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POLYIMIDE EDGE BEAD REMOVAL BY THERMAL FLATTENING AND/OR EMBOSSING

IP.com Disclosure Number: IPCOM000027505D
Original Publication Date: 1997-Jun-30
Included in the Prior Art Database: 2004-Apr-08
Document File: 2 page(s) / 84K

Publishing Venue

Xerox Disclosure Journal

Abstract

Proposed is a method for removing polyimide bead edges on silicon wafers fabricated for thermal ink jet printheads. Flattening polyimide surfaces in a heated platen press after XEROX DISCLOSURE JOURNAL - Vol. 22, No. 3 May/June 1997 135

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XEROX DISCLOSURE JOURNAL

POLYIMIDE EDGE BEAD REMOVAL BY THERMAL FLATTENING AND/OR EMBOSSING Int. C1. B41j 02/015 Robert M. White
Michael P. Duffy
Robert P. Altavela

Proposed Classification

U. S. C1. 347/020

FIG. 7

74

72

7A ..

72

70 - 70

-

FIG. 2 FIG. 3

Proposed is a method for removing polyimide bead edges on silicon wafers fabricated for thermal ink jet printheads. Flattening polyimide surfaces in a heated platen press after

XEROX DISCLOSURE JOURNAL - Vol. 22, No. 3 May/June 1997 135

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POLYIMIDE EDGE BEAD REMOVAL BY THERMAL FLATTENING AND/OR EMBOSSING (CONT'D)

prebaking and spinning minimize edge beads. Until now, the method of bead edge removal involved isolated wafer edge solvent spraying after prebaking. Removing bead edges by solvent resulted in peripheral cracking during bonding that contributed to die losses in the range of 3 to 4 percent.

Figure 1 illustrates an exemplary press composed of a pair of heated platens 20, a polished PyrexTM or metal plunger 22, a disposable Mylar@ disc 24 (approximately 0.002 inch thick), an O-ring seal 26, and a vacuum port 29. Thermal pressing of a silicon wafer 10 having a prebaked polyimide layer thereon planarizes the surface leaving the polyimide at the periphery flat. The temperature of platens 20 is set to approximately 100°C and a force, in the direction of arrow 30, is applied at 400 psi for approximately 3 minutes. Airflow indicated by arrow 28 preve...