Browsing by Author "Ko, FH"

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Behavior and surface energies of polybenzoxazines formed by polymerization with argon, oxygen, and hydrogen plasmas
(2004-11-15)
Chen, JK
;
Lin, IK
;
Ko, FH
;
Huang, CF
;
Chen, KS
Polybenzoxazine (PBZZ) thin films can be fabricated by the plasma-polymerization technique with, as the energy source, plasmas of argon oxygen or hydrogen atoms and ions. When benzoxazine (BZZ) films are polymerized through the use of high-energy argon atoms, electronegative oxygen atoms, or excited hydrogen atoms, the PBZZ films that form possess different properties aid morphologies in their surfaces. High-energy argon atoms provide a thermodynamic factor to initiate the ring-opening polymerization of BZZ and result in the polymer surface having a grid-like structure. The ring-opening polymerization of the BZZ film that is initiated by cationic species such as oxygen atoms in plasma, is propagated around nodule structures to form the PBZZ. The excited hydrogen atom plasma initiates both polymerization and decomposition reactions simultaneously in the BZZ film and Results in the formation of a porous structure on the PBZZ surface. We evaluated the surface energies of the PBZZ films polymerized by the action of these three plasmas by measuring the contact angles of diiodomethane and water droplets. The surface roughness of the films range from 0.5 to 26 nm, depending on the type of carrier gas and the plasma-polymerization time. By estimating changes in thickness, we found that tie PBZZ film synthesized by the oxygen plasma-polymerization process undergoes the slowest rate of etching in CF(4) plasma. (C) 2004 Wiley Periodicals, Inc.
Characterization and lithographic parameters extraction for the modified resists
(1999)
Ko, FH
;
Lu, JK
;
Chu, TC
;
Huang, TY
;
Yang, CC
The modification of the i-line resist structure after spiking with various amount of poly(4-vinylphenol) polymer is characterized by the spectra of ultraviolet visible (UV-VIS) and gel permeation chromatography (GPC). The chemical structure of photoactive compound is found to be unchanged after modification, while slight change in the polymer chain is observed. The resist layer coated onto the wafer is characterized by various methods including n&k analyzer, Nanospec, Fourier transform infrared red (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to fully evaluate the film properties in terms of porosity, thickness, vibrational spectrum, and thermal stability. Our thermal analysis results show that the resists are mainly decomposed in three stages. The photoactive compound (PAC) is found to decompose during the first stage, while the polymer decomposes during the latter stages. The resist exposure parameters, namely, A, B and C at 365 mn are determined by the absorbance measurement. The extracted parameters are further used in the resist profile simulation by PROLITH/2. It is shown that the spiking of poly(4-vinylphenol) polymer into the resist can improve the resolution and linearity for dense lines. In addition, the swing effects can be reduced by up to 35 and 31 % for dense and isolated lines after resist modification, respectively.
Characterization and modeling of out-diffusion of cesium, manganese and zinc impurities from deep ultraviolet photoresist
(2000)
Ko, FH
;
Wang, MY
;
Wang, TK
;
Yang, CC
;
Huang, TY
The novel radioactive tracer technique was applied to investigate the migration of cesium, manganese and zinc impurities from deep ultraviolet photoresist into underlying substrate. Two important process parameters, viz., baking temperatures and substrate types (i.e., bare silicon, polysilicon, silicon oxide and silicon nitride), were evaluated. Our results indicated that the migration ratios were all below 6%, irrespective of baking temperatures and substrate types. The substrate types did not appear to strongly affect the metallic impurity out-diffusion from deep ultraviolet photoresist. However, solvent and/or water evaporation due to temperature change was found to have a significant effect on metal migration. The net driving force of impurity changes with temperature and the impurity diffusion can be classified into four types. Based on the proposed types, the obtained migration ratios can be realized. A new model, together with a new parameter, was proposed to describe the out-diffusion behavior of impurities from deep ultraviolet photoresist. The diffusion profile of photoresist was depicted based on diffusion equations and the migration ratios. This model could explain the migration ratios of metallic impurities in photoresist layers under various baking conditions.
