Thick Film Lithography

Thick-film lithography refers to the processes used to make thick films of photoresist, i.e., typically thick film is used to refer to films that are 5-100 pm (p) thick, and subsequently produce relief patterns in those Alms. The photoresist is a radiation-sensitive material that is applied to a substrate surface, exposed to radiation to create a physiochemical change in the exposed regions, and washed in a developer solution to produce the desired physical relief patterns. 

The photoresist film thickness range being used (i.e., generally divided into thin-film lithography and thick-film lithography)... 

Positive-Tone Thick-Film Lithography Using DNQ-Novolac Resists and UV Exposure... 

Negative-Tone Thick-Film Lithography Using UV and X-Ray Exposure of Cross-Linking Resists... 

This discussion will be limited to those lithography methods that utihze the application of external radiation (i. e. optical exposure, e-beam exposure, or x-ray exposure) and will not include imprint lithography techniques such as hot embossing. Thick film lithography is generally used to refer to lithographic processes that utilize photoresist film thicknesses greater than 5 x in thickness. 

X-ray based thick film lithography is stiU the best technique for producing very high aspect ratio structures with little or no variation in part dimensions along the axis normal to the substrate. This ability to produce such high aspect ratio structures with excellent dimensional toleranc-ing is a result of the very small x-ray wavelength combined with the ability to produce very well coUimated x-ray... 

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