Jin-Young Hur

Electroless copper electrolytes and its surface characteristics for semiconductor interconnects

In this research, to develop proper electroless copper electrolytes for semiconductor interconnects, the concentration and amount of additives are varied. Then, the stability, reactivity, deposition rate, leveling effect, and surface structure are examined. After a virgin makeup solution with suitable deposition characteristics is obtained, an electroless copper coating layer of high uniformity and adhesion strength was achieved using the stabilizer, catalyst, buffer, and pH adjuster as additives and surfactant on Ru diffusion barriers. Through annealing, resistance characteristics could be enhanced. Moreover, by measuring the cyclic voltammetry stripping and mixed potential of the electroless Cu electrolyte, its surface reactivity is electrochemically evaluated, and the result is in agreement with the deposition reaction. When the electrolyte developed in this study is applied on a trench pattern wafer with A/R 3.5 and a line width of 30 nm, it is possible to observe immaculate filling with improved leveling.

A Study of Optimization of Electrodeposited CuSnZn Alloys Electrolyte and Process

CuSnZn electroplating was investigated as alternative to Ni plating. Evaluation of electrolyte and plating process was performed to control physical characteristics of the film, and to collect practical data for application. Hull-cell test was conducted for basic comparison of two commercialized products and developed product. Based on hull-cell test results, long term test of three electrolytes was performed. Various analysis on long term tested electrolyte and samples have been done. Reliable and practical data was collected using FE-SEM (FEI, Sirion), EDX (ThermoNoran SIX-200E), ICP Spectrometer (GBC Scientific, Integra XL), FIB (FEI, Nova600) for anlysis. Physical analysis and reliability test of the long term tested film were also carried out. Through this investigation plating time, plating speed, electrolyte composition, electrolyte metal consumption, hardness and corrosion resistance has been compared. This set of data is used to predict and control the chemical composition of the film and modify the physical characteristics of the CuSnZn alloy.

Study on Characteristics of Electrodeposited Thin Copper Film by Inorganic Additives in Pyrophosphate Copper Plating Bath

The copper deposit on steel plate was prepared by pyrophosphate copper plating solution made with variation of inorganic additive. NH4OH and NH4NO3 were used as inorganic additives. The copper layer characteristics - tensile strength, crystallite size and crystal orientation - were evaluated by X-ray diffraction and Universal Test Machine. The presence of ammonium nitrate results in reduction of average roughness value from 0.08 µm to 0.03 µm. In pyrophosphate copper plating solution without Inorganic additive, tensile strength of electrodeposit copper foil was reduced from 600 MPa to 180 MPa after 7 days aging. However, when adding ammonium nitrate, there was almost no change of tensile strength, intensity of crystal orientation - (111), (200) and (220) - and crystallite size (2~30 nm).

Effect of Complexing Agents on Adhesion Strength between Electroless Copper Film and Ta Diffusion Barrier

Surface Technology R B revised August 6, 2014 ; accepted August 7, 2014)AbstractThe primary purpose of this research is to investigate how much the complexing agent in electroless Cuelectrolytes will affect adhesion strength between copper film and Ta diffusion barrier for Cu interconnectof semiconductor. The adhesion strength using rochelle’s salt as complexing agent was higher than the caseof using EDTA-4Na. Effect of complexing agent on adhesion strength and electrical resistivity was studiedin crystal structural point of view.

Effects of Co content on the Cu diffusion barrier property of electroless NiCoP film

The characteristics of electroless NiCoP films were investigated as a function of Co content. Sheet resistance of a multi-stacked film of SiO2/Ta/Cu/NiP dramatically increased after annealing at 500 °C, but as more Co was co-plated in NiCoP film, the change in sheet resistance of the stacked film of SiO2/Ta/Cu/NiCoP at 500 °C became smaller. A CoP/Cu film showed no change in resistance value after annealing, which indicates the CoP film is the most effective Cu diffusion barrier. X-ray diffraction analysis showed that an as-plated NiP film of amorphous structure is easily crystallized by thermal annealing over 300 °C, while CoP showed an insignificant change in crystal structure by thermal annealing up to 500 °C. This result reveals that the CoP film is capable of preventing the diffusion of Cu at 500 °C due to the thermal stability of CoP film.

Effect of Additional Electrical Current on Adhesion Strength between Copper and Polyimide Films

The effect of the additionally applied electrical current on the adhesion strength between electroless Cu and polyimide films was investigated. Peel tests were performed after applying electrical current within the range from 0.1 to 100 mA for the duration from 1 to 30 minutes. Sample with more than 1 mA of additional electrical current for 1 minute showed higher adhesion strength than that without additional electrical current. However, samples with 10 mA of additional electrical current for more than 10 miniutes showed the degradation of adhesion strength. Ra and RMS values of the peeled polyimide surface were proportional to the adhesion strength though there were no significant changes in the morphology of the peeled surfaces with varied amount and time-length of additional electrical current. Applying electrical current could increase the density of chemical bonding, which results in increase of the adhesion strength between copper and polyimide. However, in the case of applying additional electrical current for excessive amount or time, the degradation of the adhesion strength owing to the formation of copper oxide at the interface could occur.

A Study on the Adhesion Improvement of Immersion Copper Coatings using Complexing Agent

Rare Metals Engineering, University of Science and Technology, Cheonan, Korea(Received January 14, 2015 ; revised February 2, 2015 ; accepted February 17, 2015)AbstractAmino-carboxyl acid as a complexing agent in acid copper sulfate solution was utilized to improve theadhesion of immersion copper layer for steel wire. According to the tape test results, regardless of alloycomposition of the wire, the adhesion of immersion copper layer was improved with the addition of amino-carboxyl acid. The incorporation of H and Fe in the plating layer was analyzed by TOF-SIMS. The H andFe were detected at the entire coating layer without any addition of amino-carboxyl acid. However, withaddition of amino-carboxyl acid, the H and Fe were scarcely detected at the coating layer.

A Study on How to Improve Magnesium Anodizing Process with High Biocompatibility

Anodization of die-casted AZ91D magnesium alloy was carried out using silicate based electrolyte solution instead of fluoride based solution to improve biocompatibility of oxidized layers. The anodic layer obtained from silicate based solution has smaller size of pore and smoother surface, resulting in lower corrosion rate in simulate body solution (SBF). Effect of enhanced structural and chemical properties in oxidized layer on biocompatibility was carefully considered.

Ultrasound Assisted Sn-Ag-Pd Activation Process for Electroless Copper Plating

An ultrasound-assisted Sn-Ag-Pd activation method for electroless copper plating was presented in this study. With this activation process, it was shown that the fine catalyst particles were homogeneously distributed with high density on the entire specimen. In addition, it was observed that incubation period occurred during the electroless plating step was decreased owing to the absorption of Ag which holds high catalytic activity. Resulting from the refinement and high densification of catalyst, the defect-free gap-fill was achieved within the 20x nm trench

Effects of Multi-Complex Agent Addition on Characteristics of Electroless Ni-P Solution

In this study, the effects of multi-complex agents addition on characteristics of electroless Ni plating solution are investigated. The species and the concentration of complexing agents are major factors to control the deposition rate, P concentration, and surface morphology of plating films. Adipic acid increases the deposition rate in regardless of single- or mutli-complex agent addition. However, lactic acid effectively increases the deposition rate in case of multi-addition as the complex agents with adipic or sodium succinate acid. In addition, sodium citric acid and malic acid show good stabilizing effects of plating solution and lowering the deposition rate, because they have high complexibility. Therefore, it is suggested that the development of Ni-P plating solution suitable for diverse usages can be carried out systematically using the database from this study.