Browsing by Author "Li, YH"

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A novel wafer reclaim method for silicon carbide film
(2003)
Tsui, BY
;
Fang, KL
;
Wu, CH
;
Li, YH
;
電子工程學系及電子研究所
As feature size keeps shrinking down, it is expected that amorphous SiC will replace Si3N4 in the Cu dual-damascene structure soon. SiC is chemically inert and is hard to be etched by wet processing. This property become adverse effect from the wafer reclaiming point of view. In this work, a novel wafer reclaiming method of oxidation followed by HF etching is proposed. Comparing with traditional reclaim method of wafer polish, this novel method exhibits great benefits of low cost, high throughput, and almost unlimited reclaim times.
A one-step single-cleaning solution for CMOS processes
(2003-09-01)
Chao, TS
;
Yeh, CH
;
Pan, TM
;
Lei, TF
;
Li, YH
In this paper, we demonstrate a one-step single-cleaning solution to replace the conventional RCA two-step cleaning method for complementary metal oxide semiconductor (CMOS) processes. We found the performance of devices fabricated using this new recipe is comparable or even better than that of devices fabricated using the conventional RCA method. The benefits of this method are more efficient removal of contaminants, improved driving current of devices, simpler processing, fewer steps in cleaning, time savings, reduction of cost and of chemical waste, and reduced impact on the environment. (C) 2003 The Electrochemical Society.
Computation of unstable liquid metal convection in a vertical closed cylinder heated from the side and cooled from above
(1997-08-29)
Li, YH
;
Lin, KC
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
Three-dimensional unsteady numerical computation was carried out to investigate buoyancy-driven unstable convection processes in a side-wad-heated and top-wad-cooled vertical closed cylinder containing liquid metal. The time-dependent basic flow equations were directly solved by the implicit Marker-and-Cell (MAC) scheme with the power law approximation to treat the convection-diffusion couplings. Results were obtained for liquid metal (Pr = 0.02) in a cylinder of finite aspect ratio (Gamma = 2) for various Rayleigh numbers. The predicted results indicate that the flow is relatively unstable except at low buoyancy. Specifically, of Ra = 2000 the flow evolves to a steady state but is highly asymmetric. As Ra = 3000 and 4000, the flow Becomes time periodic after the transient has died out with increasing asymmetry. At a still higher buoyancy the oscillation amplitude and flow asymmetry get larger, and a second fundamental frequency appears. The flow is quasi-periodic. Qualitatively, the flow structure is characterized by a main recirculation ill the major portion of the cylinder along with two uprising smaller cells near the side wall in the bottom half of the cylinder and another two counter rotating cells in the top half of the cylinder Finally, the critical Rayleigh number for the transition from a steady to a time periodic state was evaluated.
Computation of unstable liquid metal convection in a vertical closed cylinder heated from the side and cooled from above
(1997-08-29)
Li, YH
;
Lin, KC
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
Three-dimensional unsteady numerical computation was carried out to investigate buoyancy-driven unstable convection processes in a side-wad-heated and top-wad-cooled vertical closed cylinder containing liquid metal. The time-dependent basic flow equations were directly solved by the implicit Marker-and-Cell (MAC) scheme with the power law approximation to treat the convection-diffusion couplings. Results were obtained for liquid metal (Pr = 0.02) in a cylinder of finite aspect ratio (Gamma = 2) for various Rayleigh numbers. The predicted results indicate that the flow is relatively unstable except at low buoyancy. Specifically, of Ra = 2000 the flow evolves to a steady state but is highly asymmetric. As Ra = 3000 and 4000, the flow Becomes time periodic after the transient has died out with increasing asymmetry. At a still higher buoyancy the oscillation amplitude and flow asymmetry get larger, and a second fundamental frequency appears. The flow is quasi-periodic. Qualitatively, the flow structure is characterized by a main recirculation ill the major portion of the cylinder along with two uprising smaller cells near the side wall in the bottom half of the cylinder and another two counter rotating cells in the top half of the cylinder Finally, the critical Rayleigh number for the transition from a steady to a time periodic state was evaluated.
