Patent ID: 6169281
Filing Date: 2001-01-02
Classification: G01Q,Y10S

Abstract:
Apparatus for determining topographical features of a sample surface, wherein said apparatus comprises: a probe tip including a circular protrusion, extending parallel to said sample surface and movable in engagement with said sample surface; a cantilever attaching said probe tip to a probe mounting surface; Z-drive means for creating relative motion in a Z-direction, perpendicular to said sample surface, between said probe mounting surface and said sample surface, wherein said relative motion in a Z-direction includes movement to retain a level of engagement between said probe tip and said sample surface and an excitation vibration at an excitation frequency of vibration; X-drive means for creating relative motion in an X-direction, parallel to said sample surface, between said probe mounting surface and said sample surface, wherein said relative motion in an X-direction includes a first scanning movement to traverse said sample surface with said probe tip and a first dithering vibration at a first frequency of vibration; Y-drive means for creating relative motion in a Y-direction, parallel to said sample surface and perpendicular to said X-direction, between said probe mounting surface and said sample surface, wherein said relative motion in a Y-direction includes a second scanning movement to traverse said sample surface with said probe tip and a second dithering vibration at a second frequency of vibration; a detector generating a tip motion output signal in response to vibration of said probe tip in said Z-direction; a first demodulator generating, in response to said tip motion output signal, a first feedback signal representing an amplitude of vibration of said probe tip; a second demodulator generating, in response to said tip motion output signal, a second feedback signal representing variations in said amplitude of vibration of said probe tip occurring at said first frequency of vibration; and a computing system controlling said X-drive means and said Y-drive means to combine said first scanning movement and said second scanning movement so that said sample is traversed with said probe tip in a scanning direction.