Guard ring for a differentially pumped seal apparatus

Radiant energy – Inspection of solids or liquids by charged particles – Analyte supports

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Details

2504401, G01F 2100, G21K 508

Patent

active

048374431

ABSTRACT:
Disclosed is a guard ring (20) in a particle beam lithography system (10) of a pressurized gas surrounding a seal apparatus (14) and concentric therewith so that the guard ring (20) of gas is located between the seal apparatus (14) and ambient pressure in which the remainder of the workpiece (12) is located and forms a curtain of gas surrounding the seal apparatus (14) to reduce contamination of the seal apparatus (14) and beam column (16). In one embodiment, the guard ring (20) is formed by a ring of small ports (60) connected to a source of pressurized gas so that gas at a pressure higher than the ambient pressure is directed toward the workpiece (12). In a second embodiment, the guard ring (20) is formed by a small width groove (72) connected by gas ports (60) to a source of pressurized gas (64) by which gas is introduced into the groove (72). In a third embodiment, the guard ring (20) is formed by a plurality of gas ports (60) and counterbores (74) connected to a source of pressurized gas (64) by which gas is introduced into said counterbores (74). Both the groove (72) and the counterbores (74) serve to distribute the emitted pressurized gas. The emitted pressurized gas may be filtered dry air or gas, or an inert or an ionized gas, all of which may be preheated.

REFERENCES:
patent: 4563587 (1986-01-01), Ward et al.
patent: 4563924 (1986-01-01), Runkle et al.
patent: 4571850 (1986-02-01), Hunt et al.
patent: 4584479 (1986-04-01), Lamattina et al.
patent: 4607167 (1986-08-01), Petrie
patent: 4669226 (1987-06-01), Mandler

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