Showing papers on "Diffusion barrier published in 2008"
TL;DR: In this article, the authors present a brief overview of stress and preferred orientation in nitride-based thin films, either in the form of single-, multi-layered or nanocomposite coatings.
Abstract: Nitride-based coatings are nowadays widely studied both from fundamental and technological point of views due to their unique physical and mechanical properties. Among the binary nitrides, TiN is the most stable thermodynamically and has been widely used due to the combination of its covalent and metal-like characteristics. Coatings produced by Physical Vapor Deposition (PVD) techniques generally exhibit a crystallographic texture, which in turn may strongly affect their properties, such as hardness, wear resistance, or diffusion barrier properties in microelectronic devices. Therefore great efforts have been made in recent years to understand the underlying mechanisms governing texture development in nitride thin films. In particular, the issue of stress build-up during PVD growth and its possible interplay with film preferred orientation is essential to address. We present a brief overview of stress and preferred orientation in nitride-based thin films, either in the form of single-, multi-layered or nanocomposite coatings. X-ray Diffraction (XRD) was used in the standard θ –2 θ configuration to study the texture development with film thickness, while the sin 2 ψ method combined with linear elasticity theory was employed to determine the complete strain/stress state. XRD measurements were made in the framework of the crystallite group method, which is of prime importance in thin films exhibiting a mixed texture, as it enables to selectively measure the elastic strain in a given subset of grains. For PVD films grown with energetic particles, the appropriate modeling requires the use of a triaxial stress tensor, including a hydrostatic stress component to take into account the local distortions induced by growth-defects. This approach enables us to determine the ‘stress-free and defect-free lattice parameter’, a 0 , solely linked to chemical effect. Illustrations will be given for fiber-textured TiN and ZrN films deposited on Si substrates, epitaxial TiN layers as well as epitaxial TiN sub-layers in TiN/Cu multilayers grown on (001) MgO single crystal substrates. Ternary TiN-based coatings, either in the form of solid solutions or nanocomposites will be also investigated.
270 citations
Patent•
TSMC1
TL;DR: In this article, a semiconductor diffusion barrier layer and its method of manufacture is described, and the ratio of the glue layer thickness to the barrier layer thickness is preferably about 1 to 50.
Abstract: A semiconductor diffusion barrier layer and its method of manufacture is described. The barrier layer includes of at least one layer of TaN, TiN, WN, TbN, VN, ZrN, CrN, WC, WN, WCN, NbN, AlN, and combinations thereof. The barrier layer may further include a metal rich surface. Embodiments preferably include a glue layer about 10 to 500 Angstroms thick, the glue layer consisting of Ru, Ta, Ti, W, Co, Ni, Al, Nb, AlCu, and a metal-rich nitride, and combinations thereof. The ratio of the glue layer thickness to the barrier layer thickness is preferably about 1 to 50. Other alternative preferred embodiments further include a conductor annealing step. The various layers may be deposited using PVD, CVD, PECVD, PEALD and/or ALD methods including nitridation and silicidation methods.
258 citations
Patent•
13 Feb 2008TL;DR: In this paper, a solar cell that is readily manufactured using processing techniques which are less expensive than microelectronic circuit processing is presented. In preferred embodiments, printing techniques are utilized in selectively forming masks for use in etching of silicon oxide and diffusing dopants and in forming metal contacts to diffused regions.
Abstract: A solar cell that is readily manufactured using processing techniques which are less expensive than microelectronic circuit processing. In preferred embodiments, printing techniques are utilized in selectively forming masks for use in etching of silicon oxide and diffusing dopants and in forming metal contacts to diffused regions. In a preferred embodiment, p-doped regions and n-doped regions are alternately formed in a surface of the wafer through use of masking and etching techniques. Metal contacts are made to the p-regions and n-regions by first forming a seed layer stack that comprises a first layer such as aluminum that contacts silicon and functions as an infrared reflector, second layer such titanium tungsten that acts as diffusion barrier, and a third layer functions as a plating base. A thick conductive layer such as copper is then plated over the seed layer, and the seed layer between plated lines is removed. A front surface of the wafer is preferably textured by etching or mechanical abrasion with an IR reflection layer provided over the textured surface. A field layer can be provided in the textured surface with the combined effect being a very low surface recombination velocity.
