Browsing by Author "Cheng, YL"

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A 1.8 V, 10 Gbps fully integrated CMOS optical receiver analog front end
(2004)
Chen, WZ
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Cheng, YL
;
Lin, DS
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
A fully integrated 10 Gbps optical receiver analog front-end, includes a trans-impedance amplifier (TIA) and a limiting amplifier (LA), is fabricated using a 0.18 mum CMOS technology. The receiver front-end provides a conversion gain up to 85 dBOmega and -3 dB bandwidth of 7.6 GHz. The sensitivity of the optical receiver is - 13 dBm at a bit-error rate of 10(-12) with 2(31)-1 pseudo-random bits. 3-D symmetric transformers are utilized in the AFE design for bandwidth enhancement.
A 1.8-V 10-Gb/s fully integrated CMOS optical receiver analog front-end
(2005-06-01)
Chen, WZ
;
Cheng, YL
;
Lin, DS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A fully integrated 10-Gb/s optical receiver analog front-end (AFE) design that includes a transimpedance amplifier (TIA) and a limiting amplifier (LA) is demonstrated to require less chip area and is suitable for both low-cost and low-voltage applications. The AFE is fabricated using a 0.18-mu m CMOS technology. The tiny photo current received by the receiver AFE is amplified to a differential voltage swing of 400 mV((pp)). In order to avoid off-chip noise interference, the TIA and LA are dc-coupled on the chip instead of ac-coupled though a large external capacitor. The receiver front-end provides a conversion gain of up to 87 dB Omega and -3 dB bandwidth of 7.6 GHz. The measured sensitivity of the optical receiver is -12 dBm at a bit-error rate of 10(-12) with a 2(31) -1 pseudorandom test pattern. Three-dimensional symmetric transformers are utilized in the AFE design for bandwidth enhancement. Operating under a 1.8-V supply, the power dissipation is 210 mW, and the chip size is 1028 mu m x 1796 mu m.
Characterization and reliability of low dielectric constant fluorosilicate glass and silicon rich oxide process for deep sub-micron device application
(2001-11-01)
Cheng, YL
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Wang, YL
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Liu, CW
;
Wu, YL
;
Lo, KY
Fluorosilicate Glass (FSG) with low dielectric constant currently has been replaced as an alternative to SiO2 for device speed improvement. However, several integration aspects, such as Fluorine (F) distribution, F thermal stability, gap fill capability, capacitance reduction and via resistance of FSG prepared by the high density plasma (HDP) chemical vapor deposition (CVD) method are of concern for sub-0.18-mum devices. In this study, HDP-FSG films show different F concentrations at different locations on an 8-inch wafer. In addition, the FSG film shows poor thermal stability and F diffuses out of the film after high temperature annealing and the pressure cook test (PCT). However, the thermal stability of FSG film can be improved by capping with an oxide layer. The results indicate that silicon rich oxide (SRO) has a better effect at blocking the F diffusion out of FSG films at high temperature than plasma enhanced oxide (PE-OX). For the gap fill capability, HDP-FSG can fill all 0.23-mum gaps and some of the 0.21-mum gaps with an aspect ratio <3.8 but not the 0.19-mum gaps. A 8000 Angstrom HDP-FSG film with 600 Angstrom USG liner and 2000 Angstrom cap layer shows approximately 7.5 to 7.7% capacitance reduction on 0.23/0.23-mum gaps when compared with USG (undoped silicate glass). In addition, FSG has a larger capacitance reduction on the wider metal lines than the thinner metal lines at the same gap size due to a capacitance fringe effect. The via resistance for 0.26 mum unlanded via (which allow minor photo mis-alignment) of HDP-FSG film is also similar to that of USG. (C) 2001 Elsevier Science B.V. All rights reserved.
