The layer builder button adds a layer builder object. Layer builders can be used to import GDS files and build up a layered structure consisting of patterning defined in GDS file cells as well as plane unpatterned layers. This tool allows you to easily change the ordering and thickness of each layer and translate the position of the patterning within a layer. This is an alternative to using the GDS import options to import structures that is described in the GDSII - Import and export page.
The following example shows how to set up a layer builder with a glass substrate and a silicon y-branch structure on top of the substrate which is loaded from a GDS file.
Setting up from the GUI
Add a layer builder
Set background geometry
The background geometry defines the positions and spans of the layers. Edit the layer builder and set the x span and y span to 20 um in the background geometry section. Set the z position to 0 um. You can set the z position to refer to the position of the bottom of the layered structure, the middle, or the top.
Import GDS file
Download the layer_builder_y_branch.gds file from the Associated Files section above. Click on the "Import GDS file" button and select the layer_builder_y_branch.gds file from the file browser.
Each layer builder can load data from one GDS file.
Click on the "Add" button in the layers section twice in order to add two layers, one for the substrate, and another for the y-branch structure.
Layers in the list are stacked upwards from the bottom, towards the positive z axis. This means that the layer at the top of the list will be at the bottom, and each subsequent layer in the list is stacked on top of the previous layer. You can also change the ordering of the layers by selecting the layer and using the "Up" and "Down" buttons to move the layer up or down in the list.
To rename the layers, double-click in the Layer Name column. Set the name of the first layer in the list to "substrate", and set the name of the second layer to "y-branch".
Set up layers
Layers can either be plain with no patterning, or they can include patterning loaded from a specified GDS file. In the case of this example, the substrate will have no patterning and the y-branch layer will use patterning.
Set the thickness of the substrate layer to 2 um, and set the Material to "SiO2 (Glass) - Palik". This will be the material of the substrate layer.
Set the thickness of the y-branch layer to 0.5 um. Leave the Material as "none". This will use the background index of the simulation region as the background material. Set the Layer Number setting to 1. This will use the first layer from the specified GDS file as the patterning data. Set the Pattern Material to "Si (Silicon) - Palik".
Set patterning position
To set the x and y positions of GDS pattering, you can either use the pre-set options from the drop down menu to center or align the patterning to the corners relative to the background geometry. It's also possible to specify custom (x,y) coordinates of the center of the patterning. In the "GDS pattern reference frame" section, a preview is automatically generated showing the position of the structure with respect to the background geometry.
In the case of the layer_builder_y_branch.gds file, the y-branch structure includes an offset specified in the GDS file, so we need to translate the patterning so that the y-branch structure is moved closer to the center relative to the substrate layer. Select the "Centered at custom coordinates" option from the drop down menu, and set x to -5 um and y to -10 um.
Viewing the final structure in the Objects Tree
The layer builder automatically sets up a structure group containing the objects. You can view the structures by expanding the layer builder in the Objects tree, and the structures in each layer will be grouped into structure group.
Exporting the layer information
Using the Import and Export buttons in the edit layer builder window, it's possible to export the layer information into a .lbr file from a layer builder and load it into another layer builder.
Using script commands
A layer builder can also be added and set up completely from the script. The layer_builder.lsf script file sets up the same structure using the script. Below are the relevant script commands.