These etch rates are intended as a guide. Actual etch rates will vary, please verify before use. Film: 10:1 Buffered Oxide Etch: 10:1 Buffered Oxide Etch with Surfactnat: 5.2:1 Buffered Oxide Etch: 50:1 HF: 16:3:3 Pad Etch. 40% KOH @85°C: Phosphoric Acid @165°C: Phosphoric Acid @175°C: 16:1:1:2 Aluminum Etch @40°C

Briefing buffered chemical polishing (BCP) State-of-the-application in cavity processing. 1:1:2 (49% HF: 69.5% HNO3: 85% H3PO4) Acid temperature below 15 C “dunking” or acid circulation. Known. and. unknown. Damage layer removed, surface degreased and shiny after BCP. Limit cavity performance possibly due to field enhancement at sharp features Hydrofluoric Acid and Nitric Acid Mixtures | Nitric and HF With this solution, the HF tends to be more stable, the hydrogen gas is eliminated, and the etch rate increases. We offer different chemical concentrations of N+HF blends based on the required specification or on the desired effects of on the etch rate and surface finishes. Achieving the Desired Thickness for Etching Titanium BUFFERED OXIDE ETCH BUFFERED OXIDE ETCH 1. Product Identification Synonyms: Aqueous NH4-HF Etchant Solutions CAS %o.: Not applicable to mixtures. Molecular Weight: Not applicable to mixtures. Hydrogen Fluoride 7664-39-3 0.5 - 10% Yes Water 7732-18-5 40 - 70% No BOE Wet Etch of Silicon Dioxide + HF The actual etch rate of the oxide is dependent on a range of factors. For example, deposited SiO 2 is etched at a much higher rate than thermally grown oxide. 4 The concentration of HF and NH F in the solution coupled with temperature also effects the etch rate as seen in the following figures. Etch rate …

BUFFERED OXIDE ETCH

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 … A common buffered oxide etch solution comprises a 6:1 volume ratio of 40% NH 4 F in water to 49% HF in water. This solution will etch thermally grown oxide at approximately 2 nanometres per second at 25 degrees Celsius. Temperature can be increased to raise the etching rate.

ETCH RATE The etch rate of undoped thermal oxide by aqueous NH 4 F/HF solutions, with or with-out surfactant additives, depends on three primary factors: NH 4 F range, etching tem-perature, and specific HF content. Standard BOE etchants (40% NH 4 F/ 49% HF blends) contain over 30% NH 4 F, a range where HF content has primary influence on etch

Buffered HF has several advantages over unbuffered HF as an etchant, namely improved uniformity, better compatibility with photoresist and greatly increased etch rate. The 7:1 refers to the ratio of Ammonium Fluoride to Hydrofluoric acid. Etch rates of oxide films will vary due to differences in film densities. Deposited oxides are Microelectromechanical Systems (MEMs) Unit Processes for HF with or without the addition of ammonium flouride (NH 4F). The addition of ammonium flouride creates a buffered HF solution (BHF) also called buffered oxide etch (BOE). The addition of NH 4F to HF controls the pH value and replenishes the depletion of the fluoride ions, thus maintaining stable etch rate. SiO 2 + 6HF = H 2SiF 6 + 2H 2O