Critical Feature Size Research Articles

Deterministic Fabrication of Liquid Metal Nanopatterns for Nanophotonics Applications

AbstractGallium‐based liquid metals (LMs) are widely used for stretchable and reconfigurable electronics thanks to their fluidic nature and excellent conductivity. These LMs possess attractive optical properties for photonics applications as well. However, due to the high surface tension of the LMs, it is challenging to form LM nanostructures with arbitrary shapes using conventional nanofabrication techniques. As a result, LM‐based nanophotonics has not been extensively explored. Here, a simple yet effective technique is demonstrated to deterministically fabricate LM nanopatterns with high yield over a large area. This technique demonstrates for the first time the capability to fabricate LM nanophotonic structures of various precisely defined shapes and sizes using two different LMs, that is, liquid gallium and liquid eutectic gallium–indium alloy. High‐density arrays of LM nanopatterns with critical feature sizes down to ≈100 nm and inter‐pattern spacings down to ≈100 nm are achieved, corresponding to the highest resolution of any LM fabrication technique developed to date. Additionally, the LM nanopatterns demonstrate excellent long‐term stability under ambient conditions. This work paves the way toward further development of a wide range of LM nanophotonics technologies and applications.

(Dielectric Science and Technology Division Poster Award, 1st Place) The Influence of Pad Micro-Features on Chemical Mechanical Polishing (CMP) Performance: Insights from Computational Fluid Dynamics (CFD)

With semiconductor chip dimensions shrinking below 7 nanometers, Chemical Mechanical Planarization (CMP) becomes more critical [1], [2]. To meet the increasing demand for precision and uniformity in the fabrication of wafers and chips, enhancements in CMP consumables and operating conditions are necessary. To address these requirements, novel pad designs have been developed, particularly those that do not require conditioning [3]. It is known that the CMP polishing rate depends on pressure, pad wafer relative velocity, and the distribution of pad asperities [4]. As conventional pads provide small and random contact areas, the external pressure applied by the head determines the material removal rate (MRR) [5] Advanced pads with micro-features provide more contact areas and help deliver consistent pressure and slurry distribution during Chemical Mechanical Polishing (CMP) [6], [7]. This study uses computational fluid dynamics (CFD) to simulate the flow between pad and wafer surfaces to determine how pad surface micro-features affect the CMP process. The abrasive residence time, total fluid pressure, and slurry flow velocity are evaluated for four distinct pad micro-feature geometries: square, square-circle, circle, and ellipse. Increasing the number of edges in the pad micro-feature patterns increases pressure drop, leading to more interaction between pad and slurry and enhancement of MRR. The findings of this study confirm the effectiveness of micro-featured pads in optimizing CMP processes and provide valuable insights into the influence of microfeature geometries on critical parameters for improving the semiconductor fabrication process.[1] J. Seo, Journal of Materials Research, 36, 235–257, Jan, 2021.[2] B. Suryadevara, Advances in Chemical Mechanical Planarization (CMP). Woodhead Publishing, 2021.[3] S. Lee and E. Hwang, “Smart pad fabrication for CMP,” LMA Res Rep, vol. 10, pp. 100–104, 2002.[4] G. Ahmadi and X. Xia, J Electrochem Soc, 148, G99, 2001.[5] X. Xia and G. Ahmadi, Particulate Science and Technology, 20, 187–196, 2002.[6] S. Lee, G. Kim, M. Mcgahay, H. Kim, and H. Cho, “Pad Designs-To navigate the fundamentals of CMP.”[7] M. Mcgahay, G. Kim, S. Lee, H. Cho, and H. Kim, “Critical Feature Size of Polishing Pad and Its Performance.”

High Q-factor Polymer Microring Resonators Realized by Versatile Damascene Soft Nanoimprinting Lithography.

High-quality-factor microring resonators are highly desirable in many applications. Fabricating a microring resonator typically requires delicate instruments to ensure a smooth side wall of waveguides and 100-nm critical feature size in the coupling region. In this work, we demonstrate a new method "damascene soft nanoimprinting lithography" that can create high-fidelity waveguide by simply backfill an imprinted cladding template with a high refractive index polymer core. This method can easily realize high Q-factor polymer microring resonators (e.g., ~5 x 105 around 770 nm wavelength) without the use of any expensive instruments and can be conducted in a normal lab environment. The high Q-factors can be attributed to the residual layer-free feature and controllable meniscus cross-section profile of the filled polymer core. Furthermore, the new method is compatible with different polymers, yields low fabrication defects, enables new functionalities, and allows flexible substrate. These benefits can broaden the applicability of the fabricated microring resonator.

