International Business Machines Corporation

Michael Stuart Gordon

Paul F Petric

James L Speidell

Rodney A Kendall

James D Rockrohr

John George Hartley

William A Enichen

Donald F Haire

Rainer Butsch

David John Pinckney

A method for monitoring resist charging in an electron beam lithography system is disclosed. The method involves the use of a reference plate (REFP) registration scheme in which a resist-coated REFP having registration marks on a substrate is prepared and scanned. The scanning process includes the deposition of an amount of charge on the surface. Then the REFP is coated with a resist to be tested and scanned again. The difference between the two scans is calculated. Preferably, each scan is performed first with the stage moving in a forward-ordered serpentine path in the tool to determine the perceived positions of the registration marks and then in a backward-ordered serpentine path. As the tool's stage moves from field to field, a small charge is deposited on the REFP to simulate the effect of a writing process. The difference between the forward and reverse scan position measurements is then determined. As any intrinsic positional errors in measurement will cancel out, the forward/backward error provides a monitor of the magnitude of resist charging.

Method for monitoring resist charging in a charged particle system

A method for improving the alignment of an electron-beam through the optical axis of lenses in a lithographic system is described. The beam is nominally tilted through the center of the lens, and by using a plurality of deflectors the beam is pivoted through the center of the lens using a square wave toggle. The resolution of the beam is measured as it scans over a target, for both toggle states. The nominal tilt angle is chosen such that the resolution is identical for both toggle states. This technique does not rely on using an observation station, as it is common on TEMs, to view a magnified image of the specimen. Therefore, this technique can be used to align a beam that has been shifted off the optical axis, for instance, in a Variable-Axis-Lens lithography (VAL) system.

Method for centering a lens in a charged-particle system

A method for reducing contamination in a silicon membrane mask in a lithography system is described. The method includes: doping the top surface of the silicon membrane mask with boron to lower the electrical resistance of the mask; subsequently metalizing the surface of the mask to further lower its electrical resistance; and, finally, applying a voltage between opposite surfaces of the mask, the voltage generating an electric field that passes through the membrane mask, heating the membrane mask. The method further includes: calculating distortions in the shape of each of the patterns within the mask caused by heating the membrane mask; compensating for the proximity of other shapes positioned in the vicinity of each of the patterns; and appropriately modifying the shape of each of the patterns. The above described method can be equally applied to an e-beam system or to an ion-beam lithography system, and both, to stencil masks and to scattering masks.

Heater for membrane mask in an electron-beam lithography system

A charged particle beam is controlled by two pairs of deflectors that adjust the beam through two or more deflection centers, thereby saving cost and space and reducing system noise. The mathematics of the superposition of signals and, therefore, of the deflecting fields provide orthogonality of the adjustments so that all adjustments are independent of each other.

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Somers, NY, United States of America

Michael Stuart Gordon