Method of correction for wafer crystal cut error in semiconductor processing
View Patent ↗The present invention is directed to accounting for crystal cut error data in ion implantation systems, thereby facilitating more accurate ion implantation. One or more aspects of the invention also consider possible shadowing effects that can result from features formed on the surface of a wafer being doped. According to one or more aspects of the invention, crystal cut error data and optionally feature data also are periodically fed forward in one or more ion implantation stages or systems to ascertain how to re-orient the ion beam with respect to the workpiece to achieve desired implantation results.
1. An ion implantation system comprising:
an ion source for generating ions;
a beamline assembly for generating an ion beam from the ions generated by the ion source and directing the ions along a path of travel;
an endstation for positioning a workpiece relative to the path of travel so that ions traveling in the ion beam impact the workpiece at select locations; and
a processor that assists with obtaining implantation data relevant to determining a relative orientation between the ion beam and the surface of the workpiece to be impacted thereby.
2. The system of claim 1 , wherein the implantation data includes data relating to the orientation of the mechanical surface of the workpiece relative to the ion beam directed at the surface of the workpiece to implant ions within select locations of the workpiece.
3. The system of claim 2 , wherein the implantation data includes data regarding one or more features formed upon the surface of the workpiece, including respective spacings existing between the features, the processor determining respective degrees of shading likely to result during ion implantation given the orientation data and the feature data, and what adjustments, if any, should be made to the relative orientation between the ion beam and the surface of the workpiece to adequately mitigate shading.
4. The system of claim 2 , wherein the implantation data includes cut error data relating to a relative orientation between the surface of the workpiece and a lattice structure of the workpiece, the processor determining the severity of channeling likely to result from the ion implantation given the orientation data and the cut data, and what adjustments, if any, should be made to the relative orientation between the ion bean and the surface of the workpiece to adequately mitigate channeling.
5. The system of claim 3 , wherein the implantation data further includes cut error data relating to a relative orientation between the surface of the workpiece and a lattice structure of the workpiece, the processor also determining the severity of channeling likely to result from the ion implantation given the orientation data and the cut data, and what adjustments, if any, should be made to the relative orientation between the ion bean and the surface of the workpiece to adequately mitigate channeling.
6. The system of claim 5 , wherein, to determine what adjustments, if any, should be made to the relative orientation between the ion bean and the surface of the workpiece to adequately mitigate shading and channeling, the processor also
considers respective effects that different degrees of channeling and shadowing can have on predefined performance criteria;
compares these effects to predefined acceptable levels; and
assigns a weight to the different degrees of channeling and shadowing based upon the severity of the respective effects and the acceptable levels.
7. The system of claim 3 , wherein the feature data includes a width of one or more of the features.
8. The system of claim 4 , wherein the cut error data is obtained utilizing at least one of Rutherford backscattering, x-ray diffraction and crystallography.