Using the Lindemann criterion, we analyzed the quantum and thermal melting of
electronic and excitonic crystals recently discovered in 2D semiconductor
moir\'e patterns. We show that the finite 2D screening of the atomically thin
material can suppress (enhance) the inter-site Coulomb (dipolar) interaction
strength, thus inhibits (facilitates) the formation of the electronic
(excitonic) crystal. Meanwhile, a strong enough moir\'e confinement is found to
be essential for realizing the crystal phase with a lattice constant near 10 nm
or shorter. From the calculated Lindemann ratio which quantifies the
fluctuation of the site displacement, we estimate that the crystal will melt
into a liquid above a temperature in the order of several tens Kelvin