AVS 47th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuP

Paper TF-TuP37
Dry Cleaning of Oxide and Contaminaions on Cu Surface in Water Ambient

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: H. Ogawa, The University of Tokyo, Japan
Authors: H. Ogawa, The University of Tokyo, Japan
K. Taniguchi, The University of Tokyo, Japan
Y. Horiike, The University of Tokyo, Japan
Correspondent: Click to Email
A new cleaning method of the Cu bottom surface in via holes and gaps in the ULSI multi-level interconnection was studied employing in-situ XPS (ULVAC-PHI, model 1600). At first, reduction characteristics of the Cu native oxide (CuO and Cu@sub 2@O) on the Cu surface were investigated in N@sub 2@, H@sub 2@, O@sub 2@ and H@sub 2@O ambient at 1 Torr. Analyses of Cu2p@sub 3/2@ photoelectron and Cu@sub LMM@ Auger electron spectra showed that CuO was reduced to Cu@sub 2@O in any ambient above 150 °C of sa mple temperature, because @DELTA@G@sub f@° of Cu@sub 2@O (-146 kJ/mol) is thermodynamically lower than that of CuO (-130 kJ/mol). Cu@sub 2@O was also found to be reduced to Cu in H@sub 2@, N@sub 2@ and H@sub 2@O ambient above 300 °C. H@sub 2@O dose not act as an oxidant for Cu, because @DELTA@G@sub f@° of H@sub 2@O (-229 kJ/mol) is lower than that of the Cu oxide. Next, oxide formation and hydrocarbon (CH@sub x@) and fluorocarbon (CF@sub x@) contaminations of the Cu surface were prepa red by exposure to ICP (inductively coupled plasma) of C@sub 4@F@sub 8@/Ar (unity partial pressure ratio, 20 mTorr of total pressure, 1 kW of 13.56 MHz, V@sub dc@=400V and 2 min) and subsequent O@sub 2@ (100 mTorr, 10 min) plasma. Then the surface was exp osed by the H@sub 2@O vapor ambient at 1 Torr. As a result, almost CH@sub x@ and CF@sub x@ contaminants were removed at 300 °C, and Cu oxides were completely reduced to Cu at 400 °C, while CH@sub x@ contamination was remained in N@sub 2@ and H@sub 2@ ambient at 400 °C. The reason of high removal efficiency of CH@sub x@ and CF@sub x@ in the H@sub 2@O ambient is considered that H@sub 2@O effectively acts as an oxidant and a reducing agent to these contaminations.