Hierarchical crystalline–amorphous nanocomposites with high strength and large deformability enabled by elemental diffusion

Amorphous/nanocrystalline dual-phase structures have recently emerged as an effective way for overcoming the strength–ductility trade-off and breaking the limitation of the reverse Hall–Petch effect. Here, we proposed a new strategy to develop a hierarchical and interconnected amorphous–crystalline nanocomposite arising from the nanoscale elemental interdiffusion and oxygen adsorption behavior during thermal treatment processes. The nanocomposite consisted of a three-dimensional (3D) hierarchical network structure where the crystalline phase (Cr–Co–Ni–Al) was embedded into the Al–O-based amorphous phase network with critical feature sizes encompassing three orders of magnitude (from micrometer to nanometer scale). It can achieve ultrahigh compression yield strength of ∼3.6 GPa with large homogeneous deformation of over 50% strain. The massive interstitial atoms induced lattice distortion and hierarchical amorphous phase boundary contributed to the strength improvement. in situ Uniaxial compression inside a transmission electron microscope (TEM) revealed that the exceptional deformability of the nanocomposites resulted from the homogenous plastic flow of nano-sized amorphous phase and the plastic co-deformation behavior restricted by the nano-architected dual-phase interface. The proposed dual-phase synthesis approach can outperform conventional nanolaminates design strategies in terms of the mechanical properties achievable while providing a pathway to easily tune the microstructure of these nanolaminates.

Sub-1 nm: A Critical Feature Size in Materials Science

ConspectusSize is one of the most important issues in materials science. Sizes of conventional nanomaterials are usually one to one hundred nanometers and, according to size effect, nanomaterials usually exhibit different optical, electrical, magnetic, thermal, and catalytic properties compared with bulk materials. As the important transition from atomic scale to nanoscale, subnanometer scale is a critical feature size in materials science. With the size of nanomaterials decreasing to subnanometer scale, they further show some distinctive properties. First, subnanometer materials (SNMs) show ultrahigh specific surface area and nearly 100% surface atomic ratio, greatly enhancing their interaction with external fields. Second, the intermolecular interaction between SNMs can dominate their self-assembly process, similar to the self-assembly process of some biomacromolecules. Third, due to the dimensional similarity, one-dimensional (1D) SNMs exhibit polymer-analogue properties, endowing them easy processability. And thus, SNMs not only show excellent optical, catalytic, adhesive properties, etc. but also can be processed into functional fabrics, films, gels, and so on. In order to construct functional SNMs, a good/poor solvent system and cluster–nuclei coassembly strategy are developed, which are facile and widely applicable. Until now, various SNMs with different compositions, morphologies, and structures have been prepared successfully through these two methods, and temperature-scale and large-scale preparation are realized for some SNMs, laying a solid foundation for practical applications of SNMs. Based on the cluster–nuclei strategy, multiple effective components can be combined into the block copolymer-analogue structures, and the performance can be improved due to the synergistic effect. And through assembling polyoxometalate (POM) clusters into clusterphene structures, electron delocalization may be realized to greatly enhance the catalytic performance. This Account summarizes some work of our group on SNMs, including structures, polymer-analogue properties, assembly, processing, and catalytic performance. In the structure part, the intrinsic chirality, block copolymer-analogue structure, and metal cation-bridging-POM anion structure are mainly introduced. Then the polymer-analogue properties of 1D SNMs are briefly discussed, including the dispersion, gelation, and adhesion properties. Subsequently, the self-assembly, electrospinning, and wet-spinning of SNMs and surfactant-assisted assembly of POM clusters etc. are introduced. Finally, tailoring catalytic properties in subnanometer scale through synergetic effects and possible electronic delocalization is discussed, which is based on the cluster–nuclei coassembly strategy and surfactant-assisted assembly of POM clusters. The SNMs show great potential in catalysis, optics, adhesion, gelation, and so on, paving a new path for the applications of nanomaterials. This Account briefly introduces the current progress and future challenges in the field of SNMs and we hope this Account will be informative for researchers interested in SNMs and give new inspiration to them.

Ultralong waveguide grating antenna enabled by evanescent field modulation.

