Area selective deposition using alternate deposition and etch super-cycle strategies.

Area selective deposition (ASD) is a bottom-up process leading to a uniform deposition in only desired areas of a patterned substrate, avoiding the use of photolithography for patterning. However, whatever the strategy used to develop selective deposition by atomic layer deposition, there always comes a time when selectivity becomes defective and growth in undesired substrate areas must be corrected. This leads to the design of ASD by super-cycle alternating deposition and etch. Recent examples from the literature show a great diversity in the design of the etching step and indicate that the optimization of selective deposition by super-cycles is only possible through a careful optimization of the etching step parameters (chemistry, frequency, duration, etc.). In this paper, we discuss how to optimize this step and we show that different approaches can be developed to optimize the overall ASD process throughput, while simultaneously limiting process drift and contamination. We also show that complementary selective properties can prove a valuable leverage enabling ASD processes based on super-cycles, such as structure selective deposition, whereby a difference in thin film morphology in growth and non-growth areas can be smartly taken advantage of during the etching step.

An embedded neutral layer for advanced surface affinity control in grapho-epitaxy directed self-assembly.

Advanced surface affinity control for grapho-epitaxy directed self-assembly (DSA) patterning is essential for providing reliable DSA-based solutions for the development of semiconductor patterning. Independent control of surface affinity between the bottom and the sidewalls of a topographical guiding structure was achieved by embedding an ultrathin layer in the guiding template stack. The implementation of an embedded layer with tunable surface properties for DSA grapho-epitaxy was evaluated and optimized on 300 mm wafers by critical dimension SEM characterization. It was demonstrated that a thin protective layer, placed between the hard mask guiding template and the embedded layer, allows the preservation of the surface properties of the embedded layer during guiding template etching. The DSA performances of this novel grapho-epitaxy integration, using a topographical template patterned with 193 nm immersion lithography, were evaluated by monitoring the success rate and the critical dimension uniformity of the shrunk contacts. FIB-STEM analyses were further carried out to analyze the residual polymer thickness on the resulting contacts. This new integration leads to the control of the polymer residual thickness (a few nanometers) and uniformity (inferior to 1 nm) at the bottom of the guiding template which will facilitate the subsequent DSA pattern transfer.