Ｓｅｎｓｏｒｓ Ａｂ An X-ray sensor, a method for constructing an X-ray sensor, and an X-ray imaging system including such an X-ray sensor.
JP7179090B2 (en) 2018-06-27 2022-11-28 プリズマティック、センサーズ、アクチボラグ X-ray sensor, method for constructing an X-ray sensor, and X-ray imaging system comprising such an X-ray sensor
CN115274912A (en) * 2022-08-01 2022-11-01 中国电子科技集团公司第四十四研究所 High spatial resolution X-ray detector unit, detector and manufacturing method thereof
CN115274912B (en) * 2022-08-01 2024-01-30 中国电子科技集团公司第四十四研究所 High spatial resolution X-ray detector unit, detector and method for manufacturing the same

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