One Dimension

Grid Specification - Example 1 One Dimension

line x loc = -0.002 tag = oxi
line x loc = 0 spacing = 0.25 tag = top
line x loc = 4.0 spacing=0.25
line x loc = 400.0 tag=bottom

This section specifies the vertical grid spacings and line positions. The first line is placed at a position of -20Ã… and is tagged "oxi". No spacing is given, so the spacing defaults to the larger of the distances to the two neighbor lines. Since this is the first mesh line, the spacing defaults to the distance to the next line, 20Ã…. The second line is given a spacing of 0.25um and is tagged "top". It is placed at 0.0um. The next line is at 4.0um and also given a spacing of 0.25um. Since this line and the previous line have the same spacing, a uniform mesh spacing of 0.25um applies in this interval. The final line is placed at 400.0um and tagged "bottom". This line is at the back of the wafer, and is given no spacing. The default spacing is the distance to the previous line, 396um.

region oxide xlo=oxi xhi=top
region silicon xlo=top xhi=bottom
region gas xlo=bottom xho=bottom

The previous three lines specify the regions of the structure. Oxide is placed between the top two grid lines 20Ã… thick. The rest of the device is specified to be silicon. A gas mesh is placed along the back side of the wafer.

init

The init command indicates that the described mesh should be built. The mesh will be one-dimensional since no lateral positions were specified. A gas mesh is automatically added to the top of the wafer. Since a gas mesh is specified, another gas mesh will exist on the back of the wafer. This is useful for both heat flow and point defect simulations since it allows the back side of the wafer to assume a known condition. Commands which act on the surface of the mesh (implant, etch, deposit) will not act on the back side gas mesh. All required interface meshes are built.