High Volume Semiconductor Manufacturing Research Articles

Post Tungsten CMP Cleaning: Optimization for Cleaning Efficiency and Corrosion Reduction

Abstract Tungsten chemical-mechanical planarization (W CMP) is among the first applications of the CMP process implemented in high volume semiconductor manufacturing. Alkaline chemicals such as diluted NH4OH have been the predominant choice of post W CMP clean due to charge repulsion between W and dielectric/abrasive surface in high pH. However, W dissolution occurs spontaneously above pH ~4.0. Consequently, W corrosion can happen during post-CMP cleaning. From that perspective, acidic chemistry (e.g., pH< 4.0) seems a more benign choice to protect W, although at such low pH, isoelectric potential curves suggest coulombic attraction between W and oxide/silica surfaces, making it unfavorable for particle removal. The above pH dilemma for post-CMP cleaning and W protection can be managed by adding corrosion inhibitor to an alkaline chemical. Results from blanket and patterned wafers suggest reduction in surface defects and W dissolution can be accomplished simultaneously by an alkaline clean chemical with corrosion inhibitor (pH ~ 9.78), which shows high cleaning efficiency and reduced W loss than citric acid-based chemical (pH ~ 2.66), DIW, and diluted NH4OH. In addition, we show that DIW alone can induce severe W dissolution in features of fine geometry. Possible counter measures against such DIW-induced W corrosion are discussed.

Fabrication of nitrogen-hyperdoped silicon by high-pressure gas immersion excimer laser doping

In recent years, research on hyperdoped semiconductors has accelerated, displaying dopant concentrations far exceeding solubility limits to surpass the limitations of conventionally doped materials. Nitrogen defects in silicon have been extensively investigated for their unique characteristics compared to other pnictogen dopants. However, previous practical investigations have encountered challenges in achieving high nitrogen defect concentrations due to the low solubility and diffusivity of nitrogen in silicon, and the necessary non-equilibrium techniques, such as ion implantation, resulting in crystal damage and amorphisation. In this study, we present a single-step technique called high-pressure gas immersion excimer laser doping (HP-GIELD) to manufacture nitrogen-hyperdoped silicon. Our approach offers ultrafast processing, scalability, high control, and reproducibility. Employing HP-GIELD, we achieved nitrogen concentrations exceeding 6 at% (3.01 × 1021 at/cm3) in intrinsic silicon. Notably, nitrogen concentration remained above the liquid solubility limit to ~1 µm in depth. HP-GIELD’s high-pressure environment effectively suppressed physical surface damage and the generation of silicon dangling bonds, while the well-known effects of pulsed laser annealing (PLA) preserved crystallinity. Additionally, we conducted a theoretical analysis of light-matter interactions and thermal effects governing nitrogen diffusion during HP-GIELD, which provided insights into the doping mechanism. Leveraging excimer lasers, our method is well-suited for integration into high-volume semiconductor manufacturing, particularly front-end-of-line processes.

Metrology for 2D materials: a perspective review from the international roadmap for devices and systems.

The International Roadmap for Devices and Systems (IRDS) predicts the integration of 2D materials into high-volume manufacturing as channel materials within the next decade, primarily in ultra-scaled and low-power devices. While their widespread adoption in advanced chip manufacturing is evolving, the need for diverse characterization methods is clear. This is necessary to assess structural, electrical, compositional, and mechanical properties to control and optimize 2D materials in mass-produced devices. Although the lab-to-fab transition remains nascent and a universal metrology solution is yet to emerge, rapid community progress underscores the potential for significant advancements. This paper reviews current measurement capabilities, identifies gaps in essential metrology for CMOS-compatible 2D materials, and explores fundamental measurement science limitations when applying these techniques in high-volume semiconductor manufacturing.

Infrared nanospectroscopy characterization of metal oxide photoresists

Implementation of extreme ultraviolet (EUV) lithography in high-volume semiconductor manufacturing requires a reliable and scalable EUV resist platform. A mechanistic understanding of the pros and cons of different EUV resist materials is critically important. However, most material characterization methods with nanometer resolution use an x-ray photon or electron beam as the probe, which often cause damage to the photoresist film during measurement. Here, we illustrated the use of non-destructive infrared nanospectroscopy [or nano-Fourier-transform infrared spectroscopy (nano-FTIR)] to obtain spatially resolved composition information in patterned photoresist films. Clear evidence of exposure-induced chemical modification was observed at a spatial resolution down to 40 nm, well below the diffraction limit of infrared light. With improvements, such a nano-FTIR technique with nanoscale spatial resolution, chemical sensitivity, and minimal radiation damage can be a promising candidate for the fundamental study of material properties relevant to EUV lithography.

