JUNCTION LOCATION MEASURED BY SPREADING RESISTANCE PROBE

Spreading resistance measurements are known to be the only means for profiling the whole range of silicon concentrations. But it is also known that under certain conditions of profiles and concentrations the results are somewhat questionable. In a bipolar structure for instance, both the thickness and the doping level of the base might be much lower than the actual values. A method based on experimental data has been devised and algorithms implemented to bring these values to the right ones. Moreover it must be emphasized that the sensitivity limit of Spreading Resistance Probe (SRP) has also been experimentally demonstrated. In a silicon material of doping level C(su) any foreign impurity concentration C(im) can be measured as long as C(im) > 0.01 C(su).