Browse Prior Art Database

Multilayer Dielectric Mask

IP.com Disclosure Number: IPCOM000108432D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 58K

Publishing Venue

IBM

Related People

Lankard, J: AUTHOR [+3]

Abstract

The etch rate ratio between multilayer dielectric mask materials (SiO2 and HfO2) is too low to use standard resist materials to mask the unetched parts of the mask. It is proposed to use the multilayer dielectric mask sketched in figure 1 to solve this problem. A top layer of Al2O3 1 would be an RIE mask. Ordinary phototresist 2 would be spun on and patterned by standard means to give the structure sketched in figure 1. Then, ion beam milling of the part would cut through the Al2O3 material 1 and part way into the SiO2 3 and HfO2 layers 4. The part could then be transferred to an RIE machine, and the etching would continue using low voltage ions which would have no sputtering component in the etching.

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Multilayer Dielectric Mask

      The etch rate ratio between multilayer dielectric mask
materials (SiO2 and HfO2) is too low to use standard resist materials
to mask the unetched parts of the mask.  It is proposed to use the
multilayer dielectric mask sketched in figure 1 to solve this
problem.  A top layer of Al2O3 1 would be an RIE mask.  Ordinary
phototresist 2 would be spun on and patterned by standard means to
give the structure sketched in figure 1.  Then, ion beam milling of
the part would cut through the Al2O3 material 1 and part way into the
SiO2 3 and HfO2 layers 4.  The part could then be transferred to an
RIE machine, and the etching would continue using low voltage ions
which would have no sputtering component in the etching.  In this
mode, we have shown that the Al2O3 material 1 does not etch at a
significant rate, hence the SiO2 and HfO2 material would be etched
away down to the Al2O3 material 5 on the substrate 6. The part could
be overetched without touching the Al2O3 material 5, so the bottom of
the etched out material would be flat with no "hills" or "valleys" to
scatter light and act as "opaque" defects.

      In addition, the top layer 1 of Al2O3 could be made one half an
optical wavelength thick.  If the wavelength was in the visible
region, say, at 633 nm, the reflectivity of the Al2O3 film on top of
the multilayer dielectric film would be about 10%, and the mask would
be more visible because the contrast between the reflectivity of th...