Hot News
The movement of gas particles in the coating process

Core tips: in the process of vacuum coating equipment coating, all the time can not be separated from the movement of particles, where the particles include electrons, atoms, molecules, ions, when they collide with each other.

In the coating process of vacuum coating equipment, particle motion is indispensable all the time. Particles here include electrons, atoms, molecules and ions. When they collide, they will have a variety of interactions. For gas particles, ionization and excitation often occur.

For example, in the sputtering vacuum coating machine, argon ions are produced by the collision of electrons and argon molecules. Before the electron collides with argon, it is in the state of high-speed movement. The argon molecule is a single atomic structure. The electron collides with the atom inelastically, and the kinetic energy of the electron is transferred to the atom. According to the law of conservation of energy, the kinetic energy of the electron is reduced, and the internal energy of the atom is increased. The electron on the atom gains energy and then transitions from the low-energy level to the high-energy level to excite the atom from the ground state to the excited state State, but this time is very short, can be said to be a moment thing, about 10-7 can be maintained. If the energy of the electron on the atom is large enough, it can get rid of the fetter of the nucleus and become a free electron. The atom is composed of electrons, neutrons and protons. The electrons are negatively charged, neutrons are not charged, protons are positively charged. The number of electron charges in the atom is equal to the number of proton charges, so the atom is not charged. But when the electron gets rid of the fetter, it becomes a free electron leaving the atom, The number of proton charge of atom is larger than that of electron charge, which makes the atom become ion with positive charge. The target is connected with the cathode of power supply. Under the action of electric field, the argon ion with positive charge accelerates to the cathode. When the argon ion collides with the atoms on the target, the kinetic energy of some ions is transferred to the atoms, and the atoms are sputtered out. In addition, after some ions collide with the atoms, the electrons on the atoms are transferred to the argon ion, so that the argon ion can obtain the negative electrons with equal charges, which are originally argon atoms. The metal atoms lose electrons and become metal positive ions, and obtain part of the kinetic energy.

This is the process of argon particle movement in sputtering coating, from atom to ion, then from ion to atom, repeatedly.