Waveguide grating antenna (WGA) is a key component for an on-chip optical phased array. In order to form a beam with a small divergence angle, WGAs of several millimeters in length are highly desired. However, in high-index-contrast platforms such as silicon-on-insulator (SOI), such long WGAs typically require weakly modulated gratings with critical feature sizes below 10 nm. In this paper, we experimentally demonstrate a new, to the best of our knowledge, strategy to implement long WGAs. Instead of directly modulating a waveguide, we propose periodically modulating the evanescent field with subwavelength blocks. With this arrangement, weak grating strength can be achieved while maintaining a minimum feature size as large as 100 nm. For proof-of-concept, we experimentally demonstrate a 1-mm-long, single-etched WGA on a conventional 220 nm SOI platform, which achieves a far-field divergence angle of 0.095° and a wavelength scanning sensitivity of 0.168°/nm.

Deep learning hotspots detection with generative adversarial network-based data augmentation

Lithography process hotspot is a traditional design and quality issue for the integrated circuit manufacturing due to the gap between exposure wavelength and critical feature size. To efficiently detect the hotspot regions and minimize the necessity of conducting expensive lithography simulation experiments, various pattern-based methods have been proposed in the past years. Recent solutions have been focused on implementing deep learning strategies because of the unique strength in imagery classification tasks by employing the artificial neural networks. However, solving the technical bottlenecks such as imbalanced learning, identifying rare hotspots and effective feature extraction remains challenging. For this research, we introduce a hotspot detection method based on a convolutional neural network classifier and enhanced it by the imagery feature extraction and a generative adversarial network data augmentation system. Experimental results show competitive performance compared with the existing works.

Photonic crystal L3 cavity laser fabricated using maskless digital photolithography

Abstract Projection photolithography using an extreme-ultraviolet light source is the core technology that has enabled patterning on the scale of a few nanometers that is required for modern electronic chips. However, this high-end system is neither affordable nor needed for photonics where critical feature sizes are of 100s of nanometers (or of submicron). Although electron-beam lithography can provide a means for photonic device fabrication, it suffers from extremely low throughput. Therefore, a lithographic technique for submicron pattern generation at high throughput and low cost is in high demand. This group recently showed that maskless digital photolithography (MDPL), a convenient and versatile photolithographic technique that requires no photomask, could potentially address this demand by demonstrating photonic crystal (PhC) patterns with submicron periodicity and associated PhC band-edge lasers. In this paper, we report the fabrication of a PhC L3 cavity laser, which contains irregular air holes in terms of their positions and sizes, using the MDPL technique. Successful generation of such an aperiodic and nontrivial submicron pattern requires thorough understanding and scrupulous manipulation on light diffraction. Our achievements should provide the concrete foundation upon which compact, versatile, convenient, speedy, and economical lithographic tools for arbitrary submicron pattern generation can be developed.

Cross-Wavelength Hierarchical Metamaterials Enabled for Trans-Scale Molecules Detection Simultaneously.

Metamaterials have attracted increasing attention in sensing applications. However, the critical feature sizes of meta‐atom span several orders of magnitude in length scale, almost all the metamaterials are designed to operate at limited bands. It is challenging for a single type of meta‐atom with ultra‐broadband adaptability. Inspired by the natural hierarchical architectures, herein, the authors introduce a new constructing scheme of cross‐wavelength hierarchical metamaterials with a single type of meta‐atom that can realize enhancement of terahertz (THz) resonance and surface‐enhanced Raman scattering (SERS) at the same time. By combining multiple subwavelength structures at different hierarchical levels into a single meta‐atom, the obtained metamaterial can operate in two frequencies and realize multiple functionalities. Armed with this hierarchical metamaterial, detecting analytes as small as sub‐nanoscale chemical molecules or as big as microscale biomolecules simultaneously can be realized in one single metamaterial for the first time. As a proof‐of‐concept example, a smart sensory packaging is developed, which allowed them to real‐time monitor the kinetic growth of pathogenic bacteria and their metabolites in food without opening the packaging. They believe that their work will provide a valuable example that satisfies the unmet need for multiscale functional meta‐devices.

Computational study of plasma dynamics and reactive chemistry in a low-pressure inductively coupled CF4/O2 plasma

Plasma etching continues to play a central role in microelectronics manufacturing. As the semiconductor industry continues to shrink critical feature sizes and improves device performance, etch challenges continue to increase due to the requirement of processing smaller features along with new device structures. With their high density and high-aspect ratio features, these structures are challenging to manufacture and have required innovation in multiple areas of wafer processing. Innovations in this technology are increasingly reliant on comprehensive physical and chemical models of plasma etch processes. In the present paper, we develop a new mechanism of plasma chemical reactions for a low-pressure CF4/O2 plasma. We validate this mechanism against available experimental data using the self-consistent axisymmetric fluid model of inductively coupled plasma discharge. We show that this mechanism is in reasonable agreement with the results of experiments both quantitively and qualitatively. Using this mechanism, we analyze the influence of oxygen fraction in the feed gas mixture on the kinetics of the ion species and the fluorine and oxygen atom yield.

