Transient Thermal Processing Research Articles

NDT inspection of plastered mosaics by means of transient thermography and holographic interferometry

In this research work, experimental procedures by means of Transient Thermography and Holographic Interferometry were performed in order to detect subsurface tesserae areas of plastered mosaics. A mosaic sample consisted of various types of tesserae and covered with hydraulic lime mortar was evaluated in the laboratory with various transient thermal processing techniques such as Pulsed Phase Thermography, Thermographic Signal Reconstruction and Principal Component Thermography, as well as Holographic Interferometry in both real-time and double-exposure configurations. Results from the non-invasive investigation are presented and discussed, revealing that the above approaches can obtain a seeing through investigation of plastered mosaics.

Photonic Curing Explanation and Application to Printing Copper Traces on Low Temperature Substrates

Photonic curing is a transient thin-film thermal processing technique using flashlamps. It was developed by NovaCentrix® and incorporated in the PulseForge® toolset to address the need of the printed electronics industry to process high temperature materials on low temperature substrates such as paper and plastic on a moving web. Applications include photovoltaics, displays, solid state lighting, thin film batteries, RFID tags, and printed circuits. The ability to substitute inexpensive and flexible substrates for expensive, rigid substrates while achieving similar performance can dramatically reduce the cost of the final product and enable new products. In this paper, we discuss the technology and mechanisms of the process and illustrate a case study of forming copper traces on plastic and paper in a roll-to-roll environment. Here, a low cost copper oxide ink is printed on plastic or paper and chemically reacted using pulsed light from the PulseForge tool to form highly conductive copper traces. This process is performed in an ambient atmosphere.

Integrated bake/chill system for across-wafer temperature uniformity control in photoresist processing

An integrated bake/chill thermal processing module is developed and experimentally evaluated to achieve spatial temperature uniformity of a silicon wafer throughout the entire processing temperature cycle of ramp, hold, and quench in lithography. The module uses a set of thermoelectric devices which are used to provide distributed heating and cooling to the substrate for uniformity and transient temperature control. The experimental results demonstrate that the wafer spatial temperature uniformity is within ±0.3 and ±0.1°C during transient and steady-state thermal processing, respectively.

Thermal uniformity of 12-in silicon wafer in linearly ramped-temperature transient rapid thermal processing

This paper presents a systematic method for estimating the dynamic incident-heat-flux profiles required to achieve thermal uniformity in 12-in silicon wafers during linearly ramped-temperature transient rapid thermal processing using the inverse heat-transfer method. A two-dimensional thermal model and temperature-dependent silicon wafer thermal properties are adopted in this study. The results show that thermal nonuniformities on the wafer surfaces occur during ramped increases in direct proportion to the ramp-up rate. The maximum temperature differences in the present study are 0.835/spl deg/C, 1.174/spl deg/C, and 1.516/spl deg/C, respectively, for linear 100/spl deg/C/s, 200/spl deg/C/s, and 300/spl deg/C/s ramp-up rates. Although a linear ramp-up rate of 300/spl deg/C/s was used and measurement errors did reach 3.864/spl deg/C, the surface temperature was maintained within 1.6/spl deg/C of the center of the wafer surface when the incident-heat-flux profiles were dynamically controlled according to the inverse-method approach. These thermal nonuniformities could be acceptable in rapid thermal processing systems.

High temperature annealing of GaN, InN, AlN and related alloys

Transient thermal processing is employed for implant activation, contact alloying, implant isolation and dehydrogenation during III-nitride device fabrication. We have compared use of InN and AlN powder as methods for providing a N 2 partial pressure within a graphite susceptor for high temperature annealing of GaN, InN AlN, InAlN and InGaN. The AlN powder provides adequate surface protection to temperatures of ∼ 1100°C for AlN, ≥ 1050°C for GaN, ∼ 600°C for InN and ∼ 800°C for the ternary alloys. While the InN powder provides a higher N 2 partial pressure than AlN powder, at temperatures above ∼ 750°C the evaporation of In is sufficiently high to produce condensation of In droplets on the surfaces of the annealed samples.

Optical Effects Induced by the Multilayer Nature of SOI Films During Transient Thermal Processing with a Radiant Line Heat Source.

