Apparatus for monitoring the dry etching of a dielectric film to a given thickness in an integrated circuit
US5658418A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 1995 |
| Grant date | Aug 19, 1997 |
| Priority date | — |
| Expiry date | Sep 29, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J37/32972
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Detecting the desired etch end point in the dry etching of a structure that includes a dielectric film formed onto a substrate down to a given thickness Ef. The structure is placed in the chamber of an etching equipment provided with a view-port. A light source illuminates a portion of the structure at a normal angle of incidence through the view-port. The light contains at least two specified wavelengths (L1, L2) whose value is greater than a minimum value equal to 4*N*e (wherein N is the index of refraction and e the thickness error of the dielectric). The reflected light is applied to spectrometers tuned to each specified wavelength, for converting the reflected light into interference signals that are processed and analyzed in a dedicated unit to generate primary signals (S1, S2). An analysis of the primary signals is performed after a predetermined delay. For each wavelength, a pre-selected extremum of the primary signal is detected and a predetermined number of extrema is counted. The counting stops when the last extremum just before Ef is reached. As a result, the distance D between the last extremum and the given thickness is now determined. The etch rate ER is also measure…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.