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Browse Prior Art Database

Method For Nonconformal Polyimide Coating

IP.com Disclosure Number: IPCOM000105345D
Original Publication Date: 1993-Jul-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Pearson, DJ: AUTHOR [+3]

Abstract

A typical fine structure for high-end packaging applications involve similar '1' %% mum copper lines with nominally square cross-section. The inter-line spacing in the fine structure may be ge '1' %% mum. The disclosed technique allows a polyimide (or other polymer) coating that covers the structure non-conformally to significantly reduce the planarization step.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 85% of the total text.

Method For Nonconformal Polyimide Coating

      A typical fine structure for high-end packaging applications
involve similar '1' %% mum copper lines with nominally square
cross-section.  The inter-line spacing in the fine structure may be
ge '1' %% mum.  The disclosed technique allows a polyimide (or other
polymer) coating that covers the structure non-conformally to
significantly reduce the planarization step.

      In the disclosed method, a precursor blend was applied instead
of a single component precursor of polyimide to structure.  The
blend, for example, may be polyamic acid (PAA) and polyamic acid
ester (PAETE) of the same polyimide in a common solvent such as
N-metyl pyrrolidone (NMP).  The preferable composition of the blend
may be 10% of PAETE and 90% of PAA.  The amount of solvent may be
determined by a spin-curve for desired thickness of the coat.

      The resultant film is cured in three steps following the soft
bake process that drives the uncomplexed solvent.  In the first step
the film is annealed at cure temperature 'T' sub 'PAA' to cure the
PAA.  Subsequently, the film is heated to 'T' sub <'PAETE'> gt 'T'
sub <'PAA'> to cure the PAETE.  Finally, the film is ramped to higher
temperature to induce order in polyimide and remove traces of
solvents.

      The resultant coating improves the planarization in two ways:
(i) due to the phase separation of PAA and PAETE during soft bake the
surface roughness at nano-scale facilitating th...