The combination of deposition equipment, such as that using molecular beam epitaxy (MBE), with focused ion beam (FIB) systems makes it possible to realize maskless processing. In the conventional FIB systems, a very small beam radius in the low-energy region is difficult to obtain. Hence it is necessary to form a retarding field between the FIB column and the target. We developed a new low-energy FIB system with an electrically floating intermediate lens system, which can be utilized in the retarding mode as the target with zero bias. Using these systems, experiments on direct and selective Ga deposition were performed in the retarding mode. The incident energy (E
L) was varied from 50 to 10 eV. Selective Ga deposition, even for E
L as low as 10 eV, was confirmed by Auger electron spectroscopy.
In addition, experiments on maskless selective GaAs deposition were conducted. Ga-ion beams and As
4 molecules were supplied simultaneously on a Si substrate at the condition of E
L=50 eV and the substrate temperature of 500°C. As a result we succeeded in the selective deposition of GaAs for the first time with a low-energy FIB.
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