Method of enabling electrical connection to a substructure forming part

Abstract

A method of enabling electrical connection to a substructure (10) forming part of an electronic device, such as an integrated circuit, is described in which an aluminum-containing electrically conductive level (1) is provided on a surface (12) of the substructure (10), an insulating layer (2) is deposited so as to cover the aluminum-containing electrically conductive level (1), a photosensitive resist layer (3) is provided on the insulating layer and a plasma etching step is then used to etch away insulating material so as to expose an electrically conductive surface to enable electrical connection to be made to the level (1). The insulating material (2) may be etched through a window in the resist layer (3) so as to form a via (14) or the resist layer (3) and insulating material (2) may be etched uniformly to provide a planarized surface. In the method, a layer (4) of another conductive material which is free of aluminum is provided on the level (1) prior to covering the level (1) with insulating material (2) so that the plasma etching step exposes an electrically conductive surface (4a) of the layer (4) of the said other conductive material which thus acts to mask the level (1) to prevent catalytic reaction between the aluminum and constituents in the plasma.