Devices and methods of packaging semiconductor devices are disclosed. In some embodiments, a device includes a first semiconductor device and a second semiconductor device coupled to the first semiconductor device. An underfill material is disposed between the first semiconductor device and the second semiconductor device. The underfill material is also disposed on sidewalls of the first semiconductor device and the second semiconductor device. The underfill material has a first thickness on sidewalls of the first semiconductor device and a second thickness on sidewalls of the second semiconductor device. The second thickness is different than the first thickness.