Browsing by Author "Chen, LJ"

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Anti-reflection strategies for sub-0.18-mu m dual damascene structure patterning in KrF 248nm lithography
(1999)
Chou, SY
;
Wang, CM
;
Hsia, CC
;
Chen, LJ
;
Hwang, GW
Finding high performance and low cost anti-reflection strategies is a common goal for all photolithographers. This task is getting tough for dual damascene process than the metal-etch process because the oxide thickness variation enhances the thin film interference effect. In this paper, different ARC strategies using organic and inorganic material were examined to compare their CD control performance in sub-0.18 mu m dual damascene structure for KrF 248nm lithography. The organic bottom ARC (BARC) achieves reflectivity control through modulating its thickness. The first and second minimal points in BARC swing curve were chosen as the film thickness to be evaluated. The inorganic ARC, which referred to dielectric ARC (DARC) using PECVD silicon oxynitride (SiOxNy) in this article, was investigated with single layer and double layer structures. The double-layer DARC structure consists of two layers with different extinction coefficient K values. The optimal refractive index (N, K) and thickness of each ARC structure were calculated from some available photolithography simulators. A PECVD process for DARC growth chat provides easily tunable range of refractive index and thickness was established to meet the DW process requirement fr om simulation. The performances of each ARC structure were evaluated on patterning 0.18 mu m trench and 0.20 mu m via in back-end-of-line (BEOL) dual damascene process. It showed that the double-layer DARC provided the most effective CD control ability among these ARC structures. The double-layer DARC should be one of the most potential candidates for sub-0.18 mu m dual damascene process.
Barrier capabilities of selective chemical vapor deposited W films and WSiN/WSix/W stacked layers against Cu diffusion
(1999-02-01)
Wang, MT
;
Chen, LJ
;
Chen, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work investigates the barrier capability of W layers as well as WSiN/WSix/W stacked layers against Cu diffusion. The VV layers were selectively chemical vapor deposited (CVD) in contact holes to a thickness of about 450 nm using SiH4 reduction of WF6. We found that the CVD-W layers functioned as effective barriers against Cu diffusion, and the Cu/W(450 nm)/p(+)-n junction diodes were able to sustain a 30 min furnace annealing up to 650 degrees C without causing degradation in electrical characteristics. The use of WSiN/WSix/W stacked layers as diffusion layers further improved the thermal stability of Cu/WSiN/WSix/W(450 nm)p(+)-n junction diodes to at least 700 degrees C. The WSix layers were deposited by CVD to a thickness of 75 nm using SiH4/WF6 chemistry, and the subsequent in situ N-2 plasma treatment produced a very thin layer of WSiN on the WSix surface. This thin WSiN layer was very thermally stable and effective in suppressing Cu diffusion, failure of barrier capability for the W films was presumably due to interdiffusion of Cu and Si along grain boundaries of the W films, and the interdiffusion was probably enhanced by the formation of WSi2, The formation of WS(i)2 consumed the W layer and Si substrate, resulting in a volume change in barrier layer, which, in turn, developed local defects, such as microcracks and stress-induced weak points, and thus provided fast paths for Cu diffusion. (C) 1999 The Electrochemical Socity S0013-4651(98)04-036-1. All rights reserved.
Characterization of multilayered Ti/TiN films grown by chemical vapor deposition
(1998-11-02)
Hu, JC
;
Chang, TC
;
Chen, LJ
;
Yang, YL
;
Chang, CY
The resistivity of multilayered Ti/TiN films grown by chemical vapor deposition can be reduced from 240 mu Omega cm (standard sample) to 120 mu Omega cm with NH3 plasma post-treatment for 300 s. Increasing the number of multilayered Ti/TiN mu ms of reduced thickness and a plasma post-treatment technique contributed to reducing the resistivity of TiN films effectively. Smooth multilayered Ti/TiN films were observed by XTEM image. The content of chlorine in the multilayered Ti/TiN film was 1.6 at.%. Therefore, corrosion in the subsequent Al film should be minimized. SIMS depth profiles of the multilayered Ti/TiN sample showed that Ti atom distribution is fairly uniform. The result is in agreement with the observation of XTEM and the measurement of AES depth profiles. The resistivity of multlayered Ti/TiN films can be further reduced to 75 mu Omega cm with an in situ NH3 plasma post-treatment (500 W) for 300 s followed by RTA at 900 degrees C for 60 s. Therefore, low resistivity (<100 mu Omega cm) and low Cl concentration (<2 at.%) CVD TiN films can be achieved by a combination of forming a multilayered Ti/TiN structure, and using NH3 plasma post-treatment and RTA. (C) 1998 Elsevier Science S.A. All rights reserved.
