PYXS File Reference#

This document details the functions available in PYXS scripts. An introduction is available as a separate document: Writing PYXS files - an Introduction.

In PYXS scripts, there are basically three kind of functions and methods:

  • Standalone functions which don’t require an object. For example input() and deposit().

  • Methods on original layout layers (and in some weaker sense on material data objects), i.e. invert() or not_().

  • Methods on mask data objects, i.e. grow() and etch().


The following standalone functions are available:




Return a pseudo-mask, covering the whole wafer


Configure the lower height of the processing window for
backside processing (see below)


Return a pseudo-material describing the wafer body


Configure the accuracy parameter (see below())

Deposit material as a uniform sheet. Equivalent to
all().grow(...). Return a material data object


Configure the depth of the processing window or the wafer
thickness for backside processing (see below)


Uniform etching. Equivalent to all.etch(...)


Configure the computation margin (see below)


Start or end backside processing


Configure the height of the processing window (see below)


Fetche an input layer from the original layout. Return a
layer data object.


Configure a .lyp layer properties file to be used on the
cross-section layout


Designate the layout_data object as a litho pattern (mask).
This is the starting point for structured grow or etch
operations. Return a mask data object.

output(layer_spec, material)

Output a material object to the output layout



all() method#

This method delivers a mask data object which covers the whole wafer. It’s used as seed for the global etch and grow function only.

below(), depth() and height() methods#

The material operations a performed in a limited processing window, which extends a certain height over the wafer top surface (height), covers the wafer with a certain depth (depth) and extends below the wafer for backside processing (below parameter). Material cannot grow outside the space above or below the wafer. Etching cannot happen deeper than depth. For backside processing, depth also defines the wafer thickness.

The parameters can be modified with the respective functions. All functions accept a value in micrometer units. The default value is 2 micrometers.

bulk() method#

This methods returns a material data object which represents the wafer at it’s initial state. This object can be used to represent the unmodified wafer substrate and can be target of etch operations. Every call of bulk() will return a fresh object, so the object needs to be stored in a variable for later use:

substrate = bulk()
mask(layer).etch(0.5, into='substrate')
output("1/0", substrate)

delta() method#

Due to limitations of the underlying processor which cannot handle infinitely thin polygons, there is an accuracy limit for the creation or modification or geometrical regions. The delta parameter will basically determine that accuracy level and in some cases, for example the sheet thickness will only be accurate to that level. In addition, healing or small gaps and slivers during the processing uses the delta value as a dimension threshold, so shapes or gaps smaller than that value cannot be produced.

The default value of delta is 10 database units. To modify the value, call the delta() function with the desired delta value in micrometer units. The minimum value recommended is 2 database unit. That implies that the accuracy can be increased by using a smaller database unit for the input layout.

deposit() (grow(), diffuse()) methods#

This function will deposit material uniformly. grow() and diffuse() are just synonyms. It is equivalent to all.grow(...). For a description of the parameters see the grow() method on the mask data object.

The deposit() function will return a material object representing the deposited material.

etch() method#

This function will perform a uniform etch and is equivalent to all().etch(...). For a description of the parameter see the “etch()” function on the mask data object.

extend() method#

To reduce the likelihood of missing important features, the cross section script will sample the layout in a window around the cut line. The dimensions of that window are controlled by the extend parameter. The window extends the specified value to the left, the right, the start and end of the cut line.

The default value is 2 micrometers. To catch all relevant input data in cases where positive sizing values larger than the extend parameter are used, increase the extend value by calling extend(e) with the desired value in micrometer units.

In addition, the extend parameter determines the extension of an invisible part left and right of the cross section, which is included in the processing to reduce border effects. If deposition or etching happens with dimensions bigger than the extend value, artifacts start to appear at the borders of the simulation window. The extend value can then be increased to hide these effects.

flip() method#

This function will start backside processing. After this function, modifications will be applied on the back side of the wafer. Calling flip() again, will continue processing on the front side.

layer() method#

The layer method fetches a layout layer and prepares a layout data object for further processing. The layer() function expects a single string parameter which encodes the source of the layout data.

