News Column

Patent Application Titled "Image Sensor and Method for Fabricating the Same" Published Online

July 3, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventor LIM, Youn-Sub (Gyeonggi-do, KR), filed on March 14, 2013, was made available online on June 19, 2014.

The assignee for this patent application is Sk Hynix Inc.

Reporters obtained the following quote from the background information supplied by the inventors: "Exemplary embodiments of the present invention relate to a semiconductor device fabrication technology, and more particularly, to an image sensor and a method for fabricating the same.

"A conventional CMOS image sensor is fabricated by the following process: forming a plurality of transistors over a substrate having a photodiode formed for each pixel, forming a multilayer of metal interconnections and a plurality of interlayer dielectric layers over the transistors, and forming a plurality of color filters and a plurality of micro lenses over the interlayer dielectric layers.

"In the conventional CMOS image sensor having the structure fabricated by the above-described process, light is significantly influenced by the metal interconnections until the light reaches the photodiode from the micro lens. Therefore, the photosensitivity and quantum efficiency of the image sensor may decrease. In order to solve such a concern, a backside illumination image sensor receiving light through a backside B thereof has been proposed.

"FIG. 1 is a diagram illustrating a conventional backside illumination image sensor.

"Referring to FIG. 1, an interlayer dielectric layer 13 including metal interconnections 14 is positioned on a frontside F of a substrate 11 having unit pixel regions 101, 102, and 103 each including an isolation layer (not illustrated) and a light receiving element 12. Furthermore, an anti-reflection layer 15 is formed on a backside B of the substrate 11.

"Color filters 16 corresponding to the respective unit pixel regions 101, 102, and 103 are formed over the anti-reflection layer 15. A planarized layer 17 is positioned over the color filters 16. A micro lens 18 is formed over the planarized layer 17 so as to correspond to each of the unit pixel regions 101, 102, and 103.

"The backside illumination image sensor structure may exclude an effect of the metal interconnections, and may improve photosensitivity because the structure has no interlayer dielectric layer. However, since the isolation layer formed by a shallow trench isolation (STI) process and a plurality of photodiodes formed by an ion implant process may not reliably isolated from each other, the improvement of optical crosstalk (X-talk) characteristic may be limited, and the reduction of quantum efficiency (QE) may accompanied."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventor's summary information for this patent application: "Various exemplary embodiments of the present invention are directed to an image sensor that may prevent optical crosstalk and simultaneously increase quantum efficiency, and a method for fabricating the same.

"In an exemplary embodiment of the present invention, an image sensor includes a substrate including a plurality of unit pixel regions; a color filter formed over the substrate so as to correspond to each of the unit pixel regions; and a light absorption unit formed in the substrate under the color filter.

"In another exemplary embodiment of the present invention, an image sensor includes a substrate including a plurality of unit pixel regions; a color filter formed over the substrate; and a light absorption unit formed in the substrate under the color filter, wherein the color filter includes a first color filter, a second color filter, and a third color filter, and the first color filter overlaps the light absorption unit.

"In still another exemplary embodiment of the present invention, an image sensor includes a substrate including a plurality of unit pixel regions; a color filter having a multilayer structure over the substrate; and a light absorption unit formed in the substrate under the color filter, wherein the color filter includes a first color filter, a second color filter, and a third color filter, and the first to third color filters overlap the light absorption unit.

"In still another exemplary embodiment of the present invention, a method for fabricating an image sensor includes forming a substrate including a plurality of unit pixel regions; forming a light absorption unit in the substrate along the boundary between the unit pixel regions; and forming a color filter over the substrate so as to correspond to each of the unit pixel regions, wherein the color filter includes a first color filter, a second color filter, and a third color filter.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a diagram illustrating a conventional backside illumination image sensor.

"FIG. 2 is a cross-sectional view of an image sensor in accordance with a first embodiment of the present invention.

"FIG. 3 is a plan view of a color filter and a light absorption unit of the image sensor in accordance with the first embodiment of the present invention.

"FIGS. 4A and 4B are graphs showing transmittances of color filter materials for each wavelength.

"FIGS. 5A to 5H are cross-sectional views illustrating a method for fabricating the image sensor in accordance with the first embodiment of the present invention.

"FIG. 6 is a cross-sectional view of an image sensor in accordance with a second embodiment of the present invention.

"FIG. 7 is a cross-sectional view of an image sensor in accordance with a third embodiment of the present invention."

For more information, see this patent application: LIM, Youn-Sub. Image Sensor and Method for Fabricating the Same. Filed March 14, 2013 and posted June 19, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=6066&p=122&f=G&l=50&d=PG01&S1=20140612.PD.&OS=PD/20140612&RS=PD/20140612

Keywords for this news article include: Sk Hynix Inc.

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Source: Politics & Government Week


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