This study investigates how the chemistry of the single (O 2 , N 2 , and H 2 ) and mixed gas sources (N 2 /H 2 ), and the plasma-related operating conditions affects etching and ͑or͒ passivation of siloxane-based polymer ͑HOSP͒ films. Plasmas generated using inadequate power sources and an H 2 -dominating chemistry induced the breakdown of carbonaceous species and over-crosslinking of the HOSP films, sharply degrading the films' dielectric constant (k) and insulating characteristics. However, properly adjusting the power/energy deposition and shifting the mixed gas toward the N 2 -dominant regime generated an N 2 /H 2 plasma that acted positively to protect the films from O 2 plasma damage and retard copper diffusion during thermal annealing. X-ray photoelectron and absorption spectroscopies, along with depth-profiling secondary ion mass analysis, indicated that the passivation effect was due to the formation of a surface nitride-based layer that contained implanted nitrogen atoms of various chemical bonding states including Si-N, C-N, and O-N. The synergistic effect of the mixed N 2 /H 2 gases in the plasma passivation of HOSP films is discussed in terms of previous studies of plasma etching of low-k films and ion nitriding.

A self-aligned, integrated plating technique based on plasma physics and colloidal-related chemistry is proposed to fabricate patterns of ultrathin ͑р20 nm͒ Co-based barriers and copper films in a selective manner on dielectric ͑HOSP™ and SiO 2 ) films using electroless plating. High-resolution X-ray absorption spectroscopy, transmission electron microscopy, and atomic force microscopy reveal that, once properly pretreated by a gaseous plasma (O 2 or H 2 /N 2 ) and hydrogen peroxide (H 2 O 2 ) in a basic aqueous solution, the dielectric films can adsorb highly populated metallic ͑Ni͒ precipitates of sizes approximately from 2 to 4 nm to catalyze the deposition of electroless Co-based barriers. Finally, the capability of this technique to fabricate ''self-aligned'' patterns of barrier and copper is demonstrated and the importance of the plasma pretreatment and hydrogen peroxide ͑in SC-1 solution͒ is discussed.One solution to improve the performance of microprocessors is the implementation of copper as the interconnect metal and low dielectric constant ͑low-k͒ films as the isolating medium, enabling chips to operate with low resistance-capacitance ͑RC͒ delay and cross-talk noise, and reduced power comsuption. 1 Currently, the copper wire is deposited primarily by electrochemical plating such as electroplating and electroless plating. 2,3 However, because copper is highly diffusive and drifting in the surrounding dielectrics even at low temperatures ͑ϳ200°C͒, 4,5 a highly conducting diffusion/drift barrier layer with substantially reduced thickness typically less than ϳ20 nm must be used to separate the Cu and dielectric films. 6 Apart from sputter and chemical vapor deposited transition metal nitride/ carbide thin films ͑TiN, TaN, TiSiN, TaC͒, 7-10 electrolessly plated metal-based ͑Ni-and Co-͒ barriers are receiving extensive attention because of their proven barrier properties of Cu for dielectric layers and Si, improved gap-filling capability, reduced electrical resistivity, and simplified process flow for Cu deposition. 3,11,12 However, due to the dissimilar surfaces of the substrates ͑dielec-tric and nitride/carbide barriers͒ generally lacking catalytic properties, a seeding treatment or surface modification must be invoked to initiate the deposition of electroless barriers or Cu. Traditionally, predeposition of catalyst is obtained by sensitizing and activating in tin-palladium colloidal solutions, 12 activating in tin-free PdCl 2 acidic solutions, 13 or UV-inducing copolymer-grafting molecular modification, 14 thereby forming disjointed catalytic sites on the surface to be metallized. ͑See Ref. 15 for the general methods to form seed layers for the fabrication of copper circuits.͒ However, the major challenge of using electroless plating for circuit fabrication has been the selective patterning of the seed layer, which is further complicated by the requirement of an underlying diffusion barrier. 15,16 In this regard, we present the design of a simple ͑all-electrochemical integrated͒ process using a seeding pr...