Drilling of glass by excimer laser mask projection technique

Thin glass (< 100 microns) is a promising material from which advanced interposers for high density electrical interconnects for 2.5D chip packaging can be produced. But thin glass is extremely brittle, so mechanical micromachining to create through glass vias (TGVs) is particularly challenging. In this article we show how laser processing using deep UV excimer lasers at a wavelength of 193 nm provides a viable solution capable of drilling dense patterns of TGVs with high hole counts. Based on mask illumination, this method supports parallel drilling of up over 1,000 through vias in 30 to 100 µm thin glass sheets. (We also briefly discuss that ultrafast lasers are an excellent alternative for laser drilling of TGVs at lower pattern densities.) We present data showing that this process can deliver the requisite hole quality and can readily achieve future-proof TGV diameters as small 10 µm together with a corresponding reduction in pitch size.

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“…There are five technologies that have been considered for drilling these "through glass vias" (TGVs) in interposers 3,4) :…”

Section: The Challenges Of Drilling High Density Tgvsmentioning

confidence: 99%

Laser Drilling of High-Density Through Glass Vias (TGVs) for 2.5D and 3D Packaging

Delmdahl¹,

Paetzel²

2014

Journal of the Microelectronics and Packaging Society

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“…Furthermore, excellent pattern reproducibility is a wellknown advantage of applying excimer laser mask projection imaging in material processing [2].…”

Section: Resultsmentioning

confidence: 99%

Enabling laser applications in microelectronics manufacturing

et al. 2016

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In this experimental study, we report on highpulse-energy excimer laser drilling into high-performance build-up films which are pivotal in microelectronics manufacturing. Build-up materials ABF-GX13 from Ajinomoto as well as ZS-100 from Zeon Corporation are evaluated with respect to their viability for economic excimer laserbased micro-via formation. Excimer laser mask imaging projection at laser wavelengths of 193, 248 and 308 nm is employed to generate matrices of smaller micro-vias with different diameters and via pitches. High drilling quality is achievable for all excimer laser wavelengths with the fastest ablation rates measured in the case of 248 and 308 nm wavelengths. The presence of glass fillers in buildup films as in the ABF-GX13 material poses some limitations to the minimum achievable via diameter. However, surprisingly good drilling results are obtainable as long as the filler dimensions are well below the diameter of the micro-vias. Sidewall angles of vias are controllable by adjusting the laser energy density and pulse number. In this work, the structuring capabilities of excimer lasers in buildup films as to taper angle variations, attainable via diameters, edge-stop behavior and ablation rates will be elucidated.

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“…17,18 The difference is mainly due to the fact that the fs laser pulse length is ultrashort compared to the timescale for thermal diffusion into the material. The buildup of thermal and mechanical stresses in the material is largely suppressed.…”

Section: Optical Engineeringmentioning

confidence: 99%

Micro-hole drilling and cutting using femtosecond fiber laser

2014

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Abstract. Micro-hole drilling and cutting in ambient air are presented by using a femtosecond fiber laser. At first, the micro-hole drilling was investigated in both transparent (glasses) and nontransparent (metals and tissues) materials. The shape and morphology of the holes were characterized and evaluated with optical and scanning electron microscopy. Debris-free micro-holes with good roundness and no thermal damage were demonstrated with the aspect ratio of 8∶1. Micro-hole drilling in hard and soft tissues with no crack or collateral thermal damage is also demonstrated. Then, trench micromachining and cutting were studied for different materials and the effect of the laser parameters on the trench properties was investigated. Straight and clean trench edges were obtained with no thermal damage.

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Drilling of glass by excimer laser mask projection technique

Cited by 28 publications

References 1 publication

Laser Drilling of High-Density Through Glass Vias (TGVs) for 2.5D and 3D Packaging

Laser Drilling of High-Density Through Glass Vias (TGVs) for 2.5D and 3D Packaging

Enabling laser applications in microelectronics manufacturing

Micro-hole drilling and cutting using femtosecond fiber laser

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