KLayout Design Tips - Revision history

John d at 16:46, 18 June 2025

2025-06-18T16:46:59Z

← Older revision		Revision as of 16:46, 18 June 2025
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	=== Saving layer styles ===		=== Saving layer styles ===
	If you change the colors/styles of Layer display, Klayout doesn't save those into it's global preferences. Instead, you can either '''''File > Save Session''''' or '''''File > Save Layer Properties'''''. Layer Properties files (*.lyp) contain the layer display styles. You can either open these files manually via '''''File > Load Layer Properties''''' or set KLayout to automatically load any Layer Properties files with the same name as the currently loaded CAD file, [https://www.klayout.de/forum/discussion/102/application-note-automatically-load-a-companion-lyp-file in this hint].		If you change the colors/styles of Layer display, Klayout doesn't save those into it's global preferences. Instead, you can either '''''File > [[KLayout Design Tips#Save your editing session\|Save Session]]''''' or '''''File > Save Layer Properties'''''. Layer Properties files (*.lyp) contain the layer display styles. You can either open these files manually via '''''File > Load Layer Properties''''' or set KLayout to automatically load any Layer Properties files with the same name as the currently loaded CAD file, as [https://www.klayout.de/forum/discussion/102/application-note-automatically-load-a-companion-lyp-file in this hint].
	[[File:KLayout - auto-load layer properties screenshot.png\|alt=Screenshot of KLayout settings to auto-load layer properties\|none\|thumb\|514x514px\|KLayout > Setup > Application:Layer PropertiesSet to <code>$(combine(path(layoutfile),basename(layoutfile))+".lyp")</code>From [https://www.klayout.de/forum/discussion/102/application-note-automatically-load-a-companion-lyp-file this KLayout Forums hint].]]		[[File:KLayout - auto-load layer properties screenshot.png\|alt=Screenshot of KLayout settings to auto-load layer properties\|none\|thumb\|514x514px\|KLayout > Setup > Application:Layer PropertiesSet to <code>$(combine(path(layoutfile),basename(layoutfile))+".lyp")</code>From [https://www.klayout.de/forum/discussion/102/application-note-automatically-load-a-companion-lyp-file this KLayout Forums hint].]]
	This way, if you have two files:		This way, if you have two files:

John d: added sub headings nand layer styles

2025-06-18T16:46:17Z

added sub headings nand layer styles

← Older revision		Revision as of 16:46, 18 June 2025
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	===Turn on Editing Mode===		===Turn on Editing Mode===
	By default, KLayout might open as a "viewer" only, without draw-mode ~~capbilities~~ (no square/polygon/text buttons in the toolbar) and only ruler/zoom tools. Enable Editing mode as so:		By default, KLayout might open as a "viewer" only, without draw-mode capabilities (no square/polygon/text buttons in the toolbar) and only ruler/zoom tools. Enable Editing mode as so:

	*'''''Preferences > Editing mode > [√] Use Editing Mode by default''''', and restart the software.		*'''''Preferences > Editing mode > [√] Use Editing Mode by default''''', and restart the software.
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	===File Types===		===File Types===
⚫	OASIS format is the successor to the GDS format, and is the preferred format, except that some software (eg. Heidelberg) doesn't yet accept it. All Photomask vendors accept OASIS format. OASIS files tend to be much smaller than GDS files, and they also save the Layer Names (not just Layer Number)~~. All Photomask manufacturers accept this file type~~. KLayout ~~can convert~~ between OASIS and GDS without issue ~~(except~~ ~~that~~ GDS ~~loses~~ ~~the~~ ~~layer~~ ~~names)~~. See [https://www.klayout.de/forum/discussion/2152/oasis-the-successor-to-gds/p1?new=1 this article] for more info.

