Forays through the lithography of microelectronics (Matthias Schirmer)

Due to the fast-paced development of photolithography since the 1990s, only a short summary of the different techniques and applications can be given here. For in-depth information on the multitude of facts, technologies and procedures presented in each chapter, the added references should be consulted.

Polymers (film formers)

Polymethyl methacrylates (PMMAs) are widely used e.g. in electron beam lithography. PMMAs are produced by polymerisation of methacrylic acid esters in the presence of radical starters

Principle and functioning

Positive resist The addition of photoactive compounds (PACs, naphthoquinone diazide (NQD)) to alkali-soluble novolacs reduces the alkali-solubility of resists films.

Other resist components

Solvents are the main component of all resists, with solvent contents ranging from 50% (thick resists) to up to 99% (spray resists).

Composition of photoresists

Photoresists are particularly employed in microelectronics and in microsystems technology to generate µm- and sub-µm structures.

Photosensitive components

The p hoto sensitive components of our positive photoresists belong to the group of naphtho qu inone d iazides (NQD).

Cross linker

The patterning of negative resists is based on the stabilization of exposed areas in the presence of cross-linking agents. Radical starters like e.g. azo-bis(isobutyronitrile) (AIBN)