Producing and Controlling Substrate Temperature Uniformity from 600°C to 1100°C in CVC Rotating Disk Reactors

1994 ◽  
Vol 363 ◽  
Author(s):  
A. I. Gurary ◽  
G. S. Tompa ◽  
R. A. Stall ◽  
W. J. Kroll ◽  
P. Zawadzki ◽  
...  
Keyword(s):  
Process Parameters ◽  
Chemical Vapor ◽  
Rotating Disk ◽  
High Yield ◽  
Temperature Uniformity ◽  
Wafer Temperature ◽  
Heating Systems ◽  
Wide Range ◽  
Rotating Disk Reactors ◽  
High Degree

AbstractRotating Disk Reactors used for Chemical Vapor Deposition have evolved into a leading manufacturing technology for several materials, including metals, compound semiconductors, oxides, silicides, and nitrides. One of the hurdles to be surmounted in bringing this technology into routine high yield manufacturing has been to produce and maintain a highly uniform temperature distribution over the deposition area. With our recent introduction of the real-time Rotating Wafer Thermal Imaging (RWTI) technique, we have made dramatic improvements in the implementation of multi-zone heating systems and producing a uniform deposition temperature. Using multi-zone heaters we have demonstrated wafer temperature uniformity of less than 2°C in the temperature range from 600°C to 1100°C for 50 mm substrates located on wafer carriers with diameters from 125 to 300 mm. The wafer temperature uniformity dependence upon process parameters such as reactor pressure, reactant flows, and wafer carrier rotation speed was investigated. We have shown that multi-zone heating systems can provide high wafer temperature uniformity over a wide range of the process parameters, whereas single zone heating can provide a high degree of wafer temperature uniformity only for a limited set of process parameters. The experimental data allowed us to establish requirements for the application of single and multi-zone heating systems in vertical MOCVD Rotating Disk Reactors.

Temperature Measurements Using In Thermocouple In The Mocvd Rotating Disk Reactors

1995 ◽  
Vol 406 ◽  
Author(s):  
A. I. Gurary ◽  
R. A. Stall
Keyword(s):  
Process Parameters ◽  
Chemical Vapor ◽  
Rotating Disk ◽  
Temperature Measurements ◽  
High Yield ◽  
Wafer Temperature ◽  
Rotating Disk Reactors ◽  
And Control ◽  
Measurement And Control ◽  
Accuracy And Repeatability

AbstractRotating Disk Reactors used for Metalorganic Chemical Vapor Deposition have evolved into a leading manufacturing technology for several materials, including nitrides, compound semiconductors, metals, and oxides. One of the major issues to be resolved in bringing this technology into routine high yield manufacturing has been precise and repeatable wafer temperature measurement and control. The conventional approach to the rotating wafer temperature measurements by a stationary thermocouple located near the rotating wafer carrier suffers from low accuracy and repeatability. We have implemented a rotating thermocouple with a junction located close to the wafer for the temperature measurements in the MOCVD Rotating Disk Reactor. This approach allowed us to obtain reliable and accurate wafer temperature measurements with minimum dependence upon variable process parameters and to protect the thermocouple from degradation in the aggressive reactor environment. The temperature difference between wafer and thermocouple for the rotating and stationary thermocouple designs as a function of process parameters will be discussed.

A New Flexible Rapid Thermal Processing System

1995 ◽  
Vol 389 ◽  
Author(s):  
K. C. Saraswat ◽  
Y. Chen ◽  
L. Degertekin ◽  
B. T. Khuri-Yakub
Keyword(s):  
Control System ◽  
Real Time ◽  
Processing System ◽  
Process Conditions ◽  
Temperature Uniformity ◽  
Real Time Control ◽  
Wafer Temperature ◽  
Time Control ◽  
Wide Range ◽  
Optical Flux

