Charged particle beam system
AssigneeFEI Company
InventorsDiane K. Stewart, W. Ralph Knowles, Brian T. Kimball
Life of this patent
Estimating the term…
Abstract
A charged particle beam system uses an ion generator for charge neutralization. In some embodiments, the ion generator is configured to maintain an adequate gas pressure at the ion generator to generate ions, but a reduced pressure in the remainder of the vacuum chamber, so that another column can operate in the chamber either simultaneously or after an evacuation process that is much shorter than a process that would be required to evacuate the chamber from the full pressure required at the ion generator. The invention is particularly useful for repair of photolithography masks in a dual beam system.
Claims26
A charged particle beam apparatus comprising:
- a work piece vacuum chamber for containing a work piece and having a background chamber pressure;
- a charged particle beam source;
- a charged particle beam optical column for directing a particle beam along an optical axis toward the work piece;
- a charged particle detector comprising a volume including a detector gas ionizable by the charged particles, electrodes to produce an electric field to cause the ionization to take place, and a detector plate to detect signals induced in the ionized gas, the charged particle detector including a passage for delivery of the detector gas to maintain the pressure of the detector gas around the detector sufficient to operate the detector, while maintaining the pressure in the work piece vacuum chamber at a significantly lower pressure.
A charged particle beam apparatus comprising:
- a work piece vacuum chamber for containing a work piece and having a background chamber pressure
- a charged particle beam source;
- a charged particle beam optical column for directing a particle beam along an optical axis toward the work piece;
- an ion generator in which secondary particles generated by the impact of charged particle beam on a work piece or particles from the primary beam backscattered by the work piece ionize an ion producing gas, the ion generator positioned such that at least some of the ions travel to work piece to neutralize charge on the work piece, the ion generator including a chamber containing a gas, the chamber connected to the work piece vacuum chamber though an aperture that allows secondary or backscattered particles from the work piece to enter the chamber and allows ions to exit the chamber to neutralize charge on the work piece.
A charged particle beam apparatus comprising:
- a work piece vacuum chamber for containing a work piece and having a background chamber pressure
- a charged particle beam source;
- a charged particle beam optical column for directing a particle beam toward the work piece;
- an ion generator in which secondary particles generated by the impact of charged particle beam on a work piece or particles from the primary beam backscattered by the work piece ionize an ion producing gas, the ion generator positioned such that at least some of the ions travel to work piece to neutralize charge on the work piece, the ion generator configured such that the ion producing gas is maintained at a sufficiently high pressure at the ion generator to produce sufficient ions from the secondary or backscattered particles to neutralize charge accumulation on the work piece, while the background chamber pressure remains at a significantly lower pressure.
An ion generator for controlling charge on a sample that produces secondary electrons as it is being worked on in a sample chamber, comprising:
- a body having rear and forward ends and a gas inlet opening to be controllably supplied with a gas, the forward end having an aperture opening to receive the secondary electrons and to emit positively charged ions;
- a detector electrode mounted within said body;
- and
- a channel electrode mounted within the body between the detector electrode and the aperture opening to channel the secondary electrons toward the detector electrode, the channel and detector electrodes defining an inner volume, wherein the body is configured to maintain the supplied gas at least within the inner volume at a working pressure sufficiently higher than that of the sample chamber to promote gas ionization cascades thereby generating positively charged ions to be emitted from the inlet opening and providing an amplified secondary electron signal to the detector electrode.
Dependencies are inferred from the claim text.