Recent results in the assembly of DNA into structures and arrays with nanoscale features and patterns have opened the possibility of using DNA for sub-10 nm lithographic patterning of semiconductor devices. Super-resolution microscopy is being actively developed for DNA-based imaging and is compatible with inline optical metrology techniques for high volume manufacturing. Here, we combine DNA tile assembly with state-dependent super-resolution microscopy to introduce crystal-PAINT as a novel approach for metrology of DNA arrays. Using this approach, we demonstrate optical imaging and characterization of DNA arrays revealing grain boundaries and the temperature dependence of array quality.For finite arrays, analysis of crystal-PAINT images provides further quantitative information of array properties. This metrology approach enables defect detection and classification and facilitates statistical analysis of self-assembled DNA nanostructures.
IntroductionAs the costs and challenges of semiconductor device scaling increase, 1 new materials and technologies that enable precise patterning and placement of nanostructures are sought to supplement or replace current photolithography techniques. 2 For example, nanoscale patterning through directed self-assembly of block-copolymer (BCP) structures has been acknowledged as a viable and inexpensive lithographic mask via the International Technology Roadmap for Semiconductor manufacturing. 3,4 While progress has been made in the precise control of BCP self-assembly, defect densities and directed self-assembly of complex patterns remain challenges for manufacturing. 5 As an alternative technology, the potential for programmable, long-range order through self-assembly makes DNA an attractive material for bottom-up fabrication of nanoscale patterns, 6 as well as for templated-assembly of electronic and photonic devices with nanometer precision.
7-10Within the last two decades, DNA-based techniques such as origami, 6 tiles, 9 and bricks 11 have demonstrated precise control over the size, shape, arrangement, and assembly of DNA nanostructures and nanocomponents. While much work is still needed to approach commercial viability, lithographically confined DNA origami and large crystalline arrays of DNA origami show potential as self-assembled lithographic masks 12 and templates for precise nanoparticle assemblies.
13-18As a result of these advances, the Semiconductor Research Corporation recently listed DNAcontrolled sub-10 nm manufacturing as a technical area for its future roadmap.
19Beyond the ability to pattern at the nanoscale, metrology of patterned structures is a crucial capability in semiconductor device manufacturing that poses increasing challenges (e.g., cost, throughput, accuracy) as the device dimensions decrease. 20,21 For example, locating dislocations within a nanoscale BCP pattern requires tedious inspection of highresolution scanning electron micrographs. Likewise, common high-resolution imaging techniques used for characterization of DNA nanostructures, such as...