A phaser drill was an excavation device employing phaser technology to drill holes into rock formations or a planet's mantle. The device employed tripods to stabilize it during firing. Given it's size was built with a longer lasting or more powerful energy supply than a typical weapon phaser.
In many instances a starship's phasers were employed to act as a drill. In 2367 the USS Enterprise-D used it's main phasers as a drill 1.6 kilometers underground to access the protected bunker on Turkana IV to rescue hostages. In 2368, the Enterprise-D used it's phasers to bore holes into the mantle of Penthara IV to release carbon dioxide located in subterranean pockets. The tectonic stability of the planet was overestimated, however, and the drilling caused massive earthquakes and volcanic outbreaks. (TNG: "A Matter of Time")