A few weeks ago I triumphantly announced on my blog that I had successfully sputtered an oxide. Our cleanroom is open weekdays from 9am to 4pm. I’ve been spending as much time in there as possible. I wasn’t skipping lunch but I was not giving myself time to enjoy it. I would inhale lunch and go back in. Then, after 4pm I would go home exhausted. Another process step that I need to perfect is sputtering Gold. Unfortunately Gold doesn’t stick and needs an adhesion layer. The adhesion layer can be either Titanium or Chrome. I had done three sets of sputter runs of oxide, adhesion layer and Gold as well as lithography and etch. The first set worked out. The second and third peeled off. That means my first set is pretty useless because the processing steps I used to make it are not reliable.
It seems I need more adhesion. If I increase the thickness of the adhesion layer then the oxide metal interface will be dominated by the adhesion layer’s characteristics and not Gold. That’s not necessarily bad but not something I had considered. In our bi-weekly group meeting my advisor asked me how thick does Titanium have to be to dominate and I drew a blank. It’s important because when I do Capacitance-Voltage measurements on my oxide I need to know what my flatband voltage should be to determine how far off I am.
Also, I was talking to one of our cleanroom technicians and describing the issues I was facing and he listed of a few more concerns about the skin depth. Since I’ll be running AC signals on my metal lines I need to make sure I have enough Gold deposited so that the signal carries on the Gold and not the adhesion layer. I had planned the signals to be on Gold because it is inert, the particles in solution should not stick to it.
The point is that I’m getting damn frustrated. Colleagues of mine who started around when I did are concerning themselves with publications, conferences, writing, presentations and my Gold isn’t sticking. Did I mention my design requires three metal layers separated by oxide? My lithography masks came back the first time unusable. There’s no guarantees the next run will go any better. I feel like crap. My migraines are flaring. I got another urine infection. In addition to professional issues I have personal issues to deal with too.
Swimming has helped, as has volleyball and soon tennis. I forgot to mention I guess that our new apartment has an outdoor swimming pool and that I have acquired one of those muslim bathing suits. However more reinforcements and adjustments are needed in order to be successful I think. First off, I will need to read more. I will need to thoroughly research process steps before I go and try them on my own. There are other things of course but I will start with that.
