Movable needle type of liquid-metal-ion sources for boron and phosphorus ions

A movable needle type of liquid-metal-ion source (LMIS) has been developed for boron (B) and phosphorus (P) ions. The needle movement is very effective for accomplishing good wetting between the needle and the molten metal as well as for balancing the ion emission and inflow of the source metal at the needle apex. These features lead to stable ion emission under a wide range of experimental conditions. The B-LMIS using a combination of carbon or carbide needle and Ni--B--Si alloy emits stable B+ ions with an atomic fraction of 25% to 35%. The P-LMIS using Pt--P--Sb alloy provides a large amount of P+ and P++ atomic fractions (15%--30%) with a P++/P+ ratio of 0.5 to 2. The experimental results on energy spread per unit charge, ΔE(M/sup n/+)/n, agree with the general relationship [ΔE(M++)/2≤ΔE(M+)<ΔE(M++)]. The source lifetime is more than 250 and 150 h for the B- and P-LMIS's, respectively. These LMIS's have the capability of providing stable B and P focused-ion-beams (FIB's) by mounting them on an FIB apparatus