Copper to copper bonding by nano interfaces for fine pitch interconnections and thermal applications

dc.contributor.advisor Tummala, Rao R.
dc.contributor.author Jha, Gopal Chandra en_US
dc.contributor.committeeMember Wong, C. P.
dc.contributor.committeeMember P. M. Raj
dc.contributor.department Materials Science and Engineering en_US
dc.date.accessioned 2008-06-10T20:39:00Z
dc.date.available 2008-06-10T20:39:00Z
dc.date.issued 2008-03-06 en_US
dc.description.abstract Ever growing demands for portability and functionality have always governed the electronic technology innovations. IC downscaling with Moore s law at IC level and system miniaturization with System-On-Package (SOP) paradigm at system level, have resulted and will continue to result in ultraminiaturized systems with unprecedented functionality at reduced cost. However, system miniaturization poses several electrical and thermal challenges that demand innovative solutions including advanced materials, bonding and assembly techniques. Heterogeneous material and device integration for thermal structures and IC assembly are limited by the bonding technology and the electrical and thermal impedance of the bonding interfaces. Solder - based bonding technology that is prevalent today is a major limitation to future systems. The trend towards miniaturized systems is expected to drive downscaling of IC I/O pad pitches from 40µm to 1- 5µm in future. Solder technology imposes several pitch, processability and cost restrictions at such fine pitches. Furthermore, according to International Technology Roadmap for Semiconductors (ITRS-2006), the supply current in high performance microprocessors is expected to increase to 220 A by 2012. At such supply current, the current density will exceed the maximum allowable current density of solders. The intrinsic delay and electromigration in solders are other daunting issues that become critical at nanometer sized technology nodes. In addition, formation of intermetallics is also a bottleneck that poses significant mechanical issues. Similarly, thermal power dissipation is growing to unprecedented high with a projected power of 198 W by 2008 (ITRS 2006). Present thermal interfaces are not adequate for such high heat dissipation. Recently, copper based thin film bonding has become a promising approach to address the abovementioned challenges. However, copper-copper direct bonding without using solders has not been studied thoroughly. Typically, bonding is carried out at 400oC for 30 min followed by annealing for 30 min. High thermal budget in such process makes it less attractive for integrated systems because of the associated process incompatibilities. Hence, there is a need to develop a novel low temperature copper to copper bonding process. In the present study, nanomaterials - based copper-to-copper bonding is explored and developed as an alternative to solder-based bonding. To demonstrate fine pitch bonding, the patterning of these nanoparticles is crucial. Therefore, two novel self-patterning techniques based on: 1.) Selective wetting and 2.) Selective nanoparticle deposition, are developed to address this challenge. Nanoparticle active layer facilitates diffusion and, thus, a reliable bond can be achieved using less thermal budget. Quantitative characterization of the bonding revealed good metallurgical bonding with very high bond strength. This has been confirmed by several morphological and structural characterizations. A 30-micron pitch IC assembly test vehicle is used to demonstrate fine pitch patternability and bonding. In conclusion, novel nanoparticle synthesis and patterning techniques were developed and demonstrated for low-impedance and low-cost electrical and thermal interfaces. en_US
dc.description.degree M.S. en_US
dc.identifier.uri http://hdl.handle.net/1853/22588
dc.publisher Georgia Institute of Technology en_US
dc.subject Copper to copper bonding en_US
dc.subject Nanoparticles en_US
dc.subject Fine-pitch interconnections en_US
dc.subject Maskless patterning en_US
dc.subject.lcsh Interconnects (Integrated circuit technology)
dc.subject.lcsh Metal bonding
dc.subject.lcsh Copper
dc.subject.lcsh Microelectronic packaging
dc.title Copper to copper bonding by nano interfaces for fine pitch interconnections and thermal applications en_US
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Tummala, Rao R.
local.contributor.corporatename School of Materials Science and Engineering
local.contributor.corporatename College of Engineering
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