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Insulating Thin-Film Defect Monitor

IP.com Disclosure Number: IPCOM000040715D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Faix, W: AUTHOR [+4]

Abstract

Insulating thin-films of silicon dioxide, silicon nitride and the like are essential as a dielectric in the gate region of MOS devices. They are also used as an insulating barrier in VLSI and ULSI technology. Ever increasing integration densities and circuit speeds necessitate smaller and thinner structures (submicron technology), but decisive increases in circuit speed are obtainable only with thin SiO2 and Si3N4 layers. The main difficulty with very thin layers is the formation of small holes which adversely affect the electrical properties. For process development and process quality control, it is necessary to have a monitor which detects defects impairing the functionality of a thin insulating and/or dielectric layer. The main defects, such as holes, etc.

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Insulating Thin-Film Defect Monitor

Insulating thin-films of silicon dioxide, silicon nitride and the like are essential as a dielectric in the gate region of MOS devices. They are also used as an insulating barrier in VLSI and ULSI technology. Ever increasing integration densities and circuit speeds necessitate smaller and thinner structures (submicron technology), but decisive increases in circuit speed are obtainable only with thin SiO2 and Si3N4 layers. The main difficulty with very thin layers is the formation of small holes which adversely affect the electrical properties. For process development and process quality control, it is necessary to have a monitor which detects defects impairing the functionality of a thin insulating and/or dielectric layer. The main defects, such as holes, etc., in insulating layers are conductive and thus detectable by the method described below. The wafer, whose front face is provided with a thin insulating layer, is contacted through the silicon, and the bared silicon on the back side of the wafer is coated with a suitable resist. Then, the wafer is suspended as a cathode in a suitable electrolytic silver bath. A carbon or platinum electrode serves as an anode. Upon application of a low single-phase AC voltage of, say, 5 V, conductive defects lead to an electrolysis, with silver being deposited in the region of the defects. Method A operates such that, in addition to inactive Ag, radioactive Ag- 108 and Ag-110, respectively,...