Title :
The use of Ti as an antireflective coating for the laser planarization of Al for VLSI metallization
Author :
Lai, W.Y.C. ; Liu, Ruichen ; Cheung, K.P. ; Heim, R.
Author_Institution :
AT&T Bell Lab., Murray Hill, NJ, USA
Abstract :
Summary form only given. A report is presented on Ti as an antireflective coating (ARC) to solve the problems encountered using excimer lasers to melt and planarize an Al film. The composite metal film consists of 100-Å Ti on 0.5-1-μm Al on 1000-Å Ti:W, where Ti is the ARC and Ti:W serves as both a wetting layer and a diffusion barrier. The absorptivity at 308 nm of this composite film has been measured as 0.4, which is about five times higher than that of Al. The introduction Ti ARC widens the process window (via-fill to ablation) from ±6-8 to more than ±20%. ARC does not improve the via-fill limit: the temperature of sufficient Al flow to fill contact windows is not lowered. Rather, the wider process window is achieved by pushing the ablation limit towards a higher laser fluence range. It is concluded that 100-Å Ti is not a desirable ARC. However, the value of an ARC in widening the process window is very important to laser planarization and has been demonstrated
Keywords :
VLSI; aluminium; antireflection coatings; laser beam applications; metallisation; titanium; titanium alloys; tungsten alloys; 308 nm; Ti-Al-TiW; VLSI metallization; ablation limit; absorptivity; antireflective coating; contact windows; diffusion barrier; excimer lasers; laser fluence range; laser planarization; process window; wetting layer; Circuits; Coatings; Laser ablation; Metallization; Planarization; Power lasers; Pulsed laser deposition; Sputter etching; Stress; Very large scale integration;
Conference_Titel :
VLSI Multilevel Interconnection Conference, 1989. Proceedings., Sixth International IEEE
Conference_Location :
Santa Clara, CA
DOI :
10.1109/VMIC.1989.78064
