Endpoint Detection of Metal Stud Exposure Under Polyimide During Laser Etching
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
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.