Advances in semiconductor manufacturing technology have resulted in, among other things, reducing the cost of sophisticated electronic products to the extent that the integrated circuits fabricated in accordance with these semiconductor manufacturing technologies have become ubiquitous in the modern environment.
As is well-known, integrated circuits are typically manufactured in batches, and these batches usually contain a plurality of semiconductor wafers within and upon which integrated circuits are formed through a variety of semiconductor manufacturing steps, including, for example, depositing, masking, patterning, implanting, etching, planarizing and so on.
Completed wafers are tested to determine which die, or integrated circuits, on the wafer are capable of operating according to predetermined specifications. In this way, integrated circuits that cannot perform as desired are not packaged, or otherwise incorporated into finished products.
It is common to manufacture integrated circuits on roughly circular semiconductor substrates, or wafers. Further, it is common to form such integrated circuits so that conductive regions disposed on, or close to, the uppermost layers of the integrated circuits are available to act as terminals for connection to various electrical elements disposed in, or on, the lower layers of those integrated circuits. Such conductive regions are commonly referred to as pads. Pads are commonly used to provide electrical access to the integrated circuit both during testing and during the operation of the integrated circuit as it is incorporated into a final product. Typical pads are formed from aluminum. It is well-known that the surfaces of aluminum which are exposed to the atmosphere will oxidize. These oxidation layers interfere with the formation of low resistance electrical connection to the pads.
During the process of testing the performance of the integrated circuits, the pads are commonly contacted with probe needles, or other contact structures, of a probe card. It is through such temporary connections that a test apparatus may electrically interact with an integrated circuit.
Conventionally, the probe needles, or other contact structures, of the probe card are brought into physical contact with the pads and then moved laterally to “scrub” the pad. The scrubbing operation is intended to break through the oxide layer on the top surface of the pad, thereby providing reduced contact resistance. Unfortunately, scrubbing disturbs the pad structure and can contribute to yield loss due to failure of bond wires to properly attach to the disturbed pad structure.
What is needed are methods and apparatus for providing low contact resistance connections to pads of integrated circuits without disturbing or substantially redistributing the material from which the pads are formed.