Development of no-rinse screen printable etch paste for contact via in dielectric films

Screen printable etch paste was developed for low cost patterning of dielectric films. This technique offers a simple print and bake approach to pattern without the need for a rinse step. Residue analysis of the etched area showed no sign of any organic residue left behind by the etch process. High carrier lifetime indicates no significant contamination or silicon surface damage. The etched via diameter of 150 µm was demonstrated in thermal oxide while smaller via size of 100 µm was achieved in silicon nitride (SiN x ) or a combination of silicon oxide and nitride. Contact resistance measurement through the etched vias using TLM method showed values less than 3mΩ.cm 2 . The etch paste and process technique can be easily used in PERC cell as well as advanced architecture Interdigitated Back Contact (IBC) cell for low cost patterning.