Browsing by Author "Leu, Jihperng"

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A Study of the Relationship Between Endurance and Retention Reliability for a HfOx-Based Resistive Switching Memory
(2020-09-01)
Chung, Wei-Min
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Chang, Yao-Feng
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Hsu, Yu-Lin
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Chen, Y. -C. Daphne
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Lin, Chao-Cheng
This study determines the relationship between retention and endurance reliability for a HfOx-based resistive random access memory (ReRAM). A TiN (15 nm) / HfOx (6 nm) / Ti (10 nm) / TiN (40 nm) stacked structure is fabricated and tested to verify its basic characteristics and reliability. The high resistance states (HRS) retention behavior is characterized and is found to degrade over 100x on the endured bits because there is a sequential high temperature procedure. The degradation is reduced slightly to a similar to 30x drop for the endured devices with one single refresh cycle. During the endurance and retention test procedures, the HRS resistance decreases because neutral oxygen vacancy filaments grow and this cannot be reversed. The I-V characteristics for endured devices are also determined. The results show that isothermal treatment causes a gradual SET and RESET process with multiple feasible states. The thermally induced filament degradation model (isolated filament vs. continuous filament) is verified by the relationship between retention and endurance reliability. Design guidance is recommended for an improvement in ReRAM reliability.
Adhesion Investigation Between Metal and Benzocyclobutene (BCB) Polymer Dielectric Materials in 3-D Integration Applications
(2014-09-01)
Shih, Jian-Yu
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Huang, Wen-Chun
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Ko, Cheng-Ta
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Yang, Zheng
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Hu, Sheng-Hsiang
In this paper, the interfacial adhesion strength between metal layer and benzocyclobutene (BCB) polymer dielectric in 3-D integration applications is investigated. The effects of layer thickness, layer stacking order, and additional adhesion layer of titanium (Ti) layer between copper (Cu) and BCB polymer are investigated. Surprisingly, the conventional titanium adhesion layer commonly used in the semiconductor industry weakens the interfacial adhesion strength between copper and BCB. Additionally, to figure out the interfacial adhesion mechanisms, the interfacial structures probed by sum-frequency-generation vibrational spectroscopy are correlated to the adhesion strengths measured from corresponding sample interfaces. It is found that ordered C-H groups at the metal/BCB interface, such as titanium/BCB or molybdenum/BCB, lead to weak interfacial adhesion strength, whereas disordered interfaces, i.e., copper/BCB, lead to strong interfacial adhesion strength.
Adhesion Property Between Cu, Ti Metal and SU-8, AZ 4620 Polymer Dielectric
(2016-07)
Huang, Yen-Jun
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Hsieh, Yen-Hui
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Shih, Jian-Yu
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Chen, Han-Chun
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Leu, Jihperng
This study examines the metal/polymer interfacial adhesion strength for Cu, Ti and three polymers, BCB, SU-8 and AZ 4620. Detailed discussion and explanation focused on adhesion mechanism between metal and BCB, AZ 4620 dielectric are provided. The adhesion strengths of metal on polymer layer are measured by four point bending (FPB) test, which showed that copper and titanium have different characteristics in metal-polymer adhesion. Additionally, to figure out the interfacial adhesion mechanisms, X-ray photoelectron spectroscopy (XPS) technique is used to investigate the chemical bonding compositions between interfaces. The results indicate that the adhesion strength is enhanced by the intense reaction between metal and oxygen on the polymer main chain at the metal-polymer interfaces. On the other hand, interfacial adhesion strength is weaken owing to the destruction of polymer structure, thus the bonding between metal and polymer-main-chain debonded oxygen are of no effect on adhesion.
Advanced metallization for ULSI applications FOREWORD
(2019-07-01)
Nakatsuka, Osamu
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Baklanov, Mikhail R.
