Nano-C (United States)

Irresistible Materials (IM) is improving its Multi-Trigger Resist – a negative tone, high opacity molecular resist specifically designed for high speed EUV, and high-NA EUV lithography, capable of patterning well with thin films. Pitch 28nm dense patterns can be patterned at a dose of 32mJ/cm2, a line width of 12.0nm, and a biased LWR of 3.9nm. This resist formulation has also been used to pattern pillars at pitches of 34nm hexagonal with a dose of 42mJ/cm2 to achieve 17nm diameter pillars. P32 pillars have also been patterned with a dose of 76 mJ/cm2 and biased LCDU of 3.4nm.

Irresistible Materials (IM) is developing novel resist systems based on the multi-trigger concept, which incorporates a dose dependent quenching-like behaviour. In this study, we present the results that have been obtained using Multi Trigger Resists (MTR) by performing EUV exposures on the ASML NXE EUV scanner at IMEC. The MTR is a negative tone high opacity crosslinking resist incorporating. Pitch 28nm dense patterns can be patterned at a dose of 59mJ/cm2, a line width of 12.5nm, and a biased LWR of 3.91nm. These resist formulations have also been used to pattern 20nm diameter pillars on a hexagonal 40nm pitch with a dose of 51mJ/cm2, and a CDU of 3.5nm; and also pillars at pitches of 34nm hexagonal with a dose of 80mJ/cm2 to achieve 17.5nm diameter pillars. High photospeed approaches, which have patterned p28 lines and p34 hex pillars at sub-30 mJ/cm2 doses are also introduced.

Single exposure EUV patterning for lower pitches (below 32 nm L/S) proves to be challenging and dependent on a series of factors including exposure tool related parameters such as illumination conditions but also material related parameters such as sensitivity to EUV photons and resist chemistry. While the industry is focused on developing a set of universal exposure conditions that can be applied to all resist systems, material suppliers must constantly enhance the exposure mechanism of the resists in order to support further advance in technology. The multi-trigger concept involves a reaction that will only occur when multiple elements of the resist are initiated concurrently and in close spatial proximity in order to enable the catalytic reactions. In high dose areas the resist behaves like a traditional CAR, whilst in low dose areas, such as line edges, the reaction is second-order increasing the chemical gradient. Effectively there is a dose dependent quenching-like behaviour built into the resist, enhancing chemical contrast and thus resolution, whilst eliminating the materials stochastics impact of a separate quencher reducing roughness. The multi-trigger resist (MTR) presented consists of a novel multi-trigger control molecule and a crosslinker, which represent the resist matrix, together with a photoacid generator (PAG). Here we present results from work focused on the enhancement of the high-opacity MTR resist. The absorptivity of the resist can be increased by replacing the standard crosslinker with a high-opacity crosslinker. The absorptivity of the crosslinking molecule can itself be changed by varying both the number of attached photo-absorption groups and by varying the specific choice of the high opacity group. Other modifications to the crosslinking molecule, which are presented, include reducing the steric hindrance of the molecule by changing the structure. The high-opacity crosslinker molecules have been synthesized and then formulated into the MTR resist. We report results obtained using the new MTR system containing this high-opacity cross-linker with a variation of process conditions, and with formulation variations. The lithographic performance of a formulation containing this crosslinker, at pitch 32nm patterned on an NXE3400 is presented. The sensitivity of the resist can be increased by 25% by varying the length of the crosslinker arm whilst keeping other factors such as the number of high opacity groups constant. Furthermore, we have also investigated increasing the activation energy of the self-quenching aspect of the MTR system. In the case presented, MTR8 has a higher activation energy than MTR2 and MTR4. Having a higher activation energy is predicted to allow the introduction of a post exposed bake (PEB) to increase crosslinking and reduce pattern collapse, whilst simultaneously preserving the self-quenching behaviour. We will present results which show using a higher activation energy molecule (MTR8) results in a minimisation of Z-factor and LWR, when increasing the PEB temperature by 10 degrees compared to MTR4. Pitch 32nm dense line spaces can be patterned at a dose of 49.5mJ/cm², a line width of 15.5nm and an biased LWR of 3.69nm. Pitch 28nm dense patterns can be patterned at a dose of 59mJ/cm², a line width of 12.5nm, and a biased LWR of 3.91nm. These resist formulations have also been used to pattern 25nm diameter pillars on a 40nm pitch with a dose of 50mJ/cm², and a CDU of 2.98nm. High photospeed approaches, which have patterned p24 and p28 lines and p34 hex pillars at sub-30 mJ/cm² doses are also introduced

