Wet-recess process optimization of a developer-soluble gap-fill material for planarization of trenches in trench-first dual damascene process

This paper describes a new approach to help overcome the challenges of fabricating leading-edge devices by using the trench first dual damascene process. Wet gap-fill materials are designed to reduce film thickness bias across a wafer while keeping wafers in the same track in which they were coated. As the first process step, the wafer is coated with a thick layer of wet gap-fill material to fill all trenches, thus guarding against resist pooling in the trenches. The substrate is then baked to partially cure the wet gap-fill material. Standard 0.26N tetramethylammonium hydroxide (TMAH) is then used to wet etch the wet gap-fill layer back to the substrate surface. For this study, substrates with different trench depths and widths were processed, cross-sectioned, and measured. The effect of trench dimensions and aspect ratio on the develop properties of WGF200-343 was investigated to see if it could be used as a wet trench-fill material. This work will help develop a process that will allow the use of trench-first DD processing in modern semiconductor manufacturing.