Channel-constrained electroless metal deposition on ligating self-assembled film surfaces

Channel-constrained metallization is described as a novel process for fabrication of metal features useful as etchmasks and electrical interconnects in microelectronics applications. The method creates a requisite surface reactivity template through patterned exposure and development of photoresist films to open channels to an underlying ligand self-assembled film. Subsequent electroless metal deposition occurs selectively at exposed ligand sites in the channels, which constrain lateral metal growth detrimental to feature critical dimension (CD) control during plating. A characterization of the individual process steps is presented using a positive tone photoresist system as an example. Determination of the exposure and development conditions that promote clearance of photoresist residues from the channels while maintaining adequate feature CD control is identified as an important issue in successfully performing the process. The process has been successfully demonstrated using optical exposure sources and is compatible with a range of substrates relevant for electronics applications, including Si. The high plasma etching selectivity of a thin Ni metal masking layer was used in the fabrication of high aspect ratio structures (less than or equal to 5:1) in Si. (C) 1999 The Electrochemical Society. S0013-4651(98)03-130-9. All rights reserved.