DELIVERY OF LOW PRESSURE DOPANT GAS TO A HIGH VOLTAGE ION SOURCE

摘要

A system for delivery of low-pressure dopant gas to a high-voltage ion source in the doping of semiconductor substrates, in which undesired ionization of the gas is suppressed prior to entry into the high-voltage ion source, by modulating electron energy upstream of the high-voltage ion source so that electron acceleration effects are reduced to below a level supporting an electronic ionization cascade. The gas delivery system in a specific application includes a gas flow passage, a voltage generator electrically coupled with at least a portion of the gas flow passage to impose an electric field thereon, and an obstructive structure that is deployed to modulate acceleration length of electrons of the low-pressure gas in relation to ionization potential of the gas, to suppress ionization in the gas flow passage.