Evolving Nano Process Infrastructure Development Center (Japan)

Standard wafers with programmed defects (PDs) were fabricated to evaluate charge control techniques, resolution, and defect detection capabilities of pattern inspection tools for 7-nm and smaller nodes. To evaluate charge control techniques, the PDs were formed in line and space (LS) patterns. PDs were also formed below contact holes as programmed etching residues. These PDs were detected by a voltage contrast inspection technique. Image distortion by charging was also evaluated with the use of a wafer in a multibeam secondary electron microscope (SEM) and projection type inspection systems. Patterns with PDs were also formed on different subsurface structures. The effects of subsurface structures on the defect detection capability were evaluated based on this wafer. Another type of wafer having small defects approximately 5 nm in size on 16- to 12-nm half pitch (hp) LS patterns on a 12-inch Si-wafer, was fabricated by electron beam lithography. This wafer allowed evaluation of the defect detection capability of PDs having different shapes and sizes, such as protrusion, intrusion, bridge and open defects, on dense patterns for 7-nm and smaller nodes. Moreover, extremely small protrusion defects, with a size of 1 nm, and small bridge defects (as narrow as 1 nm) were also fabricated into LS patterns with ultra-low line-edge-roughness on a Si (110) substrate. This patterned substrate was mounted into a 12-inch Si wafer, and we evaluated the performance of tools for 12-inch wafer fabrication. We proposed a method to verify the true LER/LWR by CD-SEM measurements.

Multilayer defects (ML-defects) are the most specific type of defects on a mask for extreme ultraviolet (EUV) lithography. The intent of this paper has been to study the practical limits of the pattern shift technique to cover such defects by the absorber pattern. We have targeted to apply pattern shift to a 16nm half-pitch EUV single exposure, interconnect-like layer, in which absorber features are predominantly as small as 64nm at mask level. Three main contributors to successful defect coverage are the lateral size of the defect, the alignment of the mask pattern to the fiducial marks and the location accuracy of the blank defects relative to these fiducial marks. For our experimental analysis, we have used a specific approach in which, rather than explicitly targeting to cover the defects to render them non-printing, we kept the possibility to study their printability, together with the possibility to assess the achieved alignment of the mask pattern to the defectivity map of the blank. This was achieved by superimposing a dedicated marker frame, with the expected defect position at its center, onto a lines-and-spaces (l/s) pattern with 16nm half-pitch (at wafer scale). The marker frame allows to determine the deviation of the defect position from the expected one, and the printing impact of the defect on the l/s pattern can be compared to its expected behavior based on its relative position within the 32nm period. It is shown that mitigation feasibility is strongly dependent on the accuracy of the defect position information. Our results suggest targeting to improve that.

The role of photons in lithography is to transfer the energy and information required for resist pattern formation. In the information-deficit region, a trade-off relationship is observed between line edge roughness (LER) and sensitivity. However, the sensitivity can be increased without increasing LER in the energy-deficit region. In this study, the sensitivity enhancement limit was investigated, assuming line-and-space patterns with a half-pitch of 11 nm. LER was calculated by a Monte Carlo method. It was unrealistic to increase the sensitivity twofold while keeping the line width roughness (LWR) within 10% critical dimension (CD), whereas the twofold sensitivity enhancement with 20% CD LWR was feasible. The requirements are roughly that the sensitization distance should be less than 2 nm and that the total sensitizer concentration should be higher than 0.3 nm−3.

The thermalization of secondary electrons is an important process in the radiation effects on a condensed matter. In the lithography using ionizing radiations, it is expected that the effects of thermalization distance will become prominent in the sub-10 nm resolution region. In this study, the effects of thermalization distance on the stochastic phenomena in the fabrication of line-and-space patterns with 7 nm half-pitch were investigated on the basis of the sensitization mechanisms of chemically amplified extreme ultraviolet resists. All three factors related to the stochastic phenomena [the stochastic generation of pinching and bridges and line edge roughness (LER)] were improved by decreasing the thermalization distance. It was found that the suppression of LER and bridge generation was a more serious problem than that of pinching.

