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Proceedings Paper

Etch characteristics of Ti in Cl2/N2 and TiN in Cl2/N2/BCl3 plasmas by response surface methodology
Author(s): N. Moorthy Muthukrishnan; Kostas Amberiadis; Aicha Elshabini-Riad
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Paper Abstract

The etch characteristics of titanium (Ti) film in Cl2/N2 plasmas and titanium nitride (TiN) film in Cl2/N2/BCl3 plasmas are examined by design of experiment using central composite-face centered type design and modeled by response surface methodology (RSM). The Ti and TiN etch experiments are carried out in a Lam Research Rainbow 4600 single wafer parallel plate metal etcher. For the Ti etch process, the effects of variation of the process parameters such as Cl2, N2 gas flow, RF power and reaction pressure on output responses, etch rate and etch uniformity, are investigated. For TiN etch process, BCl3 gas flow is added as a factor in addition to the factors listed above. A statistical analysis software package, JMP, is used to design experiment and analyze the results. The factors are normalized with respect to center point for the design and analysis of the experiment in order to compare the relative significance of the model terms. Using the etch rate and uniformity data obtained from the experiment, a quadratic model is developed for etch rate and uniformity for each rate and uniformity data obtained from the experiment, a quadratic model is developed for etch rate and uniformity for each of the films. From the coefficients of the models thus developed, it is easy to determine the relative influence of the first and second order effects of factors, and two factor interactions on the etch rate and uniformity response. Contour plots, which are helpful in determining the optimum process window, are generated for both etch rate and uniformity factors. Addition of nitrogen is found to decrease the etch rate due to dilution effect. The reaction pressure decreases the etch rate probably due to loss of energies of radicals, ions and electrons. Increasing of all the factors except nitrogen flow lead to better etch uniformity. Increase in nitrogen flow is causing poor uniformity probably due to dilution of etchant species leading to across-the-wafer nonuniformity.

Paper Details

Date Published: 3 September 1998
PDF: 10 pages
Proc. SPIE 3507, Process, Equipment, and Materials Control in Integrated Circuit Manufacturing IV, (3 September 1998); doi: 10.1117/12.324338
Show Author Affiliations
N. Moorthy Muthukrishnan, LSI Logic Corp. (United States)
Kostas Amberiadis, LSI Logic Corp. (United States)
Aicha Elshabini-Riad, Virginia Polytechnic Institute and State Univ. (United States)


Published in SPIE Proceedings Vol. 3507:
Process, Equipment, and Materials Control in Integrated Circuit Manufacturing IV
Anthony J. Toprac; Kim Dang, Editor(s)

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