Thick Macroporous Silicon Membranes: Influence of the Masking Layer on the Underetching Characteristics

(2012) Sensors and Actuators A: Physical : an international journal devoted to research and development of physical and chemical transducers — Vol. 185, p. 66-72 (2012)

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Abstract
Macroporous silicon (MPS) has been demonstrated as an interesting material to be used in different applications including micromachining and chemical sensing. In most of these applications the formation of MPS in patterned areas is required or preferable. In this work we report the results of a study on the selective anodization of patterned p-type silicon substrates to form thick MPS layers. Two challenging issues were identified: (1) overetching at the edge of Si3N4 layers, which causes are principally associated with the electrical properties of the interface between the mask and the substrate and the distribution of carriers across the patterned area; (2) adherence of organic masking layers at the silicon during the anodization. Metallic Au/Ti masking layer was demonstrated to be a valuable solution to both issues. SEM cross-sectional views of macroporous layers formed on silicon substrates patterned using different materials are shown and analyzed. Experimental results are supported by two-dimensional (2D) simulations of the silicon/mask/electrolyte interface.
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Bassu, M., Scheen, G., & Francis, L. (2012). Thick Macroporous Silicon Membranes: Influence of the Masking Layer on the Underetching Characteristics. Sensors and Actuators A: Physical : an international journal devoted to research and development of physical and chemical transducers, 185, 66-72. https://doi.org/10.1016/j.sna.2012.06.019 (Original work published 2012)