Numerical Study Of Sheath Characteristics With Dielectric Material In Plasma Immersion Ion Implantation

Plasma immersion ion implantation has been widely applied to the surface modificationfield of metal,semiconductor and dielectric because of the advantages of low cost,simple operating system and efficient dealing with samples.But the application of PIII to the surface modification has been faced with a big challenge because of the charging effects on the surface.When we apply a high negative pulse to the target,the surface potential is lower than the applied voltage due to the dielectric material's capacitance.In this way,the energy of implanted ions can not reach an desirable value.On the other hand,the serious charging effects which can raise electric arc may lead damage to both the materials and plasma chamber itself.The numerical simulation method is useful for studying and analyzing the problems,and the conclusions can be a theoretical guidance for optimizing technological parameters.In this article we study the sheath characteristics with dielectric target in plasma immersion ion implantation by one-dimensional fluid model which is realized by C code.The thesis is organized as follows:In chapter one,we introduce the characteristics,applications,research methods and the current research state of the PIII technology in detail.In chapter two,we mainly introduce the the theoretical model and physics theory of the numerical methods which include the sheath dynamics theory,collision or non-collision cool fluid models,the role of SEE and some detail thoughts and methods of solving the problems.In chapter three,the sheath expansion near the target is investigated by using a one-dimensional fluid model.We can get the characteristics of the sheath evolution and then we argue the influence of some parameters on the results of surface modification.The results indicate that the evolution of the sheath thickness,the surface potential,the electric field and so on is non-uniform.In the actual progressing of PIII,high plasma density,long pulse's rise time,short fall time and thin dielectric film can release the charging effects.