KQCircuits Layers

KLayout’s right panel shows a layer tree. Layers containing meaningful device geometry are grouped by faces: 1t1-face, 2b1-face and 2t1-face. By default layer numbers 0-127 are used for the bottom face of the chips and 128-255 are used for the top face, and the data type indicates the chip number (data type 0 is used for layers not belonging to chip faces). Other texts, annotations and miscellaneous things not strictly belonging to a particular face are under the texts layer group. Other layers used only for simulations are under the aptly named simulations layer group.

Most layers have self-describing names like refpoints or instance_names but others need a bit of explanation:

  • base metal gap wo grid – This is the layer most used in code. Here you place the shapes of gaps (areas without metal) in the base metal layer that is laid out on a silicon substrate.

  • ground grid avoidance – In this layer you should draw shapes that encompass everything in base metal gap wo grid plus a small margin, usually set by the margin parameter.

  • groud grid – This layer is auto generated if the “Make ground plane grid” parameter is enabled in a chip. It fills in the chip area outside of shapes in the ground grid avoidance layer with a metal grid. Technically, this layer contains the square shaped gaps in the grid, not the metal grid itself. Hidden by default.

  • base metal addition – In some cases, you want to add metal back where it is already removed by another element. This is rarely used, for example in qubits to make sure the junctions connect correctly.

  • base metal gap – This layer has the final geometry of chips in masks. This is generated automatically when the “Merge grid and other gaps into base_metal_gap layer” parameter is enabled in chips with the formula: base_metal_gap = base_metal_gap_wo_grid + ground_grid - base_metal_addition. In this layer any rounding errors in the geometry are also automatically resolved, such that elements that should touch connect without gaps. Hidden by default.

Find more details in defaults.py.