Laser Assisted Chemical Vapor Deposition of Cu from a New Cu Organometallic Complex
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LASER ASSISTED CHEMICAL VAPOR DEPOSITION OF Cu FROM A NEW Cu ORGANOMETALLIC COMPLEX
JAESUNG HAN*, KLAVS F. JENSEN* and JOHN A.T. NORMAN** *Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 **Schumacher Company, Carlsbad, CA 92009
ABSTRACT We describe pyrolytic laser assisted chemical vapor deposition of copper onto silicon using a copper(I) (LCVD) hexafluoroacetylacetonate trimethylvinylsilane organometallic Growth rates complex with 514.5 nm radiation from an Ar÷ laser. of 0.4-40 gm/min were obtained and at intermediate laser powers, the Cu lines had a resistivity comparable to that of bulk Cu. The line shape and morphology was strongly dependent upon laser The power with volcano shapes appearing at higher powers. growth was sensitive to the nature of the substrate suggesting element in the writing that film nucleation was a critical process.
INTRODUCTION Laser-induced deposition of metals from metalorganic gas precursors has received much attention in recent years[l,2] because of its potential for replacing photolithographic metal LCVD deposition process steps with simple maskless processing. of of micron-sized low resistance metals such as Cu is for circuit repair and considerable practical importance Several customized or prototype multichip interconnections. studies of Cu LCVD have been conducted using the standard precursor, copper(II)bis-hexafluoroacetyacetonate [Cu(hfac)2] (37]. Although laser-direct writing of quality Cu deposits has been demonstrated [7], the low vapor pressure of Cu(hfac) 2 limits the deposition rate and its being a solid presents technical in its delivery. Recently, a new precursor, difficulties copper(I)-hexafluoroacetylacetonate-trimethylvinylsilane [Cu(hfac)TMVS] (CupraSelect®), which has a high vapor pressure and is liquid at room temperature, has been introduced by Norman et al. [8]. Thermal metalorganic chemical vapor deposition (MOCVD) experiment with this precursor demonstrated that a high Here we investigate the purity copper film could be obtained. use of this compound for LCVD of high-quality Cu lines. COPPER SOURCE Figure 1 shows the molecular structure of the Cu compound. The trimethylvinylsilane(TMVS) stabilizes the Cu(I) oxidation
Mat. Res. Soc. Symp. Proc. Vol. 236. 01992 Materials Research Society
98
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(CH 3) 3
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copper(I) hexafluoroacetyl acetonate trimethylvinyl silane
At elevated state under moderate temperature conditions. 0 the olefin coupling becomes unstable temperatures (>120 C), 0 1 leaving a reactive Cu+ that ultimately disproportionates to Cu 2 and Cu÷ . However, the compound has sufficiently high vapor pressure, 0.5 Torr at room temperature, to be easily transported and yields reasonable deposition rates at moderate temperatures. Moreover, this compound is a liquid at room temperature making gas handling much easier than for the conventionally used solid precursor, Cu(hfac)2. The thermal deposition mechanism is not well known at this 1 sources and preliminary point but
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