Abstract: A thermal detector comprises a rigid, frame-shaped support structure which supports a flexible, thin and substantially planar membrane of pyroelectric material. The major surfaces of the pyroelectric membrane carry electrodes, one of which is a common electrode and the other of which is defined as an array. One detector fabrication method involves preparing layered support structure and membrane components as separate assemblies and securing them together prior to performing finishing process steps. In an alternative method, a layered substrate is used as the foundation of a one-stage technique involving back-etching, and the frame-shaped support structure is created by processing the layered substrate subsequent to the attachment of the membrane thereto.