AVS 46th International Symposium
    Electronic Materials and Processing Division Thursday Sessions
       Session EM1-ThM

Paper EM1-ThM5
Complete Filling of High-Purity Copper in Subquarter-Micron Trench Structure Using Plasma CVD Reactor with H Atom Source

Thursday, October 28, 1999, 9:40 am, Room 608

Session: Cu, Low-k Dielectrics and Interfaces
Presenter: H.J. Jin, Kyushu University, Japan
Authors: H.J. Jin, Kyushu University, Japan
M. Shiratani, Kyushu University, Japan
Y. Nakatake, Kyushu University, Japan
K. Koga, Kyushu University, Japan
T. Kinoshita, Kyushu University, Japan
Y. Watanabe, Kyushu University, Japan
Correspondent: Click to Email
Complete filling of high-purity copper in subquarter-micron trench structures is a key requirement in formation of metal interconnects carrying signals in ULSI. For this interconnect application, we have developed a plasma CVD reactor equipped with an H atom source in order to control independently the concentration of H atoms and the degree of dissociation of Cu(hfac)@sub 2@, since H atoms are extremely effective in removing impurities within the film and deposition rate and film conformality presumably depends on the degree of dissociation of Cu(hfac)@sub 2@.@footnote 1,2,3@ High-purity Cu films (about 100%) with the low resistivity of 2 @micro n@@ohm@cm can be deposited, even with the low H@sub 2@ gas volume fraction of 50-67%, by using the H atom source, while high-purity films are obtained only for an H@sub 2@ gas volume fraction above 90% for the CVD reactor without the source. In order to evaluate Cu filling property in trench structures using the plasma CVD reactor with the H atom source, coverage shape of the Cu deposited film in a trench 0.4 µm wide and 3.25 µm deep is examined under conditions for which high-purity (about 100%) Cu films are obtained. While the coverage at the bottom of trench is 0% for the main discharge power P@sub m@ = 80 W, it increases with decreasing P@sub m@ to reach 95% for P@sub m@ = 15 W. These results show that a decrease in P@sub m@ leads to a reduction in the sticking probability of Cu-containing radicals, a low value of which is essential for the achievement of complete filling of extremely small width and high aspect ratio trench structures. We also have succeeded in complete and void free filling in trench 0.3 µm wide and 1 @micron@ deep using such control. Cross sectional TEM observation of Cu films shows that size of Cu grain is above 0.5 µm. @FootnoteText@ @footnote 1@M. Shiratani, et al., J. Phys. D, 29 (1996) 2754. @footnote 2@H. J. Jin, et al., J. Vac. Sci. & Tech. A17 (1999). @footnote 3@H. J. Jin, et al., Jpn. J. Appl. Phys. July (1999).