8.20 Ssspd_chapter 6_part 7_introduction to athena_process simulator  (Page 2/5)

In Athena we are doing physically based simulation.The Value Of Physically-Based Simulation:

Physically-based process simulators predict the structures that result from specified process sequences. This is done by solving systems of equations that describe the physics and chemistry of semiconductor processes.

Physically-based simulation provides three major advantages: it is predictive, it provides insight, and it captures theoretical knowledge in a way that makes this knowledge available to non-experts.

Physically-based simulation is different from empirical modeling. The goal of empirical modeling is to obtain analytic formulae that approximate existing data with accuracy and minimum complexity. Empirical models provide efficient approximation and interpolation. Empirical models, however, doesn’t provide insight, predictive capabilities, or capture theoretical knowledge. Physically-based simulation is an alternative to experiments as a source of data. Empirical modeling can provide compact representations of data from either source.

Physically-based simulation has become very important for two reasons. One, it’s almost always much quicker and cheaper than performing experiments. Two, it provides information that is difficult or impossible to measure.

Physically-based simulation has two drawbacks: you must incorporate all the relevant physics and chemistry into a simulator and numerical procedures, and you must be implement them to solve the associated equations. But these tasks have been taken care of for ATHENA users.

Physically-based process simulation tools users must specify the problem to be simulated. ATHENA users specify the problem by defining the following:

• The initial geometry of the structure to be simulated. • The sequence of process steps (e.g., implantation, etching, diffusion, exposure) that are to be simulated.• The physical models to be used.

7.7.1: Using ATHENA with other SILVACO Software

ATHENA is normally used in conjunction with the VWF INTERACTIVE TOOLS. These tools include DECKBUILD, TONYPLOT, DEVEDIT, MASKVIEWS and OPTIMIZER. DECKBUILD provides an interactive run time environment. TONYPLOT supplies scientific visualization capabilities. DEVEDIT is an interactive tool for structure and mesh specification and refinement, and MASKVIEWS is an IC Layout Editor. The OPTIMIZER supports black box optimization across multiple simulators.

ATHENA is also frequently used in conjunction with the ATLAS device simulator. ATHENA predicts the physical structures that result from processing. These physical structures are used as input by ATLAS, which then predicts the electrical characteristics associated with specified bias conditions. Using ATHENA and ATLAS makes it easy to determine the impact of process parameters on device characteristics.

7.7.1. Getting started with ATHENA.

To start ATHENA under DECKBUILD in interactive mode, enter the following UNIX command:

deckbuild -an

After a short delay, the Main Deckbuild Window will appear. The lower text window of this window will contain the ATHENA logo and version number, a list of available modules, and a command prompt. ATHENA is now ready to run. To become familiar with the mechanics of running ATHENA under DECKBUILD, load and run some of the ATHENA standard examples.