Use of Harsh Wafer Probing to Evaluate Traditional and CUP Bond Pad Structures

Hunter, Stevan; Martínez, J. M.; Salas, Cesar; Salas, Marco; Schofield, Jason; Sheffield, Steven; Wilkins, Kyle; Rasmussen, Bryce; Ruud, Troy; McBride, Vail

doi:10.1109/tcpmt.2012.2236384

Cited by 13 publications

(7 citation statements)

References 1 publication

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“…This probe cracking trend closely matches trends reported from our previous harsh probing experiments [1]. High MT(-1) pattern density pads are the weakest, showing the most ripple and cracking when harshly probed.…”

Section: Figure 12 Fraction Of Pads Cracked In Probing Vs Pattern Den...supporting

confidence: 89%

“…Cracks initiate due to stress from probing, bonding, or both. Our previous work has shown much about the mechanisms of cracking, characteristics of cracks from harsh probing and wirebonding, and how to design pad structures to prevent cracks [1][2][3][4]. Cracking tendency of pad structures is witnessed by observing the "ripple effect" in the destructive "cratering test", where wirebonds and pad Al are removed to permit inspection by optical microscope.…”

Section: Introductionmentioning

confidence: 99%

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Use of Wire Bonding to Study Bond Pad Damage from Wafer Probe

Hunter

Clark

Hornberger

et al. 2012

International Symposium on Microelectronics

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Harsh wafer probing and harsh wire bonding have been used in previous work by our group to study cracking and ripple effect on various bond pad designs in technologies having aluminum (Al) alloy based metallization in SiO2 dielectric. One outcome of the previous experimentation is the confirmation that cracks due to wafer probe may not be visible even in a careful cratering test. Probing stress can bend the top SiO2 of the pad downwards, causing high tensile stress to the underside of the film. Cracks initiating in this region easily go undetected in routine monitor procedures, unless they propagate to the top surface and break the barrier film above. Latent probing cracks can result in reliability issues for circuit under pad (CUP) bond pad designs. A typical probe crack in a CUP pad's top SiO2 layer, detected in a cratering test, may actually be accompanied by one or more hidden cracks at the bottom of the film, which may only be detected in a focused ion beam (FIB) cross section. This study uses harsh probing to create cracks in various bond pad test structures and then follows them through the wirebond process, including harsh bonding experiments. Previously undetected probe cracks may be enhanced, lengthened, and made easier to detect in wirebond monitoring and in a cratering test after wirebond. Cracks due to wirebond have different characteristics than probe cracks. Distinguishing features of both crack types are compared after bonding. Monitoring of the ripple effect in both probe and bond helps to predict and track bond pad cracking tendencies. Methods to reduce cracking from both probe and bond are reviewed.

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Section: Figure 12 Fraction Of Pads Cracked In Probing Vs Pattern Den...supporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Use of Wire Bonding to Study Bond Pad Damage from Wafer Probe

Hunter

Clark

Hornberger

et al. 2012

International Symposium on Microelectronics

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“…Several prior studies explored the failure mechanism of ILD crack in copper wire bonding. Through mechanical simulation and modeling, different wafer structures can impact ILD crack (Wang et al, 2007;Hunter et al, 2011). In the study of C40 wafer on BGA package, proper wire bonding parameters were required to avoid the ILD crack (Liu et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Improvement of inter layer dielectric crack for LQFP C90FG wafer technology devices in copper wire bonding process

