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'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php/Specific_Process_Knowledge/Lithography/EBeamLithography/Mix-and-match click here]'''
Content and illustration by DTU Nanolab unless otherwise noted.
Mix-and-match lithography is a process in which two lithography processes are combined to produce a pattern in a single resist layer. In this way one can for instance combine the high resolution of E-beam lithography with the high speed of UV lithography. Other combinations using DUV are also possible.
Mix-and-match lithography is a process in which two lithography processes are combined to produce a pattern in a single resist layer. In this way one can for instance combine the high resolution of E-beam lithography with the high speed of UV lithography. Other combinations using DUV are also possible.


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{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;"
{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;"
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| [[image:MixMatch.png|1044px]]
| [[image:MixMatch2.png|800px]]
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The two different methods for pattern alignment. Image: Thomas Pedersen.
The two different methods for pattern alignment.  
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==Alignment accuracy==
Alignment accuracy is governed by the precision with which one can determine the center of the faint exposed marks and the inherent alignment accuracy of the MLA system. Typical accuracy is found to be +/- 250 nm in both x and y.
 
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| [[image:thope231127thin07.png|400px]] | [[image:thope231127thin08.png|400px]] | [[image:thope231127thin03.png|400px]]
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Left and center: Vernier scales for measurement of alignment accuracy. Right: Waveguide where the left side is written by UV and the right side by E-beam.  
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===Test process===
===Test process===
Resist used is nLOF2020 diluted in a ratio of 27 grams of resist mixed with 51 grams of PGMEA. The resist is spin coated on Labspin 2 at 2000 RPM for 1 min (1000 RPM/s acceleration). The wafer is then soft baked at 110C for 60 seconds.
Resist used is nLOF2020 diluted in a ratio of 27 grams of resist mixed with 51 grams of PGMEA. The resist is spin coated on Labspin 2 at 2000 RPM for 1 min (1000 RPM/s acceleration). The wafer is then soft baked at 110C for 60 seconds. Resist thickness is 250 nm.




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A test pattern is exposed with doses from 100 to 600 µC/cm<sup>2</sup>. After EBL exposure a UV test pattern is exposed on MLA2 utilizing alignment to the exposed resist. After exposure the wafer is developed on Developer: TMAH UV-Lithography using recipe 3005, i.e. a 60 second PEB at 110C and 30 sec single puddle development cycle.
A test pattern is exposed with doses from 100 to 600 µC/cm<sup>2</sup>. After EBL exposure a UV test pattern is exposed on MLA2 utilizing alignment to the exposed resist. After exposure the wafer is developed on Developer: TMAH UV-Lithography using recipe 3005, i.e. a 60 second PEB at 110C and 30 sec single puddle development cycle.


===Contrast curve===
===Contrast curve===
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{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;"
{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;"
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| [[image:IMAGE74_540.png|300px]] || [[image:IMAGE825_540.png|300px]] || [[image:IMAGE768_540.png|300px]] || [[image:IMAGE847_540.png|300px]]
| [[image:250nmnLOF.png|800px]]
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| colspan="1" style="text-align: center;|
250 nm nLOF2020 contrast curve from exposure at 100 kV on JEOL 9500.
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===Example images (250 nm)===
The pattern is written at 6 nA with 10 nm beam pitch, i.e. a fairly high beam pitch in order to accomodate a large dose variation in one sequence. Initial test provides fair definition of lines down to 100 nm, the high line error roughness is most likely from the high beam pitch. A few example images are given below, all from 540 µC/cm<sup>2</sup>.
 
{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;"
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| [[image:nLOF_250nm_1.png|300px]] || [[image:nLOF_250nm_3.png|300px]] || [[image:nLOF_250nm_2.png|300px]] || [[image:nLOF_250nm_4.png|300px]]
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|-  
| colspan="4" style="text-align: center;|
| colspan="4" style="text-align: center;|
Example images from left to right: 100 nm lines (4 µm FOV), 150 nm lines (4 µm FOV), 100 nm vernier scale lines (25 µm FOV), cartoon figures (25 µm FOV). Image: Thomas Pedersen.
Example images from left to right: 100 nm lines, 150 nm lines, 100 nm vernier scale lines, cartoon figures. Image: Thomas Pedersen.
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===Example images (1500 nm)===
Undiluted nLOF2020 can also be used, in this case a 1500 nm thick resist is exposed at 160 µC/cm<sup>2</sup>. While it is possible to define lines down to about 100 nm the high aspect ratio will cause free standing lines to collapse as illustrated below.


===Example images===
{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;"
The pattern is written at 6 nA with 10 nm beam pitch, i.e. a fairly high beam pitch in order to accomodate a large dose variation in one sequence. Initial test provides fair definition of lines down to 100 nm, the high line error roughness is most likely from the high beam pitch. A few example images are given below, all from 540 µC/cm<sup>2</sup>.
|-
| [[image:nLOF_1500nm_1.png|300px]] || [[image:nLOF_1500nm_2.png|300px]]
|-
| colspan="4" style="text-align: center;|
100 nm lines in 1500 nm thick nLOF2020.  
|}
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