Browsing by Author "Wu, YL"

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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
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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.
Comment on "Generic universal switch blocks"
(2002-01-01)
Fan, HB
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Wu, YL
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Chang, YW
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資訊工程學系
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Department of Computer Science
In the paper [5], the authors defined the well-structured symmetric switch block M-N,M-W and showed that M-N,M-W is universal for any pair of positive integers N and W, However, we find that this result is partially correct. Here, we show that, when N greater than or equal to 7, M-N,M-W is not universal for odd Ws (greater than or equal to 3) and it is universal for any even W.
Copper surface protection with a completely enclosed copper structure for a damascene process
(2004-01-30)
Wang, TC
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Hsieh, TE
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Wang, YL
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Wu, YL
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Lo, KY
As integrated circuit manufacture moving to copper interconnection for the most advanced products, protection of copper (Cu) surfaces becomes a major challenge for the back-end-of-line manufacturing process. The damages on Cu, such as Cu corrosion and oxidation, are often observed on wafers when exposing bare Cu surface in the presence of moisture and/or acidic gases. Furthermore, the Cu oxide results in poor adhesion both at Cu/barrier layer and Cu/stop layer interfaces. In this work, a novel Cu dual damascene structure which completely encloses the Cu surface with a tantalum nitride layer is presented. This capping layer avoids the Cu corrosion and oxidation due to its ability to keep moisture and acid off and away from the Cu surface. (C) 2003 Elsevier Science B.V. All rights reserved.
Deformation and fracture of Al2O3/Al-Zn-Mg-Cu metal matrix composites at room and elevated temperatures
(2000-04-30)
Wu, YL
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Chao, CG
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材料科學與工程學系
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Department of Materials Science and Engineering
Al2O3/Al-Zn-Mg-Cu metal matrix composites containing 2.22 similar to 3.08 wt.% Mg in the matrix alloys have been fabricated by squeeze casting. The aim of the present study is to investigate the deformation and fracture behavior of the composites at RT (room temperature) and elevated temperature. Optical microscopy, scanning electron microscopy and image analysis were used to examine and to analyze the details of the microstructure and the fracture surface. Tensile tests were utilized to evaluate the mechanical properties from 25 to 400 degrees C. The yield stress (YS) values and UTS values for all the composites were larger than those of monolithic alloys. The UTS values for composites and monolithic alloys increased with increasing Mg content. Elevated temperature tests indicated a good strength retention for the composites; especially, UTS values of the composites showed an improvement of 18% exceeds that of the monolithic alloys from 200 to 300 degrees C. Significant dynamic strain aging occurred for composites; however, recovery and softening remained the dominant process for monolithic alloys in the range 25-300 degrees C. (C) 2000 Elsevier Science S.A. 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
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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.
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.
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.
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.