A GHz wafer prober for electron beam testing on a ps time scale

Abstract Electron-beam testing (‘e-beam’ testing) supports the development of new integrated circuits by allowing a comparison between measured and simulated internal waveforms. It avoids loading of the device under test, especially in the high frequency range of several GHz. The use of a wafer prober in combination with a high-speed e-beam test system extends the application to on-wafer measurements with a time resolution of some picoseconds. The demands made on this prober differ from those made on conventional test adapters since the prober is not used to detect signals but only to supply power and input signals to the device under test. Signals are measured exclusively by the e-beam. This offers an additional advantage since the input signals can be corrected by means of direct control by the e-beam. For example, signal losses or phase shifts due to the prober can be compensated for. While the high-frequency demands are reduced by this correction scheme, many other problems arising from the space limitations within the e-beam tester have to be solved. A new prober allows measurements in a frequency range extending to more than 10 GHz directly on the wafer without the need for cutting, mounting or bonding single chips.