Effects of Excimer Irradiation Treatment on Thermocompression Au–Au Bonding

Unami, Naoko; Sakuma, Katsuyuki; Mizuno, Jun; Shoji, Shuichi

doi:10.1143/jjap.49.06gn12

Cited by 20 publications

(8 citation statements)

References 19 publications

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“…Several Au–Au bonding techniques have been investigated to achieve low-temperature bonding, including thermocompression bonding [6,7,8,9,10,11,12], atomic diffusion bonding [4,13,14], and surface activated bonding (SAB) [15,16,17,18,19]. With SAB, the surfaces to be bonded are activated by plasma pretreatment and then bonded at low temperature (<150 °C).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Argon and Oxygen Plasma Treatments for Ambient Room-Temperature Wafer-Scale Au–Au Bonding Using Ultrathin Au Films

et al. 2019

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Au–Au surface activated bonding is promising for room-temperature bonding. The use of Ar plasma vs. O2 plasma for pretreatment was investigated for room-temperature wafer-scale Au–Au bonding using ultrathin Au films (<50 nm) in ambient air. The main difference between Ar plasma and O2 plasma is their surface activation mechanism: physical etching and chemical reaction, respectively. Destructive razor blade testing revealed that the bonding strength of samples obtained using Ar plasma treatment was higher than the strength of bulk Si (surface energy of bulk Si: 2.5 J/m2), while that of samples obtained using O2 plasma treatment was low (surface energy: 0.1–0.2 J/m2). X-ray photoelectron spectroscopy analysis revealed that a gold oxide (Au2O3) layer readily formed with O2 plasma treatment, and this layer impeded Au–Au bonding. Thermal desorption spectroscopy analysis revealed that Au2O3 thermally desorbed around 110 °C. Annealing of O2 plasma-treated samples up to 150 °C before bonding increased the bonding strength from 0.1 to 2.5 J/m2 due to Au2O3 decomposition.

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Section: Introductionmentioning

confidence: 99%

Comparison of Argon and Oxygen Plasma Treatments for Ambient Room-Temperature Wafer-Scale Au–Au Bonding Using Ultrathin Au Films

et al. 2019

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“…Additionally, vacuum ultraviolet treatments using Xe 2 * excimer lamps were utilized to improve the bond strength of the flip chip and three dimensional (3D) interconnections. [20][21][22] UV lamps can provide large area exposures and short reaction times at low temperature and only require simple and inexpensive apparatus. However, the surface modification effects depend on the lamp parameters such as the wavelength and the intensity as well as on the chamber pressure and atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Surface Modification of Polyethylene Terephthalate (PET) by 172-nm Excimer Lamp

Kasahara

Shoji

Mizuno

2012

Transactions of The Japan Institute of Electronics Packaging

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We studied the effects of 172 nm Xe 2 * excimer lamp irradiation on polyethylene terephthalate (PET) surfaces. Two kinds of techniques were applied: vacuum ultraviolet (VUV) light irradiation and VUV irradiation in the presence of oxygen gas (VUV/O 3 ). The modified PET surfaces were investigated by using contact angle measurements which enabled the surface free energy to be calculated, X-ray photoelectron spectroscopy (XPS), nano-thermal analysis (nano-TA), and atomic force microscopy (AFM). The surface free energy increased significantly after the treatments. The results of XPS analysis showed that the elemental ratio of oxygen on the surface increased, whereas that of carbon decreased. From the deconvoluted C1s and O1s spectra, it was revealed that new oxidized functional groups such as alcoholic and carboxyl groups were generated. The nano-TA results showed that a low melting temperature (T m ) layer had formed on the VUV and VUV/O 3 treated PET surfaces. The results of AFM measurements showed there were no remarkable changes after the treatments compared with untreated PET. In summary, the VUV and VUV/O 3 treatments using a Xe 2 * excimer lamp not only change the surface functionalities but also reduce the T m of the PET surfaces without significantly affecting the surface morphologies.

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“…So we need further studies to avoid these problems over graphene surface before bonding. Focus of research in an eco-friendly way such as VUV [8][9][10] and water vapor exposure method [11] for surface activation will be interesting in order to eliminate the existing process such as chemical, high temperature and harsh environment.…”

Section: Introductionmentioning

confidence: 99%

Room-temperature direct bonding of graphene films by means of vacuum ultraviolet (VUV) / vapor-assisted method

Mano

Shigetou

Mizuno

et al. 2014

2014 International Conference on Electronics Packaging (ICEP)

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A room temperature direct bonding between graphene thin films was realized by using vacuum ultraviolet (VUV) / vapor-assisted surface modification method at atmospheric pressure. In this paper, we examined the bonding between graphene mono layers and multi layers. X-ray photoelectron spectroscopy (XPS) showed that, in the ambient air, the graphene surfaces were easy to be oxidized, which resulted in the formation of CO 2 (C-O 286.6eV) and organic hydrocarbons.Additionally, chlorine from the graphene production process was found on the outmost surface. For such oxidized and adsorbed surfaces, the vacuum ultraviolet (VUV) treatment was found highly effective to modify the chemical binding condition. The VUV irradiation eliminated the oxide and contaminations, and changed the binding condition of carbon. For the monolayer graphene surface, the oxidized site was almost completely removed and C-C bond, which has the binding energy of 284.4 eV, became dominant.For the multilayer surface, although C-O bonds remained, the atomic weight percentage of carbon increased. Raman spectroscopy study results showed that the intensity of defect, which was indicated by D-band, decreased both on the monolayer and multilayer. Moreover, the intensity of 2D band, which was attributable to graphene formation, became stronger; the VUV irradiation turned out effective to modify the crystalline structure to create graphene outmost surface layer. After the VUV irradiation, the surfaces were exposed to the water vapor to make the surface hydrophilic, because molecular water can adsorbe on the hydrophilic carbon surfaces, create hydrogen bond between on the moment of contact, and make good adhesion between the surfaces. XPS observations indicated that the bridging layers including molecular layers, which were assigned as CHO (286.2eV) and/or COOH (288.2eV), were created by water exposure. Raman observations confirmed that the intensity ratio of D band and G band (I D /I G ) decreased and the ratio of 2D band and G band (I 2D /I G ) increased apparently on the monolayer and multilayer, respectively. This inferred that the defect decreased and the disordered graphene layer was reduced on the outmost surface, and the quantitative quality of graphene was improved due to the water exposure. Similarly, the peak shifts showed that, both on the monolayer and multilayer, the crosslink between carbon and hydrogen became closer. Without using chemical process, the simple VUV irradiation combined with the water exposure turned out highly effective to make tight bond between graphene surfaces without degrading the quantitative quality.

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Effects of Excimer Irradiation Treatment on Thermocompression Au–Au Bonding

Cited by 20 publications

References 19 publications

Comparison of Argon and Oxygen Plasma Treatments for Ambient Room-Temperature Wafer-Scale Au–Au Bonding Using Ultrathin Au Films

Comparison of Argon and Oxygen Plasma Treatments for Ambient Room-Temperature Wafer-Scale Au–Au Bonding Using Ultrathin Au Films

Surface Modification of Polyethylene Terephthalate (PET) by 172-nm Excimer Lamp

Room-temperature direct bonding of graphene films by means of vacuum ultraviolet (VUV) / vapor-assisted method

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