Robert Kazinczi

ASML's NXE platform performance and volume introduction

All six NXE:3100, 0.25 NA EUV exposure systems are in use at customer sites enabling device development and cycles of learning for early production work in all lithographic segments; Logic, DRAM, MPU, and FLASH memory. NXE EUV lithography has demonstrated imaging and overlay performance both at ASML and end-users that supports sub- 27nm device work. Dedicated chuck overlay performance of <2nm has been shown on all six NXE:3100 systems. The key remaining challenge is productivity, which translates to a cost-effective introduction of EUVL in high-volume manufacturing (HVM). High volume manufacturing of the devices and processes in development is expected to be done with the third generation EUV scanners - the NXE:3300B. The NXE:3300B utilizes an NA of 0.33 and is positioned at a resolution of 22nm which can be extended to 18nm with off-axis illumination. The subsystem performance is improved to support these imaging resolutions and overall productivity enhancements are integrated into the NXE platform consistent with 125 wph. Since EUV reticles currently do not use a pellicle, special attention is given to reticle-addeddefects performance in terms of system design and machine build including maintenance procedures. In this paper we will summarize key lithographic performance of the NXE:3100 and the NXE:3300B, the NXE platform improvements made from learning on NXE:3100 and the Alpha Demo Tool, current status of EUV sources and development for the high-power sources needed for HVM. Finally, the possibilities for EUV roadmap extension will be reviewed.

Performance of FlexRay: a fully programmable illumination system for generation of freeform sources on high NA immersion systems

This paper describes the principle and performance of FlexRay, a fully programmable illuminator for high NA immersion systems. Sources can be generated on demand, by manipulating an array of mirrors instead of the traditional way of inserting optical elements and changing lens positions. On demand (freeform) source availability allows for reduction in R&D cycle time and shrink in k1. Unlimited tuning allows for better machine to machine matching. FlexRay has been integrated in a 1.35NA TWINSCAN exposure system. We will present data of FlexRay using measured traditional and freeform illumination sources. In addition system performance qualification data on stability, reproducibility and imaging will be shown. The benefit of FlexRay for SMO enabling shrink is demonstrated using an SRAM example.

Experimental result and simulation analysis for the use of pixelated illumination from source mask optimization for 22nm logic lithography process

We demonstrate experimentally for the first time the feasibility of applying SMO technology using pixelated illumination. Wafer images of SRAM contact holes were obtained to confirm the feasibility of using SMO for 22nm node lithography. There are still challenges in other areas of SMO integration such as mask build, mask inspection and repair, process modeling, full chip design issues and pixelated illumination, which is the emphasis in this paper. In this first attempt we successfully designed a manufacturable pixelated source and had it fabricated and installed in an exposure tool. The printing result is satisfactory, although there are still some deviations of the wafer image from simulation prediction. Further experiment and modeling of the impact of errors in source design and manufacturing will proceed in more detail. We believe that by tightening all kind of specification and optimizing all procedures will make pixelated illumination a viable technology for 22nm or beyond. Publishers Note: The author listing for this paper has been updated to include Carsten Russ. The PDF has been updated to reflect this change.

Performance of a programmable illuminator for generation of freeform sources on high NA immersion systems

This paper describes the principle and performance of a fully programmable illuminator for a high-NA immersion system. Sources can be generated on demand, by manipulating an array of mirrors instead of the traditional way of inserting optical elements and changing lens positions. All mirrors are always used to create the source such that no light is lost when switching from one source shape to another. Measured sources generated with this new type of illumination system will be shown and compared to the target sources generated by source mask optimization software or targets of traditional sources. Comparison between measured and target source will be done both in parameters of a pupil fit model and by simulated imaging impact. Also the first results in resist obtained on a XTIV 1950Hi 1.35 NA tool equipped with this illuminator are presented and compared to measurements on the same system when it was equipped with an Aerial XP illumination system.