Miniaturization of Hydrocyclones by High‐Resolution 3D Printing for Rapid Microparticle Separation

AbstractHydrocyclones are a simple and powerful particle separation technology, widely used in macroscale industrial processes, with enormous potential for miniaturization. Although recent efforts to shrink hydrocyclones to the centimeter scale have shown great promise for passive and high‐throughput microparticle separations, further miniaturization is constrained by limited understanding of the impact of device size scale and design on separation performance, and challenges in realizing the complex internal structures of hydrocyclones at small size scales using conventional microfabrication techniques. Here, fundamental scaling issues for hydrocyclones with sub‐millimeter critical dimensions are investigated, and the first microscale hydrocyclones with critical feature size as small as 250 µm are demonstrated by taking advantages of 3D printing using stereolithography coupled with digital light processing. The resulting devices are shown to provide high separation efficiency for particles as small as 3.7 µm while operating at high flow rates up to 40 mL min−1, with scaling analysis suggesting that sub‐micrometer particle separations can be achieved with further miniaturization, potentially making the technology suitable for the rapid isolation and concentration of both inorganic and biological nanoparticles.

Mix-and-match lithography and cryogenic etching for NIL template fabrication

Field Emission Scanning Probe Lithography (FE-SPL) is an enabling technology for prototyping of sub-10 nm high-performance electronic devices. However, due to the serial writing scheme this technology is rather slow. The purpose of this work is the demonstration of a mix-and-match process in combination with cryogenic etching in order to fabricate templates for Nanoimprint Lithography (NIL). We describe (i) the fabrication of a micron-sized electrode layout on a 1.5 mm × 1.5 mm area by means of fast Direct Laser Writing (DLW), (ii) the subsequent stitching of nano-sized features on the same resist layer using high-resolution FE-SPL and (iii) the pattern transfer into silicon. IC manufacturing requires both, large throughputs with critical feature size smaller than 5 nm. Therefore, the motivation of our project is to develop a lithographic process for nano-electronic devices with critical feature size smaller than 5 nm, while the rest of the device sizes are 100 nm or larger. Thus, a possible SET template was designed for future high-throughput NIL.

User-defined microstructures array fabricated by DMD based multistep lithography with dose modulation.

A flexible and efficient strategy, digital micromirror devices (DMD) based multistep lithography (DMSL), is proposed to fabricate arrays of user-defined microstructures. Through the combination of dose modulation, flexible pattern generation of DMD, and high-resolution step movement of piezoelectrical stage (PZS), this method enables prototyping a board range of 2D lattices with periodic/nonperiodic spatial distribution and arbitrary shapes and the critical feature size is down to 600 nm. We further explore the use of DMSL to fabricate microlens array by combining with the thermal reflowing process. The square shape and hexagonal shape microlens with customized distribution are realized and characterized. The results indicate that the proposed DMSL can be a significant role in the microfabrication techniques for manufacturing functional microstructures array.

In Situ Subcellular Detachment of Cells Using a Cell-Friendly Photoresist and Spatially Modulated Light.

Dynamic adhesion and detachment of subcellular regions occur during cell migration, thus a technique allowing precise control of subcellular detachment of cells will be useful for cell migration study. Previous methods for cell detachment were developed either for harvesting cells or cell sheets attached on surfaces with low resolution patterning capability, or for detaching subcellular regions located on predefined electrodes. In this paper, a method that allows in situ subcellular detachment of cells with ≈1.5 µm critical feature size while observing cells under a fluorescence microscope is introduced using a cell‐friendly photoresist and spatially modulated light. Using this method, a single cell, regions in cell sheets, and a single focal adhesion complex within a cell are successfully detached. Furthermore, different subcellular regions of migrating cells are detached and changes in cell polarity and migration direction are quantitatively analyzed. This method will be useful for many applications in cell detachment, in particular when subcellular resolution is required.

