Browse Prior Art Database

Magnet in a Plasma Etch System to Improve Uniformity

IP.com Disclosure Number: IPCOM000062243D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bui, VQ: AUTHOR [+4]

Abstract

Plasma etching is widely used in printed circuit board manufacturing to remove polymer residue (smear) from copper inner pl after drilling through holes. Non-uniformity of plasma etching in this process can be a problem. Etch rates vary depending on location within the hole (particularly in high aspect ratio holes), and for parallel plate reactors field effects cause etch rates to be higher near the edge of a board than at the center.

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Magnet in a Plasma Etch System to Improve Uniformity

Plasma etching is widely used in printed circuit board manufacturing to remove polymer residue (smear) from copper inner pl after drilling through holes. Non-uniformity of plasma etching in this process can be a problem. Etch rates vary depending on location within the hole (particularly in high aspect ratio holes), and for parallel plate reactors field effects cause etch rates to be higher near the edge of a board than at the center.

The non-uniformity of plasma etch rates within the hole and within the board can be reduced by applying a magnetic field perpendicular to the electric field created by the reactor electrodes during the plasma process. The magnetic field will act to confine and increase the density of electrons and ions in the plasma so more reactive species are produced and edge effects are reduced.

In general, the electron density in the plasma is much greater at the edge of the board than in the center. The magnetic fields help to evenly distribute electron density around the board which in turn produces a more even distribution of reactive species and so more uniform etching.

Disclosed anonymously.

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