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Sapphire is an ultra–high purity Single Crystal Material that is grown after melting Al203(Alumina) by heating it above 2000℃. It is the second hardest material on Earth after Diamond scaling 9 on Mohs Hardness. It has excellent insulating properties and optical transmittance with abrasion and corrosion resistance of about 10 times higher than the quartz.

Recently the rapid increase in the LED demand threw light on it again for its use as substrate material and its usage is drawing attention due to its solution to the Etching problem caused by HF and Plasma.

Keeping such characteristics of Sapphire such as Chemical and Heat resistance and high hardness, Coma Technology is replacing parts made of Ceramic and Quartz used in Semiconductor process with Sapphire. We are focusing on maximizing the yield and minimizing the generation of pollutants and particles. In addition due to the high durability of Sapphire material, the life span of the parts is increased and thereby contributing innovatively in reducing cost and increased product efficiency.

Crystal StructureHexagonal, a=4.765Å c=13.001Å
Crystal Purity>99.99%
Density3.98g/cm3 Solid
Hardness9(moh’s scale)
Knoop Hardness1600 to 2200
Young’s Modulus380 GPa 30’ from c-axis /
340 GPa 60’ from c-axis
Tensile Strength300 to 400 MPa,
orientation and polish dependent
Modulus of Rupture500 to 900 MPa,
orientation and polish dependent
Compressive Strength2000MPa
Thermal Properties
Melting point2053℃
Specific Heat0.10 cal/g at 20℃
Heat Capacity0.77 J/g℃ at 20℃ / 1.25 J/g℃ at 20℃
Thermal Conductivity46.06 at 0℃, 25.12 at 100℃,
12.56 at 400℃(W/(m.K))
Coefficient (25℃)4.5 X 10-6/K perpendicular to c-axis
5.3 X 10-6/K parallel to c-axis
Dielectric Constant~9.4 at 300K at a-axis ~11.58 at 3000K at c-axis
Loss Tangent at 10 GHze< 2X 10-5 at a-axis,
< 5X 10-5 at c-axis
  • Hardness

    -Hardest matter after Diamond present on Earth.

  • Heat Resistance

    Withstand 2,040℃ with no change in properties.

  • Corrosion Resistance

    Chamber Etching in extreme NF3 and CF4 gas environment.

  • Chemical Resistance

    No radical reaction/minimum contamination.

  • Insulation

    Very stable Insulator/minimize arcing.

Plasma resistance of Sapphire
(Plasma resistance is more than 3 times better than quartz)

Corrosion measurement after 12 hours immersion in 49% HF concentration
→ Sapphire corrosion rate 0.5% vs Quartz corrosion rate 16.2%

* Test Condition: Plasma Nozzle 60/120 minutes.
* Test Result : Etching rate Of SiC 5 times more than Sapphire material.


Sapphire Window, with its strong chemical resistance, high strength and high penetrability, is used for not only the semiconductor process chambers but also many other high-degree vacuum applications.
Recently in the difficult high-degree vacuum area, sapphire windows are rapidly replacing quartz windows.
Especially in the strong etching process using NF3 and CF4 gas the quartz window surface gets blurred and rapidly etched. This etched quartz window can be undercut or can damage sealing to reduce the lifetime.
Thus the lifetime of quartz window could be substantially limited but in most cases sapphire window can be used for a longer period.
Coma Technology Co., Ltd. directly produces nozzles used in the Deposition Chamber and Etching (CVD & Etching) process during the semiconductor manufacturing process. In addition to the production of existing AI203, AIN, quartz materials ,we are also producing nozzles made od Sapphire, It maximizes the yield by minimizing the generation of pollutants and particles. Also, due to the high durability of the sapphire material, the life of the parts is increased, which increases the replacement cycle, contributing to cost reduction. Sapphire minimizes particle generation in NF3 and CF4 Environment and hence significantly increases the life span of the product.
COMA Technology Co., Ltd. is manufacturing various products using Sapphire along with Sapphire Windows and Nozzles.Cover glass for smart phone (smart watch), lift pin, precision plunger, general structure, laboratory equipment, optical lens, prism, etc can be made of sapphire.
With diversified manufacturing knowhow and technology, top quality products are being produced, by responding promptly to the customers‘ needs and development of samples to regular production.