What is the working principle of PECVD electric heating furnace?

The working principle of PECVD (Plasma Enhanced Chemical Vapor Deposition) electric heating furnace is mainly based on the chemical reaction and thin film deposition process of low-temperature plasma in low-pressure environment. Here is its detailed working principle:

1. Low temperature plasma generation
Definition of plasma: Plasma is a special gas state in which some gas molecules undergo ionization under high-energy excitation, forming a state composed of a mixture of electrons, cations, and neutral particles.
Generation method: In a PECVD electric heating furnace, reaction gases (such as SiH ₄, NH ∝, O ₂, etc.) are ionized using external energy sources such as radio frequency (RF) or microwave to form low-temperature plasma. The electron temperature in this plasma is much higher than the ion temperature, but macroscopically, the temperature is relatively low and in a non thermal equilibrium state.

2. Chemical reactions and thin film deposition
Gas diffusion: The reaction gas enters the furnace cavity from the inlet and gradually diffuses to the surface of the sample.
Chemical reaction: Under the action of an electric field excited by a radio frequency source, these gases are decomposed into electrons, ions, and highly active functional groups. These decomposition products immediately undergo chemical reactions, generating the initial components and by-products of the film.
Thin film deposition: The initial components generated are firmly adsorbed onto the surface of the sample through chemical bonds, forming crystal nuclei of a solid film. As the reaction continues, the crystal nuclei gradually expand into island like structures and eventually connect into continuous thin films. At the same time, by-products detach from the membrane surface and are discharged from the furnace cavity under the suction of the vacuum pump.

3. Heating and temperature control
Electric heating system: PECVD electric heating furnaces are usually equipped with an electric heating system to provide thermal energy to maintain the temperature required for the reaction.
Temperature control: Through high-precision temperature control systems (such as PID controlled temperature controllers), precise control of the temperature inside the furnace can be achieved. This is crucial for ensuring the quality and uniformity of thin film deposition.

4. Vacuum system
Maintain low pressure environment: The PECVD process needs to be carried out in a low pressure environment, so the furnace is usually equipped with a vacuum system to maintain the low pressure state inside the reaction chamber.
Gas exhaust: A vacuum pump is used to exhaust the by-products and unreacted gases generated during the reaction process from the furnace chamber.

5. Control system
Parameter monitoring and adjustment: PECVD electric heating furnaces are usually equipped with control systems for monitoring and adjusting process parameters such as gas flow rate, pressure, temperature, etc. This helps ensure the stability and reproducibility of the sedimentation process.