  The number of exoplanet detections continues to grow following the
development of better instruments and missions. Key steps for the understanding
of these worlds comes from their characterization and its statistical studies.
We explore the metallicity-period-mass diagram for known exoplanets by using an
updated version of The Stellar parameters for stars With ExoplanETs CATalog
(SWEET-Cat), a unique compilation of precise stellar parameters for planet-host
stars provided for the exoplanet community. Here we focus on the planets with
minimum mass below 30 M$_{\oplus}$ which seems to present a possible
correlation in the metallicity-period-mass diagram where the mass of the planet
increases with both metallicity and period. Our analysis suggests that the
general observed correlation may be not fully explained by observational
biases. Additional precise data will be fundamental to confirm or deny this
possible correlation.
