MLA150 - Troubleshooting - Revision history

John d: /* Misalignment */

2026-03-09T01:57:39Z

Misalignment

← Older revision		Revision as of 01:57, 9 March 2026
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	** 1.000 100 (aka. 100 [https://en.wikipedia.org/wiki/Parts-per_notation ppm]) scaling error over a 4-inch wafer, assuming the wafer center is perfectly aligned, will result in 1.000100 * 20mm = 2µm of misalignment 2cm away from wafer center.		** 1.000 100 (aka. 100 [https://en.wikipedia.org/wiki/Parts-per_notation ppm]) scaling error over a 4-inch wafer, assuming the wafer center is perfectly aligned, will result in 1.000100 * 20mm = 2µm of misalignment 2cm away from wafer center.
	** Typical scaling that does not require correction will be within ~10ppm (0.999 990 to 1.000 010).		** Typical scaling that does not require correction will be within ~10ppm (0.999 990 to 1.000 010).
	* Shearing (angle between X & Y axes) will manifest as an angle-based walk-off. We have never yet seen this issue.		* Shearing (angle between X & Y axes) will manifest as an angle-based walk-off. We have never yet seen this issue when matching between our tools.

	Adding more alignment marks, spaced further apart, allows for better curve-fitting and statistics when the software calculates these values in Global alignment modes.		Adding more alignment marks, spaced further apart, allows for better curve-fitting and statistics when the software calculates these values in Global alignment modes.

John d: /* Misalignment */

2026-01-15T23:41:52Z

Misalignment

← Older revision		Revision as of 23:41, 15 January 2026
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	* Scaling (aka. magnification) errors will manifest as a walk-off as you get further away from some point (eg. substrate center).		* Scaling (aka. magnification) errors will manifest as a walk-off as you get further away from some point (eg. substrate center).
	** If Scaling shows a value far away from 1.000, but you left the checkbox disabled, the magnification was ''not'' corrected during exposure. You may try '''En'''abling ~~this~~ ~~value~~ prior to exposure, to ~~correct~~ the exposed patterns accordingly.		** If Scaling shows a value far away from 1.000, but you left the checkbox disabled, the magnification was ''not'' corrected during exposure. You may try '''En'''abling the Scaling correction prior to exposure, so the MLA will adjust the exposed patterns accordingly.
	** The walk-off will be larger for larger substrates/patterns.		** The walk-off will be larger for larger substrates/patterns.
	** You can calculate how much misalignment you will get for some magnification error, for example:		** You can calculate how much misalignment you will get for some magnification error, for example:

John d: /* Misalignment */ minor updates, fixed typo

2026-01-15T23:41:20Z

Misalignment: minor updates, fixed typo

← Older revision		Revision as of 23:41, 15 January 2026
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	== Misalignment ==		== Misalignment ==
	Inadequate alignment between ~~pervious~~ and current lithography layers requires some additional investigation.		Inadequate alignment between previous and current lithography layers requires some additional investigation.

	First, pay attention to the calculated alignment corrections.		First, pay attention to the calculated alignment corrections.
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	* Shearing [_]: '''dis'''abled by default		* Shearing [_]: '''dis'''abled by default

	Observe the calculated values of Scaling and Shearing (angle between X & Y axes) after ~~alignment~~.		Observe the calculated values of Scaling and Shearing (angle between X & Y axes) after aligning.

	* Scaling (aka. magnification) errors will manifest as a walk-off as you get further away from some point (eg. substrate center).		* Scaling (aka. magnification) errors will manifest as a walk-off as you get further away from some point (eg. substrate center).
	** If Scaling shows a value far away from 1.000, but you left the checkbox disabled, the magnification was ''not'' corrected during exposure.		** If Scaling shows a value far away from 1.000, but you left the checkbox disabled, the magnification was ''not'' corrected during exposure. You may try '''En'''abling this value prior to exposure, to correct the exposed patterns accordingly.
	** The walk-off will be larger for larger substrates/patterns.		** The walk-off will be larger for larger substrates/patterns.
	** You can calculate how much misalignment you will get for some magnification error, for example:		** You can calculate how much misalignment you will get for some magnification error, for example:
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	For example:		For example:
	[[File:MLA150 Alignment versus Wafer Location v1.jpg\|alt=screenshot showing misalignment versus wafer location, with arrows indicating misalignment direction\|none\|thumb\|Example of misalignment analysis. Arrows indicate direction of misalignment at each ensured location. In this case the arrows clearly indicate the ~~cause error~~ is due to Magnification/Scaling, not X/Y shift.]]		[[File:MLA150 Alignment versus Wafer Location v1.jpg\|alt=screenshot showing misalignment versus wafer location, with arrows indicating misalignment direction\|none\|thumb\|Example of misalignment analysis. Arrows indicate direction of misalignment at each ensured location. In this case the arrows clearly indicate the misalignment is due to '''Magnification/Scaling''', not X/Y shift.]]

