Cap Film Research Articles

Comparative study of the radio-frequency magnetron sputter deposited CaP films fabricated onto acid-etched or pulsed electron beam-treated titanium

This study investigated the effect of the substrate morphology introduced by various substrate preparation techniques, namely acid etching (AE) and pulsed electron beam (PEB) treatments, on the CaP film morphology and mechanical properties. The morphology, nanohardness, and Young's modulus of the CaP coating deposited via radio-frequency (RF) magnetron sputtering were investigated by X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), scanning electron microscopy and nanoindentation studies. The Ca/P ratios of the CaP coating deposited via RF magnetron sputtering onto titanium substrates treated using AE and PEB according to XPS were 1.73±0.03 and 1.72±0.04, respectively, which is close to the Ca/P ratio of 1.67 typical for stoichiometric hydroxyapatite (HA). The AFM experiments and nanoindentation studies revealed significant differences in the morphology and mechanical responses of the CaP films deposited onto acid-etched titanium substrates treated with PEB. Deposition of the CaP coating onto the acid-etched surface resulted in a rough surface with the presence of an island-like morphology. The CaP coating onto a smooth titanium substrate treated by PEB exhibited grains with irregular shapes and decreased size. The nanoindentation hardness and the Young's modulus of the HA coating deposited onto titanium treated by the PEB treatment were determined to be 7.0±0.3 and 124±3GPa, respectively, which are significantly higher than those of the CaP coating on the acid-etched titanium substrates. Moreover, the elastic strain to failure (H/E), the plastic deformation resistance (H3/E2), and the percent elastic recovery %R of the HA coating on titanium after surface irradiation with an electron energy density of 15J·cm−2 were determined to increase by ~23%, ~70% and ~53%, respectively, compared to the CaP coating on acid-etched titanium.

Ultrathin (8-14 nm) Conformal SiN for sub-20 nm Copper/Low-k Interconnects

Ever since Al(Cu) wires were replaced by Cu to reduce RC delay, the development of lower k dielectric materials has been a challenge to the back end of line (BEOL) process [1,2]. Copper wiring with low-k or ultra low-k (ULK) dielectrics for high-performance CMOS IC’s requires the use of a robust dielectric cap barrier to prevent inter- and intra-level Cu diffusion and also to maintain device yield and reliability. Plasma Enhanced Chemical Vapor Deposited (PECVD) low-k SiCNH and SiN are the predominant dielectric Cu diffusion caps used by the industry, in part due to the strong cap/Cu debond energies [3]. This paper will present the ultrathin (<15 nm) cyclic conformal multilayer SiN dielectric as potential dielectric caps and liner for capacitance reduction in sub-20nm Cu-Low k interconnect. We developed a new cyclic multilayer conformal ultrathin (8-14 nm) SiN deposition process to improve Cu CMP recess step coverage. This process includes cyclic low rf power plasma deposition of nano thick (~2 nm) SiN using Silane and Ammonia gases and then subsequent variable rf plasma power Nitrogen (N2) plasma treatment to minimize Cu sputtering and diffusion. The process is repeated in a cyclical manner until desirable film’s thickness is achieved, figure 1. The film deposition step and it enhanced STEM and EDX step coverage images for the post-CMP top corner Cu recess divot structure as showed in figure 2. The Triangular Voltage Test (TVS) and oxidation barrier (310 C, 24 hr exposure in air) evaluation showed this thin (10-14 nm thick ) SiN cap is a good oxidation and Cu barrier. Optimal cyclic SiN film has higher breakdown voltage and lower low leakage than standard SiCNH cap, even after exposure to UV cure, figure 3. As deposited, the SiN film has compressive stress in 500 MPa range. After UV direct UV exposure for 180 sec at 380C, the film’s stress still retain at 300 Mpa compressive. The cyclic SiN cap has excellent modulus of 159 GPa and hardness of 24 GPa. BEOL 80 nm pitch device electrical data showed that device reliability of the 10-12 nm SiN cap film are about comparable to standard 25 nm SiCNH cap but with significant lower device capacitance. SUMMARY A new generations of ultra-thin (<15 nm) conformal cyclic SiN dielectric cap with robust electrical, mechanical and oxidation barrier performance was developed for sub-20 nm Cu-Low k interconnect potential use as cap and liner. Acknowledgments: This work was performed by Alliance Teams at various IBM Research and Development Facilities and at University at Albany Nanotech Foundation.

