An etching method includes providing a first insulating material layer on a substrate assembly surface and a second insulating material layer on the first insulating material layer. The first insulating material layer has an etch rate that is greater than the etch rate of the second insulating material layer when exposed to an etch composition. Portions of the first insulating material layer and the second insulating material layer are removed using at least the etch composition. Various types of structures (e.g., contacts, capacitors) are formed with use of the method.