Characterization and modeling of out-diffusion of manganese and zinc impurities from deep ultraviolet photoresist
(1999-09-01)
Wang, MY
;
Ko, FH
;
Wang, TK
;
Yang, CC
;
Huang, TY
The radioactive tracer technique was applied to investigate the out-diffusion of manganese and zinc impurities from deep-ultraviolet (DUV) photoresist. Two important process parameters, viz., baking temperature and the type of substrate (i.e., bare silicon, polysilicon, oxide, or nitride), were evaluated. Our results indicated that diffusion ratios were ail below 6%, irrespective of the substrate type and baking temperature. The substrate type did not appear to strongly affect the metallic impurity out-diffusion from DUV photoresist. However, solvent evaporation was found to have a significant effect on impurity diffusion. A new model, together with a new parameter, was proposed to describe the out-diffusion behavior of impurities from DUV photoresist. This model could explain the diffusion ratio of metallic impurities in photoresist layers under various baking conditions. The effectiveness of various wet cleaning recipes in removing metallic impurities such as manganese and zinc was also studied. It was found that (i) bath life due to temperature change can considerably affect the cleaning efficiency, and (ii) hot water immersion can effectively dissolve the impurities from the wafer surface. (C) 1999 The Electrochemical Society. S0013-4651(98)11-080-7. All rights reserved.
Characterization and modeling of the metal diffusion from deep ultraviolet photoresist and silicon-based substrate
(2001-05-01)
Wang, TK
;
Wang, MY
;
Ko, FH
;
Tseng, CL
;
奈米中心
The radioactive tracer technique was applied to investigate the out-diffusion of the transition metals (Cu, Fe and Co) from deep ultraviolet (DUV) photoresist into underlying substrate. Two important process parameters, viz., baking temperatures and substrate types (i.e., bare silicon, polysilicon, silicon oxide and silicon nitride), were evaluated. Results indicate that the out-diffusion of Co is insignificant, irrespective of the substrate type and baking temperature. The Out diffusion of Cu is significant for substrates of bare silicon and polysilicon but not for silicon oxide and nitride; for Fe, the story is reversed. The substrate type appears to strongly affect the diffusion, while the baking temperature does not. Also, the effect of solvent evaporation was found to play an important role in impurity diffusion. Using the method of numerical analysis, a diffusion profile was depicted in this work to describe the out-diffusion of metallic impurities from photoresist layer under Various baking conditions. In addition, the effectiveness of various wet-cleaning recipes in removing metallic impurities such as Cu, Fe and Co was also studied using the radioactive tracer technique. Among the six cleaning solutions studied, SC2 and SPM are the most effective in impurity removal. An out-diffusion cleaning model was first proposed to describe the cleaning process. A new cleaning coefficient, h(T), was suggested to explain the cleaning effect. The cleaning model could explain the tracer results. (C) 2001 Elsevier Science Ltd. All rights reserved.
Characterization of imprinting polymeric temperature variation with fluorescent Rhodamine B molecule
(2006-04-01)
Ko, FH
;
Weng, LY
;
Ko, CJ
;
Chu, TC
;
材料科學與工程學系奈米科技碩博班
The method to measure the imprint temperature variation of resist film with fluorescence probe technique was established. The maximal Rhodamine B concentration was 8 X 10(-4) M to achieve higher sensitivity and avoid precipitation problem. The temperature effect was a critical parameter on the temperature sensing, while imprinting pressure was not. The fluorescence intensity of Rhodamine B linearly decayed with time at various temperatures due to the formation of lactone-containing molecule during thermal stressing. The usual imprint time of less than 20 min was not affected by the signal decay effect due to limited percentage of signal variation during 100200 degrees C. The technique based on fluorescence probe method was successfully applied to measure the resist temperature variation of the imprint on the resist film of 6-in. wafer. (c) 2006 Elsevier B.V. All rights reserved.
Comparison of novel cleaning solutions, with various chelating agents for post-CMP cleaning on poly-Si film
(2001-11-01)
Pan, TM
;
Lei, TF
;
Ko, FH
;
Chao, TS
;
Chiu, TH
In this study, various cleaning solutions containing chelating agents with carboxyl acid group (-COOH), such as ethylenediaminetetraacetic acid, citric acid and oxalic acid, were developed for post-poly-Si CMP cleaning. The chelating agent and tetramethylammonium hydroxide (TMAH) were simultaneously added into 2% ammonium hydroxide alkaline solution to promote the removal efficiency on particles and metallic impurities. The effectiveness of various cleaning recipes and their interaction mechanism with poly-Si surface were studied. We could explain the surface behavior of various cleaning solutions by the different molecular size and charge of chelating agents. Based on the mechanism, the behavior of surface particle and metallic impurity can be realized. The co-existence of TMAH with citric acid or oxalic acid in the alkaline cleaning solutions can significantly enhance the electrical property for the capacitor.
