A CMOS-based fluorinated liquid direct conversion x-ray detector

Abstract

The application provides a CMOS-based fluorinated liquid direct conversion type X-ray detector, and specifically comprises a circuit board, a CMOS pixel chip, a fluorinated liquid chamber and a beryllium layer; the CMOS pixel chip is installed on the circuit board, the top layer of the CMOS pixel chip is a bare electrode exposed outside without packaging, and the bare electrode is convenient for sensing electric charge; the fluorinated liquid chamber is a chamber for storing fluorinated liquid, the chamber is installed on the CMOS pixel chip, the chamber can be made of glass, ceramic or other insulating materials around the chamber, the chamber is filled with fluorinated liquid, and the fluorinated liquid directly contacts the bare electrode on the top layer of the CMOS pixel chip; the fluorinated liquid is an inert liquid, has good X-ray absorption capacity, has extremely low dark current, and has good chemical stability without the problem of film peeling; the fluorinated liquid chamber is sealed by the beryllium layer, and the beryllium layer has the minimum shielding effect on X-rays. The application has the beneficial effects that the problems of film peeling of many detectors, uneven crystal growth, and great influence of temperature are solved.

Description

Technical Field

[0001] This invention relates to the field of detectors, and more particularly to a CMOS-based fluoride direct conversion X-ray detector. Background Technology

[0002] X-ray detectors are devices that receive X-rays and convert them into electrical signals. They enable accurate detection of the fine internal structures of samples such as biological organisms and metals, and are widely used in medical, scientific research, nuclear industry, and aerospace fields. X-ray detectors can be classified into indirect conversion detectors and direct conversion detectors based on their energy conversion method. Indirect conversion detectors consist of a scintillation crystal coating (such as cesium iodide) and a thin-film transistor (TFT), charge-coupled device (CCD), or complementary metal-oxide-semiconductor (CMOS) sensor. The operation of an indirect conversion detector generally involves two steps: first, the scintillation crystal coating converts the X-ray energy into visible light; then, the TFT, CCD, or CMOS sensor converts the visible light into an electrical signal. Because visible light is scattered during this process, it affects spatial resolution. Although newer processes fabricate scintillators into columnar shapes to improve X-ray utilization and reduce scattering, the impact of scattered light on spatial resolution cannot be completely eliminated. Direct conversion detectors do not have an intermediate scintillation crystal layer; they directly convert invisible X-rays into electrical signals, which are then read out electronically. Because the intermediate conversion process of the scintillator is unnecessary, there is no light scattering, thus achieving extremely high spatial resolution. Currently, direct-conversion detectors mainly include X-ray detectors coupled with materials such as amorphous selenium, cadmium zinc telluride, cadmium telluride, and perovskite. These detectors have high spatial resolution. Amorphous selenium detectors have strict requirements for the temperature and humidity of the operating environment. When the ambient temperature changes drastically (>5℃ / h), crystallization or even delamination may occur. Delamination is irreversible damage to the detector, and the repair cost is high. When using cadmium zinc telluride, cadmium telluride, or perovskite as detector materials, it is difficult to manufacture seamless, large-area X-ray detectors due to the difficulty in growing large-scale crystals. Due to process issues, crystal particles may also grow unevenly, and the conductivity at the crystal interface may be inhomogeneous, leading to inaccurate detection data. Moreover, the coating process is complex and costly. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a CMOS-based fluorinated liquid direct conversion X-ray detector. This detector uses fluorinated liquid coupled to the chip. As an inert liquid, the fluorinated liquid has excellent X-ray absorption capability, extremely low dark current, and ensures high spatial resolution, good conductivity uniformity, simple fabrication, and low cost. Furthermore, it eliminates the problem of film stripping.

[0004] A CMOS-based direct-conversion X-ray detector for fluorinated liquid mainly includes: a circuit board, a CMOS pixel chip, a fluorinated liquid chamber, and a beryllium layer;

[0005] A CMOS pixel chip is mounted on the upper surface of a circuit board. The top layer of the CMOS pixel chip has exposed electrodes for sensing charges. A fluorinated liquid chamber is mounted on the upper surface of the CMOS pixel chip to store fluorinated liquid. The fluorinated liquid chamber is filled with fluorinated liquid, which is in direct contact with the exposed electrodes on the top layer of the CMOS pixel chip. A beryllium layer is located on the top layer of the fluorinated liquid chamber for sealing.

