Microstructural changes in silicon induced by patterning with focused ion beams of Ga, Si and Au

We use focused beams of Ga+, Au+ and Si++ ions to induce local microstructural changes in single crystal silicon. The ions were delivered as single spot pulses into thin Si membranes that could subsequently be imaged and annealed in situ in a transmission electron microscope. For each ion, the focused ion beam implantation created an array of amorphous regions in the crystalline membrane. Annealing causes solid phase epitaxial regrowth to take place, but we show that the resulting microstructure depends on the ion species. For Ga+ and Au+, precipitates remain after recrystallization, while for Si++, dislocation loops form around the periphery of each implanted spot. We attribute these loops to defects formed during solid phase epitaxial regrowth, with controlled placement of the loops possible.

► Ga+, Au+ and Si++ were implanted into thin membranes of Si.
► Samples were imaged and annealed in situ in a transmission electron microscope.
► Focused ion beam implantation created an array of amorphous spots.
► After recrystallization, precipitates form for Ga+ and Au+, dislocation loops for Si++.
► Controlled placement of the dislocation loops possible.