Selective Etching of Silicon in Preference to Germanium and Si0.5Ge0.5

The selective etching characteristics of silicon, germanium, and Si0.5Ge0.5 subjected to a downstream H2/CF4/Ar plasma have been studied using a pair of in situ quartz crystal microbalances (QCMs) and X-ray photoelectron spectroscopy (XPS). At 50 °C and 760 mTorr, Si can be etched in preference to Ge and Si0.5Ge0.5, with an essentially infinite Si/Ge etch-rate ratio (ERR), whereas for Si/Si0.5Ge0.5, the ERR is infinite at 22 °C and 760 mTorr. XPS data showed that the selectivity is due to the differential suppression of etching by a ∼2 ML thick CxHyFz layer formed by the H2/CF4/Ar plasma on Si, Ge, and Si0.5Ge0.5. The data are consistent with the less exothermic reaction of fluorine radicals with Ge or Si0.5Ge0.5 being strongly suppressed by the CxHyFz layer, whereas, on Si, the CxHyFz layer is not sufficient to completely suppress etching. Replacing H2 with D2 in the feed gas resulted in an inverse kinetic isotope effect (IKIE) where the Si and Si0.5Ge0.5 etch rates were increased by ∼30 times with retention of significant etch selectivity. The use of D2/CF4/Ar instead of H2/CF4/Ar resulted in less total carbon deposition on Si and Si0.5Ge0.5 and gave less Ge enrichment of Si0.5Ge0.5. These results are consistent with the selectivity being due to the differential suppression of etching by an angstrom-scale carbon layer.

Medienart:

E-Artikel

Erscheinungsjahr:

2017

Erschienen:

2017

Enthalten in:

Zur Gesamtaufnahme - volume:9

Enthalten in:

ACS applied materials & interfaces - 9(2017), 24 vom: 21. Juni, Seite 20947-20954

Sprache:

Englisch

Beteiligte Personen:

Ahles, Christopher F [VerfasserIn]
Choi, Jong Youn [VerfasserIn]
Wolf, Steven [VerfasserIn]
Kummel, Andrew C [VerfasserIn]

Links:

Volltext

Themen:

Deuterium etching
Downstream plasma
Inverse kinetic isotope effect
Isotropic etching
Journal Article
Kinetic isotope effect
Plasma etching
Selective etching
Silicon and germanium etching

Anmerkungen:

Date Completed 27.07.2018

Date Revised 27.07.2018

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1021/acsami.7b02060

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM272195480