[0006] When X-rays pass through an object, they enter the fluorinated liquid chamber through the beryllium layer and react with the fluorinated liquid to produce positive and negative ions. At the same time, a negative high voltage is applied to the beryllium layer, and an electric field is formed under the action of the negative bias voltage. The negative ions are collected by the array of CMOS pixel chips under the action of the electric field, and the X-rays are identified by polling the output through the readout circuit.

[0007] Furthermore, the fluorinated liquid chamber is surrounded by glass, ceramic, or other insulating materials.

[0008] Furthermore, the beryllium layer is located on the top layer of the fluorinated liquid chamber and is used to seal the fluorinated liquid chamber.

[0009] Furthermore, the fluorinated liquid is FC40 fluorinated liquid.

[0010] Furthermore, the FC40 fluorinated liquid is a thermally and chemically stable dielectric liquid with good X-ray absorption capability and low dark current, which is used to ensure that the detector has high spatial resolution.

[0011] Furthermore, the pins of the CMOS pixel chip are soldered to the circuit board via metal wires.

[0012] The beneficial effects of the technical solution provided by this invention are as follows: This invention discloses a CMOS-based fluorinated liquid direct conversion X-ray detector, which uses FC40 fluorinated liquid coupled with a CMOS pixel chip. When X-rays pass through an object, they enter the fluorinated liquid chamber through a beryllium layer and react with the fluorinated liquid to generate positive and negative ions. Simultaneously, a negative high voltage is applied to the beryllium layer, forming an electric field under the influence of the negative bias. The negative ions are collected by the CMOS pixel chip array under the influence of the electric field, and the X-rays are identified by polling the output through a readout circuit. The fluorinated liquid directly generates an electrical signal after being exposed to X-rays, which can be read by the CMOS pixel array to obtain a digital image. FC40 fluorinated liquid solves many problems of detectors such as film removal, uneven crystal growth, and large temperature influence. The top electrode of the CMOS pixel chip is exposed and directly contacts the fluorinated liquid without encapsulation, improving the efficiency of signal detection. The beryllium layer on top of the fluorinated liquid chamber seals the fluorinated liquid chamber, which can reduce the shielding effect against X-rays. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0014] Figure 1 This is a structural diagram of a CMOS-based fluorinated liquid direct conversion X-ray detector in an embodiment of the present invention. Detailed Implementation

[0015] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0016] Please refer to Figure 1 , Figure 1 This is a structural diagram of a CMOS-based fluorinated liquid direct conversion X-ray detector in an embodiment of the present invention, specifically including: circuit board 1, CMOS pixel chip 2, fluorinated liquid chamber 3, and beryllium layer 4;

[0017] A CMOS pixel chip 2 is mounted on the upper surface of a circuit board 1. The top layer of the CMOS pixel chip 2 has an exposed electrode for sensing charge. A fluorinated liquid chamber 3 is mounted on the upper surface of the CMOS pixel chip 2 for storing fluorinated liquid. The fluorinated liquid chamber 3 is filled with fluorinated liquid, and the fluorinated liquid is in direct contact with the exposed electrode on the top layer of the CMOS pixel chip 2.

[0018] When X-rays pass through an object, they enter the fluorinated liquid chamber 3 through the beryllium layer 4 and react with the fluorinated liquid to generate positive and negative ions. At the same time, a negative high voltage is applied to the beryllium layer, and an electric field is formed under the action of the negative bias voltage. The negative ions are collected by the array of CMOS pixel chips 2 under the action of the electric field, and the X-rays are identified by polling the output through the readout circuit.

[0019] The CMOS pixel chip 2 is mounted on the circuit board 1. The top layer of this CMOS pixel chip has exposed electrodes on the outside without encapsulation, which facilitates the sensing of charges.

