Etch tunnel

Very little will be said here concerning the equipment aspects of plasma etching. There are three basic types of equipment which have been used a) barrel systems, b) planar systems, and c) systems in which the wafers are located downstream from the plasma to be referred to in this paper as downstream etching systems. These plasma etching configurations are shown schematically in Fig. 3.1. Often the barrel systems are used with a perforated metal tube called an etch tunnel which is shown in Fig. 3.1 a and b. The purpose of the etch tunnel is to protect the wafers from the energetic ion and electron bombardment to which waters immersed directly... 

Fig. 3.1. Plasma etching systems, a and b Barrel system with etch tunnel, c Planar system, d Planar system (reactive ion etching or reactive sputter etching mode), e Downstream system...

Barrel etcher with etch tunnel Arbitrary between wafers Division Not applicable 83... 

All plasma exposures were carried out in an IPC (International Plasma Corporation) 2005 capacitance-coupled barrel reactor at 13.56MHz. The reactor was equipped with an aluminum etch tunnel and a temperature controlled sample stage. Pressure was monitored with an MKS capacitance manometer RF power was monitored with a Bird R.F. power meter and substrate temperature was measured with a Fluoroptic thermometer utilizing a fiber optic probe which was immune to R.F. noise. 

Based on these characteristics, porous silicon may be described as a random array of channel-like pores or etch tunnels growing in <100) directions. For the case of n-type silicon these channels are isolated from each other and, for etching in the dark, the pore spacing is approximately equal to the depletion layer width at a planar surface [83-86]. For the case of p-type silicon the channels are interconnected. The... 

EM fungi can also get hold of nutrients from rock mineral by active weathering of rock minerals. The fungus might even do this from rather inert rock materials like granite where it has been shown that mycorrhizal fungi can etch tunnels through the stone mineral (Fig 6.7 and 6.8). 

Fig 6.8. Mycorrhizal hyphae etching tunnels in granite. Top image showing many hyphae growing ofver the surface and bottom image a close up of the hyphae penetrating into the rock. 

FIGURE 3.7 Correspondence between etch tunnels and X-ray topographic region in 4-X region (a) Optical photograph, (b) X-ray topograph. (From Halliburton, L.E. et al. 1985 in Precision Frequency Control Vol 1, eds. E. Gerber and A. Ballato, Chap. 1. Academic Press, Orlando, FL.)... 

Extended defects such as dislocations and fault surfaces can also arise in piezoelectric crystals. These defects have been studied extensively using a number of experimental techniques. One type of extended defect, called an etch tunnel, is shown in Fig. 3.7. It is believed that the growth of such tunnels depends on the control of the initial seed crystal interface and maintenance of a uniform growth rate. It is also possible that interstitial action impurities such as those mentioned previously are involved in etch tunnel formation. 

Figure 5. Oxide replica of aluminum etch tunnels grown in IN HC1+6N H2SO4 at The replica is formed...

Figure 6. Predicted width profiles of aluminum etch tunnels at 70 — 90° C solid lines), along with AICI3 electrolyte concentrations at the dissolving tip surface dashed lines). The attenuation lengths of the predicted exponential width decays were 30, 19, and 11 im at 70, 80, and 90°C, respectively, while values of...

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