Sample decontamination
Disclosed herein are methods that include: (a) exposing a sample in a chamber to a first gas, where the first gas reacts with surface contaminants on the sample to form a second gas; (b) removing at least a portion of the second gas from the chamber; and (c) exposing the sample to a charged particle beam to cause a plurality of particles to leave the sample and detecting at least some of the plurality of particles. The charged particle beam can include particles having a molecular weight of 40 atomic mass units or less.
1. A method, comprising:
exposing a sample in a chamber to a first gas, wherein the first gas reacts with surface contaminants on the sample to form a second gas;
removing at least a portion of the second gas from the chamber; and
exposing the sample to a noble gas ion beam to cause a plurality of particles to leave the sample and detecting at least some of the plurality of particles,
wherein the noble gas ion beam comprises particles having a molecular weight of 40 atomic mass units or less.
2. The method of claim 1 , wherein the first gas is ozone.
3. The method of claim 1 , wherein the surface contaminants comprise hydrocarbons.
4. The method of claim 1 , wherein a background pressure in the chamber during exposure of the sample to the first gas is less than atmospheric pressure.
5. The method of claim 1 , wherein the sample is exposed to the first gas during exposure of the sample to the noble gas ion beam.
6. The method of claim 5 , further comprising exposing the sample to the first gas prior to exposing the sample to the noble gas ion beam to form a second gas, and removing at least a portion of the second gas from the chamber.
7. The method of claim 6 , wherein the sample is exposed to the first gas in a region outside the chamber prior to exposing the sample to the noble gas ion beam in the chamber.
8. The method of claim 1 , wherein the plurality of particles comprise secondary electrons, scattered ions, or noble gas ions.
9. The method of claim 1 , wherein the noble gas ion beam comprises particles having a molecular weight of 20 atomic mass units or less.
10. The method of claim 1 , further comprising forming the first gas by introducing gas particles into an activation apparatus, and activating the gas particles to form the first gas.
11. The method of claim 1 , further comprising producing the noble gas ion beam in a gas field ion source.
12. The method of claim 1 , further comprising forming an image of the sample based on the detected particles, wherein a maximum dimension of a field of view of the image is 10 microns or less.
13. The method of claim 1 , further comprising, prior to exposing the sample to the first gas:
exposing the sample to the noble gas ion beam to cause a plurality of particles to leave the sample, detecting at least some of the plurality of particles, and forming an image of the sample based on the detected particles; and
analyzing the image to identify at least some of the surface contaminants.
14. The method of claim 1 , further comprising, prior to exposing the sample to the first gas:
exposing the sample to the noble gas ion beam to cause a plurality of particles to leave the sample, detecting at least some of the plurality of particles, and identifying at least some of the surface contaminants based on the detected particles.
15. The method of claim 1 , further comprising:
exposing one or more internal surfaces of the chamber to the first gas, wherein the first gas reacts with contaminants on the one or more internal surfaces of the chamber to form a third gas; and
removing at least a portion of the third gas from the chamber.
16. The method of claim 1 , further comprising, before exposing the sample to the first gas:
forming a plasma, and exposing the sample to the plasma outside the chamber, wherein the plasma reacts with surface contaminants on the sample to form products; and
removing at least a portion of the products from the sample surface.
17. The method of claim 16 , further comprising introducing the sample into the chamber.
18. A method, comprising:
exposing a sample to a noble gas ion beam to cause a plurality of particles to leave the sample and detecting at least some of the plurality of particles; and
during exposure of the sample to the noble gas ion beam, exposing the sample to a first gas, wherein the first gas reacts with surface contaminants on the sample to form a second gas, and removing at least a portion of the second gas from the chamber.
19. A method, comprising:
exposing a sample in a chamber to ozone, wherein the ozone reacts with surface contaminants on the sample to form volatile reaction products;
removing at least a portion of the volatile reaction products from the chamber; and
exposing the sample to a helium ion beam to cause a plurality of particles to leave the sample and detecting at least some of the plurality of particles.