A deep trench structure may be formed between electrodes of a capacitive device. The deep trench structure may be formed to a depth, a width, and/or an aspect ratio that increases the volume of the deep trench structure relative to a trench structure formed using a metal etch-stop layer. Thus, the deep trench structure is capable of being filled with a greater amount of dielectric material, which increases the capacitance value of the capacitive device. Moreover, the parasitic capacitance of the capacitive device may be decreased by omitting the metal etch-stop layer. Accordingly, the deep trench structure (and the omission of the metal etch-stop layer) may increase the sensitivity of the capacitive device, may increase the humidity-sensing performance of the capacitive device, and/or may increase the performance of devices and/or integrated circuits in which the capacitive device is included.