Wearout Reliability and Intermetallic Compound Diffusion Kinetics of Au and PdCu Wires Used in Nanoscale Device Packaging

C L Gan,T Kwuanjai,U Hashim,F C Classe,E K Ng,B L Chan

doi:10.1155/2013/486373

C L Gan, T Kwuanjai + Show 4 more

Open Access

https://doi.org/10.1155/2013/486373

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Abstract

Wearout reliability and diffusion kinetics of Au and Pd-coated Cu (PdCu) ball bonds are useful technical information for Cu wire deployment in nanoscale semiconductor device packaging. This paper discusses the HAST (with bias) and UHAST (unbiased HAST) wearout reliability performance of Au and PdCu wires used in fine pitch BGA packages. In-depth failure analysis has been carried out to identify the failure mechanism under various wearout conditions. Intermetallic compound (IMC) diffusion constants and apparent activation energies (Eaa) of both wire types were investigated after high temperature storage life test (HTSL). Au bonds were identified to have faster IMC formation, compared to slower IMC growth of PdCu. PdCu wire was found to exhibit equivalent or better wearout reliability margin compared to conventional Au wire bonds. Failure mechanisms of Au, Cu ball bonds post-HAST and UHAST tests are been proposed, and both Au and PdCu IMC diffusion kinetics and their characteristics are discussed in this paper.

Highlights

In recent years, Cu wire bonding has been widely adopted in recent nanoelectronic packaging due to its conductivity, material properties, and cost effectiveness
Wearout reliability of Au and Pd-coated Cu (PdCu) ball bonds were tted to the Weibull distribution. e characteristic values of Weibull plots for both Au and PdCu ball bonds are tabulated in Table 1, covering HAST and UHAST
In Au and PdCu wire bonding evaluations on 110 nm devices, we have successfully characterized the wearout reliability margins for HAST and UHAST and determined the diffusion kinetics of both wire types used in nanoscale semiconductor packaging

Summary

Introduction

Cu wire bonding has been widely adopted in recent nanoelectronic packaging due to its conductivity, material properties, and cost effectiveness. It is crucial to conduct knowledge-based reliability studies and understand the wearout reliability models [10] and its associated failure mechanism with Cu wire bonding in nanoelectronic device packaging which will ensure successful Cu wire bonding deployment in high pin count and nanoscale devices. Some researchers have investigated and compared the IMC diffusion kinetics and calculated the apparent activation energy for Cu and Au ball bonds IMCs a er high temperature aging [13,14,15,16,17,18,19,20,21] and predict EEaa for isothermal Cu wire interfacial fracture [22]. T 2: Summary of IMC diffusion kinetics and activation energies comparing Au and PdCu ball bonds used in 110 nm device packaging. HTSL aging stress is used to investigate IMC diffusion kinetics and determine the apparent activation energy (EEaa) for IMC growth. e values of EEaa and the diffusion constant DDoo are compared to values from previous studies [13,14,15,16,17,18,19,20,21]

Experimental

Results and Discussion

Diffusion Kinetics of Au and PdCu Ball Bonds

Conclusion