We propose a method for surface reconstruction of artist paintings. In order to reproduce the appearance of a painting, including color, surface texture, and glossiness, it is essential to acquire the pixel-wise light reflection property and orientation of the surface and render an image under an arbitrary lighting condition. A photometric approach is used to estimate bidirectional reflectance distribution functions (BRDFs) and surface normals from a set of images photographed by a fixed camera with sparsely distributed point light sources. A robust and computationally less expensive nonlinear optimization algorithm is proposed that optimizes the small number of parameters to simultaneously determine all of the specular BRDF, diffuse albedo, and surface normal. The proposed method can be applied to moderately glossy surfaces without separating captured images into diffuse and specular reflections beforehand. Experiments were conducted using oil paintings with different surface glossiness. The effectiveness of the proposed method is validated by comparing captured and rendered images.
EUVL is the most promising candidate of 32 nm generations and beyond. In this paper, we present Canon's
development status of EUVL technologies. The system design of the EUV full field high volume manufacturing tool
(VS2) is under way. The specification of VS2 is presented in this paper. The fabrication of six-aspheric-mirror prototype
projection optics (PO1) of NA 0.3 has been started. The PO1 is fabricated to evaluate and improve our technologies
of polishing and measuring the figure of mirrors. We present some results of the figuring accuracy of the mirror. EUVL
will be required to resolve sub-twenty nm L&S patterns. We are studying off-axis illumination technologies and high-
NA technologies. The simulation results of the resolution capability and the DOF are presented.
We developed a small field exposure tool (SFET) in collaboration with EUVA (Extreme Ultraviolet Lithography
System Development Association). SFET was installed at SELETE (Semiconductor Leading Edge Technologies;
Japanese Consortium) in 2006. SFET is positioned as a cornerstone of the manufacturing technologies for EUVL Full-
Field tools as well as tool for resist and mask development. We started the system design of the Full-Field tool and
fabrication of the six-mirror projection optics based on the experience of the SFET. In this paper, we introduce the
outline of Canon's activities for the full-field tool. EUVL is requested to resolve the sub 30 nm features. The studies of
the resolution for higher NA EUV projection optics is also presented.
The wavefront measurements have been performed with the EUV Wavefront Metrology System (EWMS) for the first
time using a prototype projection optic as a test optic. The wavefronts of the test optic was measured at the five positions
in the exposure field with the Digital Talbot Interferometer (DTI). The RMS magnitude of the wavefront errors ranged
from 0.71 λ (9.58 nm) to 1.67 λ (22.75 nm). The results obtained with the DTI were compared to those with the Cross
Grating Lateral Shearing Interferometer (CGLSI). As a result of a repeatability assessment, it was found that the EWMS
can stably measure the wavefronts of the test optic. Additionally, unwrapping of the phase map was found to be related
to the precision of the measurement.
Precise measurements of the wavefront aberrations of projection optics with 0.1 nm RMS accuracy are indispensable to
develop the extreme ultraviolet (EUV) lithography. In order to study measurement methods, we built the Experimental
EUV Interferometer (EEI) that has built-in Schwarzschild-type optics as test optics and was supplied with EUV
radiation of 13.5 nm in wavelength from a synchrotron radiation facility as a source light. The EEI can evaluate several
methods of EUV interferometory replacing optical parts easily. Those methods are dividable into two categories,
namely point diffraction interferometer (PDI) and lateral shearing interferometer (LSI) and those were experimentally
compared. Finally, 0.045nm RMS of reproducibility was achieved with PDI method and the residual systematic error
after removing specified errors was reduced to 0.064nm RMS excluding axial symmetrical aberrations. In addition, one
of LSI-type methods also proved to have almost enough accuracy for the assembly of the projection optics.
Comparisons between several at-wavelength metrological methods are reported. The comparisons are performed by measuring one test optic with several kinds of measurement methods from the viewpoints of accuracy, precision and practicality. According to our investigation, we found that the PDI, the LDI, and the CGLSI are the most suitable methods for evaluating optics for EUV lithography.
