Method of detecting a thin insulating film over a conductor

摘要

A method of detecting the presence of a thin insulating film having a thickness less than about 500 angstroms disposed over a surface of a conductor comprises positioning a conductive grid adjacent the surface of the insulating film. Ions of one type polarity are deposited adjacent the insulating film through openings in the grid, the openings in the grid being sufficiently small to limit the surface charge voltage on the insulating film to less than about 50 volts. After immersing the insulating film in a suspension of charged particles having a polarity opposite to the one type, the deposition of charged particles adjacent the conductor surface then indicates the presence of the insulating film.