202 citations
TL;DR: The application of an AlMoNbSiTaTiVZr high-entropy alloy film as diffusion barrier for copper metallization has been investigated in this paper, and it was determined to prevent copper-silicide formation up to 700°C for 30min.
182 citations
TL;DR: In this article, nanosized titanium dioxide (TiO 2 ) powders were used to connect substrate and hydroxyapatite (HA) in order to reduce the HA decomposition due to ion migration from the metal substrate into the HA.
Abstract: Nanosized hydroxyapatite (HA) powders were prepared by a chemical precipitation method and electrophoretically deposited on Ti6Al4V substrates. The powders were calcined before the deposition process in order to obtain crack-free coating surfaces. As an inner layer between Ti6Al4V substrate and HA coating, nanosized titanium dioxide (TiO 2 ) powders were deposited, using different coating voltages, in order to connect substrate and HA tightly. Moreover, this layer is considered to be acting as a diffusion barrier, reducing the HA decomposition due to ion migration from the metal substrate into the HA. After the sintering stage, adhesion strengths of coatings were measured by shear testing, phase changes were studied by X-ray diffraction, and coating morphology was analyzed through scanning electron microscopy observations. Results showed that usage of the TiO 2 inner layer prevented HA decomposition. Furthermore, decreasing the voltage used in TiO 2 deposition resulted in crack-free surfaces and increased adhesion strength of the overall coating.
174 citations
TL;DR: In this article, the structure and composition of surface oxide films on austenitic stainless steels in hydrogenated high-temperature water were examined by changing the chromium content in alloys and the concentration of dissolved hydrogen in high temperature water.
Abstract: The structure and composition of surface oxide films on austenitic stainless steels in hydrogenated high-temperature water were examined by changing the chromium content in alloys and the concentration of dissolved hydrogen in high-temperature water. Auger electron spectroscopy, X-ray diffraction and analytical transmission electron microscopy revealed that the oxide films had a double-layer structure: ironbased spinels as the outer layer and chromium-rich spinel oxide as the inner layer. Increasing the chromium content suppressed the corrosion rate and produced fine oxide particles with a higher chromium concentration in the inner layer. Increasing the concentration of dissolved hydrogen enhanced the corrosion rate without a notable change in oxide structure. These influences are considered to originate from changes in cation diffusion through the inner layer, such as a decrease in the lattice diffusion of iron in the inner layer due to a higher concentration of chromium in the oxide as a diffusion barri...
156 citations
TL;DR: In this article, the diffusion and spatial distribution of tin from solder, and nickel from diffusion barrier in p-type (Bi,Sb)2Te3 and n-type Bi2(Te,Se)3 thermoelectric materials were investigated using electron microscopy.
Abstract: The diffusion and spatial distribution of tin from solder, and nickel from diffusion barrier in p-type (Bi,Sb)2Te3 and n-type Bi2(Te,Se)3 thermoelectric materials were investigated using electron microscopy The results indicate that nickel is a suitable diffusion-barrier material for tin in both (Bi,Sb)2Te3 and Bi2(Te,Se)3 However, even though it is not an issue in the (Bi,Sb)2Te3, the nickel diffuses several microns into the Bi2(Te,Se)3 during the soldering processing and degrades its performance Diffusion coefficients of nickel in p-type (Bi,Sb)2Te3 and in n-type Bi2(Te,Se)3 were also quantitatively studied
125 citations
TL;DR: In this article, the growth kinetics, chemical composition, and crystallization behavior of the TiO2 films were compared for combinations of the two precursors with three different sources of oxygen thermal ALD using H2O and plasma-enhanced ALD PEALD using H 2 Oo r O 2 plasma.