[0020] The fluorinated liquid chamber 3 is used to store the fluorinated liquid. This chamber is mounted on the CMOS pixel chip. The chamber's perimeter can be made of glass, ceramic, or other insulating materials. The chamber is filled with fluorinated liquid, which directly contacts the exposed electrodes on the top layer of the CMOS pixel chip. The pins of the CMOS pixel chip are bonded to the pads on the circuit board via metal wires. The fluorinated liquid is a thermally and chemically stable dielectric liquid. As an inert liquid, it has excellent X-ray absorption and extremely low dark current. It also does not suffer from delamination issues, ensuring high spatial resolution and uniform conductivity in the detector. Furthermore, it is simple to manufacture, low in cost, and chemically stable.

[0021] The fluorinated liquid chamber 3 is sealed with a beryllium layer 4. Metallic beryllium is the lightest (lowest atomic number) stable metal, and it has the least shielding effect against X-rays.

[0022] When X-rays pass through the object, they enter the chamber through the beryllium layer 4 and react with the FC40 electronic fluorinated liquid to generate positive and negative ions. A negative high voltage is applied to the beryllium layer, and an electric field is formed under the action of the negative bias voltage. The negative ions are collected by the CMOS pixel array under the action of the electric field and output through the readout circuit.

[0023] The beneficial effects of this invention are as follows: This invention discloses a CMOS-based fluorinated liquid direct conversion X-ray detector, which uses FC40 fluorinated liquid coupled with a CMOS pixel chip. When X-rays pass through an object, they enter the fluorinated liquid chamber through a beryllium layer and react with the fluorinated liquid to generate positive and negative ions. Simultaneously, a negative high voltage is applied to the beryllium layer, forming an electric field under the influence of the negative bias. The negative ions are collected by the CMOS pixel chip array under the influence of the electric field, and the X-rays are identified by polling the output through a readout circuit. The fluorinated liquid directly generates an electrical signal after being exposed to X-rays, which can be read by the CMOS pixel array to obtain a digital image. FC40 fluorinated liquid solves many problems of detectors such as film removal, uneven crystal growth, and high susceptibility to temperature. The top electrode of the CMOS pixel chip is exposed and directly contacts the fluorinated liquid without encapsulation, improving the efficiency of signal detection. The beryllium layer on top of the fluorinated liquid chamber seals the chamber, reducing the shielding effect against X-rays.

[0024] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A CMOS-based fluorinated liquid direct conversion X-ray detector, characterized in that: include: Circuit board, CMOS pixel chip, fluorinated liquid chamber and beryllium layer; A CMOS pixel chip is mounted on the upper surface of a circuit board. The top layer of the CMOS pixel chip has an exposed electrode for sensing charge. A fluorinated liquid chamber is mounted on the upper surface of the CMOS pixel chip for storing fluorinated liquid. The fluorinated liquid chamber is filled with fluorinated liquid, and the fluorinated liquid is in direct contact with the exposed electrode on the top layer of the CMOS pixel chip. When X-rays pass through an object, they enter the fluorinated liquid chamber through the beryllium layer and react with the fluorinated liquid to produce positive and negative ions. At the same time, a negative high voltage is applied to the beryllium layer, and an electric field is formed under the action of the negative bias voltage. The negative ions are collected by the array of CMOS pixel chips under the action of the electric field, and the X-rays are identified by polling the output through the readout circuit.

2. The CMOS-based fluoride direct conversion X-ray detector as described in claim 1, characterized in that: The fluorinated liquid chamber is surrounded by glass, ceramic or other insulating materials.

3. The CMOS-based fluoride liquid direct conversion X-ray detector as described in claim 1, characterized in that: The beryllium layer is located on the top layer of the fluorinated liquid chamber and is used to seal the fluorinated liquid chamber.

4. The CMOS-based fluoride liquid direct conversion X-ray detector as described in claim 1, characterized in that: The fluorinated liquid is FC40 fluorinated liquid.

5. A CMOS-based fluoride liquid direct conversion X-ray detector as described in claim 4, characterized in that: The FC40 fluorinated liquid is a thermally and chemically stable dielectric liquid with good X-ray absorption and low dark current, which is used to ensure that the detector has high spatial resolution.

6. The CMOS-based fluoride liquid direct conversion X-ray detector as described in claim 1, characterized in that: The pins of the CMOS pixel chip are soldered to the circuit board via metal wires.

Images