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FTIR ANALYSIS OF A NEW HIGH K GATE MATERIAL FOR MOCVD APPLICATIONS

IP.com Disclosure Number: IPCOM000004700D
Original Publication Date: 2001-Apr-12
Included in the Prior Art Database: 2001-Apr-12
Document File: 5 page(s) / 18K

Publishing Venue

Motorola

Related People

Victor Vartanian: AUTHOR [+5]

Related Documents

Semiconductor Industry Association, National Technology Roadmap for Semiconductors: Technology Needs, International SEMA TECH, Austin, TX, 1999.: OTHER [+9]

Abstract

Extractive Fourier transform infrared (FTIR) spectroscopy is used to characterize the deposition rate of a new high dielectric constant metal oxide chemical vapor deposition (MOCVD) material, TN, or tetrakis nitrato titanium [Ti(NO3)4]. The inorganic precursor tetrakis nitrato titanium deposits thin titanium dioxide (dielectric constant 25-30) films. Typical deposition rates ranged from 10-45 Å/min as confirmed by reflectometry measurements. The FTIR is installed downstream of the deposition tool post-pump and uses a 22 m path-length multi-pass cell to extend the detection limits to the low ppm range. Spectral peak intensity of a by-product is found to have very high correlation to the deposition rate.

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FTIR ANALYSIS OF A NEW HIGH K GATE MATERIAL FOR MOCVD APPLICATIONS

by Victor Vartanian, Vernon Cole, Kim Reid, Laura Mendicino and Paul Thomas Brown

ABSTRACT

Extractive Fourier transform infrared (FTIR) spectroscopy is used to characterize the deposition rate of a new high dielectric constant metal oxide chemical vapor deposition (MOCVD) material, TN, or tetrakis nitrato titanium [Ti(NO3)4]. The inorganic precursor tetrakis nitrato titanium deposits thin titanium dioxide (dielectric constant 25-30) films. Typical deposition rates ranged from 10-45 Å/min as confirmed by reflectometry measurements. The FTIR is installed downstream of the deposition tool post-pump and uses a 22 m path-length multi-pass cell to extend the detection limits to the low ppm range. Spectral peak intensity of a by-product is found to have very high correlation to the deposition rate.

INTRODUCTION

Moore's law has accurately predicted the device scaling of the past 30 years. As high performance and low power continue to reduce feature sizes the semiconductor industry is reaching a point where continued adherence to Moore's law requires that new materials replace the historical conductors and dielectrics that are reaching the limits of fundamental device physics. Copper has largely replaced aluminum as the metal conductor and both high and low dielectric materials are being developed as replacements for SiO2.

The 1999 International Technology Roadmap for Semiconductors (Figure 1) indicates that for the 130 nm technology node, the equivalent oxide thickness, Tox, be 1.2-1.5 nm1. The gate oxide capacitively couples the gate to the conductive channel region between the source and drain in the MOSFET. As the feature size is reduced, the gate oxide thickness must be reduced to maintain gate capacitance (eq. 1). However, for oxide thickness below 2.0 nm, tunneling

[see the accompanying PDF file for the equation]

currents become significant and begin to dominate gate leakage to the point where the device no longer acts as a transistor2,3,4,5. To circumvent this, materials with higher permittivity than SiO2 (k=3.9) are required to reduce tunneling currents and increase the physical distance between gate and channel, to maintain gate capacitance.

where:

q the charge on a plate

A area of a parallel plate capacitor

V the voltage on a plate

?r= relative permittivity of the oxide

d thickness of the oxide

EXPERIMENTAL METHODOLOGY

Illustrated below is a molecule of tetrakis nitrato titanium, TN, or Ti(NO3)4 that is used as a precursor to deposit TiO2 as a gate oxide.

The titanium is directly bonded to eight oxygens. When TN is introduced into the chamber, the following reactions are believed to occur, with the loss of a nitric oxide the most thermodynamically favorable mechanism:

Ti(NO3)4 ? TiO2(NO3)3 NO 55 kcal mol-l

Ti(NO3)4?TiO2(NO3)2 2...