Metallization on a monolithic integrated circuit that allows the various active and passive components to be connected together by a highly conductive path. On simple circuits a single layer of metallization, often aluminium, can be used to interconnect the components to form the circuit. In more complex ICs, several layers of metal pathways may be needed: these layers are isolated from one another using insulating film deposited onto the IC, and connections between the metal layers are effected using via holes through the films, allowing the two metal films to come into contact.