The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 27, 2003
Filed:
Jun. 12, 2001
Sheng-Hsiung Yang, Hsin-Chu, TW;
United Microelectronics Corp., Hsin-Chu, TW;
Abstract
A method of reducing leakage current of a photodiode on a semiconductor wafer. The semiconductor wafer has a p-type substrate, a photosensing area, and at least one shallow trench surrounding the photosensing area. First, a doped polysilicon layer containing p-type dopants is formed in the shallow trench. Then, the p-type dopant in the doped polysilicon layer is caused to diffuse into the p-type substrate to form a p-type doped region surrounding a bottom of the shallow trench and walls of the shallow trench. After that, the doped polysilicon layer is removed and an insulator material is filled into the shallow trench to form a shallow trench isolation (STI) structure. Finally, an n-type doped region is implanted to form a photosensor. Here, the p-type doped region in the photosensing area is used to decrease the electric field surrounding the photosensing area and decrease the leakage current.