Research On Ion Movement Behavior And Uniformity Control In Large Area Plasma Source

Plasma immersion ion implantation and deposition (PIII&D) can obtain a highadhesion strength, homogeneous and dense surface modification layer oncomponents with sophisticated shapes, which can improve the wear, corrosion andfatigue resistence of the substrate. However, for comercial applications of thePIII&D, inner surface ion implantation and large area uniform plasma formation arethe key problems to be solved. This research proposed a method for large areagaseous and metallic plasma sources based on respectivley pulsed glow dischargeand overlap of cathodic arc plasma source. Large area metal plasma sources basedon direct-overlay and bend-overlay have been built, and through a particle-in-cellsimulation, the influences of the processing parameters on motion behaviors of theparticles in metal plasma were obtained, and the feasibility of the large area metalplasma source was proved. According to the experimental results of the uniformityof large area metal plasma based on direct-overlay and bend-overlay, a large areaPIII&D equipment was developed.In order to obatain a large area gaseous ion implantation and deposition in theinner surface of a tube, a method based on pulsed glow discharge was proposed, andDiamond-like carbon (DLC) films were obtained in the tube. In the low voltagepulsed glow discharge mode, the wear resistance of the the DLC film raised with theincrease of pulse frequency and bias voltage. In the high voltage pulsed glowdischarge mode, the adhesion strength and wear resistance of DLC film wereincreased by the high energy carbon ion implantation, and they are better than thesingle DLC film obatined with a low bias voltage.In order to verify the feasibility of large area metal plasma based ondirect-overlay and bend-overlay, particle-in-cell simulation was used to analyze theinfluence of the external magnetic field on movement behavior of the chargedparticles in the metal plasma. Simulation results show that it is easy for the externalmagnetic field to control the metal plasma transport process. With the increase ofthe magnetic field, the constraint of the metal plasma was enhanced, but a completeconstraint of the metal plasma requires a large magnetic field. However, theuniformity of the metal plasma is inversely proportional to the magnetic field. Theelectron in the metal plasma will change its original direction and move along thelines of the magnetic field. Due to different movements of the ions and electrons inthe metal plasma, charge separation will take place and the electrostatic forcecaused by this effect will change the ion trajectory and form a large area metalplasma. Particle-in-cell simulation results of large area metal plasma source based ondirect-overlap show that the beam current and the distance between dirrerentcathodic arc sources are the key parameters for obtaining a large area homogeneousmetal plasma. When the beam current and the distance were respectilvely20A and400mm, a large area uniform metal plasma can be obatined. Howerver, the ioncurrent density results show that metal plasma couldnot pass through the shutteruntil the blade current was above700A. However, the efficiency of this filter wasvery small.Particle-in-cell simulation results of large area metal plasma souce based onbend-overlay reveal that a small perpendicular external magnetic field can realizethe constraint of the metal plasma. The uniformity of the metal plasma in Xdirection was better than that in Y direction, and the distance of arc sources has ansignificant influence on the plasma uniformity. In addition, the spacing between thearc source and the magnetic coil should be less than100mm. The influence of thecurrent of the the magnetic coil on unifomity is obvious, and a small current canobtain a uniform metal plasma (more than80%).According to the experimental and simulational resutls, a large area PIII&Dequipment, with a metal plasma output diameter greater than500mm and adeposition thickness nonuniformity less than15%, was built. The pulsedd cathodicvacuum arc source in this facility can can work for a long time without broken thevacuum. It can meet the requirements of PIII&D process for compoents with largesize or batching processing of small parts.