Microstructure Fabricated by Monocrystalline Silicon Anisotropic Etching in Sodium Carbonate and Sodium Bicarbonate Solutions

Abstract

Abstract. The fabrication method of microstructure for monocrystalline silicon wafers based on a mixture of sodium carbonate and sodium bicarbonate solutions under different conditions has been studied in this work. The texturization process has been evaluated in terms of the surface morphology size and the coverage rate. The experiments show that the influence of Na 2 CO 3 concentration is significant by varying the concentration between 5 wt% and 30 wt%. It was shown that with the concentration of Na 2 CO 3 changing, the average size of pyramidal varies from 1.20 μm to 2.44 μm. In a word, the surface were not uniform and exhibited wide bright zones in which the texturization process was not successful. However, we find it possible to get a better pyramid structure by the addition of NaHCO 3 . Uniform microstructure in the wafers of monocrystalline silicon were formed with 20 wt% sodium carbonate and 5 wt% sodium bicarbonate at 90 °C for 20 min. Under optimized conditions, the textured silicon wafers surface exhibit a lower average size (about 0.96 μm) and the coverage rate is high.

Degradation of silicon photonic biosensors in cell culture media: analysis and prevention

“…We suggest that the etching of SOI by CCM, as reported here, is also caused by the slight alkalinity of the solution (nominal CCM pH is 7.4 for mammalian cells). In particular, there is a high concentration of sodium bicarbonate in DMEM (3.7 g/L), and this has been reported to etch crystalline silicon on its own [20]. In basic solutions, hydroxide ions (OH − ) initiate the hydrolysis reaction: $\mathit{Si}+2{\mathit{OH}}^{-}+2H_{2}O\to {\mathit{SiO}}_2{\left(\mathrm{italicOH}\right)}_2^{2-}+2H_2$ [21].…”