Enhancement of CO2 Absorption under Taylor Flow in the Presence of Fine Particles

The physical absorption of CO2 in water containing different types of particles was studied in a microchannel operated under Taylor flow. The maximum enhancement factors of 1.43−2.15 were measured for activated carbon (AcC) particles. The analysis shows that the enhancement effect can be attributed to the shuttle mechanism. Considering the separate contributions of mass transfer from bubble cap and liquid film, a heterogeneous enhancement model is developed. According to this model, the enhancement factors ECap, EFilm and EOv are mainly determined by mass transfer coefficient KL (KL, Cap and KL, Film), adsorptive capacity of particles m, and coverage fraction of particles at gas-liquid interface χ. With both effects of particle-to-interface adhesion and apparent viscosity included, the model predicts the enhancement effect of AcC particles reasonably well.

Determining the bubble cap film thickness of bursting bubbles from their acoustic emissions

A study of the sound generated by 2.5 mm radius bubbles bursting on the surface of fresh water is presented. The sound pulses are found to be sensitive to the time interval between the bubble reaching the water surface and bursting. Bubbles that burst within a few 10's of milliseconds behave like a Helmholtz resonator and radiate a swept chirp pulse. Bubbles that persist for 100's of milliseconds or more exhibit more complex acoustic behavior. An analysis of the resonator behavior provides an estimate of the film thickness in reasonable agreement with a fluid drainage model.

Low Work Function between Erbium Silicide and n-type Silicon Controlled by Cap Film Stress

The electrical and physical properties of W capped ErSix on n-type Si(100), Si(111) and Si(551) surfaces are reported. The Schottky barrier heights (SBHs) are not determined by the growth of the ErSix crystal orientations, but are determined by the silicon surface orientations. And the SBHs are changed by the ratio of W capping layer thickness and ErSix thickness. These results are considered that the work function of ErSix can be controlled by the stress during the silicidation. These silicidation reactions are very important to develop the future high current drivability devices using any surface orientation.

A Study of SiCN Cap Process Resultant Plasma Induced Damage in 40nm Technology Node

Plasma processes are widely used in the manufacturing of very large scale integration (VLSl) devices for dry etching and dielectric film deposition. Damage due to plasma becomes inevitable and can potentially break the gate dielectric bonds to increase gate dielectric leakage current, which would give rise to transistor threshold voltage shift and device failure. In our 40nm device data, there was a gate oxide leakage failure dominantly in wafer center. It was found that this failure is related to SiCN Cu interconnect cap film deposition. The purpose of this work was to investigate its failure mechanism. In the current study, SiCN films were deposited with two different types of commercial tools. The SiCN film surface charge results showed that the charge value in wafer center was obviously higher than that in wafer edge. The plasma density measurement result also showed that plasma density in the chamber center is higher than that of wafer edge. Plasma induced damage (PID) test data showed that the deposition initial step, or the NH3 pretreatment stage, was not the key factor for the device damage, but the main step of SiCN film deposition played the important role in the device damage. By adjusting the main deposition step, the film surface charge value and the charge uniformity were much improved, which led to a solution to the wafer central PID issue at 40nm device.

Low Work Function between Erbium Silicide and n-type Silicon Control by Cap Film Stress

not Available.

Bursting bubble aerosols

AbstractWe depict and analyse the complete evolution of an air bubble formed in a water bulk, from the time it emerges at the liquid surface, up to its fragmentation into dispersed drops. To this end, experiments describing the drainage of the bubble cap film, its puncture and the resulting bursting dynamics determining the aerosol formation are conducted on tapwater bubbles. We discover that the mechanism of marginal pinching at the bubble foot and associated convection motions in the bubble cap, known as marginal regeneration, both drive the bubble cap drainage rate, and are responsible for its puncture. The resulting original film thickness $h$ evolution law in time, supplemented with considerations about the nucleation of holes piercing the film together culminate in a determination of the cap film thickness at bursting ${h}_{b} \propto {R}^{2} / \mathscr{L}$, where $R$ is the bubble cap radius of curvature, and $\mathscr{L}$ a length which we determine. Subsequent to a hole nucleation event, the cap bursting dynamics conditions the resulting spray. The latter depends both on the bubble shape prescribed by $R/ a$, where $a$ is the capillary length based on gravity, and on ${h}_{b} $. The mean drop size $\langle d\rangle \ensuremath{\sim} {R}^{3/ 8} \hspace{0.167em} { h}_{b}^{5/ 8} $, the number of drops generated per bubble $N\ensuremath{\sim} \mathop{ (R/ a)}\nolimits ^{2} \mathop{ (R/ {h}_{b} )}\nolimits ^{7/ 8} $ and the drop size distribution $P(d)$ are derived, comparing well with measurements. Combined with known bubble production rates over the ocean, our findings offer an adjustable parameter-free prediction for the aerosol flux and spray structure caused by bubble bursting in this precise context.

