High-density Plasma Chemical Vapor Deposition Research Articles

Pore sealing of mesoporous silica low- k dielectrics by oxygen and argon plasma treatments

In this study, we have prepared surfactant templated mesoporous silica thin films as the ultralow- k dielectrics and a TaN X thin film deposited by plasma enhanced atomic layer chemical vapor deposition (PE-ALCVD) using TaCl 5 as the gas precursor was used as the diffusion barrier. Without any surface modification for the dielectric layer, Ta atoms could easily diffuse into the mesoporous layer seriously degrading dielectric properties. O 2 and Ar plasmas have been used to modify the surface of the mesoporous dielectric in a high density plasma chemical vapor deposition (HDP-CVD) system, and both of the treatments produced a densified oxide layer a few nanometer thick. According to transmission electron microscopy and Auger electron spectroscopy, the pore sealing treatment could effectively prevent Ta atoms from diffusing into the mesoporous dielectric during the PE-ALCVD process.

Study on Fluorine Incorporation during Etch Step for HDP-CVD Oxide Gap-Filling of Nano-Scale Shallow-Trench Isolation

For gaplling of nano-scale shallow trench isolation (STI) with no voids in high-density plasma chemical vapor deposition (HDP-CVD), an etch gas containing NF3 in the continuous deposition/etch or cyclic deposition-etch-deposition (DED) processes has been adopted and in turn its use has led to uorine incorporation. Since F incorporation observed during the gapll process is known to a ect the post-process after gapll, a control and an understanding of uorine incorporation in the etch step is required. Fluorine incorporation in the HDP-CVD oxide was investigated by varying the NF3/O2 and the NF3/Ar plasma conditions during the etch step in the reactive ion etching (RIE) and the chemical dry etching (CDE) modes. As the ow ratio of NF3 gas was increased, the uorine incorporation increased. As a result of the increased F incorporation with increasing NF3 ow ratio, wet etch rates of plasma-etched HDP oxides increased.

Improvement of Thermal Stability of Magnetoresistive Random Access Memory Device with SiN Protective Film Deposited by High-Density Plasma Chemical Vapor Deposition

Embedded magnetoresistive random access memory (MRAM) with multi-level interconnects necessitates that magnetic tunnel junction (MTJ) devices have a thermal stability of 350 °C or higher during fabrication. We have improved thermal stability of MRAM devices using SiN protective film deposited by high-density plasma chemical vapor deposition (HDP-CVD) at 200 °C. The MTJ devices with HDP-CVD SiN protective film did not degrade after post-annealing at 350 °C, which suggests that the HDP-CVD process reduced oxide metal on the etched surface of the MTJ devices and that the SiN film blocked H2O diffusion from the interlayer dielectric film during post-annealing at 350 °C. We also fabricated a 1-kbit MRAM array and experimentally demonstrated thermal stability at 350 °C.

Thermal properties of hydrogenated amorphous silicon prepared by high-density plasma chemical vapor deposition

The properties of hydrogenated amorphous silicon (a-Si:H) deposited by plasma enhanced chemical vapor deposition (PECVD) have been widely investigated. In this paper, a-Si:H films were prepared by high-density plasma chemical vapor deposition (HDP-CVD) with high power density of 3.18 W/cm 2 and high deposition rate of 2.6 nm/s. The correlation between the characteristics of Si–H n bonds and annealing temperature was investigated. Furthermore, the variation of the film stress against temperature that correlates to the hydrogen desorption at different stages during thermal annealing has also been studied in this work. The FTIR spectra show that Si–H n bond almost disappeared when annealed above 400 °C, and the film started to condense. On the other hand, thermal desorption spectra (TDS) resulted in the Si–H n bond breaking at during about 300–600 °C and the behavior of H 2 desorption remaining the same as the stress variation.