Effects of thermal boundary condition on buoyancy driven transitional air flow in a vertical cylinder heated from below
(2000-06-01)
Cheng, TC
;
Li, YH
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
A three-dimensional unsteady numerical computation was carried out here to investigate the effects of the thermal boundary condition on the convection flow in a vertical, bottom heated cylinder containing air. The thermal condition at the sidewall of the cylinder is assumed to be thermally well insulated or perfectly conducting. Results were obtained for air in a cylinder of finite aspect ratio (Gamma = 2) for various thermal Rayleigh numbers. The predicted results indicate that the flow in the sidewall insulated cylinder is highly asymmetric even at steady state and contains multicellular vortices. The flow formation processes leading to the above structures are relatively complicated. In the early transient two axisymmetric circular vortex rolls, one on top of another, appear. Then the rods merge asymmetrically. In the late stage the flow deflection by the cylinder top and bottom results in a very complex flow. In the cylinder with a perfectly conducting sidewall the transition from a steady to a time dependent flow is subcritical. However, in the cylinder with an insulated sidewall the flow transition is supercritical.
Experimental study of unsteady thermal characteristics and rotation induced stabilization of air convection in a bottom heated rotating vertical cylinder
(1998-06-01)
Ker, YT
;
Li, YH
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
Flow stabilization by cavity rotation in convection of air (Pr = 0.7) in a vertical circular cylinder heated from below is studied experimentally. The cylinder is rotated at a constant speed about its own axis. In the experiment the time variations of the air temperature at selected locations in the cylinder are measured. Results are obtained for a cylinder with diameter D = 5 cm, height H = 10 cm, imposed temperature difference Delta T = 5 degrees C to 15 degrees C and rotation rate Omega from 0 to 346.1 rpm. The experimental data clearly show the stabilization of the thermal buoyancy driven irregular flow by the cavity rotation when the rotation rate is in certain ranges. For a given Delta T two different ranges of Omega exist for the flow to be stabilized. Outside these ranges the flow oscillates periodically or quasi-periodically in time. At given Delta T and Omega the temperature oscillation at various locations exhibits some change in amplitude but negligible change in frequency. However, change of the oscillation frequency with the rotation rate is nonmonotonic and is rather significant at high rotation rates. But this frequency change with the imposed temperature difference is small. (C) 1998 Elsevier Science Ltd. All rights reserved.
Investigations of effects of bias polarization and chemical parameters on morphology and filling capability of 130 nm damascene electroplated copper
(2001-05-01)
Chang, SC
;
Shieh, JM
;
Lin, KC
;
Dai, BT
;
Wang, TC
Through elucidating the effects of current density, cupric ion concentration, bath temperature, and air agitation on plating uniformity and filling capability of copper electroplating, the deposition of copper in an acid copper electrolyte will be illustrated to scale down to the sub-0.13 mum features with uniform plating, which is required by chemical mechanical polishing in current damascene techniques. In order to achieve the defect-free filling in sub-0.13 mum vias and trenches, the electrolyte must be composed of proper amounts of cupric ions, sulfuric acid, chloride ions, wetting agent, and filling promoter. The supplied current controlled at a lower current density, agitation acceded to the electroplating process were found as further keys. In the electrolyte, the filling promoter was consisted essentially of thiazole derivatives with benzyl groups and amino-group (-NH2) offering sufficient inhibition on copper depositing and selective inhibition gradient. Moreover, a lower resistivity film and higher filling capability could be obtained by using periodic pulse current plating as compared with direct current plating. (C) 2001 American Vacuum Society.
Leveling effects of copper electrolytes with hybrid-mode additives
(2002-11-01)
Lin, KC
;
Shieh, JM
;
Chang, SC
;
Dai, BT
;
Chen, CF
100 nm vias were completely filled with copper for interconnect applications using an electrolyte in the presence of polyethylene glycols (PEG) and a hybrid-mode additive, benzotriazole (BTA). Electrochemical analyses indicated that BTA with a higher concentration inhibited the copper deposition rate, whereas BTA with a lower concentration accelerated the copper deposition rate. This electrolyte thus generated an enhanced deposition gradient within a gap because the PEG molecules and the high concentration of BTA, adsorbed at the opening of the gap, inhibited the deposition. Meanwhile, a little BTA diffused into the inner part of the gap and thus accelerated the deposition of copper. Therefore, this two-component (PEG and BTA) additive electrolyte had the capacity of a three-additive bath (accelerators, suppressors, and levelers). (C) 2002 American Vacuum Society.