Direct quantitative analysis of phthalate esters as micro-contaminants in cleanroom air and wafer surfaces by auto-thermal desorption-gas chromatography-mass spectrometry
(2005-04-08)
Kang, YH
;
Den, W
;
Bai, HL
;
Ko, FH
;
環境工程研究所
This study established an analytical method for the trace analyses of two phthalate esters, including diethyl phthalate (DEP) and di-n-butyl phthalate (DBP), known as the major constituents of cleanroom micro-contamination detrimental to the reliability of semiconductor devices. Using thermal desorption coupled with a GC-MS system, standard tubes were prepared by delivering liquid standards pre-vaporized by a quasi-vaporizer into Tenax GR tubes for calibration. This method was capable of achieving detection limits of 0.05 mu g m(-3) for 0.1 m(3) air samples and 0.03 ng cm(-2) for 150-mm wafer surface density. Actual samples collected from a semiconductor cleanroom showed that the concentration of DBP in a polypropylene wafer box (0.45 mu g m(-3)) was nearly four times higher than that in the cleanroom environment (0.12 mu g m(-3)). The surface contamination of DBP was 0.67 ng cm(-2) for a wafer stored in the wafer box for 24 h. Furthermore, among the three types of heat-resistant O-ring materials tested, Kalrez((R)) was found to be particularly suitable for high-temperature processes in semiconductor cleanrooms due to their low emissions of organic vapors. This analytical procedure should serve as an effective monitoring method for the organic micro-contamination in cleanroom environments. (c) 2005 Elsevier B.V. All rights reserved.
Effect of fluoroalkyl substituents on the reactions of alkylchlorosilanes with mold surfaces for nanoimprint lithography
(2004-11-01)
Chen, JK
;
Ko, FH
;
Hsieh, KF
;
Chou, CT
;
Chang, FC
We have applied trichloro(3,3,3-trifluoropropyl)silane (FPTS) and trichloro(1H, 1H, 2H, 2H-perfluorooctyl)silane (FOTS) for the preparation of self-assembled film on a silicon mold for use as releasing, antisticking layers for nanoimprint lithography. From contact angle measurements. we have determined the surface energies of the molds in terms of their Lewis acid, Lewis base, and van der Waals components. The surface energies of the FPTS- and FOTS-derived film decreased as the annealing temperature and immersion time increased. Suitable self-assembled films were prepared by annealing at 150 degreesC for at least 1 h. The surface roughnesses of the self-assembled film formed from FPTS and FOTS were 0.468 and 0.189 nm. respectively. The lower surface energy and roughness of the FOTS-derived film on the silicon mold prevent both the adhesion and defect-formation problems from occurring during resist imprinting. The self-assembled films prepared on the mold are resistant to immersion in acid and base, but treatment with oxygen plasma has an adverse effect on these molds' stabilities. (C) 2004 American Vacuum Society.
Effects of metallic contaminants on the electrical characteristics of ultrathin gate oxides
(2005)
Pan, TM
;
Ko, FH
;
Chao, TS
;
Chen, CC
;
Chang-Liao, KS
In this paper, we describe the effects that five metallic contaminants have on the electrical property of an ultrathin gate oxide. We found that, among five metallic contaminants, Fe and Ni resulted in the lowest electric breakdown fields (E-bd) and charge-to-breakdown ratios (Q(bd)) and the highest leakage currents and interface state densities (D-it). On the other hand, Ca-contaminated devices exhibit a lower leakage current and D-it and a higher Q(bd) than did the other metals. (c) 2005 The Electrochemical Society.
