Browsing by Author "Lee, Wen-Hsi"

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A Novel Synthesis of a CuInSe2 Thin Film from Electrodeposited Cu-Se-In-Se Precursors with Three Steps Annealing
(2012-09-01)
Hu, Shao-Yu
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Lee, Wen-Hsi
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Chang, Shih-Chieh
;
Wang, Ying-Lang
;
照明與能源光電研究所
In this study, copper indium diselenide (CIS) films were synthesized from electrodeposited Cu-Se In Se precursors by three step annealing. The Se layer between Cu and In layer was grown to prevent the formation of Cu/In compound. The Cu Se precursors were first annealed to grow uniform and conductive Cu2Se surface. After deposition of the four layers precursors, two steps annealing was employed to form Cu2Se-In2Se3 precursors. Transforming Cu2Se-In2Se3 to CIS required less thermal energy. Therefore, high quality CIS film can be synthesized by two steps annealing due to its high crystallinity. The properties of the CIS films were characterized by scanning electron microscopy (SEM), X-ray Diffraction (XRD), and Raman Spectra.
A Study of Trimethylsilane (3MS) and Tetramethylsilane (4MS) Based alpha-SiCN:H/alpha-SiCO:H Diffusion Barrier Films
(2012-03-01)
Chen, Sheng-Wen
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Wang, Yu-Sheng
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Hu, Shao-Yu
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Lee, Wen-Hsi
;
Chi, Chieh-Cheng
Amorphous nitrogen-doped silicon carbide (alpha-SiCN:H) films have been used as a Cu penetration diffusion barrier and interconnect etch stop layer in the below 90-nanometer ultra-large scale integration (ULSI) manufacturing technology. In this study, the etching stop layers were deposited by using trimethylsilane (3MS) or tetramethylsilane (4MS) with ammonia by plasma-enhanced chemical vapor deposition (PECVD) followed by a procedure for tetra-ethoxyl silane (TEOS) oxide. The depth profile of Cu distribution examined by second ion mass spectroscopy (SIMs) showed that 3MS alpha-SiCN:H exhibited a better barrier performance than the 4MS film, which was revealed by the Cu signal. The FTIR spectra also showed the intensity of Si-CH3 stretch mode in the alpha-SiCN:H film deposited by 3MS was higher than that deposited by 4MS. A novel multi structure of oxygen-doped silicon carbide (SiC:O) substituted TEOS oxide capped on 4MS alpha-SiC:N film was also examined. In addition to this, the new multi etch stop layers can be deposited together with the same tool which can thus eliminate the effect of the vacuum break and accompanying environmental contamination.
A Study on the Diffuse Mechanism and the Barrier Property of Copper Manganese Alloy on Tantalum
(2015-05-01)
Su, Ying-Sen
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Lee, Wen-Hsi
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Chang, Shih-Chieh
;
Wang, Ying-Lang
;
照明與能源光電研究所
In this paper, the electrical and material properties of CuMn/silicon oxide (SiO2) and CuMn/tantalum (Ta)/SiO2 were investigated, and an optimized concentration of Mn in the CuMn alloy as barrier layers in these two structures was also determined. CuMn alloy (0 similar to 10 atomic % Mn) deposited on SiO2 and Ta were used in this paper. A diffusion barrier layer self-formed at the interface during annealing, and the growth behavior was found to follow a logarithmic rate law. The microstructures of the CuMn films were analyzed by transmission electron microscopy and could be correlated with the electrical properties of the CuMn films. After thermal treatment, only Cu-5 at.% Mn/ SiO2 successfully avoided the diffusion of Cu atoms. Thermal stability of the films grown on Ta/SiO2 was found to be better than that on SiO2. When a Ta layer was added, the Mn atoms diffused not only to the interface, but also to the grain boundaries in the Ta layer and the interface between Ta and SiO2. This phenomenon could be explained by the surface energy. As the thickness of CuMn shrunk from 150 to 50 nm and the sample was covered with a 100-nm-thick Cu layer, the amount of Mn atoms increased at the interface of CuMn/Ta. This is because the Cu layer had higher chemical potential which induced the Mn atoms to move toward the Ta layer and reduced the amount of Mn atoms in Cu after heat treatment.
