In-situ monitoring of polishing pad wear
US5934974A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 5, 1997 |
| Grant date | Aug 10, 1999 |
| Priority date | — |
| Expiry date | Nov 5, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/0002
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
An in-situ sensor measures polishing pads during chemical mechanical polishing. From the measurements, polishing pads can be identified as worn out or unevenly worn and replaced. Scheduling maintenance according to current measurements, rather than according to statistical predictions, minimizes down time for maintenance and still prevents use of worn out or unevenly worn polishing pads. Alternatively, a tool is reconfigured according to the polishing pad measurements. Reconfiguring the tool can prolong pad life and improve polishing performance. One embodiment of the invention includes a non-contact sensor such as a laser sensor that directs an incident beam at a target area and determines a distance to a reflection point by triangulation of incident and reflected beams. As polishing pads wear, distances to the reflection points increase. Movement of the polishing pads and the sensor during polishing causes the in-situ sensor to measure portions of the polishing pads that are along a zigzag trajectory. When the frequency of the sensor's motion is a multiple of the frequency of revolution of the polishing pads, the sensor retraces the same trajectory after one or more revolutions o…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.