Sputter Etching Process Research Articles

In Situ Pre-Metallization Cleaning of CoSi2 Contact-Hole Patterns with Optimized Etching Process

We examined how controlling variables in a pre-metallization Ar sputter-etching process for in situ contact-hole cleaning affects the contact-hole profile, etching rate, and substrate damage. By adjusting process parameters, we confirmed that increasing plasma power lowered the DC bias but enhanced the etching rate of SiO2, while increasing RF power raised both, with RF power having a more pronounced effect. Higher Ar flow rate reduced etching uniformity and slightly lowered the DC bias. There was no significant difference in the amount of etching between the oxide film types, but the nitride/oxide selectivity ratio was about 1:2. Physical damage during Ar sputter-etching was closely linked to DC bias. finally, Finally, etching of the Si and CoSi2 sublayers was performed on the device contact hole model. At this time, Si losses of up to about 31.7 Å/s occurred, and the etch speed was strongly affected by the DC bias. By optimizing the RF power and plasma power, we achieved a Si/CoSi2 etch selectivity ratio of about 1:2.

Improving Aluminum Ultraviolet Plasmonic Activity through a 1 nm ta-C Film.

Aluminum (Al) can actively support plasmonic response in the ultraviolet (UV) range compared to noble metals (e.g., Au, Ag) and thus has broad applications including UV sensing, displays, and photovoltaics. High-quality Al films with no oxidation are essential and critical in these applications. However, Al is very prone to fast oxidation in air, which critically depends on the fabrication process. Here, we report that by leveraging the in situ sputter etching and sputter deposition of a 1 nm tetrahedral amorphous carbon (ta-C) film on the Al nanostructures, Al plasmonic activity can be improved. The prior sputter etching process greatly reduces the oxidized layer of the Al films, and the subsequent sputter deposition of ta-C keeps Al oxidation-free. The ta-C film outperforms the naturally passivated Al2O3 layer on the Al film because the ta-C film has a denser structure, higher permittivity, and better biocompatibility. Therefore, it can effectively improve the plasmonic response of Al and be beneficial to molecule sensing, which is proved in our experiments and is also verified in simulations. Our results can enable the various applications based on plasmon resonance in the UV range.

Sputter-etching treatment of proton-exchange membranes: Completely dry thin-film approach to low-loading catalyst-coated membranes for water electrolysis

Simultaneous plasma etching of a proton-exchange membrane (PEM) and deposition of a cerium oxide layer during reactive magnetron sputtering leads to the formation of a pronounced fiber-like structure on its surface. The level of structural porosity can be adjusted by varying the working pressure during the process. A PEM treated this way can be subsequently coated with a thin layer of iridium, forming an anode-side catalyst-coated membrane (CCM) for applications in water electrolysis. Due to the significantly enlarged surface of the membrane, there is no necessity for any additional, potentially corroding, support nanoparticles to achieve efficient in-cell operation. Moreover, utilizing a rotatory frame-shaped substrate holder and a multitarget deposition apparatus, the sputter-etching process can be used in the preparation of a full anode/cathode thin-film CCM in a single vacuum entry. This structure yields remarkable performance characteristics in an electrolyzer cell, considering its low combined noble metal loading of just 220 μg cm−2. Using this completely dry process for CCM manufacturing may facilitate efficient large-scale future production.

Experimental Study of SiO2 Sputter Etching Process in 13.56 MHz rf-Biased Inductively Coupled Plasma

Inductively coupled plasma (ICP) has been widely used in semiconductor manufacturing, especially in nanoscale etching and deposition process. It is important to understand the relationship among the 13.56[Formula: see text]MHz rf-biased power and the etching process. In this study, the effect of dual rf power on the SiO2 sputter etching is investigated by measuring the ion energy distributions (IEDs), ion flux and sputter etching rate. The results show that the IEDs transforms from uni-modal towards bi-modal distribution when rf-biased power is applied to electrode. The influence of source power, bias power, discharge pressure and current ratio on the ion flux, IEDs are investigated in detail. The energy separations measured by RFEA are in good agreement with analytical model. The ion flux can be modulated by the 13.56[Formula: see text]MHz rf-biased power. Moreover, the coil current ratio expands the control window of the ion bombardment energy for the ICP etch equipment while. Finally, an ion-enhanced etching model is introduced to obtain the sputter etching rate and reveals the influence of discharge conditions on the etch rate.

