DNA nanotechnology has shown great promise for nanopatterning applications thanks to the ability to nanoengineer rationally designed two and three-dimensional (3D) nano-objects of complex shapes with subnanometer precision and high degree of rigidity . Recently, a self-assembled DNA origami allowing sub-10 nm pattern transfer into SiO2 has been demonstrated . We report here a mechanistic study of a high resolution (10 nm) and high density (10 nm) DNA pattern transfer into a Si substrate. In order to exploit their full potential for lithographic application, the deterministic positioning of the DNA nanostructures on a predefined substrate is still a major challenge to overcome. In a second part of this paper, we present a hybrid nanopatterning process by combining locally chemically modified substrate by top-down technics with bottom-up self-assembly of DNA nanostructures in order to deterministically fix DNA origamis on the substrate. Chemical contrast is formed using conventional lithography in order to create DNA affine and adverse parts on the substrate. The pattern transfer of the DNA nanostructures in the inorganic under layer is demonstrated as well. Thus, DNA origami appears to be a promising emerging approach for the engineering of hard masks for patterning.
Patterning surface with structural DNA origami mask presents a major interest for nanolithography due to its modularity and high ability to achieve a high resolution with 3-5 nm.
In this paper, we demonstrate a sub-ten-nanometer lithography process using anhydrous HF vapor into a SiO2 substrate (figure 1). After optimizing rinsing conditions on SiO2 substrate and HF etching process, we reach a high density (<20 nm pitch) and high resolution (~10 nm CD) patterned surface with a fast etching rate of 0.2 nm.s-1. The resulting SiO2 patterns are used as hard mask in HBr/O2 plasma of Si substrate. Origami pattern features are conserved: lateral dimensions, morphology and structure. For the first time, we developed a high resolution (~10 nm) and high contrast (~65 nm) transfer of patterns into Si substrate.
We will highlight the challenges brought by this new technology and demonstrate the feasibility to control this patterning technique. AFM technique has been previously tested to confirm the pattern fidelity. Using all the available imaging capabilities on the CDSEM, we will establish the best method for each layer to achieve the precision required for the targeted nodes of this technology.
Beyond the resolution capabilities, the precise placement of the DNA pattern on the substrate is investigated. Based on a pre-patterning step using the nanoimprint technology, the affinity of the DNA with respect to the substrate is locally modified and its influence is analyzed.
Thus, DNA origami appears like a promising approach for emerging and engineering of hard mask for patterning.