Influence of RF Bias on Hydrogenated Amorphous Silicon by High-Density Plasma Chemical Vapor Deposition

We investigate the microstructure and thermal stability of hydrogenated amorphous silicon thin films deposited by high-density plasma chemical vapor deposition (HDP-CVD) with various biases using radio frequency (rf) power. The films were prepared without external heating at a high rf power density of , with the rf power bias varying from 0 to . Because sputtering also occurs during deposition, hydrogen may be present in a variety of bonding configurations in the films with various biases. Fourier transform infrared spectra show that the HDP-CVD films possess more hydrogen content as well as stretching modes than the conventional plasma-enhanced CVD counterpart. The surface morphology of the films becomes smooth upon ion bombardment under rf bias. In addition, variations of the film stress against temperature correlate to the hydrogen desorption at different stages during thermal annealing. More importantly, the different bonding configurations affect the crystallization behavior upon thermal annealing.

Germanium-Silicon Separate Absorption and Multiplication Avalanche Photodetectors Fabricated with Low Temperature High Density Plasma Chemical Vapor Deposited Germanium

AbstractA desire to monolithically integrate near infrared (NIR) detectors with silicon complementary metal oxide semiconductor (CMOS) technology has motivated many investigations of single crystal germanium on silicon (Ge/Si) diodes [1-3]. Reduction of the epitaxy thermal budget below the typical chemical vapor deposition (CVD) in-situ clean temperature (Tin-situ clean > 780°C) is also increasingly desired to reduce integration complexity. Reduced temperature growth approaches have included p+-Ge/n-Si detectors formed with low temperature poly-Ge (e-beam evaporation) or heavily dislocated single crystal germanium (molecular beam epitaxy, T ~ 450°C), which have had dark currents of ~5 mA/cm2 and responsivities of ~15 mA/W at 1310 nm, despite the large number of defects in and at the Ge/Si interface. Responsivities in these materials are however low and believed to be limited by a small diffusion length (i.e., 5-30 nm [2, 4]) due to fast electron recombination in the defect rich germanium. In this paper, we evaluate a commercially available high density plasma chemical vapor deposition (HDP-CVD) process to grow low temperature (i.e., Tin-situ & Tepitaxy < ~450°C) germanium epitaxy for a p+-Ge/p-Si/n+-Si NIR separate absorption and multiplication avalanche photodetectors (SAM-APD). This device structure is of interest both to examine ways to enhance the responsivity with internal gain as well as to examine alternatives to InGaAs-InP structures for NIR Geiger mode (GM) detection. A silicon avalanche region is highly desirable for GM to reduce after-pulsing effects, which are related to defect density that are smaller in Si than in InP [5]. Despite the high defect densities in the Ge and at the interface, the Ge-Si APDs in this work are found to have relatively low dark count rates in Geiger mode.

Suppression of hydrogen-ion drift into underlying layers using plasma deposited silicon oxynitride film during high-density plasma chemical vapor deposition

Hydrogen ions drifting into underlying layers during HDP-CVD were successfully suppressed by the insertion of plasma deposited silicon oxynitride ( p-SiO x N y H z ) film, and the hydrogen-trapping mechanism was clarified. The hydrogen ions are trapped in bonding states, not in interstitial ones. After HDP-CVD undoped silicate glass (HDP-USG) film deposition on the p-SiO x N y H z film, the decrease of the dangling bonds in the p-SiO x N y H z film measured by ESR was much lower than the increase of the desorbed hydrogen concentration measured by TDS. These results suggest that new hydrogen-trapping sites are mainly generated from ESR-inactive bonds by drifted hydrogen ions and atomic hydrogen during HDP-CVD.

Effect of Fluorine on Characteristics of Shallow Trench Isolation Prepared Using High-Density Plasma Chemical Vapor Deposition Including NF3 Chemistry

We investigated whether the fluorine of the field oxide affected gate oxide reliability and some isolation characteristics of metal–oxide semiconductor (MOS) transistors for high-density dynamic random-access memory (DRAM). Fluorine was incorporated during high density plasma (HDP) chemical vapor deposition (CVD) using NF3 chemistry for better shallow trench isolation (STI) gap-filling ability. Considerable fluorine included in the field oxide during deposition diffused from the field oxide to the silicon surface of a shallow trench during the subsequent thermal processes. This fluorine of the field oxide did not degrade the gate oxide reliability such as SILC and charge-to-breakdown characteristics. Moreover, it could improve various transistor characteristics such as the junction leakage, isolation punch-through current and data retention time of a DRAM device. It was inferred that some improvement of the MOS transistor was obtained by the interaction of Si interface traps near the trench wall with fluorine and the reduction of the density of Si interface traps.

