Charge-coupled device with focused ion beam fabrication

US4967250A · kind A · utility

Assignee

• Hughes Aircraft Company · US

Inventors

• William M. Clark, Jr. · Thousand Oaks, US
• Robert H. Walden · Newbury Park, US
• Mark W. Utlaut · Scappoose, US

Key dates

• Filing date: Oct 23, 1989
• Grant date: Oct 30, 1990
• Expiry date: Oct 23, 2009

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D62/335

Abstract

A charge-coupled device (CCD) is provided with a dopant implant gradient, lateral channel stops and blocking implants by means of a focused ion beam (FIB). The FIB is repeatedly scanned across each cell of the CCD as a succession of overlapping but discrete implant scans. The doping levels of the FIB implants accumulate to a stepwise approximation of a desired dopant density profile, the widths of the steps being no greater than about half the widths of the discrete FIB implants. With a FIB pixel of about 750-1,500 Angstroms, the widths of the steps are preferably about 250-500 Angstroms; the dimension of the cells in the dopant gradient direction can be made less than about 5 microns. The lateral channel stops and back blocking implants can be as narrow as single FIB pixel widths, thus freeing up more of the cell for charge carrying capacity.