We present the experimental results of EUVA Absolute Point Diffraction Interferometer (ABSPDI) and Lateral Shearing Interferometer (LSI) for at-wavelength characterization of the projection lens for use in extreme-ultraviolet lithography (EUVL). The attained repeatability of either type of the interferometers is within 0.04nmRMS. The experimental results have shown good consistency between the LSI and ABSPDI. The reasons for the residual differences have been analyzed and we believed it is mainly due to the CCD tilt effect in the experimental system. After the CCD tilt effect was removed, a better consistency below 0.33nm RMS has been achieved.
We are developing an at-wavelength interferometer for EUV lithography systems. The goal is the measurement of the wavefront aberration for a six-aspherical mirror projection optic. Among the six methods that EEI can measure, we selected CGLSI and PDI for comparison. PDI is a method well-known for its high accuracy, while CGLSI is a simple measurement method. Our comparison of PDI and CGLSI methods, verified the precision of the CGLSI method. The results show a difference between the methods of 0.33nm RMS for terms Z5-36. CGLSI measurement wavefronts agree well with PDI for terms Z5-36, and it is thought of as a promising method. Using FFT analysis, we estimated and then removed the impact of flare on the wavefront. As a result of having removed the influence of flare, the difference between CGLSI and PDI improved to only 0.26nm RMS in Zernike 5-36 terms. We executed PDI wavefront retrieval with FFT, which has not been used till now. By confirming that the difference between methods using FFT and Phase shift is 0.035nm RMS for terms Z5-36, we have proven that PDI wavefront analysis with FFT is possible.
The recent experimental results of EUV wavefront metrology in EUVA are reported. EUV Experimental Interferometer (EEI) was built at the NewSUBARU synchrotron facility of University of Hyogo to develop the most suitable wavefront measuring method for EUV projection optics. The result is to be reflected on EWMS (EUV Wavefront Metrology System) that measures wavefront aberrations of a six-aspherical mirror projection optics of NA0.25, of a mass-production EUV lithography tool. The experimental results of Point Diffraction Interferometer (PDI) and Lateral Shearing Interferometer (LSI) are shown and the error factors and the sensitivity of astigmatism measurements of these methods are discussed. Furthermore, for reducing these kinds of errors, another type of shearing interferometer called DTI (Digital Talbot interferometer) is newly introduced.
An Experimental extreme ultraviolet (EUV) interferometer (EEI) using an undulator as a light source was installed in New SUBARU synchrotron facility at Himeji Institute of Technology (HIT). The EEI can evaluate the five metrology methods reported before. (1) A purpose of the EEI is to determine the most suitable method for measuring the projection optics of EUV lithography systems for mass production tools.
An experimental extreme UV (EUV) interferometer (EEI) using an undulator light source was designed and constructed for the purpose of developing wavefront measurement technology with the exposure wavelength of the projection optics of EUV lithography systems. EEI has the capability of performing five different EUV wavefront metrology methods.
An EUV reflectometer, based on a laser-produced plasma (LPP) light source, has been developed for characterization of EUV lithography systems. The reflectometer consists of the LPP light source, a prefocusing toroidal mirror, a grating monochromator, a polarizer, a beam intensity monitor, a refocusing toroidal mirror and a sample stage. The LPP light source is driven by a Nd:YAG laser; the laser beam is focused onto a copper tape target. A debris mitigation system that uses a rotating shutter was developed. Higher-orders formthe grating monochromator were suppressed to less than 0.2% of incident beam intensity by total reflection of three grazing incidence mirros. In order to compensate for beam intensity instability, a beam intensity monitor using a grating beamsplitter was installed between the refocusing mirror and the sample. Beam intensity instability can be corrected to less than 0.1% by using the beam intensity monitor.