Copper metallization of hydroxyl-modified amorphous Si:C:H films

Abstract

X-ray photoelectron spectroscopy (XPS) was used to examine the initial stages of copper deposited by Physical vapor deposition (PVD), or sputter deposition, interacting with amorphous silicon:carbon:hydrogen (a-Si:C:H) films and hydroxyl modified amorphous silicon:carbon:hydrogen (a-Si:C:H/OH) films under Ultra-high vacuum (UHV) conditions. Amorphous-Si:C:H films were formed by condensing vinyltrimethylsilane (VTMS) on a titanium substrate (temperature ≤90 K) followed by electron beam bombardment (500 eV), and annealing to 300 K in UHV. Amorphous Si:C:H/OH films were formed by condensing H 2O on the condensed VTMS multilayer (≤90 K) followed by electron beam bombardment (500 eV) and annealing to 300 K in UHV. The stoichiometry of the unmodified and modified a-Si:C:H films was determined by XPS to be C 4.5:Si and C 4.3:O 0.44:Si, respectively. XPS measurements of PVD Cu on the modified film at 300 K indicate initial conformal growth with Cu(I) and Cu(0) formation at the Cu/Si:C:H/OH film interface. At higher Cu coverages, only Cu(0) was observed. In contrast, 3-dimensional island formation (Volmer–Weber growth) of Cu(0) was observed on the unmodified film. Annealing both the modified and unmodified films up to 800 K in UHV produced no significant change in the Cu(3p)/Cu(2p 3/2) intensity ratio, indicating negligible Cu diffusion through the film into the titanium substrate below 800 K.