Browsing by Author "Dai, BT"

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A novel technology to reduce the antenna charging effects during polysilicon gate electron-cyclotron-resonance etching
(1996-07-01)
Cheng, HC
;
Kang, TK
;
Ku, TK
;
Dai, BT
;
Chen, LP
A novel technique, which uses Cl-2/O-2 mixed gas in the electron cyclotron resonance (ECR) etching system, has been proposed to remove the antenna charging effect of the MOS capacitors with 5-nm-thick oxides during polysilicon gate etching. The Cl-2/O-2 can cause the trenching effect and prevents the gate oxide from the charging damage. Furthermore, the ECR system can provide high polysilicon/oxide selectivity so that the Si substrate under gate oxide is not directly bombarded by the ions. Consequently, the E(bd) degradation of the MOS capacitors disappears as the trenching effect is apparent by using moderate Cl-2/O-2 mixed gas.
A novel two-step etching to suppress the charging damages during metal etching employing helicon wave plasma
(1998-06-01)
Cheng, HC
;
Lin, W
;
Kang, TK
;
Perng, YC
;
Dai, BT
A two-step etching has been performed to eliminate the plasma charging damages during helicon-wave plasma metal etching without selectivity loss, This technique utilized a normal etching recipe to remove the Al film and followed by an optimized etching recipe for the overetching step. By increasing the bias power and decreasing the source power, the optimum etching recipe can cause the plasma more directionally and reduce the Al charging damages. Eventually, the damage mechanism was also reported.
A study on electrochemical metrologies for evaluating the removal selectivity of AlCMP
(1999)
Chiu, SY
;
Hsu, JW
;
Tung, IC
;
Shih, HC
;
Feng, MS
The in-situ electrochemical measurements were performed for the Al and Ti disks in the various slurries under the polishing or static condition. The slurries used contained Al2O3 abrasive, phosphoric acid, citric acid and hydrogen peroxide. The results showed that the addition of H2O2 could help to form an effective passivating layer on the Al surface. Besides, the addition of H2O2 enhanced Al dissolution. The maximum corrosion potential drop between the abraded and non-abraded Al electrodes corresponded to the possible maximum polishing rate of Al. The novel equipment for in-situ galvanic measurements was designed for evaluating the Al/Ti galvanic couple. It was found that Al dissolution could be suppressed in the slurry with the addition of 6 vol% H2O2 at pH 4. As regards the Al/Ti removal selectivity, the polishing with the addition of 6 vol% H2O2 at pH 4 would mitigate the Al dishing, since the polishing and dissolution of Al could be suppressed while those of Ti could be enhanced.
Aging influence of poly(ethylene glycol) suppressors of Cu electrolytes on gaps filling
(2006-05-01)
Liu, SH
;
Li, TC
;
Chen, C
;
Shieh, JM
;
Dai, BT
In this study, we investigate how the degradation of poly(ethylene glycol) (PEG) additives in Cu electroplating electrolytes influences the gaps filling of damascene features and the roughness of plated surfaces. The cleavage of PEG, whose reaction is enhanced by a high bias current and more plating cycles, not only diminishes the inhibition effect of the electrolytes, but also enables the formation of enormous complexes of short-chain PEG-Cu far from the reacting surfaces. Hence, the more plating cycles performed, the worse the gaps filling characteristic and the rougher the plated surfaces. Furthermore, an overshoot phenomenon on the transient cells voltage for PEG-containing electrolytes is observed and explained well by a dynamic equilibrium between PEG absorption ability and Cu reduction speed. Accordingly, the change in overshoot shape is closely related to PEG aging and this fact is employed to examine the reliability of electrolytes.
