• Left panel: Hierarchy (drawn levels and the tree of placed cells), Layers, and the options of the current tool.
• Toolbar: undo / redo, the tools (Select, Stretch, Move, Copy, Rectangle, Polygon, Path, Label, Via, Instance, Chop, Ruler), fit, Zoom box, Prev view, Grid, Snap, Gravity, DRD, Constraints, Magnet, Live DRC, Flylines, and GDS to export the cell.
• Status bar: X / Y of the cursor; while a command is in progress dX, dY and Dist from its reference point; Sel: n (Sel(P): n for a partial selection); Cmd: the current tool; and a mouse L: … M: … R: … line telling what each button does now.
• Right panel: cell statistics or the inspector, Edit operations, Layer operations, and the verification sections (see Verification).

Layers

• Click a layer row to make it the active layer; new shapes are drawn on it.
• Click the eye to show or hide a layer. Click the small box left of the eye to make a layer selectable or not: shapes on non-selectable (or hidden) layers are drawn but cannot be picked, like Virtuoso’s LSW. AV / NV show / hide every layer, AS / NS make every layer selectable / not.
• Filter narrows the list by name; Instances selectable controls whether placed cells can be picked.
• Each row shows the fill pattern, the name and the GDS layer/datatype. Hover a row to see its minimum width and spacing.

Drawing

Keys act on the canvas only while the mouse is over it.

While drawing a polygon or path, Backspace removes the last point and Esc cancels.

• Gravity (on by default, G toggles) snaps the cursor to vertices (diamond marker) and edges (circle marker) of nearby shapes and instance boxes, so new geometry abuts exactly.

• DRD (design-rule-driven editing, on by default) shows the minimum-spacing halo of a rectangle being drawn and marks in red every gap to a same-layer shape that is closer than the minimum spacing, and shapes narrower than the minimum width. It works while drawing rectangles and paths, moving, copying and pasting. Neighbours inside placed cells count too (at any depth), as do the shapes around a cell edited in place; a moved or pasted instance is checked by the shapes along its outline.

• Magnet (on by default) pulls a shape being drawn or moved to exactly the minimum spacing from its neighbours when it comes close.

• Live DRC (on by default) checks the rule deck around every edit; see Live DRC.

• Layer tap: T makes the layer of the shape under the cursor the active layer.

• Changing metal while routing: with the Path tool, press + (or = / PageUp) to end the path at the cursor, drop the via to the routing layer above and continue on it; - (or PageDown) goes down.

• Polygons are Manhattan by default: each point is aligned horizontally or vertically to the previous one. Hold Shift (or Ctrl) while clicking for any angle. The closing edge gets an extra corner so a Manhattan outline stays Manhattan.

• Paths are always Manhattan. Width (nm) in the left panel sets the width; 0 uses the layer’s minimum width. Path ends are extended by half the width.

• Labels on a routing layer name the net under them (used by extraction and LVS).

• Vias come from the technology (bottom layer, cut, top layer); dragging an area fills it with as many cuts as fit.

Rectangle step by step

1. Click the metal1 row in Layers.
2. Press R and drag on the canvas.
3. Press Esc to return to Select, click the rectangle and type exact coordinates in the inspector (x0, y0, x1, y1 in µm).

Selecting and editing

Partial selection

F4 (or Edit > Toggle Partial Select) toggles partial selection. In Select, a click near an edge selects that edge (both its vertices) or a vertex; Shift+click adds or removes; a drag box selects the vertices inside it (items entirely inside are taken whole). Selected edges and vertices are highlighted and the status bar shows Sel(P): n.

Press S, click a reference point, then the destination: every selected vertex moves, and Manhattan shapes stay Manhattan (adjacent edges slide along). Dragging a partially selected shape in Select stretches it too. Esc clears the partial selection.

