International Business Machines Corporation

Dietmar Wagner

Michael H Kallmeyer

The invention refers to a lithographic device for transferring patterns onto a wafer. The task of the invention is to create a new optical lithographic device with improved resolution and depth of sharpness which will allow semiconductor components to be produced with a higher packing density. According to the invention, an imaging device is used which includes an interferometric device with confocal beam path and a reflection phase shift mask. Based on the achievable resolution and depth of sharpness, the device is suitable for use in DUV step and scan systems for the manufacture of highly integrated semiconductor components. Electron-beam and x-ray lithography only have to be used for smaller grids.

Reflective phaseshift lithography system

Method and an apparatus for determining line centers in a microminiature element such as on a semiconductor wafer or a mask having linewidths and other spacings below the one micron range. The invention uses, two focussed laser beams which are directed across a line on the element, both beams being illuminated successively with a distance therebetween below the classic resolving power. A portion of the incident beam and a portion of the beam reflected from the line is conducted to respective detectors which respectively generate measurement and reference signals. These signals are treated to eliminate high frequency noise components therein. Subsequently, the filtered measurement and reference signals are digitized and synchronously processed to provide two sine shaped curves whose intersection point corresponds to the center of the scanned line.

Method and apparatus for determining line centers in a microminiature

This teaches a method and device for testing of the surface of a transparent object such as a photolithographic mask in which respective recordings with darkfield reflection illumination and darkfield transmission illumination is made, and the intensities measured are compared to form a different image, in which defects are characterized by high local levels of light intensity. Both recordings can be generated in a point-by-point mode if the surface is scanned by a focussed laser beam. In another embodiment, two recordings of the entire surface are digitized, and examined arithmetically for local image differences. Surfaces of opaque bodies can also be examined with the difference image of two darkfield reflection recordings made at different angles of illumination.

Method for surface testing

Apparatus for dark field illumination consisting of light conducting fibers having end faces arranged within an annular region which is coaxial with the optical axis of an optical assembly, such as a microscope objective. The annular region is within the numerical aperture of the optical assembly and is positioned in the rear focal plane thereof so that light emitted by the fibers becomes dark field illumination for the object plane of the optical assembly when viewed through the central aperture of the annular region. Illumination of the object plane through the central aperture also dark field illuminates the object plane when viewed through the fibers. This is true even when the object plane is illuminated in only a small area by forcussing an illumination source through the central aperture and onto the object plane.

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Fellbach-Oeffingen, Germany

Dietmar Wagner