Preparation of low density poly(methylsilsesquioxane)s for LSI interlayer dielectrics with low dielectric constant. Fabrication of Ångstrom size pores prepared by baking trifluoropropylsilyl copolymers

Abstract

We report a method to fabricate Ångstrom size pores in poly(methylsilsesquioxane) films in order to decrease the density and the dielectric constant of the film. Copolymers bearing methyl(trisiloxysilyl)units and alkyl(trisiloxysilyl) units are spin-coated and baked at 250 °C to provide rigid siloxane matrixes. Films are baked up to 450 or 500 °C to remove thermally labile alkyl groups and holes are left corresponding to the sizes of the substituents. Trifluoropropyl, cyanoethyl, phenethyl and propyl groups are investigated as thermally labile substituents. Only the trifluoropropyl group works well under the limitation of baking temperatures up to 450 or 500 °C, the pores collapsing for films bearing other substituents. A film P5 with a dielectric constant of 2.3 was obtained for trifluoropropyl. The total surface area of this film was 1.34 times that of poly(methylsilsesquioxane) film (P1) prepared by a conventional sol-gel method. The peak of pore distributions is in the region <10 Å. The peculiarity of the trifluoropropyl group is discussed.

References

1. W. W. Lee and P. S. Ho, MRS Bull., 1997, 22, 19.
2. E. T. Ryan, A. J. Mckerrow, J. Leu and S. P. Ho, MRS Bull., 1997, 22, 49.
3. J. L. Hedrick, H. J. Cha, R. D. Miller, D. Y. Yoon, H. R. Brown, S. Srinivasan, R. D. Pietro, R. F. Cook, J. P. Hummel, D. P. Klaus, E. G. Liniger and E. E. Simonyi, Macromolecules, 1997, 30, 8512.
4. N. P. Hacker, MRS Bull., 1997, 22, 33.
5. T. Ramos, K. Roderick, R. Roth, S. Wallace, N. Hendrichs, N. Rutherford, J. Drage, S. Q. Wang and D. M. Smith, Proceedings of Third International Dielectrics for ULSI Maultilevel Interconnection Conference, 1997, p. 106.
6. A. Nakashima, A. M. Egami, M. Komatu, Y. Ohkura, M. Miyajima, H. Harada and S. Fukuyama, Proceedings of Third International Dielectrics for ULSI Maultilevel Interconnection Conference, 1997, p. 303.
7. T. Saegusa, J. Macromol. Sci. A–Chem., 1991, 28, 817.
8. R. Tamaki, R. K. Naka and Y. Chujo, Polym. J., 1998, 30, 60.
9. R. Tamaki and Y. Chujo, J. Mater. Chem., 1998, 8, 1113.
10. H. Yang, N. Coombs and G. A. Ozin, J. Mater. Chem., 1998, 8, 1205.
11. C. T. Kresge, M. E. Leonowics, W. L. Roth, J. C. Vartuli and J. B. Beck, Nature, 1992, 359, 710.
12. Q. Huo, D. I. Margolese, V. Ciesla, P. Feng, T. E. Gier, P. Sieger, R. Leon, P. M. Petroff, F. Schuth and G. D. Stucky, Nature, 1994, 368, 317.
13. P. T. Tanev and T. J. Pinnavaia, Science, 1995, 267, 865.
14. S. A. TechBagshaw, E. Prouzet and T. J. Pinnavaia, Science, 1995, 269, 1242.
15. A. K. Stamper, V. McGahay and J. P. Hummel, Proceedings of Third International Dielectrics for ULSI Maultilevel Interconnection Conference, 1997, p. 13.
