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Method for low-k ILD protection

IP.com Disclosure Number: IPCOM000101671D
Publication Date: 2005-Mar-16
Document File: 3 page(s) / 58K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for low-k interlayer dielectric (ILD) protection. Benefits include improved functionality, improved reliability, and process simplicity.

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Method for low-k ILD protection

Disclosed is a method for low-k interlayer dielectric (ILD) protection. Benefits include improved functionality, improved reliability, and process simplicity.

Background

      During die-to-substrate assembly, the die and substrate are heated to reflow solder and form controlled collapse chip collect (C4) solder joints. At cool down, internal stress occurs due to the coefficient for thermal expansion (CTE) mismatch between the die and substrate. The stress is generated on the solder joints and passed to the low dielectric constant (low-k) ILD material in the die, resulting in cracking, delamination, and device failure.

 

General description

      The disclosed method is low-k ILD protection by heating the die rapidly using a multiple nanolayer material as the heat source to form solder joints during die-to-substrate assembly.

      After a die is picked and placed on a substrate that has solder bumps and pre-deposited flux, a preformed nanolayer foil is placed on the die backside. Alternatively, the material can be predeposited as backside metallization on the die. When the nanolayer material is activated, it generates enough heat by its self-propagating reactions to heat up the die instantly and melt the solder on the substrate to form solder joints. Since the whole process takes less than a second, the substrate is not heated up, which reduces or eliminates the CTE mismatch between the die and substrate. The stress on the solder joints is greatly reduced and the low-K ILD in the die is protected from damage.

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to reducing or eliminating the stress on the low-k ILD material

•             Improved functionality due by locally heating the die through the heat generated from the self-propagatin...