Shunji Kishida

Photothermal effect contribution on film quality improvement in excimer-laser induced metal CVD

KrF excimer laser induced Cr film deposition from Cr(CO)6 has been studied. Remarkable film quality dependence on laser intensity suggested the photothermal effect contribution of intensive uv laser pulses in the CVD process. A cw Ar-ion laser light and its second harmonic light were used, to separate photochemical and photothermal effects. As a result, photoinduced surface heating has been found to be very important for obtaining good quality metallic films in KrF laser induced Cr film CVD.

Laser induced metal deposition from organometallic solution

Solutions of bisbenzene metals in organic solvents have been used for the first time to produce localized deposition of metals on a glass substrate by laser induced pyrolysis. Molybdenum and chromium spots, as small as 10 μm in diameter, were obtained by using an argon‐ion laser at several tens of milliwatt power.

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.

Stable cw backward Raman amplification in optical fibers by stimulated Brillouin scattering suppression.

A backward pumping scheme with highly repetitive short pump pulses is described for cw Raman amplification of signal light in optical fibers. This pumping scheme makes possible stable and high-gain cw Raman amplification due to the efficient suppression of stimulated Brillouin scattering, which not only limits the gain but also deteriorates the gain stability of such amplification. Stable cw backward Raman amplification of 1.4-μm laser diode light signals has been achieved, for the first time, with gains as high as 14 dB in a 5.5-μm core diam and 3.5-km long single-mode fiber, pumped with a 1.32-μm mode-locked Nd:YAG laser.

cw oscillation in a Nd : phosphate glass laser

A stable cw operation in a Nd : phosphate glass laser has been acheived for the first time. An end‐pumping scheme with an Ar laser in combination with a new kind of phosphate glass material has been successfully used to reduce thermal problems. More than 10 mW cw output power has been obtained in the TEM00 mode.

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.

Aluminum chemical vapor deposition reaction of dimethylaluminum hydride on TiN studied by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry

To understand the nucleation mechanisms of aluminum film during chemical vapor deposition (CVD), the reactions of dimethylaluminum hydride (DMAH) with oxidized TiN and Si surfaces were studied by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). It was observed that DMAH exposure reduced the native oxide on the TiN surface, resulting in a clean TiN surface. The reduction of the native oxide and the deposition of Al on the TiN surface were enhanced with increasing DMAH dose. In contrast with the reaction on the TiN surface, no reduction of native oxide by DMAH exposure was observed on the Si surface except at the uppermost surface level analyzed by TOF-SIMS. The amount of Al deposited on the oxidized Si surface was less than that on the oxidized TiN surface under the same experimental conditions and was largely independent of the amount of DMAH dose over the studied range. The reduction of native oxide and the appearance of a clean TiN surface are thought to be important in accounting for the nucleation mechanism and the improved surface morphology of Al film deposited on TiN surfaces using the CVD process.

Aluminum Metallization Using a Combination of Chemical Vapor Deposition and Sputtering

An aluminum metallization process that combines blanket chemical vapor deposition and sputtering was developed for use in fabrication of future ultralarge scale integration interconnections. Blanket chemical vapor deposition of aluminum using dimethylaluminum hydride on titanium nitride, which provides superior step coverage and a smooth surface morphology for films of less than approximately 0.15 μm thickness, was only used for hole-filling. Subsequent aluminum alloy sputtering, which has a high deposition rate and provides smooth surface films, was used for the thickening of the aluminum films. This combination process draws on the respective advantages of both chemical vapor deposition and sputtering, which mutually compensate for each others drawbacks. As a result, via holes with a diameter of 0.3 μm and an aspect ratio of 2.7 were successfully filled. The resistance of contact holes fabricated by the combination process was slightly lower than that obtained in the conventional tungsten plug process due to low film resistivity of chemically vapor deposited aluminum. The contact resistivity for contacts to p- and n-type Si were 1.0 x 10 -7 and 2.9 x 10 -8 Ω cm 2 , respectively. Via hole resistance for 0.45 μm diameter holes was less than 1 Ω, which corresponds to a contact resistivity of less than 1.6 x 10 -9 Ω cm 2 between chemically vapor deposited aluminum and the underlayer titanium nitride.

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.