Forms

Each key opens a floating form and closes it again:

The Edit section of the right panel (shown when something is selected) also has:

• Flatten: replace the selected instances with their contents (one level).
• Make cell: move the selection into a new cell and place an instance of it.
• Merge: union the selected shapes per layer.
• Size with Apply: grow (positive µm) or shrink (negative) the selected shapes.
• Align (two or more items): align left, centre or right edges, bottom, centre or top edges; Space X / Space Y spread three or more items with equal gaps.

Navigation

These are the Virtuoso interaction profile, the default. With Conventional (Settings > Interaction) the wheel zooms and a right drag pans.

Bindkeys go to the canvas while the mouse is over it, and stay with it while one of its forms (q, F3, e, Shift+E) is open on top, until you click elsewhere in the window. A text field being typed in, or a focused control in a form under the mouse, gets the keys first.

Layer operations

With nothing selected, Layer operations computes Boolean results:

1. Choose layer A, an Operation (AND, OR, NOT, XOR, SIZE) and layer B (or a distance By in µm for SIZE).
2. Choose the Output layer.
3. Keep Include hierarchy (flattened) checked to include placed cells.
4. Press Run. The result shapes are added to the output layer and selected.

Boolean operations, Merge, Size and Chop handle any-angle geometry (45° and arbitrary edges, from GDS / OASIS or the polygon tool) exactly. Crossings that fall between grid points snap to the nearest database unit. When sizing, horizontal, vertical and 45° edges move by the given distance and corners of 90° or more stay sharp. Results with holes are cut into hole-free polygons.

Constraints, compaction and compare

These commands have no menu or bindkey; run them from the command palette, where they are listed as “Layout Assist: ”.

• Symmetric About Vertical / Horizontal Axis, Keep Left / Bottom Edges Aligned, Keep Centres Aligned Vertically / Horizontally and Fix In Place add a constraint to the selected items. Moving one member moves the others so the constraint keeps holding. Infer Constraints From Schematic adds symmetry constraints for the schematic’s matched devices; Remove Constraints clears them. The Constraints checkbox in the toolbar draws them, and the Constraints section of the right panel lists them, with Snap for one that no longer holds.
• Compact (Left, Then Down) and Compact Left / Right / Down / Up slide the cell’s top-level items toward one side as far as the spacing rules allow. Connected geometry and the members of a constraint move together.
• Compare With Saved and Compare With Git HEAD draw the geometry added and removed since the last save or the last commit; Next Difference steps through them.

Hierarchy

Placing a cell or an array

1. Press I. The left panel lists PCell variants and Place cell (every other cell with a layout that would not create a cycle).
2. Pick a cell, set Rotation, Mirror about x, Columns and Rows. Array elements abut at the cell’s extent.
3. Click to place.

Select an instance to edit its position, rotation and mirroring in the inspector. Check Array to turn it into an array (GDS AREF) with Columns, Rows, Column pitch and Row pitch.

Drawn depth

The levels field in Hierarchy (keys 0 to 8, and 9 for all levels) sets how many levels of placed cells are drawn with their contents (Shift+F all levels, Ctrl+F top level only). Deeper instances are drawn as labelled boxes. Missing cells are drawn in red.

Large designs stay fast: cells that are small on screen collapse to boxes and tiny shapes to dots.

The hierarchy tree (Edit > Hierarchy Tree, Shift+T) lists the cells placed in the current cell with their counts; click one to open it. Tools > Hierarchy Browser shows the whole project’s layout hierarchy with where-used lists (see Tools).

Generators and fill

The Tools menu also adds geometry to the active layout, each as one undoable step:

• Layout Generators > Guard Ring: a p+ substrate or n+ nwell ring with contacts and a metal1 strap around an area or the selection;
• Layout Generators > Via Array: via arrays on every overlap of two layers, or filling an area;
• Layout Generators > Matched Placement: common-centroid, interdigitated or 2-D common-centroid placement of matched transistors with dummies;
• Layout Generators > By Example: place the devices like a finished cell with the same circuit (matched by topology), copying its wells, implants and taps, and optionally route;
• Dummy Fill: fill squares to meet a density rule.

See Tools for the options.

