Measuring the Resistance of Very Thin Layers
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-26
The proposed method is based on the four-point method for Rs measurement and uses a very thin oxide layer on top of the implanted layer to be characterized, so that the points of the needles penetrate the center of the thin layer to a particular depth. The parameters of implantation in the dose range of about - 1 E 13 cm-2 are controlled by measuring the layer resistance of the implanted wafer after an activation anneal step. The dose range, for which this measuring method is suitable, may be extended to about - 2 E 11 cm-2, if extremely low-doped substrates of about 100 to 400 ohm cm are used and surface states are prevented from forming by cleaning the surface following the activation anneal step. However, the dose range may only be extended for lower doses if the implantation energy for boron is, for instance, - 50 keV.