	=== Die-to-Die Alignment ===		=== Die-to-Die Alignment ===

John d: added "autofocus not working" solution

2025-05-13T20:55:26Z

added "autofocus not working" solution

@@ Line 53: / Line 53: @@
 *For transparent, thin substrates, try switching to blanket deposition and etching (instead of liftoff), to provide an opaque surface
 *If nothing else works, use contact alignment with a photomask.
 ==Exposure Logs / Reports==

John d: /* Analyzing misalignment */ further explain how to draw arrows

2024-10-27T17:28:55Z

Analyzing misalignment: further explain how to draw arrows

← Older revision		Revision as of 17:28, 27 October 2024
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	It is recommended that you include [[Calculators + Utilities#General CAD files for Lithography\|Vernier alignment]] patterns between layers to measure misalignment using the microscopes.		It is recommended that you include [[Calculators + Utilities#General CAD files for Lithography\|Vernier alignment]] patterns between layers to measure misalignment using the microscopes.

	To understand the origin/mechanism of misalignment you are experiencing, it is recommended to plot the '''misalignment versus wafer location''' - this often elucidates the solution; ~~for example:~~		To understand the origin/mechanism of misalignment you are experiencing, it is recommended to plot the '''misalignment versus wafer location''' - this often elucidates the solution;

⚫	[[File:MLA150 Alignment versus Wafer Location v1.jpg\|alt=screenshot showing misalignment versus wafer location, with arrows indicating misalignment direction\|none\|thumb\|Example of misalignment analysis - in this case clearly ~~showing~~ the cause is Magnification/Scaling.]]
			Draw a small arrow indicating the direction of misalignment. For example, if 2nd layer is misaligned by (-2µm , 0µm) then you draw an arrow pointing left ← at that wafer location.

			For example:
		⚫	[[File:MLA150 Alignment versus Wafer Location v1.jpg\|alt=screenshot showing misalignment versus wafer location, with arrows indicating misalignment direction\|none\|thumb\|Example of misalignment analysis. Arrows indicate direction of misalignment at each ensured location. In this case the arrows clearly indicate the cause error is due to Magnification/Scaling, not X/Y shift.]]

	=== Die-to-Die Alignment ===		=== Die-to-Die Alignment ===

John d: /* Misalignment */

2024-10-22T23:32:34Z

Misalignment

← Older revision		Revision as of 23:32, 22 October 2024
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	#On the '''[Exposure]''' screen, '''Disable''' "Scaling" and "Shearing", and '''Enable "Rotation"'''. The CAD file's origin should be accurately placed in the center of the schematic, and aligned to the wafer edge.		#On the '''[Exposure]''' screen, '''Disable''' "Scaling" and "Shearing", and '''Enable "Rotation"'''. The CAD file's origin should be accurately placed in the center of the schematic, and aligned to the wafer edge.
	#Proceed with exposure as normal (setting Dose/Defocus and [Expose]).		#Proceed with exposure as normal (setting Dose/Defocus and [Expose]).
	Developed+Written by [[Demis D. John]], 2023		''Developed+Written by [[Demis D. John]], 2023''

	== Misalignment ==		== Misalignment ==
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	Please see the "Field alignment" section of the [[Maskless Aligner (Heidelberg MLA150)#Operating Procedures\|Operating procedure]] for detailed instructions.		Please see the "Field alignment" section of the [[Maskless Aligner (Heidelberg MLA150)#Operating Procedures\|Operating procedure]] for detailed instructions.

