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Wafer Coating Method

IP.com Disclosure Number: IPCOM000099396D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Calmbach, S: AUTHOR

Abstract

Coating wafers in pairs, with the wafer surfaces being covered with photoresist or protective lacquer according to the principle of aquaplaning, saves a considerable amount of raw material and leads to increased efficiency.

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This is the abbreviated version, containing approximately 73% of the total text.

Wafer Coating Method

       Coating wafers in pairs, with the wafer surfaces being
covered with photoresist or protective lacquer according to the
principle of aquaplaning, saves a considerable amount of raw material
and leads to increased efficiency.

      A comparatively small quantity of resist is applied to the top
of a horizontally positioned stationary wafer 1 (Fig. 1).  In
response to the tension existing on its surface, the resist spreads
to such an extent that a convex puddle 2 of about 1 to 1.5 mm
height (depending upon the viscosity) is formed.  Onto the first
wafer 1, a second wafer 3 is lowered at an angle a face-down to
contact the resist puddle (Fig.  2).  As the second or top-most wafer
continues to be lowered, the aquaplaning effect causes the resist
puddle to spread, so that the entire wafer is covered with a liquid
film 2' of tolerable thickness.  During this process, the air in the
wedge-shaped gap 4 between wafers 1, 3 is expelled by the uniformly
spreading liquid film 2', preventing the inclusion of air.  The two
wafers are made to contact each other by slowly rotating one of them
to obtain a uniform liquid film (Fig. 3).

      Wafers 1, 3 (Fig. 4) are radially separated parallel to each
other.  In this step, the wafer surfaces slide on liquid film 2'
under machine guidance.  The adhesion forces of the liquid ensure
that the two front surfaces of the wafers stay uniformly wetted.  The
reduced (viscosity- dependent) resist quanti...