High pressure charged particle beam system
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.
1. 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.
2. The particle-optical apparatus of claim 1 , in which the gas inlet comprises a gas inlet connecting the sample cell to a source of molecules other than H 2 O, N 2 or air.
3. The particle-optical apparatus of claim 1 , 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.
4. The particle-optical apparatus of claim 1 , 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.
5. The particle-optical apparatus of claim 1 , in which the sample cell pressure is greater than 10 mTorr.
6. The particle-optical apparatus of claim 5 , in which the sample chamber pressure is lower than 10 mTorr.
7. 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, the focusing column including an objective lens for focusing the charged particle beam onto the sample surface;
a sample cell within the sample chamber for receiving a sample, the sample cell being sealed against the objective lens and being sufficiently enclosed to maintain a gas pressure different from that in the sample chamber outside the sample cell;
a gas inlet connecting the sample cell to a source of a deposition precursor gas or an etch precursor gas;
a gas outlet from the sample cell directly 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;
a first pressure limiting aperture positioned between the sample cell and the charged particle beam focusing column so that most of the gas escaping from the sample cell through the pressure limiting aperture enters the charged particle beam focusing column;
an outlet for exhausting gas from the charged particle beam column above the first pressure limiting aperture;
a second pressure limiting aperture positioned above the exhaust outlet.
8. The particle-optical apparatus of claim 1 , in which the gas inlet includes multiple gas inlets for introducing gas into the cell.
9. The particle-optical apparatus of claim 1 , in which the sample cell comprises corrosion-resistant material.
10. The particle-optical apparatus of claim 1 , 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.
11. The particle-optical apparatus of claim 7 , further comprising a movable cell stage inside the sample chamber for aligning the cell with a primary beam axis.
12. The particle-optical apparatus of claim 1 including a thermally isolated sample stage for holding the sample within the sample cell.
13. The particle-optical apparatus of claim 1 , further comprising a heater for heating the sample.
14. The particle-optical apparatus of claim 1 , further comprising a source of energy for heating the cell walls.
15. The particle-optical apparatus of claim 1 , in which the sample cell includes an optically transparent window for viewing the sample.
16. The particle-optical apparatus of claim 1 , in which the detector comprises an electrode that detects an electrical signal induced by the flow of charge in the gas cascade.
17. The particle-optical apparatus of claim 1 , in which the charged particle beam column includes a magnetic lens, the magnetic lens producing a magnetic field that extends the path of electrons in the gas to produce additional collision.
18. The particle-optical apparatus of claim 1 , in which the detector includes an electrode positioned at least 3 mm from the sample to amplify the electron current.