US 4,070,501 A · Forming self-aligned via holes in thin film interconnection systems

Abstract

A method for forming self-aligned via holes which are used to interconnect levels of thin films atop substrates. A first level thin film pattern, typically comprising raised metallic stripes, is formed atop the substrate. A first level dielectric material is then deposited in blanket fashion so that the topology of the insulator conforms to the topology of the pattern. Next, a material such as polymer is deposited which tends to form a planar surface, with a greater thickness of polymer accumulating between the protuberances of the insulator than atop said protuberances. A mask is then applied, exposed and developed at selected regions where via holes are to be formed in the dielectric. A small amount of the polymer is etched, preferably in a plasma, to expose the insulator. Then the latter is etched to form the via holes. Accurately located via holes are formed, even if the mask is misaligned.

Claims14

Dependent claims

A method for forming via holes atop selected regions of a thin film pattern of raised thin film stripes disposed on a substrate comprising the steps of:

depositing a dielectric material atop said stripes and said substrate, the topology of said dielectric material including protuberances conforming to said stripes;
depositing a second material atop said dielectric material, which fills in the regions between said protuberances to a greater thickness than atop said protuberances;
said material being insensitive to exposure;
forming, on said second material, a masking layer having openings over selected protuberances, thereby exposing portions of said second material;
removing those portions of said second material which are disposed above said selected protuberances while not substantially affecting those portions of said second material disposed in the regions between said protuberances;
and
etching said dielectric material through the openings in said second material with an etchant which does not substantially attack said second material or said masking layer, thereby forming said via holes.

4 more elements

Dependencies are inferred from the claim text.

Forming self-aligned via holes in thin film interconnection systems

Life of this patent

Forming self-aligned via holes in thin film interconnection systems

Life of this patent

Abstract

Claims14