Peter Zink

Sn DPP source-collector modules: status of alpha resources, beta developments, and the scalability to HVM

For industrial EUV (extreme ultra-violet) lithography applications high power extreme ultraviolet (EUV) light sources are needed at a central wavelength of 13.5 nm, targeting 32 nm node and below. Philips Extreme UV GmbH and XTREME technologies GmbH have developed DPP (Discharge Produced Plasma) Alpha tools which run in operation at several locations in the world. In this paper the status of the Alpha Sn-DPP tools as developed by Philips Extreme UV GmbH will be given. The Alpha DPP tools provide a good basis for the development and engineering of the Beta tools and in the future of the HVM tools. The first Beta source has been designed and first light has been produced. Engineering steps will folow to optimize this first generation Beta Sn-DPP source. HVM tools target EUV power levels from 200W to 500W in IF. In this paper we show that the power requried for HVM can be generated with Sn-DPP sources. Based on Alpha Sn-DPP sources we show that repetition frequency and generated EUV pulse energy is scalable up to power levels that match the HVM requirements.

EUV sources for the alpha-tools

In this paper, we report on the recent progress of the Philips Extreme UV source. The Philips source concept is based on a discharge plasma ignited in a Sn vapor plume that is ablated by a laser pulse. Using rotating electrodes covered with a regenerating tin surface, the problems of electrode erosion and power scaling are fundamentally solved. Most of the work of the past year has been dedicated to develop a lamp system which is operating very reliably and stable under full scanner remote control. Topics addressed were the development of the scanner interface, a dose control system, thermo-mechanical design, positional stability of the source, tin handling, and many more. The resulting EUV source-the Philips NovaTin(R) source-can operate at more than 10kW electrical input power and delivers 200W in-band EUV into 2π continuously. The source is very small, so nearly 100% of the EUV radiation can be collected within etendue limits. The lamp system is fully automated and can operate unattended under full scanner remote control. 500 Million shots of continuous operation without interruption have been realized, electrode lifetime is at least 2 Billion shots. Three sources are currently being prepared, two of them will be integrated into the first EUV Alpha Demonstration tools of ASML. The debris problem was reduced to a level which is well acceptable for scanner operation. First, a considerable reduction of the Sn emission of the source has been realized. The debris mitigation system is based on a two-step concept using a foil trap based stage and a chemical cleaning stage. Both steps were improved considerably. A collector lifetime of 1 Billion shots is achieved, after this operating time a cleaning would be applied. The cleaning step has been verified to work with tolerable Sn residues. From the experimental results, a total collector lifetime of more than 10 Billion shots can be expected.

Tin DPP Source Collector Module (SoCoMo): Status of Beta products and HVM developments

For industrial EUV (extreme ultra-violet) lithography applications high power EUV light sources are needed at a central wavelength of 13.5 nm. Philips Extreme UV GmbH, EUVA and XTREME technologies GmbH have jointly developed tin DPP (Discharge Produced Plasma) source systems. This paper focuses in the first part on the results achieved from the Alpha EUV sources in the field. After integration of power upgrades in the past, now the focus is on reliability and uptime of the systems. The second part of this paper deals with the Beta SoCoMo that can be used in the first pre-production scanner tools of the lithography equipment makers. The performance will be shown in terms of power at Intermediate Focus, dose stability and product reliability but also its reachable collector lifetime, the dominant factor for Cost of Operation. In the third part of the paper the developments for the high volume manufacturing (HVM) phase are described. The basic engineering challenges in thermal scaling of the source and in debris mitigation can be proven to be solvable in practice based on the Beta implementation and related modeling calibrated with these designs. Further efficiency improvements required for the HVM phase will also be shown based on experiments. The further HVM roadmap can thus be realized as evolutionary steps from the Beta products.

Physical properties of the HCT EUV source

The paper describes recent progress on the development of an EUV source based on a hollow cathode triggered gas discharge (HCT). The principle of operation has been described in previous publications. When operated with Xe, a repetition frequency up to 4 kHz, conversion efficiency of 0.55% inband radiation in 2π and a pinch size below 3mm in length was demonstrated. Todays requirements on a commercial EUV source for volume production of wafers still exceed the current performance by large factors both in terms of output power and life time. This paper will discuss the roadmap to high power and will also show elements of the way to extended life time. Particular focus will be put onto the physical limits of Xe as radiator and the advantages of using Sn instead. It will be demonstrated that the spectral efficiency of Sn is a factor of 3 higher than Xe.

