Hexafluoroacetylacetonate Trimethylvinylsilane Research Articles

Investigation of copper layers deposited by CVD using Cu(I)hfac(TMVS) precursor

Chemical vapour deposition (CVD) of copper on titanium-coated substrates was performed in a stainless steel reactor using copper(I) hexafluoroacetylacetonate trimethylvinylsilane (Cu(I)hfac(TMVS)) as a precursor and nitrogen (N2) as carrier gas. Film resistivity, film composition and surface morphology were studied in relation to deposition temperature, process pressure and process gas flow ratio. The lowest resistivity value obtained was around 2 μΩcm. In addition, cross-sectional examination of the copper films, using a LEO SEM imaging system, indicated increased film porosity at higher deposition temperatures. An optimum carrier gas flow rate was determined: higher carrier gas flow rates caused excessive dilution of the copper precursor, whilst lower carrier gas flow rates weakened the transport of the copper precursor to the substrate. XRD data revealed formation of copper oxide (Cu2O) if annealing temperatures exceeded 450∘C for a period of 30 min.

Focused ion beam induced deposition of low-resistivity copper material

Focused ion beam (FIB) induced processes for material etching and deposition have proven successful in integrated circuit device modification applications. Current FIB metal deposition processes are typically limited to resistivities in the range of 150–200μΩcm due to included impurities; however, today’s high-frequency devices require very low interconnect resistivity. The organometallic precursor material copper (I) hexafluoroacetylacetonate trimethylvinylsilane, or Cu(hfac)TMVS for FIB-assisted metal deposition was investigated. 50kV Ga+ ions were scanned over a defined area of an Al∕SiO2 resistivity test substrate in the presence of the precursor vapor, using two different 50kV FIB column designs with beam currents from 49to2070pA and current densities of 13–36Acm−2. Resistivity was measured by the four-point probe method. This study verifies prior reported resistivities of ⩽50μΩcm at room T across all deposition parameters for film growth yields ⩽0.18μm3nC−1 ion dose. Depositing on a heated substrate yields considerably lower film resistivity at temperatures near 100°C; resistivities as low as 18.8μΩcm were achieved at the high growth yield of 0.32μm3nC−1 ion dose. At room temperature, the resistivity varied inversely but nonlinearly with growth yield across all depositions. Auger electron spectroscopy revealed Cu content of ∼60at.% in the lowest resistivity films at all substrate temperatures. Via filling with aspect ratios >9:1 is demonstrated.

Effects of hydrogen plasma pretreatment on characteristics of copper film deposited by remote plasma CVD using (hfac)Cu(TMVS)

The effects of remote hydrogen plasma pretreatment on the characteristics of copper films prepared by remote plasma chemical vapor deposition (RPCVD) using copper(I) hexafluoroacetylacetonate trimethylvinylsilane [Cu(hfac)(TMVS)] were studied at a pressure of 1 torr, substrate temperature of 200°C, and plasma power of 100 W. When the remote hydrogen plasma pretreatment was employed, catalytic active points were observed on the surface of the pre-deposited 500-Å thick TiN substrate. These active points reduced the incubation time required for the copper nucleation on the pre-deposited TiN substrate. Enhanced copper nucleation rates were observed on the hydrogen plasma pretreated TiN substrate owing to the high concentration of the reactive hydrogen species in the reaction zone, thereby enhancing the reduction reaction and leading to improved copper qualities and increased nucleation rates. The resistivity measurements of the films yielded film resistivities in the range of approximately 2.1±0.1 μΩ cm for most samples.

Microstructures of copper thin films prepared by chemical vapor deposition

The dependence of the microstructure on the electrical property of copper thin films prepared by metal organic chemical vapor deposition has been studied. The copper films have been deposited onto TiN substrates by varying the substrate temperature and carrier gas flow rate with a precursor of hexafluoroacetylacetonate trimethylvinylsilane copper(I). The film microstructures have been analyzed by transmission electron microscopy (TEM) and Auger electron spectroscopy (AES), and the film resistivity has been measured by a four-point probe. Results of the measurement indicate that the resistivity is strongly dependent of the substrate temperature during the film deposition. The electrical resistivity of the films slightly increase above 180°C, due to the presence of the carbon content of the films. Post-annealing of the films after copper deposition below 180°C has effectively reduced the film resistivity.