Numerical Study on the Dependence of Surface Topography with Sputter Etching Process

Numerical Study on the Dependence of Surface Topography with Sputter Etching Process

The creation of microscopic surface structures by interfacial diffusion of Au and Ag on Ag(110): A XPS and STM study

Experiments on single crystal Au/Ag alloy surfaces may provide insight into the physical and chemical phenomena that determine the reactivity of complex alloy surfaces such as nanoporous gold or bimetallic nanoparticles. In this study, we report the highly unexpected observation that as soon as interfacial diffusion is feasible (400K) thin gold films drastically restructure Ag(110) surfaces on the micrometer scale and create regular islands in a pattern which resembles the result of a sputter-etching process; bulk diffusion plays apparently no role during this phenomenon. Scanning tunneling microscopy (STM) reveals that the deposition of monolayer quantities of gold on the surface creates elongated islands, typically with a length of 1000nm, a width of ~50nm, and a height of ~30 lattice planes. The islands are predominantly elongated along the [1–10] direction and have a mutual distance of about 50nm. Approximately, one monolayer of gold causes the relocation of ~11ML of material. The islands are thermally unstable as further heating between 450K and 600K reduces the island structure significantly. The ‘etching’ of gold into the Ag(110) bulk material and the associated island formation can be rationalized with a simple kinetic model involving the diffusion of surface atoms only, illustrated with Monte Carlo simulations. A kinetic interpretation is also supported by the fact that those structures diminish after further annealing to higher temperatures. The observed large-scale reorganization underlines that even seemingly simple and well-defined surfaces may evolve in complex ways and that massive restructuring of surfaces can occur at temperatures well below the onset of bulk diffusion.

Nanostructured graded-index antireflection layer formation on GaN for enhancing light extraction from light-emitting diodes

We describe the fabrication and characterization of a randomly etched gallium nitride (GaN) surface for enhancing light extraction from light-emitting diodes. Our technique uses silica spheres as nano-targets in a sputter-etch process and produces a fine-grained surface with features around 35 nm. The textured surface layer acts as a graded refractive index layer with antireflection properties. Measurements show that photoluminescence intensity from such treated surfaces on a GaN LED wafer increases 2.2 times over that from pristine surfaces. These findings are also supported by computer modelling studies described here.

The Effects of the Sputter-Etching Power on the Formation of Conical Protrusions on the Surface of SUS304 Stainless Steel

SUS304 stainless steel samples were sputter-etched by a radio frequency (RF) magnetron sputtering apparatus. Correlation between the formation of conical protrusions on the steel surface and sputter power was discussed. The results show that the conical protrusion precipitates both uniformly and densely on the surface with the power being 600W, the anode-to-substrate distance being 50mm, the argon gas flow ratio being 50sccm and the sputter-etching time being 6h. The roughness of the samples sputter-etched at various sputtering powers for 6h was analyzed. According to the results, sputter-etching brings about the development of surface roughness, which in turn may affect the sputter-etching process

Three-Dimensional Micro-Coil Oscillator Fabricated with Monolithic Process on LSI

Integration technique of three-dimensional micro coils on high-performance RF-LSI is one of the key technologies to realize future wireless telecommunication services and hypersensitive capacitance sensor systems. We design and fabricate monolithic three-dimensional micro coils on LSI substrate. The micro-coil has long legs, which will minimize electromagnetic coupling to the LSI substrate. We succeed in confirming the basic operation of the integrated oscillator circuit in GHz frequency range. It is conformed that process damages by plasma ashing, heating at 200 degrees Celsius, and sputter etching process are not observed in the oscillation performance.

A novel method for the fabrication of integrated passive devices on SI-GaAs substrate

A novel process is developed for fabricating cost-effective, high-yield, and high-quality integrated passive devices on SI-GaAs substrate. Various material and processing approaches to thin film resistors (TFRs), spiral inductors, and metal-insulator-metal (MIM) capacitors are evaluated in terms of cost, yield and device performance. For better precision in TFR resistance, we modify the bottom metal manufacturing process. For higher spiral inductor quality factor (Q-factor) and yield, a much thicker second metal and a sputter-etching process is presented. For higher MIM capacitor yield, some optimised mechanisms are used. To further decrease the cost and increase the yield, SU-8 photo resist is firstly presented as a novel material for forming the final passivation layer to replace the traditional SiNx. A wireless local area network balun, low-pass filter and digital cellular system power divider are demonstrated by using this novel manufacturing process; they show very good RF performances in spite of theirs small chip size and low cost, compared with those of the reported literature.

