A method of fabricating a microwell in an array structure is disclosed herein. The array structure can include a plurality of field effect transistors (FETs), where each FET has a gate structure. The method can include disposing a titanium nitride (TiN) layer on at least one conductive layer coupled to the gate structure of at least one FET. A insulation layer can also be disposed on the array structure, where the insulation layer lies above the TiN layer. Further, an opening above the gate structure of the at least one FET can be etched to remove the insulation layer above the gate structure and to expose the TiN layer. A microwell with at least one sidewall formed from the insulation layer and with a bottom surface formed from the TiN layer is a result of the etching process.