Effects of the Partial Pressure of Copper (I) Hexafluoroacetylacetonate Trimethylvinylsilane on the Chemical Vapor Deposition of Copper

The effects of the partial pressure of precursor on the metalorganic chemical vapor deposition of copper were investigated. Copper was deposited using copper (I) hexafluoroacetylacetonate trimethylvinylsilane as a metalorganic precursor on TiN/Ti/Si substrates in a low-pressure warm-wall chemical vapor deposition reactor. The deposition rate of copper film was a constant value at a partial pressure higher than 0.048 Torr and decreased to below the constant value at a partial pressure lower than 0.048 Torr. The incubation time for copper nucleation decreased with increasing partial pressure of the precursor. The resistivity of copper film decreased to 2.00 µ Ω· cm with increasing partial pressure of the precursor. At a partial pressure lower than 0.048 Torr, copper did not nucleate inside the trench so that the step coverage of copper film became very poor.

Effect of the pressure on the chemical vapor deposition of copper from copper hexafluoroacetylacetonate trimethylvinylsilane

The effects of the deposition pressure on the deposition rate and the properties of the copper film prepared by chemical vapor deposition were studied. Copper films were deposited on titanium nitride (TiN) substrates in a low-pressure warm-wall reactor using copper(I) hexafluoroacetylacetonate trimethylvinylsilane, Cu(hfac)(tmvs), as the precursor. The deposition temperature was varied between 160°C and 220°C, and the deposition pressure was varied in the range 0.25–1.0 Torr. The deposition rate decreased with total pressure in the low-temperature region limited by surface reaction, whereas the rates were constant in the high-temperature region limited by mass transport. The decrease of deposition rate in the region limited by surface reaction is thought to be due to the by-product inhibition. The transition temperatures of the kinetic region and the surface morphology coincided with each other. In addition, both of them increased with the total pressure of the reactor. The surface roughness and resistivity decreased with total pressure, and showed rapid increase with deposition temperature. The effect of the partial pressure of the precursor on the deposition rate was also investigated.

Low resistivity LCVD direct write Cu conductor lines for IC customisation

Laser chemical vapor deposition (LCVD) of low resistivity copper from Cu(hfac)tmvs (copper(I)-hexafluoroacetylacetonate trimethylvinylsilane) is presented. The deposition was performed on Si3N4 and SiO2 passivated ICs. The deposition of Cu lines was carried out by a focused Ar+ laser beam. The deposition speed and the laser power were varied in the range of 24 to 400 μm/s and 40 to 1200 mW, respectively. The precursor gas partial pressure was 0.3 mbar buffered in 10 mbar He or H2. The morphology of the deposited lines was investigated by AFM, optical microscopy and LIMA. The LIMA analysis showed the deposited copper surface was contaminated but the contamination level decreased when the layer was depth profiled. The electrical resistivity was found to be 3.7 μΩ cm as determined by four point probe measurement. The effect of the laser beam focus location on the substrate surface is described. Low resistivity laser direct-write Cu lines were utilised in specific IC customisation cases.

High-rate deposition of high-quality Cu film with LPCVD

Basic process characteristics for Cu film deposition to be used in advanced ULSI interconnects have been studied by thermal LPCVD with liquid precursor Cu(hfac)(tmvs) (hexafluoro-acetylacetonate trimethyl-vinylsilane copper). For sufficient productivity in practical use, efforts were concentrated into obtaining high deposition rate with high film qualities of specific resistivity, surface flatness and adhesion. Three process chambers for preheating, TiN-PVD, and Cu-CVD functions were mounted on an ANELVA I-1060 single wafer cluster tool machine, where 6 inch wafers could be processed. Relationships between the deposition rate, specific resistivity, and Cu-CVD process parameters were analyzed using RSM (response surface methodology). Deposition rate over 100 nm/min was obtained at wafer temperature of 200°C, precursor flow rate of 0.67 g/min, carrier N 2 flow rate of 400 sccm, and purge Ar flow rate of 125 sccm with specific resistivity of about 1.8 μΩ cm on TiN underlayer. This shows a promising process for future Cu interconnect technology.