Wu¹,

Ye²,

Zhang³

et al. 2021

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Purpose This paper aims to investigate the root causes of and implement the improvements for the inter layer dielectric (ILD) crack for LQFP C90FG (CMOS90 Floating Gate) wafer technology devices in copper wire bonding process. Design/methodology/approach Failure analysis was conducted including cratering, scanning electron microscopy inspection and focus ion beam cross-section analysis, which showed ILD crack. Root cause investigation of ILD crack rate sudden jumping was carried out with cause-and-effect analysis, which revealed the root cause is shallower lead frame down-set. ILD crack mechanism deep-dive on ILD crack due to shallower lead frame down-set, which revealed the mechanism is lead frame flag floating on heat insert. Further investigation and energy dispersive X-ray analysis found the Cu particles on heat insert is another factor that can result in lead frame flag floating. Findings Lead frame flag floating on heat insert caused by shallower lead frame down-set or foreign matter on heat insert is a critical factor of ILD crack that has never been revealed before. Weak wafer structure strength caused by thinner wafer passivation1 thickness and sharp corner at Metal Trench (compared with the benchmarking fab) are other factors that can impact ILD crack. Originality/value For ILD crack improvement in copper wire bonding, besides the obvious factors such as wafer structure and wire bonding parameters, also should take other factors into consideration including lead frame flag floating on heat insert and heat insert maintenance.

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“…To avoid damaging the pads on the IC device during the wafer test procedure, it is necessary to limit the contact force and scrub mark length in accordance with the material and dimensions of the pad. Hunter et al [9] used a cantilever probe to conduct the probing test. The experiment observations confirmed that overdrive dominates in causing cracks, while 2156-3950 © 2014 IEEE.…”

Section: Introductionmentioning

confidence: 99%

An Experimental and Numerical Investigation Into Wafer Probing Parameters Based on Thin Wafer Breaking Strength

Liu

Chen

Chang

et al. 2015

IEEE Trans. Compon., Packag. Manufact. Technol.

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Mechanical contact caused using excessive probe force produces an oversized scrubbing mark that may result in damage to the die pad and the silicon chip breaking for thin wafer. Therefore, investigating the relationship between the wafer thickness and the limited breaking stress of the wafer, and applying this relationship as a basis for establishing suitable design rules for a multilayer needle layout are crucial. In this paper, two experimental techniques, three-point-bending test and ball-on-ring, were setup and carried out to measure the forcedisplacement relation of various wafer thicknesses (100-25 µm). The results from the testing then coupled with finite-element analysis to reverse finding the breaking stress/strain as a function of wafer thickness. In addition, experimental setup with a single tungsten needle probe contact with Al pad were employed to investigate the relations between the overdrive, beam length, and scrub mark length. A 3-D computational probing simulation model was developed and verified against the experimental data. The model is then used to examine the effects of the beam length, overdrive distance (OD), and shooting angle on the maximum stress induced within the wafer. Finally, a four-layer probe card needle shape design has been demonstrated as a practical application example; it is shown that for a wafer thickness of 25 µm and an OD of 60 µm, the allowable shooting angles of a four-layer needle probe card are as follows: 1500 µm and 0°-4°(Layer 1); 2100 µm and 0°-9°(Layer 2); 3500 µm and 0°-15°(Layer 3); and 4000 µm and 0°-15°(Layer 4).Index Terms-Finite-element method (FEM), thin wafer strength, wafer probing test. . His current research interests include multiscale computational methods, electronic packaging failure modes analysis, microforce testing methods, and structural design in precision machines.Zi-Hau Chen received the B.S. degree from Chung Hua University, Hsinchu, Taiwan, in 2008. He is currently pursuing the Ph.D. degree with the His current research interests include finiteelement simulation, mechanical modeling for electronic package and precision machine tools, and microforce testing methods. Chi-MinChang received the B.S. degree from Cheng Kung University, Tainan, Taiwan, in 2003, and the Ph.D. degree in mechanical engineering from National Chung Cheng University, Chiayi, Taiwan, in 2011.His current research interests include TIM evaluation, miniature specimen testing methods, and epoxy probe card geometry analysis and design layout using experimental, finite-element, and mechanical methods.

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Use of Harsh Wafer Probing to Evaluate Traditional and CUP Bond Pad Structures

Cited by 13 publications

References 1 publication

Use of Wire Bonding to Study Bond Pad Damage from Wafer Probe

Use of Wire Bonding to Study Bond Pad Damage from Wafer Probe

Improvement of inter layer dielectric crack for LQFP C90FG wafer technology devices in copper wire bonding process

An Experimental and Numerical Investigation Into Wafer Probing Parameters Based on Thin Wafer Breaking Strength

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