Performance and characterization of a highly selective oxide etch for sub-half micron contacts and vias

An inductively coupled plasma has been used to produce contacts and vias with sub-half micron geometries. This process achieves etch selectivities >50:1, much higher than those previously obtained. Higher etch selectivity resulted in contacts and vias with more reliable performance. Improved junction leakage is seen at contacts when the silicided layer remains intact. Via electromigration is greatly improved when the aluminum is not exposed during etch. To accurately measure these high selectivities, a new method was necessary. The merit of this approach over previous methods is discussed.