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Self-aligned air-gaps for trench-first metal hard-mask integration

IP.com Disclosure Number: IPCOM000234147D
Publication Date: 2014-Jan-14
Document File: 3 page(s) / 42K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for self-aligned air-gap formation for Back End of Line (BEOL) interconnects, without additional lithography steps.

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Title

Self-aligned air-gaps for trench-first metal hard-mask integration

Abstract

Disclosed is a method for self-aligned air-gap formation for Back End of Line (BEOL) interconnects, without additional lithography steps.

Problem

A method is needed to provide self-aligned air-gap definition for Back End of Line (BEOL) interconnects.

Solution/Novel Contribution

The novel contribution is a method for self-aligned air-gap formation that does not need additional lithography steps. The method comprises a metal hard-mask directly deposited on carbon containing dielectric material. The metal hard mask can be, for example, Titanium nitride (TiN), Titanium (Ti), Tantalum Nitride (TaN), etc. The dielectric material can be, for example, the composition of Silicon, Carbon, Oxygen, and Hydrogen (SiCOH), porous SiCOH, Ultra Low K (ULK), etc.

The self-aligned air-gap definition is done by a plasma treatment after a hard-mask open etch. This can be done as part of the hard-mask open etch or as a separate step. The air-gap formation is done by wet-etch after polish, and the air-gap closure is done
by non-conformal deposition of dielectric cap (i.e. Silicon, Carbon, (Hydrogen), Nitrogen (SiC(H)N)).

Depth is controlled by plasma treatment settings and time as well as a damage stop layer (i.e., hybrid Inter-Layer Dielectric (ILD) stack).

Method/Process

Step 1: Deposition of dielectric stack and metal hard-mask


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Step 2: Trench lithography and metal hard-mask open etch

Step...