Inexpensive and fast wafer-scale fabrication of nanohole arrays in thin gold films forplasmonics

In this paper, a fast and inexpensive wafer-scale process for the fabricationof arrays of nanoscale holes in thin gold films for plasmonics is shown. Theprocess combines nanosphere lithography using spin-coated polystyrene beadswith a sputter-etching process. This allows the batch fabrication of several1000 µm2 large hole arrays in 200 nm thick gold films without the use of an adhesion layer for the goldfilm. The hole size and lattice period can be tuned independently with this method.This allows tuning of the optical properties of the hole arrays for the desiredapplication. An example application, refractive index sensing, is demonstrated.

Durability Improvement of Optical H<sub>2</sub> Gas Sensor Using Pd Thin Film on Sputter-Etched Glass Substrate

A glass substrate was sputter-etched by R. F. magnetron sputtering at the powers of 100 or 200 W for 60 min in Ar gas. Pd thin film as a sensing agent of hydrogen (H2) was deposited on the glass substrate. The durability of the sensor was evaluated during hydrogen absorption-desorption cycles. The Pd thin film on the glass substrate without sputter etching peeled off after dozens of the cycles. However, the Pd thin film on sputter-etched glass substrate didn’t peel off. The contact angle of water on the glass substrate with sputter etching was smaller than that without sputter etching, suggesting that the surface energy of the substrate was increased by employing the sputter etching process. The improvement of durability for the optical hydrogen sensor using sputter etched substrate was related to the increase of surface energy induced by the sputter etching.

Low-resistive metal/n+-InAsSb/n-GaSb contacts

We present low-resistive electrical contacts to n-type GaSb with Te doping of 5 × 1017 cm−3 using a Ti/Pt/Au (1/35/275 nm) metalization sequence and an intermediate InAsSb contact layer with n-doping of 1 × 1020 cm−3 (also Te). The high doping level is achieved during growth, so in-diffusion of dopants is not required. To reduce the impact of the native oxide layer we remove it in a sputter-etching process using Ar ions and afterwards deposit the metalization in the same chamber. No annealing is necessary to achieve ohmic IV-characteristics with a resistivity as low as 5.1 × 10−6 Ω cm2. It improves to 3.3 × 10−6 Ω cm2 after annealing at 350 °C for 90 s. The resistivity slightly increases for deeper etching of the native oxide, which is probably due to surface damage induced during the sputter-etching process.

Characterization of the NiFe sputter etch process in a rf plasma

The sputter etching of NiFe thin films by Ar ions in a rf plasma has been studied and characterized with the use of a Langmuir probe. The NiFe sputter etch rate was found to depend strongly on incident ion energy, with the highest NiFe etch rates occurring at high rf bias power, low pressure, and moderate rf source power. NiFe etch rates initially increased with increasing rf source power, then saturated at higher rf source powers. Pressure had the weakest effect on NiFe etch rates. Empirically determined sputter yields based on the NiFe etch rates and ion current densities were calculated, and these compared favorably to sputter yields determined using the sputtering model proposed by Sigmund [Phys. Rev. 184, 383 (1969)].

Opening of aligned carbon nanotube ends via room-temperature sputter etching process

Top ends of aligned carbon nanotubes were opened via room-temperature sputter etching of the nanotubes in the same chemical-vapor deposition (CVD) chamber that the nanotubes were grown. The mechanism of the sputter etching process involves incident positive ions in the plasma, such as hydrogen or argon, colliding with the nanotube material and preferentially eroding the nanotube walls around the catalyst metal particles. The cut-off nanotube segments are removed from the sample in the CVD chamber together with the catalyst particles. This process is entirely physical in nature with no wet chemical processing steps involved. The sputter etching process is found to be faster with larger ion size, higher applied voltage forming the plasma, and higher pressure of the sputtering gas.

Control of Carbon Capping for Regrowth of Aligned Carbon Nanotubes

The regrowth of carbon nanotubes (CNTs) in a second growth stage after a first growth stage has been completely stopped has been found to be strongly related to the carbon capping present on their catalyst particles. It is shown that the undesirable carbon capping can be prevented from forming or removed and the nanotube growth can be rejuvenated by either control of plasma processing conditions during chemical vapor deposition or by inserting a room-temperature sputter etching process. The ability to cause sequential growth stages to take place in different directions makes it possible for us to clearly compare the occurrence and extent of CNT regrowth. Such a CNT regrowth process and understanding of controlling parameters can enable the creation of new nanowire configurations that could potentially be used for applications such as sharply bending nanointerconnections, nanosprings, bent AFM nanoprobes, or nanobarcodes.