A Study on the Plating and Wetting Ability of Ruthenium-Tungsten Multi-layers for Advanced Cu Metallization
(2016-01-01)
Kuo, Tai-Chen
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Su, Yin-Hsien
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Lee, Wen-Hsi
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Liao, Wei-Hsiang
;
Wang, Yu-Sheng
In this study, the plating and wetting ability of Cu/Ruthenium-Tungsten (RuW)/silicon oxide (SiO2) multi-layer stacks were investigated. RuW alloy films were prepared on a SiO2 layer by sputtering, followed by a deposition of a Cu thin film by electroplating. Scanning electron microscopy (SEM) top view images shows that Cu films can be electroplated on RuW, with smaller Cu nuclei size but in a more highly concentrated and uniform distribution than Cu films electroplated on Ta or TaN. The rate of Cu nucleation decreases and larger Cu clusters were formed on the RuW alloy films with increasing W content. Cu/RuW/SiO2 samples were annealed at 400 degrees C for 30 min and then characterized using SEM. There were fewer pin holes on the surface of a pure Cu/Ru stack compared to Cu/RuW multilayers. Cu/RuW/SiO2 multi-layers had fewer pin holes than Cu/Ta/SiO2 structures processed under similar conditions. The wetting angle, measured by SEM, of Cu on a RuW substrate (43 degrees) was still lower than that of Cu on a Ta substrate (123 degrees), which suggests that the adhesion strength of Cu onto RuW alloy is better than that onto Ta.
A study on the plating and wetting ability of ruthenium-tungsten multi-layers for advanced Cu metallization
(2016-08-16)
Kuo, Tai-Chen
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Su, Yin-Hsien
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Lee, Wen-Hsi
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Liao, Wei-Hsiang
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Wang, Yu-Sheng
In this study, the plating and wetting ability of Cu/Ruthenium-Tungsten (RuW)/silicon oxide (SiO2) multi-layer stacks were investigated. RuW alloy films were prepared on a SiO2 layer by sputtering, followed by a deposition of a Cu thin film by electro-plating. Scanning electron microscopy (SEM) top view images shows that Cu films can be electroplated on RuW, with smaller Cu nuclei size but in a more highly concentrated and uniform distribution than Cu films electroplated on Ta or TaN. The rate of Cu nucleation decreases and larger Cu clusters were formed on the RuW alloy films with increasing W content. Cu/RuW/SiO2 samples were annealed at 400 degrees C for 30 min and then characterized using SEM. There were fewer pin holes on the surface of a pure Cu/Ru stack compared to Cu/RuW multilayers. Cu/RuW/SiO2 multi -layers had fewer pin holes than Cu/Ta/SiO2 structures processed under similar conditions. The wetting angle, measured by SEM, of Cu on a RuW substrate (43) was still lower than that of Cu on a Ta substrate (123 degrees), which suggests that the adhesion strength of Cu onto RuW alloy is better than that onto Ta. Preliminary studies of Cu diffusion through 25 nm RuW layers at 650 degrees C showed no Cu penetration into the underlying Si in a Cu/RuW/Si multi-layer test structure. (C) 2016 Elsevier B.V. All rights reserved.
An electroplating method for copper plane twin boundary manufacturing
(2013-10-01)
Wang, Yu-Sheng
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Lee, Wen-Hsi
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Chang, Shih-Chieh
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Nian, Jun-Nan
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Wang, Ying-Lang
A twin boundary is a special kind of grain boundary that plays an important role in the deformation process of nanocrystalline metals, as it may affect the migration of atoms and electrons in polycrystalline solids, resulting in different electrical and mechanical properties. In this study, plane twin structures were introduced into an electroplated copper film by an electroplating method that inserts an interlayer film with a very small current density (<3 mA/cm(2)). It was found that the small-current interlayer formed a demarcation line for copper grain growth, and enhanced the twin boundaries by self-annealing at room temperature. Based on this, a method was developed to manufacture multi-plane twin boundaries to improve electron migration. Transmission electron microscopy, focused ion beam analysis, and secondary ion mass spectrometry were employed to examine this interesting phenomenon. (C) 2013 Elsevier B. V. All rights reserved.