			==== GDS vs. OASIS format ====
⚫	GDS files are considered "standard", but are somewhat antiquated, lose the text names of layers between saves and can be 1000x larger file size than OASIS. The Heidelberg software ([[Maskless Aligner (Heidelberg MLA150)\|MLA150]]) only accepts GDS as the preferred format, not OASIS.
		⚫	OASIS format is the successor to the GDS format, and is the preferred format, except that some software (eg. Heidelberg) doesn't yet accept it natively. Instead most users do all their editing in OASIS, and convert to GDS only for use on those specific tools that require it. All Photomask vendors accept OASIS format. OASIS files tend to be much smaller than GDS files, and they also save the Layer Names (not just Layer Number). KLayout converts between OASIS and GDS without issue - so you can easily convert to GDS for those tools that need it. See [https://www.klayout.de/forum/discussion/2152/oasis-the-successor-to-gds/p1?new=1 this article] for more detailed info.

		⚫	GDS files are considered "standard", but are somewhat antiquated: they lose the text names of layers between saves and can be 1000x larger file size than OASIS files (even when "zipped" in .gds.gz). The Heidelberg software ([[Maskless Aligner (Heidelberg MLA150)\|MLA150]]) only accepts GDS as the preferred format, not OASIS, so users typically save as GDS right before the MLA150 write.
⚫	~~Alternatively, in~~ KLayout the function '''File > Save Session''' will save the entire view including layer styles and window/zoom locations will be saved. You can share this file, as the entire design file is embedded within it, but it may not be as robust between KLayout versions.

			==== Save your editing session ====
		⚫	In KLayout the function '''File > Save Session''' will save the entire view including layer styles and window/zoom locations will be saved. You can share this file, as the entire design file is embedded within it, but it may not be as robust between KLayout versions. During editing, this is a helpful function to avoid losing your place.

			==== DXF Format ====
	DXF files coming from AutoCAD often are missing the "units", and may erroneously map millimeters to meters, causing your design to be scaled 1000x too large. You can fix this in '''''File > Reader Options > DXF''''', or simply instance the entire design into a new Cell with Magnification set to correct the scaling error. Also, AutoCAD allows for non-closed polygons, which are invalid shapes (even though the start/end points lie on top of each other, the shape is not technically "closed" unless you use polyline-edit "''PEDIT''" and intentionally Close them). The DXF Reader has some options to catch/fix these.		DXF files coming from AutoCAD often are missing the "units", and may erroneously map millimeters to meters, causing your design to be scaled 1000x too large. You can fix this in '''''File > Reader Options > DXF''''', or simply instance the entire design into a new Cell with Magnification set to correct the scaling error. Also, AutoCAD allows for non-closed polygons, which are invalid shapes (even though the start/end points lie on top of each other, the shape is not technically "closed" unless you use polyline-edit "''PEDIT''" and intentionally Close them). The DXF Reader has some options to catch/fix these.
	===Non-Orthogonal Arrays===		===Non-Orthogonal Arrays===
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	#The OAS file type generates much smaller files, and most photomask vendors can accept this. Photomask vendors are used to handling large files.		#The OAS file type generates much smaller files, and most photomask vendors can accept this. Photomask vendors are used to handling large files.
	#Photomask vendors are able to take multiple files and insert them into the final reticle – you just need to provide a clear schematic showing the exact insertion coordinates for each file (with respect to the origin of each file). They can also do some boolean operations (for a fee).		#Photomask vendors are able to take multiple files and insert them into the final reticle – you just need to provide a clear schematic showing the exact insertion coordinates for each file (with respect to the origin of each file). They can also do some boolean operations (for a fee).

			=== Saving layer styles ===
			If you change the colors/styles of Layer display, Klayout doesn't save those into it's global preferences. Instead, you can either '''''File > Save Session''''' or '''''File > Save Layer Properties'''''. Layer Properties files (*.lyp) contain the layer display styles. You can either open these files manually via '''''File > Load Layer Properties''''' or set KLayout to automatically load any Layer Properties files with the same name as the currently loaded CAD file, [https://www.klayout.de/forum/discussion/102/application-note-automatically-load-a-companion-lyp-file in this hint].
			[[File:KLayout - auto-load layer properties screenshot.png\|alt=Screenshot of KLayout settings to auto-load layer properties\|none\|thumb\|514x514px\|KLayout > Setup > Application:Layer PropertiesSet to <code>$(combine(path(layoutfile),basename(layoutfile))+".lyp")</code>From [https://www.klayout.de/forum/discussion/102/application-note-automatically-load-a-companion-lyp-file this KLayout Forums hint].]]
			This way, if you have two files:

