A sample scanning system with nanometric accuracy for quantitative SPM measurements

A sample scanning device operating in a working volume of 30 x 30 x 18 mum with interferometer and capacitance-based controls of displacements, is des cribed. The xy-stage uses plane mirror linear interferometers and fast phas e-meters for control of displacements of precise ball-bearing stages driven by piezo flexure actuators. The stage operates with a full range bandwidth of 200 Hz, and an estimated accuracy (k = 2) of 3 nm + 1 x 10(-3) L, where L is the lateral displacement. A novel z-stage based on a kinematic coupli ng between two plates, the upper one being moved by three bimorph plates an d the distance being measured by three capacitive sensor, is described. The tilt of the z-stage is kept within fractions of a microrad, leading to a f ull range estimated accuracy of 2 nm + 2 x 10(-3) h, where h is the vertica l displacement. The control bandwidth is of about 1 kHz, thus allowing fast and accurate step-height measurements. In order to test the device used in a scanning probe microscope, micrometric patterned surfaces made using hig h resolution e-beam lithography and precise metal deposition on silicon are imaged. Results of pitch measurements are discussed and compared with thos e obtained using optical diffractometry. (C): 2001 Elsevier Science B.V. Al l rights reserved.