One approach for a novel EUV resist is the multi-trigger concept wherein a reaction will only occur when multiple elements of the resist are initiated concurrently and in close spatial proximity. We present results focused on the enhancement of the high-opacity MTR resist which shows a decrease in dose and improvement in Z-factor using a higher activation energy MTR molecule for pitch 32nm dense lines. We present pillars at p40 with a diameter of 24nm, dose of 72mJ/cm2, with a CDU of 2.63nm.

The development of an EUV photoresist to support high volume manufacturing remains a challenging issue. Meeting the combined resolution, sensitivity, and line width roughness (RLS) requirements has proved difficult. Furthermore, defectivity issues arising from stochastic effects are becoming increasingly critical as pitches decrease. Whilst traditional chemically amplified resists will likely be used initially, a wide range of materials options are being examined for future nodes, aiming to identify a photoresist that simultaneously meets RLS and defectivity requirements. Irresistible Materials (IM) is developing novel resist systems based on the multi-trigger concept. In a multi-trigger resist, multiple elements of the resist must be simultaneously activated to enable the catalytic reactions to proceed. In high dose areas the resist therefore behaves like a traditional CAR, whilst in low dose areas, such as line edges, the reaction is second order increasing the chemical gradient. Effectively there is a dose dependent quenching-like behaviour built in to the resist, enhancing chemical contrast and thus resolution and reducing roughness, whilst eliminating the materials stochastics impact of a separate quencher. The multi-trigger material consists of a base molecule and a crosslinker, which represent the resist matrix, together with a photoacid generator (PAG). Research has been undertaken to improve this resist, in particular focusing on improving resist opacity and crosslinking density. A non-metal atom has been incorporated into the crosslinker and the results presented here show three iterations of this high opacity crosslinker. To improve the sensitivity, a mark II high-Z crosslinker was synthesised which incorporated longer arms compared to the mark I version, to reduce steric hindrance by increasing the distance of the high opacity atom from the reaction site. The results show a dramatic 65% dose-to-size reduction when using the mark II crosslinker. Further exposures investigated the effect of PEB temperature on both the mark I and mark II crosslinkers. This showed that the dose can be reduced by over 50% when using a 90 °C PEB compared to when using no PEB for the mark I crosslinker but by only 20% for the mark II crosslinker, as would be expected if steric hinderance has been reduced. We present results with the mark II crosslinker showing 16 nm half pitch lines using a 28 nm film thickness with a 90 °C PEB which results in a dose to size of 19 mJ/cm² and an LWR of 5.2 nm. A Mark III version is also presented where the chemistry of the Mark I crosslinker has been modified to improve the solubility in industry preferred solvents. We also present work aimed at improving the LWR of the high opacity resist formulation at high resolution, particularly aimed below 16 nm hp using dense lines when patterned using EUV lithography at the Paul Scherrer Institute, Switzerland. We present 13.3 nm lines on a 14 nm half pitch, with an LWR of 2.97 nm and dose of 26 mJ/cm² and 14.7 nm lines on a 15 nm half pitch, with an LWR of 2.72 nm and dose of 34 mJ/cm²

Power conversion efficiency (PCE) and long-term stability are the two key parameters of photovoltaic devices to meet standards for commercial use. In this Letter, an ordered alloyed co-acceptor by incorporating PC61BM and COi8DFIC is obtained. This ordered alloy structure increases the light absorption by producing a shoulder peak at 935 nm and improves electron mobility from 1.51 × 10–5 to 8.91 × 10–4 cm2 V–1 s–1 by PC61BM interacting with the end group of COi8DFIC and connecting adjacent COi8DFIC molecules. Consequently, the PCE is enhanced from 10.80 to 14.22%, enhancement of about 32%. Even further, the device stability is improved due to the fact that the alloy fixes the morphology of the active layer. After keeping for 7200 h, about 10 months, the PCE of those solar cells is retained at 13.2%, corresponding to a PCE loss of only 5.7%, while the PCE loss in the binary control device is up to 33.3%.