ABSTRACTA highly flexible Rapid Thermal Multiprocessing (RTM) reactor is described. This flexibility is the result of several new innovations: a lamp system, an acoustic thermometer and a real-time control system. The new lamp has been optimally designed through the use of a “virtual reactor” methodology to obtain the best possible wafer temperature uniformity. It consists of multiple concentric rings composed of light bulbs with horizontal filaments. Each ring is independently and dynamically controlled providing better control over the spatial and temporal optical flux profile resulting in excellent temperature uniformity over a wide range of process conditions. An acoustic thermometer non-invasively allows complete wafer temperature tomography under all process conditions - a critically important measurement never obtained before. For real-time equipment and process control a model based multivariable control system has been developed. Extensive integration of computers and related technology for specification, communication, execution, monitoring, control, and diagnosis demonstrates the programmability of the RTM.

Development and Implementation of Large Area, Economical Rotating Disk Reactor Technology for Metalorganic Chemical Vapor Deposition

1993 ◽  
Vol 335 ◽  
Author(s):  
G. S. Tompa ◽  
P. A. Zawadzki ◽  
M. Mckee ◽  
E. Wolak ◽  
K. Moy ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Rotating Disk ◽  
High Yield ◽  
Thermal Dynamics ◽  
Material Systems ◽  
Rotating Disk Reactor ◽  
Metalorganic Chemical

AbstractThe vertical, high speed, rotating disk reactor (RDR) has, in recent years, found broad application in the Metalorganic Chemical Vapor Deposition of a variety of material systems. These applications include epitaxial films of III-V and II-VI compound semiconductors, oxides (such as YBCO superconductors/ferroelectrics and SiO2, amongst others), Group IV materials (such as diamond and SiC), and metals (such as copper and tungsten). As production of these material systems increases, so too does the need for economical, high yield equipment capable of producing these materials with high levels of uniformity and repeatability. We have used computational fluid dynamic modeling to investigate the complex flow and thermal dynamics required for scaling existing RDRs (as large as a 7.25″ diameter disk handling up to 3×3″ wafers) to larger dimensions (11″ and 12″ diameter disks for multiple 4″ and 15.5″ diameter disk for 3×6″ wafers). The scaling parameters predicted by the modeling codes are reviewed and correlate well with experimental results. Materials results on GaAs films using TBAs, TMGa, and TMA1 for the 11″ diameter system routinely demonstrate within wafer thickness uniformities of <1.1% for 3×4″ wafers, as well as for 6″ or 8″ diameters, wafer to wafer uniformities <1% and run to run repeatabilities within 1%. These results are verified by SEM analysis, as well as with GaAs/AJGaAs Bragg reflectors. The excellent results on the 11″ and 15.5″ diameter platters combined with modeling indicated that 4×4″ wafers on a 12″ diameter platter would produce ideal films which, indeed, is the case. The 11″ diameter results have been surpassed, demonstrating <0.9% for >9″ diameters (4×4″ wafers) on a 12″ diameter susceptor. With high reactant efficiencies (>3 6%), short cycle times between growths using the loadlock, and minimal maintenance requirements, the costs per wafer in a cost of ownership model are found to be dramatically less than in competitive technologies.

Investigation of the wafer temperature uniformity in an omvpe vertical rotating disk reactor

1995 ◽  
Vol 24 (11) ◽  
pp. 1637-1640 ◽  
Author(s):  
A. I. Gurary ◽  
A. G. Thompson ◽  
R. A. Stall ◽  
W. J. Kroll ◽  
N. E. Schumaker
Keyword(s):  
Rotating Disk ◽  
Temperature Uniformity ◽  
Wafer Temperature ◽  
Rotating Disk Reactor

New Technology and Developments in Compound Semiconductor Vertical RDR-MOCVD Growth Systems