Evaluation of cleaning efficiency with a radioactive tracer and development of a microwave digestion method for semiconductor processes
(2000-02-29)
Lu, JK
;
Ko, FH
;
Chu, TC
;
Sun, YC
;
Wang, MY
A radioactive tracer technique was applied to investigate the effectiveness of various wet cleaning recipes in removing metallic impurities such as sodium, iron and cesium. The effects of solution temperatures and substrate types were studied. The mechanisms of the electrochemical segregation of metallic impurities between the substrate and cleaning solution were examined. The enthalpy of oxide formation and the effect of adsorption were the two reasons for the presence of surface metal impurities in the cleaning solutions. Our results indicated that SC2 and DHF can effectively remove the metallic impurities at 47 and 82 degrees C, while SPM and BOE are only effective at 82 degrees C. The gravimetric method was successfully implemented to evaluate the open-focused microwave digestion efficiency for anti-reflective coating and photoresist (PR) samples. By following the established microwave digestion method and inductively coupled plasma mass spectrometric determination, the detection limits (DLs) obtained for multi-elements were in the ng ml(-1) and sub-ng ml(-1) levels. Except for calcium, the spike recoveries of the metals were in the range 82-121% for the lithographic samples. The analytical results were found to be in reasonably good agreement with literature values, and the lithographic sample throughput can achieve up to 3.5 samples per hour for the analysis of 13 elements. (C) 2000 Elsevier Science B.V. 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.
Evaluation of metal migration and determination of trace metals after microwave digestion for lithographic materials
(1999-12-01)
Ko, FH
;
Wang, MY
;
Wang, TK
;
奈米中心
;
Nano Facility Center
The radioactive tracer technique was applied to investigate the migration of cesium and zinc impurities from bottom antireflective coating (BARC) and photoresist (PR) into underlying substrate. The effects of normal baking temperatures and substrate types were studied. Our results indicated that BARC has higher migration ratios than PR, irrespective of the substrate types and normal baking temperatures. The substrate type did not appear to strongly affect the metal migration ratios. However, water and/or solvent evaporation due to temperature change was found to have a significant effect on metal migration. The diffusion profiles of BARC and PR were depicted based on diffusion equations and the migration ratios. Both the UV/visible spectrometric and the gravimetric methods were successfully implemented to evaluate the feasibility of closed-vessel microwave digestion efficiency for BARC and PR samples. By following the established microwave digestion method and the inductively coupled plasma mass spectrometer (ICPMS) determination, the detection limits obtained for multielements were in the ppb and sub-ppb levels. Except for calcium, the spike recoveries of metals ranged from 91 to 132% and 87 to 125% for BARC and PR, respectively. The analytical results were found to be in reasonably good agreement with the Literature values.
Fabricating and characterizing oblique polymer structures by electron beam writing on resist-coated SiO2 wafers
(2006-04-01)
Ko, FH
;
Chen, JK
;
Chang, FC
;
材料科學與工程學系奈米科技碩博班
;
應用化學系
We have successfully fabricated SU-8 materials having oblique structures by a new electron beam technology.-We studied the contrast, sensitivity, etching, and thermal properties of SU-8, PMMA, and KrF resists to evaluate their suitability for the fabrication of oblique structures. Among these resists, SU-8 revealed the lowest contrast ratio, highest throughput, and best thermal stability, and so it became the candidate material for patterning the oblique structures. The technique we have developed involves five regional exposures of a thick SU-8 resist layer with various electron beam dosages. Furthermore, we discuss the surface morphology, reaction mechanism, and hydrophobicity after subjecting the SU-8 resist to a series of plasma treatments. The formation of surface nano-nodules during oxygen plasma treatment explains the surface hydrophobicity. We have carefully evaluated the effects of the electron beam writing dose and the design of the exposure area with respect to the inclined angle of the fabricated structure. (c) 2006 Elsevier B.V. All rights reserved.
Fabrication of biomimetic super-amphiphobic surfaces through plasma modification of benzoxazine films
(2006-03-03)
Wang, CF
;
Chiou, SF
;
Ko, FH
;
Chou, CT
;
Lin, HC
In this study, a method for producing super-amphiphobic surfaces through plasma modification of benzoxazine films is presented. Microroughening and fluorination of the benzoxazine films occurs during the plasma treatment process and a rugged surface with a micro/nano binary structure is formed. The combined effect of low surface energy and substrate roughness results in high advancing contact angles (157 degrees for water, 152 degrees for diiodomethane) and low contact angle hysteresis.
