AVS 53rd International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS2-MoM

Paper PS2-MoM10
Ta and Mo-based Metal Etch for Advanced Gate Stacks

Monday, November 13, 2006, 11:00 am, Room 2011

Session: Advanced Gate Fabrication
Presenter: E. Luckowski, Freescale Semiconductor, Inc.
Authors: E. Luckowski, Freescale Semiconductor, Inc.
A. Martinez, Freescale Semiconductor, Inc.
S. Rauf, Freescale Semiconductor, Inc.
Correspondent: Click to Email
The continued scaling of conventional CMOS devices becomes increasing difficult due to the additional series capacitance caused by polysilicon depletion, which decreases gate capacitance and requires increasingly thin gate dielectric layers. High-K dielectrics in conjunction with polysilcon gates address this problem, but interactions between polysilicon and gate dielectric material make implementation of this solution difficult. An increasingly attractive solution to these problems is the use of metal electrodes with suitable work functions and sufficient physical and electrical stability. Because selection appropriate gate electrode is driven mainly by the work function of the metal, these materials pose significant challenges that require an in-depth understanding of plasma etch properties and mechanisms in order to successfully fabricate aggressive dimensions of current advanced gate stack devices. In this work we investigate the impact of plasma parameters on etching characteristics of Ta and Mo-based materials for advanced gate stack device applications. In particular, etch rates and selectivites are discussed with respect to fabricating single and dual metal gate CMOS structures. The impact of metal etch processes on polysilicon and high-k dielectric layers will also be discussed. OES and in-situ reflectometry are used to characterize composition and changes in the plasma conditions, etch rates and profiles measured by four point probe, XRR, SEM and TEM. Plasma modeling is also done using a 2D integrated equipment-feature scale model to improve understanding of the mechanisms of metal gate etch processes.