Antenna charging effects on the electrical characteristics of polysilicon gate during electron cyclotron resonance etching
(1996-02-01)
Kang, TK
;
Ueng, SY
;
Dai, BT
;
Chen, LP
;
Cheng, HC
The nonuniformity of the induced leakage current in metal oxide semiconductor (MOS) capacitors has been investigated in an electron cyclotron resonance (ECR) system. For plasma-etched MOS capacitors with 5-nm-thick oxides, it is found that the leakage currents induced by plasma etching increase with increasing overetching time. However, additional E(bd) (breakdown held) degradation is not obvious as overetching percentage increases from 10% to 50%. A mechanism based on the antenna charging effect has been proposed to explain the E(bd) electrical characteristics. In accordance with the mechanism, the E(bd) degradation has been significantly reduced by first etching off a narrow peripheral edge around the gate pattern.
Characteristics of fluorinated amorphous carbon films and implementation of 0.15 mu m Cu/a-C : F damascene interconnection
(2001-05-01)
Shieh, JM
;
Suen, SC
;
Tsai, KC
;
Dai, BT
;
Wu, YC
Fluorinated amorphous carbon films (a-C:F) deposited by plasma enhanced chemical vapor deposition with low dielectric constant (K similar to2.3), thermal stability (higher than 400 degreesC) and acceptable adhesion to a cap layer such as SiOF or SiO2 were obtained by varying the range of content ratios between carbon and fluorine, the rf power, the process pressure and the base temperature. Standard x-ray photoelectron spectroscopy and thermal desorption spectroscopy metrologies were employed to characterize the deposited a-C:F films. The damascene pattern with 0.15 mum and an etching selectivity of more than 50 (a-C:F/SiOF, SiO2) was implemented by a mixture of etching gases of N-2+O-2. The bias power, rf power and gas hows were incorporated to optimize the etching recipe for achieving a damascene profile with a high aspect ratio. The scanning electron microscope results showed that a better etch profile can be obtained at higher bias power. In our damascene architecture, the etching stop layer or hard mask of both SiOF and SiO2 was studied. The SiOF, providing a lower dielectric constant than SiO2, would especially reduce the entire effective dielectric constant. Furthermore, we integrated electroplated copper into trenches or vias as small as 0.15 mum, with aspect ratio of 6. (C) 2001 American Vacuum Society.
Characterization of additive systems for damascene Cu electroplating by the superfilling profile monitor
(2000-11-01)
Chiu, SY
;
Shieh, JM
;
Chang, SC
;
Lin, KC
;
Dai, BT
Gap-filling dynamics of several different species of additives for copper electrodeposition was investigated by monitoring the cross section of a partially filled copper profile on the scanning electron microscopy photo. The filling ration Deltay/Deltax between "bottom-up" with "sidewall shift" was found to be proportional to the filing power of additives. The adsorption-diffusion model combined with cathode polarization and cyclic voltammetric stripping measurements was employed to explain the attribution of additives in superfilling phenomena. The superfilling dynamics was achieved under behavior of additives providing selective inhibition gradient within the damascene feature. By means of those analyses, we have optimized the appropriate amount of additives and achieved the superfilling performance for 0.15 mum vias with aspect ratio 6 by an acid-copper electrolyte with polyethylene glycol, Cl-, and 2-mercaptopyridine (2-MP). Due to the additive of 2-MP, chelate formed which enhanced adsorption ability on Cu-0 surface, and the concentration gradient between side-wall shift and bottom-up in the damascene became high enough to attend superfilling electroplating. (C) 2000 American Vacuum Society. [S0734-211X(00)13506-1].
Charging damages to gate oxides in a helicon O-2 plasma
(1997-12-01)
Lin, W
;
Kang, TK
;
Perng, YC
;
Dai, BT
;
Cheng, HC
After the exposure of metal oxide semiconductor (MOS) capacitors with antenna structures to the helicon O-2 plasma, the leakage current. charge-to-breakdown (Q(bd)) and capacitance-voltage (C-V) curves have been characterized to realize the charging damages. The results indicate that the quasi static C-V(QSCV) distortion and Q(bd) depend on the exposure time rather than the antenna ratio. The QSCV and Q(bd) Show a two stage degradation as the exposure time increases. The leakage current increases slightly for the specimens exposed to the plasma for less than 120 s, and increases considerably for the ones with the exposure time of 300 s. Based on these results, the degradation mechanism of gate oxides under the helicon O-2 plasma is established.
