Well to substrate photodiode for use in a CMOS sensor on a salicide process

• US 6,040,592 A
• Filed: 06/12/1997
• Issued: 03/21/2000
• Est. Priority Date: 06/12/1997
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Clark, Lawrence T., Hoffman, Eric J., Bawolek, Edward J., Beiley, Mark A., McDaniel, Bart
• Primary Examiner(s): Jackson, Jr., Jerome
• Application Number:
  US08/873,987
• Time in Patent Office: 1,013 Days
• Field of Search: 257/291, 257/292, 257/436, 257/443, 257/465, 257/461
• US Class Current: 257/292
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 31/1136 the device being a metal-insulator-semiconductor field-effect transistor
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

An image sensor having a well-to-substrate diode as the photodetector. In a preferred embodiment, a modern salicided (CMOS) process is utilized to manufacture the image sensor. The field oxide region above the diode junction is transparent to visible light, thus allowing the photodiode competitive quantum efficiency as compared to devices having source/drain diffusion-to-substrate photodiodes fabricated on a non-salicided process. The photodiode can be integrated as part of a sensor array with digital circuitry using a relatively unmodified digital CMOS process. Furthermore, the structure allows the optical properties of the photodiode to be engineered by modifying the well without deleterious effects, to approximate a first order, on the characteristics of a FET built in another identical well.

Claims