The authors describe a novel configuration for a wavelength selectable laser that provides wide tuning and distributed-feedback (DFB) performance and reliability at a fundamentally low cost structure. The configuration consists of a DFB laser array and a micromechanical mirror that selects one element of the array. The MEMS tilt mirror also loosens the tolerances, since the fine optical alignment is done electronically. Only one laser is operated at a time, with coarse tuning realized by selecting the correct laser and fine tuning by adjusting the chip temperature. The 33-nm total tuning at 20-mW fiber coupled power is obtained in a fully functional module.

A method for real-time backscatter correction has been implemented in a 50 keV raster-scan electron-beam mask exposure system. The real-time nature of the correction makes it an attractive, user transparent feature with flexibility to choose the correction algorithm and scattering parameters. This article describes the correction algorithms and the hardware added to the data path. We compare simulated critical dimension (CD) linearity with results from mask exposures in our new raster shaped beam proof-of-concept tool. Performance meets both throughput and CD linearity requirements for the 130 and 100 nm device generations.

A new form of read out for high density read-only memory is presented whereby a data density of 400 bits/μm2, corresponding to 256 Gbits/in.2, can be accessed at data rates in the tens of MHz range. The technique is based on detecting the modulation in light scattering from a sharp scattering object due to the dipole-dipole coupling between the probe and surface being scanned using a sensitive homodyne interferometer. Theoretical considerations indicate that data densities in the 100 Tbits/in.2 range could be accessed at data rates of 100 MHz using this technology.

A hash-memory device has been fabricated and demonstrated at room temperature by coupling a self-aligned, sub-50-nm quantum dot to the channel of a transistor on a silicon-on-insulator (SOI) substrate, Large threshold voltage shifts of up to 0.75 V are obtained for small erase/write voltages (less than or equal to 3 V) at room temperature. At 90 K, evidence of single electron storage is observed, The small size of this device is attractive for achieving high packing densities, while the relatively large output current (100 nA-mu A's), low off-state current (10 pA), and simple fabrication, requiring only minor variations in standard processing, make it suitable for integration with current silicon memory and logic technology.

The two basic structural elements of the integrated resonant channel-dropping filter are the rib waveguides and the first-order Bragg gratings. Spatial-phase-locked electron-beam lithography is used to write the Bragg grating patterns with a coherence better than λ0/150, and x-ray nanolithography is used to transfer the gratings onto optically patterned rib waveguides. These technologies are successfully combined to demonstrate a process by which channel-dropping filters and related devices can be fabricated.

A novel spectrometer is employed to study the spectrum of heavily doped quantum dots. A single-particle discrete spectrum is found to exist only in close vicinity to the Fermi energy. Levels further away are broadened beyond the average level spacing and merge to form a quasi-continuous spectrum. The broadening is traced to electron-electron interaction in the dot. For the discrete part of the spectrum, level statistics is studied as a function of magnetic field and found to agree remarkably well with recent calculations.

Very high performance sub-0.1mum channel nMOSFET's are fabricated with 35 angstrom gate oxide and shallow source-drain extensions. An 8.8-ps/stage delay at V(dd) = 1.5 V is recorded from a 0.08mum channel nMOS ring oscillator at 85 K. The room temperature delay is 11.3 ps/stage. These are the fastest switching speeds reported to date for any silicon devices at these temperatures. Cutoff frequencies (f(T)) of a 0.08-mum channel device are 93 GHz at 300 K, and 119 GHz at 85 K, respectively. Record saturation transconductances, 740 mS/mm at 300 K and 1040 mS/mm at 85 K, are obtained from a 0.05-mum channel device. Good subthreshold characteristics are achieved for 0.09 mum channel devices with a source-drain halo process.

Very high performance 0.1 /spl mu/m nMOSFETs are fabricated with 3.5 nm gate oxide and shallow arsenic/boron (halo) source-drain extension. A 10 ps/stage della is recorded at 85 K from a 0.08 pm channel ring osMlator, which is the fastest switching speed ever re- ported for any silicon device. The delay at room temper- ature is 13 ps/stage. Unity-current-gain frequency cutoffs (f/sub r/) of a 0.09 /spl mu/m channel device are 119 GHz at 85 K and 93 GHz at 300 K. Record high saturation transconductances, 1040 mSImm at 85 K and 740 mS/MM at 300 K , are obtained from a 0.05 /spl mu/m channel device. Good subthreshold characteristics are achieved for 0.1 /spl mu/m channel devices.

