Lam Research (United States)

Protein-hydroxylation catalysed by Fe(II) and 2-oxoglutarate (2OG) dependent oxygenases is an important regulatory mechanism in human biology. Such oxygenases typically coordinate their Fe(II) cofactor via a conserved triad of an aspartate- or glutamate- and two histidine-residues. By contrast, aspartate/asparagine β-hydroxylase (AspH), which catalyses asparagine/aspartate-residue oxidation in epidermal growth factor-like domains (EGFDs), has only two histidine-residues (H679, H725), with a water occupying the site normally occupied by an aspartate- or glutamate-residue. We describe mechanistic studies with catalytically active AspH crystals. Turnover studies with single crystals under cryogenic conditions give (3 R)-hydroxylated EGFDs with the product alcohol coordinating Fe(II) trans to H725. Time-resolved serial crystallography of microcrystals using an acoustic droplet ejection system, coupled to X-ray emission analyses, demonstrate turnover within 1.5 s, giving a product complex in which Fe(II) is regenerated. Solution and crystallographic studies with the O2 surrogate nitric oxide imply O2 binds to Fe(II) trans to H725. The additional Fe-chelating water is maintained throughout AspH catalysis and is not directly involved in substrate hydroxylation, because O2 is the sole oxygen source in alcohol products, as shown by 18O labelling studies. The results reveal how AspH accommodates both aspartate- and asparagine-substrates and will assist in efforts targeting AspH for cancer treatment.

Amorphous carbon exhibits distinctive properties that make it a superior choice over traditional silicon-based materials for hard masks in high-aspect-ratio etching processes. However, due to the challenging recipes used for plasma etching, it is not clear how to protect the ACL mask in harsh plasma conditions. In the present paper, we propose both gas-phase and surface reaction mechanisms which can be used to model the etching of the ACL mask by SO2/O2 low-pressure plasma. These mechanisms are used in a one-dimensional fluid plasma model to understand the influence of SO2 partial pressure on the amorphous carbon etching by low-pressure inductively coupled plasma. The results of these studies are compared with the experimental data from Ishikawa et al., Appl. Surf. Sci. 645, 158876 (2024). Our results reveal that increased SO2 partial pressure results in a decreased carbon etch rate. This reduction is attributed to two factors: sulfur atom-induced passivation of the carbon surface and a diminished atomic oxygen flux to the wafer, which suppresses carbon oxidation.

During reactive ion etching of SiNx in fluorine-based plasmas where HF is produced through a combination of gas-phase and surface reactions, ammonium fluorosilicate (AFS) has been reported to form on the SiNx surface. However, the underlying mechanism for AFS formation and its role in SiNx etching is still unclear, particularly during etching under energetic ion bombardment. In this work, using in situ attenuated total reflection Fourier-transform infrared spectroscopy, we show that during SiNx etching with a CH2F2/Ar plasma, when the substrate was at room temperature at a bias voltage of −240 V, an etch stop occurred with the simultaneous accumulation of graphitic hydrofluorocarbon and AFS on the SiNx surface. Under nominally similar conditions in a CH2F2/Ar plasma, but with the substrate at 70 or 120 °C, no etch stop was observed along with the absence of hydrofluorocarbon and AFS. By eliminating the formation of a graphitic hydrofluorocarbon layer in a SF6/H2 plasma, also at a bias voltage of −240 V, we reveal that AFS accumulation does not necessarily lead to an etch stop, and a steady-state thickness of AFS appears on surface as a result of a balance between AFS formation due to SiNx etching and AFS decomposition due to the impingement of energetic ions and H radicals. The effect of the substrate bias voltage on the etch behavior and surface composition was also studied in CH2F2/Ar and SF6/H2 plasmas. Our results show that the AFS is likely mixed with the underlying SiNx film under energetic ion bombardment instead of being present as a well-defined uniform layer. As a result, the presence of AFS does not necessarily lead to an etch stop. AFS formed on the SiNx surface decomposed when exposed to H radicals generated in H2 plasma under self-bias. Therefore, we conclude that the H radicals can play a dual role where they facilitate AFS formation by scavenging F radicals to form HF, but can also directly remove AFS formed on the surface. Finally, the slow removal of AFS by increasing the temperature to 70 °C suggests that AFS accumulation can be controlled with the substrate temperature.

Diabetic Retinopathy (DR) is a common complication of diabetes mellitus that damages the retina and leads to vision loss and potential blindness. Traditional screening using color fundus photographs is time-consuming and labor-intensive. Given the increased prevalence of diabetes, computer-aided diabetic retinopathy diagnosis has drawn scientific interest, as early diagnosis of the disease remains challenging. Deep and machine learning-based techniques have heavily contributed to enhancing medical image processing, enabling quick diagnosis and diabetic retinopathy categorization. Manual retinal vasculature segmentation is time-consuming and requires experienced supervision. This paper explores diabetic retinopathy segmentation and classification deficiencies, highlighting major issues and potential research directions. VGG-16 CNN model has been used in this paper to detect diabetic retinopathy. The accuracy of the model is 95.2%.

