COPPER CVD CHEMISTRY ON A REACTIVE SUBSTRATE - CU(HFAC)2 AND HFACH ONPT(111)

The chemistry of the copper CVD precursor Cu(hfaC)2 and of the related hfacH molecule on the Pt(111) surface has been investigated using vib rational (FTIR) spectroscopy, thermal desorption measurements, and Aug er spectroscopy. At high coverages, Cu(hfac)2 adsorption leads to the formation of a 'standing-up'' hfac [OC(CF3)CHC(CF3)O], adsorbed with i ts OCCCO skeleton essentially perpendicular to the surface. In the cas e of hfacH adsorption, and also for lower coverages of Cu(hfac)2, a di fferent surface species is formed that is tentatively identified as '' lying-down'' hfac, i.e., hfac adsorbed with the OCCCO plane essentiall y parallel to the surface. The hfac species begin to decompose below 3 00 K. In the case of a saturated layer of hfacH, a large mass 69 (CF3) thermal desorption signal is observed centered near 295 K, accompani ed by the formation on the surface of both carbon monoxide and fluorin e containing fragments. The carbon monoxide desorbs near 430 K, with n early simultaneous HF desorption. Above this temperature, only two flu orocarbon species are present on the surface in significant concentrat ion. The first (unidentified) fragment is characterized by an intense CF stretch near 1250 cm-1. Between 450 and 750 K it converts to adsorb ed CF2, which desorbs or decomposes below 850 K. Decomposition of the ''standing-up'' hfac formed from Cu(hfac)2 is similar in most respects . These results are compared to those obtained on copper surfaces, and the implications for the CVD of copper onto more reactive substrates are discussed.