Abstract: The apparatus for machining and material processing includes an excimer laser and a Fresnel zone plate array (FZP) positioned parallel to the workpiece, with the distance between the FZP and the workpiece being the focal length of the FZP. For each hole to be formed on the workpiece a corresponding Fresnel zone is patterned onto the FZP. Each Fresnel zone may be patterned directly centered over the desired hole location or in high density patterns it may be located off-center from the hole with deflection being accomplished by the formation of finer circular arcs on the side of the Fresnel zone opposite the desired direction of deflection. A beam scanner is included to provide a more uniform illumination of the FZP by the laser beam. The scanning eliminates non-uniformity of intensity. The alignment mechanism uses a helium-neon laser, the beam from the which is projected onto a surface relief grating on the workpiece.

Abstract: The apparatus for machining and material processing includes an excimer laser and a Fresnel zone plate array (FZP) positioned parallel to the workpiece, with the distance between the FZP and the workpiece being the focal length of the FZP. For each hole to be formed on the workpiece a corresponding Fresnel zone is patterned onto the FZP. Each Fresnel zone may be patterned directly centered over the desired hole location or in high density patterns it may be located off-center from the hole with deflection being accomplished by the formation of finer circular arcs on the side of the Fresnel zone opposite the desired direction of deflection. A beam scanner is included to provide a more uniform illumination of the FZP by the laser beam. The scanning eliminates non-uniformity of intensity. The alignment mechanism uses a helium-neon laser, the beam from which is projected onto a surface relief grating on the workpiece.

Abstract: The in situ process control system includes a full aperture sensor for observing the wafer through the optical train. A reference laser is provided and directed through the optical train to the wafer which partially reflects the reference beam back to an interferometer, with interference fringes being detected by the full aperture sensor. The interferometer provides a map of optical path difference before and during exposure which is then used by the control processor to monitor and control wafer warpage, aberration and distortions due to thermal effects and prior process steps. The reference laser may have multiple wavelengths to differentiate between the photoresist and the underlying layer on the wafer. Backscattered light from the wafer back through the optical train and the mask or mask plane is used to monitor exposure realtime.

Abstract: The illumination system for a semiconductor wafer stepper includes reflective elements within the projection optics of a primary mirror, a secondary mirror, a deformable mirror and a beamsplitter. The beamsplitter directs light reflected from the wafer surface back into an interferometer camera to provide depth of focus and aberration information to a computer which activates and selectively deforms the deformable mirror. Light, input from a mercury arc lamp or laser source, is projected either with an expanded or scanned beam through a reticle which is printed with the pattern to be transferred to the wafer. An interferometer is included to combine light reflected from the wafer surface with a portion of the incoming light at the beamsplitter. The interference pattern formed by that combination is used by the computer to provide realtime manipulation of focus errors, vibration and aberration by deformation of the deformable mirror.

Abstract: The imaging and illumination system with aspherization and aberration correction by phase steps includes two transparent phase plates within the optical train of a stepper illumination system. The first plate places each ray at the corrected position on the axial stigmatism plate to satisfy the sine condition. The second plate, which is the axial stigmatism plate, ensures that each ray of light focuses at the focal point. The aberration corrected light is reflected by a deformable mirror toward a secondary mirror, a primary mirror and finally onto a wafer to project a single field of large dimension. The secondary and primary mirrors provide aspherization by forming phase steps in the surfaces of the mirrors. The deformable mirror, to permit realtime correction of aberrations and manipulation of the beam for each field imaged by the system. A set of two-dimensional scanning mirrors is placed between the laser light source and a reticle containing to pattern which is to be transferred to the wafer.

Abstract: The deformable wafter chuck system includes a base with a recess having a diameter slightly smaller than the diameter of the wafer to be held. The base may have one or more orifices or channels running therethrough for distributing a vacuum to secure the wafer to the chuck, or it may have a plurality of clips attached at the rim of the chuck for holding the wafer. Attached to the chuck within the recess is a plurality of distortive actuators, such as piezoelectric crystals, which cause the wafer to be selectively deformed to assume arbitrary shapes, cancelling the warpage of the wafer to permit reduced distortion of the projected pattern. An interferometer system is included to combine light reflected from the wafer surface with a portion of incoming light modulated by a mask or reticle, thereby forming an interference pattern.