Slide 15 of 64
This slide shows a view of one of the multichannel probes (GGB in this case). The GGB probes offer 40 GHz of bandwidth on some channels. Alignment of the probe onto the wafer must be done with great care to insure that all channels touch down, but that the probe is not damaged. The wafer is cooled underneath by a Peltier pump on a water chuck. The Peltier pump permits some variation in the operating temperature, even to the point of ice forming in a humid room on the surface of a die. Care must be exercised to prevent incorporation of water into the polyimide dielectric as this degrades performance.