Abstract: The laser ablation control system and method described is active in starting laser ablation, continuing laser ablation and finally tuning laser ablation in view of product output. First, it provides a means of generating initial settings for laser ablation tool operation utilizing the high predictability of ablation on substrates of known composition. Second, it provides real time monitoring and control of the laser output in terms of the characteristics important to the system performance as it relates to the abalation process. Third, it entails statistical analysis of the photo ablated pattern with correspondent adjustment to abalation parameters. Most importantly, these elements are continuously combined to achieve optimized performance monitored during the ablation process.

Abstract: A direct laser ablation process is disclosed for forming thin film transistors on liquid crystal matrix for enabling typically color presentation from a flat panel display. The thin film transistor is of the type having an active matrix addressing scheme wherein a capacitor when charged turns on and maintains in the "on" state a field effect transistor to permit passage of light through a liquid crystal display. All patterning of the display is done either by utilizing deposition, direct ablation of an etch block followed by etching, or more preferably deposition followed by direct laser ablation. In the preferred embodiment, aluminum channels are made by deposition followed by a direct laser ablation. Anodizing follows with deposition of a silicon-nitrogen layer. With respect to the capacitor, indium tin oxide is deposited to complete a matrix capable of selectively strobing and charging the capacitor for each matrix element.

Abstract: The process of the manufacture of both the conductive layers and dielectric layers of multichip modules of the deposited variety is set forth with direct etch techniques being substituted for photolithography. Simply stated, entire circuit layers of the modules are directly etched or patterned with the circuit configuration required. Three processes are disclosed for processing the individual layers including subtractive patterning of a metallic conductor layer and direct patterning of the dielectric layer; direct etch metal processing (DEMI) involving direct removal of the metal layer with subsequent direct patterning of the dielectric layer; and, plating form process involving additive metallization and direct etching of the dielectric layer. By utilizing the disclosed processes alone or in combination, fabrication of multichip modules can occur.

Abstract: A method and apparatus for the production of transparent phase reticule mask for projecting high intensity light--such as that used for direct laser ablation of materials from substrates--is disclosed. The transparent phase reticule mask includes first portions which are for scattering light beyond the solid angle of an imaging system and second transparent portions which scatter light to an angle where projection by an imaging system can occur. Phase reticule mask configurations are disclosed including a known phase reticule mask which has gratings, and a new phase reticule mask having random phase roughening for the scattering of light. Random phase roughening includes imparting to the roughened area a mean solid angle of scattering that exceeds the solid angle of collection of an image system. Thus, the total fraction of incident light is below the ablation threshold and constitutes the dark patterned region of the mask.

Abstract: The phase mask comprises binary square wave gratings which deflect light away from the collecting aperture of the projection system and binary phase gratings which deflect the incident light into a fan of rays to fill the collecting aperture. In the transmissive regions, the mask consists of randomly-placed squares etched to a depth corresponding to a half wave retardation and filling approximately fifty percent of the area within the transmissive region. The "blocking" regions consist of a binary grating etched to the same depth as that of the transmissive region but having sufficiently high spatial frequency to deflect the incident light to points outside of the collecting aperture.

Abstract: An apparatus for using and a process of using a Fresnel zone plate array is utilized for processing materials. An optically stable frame receives coherent light and passes the coherent light through beam processing optics such as a collimator, a beam expanding telescope and an aperture. Thereafter, the beam is routed to scanning mirrors immediately overlying a Fresnel zone plate array. The Fresnel zone plate array has a plurality of discrete subapertures with each subaperture containing image information at a discrete working distance from the plate; each image produced by a subaperture of the Fresnel zone plate array typically differs from adjacent images from adjacent subapertures typically in size, shape or gain. The beam is scanned and registered to a discrete selected subaperture on the plate to cause an image from the subaperture to form on a work piece located at the working distance of a scanned subaperture.

Abstract: An object is projected through the lens system to be corrected to the image plane where the position of the diffraction limited ideal image is readily ascertainable. At least one primary image defect or Seidel Aberration is measured. These aberrations include distortion, curvature of field or Petzval curvature, spherical aberration, coma, and astigmatism. Interferometry is one technique typically used to measure the aberrations of the system. Based on the measurements, the location of an apparent object is computed. The apparent object is an imaginary location of the object which would cause the image of the object to register to the diffraction limited ideal image. Although only one corrector plate may be required to achieve the desired optical system performance improvements, in the preferred embodiment at least two corrector plate mounting planes are designed and mounts made for the insertion of first and second corrector plates to correct beam convergence and focus to the ideal image.

Abstract: A metallic substrate such a copper foil has an etch barrier such polyimide, Saran Wrap.RTM., or other plastic applied. This barrier is thereafter selectively etched or ablated with a laser, for example by passing the light through a phase reticle or phase mask having at least the image information for the fine metallic lines thereon. The remaining barrier then acts in a second etch process to remove the underlying metallic layer. A wet or dry (such as RIE) etch may be employed. Over conventional photoresist exposure methods, the developer and resist steps are eliminated. The laser can precisely pattern the barrier in a single step with the remainder of the production of the required metallic fine lines relying on a simple wet etch, a process whose control parameters are well understood and consume little time. Alternately, a process for the direct ablation of metallic layers is disclosed.

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 phase mask comprises binary square wave gratings which deflect light away from the collecting aperture of the projection system and binary phase gratings which deflect the incident light into a fan of rays to fill the collecting aperture. In the transmissive regions, the mask consists of randomly-placed squares etched to a depth corresponding to a half wave retardation and filling approximately fifty percent of the area within the transmissive region. The "blocking" regions consist of a binary grating etched to the same depth as that of the transmissive region but having sufficiently high spatial frequency to deflect the incident light to points outside of the collecting aperture.

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.