Abstract
A novel method has been developed to fabricate submicron beams with galvanic etch stop for Si in TMAH. The different Au:Si area ratios before and after the release of the beams are used to trigger the galvanic etch stop to fabricate submicron single crystal Si beams in standard Si wafers. Before the beams are released from the substrate, the Au electrodes are connected to the substrate electrically. The Au:Si area ratios are much smaller than the threshold value. TMAH etches the Si wafers. After the beams are fully released, they are mechanically supported by the Au wires, which also serve as the galvanic etch stop cathodes. The Au:Si area ratios are much larger than the threshold value. The beams are protected by galvanic etch stop. The thicknesses of the beams are determined by shallow dry etching before TMAH etching. A 530 nm thick beam was fabricated in standard (111) wafers. Experiments showed that the beam thicknesses did not change with over etching, even if the SiO2 layers on the surface of the beams were stripped.
Highlights
Submicron/nano beams are the fundamental structures of mass detection sensors and scanning probes [1,2]
Some methods have been developed to fabricate single crystal Si thin beams, most of which are based on SOI wafers [4,5,6]
The drawback of the method was that the etch rate of (111) plane was not low enough for submicron/nano beams and could cause obvious deviation from designs when the samples were overetched
Summary
Submicron/nano beams are the fundamental structures of mass detection sensors and scanning probes [1,2]. Beams are fabricated on SOI layers and released by etching oxide layers or substrates. It is possible to fabricate single crystal Si submicron/nano beams on standard wafers with (111) oriented Si micromachining [7,8].
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