Plasma etching anisotropic

Figure C2.13.5. Schematic illustrations of isotropic etching by a neutral gas and anisotropic plasma etching.

Figure 1. Cross sections of films etched with liquid or plasma etchants. The isotropic profile represents no overetch, and can be generated with liquid or plasma etch techniques. The anisotropic profile requires plasma...

Figure 13a shows the resist in a three-layer Al-RIE-PCM system by Havas et al. The dry etching conditions were similar to those of plasma etching. Therefore, an undercut was produced under the Al PCM to facilitate lift-off. Figure 13b shows the resist image in a three-layer siloxane RIE PCM system. The dry etching process was sufficiently anisotropic to eliminate the undercut. 

Plasma etching. (PE) Physical-chemical etching with free radicals, supported by ions. Etching profile anisotropic-isotropic, good selectivity. 

Precise microstructures with nearly any cross-sectional shape can be generated by means of anisotropic plasma-etching methods, where again silicon is the most important and proven material (18,20). Usually, a mask pattern is transferred into a thin layer consisting of a material resistant to plasma etching on a silicon... 

Anisotropic etch on Si can also be achieved by reactive ion etching (RIE), which is a dry (plasma) etch process. In deep RIE, cyclic etch characteristics could be produced on the etched wall [85,86]. 

The principle of nanoimprint is quite simple. As shown in Fig. lA, NIL uses a hard mold that contains nanoscale features defined on its surface to emboss into polymer material cast on the wafer substrate under controlled temperature and pressure, thereby creating thickness contrast in the polymer material, which can be further transferred through the resist layer via an O2 plasma-based anisotropic etching process. Nanoimprint has the capability of patterning sub-10 nm features, " yet only entails simple equipment setup and easy processing. This is the key reason that NIL attracted wide attention within only a few years after its inception. 

To create micromachines, films that have been deposited must be patterned and etched to reveal the desired structures. Often, it is important to etch these structures with vertical sidewalls (anisotropic etching). In this case, most pattern transfer operations (lithography and etch) are carried out using plasma etching. Conceptually, this process is the reverse of deposition. The etching process consists of exposure of the patterned and masked substrate to a low-pressure plasma. The reactive species and ions preferentially etch those areas that are not masked, resulting in the definition of features on the surface. The key to plasma etching is that the products of the reaction of the activated gas and the material to be etched must be volatile (see e.g.. Ref ). 

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