Characterization of TiN film grown by low-pressure-chemical-vapor-deposition
(1997-10-31)
Mei, YJ
;
Chang, TC
;
Hu, JC
;
Chen, LJ
;
Yang, YL
Conformal TiN films were deposited by thermal low-pressure-chemical-vapor-deposition (LPCVD) in a rotating disk reactor, using TiCl4 and NH3 with N-2 as a dilution gas. TiN plug with 0.05 mu m contact size was achieved. No void formation was observed in the TiN plug. The result demonstrated that LPCVD-TiN can be used to fill very small contact holes. The excellent step coverage and uniformity resulted from a surface-reaction-rate-limited deposition. The resistivity of TiN film was reduced to 133 mu Omega cm by in-situ NH3 plasma post-treatment. The concentration of chlorine in the TiN him was measured to be less than 2 atomic % (at.%) by Auger electron spectroscope measurement. For Al deposited on TiN, the Al orientation was found to be dependent on the deposition method of Al film, but not on the underlying TiN orientation. (C) 1997 Elsevier Science S.A.
Chemical mechanical polishing for selective CVD-W
Wang, MT
;
Yeh, WK
;
Tsai, MS
;
Tseng, WT
;
Chang, TC
This work investigates chemical mechanical polishing (CMP) for W-filled contact holes, vias, and trenches by selective chemical vapor deposition. A novel process that combines the CMP technique with selective chemical vapor deposition of tungsten (CVD-W) was employed to remove nail heads due to overgrowth and W-particles on the surface of dielectric due to selectivity loss. The overfilled nail heads and the selectivity loss can be completely removed with very low down-pressure (3 psi) in a very short polishing time (30 s). This indicates that the novel process is very promising for ULSI multilevel interconnection application. The removal rate selectivities of W to thermal oxide, PECVD-TEOS, and BPSG were found to be 47:1, 30:1 and 15:1, respectively, while the selectivities of W to the barrier metals of TiW, Ti and Ta were determined to be 0.6:1, 6:1 and 28:1, respectively. (C) 1997 Elsevier Science S.A.
Chemical mechanical polishing for selective CVD-W
Wang, MT
;
Yeh, WK
;
Tsai, MS
;
Tseng, WT
;
Chang, TC
This work investigates chemical mechanical polishing (CMP) for W-filled contact holes, vias, and trenches by selective chemical vapor deposition. A novel process that combines the CMP technique with selective chemical vapor deposition of tungsten (CVD-W) was employed to remove nail heads due to overgrowth and W-particles on the surface of dielectric due to selectivity loss. The overfilled nail heads and the selectivity loss can be completely removed with very low down-pressure (3 psi) in a very short polishing time (30 s). This indicates that the novel process is very promising for ULSI multilevel interconnection application. The removal rate selectivities of W to thermal oxide, PECVD-TEOS, and BPSG were found to be 47:1, 30:1 and 15:1, respectively, while the selectivities of W to the barrier metals of TiW, Ti and Ta were determined to be 0.6:1, 6:1 and 28:1, respectively. (C) 1997 Elsevier Science S.A.
Chemical mechanical polishing for selective CVD-W
(1997-10-30)
Wang, MT
;
Yeh, WK
;
Tsai, MS
;
Tseng, WT
;
Chang, TC
This work investigates chemical mechanical polishing (CMP) for W-filled contact holes, vias, and trenches by selective chemical vapor deposition. A novel process that combines the CMP technique with selective chemical vapor deposition of tungsten (CVD-W) was employed to remove nail heads due to overgrowth and W-particles on the surface of dielectric due to selectivity loss. The overfilled nail heads and the selectivity loss can be completely removed with very low down-pressure (3 psi) in a very short polishing time (30 s). This indicates that the novel process is very promising for ULSI multilevel interconnection application. The removal rate selectivities of W to thermal oxide, PECVD-TEOS, and BPSG were found to be 47:1, 30:1 and 15:1, respectively, while the selectivities of W to the barrier metals of TiW, Ti and Ta were determined to be 0.6:1, 6:1 and 28:1, respectively. (C) 1997 Elsevier Science S.A.
