Ion implantation and drive-in of dopants in silicon

wfr         type of the silicon or epi substrate, select n or p type
res         resistivity of silicon or epi substrate in ohm-cm
dop        dopant type, select boron or phosphorus
eng        energy of implant in keV
dose      implant dose in atoms/cm2
temp      temperature of drive-in in °C
time       time of drive-in in min
sel         number denoting the selected result.
              Use 1 for peak concentration, 2 for junction depth and 3 for sheet resistance


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.


-Oxidation and implanting through oxide are not considered. But oxide has similar stopping power of ions like silicon.
-The implant beam is assumed to be directed at a small angle to the <100> silicon surface to reduce effects of channeling.
-The distribution of dopants are considered to be Gaussian which could be assumed to be true for low implant energy.
-Rapid thermal processing is not modeled.
-High concentration diffusion is not considered.
-The variation in the diffusion profile due to point defects are not considered.
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