scholarly journals In Situ Monitoring of III-V Processing

1998 ◽  
Vol 535 ◽  
Author(s):  
F. L. Terry
Keyword(s):  
High Performance ◽  
Electron Cyclotron Resonance ◽  
Optical Emission ◽  
High Volume ◽  
In Situ Monitoring ◽  
Ex Situ ◽  
Flat Panel Display ◽  
Endpoint Detection ◽  
Detection Schemes

AbstractFabrication of high performance III-V devices and integrated circuits depends on careful control of layer thicknesses and compositions in the as-grown epitaxial layers and in the etching of these layers. The relatively high value of compound semiconductor devices (compared with high-volume Si devices) makes the use of advanced process control (with expensive in situ sensors) potentially advantageous. Considerable attention has been given to the problems of realtime feedback control of MBE growth systems. In this paper, I will discuss experiences with use of both in situ and ex situ monitors for controlling reactive ion etching (RIE) of III-V materials. Specific examples from an electron cyclotron resonance (ECR) RIE base contact etch from an AlInAs/GalnAs HBT process will be given. The relative merits of reflection-based wafer sensors vs. process state sensors (optical emission spectroscopy and mass spectroscopy) will be discussed. The unique opportunities and problems associated with the III-V materials and required etch processes will be contrasted to implementation of advanced wafer state endpoint detection schemes in Si and flat panel display processes. Specific problems and solutions from our research which I will discuss include chamber seasoning effects on the drift of optical emission based endpoint detection schemes and signal processing techniques for accounting for this drift, modeling of the optical dielectric function of the compounds of interest vs. composition, and the effects of surface roughness on optical thickness measurements.

scholarly journals Tetrathiafulvalene: A Gate to the Mechanochemical Mechanisms of Electron Transfer Reactions

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 482
Author(s):  
Richard Chen ◽  
Mehmet Kerem Gokus ◽  
Silvina Pagola
Keyword(s):  
Mechanochemical Synthesis ◽  
Amorphous Material ◽  
In Situ Monitoring ◽  
Ex Situ ◽  
Mechanochemical Reaction ◽  
Charge Transfer Complexes ◽  
Spectroscopic Techniques ◽  
Diffusion Controlled ◽  
Mechanochemical Reactions

This report describes aspects of our previous studies of the mechanochemical synthesis of charge transfer complexes of the electron donor tetrathiafulvalene, which are relevant to the use of laboratory X-ray powder diffraction for ex situ monitoring of mechanochemical reactions toward investigating their mechanisms. In particular, the reaction of tetrathiafulvalene and chloranil was studied under neat mechanochemical conditions and liquid-assisted grinding with diethyl ether (1 μL/mg). The product in both cases is the green tetrathiafulvalene chloranil polymorph and the mechanism of the redox reaction is presumably the same. However, while the kinetic profile of the neat mechanochemical synthesis was fitted with a second-order rate law, that of the overall faster liquid-assisted grinding reaction was fitted with the Ginstling-Brounshtein 3D diffusion-controlled model. Hence, the diffusional processes and mass transfer bringing the reactants together and separating them from products must be different. Diffraction measurements sensitive to crystalline phases and amorphous material, combined with in situ monitoring by spectroscopic techniques, will ultimately afford a better understanding of mechanochemical reaction mechanisms, a hot topic in mechanochemistry.

In situ and Ex situ Applications of Spectroscopic Ellipsometry

1993 ◽  
Vol 324 ◽  
Author(s):  
John A. Woollam ◽  
Blaine Johs ◽  
William A. McGahan ◽  
Paul G. Snyder ◽  
Jeffrey Hale ◽  
...  
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Integrated Circuit ◽  
Ex Situ ◽  
Flat Panel Display ◽  
Flat Panel ◽  
Integrated Circuit Fabrication ◽  
Circuit Fabrication ◽  
Multilayer Stacks ◽  
Deposition Control

AbstractWe briefly review the optics of ellipsometry, followed by discussions of a series of example applications of the technique including single films on a substrate; multilayer stacks common to silicon integrated circuit fabrication; flat panel display materials, and in situ semiconductor growth and deposition control.

scholarly journals On the Etching Mechanism of Highly Hydrogenated SiN Films by CF4/D2 Plasma: Comparison with CF4/H2

