Nanomoulding with amorphous metals

The small print Shrinking the dimension of features printed onto thermoplastics is critical for the manufacture of high-density storage devices such as CDs and DVDs of ever-greater capacity. The degree of miniaturization that can be achieved is limited in large part by the durability of the materials available for the mould, usually brittle silicon, and its ease of processing. Kumar et al . propose a new method for moulding features down to the 13 nm range using metallic glasses as both mould and — replacing thermoplastic polymers — as imprint materials too. The features made with these materials can in turn be replicated in materials with lower softening temperatures, or they can be erased and moulded again, providing a new way to produce, for example, high-density rewritable devices. This work proposes a new method for moulding features down to the 13-nm range onto amorphous metallic surfaces, which are much more durable materials. The features thus made can in turn be replicated in materials with lower softening temperatures, or they can be erased and moulded again, providing a new way to produce for example rewritable media supports. Nanoimprinting promises low-cost fabrication of micro- and nano-devices by embossing features from a hard mould onto thermoplastic materials, typically polymers with low glass transition temperature 1 . The success and proliferation of such methods critically rely on the manufacturing of robust and durable master moulds 2 . Silicon-based moulds are brittle 3 and have limited longevity 4 . Metal moulds are stronger than semiconductors, but patterning of metals on the nanometre scale is limited by their finite grain size. Amorphous metals (metallic glasses) exhibit superior mechanical properties and are intrinsically free from grain size limitations. Here we demonstrate direct nanopatterning of metallic glasses by hot embossing, generating feature sizes as small as 13 nm. After subsequently crystallizing the as-formed metallic glass mould, we show that another amorphous sample of the same alloy can be formed on the crystallized mould. In addition, metallic glass replicas can also be used as moulds for polymers or other metallic glasses with lower softening temperatures. Using this ‘spawning’ process, we can massively replicate patterned surfaces through direct moulding without using conventional lithography. We anticipate that our findings will catalyse the development of micro- and nanoscale metallic glass applications that