A capacitor forming method includes forming an electrically conductive support material over a substrate, forming an opening through at least the support material to the substrate, and, after forming the opening, forming a capacitor structure contacting the substrate and the support material in the opening. The support material contains at least 25 at % carbon. Another capacitor forming method includes forming a support material over a substrate, forming an opening through at least the support material to the substrate, and, after forming the opening, forming a capacitor structure contacting the substrate and the support material in the opening. The support material contains at least 20 at % carbon. The support material has a thickness and the opening has an aspect ratio 20:1 or greater within the thickness of the support material.