Effect of Annealing on the Microstructure and Electrical Property of RuN Thin Films
(2011)
Wu, Chia-Yang
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Lee, Wen-Hsi
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Chang, Shih-Chieh
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Cheng, Yi-Lung
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Wang, Ying-Lang
Ruthenium (Ru) and ruthenium nitride (RuN) thin films have been investigated as candidates for barrier layers in copper (Cu) damascene processes. In order to study the thermal stability of the Ru and RuN films, the as-deposited films were annealed by rapid thermal annealing (RTA), and the film resistance was real-time measured by a four-point probe, which was embedded in the RTA tool. The X-ray diffraction data show that the grain size of Ru decreased with the increase of the nitrogen (N) content. The Ru phases gradually changed to the RuN phases, and the resistivity of the RuN films decreased with annealing time due to nitrogen effusion. Discontinuous RuN films were found when the annealing temperature was higher than 800 degrees C and then caused a poor Cu diffusion barrier property. We also demonstrated that the Cu film could be directly electroplated on the RuN films with adequate adhesion. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3537825] All rights reserved.
Effect of bis-(3-sodiumsulfopropyl disulfide) byproducts on copper defects after chemical mechanical polishing
(2008-01-01)
Hung, Chi-Cheng
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Lee, Wen-Hsi
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Hu, Shao-Yu
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Chang, Shih-Chieh
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Chen, Kei-Wei
In the semiconductor metallization process, the superior gap-fill capability of copper (Cu) electroplating is mainly due to external additives, such as bis-(3-sodiumsulfopropyl disulfide) (SPS), which is used as an accelerator. This study demonstrates that the byproducts of SPS induced Cu defects after a chemical-mechanical-polishing (CMP) process. In conventional cyclic-voltammetric-stripping analysis, the byproducts generated from organic additives are very difficult to quantify. In this study, the authors used mass-spectrum analysis to quantify SPS byproducts and found that the SPS byproduct, 1,3-propanedisulfonic acid, correlated with the formation of Cu defects because it influenced the properties of electroplated Cu films and the chemical corrosion rate, then induced defects after the CMP process. (C) 2008 American Vacuum Society.
Effect of Electrolyte Composition on Cu Stripping of Pt Contact Pins in Semiconductor Cu Electroplating Process
(2011-11-01)
Hu, Shao-Yu
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Lee, Wen-Hsi
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Chang, Shih-Chieh
;
Wang, Ying-Lang
;
照明與能源光電研究所
In Cu electroplating processes, the wet-contact pins are deposited with Cu films. The Pt contact pins should be stripped to remove extra Cu films to maintain contact quality and plating efficiency. However, the stripping behavior is affected by electrolyte composition. The proportion of copper sulphate and sulfuric acid changes the conductivity, pH, and cupric-ion concentration of the electrolyte solution. In this study, an electrochemistry analysis system is employed to characterize the behavior of the Pt stripping process in electrolytes having various electrolyte proportions. It was found that increasing the copper sulphate and sulfuric acid concentrations suppresses the Cu stripping current but enhances the water electrolysis reaction on the Pt surface. Copper sulphate decreased the rate of oxide dissolution and cupric diffusion. The dissolution rate was limited by denser cation layer. Sulfuric acid decreased the dissolubility of cupric ions and suppressed the electrode from releasing more cupric ions. There is no significant influence of additives such as leveler suppressor on the stripping. Minute quantity of HNO3 and H3PO4 were also added to the plating electrolyte. The additional acid HNO3 eliminated the inhibition form dense cupric layer and enhanced the stripping performance without changing the quality of the deposited films during the plating process.