Characterization and thermal stability of fluorosilicate glass films deposited by high density plasma chemical vapor deposition with different bias power
(2006-03-01)
Hsiao, WC
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Liu, CP
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Wang, YL
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Cheng, YL
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材料科學與工程學系
High-density plasma chemical vapor deposition (HDP-CVD) fluorosilicate glass (FSG) films were evaluated for the application of intermetal dielectric (IMD) materials in current devices. Film characteristics were examined as a function of deposition/sputter etch (D/S) ratio, which was controlled by the bias power in HDP-CVD. FTIR spectra show that the positions of Si-O and Si-F peaks are independent of the bias power, but the Si-O shifted to a higher wave number and Si-F-2 appeared upon annealing for the films deposited at lower bias power. Stress hysteresis of the FSG films after the first thermal cycle shows a nonequilibrium nature of the microstructure related to impurity content, especially for the film deposited with lower bias power. Thermal desorption of H2O, F, O-2 and Ar were examined, while most of the desorption behaviour can be related to the physical pore structure and pore quantity. (c) 2005 Elsevier B.V. All rights reserved.
Comparison of characteristics and integration of copper diffusion-barrier dielectrics
(2006-03-01)
Wang, TC
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Cheng, YL
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Wang, YL
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Hsieh, TE
;
Hwang, GJ
The characteristics of various copper (Cu) barrier layers, including SiN, SiCN, and SiCO, were investigated in this work. Carbon-based barrier films (SiCN and SiCO) improved the dielectric constant and line-to-line capacitance, but led to sacrifice in film deposition rate, diffusion-barrier performance, and adhesion strength to Cu in comparison with SiN films. In addition, SiN and SiCO films showed the superior electromigration (EM) performance and stress-induced void migration (SM) performance, respectively. Furthermore, the reliability results of SM and EM are strongly related to the barrier film stress characteristics and the adhesion strength between Cu layers. Therefore, optimization of the barrier layer stress and the enhancement of the interfacial condition between Cu and barrier films are crucial to significantly improve reliability. (c) 2005 Elsevier B.V. All rights reserved.
Effect of carrier gas on the structure and electrical properties of low dielectric constant SiCOH film using trimethylsilane prepared by plasma enhanced chemical vapor deposition
(2004-12-22)
Cheng, YL
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Wang, Y
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Lan, JK
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Chen, HC
;
Lin, JH
For a low dielectric constant inter-metal dielectric application, the low-k SiCOH film with a dielectric constant of 2.8-3.2 has been deposited by plasma-enhanced chemical vapor deposition (PE-CVD) with trimethylsilane (3MS), oxygen, and the carrier gas. In this work, we present the effects of the carrier gas on the characterizations of the low-k films, including reaction mechanism, the deposition rate, and the mechanical and electrical properties. According to the experimental results, the low-k film in Ar carrier gas exhibits the improvement in deposition rate, nonuniformity, leakage current, and hardness. In addition, the dielectric constant of the deposited low-k film is slightly sacrificed due to the decrease of micropores in the deposited films. (C) 2004 Elsevier B.V. All rights reserved.
Effect of deposition temperature and oxygen flow rate on properties of low dielectric constant SiCOH film prepared by plasma enhanced chemical vapor deposition using diethoxymethylsilane
(2006-02-24)
Cheng, YL
;
Wang, YL
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Hwang, GJ
;
O'Neill, ML
;
Karwacki, EJ
Low dielectric constant (Low-k) films (SiCOH) were deposited from diethoxymethylsiliane [DEMS; SiH(CH3) (OC2H5)(2)] which has two ethoxy groups along with one methyl group attached to the silicon atoms. The deposited films have been characterized for different oxygen flows, ranging from 50 to 250 standard cubic centimeters per minute (seem). The growth rate is increased with the increasing oxygen (O-2) flow. The absorbance spectrum of Fourier transform infrared spectroscopy shows that the frequency of Si-O stretching vibration mode in the SiCOH film is shifted to a higher wave number with the increase of oxygen flow. It is deduced that the oxygen does not participate in a simple oxidative mechanism, and has no apparent impact on the methyl content even if the relative Si-O content of the deposited films is up to an O-2/DEMS flow rate ratio of 1:1. Also, the refractive index is decreased with increasing the oxygen flow and slightly increased with the deposition temperature. The dielectric constant of the SiCOH is investigated between 2.7 and 3.2, depending on the deposition temperature and O-2/DEMS flow rate ratio, which is lower than that of the current OSG films (k=2.9-3.3). SiCOH films deposited with DEMS only exhibit higher mechanical hardness and lower leakage current than those deposited with both DEMS and oxygen. (c) 2005 Elsevier B.V. All rights reserved.