Xenon DPP Source Technologies for EUVL Exposure Tools

The learning gained in previous developments for EUV Micro Exposure and Alpha Tools builds the basis for the EUVL source development at XTREME technologies and Philips EUV. Field data available from operation of these tools are in use for continuous improvements in core technology areas such as plasma generation and forming, component reliability, debris mitigation and optical performance. Results from integration and operation of alpha tool sources are presented in the areas power performance, component lifetime and debris mitigation efficiency. The analysis results and simulation work of the realized EUV source concept are discussed and innovative concepts for component and module improvements are introduced. The technological limit for the Xenon based sources seems to be reached on alpha performance level. Therefore the next EUV source generations are based on Tin to increase the efficiency and full performance of those sources. For the Betatool and HVM source generations a joint development work between XTREME technologies and Philips EUV is introduced. The related work is content of another presentation of this conference.

Status of Philips' extreme UV source

The paper describes progress of the Philips’ hollow cathode triggered (HCT) gas discharge EUV source. The program has been focussed on three major areas: (1) Studying the basic physics of ignition, pinch formation and EUV generation. The paper reports on progress in this area and particularly describes the underlying atomic physics both for Xe and Sn. (2) Discharge based on Sn. Results on overall efficiency more than 5 times the Xe efficiency are reported as well as high frequency operation up to 6.5 kHz. This system shows all the necessary ingredients for scaling to production power levels. (3) Integration of the Xe source in an alpha tool. Results on integration issues like electrode life time, collector life time and dose control will be presented.

Design and fabrication considerations of EUVL collectors for HVM

The power roadmap for EUVL high volume manufacturing (HVM) exceeds the 200W EUV in-band power at intermediate focus, thus posing more demanding requirements on HVM sources, debris suppression systems and collectors. Starting from the lessons learned in the design and fabrication of the grazing incidence collectors for the Alpha EUVL scanners, Media Lario Technologies is developing HVM optical solutions that enable designed-in lifetime improvements, such as larger source-collector distances, optimized collection efficiency through larger collected solid angles, and customized EUV reflective layers. The optical design of an HVM collector is described together with the selection of the sacrificial ruthenium reflective layer. The water cooling layout of the collector is evolved from the integrated cooling technology developed at Alpha level into an innovative cooling layout that minimizes the thermal gradients across the mirrors and allows controlling the optical performance at the far-field plane. Finally, the evolution of the collectors manufacturing technologies for HVM is discussed. XTREME technologies and Philips Extreme UV support this work by integrating the collector in the complete source collector module (SoCoMo). At system level, each component of the SoCoMo is part of a development and improvement plan leading to a comprehensive system that will fulfill the 200+ W EUV in-band power at intermediate focus.

Thermal and Optical Characterization of Collectors Integrated in a Sn-DPP based SoCoMo

The paper presents the results of an investigation into the thermal and optical characteristics of alpha-type dual-mirror grazing incidence collectors for Extreme Ultra-violet Lithography integrated into a tin-fueled discharge produced plasma source. The performance of the system is assessed at various power levels and temperature conditions. The thermal and the optical data, in particular images at extra-focal planes behind the intermediate focus, are compared to the predictions of the thermo-optical model of the system. The data we present provide verification of the models used to design the collector and validation of the thermo-optical modeling approach for design of future generations of collectors.

Status of DPP EUV sources development for Beta/HVM

XTREME technologies and Philips EUV have provided the majority of available EUV sources based on Discharge Produced Plasma (DPP) technology worldwide since 2003. The fact that all existing prototype scanners make use of DPP sources and that further power scaling and debris mitigation upgrades are made according to plan clearly contributes to the maturity of this technology. We will present the latest status of our tin based DPP sources in the joint development work of XTREME technologies and Philips EUV. Demonstration experiments pave the way for this technology towards the HVM power level.