Research On Fluid Transmission And Control System For Immersion Lithography

The fast development of information technology promotes the semiconductor manufacturing technology, and the resolution of lithography has been decreasing according to the prediction of Moore's Law. Through the use of phase-shift masks (PSM), optical proximity correction (OPC), and other resolution enhancement techniques (RETs), optical lithography have been able to fabricate features smaller than the wavelength of light used to create them. However, it has an absolute maximum resolution of about 50 nm, and not capable of meeting 45 nm and 32 nm node in the future. Immersion lithography has been proposed as a method for extending optical lithography resolution to 45 nm and below. The premise behind immersion lithography is to improve resolution by increasing the index of refraction in the space between the final projection lens and the wafer by inserting a high index liquid in place of the low index air that currently fills the gap. The fluid transmission mechanism is a key infrastructure of immersion lithography equipment, which is used to execute the liquid dispensation and recovery, and ensures no leakage or bubbles. This thesis is mainly devoted to the design, simulation and experiment research of the fluid transmission mechanism.The first chapter introduced the development of VLSI and the principle of optical lithography. By comparing to the summarized competing next-generation lithography (NGL) technologies, the advantages of immersion lithography were presented. Then the research work and current progress on immersion lithography were detailedly reviewed. At last, the significance and content of the thesis were presented.The second chapter analyzed the the physics of fluid filling process. Then the simulation method of computational fluid dynamatics (CFD) using volume of fluid (VOF) model was presented. Two dimentional simulations were performed to investigate the effects of contact angle, scan direction, dispense velocity and dispense angle. At last, three dimentional simulations were carried out to analyze the shape of the meniscus at various gap heights.The third chapter set up a two dimentional wafer stage, using Programmable Multi-Axis Controller (PMAC) to control the servo motors. Then PEWIN32 was performed to execute the motion programme and optimize the control parameters. At last the setup of gas-liquid control loop was introduced.The fourth chapter firstly summarized various liquid seal methods, and...