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Method and System for utilizing Titanium Oxygen Getter and Optimized Stoichiometry Titanium Nitride barrier for Preventing Contact Profile Distortion and Hollow CA

IP.com Disclosure Number: IPCOM000235770D
Publication Date: 2014-Mar-25
Document File: 4 page(s) / 90K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system is disclosed for utilizing titanium oxygen getter and optimized stoichiometry Titanium Nitride (TiN) barrier for preventing contact profile distortion and hollow CA.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 46% of the total text.

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Method and System for utilizing Titanium Oxygen Getter and Optimized Stoichiometry Titanium Nitride barrier for Preventing Contact Profile Distortion and Hollow CA

Disclosed is a method and system for utilizing titanium oxygen getter and optimized stoichiometry Titanium nitride (TiN) barrier for preventing contact profile distortion and hollow CA.

The method and system converts a portion of deposited Titanium (Ti) into Titanium nitride (TiN) and the remaining deposited Ti as an oxygen getter. Here, the Ti at the Ti/Tetraethyl Orthosilicate (TEOS) interface acts as an oxygen getter and a portion of about 30% to 50% of the Ti is converted to Titanium Nitride (TiNx) using nitrogen plasma. The nitrogen plasma acts as a diffusion barrier and an adhesion layer to a Tungsten (W) film. The amount of nitrogen that can be incorporated into a Physical Vapor Deposition (PVD) Ti film is controlled by adjusting the nitrogen plasma annealing conditions. This prevents fluorine diffusion, TixF formation and thus CA profile deformation/distortion.

The distortion of a CA profile is transpired as a resultant stress due to volume expansion by TixF formation exceeding its elasticity to a plastic state. Therefore, the resultant stress to be maintained in its elastic region and the distortion of the CA profile are prevented by reducing the total Ti in a layer. In such a case, deposition of total Ti, for instance, 80 Angstrom(A) maintains its physical and mechanical integrity as an oxygen getter or a Low voltage NMOS Region (LNR) without any weak spot. Thereafter, a portion of the layer is converted to TiN as an in position layer by a process of nitrogen plasma reaction. The process of nitrogen plasma reaction eliminates an Atomic Layer Deposition (ALD) TiN step which further helps in maintaining wider opening for W deposition.

In another scenario, the method and system reduces a current Ti layer to its half or less than half and then executes steps as illustrated in flow chart of fig.1.

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Figure 1

As shown in fig.1, initially a wet cleaning is performed and then Ti oxygen getter and the TiN is obtained. In the subsequent steps, the ALD is filled by a cool fill and then a Chemical Vapor Deposition (CVD) is performed at high temperature.

Thereafter, the method and system utilizes optimized nitrogen plasma annealing for better stoichiometry of TiNx. If Fluorine (F) diffuses through the TiN, reacts and forms TiFx, then a net volume expansion is around 50% or less than a Process of Record (POR). Therefore, the method and system reduces the resultant stress due to less volume expansion and thus prevents the distortion of CA profile.

In a first embodiment, the portion of Ti is converted into an optimized stoichiometry TiNx as shown in fig.1.

Figure 2

Initially the Ti layer is deposited and a portion of 40% - 50% is converted into TiNx using the nitrogen plasma annealing. Here, the TiNx acts as a diffusion barrier and adhesion layer for the tungste...