Effect of deposition temperature, on thermal stability in high-density plasma chemical vapor deposition fluorine-doped silicon dioxide
(2004-05-01)
Cheng, YL
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Wang, YL
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Chen, HW
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Lan, JL
;
Liu, CP
Thermal stability of fluorine-doped silicon dioxide films deposited by high-density plasma chemical vapor deposition as a function of deposition temperature were investigated in this study. Both thermal desorption spectrum and annealing test results show that SiOF films deposited above 400 degreesC have better thermal stability. Furnace annealing data indicate that non -Si-F- bonding fluorine does exist in low-deposition-temperature SiOF films. Furthermore, secondary-ion mass spectrometer results also reveal that the fluorine in SiOF films with a lower-deposition temperature is easily diffused out and turned into the underlayer, which results in less thermally stable SiOF films. Moreover, short-loop simulation results have been subsequently tested and it was concluded that the deposition temperature of the SiOF film is extremely important for thermal stability. (C) 2004 American Vacuum Society.
Effect of substrate on the step coverage of plasma-enhanced chemical-vapor deposited tetraethylorthosilicate films
(2003-07-01)
Lan, JK
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Wang, YL
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Chao, CG
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Lo, K
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Cheng, YL
Plasma-enhanced chemical-vapor deposition tetraethylorthosilicate (TEOS) films are extensively used as the interlayer dielectric films in multilevel interconnection processes. When TEOS oxide films were deposited on metal patterns three different substrates, titanium nitride (TiN), aluminum (Al), and oxide (SiO2), were used. This study examines the dependence of these substrates on TEOS step coverage. The deposition rates of TEOS oxide revealed that the SiO2 substrate lead to highest TEOS deposition rate during the initial deposition period of 5 s. Then, the TEOS deposition rate of the substrates was nearly the same. The TiN substrate exhibited the highest sidewall step coverage but the sidewall step coverage of the Al substrate deteriorated due to its granular surface. Additionally, different substrates exhibited different coverage of the bottom step. Moreover, the bottom step coverage exceeded the sidewall coverage for all substrates. (C) 2003 American Vacuum Society.
Heat, moisture and chemical resistance on low dielectric constant (low-k) film using diethoxymethylsilane (DEMS) prepared by plasma enhanced chemical vapor deposition
(2006-02-24)
Cheng, YL
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Wang, YL
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Lan, JK
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Hwang, GJ
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O'Neil, ML
Resistance of low dielectric constant (low-k) dielectrics, deposited using Diethoxymethylsilane (DEMS) precursor and helium (He) carrier gas with or without oxygen (O-2) reaction gas, against heat, moisture stress and chemical treatment is clarified. The low dielectric constant organosilicate glass (OSG) films deposited using DEMS and O-2 is shown to be the most reliable: the dielectric constant are stable even after a heating test at 700 degrees C and a pressure cooker test (PCT) for 168 h. This stability is high enough to ensure the low-k properties throughout fabricating multilevel interconnects and long-term reliability after the fabrication. This is due to the stability of Si-CH3 bonds and more Si-C-Si- bonds, which has high degree of cross-linking. However, the degradation of the dielectric constant occurs after O-2 plasma ashing process. The nitrogen plasma treatment is proposed to prevent the damage from O-2 attack in the low-k films deposited using DEMS precursor. (c) 2005 Elsevier B.V. All rights reserved.
Integration of a stack of two fluorine doped silicon oxide film with ULSI interconnect metallization
(2004-01-15)
Cheng, YL
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Wang, YL
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Liu, CP
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Wu, YL
;
Lo, KY
Recently, fluorosilicate glass (FSG) has received much attention for application in microelectronics manufacturing due to its low dielectric constant and stable gap-filling ability. Although FSG films have been demonstrated as potential inter metal dielectrics (IMD) for sub-micron devices, integrating a stack of two fluorine doped silicon oxide film deposited on a high-density plasma chemical vapor deposition (HDP-CVD) system for gap filling and a plasma-enhanced chemical vapor deposition (PECVD) system for throughput has not been fully investigated. In this research, an excellent and exceptionally stable process was demonstrated for a stack of HDP-CVD FSG and PECVD FSG layers. Cracks that result from multi-level metal technology were eliminated when higher compressive stress PECVD FSG film was implemented as a capping layer. An 11% capacitance reduction was achieved when comparing a stack of FSG films to undoped silicon oxide. No problem occurred for photo, via etching and chemical mechanical polishing of FSG film. The FSG layer stack's via resistance (Rc(-)Via) as well as a full HDP-FSG scheme is comparable. These results are very promising for the integration of FSG films as inter metal dielectric for devices. (C) 2003 Elsevier B.V. All rights reserved.
