Patent ID: 6225136
Filing Date: 2001-05-01
Classification: H01L

Abstract:
A method of preparing a series of contaminated silicon wafers by controllably adding at least one contaminant to a plurality of silicon wafers, the method comprising:providing a first wafer having a surface with a surface charge;providing a second wafer having a surface with a surface charge;providing a first solution containing a first known concentration of the at least one contaminant and having a first pH;providing a second solution containing a second known concentration of the at least one contaminant and having a second known pH, the second known concentration of the at least one contaminant being substantially the same as the first known concentration of the at least one contaminant;applying the first solution to the surface of the first wafer;applying the second solution to the surface of the second wafer;allowing the first and second solutions to remain on the surfaces of the first and second wafers for a predetermined period of time, so that the surface charges of the surfaces are at least partially controlled by the pHs of the solutions, and so that the at least one contaminant adsorbs to the surfaces in surface concentrations at least partially determined by the surface charges of the surfaces; andremoving the first and second solutions while leaving the adsorbed at least one contaminants on the surfaces, such that the first wafer has a first surface concentration of contaminants, and the second wafer has a second surface concentration of contaminants that is different from the first surface concentration of contaminants.