Charging damages to gate oxides in a helicon O-2 plasma
(1997-12-01)
Lin, W
;
Kang, TK
;
Perng, YC
;
Dai, BT
;
Cheng, HC
After the exposure of metal oxide semiconductor (MOS) capacitors with antenna structures to the helicon O-2 plasma, the leakage current. charge-to-breakdown (Q(bd)) and capacitance-voltage (C-V) curves have been characterized to realize the charging damages. The results indicate that the quasi static C-V(QSCV) distortion and Q(bd) depend on the exposure time rather than the antenna ratio. The QSCV and Q(bd) Show a two stage degradation as the exposure time increases. The leakage current increases slightly for the specimens exposed to the plasma for less than 120 s, and increases considerably for the ones with the exposure time of 300 s. Based on these results, the degradation mechanism of gate oxides under the helicon O-2 plasma is established.
Chemical mechanical polishing of PSG and BPSG dielectric films: The effect of phosphorus and boron concentration
(1995-12-01)
Liu, CW
;
Dai, BT
;
Yeh, CF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Chemical-mechanical polishing of blanket and patterned oxide films doped with phosphorus and boron has been studied. FTIR was used to characterize the film microstructure. Experimental results show that an increase of phosphorus level promoted the polish rate of PSG film. We also found that increasing the boron content enhanced the polish rate of BPSG films although phosphorus contents is decreased. This implies that boron is more effective than phosphorus in enhancing the polishing rate of BPSG films. However, the hardness of these doped films is slightly affected by doping level. Excellent planarity achieved by CMP is demonstrated for patterned wafers. Here, we also identify inversion patterns for the composite dielectric formed by a thin hard film on the top of a thick soft film. Such inversion phenomenon can be used for monitoring CMP process as a means of end point detection.
Dopant profile engineering by near-infrared femtosecond laser activation
(2006-03-27)
Wang, YC
;
Pan, CL
;
Shieh, JM
;
Dai, BT
;
光電工程學系
Femtosecond laser annealing (FLA) was employed for activation of phosphorus (P)- and boron (B)-implanted silicons with negligible dopant diffusion. Preamorphizing implantation is not required. We found that the dopant profiles in FLA-activated samples essentially duplicate those of as-implanted ones even for junctions as deep as 100 nm below the surface. The measured sheet resistances and activation efficiencies of P- and B-implanted samples were in the range of 100-400 Omega/square and 28%-35%, respectively. Moreover, thermal-energy-assisted dopant diffusion by heating was observed for substrate temperature as low as 100 degrees C. The shallow activated-depth feature associated with FLA reduces the separation between end-of-range defects and high-concentration portion of dopants. This generates a steep interstitial gradient responsible for observed B and P uphill diffusions at a depth of about 60 nm below the surface. (c) 2006 American Institute of Physics.
Effect of surface passivation removal on planarization efficiency in Cu abrasive-free polishing
(2006)
Fang, JY
;
Tsai, MS
;
Dai, BT
;
Wu, YS
;
Feng, MS
Selective removal of surface passivation on protruded Cu film is a critical factor of Cu planarization. For a stress-free Cu abrasive-free polishing (Cu AFP) process, due to the lack of mechanical abrasion by abrasives, a polishing pad is used instead of abrasives to remove surface passivation during Cu planarization. Thus, the planarization efficiency in Cu AFP relates to the efficiency of surface passivation removed by a pad. Comparing Cu oxides with a non-native Cu-BTA (Cu-Benzotriazole) monolayer used as surface passivation, this study found that an oxide-free Cu surface should be required in Cu AFP. When Cu oxides function as surface passivation in Cu AFP, they are removed with greater difficulty by a pad resulting in low planarization efficiency. Contrary to Cu oxides, high planarization efficiency can be obtained with non-native Cu-BTA as surface passivation in Cu AFP. (c) 2005 The Electrochemical Society.
