Aluminum-backed wafer and chip

Claim 1

A packaged circuit chip comprising: a chip substrate having a front and back surface, said substrate front surface having a circuit with resistors formed thereon, said chip substrate back surface having deposited thereon an attachment layer of aluminum having a thickness of from about 5,000 to about 30,000 Å, said attachment layer of aluminum having an outer gold eutectic preform layer deposited thereon, a package having a chip-receiving surface thereon, said attachment layer of aluminum on the chip substrate back surface being in bonding contact with the chip-receiving surface of the package through the gold eutectic preform layer wherein the bonding contact between the chip-receiving surface and the attachment layer of aluminum is between about 90 to 100% such that the coefficient of expansion across the chip is essentially equalized such that the change in resistance of the resistors is less than about 0.003% when subjected to thermal cycling over the range of from -55° C. to 125° C. for 15 cycles and gold diffusion into the back surface of the chip is substantially prevented.