Enabling Large-Area Selective Deposition on Metal-Dielectric Patterns using Polymer Brush Deactivation

Abstract

Area-selective deposition could be an important self-aligning material-deposition technique to enable future nanoelectronics by accurately placing active materials at previously defined substrate patterns. We describe a robust self-aligning strategy to pattern uniform gold (Au) thin films on only the dielectric areas of prepatterned copper/silicon dioxide (Cu/SiO2) substrates. The use of an amine-terminated polystyrene polymer brush (i.e., PS-NH2) to selectively block micrometer Cu regions of patterned Cu/SiO2 substrates is demonstrated. Following thermal evaporation of ∼35 nm thick Au films on PS-NH2 modified Cu/SiO2 surfaces and subsequent acetic acid etching, large-area selective patterning of Au films on SiO2 regions was achieved. We evaluated the influence of the initial PS-NH2 polymer brush film concentration and etching conditions to optimize the process window for the demonstration of highly successful area-selective deposition on SiO2 surface regions. X-ray photoelectron spectroscopy and scanning electron microscopy analysis show the high selectivity of the initial polymer brush deposition process. Auger electron spectroscopy and transmission electron microscopy data reveal the distinct interfaces at the substrate surface after Au area-selective deposition. The technique is highly reproducible with no discernible deposition of Au on Cu over macroscale areas after etching. The process involves relatively short and inexpensive processing steps compared to previously reported methods. The accuracy and precision exemplified in this work to dictate metal deposition at desired substrate areas make the process appealing for future semiconductor practices.

Green Nanofabrication Opportunities in the Semiconductor Industry: A Life Cycle Perspective

“…Polymer brushes can be defined as long chain polymer molecules that are attached to an interface or surface by some means [ 65 ]. They can be used for ASD to facilitate selective patterning of large substrate areas [ 11 , 17 ]. For example, in poly(2-vinylpyridine) (P2VP) or poly(4-vinylpyridine) (P4VP) brushes, it is the presence of an unshared electron pair on the nitrogen atom of the pyridine ring that facilitates coordination bonding with various metal species [ 66 ].…”

“…For example, in poly(2-vinylpyridine) (P2VP) or poly(4-vinylpyridine) (P4VP) brushes, it is the presence of an unshared electron pair on the nitrogen atom of the pyridine ring that facilitates coordination bonding with various metal species [ 66 ]. Conversely, Polymer brushes such as polystyrene (PS) can be used for surface deactivation to block metals adhering to the substrate [ 17 , 21 , 67 , 68 ].…”

“…ASD as mentioned previously can be used for polymer-based pattern formation to activate or deactivate a surface region. The capability of polymer brushes to poses high grafting densities make them an appealing option for surface activation or deactivation [ 17 ]. The quality of polymer brush deposition or attachment to the substate requires carful optimisation to achieve monolayer formation, which determines the regularity of the inorganic film [ 21 ].…”

“…It is the chemical incompatibility of the BCP blocks that enables self-assembly into a variety of morphologies [ 13 , 14 , 15 ]. The molecular mechanisms of ASD and DSA technologies must be better understood before these techniques can be integrated into semiconductor manufacturing processes [ 11 , 16 , 17 , 18 ].…”

Area-Selective Deposition of Ruthenium by Area-Dependent Surface Diffusion

“…To date, ASD can be achieved through different approaches, many of which rely on the combined use of surface modifications and vapor phase deposition techniques such as chemical vapor deposition (CVD) [10][11][12][13] and atomic layer deposition (ALD) 4, [14][15] . Surface modifications are typically aimed at suppressing the adsorption of precursor molecules on nongrowth surfaces [16][17][18][19][20][21][22][23][24][25][26][27] . However, the growth and morphology of deposits is not dictated by adsorption alone, but is rather the result of the competition between adsorption, surface diffusion, and aggregation of adspecies [28][29][30][31] (Figure 1).…”