Dependence of RF Power Bias on Hydrogenated Amorphous Silicon by High-Density Plasma Chemical Vapor Deposition

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HDP-CVD STI oxide process with in situ post deposition laterally enhanced sputter etchback for the reduction of pattern-dependent film topography in deep submicron technologies

This paper introduces a postdeposition pattern-dependent topography-reduction enhancement to the high-density plasma chemical-vapor deposition (HDP-CVD)oxide profile for shallow trench isolation in deep submicron technologies. The enhancement is labeled "laterally enhanced sputter etchback" (L-SEB) and is carried out in situ in the HDP-CVD reactor after film deposition. The L-SEB is set up using O/sub 2/ and Ar at high O/sub 2/ flow. A design of experiment was run to search for optimum gas flow conditions. The optimized process is shown to yield significant lateral "pull-in" of the sizeable HDP oxide cones over large thin-oxide features and flattening of smaller cones over dense small features, without appreciable impact on field oxide (FOX) thickness or corner integrity. This contributes a significant improvement to an STI module that incorporates downstream planarization processes of reverse-tone etch (RTE) and chemical mechanical polishing (CMP). It also allows a start with a thinner film thickness and usage of a smaller lithography compensation factor for the reverse-tone mask, thus facilitating a smaller minimum feature for RTE exposure. These advantages enhance the manufacturability of the STI process module in terms of reducing the starting HDP film thickness,cutting down on etching and polishing times of RTE and CMP, respectively,and yielding better post-CMP within-die and within-wafer FOX uniformities.

Hydrogen Ion Drift into Underlying Oxides by RF Bias during High-Density Plasma Chemical Vapor Deposition

High-density plasma chemical vapor deposition (HDP-CVD) is a deposition method of current interest for the gap-filling process of the intermetal dielectric (IMD) in semiconductor circuits. We first demonstrated that hydrogen ions drift into underlying thermal oxides during HDP-CVD with a SiH4–O2–Ar system, and that they degrade the reliability of gate oxides. The characteristics of the oxides were investigated using secondary ion mass spectroscopy (SIMS), thermal desorption spectroscopy (TDS), and capacitance–voltage (C–V) measurements of metal–oxide–semiconductor (MOS) capacitors. The hydrogen ions that are dissociated from SiH4 in plasma penetrate into the HDP-CVD oxides, and some of the hydrogen ions in the HDP-CVD oxides drift into the underlying thermal oxides by rf bias. The drifting hydrogen creates two chemical bonding states and generates hole trap sites in the underlying thermal oxides.

Deposition temperature determination of HDPCVD silicon dioxide films

High density plasma chemical vapor deposition (HDPCVD) is a widely used technique in semiconductor integrated circuit (IC) manufacturing, especially to form inter-metal silicon (IMD) dioxide thin films. It was designed for commercially available tools in order to satisfy the gap filling requirements necessary for 0.18 and 0.15 μm technology ICs, but it has been successfully extended also for 0.13 μm technological node and over. HDPCVD technique has a potential impact on device electrical characteristics and metallurgy compatibility, according to process conditions, such as deposition temperature. The work here presented deals with some physical–chemical characteristics of the HDPCVD deposited thin un-doped silicate glass (USG) films used in IC architecture. In a particular way, the dependence of the Si–OH bond concentration, revealed by FTIR, wet etch rate ratio compared with thermal SiO 2 and hydrogen content, determined by elastic recoil detection analysis (ERDA), are correlated with deposition temperature. The results demonstrate how it is possible after film deposition to reveal from the HDPCVD USG film itself which real temperature it has been deposited at, allowing a practical method in production environment for statistical process control.

