Apparatus for reducing distortion in fluid bearing surfaces

An ion implanter comprising:

• (i) an ion beam generator to generate a beam of ions to be implanted;
• (ii) a process chamber into which the ion beam is directed, the process chamber having a stator base thereon;
• (iii) a stator attached to the stator base providing a first planar fluid bearing surface extending in a direction of movement;
• (iv) a moving member having a second planar fluid bearing surface extending over said first surface, said moving member being mounted to be movable relative to said stator in said direction of movement, said first and second bearing surfaces being adapted to allow the second surface to be supported spaced from said first surface by a bearing fluid, one of said stator and said stator base having a locating member extending normal to the plane of said first bearing surface and the other of said stator and said stator base having a recess shaped to receive said locating member;
• (v) a fluid seal enabling said member to slide in said channel in said normal direction sealing off an enclosed volume between said member and said other of said stator and said stator base;
• (v) a plurality of fixtures at respective points distributed in a plane parallel to said first bearing surface to fix said locating member and said other of said stator and said stator base together at said points to form said enclosed volume, the number of said fixtures being the minimum necessary so that the first planar bearing surface of the said stator remains undistorted, and a fluid controller controlling the supply of a fluid to said enclosed volume to maintain said first planar bearing surface undistorted under the loading of said moving member.

A fluid bearing comprising:

• (i) a base;
• (ii) a stator attached to the base providing a first fluid bearing surface extending in a direction of movement;
• (iii) a moving member having a second fluid bearing surface extending over the said first bearing surface, said moving member being mounted to be movable relative to said stator in said direction of movement, said first and second bearing surfaces being adapted to allow the second bearing surface to be supported spaced from the said first surface by a bearing fluid, one of said stator and said base having a locating member extending in a direction of extension forming an obtuse angle with the direction of movement of the first bearing surface, and the other of the said stator and said base having a recess shaped to receive the said locating member;
• (iv) a fluid seal enabling said member to slide in said recess in said direction of extension sealing off an enclosed volume between said member and said other of said stator and said base;
• and
• (v) a plurality of fixtures at respective points distributed in a plane perpendicular to said direction of extension to fix said locating member and said other of said stator and said base together at said points to form said enclosed volume, the number of fixtures being the minimum necessary so that the first bearing surface remains undistorted, and
• (vi) a fluid controller controlling the supply of a fluid to said enclosed volume to maintain said first bearing surface undistorted under the loading of said moving member, the strength of the locating member and the stator being sufficient to prevent distortion thereof under the influence of components of the loading of the said moving member in a direction perpendicular to the said direction of extension of the said locating member.