Abstract: cSCK-CEN, Boeretang 200, B-2400 Mol, Belgium Atomic layer deposition ALD of TiO2 films from tetrakisdimethylamido titanium TDMAT or titanium tetraisopropoxide TTIP precursors was investigated. The growth kinetics, chemical composition, and crystallization behavior of the TiO2 films were compared for combinations of the two precursors with three different sources of oxygen thermal ALD using H2O and plasma-enhanced ALD PEALD using H2 Oo r O 2 plasma. For TDMAT, the growth rate per cycle GPC decreased with increasing temperature; while for TTIP with either water plasma or O2 plasma, a relatively constant growth rate per cycle was observed as a function of substrate temperature. It was found that the crystallization temperature of the TiO2 films depends both on film thickness and on the deposition conditions. A correlation was observed between the TiO2 crystallization temperature and the C impurity concentration in the film. The TiO2 films grown using a H2O plasma exhibit the lowest crystallization temperature and have no detectable C impurities. In situ X-ray diffraction measurements were used to test the diffusion barrier properties of the TiO2 layers and proved that all TiO2 films grown using either H2 Oo r O2 plasma are dense and continuous.
123 citations
TL;DR: In this paper, the performance of high-entropy alloy (HEA) nitride was evaluated in the case of copper metallization diffusion barrier and the results showed that the current nitride prevents the reaction between Cu and Si before its failure at 900°C.
Abstract: Results on copper metallization diffusion barriers using high-entropy alloy (HEA) nitride are reported. The HEA nitride (AlMoNbSiTaTiVZr)50N50 is amorphous in the as-deposited state and remains its noncrystallinity up to a high temperature of 850°C. To evaluate its diffusion barrier characteristics, Cu∕(AlMoNbSiTaTiVZr)50N50∕Si test structures were prepared and annealed under 750–900°C for 30min. The results show that the current nitride prevents the reaction between Cu and Si before its failure at 900°C. The outstanding barrier performance and high thermal stability of amorphous structure are suggested to originate from multiprincipal-element effects.
105 citations
TL;DR: TaN and TiN films were deposited by remote plasma atomic layer deposition (ALD) using the combinations of Ta[N(CH 3 ) 2 ] 5 precursor with H 2 plasma and TiCl 4 precursor with h 2 -N 2 plasma, respectively as mentioned in this paper.
Abstract: TaN and TiN films were deposited by remote plasma atomic layer deposition (ALD) using the combinations of Ta[N(CH 3 ) 2 ] 5 precursor with H 2 plasma and TiCl 4 precursor with H 2 -N 2 plasma, respectively. Both the TaN and TiN films had a cubic phase composition with a relatively low resistivity (TaN: 380 μΩ cm; TiN: 150 μΩ cm). Dissimilar from the TiN properties, the material properties of the TaN films were found to depend strongly on the plasma exposure time. Preliminary tests on planar substrates were carried out revealing the potential of the TaN and TiN films as Cu and Li diffusion barriers in through-silicon via and silicon-integrated thin-film battery applications, respectively. For the specific films studied, it was found that TiN showed better barrier properties than TaN for both application areas. The TiN films were an effective barrier to Cu diffusion and had no Cu diffusion for anneal temperatures up to 700°C. The TiN films showed low Li intercalation during electrochemical charging and discharging.
99 citations
Patent•
IBM1
TL;DR: In this paper, a system and method for eliminating undercut when forming a C4 solder bump for BLM (Ball Limiting Metallurgy) and improving the C4 pitch is presented.