Novel Cap Annealing Process for SiC Crystal Using ECR-Sputtered Carbon Films and ECR Plasma Ashing

A high dose impurity doping process for 4H-SiC crystals has been developed using electron cyclotron resonance (ECR) sputtered carbon cap film and ECR plasma ashing. ECR-sputtered carbon films are newly found crystalline carbon films of which the hardness is comparable to that of diamonds. Since this carbon film showed such a high thermal tolerance that the hardness did not change after 1900oC annealing, this carbon cap film worked well for suppressing roughening during annealing for aluminum-ion implanted 4H-SiC. Cap carbon film can be removed successfully by using high density ECR plasma ashing.

Integration of Self-Assembled Porous Silica in Low-k/Cu Damascene Interconnects

Integration of a self-assembled porous silica film layered with a cap film was carried out for low-k/Cu damascene structures. The dielectric constant of the porous silica in the layered damascene structure was extracted, and the process-induced damage layer was characterized. Due to the integration process of low-k/Cu damascene, the hydrophobic methyl group was decomposed by plasma etching and subsequent barrier and seed sputtering as well as by Cu electroplating, resulting in the formation of hydrophilic silanol groups. The lateral dimension of the process-induced damaged layer and its effective dielectric constant were found to be 35 nm and 10, respectively.

Evaluation of plasma damage in ultra-low- k materials with cap film using “extracted k-value” method

An “extracted k-value” method has been developed for evaluating postdevice-process damage in ultra-low- k materials inside a multi-layer structure. It is found that an in-depth analysis with using X-ray reflectivity (XRR) is very effective for recognizing the nature of the damage. With these methods, it is investigated that the damage generated in porous methylsilsesquioxane (MSQ) during cap-film deposition and the effect of subsequent process for the improvement.

Biocompatibility of Solid-Dosage Forms of Anti-Human Immunodeficiency Virus Type 1 Microbicides with the Human Cervicovaginal Mucosa Modeled Ex Vivo

Topical anti-human immunodeficiency virus (HIV) microbicides are being sought to reduce the spread of HIV type 1 (HIV-1) during sexual intercourse. The success of this strategy depends upon the selection of formulations compatible with the natural vaginal mucosal barrier. This study applied ex vivo-modeled human cervicovaginal epithelium to evaluate experimental solid-dosage forms of the anti-HIV-1 microbicide cellulose acetate 1,2-benzenedicarboxylate (CAP) and over-the-counter (OTC) vaginal products for their impact on inflammatory mediators regarded as potential HIV-1-enhancing risk factors. We assessed product-induced imbalances between interleukin-1alpha (IL-1alpha) and IL-1beta and the natural IL-1 receptor antagonist (IL-1RA) and changes in levels of IL-6, tumor necrosis factor alpha, IL-8, gamma interferon inducible protein 10 (IP-10), and macrophage inflammatory protein 3alpha (MIP-3alpha), known to recruit and activate monocytes, dendritic cells, and T cells to the inflamed mucosa. CAP film and gel formulation, similarly to the hydroxyethylcellulose universal vaginal placebo gel and the OTC K-Y moisturizing gel, were nontoxic and caused no significant changes in any inflammatory biomarker. In contrast, OTC vaginal cleansing and contraceptive films containing octoxynol-9 or nonoxynol-9 (N-9) demonstrated similar levels of toxicity but distinct immunoinflammatory profiles. IL-1alpha, IL-1beta, IL-8, and IP-10 were increased after treatment with both OTC vaginal cleansing and contraceptive films; however, MIP-3alpha was significantly elevated by the N-9-based film only (P < 0.01). Although both films increased extracellular IL-1RA, the cleansing film only significantly elevated the IL-1RA/IL-1 ratio (P < 0.001). The N-9-based film decreased intracellular IL-1RA (P < 0.05), which has anti-inflammatory intracrine functions. This study identifies immunoinflammatory biomarkers that can discriminate between formulations better than toxicity assays and should be clinically validated in relevance to the risk of HIV-1 acquisition.

