Semiconductor devices including lids having liquid-cooled channels and methods of forming the same are disclosed. In an embodiment, a semiconductor device includes a first integrated circuit die; a lid coupled to the first integrated circuit die, the lid including a plurality of channels in a surface of the lid opposite the first integrated circuit die; a cooling cover coupled to the lid opposite the first integrated circuit die; and a heat transfer unit coupled to the cooling cover through a pipe fitting, the heat transfer unit being configured to supply a liquid coolant to the plurality of channels through the cooling cover.