Chemical vapor deposition of copper from CuI hexafluoroacetylacetonate trimethylvinylsilane for ultralarge scale integration applications

In this article, the authors report the results of a study aimed at optimizing a manufacturable thermal copper-chemical vapor deposition process, using (tmvs) CuI (hfac) as the source, where tmvs=trimethylvinylsilane and hfac=hexafluoroacetylacetonate, and establishing associated material and process characteristics and performance. This study employed a two-stage design of experiments approach in conjunction with actual deposition runs on unpatterned silicon (Si) and titanium nitride (TiN) surfaces, as well as SEMATECH patterned TiN structures with feature sizes as small as 0.30 μm with aspect ratio 6:1. All samples were analyzed by Auger electron spectroscopy, Rutherford backscattering, four-point resistivity probe, and cross-section scanning electron microscopy. The results of these analyses showed that precursor concentration, substrate temperature, and in situ predeposition substrate surface plasma treatment play a key role in achieving good conformality and complete filling at high growth rates in aggressive via and trench structures. Based on these findings, an optimum process window was identified and employed to demonstrate complete high growth rate (∼2000 Å/min) filling of 0.3 μm, 6:1 aspect ratio, devices structures with pure copper at as-deposited resistivities of 1.8 μΩ cm.

Copper chemical vapour deposition using copper(I) hexafluoroacetylacetonate trimethylvinylsilane

The effects of the deposition temperature on the microstructure and the electrical resistivity of copper films prepared by chemical vapour deposition (CVD) were studied at the deposition temperatures between 160 ‡C and 330 ‡C. Copper films were prepared on titanium nitride (TiN) substrates in a low-pressure warm-wall reactor using copper(I) hexafluoroacetylacetonate trimethylvinylsilane, Cu (hfac)(TMVS), as the precursor. The activation energy for the deposition was found to be 45.4 kJ mol−1 at the total pressure of 66.7 Pa. The films deposited at below 200 ‡C, where the deposition is limited by surface reaction, were dense and had low resistivity of approximately 2 ΜΩcm. Moreover, they exhibited excellent step coverage. However, the films deposited at above 200 ‡C, where the mass transport processes become important, were composed of poorly connected globular grains, resulting in considerably high resistivities and rough surfaces. Effects of the deposition temperature on the grain size and the preferred orientation of the films were also investigated.

Growth, selectivity and adhesion of CVD-deposited copper from Cu +1 (hexafluoroacetylacetonate trimethylvinylsilane) and dichlorodimethylsilane

Copper films have been deposited by low-pressure (1–20 mTorr) chemical vapour deposition using Cu 1+ (hexafluoroacetylacetonate) trimethylvinylsilane onto SiO 2 patterned substrates having seed layers of W, TiN and Al. Blanket deposition is observed for all growth temperatures in the range 140 ° C ≤ T g ≤ 240 ° C. However, depending on the initial substrate seed layer and pre-treatment, the relative strength of the copper-oxide and copper-seed layer bond can be dramatically altered particularly when growth is carried out in the presence of dichloromethylsilane (DCDMS). The degree of selectivity as well as film morphology is also found to be sensitive to the initial pre-treatment, growth temperature and flow rate of DCDMS.

The Effect of Adding Hexafluoroacetylacetone on Chemical Vapor Deposition of Copper Using Cu(I) and Cu(II) Precursor Systems

The effect of adding hexafluoroacetylacetone [H(hfac)] on the characteristics of copper chemical vapor deposition (CVD) with beta‐ketonate precursors was studied. A significant difference in this effect is found for a CVD system using Cu(II) and Cu(I) precursors. In the reaction system using copper(II) bis‐hexafluoroacetylacetonate as the Cu(II) precursor, H(hfac) addition improves deposition selectivity on substrate surfaces by eliminating copper nuclei growth on the insulator. In the system using copper(I)‐hexafluoroacetylacetonate trimethylvinylsilane [Cu(hfac)(tmvs)] as, a Cu(I) precursor, selectivity is lost by H(hfac) addition but void formation in blanket CVD films in subquarter micron trenches has been suppressed. These results can be explained by the role of the H(hfac) species in the two deposition reactions. In the Cu(II) precursor system, H(hfac) poisons hydrogen‐induced active surface sites on an insulator. In the Cu(I) system, it acts as a catalytic reagent for the disproportional reaction of Cu(hfac) and enhances nucleation at the first stage of the deposition reaction.

