An integrated circuit structure is described which includes a base semiconductor structure and a programmable semiconductor structure which are fabricated separately and later joined to form the integrated circuit structure. The base semiconductor structure includes conventional semiconductor devices fabricated in accordance with a first set of design rules. The programmable semiconductor structure includes programmable elements fabricated in accordance with a second set of design rules which may be different than the first set of design rules. The programmable elements are used to control the configuration of the integrated circuit structure or to provide field programmable devices for use in the integrated circuit structure.