Experimental investigation on anisotropic surface properties of crystalline silicon

Anisotropic etching of silicon has been studied by wet potassium hydroxide (KOH) etchant with its variation of temperature and concentration. Results presented here are temperature dependent etch rate along the crystallographic orientations. The etching rate of the (111) surface family is of prime importance for microfabrication. However, the experimental values of the corresponding etch rate are often scattered and the etching mechanism of (111) remains unclear. Etching and activation energy are found to be consistently favorable with the thermal agitation for a given crystal plane. Study demonstrate that the contribution of microscopic activation energy that effectively controls the etching process. Such a strong anisotropy in KOH allows us a precious control of lateral dimensions of the silicon microstructure. Keywords: microfabrication; activation energy; concentration; anisotropy; crystal plane DOI: http://dx.doi.org/10.3126/bibechana.v8i0.4828   BIBECHANA 8 (2012) 59-66 

Experimental investigation on anisotropic surface properties of crystalline silicon

Anisotropic etching of silicon has been studied by wet potassium hydroxide (KOH) etchant with its variation of temperature and concentration. Results presented here are temperature dependent etch rate along the crystallographic orientations. The etching rate of the (111) surface family is of prime importance for microfabrication. However, the experimental values of the corresponding etch rate are often scattered and the etching mechanism of (111) remains unclear. Etching and activation energy are found to be consistently favorable with the thermal agitation for a given crystal plane. Study demonstrate that the contribution of microscopic activation energy that effectively controls the etching process. Such a strong anisotropy in KOH allows us a precious control of lateral dimensions of the silicon microstructure. Keywords: microfabrication; activation energy; concentration; anisotropy; crystal plane DOI: http://dx.doi.org/10.3126/bibechana.v8i0.4828   BIBECHANA 8 (2012) 59-66 

THERMAL INDUCED MICROSTRUCTURES OF KOH ETCHED SILICON SURFACE

Anisotropic KOH etching of silicon for the fabrication of Micro-electro mechanical system (MEMS) part is based on surface finish and angular dependence of etch rate, creating thin diaphragm. The absolute values of orientation dependent etch rate is found to vary with thermal agitation. In this work, experimental results of etch rate is found quite consistent with simulated and are justify with their unusual values of activation energy along different planes. The various sites that an atom can occupy are not equivalent of their energy; some are more favorable to removal than others. In this paper attention is given to demonstrate thermal activation energy is the prime parameter that influences the behavior of etching mechanism as well as AFM surface morphology. Lowvoltage contact mode atomic force microscopy (AFM) has been employed to analyze the morphology of the etched silicon surface at relevant different temperature. A systematic variation in morphological growth leads to stabilized surface structure under the influence of associated activation energy is concluded

Thermal Induced Structural Conductivity in LPCVD Polysilicon Film on Silicon Nitride/SiO 2 Capped (100) Silicon

Polysilicon (PS) grains are clustered in an order in the presence of thermal doping of boron in low pressure chemical vapour deposition (LPCVD). PS layer is lying on silicon nitride/silicon dioxide bed over (100) silicon substrate. The doped PS at different temperatures has been analyzed for the grain size and the shape of the clusters, employing non-contact mode atomic force microscopy (AFM). The grain size of the PS remains intact without a significant change with increasing doping temperature. A substantial increase in the cluster size and its density of the grains has been observed. The cluster formation mechanism induced by thermal variation is discussed in the context of recorded AFM images. The clusters lead to PS rings comprising of grains of the size of 100 nm