Chemical mechanical polishing for selective CVD-W
(1997-10-30)
Wang, MT
;
Yeh, WK
;
Tsai, MS
;
Tseng, WT
;
Chang, TC
This work investigates chemical mechanical polishing (CMP) for W-filled contact holes, vias, and trenches by selective chemical vapor deposition. A novel process that combines the CMP technique with selective chemical vapor deposition of tungsten (CVD-W) was employed to remove nail heads due to overgrowth and W-particles on the surface of dielectric due to selectivity loss. The overfilled nail heads and the selectivity loss can be completely removed with very low down-pressure (3 psi) in a very short polishing time (30 s). This indicates that the novel process is very promising for ULSI multilevel interconnection application. The removal rate selectivities of W to thermal oxide, PECVD-TEOS, and BPSG were found to be 47:1, 30:1 and 15:1, respectively, while the selectivities of W to the barrier metals of TiW, Ti and Ta were determined to be 0.6:1, 6:1 and 28:1, respectively. (C) 1997 Elsevier Science S.A.
Coherent control multiphoton processes in semiconductor saturable Bragg reflector with freezing phase algorithm
(2005-03-01)
Chen, MC
;
Huang, JY
;
Chen, LJ
;
光電工程學系
;
Department of Photonics
A freezing phase concept has been proposed for adaptive coherent control with a femtosecond pulse shaper. We applied the scheme to investigate multiphoton processes in InAs quantum dot saturable Bragg reflector (SBR). The optical transition of InAs quantum dots can be revealed in the spectral phase sensitivity plot of second harmonic signal. We also achieved a three-time increase in image contrast on regions with photoluminescent wavelength differing only 18 nm by using coherent control nonlinear optical microscopy. Our results suggest the new freezing phase scheme to be useful for various investigations which require fast and reliable complete-field characterization and coherent control on one setup.
Copper electroplating for future ultralarge scale integration interconnection
(2000-03-01)
Gau, WC
;
Chang, TC
;
Lin, YS
;
Hu, JC
;
Chen, LJ
Copper has received considerable attention during the past few years because of its low electrical resistivity, high melting temperature, and high electromigration resistance. Since electrochemical plating has several advantages compared to physical vapor deposition and chemical vapor deposition due to its low cost and low processing temperature, it becomes the most attractive technique for the implementation of Cu metallization. In this article, we report an electroplating scheme for Cu deposition and study aspects of copper electroplating related to chemical additives effected on Cu deposition. A low resistivity Cu him (similar to 2 mu Omega cm) could be obtained when metallic ion concentration is decreased or current density is increased. The detailed correlation between film resistivity, electrolyte concentration, current density, and film morphology is given in this study. In addition, chemical additives in electrolyte solutions also play important roles in copper electroplating. In this report, thiourea and polyethylene glycol, which are usually added in printing circuit board electroplating to influence nucleation, have been used as gap filling promoters to help Cu filling. The results show that addition of thiourea and polyethylene glycol could help in forming smooth Cu film but does not promote Cu filling ability. Hydroxyl amine sulfate, which has both amino and sulfate groups, is proposed for use as a gap filling promoter in helping Cu electroplating. In this work, we demonstrate that Cu could be electroplated into fine trenches (at 0.3 mu m dimension with aspect ratio of 3) when hydroxyl amine sulfate is present and no voids are formed. (C) 2000 American Vacuum Society. [S0734-2101 (00)07602-8].
Copper electroplating for future ultralarge scale integration interconnection (vol 18, pg 656, 2000)
(2000-09-01)
Gau, WC
;
Chang, TC
;
Lin, YS
;
Hu, JC
;
Chen, LJ
Effects of a new combination of additives in electroplating solution on the properties of Cu films in ULSI applications
(2000-07-01)
Hu, JC
;
Chang, TC
;
Wu, CW
;
Chen, LJ
;
Hsiung, CS
Effects of a new combination of additives in acid electroplating solution on the properties of Cu thin films have been investigated, The electroplated Cu films exhibit an excellent superfilling behavior. 0.18 mu m vias with an aspect ratio exceeding 5 were filled completely without any void or seam. Strong (111) texture was found for the electroplated Cu films. The resistivity of a 450-nm-thick Cu film was measured to be 1.84 mu Omega cm. (C) 2000 American Vacuum Society. [S0734-2101(00)08004-0].