The function understands the following variants:

  • layer("17"): Layer 17, datatype 0

  • layer("17/6"): Layer 17, datatype 6

  • layer("METAL1"): layer “METAL1” for formats that support named layers (DXF, CIF)

  • layer("METAL1 (17/0)"): hybrid specification for GDS (layer 17, datatype 0) and “METAL1” for named-layer formats like DXF and CIF.

layers_file() method#

This function specifies a layer properties file which will be loaded when the cross section has been generated. This file specifies colors, fill pattern and other parameters of the display:


mask() method#

The mask() function designates the given layout data object as a litho mask. It returns a mask data object which is the starting point for further etch() or grow() operations:

l1 = layer("1/0")
metal = mask(l1).grow(0.3)
output("1/0", metal)

output() method#

The output() function will write the given material to the output layout. The function expects two parameters: an output layer specification and a material object:

output("1/0", metal)

The layer specifications follow the same rules than for the layer() function described above.

planarize() method#

The planarize() function removes material of the given kind (into argument) down to a certain level. The level can be determined numerically or by a stop layer.

The function takes a couple of keyword parameters in the Python notation (name=value), for example:

planarize(downto=substrate, into=metal)
planarize(less=0.5, into=[metal, substrate])

The keyword parameters are:




(mandatory) A single material or an array or materials. The
planarization will remove these materials selectively.


Value is a material. Planarization stops at the topmost point
of that material. Cannot be used together with less or to.


Value is a micrometer distance. Planarization will remove a
horizontal alice of the given material, stopping less
micrometers measured from the topmost point of that material
before the planarization. Cannot be used together with downto
or to.


Value is micrometer z value. Planarization stops when reaching
that value. The z value is measured from the initial wafer
surface. Cannot be used together with downto or less.

Methods on original layout layers or material data objects#

The following methods are available for these objects:



size(s) or size(x, y)

Isotropic or anisotropic sizing

sized(s) or sized(x, y)

Out-of-place version of size()


Invert a layer


Out-of-place version of invert()


Boolean OR (merging) with another layer


Boolean AND (intersection) with another layer


Boolean XOR (symmetric difference) with another layer


Boolean NOT (difference) with another layer

size() method#

This method will apply a bias to the layout data. A bias is applied by shifting the edges to the outside (for positive bias) or the inside (for negative bias) of the figure.

Applying a bias will increase or reduce the dimension of a figure by twice the value.

Two versions are available: isotropic or anisotropic sizing. The first version takes one single value in micrometer units and applies this value in x and y direction. The second version takes two values for x and y direction.

The size() method will modify the layer object (in-place). A non-modifying version (out-of-place) is sized().

l1 = layer("1/0")
metal = mask(l1).grow(0.3)

sized() method#

Same as size(), but returns a new layout data object rather than modifying it:

l1 = layer("1/0")
l1_sized = l1.sized(0.3)
metal = mask(l1_sized).grow(0.3)
# l1 can still be used in the original form

invert() method#

Inverts a layer (creates layout where nothing is drawn and vice versa). This method modifies the layout data object (in-place):

l1 = layer("1/0")
metal = mask(l1).grow(0.3)

A non-modifying version (out-of-place) is inverted().

inverted() method#

Returns a new layout data object representing the inverted source layout:

l1 = layer("1/0")
l1_inv = l1.inverted()
metal = mask(l1_inv).grow(0.3)
# l1 can still be used in the original form

or_(), and_(), xor(), not_() methods#

These methods perform boolean operations. Their notation is somewhat unusual but follows the method notation of Python:

l1 = layer("1/0")
l2 = layer("2/0")
one_of_them = l1.xor(l2)

Here is the output of the operations:

layer a

layer b





























Methods on mask data objects: grow() and etch()#

The following methods are available for mask data objects:




Deposition of material where this mask is present


Removal of material where this mask is present

grow() method#

This method is important and has a rich parameter set, so it is described in an individual document here: The grow() Method.

etch() method#

This method is important and has a rich parameter set, so it is described in an individual document here: The etch() Method.