On-Wafer Temperature Monitoring Sensor for Condition Monitoring of Repaired Electrostatic Chuck

The temperature of electrostatic chuck (ESC), a wafer susceptor used in semiconductor etch equipment, must accurately control the temperature of wafers during the etching process to obtain uniform and consistent process results. Failure to control the precise temperature can lead to rejection from the high-volume semiconductor manufacturing site (one of the most high-cost equipment components which can be repaired for its extended use). In this research, we propose a wireless-type on-wafer temperature monitoring system (OTMS) for easier and faster temperature monitoring to help temperature measurements of the repaired ESC in atmospheric and vacuum conditions. The proposed method, which can effectively measure the temperature distribution of the ESC, should manage the operational condition of ESC. A successful demonstration of the 300 mm size OTMS for the repaired parts enhanced the quality assurance with a temperature deviation of ±3.83 °C over 65 points of measurement.

Model-based characterisation of complex periodic nanostructures by white-light Mueller-matrix Fourier scatterometry

Optical scatterometry is one of the most important metrology techniques for process monitoring in high-volume semiconductor manufacturing. By comparing measured signatures to modelled ones, scatterometry indirectly retrieves the dimensions of nanostructures and, hence, solves an inverse problem. However, the increasing design complexity of modern semiconductor devices makes modelling of the structures ever more difficult and requires a multitude of parameters. Such large parameter spaces typically cause ambiguities in the reconstruction process, thereby complicating the solution of the inherently ill-posed inverse problem further. An effective means of regularisation consists of systematically maximising the information content provided by the optical sensor. With this in mind, we combined the classical techniques of white-light interferometry, Mueller polarimetry, and Fourier scatterometry into one apparatus, allowing for the acquisition of fully angle- and wavelength-resolved Mueller matrices. The large amount of uncorrelated measurement data improve the robustness of the reconstruction in the case of complex multi-parameter problems by increasing the overall sensitivity and reducing cross-correlations. In this study, we discuss the sensor concept and introduce the measurement strategy, calibration routine, and numerical post-processing steps. We verify the practical feasibility of our method by reconstructing the profile parameters of a sub-wavelength silicon line grating. All necessary simulations are based on the rigorous coupled-wave analysis method. Additional measurements performed using a scanning electron microscope and an atomic force microscope confirm the accuracy of the reconstruction results, and hence, the real-world applicability of the proposed sensor concept.

最先端短波長光源（DUV, EUV）と半導体製造への応用

最先端短波長光源（DUV, EUV）と半導体製造への応用

The Status of Nanoimprint Lithography for High Volume Semiconductor Manufacturing

The Status of Nanoimprint Lithography for High Volume Semiconductor Manufacturing

High Power LPP-EUV Source with Long Collector Mirror Lifetime for Semiconductor High Volume Manufacturing

High Power LPP-EUV Source with Long Collector Mirror Lifetime for Semiconductor High Volume Manufacturing

Nanoimprint system for high volume semiconductor manufacturing

Nanoimprint system for high volume semiconductor manufacturing

EUV light generation using laser induced Sn plasma for semiconductor high volume manufacturing

EUV light generation using laser induced Sn plasma for semiconductor high volume manufacturing

Dielectric-MoS2 Interfaces Grown By Atomic Layer Deposition

Molybdenum disulfide (MoS2) has become a prototypical transition metal dichalcogenide (TMDC) atomic-layered material because of its unique materials properties. For example, bulk MoS2 exhibits an indirect band-gap of 1.3 eV, while a single monolayer has a direct band-gap of 1.8 eV. Recently, nanometer scale transistor devices have been made with MoS2 and graphene, yet much of this work relies on layered materials prepared using chemical vapor deposition (CVD) and mechanically exfoliation. Multiple reports have demonstrated the growth of MoS2 via CVD, but only a few studies have reported MoS2 growth using atomic layer deposition (ALD), which offers potential advantages for high volume semiconductor manufacturing. Here, we report the ALD of few-layer MoS2 films using MoF6 and various sulfur precursors on various ALD-grown dielectric surfaces and the ALD of metal oxides on the ALD MoS2 films at temperatures between 100-300 °C. In particular, we used in-situ quartz crystal microbalance measurements to investigate the nucleation of MoS2 ALD on oxide surfaces and vice versa. In general, self-limiting growth of MoS2 was observed on a wide range of dielectric surfaces including alumina, magnesia, and hafnia. The ALD MoS2 films were amorphous as-deposited, but crystallized into a layered atomic structure upon annealing at 800 °C. Using in-situ spectroscopy and electrical measurements, growth inhibition of MoS2 was seen depending on the growth substrate. These studies provide insight into the low-temperature ALD of MoS2 and provide guidance for the ALD of additional TMDC films.

Extreme ultraviolet resist materials for sub-7 nm patterning.

Continuous ongoing development of dense integrated circuits requires significant advancements in nanoscale patterning technology. As a key process in semiconductor high volume manufacturing (HVM), high resolution lithography is crucial in keeping with Moore's law. Currently, lithography technology for the sub-7 nm node and beyond has been actively investigated approaching atomic level patterning. EUV technology is now considered to be a potential alternative to HVM for replacing in some cases ArF immersion technology combined with multi-patterning. Development of innovative resist materials will be required to improve advanced fabrication strategies. In this article, advancements in novel resist materials are reviewed to identify design criteria for establishment of a next generation resist platform. Development strategies and the challenges in next generation resist materials are summarized and discussed.

