Lithographic processes

Fig. 3. Lithographic process using positive- and negative-resist systems. The element (a) is (b), exposed to uv radiation (c), developed and (d), the metal is...

Figure 8. A schematic for a typical single layer (left) and a multilayer lithographic process.

You are to optimize the thickness of resist used in a production lithographic process. There are a number of competing effects in lithography. 

The process control of the post-exposure bake that is required for chemically amplified resist systems deserves special attention. Several considerations are apparent from the previous fundamental discussion. In addition for the need to understand the chemical reactions and kinetics of each step, it is important to account for the diffusion of the acid. Not only is the reaction rate of the acid-induced deprotection controlled by temperature but so is the diffusion distance and rate of diffusion of acid. An understanding of the chemistry and chemical kinetics leads one to predict that several process parameters associated with the PEB will need to be optimized if these materials are to be used in a submicron lithographic process. Specific important process parameters include ... 

The three-dimensional circuit elements are fabricated by a series of processes collectively known as lithography . The pattern is first generated in a polymeric film on a device wafer and this pattern is then transferred via etching, into the underlying thin film. The purpose of this book is to review the theory, materials, and processes that are used in the lithographic process. This book is intended to be a tutorial and not a comprehensive review. Each chapter contains many references to which the reader can refer for more detail on any specific aspect of microlithography. 

As the complexity of integrated circuits increases and the dimensions of each circuit element decrease, greater demands are placed on the lithographic process, particularly with respect to resolution. Indeed, we are rapidly approaching the limits of photolithographic techniques for reproduc-... 

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