The influence of junction formation process variables on diffusion sheet resistance using statistical design of experiment methodology

The statistical design of experiments technique was used to study the influence of junction formation process variables on the diffusion sheet resistance. A two-level screening experiment with 2³ factorial design was used to evaluate three process variables in eight combination runs. The factors were BF₂ and Ar implantation dose, drive-in temperature and drive-in time. Variance analysis was used to analyze the data and we found that all of the main variables were important for arsenic implanted wafers but only the drive-in temperature factor was important for boron implanted wafers. We also discovered that there was no significant interaction between the factors. For arsenic implanted wafers, which were driven-in at 950°C, the measured sheet resistances were at between 110 and 130 Ω/□ while for wafers which were driven-in at 850°C, the sheet resistances were measured at between 60 and 90 Ω/□. For boron implanted wafers, the measured sheet resistance values were found to be constant at about 30 Ω/□, regardless of drive-in temperature. The experimental data were used in regression equations to model the sheet resistance. By this, we have illustrated how the statistical design of experiments methodology can be used effectively in order to control the process performance