Abstract: A system and method for eliminating undercut when forming a C4 solder bump for BLM (Ball Limiting Metallurgy) and improving the C4 pitch. In the process, a barrier layer metal stack is deposited above a metal pad layer. A top layer of the barrier layer metals (e.g., Cu) is patterned by CMP with a bottom conductive layer of the barrier metal stack removed by etching. The diffusion barrier and C4 solder bump may be formed by electroless plating, in one embodiment, using a maskless technique, or by an electroplating techniques using a patterned mask. This allows the pitch of the C4 solder bumps to be reduced.
Patent•
9 Apr 2008TL;DR: In this article, a layer of cobalt nitride is formed by chemical vapor deposition from a novel cobalt amidinate precursor, which facilitates the nucleation, growth and adhesion of copper wires.
Abstract: An interconnect structure for integrated circuits incorporates a layer of cobalt nitride that facilitates the nucleation, growth and adhesion of copper wires. The cobalt nitride may deposited on a refractory metal nitride or carbide layer, such as tungsten nitride or tantalum nitride, that serves as a diffusion barrier for copper and also increases the adhesion between the cobalt nitride and the underlying insulator. The cobalt nitride may be formed by chemical vapor deposition from a novel cobalt amidinate precursor. Copper layers deposited on the cobalt nitride show high electrical conductivity and can serve as seed layers for electrochemical deposition of copper conductors for microelectronics.
1 Mar 2008
TL;DR: In this article, the adsorption energies and sites on graphene sheet for a lot of atomic species including transition metals, noble metals, nitrogen and oxygen were investigated as prototypes for formation of nano-structures on carbon nanotube (CNT) wall.
Abstract: DFT calculation of various atomic species on graphene sheet is investigated as prototypes for formation of nano-structures on carbon nanotube (CNT) wall. We investigate computationally adsorption energies and adsorption sites on graphene sheet for a lot of atomic species including transition metals, noble metals, nitrogen and oxygen, using the DFT calculation as a prototype for CNT. The suitable atomic species can be chosen as each application from those results. The calculated results show us that Mo and Ru are bounded strongly on graphene sheet with large diffusion barrier energy. On the other hand, some atomic species has large binding energies with small diffusion barrier energies
TL;DR: In this article, the properties of an Ir (5nm)∕TaN (5 nm) stacked layer as a copper diffusion barrier on Si have been investigated and the results indicate that the Ir∕ TaN bilayer is an effective diffusion barrier for copper metallization.
Abstract: The properties of an Ir (5nm)∕TaN (5nm) stacked layer as a copper diffusion barrier on Si have been investigated. Ir∕TaN bilayer barriers were prepared at room temperature by magnetron sputtering followed by in situ Cu deposition for diffusion tests. Thermal annealing of the barrier stacks was carried out in vacuum at high temperatures for 1h. X-ray diffraction patterns, cross sectional transmission electron microscopy images, and energy-dispersive spectrometer line scans on the samples annealed at 600°C revealed no Cu diffusion through the barrier. The results indicate that the Ir∕TaN bilayer is an effective diffusion barrier for copper metallization.
Patent•
28 Feb 2008
TL;DR: ProtProtective caps as discussed by the authors are formed by depositing a source layer of dopant-generating material (e.g., material generating B, Al, Ti, etc.) over an exposed copper line, converting the upper portion of the source layer to a passivated layer.
Abstract: Protective caps residing at an interface between metal lines and dielectric diffusion barrier (or etch stop) layers are used to improve electromigration performance of interconnects. Protective caps are formed by depositing a source layer of dopant-generating material (e.g., material generating B, Al, Ti, etc.) over an exposed copper line, converting the upper portion of the source layer to a passivated layer (e.g., nitride or oxide) while allowing an unmodified portion of a dopant-generating source layer to remain in contact with copper, and, subsequently, allowing the dopant from the unmodified portion of source layer to controllably diffuse into and/or react with copper, thereby forming a thin protective cap within copper line. The cap may contain a solid solution or an alloy of copper with the dopant.
TL;DR: In this paper, a thin Mn oxide layer was formed with a uniform thickness of 2.6-10nm depending on deposition temperature between 100 and 400°C, and thermal chemical vapor deposition (CVD) was found to be an excellent barrier formation process.
