Method of and apparatus for measuring flatness of semiconductor wafers that have not been subjected to donor-killer treatment
US6002262A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 19, 1996 |
| Grant date | Dec 14, 1999 |
| Priority date | — |
| Expiry date | Jul 19, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A halogen lamp of illuminance 150,000 lux or greater and wavelength 1129 nm or less is provided in the vicinity of a probe of an electrostatic capacitative flatness measuring instrument, and illuminates the surface of the wafer under measurement. When the light enters into the bulk, it is converted to excitation energy, which converts the valence electrons of the silicon into conduction electrons. Since the free electrons or positive holes generated from the silicon are overwhelmingly more than the dopant or oxygen donors, the wafer exhibits characteristics similar to metal. That is, electrons are uniformly distributed in all parts of the wafer. When, in this state, the upper face and lower face of the wafer are measured, the relative dielectric constant is fixed in all locations, so all the changes in electrical amount can be measured as changes in distance between the wafer and the probe. Thus, the accurate flatness measurement for semiconductor wafers that have not been subjected to donor-killer treatment can be achieved by using an electrostatic capacitative flatness measuring instrument.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.