How thick? How deposit - PVD, CVD, sputtered, IBAD, ...? What temperature?
I have not worked with Nb, but the above questions will strongly influece the answer. Very thin layers will usually require nothing special. Thicker layers will depend on conditions. Do describe what you need, and what resources you have to control the deposition conditions. Then seek to minimize residual stress (compare CTEs of film and substrate).
I can grow even 40 nm thick Nb on a SiO2 substrate using our AJA sputtering system. If you wish you can also try Ti, Cr, or MoGe (less than 5-nm thick) as an adhesive layer.