A novel packaging method using wafer-level BCB polymer bonding and glass wet-etching for RF applications

Seok, Seonho; Rolland, N.; Rolland, P.A.

doi:10.1016/j.sna.2008.06.008

Cited by 12 publications

(4 citation statements)

References 9 publications

(11 reference statements)

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“…Within the framework of micro/nanotechnologies, polymer-based materials such as polymethylmethacrylate (PMMA) [1,2], poly-vinyl chloride (PVC) [3][4][5], poly-vinyl alcohol (PVA) [6,7], polysiloxane (PSX) [8], SU-8 epoxy resin [9][10][11][12], polydimethylsiloxane (PDMS) [13][14][15][16][17], benzocyclobutene (BCB) [18][19][20][21][22],…, have shown very promising potentialities for a wide range of applications: sacrificial layers techniques, surface micropatterning, micro/nanomaterials integration, dielectric insulation, packaging (from wafer to system level),… Nevertheless, whatever the polymer chemistry, the mass-fabrication requirement has been carried out through the development of specific micro/nanolithography processes based on inkjet printing, spray coating, micro/nano contact printing, micromoulding, serigraphy shadow mask patterning and of course photolithography. This last process is well adapted to wafer level packaging techniques.…”

Section: Introductionmentioning

confidence: 99%

“…allows the determination of the final thickness hf deposited by spin coating. For a Newtonian solution (n =1), it is equivalent to the relation defined by Meyerhofer[26]:(22) For a Maxwellian solution (0 < n < 1), equation(21) still involves the arbitrary radius parameter r0 (as a consequence of the non-consideration of the gravity forces in the theoretic model, see below). This mathematical consequence prevents from having any information on the solvent surfacic evaporation per unit time parameter e. Nevertheless, equation(21)can be simplified in order to highlight the relation between the final thickness hf and the main parameter of the spin coating process, i.e.…”

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confidence: 99%

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Theoretical studies of the spin coating process for the deposition of polymer-based Maxwellian liquids

Temple‐Boyer

Mazenq

Doucet

et al. 2010

Microelectronic Engineering

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This paper deals with the study of spin coating processes for the deposition of polysiloxane-based thin films. Specific developments are proposed in order to adapt the hydrodynamic laws theory to the spin coating of Maxwellian liquids. Theoretical and experimental results are compared, evidencing a good fit and enabling to define the Maxwellian law for the studied polysiloxane polymer. Finally, the theoretical developments are successfully extended to the BCB 4026 and SU-8 3050 photosensitive resins.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Theoretical studies of the spin coating process for the deposition of polymer-based Maxwellian liquids

Temple‐Boyer

Mazenq

Doucet

et al. 2010

Microelectronic Engineering

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“…One of the promising candidates of polymer adhesives for RF MEMS applications is benzo-cyclo-butene (BCB) from Dow Chemical Company. BCB is an organic resin with superior electrical, mechanical and thermal properties due to its high resistivity (10 19 Ω·cm), low loss tangent (0.0008–0.002), low permittivity (2.65), low moisture absorption (<0.2%), low out-gassing, low cure temperature (<250 °C), small volume shrinkage during curing (5–6%) and excellent dielectric stability over a wide frequency range [ 14 , 15 , 16 ]. Additionally, BCB as the intermediate bonding material offers the highest bond strength in comparison to other conventional bonding polymers [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Wafer-Level Packaging Method for RF MEMS Applications Using Pre-Patterned BCB Polymer

2018

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A radio-frequency micro-electro-mechanical system (RF MEMS) wafer-level packaging (WLP) method using pre-patterned benzo-cyclo-butene (BCB) polymers with a high-resistivity silicon cap is proposed to achieve high bonding quality and excellent RF performance. In this process, the BCB polymer was pre-defined to form the sealing ring and bonding layer by the spin-coating and patterning of photosensitive BCB before the cavity formation. During anisotropic wet etching of the silicon wafer to generate the housing cavity, the BCB sealing ring was protected by a sputtered Cr/Au (chromium/gold) layer. The average measured thickness of the BCB layer was 5.9 μm. In contrast to the conventional methods of spin-coating BCB after fabricating cavities, the pre-patterned BCB method presented BCB bonding layers with better quality on severe topography surfaces in terms of increased uniformity of thickness and better surface flatness. The observation of the bonded layer showed that no void or gap formed on the protruding coplanar waveguide (CPW) lines. A shear strength test was experimentally implemented as a function of the BCB widths in the range of 100–400 μm. The average shear strength of the packaged device was higher than 21.58 MPa. A RF MEMS switch was successfully packaged using this process with a negligible impact on the microwave characteristics and a significant improvement in the lifetime from below 10 million to over 1 billion. The measured insertion loss of the packaged RF MEMS switch was 0.779 dB and the insertion loss deterioration caused by the package structure was less than 0.2 dB at 30 GHz.

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“…Some of the more specialized approaches include localized laser heating [ 13 ], localization of UV-curable adhesive by centrifugal spinning [ 14 ], and transfer bonding of pre-formed benzocyclobutene (BCB) caps [ 15 ]. More common approaches to selective adhesive bonding are based on patterning of photosensitive adhesives by photolithography, or masking and etching of non-photosensitive adhesives [ 12 , 16 , 17 , 18 ]. However, patterning by either photolithography or etching typically requires partial cross-linking of the polymer adhesive, for example by baking.…”

Section: Introductionmentioning

confidence: 99%

Cost-Efficient Wafer-Level Capping for MEMS and Imaging Sensors by Adhesive Wafer Bonding

et al. 2016

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Device encapsulation and packaging often constitutes a substantial part of the fabrication cost of micro electro-mechanical systems (MEMS) transducers and imaging sensor devices. In this paper, we propose a simple and cost-effective wafer-level capping method that utilizes a limited number of highly standardized process steps as well as low-cost materials. The proposed capping process is based on low-temperature adhesive wafer bonding, which ensures full complementary metal-oxide-semiconductor (CMOS) compatibility. All necessary fabrication steps for the wafer bonding, such as cavity formation and deposition of the adhesive, are performed on the capping substrate. The polymer adhesive is deposited by spray-coating on the capping wafer containing the cavities. Thus, no lithographic patterning of the polymer adhesive is needed, and material waste is minimized. Furthermore, this process does not require any additional fabrication steps on the device wafer, which lowers the process complexity and fabrication costs. We demonstrate the proposed capping method by packaging two different MEMS devices. The two MEMS devices include a vibration sensor and an acceleration switch, which employ two different electrical interconnection schemes. The experimental results show wafer-level capping with excellent bond quality due to the re-flow behavior of the polymer adhesive. No impediment to the functionality of the MEMS devices was observed, which indicates that the encapsulation does not introduce significant tensile nor compressive stresses. Thus, we present a highly versatile, robust, and cost-efficient capping method for components such as MEMS and imaging sensors.

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A novel packaging method using wafer-level BCB polymer bonding and glass wet-etching for RF applications

Cited by 12 publications

References 9 publications

Theoretical studies of the spin coating process for the deposition of polymer-based Maxwellian liquids

Theoretical studies of the spin coating process for the deposition of polymer-based Maxwellian liquids

Wafer-Level Packaging Method for RF MEMS Applications Using Pre-Patterned BCB Polymer

Cost-Efficient Wafer-Level Capping for MEMS and Imaging Sensors by Adhesive Wafer Bonding

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