			* <code>MyCADDesign.gds</code> (or <code>.oas</code>), and
			* <code>MyCADDesign.lyp</code> - layer properties

			KLayout will automatically load the layer properties when it loads the OAS/GDS file.

			By default <code>Automatically add other layers</code> is enabled, so any layers that aren't in your CAD file will be created and left empty - disabling this ''won't'' create those empty layers.

	''[[Demis D. John]], updated 2022-09''		''[[Demis D. John]], updated 2022-09''

John d: link to example CAD files

2025-04-19T22:49:53Z

link to example CAD files

← Older revision		Revision as of 22:49, 19 April 2025
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	__TOC__		__TOC__

			=== [[Calculators + Utilities#Example CAD File\|Example CAD Files]] ===
			See the above link for example CAD files set up with Cells, Instancing, Origins and Layers setup as recommended.

	===Turn on Editing Mode===		===Turn on Editing Mode===

John d: /* How to draw Text */ minor update

2024-05-01T15:57:09Z

How to draw Text: minor update

← Older revision		Revision as of 15:57, 1 May 2024
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	**Klayout doesn't natively support circles because the GDS file format does not have a "circle" primitive built-in, so instead it creates a polygon. Make sure you include enough polygon points, eg. 32. See the [https://www.klayout.de/forum/discussion/142/making-circles forum help pages] on this for more info.		**Klayout doesn't natively support circles because the GDS file format does not have a "circle" primitive built-in, so instead it creates a polygon. Make sure you include enough polygon points, eg. 32. See the [https://www.klayout.de/forum/discussion/142/making-circles forum help pages] on this for more info.

	=== How to draw Text ===		===How to draw Text===
	A common mistake is to use the “Text” tool to draw text that you want to get printed on the mask plate.		A common mistake is to use the “Text” tool to draw text that you want to get printed on the mask plate.

	'''Only Polygons''' will get printed on the final mask plate. To print text, you have to convert the Text tool objects into polygons as so:		'''Only Polygons''' will get printed on the final mask plate. To print text, you have to convert the Text tool objects into polygons as so:

	* Use the Text Tool to place some text. These text objects are useful for comments/labels on a layout that won’t get printed.		*Use the '''Text''' Tool to place some text. These text objects are useful for comments/labels on a layout that won’t get printed.
	* select the text object		*select the text object
	* Use the function Edit > Selection > Convert to PCell		*Use the function '''Edit > Selection > Convert to PCell'''
	* by default the PCell ~~“BASIC~~.~~TEXT”~~ should be selected.		*by default the PCell “'''BASIC.TEXT'''” should be selected.
	* Select the object again if needed, and view the object’s Properties (Edit > Properties)		*Select the object again if needed, and view the object’s Properties ('''Edit > Properties''')
	* Here you can adjust the Size ~~vía~~ ~~“Magnification”~~, the text, and other useful properties.		*Here you can adjust the Size via the “''Magnification''” parameter, the text string, and other useful properties.

	Note that the default font has enclosed spaces, which is sometimes non-optimal for lift-off processes. See this hint for [https://www.klayout.de/forum/discussion/comment/6919/#Comment_6919 installing a Vented Font.]		Note that the default font has enclosed spaces, which is sometimes non-optimal for lift-off processes. See this hint for [https://www.klayout.de/forum/discussion/comment/6919/#Comment_6919 '''installing a Vented Font.''']