Effects of composition and N-2 plasma treatment on the barrier effectiveness of chemically vapor deposited WSix films
(2000-07-01)
Wang, MT
;
Chuang, MH
;
Chen, LJ
;
Chen, MC
;
電子工程學系及電子研究所
This work investigates the thermal stability of chemically vapor deposited amorphous WSix layers used as a diffusion barrier between Cu and Si substrate, in which the WSix layers were deposited to a thickness of about 50 nm using the SiH4 reduction of WF6 at various SiH4/WF6 how ratios. For 30 min annealing in nitrogen ambient, the effectiveness of the WSix layers as barriers between a copper overlayer and a p(+) -n junction diode decreases as the Si/W atomic ratio, x, increasing from 1 to 1.3. This composition change is obtained by raising the SiH4/WF6 flow ratio from 3 to 50. As deposited, all films are x-ray amorphous. Their resistivity increases roughly linearly with x. The barrier capability of WSix layers can be significantly improved by an in situ N-2 plasma treatment. The N-2 plasma treatment produces a very thin layer of WSiN (about 5 nm) on the surfaces of WSix layers. In particular, the Cu/WSiN/WSix/ p(+) -n junction diodes with the WSix layers deposited with a SiH4/WF6 flow ratio of 3 were able to remain intact up to at least 600 degrees C. (C) 2000 American Vacuum Society. [S0734-211X(00)03204-2].
Effects of corrosion environments on the surface finishing of copper chemical mechanical polishing
(1997-10-31)
Wang, MT
;
Tsai, MS
;
Liu, C
;
Tseng, WT
;
Chang, TC
Copper chemical mechanical polishing (Cu-CMP) was investigated using slurries containing alumina abrasive and various types and concentrations of oxidizer, as well as benezotriazole (BTA) additive. We found that the corrosion rate of copper film decreases with increasing BTA concentration in 3 vol.% HNO3 solution, but the passivation effect of BTA saturates as the concentration reaches about 0.01 M. On the other hand, a small amount of H2O2 in H2O2/XJFW8099 slurry enhances the corrosion rate dramatically, while abundance of H2O2 in the slurry suppresses the corrosion reaction effectively. The polishing rate and its non-uniformity decrease with increasing volume ratio of H2O2 in H2O2/XJEW8099 slurry. A very smooth surface with a removal rate of 363.0 nm/min was obtained using the slurry of 1/1 ratio. Depletion of H2O2 in the slurry can result in more abrasive residuals as well as a rougher surface; the surface roughness increases from 0.3 to 9.9 nm as the H2O2/XJFW8099 ratio decreases from 1/1 to 1/4. Our results indicate that the corrosion rate, polishing rate and surface roughness of copper films are sensitively dependent on the type and concentration of oxidizer as well as the BTA additive. (C) 1997 Elsevier Science S.A.
Effects of isolation materials on facet formation for silicon selective epitaxial growth
(1997-10-20)
Tseng, HC
;
Chang, CY
;
Pan, FM
;
Chen, JR
;
Chen, LJ
Effects of isolation materials on facet formation for low temperature Si selective epitaxial growth (SEG) using Si2H6 have been demonstrated by ultrahigh vacuum-chemical molecular epitaxy (UHV-CME) system. The activation energy of the Si epitaxial growth is 47.35 Kcal/mol. The isolation material includes silicon nitride, wet oxide, and tetraethylorthosilicate (TEOS) oxide. Different isolation materials have different faceting behaviors for the Si epilayer. A silicon nitride mask and a wet oxide mask result in a preferred faceting plane of (111) and (311), respectively. Using a TEOS oxide mask, we obtain a low temperature Si SEG layer without facet and twin formation, The preferred faceting plane orientation for different isolation materials is ascribed to the difference in the interface free energy between the Si layer and the isolation material. (C) 1997 American Institute of Physics.
Electrical reliability issues of integrating thin Ta and TaN barriers with Cu and low-K dielectric
(1999-11-01)
Wu, ZC
;
Wang, CC
;
Wu, RG
;
Liu, YL
;
Chen, PS
This work investigates the integration of very thin sputtered Ta and reactively sputtered TaN barriers with Cu and a low-dielectric-constant (low-K) layer of poly(arylene ether) (PAE-2). It is found that Cu readily penetrates into PAE-2 and degrades its dielectric strength in metal-insulator semiconductor capacitors of Cu/PAE-2/Si structure at temperatures as low as 200 degrees C. Very thin Ta and TaN films of 25 nm thickness sandwiched between Cu and the low-K dielectric served as effective barriers during a 30 min thermal annealing at temperatures up to 400 and 450 degrees C, respectively. We propose a failure mechanism of outgassing induced gaseous stress of PAE-2 under the Ta film to explain its premature barrier degradation. The TaN barrier did not suffer from this gaseous stress problem because of its stronger adhesion to PAE-2 than that of Ta to PAE-2, leading to a better long-term reliability. (C) 1999 The Electrochemical Society. S0013-4651(99)04-046-X. All rights reserved.
