6. Postbake / hardbake
Postbake / hardbake
For specific process steps, a postbake at approximately 110 °C leads to a higher etch stability during wet-chemical and plasma-chemical etching procedures. Higher temperatures are possible for stronger etch conditions, may however result in a rounding of resist profiles.
Structures in very thick films (> 5 μm) may even converge. UV curing (short wave deep UV exposure with simultaneous heating of the wafer to up to 180 °C, if required) leads to strong hardening of resist structures. While the melting of structures is now prevented in most cases, a subsequent removal is extremely difficult.