Key chip manufacturing technologies such as RIE, ALD, ALE, CVD, and PVD utilize low temperature plasmas. In this talk, we will review important trends on the evolution of plasma solutions for etching. Plasma sources continuously evolved to meet the ever more stringent requirements posed by Moore's Law. The 1990ies saw the emergence of high density, inductively or transformer coupled (ICP or TCP) plasmas which revolutionized etching of silicon and other conductive materials. They allowed independent tuning of ion flux and energy. Dual frequency capacitively coupled plasmas (CCP) stood their ground for etching of SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and other dielectrics. The following decade was characterized by the move from 200 to 300 mm tools and rapid improvement of ion flux uniformity across the wafer. TCP/IPC sources with more than one coil were introduced. Frequency mixing was found effective for spatial tuning of ion fluxes in CCP tools. As feature dimensions approached nanometers and aspect ratios 50 and more, within die performance became the driving force of RF and plasma technology. Plasma pulsing, direct drive technology, and non-sinusoidal RF are at the center of current development because these technologies allow for the ion energy and angular distribution control which is needed for 3D devices which are characterized by large aspect ratios. These innovative RF technologies must operate with RF powers of close to 100 kW total power. The resulting RF systems are among the most sophisticated in existence. In summary, low temperature plasmas are instrumental in the manufacturing of the integrated circuits which enable the breathtaking progress in computing and artificial intelligence (AI). At the same time, AI and machine learning play a critical role in advancing RF systems for IC manufacturing.

As the semiconductor industry adopts new and more complex advanced packaging schemes, the wafer edge becomes increasingly important in terms of maximizing yield. This paper will provide an overview of packaging applications for both plasma bevel etch and PECVD bevel deposition. Bevel etch has long been used in wafer processing to reduce edge defects but has become instrumental in maintaining wafer edge health for chip-to-wafer and wafer-to-wafer bonding schemes. Bevel deposition replaces multiple process steps with a single annular deposition of Si or C-based film and is being adopted for metal contamination mitigation and edge roll-off compensation prior to wafer-to-wafer bonding.

Ternary bulk (A,B)mO2m + 1 materials, where A = Zr or Hf, B = Nb or Ta, and m is the multiplicity, were recently shown to be entropy stabilized at elevated temperature due to an exceptionally high degree of structural disorder. We report the transformation of atomic layer deposited amorphous ZrO2–Ta2O5 thin films into ternary entropy stabilized Zr2Ta2O9 upon annealing at 800 °C in N2. Ag/Zr2Ta2O9/Si metal/oxide/semiconductor devices exhibited light-activated self-rectifying resistive switching with a set field of ∼+0.56 MV/cm, a threshold field of +0.17 MV/cm, a reset field of −0.59 MV/cm, and a current ratio of 7000:1 between the low and high resistance states under illumination. Devices with unannealed (amorphous) films did not exhibit switching in this field range.

p-GaN HEMTs are favored for bridge topology applications where they act as the freewheeling transistors to commute the current during the dead time. However, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_DS</i> , <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v_DS</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v_GS</i> oscillations at this period are observed and may introduce EMI problems. In this paper, we have demonstrated the presence of the negative resistance effect in p-GaN HEMTs by small signal analysis and revealed the origin of the abovementioned oscillations. The negative resistance comes from the unique reverse conduction mechanism of p-GaN HEMT and strengthen the oscillation of the driving current <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_G</i> . According to the derivation formula of the negative resistance, it can be reduced by paralleling a resistor between the drain and source of the freewheeling transistor. Thus, an anti-parallel lateral rectifier (LR) is monolithically integrated with the p-GaN HEMT to reduce the negative resistance. A synchronous buck converter was constructed to verify the effectiveness in a circuit-level application. The experiment results show that the negative resistance has a 11% reduction and the oscillation amplitude of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_DS</i> is reduced by 60% with 1% chip area of LR. Meanwhile, the high switching speed of the p-GaN HEMT is not affected.

In this work, we estimated the edge placement error (EPE) and demonstrated the feasibility of patterning an advanced 18-16 nm metal pitch (MP) BEOL using the SEMulator3D® virtual fabrication platform. The full 18 nm MP process flow patterned using a SALELE technique was simulated to evaluate three EPE challenges: LE1 on LE2, BL1 on LE1 and BL2 on LE2. We explored the impact of process variations and patterning sensitivities on EPE variability. The simulation identified significant process parameters and corresponding process windows that need to be controlled to ensure successful EPE control.

Dry deposited and dry developed photoresist continue to demonstrate low defectivity and roughness with 0.33NA imaging. This work showcases a test vehicle that was developed on 0.33 NA to characterize the dry resist performance at P26L/S single exposure and validate defectivity performance through large area electrical yield measurement. The effect of different process parameters such as underlayer, post exposure bake, dry development and mask bias, on post litho and post etch performance are evaluated using this test vehicle (e.g., we showed that by optimizing dry development chemistry we can improve roughness without impact to dose to size). The electrical yield in large area (1m long meander and fork-fork structures) is measured post a W-damascene based metallization, and is used to verify the yield benefit of the optimized resist chemistry. This vehicle offers the ability to co-optimize process parameters to demonstrate best roughness and defectivity. at improved sensitivity enabling us to push the limits of the RLS trade-off. By adopting this holistic approach, we demonstrate our readiness for high NA EUV patterning.