In this study, we evaluated the impact of a new development method ESPERT™ on tight pitch contact holes patterns fabricated by extreme ultraviolet (EUV) and e-beam (EB) lithography. For EUV lithography, ESPERT™ demonstrated significant improvements in sensitivity along with reductions in roughness and defects. For EB lithography, the technology improved sensitivity while maintaining roughness levels. In addition, we attempted to provide a qualitative explanation of the characteristic behavior observed in LCDU by introducing a new parameter. This research demonstrates the practicality of ESPERT™ in tight pitch patterning, suggesting that ESPERT™ could play a crucial role in enhancing patterning quality.

To achieve miniaturization in high-volume manufacturing (HVM), reducing the roughness of the chemically amplified resist (CAR) is highly desired. In a previous paper, post-development treatment (PDT) under development could reduce the low-frequency roughness of the 28 nm pitch line and space (L/S) [1], but the mechanism was unclear. Therefore, to understand the effect of PDT on the CAR, we performed a basic evaluation using CAR films that were either unexposed or exposed to KrF flood exposure. The results of the CAR surface roughness by atomic force microscopy (AFM) revealed a similar trend to the roughness reduction observed for 28 nm pitch L/S. Furthermore, our investigation into the PDT’s impact on etch process resistance suggested an enhancement in etching resistance while maintaining a smooth surface of the CAR. This potential dual benefit of the PDT, which involves reducing roughness and improving, could significantly impact HVM.

Herein, we present high-resolution EUV patterning results achieved using Lam Research’s negative-tone metal-oxide-based photoresist. We enable an entirely dry resist process flow by employing both the deposition and the development in the vapor phase. This approach offers benefits over conventional spin coating and wet development methods. It eliminates the need for organic solvents used for both coating and development steps, as well as the line-collapse defects which stem from the capillary forces during desolvation of wet developers. Additionally, by employing a vapor phase developer that reacts, volatilizes, and sequentially removes one monomeric species at a time from the wafer, superior resolution and wider process windows can be attained. In this report, we describe the dry development chemistries which selectively react and remove unexposed regions of the material, as well as the key parameters which influence the etch rates and selectivity. Using our dry process we demonstrate line/space patterns resolved at 24nm pitch with patterning metrics targeted toward high NA EUV lithography.

Metal oxide resist (MOR) patterning is extensively utilized in EUV lithography for the next generation devices. Decrease in device sizes and subsequent shrinkage of critical dimensions (CD) had been unavoidable in advanced nodes, leading to inevitable increase of the aspect ratio and the collapse of desired patterns. Preventing pattern collapse has become critical challenge in EUV lithography with MOR, but it could not be fully addressed by the MOR by itself. The underlayer has been introduced to mitigate undesirable pattern collapse and to allow the resist to serve the role as a mask for pattern transfer. Various approaches to prevent pattern collapse via underlayers have been explored, such as matched surface energy at the resist-underlayer interface, enhanced adhesion to the resist and uniform distribution of the related components via crosslinking density control. In this paper, we have designed novel MOR underlayers incorporating appropriate functional groups into the resin to demonstrate improvement in pattern collapse margin upon the patterning with metal oxide resist.

As lithographic pattern sizes continue to decrease, functional sub-layers possessing fast etch rates and high etch selectivity are necessary towards maintaining good aspect ratios and promoting successful pattern transfer. As such, the research and development of methods for predicting a polymer’s etch rate has been crucial towards designing polymers for successful utilization in lithographic sub-layers. From these methods, the Ohnishi Parameter is commonly referenced to signify how prone a polymer is to certain etching conditions. However, although O.P. values can be a powerful predictive tool, discrepancies with actual etch rates have been found with the implementation of certain monomers. In an attempt to elucidate the factors that lead to these variabilities, bond dissociation energies were calculated for a series of polymers with known etch rates. In combination with previously cited research, our initial findings outline the advantages of adopting dissociation energies as an alternative to the Ohnishi Parameter.

Ligands play roles in determining the properties of metal-containing EUV resists. In this study, a new series of complexes of the type R₃Sb(O₂CR’)₂ have been developed, showcasing positive-tone imaging. Ten R₃Sb(O₂CR’)₂ complexes were synthesized with variations in the R and R’ groups. Studies focusing on development solution, polymerizable olefin content, and molecular weight of these complexes indicated that styrene carboxylate ligands and low molecular weight R groups demonstrated positive-tone performance with fast photospeeds.

We conducted a series of mechanistic studies involving the exposure of antimony carboxylate complexes (R₃Sb(O₂CR')₂) which exhibit positive-tone patterning upon to EUV light or e-beams. The volatile photoproducts were evaluated using in situ mass spectrometry, revealing carbon dioxide and fragments of the R ligands (isopropenyl, isopropyl). Additionally, fragments corresponding to the breaking of the metal-carbon bond and metal-oxygen bond were observed. These results provide evidence that polymerization occurs for photoresists containing terminal olefins, resulting in a nonvolatile R’-group after decarboxylation. Ultimately, we propose a network of plausible mechanistic steps that are consistent with the structure-function and mass-spectral outgassing experiments.