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Zhao, Chao
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Chan, Mansun
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Leu, Jihperng
Anisotropic optical transmission of femtosecond laser induced periodic surface nanostructures on indium-tin-oxide films
(2012-09-03)
Wang, Chih
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Wang, Hsuan-I
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Luo, Chih-Wei
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Leu, Jihperng
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材料科學與工程學系
Two types of periodic nanostructures, self-organized nanodots and nanolines, were fabricated on the surfaces of indium-tin-oxide (ITO) films using femtosecond laser pulse irradiation. Multiple periodicities (approximately 800 nm and 400 nm) were clearly observed on the ITO films with nanodot and nanoline structures and were identified using two-dimensional Fourier transformation patterns. Both nanostructures show the anisotropic transmission characteristics in the visible range, which are strongly correlated with the geometry and the metallic content of the laser-induced nanostructures. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4751983]
Broadband UV-assisted thermal annealing of low-k silicon carbonitride films using a C-rich silazane precursor
(2018-11-01)
Chang, Wei-Yuan
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Chung, Hau-Ting
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Chen, Yi-Chang
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Leu, Jihperng
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材料科學與工程學系
Low-k dielectric silicon carbonitride (SiCxNy) films are deposited by plasma-enhanced chemical vapor deposition using a carbon-rich silazane precursor, N-methyl-aza-2,2,4-trimethylsilacyclopentane (SiC7NH17), at 100 degrees C. The post-treatments of SiCxNy films are carried out by thermal annealing and a broadband UV-assisted thermal annealing (UV-annealing) at 400 degrees C for 5 min. Compared to the thermal annealing treatment, UV-annealing can improve both dielectric and mechanical properties of low-k SiCxNy films. Under thermal annealing, SiCxNy films show great thermal stability, but little structural change. In contrast, upon UV-annealing, most of the Si-H and N-H bonds are broken up, which induces more Si-N cross-linking and converts Si-C matrix into Si-N matrix. The ethylene bridges in Si-(CH2)(2)-Si also remain intact, but the unbridged hydrocarbons in Si-(CH2)(2)-N and Si-CH2-CH3 bonds decompose completely during the UV-annealing process. These account for the reduced dielectric constant to k = 3.2 from 3.6 and a 21% enhancement of Young's modulus to 7.4 GPa in the SiCxNy films after UV-annealing. Broadband UV-annealing shows promise as a post-treatment method for enhancing the properties of low-k dielectric barrier, SiCxNy films. Published by the AVS.
Comparison of H-2 and NH3 Treatments for Copper Interconnects
(2013)
Chang, Yu-Min
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Leu, Jihperng
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Lin, Bing-Hong
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Wang, Ying-Lung
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Cheng, Yi-Lung
The surface state, electrical, and reliability characteristics of copper (Cu) interconnects after ammonia (NH3) or hydrogen (H-2) plasma treatment were investigated in this study. The experimental results show that H-2 plasma treatment has excellent Cu oxide removal efficiency, less impact on the formation of Cu hillocks, and less damage on low-dielectric constant (low-k) dielectrics in comparison to NH3 plasma treatment. However, H-2 plasma treatment results in a higher leakage current between the Cu lines and shorter electromigration (EM) failure time due to a weaker adhesion strength at the Cu film interface. On the other hand, NH3 plasma treatment without the sufficient treatment time would lead to an increased probability of delamination at the Cu/barrier layer interface since the Cu oxide layer can not be completely removed. As a result, extending NH3 plasma treatment time can efficiently reduce the adhesion failure and enlarge EM resistance as well.
