Plasma-enhanced Chemical Vapor Deposition Process Research Articles

Novel Precursors for SiCH Low-k Caps beyond the 22 nm Node: Reactions of Silacyclopentane Precursors in the Plasma-Enhanced Chemical Vapor Deposition Process and Structural Analyses of SiCH Films

To form SiCH films with high carbon content using plasma-enhanced chemical vapor deposition (PECVD), 1,1-divinylsilacyclopentane (DVScP) and 5-silaspiro[4,4]nonane (SSN) were designed as novel precursors for the low-k cap layer and Cu diffusion barrier at the top of Cu lines. We elucidated the relationship between the structure of low-k SiCH films made from these newly developed precursors and their barrier properties against copper and oxygen diffusion. We also studied the relationship between the structure of SiCH and the deposition process under various RF plasma powers. A Monte Carlo simulation was employed to estimate the deposition profile using an overhang test structure. Fourier transform infrared (FT-IR) spectroscopy was used to analyze the molecular structures. Our novel silacyclopentanes formed SiCH films with high carbon content and good barrier properties at high RF powers due to the specific reactions of silacyclopentanes designed according to our quantum chemical calculations. Precursor design is thus an important factor in forming SiCH with high carbon content that achieves both lower k and good barrier properties.

Novel Precursors for SiCH Low-kCaps beyond the 22 nm Node: Reactions of Silacyclopentane Precursors in the Plasma-Enhanced Chemical Vapor Deposition Process and Structural Analyses of SiCH Films

Novel Precursors for SiCH Low-<i>k</i>Caps beyond the 22 nm Node: Reactions of Silacyclopentane Precursors in the Plasma-Enhanced Chemical Vapor Deposition Process and Structural Analyses of SiCH Films

Enhanced Growth and Osteogenic Differentiation of Human Osteoblast-Like Cells on Boron-Doped Nanocrystalline Diamond Thin Films

Intrinsic nanocrystalline diamond (NCD) films have been proven to be promising substrates for the adhesion, growth and osteogenic differentiation of bone-derived cells. To understand the role of various degrees of doping (semiconducting to metallic-like), the NCD films were deposited on silicon substrates by a microwave plasma-enhanced CVD process and their boron doping was achieved by adding trimethylboron to the CH4:H2 gas mixture, the B∶C ratio was 133, 1000 and 6700 ppm. The room temperature electrical resistivity of the films decreased from >10 MΩ (undoped films) to 55 kΩ, 0.6 kΩ, and 0.3 kΩ (doped films with 133, 1000 and 6700 ppm of B, respectively). The increase in the number of human osteoblast-like MG 63 cells in 7-day-old cultures on NCD films was most apparent on the NCD films doped with 133 and 1000 ppm of B (153,000±14,000 and 152,000±10,000 cells/cm2, respectively, compared to 113,000±10,000 cells/cm2 on undoped NCD films). As measured by ELISA per mg of total protein, the cells on NCD with 133 and 1000 ppm of B also contained the highest concentrations of collagen I and alkaline phosphatase, respectively. On the NCD films with 6700 ppm of B, the cells contained the highest concentration of focal adhesion protein vinculin, and the highest amount of collagen I was adsorbed. The concentration of osteocalcin also increased with increasing level of B doping. The cell viability on all tested NCD films was almost 100%. Measurements of the concentration of ICAM-1, i.e. an immunoglobuline adhesion molecule binding inflammatory cells, suggested that the cells on the NCD films did not undergo significant immune activation. Thus, the potential of NCD films for bone tissue regeneration can be further enhanced and tailored by B doping and that B doping up to metallic-like levels is not detrimental for cells.

Plasma enhanced atomic layer deposition of SiNx:H and SiO2

As the nanoelectronics industry looks to transition to both three dimensional transistor and interconnect technologies at the &amp;lt;22 nm node, highly conformal dielectric coatings with precise thickness control are increasingly being demanded. Plasma enhanced chemical vapor deposition (PECVD) currently fills this role for most applications requiring low temperature processing but does not always meet step coverage and thickness precision requirements. The authors present results for a hybrid technique, plasma enhanced atomic layer deposition (PEALD), which utilizes typical PECVD process gases and tooling while delivering improved topography coverage and thickness control. Specifically, the authors show that alternating SiH4 gas/N2 plasma exposures applied in an atomic layer deposition sequence can be used to deposit SiNx:H films in a self-limiting fashion with improved conformality and superior performance as a moisture barrier. PEALD of SiO2 using alternating SiH4 and CO2 plasma exposures is further demonstrated.

