Air-Gaps for Electrical Interconnections

Kohl, Paul A.; Zhao, Qiang; Patel, Krishna Kumar; Schmidt, Douglas S.; Bidstrup-Allen, S.A.; Shick, Robert A.; Jayaraman, Saikumar

doi:10.1149/1.1390631

Cited by 40 publications

(16 citation statements)

References 6 publications

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“…This includes fabrication of air-gaps in electrical interconnects, MEMS, microfluidic devices, and micro-reactors. The formation of air-gaps is important in electrical interconnects because it lowers the effective dielectric constant of the matrix [1]- [5]. The fabrication of buried air-channels is useful for the creation of vias in multi-level wiring boards, micro-display boards with high resolution, and ink-jet printer heads.…”

Section: Introductionmentioning

confidence: 99%

“…Also, Moore et al used highly structured dendritic material, specifically, hyperbranched polymers as a dry-release sacrificial material in the fabrication of cantilever beam [8]. Previous work by Kohl et al has demonstrated the fabrication of air-gaps using nonphotosensitive sacrificial polymers that decompose in the range 250-425 C [1], [4]. Fig.…”

Section: Introductionmentioning

confidence: 99%

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Air-channel fabrication for microelectromechanical systems via sacrificial photosensitive polycarbonates

Jayachandran

Reed

Zhen

et al. 2003

J. Microelectromech. Syst.

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This research involves the fabrication of encapsulated air-channels via acid-catalyzed degradation of photosensitive polycarbonates (PCs). There is a need for lower-temperature, degradable polymeric materials to fabricate buried air-channels for microelectromechanical systems (MEMS), microfluidic devices, and micro-reactors. Some polycarbonates undergo thermolytic degradation in the temperature range of 200 to 350 C. These polycarbonates are also known to undergo acid-catalyzed decomposition in the presence of catalytic amounts of acid. A small percentage of an acid in the polycarbonate formulation can greatly reduce the onset of decomposition temperature to the 100 to 180 C temperature range. The photoacid and thermalacid induced degradation behavior of PCs and its use as a sacrificial material for the formation of air-gaps have been studied in this work. The decomposition of several polycarbonates with the aid of in situ generated photo-acid has been demonstrated and applied to the fabrication of micro air-channels. Based on FT-IR, mass spectrometry, and thermogravimetric analysis (TGA), a degradation mechanism was proposed.[849]

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Air-channel fabrication for microelectromechanical systems via sacrificial photosensitive polycarbonates

Jayachandran

Reed

Zhen

et al. 2003

J. Microelectromech. Syst.

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“…Several processing techniques have been disclosed for forming air-isolation in electronic devices including the use of CMP and via etch [4], etch back technique [7][8], sacrificial polymers [5,6,[10][11][12][13], and wet etching [9]. Among these techniques, the use of a sacrificial polymer for creation of air-gaps is a promising method which can be applied to a variety of applications.…”

Section: Fabrication Of Air-gap Structuresmentioning

confidence: 99%

“…Among these techniques, the use of a sacrificial polymer for creation of air-gaps is a promising method which can be applied to a variety of applications. The fabrication of air-gaps in electrical interconnects based on a sacrificial polymer and plasma-enhanced chemical vapor deposited (PECVD) SiO 2 has been presented by Kohl et al [10][11]. A sacrificial polymer embedded between metal interconnect structures was used.…”

Section: Fabrication Of Air-gap Structuresmentioning

confidence: 99%

Design and fabrication of ultra low-loss, high-performance 3D chip-chip air-clad interconnect pathway

Uzunlar

Sharma

Saha

et al. 2013

2013 IEEE 63rd Electronic Components and Technology Conference

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In this study, we are pursuing an ultra low-loss interconnect pathway for 3D chip-chip connectivity, incorporating air-clad planar interconnects, air-clad TSVs, and gradual vertical-horizontal transitions. The motivation is to create an air-gap technology that offers the lowest possible effective k-value and near zero loss tangent minimizing the dielectric loss. The design and modeling of air-gap interconnection is presented. The fabrication challenges in airclad interconnect lines are discussed. A monolithic inverted air-gap horizontal transmission line structure is proposed as a means for further decreasing the dielectric loss. Extension of air-clad TSV technology for optical transmission is briefly discussed. IntroductionModern electronic systems are composed of a dense fabric of interconnect lines that connect electronic devices and chips. The scaling of transistors has resulted in miniaturization of individual devices and their interconnects. Smaller crosssectional area of electrical interconnects results in higher signal attenuation and makes data and clock recovery complex. High-speed interconnects have two primary loss mechanisms, namely metallic skin effect losses and dielectric losses. Skin effect loss is a phenomenon where, at high frequencies, the current is crowded into the near-surface region of the metal around the periphery of the conductor. As a result, the effective AC resistance per unit length of conductor increases with frequency. The second loss mechanism deals with dielectric losses. Dielectric losses are directly proportional to frequency and are therefore more pronounced at higher frequencies. Also, resistive losses in the return ground path cannot be ignored and are determined by the geometry and materials constituting the return path. Overall, dielectric losses dominate at frequencies above several GHz [1-2], as shown in Figure 1. This figure was produced with data from the International Technology Roadmap for Semiconductors (ITRS) for signal frequencies up to 50 GHz. As shown in Figure 1, the dielectric loss is more than twice that of the conductor loss at 20 GHz and the dielectric loss becomes more dominant at frequencies above 20 GHz. Thus, in order to achieve meaningful reduction in signal attenuation it is important to find ways to mitigate the dielectric loss at high frequencies. One way of achieving this goal is to use better interconnect and substrate materials.

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“…This type of structure could be used in applications that require hollow channels for fluid or gas plumbing ͑i.e., microfluidics 5 or gas chromatography 6,7 ͒. Air-bridge structures 8 used in microelectronics to create low-dielectric constant regions could also be created using this new fabrication method. Pressure sensing devices that require a movable membrane 9,10 could also be impacted.…”

Section: Introductionmentioning

confidence: 99%

Polymer stretching to produce flat suspended micromembranes

Campbell

2005

J. Micro/Nanolith. MEMS MOEMS

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A microfabrication technique specifically applicable for making structures with thin, flat air gaps is presented. The technique relies upon heating a polymer causing it to contract and form a stretched micromembrane across stationary platforms. To validate and quantify this process, structures were made using SU8, a spin-on photosensitive epoxy, as the polymer attached to a silicon substrate. The stretching of the SU8 in these structures for different heat treatments was characterized using a mechanical profilometer. Optical interference effects were also used to evaluate the overall flatness of these structures based on the reflected colors across their surfaces. SU8 membranes up to 200 micrometers wide were successfully stretched flat with variations in the underlying air-gap thickness of less than 20 nm. © 2005 Society of PhotoOptical Instrumentation Engineers.

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Air-Gaps for Electrical Interconnections

Cited by 40 publications

References 6 publications

Air-channel fabrication for microelectromechanical systems via sacrificial photosensitive polycarbonates

Air-channel fabrication for microelectromechanical systems via sacrificial photosensitive polycarbonates

Design and fabrication of ultra low-loss, high-performance 3D chip-chip air-clad interconnect pathway

Polymer stretching to produce flat suspended micromembranes

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