High pressure charged particle beam system
AssigneeFEI Company
InventorsWilliam Ralph Knowles, Rae Knowles, Milos Toth
Life of this patent
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Abstract
The current invention includes methods and apparatuses for processing, that is, altering and imaging, a sample in a high pressure charged particle beam system. Embodiments of the invention include a cell in which the sample is positioned during high pressure charged particle beam processing. The cell reduces the amount of gas required for processing, thereby allowing rapid introduction, exhaustion, and switching between gases and between processing and imaging modes. Maintaining the processes gases within the cell protects the sample chamber and column from contact with the gases. In some embodiments, the temperature of the cell walls and the sample can be controlled.
Claims52
A particle-optical apparatus comprising:
- a sample chamber;
- a sample cell for receiving a sample within the sample chamber, the sample 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 molecules other than H2O, N2 or air;
- a charged particle beam source;
- a charged particle beam focusing column for directing charged particles from the charged particle beam source toward the sample;
- and
- at least one pressure limiting aperture, positioned between the charged particle beam source and the sample, for maintaining the pressure at the sample higher than the pressure in the charged particle beam focusing column.
A particle-optical apparatus comprising:
- a sample chamber;
- 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 a gas;
- a charged particle source;
- a charged particle beam focusing column for directing charged particles from the charged particle source toward the sample;
- at least one pressure limiting aperture, positioned between the charged particle source and the sample, for maintaining a lower pressure in the charged particle beam column than at the sample;
- a detector positioned apart from the sample stage for detecting electrons emitted from the sample, the electrons emitted from the sample comprising an electron current, the electron current being amplified by collisions with electrons in the gas to produced an amplified imaging signal for forming an image of the sample.
The particle-optical apparatus of any of the above claims, in which the gas inlet connecting the sample cell to a source of gas includes a gas inlet connecting the sample cell to a source of gas molecules comprising organics, metalorganics, organometallics, organohalides, aromatics, amines, or organosilanes.
The particle-optical apparatus of any of the above claims, in which the gas inlet connecting the sample cell to a source of gas includes a gas inlet connecting the sample cell to a source of gas molecules comprising phosphines, halides, chlorides, fluorides, metal halides, metal chlorides, metal fluorides, metal hydrides, or silanes.
The particle-optical apparatus of any of the above claims, in which the sample cell pressure is greater than 10 mTorr.
The particle-optical apparatus of any of the above claims, in which the sample cell includes a gas outlet, the gas outlet being separate from the gas inlet, the gas outlet being other than through the pressure limiting aperture and the focusing column.
The particle-optical apparatus of any of the above claims, further comprising a valve for selectively connecting the gas input to one or more of multiple gas sources to allow for switching among gas sources.
The particle-optical apparatus of any of the above claims, in which the gas inlet includes multiple gas inlets for introducing gas into the cell.
The particle-optical apparatus of any of the above claims, in which the sample cell comprises corrosion-resistant material.
The particle-optical apparatus of any of the above claims, in which the surfaces of the sample cell comprise stainless steel.
The particle-optical apparatus of any of the above claims, in which the gas inlet connecting the sample cell to a source of a gas includes a gas inlet connecting the sample cell to a source of a gas that, when activated by the charged particle beam, etches material from or deposits material onto, a sample in the sample cell to form an element in a microscopic structure.
The particle-optical apparatus of any of the above claims, further comprising a movable cell stage inside the sample chamber for aligning the cell with a primary beam axis.
The particle-optical apparatus of any of the above claims, further comprising a movable sample stage within the sample cell for changing the position of the sample.
The particle-optical apparatus of any of the claims including a thermally isolated sample stage for holding the sample within the sample cell.
The particle-optical apparatus of any of the above claims, further comprising a heater for heating the sample.
The particle-optical apparatus of any of the above claims, further comprising a source of energy for heating the cell walls.
The particle-optical apparatus of any of the above claims, in which the sample cell includes an optically transparent window for viewing the sample.
A method of processing a sample using a particle-optical apparatus having a charged particle beam focusing column and a sample chamber containing a sample cell separated from the charged particle beam focusing column by at least one pressure limiting aperture comprising:
- delivering a first gas other than water vapor, air or nitrogen to a sample in the sample cell through a gas input connected to the sample cell;
- maintaining the sample cell at a pressure higher than the pressure of the sample chamber;
- and
- directing a beam of electrically charged particles through the charged particle beam focusing column and through the at least one pressure limiting aperture towards a sample to process the sample;
- where the pressure in the sample cell is higher than the pressure in the charged particle beam focusing column.
A method of fabricating a microscopic structure using an electron beam in an electron beam apparatus including an electron beam column, a sample chamber separated from the electron beam column by a pressure limiting aperture for maintaining pressure in the electron beam column lower than the pressure in the sample chamber, and a sample cell for receiving a sample positioned within the sample chamber, the sample cell sufficiently enclosed to maintain a gas pressure different from that in the sample chamber, and the sample chamber maintaining the sample cell including a gas inlet, the method comprising:
- positioning a sample in the sample cell;
- delivering a first precursor gas through the gas inlet into the sample cell;
- maintaining the pressure in the sample cell higher than the pressure in the sample chamber;
- maintaining the pressure in the sample chamber higher than the pressure in the electron column;
- and
- producing a desired microscopic structure by directing a sub-micron electron beam toward the sample, the electron beam activating the precursor gas to locally etch from or deposit material onto the sample near the impact point of the electron beam to produce the desired structure.
A method of processing a sample using a particle-optical apparatus having a charged particle beam focusing column and a sample chamber containing a sample cell separated from the charged particle beam focusing column by at least one pressure limiting aperture comprising:
- delivering a first gas to a sample in the sample cell through a gas input connected to the sample cell;
- maintaining the sample cell at a pressure higher than the pressure of the sample chamber;
- and
- directing a beam of electrically charged particles through the charged particle beam focusing column and through the at least one pressure limiting aperture towards a sample to process the sample;
- detecting electrons emitted from the sample using a detector positioned apart from the sample stage, 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,
- where the pressure in the sample cell is higher than the pressure in the charged particle beam focusing column.
Dependencies are inferred from the claim text.