Dye-sensitized solar cells based on agarose gel electrolytes using allylimidazolium iodides and environmentally benign solvents
(2013-02-28)
Hsu, Hsin-Ling
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Tien, Cheng-Fang
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Yang, Ya-Ting
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Leu, Jihperng
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材料科學與工程學系
Novel agarose gel electrolytes are prepared by allylimidazolium iodides-based ionic liquids and environmentally benign co-solvents (propylene carbonate (PC) and dimethyl sulfoxide (DMSO)) for dye-sensitized solar cells (DSSCs). Among 1-allyl-3-ethylimidadolium iodide (AEII), 1-allyl-3-propylimidazolium iodide (APII), 1-3-diallylimidazolium iodide (DAM, and 1-methyl-3-propylimidazolium iodide (MPII) ionic liquids, the agarose gel electrolyte containing AEII exhibits the best DSSC performance. The efficiency of the DSSC using the agarose gel electrolyte containing 1.5 M AEII and 0.65 wt% agarose is 5.89% with the highest I-3(-) diffusion coefficient of 7.7 x 10(-6) cm(2) s(-1). The performance of the AEII ionic liquid-based agarose gel electrolyte is comparable to the liquid electrolyte based on 3-methoxypropionitrile (MPN) (5.84%) under illumination at AM 1.5, 100 mW cm(-2). Moreover, the DSSC performance of the allylimidazolium iodides ionic liquid-based agarose electrolyte is determined by the interaction between ionic liquid and agarose, which affects the rigidity of the ion channels and the I-3(-) diffusion coefficient. (C) 2013 Elsevier Ltd. All rights reserved.
Effect of Curing on the Porogen Size in the Low-k MSQ/SBS Hybrid Films
(2011)
Chen, Yu-Han
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Jeng, U-Ser
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Leu, Jihperng
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材料科學與工程學系
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Department of Materials Science and Engineering
The interaction between a polystyrene-b-polybutadiene-b-polystyrene (SBS) porogen and a low-k methylsilsesquioxane (MSQ) matrix under different curing profiles and their impact on porogen size were studied by grazing incidence small-angle X-ray scattering, viscosity measurement, and Fourier transform infrared analysis. For slow curing, significant porogen diffusion and aggregation occurred between 100 and 170 degrees C, at which the porogen size increased from 12 to 32 nm. The interaction mechanism between porogen and the MSQ matrix and its correlation with porogen size during the thermal cure process were elucidated. The aggregation of the SBS porogen was greatly influenced by the microstructure of the MSQ matrix at three controlling temperatures; namely, (1) glass transition temperature, T(g) (similar to 100 degrees C), (2) onset temperature (160 degrees C) for transforming cage to network structure, and (3) immobilization temperature (170 degrees C). In contrast, a rapid curing rate enabled the formation of small porogen size (similar to 12 nm) in the hybrid films and yielded better mechanical strength. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3529246] All rights reserved.
Effect of layout on electromigration characteristics in copper dual damascene interconnects
(2014-10-05)
Cheng, Y. L.
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Chang, Y. M.
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Leu, Jihperng
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Bo, T. C.
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Wang, Y. L.
This study demonstrates that the electromigration (EM) behavior of dual damascene Cu lines is strongly affected by the layout which surrounded the tested EM lines, especially for Cu line below 0.10 mu m used for 40 nm or below technologies. The Cu EM lifetime declines as the number of local dummy lines increase, and the global dummy line density increases with the width of the Cu line below 0.063 mu m. This work presents mechanisms of layout effects that explain the EM characteristics and can be exploited to improve the layout effect. Therefore, not only the stressed Cu line structures, but also the surrounding layouts must to be considered in assessing EM reliability of a real IC circuit in 40 nm or below technology. (C) 2014 Elsevier B.V. All rights reserved.
Effect of Moisture on Electrical and Reliability Characteristics for Dense and Porous Low-k Dielectrics
(2013-01-01)
Cheng, Yi-Lung
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Huang, Jun-Fu
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Chang, Wei-Yuan
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Chang, Yu-Min
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Leu, Jihperng
The effect of absorbed moisture on the electrical and reliability characteristics of the low-k dielectrics was investigated in this study. The experimental results indicate that the porous low-k dielectrics would absorb more moisture as compared to the dense low-k dielectrics. This absorbed moisture degrades the electrical and reliability performance of the low-k dielectrics. A higher temperature anneals at 400 degrees C is needed to decompose physicallyadsorbed water, which is benefit to restore reliability performance. On the other hand, the chemically-adsorbed moisture seems to be difficult to be removed by a 400 degrees C annealing, causing a degraded TDDB performance.
