Oregon State University

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Event Details

PhD Oral Preliminary Examination – Dustin Austin

Thursday, September 8, 2016 10:00 AM - 12:00 PM

ALD of Multi-Insulator MIM Capacitors
Back end of line (BEOL) metal-insulator-metal capacitors (MIMCAPs) have become a core passive device in integrated circuits (IC). According to the 2020 node of the International Technology Roadmap for Semiconductors (ITRS), scaling the area of these devices for analog/mixed-signal ICs will require simultaneously increasing capacitance density while maintaining low voltage nonlinearity (characterized by the quadratic voltage coefficient of capacitance, αVCC) and low leakage current density. In addition to these conflicting performance requirements, BEOL processing allows for temperatures of no more than 400°C. Al2O3/SiO2 bilayers are first assessed for targeting the IRTS 2020 node for MIMCAPs. These oxides are attractive due to their large metal-insulator barrier heights, high dielectric breakdown strength, and common usage in IC fabrication. SiO2 is a fairly new plasma enhanced atomic layer deposition (PEALD) process and is one of the few materials to exhibit a negative αVCC, which enables its use in combination with the positive αVCC of Al2O3 to target ultra-low device voltage nonlinearity through αVCC canceling. PEALD is used to deposit high quality pin-hole free nanolaminate Al2O3/SiO2 stacks at low temperature without breaking vacuum. The self-limiting reactions of PEALD enable precise control over film thickness, which is critical for optimizing the αVCC cancelling effect for ultra-thin films. Novel ALD processes are also developed for bismuth oxide (Bi2O3) using Bi(OCMe2iPr)3 and H2O, as well as ruthenium oxide (RuO2) and ruthenium metal (Ru) using Ru(DMBD)(CO)3 and O2. This Bi2O3 process enables multi-component ALD films such as BiTaO4, which in literature is a promising material for MIMCAPs due to its reported high-κ with low leakage current density. Additionally ALD of metals has been gaining interest for several years for very thin films in high aspect ratio structures. RuO2 is a conductive oxide which has found use in MIMCAPs as an electrode that can aid in obtaining the high-κ rutile phase of TiO2 by templating its growth. RuO2 is also less likely to form an interfacial layer during dielectric deposition than commonly used electrodes such as TaN and TiN. This interfacial layer can comprise a substantial percentage of the dielectric thickness and reduce the maximum achievable capacitance. Ru metal has a low bulk resistivity and been shown in literature to be a potential Cu barrier to replace TaN. Current work toward further understanding of the origin of αVCC in high-κ dielectrics will be discussed, with focus on the impact of various metal electrodes and hydrogen content within the dielectric film.

Major Advisor: John Conley
Committee: Thomas Plant
Committee: Larry Cheng
Committee: David Cann
GCR: Karen Shell

Kelley Engineering Center (campus map)
Nicole Thompson
1 541 737 3617
Nicole.Thompson at oregonstate.edu
Sch Elect Engr/Comp Sci
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