SPTS’ patented Primaxx® HF/Alcohol process employs a reduced pressure, gas phase environment for the isotropic etch removal of sacrificial oxide layers. The process is generally carried out at pressures between 75 and 150 torr providing controlled, residue-free etching. Typical vertical and lateral oxide etch rates are in the 0.1 - 10

the etch rates of other materials that will be exposed to the etch, such as masking films and underlying layers, enables an etch process to be chosen for good selectivity (high ratio of etch rate of the target material to etch rate of the other material)—if one exists. While several large literature-review compilations in the solution coupled with temperature also effects the etch rate as seen in the following figures. Etch rate of SiO 2 increases with increasing weight % of HF in the etch solution, as well as higher ratios of NH 4 F buffer in the solutions. Etch rate also increases with increasing temperature. Etch rate: r • Speed at which ethcing occurs • Typical unit: r [nm/min] Selectivity : S • Ratio of two etch rates Example 1: SiO 2 etching with hydrofluoric acid (HF): SiO 2+ 6 HF H 2SiF 6 + 2 H 2O A. Determine the etch time for a 1,2 μm thick SiO 2 film with r SiO2 = 400 nm/min 3 min. B. How thick should the resist mask be if the The different equilibria in HF and HF/HCl solutions are examined and the etching reaction of SiO2 is investigated as a function of the different species present in the HF solution. A new model for

Below is a table with the freezing point and etch rates for buffered oxide etch mixtures. Table 1269. Buffered Oxide Etch Data

Etchants | Fujifilm [United States] Fujifilm has advanced capabilities for the precise blending of Buffered Etchants with tight assay specification ranges, available in multiple NH4F:HF ratios Utilized to etch SiO2 films Utilized as pre-diffusion and pre-metallization surface preparations Formulated from high purity 49% Hydrofluoric Acid and high purity 40% Ammonium Fluoride Buffered Oxide Etch STANDARD OPERATING PROCEDURE Both thermally grown and deposited SiO2 can be etched in buffered hydrofluoric acid. However, etching of deposited films proceeds a lot faster than that of the thermal oxide. Densification of the deposited films, by heat treatment at 1000-1200oC for about 15 minutes, results in a fall in the etch rate to approximately the same as that for the

A comparative study of chemical etch rates in diluted HF or a mixture of HF, H2O, and HNO3 (P etch) was performed on conventional thermal silicon oxides (1050–1120 °C; O2 pressure ≊1.1 atm; one type with addition of 0.02% C2H3Cl3) and buried oxide layers. The latter were formed by single or multiple implanting n‐ and p‐type (100) Si maintained at ≊600 °C with 150–200‐keV O+

The Modelization of the Wet Etching Rate by the The commented results are based on the segregation at Si/SiO2. We have developed a “theory” based on an empirical equation which modelizes the etch rate in non doped SiO2, to modelize it for those n-doped and p-doped. This “theory” stipulates that the etch rate in doped SiO2 can be predicted by knowing the etch rate in nondoped one. (PDF) The etching mechanisms of SiO2 in Hydrofluoric acid The different equilibria in HF and HF/HCl solutions are examined and the etching reaction of SiO2 is investigated as a function of the different species present in the HF solution. A new model for BOE / HF – Silicon dioxide Etching Standard Operating