Abstract
Using scanning electron microscopy, the microstructure of annealed N-type parylene films on silicon substrate was observed and compared to the asdeposited film. The diffusion of copper through the parylene-N film was studied and correlated to the microstructure. A web-like microstructure was observed on annealing parylene-N to a temperature of 300°C and higher. This microstructure differed from the as-deposited homogeneous and continuous structure at room temperature. The web-like structure observed is proposed to be a fibrillar crystalline structure embedded in an amorphous matrix. X-ray diffraction studies supported this view and showed that the crystalline structure was theß phase. Also, when the film was annealed at 300 and 350°C, a thin continuous layer was formed at the surface of the web-like parylene-N film. In contrast, no such thin layer was observed when the annealing was performed with a copper overlayer. Based on this observation, a two-stage annealing process was carried out to reduce the copper diffusion into parylene-N, preannealing, before copper deposition and post-annealing after copper deposition. The results, as judged from Rutherford backscattering spectroscopy indicate that the thermal stability for copper diffusion into parylene-N films can be increased by 50°C (from 300 to 350°C) using pre-annealing. Experimental data shows that a minimum pre-anneal temperature of 250°C for 1 h is required for this purpose.
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References
C.P. Wong, Polymers for Electronic and Photonic Applications, (New York: Academic Press, 1993); Low-dielectric constant materials: synthesis and applications in microelectronics, eds. T.-M. Lu, S.P. Murarka, T.S. Kuan and C.H. Ting (Pittsburgh, PA: Mater. Res. Soc., 1995).
F. Beach, C. Lee, D.R. Bassett, T.M. Austin and R. Olson, Encyclopedia of Polymer Science and Engineering, 17, 2nd. ed. (New York: John Wiley and Sons, 1989), p. 990.
N. Majid, S. Dabral and J.F. McDonald, J. Electron. Mater. 18 (2), 301 (1989); N. Majid, S. Dabral, H.T. Lin and J.F. McDonald, Proc. VLSI 1988 Multilayer Interconnection Conf. V-MIC88, Santa Clara, CA, June 13–14, 1988, p. 299.
B.J. Bachman, First Inter. SAMPE Electro. Conf., June 23–25, 1987, p. 431.
T.-M. Lu, J.F. McDonald, S. Dabral, G.-R. Yang, L. You and P. Bai, Mater. Res. Soc. Symp. Proc, 181, (Pittsburgh, PA: Mater. Res. Soc., 1990), p. 55.
J. F. McDonald, S. Dabral, G.-R. Yang, H. Bakhru and T.-M. Lu, IEEE VMIC, Santa Clara, CA, (IEEE CAT 90 TH 0325-1), 345 (1990).
S. Dabral, Y. Zhang, X.-M. Wu, L. You, C.-I. Lang et al., J. Vac. sci. Tech. B 11 (5), 1825 (1993).
J.H. Das and J.E. Morris, J. Appl. Phys. 6 (12), 5816 (1989).
F. Faupel, D. Gupta, B.D. Silverman and P.S. Ho, Appl. Phys. Lett. 55 (4), 357 (1989).
C. K. Hu, S. Change, M.B. Small and J.E. Lewis, IEEE VMIC Conf, Santa Clara, CA, June 9–10, 1986, p. 181.
G -R. Yang, S. Dabral, L. You, J.F. McDonald and T.-M. Lu, J. Elecron. Mater. 20 (7), 571 (1991).
S. Dabral, G.-R. Yang, H. Bakhru, T.-M. Lu and J.F. McDonald, J. Vac. sci. Tech. A 10 (4), 2764 (1992).
G.-R. Yang, S. Dabral, X.-M. Wu, T.-M. Lu and J.F. McDonald, J. Vac. sci. Tech. A 10 (4), 916 (1992).
Novatran Corporation, Clear Lake, WI.
S.N. Mei and T.-M. Lu, J. Vac. sci. Tech. A 6, 9 (1988).
J E Baglin, Nucl. Inst. Meth. Phys. B3, 764 (1989).
S. Kubo and B. Wunderlich, J. Poly. sci. 10, 1949 (1972).
Xin Zhang, Ph.D. Thesis, Rensselaer Polytechnic Institute (1995).
W.D. Niegisch, J. Appl. Phys. 37, 404 (1966).
D.E. Kirkpatrick and B. Wunderlich, J. Poly. sci. B 24, 931 (1986).
P.K. Wu, G.-R. Yang and T.-M. Lu, App. Phys. Lett, submitted.
L. You, G.-R. Yang, D.B. Knorr, J.F. McDonald and T.-M. Lu, Appl. Phys. Lett. 64, 2812 (1994).
S. Kubo and B. Wunderlich, J. Appl. Phys. 42 (12), 4558 (1971).
D.R. Linde, CRC Handbook of Chemistry and Physics, 71st. ed., p. 90.
J.K. DePorter, D.G. Baird and G.L. Wilkes, J. Mater. sci.: Rev. Mac. Chem. Phys. C33 (1) 1993.
P.K. Wu, G.-R. Yang, J.F. McDonald and T.-M. Lu, J. Electron. Mater. 24, 53 (1995).
G.-R. Yang, D. Mathur, J.F. McDonald and T.-M. Lu, J. Vac. sci. Tech. A, to be pubished Nov.–Dec. (1996).
G.-R. Yang, S. Dabral, L. You, H. Bakhru, J.F. McDonald and T.-M. Lu, Mater. Res. Soc. Proc.f 203, (Pittsburgh, PA: Mater. Res. Soc., 1991), p. 271. $
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Yang, G.R., Mathur, D., Wu, X.M. et al. Microstructures of parylene-N thin films and the effect on copper diffusion. J. Electron. Mater. 25, 1778–1783 (1996). https://doi.org/10.1007/s11664-996-0035-y
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DOI: https://doi.org/10.1007/s11664-996-0035-y