Toward individually addressable nanometer size surface pixels: Ultrathin dendrimer films as resists for scanning probe lithography

Scanning probe lithography (SPL) has recently been shown to be a versatile technique for patterning semiconductor surfaces. The intense electric field emanating from the scanning probe tip can be used for the patterning of carbon-based self-assembled monolayers and thin films, as well as the anodization or field-enhanced oxidation of passivated metal surfaces. We have been investigating the use of monolayers and ultra-thin films made from dendritic polymers as resists for SPL. Dendrimer films have been prepared by both covalent and ionic binding to the wafer surface. Silicon wafers were treated with dendritic chlorosilanes to afford self-assembled monolayers from the functionalized dendrons. Ionically bound dendrimer films were prepared by treating an aminopropylsilane-modified wafer surface with a dendritic carboxylic acid. These ultra-thin dendrimer films were characterized by atomic force microscopy (AFM), contact angle goniometry, and optical ellipsometry. The dendrimer films were shown to be effective resists for SPL, and we have patterned negative tone oxide images onto dendrimer modified wafer surfaces. Pattern transfer can be achieved by a selective wet etch resulting in the formation of positive tone images.