The box command button allows creation of boxes (rectangles) on the currently selected layer. The box can be defined by either clicking button 1 on two diagonal corners, or by pressing button 1 to define the first corner, dragging, then releasing button 1 to define the second corner. The outline of the box is ghost-drawn during creation. The new box will be merged with or clipped to existing boxes on the same layer.
While the command is active in physical mode, the cursor will snap to horizontal or vertical edges of existing objects in the layout if the edge is on-grid, when within two pixels. When snapped, a small dotted highlight box is displayed. This makes it much easier to create abutting objects when the grid snap spacing is very fine compared with the display scaling. This feature can be disabled by setting the NoSnapToEdges variable.
In physical mode, if an electrical specification exists for the current layer, as set in the technology file (see 11.1.1) the electrical parameters for the box being created can be printed by holding the Shift key while releasing or clicking mouse button 1, whichever would complete the box. In this case, the box is not created, but the electrical parameters for the box are displayed. This allows the dimensions of the box to be fine-tuned before actual creation. An electrical specification for the layer provides computation of resistance, capacitance, or transmission line parameters for boxes on the layer. See 11.1.1 for more information.
In physical mode while the box command is active, holding down the Ctrl key while clicking on a subcell will paint the area of the subcell with the current layer.
In electrical mode, the box command is available by selecting the box function in the shapes menu. On layers other than the SCED layer, the box is rendered with a dotted border and no fill. On the SCED layer, the fill attribute associated with the layer is used. If a fill or solid border is desired on an upper layer, a polygon should be used rather than a box. Boxes have no electrical significance, but can be used for illustrative purposes.