Alternating Phase Shift Mask (APSM) Technology has been developed and successfully implemented for the poly gate of 65nm node Logic application at Intel. This paper discusses the optimization of the mask design rules and fabrication... more
Alternating Phase Shift Mask (APSM) Technology has been developed and successfully implemented for the poly gate of 65nm node Logic application at Intel. This paper discusses the optimization of the mask design rules and fabrication process in order to enable high volume ...
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Moore's law has been guiding the semiconductor industry for four decades. Lithography is the key enabler to keep the industry on the technology treadmill. Lithographers have been facing unprecedented challenges during last five years... more
Moore's law has been guiding the semiconductor industry for four decades. Lithography is the key enabler to keep the industry on the technology treadmill. Lithographers have been facing unprecedented challenges during last five years to keep the technology on the technology treadmill by developing various kinds of resolution enhancement techniques (RETs). In low K1 regime, co-optimization of design, layout mask, OPC, lithography and etching is the primary strategy to deliver a production-worthy patterning solution. Optical shrink is not a trivial task anymore. Intel always pursues parallel patterning techniques based on the dual exposure wavelength patterning strategy. While EUVL is the preferred patterning solution for 32nm node, 193nm immersion lithography with super high NA illumination is one of the parallel patterning strategies. The effects of polarization at super high NA illumination on mask technology, such as lens reduction ratio, blank absorber thickness and image imbalance correction, and restriction on design layout are addressed in this paper. Contact patterning is extremely challenging at low K1. Contact shape factor (circularity) which impacts the design rule will be discussed in this paper. Explosion of data file size and mask write time, stringent mask CD control and mask defect disposition are direct consequences of low-K1/high-MEEF (Mask Error Enhancement Factor) lithography. Mask makers alone cannot resolve the challenges in a cost effective manner. A seamless integration solution is a must.
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An analysis of the stability and halo formation is presented for a breathing axisymmetric beam of uniform density [Kapchinsky-Vladimirsky (KV) beam] in a uniform focusing channel. Theoretical results are obtained for the form of modes... more
An analysis of the stability and halo formation is presented for a breathing axisymmetric beam of uniform density [Kapchinsky-Vladimirsky (KV) beam] in a uniform focusing channel. Theoretical results are obtained for the form of modes involving nonuniform charge density. In ...
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An analysis of the stability of a breathing beam of uniform density and circular cross section is presented. Theoretical results are obtained for the form of the modes involving nonuniform charge density. In particular, the mismatch-tune... more
An analysis of the stability of a breathing beam of uniform density and circular cross section is presented. Theoretical results are obtained for the form of the modes involving nonuniform charge density. In particular, the mismatch-tune depression space is explored to determine the ...
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ABSTRACT
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Alternating phase shift mask (altPSM) as a strong resolution enhancement technique is increasingly required to meet the tighter lithographic requirements on gate critical dimension (CD) control, depth of focus and low k1 applications in... more
Alternating phase shift mask (altPSM) as a strong resolution enhancement technique is increasingly required to meet the tighter lithographic requirements on gate critical dimension (CD) control, depth of focus and low k1 applications in full chip patterning of logic and memory devices. While the frequency doubling mechanism of altPSM benefits the quality of imaging, the inherent intensity asymmetry between phase
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Deviations from paraxial image models are significant at numerical apertures (NA) planned to support immersion lithography. Apodization and rotation of polarization by high numerical optics are well-characterized phenomena. Similar... more
Deviations from paraxial image models are significant at numerical apertures (NA) planned to support immersion lithography. Apodization and rotation of polarization by high numerical optics are well-characterized phenomena. Similar behaviors follow from intrinsic properties of photomask patterns at high spatial frequencies. Diffraction efficiencies differ from values predicted using Kirchhoff boundary conditions, and depend on polarization. Pellicles also apodize diffraction patterns
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Particle beams with collimated discrete charged carriers such as electrons have been employed to lithographically transfer design patterns onto the photoresist for fabrication of devices, such as photomasks. In this paper, we use a single... more
Particle beams with collimated discrete charged carriers such as electrons have been employed to lithographically transfer design patterns onto the photoresist for fabrication of devices, such as photomasks. In this paper, we use a single standard deviation sigma of total blur based on Gaussian convolution kernel to address the limit of ebeam lithography, where the total blur is constituted of
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Ultra high numerical aperture (NA) enables extension of ArF lithography for the 45 technology node and beyond. The resulting changes in design rules drives feature sizes on the mask into the sub-wavelength regime. As 2-beam imaging... more
Ultra high numerical aperture (NA) enables extension of ArF lithography for the 45 technology node and beyond. The resulting changes in design rules drives feature sizes on the mask into the sub-wavelength regime. As 2-beam imaging techniques (off-axis illumination and alternating phase shift mask) are required for strong resolution enhancement in low-k1 lithography, traditional scalar and paraxial approximations used for optical image modeling are no longer valid in the ultra high NA regime. Vector and thick-mask based models are required to account for topographic effects and large angles of incident light at the reticle plane in ultra-high NA systems. Although vector-based imaging theory is well understood, experimental validation is required to ensure the appropriate topographical and optical parameters are being used. To address these issues, finite-difference time-domain rigorous electromagnetic simulation are compared to experimental measurements of the polarization dependent diffraction efficiencies on advanced optical reticles. Based on these results, the impact of mask induced polarization to vectorial imaging latitude is assessed. The impact of polarization purity, mask absorber profile, and Fresnel effects through the pellicle on process window and OPC are also discussed.
