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Endpoint Detection of Metal Stud Exposure Under Polyimide During Laser Etching

IP.com Disclosure Number: IPCOM000039653D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Dreyfus, RW: AUTHOR [+2]

Abstract

A method has been proposed for the endpoint detection of Al or other metal studs under a variable thickness of polyimide (PI), or other films, during laser ablation of semiconductor devices. The proposal suggests applying laser-induced fluoresence of Al or other metal atoms as an endpoint detector for laser etching of organic films into Al studs. In the technique a portable, tunable dye laser 1 (Fig. 1) is directed above the substrate material 2 which is covered by polyimide with underlying Al studs. The excimer laser beam 3 is used to etch variable thickness films or PI. As the studs are uncovered, Al atoms are ablated into the gas phase and their presence indicates the studs are uncovered.

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Endpoint Detection of Metal Stud Exposure Under Polyimide During Laser Etching

A method has been proposed for the endpoint detection of Al or other metal studs under a variable thickness of polyimide (PI), or other films, during laser ablation of semiconductor devices. The proposal suggests applying laser- induced fluoresence of Al or other metal atoms as an endpoint detector for laser etching of organic films into Al studs. In the technique a portable, tunable dye laser 1 (Fig. 1) is directed above the substrate material 2 which is covered by polyimide with underlying Al studs. The excimer laser beam 3 is used to etch variable thickness films or PI. As the studs are uncovered, Al atoms are ablated into the gas phase and their presence indicates the studs are uncovered. Since the Al atoms are detected above the substrate, interference from the excimer laser is minimal because of the widely differing wavelengths of the two lasers. The Al atoms are detected by optically pumping the Al resonance transition through an imaging system 4 and detecting the subsequent fluoresence using a monochromator 5 with a photomultiplier 6, or photodiode array. A boxcar integrater 7, or a gated detector, is used to lock onto the pulsed fluorescence, thereby providing very high sensitivity to detect a precise endpoint on the recorder 8.

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