Bosch etch

The post heights were 55 pm and 75 pm for the wet HF and Bosch etches, respectively. Three posts were chosen on each sample two 200-pm diameter... 

The top surfaces of the replicate posts show small deviations from the stamp as well. There are some observed distortions in the topography of the replicate posts. These distortions are due to the adhesion of the plastic to the metal during release of the replicate from the stamp. The performance of the post pattern is not compromised, because fluids are intended to move around the posts and not over the top surface. The area measurements from nominal-to-stamp and from stamp-to-replicate for the Bosch etch have a higher overall deviations from the nominal structures when directly compared to the HF glass etch post structures. 

FIGURE 18.2 Scanning electron micrographs of silicon microneedles, (a) Silicon microneedles micro-fabricated using a modified form of the BOSCH deep reactive ion etching process. The microfabrication process was accomplished at CCLRC Rutherford Appleton Laboratory (Chilton, Didcot, Oxon, UK). The wafer was prepared at the Cardiff School of Engineering, Cardiff University, UK. Bar = 100 pm (b-d) platinum-coated silicon microneedles prepared using a wet-etch microfabrication process performed at the Tyndall National Institute, Cork, Ireland. Bar = 1 mm (b), 100 pm (c,d). 

Laermer F, Schilp A (Robert Bosch GmbH). Method of Anisotropically Etching Silicon. U.S. Patent No. 5501893, 1996. 

The rapid mixer is composed of layers that are fabricated separately and then assembled together. The main four channel device, represented by the cartoon of Fig. 12.2, is etched through a 1-mm-thick silicon wafer using an anisotropic Bosch process RIE (Unaxis 770, Unaxis). The depth of this etch requires a thick mask. We use a 7 pm layer of PECVD silicon dioxide (GCI PECVD Group Sciences Incorporated, San Jose, CA). This mixer is sandwiched between two 100 pm thick poly(dimethylsiloxane) (PDMS) layers (Duffy et al, 1998), which contain channels in a T configuration. 

The anisotropic nature of the etching by RIE and DRIE is a result of the directionality of the impinging ions. Sometimes it is useful to etch very deep channels or holes. Using conventional DRIE, some tapering of the sidewall profile is expected. However, an etching process has been developed where sequential etch/passivate steps are performed. This etching process, called the Bosch process, uses conventional DRIE methods as process gases for a short period of time, interrupts... 

F. Larmer, A. Schilp, K. Funk, M. Offenberg, Bosch deep silicon etching improving uniformity and etch rate for advanced MEMS applications, Proc. MEMS 99, Orlando, FL, USA, 211-216, Jan. 17-21, 1999. 

For automotive applications, the various functions require several special material properties. Here, we concentrate on properties of thin films rather than on their production processes. A wide range of publications deal with sensor-specific processes, for example, silicon reactive ion etching (RIE) using the Bosch trench process [2] and sacrificial oxide etching [3, 4]. The details of standard deposition and structuring processes are described in numerous books on semiconductor technology (e.g., [5, 6]), and they are not discussed in depth here. 

Bosch process Deep reactive-ion etching (DRIE) Etching single crystalline materials Physical-chemical etching Potassium hydroxide (KOH) etching Silicon etching... 

Among the available anisotropic process schemes and recipes, the Bosch process which is named after the German company that developed and patented the technique is recognized as a standard process for ICP system. The Bosch approach is based on a variation of the Teflon-film sidewall passivation technique which avoids the recombination of active species in the gas phase. The deposition and etching steps are performed subsequently to control the sidewall profile of the 3D structures. In the deposition step, the precursor gas (CF4, C4Fg, CHF3, C2F6, or... 

Advanced silicon etching (ASE ) Bosch Vanderbilt University, Nashville, TN, USA process DRIE (Deep reactive ion etching) ... 

Reactive Ion Etching a (RIE), Fig. 7 (a) Bosch process schematic repetition of etch and deposit pulses. SEM images of etched structures ... 

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