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1535
Author(s):  
Shih-Nan Hsiao ◽  
Thi-Thuy-Nga Nguyen ◽  
Takayoshi Tsutsumi ◽  
Kenji Ishikawa ◽  
Makoto Sekine ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Etch Rate ◽  
Emission Spectra ◽  
Optical Emission ◽  
In Situ Monitoring ◽  
Photoelectron Spectra ◽  
Hydrogen Atoms ◽  
Hydrogen Dissociation ◽  
Optical Emission Spectra

With the increasing interest in dry etching of silicon nitride, utilization of hydrogen-contained fluorocarbon plasma has become one of the most important processes in manufacturing advanced semiconductor devices. The correlation between hydrogen-contained molecules from the plasmas and hydrogen atoms inside the SiN plays a crucial role in etching behavior. In this work, the influences of plasmas (CF4/D2 and CF4/H2) and substrate temperature (Ts, from −20 to 50 °C) on etch rates (ERs) of the PECVD SiN films were investigated. The etch rate performed by CF4/D2 plasma was higher than one obtained by CF4/H2 plasma at substrate temperature of 20 °C and higher. The optical emission spectra showed that the intensities of the fluorocarbon (FC), F, and Balmer emissions were stronger in the CF4/D2 plasma in comparison with CF4/H2. From X-ray photoelectron spectra, a thinner FC layer with a lower F/C ratio was found in the surface of the sample etched by the CF4/H2 plasma. The plasma density, gas phase concentration and FC thickness were not responsible for the higher etch rate in the CF4/D2 plasma. The abstraction of H inside the SiN films by deuterium and, in turn, hydrogen dissociation from Si or N molecules, supported by the results of in situ monitoring of surface structure using attenuated total reflectance-Fourier transform infrared spectroscopy, resulted in the enhanced ER in the CF4/D2 plasma case. The findings imply that the hydrogen dissociation plays an important role in the etching of PECVD-prepared SiN films when the hydrogen concentration of SiN is higher. For the films etched with the CF4/H2 at −20 °C, the increase in ER was attributed to a thinner FC layer and surface reactions. On the contrary, in the CF4/D2 case the dependence of ER on substrate temperature was the consequence of the factors which include the FC layer thickness (diffusion length) and the atomic mobility of the etchants (thermal activation reaction).

scholarly journals In-situ monitoring and ex-situ elasticity mapping of laser induced metal melting pool using ultrasound: Numerical and experimental approaches

2021 ◽  
Vol 71 ◽  
pp. 178-186
Author(s):  
Teng Yang ◽  
Yuqi Jin ◽  
Brian Squires ◽  
Tae-Youl Choi ◽  
Narendra B. Dahotre ◽  
...  
Keyword(s):  
In Situ Monitoring ◽  
Ex Situ ◽  
Melting Pool ◽  
Experimental Approaches ◽  
Metal Melting

In Situ Monitoring and Real-Time Control of Gate Hardmask Etching in High-Volume Manufacturing of ICs

2008 ◽  
Vol 155 (11) ◽  
pp. D699 ◽  
Author(s):  
Lele Chen ◽  
Weinan Jiang ◽  
Todd Pao ◽  
Bill Lin ◽  
Linda Xu ◽  
...  
Keyword(s):  
Real Time ◽  
High Volume ◽  
In Situ Monitoring ◽  
Real Time Control ◽  
Time Control

scholarly journals Linking In Situ Melt Pool Monitoring to Melt Pool Size Distributions and Internal Flaws in Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1856
Author(s):  
Claudia Schwerz ◽  
Lars Nyborg
Keyword(s):  
Near Infrared ◽  
In Situ Monitoring ◽  
Ex Situ ◽  
Process Conditions ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Melt Pool ◽  
Melt Pool Size

In situ monitoring of the melt pools in laser powder bed fusion (LPBF) has enabled the elucidation of process phenomena. There has been an increasing interest in also using melt pool monitoring to identify process anomalies and control the quality of the manufactured parts. However, a better understanding of the variability of melt pools and the relation to the incidence of internal flaws are necessary to achieve this goal. This study aims to link distributions of melt pool dimensions to internal flaws and signal characteristics obtained from melt pool monitoring. A process mapping approach is employed in the manufacturing of Hastelloy X, comprising a vast portion of the process space. Ex situ measurements of melt pool dimensions and analysis of internal flaws are correlated to the signal obtained through in situ melt pool monitoring in the visible and near-infrared spectra. It is found that the variability in melt pool dimensions is related to the presence of internal flaws, but scatter in melt pool dimensions is not detectable by the monitoring system employed in this study. The signal intensities are proportional to melt pool dimensions, and the signal is increasingly dynamic following process conditions that increase the generation of spatter.

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