Method and apparatus for generating charged particles for deposition on a surface
View Patent ↗A method for establishing a calibrating standard for wafer inspection includes depositing solid ionized particles of a known size range with an aerosol onto a wafer. The method also includes depositing particles onto a wafer in a deposition chamber by using an aerosol stream and the solid particles suspended in a gas; ionizing the aerosol stream with a negative or positive charge polarity or both by passing the aerosol stream through a non-radioactive ionizer to produce charged particles and supplying such aerosol stream to the deposition chamber. An apparatus for producing charged particles includes an atomizer and a non-radioactive ionizer in fluid communication with each other. The apparatus may also include an electrospray droplet generator for producing an aerosol with dry-solid particles and an ionizer that ionizes the molecules of the gas. The apparatus may also include a generator for generating an aerosol with particles suspended in the gas with a non-radioactive ionizer that ionizes the gas in the aerosol causing the aerosol particles to be charged. The apparatus may further include an electrostatic classifier for classifying the charged particles to a selected size range.
1. A charged particle generating apparatus including an atomizer for producing an aerosol and a non-radioactive ionizer downstream and in fluid communication with the atomizer, the non-radioactive ionizer having sufficient voltage and configured to produce ionization directly in the aerosol without dilution resulting in charged particles.
2. A charged particle generating apparatus including an electrospray droplet generator configured to produce charged particles in a first gas containing dry-solid particles carrying a charge and a non-radioactive ionizer in fluid communication with each other, the non-radioactive ionizer configured to produce positive and negative ions in a second undiluted gas different than the first gas sufficient to reduce the particle charge to a level lower than the first gas.
3. An apparatus for producing a charged monodisperse aerosol including a charged particle generator containing a non-radioactive ionizer, and an electrostatic classifier, the charged particle generation being configured to produce an undiluted charged particle stream to the electrostatic classifier.
4. An apparatus for providing charged particles for deposition on a substrate, the apparatus comprising:
an electrospray generator for generating an aerosol with dry solid particles suspended in a gas;
a non-radioactive ionizer configured to ionize the gas in the aerosol to provide ions of a positive and a negative charge polarity in the gas causing the dry solid particles in the aerosol to be charged in a fashion suitable for depositing on the substrate; and
a deposition chamber in which the dry solid particles in the aerosol are deposited onto the substrate.
5. The apparatus of claim 4 and further comprising a particle classifier for classifying particles in the aerosol in a selected size range before deposition on the substrate.
6. The apparatus of claim 4 wherein the non-radioactive ionizer is a corona ionizer operating with an AC high voltage.
7. An apparatus for providing charged particles for deposition on a substrate, the apparatus comprising:
an electrospray droplet generator for producing an aerosol with dry-solid particles suspended in a first gas;
an ionizer that ionizes the molecules of the gas configured to provide ions of a positive and negative charge in a second undiluted gas different from the first gas; and
a mechanism that mixes the ionized gas with the aerosol to provide charged particles in a fashion suitable for depositing on the substrate.
8. The apparatus of claim 7 wherein the ionizer is a non-radioactive type ionizer.
9. The apparatus of claim 8 wherein the ionizer is a corona ionizer.