Laser-produced plasma sources offer the best option for scalability to support high-throughput lithography. Challenges associated with the complexity of such a source are being addressed in a pilot program where sources have been built and integrated with extreme-ultraviolet (EUV) scanners. Up to now, five pilot sources have been installed at R&D facilities of chip manufacturers. Two pilot sources are dedicated to product development at our facility, where good dose stability has been demonstrated up to levels of 32 W of average EUV power. Experimental tests on a separate experimental system using a laser prepulse to optimize the plasma conditions or EUV conversion show power levels equivalent to approximately 160 W within a low duty-cycle burst, before dose control is applied. The overall stability of the source relies on the generation of Sn droplet targets and large EUV collector mirrors. Stability of the Sn droplet stream is well below 1 μm root mean square during 100+ h of testing. The lifetime of the collector is significantly enhanced with improved coatings, supporting uninterrupted operation for several weeks.
Laser produced plasma (LPP) systems have been developed as a viable approach for the EUV scanner light sources to
support optical imaging of circuit features at sub-22nm nodes on the ITRS roadmap. This paper provides a review of
development progress and productization status for LPP extreme-ultra-violet (EUV) sources with performance goals
targeted to meet specific requirements from leading scanner manufacturers. The status of first generation High Volume
Manufacturing (HVM) sources in production and at a leading semiconductor device manufacturer is discussed. The
EUV power at intermediate focus is discussed and the lastest data are presented. An electricity consumption model is
described, and our current product roadmap is shown.
This paper describes the development of laser-produced-plasma (LPP) extreme-ultraviolet (EUV) source architecture
for advanced lithography applications in high volume manufacturing. EUV lithography is expected to succeed 193nm
immersion technology for sub-22nm critical layer patterning. In this paper we discuss the most recent results from high
EUV power testing and debris mitigation testing on witness samples and normal incidence collectors. Subsystem
performance will be shown including the CO2 drive laser, debris mitigation, normal incidence collector and coatings,
droplet generation, laser-to-droplet targeting control, intermediate-focus (IF) metrology and system use and experience.
In addition, a number of smaller lab-scale experimental systems have also been constructed and tested. This
presentation reviews the experimental results obtained on systems with a focus on the topics most critical for an HVM
Laser produced plasma (LPP) systems have been developed as a viable approach for the EUV scanner light source to support optical imaging of circuit features at sub-22nm and beyond nodes on the ITRS roadmap. This paper provides a review of development progress and productization status for LPP extreme-ultra-violet (EUV) sources with performance goals targeted to meet specific requirements from leading scanner manufacturers. The status of first generation High Volume Manufacturing (HVM) sources in production and of prototype source operation at a leading scanner manufacturer is discussed. The EUV power at intermediate focus is discussed and the lastest data is presented. An electricity consumption model is described, and our current product roadmap is shown.
Improved performance and specific results are reported for several test and prototype extreme ultraviolet (EUV) light sources developed for next-generation lithography. High repetition rate and high-power CO2 laser-produced plasma sources operating on tin droplet targets are described. Details of laser architecture, source chambers and system operation are given. Stable output power, efficient light collection, and clean EUV transmission could be achieved for hours of operation. We review progress during integration of light sources with collector mirrors reaching EUV power levels at intermediate focus of 60 W and 45 W, respectively, with duty cycles of 25% and 40%. Far-field EUV images of the collected light were recorded to monitor the source output performance during extended tests of collector longevity and debris protection with system operation time exceeding 50 h. Development results on EUV spectra, out-of-band (OOB) radiation, and ion debris obtained with dedicated metrology setups are also described. Angle-resolved measurements with ion energy analyzer and Faraday cups reveal the contributions of individual ion charge states in related spectra. Our laser-produced EUV light source technology has now reached a level of maturity in full integration where prototype sources can be delivered and pilot line introduction can be prepared.
This paper is devoted to the development of laser produced plasma (LPP) EUV source architecture for advanced
lithography applications in high volume manufacturing of integrated circuits. The paper describes the development
status of subsystems most critical to the performance to meet scanner manufacturer requirements for power and
debris mitigation. Spatial and temporal distributions of the radiation delivered to the illuminator of the scanner are
important parameters of the production EUV tool, this paper reports on these parameters measured at the nominal
repetition rate of the EUV source. The lifetime of the collector mirror is a critical parameter in the development of
extreme ultra-violet LPP lithography sources. Deposition of target material and contaminants as well as sputtering
and implantation of incident particles can reduce the reflectivity of the mirror coating substantially over time during
exposure even though debris mitigation schemes are being employed. We report on progress of life-test experiments
of exposed 1.6sr collectors using a Sn LPP EUV light source. The erosion of MLM coating is caused mostly by the
high-energy ions generated from the plasma. In this manuscript the ion distribution measured at small (14 degree)
and medium (45 degree) angles to the laser beam are presented. The measurements show that the chosen
combination of the CO2 laser and Sn droplet targets is characterized by fairly uniform angular ion energy
distribution. The maximum ion energy generated from the plasma is in the range of 3-3.5 keV for all incident angles
of the collector. The measured maximum energy of the ions is significantly less than that measured and simulated
for plasmas generated by short wavelength lasers (1 μm). The separation of ions with different charge states was
observed when a retarding potential was applied to the Faraday Cup detector.
Laser produced plasma (LPP) systems have been developed as a viable approach for the EUV scanner light source for
optical imaging of circuit features at sub-32nm and beyond nodes on the ITRS roadmap. This paper provides a review
of development progress and productization status for LPP extreme-ultra-violet (EUV) sources with performance goals
targeted to meet specific requirements from leading scanner manufacturers. We present the latest results on power
generation, stable and efficient collection, and clean transmission of EUV light through the intermediate focus. We
report on measurements taken using a 5sr collector optic on a production system. Power transmitted to intermediate
focus (IF) is shown. The lifetime of the collector mirror is a critical parameter in the development of extreme ultraviolet
LPP lithography sources. Deposition of target material as well as sputtering of the multilayer coating or
implantation of incident particles can reduce the reflectivity of the mirror coating during exposure. Debris mitigation
techniques are used to inhibit damage from occuring, the results of these techniques are shown. We also report on the
fabrication of 5sr collectors and MLM coating reflectivity, and on Sn droplet generators with droplet size down to 30μm
We report the use of a windowless resonant spectrophone to make highly sensitive (10-9 cm-1) photoacoustic measurements of atmospheric water vapor and aerosol absorption. A tunable high-resolution cw Nd:YAG laser was used to measure the water vapor lines and aerosol absorption spectrum at 1.064 mm. The water vapor absorption lines were used to calibrate the spectrophone for the aerosol measurements. The spectrophone was also calibrated using the theoretical expression with an independent measurement of the Q of the spectrophone. The initial windowless spectrophone has the ability to make in situ real- time measurements of atmospheric absorption to an accuracy sufficient for thermal blooming calculations. The ability of the spectrophone to detect at the 40-parts-per-trillion-level of other gaseous and volatile species is discussed. The use of resonant mufflers to isolate the spectrophone from external noise is also presented.