Line edge roughness (LER) rapidly increases in the sub-10-nm-half-pitch region of resist processes used for the fabrication of semiconductor devices. Sub-10-nm fabrication with high throughput is a challenging task. In this study, the stochastic effects (LER and stochastic defect generation) of chemically amplified resist processes in the sub-10-nm-half-pitch node were investigated, assuming the use of extreme ultraviolet (EUV) lithography. The latent images were calculated by a Monte Carlo method on the basis of the sensitization and reaction mechanisms of chemically amplified EUV resists. 7-nm-half-pitch fabrication by chemically amplified resist processes is considered to be feasible. However, significant improvement in the efficiencies of the conversion processes from optical images to resist images is required.

We examined effects of doping with hydrophilic materials on micro-phase separation of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA). As the hydrophilic materials, three organic acid compounds; butane -1,2,3,4- tetracarboxylic acid (BTA), cyclobutane -1,2,3,4- tetracarboxylic acid (CBTC), and sulfonyl-4,4'-diphenol (SNDP) were utilized in this experiment. By adding them to the PS-b-PMMA, it was found that they induced reducing phase-separation size. The doping of organic acid compounds into PS-b-PMMA decreased the phase separation size, while increasing doping PMMA homopolymer increased it. The PS-b-PMMA with low molecular weight PS 10.0 kg/mol -b- PMMA 10.0 kg/mol was utilized to examine the effect for phase-separation limit. By doping with 5 wt% of CBTC PS-b-PMMA showed lamellar structure with 8.2 nm half pitch. We considered that the doping organic acid compounds were a promising path for overcoming the phase-separation limit in PS-b-PMMA.

This peer-reviewed paper examines the risks and responsibilities of water providers and the process resource companies should undertake to document how they will deliver a safe and secure water supply to their employees and contractors, and the communities in which they operate, thereby reducing the risks of water quality incidents and managing the impact to the organisation should an incident occur. Water quality incidents can have major impacts to human health and the brand perception of the resource company supplying the water, and can potentially shutdown resource abstraction. Resource companies have a duty of care to provide a secure and safe drinking water supply. This is reinforced by state health departments directing resource organisations to comply with the Australian Drinking Water Guidelines (ADWG), which were updated in 2011 (National Health and Medical Research Council, 2011). Organisations in the CSG industry experience an additional challenge—managing water by-product from gas extraction. There are drivers for the beneficial use of this water—including irrigation, aquifer recharge and municipal supply—resulting in changes to legislation in Queensland (DERM, 2010) that require a process similar to ADWG recommendations, where beneficial use or disposal may impact potable supplies. The ADWG provides clear guidance to potable water providers—whether they are supplying a few consumers or major towns requiring a Drinking Water Quality Management System (DWQM System). This guidance includes documenting a clear process to securing a clean water source, making the water safe to consume and proving it is safe. Developing a DWQM System enables resource companies to understand issues in supplying drinking water through regular review and improvement, while minimising and managing the health risks to consumers.

With extreme ultraviolet (EUV) resists reaching resolution capabilities beyond the 20 nm half-pitch line and space patterns, a trend has emerged in applying ultrathin resists (film thickness less than 60 nm) to compensate for possible issues in resolution-limiting pattern collapse and line width roughness, among other aspects. Thus, a clear understanding of the pattern mechanisms of resists at these extreme conditions is necessary. This paper focuses on the pattern formation characteristics of various EUV resist platforms for ultrathin films during dissolution by using in situ high-speed atomic force microscopy in liquid. As a result, it was observed that, regardless of the resist platform, there is a decrease in the size of the “dissolution clusters” at ultrathin conditions. Such fundamental information on ultrathin resist films may provide possible pointers to further extend the potential of EUV resists for achieving higher resolution limits and minimal line width roughness.