Method of forming a beol interconnect structure using a subtractive metal via first process
AssigneeInternational Business Machines Corporation
InventorsYann Mignot, Yongan Xu, Hsueh-Chung Chen
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Abstract
A method of forming a BEOL interconnect structure having improved resistance-capacitance is provided in which a via metal layer is created by a first metallization process and thereafter shrunk by a subtractive etch; these steps relax the critical dimension, ensure a via straight profile, avoid via chamfering and bowing, and maximize metal volume. Top trench metallization is then performed above the via metal layer; this step eliminates reactive ion etch lag and ensures no metallization void issues.
Claims20
A method of forming a back-end-of-the-line interconnect structure, the method comprising:
- forming a dielectric capping layer on a surface of a metal level, wherein the metal level comprises a plurality of electrically conductive structures embedded in a dielectric material layer;
- forming via openings into the dielectric capping layer, wherein each of the via openings physically exposes a surface of one of the electrically conductive structures embedded in the dielectric material layer;
- forming a first metal-containing layer in each of the via openings and on a topmost surface of the dielectric capping layer;
- etching the first metal-containing layer utilizing a patterned photoresist-containing structure as a first etch mask to provide first metal-containing structures, wherein each of the first metal-containing structures has a lower portion located in one of the via openings and an upper portion extending vertically upwards from the lower portion;
- forming a first interconnect dielectric material layer laterally adjacent to the upper portion of each of the first metal-containing structures;
- forming a second metal-containing layer on the first interconnect dielectric material layer and each of the first metal-containing structures;
- etching the second metal-containing layer utilizing another patterned photoresist-containing structure as a second etch mask to provide second metal-containing structures;
- and
- forming a second interconnect dielectric material layer laterally adjacent to each of the second metal-containing structures and on the first interconnect dielectric material layer.
A method of forming a back-end-of-the-line interconnect structure, the method comprising:
- forming a dielectric capping layer on a surface of a metal level, wherein the metal level comprises a plurality of electrically conductive structures embedded in a dielectric material layer;
- forming via openings into the dielectric capping layer, wherein each of the via openings physically exposes a surface of one of the electrically conductive structures embedded in the dielectric material layer;
- forming a selective metal-containing cap in each of the via openings;
- forming a first metal-containing layer on each of the selective metal-containing caps and on a topmost surface of the dielectric capping layer;
- etching the first metal-containing layer utilizing a patterned photoresist-containing structure as a first etch mask to provide first metal-containing structures;
- forming a first interconnect dielectric material layer laterally adjacent each of the first metal-containing structures;
- forming a second metal-containing layer on the first interconnect dielectric material layer and each of the first metal-containing structures;
- etching the second metal-containing layer utilizing another patterned photoresist-containing structure as a second etch mask to provide second metal-containing structures;
- and
- forming a second interconnect dielectric material layer laterally adjacent to each of the second metal-containing structures and on the first interconnect dielectric material layer.
Dependencies are inferred from the claim text.