	===Cells & Instances of Cells===		===Cells & Instances of Cells===
	It is highly recommended that you understand and use the concept of "Cells" in your design. This is critical for direct-write machines ([https://wiki.nanotech.ucsb.edu/wiki/E-Beam_Lithography_System_(JEOL_JBX-6300FS) EBL], [https://wiki.nanotech.ucsb.edu/wiki/Maskless_Aligner_(Heidelberg_MLA150) MLA], Mask-writing vendors), and if used properly, helps tremendously with programming the Stepper lithography machines. This functionality also circumvents many problems with enormous file sizes (due to huge numbers of identical polygons), by "pointing" to the same polygon only defined once in the file. Links to documentation below:		It is highly recommended that you understand and use the concept of "'''Cells'''" & "'''Instances'''" in your design. This is critical for direct-write machines ([https://wiki.nanotech.ucsb.edu/wiki/E-Beam_Lithography_System_(JEOL_JBX-6300FS) EBL], [https://wiki.nanotech.ucsb.edu/wiki/Maskless_Aligner_(Heidelberg_MLA150) MLA], Mask-writing vendors), and if used properly, helps tremendously with programming the Stepper lithography machines. This functionality also circumvents many problems with enormous file sizes (due to huge numbers of identical polygons), by "pointing" to the same polygon only defined once in the file. Links to documentation below:

	*Create a new cell, and instancing that cell: [https://www.klayout.de/doc-qt4/manual/create_instance.html KLayout Docs : Creating a Cell instance]		*Create a new cell, and instancing that cell: [https://www.klayout.de/doc-qt4/manual/create_instance.html KLayout Docs : Creating a Cell instance]
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	===File Types===		===File Types===
	OASIS format is the successor to the GDS format, and is the preferred format, except that some software doesn't yet accept it. OASIS files tend to be much smaller than GDS files, and they also save the Layer Names (not just Layer Number). All Photomask manufacturers accept this file type. KLayout can convert between OASIS and GDS without issue (except that GDS loses the layer names). See [https://www.klayout.de/forum/discussion/2152/oasis-the-successor-to-gds/p1?new=1 this article] for more info.		OASIS format is the successor to the GDS format, and is the preferred format, except that some software (eg. Heidelberg) doesn't yet accept it. All Photomask vendors accept OASIS format. OASIS files tend to be much smaller than GDS files, and they also save the Layer Names (not just Layer Number). All Photomask manufacturers accept this file type. KLayout can convert between OASIS and GDS without issue (except that GDS loses the layer names). See [https://www.klayout.de/forum/discussion/2152/oasis-the-successor-to-gds/p1?new=1 this article] for more info.

	GDS files are considered "standard", but are somewhat antiquated, lose the text names of layers between saves and can be 1000x larger file size than OASIS. The Heidelberg software ([[Maskless Aligner (Heidelberg MLA150)\|MLA150]]) accepts GDS as the preferred format.		GDS files are considered "standard", but are somewhat antiquated, lose the text names of layers between saves and can be 1000x larger file size than OASIS. The Heidelberg software ([[Maskless Aligner (Heidelberg MLA150)\|MLA150]]) only accepts GDS as the preferred format, not OASIS.

	Alternatively, in KLayout the function '''File > Save Session''' will save the entire view including layer styles and window/zoom locations will be saved. You can share this file, as the entire design file is embedded within it, but it may not be as robust between KLayout versions.		Alternatively, in KLayout the function '''File > Save Session''' will save the entire view including layer styles and window/zoom locations will be saved. You can share this file, as the entire design file is embedded within it, but it may not be as robust between KLayout versions.