The spectrum of heavily doped quantum dots is found to be discrete only in close vicinity to the Fermi energy. Levels further away are broadened beyond the average level spacing and merge to form a quasi-continuous spectrum. This breakdown of a single particle picture is consistent with electron-electron interaction in the dot. For the discrete part of the spectrum, level statistics is studied as a function of magnetic field and found to agree remarkably well with recent calculations.

Bragg gratings have been formed in optical fibres by diffraction of a phase mask. This technique is expanded by allowing for the possibility of shifting the Bragg wavelength for a fixed mask periodicity. This method uses a simple lens to introduce a curvature on to the wavefront of the diffracting light that results in a magnification of the original periodicity formed by the mask. The Letter shows experimentally that the Bragg wavelength is shifted to shorter wavelength by the addition of a converging lens before the mask.

Earlier spatial-phase-locked e-beam lithography (SPLEBL) was proposed as a means of eliminating the well-known problem of feature placement precision in scanning electron-beam lithography. In SPLEBL, a grid with long-range spatial-phase coherence is created on a substrate (or on top of its resist coating) and this grid is used to feedback information on beam location to the control system. In initial tests a standard deviation (σ) of 0.3 nm for phase-locking precision in one dimension was demonstrated, which represents the finest field stitching ever obtained with any lithographic method. In two dimensions (2D), σx, σy=0.6, 0.4 nm was obtained. Moiré spatial-phase locking was also demonstrated in 2D. Two strategies for the global-fiducial grid appear feasible: plating base modulation and a thin film of holographically exposed photoresist on thin-film Al above the e-beam resist. Either would permit spatial-phase locking without exposure of resist.

Enhancement-mode Si/SiGe n-type modulation-doped transistors with a 0.5-mum-length T-gate have been fabricted. Peak transconductances of 390 mS/mm at room temperature and 520 mS/mm at 77 K have been achieved. These high values are attributable to a combination of the high quality of the material used, having a room temperature mobility of 2600 cm2/V . s at an electron sheet concentration of 1.5 x 10(12) cm2, and an optimized layer design that minimizes the parasitic series resistance and the gate-to-channel distance.

The authors report on the fabrication and the resultant device characteristics of the first 0.25- mu m gate-length field-effect transistor based on n-type modulation-doped Si/SiGe. Prepared using ultrahigh vacuum/chemical vapor deposition (UHV/CVD), the mobility and electron sheet charge density in the strained Si channel are 1500 (9500) cm/sup 2//V-s and 2.5*10/sup 12/ (1.5*10/sup 12/) cm/sup -2/ at 300 K (77 K). At 77 K, the devices have a current and transconductance of 325 mA/mm and 600 mS/mm, respectively. These values far exceed those found in Si MESFETs and are comparable to the best results achieved in GaAs/AlGaAs modulation-doped transistors.< >

The electron beam sensitivities of three different types of high molecular weight polysilmethylene polymers and copolymers were investigated. It was found that methyl derivatives of these polymers have high sensitivities to irradiation and have a negative tone. The influence of the molecular weight upon electron beam sensitivity was also investigated. In contrast to polysiloxanes, phenyl containing polysilmethylenes were found to have a much higher sensitivity (up to 10 ¢c for poly-1,1-diphenyl- 1-silacyclobutane) and comparable thermal stabilities (up to 400°C). It was found that some of these polymers have similar lithographic properties to the more common polysiloxanes. Mechanisms of crosslinking and degradation reactions of these polymers are discussed.

Switching delay measurements are reported for self-aligned, almost fully scaled, liquid-nitrogen-temperature operation NMOS inverters with deep-submicrometer gate lengths. The shortest delay per stage of 13.1 ps was measured in 0.1- mu m gate-length circuits. Circuit simulations based on the measured device characteristics show that still shorter delay times can be reached with such a technology.<>

Transport properties are investigated in self-aligned NMOS devices with gate lengths down to 0.07 mu m. Velocity overshoot was observed in the form of the highest transconductances measured to date in Si FETs, as well as in the trend of the transconductance with gate length. The measured transconductance reached 910 mu S/ mu m at liquid-nitrogen temperature and 590 mu S/ mu m at room temperature. Velocity overshoot, by making such transconductances possible, should extend the value of miniaturization to dimensions that are smaller than what was commonly assumed to be worthwhile to pursue.< >

The first device performance results are presented from experiments designed to assess FET technology feasibility in the 0.1-µm gate-length regime. Low-temperature device design considerations for these dimensions lead to a 0.15-V threshold and 0.6-V power supply, with a forward-biased substrate. Self-aligned and almost fully scaled devices and simple circuits were fabricated by direct-write electron-beam lithography at all levels, with gate lengths down to 0.07 µm. Measured device characteristics yielded over 750-mS/mm transconductance, which is the highest value obtained to date in Si FET's.