International Business Machines Corporation

Mark A McCord

Fritz J Hohn

Leonard Berenbaum

An X-ray mask membrane 12 is discussed wherein a cantilever and tip portion such as used on an atomic force or scanning tunneling microscope are fabricated directly as part of the mask. The mask is located over a wafer and the vertical (z) motion of the tip with respect to the wafer is achieved with a piezoelectric device which is mounted on a movable support above the cantilever. Piezoelectric device may be a tube having an electrode divided into quadrants so that the end of the tube could be positioned in three dimensions to allow for alignment of the end of the tube to the cantilever tip. X and Y motion of the tip and the mask membrane relative to the wafer is achieved by mounting the wafer on an x-y stage driven by piezoelectric or other transducers. The wafer includes a raised alignment mask on its upper surface. The wafer, mask membrane, and z piezoelectric tube are held rigidly but adjustably with respect to each other by a mechanical fixture. The z piezoelectric tube is lowered until it touches the cantilever; it is then lowered further by the designed gap spacing, deflecting the cantilever downward. The wafer is then raised until it is detected by the tip on the cantilever, either by sensing a tunneling current (STM) or a force (AFM). The wafer is now at the correct z gap setting, and is scanned back and forth in the x and y directions until the location of the alignment mark is determined by the cantilever tip following the contours of the alignment mark, thus setting the proper alignment between the wafer and the mask in the x, y direction.

X-ray mask containing a cantilevered tip for gap control and alignment

An electrical probe which incorporates a scanning proximity microscope for probing the sub-micron features of an integrated circuit. An optical microscope is provided to find the general region of interest, and a piezoelectric tube scanner which controls the position of the probe is disposed at an acute angle to the substrate, so as not to obscure the view of the optical microscope. A number of such probes may be located around the integrated circuit.

Electrical probe incorporating scanning proximity microscope

The present invention is an improved mechanism for the coarse adjustment of a scanning tunneling microscope stage. In the present invention the stage is moved by forces transmitted through rigid wire springs mounted on leaf spring assemblies which transmit the motion from rigidly mounted micrometer adjusting devices. It is intended that the coarse adjustment mechanism of the present invention will provide improved performance over coarse adjustment mechanisms presently available for STM applications. The present invention replaces separate sets of leaf springs for X and Y motion with a single set of four wire springs. This simplifies the design and increases the rigidity and stability by reducing the mechanical path length from the solid base to the X-Y-Z stage. The screw mechanisms are all directly connected to the rigid base. (This is made possible by the additional pairs of wire springs connected from the X and Y screws to the stage.) The following advantages are achieved: first, since the screw mechanisms do not move with the stage, driving mechanisms such as motors and gears can be simply connected; and, second, the rigidity and stability are again increased since the stage position is referenced directly to the base through all three screws rather than through intermediate support structures.

Growing community of inventors

Mohegan Lake, NY, United States of America

Mark A McCord