A MICROSCOPE that fires pulses of antimatter can pick up defects that no
other microscope can detect, say the German scientists who designed it.
Antimatter microscopes could be invaluable to people who make silicon chips.
Werner Triftsh盲user at Munich鈥檚 Military University used a radioactive
isotope of sodium that produces positrons鈥攁nti-electrons鈥攁s it
decays. The positrons pass through a series of electric fields that bunch them
into pulses before they strike the target on the microscope stage.
When positrons collide with a material, they recombine with electrons,
producing a flash of light. But since positrons are positively charged, they are
drawn to defects in the material鈥檚 surface where positively-charged atomic
nuclei are missing. These regions also have fewer nearby electrons, so positrons
last longer before being destroyed.
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Triftsh盲user fired pulses of positrons at a silicon wafer etched with a
pattern of defects and recorded how long the positrons lasted. He found that
those stuck inside defects lasted twice as long as the others. Alexander Weiss
of the University of Texas at Arlington says the antimatter
microscope鈥攄escribed in next week鈥檚 Physical Review Letters
鈥攚ill be useful for the semiconductor industry, which strives to keep
defects in silicon wafers to a minimum.