Wednesday, November 29, 2006

US Patent 7141179 - Nanocavity Detection

This patent supposedly teaches a method of detecting cavities sized below 0.1 nanometer, which is slightly less than the diameter of atoms. I might be wrong but it seems to me that the U.S. application makes the mistake of confusing 0.1 nanometer with 0.1 micrometer (several references in the specification reciting 0.1 nanometer and 1000 Angstroms in the alternative seem to support this contention.) Nevertheless the patent teaches enhancing small scale defect detection so as to be observable by conventional techniques such as optical microscopy. Claim 1 reads:

1. A method of detecting a defect cavity sized below 0.1 nanometer with commonly used low-sensitivity monitoring equipment, comprising: a) selecting a wafer from a lot; b) applying a treatment to the selected wafer, the treatment removing a 1 to 100 nanometer thick portion of the selected wafer and enhancing a size of a defect cavity in the wafer to above 0.1 nanometer; and c) applying a 1 to 50 nanometer thick metallic layer on the treated wafer: d) scanning the wafer for cavity defects using 0.1 nanometer detection threshold monitoring equipment.