Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 02 processing: Difference between revisions

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 The error on the flat alignment is surprising when compared to the 0±0.1° measured on Aligner: Maskless 01. The centring, on the other hand, is seen to be within a few hundred µm, without correcting for the flats.
-'''Result of loading the same substrate 2x9 times without removing it from the stage:'''
+'''Result of loading the same substrate ~10 times without removing it from the stage:'''
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 |-style="background:WhiteSmoke; color:black"
-|Optical
+|Optical autofocus
-autofocus
+(as installed)
 | 3.7 mRad
 | ±13.9 mRad
@@ Line 326: / Line 326: @@
 |-
 |-style="background:WhiteSmoke; color:black"
-|Pneumatic
+|Pneumatic autofocus
-autofocus
+(as installed)
 | -3.1 mRad
 | ±1.4 mRad
 ±0.08°
-|}
+|-
+|-style="background:WhiteSmoke; color:black"
+|Positioning a wafer repeatedly using the alignment tool
+(measured using pneumatic autofocus)
+| -1.7 mRad
+| ±8.3 mRad
+±0.5°
-This shows that using optical autofocus significantly increases the error on the flat measurement, while using pneumatic atuofocus performs similar to Aligner: Maskless 01. It is thus recommended to use pneumatic autofocus for the first print if crystal alignment is important for subsequent processing.
+|-
+|-style="background:WhiteSmoke; color:black"
+|Optical autofocus
+after hardware upgrade February 2020
+| -0.3 mRad
+| ±1.4 mRad
+±0.08°
-'''Result of using only the alignment tool, pushing it to the extremes:'''
+|-
+|-style="background:WhiteSmoke; color:black"
+|Pneumatic autofocus
+after hardware upgrade February 2020
+| -0.6 mRad
+| ±1.4 mRad
+±0.08°
--11.08 to 5.54mRad, corresponding to -0.6 to 0.3°, average -0.1±0.5° (6 measurements, including 2 without pushing the alignment tool). Measured using pneumatic autofocus. This should be compared to the ±1° crystal alignment spec of the SEMI wafer standard.
+|}
-It would seem that applying the flat angle measured with optical autofocus to the print introduces more error than relying only on the alignment tool.
+This shows that using optical autofocus significantly increases the error on the flat measurement, while using pneumatic atuofocus performs similar to Aligner: Maskless 01. Initially, it was thus recommended to use pneumatic autofocus (or rely only on the alignment tool) for the first print if crystal alignment is important for subsequent processing. However, after the autofocus hardware and software upgrade in February 2020, the two methods yield equally good results.
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