Abstract: Advanced large-scale integrated interconnect structure faces a major challenge in forming a thin and conformal diffusion barrier layer. We deposited a Mn oxide layer by thermal chemical vapor deposition (CVD) on SiO2 substrates and investigated deposition behavior and diffusion barrier property. A thin Mn oxide layer was formed with a uniform thickness of 2.6–10nm depending on deposition temperature between 100 and 400°C. Heat-treated samples of Cu/CVD-Mn oxide/SiO2 indicated no interdiffusion at 400°C for 100h. The CVD of the Mn oxide layer was found to be an excellent barrier formation process.
Patent•
27 Mar 2008TL;DR: In this article, a method of manufacturing a semiconductor device for forming an electrically conductive layer whose main component being Cu in a recess in an improved state of the embedding characteristics according to reflow processing at a high temperature ≥400°C is provided.
Abstract: PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device for forming an electrically conductive layer whose main component being Cu in a recess in an improved state of the embedding characteristics according to reflow processing even if the reflow processing at a high temperature ≥400°C is not carried out. SOLUTION: In the method of manufacturing the semiconductor device, first, a step of forming a wiring groove 16 in an interlayer dielectric 15 provided on a substrate 11 is carried out. Then, a step of forming an alloy layer 21 consisting of a CuMn alloy is carried out while covering the inner wall of the wiring groove 16. Next, the step is carried out wherein the wiring groove 16 is filled with the alloy layer 21 by making the alloy layer 21 flow via reflow processing, and a self-formed barrier film 22 consisting of an Mn compound having the diffusion barrier properties for Cu is formed at the interface between the alloy layer 21 and the interlayer dielectrics 12, 15 by making Mn in the alloy layer 21 react with the constituents of the interlayer dielectrics 12, 15. COPYRIGHT: (C)2008,JPO&INPIT
TL;DR: Titanium powders are densified together with steel spheres, wires or wire meshes which are subsequently removed by electrochemical dissolution, creating porosity that replicates the steel spaceholders as discussed by the authors.
Abstract: Titanium powders are densified together with steel spheres, wires or wire meshes which are subsequently removed by electrochemical dissolution, creating porosity that replicates the steel space-holders. Interdiffusion between steel and titanium is prevented by formation of a TiC diffusion barrier. Without this barrier, a Fe-containing titanium zone adjacent to the space-holder is formed which can be removed electrochemically, thus increasing the size and volume fraction of the pores.
Patent•
29 May 2008TL;DR: In this paper, a thin-film transistor includes a gate electrode, a first insulating layer, a semiconductor layer, and a hydrogen diffusion barrier layer covering the channel region and exposing the source and drain regions.
Abstract: A thin film transistor includes a gate electrode, a first insulating layer on the gate electrode, a semiconductor layer on the gate electrode and separated from the gate electrode by the first insulating layer, the semiconductor layer including a channel region corresponding to the gate electrode, a source region, and a drain region, a hydrogen diffusion barrier layer on the semiconductor layer, the hydrogen diffusion barrier layer covering the channel region and exposing the source and drain regions, and a second insulation layer on the source and drain regions and on the hydrogen diffusion barrier layer, such that the hydrogen diffusion barrier layer is between the second insulation layer and the channel region.
TL;DR: In this article, a selective oxidation technique has been applied to form a diffusion barrier on the Ni-based superalloy substrate by heating the substrate with electron beam of the electron beam-physical vapor deposition (EB-PVD) facility.
TL;DR: In this paper, Ru-incorporated TaN (Ru-TaN) films were investigated as a Cu diffusion barrier material and they were prepared by sequential deposition of Ru and TaN using plasma-enhanced atomic layer deposition.