Effect of tungsten incorporation in cobalt tungsten alloys as seedless diffusion barrier materials
(2017-03-05)
Su, Yin-Hsien
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Kuo, Tai-Chen
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Lee, Wen-Hsi
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Wang, Yu-Sheng
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Hung, Chi-Cheng
With the increase in the aspect ratio of the interconnect features in integrated circuits, the direct electroplating of Cu on diffusion barrier without sputtered Cu seed layers is attracting more and more attention. In this study, direct electroplating of Cu onto sputtered CoW films with various W concentration in acidic CuSO4 solution is investigated. Also, the adhesion and anti-diffusion properties of the CoW thin films for Cu are explored. The results show that Cu films cannot be electrodeposited on thin Co layers due to corrosion of Co in the acidic bath. For CoW alloys, higher W concentration is found to be beneficial for suppressing corrosion of CoW films and also improving the thermal stability. However, on the surface of Cu/CoW films with high W concentration, Cu agglomeration and pin-holes were found after annealing, indicating poor adhesion between Cu and high W-content CoW alloys. In this study, CoW alloys with moderate W concentration around 50% are found to be a direct platable material which also demonstrates desirable adhesion and anti-diffusion characteristics for Cu interconnects application. (C) 2017 Elsevier B.V. All rights reserved.
Effect of Under-Layer Treatment of Ta/TaN Barrier Film on Corrosion Between Cu Seed and Ta in Chemical-Mechanical-Polishing Slurry
(2010-07-01)
Lee, Wen-Hsi
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Hung, Chi-Cheng
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Wang, Yu-Sheng
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Chang, Shih-Chieh
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Wang, Ying-Lang
Tantalum/tantalum nitride (Ta/TaN(x)) composite film is widely used as a copper (Cu) diffusion barrier layer. In order to reduce via-resistance, an additional argon (Ar) re-sputtering process is used to thin the barrier thickness at the feature bottom. In this study, the effect of (Ar) re-sputtering of the under-layer of TaN(x) barrier films on the corrosion between Cu seeds and upper Ta films in chemical-mechanical-polishing (CMP) slurries was investigated. The results show that Ar re-sputtering of the under-layer of the TaN(x) barrier has a strong influence on the corrosion of Cu seeds and Ta films. The equivalent circuit, simulated using data from electrochemical analysis, reveals changes in resistance and capacitance elements of the Cu-Ta electrochemical system, proving that the phase transformation of upper Ta films under different TaN(x) conditions leads to different degrees corrosion of Cu seeds and the Ta films.
Effects of (002) beta-Ta barrier on copper chemical mechanical polishing behavior
(2013-02-01)
Wang, Yu-Sheng
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Chen, Kei-Wei
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Cheng, Min-Yuan
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Lee, Wen-Hsi
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Wang, Ying-Lang
This study proposes that the corrosion resistance of copper film correlates well with underlying barrier's orientation. To test the hypothesis, we performed X-ray diffraction, conducted copper removal rate experiments after chemical mechanical polishing, and tested static potentiodynamic polarization. The results all show that copper deposited on strongly (002) oriented beta-Ta barrier layer demonstrated better chemical resistance against surface reaction with the slurry for strong copper (111) orientation. The findings were consistent with the result of the chronoamperometric test at 0.3 V in which the more passive film formed on the composite film with (002) beta-Ta underlying barrier. (C) 2012 Elsevier B.V. All rights reserved.
Enhancement of the Thermal Stability of TiN(x) Capping Layer on the Nickel Silicides
(2011-04-01)
Wu, Chi-Ting
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Lee, Wen-Hsi
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Chang, Shih-Chieh
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Cheng, Yi-Lung
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Wang, Ying-Lang
In this study, the effects of TiN(x) capping layers on the thermal stability of nickel silicides have been investigated in a rapid thermal annealing (RTA) process. Various TiN(x) films were deposited on the nickel film by different N(2) flow rates. It was found that the TIN(x) capping layer could improve the thermal stability of nickel silicides and suppress silicide agglomeration. The TIN(x) film deposited with higher N(2) flow rates had better thermal stability than those with lower N(2) flow rates. The corrosion behaviors of the TIN(x) films deposited with various N(2) flow rates and nickel films in the H(2)SO(4):H(2)O(2) (4:1) solution were investigated. We found that the corrosion currents (I(corr)) of the nickel and NiSi films were much higher than those of the TiN(x) films, while the I(corr) of the TiN(x) films deposited with higher N(2) flow rates was much lower than that of the TiN(x) films deposited with lower N(2) flow rates.