	DXF files coming from AutoCAD often are missing the "units", and may erroneously map millimeters to meters, causing your design to be 1000x too large. You can fix this in '''''File > Reader Options > DXF''''', or simply instance the entire design into a new Cell with Magnification set to correct the scaling error. Also, AutoCAD allows for non-closed polygons, which are invalid shapes (even though the start/end points lie on top of each other, the shape is not technically "closed" unless you use polyline-edit "''PEDIT''" and intentionally Close them). The DXF Reader has some options to catch/fix these.		DXF files coming from AutoCAD often are missing the "units", and may erroneously map millimeters to meters, causing your design to be scaled 1000x too large. You can fix this in '''''File > Reader Options > DXF''''', or simply instance the entire design into a new Cell with Magnification set to correct the scaling error. Also, AutoCAD allows for non-closed polygons, which are invalid shapes (even though the start/end points lie on top of each other, the shape is not technically "closed" unless you use polyline-edit "''PEDIT''" and intentionally Close them). The DXF Reader has some options to catch/fix these.
	===Non-Orthogonal Arrays===		===Non-Orthogonal Arrays===
	Arrays created with diagonal instancing (non-orthogonal arrays) can be incompatible with photomask vendor's mask writing software.		Arrays created with diagonal instancing (non-orthogonal arrays) can be incompatible with photomask vendor's mask writing software.

John d: How to print text

2023-09-02T16:10:57Z

How to print text

@@ Line 20: / Line 20: @@
 **Another way is to convert a square to a polygon directly with '''''Edit>Selection>Round Corners''''' function with '''''Outer Corner Radius''''' = the desired circle radius (radius is not changeable afterards in this method, but computation may be faster for a large number of objects).
 **Klayout doesn't natively support circles because the GDS file format does not have a "circle" primitive built-in, so instead it creates a polygon. Make sure you include enough polygon points, eg. 32. See the [https://www.klayout.de/forum/discussion/142/making-circles forum help pages] on this for more info.
 ===Cells & Instances of Cells===

John d: /* File Types */ Mentioned that MLA150 requires GDS

2022-09-08T02:32:54Z

File Types: Mentioned that MLA150 requires GDS

← Older revision		Revision as of 02:32, 8 September 2022
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	OASIS format is the successor to the GDS format, and is the preferred format, except that some software doesn't yet accept it. OASIS files tend to be much smaller than GDS files, and they also save the Layer Names (not just Layer Number). All Photomask manufacturers accept this file type. KLayout can convert between OASIS and GDS without issue (except that GDS loses the layer names). See [https://www.klayout.de/forum/discussion/2152/oasis-the-successor-to-gds/p1?new=1 this article] for more info.		OASIS format is the successor to the GDS format, and is the preferred format, except that some software doesn't yet accept it. OASIS files tend to be much smaller than GDS files, and they also save the Layer Names (not just Layer Number). All Photomask manufacturers accept this file type. KLayout can convert between OASIS and GDS without issue (except that GDS loses the layer names). See [https://www.klayout.de/forum/discussion/2152/oasis-the-successor-to-gds/p1?new=1 this article] for more info.

	GDS files are considered "standard", but are somewhat antiquated, lose the text names of layers between saves and can be 1000x larger file size.		GDS files are considered "standard", but are somewhat antiquated, lose the text names of layers between saves and can be 1000x larger file size than OASIS. The Heidelberg software ([[Maskless Aligner (Heidelberg MLA150)\|MLA150]]) accepts GDS as the preferred format.

	Alternatively, in KLayout the function '''File > Save Session''' will save the entire view including layer styles and window/zoom locations will be saved. You can share this file, as the entire design file is embedded within it, but it may not be as robust between KLayout versions.		Alternatively, in KLayout the function '''File > Save Session''' will save the entire view including layer styles and window/zoom locations will be saved. You can share this file, as the entire design file is embedded within it, but it may not be as robust between KLayout versions.

John d: /* File Types */ clarify OASIS GDS compatibility

2022-09-08T02:30:32Z

File Types: clarify OASIS GDS compatibility

← Older revision		Revision as of 02:30, 8 September 2022
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	===File Types===		===File Types===
	OASIS files tend to be much smaller than GDS files, and they also save the Layer Names (not just Layer Number). ~~Most~~ Photomask manufacturers accept this file type.		OASIS format is the successor to the GDS format, and is the preferred format, except that some software doesn't yet accept it. OASIS files tend to be much smaller than GDS files, and they also save the Layer Names (not just Layer Number). All Photomask manufacturers accept this file type. KLayout can convert between OASIS and GDS without issue (except that GDS loses the layer names). See [https://www.klayout.de/forum/discussion/2152/oasis-the-successor-to-gds/p1?new=1 this article] for more info.

