Hexafluroacetylacetonate (β-diketone) is a clear liquid with pungent odor. It is a stable liquid and is used in the state-of-the art “thermal atomic layer etching” of various materials such as metals, metal oxides, metal nitrides. A β-diketone is commonly used as the organic vapor and is exposed onto oxidized metal surfaces because of its high reactivity and affinity to metals. Among various types of β-diketones, acetylacetone (ACAC) and hexafluoroacetylacetone (hfacH) are the most widely used molecules because of high volatility and reactivity and because of the formation of stable metal diketonates.
In ALE it has been reported that Co, Fe, Ni can be etched by hfacH in supercritical CO2. Etch is accomplished by chelation of the metal ion. Chelation is the formation of chemical bonds between a single central metal atom and organic molecules. Chelating reactants such as HFAC and HACAC are not reactive enough to bond to most metal surfaces easily. Metal are fully oxidized for the reaction to proceed generating a volatile metal complex and water. This property can be used to design thermal isotropic ALE processes. HfacH as the organic vapor is used as an etchant for Co and Cu thin films.
In addition to the attractive physical properties and chemical reactivity of hfacH, the presence of fluorine in the ligand formed on a surface can be used as a spectroscopic probe of surface chemical reactions to help us identify the mechanism of the etching process.
- It’s primary use is as a substitute for CFC-12 products in refrigeration
- As a substitute for SF6 in magnesium production
- Paired with SF6 for laser machining of silicon
- Highly purified form is used as a propellant in some medical sprays and inhalers
|Chloride||< 3 ppm|
|High Boiling Residue||< 0.01 ppmv|
|Other Refrigerants||< 0.5 ppm|
|Water||< 10 ppm|
|Acidity (HCL)||< 1 ppm|
|Halogenated Unsaturated Volatile Impurities||< 40 ppm|
|Chemical & Physical Properties|
|Molecular Weight||102.04 g/mole|
|Specific Volume||3.7078 cu. ft/lb|
|Pressure @ 70°F||81.3 psig|
|Valve Outlet||CGA 660; 1/4 flare (30 lbs)|
|DOT Name||1,1,1,2-Tetrafluoroethane or Refrigerant Gas r134A|
|DOT No.||UN 3159|
|DOT Label||Green, Non-Flammable Gas|
|Cylinder Size||Fill Volume|