Thermal conductivity and sound velocity measurements of plasma enhanced chemical vapor deposited a-SiC:H thin films

We report ultrafast optical measurements of the thermal conductivity and longitudinal sound velocity for a-SiC:H thin films deposited by plasma enhanced chemical vapor deposition (PECVD). Porous and non-porous films with mass densities ranging from 1.0–2.5 g/cm 3 were obtained by intentionally varying the PECVD process conditions. The longitudinal sound velocities for these materials as determined by picosecond ultrasonics ranged from 2370 m/s to 10460 m/s, and the Young's modulus determined from the sound velocity measurements ranged from 5–200 GPa. Time domain thermoreflectance measurements determined the thermal conductivity to range from 0.0009 W/cmK to 0.042 W/cmK.

Complementary metal-oxide semiconductor-compatible silicon carbide pressure sensors based on bulk micromachining

This Letter presents a complementary metal-oxide semiconductor-compatible silicon carbide (SiC) absolute capacitive pressure sensor for harsh environmental applications. The pressure sensor was fabricated by bulk micromachining technology. Low-temperature SiC film was deposited by the plasma-enhanced chemical vapour deposition process and utilised as the moveable membrane of the device. Even though the deposited film has a good mechanical property and high chemical resistance, it takes low electric conductivity, thus tungsten(W) was used as the sensor&apos;s electrodes. This pressure sensor exhibits a linear response over a pressure range of 2 bars, with a total change of 507.1 mV (i.e. 0.274 pF). Furthermore, it is confirmed to withstand KOH etching for more than 30 min.

Importance of Starting Procedure for Film Growth in Substrate-Type Microcrystalline-Silicon Solar Cells

The starting procedure of hydrogenated microcrystalline-silicon (µc-Si:H) film growth at a high rate has been controlled in a plasma-enhanced chemical vapor deposition process to improve the optoelectronic properties of the resulting n/i interface as well as the intrinsic bulk layer in µc-Si:H-based substrate-type (n–i–p) solar cells. The electron temperature, monitored using optical emission spectroscopy, in the plasma during film growth is successfully controlled by changing the starting procedure, i.e., gradual SiH4 introduction and slow power application, leading to the preparation of high-quality µc-Si:H films with a low dangling-bond defect density. Reduction of the defect density in the intrinsic layer and improvement of the optoelectronic properties at the n/i interface are demonstrated through the fabrication of single-junction n–i–p solar cells showing high photovoltaic performance.

Low temperature deposition of high open-circuit voltage (>1.0 V) p–i–n type amorphous silicon solar cells

P–i–n type hydrogenated amorphous silicon (a-Si:H) solar cells were deposited by the radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) process at a low substrate temperature of 125 °C, which is compatible with low-cost poly (ethylene terephthalate) (PET) plastic substrates. Wide band gap ( E opt >1.88 eV) intrinsic a-Si:H films were achieved before the onset of the microcrystalline regime by changing the hydrogen dilution ratios. On the other hand, the structural, optical and electrical properties of p-type hydrogenated amorphous silicon carbide (p-a-SiC:H) window layers have been optimized at 125 °C. High quality p-a-SiC:H film with high optical band gap ( E 04=2.02 eV) and high conductivity ( σ d =1.0×10 −7 S/cm) was deposited at ‘low-power regime’ under low silane flow rates and high H 2 dilution conditions. With the combination of wide band gap p-a-SiC:H window layers and intrinsic a-Si:H layers, a high V oc of 1.01 V (efficiency=5.51%, FF=0.72, J sc =7.58 mA/cm 2) was obtained for single junction a-Si:H p–i–n solar cell at a low temperature of 125 °C. Finally, flexible a-Si:H solar cell on PET substrate with efficiency of 4.60% ( V oc =0.98 V, FF=0.69, J sc =6.82 mA/cm 2) was obtained.

Growth of bent carbon nanotubes by in-situ control of cantilever bending

A new and simple method for in-situ control of the growth direction of carbon nanotubes (CNTs) on cantilevers has been developed using plasma enhanced chemical vapor deposition (PECVD). Plasma-induced surface stresses in PECVD processes tend to cause bending of the cantilevers, which significantly changes the electric field distribution near the free-end of the cantilever. By adjusting the flow ratio of the feed gases during CNT growth, the degree of cantilever bending can be controlled due to the change in the plasma-induced surface stress, and in doing so manipulating the field line direction, as well as the growth direction of CNTs. Combining this in-situ tunable CNT growth technique with electron beam induced deposition of catalyst patterns, we have fabricated a bent CNT on a cantilever in one single, continuous deposition run.

