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Immersion patterning down to 27 nm half pitch

Published in:
J. Vac. Sci. Technol. B, Microelectron. Process. Phenon., Vol. 24, No. 6, November/December 2006, pp. 2789-2797 (EIPBN 2006, 30 May-2 June 2006).

Summary

Liquid immersion interference lithography at 157 nm has been used to print gratings of 27 nm half pitch with a fluorine-doped fused silica prism having index of 1.66. In order to achieve these dimensions, new immersion fluids have been designed and synthesized. These are partially fluorinated organosiloxanes with indexes up to 1.5. Their absorbance is on the order of 0.4/um (base 10), enabling the use of liquid films with micron-size thickness. To utilize these semiabsorptive fluids, an immersion interference printer has been designed, built, and implemented for handling micron-scale liquid layers.
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Summary

Liquid immersion interference lithography at 157 nm has been used to print gratings of 27 nm half pitch with a fluorine-doped fused silica prism having index of 1.66. In order to achieve these dimensions, new immersion fluids have been designed and synthesized. These are partially fluorinated organosiloxanes with indexes up...

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Nanocomposite approaches toward pellicles for 157-nm lithography

Published in:
J. Microlith., Microfab., Microsyst., Vol. 4, No. 1, January-March 2005, pp. 013004-1 - 013004-6.

Summary

Pellicle materials for use at 157 nm must display sufficient transparency at this wavelength and adequate lifetimes to be useful. We blended a leading candidate fluoropolymer with silica nanoparticles to examine the effect on both the transparency and lifetime of the pellicle. It is anticipated that these composite materials may increase the lifetime by perhaps quenching reactive species and/or by dilution, without severely decreasing the 157-nm transmission. Particles surface-modified with fluorinated moieties are also investigated. The additives are introduced as stable nanoparticle dispersions to casting solutions of the fluoropolymers. The properties of these solutions, films, and the radiationinduced darkening rates are reported. The latter are reduced in proportion to the dilution of the polymer, but there is no evidence that the nanoparticles act as radical scavengers.
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Summary

Pellicle materials for use at 157 nm must display sufficient transparency at this wavelength and adequate lifetimes to be useful. We blended a leading candidate fluoropolymer with silica nanoparticles to examine the effect on both the transparency and lifetime of the pellicle. It is anticipated that these composite materials may...

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A high-power MEMS electric induction motor

Published in:
J. Microelectromech. Syst., Vol. 13, No. 3, June 2004, pp. 465-471.

Summary

An electric induction micromotor with a 4-mm-diameter rotor was designed and built for high-power operation. Operated at partial actuating voltage, the motor has demonstrated an air gap power in excess of 20 mWand torque of 3 5 Nmat speeds in excess of 55 000 rpm. Operation at higher power and speed was limited by bearing stability at higher rotational speeds. The device builds on an earlier micromotor demonstrated by Frechette et al. The high power of the present motor is enabled by its low-loss, high-voltage electric stator, which also offers improved efficiency. The development of this electromechanical device is an important enabling step not only for watt-scale micromotors, but also for the development of microelectric generators. This paper presents the motorαs design, the fabrication process that was created to meet its stringent design requirements, and its performance to date.
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Summary

An electric induction micromotor with a 4-mm-diameter rotor was designed and built for high-power operation. Operated at partial actuating voltage, the motor has demonstrated an air gap power in excess of 20 mWand torque of 3 5 Nmat speeds in excess of 55 000 rpm. Operation at higher power and...

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Photoresist outgassing: a potential Achilles heel for short wavelength optical lithography?

Published in:
SPIE Vol. 5376, Advances in Resist Technology and Processing XXI, 22-27 February 2004, pp. 1-15.

Summary

The outgassing of volatile organic compounds during photoresist exposure at short wavelengths (
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Summary

The outgassing of volatile organic compounds during photoresist exposure at short wavelengths (

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Marathon evaluation of optical materials for 157-nm lithography

Published in:
J. Microlithogr., Microfab., Microsyst., Vol. 2, No. 1, January 2003, pp. 19-26.

Summary

We present the methodology and recent results on the longterm evaluation of optical materials for 157-nm lithographic applications. We review the unique metrology capabilities that have been developed for accurately assessing optical properties of samples both online and offline, utilizing VUV spectrophotometry with in situlamp-based cleaning. We describe ultraclean marathon testing chambers that have been designed to decouple effects of intrinsic material degradation from extrinsic ambient effects. We review our experience with lithography-grade 157-nm lasers and detector durability. We review the current status of bulk materials for lenses, such as CaF(2) and BaF(2), and durability results of antireflectance coatings. Finally, we discuss the current state of laser durability of organic pellicles.
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Summary

We present the methodology and recent results on the longterm evaluation of optical materials for 157-nm lithographic applications. We review the unique metrology capabilities that have been developed for accurately assessing optical properties of samples both online and offline, utilizing VUV spectrophotometry with in situlamp-based cleaning. We describe ultraclean marathon...