Enhancement of the Thermal Stability of TiNx Capping Layer on the Nickel Silicides
(2011-04-01)
Wu, Chi-Ting
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Lee, Wen-Hsi
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Chang, Shih-Chieh
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Cheng, Yi-Lung
;
Wang, Ying-Lang
In this study, the effects of TiNx capping layers on the thermal stability of nickel silicides have been investigated in a rapid thermal annealing (RTA) process. Various TiNx films were deposited on the nickel film by different N-2 flow rates. It was found that the TINx capping layer could improve the thermal stability of nickel silicides and suppress silicide agglomeration. The TINx film deposited with higher N-2 flow rates had better thermal stability than those with lower N-2 flow rates. The corrosion behaviors of the TINx films deposited with various N-2 flow rates and nickel films in the H2SO4:H2O2 (4:1) solution were investigated. We found that the corrosion currents (I-corr) of the nickel and NiSi films were much higher than those of the TiNx films, while the I-corr of the TiNx films deposited with higher N-2 flow rates was much lower than that of the TiNx films deposited with lower N-2 flow rates.
Fabrication of Vertically Stacked Nanosheet Junctionless Field-Effect Transistors and Applications for the CMOS and CFET Inverters
(2020-09-01)
Sung, Po-Jung
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Chang, Shu-Wei
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Kao, Kuo-Hsing
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Wu, Chien-Ting
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Su, Chun-Jung
In this study, conventional CMOS and complementary field-effect transistor (CFET) inverters based on a vertically stacked-nanosheet (NS) structure were fabricated. The NS below 8-nm channel layer thickness (T-Si) was obtained by dry etching and wet etching processes. The channel thickness is controlled by dry etching, and the channel width was shrunk down by wet etching. Compared to single nanowire field-effect transistors (NSFETs), stacked NSFETs exhibit higher ON-current performance. For the CMOS inverter, the voltage transfer characteristics (VTCs) could be matched much better by adjusting the channel widths and layers for N-channel MOSFET (NFET) and P-channel MOSFET (PFET), respectively. For the CFET inverter, layout areas could be reduced and requires less number of lithographic and ion implantation steps contrary to the CMOS inverter. However, we observe that the VTCs of the CFET inverters still show asymmetric behavior due to the difficulties of adjustment in NS layers and systematic behavior of threshold voltages for NFETs/PFETs. This work experimentally demonstrates the CMOS and CFET inverters on the vertically stacked NS structure, which is promising for system-on-panel (SoP) and 3-D-ICs applications.
Investigation of Barrier Property of Copper Manganese Alloy on Ruthenium
(2015-03-01)
Su, Yin-Hsien
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Wu, Sze-Ann
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Wu, Chia-Yang
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Wang, Ying-Lang
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Lee, Wen-Hsi
This paper investigates the properties of CuMn/Ru/SiO2. The optimal concentration of Mn in the CuMn alloy as a barrier layer in this structure is determined. The properties of CuMn/Ru/SiO2 are compared to those of CuMn/SiO2 and CuMn/Ta/SiO2. The electrical and material properties of CuMn (010 at.% Mn) alloy films deposited on SiO2, Ta, and Ru are studied. A diffusion barrier layer self-formed at the interface during annealing, and the growth behavior followed a logarithmic rate law. The microstructures of the CuMn films are analyzed using transmission electron microscopy and are correlated with the electrical properties. After thermal treatment, only Cu-5 at.% Mn/SiO2 did not exhibit a diffusion of Cu atoms. After annealing, the thermal stability of films grown on Ru/SiO2 was better than that of films grown on SiO2 and Ta/SiO2. When a Ta or Ru layer was added, the Mn atoms diffused not only to the interface but also to the grain boundaries in the under layer and to the interface between the under layer and SiO2. The tolerance of Mn content increased when the Ru layer was used, and thus, CuMn/Ru prevented the diffusion of Cu after heat treatment at 600 degrees C for 30 min.