Study of hybrid PVD–PECVD process of Ti sputtering in argon and acetylene

Hybrid PVD–PECVD process of target sputtering in hydrocarbon containing atmosphere combines aspects of both conventional reactive magnetron sputtering (PVD) and plasma enhanced chemical vapour deposition (PECVD). Such process is being typically used for deposition of metal carbides embedded in hydrogenated carbon matrix. Compared to the conventional co-sputtering of metal and carbon targets, in the hybrid deposition process the source of the carbon is dissociated hydrocarbon vapour in plasma. The aim of this paper is to study the extent of similarities or differences between this hybrid process and the conventional reactive magnetron sputtering. We have chosen the sputtering of titanium target in acetylene containing atmosphere as a representative of the hybrid processes. We focused on experimental measurements of the hybrid PVD–PECVD process behaviour, the time necessary for the process to achieve steady-state conditions and basic modelling of the process.

ChemInform Abstract: Production and Detection of H Atoms and Vibrationally Excited H2 Molecules in CVD Processes

AbstractReview: 184 refs.

The application of dry photoresists in fabricating cost-effective tapered through-silicon vias and redistribution lines in a single step

In this paper, we report a simple and cost-effective technique to fabricate a partially electroplated tapered through-silicon via (TSV) and redistribution line (RDL)-like structures on the field in a single process step using dry laminated photoresists. An array of 100 µm deep positively tapered silicon vias was etched by a three-step non-Bosch plasma etching process. Insulation, diffusion barrier and seed layers were deposited by low-temperature plasma-enhanced chemical vapor deposition and sputtering processes, respectively. A 15 µm thick dry MXA115 photoresist was laminated on the wafer by a roller-less vacuum lamination process. The dry resist allows a satisfactory patterning of the RDL-like structures by eliminating the chances of resist residuals falling in the etched TSVs. Direct-current (dc) electroplating was used to deposit 10 µm thick copper layers on the via sidewalls as well as on the field. Therefore, the electroplating not only partially fills the vias but also forms the RDL structures at the same time. Since both TSVs and RDLs are fabricated together in a single process step, several conventional process steps such as over-burden polishing, lithography, and metal etching were avoided. Compared to the conventional TSV fabrication processes, this dry resist lithography-based method turned out to be simple and very cost-effective in making complex TSV interconnects.

Plasma Composition by Mass Spectrometry in a Ar-SiH4-H2 LEPECVD Process During nc-Si Deposition

Mass spectrometry has been used to assess plasma composition during a low-energy plasma-enhanced chemical vapor deposition (LEPECVD) process using argon-silane-hydrogen (Ar-SiH4-H2) gas mixtures with input flows of 50 sccm Ar, 2–20 sccm SiH4 and 0–50 sccm H2 at total pressures of 1–4 Pa. Energy-integrated ion densities, residual gas analysis and threshold ionization mass spectrometry have been used to characterize the transition from amorphous (a-Si) to nano-crystalline silicon (nc-Si) deposition at constant LEPECVD operating parameters. While relative ion densities have a marked decrease with H2 input, the densities of SiHx (x < 4) radicals show evolution trends depending on the SiH4 and H2 input. For conditions leading to nc-Si growth a turning point is reached above which SiH is the main radical. Observed SiHx density trends with H2 input are explained based on kinetic reaction rates calculated from previously obtained Langmuir probe data.

Atomic Layer Deposition of Aluminum Oxide for Surface Passivation of InGaAs/InP Heterojunction Bipolar Transistors

In this paper, the growth and material properties of Al2O3 layers grown by thermal atomic layer deposition (ALD) with water vapor, and plasma ALD with oxygen plasma are examined by spectroscopic ellipsometry and X-ray reflectivity on Si substrates and InGaAs/InP epilayers. The thermal-ALD and plasma-ALD deposited Al2O3 layers have subsequently been used to passivate the surface of InGaAs/InP heterojunction bipolar transistors (HBTs). The impact and efficiency of the ALD-Al2O3 passivation layers have been evaluated using the dc current gain and breakdown voltage of the InGaAs/InP HBTs. For comparison, the results from these experiments are contrasted with results from similar samples passivated with SiO2 using conventional plasma enhanced chemical vapor deposition (PECVD). The thermal-ALD-Al2O3 passivated InGaAs/InP HBTs show higher current gains as compared to structures passivated using the plasma-ALD or PECVD processes, suggesting differences in the dielectric-semiconductor interface properties. More importantly, as compared to PECVD-SiO2, the common emitter characteristics of both (thermal and plasma) ALD-Al2O3 passivated HBTs show fairly stable device breakdown voltage, which is of particular importance, especially in analog applications.

