Patent ID: 8921811

Claim:
A particle-optical apparatus comprising: a sample chamber; a charged particle source; a charged particle beam focusing column for directing charged particles from the charged particle source toward the sample; a sample cell within the sample chamber for receiving a sample, the cell sufficiently enclosed to maintain a gas pressure different from that in the sample chamber; a gas inlet connecting the sample cell to a source of an etch precursor gas or a deposition precursor gas; at least one pressure limiting aperture, directly coupling the sample cell to the charged particle beam focusing column, for maintaining a lower pressure in the charged particle beam column than at the sample; a gas outlet connecting the sample cell to a pump for evacuating the sample cell, the gas outlet being separate from the gas inlet, the gas outlet being other than through the pressure limiting aperture and the focusing column; a first stage for moving the sample cell and aligning the sample cell with the at least one pressure limiting aperture; a second stage positioned within the sample cell for moving the sample and aligning the sample with the charged particle beam; and a detector positioned apart from the first and second stages for detecting electrons emitted from the sample, the electrons emitted from the sample comprising an electron current, the electron current being amplified by a gas ionization cascade to produce an amplified imaging signal for forming an image of the sample.