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Method for anchoring micro-vias to enhance via reliability in substrates

IP.com Disclosure Number: IPCOM000007688D
Publication Date: 2002-Apr-15
Document File: 4 page(s) / 568K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for anchoring micro-vias to enhance via reliability in substrates. Benefits include improved reliability.

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Method for anchoring micro-vias to enhance via reliability in substrates

Disclosed is a method for anchoring micro-vias to enhance via reliability in substrates. Benefits include improved reliability.

Background

              Micro-vias are critical substrate features that are used to interconnect metal layers, enabling signal and power routing.

              Via delamination and via cracking under high-stress conditions are known issues that substrate technology development teams have experienced in all technology generations. When packages are highly stressed, via interconnects start to crack and delaminate, creating an open failure. The risks from via cracking or delamination increase when via sizes are smaller and when filled vias are stacked in multiple substrate layers.

              No conventional robust process exists to ensure via delamination does not occur under high stress. Monitors, such as via pop and temperature shock stressing, help catch the problem but do not eliminate the risk of via delamination. Via reliability is increased by utilizing dielectric material with lower coefficient for thermal expansion (CTE), resulting in reduced via structure stress.

General description

              The disclosed method anchors micro-vias to enhance via reliability in substrates and to avoid via delamination under high-stress conditions. An optimized etching chemistry creates an isotropic anchor at the micro-via bottoms. The chemistry etches the Cu land, creating a concave dip and undercutting the Cu land sideways. The result is a via that holds onto or anchors against the overlaying layer of the dielectric material. Via anchoring improves technologies that are dependant on filled-stacked vias with increased via density.

              The key elements of th...