  We present measurements of the self- and mutual inductance of NbN and bilayer
NbN/Nb inductors with Nb ground plane(s) fabricated in an advanced process for
superconductor electronics developed at MIT Lincoln Laboratory. In this
process, the signal traces of logic cell inductors are made either of a 200-nm
NbN layer with $T_c$=15 K or of an in-situ deposited NbN/Nb bilayer, replacing
a 200-nm Nb layer M6 in the standard SFQ5ee process with nine superconducting
layers. Nb ground planes were preserved to maintain a high level of interlayer
shielding and low intralayer mutual coupling. A two-step patterning of the top
Nb and the bottom NbN layers of the NbN/Nb bilayer allows to create inductors
in a very wide range of linear inductance values, from low values ~ 0.4
pH/$\mu$m typical for Nb geometrical inductors to ~ 35 pH/$\mu$m typical to
thin-film kinetic inductors. Mutual inductance of NbN and Nb inductors, of NbN
inductors, and of bilayer inductors is the same as between two Nb inductors
with the same geometry and placement between the ground planes, i.e., mutual
inductance does not depend on superconducting properties of the signal traces
in the studied range of linewidths. We measured magnetic field penetration
depth and kinetic inductance of NbN films with thickness t=200 nm to be
$\lambda$ = 491+/-5 nm and 1.51 pH/sq, and 2.06 pH/sq at t=150 nm. The kinetic
inductance was found to be larger than that expected for superconductors with
short mean free path, indicating a reduction in the superfluid density, likely
due to carrier localization effects. Kinetic inductance associated with
right-angled bends of the NbN inductors is negligible at linewidths
$w<{\lambda}^2/t$, indicating a very small current crowding in structures with
superconducting ground plane(s). Implementation of NbN and NbN/Nb inductors can
significantly increase integration scale of superconductor digital electronics.
