With same area, of course MOM capacitor with shorter space has larger capacitance value . Why foundry provides MOM capacitor with larger space, and what's the benefit?
MOM are used when MIM are absent or incapable of the voltage.
If you mean to use high voltages then your interconnect and
interlevel dielectric become "reliability items" where before, at
low voltage, they were not.
Presumably with two different rules for one structure, there
would be some reason given and some application guidance
for when / why to use. Maybe you should read it. Of if you
really can't find it, ask the foundry applications people.
MOM are used when MIM are absent or incapable of the voltage.
If you mean to use high voltages then your interconnect and
interlevel dielectric become "reliability items" where before, at
low voltage, they were not.
Presumably with two different rules for one structure, there
would be some reason given and some application guidance
for when / why to use. Maybe you should read it. Of if you
really can't find it, ask the foundry applications people.