Laser induced pyrolytic deposition of copper from (hexafluoroacetylacetonate)(trimethylvinylsilane) copper

The photothermal laser induced chemical vapor deposition of copper from its hexafluoroacetylacetonate trimethylvinylsilane derivative is studied as a function of added water vapor pressure. The height, width, electrical conductivity, and chemical composition of the deposited copper lines are measured. Under anhydrous conditions, the lines are characterized by a low growth rate, high carbon contamination, and poor electrical resistivity. In the presence of water vapor, a high growth rate (1800 μm/min) and high purity copper lines are obtained with a resistivity ratio of 1.1.

Terraced Copper Growth Deposited Onto Teflon AF1600 by The Excimer Laser Irradiation of Cu(hfac)Tmvs

ABSTRACTThe laser chemical vapour deposition (LCVD) of the organometallic precursor Cu(hfac)TMVS (hexafluoroacetylacetonate)(trimethylvinylsilane) is used to grow copper films on a Teflon AF1600 substrate. Exposure to excimer laser radiation at 248 nm results in a terraced copper growth. A simple model, based on interference effects in the Teflon and copper layers, is presented to account for this structure.

Combined experimental and modeling studies of laser-assisted chemical vapor deposition of copper from copper(I)-hexafluoroacetylacetonate trimethylvinylsilane

We describe laser-assisted chemical vapor deposition of copper from copper(I)- hexafluoroacetylacetonate trimethylvinylsilane onto silicon and metal substrates. The deposition process was driven thermally with 514.5 nm radiation from an argon ion laser. The relationship between operating parameters and the materials properties of deposited copper lines was investigated experimentally and interpreted through models of the deposition process. The as-deposited Cu lines were of high purity, showing no detectable carbon and oxygen contamination, and at optimal conditions, the resistivity of the lines was comparable to that of bulk copper. The line morphology was strongly dependent upon laser power with volcano shapes appearing at higher powers, as well as spatially periodic structures occurring in a narrow range of laser powers and scanning speeds. A mathematical model was developed for the laser heating and deposition processes to provide insight into the fundamental processes underlying the observed phenomena. Optical and thermophysical property changes caused by the continuously growing deposit were included, thereby enabling accurate predictions of the laser induced temperature distributions. The surface temperature distribution and the maximum temperature rise at the center of the laser beam were significantly affected by the deposit. The model further allowed identification of kinetic parameters for the deposition process. The volcano-shaped deposits were attributed to enhanced desorption of precursors in the center of the irradiated spot, and the periodic structures were interpreted in terms of a nonlinear coupling between heat conduction and chemical kinetics.

Metal Organic Chemical Vapor Deposition of Al and CuAl Alloy Films in a Vertical, High-Speed, Rotating Disk Reactor

ABSTRACTA vertical high-speed, rotating disk reactor has been used to produce Al and CuAl alloy films on 125 mm diameter Si (100) wafers. Trimethylamine-alane and Cu (hexafluoroacetylacetonate) trimethylvinylsilane (CupraSelect™) were used as metal precursors. Aluminum films were deposited over the temperature range from ∼100 C to 700 C. Aluminum sheet resistance measurements showed the films to have resistance 2 to 3 times that of bulk Al films. CuAl alloy films were deposited sequentially and by codeposition. At 30 Torr, deposition rates as high as 3.7 um/hr, 0.024 um/hr, and 1 um/hr for Al, Cu, and CuAl films, respectively, were demonstrated. Auger analysis showed the deposited films to be free of contaminants.

Laser Assisted Chemical Vapor Deposition of Cu from a New Cu Organometallic Complex

AbstractWe describe pyrolytic laser assisted chemical vapor deposition (LCVD) of copper onto silicon using a copper(I) hexafluoroacetylacetonate trimethylvinylsilane organometallic complex with 514.5 nm radiation from an Ar+ laser. Growth rates of 0.4-40 μm/min were obtained and at intermediate laser powers, the Cu lines had a resistivity comparable to that of bulk Cu. The line shape and morphology was strongly dependent upon laser power with volcano shapes appearing at higher powers. The growth was sensitive to the nature of the substrate suggesting that film nucleation was a critical element in the writing process.