Etching for

A fonn of anisotropic etching that is of some importance is that of orientation-dependent etching, where one particular crystal face is etched at a faster rate than another crystal face. A connnonly used orientation-dependent wet etch for silicon surfaces is a mixture of KOH in water and isopropanol. At approximately 350 K, this etchant has an etch rate of 0.6 pm min for the Si(lOO) plane, 0.1 pm min for the Si(l 10) plane and 0.006 pm miiG for the Si(l 11) plane [24]. These different etch rates can be exploited to yield anisotropically etched surfaces. 

Etch Mechanisms. Most wet etches for the compound semiconductors employ oxidation of the semiconductor followed by dissolution of the oxide. For this reason, many wet etches contain the oxidant hydrogen peroxide, although nitric acid can also be used. One advantage of wet etching over dry is the absence of subsurface damage that is common with dry etching. Metal contacts placed on wet-etched surfaces exhibit more ideal characteristics than dry-etched surfaces. 

Figures 3(b) and 3(c) were the EDS results of the etched nanodot arrays shown in Figs. 2(b) and 2(c). The EDS of Fig. 3(b) was almost identical to that of Fig. 3(a). It means that niobium oxide masks were still on Si film although the Si dots were formed. Fig. 3(c) was the EDS result of the nanodot arrays etched for longer etch time than Fig. 3(b). The Nb peak disappeared due to the increased etching and it was confirmed that the nanodots consisted of only Si. The diameters of Si nanodots were approximately 20 30 nm. It was demonstrated that the optimal etching condition could form close-packed and highly ordered Si nanodot arrays without niobium oxide mask. It is expected that this novel technique of forming...

Fig. 2. FESEM images of (a) niobium oxide arrays before etching, and of Si nanodot arrays etched for (b) 20 s and (c) 30 s at 20% CI2, 500 W coil rf power, 300 V dc-bias voltage and 5 mTorr gas pressure...

Fig. 4. XPS spectrum of (a) as-deposited Co2MnSi films and XPS spectra of Co2MnSi films etched for (b) 0.5 min, (c) 1 min...

Step 9 KOH anisotropic etching for 3hr and 40 minutes until only 60pm silicon left... 

An example of the ability of atomic hydrogen to passivate the electrically active damage created by Ar2+ ion beam (6 keV) bombardment of n-type (N = 1.5 x 1016 cm-3) Ge is shown in Fig. 8. In this case the Ge was sputter etched for 10 min. at 24°C or 100°C and the spectrum recorded using an evaporated Au Schottky contact. The damage created by the sputtering caused the rather broad peak of Fig. 8(i), which was unaffected by a 30 min. anneal at 200°C in molecular hydrogen. Heating in atomic... 

Figure 5. RBS spectra of a m-cresol novolac film treated with TiCU for 2 mins, (dotted line) and then etched for 30 mins, by O2 RIE (solid line).

Table II summarizes surface roughness values measured for PMMA and VMCH samples etched for 1.0 minute at 35mTorr at various power densities. Although the measured values of 80 - 105 A fall within the ranges obtained from the interferometer and transition layer theory, there is no significant variation with power density. Differences in surface roughness between pre-etched films of PMMA and VMCH are also negligible according to the stylus measurements.

For all runs, there is a clear decrease in measured pit density with increasing C/CQ ratio. In the closed experiments, pit densities reach background levels (<3 x 10 cm ) at C/C = 0.75. In the flow experiments, samples from crystal R5 (etched for 6.5 hours) and R5SE (crystal R5 after etching 6.5 hours cleaned and re-etched for 25 more hours) show background levels (1 x 10 cm"" ) above C/CQ 0.8. Figure 3 shows R5SE surfaces etched above and below 0.8 CQ. 

Chromic or sulfo-chromic acid etching, for polyolefins, polystyrene, ABS, polyacetal, polyphenylene ether. .. These treatments have two effects ... 

Sodium naphthalene etching or Tetra Etch for PTFE improves the surface roughness and creates unsaturated bonds, carbonyl and carboxyl groups. 

Figure 9. Concentration depth profiles of oxygen obtained from RBS measurement of plasma-treated PE and that of plasma-treated and water etched for 24 hours [78].

Table 4. Result of evaluation of XPS C(ls) peak for the PE samples 1 and 24 hours after the plasma treatment and plasma treated PE sample subsequently water etched for 24 hours. Concentrations of selected groups...

Instead of hydrating the sections, they may be etched for 1 or 2 min with a freshly prepared saturated solution of sodium mefa-periodate. 

The second definition of the purpose of a carrier was to remove the overburden of material above a surface above the device plane. For present purposes, we define the device level as the boundary between the material one wishes to remove and the material one wants to keep. It is not necessarily planar, and it moves up with each layer. For oxide CMP, this layer lies within the topmost film layer. For metal CMP, this surface is defined by the topmost surface of the dielectric into which lines and vias are etched for a damascene process. This definition must accommodate a wafer with a modest amount of bow, tilt, warp, and total thickness variation. Furthermore, it must accommodate very modest amounts of bow, warp, tilt. 

The SiC Schottky diodes and capacitors that have been processed by the authors were processed on either 6H or 4H substrates (n-type, about 1 x 10 cm ) with a 5-10- m n-type epilayer (2-6 x lO cm" ) [123, 124]. A thermal oxide was grown and holes were etched for the metal contacts. In the case of the Schottky sensors, the SiC surface was exposed to ozone for 10 minutes before deposition of the contact metal. This ozone treatment produces a native silicon dioxide of 10 1 A, as measured by ellipsometry [74, 75]. The MISiC-FET sensors (Figure 2.9) were processed on 4H-SiC, as previously described [125]. The catalytic metal contacts consisted of 10-nm TaSiyiOO-nm Pt, porous Pt, or porous Ir deposited by sputtering or by e-gun. 

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