Thick Film Photoresist Process for Copper Pillar Bumps on Surface Acoustic Wave - Wafer Level Packages

Schober, Jakob; Berger, Johannes; Eulenkamp, Constanze; Nicolaus, Karl; Feiertag, G.

doi:10.1109/estc48849.2020.9229720

Cited by 5 publications

(2 citation statements)

References 15 publications

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“…A commercial TMAH (tetramethylammonium hydroxide) based developer is used. The exact spin coat recipe, the impact of resist bake temperature and duration, and the development process on the resist opening shape and diameter is described in our previous work [9]. This publication also describes the significant impact of the required plasma cleaning after resist development on the adhesion of the electroplated Cu to the underlying Cu seed-layer.…”

Section: B Copper Pillar Bumps Manufacturingmentioning

confidence: 99%

Reliability Study of Miniaturized Surface Acoustic Wave RF-Filters With Copper Pillar Bump Interconnections

Schober

Eulenkamp

Nicolaus³

et al. 2021

IEEE Access

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Microacoustic radio frequency filters are essential electronic components for all devices using wireless communication. For miniaturization and cost reduction it is necessary to further reduce the area for the electrical contacts on the chip. CPB (copper pillar bump) interconnections on radio frequency filters can release valuable chip design area of up to 26 % compared to standard SB (solder bump) interconnections on a Qualcomm TFAP (Thin Film Acoustic Package). We developed a process to deposit CPB interconnections on microacoustic radio frequency filters. A 1.20 mm  1.60 mm SAW (surface acoustic wave) LTE (Long Term Evolution) band 26 duplexer with a height of 0.20 mm including the CPB interconnections was investigated. Unbiased highly accelerated stress test, damp heat steady state, dry heat, and temperature cycling reliability tests have shown that the new interconnection technology fulfills the reliability requirements of the smart device industry. Two failure modes caused by extended temperature cycling reliability were identified via scanning acoustic microscopy and scanning electron microscopy analyses on cross sections.

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Section: B Copper Pillar Bumps Manufacturingmentioning

confidence: 99%

Reliability Study of Miniaturized Surface Acoustic Wave RF-Filters With Copper Pillar Bump Interconnections

Schober

Eulenkamp

Nicolaus³

et al. 2021

IEEE Access

Self Cite

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“…For the photoresist, a light-sensitive and polymer-structured material, homogenous coating with desirable thickness is important. To achieve a homogenous photoresist coating, the process of spin coating parameters such as temperature and speed of rotation should be tuned accordingly [11]. The second step is the laser exposure onto the photoresist.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study on the Photoresist Patterning of Glass and Silicon With Microholes via Maskless Photolithography

GÜÇLÜER

Keleş

2022

Eurasian Journal of Science Engineering and Technology

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Maskless photolithography, a useful tool used in patterning the photoresist which acts as a mask prior to the actual etching process of substrate, has attracted attention mainly due to the taking advantage of reducing cost because of not requiring a preprepared mask and freedom in creating the desired pattern on any kind of substrate. In this study, we performed the positive photoresist patterning with microstructures on both glass and silicon substrates via maskless photolithography. Specifically, we examined the discrepancies between the transparent (glass) and reflective (silicon) substrates even though the photolithographic process has been carried out under the same conditions. Since the positive photoresist patterning was the subject of this study, we could successfully produce the microholes with almost circular shapes and properly placed in squarely packed on both substrates as confirmed by optical microscopy and profilometer mapping measurements. We observed additional rings around the holes when silicon was used as substrate while very clear microholes were obtained for glass. Besides, the number of the rings increased when the writing speed of laser (velocity) reduced. We claim that these important findings can be attributed to the standing wave effect phenomenon which results from the multiple reflections through the semi-transparent photoresist coated on the reflective surface of the polished silicon. In brief, we reveal an important conclusion, in this study, based on the differences in formation of the microholes only due to the substate preference while all the photolithographic process parameters are kept the same.

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Reliability Study of Copper Pillar Bump Interconnects for Acoustic Wave - Wafer Level Package

Schober

Nicolaus²,

Feiertag

2020

2020 IEEE 22nd Electronics Packaging Technology Conference (EPTC)

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Thick Film Photoresist Process for Copper Pillar Bumps on Surface Acoustic Wave - Wafer Level Packages

Cited by 5 publications

References 15 publications

Reliability Study of Miniaturized Surface Acoustic Wave RF-Filters With Copper Pillar Bump Interconnections

Reliability Study of Miniaturized Surface Acoustic Wave RF-Filters With Copper Pillar Bump Interconnections

A Comparative Study on the Photoresist Patterning of Glass and Silicon With Microholes via Maskless Photolithography

Reliability Study of Copper Pillar Bump Interconnects for Acoustic Wave - Wafer Level Package

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