Fabrication of sub-60-nm contact holes in silicon dioxide layers
(2004-06-01)
Ko, FH
;
You, HC
;
Chu, TC
;
Lei, TF
;
Hsu, CC
We have developed a fabrication technique, comprising electron-beam writing, chemical shrinking, and silicon dioxide etching, for the fabrication of sub-60-nm contact holes. The dimensions of the contact holes after the electron-beam writing, chemical shrinkage, and plasma etching steps were 140, 93, and 53 nm, respectively. We carefully evaluated the critical process parameters, such as mixing-bake temperature, mixing-bake time, plasma etch selectivity, and the profile shapes. A higher mixing-bake temperature led to an overhang of the contact hole in the resist; the optimal mixing-bake conditions occur when heating at 110 degreesC for 70 s. A fluorinated mixture of gases (CHF3/CF4 = 1:1) was used to etch the nano-scale contact holes in the silicon dioxide layer. The formation of side-wall polymers during the plasma etch phase contributed further to the contact hole shrinkage in addition to resist chemical shrinkage. The ratio of the hole's perimeter to its area affects the shrinkage dimensions of the etch process, especially for smaller contact holes. The pattern reduction due to side-wall polymer deposition in etch process has the inverse relationship with the diameter of contact hole. (C) 2004 Elsevier B.V. All rights reserved.
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.
Fullerene-incorporation for enhancing the electron beam resist performance for contact hole patterning and filling
(2006-04-03)
You, HC
;
Ko, FH
;
Lei, TF
;
材料科學與工程學系奈米科技碩博班
;
電子工程學系及電子研究所
The fullerene molecules such as C60 and C70 were incorporated in the commercial positive electron beam resist to investigate the performances for patterning and filling the contact holes at nanometer scale. The sensitivity, process window and contrast of the modified resist were improved, while the toluene dilution degraded the sensitivity. The electron beam dose affected the designed holes dimension, and the adulterated resist could print sub-50 nm holes pattern. We found the small amount (0.01-0.02% w/v) of fullerene molecules very effectively promoted the etch resistance and selectivity under fluoro-containing gases, and minimized the film stress. The etching resistance for C60 and C70 modification could be improved by 65% and 68%, respectively. Together with the fullerene-incorporated resist and the etching processes, the sub-50 nm contact hole could be achieved. In addition, the gap-filling and step coverage capability of titanium nitride into nanometer contact hole with chemical vapor deposition was better than physical vapor deposition. (c) 2005 Elsevier B.V. All rights reserved.
Mechanism and modeling of ring pattern formation for electron beam exposure on Zwitterresist
(2003-06-01)
Chen, JK
;
Ko, FH
;
Chen, HL
;
Chang, FC
;
應用化學系
The novel sensitivity curve was determined for the zwitterresist. The irradiation dose in the center could create a ring pattern due to simultaneous exhibition of the positive tone and negative tone of zwitterresist. The natural logarithm dependence of ring width and electron beam dose was linear in two ranges, irrespective of the dot design radius. The heating effect was identified from 600 muC/cm(2), while it could be neglected at less than 600 muC/cm(2). Mathematical modeling for the prediction of ring width for zwitterresist, was achieved by considering the electron scattering and heating effects. The results of experimental measurement and modeling on ring width showed a very good correlation.
Migration-adsorption mechanism of metallic impurities out of chemically amplified photoresist onto silicon-based substrates
(2000-10-01)
Yang, CC
;
Ko, FH
;
Wang, MY
;
Wang, TK
;
Wu, SC
The radioactive tracer technique was applied to investigate the migration and adsorption behaviors of metallic impurities (i.e., Ba, Cs, Zn, and Mn) out of chemically amplified photoresist onto silicon-based underlying substrates. Two important process parameters, i.e., baking temperatures and substrate types (e.g., bare silicon, polysilicon, oxide, and nitride) were evaluated. Our results indicated that the transition metals (Zn and Mn) have lower migration ratios than alkali metal (Cs) and alkaline earth metal (Ba), irrespective of the substrate types and baking temperatures. The transition metals form stable complexes with the coexisting solvents and/or hydrolysis species in the photoresist layer. The size of the metal complex, the drag force in solvent evaporation, and the baking process were found to have significant effects on impurity migration. A new model, together with the metal migration in the chemically amplified photoresist and the subsequent adsorption onto the underlying substrate, was proposed to explain the pathway of the metal migration. This model could explain the migration ratios of metallic impurities out of the photoresist layer onto the substrate surface. (C) 2000 The Electrochemical Society. S0013-4651(00)01-026-0. All rights reserved.