Name: Suzhou cycas Microelectronics Co., Ltd.
Address: 1st floor,B06 building,No.2,Fuxing Road,Zhangjiagang Economic Development Zone,Jiangsu Province 215600PRC
1、 What does PVD mean? PVD (physical vapor deposition) is a kind of technology which uses physical methods to vaporize the surface of material source into atoms, molecules or ions under vacuum, and to deposit films with special functions on the surface of substrate. PVD is mainly divided into three categories: evaporation, sputtering and ion plating.
2 Under vacuum condition, the material is heated, evaporated or sublimed, and the atoms or molecules of the material are directly deposited on the substrate.
Several common vacuum evaporation technologies are introduced as follows:
1. Resistance evaporation adopts evaporation coating technology of resistance heating evaporation source, which is generally used to evaporate low melting point materials, such as aluminum, gold, silver, zinc sulfide, magnesium fluoride, chromium trioxide, etc.; heating resistance generally adopts tungsten, molybdenum, tantalum, etc.
simple structure, low cost,
disadvantages: the material is easy to react with the crucible, which affects the purity of the film. The dielectric film with high melting point cannot be evaporated; the evaporation rate is low.
2. The technology of electron beam evaporation, which uses high-speed electron beam heating to vaporize the material and condense the film on the substrate surface.The energy density of the electron beam heat source can reach 104-109w / cm2, which can reach over 3000 ℃, and can evaporate high melting point metals or dielectric materials such as tungsten, molybdenum, germanium, SiO2, Al2O3, etc. There are two kinds of electron beam heating sources, i.e. the straight gun type electron gun and the E-type electron gun (or the loop type). The electron beam is emitted from the source. The magnetic field coil is used to focus and deflect the electron beam and bombard and heat the film material.
Advantages: it can evaporate any material. The film has high purity and directly acts on the surface of the material. The thermal efficiency is high. The structure of the electron gun is complex, the cost is high. The compound is easy to decompose when it is deposited,
the chemical ratio is out of balance.
3. Laser evaporation uses high-energy laser beam to evaporate the material to form the film, which is generally called laser evaporation. The advantages of the film are high purity, high evaporation rate. It is especially suitable for the alloy or compound with complex evaporation components. The stoichiometric ratio of the film is consistent with the target material. It is easy to produce tiny particles splashing, which affects the film quality.
4. Induction heating evaporation is a technology that uses high frequency electromagnetic field induction heating to make the material evaporate and condense on the substrate surface to form a film.
large evaporation rate, about 10 times larger than resistance evaporation source The temperature of the evaporation source is stable, and it is not easy to produce splashing phenomenon.
The temperature of the crucible is low, and the crucible material has less pollution to the film guide. The evaporation device must be shielded with high cost and complex equipment. Third, the sputtering coating in vacuum, the high-energy particles bombard the surface of the material, so that the atoms can obtain enough energy to escape from the surface, and reach the substrate condensation film technology. Compared with the real hair coating, the sputtering coating is suitable for all (including high melting point) materials. It has the advantages of strong adhesion, controllable composition, easy to scale production and so on. 1. The two pole sputtering adds a DC high voltage between the target and the substrate, the gas (generally ar2) between the plates is ionized, and the high-speed charged ion bombards the target surface. In order to maintain the self-sustaining discharge, the discharge pressure is generally as high as 10 Pa at a normal sputtering distance of several centimeters between the two plates, which is not good for sputtering efficiency and film quality. Therefore, DC sputtering mostly uses non self sustaining discharge, that is, four pole sputtering with hot electron emitter and auxiliary anode, which can make sputtering at low pressure of 10-1-10-2 PA. Advantages: simple structure and disadvantages: only the metal material with good conductivity can be sputtered with low sputtering efficiency. 2. RF power supply is used instead of DC power supply for RF sputtering. When high frequency voltage is applied between target and substrate, the target electrode will produce self bias effect (i.e. the target electrode will automatically be in negative potential state), so that the sputtering of insulation target can be maintained. The commonly used frequency is about 13.56 MHz. Advantages:
all materials can be sputtered, including conductors and insulators; high sputtering efficiency; mass production
Disadvantages There are some radiation problems in RF power supply.
3. The working principle of magnetron sputtering is that electrons collide with argon atoms in the process of flying to the substrate under the action of electric field E, resulting in AR positive ions and new electrons; new electrons fly to the substrate, and Ar ions accelerate to fly to the cathode target under the action of electric field, and bombard the target surface with high energy, resulting in sputtering of the target. In sputtered particles, the neutral target atoms or molecules are deposited on the substrate to form a thin film, and the secondary electrons generated will be affected by the electric field and magnetic field, resulting in the direction drift of E (electric field) × B (magnetic field), which is called e × B drift for short, and its motion track is similar to a cycloid. If the magnetic field is circular, the electrons move in the form of approximate cycloid on the target surface. Their motion path is not only very long, but also bound in the plasma region near the target surface. In this region, a lot of AR is ionized to bombard the target, thus achieving a high deposition rate. With the increase of the number of collisions, the energy of the secondary electrons is exhausted and gradually away from the target surface, and finally deposited on the substrate under the action of the electric field E. Because the energy of the electron is very low and the energy transferred to the substrate is very small, the substrate temperature rise is low. Magnetron sputtering is a collision process between the incident particles and the target. The incident particle experiences a complex scattering process in the target, collides with the target atom, and transfers part of the momentum to the target atom, which collides with other target atoms, forming a cascade process. In this kind of cascade process, some target atoms near the surface obtain enough momentum to move outwards, leaving the target to be sputtered out.