Bilayer photoresist process

摘要

The present invention relates to a bilayer photoresist process, wherein a first planarizing resist layer is applied to a base and a second or top photoresist layer is applied over the first. The top layer resist is sensitive to deep UV light, while the planarizing layer resist is sensitive to near UV or violet light. The top layer, by use of a dye or other means, is opaque to predetermined near UV or violet wavelengths by which the planarizing layer is illuminated. The top layer is patterned using deep UV light. A flood exposure of the predetermined near UV or violet wavelengths is then used to transfer the pattern of the top layer to the bottom planarizing resist layer. Improved resolution is achieved by the use of deep UV light for patterning the top layer. Less costly yet faster illumination of the planarizing layer is accomplished by using near UV or violet light. Additionally pattern degradation due to spurious reflections normally occurring from near UV exposure of the top layer is avoided. Also, the near UV sensitive resist planarizing layer results in a better dry etch mask than previous bilayer scheme planarizing layers. The pattern of the resolution layer can be transferred to the planarization layer by plasma etching.