Investigation of the Galvanic Effect between RuN Barriers and Cu Seed Layers
(2011-12-01)
Wu, Chia-Yang
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Lee, Wen-Hsi
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Chang, Shih-Chieh
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Wang, Ying-Lang
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照明與能源光電研究所
In this study, we investigated the galvanic effect between the Cu metals and ruthenium nitride (RuNx) films that were deposited at various nitrogen (N-2) gas flow rates in chemical mechanical polishing slurries. It was found that the galvanic corrosion of the RuNx films was inhibited with increasing N-2 gas flow ratio, whereas the galvanic corrosion of the Cu seed layers was enhanced. Electrochemical impedance spectroscopy showed that the galvanic corrosion resistance of RuNx increased and that of the ruthenium oxide layer decreased as N-2 flow ratio increased. This was because the increase in the N content in the RuNx films inhibited the corrosion and oxidation of the Ru metals. (C) 2011 The Japan Society of Applied Physics
Investigation the Electroplating Behavior of Self Formed CuMn Barrier
(2013-08-01)
Wu, Chia-Yang
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Lee, Wen-Hsi
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Chang, Shih-Chieh
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Wang, Ying-Lang
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照明與能源光電研究所
The electrical and material properties of Copper (Cu) mixed with [0 similar to 10 atomic% manganese (Mn)] and pure Cu films deposited on silicon oxide (SiO2)/silicon (Si) are explored. Cu electroplating on self formed CuMn barrier was investigated with different Mn content. The electrochemical deposition of the Cu thin film onto the electrode using CuMn barrier was investigated. Scanning electron microscopic (SEM) micrographs of copper electroplating on CuMn films were examined, and the copper nucleation behaviors changed with the Mn content. Since the electrochemical impedance spectroscopy (EIS) is widely recognized as a powerful tool for the investigation of electrochemical behaviors, the tool was also used to verify the phenomena during plating. It was found that the charge-trasfer impedance decrease with the rise in the Mn content below 5%, but increase with the rise in the Mn content higher than 5%. The result was corresponded to the surface energy, the surface morphology, the corrosion and the oxidation of the substrate.
Pulsed Electrodeposition of CuInSe(2) Thin Films onto Mo-Glass Substrates
(2011-01-01)
Hu, Shao-Yu
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Lee, Wen-Hsi
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Chang, Shih-Chieh
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Cheng, Yi-Lung
;
Wang, Ying-Lang
In this study, copper indium selenide (CIS) films were deposited by pulsed electrodeposition with multi potentials to control the atomic ratio of the CIS film and improve the deposition uniformity. It was found that smaller duty cycle and pulsed period enhanced the cathodic current due to ion replenishment. The results show that the Cu/In ratio was significantly influenced by reverse voltage of pulsed electrodeposition. The uniformity of the CIS films can be improved by proper reverse voltage. The deposition rate did not decrease in direct proportion to the duty cycle because the plating current was enhanced by the pulse effect. The pulsed deposited CIS film with optimized composition show smaller grain size, smoother microstructure, and less secondary phase than constant deposited film. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3567762] All rights reserved.
Pulsed Electrodeposition of CuInSe2 Thin Films onto Mo-Glass Substrates
(2011-01-01)
Hu, Shao-Yu
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Lee, Wen-Hsi
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Chang, Shih-Chieh
;
Cheng, Yi-Lung
;
Wang, Ying-Lang
In this study, copper indium selenide (CIS) films were deposited by pulsed electrodeposition with multi potentials to control the atomic ratio of the CIS film and improve the deposition uniformity. It was found that smaller duty cycle and pulsed period enhanced the cathodic current due to ion replenishment. The results show that the Cu/In ratio was significantly influenced by reverse voltage of pulsed electrodeposition. The uniformity of the CIS films can be improved by proper reverse voltage. The deposition rate did not decrease in direct proportion to the duty cycle because the plating current was enhanced by the pulse effect. The pulsed deposited CIS film with optimized composition show smaller grain size, smoother microstructure, and less secondary phase than constant deposited film. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3567762] All rights reserved.