AbstractRadiation heat transfer has been found to have the greatest Impact on the quality of the thin recrystalllzed silicon film during zone-melting recrystallizatlon (ZMR) processing. This study focused on the radiation effects during ZMR with an Infrared radiant line heat source such as a graphite strip heater. The multilayer nature of the capped sllicon-on-tnsulator (SOI) structure Induces complex optical effects which affect the temperature distribution during processing. A two dimensional numerical model of the ZMR process has been developed using a finite difference scheme. The effect of the radiant line heat source’s emission into the wafer has been modeled with a matrix method using Fresnel coefficients. A numerical parametric study was conducted to observe the effects of varying the thickness of the different layers In a capped SOI wafer on the maximum temperature and melt width attained. Results indicate that the variation of either the capping or insulating silicon oxide layer causes significant fluctuations of the reflectivity and temperature profile of the film. Increasing the thickness of the Si layer results in a nearly linear increase in temperature and melt width after complete melting. Layering schemes that are sensitive to small variations In thickness that may result in large changes in reflectivity were Identified.

Diffusion phenomena and defect generation in rapidly annealed GaAs

A detailed study of transient thermal processing of S-doped epitaxial GaAs wafers, both with and without ion-implantation damage being present, has been performed. The average diffusivity of S is given for the temperature range 950–1050 °C, and is shown to be dependent on the position of any lattice damage present, the surface condition (capped or capless), and the annealing regime employed (thermal or rapid thermal). The mobility of the S-doped region is degraded by rapid annealing, and the extent of this degradation is a function of the experimental conditions employed. Implantation of Si (which occupies a Ga site) into S-doped n+ regions (S occupies an As site) failed to increase the electrical activity of the region above the often observed limit of 2×1018 cm−3.

Comparison of Ion-Milling Techniques For Cross-Sectional TEM of Semiconductors

The use of cross-sectional Transmission Electron Microscopy (TEM) has become invaluable for the characterization of the near-surface regions of semiconductors following ion-implantation and/or transient thermal processing. A fast and reliable technique is required which produces a large thin region while preserving the original sample surface. New analytical techniques, particularly the direct imaging of dopant distributions, also require good thickness uniformity. Two methods of ion milling are commonly used, and are compared below. The older method involves milling with a single gun from each side in turn, whereas a newer method uses two guns to mill from both sides simultaneously.

Transient Thermal Processing of GaAs

ABSTRACTA comprehensive review is presented of the use of transient thermal processing for the activation of implanted dopants, the alloying of ohmic contacts, the pulse diffusion of Zn for p+ contacts, and other heat treatments of GaAs. In all cases, transient processing produces results at least as good as furnace heating, and in some instances, markedly better. The special needs of GaAs, such as encapsulation of the wafer surface, and prevention of slip and warpage are discussed, as well as recent results detailing implant damage removal processes during transient annealing.

Crystallography and Interfaces of Epitaxial Fluorite Metals and Insulators on Semiconductors

ABSTRACTCrystals with the cubic fluorite structure and small lattice mismatches can be grown epitaxially on cubic semiconductors. In this manner thin-film single-crystal metals (NiSi2 and CoSi2) and insulators (e.g. CaF2 , BaF2) have been grown on silicon, germanium and indium phosphide. With close attention to deposition and growth parameters, afforded either by atomically clean conditions or transient thermal processing, great control can be exerted over the crystallography and interfaces of these systems. This has resulted in films with unique physical properties and exceptionally high quality and reproducibility. We review the microstructure of these films in this paper and identify two important new growth regimes for these materials: very thin films (less than 30Å) and transient thermal processing with ultra-fast laser pulses. Examination of the structure of these films, using high-resolution electron microscopy, provides insight into these nucleation and growth processes. One intriguing observation is that all these fluorite structure thin films have an overwhelming tendency to grow with a 180° rotated orientation (B) on (111) semiconductors.

Laser Annealing of Ion Implanted Semiconductors

ABSTRACTPhoton energy from laser beams can be used to rapidly heat and melt localized regions of semiconductors with a high degree of spatial and temporal selectivity. Pulsed lasers have been successfully used to anneal displacement damage and to remove other defects. However, the number density of trapped defects increases with velocity of solidification and finally thin layers turn directly amorphous after laser-melt quenching. Annealing characteristics are found to be a strong function of ion implantation variables, which determine optical properties of materials. By both solid- and liquid-phase crystallization, supersaturated solid solutions can be formed. Residual defects in SPE grown layers primarily consist of dislocation loops. Device applications utilizing these transient thermal processing techniques are reviewed briefly.