Characterization and thermal stability of fluorosilicate glass films deposited by high density plasma chemical vapor deposition with different bias power

High-density plasma chemical vapor deposition (HDP-CVD) fluorosilicate glass (FSG) films were evaluated for the application of inter-metal dielectric (IMD) materials in current devices. Film characteristics were examined as a function of deposition/sputter etch (D/S) ratio, which was controlled by the bias power in HDP-CVD. FTIR spectra show that the positions of Si–O and Si–F peaks are independent of the bias power, but the Si–O shifted to a higher wave number and Si–F 2 appeared upon annealing for the films deposited at lower bias power. Stress hysteresis of the FSG films after the first thermal cycle shows a nonequilibrium nature of the microstructure related to impurity content, especially for the film deposited with lower bias power. Thermal desorption of H 2O, F, O 2 and Ar were examined, while most of the desorption behaviour can be related to the physical pore structure and pore quantity.

Effect of high-voltage sheath electric field and ion-enhanced etching on growth of carbon nanofibers in high-density plasma chemical-vapor deposition

The results of a parametric study on the growth of vertically aligned carbon nanofibers (CNFs) by high-density inductively coupled plasma (ICP) chemical-vapor deposition are reported. We investigated the mechanisms that cause the detachment of CNFs during the growth process by high-density plasma-enhanced chemical-vapor deposition with high substrate bias voltage and atomic hydrogen concentration. A simplified model, combining the Child law for sheath field, floating sphere model for field enhancement at the fiber tip and electric-field screening effect, was employed to estimate the detachment electrostatic force on individual CNFs induced by plasma sheath electric field. The force was found to increase with substrate bias voltage, bias current, and lengths of CNFs, consistent with the experimental observations that CNFs density decreases with ICP power, bias power, and growth time. However, the magnitude of the electrostatic force per se cannot explain the detachment phenomena. The other factor is believed to be the ion-assisted etch of CNFs by atomic hydrogen during the growth process since it was observed that the lower end of CNFs formed earlier in the synthesis process became thinner than the tip end.

Characterization of sputter-induced temperature effect in fluorine doped SiO 2 film deposition by high-density plasma chemical vapor deposition

High-density plasma chemical vapor deposited fluorosilicate glass (FSG) has been successfully used for the inter-metal dielectric material in ultra-large semiconductor integration manufacturing due to its low-dielectric constant and stable gap-filling capability. However, temperatures rise and related effects due to sputter etch from the deposition process have become major concerns for film properties. In this paper, an independent helium-cooling system was employed to control a suitable temperature range from 410 °C to 460 °C during FSG deposition. Subsequently, film properties including fluorine concentration, distribution, refractive index, dielectric constant and gap-filling capability were thus examined as a function of He pressure used in the cooling system. The results show that both deposition rate and fluorine concentration increase with increasing helium pressure; however, more fluorine becomes inactive, which might be present as defects. We have shown that an FSG film with a dielectric constant down to 3.43 as well as good gap-filling capability can be achieved when employing this new cooling system with 9 mTorr helium pressure.

Electrical Conduction Mechanisms of Nitrogenated Amorphous Carbon Films Deposited by High‐Density Plasma Chemical Vapor Deposition

AbstractSummary: In this work, we study the electrical conduction mechanisms of nitrogenated amorphous carbon (a‐C:H:N) films, which were deposited by a high‐density plasma chemical vapor deposition (HDP‐CVD) technique. The plasma was inductively coupled by an external planar coil. Mixtures of methane and nitrogen at different concentrations were used in the depositions. The working pressure process was 15 mTorr and the RF power was 250 W. An analysis focused on the influence of the precursor gases and plasma parameters on the conduction mechanisms of the a‐C:H:N films is reported. Current‐voltage (I‐V) curves were used to study the conduction mechanisms of the a‐C:H:N films. As a result of these studies we observed that the main electrical conduction mechanism found in the I‐V characteristics of our a‐C:H:N films was the Poole‐Frenkel emission. I‐V curves were also obtained in the range of 0–100 V and they were used to determine the electrical resistivity of the films.Current‐voltage characteristics of the a‐C:H:N films deposited with various N2 content in the discharge.magnified imageCurrent‐voltage characteristics of the a‐C:H:N films deposited with various N2 content in the discharge.

