Patent ID: 7304319

Claim:
A charge compensation device for suppressing charging of a wafer, when said wafer is irradiated with a charged particle beam containing an ion beam extracted from a beam generation source unit onto the wafer, while reciprocal scanning by the reciprocal swinging beam over a predetermined scanning range on a beam line, wherein said charge compensation device comprises: at least one first arc chamber having at least one first extraction hole which opens up in a second arc chamber; and the second arc chamber having at least one second extraction hole faced on said reciprocal swinging beam of said predetermined scan range on the beam line, a first arc voltage being applied to said first arc chamber to produce first plasma in said first arc chamber, the generated first plasma being extracted from said first arc chamber and introduced into said second arc chamber, and second plasma being produced in said second arc chamber again, and second extracted plasma from said second arc chamber forms a plasma bridge between said second extraction hole and said reciprocal swinging beam, and wherein said second arc chamber extends over said predetermined scan range and said second extraction hole is in the form of a single slit extending over said predetermined scan range or in the form of a plurality of holes arranged at intervals over said predetermined scan range.