Extending 1.35 NA immersion lithography down to1x nm production nodes

Mainstream high-end lithography is currently focusing on 32 nm node and 22 nm node where 1.35 NA immersion technology is well established for the most critical layers. Double-patterning and spacer-patterning techniques have been developed and are being widely used to print the most critical layers. Further down the lithography roadmap we see 1x nm nodes coming where EUV lithography will take over critical layers from immersion. In order to enable a smooth industry-wide transition towards EUV, 1.35 NA immersion technology will continue to play a critical role in manufacturing front end layers in the coming years. Using immersion technology beyond the 22 nm node, we expect an increase in the use of double and even quadruple patterning technology for the critical layers. This demands tighter control of especially overlay and focus performance on the 1.35 NA immersion tools. Also fully flexible illumination and wave front control will be needed to optimize the contrast for these low k1 applications. In this paper we present the state-of-the-art system performance of todays 1.35 NA ArF immersion tool production workhorse, the TWINSCAN NXT:1950i. Furthermore we show the required scanner improvements on imaging, overlay and cost of ownership to enable device shrink below the 20 nm node in 2013 using immersion technology.

LPP EUV source readiness for NXE 3300B

Laser produced plasma (LPP) light sources have been developed as the primary approach for EUV scanner imaging of circuit features in sub-20nm devices in high volume manufacturing (HVM). This paper provides a review of development progress and readiness status for the LPP extreme-ultra-violet (EUV) source. We present the latest performance results from second generation sources, including Prepulse operation for high power, collector protection for long lifetime and low cost of ownership, and dose stability for high yield. Increased EUV power is provided by a more powerful drive laser and the use of Prepulse operation for higher conversion efficiciency. Advanced automation and controls have been developed to provide the power and energy stability performance required during production fab operation. We will also discuss lifetesting of the collector in Prepulse mode and show the ability of the debris mitigation systems to keep the collector multi-layer coating free from damage and maintain high reflectivity.

Aerial imaging for source mask optimization: mask and illumination qualification

As the semiconductor industry moved to 4X technology nodes and below, low-k1 ArF lithography approached the theoretical limits of single patterning resolution, a regime typically plagued by marginally small process windows. In order to widen the process window bottleneck, projection lithography must fully and synergistically employ all available degrees of freedom. The holistic lithography source mask optimization (SMO) methodology aims to increase the overall litho performance and achieve a robust process window for the most challenging patterns by balancing between the mask and illumination source design influences. The typical complexity of both mask and illumination source that results from a generic SMO process exceeds the current norm in the lithographic industry. In particular, the SMO literature reports on masks that fully operate as diffractive optical elements, with features that have little resemblance to the final wafer-level pattern. Additionally, SMO illumination sources are characterized by parametric or pixelated shapes and a wide range of transmission values. As a consequence of the new mask and source designs, qualifying the mask for printing and non-printing defects and accurate assessment of critical dimensions becomes one of the main mask inspection challenges. The aerial imaging technologies of Applied Materials Aera2TM mask inspection tool provide enabling solutions by separating out only the defects that matter and accurately measures aerial imaging critical dimensions. This paper presents the latest numerical and experimental SMO mask qualifications research results performed at Applied Materials with a mask containing two-dimensional DRAM production structures.

Laser produced plasma light source development for HVM

This paper describes the development of a laser-produced-plasma (LPP) extreme-ultraviolet (EUV) source for advanced lithography applications in high volume manufacturing. EUV lithography is expected to succeed 193nm immersion double patterning technology for sub- 20nm critical layer patterning. In this paper we discuss the most recent results from high power testing on our development systems targeted at the 250W configuration, and describe the requirements and technical challenges related to successful implementation of these technologies. Subsystem performance will be shown including Conversion Efficiency (CE), dose control, collector protection and out-of-band (OOB) radiation measurements. This presentation reviews the experimental results obtained on systems with a focus on the topics most critical for a 250W HVM LPP source.

Aerial imaging qualification and metrology for source mask optimization

As the semiconductor industry moves to 3X technology nodes and below, holistic lithography source mask optimization (SMO) methodology targets an increase in the overall litho performance with improved process windows. The typical complexity of both mask and illumination source exceeds what the lithographic industry has been accustomed to, and presents a novel challenge to mask qualification and metrology. In this paper we demonstrate the latest in aerial imaging technologies of Applied Materials Aera2TM mask inspection tool. The aerial imaging capability opens the door to a wide variety of metrological measurements analysis at aerial level and provides enabling solutions for mask and scanner qualifications. In particular, we demonstrate core and periphery DRAM pattern process window assessment and MEEF measurements, performed on an advanced test mask.