Excimer Laser Irradiation of Metallic Films on Ceramic Substrates

1991 ◽  
Vol 235 ◽  
Author(s):  
M. J. Godbole ◽  
A. J. Pedraza ◽  
D. H. Lowndes ◽  
J. R. Thompson
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Surface Region ◽  
Copper Films ◽  
Metallic Films ◽  
Ceramic Substrates ◽  
Near Surface ◽  
Excimer Laser Irradiation ◽  
Sputter Deposited ◽  
Density Threshold

ABSTRACTCopper films sputter deposited on mechanically polished (optical finish) and on annealed substrates were laser-irradiated at various energy densities. The effect of the substrate condition on both the evaporation threshold and the morphology of the laser-irradiated metallic films was investigated. The energy density threshold for laser-induced evaporation of the copper films was studied using energy dispersive x-ray spectroscopy (EDS) in a scanning electron microscope (SEM). It was found that for annealed substrates the energy density threshold decreases relative to the threshold for the as-polished condition. These results are compared with predictions of a mathematical model that assumes that the near surface region of the as-polished ceramic is a highly damaged region and, thus, constitutes a thermal barrier. The film remains intact and with almost no change in morphology after laser irradiation at energy densities lower than 0.80 J/cm2 if the substrate has been previously annealed. On the other hand, copper films deposited on as-polished substrates break up during laser processing forming copper islands.

Electroless copper films deposited onto laser-activated aluminum nitride and alumina

1994 ◽  
Vol 9 (4) ◽  
pp. 1019-1027 ◽  
Author(s):  
M. J. DeSilva ◽  
A. J. Pedraza ◽  
D.H. Lowndes
Keyword(s):  
Energy Density ◽  
Aluminum Nitride ◽  
Laser Irradiation ◽  
Laser Energy ◽  
Annealing Treatment ◽  
Surface Region ◽  
Laser Energy Density ◽  
Copper Films ◽  
Near Surface ◽  
Electroless Copper

Metallization of ceramic substrates by laser activation and subsequent electroless deposition has been demonstrated recently in aluminum nitride and alumina. However, the bond strength between the electroless copper and the ceiamic substrate is weak (less than 14 MPa). Low temperature annealing of electroless copper films deposited on substrates activated at low laser energies strongly increases the adhesion strength. The effectiveness of the annealing for improving the metal-ceramic bonding is dependent upon the laser treatment performed on the substrate prior to deposition. Faster deposition kinetics are obtained for both substrates by increasing the laser energy density. On the other hand, an increase in the laser energy density leads to poor adhesion strengths. The dislocation microstructure produced during laser irradiation in aluminum nitride is analyzed as a possible cause of laser activation. Free aluminum produced by laser irradiation of aluminum nitride and of alumina is discussed as another factor of laser activation. The chemical and microstructural changes taking place in the near-surface region as a consequence of laser-induced processes are correlated with adhesion enhancement promoted by the annealing treatment.

Microstructural changes of Aluminum Nitride after laser irradiation and electroless copper deposition

1994 ◽  
Vol 52 ◽  
pp. 636-637
Author(s):  
S. Cao ◽  
A. J. Pedraza ◽  
L. F. Allard
Keyword(s):  
Aluminum Nitride ◽  
Laser Irradiation ◽  
Electroless Deposition ◽  
Thermal Evaporation ◽  
Surface Region ◽  
Near Surface ◽  
Laser Patterning ◽  
Electroless Copper ◽  
Excimer Laser Irradiation ◽  
Laser Effect

Excimer-laser irradiation strongly modifies the near-surface region of aluminum nitride (AIN) substrates. The surface acquires a distinctive metallic appearance and the electrical resistivity of the near-surface region drastically decreases after laser irradiation. These results indicate that Al forms at the surface as a result of the decomposition of the Al (which has been confirmed by XPS). A computer model that incorporates two opposing phenomena, decomposition of the AIN that leaves a metallic Al film on the surface, and thermal evaporation of the Al, demonstrated that saturation of film thickness and, hence, of electrical resistance is reached when the rate of Al evaporation equals the rate of AIN decomposition. In an electroless copper bath, Cu is only deposited in laser-irradiated areas. This laser effect has been designated laser activation for electroless deposition. Laser activation eliminates the need of seeding for nucleating the initial layer of electroless Cu. Thus, AIN metallization can be achieved by laser patterning followed by electroless deposition.

