Direct evidence for the formation of a passivating layer during chemomechanical polishing of silica by a hydrogen difluoride-based reagent

Abstract

The sparingly soluble material (the passivating layer) formed during chemomechanical polishing of silica wafers by [HF,J--cerium(~v) oxide-sucrose mixtures at low pH has been identified as K,SiF, coated with a thin silica layer.

Laser-Assisted Formation of Porous Silicon in Diverse Fluoride Solutions: Hexafluorosilicate Deposition

“…A passivating layer of K 2 SiF 6 has been observed during chemomechanical polishing of silica in the presence of KHF 2 . Boyle et al report an IR spectrum in which the main bands of the thin-film spectrum agree with the bulk spectrum of Badachhape et al In an investigation of the effects of alkali metal and quaternary-ammonium cations on the rate of anodic formation of por-Si, white, sparingly soluble films formed on the external surface in the presence of K + , Rb + , and Cs + . These were identified as hexafluorosilicates. , Stain etching of silicon in HF−oxidant−H 2 O (oxidant = K 2 Cr 2 O 7 , KBrO 3 , or KMnO 4 ) has been studied. , As the concentration of the oxidant is increased, the etch rate increases to a limiting value as the thickness of the K 2 SiF 6 increases.…”

“…A passivating layer of K 2 SiF 6 has been observed during chemomechanical polishing of silica in the presence of KHF 2 . Boyle et al 31 report an IR spectrum in which the main bands of the thin-film spectrum agree with the bulk spectrum of Badachhape et al 32 In an investigation of the effects of alkali metal and quaternary-ammonium cations on the rate of anodic formation of por-Si, white, sparingly soluble films formed on the external surface in the presence of K + , Rb + , and Cs + . These were identified as hexafluorosilicates.…”

“…Evidence of other workers 31,33,35,36,40 suggests that the deposit is K 2 SiF 6 . EDX analysis of the crystals formed in KHF 2 shows that they contain silicon, potassium, and fluorine.…”

Template-free fabrication of silicon micropillar/nanowire composite structure by one-step etching

“…K 2 SiF 6 crystallite, spontaneously generating when the solubility product of K 2 SiF 6 exceeded to 6.3 × 10 −7 mol 3 dm −9 , is a byproduct during the forming process of porous silicon [ 11 ]. Hadjersi et al reported that an insoluble solid-phase film (K 2 SiF 6 ) covered the top of porous silicon layer by the etching of silicon-coated silver film in HF-oxidizing solution [ 14 ].…”

“…Recently, K 2 SiF 6 crystallites have been observed during the different wetting etchings of silicon substrate in the presence of HF and K + ions, such as chemomechanical polishing [ 11 ], stain etching [ 12 ], laser-assisted etching [ 13 ], and metal-assisted electroless etching (MAEE) [ 14 , 15 ]. These K 2 SiF 6 crystallites are insoluble in dilute HF solution and to some extent can prevent the etchant solution from the contact with silicon surface.…”