Yukio Morishige

Growth and Characterization of Liquid-Phase Epitaxial Bi-Substituted Iron Garnet Films for Magneto-Optic Application

The effects of the chemical species of host rate-earth ions, melt compositions and growth orientations on the Bi-substitution level and magneto-optic properties of Bi-substituted garnet films grown by liquid-phase epitaxy were examined. For Gd3+ ions, a higher level of Bi substitution was attained than for Y3+ or Lu3+ ions, when garnet films were grown under the same growth conditions. A maximum Faraday rotation coefficient of -2880°/cm at 1.30 µm was observed in the (GdBi)3(FeAlGa)5O12 film with a Bi-substitution level of 1.56 moles per garnet formula unit. The optical absorption coefficient was as small as 1.6 cm-1 in the (GdBi)3(FeAlGa)5O12 film with a Faraday rotation coefficient of -1800°/cm; consequently, a figure of merit of 267°/dB was attained at 1.30 µm.

High‐speed laser direct writing of tungsten conductors from W(CO)6

High‐speed laser direct writing of tungsten conductors using tungsten‐hexacarbonyl [W(CO)6] is demonstrated. Tungsten lines were constructed on the Si‐LSI substrate at a writing speed as high as 300 μm/s with laser‐induced low‐pressure chemical vapor deposition. This speed is more than two orders of magnitude higher than the previously reported value for this material. Experiments are analyzed within the conventional three‐dimensional diffusion theory for the reactant. It has been found that the deposition rate limiting factor is the transport rate for the reactant into the reaction zone. The upper limit of the writing speed is predicted to be of the order of mm/s for the present material.

Large scale two-step selective aluminum CVD on laser patterned palladium lines

Abstract In the present report we first outline and characterize the details of uniform deposition of PdAc from an acetone solution on a large area. Then, we investigate the parameters that highly influence the thickness and quality of the laser direct-written palladium lines (spin coating speed among others). Currently, good quality and uniform patterning of laser written thin lines of Pd have been achieved on samples as large as 4 inches in diameter. The Pd lines are well resolved (minimum of 3 μm in width now) and exhibit fairly good resistivity around 30 μΩ⋯cm. They also showed good adhesion to the SiO 2 substrate as they endure repeated Scotch tape adhesion tests. Moreover, the second step of highly selective Al-CVD has been investigated under various conditions and gave rise to resistivities of about 6.5 μΩ⋯cm and 3000 A thickness for a 7 min deposition. This process stands out as very promising for packaging and high density interconnect technologies.

Thick gold-film deposition by high-repetition visible pulsed-laser chemical vapor deposition

A highly conductive gold film, over 10 μm-thick with well-controlled linewidth, has been successfully deposited from dimethyl-gold-acetylacetonate and its fluorinated derivative by pyrolytic CVD (Chemical Vapor Deposition) with a high-repetition, visible, pulsed laser. The thermal damage to the polyimide substrate has been substantially suppressed by reducing the thermal diffusion length within 0.2 μm in pulsed-laser-induced transient heating, in contrast to the cw laser-CVD scheme. Reproducible and low contact resistance as low as 0.5 Ω between the written line and the existing gold line has been obtained. Sufficiently tough adhesion to polyimide has been observed for the deposit from dimethyl-gold-acetylacetonate. Reasonable agreement has been obtained between the observed deposition characteristics and analytical results for precursor supply rate and temperature increase during short-pulse irradiation.

Laser chemical vapor deposition direct patterning of insulating film

The 10 μm scale patterned SiO2 films with excellent insulating quality has been directly deposited by laser chemical vapor deposition projection printing. Leakage current through the SiO2 film was kept within permissible limits for large scale integration (LSI) functioning. This new local insulating scheme substantially extends the potential of laser direct writing circuit restructuring technology, such as in locally insulating two crossing interconnections on LSIs.

Novel drilling technique in polyimide using visible laser

We report a new and fast laser‐drilling technique in polyimide. This drilling process consists of two steps. First, the polyimide is irradiated with millisecond pulse of visible laser light. Second, the debris inside and around the holes are ultrasonically cleaned in water in a short time. In this report, we also analyze the emitted light originated from the laser induced polyimide decomposition that leads to the drilling. The mechanism behind the drilling is believed to be associated to a volcano‐eruption‐like behavior. This inexpensive technique provides good quality drilling, high throughput, and very promising applications in packaging technology.

High-accuracy laser mask repair technology using ps UV solid state laser

Laser Mask Repair System named LM700A has been developed to satisfy the increasing demands for higher accuracy with thigh throughput photomask repair system in recent semiconductor industry requirements. This paper introduces the basic configuration of the system, evaluated results for Chromium (Cr) binary masks and Molybdenum Silicide (MoSi) HalfTone (HT) phaseshift masks repairing performances, and the features of removing process using mid range (250ps) pulse duration ablation mechanism.

Output-stabilized high-repetition-rate 1.545-μm Q-switched Er:glass laser

A newly developed Q-switched Er:glass laser with a long pulse length, suitable for fiber-fault location, is described. A specially prepared athermal rod has made it possible to operate at a 5-Hz repetition rate. A feedback-stabilized Q-switching method involving fluorescence monitoring has been applied to this three-level laser system. A ±3% power stability (standard deviation) has been obtained for a 1-μsec pulse with a 2-mJ output energy.

1 PM SPECTRALLY NARROWED ARF EXCIMER LASER INJECTION LOCKED BY FOURTH HARMONIC SEED SOURCE OF 773.6 NM TI:SAPPHIRE LASER

We have achieved spectrum narrowing to 1 pm in a high‐power ArF excimer laser injection locked by an all solid‐state fourth harmonic (193.4 nm) seed source of 773.6 nm Ti:sapphire laser radiation. Superior laser properties such as sufficient output energy (90 mJ/pulse, 50 pps), locking efficiency exceeding 90%, wavelength drift less than 0.4 pm, and spectrum bandwidth fluctuation less than 0.2 pm were obtained, which meet the requirements for 1 Gbit dynamic random access memory microlithography.

Novel Technique of Laser Through-Hole Drilling in Teflon.

A novel technique of laser drilling of reinforced Teflon films with SiO2 particles is demonstrated. The new process consists of three simple steps. First, 300 A of gold is deposited on Teflon to allow laser absorption. Second, drilling is done by pulsed irradiation at a rate of one hole per pulse. At this stage the Teflon is only modified by the laser irradiation. Third, the modified Teflon is removed by ultrasonic cleaning, leaving behind clean through-holes of 50 µm in diameter. A potential drilling speed as high as 60000 holes/min with fairly high spatial resolution is the main attraction of this simple technique.