JPH0210973A - X-ray image pickup element - Google Patents

Abstract

PURPOSE:To attain an X-ray image pickup element with long service life in which a soft X-ray area is used symmetrically by forming a fluorescent substance suitable for the spectral sensitivity characteristic of a solid-state image pickup element in a thickness nearly absorbing the X-ray completely. CONSTITUTION:A fluorescent layer 201 made of halogen barrium (samarium) is formed directly to the surface of an image pickup element 202. In the case of forming a thin film, the vacuum vapor deposition method was used. In this case, the sublimation method is applied in the fluoride group and the flash method is used for other halogen chemical compound so as to form the thin film of 30mum or below uniformly as a fluorescent substance 201. The film thickness of 10mum is adopted for the element because the soft X-ray region is formed symmetrically. Thus, the transmission of X-ray is suppressed to be 0.01% or below, the damage to a solid-state image pickup element is eliminated almost completely and the deterioration in the resolution is suppressed to be 20lp/mm or over. A dry nitrogen gas thin layer is formed to the space with a window 102 protecting the fluorescent substance 201 to prevent damage due to environmental factors.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a widely used X-ray imaging device.

[Summary of the Invention 1 The present invention protects the solid-state imaging device by forming a thin film of barium halide (samarium) phosphor having an emission band of 600 nm or more in imaging in the soft X-ray region. materials with high X-ray transmittance and high radiation resistance (Be, C single crystal, polyimide film),
The present invention relates to a compact, long-life, and high-resolution X-ray imaging device that is integrated with a window used as a window material.

[Prior art 1] Conventionally, a phosphor was attached to a solid-state image sensor, and a device for converting radiation into visible and infrared light to capture an image was developed using the Japanese Patent Publication No. 5
No. 8-37702 discloses the phosphor with a metal back.

[Problem to be solved by the invention 1 However, conventional solid-state imaging devices with phosphors are made of materials that are weak against X-rays, and even in the formation of the phosphor layer, high resolution cannot be achieved. It is not a method that can be used.

In other words, the most important requirement for X-ray imaging using a solid-state imaging device is long life. For this reason, if the X-rays are not completely converted by the phosphor layer, image burnout will occur in the solid-state image pickup device using silicon. In addition, the phosphor layer must also avoid damage such as coloring due to X-rays. Therefore, it is necessary to use a phosphor layer that is resistant to X-rays and almost completely converts it into visible or infrared light. , in the conversion process,
The challenge is to reduce blurring of images to the maximum extent possible.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention is compatible with the spectral sensitivity characteristics of solid-state imaging devices using Zinocon, which is currently commonly used as a phosphor. A single layer of this phosphor was formed using barium halide (samarium) which is resistant to X-rays. Furthermore, it was decided to eliminate blur in the phosphor layer by keeping the film thickness to 30 μm or less.

[Function] By using the above means, in this invention, the following effects are obtained by using barium halide (samarium):
Since this substance has an emission band at E300 nm or higher, particularly at 700 nm or higher, the spectral sensitivity of the silicon-based material almost coincides with the optimum 800 nm range.

In addition, the success of film formation by vapor deposition has made it possible to form a thin and uniform layer consisting only of phosphor, resulting in a longer lifespan against X-rays. In addition, it has become possible to control the film thickness to 30 μm or less, which maintains high resolution.

〔Example〕

Embodiments of the invention will be described with reference to the following drawings and tables.

In FIG. 1, a window 102 is attached to the light-receiving surface side of the main body 101 of the solid-state image sensor in order to protect the phosphor layer formed by vapor deposition on the light-receiving surface of the image sensor. The window material for this window needs to be both X-ray resistant and highly X-ray transparent. Form body layers. A vacuum evaporation method was used to form the thin film. At this time, in the case of fluorides, a sublimation method was used, and in the case of other halides, a thin film of 30 μm or less was uniformly formed as the phosphor 201 by a flash method. Since the X-ray region was symmetrical, the film thickness was set to 10 μm. As a result, the transmission of X-rays is suppressed to 0.01% or less, almost completely eliminating damage to the solid-state image sensor, and reducing resolution deterioration by 201%.
2 p/mm or more.

In addition, this base material, excluding fluoride base materials, is susceptible to moisture and carbon dioxide gas, so a thin layer of dry nitrogen gas is created in the space between the window 102 that protects the phosphor 201 and damage caused by environmental factors. prevented.

Furthermore, in order to prevent X-ray damage to the main body of the imaging device and others due to transmission, the surface was covered with an X-ray shield 203 made of polyimide resin about 1 mm thick.

As a result of the above, an integrated compact and long-life X#il imaging element was completed.

[Effects of the Invention] As explained above, the present invention has a 101p/ Beyond mm ^,
We succeeded in creating a long-life X-ray imaging device with a resolution of approximately 30-40°C p/mm.

[Brief explanation of the drawing]

FIG. 1 is an external view of an X-ray IR imaging device completed according to the present invention, and FIG. 2 is a sectional view simply showing an embodiment of the main components of this X-ray imaging device.・・Main body・・Window・・Fluorescent body・・Image sensor・・X-ray shield

Claims (1)

[Claims] Barium halide (samarium) is placed on the solid-state image sensor.
An X-ray imaging device characterized by forming a phosphor layer of.