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Hafnium Carbide HfC Notes

Hafnium Carbide (HfC) General Information

Hafnium oxide is an inorganic compound with a chemical formula of HfO2. It has a density of 9.68 g/cc, a melting point of 2,758°C, and a vapor pressure of 10-4 Torr at 2,500°C. It is off-white in color and generally considered to be one of the more stable hafnium compounds. Hafnium oxide has been utilized significantly in recent years as an addition to computer chips as a way to improve the speed and efficiency of processors. It is also evaporated under vacuum for optical coatings and semiconductor fabrication.

Hafnium Carbide HfC Specifications

Material TypeHafnium Carbide
Melting Point (°C)~3,890
Theoretical Density (g/cc)12.2
Type of BondIndium, Elastomer
Z Ratio**1.00
Temp. (°C) for Given Vap. Press. (Torr) 10-4:  ~2,600
Export Control (ECCN) 1C231

** The z-ratio is unknown. Therefore, we recommend using 1.00 or an experimentally determined value. Please click here for instructions on how to determine this value.


Empirical Determination of Z-Factor

Unfortunately, Z Factor and Shear Modulus are not readily available for many materials. In this case, the Z-Factor can also be determined empirically using the following method:

  • Deposit material until Crystal Life is near 50%, or near the end of life, whichever is sooner.
  • Place a new substrate adjacent to the used quartz sensor.
  • Set QCM Density to the calibrated value; Tooling to 100%
  • Zero thickness
  • Deposit approximately 1000 to 5000 A of material on the substrate.
  • Use a profilometer or interferometer to measure the actual substrate film thickness.
  • Adjust the Z Factor of the instrument until the correct thickness reading is shown.

Another alternative is to change crystals frequently and ignore the error. The graph below shows the % Error in Rate/Thickness from using the wrong Z Factor. For a crystal with 90% life, the error is negligible for even large errors in the programmed versus actual Z Factor.

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