16. J. Hedrick, J. Labadie, T. Russell, V. Wakharkar and D. Hofer, Advance in Polyimide Science and Technology, ed. C. Feger, M. M. Khojasteh and S. M. Htoo, Technomic, Lancaster, 1993, p. 184.
17. J. W. Labadie, J. M. Hedric, V. Wakharkar, D. C. Hofer and T. P. Russel, Transaction on components, hybrid, and manufacturing technology, IEEE, 1992, 15, 925.
18. O. Gain, G. Seytre, J. Garapon, J. Vallet and B. SillionHigh-temperature properties and applications of polymeric materials, ed. M. R. Tant, J. W. Connell and H. L. N. McManus, ACS Symp. Ser., 603, American Chemical Society, Washington, DC, 1995, ch. 13, p. 200.
19. D. A. Loy and K. J. Shea, Chem. Rev., 1995, 95, 1431.
20. S. J. Gregg and A. S. W. Sing, Adsorption, surface area and porosity, 2nd edn., New York, 1982.
21. I. Langmuir, J. Am. Chem. Soc., 1918, 40, 1361.
22. E. P. Barret, L. G. Joyner and P. P. Halenda, J. Am. Chem. Soc., 1951, 73, 373.
23. J. H. deBoer, G. B. Linsen, T. Plas and G. J. Zondervan, J. Catal., 1965, 4, 649.
24. W. D. Harkins and G. Jura, J. Chem. Phys., 1943, 11, 431.
25. R. H. Baney, M. Itoh, A. Sakakibara and I. Suzuki, Chem. Rev., 1995, 95, 1409.
26. S. Fujimoto, H. Ohtani and S. Tsuge, Fresenius' Z. Anal. Chem., 1988, 331, 342.
27. T. H. Thomas and T. C. Kendrich, J. Polym. Sci., A2, 1969, 7, 537.
28. M. Zeldin, B. R. Qian and S. J. Choi, J. Polym. Sci., Polym. Chem. Ed., 1983, 21, 1361.
29. J. C. Kleinert and C. J. Weschler, Anal. Chem., 1980, 52, 1245.
30. A. Ballistreri, D. Garrozzo and G. Montaudo, Macromolecules, 1984, 17, 1312.
31. N. Grassie and I. G. MacFarlane, Eur. Polym. J., 1978, 14, 875.
32. N. Grassie, I. G. MacFarlane and K. Francey, Eur. Polym. J., 1979, 15, 415.
33. S. Hofmann, L. G. Blomberg, J. Buijten, K. Markides and T. Wannmann, J. Chromatogr., 1984, 302, 95.
34. M. Gazicki, A. M. Wrobel and M. Kryszewski, J. Appl. Polym. Sci., Appl. Polym. Symp., 1984, 38, 1.
35. W. Patnode and A. M. Wilcock, J. Am. Chem. Soc., 1946, 68, 358.
36. M. J. Hunterm, J. F. Hyde, W. L. Warrick and H. J. Fletcher, J. Am. Chem. Soc., 1946, 68, 667.
37. S. B. Lin, High-temperature properties and applications of polymeric materials, ed. M. R. Tant, J. W. Connell and H. L. N. McManus, ACS Symp. Ser., 603, American Chemical Society, Washington, DC, 1995, ch. 3, p. 37.
38. G. J. Knight and W. W. Wright, Br. Polym. J., 1989, 21, 199.
39. T. C. Kendrick, B. Paarbhoo and J. W. White, The chemistry of organo silicon compounds, ed. S. Patai and Z. Rappoport, John Wiley & Sons Ltd., New York, 1989, ch. 21, p. 1289.
40. T. Kitakohji, S. Takeda, M. Nakajima and M. Usui, Jpn. J. Appl. Phys., 1983, 22, 1934.
41. V. B. Pavlova, I. A. Metkin and Y. A. Yuzhelevskii, Vysokomol. Soedin., Ser. B, 1980, 22, 563.
42. G. Sloniskii, A. Askadskii and A. Kitaigorodskii, Polym. Sci. USSR, 1970, A12, 556.
43. S. Ando, Kobunshi Ronbunshu, 1994, 51, 25.