Effect of moisture on electrical properties and reliability of low dielectric constant materials
(2014-02-01)
Cheng, Yi-Lung
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Leon, Ka-Wai
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Huang, Jun-Fu
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Chang, Wei-Yuan
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Chang, Yu-Min
The effect of absorbed moisture on the electrical characteristics and reliability of low dielectric constant materials (low-k) was investigated in this study. The experimental results reveal that porous low-k dielectrics absorb more moisture than dense low-k dielectrics. This absorbed moisture degrades the electrical performance and reliability of both classes of low-k dielectrics. Annealing at a higher temperature of 400 degrees C is required to decompose the physically-adsorbed moisture and thereby restore reliability performance. However, the chemically-adsorbed moisture seems to be difficult to remove by annealing at 400 degrees C, causing a degraded TDDB performance. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Effect of NH3/N-2 ratio in plasma treatment on porous low dielectric constant SiCOH materials
(2014-05-01)
Huang, Jun-Fu
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Bo, Tain-Cih
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Chang, Wei-Yuan
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Chang, Yu-Min
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Leu, Jihperng
This study investigates the effect of the NH3/N-2 ratio in plasma treatment on the physical and electrical properties as well as the reliability characteristics of porous low-k films. All of the plasma treatments resulted in the formation of a thin and modified layer on the surface of porous low-k films, and the properties of this modified layer were influenced by the NH3/N-2 ratio in the plasma. Experimental results indicated that pure N-2 gas plasma treatment formed an amide-like/nitride-like layer on the surface, which apparently leads to a higher increase in the dielectric constant. Plasma treatment with a mixture of NH3/N-2 gas induced more moisture uptake on the surface of the low-k dielectric, degrading the electrical performance and reliability. Among all plasma treatment with NH3/N-2 mixed gas, that with pure NH3 gas yielded low-k dielectrics with the worse electrical and reliability characteristics. (C) 2014 American Vacuum Society.
Effect of pore size/distribution in TiO2 films on agarose gel electrolyte-based dye-sensitized solar cells
(2014-06-01)
Hsu, Hsin-Ling
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Tien, Cheng-Fang
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Leu, Jihperng
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材料科學與工程學系
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Department of Materials Science and Engineering
This study develops a simple method to change the distribution of the pore size in a TiO2 layer, using polyethylene glycol (PEG), while maintaining nearly the same surface area and porosity to clarify how large pores affect the performance of dye-sensitized solar cells (DSSCs). Specifically, a heating step at 100 A degrees C for a specific duration is added prior to PEG removal and TiO2 sintering at 400 A degrees C. This process transforms the role of the PEG from a surfactant to a pore generator (porogen) and forms larger pores, depending on the loading and aggregation time for the PEG to gain larger pores. The effect of larger pores in TiO2 films under 30 % PEG loading, on the performance of an agarose gel electrolyte-based DSSC, was further investigated using the ionic liquid, 1-allyl-3-ethylimidazolium iodide (AEII). The I-V characteristic and the electrochemical impedance spectroscopy analysis show that larger pores readily improve redox couple diffusion in a TiO2 porous electrode and modify the interface between electrolyte and TiO2. Using the optimized TiO2 film with larger pores (30 % PEG loading, 100 A degrees C/60 min), an efficiency of 7.43 % is achieved for the agarose gel electrolyte-based DSSC, which represents a 26.1 % improvement over TiO2 without the addition of PEG.