Modeling and Simulation of a Chemical Vapor Deposition

We are motivated to model PE‐CVD (plasma enhanced chemical vapor deposition) processes for metallic bipolar plates, and their optimization for depositing a heterogeneous layer on the metallic plate. Moreover a constraint to the deposition process is a very low pressure (nearly a vacuum) and a low temperature (about 400 K). The contribution of this paper is to derive a multiphysics system of multiple physics problems that includes some assumptions to simplify the complicate process and allows of deriving a computable mathematical model without neglecting the real‐life processes. To model the gaseous transport in the apparatus we employ mobile gas phase streams, immobile and mobile phases in a chamber that is filled with porous medium (plasma layers). Numerical methods are discussed to solve such multi‐scale and multi phase models and to obtain qualitative results for the delicate multiphysical processes in the chamber. We discuss a splitting analysis to couple such multiphysical problems. The verification of such a complicated model is done with real‐life experiments for single species. Such numerical simulations help to economize on expensive physical experiments and obtain control mechanisms for the delicate deposition process.

Iterative Operator Splitting Method for Coupled Problems: Transport and Electric Fields

In this article a new approach is considered for implementing operator splitting methods for transport problems, influenced by electric fields. Our motivation came to model PE-CVD (plasma-enhanced chemical vapor deposition) processes, means the flow of species to a gas-phase, which are influenced by an electric field. We consider a convection-diffusion equation and a Lorence force in the electrostatic case. The iterative splitting schemes is given as an embedded coupling method and we apply such a scheme as a fast solver. The decomposition analysis is discussed for the nonlinear case. Numerical experiments are given with respect to explicit Adam-Bashforth schemes. We discuss the convergence behavior in time and space for the iterative schemes.

Operator Splitting Method for Coupled Problems:Transport and Maxwell Equations

In this article a new approach is considered for implementing operator splitting methods for transport problems, influenced by electric fields. Our motivation came to model PE-CVD (plasma-enhanced chemical vapor deposition) processes, means the flow of species to a gas-phase, which are influenced by an electric field. Such a field we can model by wave equations. The main contributions are to improve the standard discretization schemes of each part of the coupling equation. So we discuss an improvement with implicit Runge- Kutta methods instead of the Yee’s algorithm. Further we balance the solver method between the Maxwell and Transport equation.

Transient Phenomena in Plasma-Enhanced Chemical Vapor Deposition Processes of Thin-Film Silicon

The time-dependent gas phase kinetics in plasma-enhanced chemical vapor deposition (PECVD) processes has been studied. The temporal evolutions of the gas phase species, concentration and plasma parameters are measured in hydrogen-diluted silane plasmas, using plasma diagnostic techniques including mass spectrometry, optical emission spectroscopy, and probe and laser light scattering techniques. It is identified that gas phase kinetics such as electron collisions, chemical reactions, and particle transport play important roles in the transient phenomena of thin-film silicon PECVD processes. The characteristic times of the gas decomposition and depletion, diffusive transport, and nanoparticle growth and drift are discussed.

Plasma Enhanced Atomic Layer Deposition of SiN:H Using N2 and Silane

As the nano-electronics industry looks to transition to both three dimensional transistor and interconnect technologies at the < 22 nm node, highly conformal dielectric coatings with precise thickness control are increasingly being demanded. Plasma Enhanced Chemical Vapor Deposition (PECVD) currently fills this role for most applications requiring low temperature processing, but does not always meet step coverage and thickness precision requirements. We present results for a hybrid technique, Plasma Enhanced Atomic Layer Deposition (PEALD), that utilizes typical PECVD process gases and tooling while delivering improved topography coverage and thickness control. Specifically, we show that alternating SiH4 gas / N2 plasma exposures applied in an atomic layer deposition sequence can be used to deposit SiN films in a self limiting fashion.

Corrosion resistance and chemical stability of super-hydrophobic film deposited on magnesium alloy AZ31 by microwave plasma-enhanced chemical vapor deposition

A super-hydrophobic film was successfully deposited on magnesium alloy AZ31 by the microwave plasma-enhanced chemical vapor deposition (MPECVD) process. The film surface showed a static water contact angle of more than 150°. The hydrophobicity and root mean square roughness of the film surface increased with an increase in deposition time. The anticorrosion resistance of the deposited film was estimated by electrochemical impedance spectroscopy (EIS) measurements. The EIS measurements and appropriate equivalent circuit models revealed that the super-hydrophobic film considerably improved the anticorrosion resistant performance of magnesium alloy AZ31. The anticorrosion mechanism of the super-hydrophobic film was also considered. Moreover, the chemical stability of the super-hydrophobic film in acidic, neutral, and alkaline aqueous solutions was investigated. The super-hydrophobic film showed high chemical stability in acidic and neutral aqueous solutions.