  Silicon nanostructuring imparts unique material properties including
antireflectivity, antifogging, anti-icing, self-cleaning, and/or antimicrobial
activity. To tune these properties however, a good control over features size
and shape is essential. Here, a versatile fabrication process is presented to
achieve tailored silicon nanostructures (thin/thick pillars,
sharp/truncated/re-entrant cones), of pitch down to ~50 nm, and high-aspect
ratio (>10). The approach relies on pre-assembled block copolymer (BCP)
micelles and their direct transfer into a glass hard mask of an arbitrary
thickness, now enabled by our recently reported regenerative secondary mask
lithography. During this pattern transfer, not only the mask diameter can be
decreased but also uniquely increased; constituting the first method to achieve
such tunability without necessitating a different molecular weight BCP.
Consequently, the hard mask modulation (height, diameter) advances the
flexibility in attainable inter-pillar spacing, aspect ratios, and re-entrant
profiles (= glass on silicon). Combined with adjusted silicon etch conditions,
the morphology of nanopatterns can be highly customized. The process control
and scalability enable uniform patterning of a 6-inch wafer which is verified
through cross-wafer excellent antireflectivity (<5%) and water-repellency
(advancing contact angle 158{\deg}; hysteresis 1{\deg}). It is envisioned the
implementation of this approach to silicon nanostructuring to be far-reaching,
facilitating fundamental studies and targeting applications spanning solar
panels, antifogging/antibacterial surfaces, sensing, amongst many others.
