Using align_weak for bad marks
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You might have low-contrast marks if you did not etch deep enough, or if you accidently used copper instead of gold, etc. Instead of using the EBPG's built-in alignment routine (mvm) you can use align_weak.sh, a program that gathers image frames, averages them, and then searches the image for a rectangular mark. Your marks have to be rectangles, and there must be some contrast, but you can do a lot more averaging than you can with the usual "mvm" command. The accuracy will not be as good, but you might save the day.
Note that the accuracy of align_weak.sh is limited by the images. If you collect a 30x30 um image with 1024x1024 pixels, then the pixel size will be 29 nm. The largest bitmap size is 1024x1024, and alignment accuracy cannot be better than one pixel.
(If your marks have almost no contrast, try turning on the secondary detector.)
(If your marks have high contrast but are weird shapes, then you need a different solution. Look for the tip about correlation alignment.)
How to use the align_weak script:
1. Find the script in /public (on the ebpg) and make a copy in your own directory.
cp /public/align_weak_p20.sh align_weak.sh
Notice that we renamed the file to "align_weak.sh" when we copied it. That's the name associated with the mark type "weak", found in cjob. (For our friends outside of Yale, you can find this script in the ebpg funpak. Read the installation instructions at the top of the script.)
2. We have already defined a new mark type called "weak," so you do not need to create a new mark type. You can use the mark type "weak" which points to ./weak_mark.sh Note that "weak" points to the copy of weak_mark.sh in the current directory, " ./ " You will find "weak" as a mark type in cjob, and you can use "weak" in commands such as
mvm 0,0 --rel weak
By default, the script is set up for a positive (bright) 20 um mark, so you might have to edit the script to change a few parameters:
gedit align_weak.sh
The size might be different, and the "polarity" might have to be "dark" instead of "bright". Be sure to edit your local copy. DO NOT edit the original in /public. That would be rude.
3. Now you can test the script by moving to your horrible mark with
mvm 0,0 --rel weak
sp horrible
(In this example, "sp" saves the mark position in the symbol "horrible")