We have investigated microwave power detection based from carbon nanotube (CNT) thin films and chemical vapor deposition (CVD) grown graphene. Our experiments indicate that power detection from the CNT devices is primarily due to bolometric mechanisms. While, power detection from the graphene devices is primarily due to signal rectification. Both enabling materials are relatively inexpensive and easily blanketed on a variety of substrates{enabling low-cost/disposable, surface-conformal power sensors for wideband spectrum sensing applications. However, it is significantly less challenging to pattern and integrate CNT thin films than it is to do the same with graphene. CNT thin film and graphene power detectors were realized by fabricating metallic Corbino disc test structures over these enabling materials. Such test structures are convenient for on-wafer characterization with ground-signal probes. The CNT devices were also evaluated with transient current-versus- voltage traces and microwave reflection spectroscopy to respectively measure thermal time constants and values of complex conductivity. The bolometer performance of these devices was gauged in terms of power detection sensitivity, noise equivalent power, and dynamic range. The measurements were performed with 915 MHz test signals and yielded sensitivities as high as 0.36 mV/mW at room temperature and 2.3 mV/mW when cooled with liquid nitrogen. Similarly, graphene Corbino disc test structures were characterized with 433.92 MHz test signals and yielded power detection sensitivities of 3.25 mV/mW (at room temperature) and 5.43 mV/mW (at 80 K). These devices feature gate control over the channel conductance, which contributed a frequency-limiting parasitic capacitance. Our investigations revealed that rectification, due to characteristic nonlinear current versus voltage behavior, was more prevalent in the graphene than bolometric detection, due to Joule heating.

Indene‐C60‐bisadduct (ICBA) can represent an excellent choice as an acceptor of organic solar cells due to the, at most, similar cost, higher efficiency, and higher open‐circuit voltage (VOC) obtained in small‐scale devices compared to phenyl[60]butyrate methyl ester ([60]PCBM). We have investigated ICBA in printed solar cells and assessed the upscale of the printing process to a roll‐to‐roll (R2R) pilot production. Performances of poly(3‐hexylthiophene):ICBA solar cells are confirmed to be superior compared to [60]PCBM. Using large scale 2D R2R printing techniques, with both active material systems excellent processability, reproducibility, and yield are reached. At first, ICBA based large area modules (57 cm2) showed significant loss in efficiency. However, stressing the devices by exposure to sunlight was found to lead high efficiency modules with a VOC of 0.78 V per cell and a PCE of 3.4%. This is among the highest VOC per cell values realized with fully R2R processed organic photovoltaic modules and among the highest PCEs with P3HT based R2R processed modules. Imaging techniques have allowed to identify that stressing with sunlight partially burns shunts and recovers S‐shaped behavior in the ICBA‐based modules.

Based on the atomic electronic configuration and Ti-Se coordination, a valence bond model for the layered transition metal dichalcogenide (TMDC) 1T-TiSe2 is proposed. 1T-TiSe2 is viewed as being composed of edge-sharing TiSe4-plaquettes as TiSe2-ribbon chains in each layer via a directional valence shell electron distribution as chemical bonds, in contrast to the conventional layer view of face-sharing TiSe6-octahedra. The four valence electrons per Ti in the hybridized dsp2-orbitals of square coordination form σ-bonds with the four nearest neighbor Se atoms in the chain. The electrons in the lone pair of the Se-4pz orbital are proposed to form a dp type π-bond via side-to-side orbital overlap with the empty Ti-3dxz/3dyz orbitals within each chain, which is positively supported by quantum chemistry calculations. A study of electron energy loss spectroscopy (EELS) with transmission electron microscopy (TEM) for 1T-TiSe2 is presented to show an energy loss near ∼7 and ∼20 eV, which confirms the existence of collective plasmon oscillations with the predicted effective electron numbers for the π- and (π + σ)-bond electrons, respectively.