METHOD FOR THE MEASUREMENT OF THE LATERAL DOSE DISTRIBUTION OF DOPANTS AT IMPLANTATION OR DIFFUSION MASK EDGES (LATERAL SIMS)

A method is presented allowing the lateral dopant distribution in the vicinity of the edge of a linear implantation (or diffusion) mask of s pecific test samples to be measured. Basically, the sample is sectione d perpendicularly to the surface, and parallel to the mask edge. The d opant distribution into the depth of this section (i.e., parallel to t he surface of the wafer) is then measured with secondary ion mass spec trometry (SIMS), making use of its excellent depth resolution. The con cept of this approach, its requirements, the sample preparation, and f irst results obtained on ion-implanted arsenic in silicon are presente d and discussed. Limiting effects involved in this approach are identi fied, and a potentially useful extension of the method toward the meas urement of the two-dimensional dopant distribution (2D SIMS) is discus sed. The results of the measurements on ion-implanted arsenic appear t o be sufficiently accurate to provide a valuable input for comparison with computer simulation results.