An approach to measuring the mechanical properties of thin films with in—plane and thickness dimensions comparable to those of films in VLSI electronic devices and in multi—chip modules is being developed. The guiding principles are to utilize as much as possible the technology of microelectronic fabrication and to make the design downward—scalable in size so that eventually the very smallest films and structures can be tested. The necessary components have been designed; we are in the process of building and testing them.
The specimen and associated instrumention are fabricated by semiconductor techniques on a 50 mm—diameter silicon wafer. Piezoresistors arranged as strain—sensitive Wheatstone bridges are fabricated by diffusion. One bridge, located on a grip section, is the load cell. After opening contact windows and metallization, the thin—film specimen is deposited. Then the silicon wafer is patterned and etched, leaving the specimen hanging between two instrumented grip sections linked by flexible silicon springs. Relative displacement of the grip sections is imposed by either a micrometer or a micro—stepper motor and measured by a scanned laser beam and by additional strain—sensitive bridges.