Review—Management of Copper Damascene Plating

An overview of process and quality control issues faced in controlling copper damascene plating is provided. The challenges for effective management of a copper damascene plating process have evolved due to early limitations and problems which were discovered, and then as more demands resulted from Chemical Mechanical Planarization issues, yield and reliability concerns, reduction in critical feature size and the shift to 300 mm wafers as well as the adoption of dielectric films with low dielectric constants. The demands have been addressed by adherence to quality control methodology, improvements in plater design and operation, advancements in plating electrolytes, and by new metrology tools and methodology. The key measurement areas outlined here are bath concentration measurement and control, film properties metrology, contamination issues, and defects. Particular attention is given to the use of electrochemical and optical methods with enhanced capabilities. This includes the use of chemometrics for electroanalytical bath concentration control and optical methods for film thickness, surface roughness, and film stress/wafer curvature measurements.

Mechanically Assisted Self-Healing of Ultrathin Gold Nanowires.

As the critical feature sizes of integrated circuits approaching sub-10 nm, ultrathin gold nanowires (diameter <10 nm) have emerged as one of the most promising candidates for next-generation interconnects in nanoelectronics. Also due to their ultrasmall dimensions, however, the structures and morphologies of ultrathin gold nanowires are more prone to be damaged during practical services, for example, Rayleigh instability can significantly alter their morphologies upon Joule heating, hindering their applications as interconnects. Here, it is shown that upon mechanical perturbations, predamaged, nonuniform ultrathin gold nanowires can quickly recover into uniform diameters and restore their smooth surfaces, via a simple mechanically assisted self-healing process. By examining the local self-healing process through in situ high-resolution transmission electron microscopy, the underlying mechanism is believed to be associated with surface atomic diffusion as evidenced by molecular dynamics simulations. In addition, mechanical manipulation can assist the atoms to overcome the diffusion barriers, as suggested by ab initio calculations, to activate more surface adatoms to diffuse and consequently speed up the self-healing process. This result can provide a facile method to repair ultrathin metallic nanowires directly in functional devices, and quickly restore their microstructures and morphologies by simple global mechanical perturbations.

Low-loss integrated electrical surface plasmon source with ultra-smooth metal film fabricated by polymethyl methacrylate ‘bond and peel’ method

External light sources are mostly employed to functionalize the plasmonic components, resulting in a bulky footprint. Electrically driven integrated plasmonic devices, combining ultra-compact critical feature sizes with extremely high transmission speeds and low power consumption, can link plasmonics with the present-day electronic world. In an effort to achieve this prospect, suppressing the losses in the plasmonic devices becomes a pressing issue. In this work, we developed a novel polymethyl methacrylate ‘bond and peel’ method to fabricate metal films with sub-nanometer smooth surfaces on semiconductor wafers. Based on this method, we further fabricated a compact plasmonic source containing a metal-insulator-metal (MIM) waveguide with an ultra-smooth metal surface on a GaAs-based light-emitting diode wafer. An increase in propagation length of the SPP mode by a factor of 2.95 was achieved as compared with the conventional device containing a relatively rough metal surface. Numerical calculations further confirmed that the propagation length is comparable to the theoretical prediction on the MIM waveguide with perfectly smooth metal surfaces. This method facilitates low-loss and high-integration of electrically driven plasmonic devices, thus provides an immediate opportunity for the practical application of on-chip integrated plasmonic circuits.

Robust valley polarization of helium ion modified atomically thin MoS2

Atomically thin semiconductors have dimensions that are commensurate with critical feature sizes of future optoelectronic devices defined using electron/ion beam lithography. Robustness of their emergent optical and valleytronic properties is essential for typical exposure doses used during fabrication. Here, we explore how focused helium ion bombardement affects the intrinsic vibrational, luminescence and valleytronic properties of atomically thin . By probing the disorder dependent vibrational response we deduce the interdefect distance by applying a phonon confinement model. We show that the increasing interdefect distance correlates with disorder-related luminscence arising 180 meV below the neutral exciton emission. We perform ab initio density functional theory of a variety of defect related morphologies, which yield first indications on the origin of the observed additional luminescence. Remarkably, no significant reduction of free exciton valley polarization is observed until the interdefect distance approaches a few nanometers, namely the size of the free exciton Bohr radius. Our findings pave the way for direct writing of sub-10 nm nanoscale valleytronic devices and circuits using focused helium ions.

