Cryogenic etch process development for profile control of high aspect-ratio submicron silicon trenches

Abstract

Nanofabrication of high aspect ratio (∼50:1) sub-10 nm silicon nanowires using inductively coupled plasma etching J. Vac. Sci. Technol. B 30, 06FF02 (2012); 10.1116/1.4755835 Cryogenic inductively coupled plasma etching for fabrication of tapered through-silicon vias J. Vac. Sci. Technol. A 28, 719 (2010); 10.1116/1.3281005 Model for aspect ratio dependent etch modulated processing J. Vac. Sci. Technol. A 28, 334 (2010); 10.1116/1.3305716Profile control of high aspect ratio trenches of silicon. I. Effect of process parameters on local bowing A cryogenic etch process using low temperature ͑T ഛ −100°C͒ and SF 6 and O 2 gases is presented for fabricating high aspect ratio silicon microstructures, including photonic devices and micro-and nanoelectromechanical systems. The process requires only a single electron beam resist mask and results in open area etch rates of 4 m / min. Various etch process parameters, including O 2 flow, rf forward power, substrate temperature, and chamber pressure were studied, and the resulting effect on the etch quality was evaluated in terms of sidewall verticality and surface roughness. The optimized process uses low temperature ͑T =−110°C͒ and low chamber pressure ͑P = 7 mTorr͒ and enables sidewall verticality greater than 89.5°with roughness of 1 -10 nm. A silicon etch selectivity of 26:1 was obtained for 380 nm thick electron beam resist. Using the optimized process, a silicon-on-insulator Fabry-Pérot optical cavity with integrated rib waveguides and deeply etched silicon/air distributed Bragg reflector mirrors was fabricated and tested. The device exhibits sharp resonance peaks with full width at half maximum ⌬ = 0.45 nm, free-spectral range of 26 nm, finesse F = 58, and quality factor Q = 3400 ͑at 0 = 1531.6 nm͒. The optical measurements and extracted mirror reflectance ͑R Ϸ 95% ͒ confirm the high quality of our optimized etch process.

High precision positioning of plasmonic nanoparticle based on damascene process

“…Here, we present a new fabrication route for plasmonic nanostructures based on electron beam lithography, Si cryo etching [13] and the damascene process for filling up Si nanopores with single metal particles.…”

Cryogenic Etching of Silicon: An Alternative Method for Fabrication of Vertical Microcantilever Master Molds

“…They achieve aspect-ratios >10:1. Their optimized process is used for making integrated rib waveguides for photonics applications [16]. However, even when an appropriate set of parameters has been determined, they are not necessarily applicable to all designs, and the process must be tuned for each specific mask layout and final desired etch profile.…”

Damage Free Cryogenic Etching of a Porous Organosilica Ultralow-k Film

“…6,7 At cryogenic temperature, etching product (SiO x F y ) 8,9 condenses at the surface of low-k material and protects the sidewall from being eroded. 10 This passivation layer in the trench bottom is consumed due to ion bombardment. In this work, the influence of the chuck temperature and bias power has been investigated with blanket low-k films.…”