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 specific test samples to be measured. Basically, the sample is sectioned perpendicularly to the surface, and parallel to the mask edge. The dopant distribution into the depth of this section (i.e., parallel to the surface of the wafer) is then measured with secondary ion mass spectrometry (SIMS), making use of its excellent depth resolution. The concept of this approach, its requirements, the sample preparation, and first results obtained on ion-implanted arsenic in silicon are presented and discussed. Limiting effects involved in this approach are identified, and a potentially useful extension of the method toward the measurement of the two-dimensional dopant distribution (2D SIMS) is discussed. The results of the measurements on ion-implanted arsenic appear to be sufficiently accurate to provide a valuable input for comparison with computer simulation results.