lecture19 - http:/ocw.mit.edu _ MIT OpenCourseWare 2.830J /...

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MIT OpenCourseWare ____________ http://ocw.mit.edu 2.830J / 6.780J / ESD.63J Control of Manufacturing Processes (SMA 6303) Spring 2008 For information about citing these materials or our Terms of Use, visit: ________________ http://ocw.mit.edu/terms .
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1 M anufacturing Control of Manufacturing Processes Subject 2.830/6.780/ESD.63 Spring 2008 Lecture #19 Case Study: Tungsten CVD DOE/RSM April 29, 2008
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2 M anufacturing Case Study Reading • Thomas E. Clark, Mei Chang, and Cissy Leung, “Response surface modeling of high pressure chemical vapor deposited blanket tungsten,” J. Vac. Sci. Technol. B, vol. 9, no. 3, pp. 1478- 1486, May/June 1991.
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3 M anufacturing Agenda • Background: Tungsten CVD • Preliminary Work (not shown in paper) • Experimental Design: Central Composite •D a t a • RSM Analysis – Paper vs. In-Class • Exploratory Analyses: JMP – Stepwise regressions – Optimization • Other Ideas?
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4 M anufacturing Tungsten Plugs • W is a conductor used for: contacts (to silicon or poly) plugs (between aluminum metal layers) – W plugs remain important in copper interconnect (contacts) • Highly conformal: able to fill small holes • Originally used with plasma etchback (as shown) – Now CMP is used for plug formation with a polish-back step Image removed due to copyright restrictions. Please see Fig. 7 in Clark, Thomas E., et al. “Response Surface Modeling of High Pressure Chemical Vapor Deposited Blanket Tungsten.” Journal of Vacuum Science and Technology B 9 (May/June 1991): 1478-1486.
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5 M anufacturing Inputs: • Gap space • Temperature •H 2 pressure •W F 6 pressure Image removed due to copyright restrictions. Please see Fig. 1 in Clark, Thomas E., et al. “Response Surface Modeling of High Pressure Chemical Vapor Deposited Blanket Tungsten.” Journal of Vacuum Science and Technology B 9 (May/June 1991): 1478-1486.
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6 M anufacturing Tungsten CVD Outputs 1. Deposition rate – desire a high rate, e.g. 500 nm/min 2. Resistivity ρ – desired value depends on application; usually desire low resistivity 3. R s uniformity – need good wafer-level uniformity (<3%) to avoid recessed plugs in etchback 4. Film stress – avoid high stress to prevent delamination 5. Step coverage – desire 100% fill (flat fill) of trench or hole 6. WF 6 conversion – want efficient usage of this expensive gas 7. Reflectance – desire highly reflective surface, indicating smooth surface morphology 8. Reproducibility – need good run to run repeatability of process
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This note was uploaded on 09/24/2010 for the course MECHE 2.830J taught by Professor Davidhardt during the Spring '08 term at MIT.

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lecture19 - http:/ocw.mit.edu _ MIT OpenCourseWare 2.830J /...

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