Characterization of Pd-free electroless Co-based cap selectively deposited on Cu surface via borane-based reducing agent

In this work, a highly selective and self-activated (Pd-free) Co-based deposition process for capping of Cu-lines is presented. TEM images of the cross-section of capped Cu-lines show no extraneous deposition, which translates to selectivity and direct deposition of Co-based alloy on the Cu surface without Pd-activation as a pretreatment step in conventional electroless deposition. Furthermore, an 8.6% increase in the sheet resistance(Rs) via Pd-activation process which is higher than that of the Co-based self-activated process indicates that Pd may diffuse into Cu line and induce Rs increase. Results from grazing incidence X-ray diffraction (GIXRD) analysis on as-deposited Co-based films reveal that it has a nano-crystalline structure. Such structure changes very little after annealing over 400 °C for 30 min. AES depth profiles also reveal a uniform distribution of the elemental components and extremely low B content. Additionally, Cu was not detected on Co cap film, indicating such films could serve as diffusion barrier layers to inhibit Cu diffusion.

ASRI2005‐90 Vaginal formulations – how innocuous are they to the vaginal epithelial immune function?

Problem: The disruption of the epithelial barrier and activation of inflammatory pathways may lead to increased susceptibility to viral infection. Over‐the‐counter (OTC) vaginal products have received little attention in this regard, however the recent development of anti‐HIV‐1 microbicides has brought the importance of mucosal integrity to forefront. While vaginal microbicides represent a promising strategy for preventing HIV‐1 and other sexually transmitted infections, they can be efficacious only if they cause no epithelial toxicity or inflammation.Method: We used a novel organotypic cervicovaginal model (VEC100, Mattek) to compare hygienic or spermicidal OTC to the anti‐HIV‐1 microbicide cellulose acetate 1,2‐benzenedicarboxylate (CAP).Results: CAP film and gel formulations appeared non‐toxic in MTT and LDH viability assays and did not induce release of pro‐inflammatory mediators e.g. IL‐1, IL‐6 and IL‐8 as compared to controls. In contrast, a commercially available vaginal cleansing film containing Nonoxynol‐9 showed proinflammatory potential commeasurable to that of TNFα.Conclusions: Our study demonstrates the usefulness of the VEC tissue model for immunoinflammatory characterization and safety assessment of vaginal products. It provides evidence that CAP in film and gel forms may be used as a safe anti‐HIV‐1 prevention agent or vehicle for other vaginal products. This study was supported by NICHD 1P01HD041761.

Deoxidization of Water Desorbed from APCVD TEOS ­ O 3 SiO2 Film with Thin Titanium Cap Film

The water absorption characteristics and desorption characteristics of atmospheric-pressure chemical vapor deposited (APCVD) tetraethylorthosilicate and ozone film have been studied in detail to apply film to LSI intermetal dielectric film. film absorbs a large amount of water from the air, and desorbs the water at 200°C or less. It has also been found that titanium thin film deposited on film suppresses water desorption from film completely. Titanium thin film deoxidizes water desorbed from film to hydrogen even at 200°C or less. The reliability of aluminum wiring with intermetal dielectric film has not been sufficient because of aluminum film bursting in the via-hole formed on film during high-temperature storage testing at 150°C or more. However, if titanium thin film is used as the lowest layer of the accumulating aluminum wiring structure on film, aluminum bursting in the via-hole is suppressed completely. We consider the aluminum bursting to be caused by water pressure during the high-temperature storage testing, and the suppression by the titanium thin film to be caused by titanium deoxidization of water to hydrogen. © 2004 The Electrochemical Society. All rights reserved.

Optimization of Dielectric Cap Adhesion to Ultra-Low-k Dielectrics

AbstractIn this work, the adhesion of CVD dielectric caps to ULK MSQ spin-on dielectric materials with k values of 2.2 and 2.0, and a ULK CVD material with a k value of 2.7 is presented. A substantial improvement in cap adhesion to both the k2.2 ULK MSQ and the k2.7 ULK CVD material is demonstrated. The improvement is obtained using a low-k CVD glue material between the ULK dielectric and the subsequent cap material and/or by optimizing the CVD cap film deposition. Four-point bend measurement of adhesion strength is used to quantify the improvement in interface adhesion. The improvement in CVD cap adhesion is demonstrated to be strongly dependent upon both the glue layer film and the cap deposition conditions. While optimization of the CVD cap materials results in adequate adhesion for the k2.2 ULK MSQ, these improvements are demonstrated not to extend to the k2.0 ULK MSQ film.

Water dispersible microbicidal cellulose acetate phthalate film.

BackgroundCellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as "Aquateric" and containing additional ingredients required for micronization, used for tablet coating from water dispersions, was shown to adsorb and inactivate the human immunodeficiency virus (HIV-1), herpesviruses (HSV) and other sexually transmitted disease (STD) pathogens. Earlier studies indicate that a gel formulation of micronized CAP has a potential as a topical microbicide for prevention of STDs including the acquired immunodeficiency syndrome (AIDS). The objective of endeavors described here was to develop a water dispersible CAP film amenable to inexpensive industrial mass production.MethodsCAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined.ResultsThe prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ≈50 to ≈65% ethanol (EtOH). The films are ≈100 µ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold.ConclusionsSoft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP.

Buckling instabilities of thin cap layers deposited onto low-k dielectric films

ABSTRACTCompressive stresses in thin capping films deposited onto low-k dielectric substrates are particularly prone to relaxation through buckling. This is due to insufficient cap/low-k film adhesion energy and to the compliance of low dielectric constant films. Low-k dielectric films, especially when porous, have low elastic modulus and demonstrate poor adhesion to other layers.When adhesion is poor the cap film can locally buckle as if unconstrained. The buckle front can propagate like a crack and lead to complete delamination of the cap layer. If the cap/low-k film adhesive energy is high, wrinkling instabilities can take place under specific conditions determined by the geometry and the mechanical properties of the stack. In this case the dielectric also deforms due to stress relaxation. A theoretical and experimental evaluation of the parameters influencing the occurrence of these instabilities is presented. This study was carried out to explore the application and reliability of low-k materials as dielectrics for advanced interconnects.

Testa Structure and Histochemistry Related to Water Uptake in Leucaena leucocephala Lam. (De Wit)

The testa structure and histochemistry of Leucaena leucocephala Lam. (De Wit) seed were investigated by bright-field and fluorescence light microscopy, and scanning electron microscopy. The testa consisted of several separate layers. Externally there was a non-cellular layer made up of two parts differing in histochemical characteristics: an "outer strip" rich in hydrophilic substances, and a "thicker part" showing the occurrence of phenolics, involved in water impermeability control. A second underlying thin layer was formed by the palisade cell caps, joined one to another. This layer, which we called the "cap film ", became metachromatic reddish-blue with Toluidine O pH 4·4 and reacted positively with Alcian blue pH 2·5, revealing the presence of polysaccharide hydrophilic material. The palisade cells consisted of two parts, having different structures and histochemical features. The furrowed upper part revealed the simultaneous presence of hydrophilic and hydrophobic substances in the furrows and in the ribs respectively. The corresponding periclinal section showed a central daisy-like pattern (made up of hydrophilic material) with a small chain of tiny spots (made up of hydrophobic material) all around it. The inner part of the palisade cells was also furrowed, but showed only hydrophobic substances of lipidic nature, detected by Auramine O and Phosphine 3R. The light line was found to be rich in callose as shown by the strong fluorescence induced by Aniline Blue. These findings add supporting evidence of the complex structure and composition of the Leucaena leucocephala testa.

Parasitic Channel Induced by Spin‐On‐Glass in a Double‐Level Metallization Complimentary Metal Oxide Semiconductor Process: Its Formation and Method of Suppression

We studied the degradation mechanism and the suppression method for parasitic channel formation by inorganic spin‐on‐glass (SOG) in complimentary metal oxide semiconductor (CMOS) devices with double‐level metallization using test structures and a high frequency C‐V technique. The positive charge induced near the interface in the field isolation region caused the parasitic channel. We propose a new mechanism that atomic hydrogen created by the SOG film diffuses to the interfacial region and generates the positive charge. There are two distinct mechanisms for the creation of the atomic hydrogen by the SOG films with different cap oxide. In cap which is nondoped silicon oxide deposited by PECVD, Si—OH bonds in the SOG film are broken during the cap deposition and create the atomic hydrogen. In nondoped silicate glass (NSG) cap which is nondoped silicate glass deposited by atmospheric pressure chemical vapor deposition (APCVD), water desorbed from the SOG film reacts with the aluminum electrode and creates the atomic hydrogen. Furthermore, film with higher dangling bond density exhibited a capability to reduce the density of the SOG‐related positive charge. Especially, the bottom film under the SOG film was more effective for reducing the positive charge density compared with the cap film on the SOG film. The improvement is attributed to trapping of SOG‐related atomic hydrogen by the dangling bond in the film. These experimental results are qualitatively explained well with the trapping model introducing the dangling bond as the trap center in the cap and bottom films.