1994 ◽  
Vol 340 ◽  
Author(s):  
M. McKee ◽  
G.S. Tompa ◽  
P.A. Zawadzki ◽  
A. Thompson ◽  
A. Gurary ◽  
...  
Keyword(s):  
New Technology ◽  
Chemical Vapor ◽  
Rotating Disk ◽  
Easy Access ◽  
Organic Chemical ◽  
Optimum Process ◽  
Process Conditions ◽  
Monitoring And Control ◽  
Large Area ◽  
Wide Range

ABSTRACTCompound semiconductors are at the heart of todays advanced digital and optoelectronic devices. As device production levels increase, so too does the need for high throughput deposition systems. The vertical rotating disk reactor (RDR) has been scaled to dimensions allowing metal organic chemical vapor deposition (MOCVD) on multiple substrates located on a 300 mm diameter platter. This symetric large area reactor affords easy access over a wide range of angles for optical monitoring and control of the growth process. The RDR can be numerically modeled in a straightforward manner, and we have derived scaling rules allowing the prediction of optimum process conditions for larger reactor sizes. The material results give excellent agreement with the modeling, demonstrating GaAs/AlAs structures with <±0.9% thickness uniformities on up to 17-50mm or 4-100mm GaAs substrates. Process issues related to reactor scaling are reviewed. With high reactant efficiencies and short cycle times between growths, through the use of a vacuum loadlock, the costs per wafer are found to be dramatically less than in alternative process reactors. The high reactant utilization, in combination with a dedicated and highly efficient exhaust scrubbing system, minimizes the systems environmental impact.

A New Flexible Rapid Thermal Processing System

1995 ◽  
Vol 387 ◽  
Author(s):  
K. C. Saraswat ◽  
Y. Chen ◽  
L. Degertekin ◽  
B. T. Khuri-Yakub
Keyword(s):  
Control System ◽  
Real Time ◽  
Processing System ◽  
Process Conditions ◽  
Temperature Uniformity ◽  
Real Time Control ◽  
Wafer Temperature ◽  
Time Control ◽  
Wide Range ◽  
Optical Flux

AbstractA highly flexible Rapid Thermal Multiprocessing (RTM) reactor is described. This flexibility is the result of several new innovations: a lamp system, an acoustic thermometer and a real-time control system. The new lamp has been optimally designed through the use of a “virtual reactor” methodology to obtain the best possible wafer temperature uniformity. It consists of multiple concentric rings composed of light bulbs with horizontal filaments. Each ring is independently and dynamically controlled providing better control over the spatial and temporal optical flux profile resulting in excellent temperature uniformity over a wide range of process conditions. An acoustic thermometer non-invasively allows complete wafer temperature tomography under all process conditions - a critically important measurement never obtained before. For real-time equipment and process control a model based multivariable control system has been developed. Extensive integration of computers and related technology for specification, communication, execution, monitoring, control, and diagnosis demonstrates the programmability of the RTM.

Structural and electronic properties of defects in semiconductors

1995 ◽  
Vol 53 ◽  
pp. 4-5
Author(s):  
J.L. Batstone
Keyword(s):  
Semiconductor Device ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Extended Defects ◽  
Transmission Electron ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Metal Organic ◽  
Film Substrate

The development of growth techniques such as metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy during the last fifteen years has resulted in the growth of high quality epitaxial semiconductor thin films for the semiconductor device industry. The III-V and II-VI semiconductors exhibit a wide range of fundamental band gap energies, enabling the fabrication of sophisticated optoelectronic devices such as lasers and electroluminescent displays. However, the radiative efficiency of such devices is strongly affected by the presence of optically and electrically active defects within the epitaxial layer; thus an understanding of factors influencing the defect densities is required.Extended defects such as dislocations, twins, stacking faults and grain boundaries can occur during epitaxial growth to relieve the misfit strain that builds up. Such defects can nucleate either at surfaces or thin film/substrate interfaces and the growth and nucleation events can be determined by in situ transmission electron microscopy (TEM).