Integration of MOCVD titanium nitride with collimated titanium and ion metal plasma titanium for 0.18-mu m logic process
(2001-11-01)
Lan, JK
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Wang, YL
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Lo, KY
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Liu, CP
;
Liu, CW
Both collimated titanium (CO-Ti) and ion metal plasma titanium (IMP-Ti) have been widely used for plug liner layers. The focused ion beam (FIB) images of these films show that the IMP-Ti surface is granular and the CO-Ti surface is amorphous. It is concluded that the lower reflectivity and resistivity of IMP-Ti films are caused by the fact that IMP-Ti has a larger grain than that of the CO-Ti films. We define a grain size factor (GF) and find that the activation energy of grain growth of IMP-Ti film is 3.8 times larger than that of CO-Ti film. The electric measurement of vias resistance shows that IMP-Ti plug liner gives 13.6% higher via resistance and broader distribution than that of the CO-Ti plug liner. From the experimental data, we can conclude that there are three factors that make the IMP Ti plug liner process have higher vias resistance. These three factors are IMP-Ti resistivity, IMP-Ti thickness and CVD TiN thickness. (C) 2001 Elsevier Science B.V. All rights reserved.
Mechanisms of circular defects for shallow trench isolation oxide deposition
(2003-09-01)
Lan, JK
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Wang, YL
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Liu, CP
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Chao, CG
;
Ay, CY
Shallow trench isolation (STI) is extensively used as the isolation method beyond 0.18 mum generation. This study explored the formation of circular defects in high-density plasma (HDP) STI deposition. Circular defects were caused by the burst flow of silane reactive gas. The defect maps were coincident with the silane flow field. Fourier transform infrared and secondary-ion-mass spectroscopy data exhibited that the silane-burst flow formed a silicon rich oxide (SRO) film. This SRO film existed between the STI oxide and liner oxide. The circular defects were easily found using optical microscopy (OM) for STI with SRO film. Scanning electron microscopy and transmission electron microscopy photographs show that these defects include bubbles and concavities. When SRO fully covers the liner oxide, bubbles easily form by delamination between SRO film and liner oxide. This correlates with the high tensile stress produced by the SRO film. Besides this, higher STI deposition temperatures yield more bubbles. When SRO discontinuously forms on the liner oxide, the concavities were induced by the variation of STI deposition rate on SRO film and liner oxide. The surface charge difference between the SRO film and the liner oxide is the driving force for the generation of concavities. (C) 2003 American Vacuum Society.
Moisture resistance and thermal stability of fluorine-incorporation siloxane-based low-dielectric-constant material
(2004-01-30)
Cheng, YL
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Wang, YL
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Wu, YL
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Liu, CP
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Liu, CW
The low dielectric constant (low-k) of organo-silica-glass (OSG) and fluorine-incorporated OSG (OFSG) materials produced from plasma-enhanced chemical vapor deposition of trimethylsilane are thermally stable to greater than 600 degreesC. FTIR analysis indicates that Si-CH3 bonds and Si-F bonds remain intact to temperatures well above that normally encountered during integrated circuit manufacture, allowing these materials to maintain a low-k value. While OFSG materials proved to have less hydrolytic resistant than their non-fluorinated analogs during high pressure, high temperature water exposure (pressure cooker test), their leakage current was found to be lower than OSG films before and after wafer exposure. The measured properties of OFSG blanket films suggest that this material is sufficiently robust to ensure stability of reliability after the fabrication. (C) 2003 Elsevier B.V. All rights reserved.
