Nano Lithography

Introduction

Implications of Lithography ¹

The microelectronic industry is remarkable for its exponential growth over recent decades. At the heart of this success is “Moore's law”, a simple technical and economic assessment according to which it is always possible to integrate more and more functions into a circuit at reduced costs. This observation, made in the mid-1960s, has been transformed into a passionate obligation to fulfill its own prophecy, and has focused the efforts of an entire generation of microelectronics researchers and engineers.

Anyone talking about greater integration density is thinking about increasing our capacity to precisely define and place increasingly smaller components, building and using materials to support them. Lithography is succeeding in this arena, using increasingly sophisticated techniques, and is essential to the progress of the semiconductor industry because it allows a reduction in the size of patterns as well as an increase in the integration density of the integrated circuits at an economically acceptable cost.

The issue of dimension is considered so central to all microelectronic improvements that the industry calls each generation of the process, or each technological node, after a dimension which characterizes the technology; often, the half-pitch of the most dense interconnection is used. For a 45 nm technology for example, the minimum period of the interconnection pattern is 90 nm. Doubling the integration density of a circuit means ...