Abstract: Ru-incorporated TaN (Ru-TaN) films were investigated as a Cu diffusion barrier material. Ru-TaN films were prepared by sequential deposition of Ru and TaN using plasma-enhanced atomic layer deposition (PEALD). The film composition was controlled by the number of Ru unit cycles. While the resistivity of Ru-TaN films was increased abruptly at low Ru composition (∼0.06), the resistivity of Ru-TaN films was decreased gradually as the Ru composition increased after that composition. The crystal structures of Ru-TaN films were amorphous at the Ru composition range from 0.19 to 0.52 due to disturbance of grain growth. However, the Ru-TaN films had TaN-like structure below this range and Ru-like structure above this range. The amorphous Ru-TaN films had nanocrystallite embedded structure in an amorphous matrix. This amorphous Ru-TaN barrier showed a better Cu diffusion barrier property (∼700°C) than the TaN barrier (∼650°C) because the Cu diffusion through the grain boundary was suppressed by the amorphization. In addition, the Ru-TaN barrier exhibited good adhesion to both Cu and SiO 2 .
TL;DR: In this paper, the copper diffusion barrier properties of P doped Ru film are studied, which improves copper barrier properties and has excellent thermal stability and is an alternative Cu diffusion barrier for advanced Cu interconnects.
TL;DR: In this article, Ru-Ta-N and Ru-N films are applied as a diffusion barrier in the Cu/bartier/SiO 2 /Si multilayered systems.
Abstract: Ultrathin Ru-N and Ru-Ta-N films (∼ 15 nm in thickness) deposited by reactive sputtering are applied as a diffusion barrier in the Cu/bartier/SiO 2 /Si systems. After film deposition, the samples are tested before and after annealing at 200-900°C in vacuum for 30 min. The sheet resistance examined by four-point probe appraises that the Ru-Ta-N barrier would not fail until annealing at 900°C, as compared to Ru-N, which fails after annealing at 600°C. The depth distribution of elements examined by Auger electron spectroscopy confirms different degrees of Cu diffusion into underlayers for the two systems after annealing at 600°C. Also, the cross-sectional microstructures of the Cu/barrier/SiO 2 /Si samples analyzed by transmission electron microscopy, the crystallinity of barrier films examined by grazing incident angle X-ray diffraction, and the chemical state of barrier characterized by X-ray photoelectron spectroscope might explain the difference in barrier performance for the ultrathin Ru-N and Ru-Ta-N films in the Cu/barrier/SiO 2 /Si multilayered systems.
TL;DR: In this paper, the effect of top metal electrodes on the electrical characteristics of Al2O3 metal-insulator-metal capacitors was studied and the leakage current and breakdown characteristics were observed to have a strong dependence on the electrode material.
Abstract: The effect of top metal electrodes on the electrical characteristics of Al2O3 metal-insulator-metal capacitors is studied. The leakage current and breakdown characteristics were observed to have a strong dependence on the electrode material. Devices with Al electrodes exhibited significantly higher breakdown voltages compared to devices with Au, Ni, Cu, and Ag electrodes. Introducing an Al diffusion barrier dramatically increased the breakdown field and reduced the leakage current for capacitors with Ag, Au, and Cu electrodes. The electrical characteristics were found to relate well to material properties of the contacting metals, such as ionization potential and diffusion coefficient.
TL;DR: In this paper, the authors used energetic reactive ion bombardment during simultaneous pulsed laser deposition to enhance film crystallization at low temperatures, and showed improved hardness in comparison to amorphous films.
Patent•
28 Feb 2008
TL;DR: In this paper, a self-formation barrier film composed of an Mn compound having copper diffusion barrier performance at the interface between the alloy layer 17 and the porous film 20 was constructed to prevent the peeling of an electrically conductive layer without making the concentration of Mn in an alloy layer high.
