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"Conversion Structure, Image Sensor Assembly and Method for Fabricating Conversion Structure" in Patent Application Approval Process

August 6, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent application by the inventors Ho, Shu-Lin (Taoyuan County, TW); Tang, Pao-Yun (Taoyuan County, TW); Yang, Kei-Hsiung (Taoyuan County, TW), filed on April 12, 2013, was made available online on July 24, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to Architek Material Co., Ltd.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention generally relates to the field of electromagnetic wave sensor assemblies, and more particularly, to a conversion structure, an image sensor assembly and a method of fabrication a conversion structure.

"With the advent of the aging society, the focus on the development of methods for preventive medicare has attracted much attention, especially to the development of equipments for medical diagnostic imaging due to its high technical threshold, high value-added benefit and non-invasive properties. Generally, the types of the medical diagnostic imaging equipments include X-rays systems, electrocardiography (ECG) systems, ultrasonic diagnostic systems, computed tomography (CT) systems, magnetic resonance imaging (MRI) systems, and so forth. Among these types of equipments, X-ray and computed tomography systems are widely used in various medical fields, such as dentistry, orthopedics, chest medicine x-ray radiography and so on.

"Generally, the diagnostic X-ray systems and the computed tomography systems are equipped with an X-rays image sensor assembly so as to convert the X-ray beams penetrating through a human body into corresponding electric signals. The electric signals are then transmitted into circuits and calculated by a processor respectively. In a conventional X-rays image sensor assembly, a conversion structure and a light sensor assembly are incorporated as parts of the X-rays image sensor assembly. The conversion structure can convert X-rays into electromagnetic waves which are detectable by the light sensor assembly. The light sensor assembly can further convert the electromagnetic waves into the corresponding electric signals. The conversion structure described above generally uses a scintillator as a material for converting X-rays into the electromagnetic waves and the composition of the scintillator is usually cesium iodide doped with thallium (CsI:Tl).

"However, there are many drawbacks when using scintillators as main active components in the X-rays image sensor assemblies. For example, in order to prevent toxic heavy metals, i.e. Tl, from causing environmental pollution and from negatively affecting human health, expensive waste gas filtration systems are required for the process of manufacturing the scintillator. In addition, in order to prevent light scattering when the light passes through the scintillator and to improve the resolution of the image sensor assembly, an epitaxial growth process is required, so as to provide an anti-scatter CsI:Tl pillar structure. Furthermore, Tl and CsI can not be mixed uniformly due to their inherent material properties. That is to say, Tl is unevenly distributed within CsI:Tl and causes bad light conversion efficiency. Besides, since CsI:Tl is prone to deliquescence, the sealing degree of the corresponding image sensor assembly needs to be well controlled.

"Therefore, there is a need to provide a conversion structure, an image sensor assembly and a method of fabrication a conversion structure that can overcome the above-mentioned drawbacks."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "To this end, one purpose of the present invention is to provide a conversion structure, an image sensor assembly and a method for fabricating a conversion structure that overcome the drawbacks caused by using CsI:Tl as scintillator.

"According to an embodiment of the present invention, an electromagnetic wave conversion structure is provided. The electromagnetic wave conversion structure consists of a substrate, a plurality of electromagnetic wave conversion units forming a two-dimensional array, a reflective film and a plurality of reflective layers. The substrate has a first surface and a second surface disposed opposite to the first surface. The second surface consists of a plurality of trenches formed in the body of the substrate. Each electromagnetic wave conversion unit is disposed in each of the trenches, and is used to absorb a first electromagnetic wave with a first wavelength and to emit a second electromagnetic wave with a second wavelength. The first wavelength is shorter than the second wavelength. The reflective film, which is transparent or semi-transparent to the first electromagnetic wave, covers the first surface of the substrate and is used to reflect the second electromagnetic wave. Each of the reflective layers used to reflect the second electromagnetic wave is disposed on the sidewall of each trench of the corresponding electromagnetic wave conversion unit.

