Long term isothermal reliability of copper wire bonded to thin 6.5 &amp;#x00B5;m aluminum

Francis²,

Chan³

et al. 2013

Gold Bull

Wire bonding is the predominant mode of interconnection in microelectronic packaging. Gold wire bonding has been refined again and again to retain control of interconnect technology due to its ease of workability and years of reliability data. Copper (Cu) wire bonding is well known for its advantages such as cost-effectiveness and better electrical conductivity in microelectronic packaging. However, extended reliabilities of Cu wire bonding are still unknown as of now. Extended reliabilities of Au and Pd-coated Cu (Cu) ball bonds are useful technical information for Au and Cu wire deployment in microelectronic packaging. This paper discusses the influence of wire type and mold compound effect on the package reliability and after several component reliability stress tests. Failure analysis has been conducted to identify its associated failure mechanisms after the package conditions for Au and Cu ball bonds. Extended reliabilities of both wire types are investigated after unbiased HAST (UHAST), temperature cycling (TC), and high-temperature storage life test (HTSL) at 150, 175, and 200°C aging temperatures. Weibull plots have been plotted for each reliability stress. Obviously, Au ball bond is found with longer time to failure in unbiased HAST stress compared to Cu ball bonds for both mold compounds. Cu wire exhibits equivalent package and or better reliability margin compared to Au ball bonds in TC and HTSL tests. Failure mechanisms of UHAST and TC have been proposed, and its mean time to failure (t 50 ), characteristic life (t 63.2 , η), and shape parameter (ß) have been discussed in this paper. Feasibility of silver (Ag) wire bonding deployment in microelectronic packaging is discussed at the last section in this paper.

Section: High-temperature Storage Lifesupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Extended reliability of gold and copper ball bonds in microelectronic packaging

Francis²,

Chan³

et al. 2013

Gold Bull

“…The typical wearout failure mechanism of Cu ball bond is CuAl micro-cracking and Kirkendall voiding is observed in Au ball bond after HTSL aging tests. These wearout failures are similar to previous works done (Classe and Gaddamraja, 2011). Hence it can be concluded that the Au atom diffuses much faster than Cu atoms in Al metallization and induce Kirkendall voiding after aging tests.…”

Section: Apparent Activation Energy (E Aa ) For Au and Cu Ball Bondssupporting

confidence: 88%

“…The apparent activation energy, E aa can be calculated from the gradient of the plot ln T versus 1/kT. Table III tabulates the results of E aa and typical wearout failure mechanisms of Au and Cu ball bond after HTSL stress of our studies compare to previous engineering works conducted by researchers (Classe and Gaddamraja, 2011). In our evaluation, the values obtained for E aa (in eV) of Au ball bond is similar to value published in JEDEC JEP112 while E aa of Cu ball bond is slightly higher than bare Cu ball bond.…”

Section: Apparent Activation Energy (E Aa ) For Au and Cu Ball Bondsmentioning

confidence: 88%

Superior performance and reliability of copper wire ball bonding in laminate substrate based ball grid array

Microelectronics International

Classe

Hashim

2013

Purpose -The purpose of this paper is to provide a systematic method to perform long-term reliability assessment of gold (Au) and copper (Cu) ball bonds in fineline ball grid array package. Also with the aim to study the apparent activation energies (E aa ) and its associated wearout mechanisms of both Au and Cu wire in semiconductor device packaging. This paper discusses the influence of wire type on the long-term reliability and mechanical performance after several component reliability stress tests. Design/methodology/approach -A fineline ball grid array (FBGA) package with Cu and Au wire bonds was assembled with green molding compound and substrate. Samples are subjected for long-term high temperature storage bake test at elevated temperatures of 1508C, 1758C and 2008C. Long-term reliability plots (lognormal plots) are established and E aa of both ball bonds are determined from Arrhenius plots. Detailed failure analysis has been conducted on failed sample and HTSL failure mechanisms have been proposed. Findings -Reliability results show Au ball bond in FBGA package is observed with higher hour-to-failure compared to Cu ball bonds. The E aa value of high temperature storage life (HTSL) reliability for Au ball bond is lower than Cu ball bond. Typical HTSL failure mechanism of Au ball bond is induced by micro-voiding and AuAl intermetallic compound (IMC) micro-cracks while CuAl IMC micro-cracking (induced by Cl 2 corrosion attack and microcracking) caused wearout opens in Cu ball bond. These test results affirm the test-to-failure data collected is a useful method for lifetime prediction and E aa calculation. Practical implications -The paper reveals higher reliability performance of Cu ball bond in FBGA flash memory package which can be deployed in flash memory FBGA packaging with optimised package bill of materials. Originality/value -The test-to-failure methodology is a useful technique for wearout reliability prediction and E aa calculation.

“…Gan et al [12] characterized the wearout reliability on Au and Pd-coated Cu ball bonds used in �neline �GA �ash memory packages. 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 aa for isothermal Cu wire interfacial fracture [22]. In the �rst part of this study, Au and Pd-coated Cu bonds reliability are investigated under biased HAST and UHAST; resulting wearout reliability plots are generated, and…”

Section: Introductionmentioning

confidence: 99%

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

Journal of Nanomaterials

Chan

et al. 2013

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.