New semiconducter device structures with beam leads are described. Contacts, approximately 10 µ thick, are deposited on the semiconductor slice as an array of metal patterns and the excess semiconductor is then removed leaving the device or devices with semirigid beam leads cantilevered beyond the semiconductor. The leads provide structural support for chips; they may be welded to thin film circuits or headers. This obviates the need for wafer bonding and thermocompression wire bonding to the chip. The metal overlay may also be used as hermetic junction seals when required. This paper describes application of the new structure to moderate and high-speed transistors, and test devices. Thermal aging in 360°C steam indicates high resistance to ambient penetration. High-temperature bias aging indicates behavior similar to planar structures; i. e., surface-potential drift. Although these effects impose design constraints, they do not preclude the design and fabrication of many types of useful devices. Thermal rise in these structures is acceptable for low-to-medium-power applications. For higher power, wafer heat sinking may be used. Assemblies of units have been successfully centrifuged to 100,000 g's, and other mechanical tests have been performed.