Etch products

Houle F A 1986 A reinvestigation of the etch products of silicon and XeF2 doping and pressure effected. Appl. Phys. 60 3018-27... 

A Dektak siuface profilometer was used to measure the etch rates. The profiles of the etched films were observed by field emission scanning electron microscopy (FESEM). In addition, x-ray photoelectron spectroscopy PCPS) was utilized to examine the existence of possible etch products or redeposited materials, and to elucidate the etch mechanism of Co2MnSi magnetic films in a CVOa/Ar plasma. 

UV Etching. A typical mass spectrum of the vaporized UV etching products is shown in Figure 4, together with a background spectrum obtained without UV irradiation. The comparison clearly shows that UV irradiation causes an increase in intensity for various mass peaks. For example, the intensity of the peaks of m/e=15, 31, 59 and m/e=41, 69 increased drastically by UV irradiation. The former three are due to side-chain scission caused by UV absorption at the C=0 unit, while the latter two are due to main-chain scission initiated by side-chain scission (11). The structure and mass numbers of typical vaporized species are shown in Table I. From here on, we use the spectral intensity after the background is subtracted. 

Chlorine-based plasma etching of aluminum films causes serious degradation of photoresist materials. To some extent, these effects are a result of the etch product, AICI3. Aluminum trichloride is a Lewis acid used extensively as a Friedel-Crafts catalyst. Therefore, it is hardly surprising that this material reacts with and severely degrades photoresists (74). 

Figure 26. Experimental configuration for monitoring optical emission from etch products using an auxilliary discharge located downstream from the etch reaction zone. (Reproduced with permission from Ref. 119.)...

Figure 27. End point detection of a native oxide/silicon interface using chemiluminescence from Sip3 formed by the reaction of the etch product Sip2 with P and P2. Etching was performed with P atoms downstream...

Unfortunately, since ion milling is a purely physical process, selectivity is generally poor. Indeed, selectivity in such systems depends almost exclusively on differences in sputter yield between materials. Finally, since the etch products are not volatile, redeposition and trenching can be serious limitations (146). 

Finally, it should be mentioned that, in the case of etching plasmas, any of the mass spectrometric or optical spectroscopic methods described in Sect. 2.1.4 could in principle be calibrated to measure the etch rate simply by monitoring the etch product. This approach, has been used for end-point detection in the etch process These methods may also be applicable to polymerizing plasmas where interesting correlations between the concentration of certain gas phase species and polymerization rate have been noted s . ... 

The exact nature of the hydrolysis products is not well established, however, the generation of HF is clear. Such ionic liquids have been observed to etch their glass containers and, in one case, a small explosion occurred when there was a build up of gas pressure in the bottle (presumably from the etch products). Notably, a number of PFg- ionic liquids are water immiscible nonetheless they are able to dissolve... 

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