PCells

Parametric cells are generated from the technology and stored as ordinary cells in the pcells library (for example nmos_w1000_l180_nf2).

Device appears when the technology is a PDK with several MOS devices of that polarity (for example low- and high-Vt variants): the PCell then draws that device’s marker layers, and the variant name ends with the device name. The default is the PDK’s first device.

To place one, press I, choose the PCell in the left panel, set its parameters and click. To change a placed PCell, select it, edit the parameters in the PCell section of the inspector and press Apply. Well and substrate taps (ntap, ptap) are created by schematic-driven layout; their parameters can be edited in the inspector the same way.

SKILL scripts

Tools > Load SKILL (.il) runs a Cadence SKILL file on the project; ics skill and the MCP tool run_skill do the same from the command line and from agents. Printed output goes to the log, every changed layout can be undone, and geGetEditCellView() returns the cell open in the editor.

The CIW tab of the bottom panel (Tools > SKILL CIW, or “CIW” in the command palette) is an interactive SKILL prompt like Virtuoso’s Command Interpreter Window. Variables, procedures and open cellviews persist between commands and include everything defined by files loaded with Tools > Load SKILL; opening another project starts a fresh session. Enter runs the line, a line with unclosed parentheses or strings continues on the next one (the prompt shows ...), and Up / Down recall earlier commands.

cv = dbOpenCellViewByType("work" "pad" "layout" "maskLayout" "w")
for(i 0 3
  dbCreateRect(cv list("metal1" "drawing") list(i*2:0 i*2+1:1)))
dbCreateInstByMasterName(cv "work" "via_cell" "layout" "I0" 0:5 "R90")
printf("%d shapes\n" length(cv~>shapes))

Supported:

• syntax: C style f(a b) and Lisp (f a b) calls, infix operators, x:y points, obj~>prop, tbl[key], 'quote, ?key arguments, ; and /* */ comments, scale factors such as 1.5u;
• control: if / then / else, when, unless, cond, case, while, for, foreach (also mapcar and tables), let, prog / return, setof, exists, errset, error;
• procedure / defun with @optional, @key, @rest, lambda, funcall, apply, mapcar, load; list, string, math and printf / sprintf built-ins, makeTable tables and disembodied property lists;
• layout: dbOpenCellViewByType ("r", "w" clears the layout, "a" appends; libraries and cells are created on demand), dbCreateRect, dbCreatePolygon, dbCreatePath, dbCreateLabel, dbCreateInst, dbCreateInstByMasterName, dbCreateSimpleMosaic, dbDeleteObject, dbMoveFig, dbCopyFig, dbFindAnyInstByName, dbGetOverlaps, dbTransformPoint / dbTransformBBox; layer Boolean operations dbLayerAnd, dbLayerOr, dbLayerXor, dbLayerAndNot (cv layer shapes1 shapes2) and dbLayerSize (cv layer shapes size), which add the result to layer and return the new shapes (any-angle geometry included); dbSave and dbClose do nothing (save the project). Shape, instance and cellview properties (bBox, points, layerName, xy, orient, shapes, instances, …) can be read, and the geometric ones set.

Coordinates are in µm. A layer is a name, list(name purpose) or a layer index; a purpose other than drawing first looks for a layer named name.purpose or name_purpose. Variables are dynamically scoped as in .il files. Not supported: schematic views, PCell definitions (pcDefinePCell), interactive hi* / le* forms and SKILL++ (.ils) lexical scoping.

GDSII

• File > Import > GDSII / OASIS… reads a GDS or OASIS file into a new library with full hierarchy.
• GDS in the toolbar or File > Export > Cell GDSII… writes the cell and every cell it places; Export > Library GDSII… writes every layout in the project. Cell OASIS… and Library OASIS… write OASIS instead.

Layers are mapped by GDS layer / datatype. Layers the technology does not have are added to it on import, so nothing is lost. A stream layer map (Tools > Stream Layer Map, or a Virtuoso layer map file) renumbers layers on export, maps other numbers onto technology layers on import, or drops them.