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Investigation of the physical and practical limits of dense-only phase shift lithography for circuit feature definition

Published in:
J. Microlith., Microfab., Microsyst., Vol. 1, No. 3, October 2002, pp. 243-252.

Summary

The rise of low- k1 optical lithography in integrated circuit manufacturing has introduced new questions concerning the physical and practical limits of particular subwavelength resolution-enhanced imaging approaches. For a given application, trade-offs between mask complexity, design cycle time, process latitude and process throughput must be well understood. It has recently been shown that a dense-only phase shifting mask (PSM) approach can be applied to technology nodes approaching the physical limits of strong PSM with no proximity effects. Such an approach offers the benefits of reduced mask complexity and design cycle time, at the expense of decreased process throughput and limited design flexibility. In particular, dense-only methods offer k1,0.3, thus enabling 90 nm node lithography with high-numerical aperture 248 nm exposure systems. We present the results of experiments, simulations, and analysis designed to explore the trade-offs inherent in dense-only phase shift lithography. Gate and contact patterns corresponding to various fully scaled circuits are presented, and the relationship between process complexity and design latitude is discussed. Particular attention is given to approaches for obtaining gate features in both the horizontal and vertical orientation. Since semiconductor investment is dependent on cost amortization, the applicability of these methods is also considered in terms of production volume.
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Summary

The rise of low- k1 optical lithography in integrated circuit manufacturing has introduced new questions concerning the physical and practical limits of particular subwavelength resolution-enhanced imaging approaches. For a given application, trade-offs between mask complexity, design cycle time, process latitude and process throughput must be well understood. It has recently...

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Infrared frequency selective surfaces fabricated using optical lithography and phase-shift masks

Published in:
J. Vac. Sci. Technol. B, Vol. 19, No. 6, November/December 2001, pp. 2757-2760. (45th Int. Conf. on Electron, Ion, and Photon Beam Technology and Nanofabrication (EIPBN), 29 May-1 June 2001.)

Summary

A frequency selective surface (FSS) structure has been fabricated for use in a thermophotovoltaic system. The FSS provides a means for reflecting the unusable light below the band gap of the thermophotovoltaic cell while transmitting the usable light above the band gap. This behavior is relatively independent of the light's incident angle. The fabrication of the FSS was done using optical lithography and a phase-shift mask. The FSS cell consisted of circular slits spaced by 1100 nm. The diameter and width of the circular slits were 870 and 120 nm, respectively. The FSS was predicted to pass wavelengths near 7 um and reflect wavelengths outside of this pass band. The FSSs fabricated performed as expected with a pass band centered near 5 um.
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Summary

A frequency selective surface (FSS) structure has been fabricated for use in a thermophotovoltaic system. The FSS provides a means for reflecting the unusable light below the band gap of the thermophotovoltaic cell while transmitting the usable light above the band gap. This behavior is relatively independent of the light's...

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Monolithic 3.3V CCD/SOI-CMOS Imager Technology

Summary

We have developed a merged CCD/SOI-CMOS technology that enables the fabrication of monolithic, low-power imaging systems on a chip. The CCD's, fabricated in the bulk handle wafer, have charge-transfer inefficiencies of about 1x10(-5) and well capacities of more than 100,000 electrons with 3.3-V clocks and 8x8um pixels. Fully depleted 0.35pm SOI-CMOS ring oscillators have stage delay of 48ps at 3.3V. We demonstrate for the first time an integrated image sensor with charge-domain A/D conversion and on-chip clocking.
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Summary

We have developed a merged CCD/SOI-CMOS technology that enables the fabrication of monolithic, low-power imaging systems on a chip. The CCD's, fabricated in the bulk handle wafer, have charge-transfer inefficiencies of about 1x10(-5) and well capacities of more than 100,000 electrons with 3.3-V clocks and 8x8um pixels. Fully depleted 0.35pm...

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Dynamic suppression of interface-state dark current in buried-channel CCDs

Published in:
IEEE Trans. Electron. Devices, Vol. 38, No. 2, February 1991, pp. 285-290.

Summary

It is shown that the time dependence of the carrier generation rate at a depleted surface can be exploited to completely suppress interface-state dark current in buried-channel charge-coupled devices (CCDs). When a surface is switched from an inverted to a depleted state, the generation current recovers with a time constant which is strongly temperature dependent and varies from a few milliseconds at room temperature to nearly 3 h at -80 degrees C. This property can be applied to three- and four-phase CCDs by exchanging charge packets between adjacent phases within a cell at a rate that ensures that each phase remains out of inversion for time that is short in comparison to the recovery time. Measurements of this effect have been made on a CCD imager over the temperature range from -40 degrees C to +22 degrees C, and the results agree well with theory.
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Summary

It is shown that the time dependence of the carrier generation rate at a depleted surface can be exploited to completely suppress interface-state dark current in buried-channel charge-coupled devices (CCDs). When a surface is switched from an inverted to a depleted state, the generation current recovers with a time constant...

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