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US-12618988-B1 - Radiation detection systems and methods

US12618988B1US 12618988 B1US12618988 B1US 12618988B1US-12618988-B1

Abstract

A method of forming a radiation detector includes forming a stack including a plurality of arrays of radiation detection devices. Forming an array of the plurality of arrays includes forming a polysilicon layer over an interlayer dielectric layer of another array of the plurality of arrays; forming charge storage layers over the polysilicon layer; forming a second polysilicon layer over the charge storage layers; etching the second polysilicon layer to form gate stacks; and depositing an interlayer dielectric disposed on at least three sides of the gate stacks, the interlayer dielectric including a radiation reactive material.

Inventors

  • TIM Z HOSSAIN
  • MARK CLOPTON
  • Clayton Fullwood

Assignees

  • CERIUM LABORATORIES LLC

Dates

Publication Date
20260505
Application Date
20231120

Claims (20)

  1. 1 . A radiation detector comprising: a semiconductor substrate; a radiation detection stack comprising a plurality of arrays of radiation detection devices, each array of the plurality of arrays of radiation detection devices including a set of gate stacks disposed over a plurality of source/drain regions, each gate stack of the set of gate stacks including a gate layer disposed adjacent a charge storage structure, each array including an interlayer dielectric formed of a radiation reactive material, the interlayer dielectric surrounding the set of gate stacks on at least three sides; and a plurality of metal structures disposed over the radiation detection stack, the metal structures defining a set of word line and a set of bit lines.
  2. 2 . The radiation detector of claim 1 , wherein a word line of the set of word lines is in electrical communication with a gate from each array of the plurality of arrays.
  3. 3 . The radiation detector of claim 2 , wherein the source/drain regions are arranged in rows and each row of source/drain regions is uniquely in electrical communication with a bit line.
  4. 4 . The radiation detector of claim 1 , wherein a bit line of the set of bit lines is in electrical communication with a row of the plurality of source/drain regions in each array of the plurality of arrays.
  5. 5 . The radiation detector of claim 4 , wherein each gate layer of the set of gate stacks of each array is uniquely in electrical communication with a word line.
  6. 6 . The radiation detector of claim 1 , wherein the radiation reactive material includes a radiation reactive component selected from boron-10 ( 10 B), lithium-6 ( 6 Li), cadmium-113 ( 113 Cd), gadolinium-157 ( 157 Gd), uranium-235 ( 235 U), and a combination thereof.
  7. 7 . The radiation detector of claim 6 , wherein the radiation reactive material includes at least 50% of the radiation reactive component.
  8. 8 . The radiation detector of claim 7 , wherein the radiation reactive material includes at least 80% of the radiation reactive component.
  9. 9 . The radiation detector of claim 6 , wherein the radiation reactive material includes an oxide, nitride, oxynitride, or carbide of the radiation reactive component.
  10. 10 . The radiation detector of claim 6 , wherein the radiation reactive material includes an oxide, nitride, oxynitride, or carbide of boron-10.
  11. 11 . The radiation detector of claim 10 , wherein the radiation reactive material includes an oxide of boron-10.
  12. 12 . The radiation detector of claim 1 , wherein the charge storage structure includes an oxide of silicon disposed over a nitride of silicon disposed over an oxide of silicon.
  13. 13 . The radiation detector of claim 1 , wherein the charge storage structure includes two charge storage regions within the nitride of silicon.
  14. 14 . A radiation detector comprising: a semiconductor layer comprising first and second source/drain regions and a gate region disposed between the source/drain regions; a gate stack disposed over the gate region of the semiconductor layer, the gate stack including a gate layer disposed adjacent a charge storage structure; and a radiation reactive structure disposed around the gate stack and surrounding the gate stack on at least three sides, the radiation reactive structure formed of a radiation reactive material.
  15. 15 . The radiation detector of claim 14 , wherein the radiation reactive material includes a radiation reactive component selected from boron-10 ( 10 B), lithium-6 ( 6 Li), cadmium-113 ( 113 Cd), gadolinium-157 ( 157 Gd), uranium-235 ( 235 U), and a combination thereof.
  16. 16 . The radiation detector of claim 15 , wherein the radiation reactive material includes at least 50% of the radiation reactive component.
  17. 17 . The radiation detector of claim 16 , wherein the radiation reactive material includes at least 80% of the radiation reactive component.
  18. 18 . The radiation detector of claim 15 , wherein the radiation reactive material includes an oxide, nitride, oxynitride, or carbide of the radiation reactive component.
