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Modified in Situ Sputter Clean Process

IP.com Disclosure Number: IPCOM000059723D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Trumpp, HJ: AUTHOR

Abstract

Different modifications of a sputter clean unit, such as having a calotte-shaped wafer dome without holes, using backers shielding the backside of the wafers from the plasma, and selecting a specific distance ratio of the dome backside and the wall to the dome frontside and the wall, permit using the sputter clean process also for metallizations in conjunction with lift-off photoresist structures having a high temperature sensitivity. In a modified arrangement, the plasma is separated into a "hard" and a "soft" plasma, the former, burning between the dome backside and the wall of the probe chamber, sputtering aluminum and reducing the water vapor partial pressure, and the latter, burning on the dome frontside, removing aluminum oxide surface layers.

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Modified in Situ Sputter Clean Process

Different modifications of a sputter clean unit, such as having a calotte-shaped wafer dome without holes, using backers shielding the backside of the wafers from the plasma, and selecting a specific distance ratio of the dome backside and the wall to the dome frontside and the wall, permit using the sputter clean process also for metallizations in conjunction with lift-off photoresist structures having a high temperature sensitivity. In a modified arrangement, the plasma is separated into a "hard" and a "soft" plasma, the former, burning between the dome backside and the wall of the probe chamber, sputtering aluminum and reducing the water vapor partial pressure, and the latter, burning on the dome frontside, removing aluminum oxide surface layers. In an embodiment that has been reduced to practice, wafer backers with a thickness of about 5 mm and a spacing of about 1 mm from the wafers shield the latter from the hard plasma and the heat emitted by it. This keeps the heating of the wafers so low that even sputter clean times of about 5 minutes do not cause the temperature-sensitive photoresist to flow, as is generally observed at temperatures of about 115OEC. To effectively separate the hard and the soft plasma, care must be taken that all positions of the dome are provided with backers, i.e., that the dome is totally closed. Even more significant for the formation of the hard and the soft plasma are the dimensions within t...