Gas-Phase HF/Vapor Etching of Thermal Silicon Dioxide Films

Molecular Lithography through DNA-Mediated Etching and Masking of SiO2

“…Experimental evidence based on in situ FTIR spectroscopy has suggested that HF and H 2 O molecules form a HFÀH 2 O complex that adsorbs on the SiO 2 surface more strongly than either molecule alone. 21,22 Other mechanistic studies 21 have suggested that the etching reaction starts with the deprotonation of HF by water to generate HF 2 À ions:…”

“…The vapor-phase etching of SiO 2 using HF gas is characterized by the thermodynamically favorable reaction between SiO 2 and HF gas to produce SiF 4 and H 2 O: SiO 2 false( normals false) + 4 HF false( normalg false) → SiF 4 false( normalg false) + 2 H 2 O false( normalg false) However, to overcome the kinetic barrier, water is needed as a catalyst in the reaction, since HF alone does not etch SiO 2 . Experimental evidence based on in situ FTIR spectroscopy has suggested that HF and H 2 O molecules form a HF–H 2 O complex that adsorbs on the SiO 2 surface more strongly than either molecule alone. , Other mechanistic studies have suggested that the etching reaction starts with the deprotonation of HF by water to generate HF 2 – ions: 6 HF + 3 H 2 O → 3 HF 2 − + 3 H 3 O + These ions then etch away SiO 2 to produce water and other gaseous products: 3 HF 2 − + 3 H 3 O + + SiO 2 → 2 HF + SiF 4 + 5 H ...…”

Determination of the Model for the Chemical Structure of Porous PECVD Low-k Films

“…A high number of papers on the etching mechanisms of HF on SiO 2 have been published and many different etch mechanisms have been proposed. 9,10 There is a consensus that HF, without the presence of H 2 O, etches SiO 2 extremely slowly: H 2 O acts as a catalyst for the HF etching of SiO 2 . 9,11 A wetted Si-O surface, hence, etches much faster (order(s) of magnitude) than an unwetted Si-O surface.…”

“…9,10 There is a consensus that HF, without the presence of H 2 O, etches SiO 2 extremely slowly: H 2 O acts as a catalyst for the HF etching of SiO 2 . 9,11 A wetted Si-O surface, hence, etches much faster (order(s) of magnitude) than an unwetted Si-O surface. Besides, it has been shown that the etch rate of SiO 2 in HF depends on many factors and that reproducibility is not always very good.…”