Understanding Conformational Entropy in Small Molecules

2020 ◽  
Author(s):  
Lucian Chan ◽  
Garrett Morris ◽  
Geoffrey Hutchison
Keyword(s):  
Small Molecules ◽  
Degrees Of Freedom ◽  
Absolute Error ◽  
Low Energy ◽  
Standard Entropy ◽  
Free Energies ◽  
Conformational Entropy ◽  
Wide Range ◽  
High Degree ◽  
Empirical Corrections

The calculation of the entropy of flexible molecules can be challenging, since the number of possible conformers grows exponentially with molecule size and many low-energy conformers may be thermally accessible. Different methods have been proposed to approximate the contribution of conformational entropy to the molecular standard entropy, including performing thermochemistry calculations with all possible stable conformations, and developing empirical corrections from experimental data. We have performed conformer sampling on over 120,000 small molecules generating some 12 million conformers, to develop models to predict conformational entropy across a wide range of molecules. Using insight into the nature of conformational disorder, our cross-validated physically-motivated statistical model can outperform common machine learning and deep learning methods, with a mean absolute error ≈4.8 J/mol•K, or under 0.4 kcal/mol at 300 K. Beyond predicting molecular entropies and free energies, the model implies a high degree of correlation between torsions in most molecules, often as- sumed to be independent. While individual dihedral rotations may have low energetic barriers, the shape and chemical functionality of most molecules necessarily correlate their torsional degrees of freedom, and hence restrict the number of low-energy conformations immensely. Our simple models capture these correlations, and advance our understanding of small molecule conformational entropy.

Facile Synthesis of a Diverse Library of Mono-3-substituted β-Cyclodextrin Analogues

2018 ◽  
Author(s):  
Kathryn Kellett ◽  
Brendan M. Duggan ◽  
Michael Gilson
Keyword(s):  
High Yield ◽  
Facile Synthesis ◽  
Wide Range

We have described simple, high-yield, protocols, which require only commonly accessible equipment, to synthesize a wide range of β-CD derivatives mono-substituted at the secondary face. These derivatives may be useful in their own right, and they are also scaffolds for further modification, and examples of the far broader array of derivatives that may be accessed by these procedures.

Cerebellotrigeminal Dermal Dysplasia (Gómez-López-Hernández Syndrome)

2018 ◽  
Vol 16 (05) ◽  
pp. 362-368 ◽  
Author(s):  
Federica Sullo ◽  
Agata Polizzi ◽  
Stefano Catanzaro ◽  
Selene Mantegna ◽  
Francesco Lacarrubba ◽  
...  
Keyword(s):  
De Novo ◽  
Chromosomal Rearrangements ◽  
Number Of Patients ◽  
Wide Range ◽  
Visual Problems ◽  
Neurodevelopmental Abnormalities ◽  
Clinical Triad ◽  
High Degree ◽  
Motor Handicap

Cerebellotrigeminal dermal (CTD) dysplasia is a rare neurocutaneous disorder characterized by a triad of symptoms: bilateral parieto-occipital alopecia, facial anesthesia in the trigeminal area, and rhombencephalosynapsis (RES), confirmed by cranial magnetic resonance imaging. CTD dysplasia is also known as Gómez-López-Hernández syndrome. So far, only 35 cases have been described with varying symptomatology. The etiology remains unknown. Either spontaneous dominant mutations or de novo chromosomal rearrangements have been proposed as possible explanations. In addition to its clinical triad of RES, parietal alopecia, and trigeminal anesthesia, CTD dysplasia is associated with a wide range of phenotypic and neurodevelopmental abnormalities.Treatment is symptomatic and includes physical rehabilitation, special education, dental care, and ocular protection against self-induced corneal trauma that causes ulcers and, later, corneal opacification. The prognosis is correlated to the mental development, motor handicap, corneal–facial anesthesia, and visual problems. Follow-up on a large number of patients with CTD dysplasia has never been reported and experience is limited to few cases to date. High degree of suspicion in a child presenting with characteristic alopecia and RES has a great importance in diagnosis of this syndrome.

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