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GENERAL INFORMATION
chapter 1, EUV Source Technology: Challenges and Status
Table of Contents
- Section I: Introduction and Technology Review
- 1. EUV Source Technology: Challenges and Status
- Section II: Fundamentals and Modeling
- 3. Atomic Xenon Data
- Section III: Plasma Pinch Sources
- 12. Dense Plasma Focus Source
- Section IV: Laser-Produced Plasma (LPP) Sources
- 19. Technology for LPP Sources
- Section V: EUV Source Metrology
- 27. Flying Circus EUV Source Metrology and Source Development Assessment
- Section VI: Other Types of EUV Sources
- 31. Electron-Based EUV Sources for At-Wavelength Metrology
- Section VII: EUV Source Components
- 33. Grazing-Incidence EUV Collectors
Chapter Contents
- 1.1 Introduction
- 1.2 Conversion Efficiency of EUV Sources
- 1.3 EUV Source Power
- 1.4 Source Components and Their Lifetimes
- 1.5 Summary and Future Outlook
- References
Excerpt
1.1 Introduction
Extreme ultraviolet lithography (EUVL) is the leading technology being considered for printing circuits at the 32-nm node and below in a high-volume manufacturing (HVM) environment fab. In EUVL, a 13.5-nm-radiation wavelength generated by an EUV source is used to print circuits. Because light radiation is strongly absorbed at this wavelength, the entire EUVL scanner system must be in a vacuum environment, and all optics must be reflective, not refractive. Based on the HVM requirements of 100-wafer∕h throughput and other system requirements for optics, resist sensitivity, and overhead (Table 1.1), a power requirement of 115 W has been specified for HVM EUVL scanners. Besides power, EUV sources must meet additional specifications. The production-level requirements in Table 1.1 have been jointly agreed upon by major scanner manufacturers.
Discharge-produced plasma (DPP) and laser-produced plasma (LPP) are the leading technologies for generating high-power EUV radiation at 13.5 nm. In both technologies, hot plasma of ≈20–50 eV of the chosen fuel material is generated, which produces EUV radiation. In DPP, magnetic pinching of low-temperature plasma generates the high-temperature plasma. In LPP, the target material is heated by a laser pulse to generate high-temperature plasma. Xenon, tin, and lithium are the fuel materials of choice for EUV sources.
The cost-effective implementation of EUVL in HVM presents many technical challenges, of which the EUV source power has remained the greatest one until recently. In the fall of 2004, significant progress in EUV source power was reported at the EUVL Symposium in Miyazaki, Japan, making source power a lesser concern. The current challenges for implementing EUVL in HVM are listed in Table 1.2.
Today worldwide, more than eight suppliers and consortia are working to develop high-power EUV sources for EUVL. In addition, some suppliers are working to develop low-power EUV sources that are finding applications in metrology to support EUVL. This chapter presents the status of high-power EUV source technology and summarizes the technical challenges that must be overcome to meet the specifications for high-power EUV sources in HVM.
1.2 Conversion Efficiency of EUV Sources
1.2.1 DPP versus LPP
The conversion efficiency (CE) is the ratio of energy radiated by the EUV source in a 2% bandwidth (BW) around 13.5 nm to the input energy to the EUV source. The CE is used to estimate the utility requirements, choose the fuel, and understand the limits of power scaling. The fundamental CE for a fuel represents the upper limit of CE for that particular fuel.
For DPP, the input energy is the electrical energy consumed by the entire system (energy dissipated in the plasma plus energy lost in the electrical system).
©2006 Society of Photo-Optical Instrumentation Engineers
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