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Development of extended optical systems using liquid immersion for patterning enables numerical apertures... more
Development of extended optical systems using liquid immersion for patterning enables numerical apertures > 1.2 lithography. Hyper numerical aperture (NA) lithography has to deal with extremely oblique incident light, mask polarization, mask topography effects and large diffraction angle from mask feature with tight pitch. Simulation tools predicting highly accurate results based on real experimental data are widely used in the
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The 2005 edition of the International Technology Roadmap for Semiconductors specifies that phase errors of alternating phase-shifting masks (APSM) should approach +/- 1 degree by 2008. This specification is reasonably motivated by the... more
The 2005 edition of the International Technology Roadmap for Semiconductors specifies that phase errors of alternating phase-shifting masks (APSM) should approach +/- 1 degree by 2008. This specification is reasonably motivated by the desire to keep imaging effects of mask errors below those of aberrations of projection optics, but it implies a questionable assumption that the phase of a feature
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Pixelated phase masks rendered from computational lithography techniques demand one generation-ahead mask technology development. In this paper, we reveal the accomplishment of fabricating Cr-less, full field, defect-free pixilated phase... more
Pixelated phase masks rendered from computational lithography techniques demand one generation-ahead mask technology development. In this paper, we reveal the accomplishment of fabricating Cr-less, full field, defect-free pixilated phase masks, including integration of tapeout, front-end patterning and backend defect inspection, repair, disposition and clean. This work was part of a comprehensive program within Intel which demonstrated microprocessor device yield. To
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ABSTRACT This work describes the advantages, tolerances and integration issues of using Pixelated Phase Masks for patterning logic interconnect layers. Pixelated Phase Masks (PPMs) can act as variable high-transmission attenuated phase... more
ABSTRACT This work describes the advantages, tolerances and integration issues of using Pixelated Phase Masks for patterning logic interconnect layers. Pixelated Phase Masks (PPMs) can act as variable high-transmission attenuated phase shift masks where the pixelated phase configuration simultaneously optimizes OPC and SRAF generation. Thick mask effects help enable PPMs by allowing larger minimum pixel sizes and phase designs with near equal sized zero and piphase regions. PPMs with a 3-tone pixel mask (un-etched glass, etched glass, chrome) offer more flexible patterning capability compared to 2-tone pixel mask (no chrome) style but at the detriment of a more complex mask making process. We describe the issues and opportunities associated with using PPMs for patterning a 65nm generation first level metal layer of a micro-processor.
As silicon processes scale toward the 45 nm node using conventional 0.25 magnification, widths of sub-resolution assist feature (SRAF) and printable defects on photomasks drop far below the ArF laser wavelength. Adoption of polarized... more
As silicon processes scale toward the 45 nm node using conventional 0.25 magnification, widths of sub-resolution assist feature (SRAF) and printable defects on photomasks drop far below the ArF laser wavelength. Adoption of polarized illumination and higher numerical aperture (NA) could invalidate the scaling relations we used in the past to determine which small mask features or errors will print
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The longitudinal single bunch collective effects in a Muon Collider ring are theoretically examined. The situation involves an intense bunch, a short bunch, a small momentum compaction, a rather large impedance compared with the stability... more
The longitudinal single bunch collective effects in a Muon Collider ring are theoretically examined. The situation involves an intense bunch, a short bunch, a small momentum compaction, a rather large impedance compared with the stability threshold criterion, and a luminosity life time limited by muon decay to a thousand turns. Qualitative descriptions of stability are given and a scaling law for the instability threshold is derived. Numerical simulation results for the impedance-related instabilities are given for two cases of current interest-a 250 GeV×250 GeV demonstration machine and a 2 TeV×2 TeV high energy machine. The results of these simulations are in good agreement with the predictions of the scaling law and show that the longitudinal collective effects are controllable with a proper choice of parameters (viz. RF voltage, RF frequency, linear and non-linear longitudinal chromaticity)
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Novel RET-Pixelated Phase Mask (PPM) is proposed as a novel Resolution Enhancement Technique (RET). PPM is made of pixels of various phases with lateral dimensions significantly smaller than the illuminating radiation wavelength. Such PPM... more
Novel RET-Pixelated Phase Mask (PPM) is proposed as a novel Resolution Enhancement Technique (RET). PPM is made of pixels of various phases with lateral dimensions significantly smaller than the illuminating radiation wavelength. Such PPM with a singular choice of pixel ...