  19. 19 . The radiation detector of claim 15 , wherein the radiation reactive material includes an oxide, nitride, oxynitride, or carbide of boron-10.
  20. 20 . The radiation detector of claim 14 , wherein the charge storage structure includes two charge storage regions, and wherein the charge storage structure includes an oxide of silicon disposed over a nitride of silicon disposed over an oxide of silicon.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) This application is continuation of U.S. patent application Ser. No. 17/605,070, filed Feb. 22, 2022, which is a 371 of International Application No. PCT/US20/29369, filed Apr. 22, 2020, which claims benefit of U.S. Provisional Application No. 62/837,286, filed Apr. 23, 2019, each of which is incorporated herein by reference in its entirety. FIELD OF THE DISCLOSURE This disclosure, in general, relates to systems and methods for detecting ionizing radiation. BACKGROUND With the occurrence of highly publicized terrorist events, concern for control of hazardous materials, particularly radioactive sources, is high. In particular, sources of neutron radiation are of particular concern. Fissile material can be used to make dirty bombs or nuclear weapons, which if used, could cause extensive loss of life and property damage. However, conventional methods for detecting neutron radiation suffer from sensitivity to gamma radiation and high cost. Conventional technologies for detecting radiation are expensive and cumbersome. Large and expensive equipment is used at major ports to test for the presence of radioactive material. On the other extreme, smaller handheld devices with low sensitivity are available. As such, a less expensive and more accurate solution would be desirable. BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 include illustrations of example workpieces for forming an embodiment of a detection device. FIG. 6 includes an illustration of example portions of a detection device. FIG. 7, FIG. 8, and FIG. 9 include illustrations of example workpieces for forming an embodiment of a detection device. FIG. 10 and FIG. 11 include illustrations of example portions of a detection device. FIG. 12 includes a plan-view illustration of an example detection device array. FIG. 13 and FIG. 14 include illustrations example portions of a detection device. FIG. 15 and FIG. 16 include illustrations of an example portion of a detection system. FIG. 17 includes an illustration of an example configuration of circuitry for a detection system. FIG. 18 includes an illustration of example circuitry for detecting radiation events. FIG. 19 includes an illustration of an exemplary detection system. The use of the same reference symbols in different drawings indicates similar or identical items. DETAILED DESCRIPTION In an exemplary embodiment, a radiation detection system includes an array of radiation detection devices. The devices can be formed using methods similar to those methods used to form memory devices, such as Mirrorbit™ devices. The detection devices include charge storage regions to store a charge above a voltage threshold. When a neutron interacts with a radiation reactive material, the neutron causes a nucleus fission that releases an alpha particle. The alpha particle can disturb the charge stored in the charge storage region, resulting in the stored charge falling below the voltage threshold. When the charge stored in the charge storage region is above the threshold, current through the device can be limited, referred to herein as a “0” state. When the charge drops below the voltage threshold, indicating a detection event, a higher current can flow through the device, referred to herein as a “1” state. In an example, a device includes a gate structure formed over a substrate. In particular, the gate structure can be formed over a portion of the substrate between source and drain regions. The gate structure can include a charge storage structure that, for example, includes a layer of an oxide of silicon disposed on a layer of a nitride of silicon disposed on a layer of an oxide of silicon. Within the gate structure, one or more conductive layers can optionally be disposed adjacent to the charge storage structure. In an example, the conductive layer is a polysilicon layer disposed adjacent the charge storage structure. In an example, a neutron sensitive layer can be disposed around the polysilicon layer. For example, the neutron sensitive layer can be formed of a doped oxide layer, such as a layer doped with boron. In addition, the gate structure can include a gate oxide layer in direct contact with the substrate. The gate structure can further include sidewalls. Exemplary sidewalls can include a nitride of silicon. In particular, an insulative material filling the space between detection devices and surrounding the detection devices on at least three sides can be formed of a radiation reactive material. As illustrated in FIG. 1, an optional insulator layer 104 is disposed over a semiconductor substrate 106. In an example, the semiconductor substrate 106 can be formed of a semiconductor material, such as a silicon-based material, including silicon or silicon germanium, among other