Effects of helicon-wave-plasma etching on the charging damage of aluminum interconnects
(1998-07-01)
Lin, W
;
Kang, TK
;
Perng, YC
;
Dai, BT
;
Cheng, HC
The etching parameters of aluminum in the helicon wave plasma are characterized to elucidate the mechanism of charging damage. By increasing the ion energy and decreasing the plasma density via increase of the bias power and decrease of the source power, respectively, we can significantly reduce charging damage, On the basis of this concept, we develop a two-step etching technique to suppress the charging damage without selectivity loss. Such a high-density plasma etching technique will be very suitable for the formation of high-density, and narrow-line interconnects.
Effects of mechanical characteristics on the chemical-mechanical polishing of dielectric thin films
(1996-12-15)
Tseng, WT
;
Liu, CW
;
Dai, BT
;
Yeh, CF
;
電子工程學系及電子研究所
The effects of as-deposited (intrinsic) stress, externally applied (extrinsic) stresses, hardness, and modulus of various dielectric firms on chemical-mechanical polishing (CMP) removal and post-CMP cleaning processes are studied in this article. Intrinsic stresses of the polished dielectrics do not contribute directly to the CMP removal rate. Extrinsic stresses including normal and shear components are calculated using principles of elasticity and fluid mechanics respectively and their roles in the material removal process are discussed. Theoretical evaluation and experimental results both suggest that hardness and modulus are the two most important material characteristics affecting the CMP process. Efficiency of post-CMP particle extraction can be monitored using an adhesion probability which is related to the hardness of wafer and pad. Tn addition, particle removal rate can be remarkably enhanced by increasing pressure (normal stress) while increasing pad rotation speed (shear stress) contributes little to reduce the particle count.
Electrochemical behavior of copper chemical mechanical polishing in KIO3 slurry
(2002-03-01)
Hsu, JW
;
Chiu, SY
;
Tsai, MS
;
Dai, BT
;
Feng, MS
The electrochemical behavior of polishing copper with colloidal silica abrasive slurry formulated with KIO3 oxidizer has been investigated. For planarization of the surface morphology, the control of the surface passivation of Cu is critical during polishing. KIO3 is not only all oxidizer but also a passivator for copper in an acidic slurry by forming a CuI layer on the surface. With alkaline slurry, Cu2O is the primary corrosion product on the Cu surface. The copper corrosion rate and removal rate can be decreased dramatically with increasing slurry pH. The low corrosion resistance or high corrosion susceptibility of Cu as determined by electrochemical measurements is the basis for the high removal rates. The copper removal rate is reduced from 4600 to 650 Angstrom/min when the slurry pH is increased from 2 to 5: and the copper removal rate levels off atpH 7 with a steady-state removal rate of 200 Angstrom/min, (C) 2002 American Vacuum Society.
Electroplating copper in sub-100 nm gaps by additives with low consumption and diffusion ability
(2002-05-01)
Lin, KC
;
Shieh, JM
;
Chang, SC
;
Dai, BT
;
Chen, CF
This work presents a novel leveler with low consumption and low diffusion that achieved defect-free filling in vias as small as 0.1 mum and generated as-deposited films with low resistivities. Experimental results indicate that the additive, 2-aminobenzothiazole (2-ABT), with benzyl and amino (-NH2) functional groups, is a desirable leveler. It produced a highly selective concentration gradient between the opening and the bottom of the feature. This novel leveler, with weaker adsorption, also reduced the consumption during copper electroplating, and eventually deposited a film with a high conductivity. (C) 2002 American Vacuum Society.
