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Plasma Etching Process of Semiconductor Structures to Expose Metal

IP.com Disclosure Number: IPCOM000059945D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Marchetti, P: AUTHOR [+2]

Abstract

The plasma etching process described permits selective removal of passivation layers, such as silicon dioxide and silicon nitride, from semiconductor chips. The important feature of this technique is that the "unlayering" is accomplished in an anisotropic (directional) fashion, which allows underlying structures to be exposed for analysis without altering important characteristics of those structures. This technique employs a parallel plate plasma etching system with radio frequency power applied between two electrodes. The electrodes are in a partially evacuated chamber through which a mixture of oxygen and carbon tetrafluoride is pumped. The radio frequency ionizes the gas mixture to form a plasma which produces the desired etching action.

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Plasma Etching Process of Semiconductor Structures to Expose Metal

The plasma etching process described permits selective removal of passivation layers, such as silicon dioxide and silicon nitride, from semiconductor chips. The important feature of this technique is that the "unlayering" is accomplished in an anisotropic (directional) fashion, which allows underlying structures to be exposed for analysis without altering important characteristics of those structures. This technique employs a parallel plate plasma etching system with radio frequency power applied between two electrodes. The electrodes are in a partially evacuated chamber through which a mixture of oxygen and carbon tetrafluoride is pumped. The radio frequency ionizes the gas mixture to form a plasma which produces the desired etching action. Traditional methods, such as wet etching or dry plasma etching in a barrel reactor using CF4/O2 gas mixtures, tend to be isotropic and make it difficult to evaluate certain types of defects, such as inclusions or voids, in the metal structures. In the parallel-plate system the sample is exposed to energetic ion bombardment as well as the chemically reactive species. The ion bombardment causes the etch front to move fastest perpendicular to the surface. The system can be run either in the plasma or reactive ion etch modes. The critical parameters which need control are the chamber pressure, gas flow, RF power, sample temperature and etch time. It is important t...