	GDS files are considered "standard", but are somewhat antiquated, ~~and~~ lose the text names of layers between saves.		GDS files are considered "standard", but are somewhat antiquated, lose the text names of layers between saves and can be 1000x larger file size.

	Alternatively, in KLayout the function '''File > Save Session''' will save the entire view including layer styles and window/zoom locations will be saved. You can share this file, as the entire design file is embedded within it, but it may not be as robust between KLayout versions.		Alternatively, in KLayout the function '''File > Save Session''' will save the entire view including layer styles and window/zoom locations will be saved. You can share this file, as the entire design file is embedded within it, but it may not be as robust between KLayout versions.

John d: /* How to draw circles */ better method to convert all Cells to Static Cells

2022-09-08T01:58:11Z

How to draw circles: better method to convert all Cells to Static Cells

← Older revision		Revision as of 01:58, 8 September 2022
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	===How to draw circles===		===How to draw circles===

	*You have to draw a square, and then apply the function '''''Edit > Selection > Convert to PCell'' > Basic.CIRCLE'''. ~~Sometimes these~~ P-~~Cells~~ ~~don't~~ ~~convert properly at the photomask vendor, so make sure to run '''''Edit > Selection > Convert to Static~~ Cell~~'''''~~ or ~~'''''Flatten'''''~~ ~~(which converts~~ to a ~~polygon)~~ ~~before~~ ~~sending~~ to ~~the~~ ~~vendor/machine~~.		*You have to draw a square, and then apply the function '''''Edit > Selection > Convert to PCell'' > Basic.CIRCLE'''. (A P-Cell is a Cell with parameters - like a programmer's "function" with "arguments" of sorts.)
			*Sometimes these P-Cells don't convert properly at the photomask vendor, so make sure to run '''''Edit > Selection > Convert to Static Cell''''' or '''''Edit > Layout > Convert All Cells to Static''''' before sending to the vendor/machine, which converts to a regular polygon in a Cell. (You lose editing capabilities of the P-Cell when you do this.)
	**Another way is to convert a square to a polygon directly with '''''Edit>Selection>Round Corners''''' function with '''''Outer Corner Radius''''' = the desired circle radius (radius is not changeable afterards in this method, but computation may be faster for a large number of objects).		**Another way is to convert a square to a polygon directly with '''''Edit>Selection>Round Corners''''' function with '''''Outer Corner Radius''''' = the desired circle radius (radius is not changeable afterards in this method, but computation may be faster for a large number of objects).
	**Klayout doesn't natively support circles because the GDS file format does not have a "circle" primitive built-in, so instead it creates a polygon. Make sure you include enough polygon points, eg. 32. See the [https://www.klayout.de/forum/discussion/142/making-circles forum help pages] on this for more info.		**Klayout doesn't natively support circles because the GDS file format does not have a "circle" primitive built-in, so instead it creates a polygon. Make sure you include enough polygon points, eg. 32. See the [https://www.klayout.de/forum/discussion/142/making-circles forum help pages] on this for more info.

John d: added author credit

2022-09-08T01:55:17Z

added author credit

← Older revision		Revision as of 01:55, 8 September 2022
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	If you do need to use a non-orthogonal array, make sure to use '''''Selection > Resolve Arrays''''' before submitting your design to the manufacturer/machine.		If you do need to use a non-orthogonal array, make sure to use '''''Selection > Resolve Arrays''''' before submitting your design to the manufacturer/machine.

