International Business Machines Corporation

Warren J Pinckney

Alfred Mack

Charles A Gaston

Alan D Wilson

Brian C O'Neill

Gerard Joseph Scharff

Charles H Locke

Karl W Beumer

Anthony A Pantusco

George R Santillo, Jr

A high precision, high throughput submicrometer workpiece positioning system, particularly useful as a workpiece positioning means in electron beam lithography tools. The positioning system increases mechanical stability by essentially eliminating mechanical hysteresis, which allows state of the art electron beam lithography systems to provide the repeatable, accurate and dense circuit patterns that modern semiconductor trends demand. The positioning system in preferred form comprises a movable positioning table, a workpiece supporting superstructure which is elastically joined to the movable positioning table by three geometrically distinct kinematic support means and a two-stage coupling means which mounts a workpiece (i.e., semiconductor mask or wafer) to the workpiece supporting superstructure. A laser interferometer locating-positioning system is utilized to position the workpiece. The interferometer mirrors are integral with the workpiece supporting superstructure. The coupling means mounts a workpiece to the workpiece supporting superstructure with a minimum of mechanical distortion. Three two-stage coupling means are utilized in preferred form. The first stage is removable from the positioning, and allows for workpiece loading and unloading outside of the positioning system. The removable stage comprises an integral unit which includes two opposing arms with large radii spherical ends and a tab member. The spherical end center lines are collinear, providing for vertical clamping of the workpiece. The second stage is stationary and integral with the workpiece supporting superstructure. The stationary stage comprises two opposing arms with large radii spherical ends and clamps the tab of the removable stage by vertical clamping.

Workpiece mounting and clamping system having submicron positioning

A monocrystalline silicon ingot is grown from molten silicon by progressively lifting a monocrystalline seed from the molten silicon, which is disposed within a crucible in a furnace, through mounting the seed on a graphite pull shaft. The pull shaft is surrounded by a bellows, which is connected to a carriage to which the pull shaft also is connected. A seal, which is carried by the bellows structure, seals the pull shaft in its rotary motion. Because the bellows structure and the pull shaft are both connected to the carriage, there is no relative linear motion therebetween so that there is no necessity to seal for linear motion of the pull shaft. A pair of lifting mechanisms is connected to diametrically opposite sides of the carriage to support the carriage and to exert a lifting force on the pull shaft along its longitudinal axis. The crucible also must be raised as the level of the molten silicon is depleted due to the formation of the ingot on the seed at the end of the pull shaft. This is because there is an optimum heating zone, which is an isothermal zone and is relatively small, within the furnace, and it is necessary for the level of the molten silicon to be maintained within this zone. The crucible is lifted through being connected to a carriage, which is supported and lifted by a similar arrangement to that for lifting the carriage to which the pull shaft is connected.

Method and system for growing monocrystalline ingots

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New Fairfield, CT, United States of America

Warren J Pinckney