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Bilayer Metal Hard Mask for Contact RIE

IP.com Disclosure Number: IPCOM000236384D
Publication Date: 2014-Apr-23
Document File: 2 page(s) / 138K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a scheme that allows three (or more) color memorizations into a Titanium Nitride/Low-Temperature Silicon Oxide (TiN/LTO) bilayer mask prior to the source/drain contact etch. This eliminates multiple occurrences of plasma exposure to the source/drain region and reduces the instances of damage from exposure to Reactive Ion Etching (RIE).

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Bilayer Metal Hard Mask for Contact RIE

The current process on record (POR) flow requires three exposures for source/drain (S/D) contacts. With this scheme, the source/drain regions of the first exposure CA can be exposed to Reactive Ion Etching (RIE), which is a potential damage mechanism, a minimum of six times before considering rework.

The novel solution is a scheme that allows three (or more) color memorizations into a Titanium Nitride/Low-Temperature Silicon Oxide (TiN/LTO) bilayer mask prior to the source/drain contact etch. This eliminates multiple occurrences of plasma exposure to the source/drain region. Specifically, the source/drain region is only exposed to RIE processes during the final oxide etch. Moreover, this scheme can be transferred to the gate contact two-color etch, which can eliminate an additional four source/drain plasma exposures. This scheme also utilizes in-situ dry TiN strip during the last exposure, thereby reducing the need for wet TiN removal and decreasing concern for downstream TiN contamination.

Each exposure (CA, CC, or CE for S/D contacts; CB, CD for gate contacts) is memorized into TiN. During the last exposure (CE or CD), the pattern is transferred into LTO, followed by an in-situ dry removal of the TiN. Thus, the mask going into the S/D and gate contact Inter-Layer Dialectric (ILD) etch is LTO.

Figure 1: Proposed TiN Hard Mask Self-Aligned Contact (SAC) Flow
This scheme shows 2-color memorization for S/D contacts, and is ex...