Grrrarrgghh@#%!!!!!! (part 2)
You should probably read the previous post before this one.
I got in on Tuesday morning fully confidant that I could still manage to have both samples tested by my Thursday deadline. I had a new developer recipe and I had decided to bend the rules slightly and use the nicer contact aligner. I've asked for explicit permission to use the better aligner several times now, but I've just been ignored. Meanwhile, no one else seems to pay any attention to the sign on the door which says who can use the aligner. I hate to cross a line that I'm not technically supposed to, but I can simply no longer get by with the other machine, it just doesn't work well enough to process these devices.
And the nicer machine is MUCH nicer. The action on the arm swinging forward is so smooth that it couldn't possibly knock the sample out of alignment, even if it was in poor contact. And as a bonus, the microscope actually focuses! Aligning an 8 micron by 8 micron square on top of a 10 micron by 10 micron square is much easier when you can see them. It takes roughly an hour to align and expose two samples on the micro aligner, I can do it in 20 minutes on the nano aligner. It was so much easier, it felt like I was somehow cheating.
Of course, the developer recipe failed miserably. Completely washed away the photoresist squares that were supposed to protect the devices from the SiO2 I needed to deposit next. It took two more tries on each one to finally dilute the developer enough that it didn't destroy the pattern completely, and even then it looked terrible, but it looked like at least 50% of the devices would survive.
The next machine I needed was in use. I came back that night and deposited the insulator without issue. As I expected, very few of the device looked like they survived this far.
Wednesday morning I just needed to do one more step. I was able to do the exposure in two tries (more developer issues), and Paul and I went to deposit the Nb contact layer. The Ion Mill was acting funny, but we pressed on. The Nb came out with a distinct blue tint, but we pressed on (no one listens to me when I say that something looks like it's colored funny). It took until nearly 5 pm.
While soaking the samples in acetone to lift off the unnecessary Nb, I began to stake out my claim on the testing equipment since I knew I was going to need to be there all night. Turns out Soren and Kevin both wanted it too. Well, too bad for them, I've got a deadline.
Except that it turned out I wouldn't be needing it afterall. All of the Nb I had deposited lifted off, not just the unnecessary parts, meaning that there was no way to contact the samples for testing and I would need to repeat the entire step. At this point Paul said to forget it, the sample looked awful and unless we could get a reliable developer recipe and figure out what was wrong with the Nb we would never get any useful info out of the samples.
It turns out that the machine was just out of Nb and we were actually sputtering the Nb container onto our sample. See, I told you it looked weird.
*sigh*
-Tim
I got in on Tuesday morning fully confidant that I could still manage to have both samples tested by my Thursday deadline. I had a new developer recipe and I had decided to bend the rules slightly and use the nicer contact aligner. I've asked for explicit permission to use the better aligner several times now, but I've just been ignored. Meanwhile, no one else seems to pay any attention to the sign on the door which says who can use the aligner. I hate to cross a line that I'm not technically supposed to, but I can simply no longer get by with the other machine, it just doesn't work well enough to process these devices.
And the nicer machine is MUCH nicer. The action on the arm swinging forward is so smooth that it couldn't possibly knock the sample out of alignment, even if it was in poor contact. And as a bonus, the microscope actually focuses! Aligning an 8 micron by 8 micron square on top of a 10 micron by 10 micron square is much easier when you can see them. It takes roughly an hour to align and expose two samples on the micro aligner, I can do it in 20 minutes on the nano aligner. It was so much easier, it felt like I was somehow cheating.
Of course, the developer recipe failed miserably. Completely washed away the photoresist squares that were supposed to protect the devices from the SiO2 I needed to deposit next. It took two more tries on each one to finally dilute the developer enough that it didn't destroy the pattern completely, and even then it looked terrible, but it looked like at least 50% of the devices would survive.
The next machine I needed was in use. I came back that night and deposited the insulator without issue. As I expected, very few of the device looked like they survived this far.
Wednesday morning I just needed to do one more step. I was able to do the exposure in two tries (more developer issues), and Paul and I went to deposit the Nb contact layer. The Ion Mill was acting funny, but we pressed on. The Nb came out with a distinct blue tint, but we pressed on (no one listens to me when I say that something looks like it's colored funny). It took until nearly 5 pm.
While soaking the samples in acetone to lift off the unnecessary Nb, I began to stake out my claim on the testing equipment since I knew I was going to need to be there all night. Turns out Soren and Kevin both wanted it too. Well, too bad for them, I've got a deadline.
Except that it turned out I wouldn't be needing it afterall. All of the Nb I had deposited lifted off, not just the unnecessary parts, meaning that there was no way to contact the samples for testing and I would need to repeat the entire step. At this point Paul said to forget it, the sample looked awful and unless we could get a reliable developer recipe and figure out what was wrong with the Nb we would never get any useful info out of the samples.
It turns out that the machine was just out of Nb and we were actually sputtering the Nb container onto our sample. See, I told you it looked weird.
*sigh*
-Tim
posted by tjmcardl | 5:39 PM
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