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The Use of Contact Pad Structure With Diffusion Barrier Metal Column Surrounding the Fine Line Interconnect

IP.com Disclosure Number: IPCOM000038700D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Kwok, TY: AUTHOR [+2]

Abstract

This publication describes a technique to improve the electromigration life-time by reducing extrusion-shorts in fine line interconnects and electrical opens on anode contact pads. In the Al-Cu fine line interconnects, electromigration-induced failure mainly comes from void-opens because it occurs at an earlier time than extrusion-shorts. By using the A1-transition metal intermetallic sandwich layered structure (e.g., A1-Cu/Hf/A1-Cu) in AMET fine line interconnects, the electromigration-induced void-open failure mechanism has been improved due to the microstructure modification and the redundant A1-intermetallic layer. As a result, the extrusion-short becomes the dominated mechanism in the fine line interconnects.

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The Use of Contact Pad Structure With Diffusion Barrier Metal Column Surrounding the Fine Line Interconnect

This publication describes a technique to improve the electromigration life-time by reducing extrusion-shorts in fine line interconnects and electrical opens on anode contact pads. In the Al-Cu fine line interconnects, electromigration- induced failure mainly comes from void-opens because it occurs at an earlier time than extrusion-shorts. By using the A1-transition metal intermetallic sandwich layered structure (e.g., A1-Cu/Hf/A1-Cu) in AMET fine line interconnects, the electromigration-induced void-open failure mechanism has been improved due to the microstructure modification and the redundant A1- intermetallic layer. As a result, the extrusion-short becomes the dominated mechanism in the fine line interconnects. It has been found that the extrusion- short occurs at the time when there is a large A1-Cu depletion area in the cathode contact pad. In addition, electrical-open failure is also observed near and in the anode contact pad. All these indicate that the contact pad serves as the source or the sink for A1-Cu being transported along the fine line interconnect out of or into the connect pad. The Cr/Cu/Au diffusion barrier metals used in BLM provide good electromigration resistance (Fig. 1). Thus, the contact pad structure can be designed in such a way (Fig. 2) that allows a diffusion barrier metal column (e.g., Cr/Cu/Au in BLM, or Cr+CrOx, or Ti-W) in...