Novel Shallow Trench Isolation Process from Viewpoint of Total Strain Process Design for 45 nm Node Devices and Beyond

In this paper, a novel shallow trench isolation (STI) process is proposed for 45 nm node technologies and beyond. The major features of this process are the use of a fluorine-doped (F-doped) SiO2 film for gap filling and high-temperature rapid thermal oxidation (HT-RTO) for gate oxidation. Voidless filling of a narrow trench can be realized by F-doped high-density plasma chemical vapor deposition (F-doped HDP-CVD). Moreover, electron mobility degradation caused by STI stress and junction leakage currents can be minimized using F-doped HDP-CVD with HT-RTO. It was also confirmed that compressive stress in the F-doped HDP-CVD sample is smaller in every measurement point around STI than that in the conventional HDP-CVD sample by convergent-beam electron diffraction (CBED). The Si-F bonds in the oxide film play a very important role in stress reduction. By utilizing HT-RTO, Si-F bonds remain and make the SiO2 film in the trench coarse. This technique is a very promising 45 nm node STI scheme with high performance and high reliability.

Conductance Fluctuations in Amorphous Silicon Nanoparticles

AbstractHydrogenated amorphous silicon nanoparticles with an average diameter of 150 nm have been synthesized by high-density plasma chemical vapor deposition. The particles are deposited onto a conducting substrate and are then surrounded by an insulating matrix, electrically isolating the particles. Electrical contact is made to the top of each nanoparticle; the current-voltage characteristics of the nanoparticles indicate that transport is space-charge limited through the a-Si:H. The spectral density of the current fluctuations in the a-Si:H nanoparticles is well described by a 1/f frequency dependence for frequency f. However, the octave separation dependence of the correlation coefficients of the noise power for the nanoparticles are very well described by an ensemble of fluctuators whose amplitudes are independently modulated in parallel, rather than the serial kinetics typically observed in bulk a-Si:H.

Fabrication of autocloned photonic crystals by using high-density-plasma chemical vapor deposition

The high-density-plasma chemical vapor deposition (HDP-CVD) method was demonstrated as an alternative to radio-frequency (rf) bias sputtering method for fabrication of “autocloned” photonic crystals. We successfully preserved periodic surface corrugation after deposition of multilayer stacks under appropriate chemical vapor deposition conditions. Freedom of the shaping process was increased by simply raising the bias power of the autocloning process, and thus created autocloned structures having a strong modulation of the effective refractive index in the lateral direction. The method allows photonic bands of autocloned photonic crystals to be designed with greater controllability and a simpler fabrication process. Furthermore, the HDP-CVD method has better step-coverage than the sputtering method and can be used to fabricate autocloning structures with small feature-sizes.

Correlation between the dielectric constant and X-ray diffraction pattern of Si-O-C thin films with hydrogen bonds

The amorphous structure of organic–inorganic hybrid type Si-O-C thin films was studied using the first principles molecular-dynamics method with density functional techniques. The correlation between the dielectric constant and the degree of amorphous structure in organic–inorganic hybrid type Si-O-C thin films was studied. Si-O-C thin films were deposited by high-density plasma chemical vapor deposition using bis-trimethylsilylmethane and oxygen precursors. As-deposited films and films annealed at 500 °C were analyzed by X-ray diffraction (XRD). For quantitative analysis, the X-ray diffraction patterns of the samples were transformed to the radial distribution function (RDF) using Fourier analysis. Hybrid type Si-O-C thin films can be divided into three types using their amorphous structure and the dielectric constant: those with organic, hybrid, and inorganic properties.