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Ultratech Stepper, Inc., was founded in 1979 by Leo de Bos, located in Santa Clara, California. The product line consisted of 1x microlithography steppers, using a unique catadioptric lens design. Until 1992, Ultratech Stepper, Inc., was a subsidiary of General Signal. Previous presidents included Leo de Bos and George Rutland.
Once this fine alignment is completed, the shot is exposed by light from the stepper's illumination system that passes through the reticle, through a reduction lens, and on to the surface of the wafer. A process program or "recipe" determines the length of the exposure, the reticle used, as well as other factors that affect the exposure.
In March 1993 Zafiropoulo acquired certain assets and liabilities of the Ultratech Stepper Division of General Signal, and the new company became independent, as Ultratech Stepper, Inc. Zafiropoulo became the President, CEO and Chairman of the newly independent Ultratech Stepper. Later it was renamed Ultratech, Inc. [2]
a 26 gauge needle bent twice used for incising the anterior capsule of the lens in lens extraction Wire vectis: a loop of wire attached to a stack used to extract cataract affected lenses Irrigating vectis: a small hollow instrument with a used to introduce fluid into the anterior chamber to raise its pressure to aid cataract extraction [2] Canula
The lenses in the highest resolution "dry" photolithography scanners focus light in a cone whose boundary is nearly parallel to the wafer surface. As it is impossible to increase resolution by further refraction, additional resolution is obtained by inserting an immersion medium with a higher index of refraction between the lens and the wafer.
The first contact lenses were made of glass, in 1888. Initially the glass was blown but soon lenses were made by being ground to shape. For the first fifty years, glass was the only material used. The lenses were thin, yet reports of injury were rare. In 1938 perspex (polymethylmethacrylate, or PMMA) began to replace glass in contact lens ...
In a modern stepper or scanner, the pattern in the photomask is projected and shrunk by four or five times onto the wafer surface. [10] To achieve complete wafer coverage, the wafer is repeatedly "stepped" from position to position under the optical column or the stepper lens until full exposure of the wafer is achieved. A photomask with ...
Beyond the models used for RET and OPC, computational lithography attempts to improve chip manufacturability and yields such as by using the signature of the scanner to help improve accuracy of the OPC model: [8] polarization characteristics of the lens pupil, Jones matrix of the stepper lens, optical parameters of the photoresist stack ...