Is It possible to submit design into new SKY90-FD 90nm? If so, how can I do that? Thank you

It's not ready yet - and no info on when it will be...

yeah... the 90nm technology node has been published by Skywater / Google , but at least to my knowledge hasnt been used yet at the mpw runs... I think its mostly due to money and like @Matt Venn said, its not ready for use yet... Most projects here are totally fine with a larger process node... But time will tell, if its going to be used. The only benefit for this community here would be the copper interconnect, which should allow for higher switching speeds. https://github.com/google/sky90fd-pdk

I think the fact that it is FDSOI makes it a very interesting process compared to bulk CMOS. We'll make announcements as the development of the process and PDK progresses, but right now it's moving pretty slowly.