Range and straggle of boron in photoresist

Abstract

The range and straggle of boron in KTFR are measured and found to be in excellent agreement with the theoretical values of Lindhard, Scharff and Schiøtt for projected range, R p , and straggling, Δ R p , (depth of peak and width of assumed Gaussian distribution) if an empirical correction is made to the electronic stopping power using the results of Ormrod and Duckworth. A probable deviation from a Gaussian distribution approximation is found in this experiment for the fraction of ions which penetrate shallowly ( x 《 R p , where x is the depth) but a good fit to the Gaussian assumption is seen for the deeply penetrating ions ( x 《 R p ). From the results, curves are constructed which give the thickness of KTFR necessary to stop a given fraction of incident ions so a photoresist thickness sufficient for masking purposes may be chosen.