We examined the synthesis of polyhemiacetals by the addition reaction of vinyl ethers and carboxylic acids in the presence of certain catalysts in various reaction conditions, yielding corresponding polyhemiacetals. Their physical properties such as solubility, film-forming ability, and their thermal stability showed good performance for application as resist materials, and the thickness-loss property of their thin-films on the silicon wafer was also excellent. Furthermore, their resist sensitivity was investigated in the films state with EB and EUV exposure tools, showing good sensitivity of E₀ = 10μC/cm²(EB) and E₀ = 1.0mJ/cm²(EUV), which were consistent of the structure of the synthesized polyhemiacetals.

Polyaddition reaction of 4-tert-butylcalix[8]arene derivative (BCA[8]-VE) with pendant vinyl ether groups and 4,4-(propane-2,2-diyl)diphenol (PDP) was examined, to afford the grape-shaped polyacetal (Botryosin) poly(BCA[8]-VE-co-PDP). The synthesized poly(BCA[8]-VE-co-PDP) showed good physical properties such as high thermal stability, solubility, and film-forming ability to relevant to resist material. Furthermore, its resist sensitivity was examined using electron beam (EB) exposure tool and showed a good sensitivity of E₀ = 50 μC/cm². Then its sensitivity was also examined using extreme ultraviolet (EUV) light exposure tool and showed a good sensitivity of E₀ = 4.0 mJ/cm² with high contrast.

EUV lithography technology has started to be used for the fabrication of 7 nm logic devices, and has been used for mass production technology since 2020. As EUV lithography plays a more important role in semiconductor manufacturing, photoresists for EUV exposure also become more important. However, there are few places in Japan where we can use EUV exposure tool. To solve this problem, it is effective to evaluate photoresists by other wavelengths such as 248 nm to screen samples in the initial stage. In our former report, we have evaluated the correlation between KrF, EB and EUV exposure, and we showed that there are good correlations among them. In this report, we synthesized acrylic polymers by changing the ratio of protection group or molecular weight. Acrylic monomers using this report are commercially available, for example a protection group type and a lactone polarity type. Using these samples, the evaluations by KrF, ArF and EUV exposure were performed, respectively.

In order to understand the behavior of secondary electrons in the initial processes occurring in EUV irradiation, the binary encounter collision theory was used for the calculation of collision cross section of low-energy electrons, and Spencer Fano’s theory was used for the continuous electron slowing-down process. Using the ionization and excitation cross sections and the continuous slowing-down spectra, the ionization yield and the excited state yield for various electron energy were calculated in poly(hydroxystyrene) after EUV irradiation. The yields for 80 eV photoelectron are about 3 for ionization and 4 for excited states. The stopping power and mean free path of secondary electrons based on the cross section were also estimated for the discussion of electron range in the polymer.

The transport of slow electrons holds fundamental significance and finds applications across various fields. In extreme ultraviolet (EUV) lithography, electrons generated after EUV photon absorption can initiate chemical reactions, thereby inducing a solubility switch. Investigating electron transport within materials pertinent to EUV lithography is not only of fundamental interest but also aids in understanding and enhancing lithographic resolution. In this study, we employed an experimental approach to measure the effective electron attenuation length (EAL) for electrons within the 10–90 eV energy range across several relevant materials, including poly(4-hydroxystyrene) and chemically amplified resists. The obtained EAL values exhibited minimal dependence on electron energy and ranged between 0.6 and 2.7 nm, varying depending on the material under investigation.

The industry has seen non-conventional metal-based materials in both logic and memory areas, such as Spin-on Metal Oxide Resist (MOR), Underlayer for EUV lithography and Spin-on Metal Hard Masks (MHM). Despite the immense potential of these new materials, the industry has paid enormous attention to avoid due to the general concern about trace metal impurities. Purposely introducing these metal-containing materials will inevitably raise alert, especially for track processes involving spin-coat layers that are currently handling primarily high purity organic materials. To address this new application challenge, or more specifically to protect the wafer edges from metal contamination during track processes, the authors have developed wafer Edge Protection Layer (EPL) material. EPL allows the wafer edge protection when the metal-containing coating is applied and the clean stripping with a proprietary solvent, ACE to yield bevel and backside metal-free wafers that could be further processed as usual. This paper provides the design of EPL material and process, key properties vs. molecular weight, solvent, bake condition and performance of EPL & ACE package, with the aim to offer the industry a practical solution for safely introducing metal-containing spin-coat layers.

