Appeal No. 1997-3473
Application No. 08/331,684
paddle 23 and not over bottom pole tip 22, hill region 25
develops in the formation process. Metallic seed layer 33 is
then typically deposited in a uniform thickness, and a
photoresist layer 36 is then spun down onto seed layer 33, and
therefore has a varying thickness, being thinnest at hill
region 25. Photoresist layer 36 is then patterned for top
pole piece 14, and when the patterned area of 36 is washed
away, an opening or mold is formed in layer 36 for pole piece
14. However, because photoresist layer 36 is spun on in
liquid form, it is much thinner at hill region 25 than it is
in the regions above bottom pole tip 22 and bottom pole paddle
23. At hill region 25, layer 36 is insufficient to
effectively act as a mold for top pole piece 14. As can be
seen in prior art Figure 5, top pole piece 14 is higher than
the top surface of layer 36, resulting in the deformation of
pole piece 14 resulting in over plate at 35.
Appellants avoid over plate 35 by using a cavity
insulation layer 64 (shown in Figure 9 at the hill region).
Here, cavity insulation layer 64 provides extra thickness,
effectively raising the level of top pole photoresist layer 66
(layer 36 in Figure 5), relative to that of top pole piece 44
3
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