	=== Handling very large files ===		===Handling very large files===
	If you will be generating millions of identical shapes (eg. repeating array of circles), the file size can quickly become enormous due to all the stored polygon points. You can reduce the number of polygon points stored by:		If you will be generating millions of identical shapes (eg. repeating array of circles), the file size can quickly become enormous due to all the stored polygon points. You can reduce the number of polygon points stored by:

	# Reduce the number of points in each shape/circle if possible. Gentle corners will be rounded by the lithography resolution.		#Reduce the number of points in each shape/circle if possible. Gentle corners will be rounded by the lithography resolution.
	# Use Cell instancing so that only one, or a few, polygons are defined, and that same polygon is then only referenced as a repeating Cell instance. (See above for tutorials).		#Use Cell instancing so that only one, or a few, polygons are defined, and that same polygon is then only referenced as a repeating Cell instance. (See above for tutorials).
	# The OAS file type generates much smaller files, and most photomask vendors can accept this. Photomask vendors are used to handling large files.		#The OAS file type generates much smaller files, and most photomask vendors can accept this. Photomask vendors are used to handling large files.
	# Photomask vendors are able to take multiple files and insert them into the final reticle – you just need to provide a clear schematic showing the exact insertion coordinates for each file (with respect to the origin of each file). They can also do some boolean operations (for a fee).		#Photomask vendors are able to take multiple files and insert them into the final reticle – you just need to provide a clear schematic showing the exact insertion coordinates for each file (with respect to the origin of each file). They can also do some boolean operations (for a fee).

			''[[Demis D. John]], updated 2022-09''

John d: link to QNFCF Youtube videos on Cells

2022-09-03T15:35:44Z

link to QNFCF Youtube videos on Cells

← Older revision		Revision as of 15:35, 3 September 2022
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	__TOC__		__TOC__

	=== Turn on Editing Mode ===		===Turn on Editing Mode===
	By default, KLayout might open as a "viewer" only, without draw-mode capbilities (no square/polygon/text buttons in the toolbar) and only ruler/zoom tools. Enable Editing mode as so:		By default, KLayout might open as a "viewer" only, without draw-mode capbilities (no square/polygon/text buttons in the toolbar) and only ruler/zoom tools. Enable Editing mode as so:

	* '''''Preferences > Editing mode > [√] Use Editing Mode by default''''', and restart the software.		*'''''Preferences > Editing mode > [√] Use Editing Mode by default''''', and restart the software.

	===Turn on the display of the Origin (0,0)===		===Turn on the display of the Origin (0,0)===

	*'''''Preferences > Display > Background > Axis''''' = change from the default "invisible", eg. "'''''Lines ~~with Ticks~~'''''".		*'''''Preferences > Display > Background > Axis''''' = change from the default "invisible", eg. "'''''Lines'''''".

	===Minimum Step-Size / Database Unit===		===Minimum Step-Size / Database Unit===
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	===How to draw circles===		===How to draw circles===

	*You have to draw a square, and then apply the function '''''Edit > Selection > Convert to PCell'' > Basic.CIRCLE'''. Sometimes these P-Cells don't convert properly at the photomask vendor, so make sure to run '''''Edit > Selection > Convert to Static Cell''''' (which converts to a polygon) before sending to the vendor/machine.		*You have to draw a square, and then apply the function '''''Edit > Selection > Convert to PCell'' > Basic.CIRCLE'''. Sometimes these P-Cells don't convert properly at the photomask vendor, so make sure to run '''''Edit > Selection > Convert to Static Cell''''' or '''''Flatten''''' (which converts to a polygon) before sending to the vendor/machine.
	**Another way is to convert a square to a polygon directly with '''''Edit>Selection>Round Corners''''' function with '''''Outer Corner Radius''''' = the desired circle radius (radius is not changeable afterards in this method, but computation may be faster for a large number of objects).		**Another way is to convert a square to a polygon directly with '''''Edit>Selection>Round Corners''''' function with '''''Outer Corner Radius''''' = the desired circle radius (radius is not changeable afterards in this method, but computation may be faster for a large number of objects).
	**Klayout doesn't natively support circles because the GDS file format does not have a "circle" primitive built-in, so instead it creates a polygon. Make sure you include enough polygon points, eg. 32. See the [https://www.klayout.de/forum/discussion/142/making-circles forum help pages] on this for more info.		**Klayout doesn't natively support circles because the GDS file format does not have a "circle" primitive built-in, so instead it creates a polygon. Make sure you include enough polygon points, eg. 32. See the [https://www.klayout.de/forum/discussion/142/making-circles forum help pages] on this for more info.

