Browsing by Author "Kho, Yi-Tung"

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Adhesion and Material Properties Between Polyimide and Passivation Layers for Polymer/Metal Hybrid Bonding in 3-D Integration
(2019-03-01)
Lu, Cheng-Hsien
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Kho, Yi-Tung
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Chen, Chiao-Pei
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Tsai, Bin-Ling
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Chen, Kuan-Neng
This paper investigates polymer/metal hybrid bonding structure using conventional polyimide and modified polyimide-like material. Adhesion properties between bonding material and passivation layer were evaluated by four-point bending method, atomic force microscopy, water contact angle measurement, and X-ray photoelectron spectroscopy. Various annealing temperatures were applied to verify the reliability under thermal stress. The results show that the modified polyimide-like material with the curing temperature below 250 degrees C has better adhesion than the conventional polyimide. This modified polyimide material can be used in low-temperature hybrid bonding technology for advanced integration.
Adhesion Property of Polyimide and Passivation Layer for Polymer/metal Wafer-level Hybrid Bonding in 3D Integration
(2018-01-01)
Lu, Cheng-Hsien
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Kho, Yi-Tung
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Yang, Yu-Tao
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Chen, Yu-Pei
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Chen, Chiao-Pei
In this paper, the four-point bending method experiments were carried out with different polyimides and passivation layers for realization of adhesion property below 400 degrees C. Three types of passivation layers, thermal oxide, tetraethoxysilane (TEOS) oxide, silicon nitride, and three types of polyimides, with hydrophobic silane, with hydrophilic silane and without silane, and annealing temperature were all considered in this paper. Moreover, the relation between adhesion strength and surface roughness is discussed. Finally, a low thermal budget (250-375 degrees C) polyimide/metal hybrid bonding scheme with good stress release was proposed for future hybrid bonding applications.
Development and Investigation of Ultra-Thin Buffer Layers Used in Symmetric Cu/Sn Bonding and Asymmetric Cu/Sn-Cu Bonding for Advanced 3D Integration Applications
(2017-01-01)
Chen, Hsiu-Chi
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Kho, Yi-Tung
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Huang, Yen-Jun
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Hsieh, Yu-Sheng
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Chang, Yao-Jen
In this work, a particular ultra-thin buffer layer (UBL) with various thickness ranging from 10 nm to 100 nm and different materials including Co, Ni, Pd and Ti is inserted between Cu/Sn to delay the interdiffusion prior to eutectic bonding. The efficacy of the buffer layer and the bonding quality are systematically conferred using microstructure imaging, material analysis, and electrical performance. In addition to symmetric Cu/Sn bonding with UBL, an asymmetric Cu/Sn-Cu bonding which is proposed to relieve the heat enhanced interdiffUsion issues thereby enhancing the reliability performance is demonstrated with the assistance of UBL technology.
Investigation and Optimization of Ultrathin Buffer Layers Used in Cu/Sn Eutectic Bonding
(2018-07-01)
Tang, Ya-Sheng
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Chen, Hsiu-Chi
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Kho, Yi-Tung
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Hsieh, Yu-Sheng
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Chang, Yao-Jen
Ultrathin buffer layers (UBLs) with varied thickness ranging from 10 to 100 nm and different materials were used in Cu/Sn eutectic bonding. A Cu/Sn film thinner than 2 mu m could fully react and became stiff and rough Cu-Sn intermetallic compound layer, which leads to failure bonding. Four kinds of semiconductor compatible materials including Ti, Pd, Co, and Ni were inserted between Cu/Sn to delay interdiffusion prior to eutectic bonding. In addition to symmetric Cu/Sn bonding with UBL, asymmetric Cu/Sn-Cu bonding scheme with 50-nm Ni UBL was demonstrated. With good mechanical properties, bonding quality, and electrical characteristics, the application of submicrometer Cu/Sn wafer-level bonding by assistance of buffering layer gives a promising and flexible platform for future 3-D integration applications.
Investigation of Co Thin Film as Buffer Layer Applied to Cu/Sn Eutectic Bonding and UBM With Sn, SnCu, and SAC Solders Joints
(2017-11-01)
Tang, Ya-Sheng
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Derakhshandeh, Jaber
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Kho, Yi-Tung
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Chang, Yao-Jen
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Slabbekoorn, John
The demand of small-feature-size, high-performance, and dense I/O density applications promotes the development of fine-pitch vertical interconnects for 3-D integration where microbumps are fabricated with Cu through-silicon via and under-bump metallization. Small dimension Cu/Sn bonding has to be developed to address the needs of increasing I/O density and shrinking pitch and size for future applications. For fine-pitch microbumps, it is important to select right UBM and solder materials to obtain lower UBM consumption, which means lower intermetallic compound (IMC) thickness. To find the best binary system material for fine-pitch microbumps with a different annealing temperature and time, we investigate the interfacial reaction and intermetallic compound morphologies of Co UBM with Sn, SnCu, and SAC solders. A thin, uniform, and single-phase IMC between solder and UBM facilitates finer pitch and more reliable microbumps development; the higher activation energies imply longer solder lifetime. Co, as an ultrathin buffer layer (UBL), is also used in Cu/Sn bonding. A comparison between Cu-Sn bonding with and without UBL is conducted. From this study, Co as UBL and UBM is explored and could be applied in semiconductor applications.
Polymer for Wafer-level Hybrid Bonding and Its Adhesion to Passivation Layer in 3D Integration
(2017-01-01)
Lu, Cheng-Hsien
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Kho, Yi-Tung
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Cheng, Chuan-An
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Huang, Yen-Jun
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Chen, Kuan-Neng
Hybrid bonding is one of the key technologies in 3D IC integration, which can integrate various functional chips using vertical interconnection to reduce RC delay and realize heterogeneous integration by bonding process. Conventional hybrid bonding uses oxide layer as the filling material between the metal interconnect, which can prevent oxidation of metal layer and enhance the bonding strength. However, there are some issues of oxide layer such as its poor stress absorption and the demand of surface flatness. Polymer is the potential material to replace oxide as hybrid bonding material because of its stress release property and better surface roughness tolerance. This paper investigates the adhesion properties of polymer and passivation layer and demonstrates perfect polymer-to-polymer wafer-level bonding results.