AVS 46th International Symposium
    Plasma Science and Technology Division Thursday Sessions
       Session PS1-ThA

Paper PS1-ThA9
Integration of Metal Masking and Etching for Deep Submicron Patterning

Thursday, October 28, 1999, 4:40 pm, Room 612

Session: High Fidelity Pattern Transfer
Presenter: C.T. Gabriel, VLSI Technology
Authors: C.T. Gabriel, VLSI Technology
R. Kim, VLSI Technology
D.C. Baker, VLSI Technology
Correspondent: Click to Email
Although copper damascene interconnects offer many advantages over conventional subtractive etched Al alloys, the challenges and costs associated with converting to copper have combined to extend the useful life of Al alloy etching into the deep submicron regime. As a result, metal masking and etching are facing new challenges. DUV photolithography has replaced the conventional i-line technique for patterning fine metal pitches, but some DUV photoresists are less able to withstand the aggressive plasma environment than their i-line counterparts. Reflectivity increases at DUV wavelengths, so dielectric anti-reflective films are added on top of the metal stack. The mask-open process, where the dielectric film is plasma etched prior to etching the metal stack, alters the photoresist further and influences the subsequent metal etch. Aspect ratio dependent etch effects increase when etching narrow spaces resulting from tightened metal pitches, and gas additives may be required to protect the metal sidewalls. These effects are characterized and the challenges of deep submicron metal etch process development are discussed. The option of true hardmasked etching of the metal stack is also investigated.