Design, Growth and Properties of Boron-Based Thin Films for Electronics and Nanosized Electronics - BORON

Institution CRP Gabriel Lippmann
Partenaire(s) : University of Texas, Austin
Du : 01/11/2006
Au : 31/10/2010
Budget : 256 000,00€
Contact(s) : Migeon Henri-Noël , Valle Nathalie

Summary

This project in collaboration with the University of Texas aims at studying boron carbonitride (BCxNy called BCN). BCN films are considered to be a good copper diffusion barrier material for integrated circuit interconnections, thanks to its very low permittivity, as well as its good adhesion with low-K porous dielectric material and also with copper. For such an application, the thickness of the BCN barrier film is about 5 to 10 nm.

An adequate reliability study of their anti-copper-diffusion capacity requires the use of Secondary Ion Mass Spectrometry (SIMS), which combines high depth resolution and high sensitivity, and may allow the quantification of copper diffused in these ultra-thin BCN films. At the CRP-GL, the main objective of the project is the quantitative SIMS investigation of ultra-thin BCN films. Two quantitative SIMS approaches are employed and tested on BCN films: correlation between X-ray Photoelectron Spectroscopy (XPS) composition data and SIMS intensities either 1/ in MCs+ mode which has already been proven to be able to circumvent the matrix effect for different matrixes or 2/ in M- mode with the use of simultaneous neutral Cs deposition while bombarding the surface by Cs+, in order to optimize the useful ionization yield of negative secondary ions M-.

For simplification, this study started on major elements of relatively thick films (from 20 to 70 nm) to make sure that these analyses lie in the steady state regime of SIMS. The studied BCN films were deposited by chemical vapour deposition at the University of Texas and their compositions were monitored by XPS. By varying the flow rates of the carrying gas NH(CH3)2:(BH3) and the co-reactive gases (NH3 and C2H4), a broad composition range was obtained (45.7£ B £67.6; 6.8£ C £43.1; 1.3£ N £26.8 at. %). The in-depth analyses using the mode MCsx+ were performed on a CAMECA IMS6f instrument. Linear relationships between the XPS concentrations and the secondary ion intensities (BCs+, CCs+, NCs+, BCs2+, CCs2+, NCs2+) measured by SIMS were obtained over the studied range of compositions.

This SIMS quantitative study on these relatively thick BCN films shows that SIMS is a technique capable of quantifying BCN films. So, the quantification of major and minor elements on BCN ultra-thin films will be carried out using the same approach. By using the mode M-, the first in-depth analyses with and without the assistance of neutral Cs deposition were acquired on a SIMS prototype instrument developed at SAM. The interpretation of these new results is in progress. Collaborations: (synergies that were not specified in the convention) Contributions to Conferences: Quantification of BCN films by SIMS using neutral cesium deposition, F. Wu, N. Valle, R. Fitzpatrick, J.G. Ekerdt, L. Houssiau, H.N. Migeon., SIMS XVII Toronto, September 2009. (Poster) Quantitative investigation of BCN films by dynamic SIMS using the MCsx+ mode, F. Wu, N. Valle, R. Fitzpatrick, J.G. Ekerdt, L. Houssiau, H.N. Migeon, SIMS XVII Toronto, September 2009. (Oral presentation)

Programme:

• Materials World Network, Call 2005

Foreign Funding Agency:

• National Science Foundation (USA)

Figure: Relationship between SIMS and XPS mesurements for boron and carbon