With the “first light” of high Numerical Aperture (NA) scanner announced by ASML earlier this year, it has become clear that the inevitable resist thickness shrinkage will pose great challenge to pattern transfer with current chemically amplified resist (CAR), on top of other technical challenges including resolution, line roughness and defects. Historically, through the litho stack optimization, and more critically, the underlayer (UL) optimization, the overall litho performance of a given resist system could be largely improved to meet manufacturing needs. In this paper, we propose the possibility of using spin-on metal-oxide hard mask (SOMHM) materials as EUV lithography UL for CAR. By first validating the excellent etch selectivity at P44 L/S between CAR and SOMHM UL, as well as that between UL and other hard mask layers such as SOC, SiN or SiOx, the following P32 full wafer investigation allowed us to examine the critical parameters such as LER and LWR. Studies of even smaller pitches of 28nm and 24nm showed more advantages of SOMHM UL due to the etch budget limit of CAR when thinner resist is required to address some litho pattern defects. The possibility of simplifying the standard tri-layer stack is also demonstrated by using SOMHM as the UL as well as direct hard mask for pattern transfer into 60nm SiN.

Recently, in addition to enhancing the performance of semiconductor integrated circuits by process node evolution, advanced packaging technology is also driving the progress of electronic devices. In advanced packaging technology, chiplets integration technology is being paid much attention based on the functional and economical requirements, whereas there are some challenges to be solved. Regarding reliability, thermal management should be in consideration because power density is being increased in electronic devices. As for manufacturing, assemble process become so complicated that the material to enable the simplified process is preferred. Furthermore, in order to achieve higher performance beyond the limitation of electric signal transmission, CPO (Co-Packaged Optics) is expected to be a promising technology. In this technology, formation of well-controlled interface between electrical and optical signal is quite important. In this paper, we would like to introduce our proposal of new functional materials for advanced package including thermal interface sheet with vertically oriented graphite fillers, chemical resistant dicing tape, high heat resistant temporary bonding film, and optical transparent adhesive.

Expectation for advanced packaging technology has been raised due to increase in demand for small and high performance electronic components. In particular, FO-PKG (Fan-Out Package) is recognized as one of the most important package structures to realize high-density integration effectively. Redistribution technology is essential in FO-PKG and photoimageable dielectric for redistribution layer has been focused as the key material to meet the requirements such as package reliability. Crack resistance of the photoimageable dielectric in TCT (Thermal Cycle Test) is one of the important criteria to determine the package reliability. However, fabrication and evaluation of the TEG (Test Element Group) for TCT take a long time because of their complicated procedure. Therefore, clarification of influential material properties on crack resistance is crucial to accelerate material development. In this study, we focused on the relationship between tensile properties and crack resistance. We found out the correlationship between the result of repeated-load tensile test and the crack resistance.

With the recent breakthrough in microfabrication technology, microdevices in analytical chemistry have made remarkable progress and are now being put to practical use as micro chemical analysis systems such as micro-total analysis systems (μTAS) and Lab on a Chip. In microfluidic channels, which are an elemental function of these systems, it is necessary to make the channel walls partially hydrophilic or hydrophobic for solution control, but it has been difficult to obtain a continuous and spatially stable contact angle surface. In this study, hydrogen-containing silicon carbide films were deposited on silicon under various conditions using a sputtering deposition system, a newly developed (Shinko Seiki) PIG (Penning Ionization Gauge) plasma CVD method, in order to control the contact angle. This equipment can be applied to hot cathode Penning Ionization Gauge ion source, which can easily obtain high-density plasma for plasma CVD to produce thin films. The surface structures of these films were analyzed by photoelectron spectroscopy using synchrotron radiation to control the composition of the hydrogen-containing silicon carbide oxide films. As a result, hydrophilicity of the surface was obtained with increasing oxygen flow rate in the deposition. This result is important in that it can be used for channel walls of microdevices to obtain stable contact angle surfaces and to control fluid flow.

Micro fluidic devices utilize size effects to achieve fast and high-yield reactions with simple structures. In this study, high-aspect-ratio micro capillary arrays were fabricated using synchrotron-radiation Deep X-ray Lithography (DXL). This structure has functions such as valves, reservoirs, mixers, and immune reaction fields to provide vertical fluid control. However, fluid behavior in a micro capillary is affected by the contact angle of the material surface, so it is necessary to control the contact angle of the surface. The stability of the contact angle is also important for fluid control. Therefore, SiCOxHy films, which are formed by Penning Ionization Gauge (PIG) plasma Chemical Vapor Deposition (CVD) method and whose contact angle can be controlled by changing the deposition conditions, were coated on the reaction field to measure the stability of the contact angle and detect the reaction. When SiCOxHy films were formed on 96-well microtiter plates and Enzyme-Linked Immunosorbent Assay (ELISA) was performed, changes in absorbance on the concentration of the substance to be measured were observed at a contact angle of 63.8 degrees. Thus, the prospect of applying SiCOxHy films to micro fluidic devices for immunosorbent assays has demonstrated to be promising.