Appeal 2007-2494
Application 10/161,134
{Figure 2 of Mason is said to show a substrate with oxide, nitride, optical
assist, and photoresist layers deposited thereon.}
[19] According to Mason, by reducing optical interference between the
photoresist layer 22 and the substrate 10, the optical assist layer 16
reduces or eliminates foot formation during photoresist patterning, as
depicted in Figure 3 below (Mason at 2-5, ¶¶ 2-4 and 7).
{Figure 3 of Mason is said to show a photoresist pattern lacking foot
formation.}
[20] The optical assist layer 16 is transparent or semitransparent and has a
different refractive index from the nitride layer (Mason at 3-4, ¶¶ 4
and 6).
[21] Suitable materials for forming the optical assist layer include
tetraethyloxysilane (TEOS), non-TEOS silicon dioxide, aluminum
oxide, zinc oxide and borophosphosilicate glass (BPSG) (Mason at 4-
5, ¶ 6).
[22] The thickness of the optical assist layer 16 is said to depend on the
thickness of the underlying nitride 14 and oxide 12 layers and the size
of the refractive index (Mason at 6, ¶ 8).
[23] The photoresist pattern 24 is used as a mask and underlying optical
assist 16, nitride 14 and oxide 12 layers are etched to create a "hard
mask" pattern that matches the photoresist pattern 24, as depicted in
Figure 4 reproduced below (Mason at 5, ¶ 7).
8
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Next
Last modified: September 9, 2013