Cliptin,
you can make cells any size you want. 0.15um had some support because 0.18um lithography tools could be re-used with some re-jigging to "scribe" the smaller photomasks (gross simplification).
0.13um was too big a step as the light wavelengths used were too large. Every semi-con company I know has at some stage tried to re-use there lithography tools (or most of them) for the next generation to save costs - because these tools cost tens and hundreds of millions.
Intel did it at 0.25 to 0.18 and invested in new tools for 0.13 - and plans to use their 0.13 tools for 0.09 - bugger that 190nm.
AMD had new tools for 0.18um (partly becasue of the change to Cu) and I think showed how big a lead they had.
AMD re-used there 180nm tools for 130nm and it showed - the AMD 130nm process isn't as good as Intels. It will probably change back to AMD's favour at 90nm. The 90nm Hammers should be something special.
But back to your question, there was a talk of 150nm stuff, but the chip race was in full swing and while yields bin/splits and costs would certainly have been better for AMD if they hadn't been so ambitious, it's the top speed chips that garner revenue so there hand was forced.
Debugging a new chip fabrication process is costly and time consuming, so they probably bit the bullet.
NVIDIA and ATi are in this up to there necks as well. ATi banked on a stable and mature 150nm process, NVIDIA took a gamble. NVIDIA lost. if and when we see GeForceFX, it should clock insanely, but by the time NVIDIA (or more correctly TSMC) can get enough of them into the hands of consumers, ATi will most likely have a 130nm part AND a new revision of the Radeon, so when things matter to profits - ATi will be a contender.
But what would I know...