Study of the 300-mm CoSi 2 defects induced by Soft Sputter Etch process before cobalt deposition—characterization, design of experiment and 200/300 mm comparison

Cobalt salicide has been the reference salicide for sub −0.25 μm CMOS technology nodes to lower the sheet resistances on source, drain and poly areas. A critical step in the cobalt silicide formation is the Soft Sputter Etch (SSE) before Co deposition [A.H.M. Kamal, N.S. Argenti, C.S. Blair, IEEE Transaction on Semiconductor Manufacturing, vol. 15, No. 3, August 2002.]. It has to remove native oxide and impurities to ensure a clean surface, but it should also be soft enough to avoid leakages and resputtering. In this paper, the 300-mm SSE chamber behavior is analyzed on blanket and 90-nm technology node patterned wafers to explain the formation mechanism of defects observed in salicided areas. Defectivity has been observed along the spacers, especially in pinched active structures. A nitrogen analysis performed by μ-Auger spectroscopy showed that nitride from the spacers was re-sputtered on the active areas during the SSE process, subsequently blocking the salicidation. DOE on blanket wafers were run characterizing the 300-mm chamber behavior. No major differences were seen between 200- and 300-mm chambers on blanket wafers. Etch rate was found to be mainly dependent on the RF bias power, whereas both RF bias and RF coil powers influenced the DC bias voltage on the wafer during process. Furthermore, a DOE on 90-nm technology node patterned wafers was performed in order to reduce nitride resputtering and thereby improve defectivity and device performance. Results showed that optimizing the ratio between RF bias and RF coil and changing both RF values was a way to improve the salicidation process. Indeed, salicidation improvement can be achieved by rising the DC bias on the wafer.

A new type of tribological coating for machine elements based on carbon, molybdenum disulphide and titanium diboride

In this study, solid lubricant films containing molybdenum disulphide, carbon, and titanium diboride (MoS 2:C:TiB 2) were deposited onto steel substrates by a non-reactive d.c. magnetron sputtering process. Adhesion was examined as a function of sputter-etching parameters and design of the interface between TiB 2 intermediate layer and MoS 2:C:TiB 2 top layer. Optimum adhesion was achieved by a short sputter etching process at high r.f. power in combination with a smoothly graded interface. The tribological behaviour of the optimized coating was then examined at ambient air in dependence of relative humidity (RH). The friction coefficient turned out to be nearly independent of RH. The wear rate at low RH was about 5×10 −8 mm 3/Nm. However, wear rate increased significantly with RH.

Plasma deposition of hydrogenated diamond-like carbon films from CH4-Ar mixtures

Hydrogenated diamond-like carbon coatings have been deposited from CH 4 radiofrequency plasmas. The effect of the argon addition to the precursor CH 4 gas has been investigated. The argon dilution has been found to influence the plasma phase and the structural, optical and mechanical properties of the films. The plasma phase has been monitored and analyzed by optical emission spectroscopy . In particular, it is shown that the prevalence of H*, Ar + *, C 2 * and H 2 * , CH* emitting species are observed in Ar-rich and CH 4 -rich CH 4 -Ar plasmas, respectively. Furthermore, it is shown that simultaneous sputter-etching and growth processes occur and in Ar-rich CH 4 -Ar mixtures the sputter-etching process prevails on the growth process. A well-defined transition from sputter-etching to growth process is localized at 15% methane in the feeding mixture.

PECVD of hydrogenated diamond-like carbon films from CH 4–Ar mixtures: growth chemistry and material characteristics

Hydrogenated diamond-like carbon film growth from CH 4–Ar plasmas has been investigated under the effect of negative DC self-bias voltage. The deposition rate, the optical emission spectroscopy data and the material properties have been examined for understanding the growth mechanism. It is suggested that the sputter-etching process in competition with the growth process is responsible for the decrease of deposition rate at high bias voltage (i.e. high radio frequency power and low pressure). The clear and important roles of Ar ions and H atoms in sputter-etching process are well evidenced by the joined analysis of deposition rate, emitting species intensities and modified material properties.