Non-contact wafer testing

Wafer testing is a normal step in semiconductor device fabrication, used to detect defects in integrated circuits (IC) before they are assembled during the IC packaging step.

Traditional (contact) wafer testing

Probing ICs while they are still on the wafer normally requires that contact be made between the automatic test equipment (ATE) and IC. This contact is usually made with some form of mechanical probe. A set of mechanical probes will often be arranged together on a probe card, which is attached to the wafer prober. The wafer is lifted by the wafer prober until metal pads on one or more ICs on the wafer make physical contact with the probes. A certain amount of over-travel is required after the first probe makes contact with the wafer, for two reasons:

There are numerous types of mechanical probes available commercially: their shape can be in the form of a cantilever, spring, or membrane, and they can be bent into shape, stamped, or made by Microelectromechanical systems processing.

Using mechanical probes has certain drawbacks:

[1]

shrinking pad sizes makes design & manufacturing of smaller & more accurate probes a challenge

Non-contact (wireless) wafer testing

Alternatives to mechanical probing of ICs have been explored by various groups (Slupsky,[4] Moore,[5] Scanimetrics,[6] Kuroda[7]). These methods use tiny RF antennae (similar to RFID tags, but on a much smaller scale) to replace both the mechanical probes and the metal probe pads. If the antennae on the probe card and IC are properly aligned, then a transmitter on the probe card can send data wirelessly to the receiver on the IC via RF communication.

This method has several advantages:

References

  1. "Test & Measurement World". Probe-mark inspection.
  2. "Test & Measurement World". Investigation Conquers Probe-Card Problems.
  3. "StatsChipPac". Wafer Sort.
  4. "Slupsky, Steven". Non-contact tester for electronic circuits.
  5. "Moore, Brian". Wireless radio frequency technique design and method for testing of integrated circuits and wafers.
  6. "Scanimetrics". Scanimetrics, Inc. provides non-contact test solutions to the semiconductor industry.
  7. "Kuroda, Tadahiro". System debug method using a wireless communication interface.
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