hi,
i didn't understand your question fully...for a such a big cap 30pf, apart from moscap there is no other option. I know it has max and min value that doesn't mean it shouldn't be used as a cap. MIM or MOM are very difficult from area point of view (i can say impossible also). Other wise go for some active circuit which can multiply you small value of cap and gives you 30p.

Thanks,
Rajasekhar.