Wafer shape accuracy using symmetric and asymmetric instrument error signatures
US6594002B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 31, 2001 |
| Grant date | Jul 15, 2003 |
| Priority date | — |
| Expiry date | Jul 31, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/0002
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method to determine the systematic error of an instrument that measures features of a semiconductor wafer includes the following sequential steps. Collecting sensor data from measurement runs on front and back surfaces of a wafer while the wafer is oriented at different angles to the instrument for each run, yielding a front data set and a back data set for each angle. Then organizing the data in each set into a wafer-fixed coordinate frame. Reflecting all back surface data about a diameter of the wafer creates a reflected back data set. Subtracting the reflected back data from the front data for each wafer angle, and dividing the result by two, yields an averaged wafer shape for each load angle. Adding the reflected back data to the front data and dividing the result by two, yields an instrument signature for each load angle. The symmetric corrector is calculated by taking the average over all instrument signatures at each load angle. The symmetric corrector is successively rotated to the same angle as a front shape measurement and subtracted, yielding a calibrated wafer data set. A wafer mean is computed by averaging these calibrated wafer shape measurements. When the wafer mea…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.