International Business Machines Corporation

Arthur Paul Johnson

Chung H Lam

Jed Hickory Rankin

Christa Regina Willets

James William Adkisson

Mark David Jaffe

Robert K Leidy

Jeffrey C Maling

A novel image sensor structure formed on a substrate of a first conductivity type includes a photosensitive device of a second conductivity type and a surface pinning layer of the first conductivity type. A trench isolation region is formed adjacent to the photosensitive device pinning layer. The structure includes a dopant region comprising material of the first conductivity type formed along a sidewall of the isolation region that is adapted to electrically couple the pinning layer to the substrate. The corresponding method facilitates an angled ion implantation of dopant material in the isolation region sidewall by first fabricating the photoresist layer and reducing its size by removing a corner, or a corner portion thereof, which may block the angled implant material. To facilitate the angled implant to the sidewall edge past resist block masks, two methods are proposed: 1) a spacer type etch of the imaged photoresist; or, 2) a corner sputter process of the imaged photoresist.

Masked sidewall implant for image sensor

A square spacer and method of fabrication. The method includes forming a spacer film on a mandrel positioned on a substrate, forming an oxide film on the spacer film, performing a first etching, and performing a second etching. The spacer film is formed on perpendicular first and second sides of the mandrel. A first region and a second region of the spacer film are on the first side and the second side of the mandrel, respectively. The spacer film may include a conductive material such as polysilicon or tungsten. The spacer film may alternatively include an insulative material such as silicon dioxide, silicon nitride, or silicon oxynitride. The oxide film is formed such that a first region and a second region of the oxide film are on the first region and the second region of the spacer film, respectively. The oxide film may include silicon dioxide. The first etching etches away the first region of the oxide film and a portion of the first region of the spacer film. The second etching forms the square spacer by etching away the remaining first region of the spacer film and also a portion of the second region of the oxide film, after which a top surface of the second region of the spacer film and a top surface of the second region of the oxide film are at about the same height above the substrate. The first and second etching may be accomplished by reactive ion etching or chemical downstream etching.

Fabricating a square spacer

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Essex Junction, VT, United States of America

Arthur Paul Johnson