Linear gas bearing with integral vacuum seal for use in serial process ion implantation equipment

Apparatus comprising a high vacuum chamber having a chamber wall, a platen disposed within said high vacuum chamber, a shaft connected to said platen and extending through said chamber wall for generally vertical reciprocating movement with respect to said high vacuum chamber, a bearing including a bearing sleeve connected to said chamber for slidably receiving said shaft, said bearing forming a plurality of internal grooves axially spaced along said shaft, means for interconnecting said grooves with a gas film disposable between said shaft and said sleeve, vacuum pump means for establishing selected pressures in said grooves, and thereby forming a seal between said shaft and said sleeve while accommodating said relative movement therebetween, wherein ambient pressure acting on said shaft outside said high vacuum chamber and high vacuum acting on said platen and shaft within said high vacuum chamber form a differential pressure acting thereon selected such that said differential pressure creates a counteracting force which tends to pull said shaft and platen vertically upward so as to counterbalance gravity forces tending to pull said shaft and platen vertically downward.

A linear bearing system for ion implant equipment comprising a high precision shaft of predetermined diameter extending through a wall of a high vacuum chamber, a bearing sleeve connected externally to said chamber for slidably accommodating said shaft for linear, reciprocating movement with respect thereto, said bearing sleeve defining a plurality of internal annular grooves at successively lower respective pressures between atmospheric pressure and high vacuum levels, said grooves axially spaced along and adjacent said high precision shaft, vacuum pump means for establishing and maintaining said pressures in said grooves, and means for maintaining a gas film of preselected thickness between said precision diameter shaft and said bearing sleeve and interconnecting said grooves, and wherein the one of said grooves nearest said chamber being maintained at a pressure sufficient to set a flow of gas between said shaft and said bearing sleeve and into said chamber to negligible levels, whereby a non-contact seal is provided between said high precision shaft and said bearing sleeve while permitting linear, reciprocating motion of said shaft with respect to said bearing sleeve.