"According to another embodiment of the present invention, an image sensor assembly is provided. The image sensor assembly includes a conversion structure and a light sensor assembly. The conversion structure includes a first substrate, a plurality of electromagnetic wave conversion elements, a reflective film, and a plurality of reflective layers. The first substrate has a first surface and a second surface opposite to the first surface, wherein the second surface of the substrate has a plurality of trenches penetrating the substrate. The electromagnetic wave conversion elements are respectively disposed in each of the trenches, wherein each of the electromagnetic wave conversion elements is used to absorb a first electromagnetic wave having a first electromagnetic wave wavelength and to emit a second electromagnetic wave having a second electromagnetic wave wavelength, wherein the first electromagnetic wave wavelength is shorter than the second electromagnetic wave wavelength. The reflective film covers the first surface of the substrate, wherein the first electromagnetic wave penetrates the reflective film, and the reflective film is used to reflect the second electromagnetic wave. The reflective layers are respectively disposed between a sidewall of each of the trenches and each of the electromagnetic wave conversion elements, wherein the reflective layers are used to reflect the second electromagnetic waves. The light sensor assembly is disposed opposite to the second surface of the first substrate and includes a plurality of sensing regions. The light sensor assembly includes a second substrate and a plurality of light sensor devices. The light sensor devices are respectively disposed within each of the sensing regions on the second substrate.

"According to still another embodiment of the present invention, a method for fabricating a conversion structure is provided. The method includes the following steps. First, a substrate having a first surface and a second surface opposite to the first surface is provided. A plurality of trenches penetrating the substrate is formed on the second surface. A reflective film is formed to cover the first surface of the substrate. A reflective layer is formed on the sidewall of each of the trenches. An electromagnetic wave conversion element is filled into each of the trenches, wherein each electromagnetic wave conversion element is used to absorb a first electromagnetic wave having a first electromagnetic wave wavelength and to emit a second electromagnetic wave having a second electromagnetic wave wavelength, and the first electromagnetic wave wavelength is shorter than the second electromagnetic wave wavelength.

"The present invention provides a conversion structure, an image sensor assembly and a method for fabricating a conversion structure. Since the currently used epitaxial growth processes and toxic materials are all replaced in the present invention, the corresponding process can be more convenient and eco-friendly. In addition, owing to the specific geometric design of the conversion structure trench and the existence of the reflective film and the reflective layer, the intensity of light having a second wavelength and outputted from the conversion structure into the light sensor assembly can be increased accordingly. In this way, the change in light intensity can be determined by the light sensor devices more easily so as to overcome the drawbacks usually associated to CsI:Tl, such as relatively low light conversion efficiency.

"These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a schematic top view showing a conversion structure according to an embodiment of the present invention.

"FIG. 2 is a schematic cross-sectional diagram taken along a line A-A' in FIG. 1 according to an embodiment of the present invention.

"FIG. 3 is a schematic top view showing a conversion structure according to an embodiment of the present invention.

"FIG. 4 to FIG. 8 are schematic cross-sectional diagrams taken along a line A-A' in FIG. 1 according to embodiments of the present invention.

"FIG. 9 is a schematic perspective diagram showing an image sensor assembly according to an embodiment of the present invention.

"FIG. 10 is a schematic partial cross-sectional diagram showing a light sensor assembly according to an embodiment of the present invention.

"FIG. 11 and FIG. 12 are schematic diagrams showing a layout of conversion units in each sensing region according to different embodiments of the present invention."

URL and more information on this patent application, see: Ho, Shu-Lin; Tang, Pao-Yun; Yang, Kei-Hsiung. Conversion Structure, Image Sensor Assembly and Method for Fabricating Conversion Structure. Filed April 12, 2013 and posted July 24, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4368&p=88&f=G&l=50&d=PG01&S1=20140717.PD.&OS=PD/20140717&RS=PD/20140717

Keywords for this news article include: Electronics, Legal Issues, Electromagnet, Diagnostic Imaging, Architek Material Co. Ltd..

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Source: Electronics Newsweekly


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