We present the first laboratory experiments using a notch-filter mask, a coronagraphic image mask that can produce infinite dynamic range in an ideal Lyot coronagraph according to scalar diffraction theory. We fabricated the first notchfilter mask prototype with .25 µm precision using an e-beam lithography machine. Our initial optical tests show that the prototype masks generate contrast levels of 10 −5 at 3λ/D and 10 −6 at ∼ 8λ/D, with a throughput of 27%. We speculate on the "as-is" performance of such a mask in the Hubble Space Telescope.

Abstract:We present here new experimental results on high contrast imaging of 10 -7 at 4.5λ/D (λ=0.820 microns) by combining a circular focal plane mask (coronagraph) of 2.5λ/D diameter and a multi-Gaussian pupil plane mask. Both the masks were fabricated on very high surface quality (λ/30) BK7 optical substrates using nano-fabrication techniques of photolithography and metal lift-off. This process ensured that the shaped masks have a useable edge roughness better than λ /4 (rms error better than 0.2 microns), a specification that is necessary to realize the predicted theoretical limits of any mask design. Though a theoretical model predicts a contrast level of 10 -12, the background noise of the observed images was speckle dominated which reduced the contrast level to 4x10 -7 at 4.5λ/D. The optical setup was built on the University of Illinois Seeing Improvement System (UnISIS) optics table which is at the Coude focus of the 2.5-m telescope of the Mt. Wilson Observatory. We used a 0.820 micron laser source coupled with a 5 micron single-mode fiber to simulate an artificial star on the optical test bench of UnISIS.

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Low-k dielectric materials compatible with copper interconnect fabrication processes extending to the sub-50-nm technology nodes are desired for high speed integrated circuit (IC) fabrication. We demonstrate that bisbenzocyclobutene (BCB), an organic low-k dielectric material, can be patterned with sub-100-nm resolution using electron beam lithography, providing new avenues for nanoscale electrical and optical interconnect fabrication. OVERVIEWThe demand for improved performance and increased speed of semiconductor integrated circuits (ICs) has resulted in increasing levels of device and interconnect integration. To avoid limiting electrical interconnect time delays, much research has focused on the development and implementation of low dielectric constant interlevel metal insulators compatible with low resistivity copper interconnects. The International Technology Roadmap for Semiconductors (ITRS) calls for an interlevel metal insulator with an effective dielectric constant of 2.6-3.1 for the 90-nm and 70-nm technology nodes and 2.3-2.7 for the 65-nm technology node.

We present the first laboratory experiments using a notch-filter mask, a coronagraphic image mask that can produce infinite dynamic range in an ideal Lyot coronagraph according to scalar diffraction theory. We fabricated the first notchfilter mask prototype with .25 µm precision using an e-beam lithography machine. Our initial optical tests show that the prototype masks generate contrast levels of 10 −5 at 3λ/D and 10 −6 at ∼ 8λ/D, with a throughput of 27%. We speculate on the "as-is" performance of such a mask in the Hubble Space Telescope.