Numerical Study of the Impact of Vibration Localization on the Motional Resistance of Weakly Coupled MEMS Resonators

This paper presents a numerical study of the impact of process-induced variations on the achievable motional resistance $R_{x}$ of 1-D, 2-D, cyclic, and cross-coupled architectures of weakly coupled electrostatically transduced microelectromechanical resonators operating in the 250-kHz range. We use modal analysis to find the $R_{x}$ of such coupled arrays and express it as a function of the eigenvectors of the specific mode of vibration. Monte Carlo numerical simulations, which accounted for up to 0.75% variation in critical resonator feature sizes, were initiated for different array sizes and coupling strengths for the four distinct coupling architectures. Improvements in the mean and standard deviation of the generated $R_{x}$ distributions are reported when the resonators are implemented in a cross-coupled scheme, as opposed to the traditional 1-D chain. The 2-D coupling scheme proves to be a practical and scalable alternative to weakly coupled 1-D chains to improve the immunity to process variations. It is shown that a 75% reduction in both the mean and standard deviation of the $R_{x}$ is achieved, as compared with the traditional 1-D chain for a normalized internal coupling $\kappa >10^{-2}$ . [2014-0217]

Wet Processing for Post-epi & Pre-furnace Cleans in Silicon Carbide Power MOSFET Fabrication

Silicon carbide (SiC) power devices provide improved switching efficiency and are well-suited for high temperature, and medium to high voltage applications. As such, they are expected to spur growth for applications >1000V over the next decade as they enable significant reduction in emissions [1]. The chemically inert nature of SiC presents unique opportunities and challenges with regard to cleaning and surface preparation for fabrication of power metal-oxide-semiconductor field-effect transistors (MOSFETs). SiC processing often leverages learning from ultra-large-scale integration (ULSI) Si, but exposing where that experience can be directly transferred or must be modified is part of the charter for the SiC fabrication community. Here we present results for cleans post-epi test, also known as initial wafer clean (IWC), and prefurnace clean based on concentrated chemistries developed for Si, and discuss cost tradeoffs as the technology ramps from pilot to volume production. Although the diffusion of metals in single-crystal SiC is much slower than that found in silicon (Si) for similar temperatures, SiC thermal processing generally occurs at much higher temperatures and therefore metal contamination must be minimized to maintain process control and reliability. Iron, nickel, and other metallics are understood to degrade intrinsic lifetime of gate oxides, so are monitored for SiC processing at levels comparable to appropriate Si technology nodes. W-anode TXRF is an effective diagnostic tool used in controlling these contaminants, so is employed by measuring Si and SiC monitor wafers run alongside device lots at appropriate process steps. TXRF was performed at EAG in a Technos TREX model instrument. Additionally, 1200V SiC MOSFETs are fabricated on epitaxially grown N- layers and typically characterized with mercury (Hg) probe capacitance-voltage (MCV), leaving trace levels of Hg on the SiC wafer surface. In addition to the typical metal concerns, Hg must be removed before wafers proceed into the fabrication process flow. For this study, 100mm SiC wafers were Hg probed in a Semilab MCV-530 tester, utilizing a multi-measurement pattern of 44 points. Trace levels of Hg were analyzed with mapping-mode Mo-anode TXRF before and after a variety of cleans to provide a basis for comparison. Concentrated ULSI Si cleans (SC1, SPM, DHF, etc) with appropriate station segregation were shown to be an effective surface preparation approach for both the prefurnace clean and IWC evaluations. Iron mapped with W-anode TXRF is often measured below 1e10 atoms/cm2, representing control of Fe at or below levels identified by ITRS for Si nodes ~180nm [2], quite acceptable for the relatively thick gate oxides (~50nm SiO2) and critical feature sizes required in power semiconductor fabrication. For the IWC study, mapped Hg levels measured with Mo-anode TXRF on SiC were shown to be reduced from a typical average value of 2.5e14 atoms/cm2, and typical maximum value of 2.4e15 atoms/cm2 immediately after post-epi test, to levels below the 300-second detection limit of 7e10 atoms/cm2. In the extended paper we will discuss prefurnace cleans in the context of control charting for pilot volume manufacturing, and compare a variety of cleans at IWC; including dilute mixtures, to evaluate improvements in cost effectiveness through reduction of chemical consumption and environmental impact. Research was sponsored by the NY Power Electronics Manufacturing Consortium. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of NY Power Electronics Manufacturing Consortium or the state of New York. [1] E. Vivrey, “Wide Band Gap Power Electronics: A Path Toward CO2 Emission Decrease”, Semicon West TechXPOT, July 10th, 2014. [2] International Technology Roadmap for Semiconductors, 2000 Update, Front End Process, http://www.itrs.net