Monitor and eliminate the circular defects in HDP-STI deposition through oxynitride/oxide composite liner
(2004-01-30)
Lan, JK
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Wang, YL
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Liu, CP
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Lee, WH
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Ay, C
This paper investigates. the monitor and elimination methods for the circular defects in high-density-plasma shallow trench isolation (HDP-STI) deposition process. The optical measurement method can monitor the circular defects in early stage. When the thickness of silane-burst film exceeds 7.8 nm, the fit-error can alert the circular defects. The oxynitride/oxide composite liner can eliminate the circular defects. Besides this, the oxynitride/oxide composite liner can also improve the breakdown strength of the STI oxide. The breakdown strength of the STI oxide increases, respectively, 375 and 30% in the wafer center and edge. The uniformity of the STI breakdown strength was reduced from greater than 200% to less than 10% using the composite liner. The traditional N2O plasma treatment for stabilizing the oxynitride film is harmful in the HDP-STI process. The N2O plasma treatment shows the worst circular defect performance. (C) 2003 Elsevier B.V. All rights reserved.
Optimization of post-N-2 treatment and undoped-Si-glass cap to improve metal wring delamination in deep submicron high-density plasma-fluorinated silica glass intermetal dielectric application
(2004-07-01)
Cheng, YL
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Wang, YL
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Lan, JK
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Wu, SA
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Chang, SC
Integration issues of metal line delamination from fluorinated silica glass (FSG) in deep submicron intermetal dielectric applications were investigated in this study. A metal line peeled off after a nonoptimized in situ deposition of undoped-silicon-glass (USG; SiO2) capping layer followed the post-FSG-chemical mechanical polishing N-2 treatment. It was found that higher bias power and longer process time of N-2 treatment led to more active fluorine species diffusing from the FSG films to the USG surface, which might react with subsequent Ti/TiN/W metal layer and result in metal delamination. Using plasma-enhanced N-2 treatment and ex situ USG capping with lower initial deposition temperature by extra cooling step, the stability of the FSG films was improved and resulted in a robust structure without metal peeling. (C) 2004 American Vacuum Society.
Study the impact of liner thickness on the 0.18 mu m devices using low dielectric constant hydrogen silsesquioxane as the interlayer dielectric
(2000-12-01)
Lan, JK
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Wang, YL
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Wu, YL
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Liou, HC
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Wang, JK
The electrical performance of hydrogen silsesquioxane (HSQ) as the interlayer level dielectric (ILD) has been determined by using two-metal-layered test structures to study the impact of oxide liner thickness on the capacitance reduction. In comparison with SiO2, HSQ test structures formed with SiO2 cap and liner or with SiO2 cap only, have 20-27% lower intraline capacitance while 6-16% reduction was observed for fluorosilicate glass (FSG) relative to SiO2. It was found that the capacitance of SiO2/HSQ ILDs did not vary with oxide liner thickness as expected. Similar effects were observed with via resistance measurement. Analysis of the structure shows that wide variation of SiO2/HSQ/SiO2 stack thickness after oxide Chemical Mechanical Polishing (CMP) step changed the expected contribution of liner thickness on the intraline and interlayer capacitance. This thickness variation also has a strong impact on landed/unlanded via resistance. Therefore, a good control of oxide CMP on the ILD stack is needed to reduce the thickness variation of the liner/HSQ/cap ILD stack which in turn will enhance process yields in the 0.18 mum devices. (C) 2000 Elsevier Science B.V. All rights reserved.
X-ray reflectivity and FTIR measurements of N-2 plasma effects on the density profile of hydrogen silsesquioxane thin films
(2001-10-01)
Lee, HJ
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Lin, EK
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Wu, WL
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Fanconi, BM
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Lan, JK
The density depth profile and chemical bond structure of hydrogen silsesquioxane (HSQ) thin films treated with an N-2 plasma with varying power and exposure time were measured using specular X-ray reflectivity (SXR) and Fourier transform infrared (FTIR) spectroscopy. The SXR data indicated that the density profile of an untreated HSQ film is not uniform. At least four layers with different electron densities were required to fit the SXR data. For HSQ films treated with either increasing plasma power or plasma exposure time, the film roughness increased and a densified layer was observed at the film/air interface. The thickness of the densified layer increased with both plasma power and plasma exposure time. In the FTIR spectra of the plasma-treated films, the intensities of the Si-O peaks due to the network structure and the Si-OH peak due to water absorption increased and the intensities of the Si-H peaks decreased. The FTIR data show that the plasma converts the HSQ structure into a SiO2-like structure and are consistent with the densification observed in the SXR measurements. In general, the HSQ film is more sensitive to increasing plasma power than to increasing plasma exposure time. (C) 2001 The Electrochemical Society.