Effect of Porogen Incorporation on Pore Morphology of Low-k SiCxNy Films Prepared Using PECVD
(2015-01-01)
Tu, Hung-En
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Su, Chun-Jen
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Jeng, U-Ser
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Leu, Jihperng
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材料科學與工程學系
Low-k porous SiCxNy films were prepared through plasma-enhanced chemical vapor deposition, using 1,3,5-trimethyl-1,3,5-trivinylcyclotrisilazane (VSZ) as the matrix precursor and epoxycyclohexane (ECH) as a porogen. The effects of porogen loading and deposition temperature on porogen incorporation, pore morphology, and the properties of porous SiCxNy films were examined. In addition, the impact of film shrinkage and the corresponding nanopore structures after annealing were studied. The porosity of films deposited at 100 degrees C increased from 1.8% to 19.8% when ECH loading increased to 30%, above which the porosity remained nearly constant because of high film shrinkage. The pore size decreased slightly from 4.1 to 3.7 nm when ECH loading increased to 30%, above which the pores became larger and were broadly distributed. By contrast, increasing deposition temperature at 20% ECH loading decreased porogen incorporation and increased film density. The porosities and pore size of films decreased, respectively, when the deposition temperature increased. A short-range ordering of pores was observed only at low deposition temperatures because the N-Si-C cross-linked structures and organic phase were present. Optimized processing parameters facilitated the fabrication of low-k porous SiCxNy films exhibiting 19.8% porosity, 3.7-nm pores, a k value of 3.18, and an elastic modulus of 7.7 GPa. (C) The Author(s) 2014. Published by ECS. All rights reserved.
Effect of surfactants on the porogen size in the low-k methylsilsesquioxane/polystyrene hybrid films
(2012-11-01)
Chen, Yu-Han
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Tu, Hung-En
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Leu, Jihperng
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材料科學與工程學系
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Department of Materials Science and Engineering
An anionic surfactant, sodium dodecylbenzenesulfonate (NaDBS) and a cationic surfactant, domiphen bromide (DB) were used to modify the surface potential of polystyrene (PS) porogen in a post-integration porogen removal scheme. The effect of surfactant modification on the porogen and pore size in the low-k methylsilsesquioxane (MSQ)/PS hybrid films at 10 wt% PS loading, under a slow curing rate, was studied by grazing incidence small-angle X-ray scattering, viscosity measurement, and Fourier-transform infrared analysis. For PS porogen without modification, the porogen aggregated and its size increased from 10.0 to 16.5 nm at different rates, up to 200 degrees C, depending on the porogen diffusivity and steric hindrance by the successively cross-linked MSQ matrix at T >= T-g. In contrast, the NaDBS- and DB-modified porogens with higher surface potential impede their aggregation within the cross-linking MSQ matrix, resulting in a smaller porogen size, by electrostatic repulsion and increased viscosity due to electroviscous effect. Also, the columbic attraction between Si-OH groups of MSQ matrix and the positively charged, DB-modified PS, restrains the PS porogen, thus reduces its aggregation during cure step, leading to a small porogen size and tight distribution (8.7 +/- 2 nm) at 200 degrees C and later a similar pore size after porogen removal at 400 degrees C. (C) 2012 Elsevier Inc. All rights reserved.
Effect of thermal treatment on physical, electrical properties and reliability of porogen-containing and porogen-free ultralow-k dielectrics
(2013-01-15)
Chang, Yu-Min
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Chang, Wei-Yuan
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Huang, Jun-Fu
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Leu, Jihperng
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Cheng, Yi-Lung
The effects of thermal annealing on the physical, electrical properties and reliability of porogen-containing and porogen-free ultralow-k dielectrics prepared by plasma-enhanced chemical vapor deposition (PECVD) are investigated. The porogen-free low-k dielectrics are obtained by using UV curing process to removal organic sacrificial phase and to generate open porosity. The results are compared with PECVD porogen-containing low-k films fabricated without UV curing process and PECVD low-k dielectrics deposited without organic sacrificial phase. The experimental results show that all low-k films remained stable after they were experimentally heating to temperatures up to 700 degrees C. The non-porous low-k films also showed the highest reliability. Although the porous-free low-k film requires an additional UV curing process, the heat stress confirmed that its thermal stability was better than that of the porogen-containing low-k film. At an annealing temperature above 500 degrees C, the heating process is comparable to UV curing, but does not provide Si-O-Si cross-linking within the film. At an annealing of 600 degrees C, the porogen-free low-k films have a relatively higher breakdown electric-field and longer failure time in comparison to the porogen-containing low-k films. However, pores generated in porogen-containing low-k films at high temperature cause reliability to degrade with annealing temperature. Crown Copyright (c) 2012 Published by Elsevier B.V. All rights reserved.
