Introduction to PECVD principle
Time：2020-10-09 13:16 Click：
PECVD literally means: plasma (P) enhanced (E) chemical vapor deposition (CVD). The reaction gas is converted into plasma under the action of the equipment radio frequency (RF) to carry out a chemical reaction to generate the required film material. The reaction temperature is relatively low. The film-forming density is worse than that of the furnace tube. But it is efficient and easy to maintain.
Generally speaking, when using PECVD technology to prepare thin film materials, the growth of the thin film mainly includes the following three basic processes:
First of all, in the non-equilibrium plasma, the primary reaction between electrons and the reactive gas causes the reactive gas to decompose to form a mixture of ions and reactive groups;
Second, various active groups diffuse and transport to the film growth surface and the tube wall, and at the same time secondary reactions between the reactants occur;
Finally, various primary and secondary reaction products that reach the growth surface are adsorbed and reacted with the surface, accompanied by the re-release of gas phase molecules.
Gas (such as SiH4, NH3, N2, etc.) is ionized into ions under the action of radio frequency power; after multiple collisions, a large number of active groups such as SiH3- and H- are produced; these active groups are adsorbed on the substrate or replace the surface of the substrate H atoms; the adsorbed atoms migrate on the surface of the substrate under the action of their own kinetic energy and the temperature of the substrate, and choose the lowest energy point to stabilize; at the same time, the atoms on the substrate continuously break away from the bondage of the surrounding atoms and enter the plasma to achieve dynamic equilibrium ; When the atomic deposition speed is greater than the escape speed, the thin film we need can be continuously deposited on the substrate surface.