Nanoimprint System for High Volume Semiconductor Manufacturing; Requirement for Resist Materials

Nanoimprint System for High Volume Semiconductor Manufacturing; Requirement for Resist Materials

Post Salicidation Clean: Removal of Unreacted Pt from High Pt Content NiPt Silicide

Silicides are used for providing stable ohmic contacts on gate, source and drain areas. After the silicide is formed, unreacted silicide is removed by using strongly oxidizing wet clean solutions. For 2x nm technologies, Ni Pt has been used as a salicide with progressively higher amounts of Pt used for each advanced node. Complete removal of unreacted Ni Pt was found to have become became intermittent when the Pt content in the silicide exceeded 10%. The residual unreacted Ni Pt stringers were found to be pure Pt. A wet clean process was developed to remove unreacted Pt in all cases and its manufacturability determined for a semiconductor high volume manufacturing production line.

Effect of Pre-heat and Inert Gas Species on Cryogenic Aerosol Cleaning Performance in Semiconductor Manufacturing

Cryogenic aerosol cleaning is a dry cleaning method used in the back end of line (BEOL) semiconductor manufacturing to remove defects from planar hydrophobic surfaces such as SiCOH and SiCxNyHz. Cryogenic aerosol cleaning is preferred over conventional wet cleaning methods as it is a non-contact cleaning method, which uses inert gases to generate sub-micrometer-sized solid aerosol particles that physically remove nanometer-sized contaminants on wafer surfaces. Particle removal mechanism involves detachment of the particles upon impact with aerosol, diffusion, and finally entrainment away from the wafer. In BEOL metal line patterning, particles on the dielectric isolation surfaces translate through the subsequent lithography and copper fill steps in to single or multiple metal line open defects that are yield killers. In this study, we show that the particle removal performance of the standard aerosol cleaning can be enhanced by pre-heating the wafer and use of a higher molecular weight inert gas, namely Ar, for aerosol generation. Both the addition of a Pre-heat step and the use of Ar as the aerosol source showed 47–52% reduction in single and multiple line opens detected through wafer electrical tests during high volume semiconductor manufacturing process.

Novel EUV Resist Development for Sub-14nm Half Pitch

Extreme ultraviolet (EUV) lithography has emerged as a promising candidate for the manufacturing of semiconductor devices at the sub-14nm half pitch lines and spaces (LS) pattern for 7 nm node and beyond. The success of EUV lithography for the high volume manufacturing of semiconductor devices depends on the availability of suitable resist with high resolution and sensitivity. It is well-known that the key challenge for EUV resist is the simultaneous requirement of ultrahigh resolution (R), low line edge roughness (L) and high sensitivity (S). In this paper, we investigated and developed new chemically amplified resist (CAR) materials to achieve sub-14 nm hp resolution. We found that both resolution and sensitivity were improved simultaneously by controlling acid diffusion length and efficien-cy of acid generation using novel PAG and sensitizer. EUV lithography evaluation results obtained for new CAR on Micro Exposure Tool (MET) and NXE3300 system are described and the fundamentals are discussed.

半導体微細化技術の現状と今後の展望

1．はじめに 半導体の微細化の道筋はITRSのロードマップ(1)によれば，2011年に22 nm NAND Flashメモリの量産がダブルパターニングで開始された (図1) 。また16 nmでは過去EUVが本命とされていたが，光源出力の問題から量産技術の選択からはずされ (2012年)，現在ではArF液浸リ

Detection of Defects in EUVL Mask using Coherent EUV Source

The detection and evaluation of printable defects in extreme ultraviolet lithography (EUV) masks are one of the most critical issues for high-volume manufacturing of next generation semiconductor. The coherent EUV scatterometry microscope is a strong candidate for high-precision inspection of defects. We have developed the high-order harmonics generation system to generate coherent EUV light using the commercial table-top laser system. The low beam divergence was measured to be 0.18mrad for 13.5nm (59th) high-order harmonics. The spatially coherent, 59th harmonics was improved the contrast ratio of diffraction images. Defect signals were observed from the 2-nm width line-defect in the 88-nm line-and-space (L/S) pattern and the 54-nm defect in the 360nm pitch pattern using coherent scatterometry microscope equipped with high-order harmonics generation system as a practical coherent EUV light source.

Evaluating economic effects of semiconductor manufacturing in water‐limited regions

High‐volume semiconductor manufacturing (HVSM), with its associated high demands for freshwater, is often located in regions with limited water resources. This nexus of water demand and scarcity has generated concerns among municipal governments, prompting several to consider water supply restrictions as they plan for economic growth and development. By assessing water use data and economic valuations of land use from Chandler, Ariz., this study compared the economic benefit of HVSM with three alternative water uses: office, retail, and general manufacturing. Normalizing the economic benefit to net water use (after reclamation) had a marked effect on the fiscal consequences of water uses. The effects generated by mostly nonconsumptive water uses (such as HVSM and general manufacturing) increased significantly relative to less water‐intensive, but more consumptive, water uses. Results showed that water‐intensive land uses need not be avoided in communities where water is scarce, provided the community has the facilities necessary to reclaim the wastewater.