Microleveling mechanisms and applications of electropolishing on planarization of copper metallization
(2002-09-01)
Chang, SC
;
Shieh, JM
;
Huang, CC
;
Dai, BT
;
Li, YH
The optimization of Cu electropolishing processes was explored to be in the mass-transfer-limited plateau with a stable limiting current density and in concentrated phosphoric acid by elucidating surface morphologies and potentiodynamic polarization. After electropolishing, the average roughness of polished surfaces achieved to 1.1 nm. Both the x-ray photoelectron spectroscopy and the electrochemical impedance spectroscopy suggest that the existence of a passivation film on the polished surface contributed to the microleveling effect of Cu electropolishing. Moreover, this passivation layer also induces an application of end point in electropolishing. (C) 2002 American Vacuum Society.
Numerical simulation of flow pattern formation in a bottom heated cylindrical fluid layer
(1996-10-01)
Li, YH
;
Chu, TC
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
The temporal formation of the buoyancy-driven flow structures in a bottom heated, shadow, cylindrical fluid layer was numerically studied. The unsteady three-dimensional Navier-Stokes and energy equations were discretized by the power law scheme and solved by the fully implicit Marker-and-Cell method. Computations were carried out for the pressurized argon (Pr = 0.69) and wafer (Pr = 6.1) layers for various Rayleigh numbers and heating rates of the layer. ln the pressurized argon layer at a slightly supercritical Rayleigh number with Ra-f = 1.05Ra(c), a steady straight roll pattern was formed when the heating rate was very slow (a = 0.001) after a long transient stage. When the heating rate was raised to a = 0.01, a very different structure like U-rolls was formed at steady state. In the water layer with Ra-f = 1.05Ra(c), a straight roll pattern was again formed, hut at a = 0.01. At Ra-f = 1.13Ra(c), curved rolls with the three foci at the sidewall were formed for a = 0.01. A pattern in the form of U-rolls appears at a = 0.01. Regular concentric circular rods prevail at a = 1.0. When the Rayleigh number is further raised to 1.23Ra(c), the resulting steady flow is dominated by incomplete circular rolls with open ends near theta = 0 degrees.
Numerical simulation of flow pattern formation in a bottom heated cylindrical fluid layer
(1996-10-01)
Li, YH
;
Chu, TC
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
The temporal formation of the buoyancy-driven flow structures in a bottom heated, shadow, cylindrical fluid layer was numerically studied. The unsteady three-dimensional Navier-Stokes and energy equations were discretized by the power law scheme and solved by the fully implicit Marker-and-Cell method. Computations were carried out for the pressurized argon (Pr = 0.69) and wafer (Pr = 6.1) layers for various Rayleigh numbers and heating rates of the layer. ln the pressurized argon layer at a slightly supercritical Rayleigh number with Ra-f = 1.05Ra(c), a steady straight roll pattern was formed when the heating rate was very slow (a = 0.001) after a long transient stage. When the heating rate was raised to a = 0.01, a very different structure like U-rolls was formed at steady state. In the water layer with Ra-f = 1.05Ra(c), a straight roll pattern was again formed, hut at a = 0.01. At Ra-f = 1.13Ra(c), curved rolls with the three foci at the sidewall were formed for a = 0.01. A pattern in the form of U-rolls appears at a = 0.01. Regular concentric circular rods prevail at a = 1.0. When the Rayleigh number is further raised to 1.23Ra(c), the resulting steady flow is dominated by incomplete circular rolls with open ends near theta = 0 degrees.
