This paper reviews the physical and chemical principles of plasma-assisted chemical vapor deposition (CVD) technique for thin films. We focus on the integration, process, and reliability requirements for dielectric films used for isolation, passivation, barrier, and antireflective-coating applications in ultra-large-scale integrated (ULSI) semiconductor circuits.

PECVD --- Dielectric films --- ULSI circuits --- Microelectronics production

In this investigation, the anisotropic extent of HAZ in laser grooving of fiber-reinforced plastic was studied by constructing an analytical model then comparing results obtained with the experimental. A principle of three main components of anisotropic thermal conductivity was considered, and then the equation governing thermal conduction process was transformed to a form similar to that of isotropic material. An analysis, based on a three-dimensional anisotropic thermal conductivity and a moving heat source, was presented to predict HAZ extent in laser grooving of fiber-reinforced plastic. This analysis included prediction of HAZ extent when grooving is parallel to the principal axes and when it is off-axes. The HAZ extent was determined depending on temperature difference relative to matrix combustion or char temperature. With respect to survey of previous works, this investigation is a novel attempt to analyze the extent of HAZ in FRP grooving by a CW CO2 laser.

CW CO2 laser --- Laser cutting --- HAZ --- Fiber-reinforced plastics

In this work, results of a mathematical analysis of the role of workpiece preheating in laser keyhole welding were presented. This analysis considered the steady-state welding as well as certain range of boundary conditions over which preheating effect would be indicated. This work is an attempt to interpret the role of preheating to increase welding depth and perform keyhole welding with high quality using physical and thermal properties of steel alloys.

Preheating effect --- Keyhole welding --- Laser welding --- Low-carbon steel

In this work, the effect of self-absorption by molecules of the active medium on the output laser power of a low-pressure CW CO2 laser was studied. The effects of discharge current, output coupling and total gas pressure on the output laser power were discussed. It was explained that the self-absorption depends on CO2 concentration, output coupling and discharge current and there is a threshold value for both output coupling and discharge current at which the absorption is clearly effective.

Co2 laser --- CW lasers --- Self-absorption --- Output coupling