SIMS AS AN END-POINT DETECTOR IN MICRO-MACHINING WITH FOCUSED ION BEAMS.

Machining or sputtering patterns with micron-sized dimensions, and submicron dimensional control can now be readily accomplished with Focused Ion Beams (FIB). The ion beam spot size (2.0microns) and vector scan control allow the lateral resolution, but the depth information must somehow be obtained. We are frequently required to sputter to an interface which is buried beneath two or more layers, with a depth resolution of a few hundred angstroms. SIMS is a natural choice as an end point detector for focused ion beam machining. High sensitivity is necessary, since the primary ion beam current is of the order of 100 pA. Our instrument has a sensitivity of 4 x 10 sup 5 cps/nA of Ga primary beam current. The SIMS has been incorporated into the FIB instrument so as to be non-interfering with any of the other functions of the machine.