The Origin and Implications of (111)-Textured Grains Obtained via Nucleation and Growth of Solids in Pulsed-Laser-Quenched Al Films on SiO2

2006 ◽  
Vol 979 ◽  
Author(s):  
J. B. Choi ◽  
Min H. Choi ◽  
U.-J. Chung ◽  
A. B. Limanov ◽  
James S. Im
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Heterogeneous Nucleation ◽  
Microstructural Analysis ◽  
Pulsed Laser ◽  
Nucleation And Growth ◽  
Nucleation Model ◽  
Wide Energy ◽  
Excimer Laser Irradiation ◽  
Condensed Systems

AbstractWe have investigated excimer laser irradiation of 2000-Å-thin as-deposited Al films on SiO2. Microstructural analysis of the irradiated films conducted with AFM and EBSD techniques reveals that there exists a wide energy density interval over which large equaxed grains with a strong (111) texture are obtained. Based on thermal, transformational, and microstructural considerations, we propose a heterogeneous nucleation model to account for the observed behaviors, and discuss the implication of the model on the phenomenon of heterogeneous nucleation of crystalline solids in condensed systems as regards the thermodynamic role played by the orientation of subcritical clusters.

Effect of Laser Irradiation on Carbon-Implanted Copper Substrates

1992 ◽  
Vol 242 ◽  
Author(s):  
Rajiv K. Singh ◽  
John Viatella
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Thermal Effects ◽  
Rapid Heating ◽  
Rapid Quenching ◽  
Phase Changes ◽  
Transient Temperature ◽  
Near Surface ◽  
Nanosecond Lasers ◽  
Non Equilibrium

ABSTRACTWe have analyzed the non-equilibrium thermal effects of pulsed nanosecond lasers on carbon-implanted copper substrates. The thermal effects of pulsed nanosecond lasers were simulated by numerically solving the heat flow equation and taking into account the phase changes which occur at the surface of the irradiated solid. Intense pulsed laser irradiation induces rapid heating at the near surface resulting in melting, followed by rapid quenching of the melt phase. The effect of laser variables (energy density, etc.) on the maximum melt depth, melt-in and solidification velocities and transient temperature profiles have been computed. Maximum melt depths and the surface temperatures were found to increase approximately in a linear manner with pulse energy density. Extremely high average solidification velocities (20–45 m/sec) were calculated which may give rise to solute trapping and other non-equilibrium segregation effects. The change in laser-irradiated characteristics of copper substrates as a result of carbon-ion implantation is also discussed.

Arf Laser Ablation of Yba2Cu3O7‐X as Studied by Emission Spectroscopy, Sem and Edax

1989 ◽  
Vol 169 ◽  
Author(s):  
Alon Hoffman ◽  
Rafael R. Manory
Keyword(s):  
Laser Ablation ◽  
Plasma Plume ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Surface Region ◽  
Fluorescence Emission Spectra ◽  
Near Surface ◽  
Spatially Resolved ◽  
Excimer Laser Irradiation ◽  
Beam Center

AbstractThe fluorescence emission spectra from the plasma plume induced by ArF excimer laser irradiation of YBa2Cu3O7‐x was studied and compared to the spectra of Y, YO, Cu, CuO, and YCuO under similar conditions. The only compound detected in the Y‐Ba‐Cu‐O ablated material spectra was YO. Spatially resolved measurements from the plasma plume emanating from the irradiated superconducting material were performed also as a function of distance from the surface.The effect of laser ablation on the morphology and composition of the irradiated YBa2Cu3O7‐x material was studied by SEM and EDAX. It was found that the 1‐2‐3 composition ratio of the near surface region was maintained after ablation. Changes in the morphology were observed in the track region and three distinctive regions could be identified as a function of distance from the beam center.

