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Browse Prior Art Database

Robust Method using Simple Unit Processes for Thin Film Cu Polyimide Packaging Structures

IP.com Disclosure Number: IPCOM000107635D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 100K

Publishing Venue

IBM

Related People

Farooq, MS: AUTHOR [+5]

Abstract

This invention proposes a method using simple and well-proven unit processes for building thin film packaging structures. It uses optical lithography along with photoresist to define the pattern, low stress polyimides as the dielectric, electroplating for metallization, and micromilling for planarization. The result is a robust process with dense line patterns and excellent electrical performance.

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Robust Method using Simple Unit Processes for Thin Film Cu Polyimide Packaging Structures

       This invention proposes a method using simple and
well-proven unit processes for building thin film packaging
structures.  It uses optical lithography along with photoresist to
define the pattern, low stress polyimides as the dielectric,
electroplating for metallization, and micromilling for planarization.
The result is a robust process with dense line patterns and excellent
electrical performance.

      The method is schematically shown in Figures 1 through 6.
These figures represent a typical cross-section, normal to the
substrate surface.

      Figure 1: The Cu-polyimide thin film is built on polished glass
ceramic substrates.

      Figure 2: The first step is to sputter 0.15 microns of Cr-Cu.
The first wiring level is defined in photoresist (P/R).

      Figure 3: The wiring level is formed by electroplating Cu to
the required final thickness through the mask created in the P/R, and
this P/R is subsequently stripped.

      Figure 4:  The next step is to apply another layer of P/R to
define the vias.  The studs are then formed by electroplating Cu to
thickness greater than the final required stud thickness.

      Figure 5: The P/R is stripped, the seed layer etched and the
remaining structure capped by plating with electroless cobalt.

      Figure 6: Polyimide is then applied to cover the entire wiring
level and stud structure.  Micr...