In Situ End Point Detect of Photoresist Developing Using Scanning Spectrometric Technique
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2005-Apr-05
Fatula, J: AUTHOR [+3]
This idea addresses the problem of knowing when a photoresist image has been developed for long enough.
In Situ End Point Detect of Photoresist Developing Using
This idea addresses the problem of knowing when a
photoresist image has been developed for long enough.
Suggested is the
monitoring of the reflection of light
from the surface of the wafer/resist as it is being developed and
monitoring the change in the amplitude of the peaks which represent
the spectral composition of said light. By comparing with a
reference spectrum, and monitoring the rate of change in the
amplitude, the point at which the resist has been developed for the
correct amount of time can be determined.
The change in
the amplitude of the peaks which represent
the spectrum of the reflected light is known to be related to the
resist absorption and will change as the resist develops off the
drawing shows the relative positioning of
fiber optic bundles in an FSI develop station (for example).
provides the light and is held in position by a
glass plate which is placed on top of the puddle of developer on top
of the spinning wafer. (This has the advantage of controlling the
miniscus of developer.) The light source would have to be of a
spectrum that does not expose the resist. Another fiber optic
bundle collects light which is reflected from the surface of the
developing wafer/resist and sends it to a 1024 channel
spectrophotometer. A third fiber optic bundle monitors the light
source and provides a reference spectrum. ...