			''Written by [[Demis D. John]], 2024-10''

	==Greyscale Lithography Limitations==		==Greyscale Lithography Limitations==

John d: /* Aligning to a quarter-wafer/irregular piece */ autor

2024-10-22T23:31:39Z

Aligning to a quarter-wafer/irregular piece: autor

← Older revision		Revision as of 23:31, 22 October 2024
Line 137:		Line 137:
	#On the '''[Exposure]''' screen, '''Disable''' "Scaling" and "Shearing", and '''Enable "Rotation"'''. The CAD file's origin should be accurately placed in the center of the schematic, and aligned to the wafer edge.		#On the '''[Exposure]''' screen, '''Disable''' "Scaling" and "Shearing", and '''Enable "Rotation"'''. The CAD file's origin should be accurately placed in the center of the schematic, and aligned to the wafer edge.
	#Proceed with exposure as normal (setting Dose/Defocus and [Expose]).		#Proceed with exposure as normal (setting Dose/Defocus and [Expose]).
			Developed+Written by [[Demis D. John]], 2023

	== Misalignment ==		== Misalignment ==

John d: /* Misalignment */ added typical value for scaling

2024-10-22T23:29:15Z

Misalignment: added typical value for scaling

← Older revision		Revision as of 23:29, 22 October 2024
Line 156:		Line 156:
	** You can calculate how much misalignment you will get for some magnification error, for example:		** You can calculate how much misalignment you will get for some magnification error, for example:
	** 1.000 100 (aka. 100 [https://en.wikipedia.org/wiki/Parts-per_notation ppm]) scaling error over a 4-inch wafer, assuming the wafer center is perfectly aligned, will result in 1.000100 * 20mm = 2µm of misalignment 2cm away from wafer center.		** 1.000 100 (aka. 100 [https://en.wikipedia.org/wiki/Parts-per_notation ppm]) scaling error over a 4-inch wafer, assuming the wafer center is perfectly aligned, will result in 1.000100 * 20mm = 2µm of misalignment 2cm away from wafer center.
			** Typical scaling that does not require correction will be within ~10ppm (0.999 990 to 1.000 010).
	* Shearing (angle between X & Y axes) will manifest as an angle-based walk-off. We have never yet seen this issue.		* Shearing (angle between X & Y axes) will manifest as an angle-based walk-off. We have never yet seen this issue.

John d: addded misalignment section

2024-10-22T23:26:01Z

addded misalignment section

@@ Line 137: / Line 137: @@
 #On the '''[Exposure]''' screen, '''Disable''' "Scaling" and "Shearing", and '''Enable "Rotation"'''.  The CAD file's origin should be accurately placed in the center of the schematic, and aligned to the wafer edge.
 #Proceed with exposure as normal (setting Dose/Defocus and [Expose]).
 ==Greyscale Lithography Limitations==

Sawyer l: Piezo range values

2024-10-18T17:08:22Z

Piezo range values

← Older revision		Revision as of 17:08, 18 October 2024
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	After exposure, open the logfile for your Job (see [[MLA150 - Troubleshooting#Exposure Logs .2F Reports\|this tip for logfile location]]) and search for the word "''piezo''". This records the Z-height Piezo position - the physical autofocus position - at the end/start of each stripe (when the optical head changes direction, off the substrate). Since the piezo freezes motion off the substrate, this value indicates the autofocus piezo height at the edge of your substrate.		After exposure, open the logfile for your Job (see [[MLA150 - Troubleshooting#Exposure Logs .2F Reports\|this tip for logfile location]]) and search for the word "''piezo''". This records the Z-height Piezo position - the physical autofocus position - at the end/start of each stripe (when the optical head changes direction, off the substrate). Since the piezo freezes motion off the substrate, this value indicates the autofocus piezo height at the edge of your substrate.

	When in-focus on your substrate this should be in the range ~2,000 to 25,000 or so. If you see a value ~~like~~ ~~"192"~~ or ~~<500~~, then this usually means the autofocus drove to it's limit, because it was not tracking the substrate surface. Sometimes the first one or two stripes are in-focus, and then the rest are out of focus. Other times, the system is out of focus from the start, and stays this way for the entire exposure.		When in-focus on your substrate this should be in the range ~28,000 to 51,000 or so. If you see a value significantly outside of this range, then this usually means the autofocus drove to it's limit, because it was not tracking the substrate surface. Sometimes the first one or two stripes are in-focus, and then the rest are out of focus. Other times, the system is out of focus from the start, and stays this way for the entire exposure.

	You can see the optical autofocus laser position in the camera, it is about 6µm up-left from the central crosshair. It is a confocal surface detection, which continuously tracks the surface – even while manually driving around the substrate before exposure. When this laser hits a bad point (eg. black /dark no reflection, or particle, or steep slope) it can lose surface tracking. During substrate load, the system attempts to land on the surface using this system.		You can see the optical autofocus laser position in the camera, it is about 6µm up-left from the central crosshair. It is a confocal surface detection, which continuously tracks the surface – even while manually driving around the substrate before exposure. When this laser hits a bad point (eg. black /dark no reflection, or particle, or steep slope) it can lose surface tracking. During substrate load, the system attempts to land on the surface using this system.