Browse Prior Art Database

Spray Develop End-Point-Detection System

IP.com Disclosure Number: IPCOM000100829D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Babinski, JP: AUTHOR

Abstract

By strobing to sample light reflection only at a specific planar region of a spinning product wafer, monochromatic light interference sensing for end-point detection of photoresist development is significantly improved. Angular position detection and electronics to strobe either input light or output signal of a conventional interference end-point sensor are added to standard spin-spray equipment to achieve the benefit.

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Spray Develop End-Point-Detection System

       By strobing to sample light reflection only at a specific
planar region of a spinning product wafer, monochromatic light
interference sensing for end-point detection of photoresist
development is significantly improved.  Angular position detection
and electronics to strobe either input light or output signal of a
conventional interference end-point sensor are added to standard
spin-spray equipment to achieve the benefit.

      A signal of the type shown in Fig. 1 is the result of detection
of reflection intensity Y and development time X of photoresist being
developed on a planar region of a spinning wafer.  This solid curve
may be generated by continuous light input and reflection measurement
on a non-product, planar wafer or by accepting reflection data only
from a planar region or regions of a product wafer and connecting the
data points. Maxima in the curve are generated at photoresist
thicknesses, resulting in constructive interference of the reflected
monochromatic light, e.g. at thicknesses of multiples of the half
wavelength of the light.  Minima occur similarly at half wavelength
thicknesses apart as the photoresist is developed away.  End point of
development is detected when reflected light intensity Y becomes
constant with development time X.

      Referring to Fig. 2, product wafers which offer planar area 12
only in a small region at a radius other than near the center of
wafer 10 have changing...