Hints, Tips and Solutions – November 2003

Q. Is there a way to automatically specify mesh spacing in ATHENA?

A. Yes, there are three ways to automatically specify grid spacing. The most preferred method is described below and could best be described as “semi-automatic”. The other methods not described below utilize the MaskViews/ATHENA interface and the adaptive meshing feature respectively.

The method described below is much preferred as it leaves the user in complete control of the mesh. If this simple procedure is followed correctly, mesh related problems are much less likely to occur.

I. Introduction

(i) Mesh in the X-Direction

When deciding on the placement of mesh points in the X direction, it is important to ensure that a defined mesh point is placed at every etched edge or deposited edge in the final structure.

If there is a vertical edge in the structure in a location without a corresponding mesh point, the meshing algorithum then has to re-arrange the mesh to ensure that one exists. During the re-arrangement process, X-mesh points near the effected surface may have to be removed to create the new mesh. Usually this is fine if it happens only once or twice, but if it happens repeatedly, the user is no longer in control of the mesh locations in the X-direction.

The meshing algorithum does not know in advance, what the next process step is going to be. Thus the automated re-meshing algorithum may remove X-mesh points that it will require for a later process step, necessatating further automated mesh re-generation. Eventually, if this situation happens repeatedly, the mesh becomes dis-ordered and structural problems become more likely.