Simulation And Experimental Study Of Electrostatic Force In Electrostatic Chuck Used In IC Equipment

Electrostatic chuck(ESC)has been widely used in semiconductor processing such as etching,PVD and CVD.It is a piece of equipment which can adsorb wafer on its surface by electrostatic adsorption principle and can control the wafer's temperature through the back blowing gas.Electrostatic chuck has many advantages compared with mechanical chuck and vacuum chuck,it is not only avoids irreparable damage to the wafer due to mechanical reasons such as pressure and collision,but also can reduces particle contamination and increases the effective processing area of the wafer in the use of the traditional mechanical chuck.At the same time,it overcomes the defects of the vacuum chuck can not be applied in low pressure environment.Clamping force is one of the most important technical indicators of ESC,the size of the electrostatic force and its uniformity directly influence the quality and efficiency of wafer processing.This dissertation studies the electrostatic adsorption mechanism and establishes the electrostatic force model of ESC used in IC equipment.Parameters which affecting the electrostatic force of ESC are analyzed and optimized by mean of numerical simulation and experiment.The research work has been done in this dissertation includes the following aspects:1.IC fabrication process and the working principle of ESC used in IC process chamber were analyzed,and the electrostatic adsorption mechanism of ESC was studied.All this work provides a theoretical basis for the modeling,simulation,optimizing design and experimental measurements of ESC.2.The method of modeling and simulation of electrostatic force by COMSOL software is proposed,and the accurateness is validated by comparing the results with those from reference.Then,the simulation of ESC in real manufacturing process is finished using the above method.The curves between clamping force and main parameters such as DC voltage,electrode thickness,electrode radius,dielectric thickness and helium gap are obtained.Moreover,the effects of these factors on clamping force are investigated by means of orthogonal experiments.The results show that the factors can be ranked in order of voltage,electrode radius,helium gap and dielectric thickness according to the importance.3.The measurement scheme of electrostatic force was determined,and a bipolar electrostatic chuck and electrostatic force measuring device were designed.The above device can be used for experimental verification of electrostatic adsorption force.4.The ESC and its electrostatic force measuring device were used to experimental verification of electrostatic adsorption force.The accuracy of the simulation method was further validated by comparing the experimental results with the simulation results.The research can offer references for the design of ESC,and it has significance to reduce experimental cost and improve the reliability of the equipment.