  Using the Lindemann criterion, we analyzed the quantum and thermal melting of
electronic/excitonic crystals recently discovered in two-dimensional (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
wavelength 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 critical temperature ranging from
several tens Kelvin to above 100 K (depending on the system parameters).
