Silicon Carbide is the only chemical compound of carbon and silicon. It was originally produced by a high temperature electro-chemical reaction of sand and carbon. Silicon carbide is an excellent abrasive and has been produced and made into grinding wheels and other abrasive products for over one hundred years. Today the material has been developed into a high quality technical grade ceramic with very good mechanical properties.It is used in abrasives,refractories,ceramics,and numerous high-performance applications. Silicon carbide whisker can also be made an electrical conductor and has applications in resistance heating, flame igniters and electronic components. Structural and wear applications are constantly developing.
Chemical heater and etch process are important terms that must be learned by people and businesses in the semiconductor industry. In this article, I am sharing about the types of chemical heaters used in the wet process system as well as the silicon nitride etch process.
Types of chemical heater
Quartz – Gas Heater — a system that is designed to meet the growing demand for heated high purity gasses. It has the capacity of heating a wide range of gases including: Ammonia (NH3), Helium (He), Argon (Ar), Hydrogen (H2), Arsine (AsH3),Hydrogen Bromide (HBr), Boron Trichloride (BCl3),Hydrogen Chloride (HCl), Carbon Dioxide (CO2), Nitrogen (N2),Carbon Monoxide (CO), Chlorine (Cl2), Nitrous Oxide (N2O), Oxygen (O2),Disilane (Si2H6), Sulfur Dioxide (SO2),Methylsilane (SiH3CH3)
Quartz – Fluid Heater — used in the semiconductor industry and its traditional application includes recirculation loop, either as the sole head source or a combination of a heated quartz tank.
SiC – HF & KOH Heater — designed for heating HF (hydrofluoric acide), KOH (potassium hydroxide), and other high PH chemistries. It uses high purity Silicon Carbide (SiC) as a heat transfer material because it has excellent heat transfer properties and eliminates the risk of contamination due to Teflon breakdown.
Interesting Facts about the Silicon Nitride Etch process
To be able to achieve the greatest etch rates and best selectivity, the phosphoric acid should have the highest ratio of water at a given temperature. For as long as the boil point is maintained, the etch rate of both Si3N4 and SiO2 can be precisely controlled.
Maintaining a boiling solution is one of the challenges in the etch process. When phosphoric acid is heated, the water solution begins boiling off. When temperature is not maintained, it affects the etching process as the acid concentration increase. Wet etch companies use a standard temperature controller to maintain temperature, but the water concentration will decrease and will change the etch rates. As a solution, wet etch process engineers use water addition system.
A technology called closed “reflux” system is used and it is created above the bath using condensing collar and a lid – this is to minimize water addition.
The chemical fumes and high temperatures that Nitride Etch tanks are subjected to are known to decrease bath life substantially by attacking the sealant that prevents liquid and fumes from entering the heater area. This problem has been addressed through the use of aquaseal.
Quartz Nitride Reflux system is engineered to address the unique needs of the silicon nitride etch process. It gives the following benefits to customers: process uniformity, lot-to-lot repeatability, prevents stratification.
Related reading:silicon dioxide nanoparticles multi walled carbon nanotubes