Full Factorial Design (2^k) for 45 Degree of Wall Angle in Anisotropic Wet Etching Process

admin June 27, 2019

Authors:

Alonggot Limcharoen Kaeochotchuangkul,Pathomporn Sawatchai,RungrueangPhatthanakun,Komgrit Leksakul,

DOI NO:

https://doi.org/10.26782/jmcms.2019.06.00001

Keywords:

Anisotropic Wet Etching,Silicon and Silicon dioxide, Hillock,ltrasonic Agitation,45 ̊ Wall Angle,Design of Experiment,

Abstract

This research aims to discover the optimal anisotropic wet etching condition in order to reduce hillocks that occur on the etched surface or reduce roughness and increase etch rate for 45 degree of wall angle (micro-mirror) of a silicon substrate by adopting a design of experiment (DOE) technique and the factorial 2k. Three potential factors which are an ultrasonic mode, a speed motor and a sample orientation, are employed in the factorial design. Analysis of variance (ANOVA) at a p-value significance level of 0.05 is used to assess the significance of the factors on an etch rate and a surface roughness (Ra). The silicon substrates were etched in 20 wt. % sodium hydroxide (NaOH) with Isopropyl alcohol (IPA) at 60 ͦC of solution temperature. An experiment with 24 runs, eight conditions and three replications for each condition, was performed and it was found that the ultrasonic mode was a significant factor which affected the etch rate. An ultrasonic mode and a speed motor were significant factors influencing the surface roughness (Ra). The optimal conditions of 45 degrees of wall angle of a silicon substrate, which were the maximum etch rate and the minimum roughness, were investigated by using a desirability optimization technique in sense of a soft mode of ultrasonic, a speed motor of 5 rpm and a vertical orientation with a desirability value of 0.7619. Finally, the optimal conditions were verified with experimental result

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Alonggot Limcharoen Kaeochotchuangkul, Pathomporn Sawatchai, Rungrueang Phatthanakun, Komgrit Leksakul View Download