Thermal-wave measurement techniques have recently been developed for measuring ion implant dose over the range 1E10 to 1E16 ions/cm2. The spatial resolution obtained with this method is 1 µm, an improvement of approximately 3000X over that of other dose monitors. This resolution capability together with the fact that the thermal-wave measurements are noncontact and nondestructive, permit dose measurements to be made on implanted areas (device features) on patterned wafers, as well as on test wafers.
A new potential application of the thermal-wave technique is the measurement of dose implanted by focused ion beam (FIB). Since the FIB technique is a high-resolution, direct-write process and since current FIB systems are limited to scan fields of less than 0.5 mm2, a high-resolution probe to monitor dose and uniformity is necessary.
In this paper, we report the measurement of ion dose implanted by focused beams into areas of ‹10−2 mm2. Even single FIB-implanted lines of 0.20 µm width have been detected, and programmed lateral dose variations measured. Experimental results demonstrating the potential of this technique are presented.