The new M-series metrology scanner is the latest addition to the Quesant line of products. This is a full 3-axis metrology scanner developed specifically for applications requiring a high degree of accuracy and repeatability in surface topography measurements. The unique capacitive position sensors in its design ensures consistent measurement performance regardless of the scan size, speed, offset, or rotation.

       Figure 2 illustrates the kind of improvement in performance you can expect. After taking an initial 80µm scan of the integrated circuit pattern the user is able to zoom-in and rotate the scan in one step to look at a surface detail. There is no need to wait for the transient response of the piezoelectric material to decay- no need to be concerned about variations in the scanner calibration with the new scan parameters. Precise measurements can be taken immediately.

       The dynamic range of the M-series scanner is 80µm in X and Y, and >8µm in Z. It can be installed into either the Q-350 or Q-400 platforms. In addition, all of the standard modes of operation ( Con-tact, Wavemode, Lateral Force, Phase, MFM) are available with this scanner.

       The inner workings of Quesant's unique capacitive position sensor can be understood with the help of Figure 3. Consider the Z axis sensor first. This is formed by the three circular capacitor plates (violet, green, violet) at the bottom of the piezo translation tube (gray). The outer two plates are fixed in position, while the middle plate is attached to the piezo tube and moves vertically with the tube as it expands and contracts. The vertical position of the probe is measured by oscillating the fixed plate potentials 180° out of phase, producing a time varying voltage at the center plate proportional to its relative position, and then synchronously detecting and filtering the center plate voltage to produce the Z position signal. The XY position of the probe is measured in a similar manner via the electrodes on a pair of concentric cylinders located above the Z stack. In this case, the electrodes on the fixed outer cylinder generate the time varying voltage detected by the X-pair and Y-pair of electrodes on the inner cylinder, which is affixed to the translation tube.