Emission of bright blue light from mesoporous silica with dense Si (Ge) nanocrystals
(2005)
Cho, AT
;
Shieh, JM
;
Shieh, J
;
Lai, YF
;
Dai, BT
Three-dimensional Si (Ge) nanocrystals (NCs) were dispersed within the nanopores of mesoporous silica films by high-density plasma (HDP), low-density plasma, or implantation. Surface states of the resulting Si (Ge) NCs/silica arrays initiate blue-white photoluminescence (PL). HDP makes reactive species highly mobile and enables deposited NCs bonded with pore-wall well, therefore, efficiently constructing photoemission arrays. The mean density of HDP-synthesized semiconducting NCs is as high as 1 x 10(18)/cm(3). Accordingly, blue PL of arrays obtained with HDP, which is 4- 7 times stronger than those obtained with other methods, exhibits quantum-efficiency of 1%, near the reported value for green-to-red light emission from quantum-confined Si NCs. © 2005 The Electrochemical Society. All rights reserved.
Evaluation of impurity migration and microwave digestion methods for lithographic materials
(1999)
Ko, FH
;
Hsiao, LT
;
Chou, CT
;
Wang, MY
;
Wang, TK
In the section of incoming quality (IQC) or quality reliability analysis (QRA) of advanced semiconductor fabrication company, it is inevitable to regulate the strict standard for the incoming materials to ensure the reliability. In our radioactive tracer study, it is interestingly found the various amounts of metal and trace element impurities in the lithographic materials may migrate into the substrate. Based on the complex organic matrix in lithographic materials such as bottom anti-reflective coating (BARC), I-line resist and DUV resist, it is not easy to direct determine the multi-elements by the instrumentation. In this work, the lithographic materials are first decomposed by the close-vessel and open-focused microwave oven, and the digest is evaporated to incipient dryness. After adding water, the sample solutions are used either for evaluating the completeness of the digestion process by UV-VIS spectrometer, or for the determination of eleven elements using inductively coupled plasma mass spectrometry (ICP-MS). In addition, the digestion efficiency is also evaluated by the weight of total dry residual after various digestion recipes. By the complementary digestion method, the method detection limits for analytes can be achieved at lower than ng/g level. For evaluation of data accuracy, the results obtained by the two independent degestion methods are in good agreement. Moreover, the spiking recovery tests for all the elements are of 70 to 130%. According to the microcontamination control limit predicted by the SIA roadmap, the established method can meet the requirements for the quality control of lithographic materials in the future ten years.
Fabrication of thin film transistors by chemical mechanical polished polycrystalline silicon films
(1996-03-01)
Chang, CY
;
Lin, HY
;
Lei, TF
;
Cheng, JY
;
Chen, LP
A top-gate p-channel polycrystalline thin film transistor (TFT) has been fabricated using the polycrystalline silicon (poly-Si) film as-deposited by ultrahigh vacuum chemical vapor deposition (UHV/CVD) and polished by chemical mechanical polishing (CMP), In this process, long-term recrystallization in channel films is not needed. A maximum field effect mobility of 58 cm(2)/V-s, ON/OFF current ratio of 1.110(7), and threshold voltage of -0.54 V were obtained. The characteristics are not poor. In this work, therefore, we have demonstrated a new method to fabricate poly-Si TFT's.
Film characterization and evaluation of process performance for the modified electron beam resist
(2000)
Ko, FH
;
Ting, JH
;
Chou, CT
;
Hsiao, LT
;
Huang, TY
The modification of the electron beam resist by spiking with various amounts of poly(styrene-co-maleic anhydride) copolymer is performed. The characterization of resist solutions by gel permeation chromatography (GPC) and viscosity measurement reveals the main polymer chain in the resist is unchangeable, irrespective of the amount of modification. In addition, the spiking copolymer exists in original form. The viscosity of the resist increases with the amount of spiking polymer. Our thermal analysis results show that the resists are mainly decomposed in two regions (280 and 544 degrees C). The mass loss at 280 degrees C is significant higher than at 544 degrees C. The spectra of Fourier transform infrared red (FTIR) spectrometer indicate the extent of carbonate group decomposition decreases with temperature for resists. The plasma etching experiment indicates the promotion of etching resistance of the resist film is due to modification, while the resolution, sensitivity and contrast are not degraded. Owing to the polymer aggregation effect, the stripping performance of the resist film can achieve better after copolymer modification.