Buffered Oxide Etchants0 pages

TECHNICAL PRODUCT INFORMATION
Buffered Oxide Etchant
• FUJIFILM Buffered Oxide Etchants are silicon oxide etchants formulated
from high purity 49% Hydrofluoric Acid and high purity 40% Ammonium
Fluoride.
• Formulations are available in standard NH4F:HF ratios or made to
customer specification.
• Stringent control of both hydrofluoric acid and ammonium fluoride
content ensures lot to lot reproducibility of etch rate characteristics.
• A Certificate of Analysis is provided with every lot and includes assay,
trace metal analysis, and particle count analysis at 02µ and 0.5µ.
• Formulations are also available with OHS™ to improve surface wetting
and promote etch uniformity.
• Buffered HF's are also used as pre-diffusion and premetallization surface
preparations. Buffered hydrofluoric
• Etch rates may also vary in SiO2 films due to changes in film densities
that result from the presence of dopants. These variations are impacted
by dopant type and concentration.
• Phosphorous doped films are less dense and tend to etch
faster. An increase in phosphorous concentration will increase
etch rates.
• Boron doped oxide (borosilicate glass) is more dense and tends
to etch slower.
• Elevated temperatures also increases SiO2 sidewall sloping.
• Etching should be done in polypropylene, polyethylene, Teflon® or other
fluorocarbon containers.
• To minimize fluctuations in etch rate, etch bath temperature should be
controlled to ±0.5°C.
• Substrates can be etched for a predetermined time or to visual dewet. A
10 to 20 second overetch ensures isolation of features.

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