Enhanced dopant activation and elimination of end-of-range defects in BF2+-implanted silicon-on-insulator by high-density current
(2001-12-10)
Lin, HH
;
Cheng, SL
;
Chen, LJ
;
Chen, C
;
Tu, KN
Enhanced dopant activation and elimination of end-of-range (EOR) defects in BF2+-implanted silicon-on-insulator (SOI) have been achieved by high-density current stressing. With the high-density current stressing, the implantation amorphous silicon underwent recrystallization, enhanced dopant activation and elimination of the (EOR) defects. The current stressing method allows the complete removal of EOR defects that has not been possible with conventional thermal annealing in the processing of high-performance SOI devices. (C) 2001 American Institute of Physics.
Evaluating the impact of spherical aberration on sub-0.2-micron contact/via hole patterning
(2001)
Chou, SY
;
Lou, JC
;
Lai, CM
;
Liang, FJ
;
Chen, LJ
Several super resolution techniques, such as phase-shifting mask (PSM) and off-axis illumination (OAI), have been reported to extend the resolution limit and increase the depth-of-focus ( DOF) of optical lithography. However, these techniques provide less immunity to spherical aberration than the conventional approaches like chrome binary mask and low coherent illumination. Best focus position shift is the most well known anomalous phenomenon resulted from spherical aberration. In this paper, the origin of best focus shift is explained in pictorial and analytical forms. The phenomenon is evaluated by observing the exposure-defocus windows of sub-0.2mum hole patterns from an 18 % transmission rim-type attenuated PSM combined with several types of illumination. Under high coherent illumination, severe focus shift was observed in sparse patterns as strong phase-shifting effect is applied. For dense hole patterns,, OAI results in abrupt focus position variation at specific pattern pitch. The experimental results show that spherical aberration would induce best focus shift, distortion of process windows, loss of DOF, and shrink-age of iso/dense process window overlap. Two approaches were proposed to suppress the impact of spherical aberration. One is introducing proper amount of phase bias in attenuated PSM to adjust the wave aberration in the lens. The other more feasible method is using a customized illumination. A synthesized illumination aperture was proposed to compensate the focus shift. Excellent lithographic performance was obtained in the experiment from this method.
Fabrication of NiSi2 nanocrystals embedded in SiO2 with memory effect by oxidation of the amorphous Si/Ni/SiO2 structure
(2005-07-01)
Yeh, PH
;
Wu, HH
;
Yu, CH
;
Chen, LJ
;
Liu, PT
NiSi2 nanocrystals embedded in the SiO2 layer exhibiting a memory effect have been formed by dry oxidation of an amorphous Si/Ni/SiO2 structure at 900 degrees C. A pronounced capacitance-voltage hysteresis was observed with a memory window of I V under the 2 V programming voltage for the samples. For dry oxidation at 800 degrees C, no distinct memory effect was detected. The processing of the structure is compatible with the current manufacturing technology of the semiconductor industry. The structure represents a viable candidate for low-power nanoscaled nonvolatile memory devices. (c) 2005 American Vacuum Society.
Focus latitude enhancement of symmetrical phase mask design for deep submicron contact hole patterning
(2001-11-01)
Chou, SY
;
Lou, JC
;
Chen, LJ
;
Shiu, LH
;
Liu, RG
The mechanism of focus latitude enhancement for contact/via hole printing is explained by approximating the axis intensity distribution of an image as a series of cosine functions to characterize the interference between each pair of diffraction beams. It is found that a phase-shifting mask (PSM) with symmetrical assist features improves the depth of focus (DOF) by introducing destructive interference to counterbalance the intensity fluctuation from constructive interference as defocus. A simple formula was derived to represent the capability of focus latitude enlargement. It shows that the extent of enhancement depends on the exposure wavelength and numerical aperture of a projection lens only. Increasing the degree of partial coherence degrades the focal range enlargement because a larger illumination angle elongates the destructive interference pattern in the optical-axis direction to weaken its ability for intensity compensation. On the other hand, the lack of constructive interference in dense hole imaging fails the mask pattern transfer, which limits the application of the phase-shifting method to pattern pitch greater than root2lambda/NA. A tiny amount of spherical aberration results in prominent asymmetrical defocus behavior because the wave deformation in the projection lens shifts the distribution of constructive and destructive interference patterns to opposite defocus directions. The printing characteristics of 0.17 mum contact using an 18% transmission, rim-type attenuated phase-shifting mask are investigated to corroborate our analysis of defocus behavior. The dependence of depth of focus on pattern duty is stressed to elucidate the difference in mechanisms of focus latitude improvements for a sparse hole and periodic dense hole. (C) 2001 American Vacuum Society.