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Eliminating the Step in Etched Via Holes Interrupted Sputter Glass Deposition

IP.com Disclosure Number: IPCOM000089710D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Bialko, JA: AUTHOR [+2]

Abstract

The sputter deposition of insulating glass over the metal patterns is usually done in a single continuous deposition process. However, at times it is necessary to interrupt the deposition process before the desired glass thickness is reached. The remaining glass must be deposited in another system or in the same system. Under normal operating conditions, after the second layer of SiO(2) is deposited, the glass at the interface between the two layers is significantly different so that the profile of an etched via hole at this interface has a discontinuity.

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Eliminating the Step in Etched Via Holes Interrupted Sputter Glass Deposition

The sputter deposition of insulating glass over the metal patterns is usually done in a single continuous deposition process. However, at times it is necessary to interrupt the deposition process before the desired glass thickness is reached. The remaining glass must be deposited in another system or in the same system. Under normal operating conditions, after the second layer of SiO(2) is deposited, the glass at the interface between the two layers is significantly different so that the profile of an etched via hole at this interface has a discontinuity.

In a lift-off process, the metal is evaporated at approximately normal incidence. Because of this, the discontinuity in the via hole profile can significantly reduce the metal land thickness at that interface and possibly cause a discontinuous metal land pattern. This is illustrated in the figure, where the second level of metal is discontinuous in the via hole.

This problem is solved by starting the deposition of the second layer in the "zero" mode, i.e., by adjusting the cathode-anode power ration in a driver anode system so that the re-emission rate of glass from the substrate is equal to the deposition rate. This is continued for sufficient time, around 10 minutes, to heat and sputter-clean the surface, thereby assuming a better interface. The power at the anode is then decreased so that the glass starts depositing on the surface i...