Impurity Activation in N+ Ion-Implanted 6H-SiC with Pulsed Laser Annealing Method

2000 ◽  
Vol 640 ◽  
Author(s):  
O. Eryu ◽  
K. Aoyama ◽  
K. Abe ◽  
K. Nakashima
Keyword(s):  
Contact Resistance ◽  
Laser Irradiation ◽  
Carrier Density ◽  
Laser Annealing ◽  
Pulsed Laser ◽  
Surface Region ◽  
Near Surface ◽  
Pulsed Laser Annealing ◽  
Annealing Method ◽  
Ion Implanted

ABSTRACTWe have succeeded in pulsed laser annealing of N+ ion-implanted n-type 6H-SiC for increasing the carrier density near surface in order to decrease contact resistance, which induces little redistribution of implanted impurities after laser irradiation. By repeated laser irradiation at low energy density, the ion–implanted impurities were electrically activated without melting the surface region. SiC substrates with impurity concentration of 2×1018 /cm3 were implanted with 30 keV N+ ions with dose of 4.7×1013/cm2. After pulsed laser annealing, a contact resistance was measured to be 5.7×10−5 Ωcm2 using Al electrode on the N+ -implanted layer.

Substrate Surface Effects on the Properties of Sputter-Deposited and Laser-Irradiated Films.

1991 ◽  
Vol 238 ◽  
Author(s):  
A. J. Pedraza ◽  
M. J. Godbole ◽  
L. Romana
Keyword(s):  
Electron Microscopy ◽  
Substrate Surface ◽  
Surface Condition ◽  
Surface Region ◽  
Film Rupture ◽  
Near Surface ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Tunnelling Microscopy ◽  
Sputter Deposited

ABSTRACTSapphire substrates, mechanically polished to an optical finish, were annealed for two days at either 1000°C or 1350°C. The near surface condition of as-polished and of the annealed substrates was analyzed by Rutherford backscattering/channeling (RBS-C) and by scanning electron microscopy/channeling (SEM-C), by transmission electron microscopy (TEM), and by scanning tunnelling microscopy (STM). The polished substrates were found to be RBS-amorphous up to 100 nm, and heavily damaged at larger depths. In agreement with these results, no electron channeling was obtained from polished samples. TEM, however, showed that the damaged region was crystalline, and the only defects detected were microtwins. Both RBS-C and SEM-C analyses revealed that the damage is removed when the sapphire substrates are annealed for 48 hrs. at 1350°C. The condition of the near-surface region, viz., as-polished or annealed, is found to strongly affect the morphology of the laser-irradiated copper films deposited on sapphire substrates. A correlation is found between the threshold for film evaporation and for film rupture upon laser irradiation, both being a function of the substrate condition. It is concluded that the near-surface damaged layer acts as a thermal barrier for heat transport across the substrate.

Formation of polytype microstructure in pulsed-laser-irradiated sapphire substrates

1995 ◽  
Vol 53 ◽  
pp. 344-345
Author(s):  
Siqi Cao ◽  
A. J. Pedraza ◽  
L. F. Allard ◽  
D. H. Lowndes
Keyword(s):  
Energy Density ◽  
Laser Irradiation ◽  
Electroless Deposition ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Surface Modifications ◽  
Near Surface ◽  
Sapphire Substrates ◽  
Hcp Structure ◽  
Pulsed Laser Irradiation

Surface modifications of wide-gap materials are produced by pulsed laser irradiation. Under given conditions, these near-surface modifications can promote adhesion enhancement of deposited thin film materials, and activation for electroless deposition. AIN decomposes during laser irradiation leaving a metallic film on the surface. High density dislocations were observed in the surface layer of AIN that was laser melted but not decomposed. The laser melted alumina becomes amorphous at a laser energy density of ~1J/cm2. In sapphire, γ-alumina is formed when the sample is laser irradiated in Ar/4%H2. Here, we report the formation of a new structure in laser-irradiated sapphire.Optically polished c-axis sapphire substrates were laser-irradiated in an Ar/4%H2 atmosphere at 4J/cm2 energy density, using a 308 nm-wavelength laser with a pulse duration of ~40 ns. Sapphire (A12O3) has a space group R 3 c and can be described as an hcp structure having oxygen and aluminum layers alternately stacking along the c-axis.

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