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Electroless Plating Scheme to Hermetically Seal Copper Features

IP.com Disclosure Number: IPCOM000103948D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Carr, J: AUTHOR [+3]

Abstract

Disclosed is a process used to completely encapsulate copper interconnects in a metal jacket, thus improving copper/polyimide adhesion and preventing copper oxidation and corrosion. This process utilizes a selective plating step in conjunction with a chemical-mechanical polishing (CMP) process for defining copper features in a suitable dielectric material (e.g., polyimide or quartz).

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Electroless Plating Scheme to Hermetically Seal Copper Features

      Disclosed is a process used to completely encapsulate copper
interconnects in a metal jacket, thus improving copper/polyimide
adhesion and preventing copper oxidation and corrosion.  This process
utilizes a selective plating step in conjunction with a
chemical-mechanical polishing (CMP) process for defining copper
features in a suitable dielectric material (e.g., polyimide or
quartz).

      CMP normally allows one to encapsulate three out of the four
copper surfaces with a suitable metal liner, typically a transition
metal (such as Cr, Ta, Ti, W, etc) or a transition metal oxide or
nitride (Fig. 1 and Fig. 2).  The top surface is subsequently coated
with a thin layer of an insulator (such as p-e CVD silicon nitride or
silicon carbide).  Due to the large thermal expansion coefficient
mismatch between the copper and these thin dielectric films a stable
hermetic seal is often not formed, resulting in unacceptable
reliability of the copper features.  Further, this thin insulating
layer is typically a material with a high dielectric constant (e.g.,
substantially higher than polyimide) resulting in an increase in the
RC circuit delay.

      As a solution to these problems a selective electroless plating
process was used to deposit a thin metal film on top of the copper
features after CMP, resulting in a completely metal encapsulated
copper structure.  Selective electroless plating involves pl...