Fabrication of a beam-mass structure using single-step electrochemical etching for micro structures (SEEMS)

Abstract

This paper presents a new wet etching technique for micromachining called single-step electrochemical etching for micro structures (SEEMS), which is based on electrochemical etching in hydrofluoric acid. During the etching, the shape of the etched structure can be controlled by changing the light intensity. Several problems involved in the SEEMS process had to be solved. The two main problems are, firstly, that over-etching can be seen at the clamping point of the free standing beam and, secondly, it is difficult to remove large areas. These problems can be considerably reduced by an improved mask layout and a perforated mass supported by a single cantilever can be achieved. In addition, a new initial pit formation is demonstrated to make structures which are free from crystal orientation of silicon substrate.

Plasma etched initial pits for electrochemically etched macroporous silicon structures

“…Consequently, no sharp stepwise modulation of the pore diameter can be realized in this way. On the other hand, an even larger increase in the photocurrent can reduce the wall thickness to zero, leading to the joining of macropores at the bottom [6]. The macropore array is then separated from the substrate, resulting in a free-standing macroporous film.…”

“…Recent reports show that satisfactory results can also be reached by using double-side polished wafers and adjusting the etching parameters more precisely, but the pattern density effects remain to be explained [6,11]. This needs to be clarified before electrochemical etching can be used as a micromachining tool.…”

“…In order to obtain regular pores, the initial pits are made by photolithography. The anisotropic alkaline wet etching and RIE techniques can be applied to prepare initial pits, which can then be transformed into deep structures by means of electrochemical etching [6]. The macropore morphology depends sensitively on the pre-patterning geometry, the anodization conditions and substrate properties [7].…”

Single wafer fabrication of a symmetric double-sided beam–mass structure using DRIE and wet etching by a novel vertical sidewall protection technique

“…In the creation of beams and beam-mass structures, extensive work has been carried out using wet etching or deep reactive ion etching (DRIE) or combination of both. DRIE offers the potential to achieve features with a very high aspect ratio, while wet etching has many inherent advantages including low process cost, high etching rate, good surface smoothness, high degree of anisotropy and low environmental pollution [2][3][4][5][6][7][8][9]. In many cases, both DRIE and wet etching are implemented: the mass is often first 4 Author to whom any correspondence should be addressed.…”

Prototyping of Diffractive Grating Optics for Sensor Application by an Integrated Probe-Based System

“…Hot embossing [Chou et al, 1995] is suitable for foil application, but not for high-performance DOE or any production with microstucture fidelity requirements. Photolithography [Roth et al, 1999], microcontact printing [Kim et al, 1996], and scanning electrochemical microlithography techniques [Ohji et al, 2000;Said, 2004] can be employed for fabrication of microstructures, but these techniques possess significant limitation for patterning structures of nano-meter scale.…”