Abstract: A method for compensating for flare-induced critical dimensions (CD) changes in photolithography. Changes in the flare level results in undesirable CD changes. The method when used in extreme ultraviolet (EUV) lithography essentially eliminates the unwanted CD changes. The method is based on the recognition that the intrinsic level of flare for an EUV camera (the flare level for an isolated sub-resolution opaque dot in a bright field mask) is essentially constant over the image field. The method involves calculating the flare and its variation over the area of a patterned mask that will be imaged and then using mask biasing to largely eliminate the CD variations that the flare and its variations would otherwise cause. This method would be difficult to apply to optical or DUV lithography since the intrinsic flare for those lithographies is not constant over the image field.

Abstract: A method of etching a semiconductor crystal is given. The crystal includes elements selected from one of the groups: (a) indium and phosphorus; (b) gallium and arsenic; (c) aluminum and arsenic. The method comprises the steps of placing the crystal in an aqueous solution of H.sub.3 PO.sub.4 or HCl, and while the crystal is in contact with the solution illuminating predetermined regions of the crystal with light so that etching proceeds at the illuminated predetermined regions much more rapidly than at nonilluminated regions of the crystal. The method also includes focusing the light to a small spot on the crystal and moving the spot on the crystal so that a groove is etched in the crystal.

Abstract: Many prior art bistable optical devices require resonant optical cavities and are therefore limited in their operation due to the long lifetimes associated with their high-finesse cavities. A bistable optical device that does not use a resonant cavity is disclosed wherein a nonlinear medium whose index of refraction increases with increased light intensity is arranged to have input and output faces into which and out of which a laser beam having a nonuniform spatial profile can be propagated. A mirror having a predetermined area of reflectivity is positioned with respect to the output face of a nonlinear medium so as to reflect only the light energy that propagates in an area at the output face that is approximately equal to the area which the beam presents at this face when the beam is propagating at a critical power level, that is, when the beam is self-trapped.

Abstract: An atomic or molecular beam detector is disclosed wherein the beam to be detected is coupled through a chopper to form a spatially modulated beam which is then directed at the pressure sensitive surface of a small sensitive microphone. The electrical output signal of this microphone is coupled to a phase-sensitive detector in order to detect the energy that is present in the signal at the frequency corresponding to the chopping rate. In the specific embodiment disclosed, a light beam is also coupled through the chopper in order to develop a second electrical signal which is mixed with the electrical output of the microphone and then coupled through a low pass filter to provide a DC signal when the atomic or molecular beam is present.

Abstract: A cw laser beam of radiation superimposed upon a beam of particles, for example a beam of neutral particles, can cause substantial changes in particle trajectories when the radiation frequency is tuned near a resonant transition in the particle. The particles can be confined by, ejected from, or steered by the laser beam. The present invention teaches the range of values over which the frequency of electromagnetic radiation is to be offset from the frequency of a particle resonance, as a function of radiation power for specific wave propagation modes, to produce best focusing of the particle beam by a copropagating beam of electromagnetic radiation. Our invention takes into account the effect of random fluctuations which arise out of the quantum nature of the electromagnetic wave-particle interaction in order to determine the appropriate range of values.

Abstract: The present invention relates to an apparatus for providing second harmonic generation from a single beam in an isotropic medium. An isotropic medium having a two-photon transition between a first level and a second level with a quadrupole moment therebetween is exposed to a beam of laser radiation. The photons in the laser beam have an energy which is substantially equal to one-half the energy difference between the first and second levels.