I need to realize a double gate finFET with a metal gate (WTi). My oxide is the HfO2. I tried a simple oxigen cleaning followed by a sputtering of the metal, but the adhesion was very poor and when I tried to achieve double gate separation with CMP it got detached. Should I try with a thin interlayer (Cr, Ti, TiN)?
I cannot use a softer metal because it has to withstand a successive annealing.
Added détails: The thickness of the WTi layer is 500 nm, while the oxide is 3 nm ALD HfO2 on a 1 um thick silicon dioxide layer. I did not perform any post-deposition processing or anneal (I directly tried the CMP that detached it), do you think it would help? Which parameters should I use? The pressure of deposition for the sputteting of WTi is 5e-2 mbar.
Thanks in advance
W and particularly Ti shouldn't have a problem adhering to oxides. How thick are they? What post-deposition processing and anneal did you perform? What was the base pressure for metal deposition?
I would suggest putting down a thin layer of Ti first, since it is part of your alloy layer.
I suggest you to grow very thin layer of Cr as buffer layer, as It will cause good adhesion to your metal gate system.
Я предлагаю Вам сделать мягкий отжиг титана в среде водорода. Температура отжига до 600 С, расход водорода 10-15 дм кубических в минуту, время выбирается экспериментально по результатам адгезии.
I assume 5e-2 mbar is the sputtering pressure; what is the system's base pressure? (i.e., the lowest pressure before you introduce Ar)
What's your gas purity?
Was the surface smooth before CMP?
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