Browsing by Author "Lu, CP"

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Comparison of novel cleaning solutions, with various chelating agents for post-CMP cleaning on poly-Si film
(2001-11-01)
Pan, TM
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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.
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
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Shieh, JM
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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.
Novel cleaning solutions for polysilicon film post chemical mechanical polishing
(2000-07-01)
Pan, TM
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Lei, TF
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Chen, CC
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Chao, TS
;
Liaw, MC
Novel cleaning solutions were developed for post-CMP process, surfactant tetra methyl ammonium hydroxide (TMAH) and/or chelating agent ethylene diamine tetra acetic acid (EDTA) were added into the diluted ammonium hydroxide (NH4OH+H2O) alkaline aqueous solution to enhance removal of metallic and organic contamination, From the experimental result, it is found that the particle and metal removal efficiency and the electrical characteristics are significantly improved for post-CMP cleaning.
Novel one-step aqueous solutions to replace pregate oxide cleans
(2004-08-01)
Pan, TM
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Lei, TF
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Ko, FH
;
Chao, TS
;
Chin, TH
We have developed a number of novel solutions to use for one-step pregate oxide cleaning; they are based on tetraalkylammonium hydroxides of varying alkyl chain lengths, namely tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH). We added these surfactants together with ethylenediaminetetraacetic acid (EDTA) into the RCA SC-1 cleaning solution to enhance the efficiency of cleaning. With the exception of the TBAH solution, the cleaning efficiency of these solutions toward particles was 4%-7% higher than that of the conventional RCA method. Our cleaning methods have better efficiency toward the removal of Fe, Na, Ca, Cu, and Mn contaminants. We found that the conventional RCA method results in 10(9)-10(10) atoms/cm(2) of Cu and Mn after cleaning. The electrical breakdown field of MOS capacitors was enhanced when using the new cleaning method. The literature model for surface adsorption and double-layer formation explains the cleaning behavior of the tetraalkylammonium ion-containing solutions. The removal of surface particles and metallic contaminants and the degree of surface roughness agree with the model's predictions. We believe that the best solution for use in one-step cleaning-one that comprises EDTA and TPAH-can replace the traditional RCA cleaning method. This new method has great potential for pregate oxide cleaning because it has the advantages of faster cycle times, lower costs, and greater efficiency.
One-step cleaning solution to replace the conventional RCA two-step cleaning recipe for pregate oxide cleaning
(2001-06-01)
Pan, TM
;
Lei, TF
;
Chao, TS
;
Liaw, MC
;
Ko, FH
This work proposes an advanced wet chemical one-step cleaning process which omits the hydrochloric acid/hydrogen peroxide/water mixture (HPM) step in RCA. A novel one-step cleaning solution had been developed for pregate oxide cleaning to replace the conventional RCA two-step cleaning recipe, which used ammonia/hydrogen peroxide (or SC-1) and HPM (or SC-2) step. Tetramethylammonium hydroxide (TMAH) and ethylenediaminetetraacetic acid (EDTA) were added into the RCA SC-1 cleaning solution to enhance cleaning efficiency. From the experimental results, the particles and metallic contamination on the bare Si wafer surface could be removed significantly by applying this one-step cleaning solution. The effectiveness of various cleaning recipes and their interaction mechanism with silicon surfaces were studied. The surface adsorption and double layer models could explain the surface behavior of TMAH solutions. Based on the model, the particle, surface roughness and metallic contaminants can be realized. It was observed that the electrical properties of metal oxide semiconductor capacitors after cleaning with this novel solution were better than those after the conventional RCA cleaning. Besides, the cleaning method combining NH4OH, tetramethylammonium hydroxide, ethylenediaminetetraacetic acid, and H2O2, at 80 degreesC for 3 min showed high performance on particle removal, metal cleaning, surface smoothness, and electrical properties. Hence, this one-step cleaning process is very promising for future large sized silicon wafer cleaning due to the advantages of time-saving, low cost, and high performance. (C) 2001 The Electrochemical Society.
Optimum conditions for novel one-step cleaning method for pre-gate oxide cleaning using robust design methodology
(2000-10-01)
Pan, TM
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Lei, TF
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Chao, TS
;
Liaw, MC
;
Lu, CP
A novel one-step cleaning method has been developed for pre-gate-oxide cleaning to replace the conventional RCA two-step cleaning process. Tetramethyl ammonium hydroxide (TMAH) and ethylenediamine tetraacetic acid (EDTA) are added into the RCA SC-1 cleaning solution to enhance cleaning efficiency. We adapt a robust design methodology (Genichi Taguchi method) to analyze the results of our experiments. Using this novel method, it is found that the optimum conditions are A(1)B(2)C(1)D(1) (A(1): TMAH : NH4OH = 1 : 50, B-2: EDTA concentration is 100 ppm, C-1: cleaning time is 5 min, and D-1: cleaning temperature is 60 degreesC). This novel one-step cleaning method is very promising for future large-sized silicon wafer cleaning processes because it has the advantages of reduced processing time and temperature, cost reduction due to reduced chemical usage and improved performance.
Performance evaluation of cleaning solutions enhanced with tetraalkylammonium hydroxide substituents for post-CMP cleaning on poly-Si film
(2002-06-01)
Pan, TM
;
Lei, TF
;
Ko, FH
;
Chao, TS
;
Liaw, MC
The cleaning solutions augmented with tetraalkylammonium hydroxides (TAAHs) with various chain-lengths of hydrocarbon substituents were developed for post-poly-Si chemical mechanical polishing (CMP) cleaning. The cleaning performance with respect to particle, organic, and metal removal as well as surface roughness was evaluated for a series of 3% NH4H solutions dosed with 0.26 M of a TAAH and 100 ppm of ethylenediaminetetraacetic acid (EDTA). The experimental results demonstrated that the cleaning solutions enhanced with these surfactants (TAAH) and a chelating agent (EDTA) achieved significantly better removal efficiencies of particle and metal impurities than the control solution containing 3% NH4OH only. A conceptual model involving surface adsorption and double-layer formation was used to postulate the aqueous-phase surface interactions between the tetraalkylammonium cations and the poly-Si surface, and to explain the removal mechanisms of particle and metal impurities from the surface. The improved electrical properties (current density-electric field and charge-to-breakdown characteristics) of the post-CMP capacitor after cleaning further demonstrated the reliability and feasibility of the proposed cleaning recipes. (C) 2002 The Electrochemical Society.
Wetting effect on gap filling submicron damascene by an electrolyte free of levelers
(2002-07-01)
Chang, SC
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Shieh, JM
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Lin, KC
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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.