Fabrication and evaluation of self-aligned funnel inlets for DNA analysis in nanochannels

A variety of DNA analysis techniques are enabled by linearization of the macromolecules through physical confinement in nanochannels. This work demonstrates the first nanolithography-free method for creating funneled inlets for nanochannels that are themselves fabricated without nanolithography. A self-aligning, anisotropic funnel etch step was introduced, which widens the entrance of the nanochannel by a factor of 10. Additionally, the shape of the funnel can be controlled by the etch parameters from an 8° inlet angle to 34°. Funneled inlets are suitable to reduce the entropic barrier and increase the amount of DNA molecules introduced into a nanochannel. The funnel etch can be done with XeF 2 when the nanochannels are surrounded by silicon nitride. Simulations of the electric field show how the introduced funnel can increase the capture rate of molecules by increasing the capture range by 20%. The funnels have been shown to bring DNA molecules into the nanochannels, where they are extended. This nanochannel and funnel etch method brings design freedom, while being a low-cost solution that is easily scalable for production of Lab-on-Chip DNA analysis systems.