Effect of UV curing time on physical and electrical properties and reliability of low dielectric constant materials
(2014-11-01)
Kao, Kai-Chieh
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Chang, Wei-Yuan
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Chang, Yu-Min
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Leu, Jihperng
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Cheng, Yi-Lung
This study comprehensively investigates the effect of ultraviolet (UV) curing time on the physical, electrical, and reliability characteristics of porous low-k materials. Following UV irradiation for various periods, the depth profiles of the chemical composition in the low-k dielectrics were homogeneous. Initially, the UV curing process preferentially removed porogen-related CHx groups and then modified Si-CH3 and cage Si-O bonds to form network Si-O bonds. The lowest dielectric constant (k value) was thus obtained at a UV curing time of 300 s. Additionally, UV irradiation made porogen-based low-k materials hydrophobic and to an extent that increased with UV curing time. With a short curing time (<300 s), porogen was not completely removed and the residues degraded reliability performance. A long curing time (>300 s) was associated with improved mechanical strength, electrical performance, and reliability of the low-k materials, but none of these increased linearly with UV curing time. Therefore, UV curing is necessary, but the process time must be optimized for porous low-k materials on back-end of line integration in 45 nm or below technology nodes. (C) 2014 American Vacuum Society.
Effects of CF(4) plasma treatment on the moisture uptake, diffusion, and WVTR of poly(ethylene terephthalate) flexible films
(2011-10-25)
Wang, Chih
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Lai, Po-Cheng
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Syu, Shu Hao
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Leu, Jihperng
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材料科學與工程學系
We studied the effects of CF(4) plasma surface treatment on moisture uptake, diffusion, and the water-vapor-transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF(4) plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF(4) plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m(2)/day, while a significant reduction (84%) of WVTR to 0.43 g/m(2)/day, is achieved for CF(4) plasma-treated PET film (60 W. 15 min), which alters the surface hydrophobicity (similar to 107 degrees) and simultaneously builds a denser, fluorinated top-layer (47 nm). The surface fluorinated layer has a diffusivity of to 8.7 x 10(-12) m(2)/s and a WVTR of similar to 1.0 x 10(-4) g/m(2)/day based on a series resistance model. (C) 2011 Elsevier B.V. All rights reserved.
Effects of CF4 plasma treatment on the moisture uptake, diffusion, and WVTR of poly(ethylene terephthalate) flexible films
(2011-10-25)
Wang, Chih
;
Lai, Po-Cheng
;
Syu, Shu Hao
;
Leu, Jihperng
;
材料科學與工程學系
We studied the effects of CF4 plasma surface treatment on moisture uptake, diffusion, and the water-vapor-transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF4 plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF4 plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m(2)/day, while a significant reduction (84%) of WVTR to 0.43 g/m(2)/day, is achieved for CF4 plasma-treated PET film (60 W. 15 min), which alters the surface hydrophobicity (similar to 107 degrees) and simultaneously builds a denser, fluorinated top-layer (47 nm). The surface fluorinated layer has a diffusivity of to 8.7 x 10(-12) m(2)/s and a WVTR of similar to 1.0 x 10(-4) g/m(2)/day based on a series resistance model. (C) 2011 Elsevier B.V. All rights reserved.