Anisotropic Vapor HF etching of silicon dioxide for Si microstructure release

Damages are created in a sacrificial layer of silicon dioxide by ion implantation to enhance the etch rate of silicon-dioxide in liquid and vapor phase hydrofluoric acid. The etch rate ratio between implanted and unimplanted silicon dioxide is more than 150 in vapor hydrofluoric acid (VHF). This feature is of interest to greatly reduce the underetch of microelectromechanical systems anchors. Based on the experimentally extracted etch rate of unimplanted and implanted silicon dioxide, the patterning of the sacrificial layer can be predicted by simulation

World-to-chip interconnects for efficient loading of genomic DNA into microfluidic channels

A novel sloped interconnect for the efficient delivery of long genomic DNA fragments into a microfluidic channel is designed, fabricated and tested. Out-of-plane slopes are fabricated in silicon wafers using the deep reactive-ion etch lag phenomenon and a combination of anisotropic and isotropic etching. The final structure is capped with anodically bonded glass. Based upon a series of etch-lag calibration studies, the interconnect was designed using finite element analysis to provide a channel with flow acceleration properties appropriate to straighten DNA molecules. The efficiency of transit of the 48.5 kb DNA fragments (~16.5 µm long when fully extended) through the microfluidic device, established using quantitative real-time polymerase chain reaction, is 95 ± 7.3%

Note: Fast and reliable fracture strain extraction technique applied to silicon at nanometer scale

Simple fabrication process and extraction procedure to determine the fracture strain of monocrystalline silicone are demonstrated. Nanowires/nanoribbons in silicon are fabricated and subjected to uniaxial tensile stress along the complete length of the beams. Large strains up to 5% are measured for nanowires presenting a cross section of 50 nm x 50 nm and a length of 2.5 μm. An increase in fracture strain for silicon nanowires (NWs) with the downscaling of their volume is observed, highlighting the reduction of the defects probability as volume is decreased

High-Throughput On-Chip Large Deformation of Silicon Nanoribbons and Nanowires

An on-chip internal stress-based testing device has been developed in order to deform silicon nanoribbons and nanowires up to large strains enabling high throughput of data. The fracture strain and survival probability distribution have been generated for 50-nm-thick and 50- or 500-nm-wide specimens with lengths varying between 2.5 and 10 μm. Fracture strains reaching up to 5% are attained in the smallest specimens, whereas 90% of the specimens survive 2.5% deformation. This testing platform opens an avenue to investigate and use electromechanical couplings appearing under large mechanical stress or large deformation