1.3 Outline of the Thesis

This thesis is devoted to photolithography simulation. A three-dimensional simulation method is presented that treats the problem in the physically most rigorous way by solving repeatedly the Maxwell equations and is nevertheless suited for a workstation-based simulation. In three dimensions previous approaches with the same degree of rigorousness have been constrained to massively parallel supercomputers [5,6,7]. Only one other method has been proposed for a workstation-based simulation [8,9,10], but it still has some limitations in the physical process modeling capability.

The thesis is organized as follows: In Chapter 2 a detailed description of the photolithography process is presented. Alternative non-optical lithography techniques are also briefly discussed. Chapter 3 provides an introduction into photolithography simulation. Simulation tasks as well as the fundamentals of any photolithography simulator are described. The subsequent four chapters are devoted to various aspects of photolithography simulation. Chapter 4 deals with the aerial image formation and simulation, Chapter 5 outlines the photoresist exposure/bleaching reaction. In Chapter 6 a novel three-dimensional method for rigorous nonplanar photolithography exposure simulation is presented. Chapter 7 focuses on the photoresist development process. Mathematical details of the applied simulation methods can be found in the appendices. In Chapter 8 examples for aerial image simulation as well as for photoresist exposure/bleaching and development are shown. The thesis concludes with a brief discussion of the achieved results and gives some outlook for future work.