Feature length-scale modeling of LPCVD and PECVD MEMS fabrication processes

Musson, Lawrence; Ho, Pauline; Plimpton, Steven J.; Schmidt, Rodney C.

doi:10.1007/s00542-005-0011-0

Cited by 7 publications

(3 citation statements)

References 10 publications

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“…For accurately modeling the material layer interfaces within the thin-film a-Si solar cells considered in this work, we employ the topology simulator ChISELS that is based on a BTRM coupled in an iterative fashion with a level-set method (Musson et al, 2005). The BTRM facilitates low-pressure deposition and etch processes to be modeled on micron-scale patterned substrates (Cale and Mahadev, 1996;Cale, 1991).…”

Section: Level-set Based Topology Simulationmentioning

confidence: 99%

Back-reflector design in thin-film silicon solar cells by rigorous 3D light propagation modeling

Blome

McPeak²,

Burger³

et al. 2014

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

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Purpose -The purpose of this paper is to find an optimized thin-film amorphous silicon solar cell design by numerically optimizing the light trapping efficiency of a pyramid-structured back-reflector using a frequency-domain finite element Maxwell solver. For this purpose short circuit current densities and absorption spectra within the investigated solar cell model are systematically analyzed. Furthermore, the authors employ a topology simulation method to accurately predict the material layer interfaces within the investigated solar cell model. The method simulates the chemical vapor deposition (CVD) process that is typically used to fabricate thin-film solar cells by combining a ballistic transport and reaction model (BTRM) with a level-set method in an iterative approach. Predicted solar cell models are far more realistic compared to solar cell models created assuming conformal material growth. The purpose of the topology simulation method is to increase the accuracy of thin-film solar cell models in order to facilitate highly accurate simulation results in solar cell design optimizations. Design/methodology/approach -The authors perform numeric optimizations using a frequency domain finite element Maxwell solver. Topology simulations are carried out using a BTRM combined with a level-set method in an iterative fashion. Findings -The simulation results reveal that the employed pyramid structured back-reflectors effectively increase the light path in the absorber mainly by exciting photonic waveguide modes. In using the optimization approach, the authors have identified solar cell models with cell periodicities around 480 nm and pyramid base widths around 450 nm to yield the highest short circuit current densities. Compared to equivalent solar cell models with flat back-reflectors, computed short circuit current densities are significantly increased. Furthermore, the paper finds that the solar cell models computed using the topology simulation approach represent a far more realistic approximation to a real solar cell stack compared to solar cell models computed by a conformal material growth assumption.Research limitations/implications -So far in the topology simulation approach the authors assume CVD as the material deposition process for all material layers. However, during the fabrication process sputtering (i.e. physical vapor deposition) will be employed for the Al:ZnO and ITO layers.The current issue and full text archive of this journal is available atThe research presented here is the result of a multi-disciplinary, collaborative project headed by K.M. McPeak (OMEL, ETH Zü rich). Special thanks go to Larry C. Musson from Sandia National Laboratories for helping with the topology simulations. In addition to the authors of this paper, the project relies on the work and contributions of: T.S. Cale (Process Evolution Ltd.), N. Wyrsch (EPFL, Lausanne) and M. Hojeij, Y. Ekinci (Paul Scherrer Institut). Furthermore the authors acknowledge funding by the DFG Research Center Matheon in the context of project D2...

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Section: Level-set Based Topology Simulationmentioning

confidence: 99%

Back-reflector design in thin-film silicon solar cells by rigorous 3D light propagation modeling

Blome

McPeak²,

Burger³

et al. 2014

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

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“…Whereas the method remains substantially a level-set method, fix-ups to the level-set function are made to help alleviate some of the inaccuracies in it; viz., it alleviates inaccuracies in integrating the first-order wave equation, which models the evolution of the level-set function, and those due to the construction of the so-called extension velocity field in Equation 1. The following discussion assumes knowledge of the level-set method and how it is employed in ChISELS; details are available in [6].…”

Section: Methods Onementioning

confidence: 99%

“…When modeling MEMS fabrication processes by the method described in [6], the surface must be rendered for the transport calculations. This is done by representing the surface by elements as a contiguous set of line segments or triangular patches.…”

Section: Methods Onementioning

confidence: 99%

LDRD final report : on the development of hybrid level-set/particle methods for modeling surface evolution during feature-scale etching and deposition processes.

McBride¹,

Schmidt²,

Musson³

2005

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Two methods for creating a hybrid level-set (LS) / particle method for modeling surface evolution during feature-scale etching and deposition processes are developed and tested. The first method supplements the LS method by introducing Lagrangian marker points in regions of high curvature. Once both the particle set and the LS function are advanced in time, minimization of certain objective functions adjusts the LS function so that its zero contour is in closer alignment with the particle locations. It was found that the objective-minimization problem was unexpectedly difficult to solve, and even when a solution could be found, the acquisition of it proved more costly than simply expanding the basis set of the LS function. The second method explored is a novel explicit marker-particle method that we have named the grid point 3 particle (GPP) approach. Although not a LS method, the GPP approach has strong procedural similarities to certain aspects of the LS approach. A key aspect of the method is a surface rediscretization procedure-applied at each time step and based on a global background mesh-that maintains a representation of the surface while naturally adding and subtracting surface discretization points as the surface evolves in time. This method was coded in 2-D, and tested on a variety of surface evolution problems by using it in the ChISELS computer code. Results shown for 2-D problems illustrate the effectiveness of the method and highlight some notable advantages in accuracy over the LS method. Generalizing the method to 3D is discussed but not implemented.4

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Simulation of Chemical Vapor Deposition Processes

Kleijn

Cavallotti

2012

Characterization of Materials

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Chemical vapor deposition (CVD) is probably the most used technology for the growth of high quality thin solid films. It is in fact widely used in the electronic and optoelectronic industry to deposit semiconducting, conducting, and insulating films as well as in the mechanical industry to grow anticorrosion and antiwear coatings on tools and equipment. The success of CVD is determined by its capability to couple reasonably high deposition rates while maintaining high‐level structural and morphological properties of the grown material. The success of CVD processes as well as the continuous increase of deposition rates and of the range of materials that can be grown through this technique relies in part on the availability of powerful modeling tools that simulate the growth process. In the present article, the status of the art of modeling CVD processes is reviewed. Particular emphasis is placed on the multiscale nature of this theoretical field, which encompasses phenomena with characteristic length scales that go from 10–10 to 100 m. In this light, advantages and disadvantages related to the use of modeling tools apt to treat specific length and time scales phenomena relevant to CVD are reviewed and discussed.

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Feature length-scale modeling of LPCVD and PECVD MEMS fabrication processes

Cited by 7 publications

References 10 publications

Back-reflector design in thin-film silicon solar cells by rigorous 3D light propagation modeling

Back-reflector design in thin-film silicon solar cells by rigorous 3D light propagation modeling

LDRD final report : on the development of hybrid level-set/particle methods for modeling surface evolution during feature-scale etching and deposition processes.

Simulation of Chemical Vapor Deposition Processes

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