Stability investigation of single-wafer process by using a spin etcher
(2003-07-01)
Kang, TK
;
Wang, CC
;
Tsui, BY
;
Yang, WL
;
Chien, FT
Etch rate instability was found in a spin etcher. When chemical was pumped to the spin etcher, the flow rate became unstable; possibly resulting in a chemical deficiency due to low mass transport at the wafer edge. Consequently, the etch rate and etch uniformity are unstable. The detailed etch mechanism has been investigated and the mass transport deficiency can be avoided. Less than 2% of etch nonuniformity and a stable process can be achieved by achieving a stable flow rate and control of the surface reaction over the whole wafer in spin etching. (C) 2003 The Electrochemical Society.
Superpolishing for planarizing copper damascene interconnects
(2003-05-01)
Chang, SC
;
Shieh, JM
;
Dai, BT
;
Feng, MS
;
Li, YH
We demonstrate a superpolishing electrolyte, which consists of acid additives in conventional Cu polishing electrolytes (H3PO4), for efficiently planarizing Cu damascene features. The significant additive concentration gradient in features, resulting in a selective Cu dissolution rate within features, is explored as a major mechanism that yields such electrolytes with high planarization efficiency. Moreover, another additive, polyethylene glycol as a suppressor, is also employed to reduce oxygen bubbling on polished films. Consequently, a smooth surface with a complete step height elimination is obtained in a 70 mm trench after electropolishing. (C) 2003 The Electrochemical Society.
The effect of plating current densities on self-annealing Behaviors of electroplated copper films
(2002-09-01)
Chang, SC
;
Shieh, JM
;
Dai, BT
;
Feng, MS
;
Li, YH
In this study, the effect of plating current densities on self-annealing behaviors of electroplated Cu films was found to be relevant to the polarization resistance of electroplating systems. Porous films with defects occurred at low plating current density or at low polarization resistance. In contrast, dense films with small grains occurred at higher plating current density or at higher polarization resistance. However, when more current was further supplied, Cu aggregation occurred and deposited films became spongy or dendritic. We suggest that both the defects within porous films and the underlying energy of fine-grained deposits accelerated self-annealing. These two characteristics competed with each other to determine the resistivity drop by self-annealing. On the other hand, the (111) texture evolutions of deposited Cu films with an increase of plating current densities were consistent with the evolutions of resistivity and surface morphology. (C) 2002 The Electrochemical Society.
The port-to-port isolation of the downconversion P-type micromixer using different N-well topologies
(2006-04-01)
Tseng, SC
;
Meng, CC
;
Li, YH
;
Huang, GW
;
電信工程研究所
The port-to-port isolation of the micromixer is studied using three different p-type downconversion micromixers in 0.35-mu m CMOS technology. Both the body effect and the well isolation influence the port-to-port isolation significantly. The body effect degrades the LO-to-RF isolation and also deteriorates the LO-to-RF isolation. Without the well isolation, the LO-to-RF isolation drops. However, the RF-to-IF isolation is independent of the body effect and well isolation. The p-type micromixer with a separate N-well and without body effect has the best port-to-port isolation properties; its LO-to-IF, LO-to-RF, and RF-to-IF isolations are -59 dB, -58 dB, and -30 dB, respectively.
Wetting effect on gap filling submicron damascene by an electrolyte free of levelers
(2002-07-01)
Chang, SC
;
Shieh, JM
;
Lin, KC
;
Dai, BT
;
Wang, TC
By using an acid-copper electrolyte without levelers and brighteners, we achieved defect-free filling of 0.13 mum vias with aspect ratio 8:1. This novel electrolyte consisted of copper sulfate (CuSO4.5H(2)O), sulfuric acid (H2SO4), chloride ions (Cl-), and two different average molecular weights of polyethylene glycols (PEG). The smaller-molecular-weight PEG200, with higher diffusion ability, was identified to enhance cupric ions transporting into deep features and was treated as a bottom-up filling promoter. The larger-molecular-weight PEG2000, with higher polarization resistance, provided enough inhibition effect on cupric ion reduction to obtain denser and small-grained deposits in a lower-current-density region, which benefits the filling capability in submicron features. In addition, adding PEG2000 could reduce the interfacial energy between the electrolyte and the opening of trenches/vias to enhance the filling capability. (C) 2002 American Vacuum Society.