	===Cells & Instances of Cells===		===Cells & Instances of Cells===
	It is highly recommended that you understand and use the concept of "Cells" in your design. This is critical for direct-write machines ([https://wiki.nanotech.ucsb.edu/wiki/E-Beam_Lithography_System_(JEOL_JBX-6300FS) EBL], [https://wiki.nanotech.ucsb.edu/wiki/Maskless_Aligner_(Heidelberg_MLA150) MLA], Mask-writing vendors), and if used properly, helps tremendously with programming the Stepper lithography machines. This functionality also circumvents many with enormous file sizes (due to huge numbers of identical polygons), by "pointing" to the same polygon only defined once in the file. Links to documentation below:		It is highly recommended that you understand and use the concept of "Cells" in your design. This is critical for direct-write machines ([https://wiki.nanotech.ucsb.edu/wiki/E-Beam_Lithography_System_(JEOL_JBX-6300FS) EBL], [https://wiki.nanotech.ucsb.edu/wiki/Maskless_Aligner_(Heidelberg_MLA150) MLA], Mask-writing vendors), and if used properly, helps tremendously with programming the Stepper lithography machines. This functionality also circumvents many problems with enormous file sizes (due to huge numbers of identical polygons), by "pointing" to the same polygon only defined once in the file. Links to documentation below:

	*Create a new cell, and instancing that cell: [https://www.klayout.de/doc-qt4/manual/create_instance.html KLayout Docs : Creating a Cell instance]		*Create a new cell, and instancing that cell: [https://www.klayout.de/doc-qt4/manual/create_instance.html KLayout Docs : Creating a Cell instance]
	*Viewing only some levels of the Cell heirarchy, to prevent drawing all objects: [https://www.klayout.de/doc/manual/hier.html KLayout Docs: Viewing Cell Heirarchy]		*Viewing only some levels of the Cell heirarchy, to prevent drawing all objects: [https://www.klayout.de/doc/manual/hier.html KLayout Docs: Viewing Cell Heirarchy]
			*Video Tutorials: [https://www.youtube.com/watch?v=VaoRk8fuvKY QNFCF: KLayout Cell Hierarchy Part 1] & [https://www.youtube.com/watch?v=5wvRE4HFbuw QNFCF: KLayout Cell Hierarchy Part 2]

	===File Types===		===File Types===
Line 40:		Line 41:
	[[File:KLayout - Non-Orthogonal Arrays.png\|alt=Klayou screenshot showing non-orthogonal array definition\|none\|thumb\|485x485px]]		[[File:KLayout - Non-Orthogonal Arrays.png\|alt=Klayou screenshot showing non-orthogonal array definition\|none\|thumb\|485x485px]]
	If you do need to use a non-orthogonal array, make sure to use '''''Selection > Resolve Arrays''''' before submitting your design to the manufacturer/machine.		If you do need to use a non-orthogonal array, make sure to use '''''Selection > Resolve Arrays''''' before submitting your design to the manufacturer/machine.

			=== Handling very large files ===
			If you will be generating millions of identical shapes (eg. repeating array of circles), the file size can quickly become enormous due to all the stored polygon points. You can reduce the number of polygon points stored by:

			# Reduce the number of points in each shape/circle if possible. Gentle corners will be rounded by the lithography resolution.
			# Use Cell instancing so that only one, or a few, polygons are defined, and that same polygon is then only referenced as a repeating Cell instance. (See above for tutorials).
			# The OAS file type generates much smaller files, and most photomask vendors can accept this. Photomask vendors are used to handling large files.
			# Photomask vendors are able to take multiple files and insert them into the final reticle – you just need to provide a clear schematic showing the exact insertion coordinates for each file (with respect to the origin of each file). They can also do some boolean operations (for a fee).