what it means by a double grounded substrate

hello,

i am not able to get the meaning of a double grounded Neltec NY9217 substrate. as mentioned in the research paper i am working with. could u please help me with this problem.

thank you

I'm not sure in which context you are asking your doubt. If its physical design, we usually have different VSS domains. From one domain to another domain we keep a margin of X um depending upon the technology node.

Double grounded is sometimes used to mean that the substrate has a conductive cladding on both sides (top and bottom). It depends on the use, though.