Themes > Science > Physics > Nuclear Physics > Applications of Nuclear Physics > Materials
Ion Implantation
Chip manufacturers create integrated circuits
by doping silicon wafers with boron or phosphorous ions. Ion implantation
systems load several wafers onto a wheel and rotate the wheel in front of
an ion beam (see the photo below to the left). They accelerate the dopant
ions to high energies and shoot them into the wafers. The ion accelerators
in these systems are descendants of nuclear physics research tools.
Nitrogen ions implanted into surgical alloys help prevent repeated surgery to replace hip prostheses by reducing wear and corrosion from normal body fluids. The photograph below to the right shows a nitrogen-implanted artificial femur.
Ion Implantation System for
Semiconductor |
Ion Implanted Artificial Femur |
RBS and Channeling
Rutherford back scattering (RBS) and channeling are quality assurance techniques in the semiconductor industry. Both techniques accelerate alpha particles (helium nuclei) toward a chip. RBS experiments study the reflected alpha particles to measure levels of impurities. Channeling experiments check the effectiveness of ion implantation. Implanted boron and phosphorous ions serve their intended purpose as electron donors or receptors only if they sit on a silicon site in the crystal lattice -- not if they occupy random interstitial sites. Since interstitial ions block the transmission of alpha particles through channels in the lattice, channeling experiments can detect them.
Information provided by: http://www.phy.anl.gov