Browse Prior Art Database

Removal of Residue in a Polysulfone Lift Off Process

IP.com Disclosure Number: IPCOM000089047D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Takacs, MA: AUTHOR

Abstract

Lift-off structures used in high temperature semiconductor metallization processes are described in U. S. Patent 4,004,044. A full polysulfone underlay may also be incorporated under the resin glass material which remains very stable at high temperatures.

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Removal of Residue in a Polysulfone Lift Off Process

Lift-off structures used in high temperature semiconductor metallization processes are described in U. S. Patent 4,004,044. A full polysulfone underlay may also be incorporated under the resin glass material which remains very stable at high temperatures.

If a thick coating of resin glass 4 is applied to polysulfone underlay 2, a thin sputtered metal 6 may be deposited without detrimental curling of the resin glass overhang. The polysulfone sidewall then acts as a barrier to the sputter- deposited metal. Any lifting or adhesion failure of the polysulfone 2 to substrate 1 prevents the polysulfone sidewall from acting as a metal stop, allowing lateral penetration of the sputter-deposited metal 6, as shown at region 10 in Fig. 1.

However, the standard residue removal step of dipping the structure into a 10:1 buffered HP solution causes gross adhesion failure and lifting of the polysulfone underlay from the substrate, due primarily to stresses caused by the thick overlying resin glass. This residue removal process is carried out after the resin glass and polysulfone are plasma-etched and prior to metal deposition.

The new residue removal process substitutes a 20-second immersion of the structures in a solution of D.I. H(2)O:NH(4)F:HF in the volume ratio of 200:20:1, respectively.

Subsequent water rinsing and drying leaves no residue and results in no lifting or adhesion failure of the polysulfone underlay, as shown...