This interface could be used to evaluate 1-D dopant distribution resulting from ion implantation and subsequent drive-in. The base substrate is <100> silicon of either p-type or n-type with a known resistivity. The dopant can be either boron or phosphorus. The dopant distribution resulting from implantation and drive-in can be calculated and plotted.
During the implantation step a known dose of impurity is introduced into silicon. Based on the energy and dose of this process, the range and straggle of the path of ions are estimated from which junction depth and peak concentration can be calculated. The peak concentration happens at the depth indicated by range and the dopant distribution follows a Gaussian distribution. This can be assumed to be true for energies below 200keV which is set as the maximum limit in the energy input.
The dose introduced during implantation is diffused deeper into silicon during the drive-in step till it reaches the desired depth and resistivity. For a given temperature and time of drive-in, the resulting junction depth, sheet resistance and peak concentration can be found out.
The plotter will show separate profile for the implantation step alone and a composite plot of implant and drive-in steps. The depth at which these profiles meet the background concentration of the wafer is the junction depth. Using the crosshair tool this location can be read out from the graph. The concentration at any depth can also be found out from the graph.