Abstract: PROBLEM TO BE SOLVED: To provide a semiconductor device and a manufacturing method thereof for preventing the peeling of an electrically conductive layer without making the concentration of Mn in an alloy layer (seed layer) high SOLUTION: In this manufacturing method of the semiconductor device, first, a wiring groove 16 is formed on an interlayer insulating film 15 formed on a substrate 11, and a porous film 20 is formed covering the inner wall of the wiring groove 16 Then, the alloy layer 17 composed of a CuMn alloy is formed on the porous film 20 in a state of covering the inner wall of the wiring groove 16 Then, the wiring groove 16 having the alloy layer 17 is filled with an electricity conductive layer 18 whose main component is Cu Subsequently, heat treatment is carried out to make Mn in the alloy layer 17 react with the constituent of the porous film 20 to form a self-formation barrier film 19 composed of an Mn compound having copper diffusion barrier performance at the interface between the alloy layer 17 and the porous film 20 COPYRIGHT: (C)2008,JPO&INPIT
TL;DR: In this paper, the authors investigated the applicability of self-formation of the diffusion barrier between Cu(Ti) films and SiO2/Si substrates after annealing at elevated temperatures.
Abstract: In our previous studies, thin Ti-rich diffusion barrier layers were found to be formed at the interface between Cu(Ti) films and SiO2/Si substrates after annealing at elevated temperatures. This technique was called self-formation of the diffusion barrier, and is attractive for fabrication of ultralarge-scale integrated (ULSI) interconnects. In the present study, we investigated the applicability of this technique to Cu(Ti) alloy films which were deposited on low dielectric constant (low-k) materials (SiOxCy), SiCO, and SiCN dielectric layers, which are potential dielectric layers for future ULSI Si devices. The microstructures were analyzed by transmission electron microscopy (TEM) and secondary-ion mass spectrometry (SIMS), and correlated with the electrical properties of the Cu(Ti) films. It was concluded that the Ti-rich interface layers were formed in all the Cu(Ti)/dielectric-layer samples. The primary factor to control the composition of the self-formed Ti-rich interface layers was the C concentration in the dielectric layers rather than the enthalpy of formation of the Ti compounds (TiC, TiSi, and TiN). Crystalline TiC was formed on the dielectric layers with a C concentration higher than 17 at.%.
TL;DR: In this paper, the thermal stability of Ni"2Si/n-SiC contacts with Au overlayer without or with Ta-Si-N diffusion barrier was investigated after long anneals at 400^oC in air.
TL;DR: In this paper, an atomic layer deposited (ALD)-Ru thin films between Cu and Si were improved with the use of an underlying 2 nm thick ALD-TaCN interlayer as diffusion barrier for the direct plating of Cu.
Abstract: Diffusion barrier performances of atomic layer deposited (ALD)-Ru thin films between Cu and Si were improved with the use of an underlying 2 nm thick ALD-TaCN interlayer as diffusion barrier for the direct plating of Cu. Ru was deposited by a sequential supply of bis(ethylcyclopentadienyl)ruthenium [Ru(EtC p ) 2 ] and NH 3 plasma and TaCN by a sequential supply of (NEt 2 ) 3 Ta = Nbu t (tert-butylimido-trisdiethylamido-tantalum), and H 2 plasma. Sheet resistance measurements, X-ray diffractometry, and Auger electron spectroscopy analysis showed that the bilayer diffusion barriers of ALD-Ru (12 nm)/ALD-TaCN (2 nm) and ALD-Ru (4 nm)/ALD-TaCN (2 nm) prevented the Cu diffusion up to annealing temperatures of 600 and 550°C for 30 min, respectively. This is because of the excellent diffusion barrier performance of the ALD-TaCN film against the Cu, due to its amorphous structure. A 5 nm thick ALD-TaCN film was even stable up to annealing at 650°C between Cu and Si. Transmission electron microscopy investigation, combined with energy-dispersive spectroscopy analysis, revealed that the ALD-Ru/ALD-TaCN diffusion barrier failed by the Cu diffusion through the bilayer into the Si substrate. This is due to the ALD-TaCN interlayer preventing the interfacial reaction between the Ru and Si.