In an embodiment, a device includes: a semiconductor die including a semiconductor material; a through via adjacent the semiconductor die, the through via including a metal; an encapsulant around the through via and the semiconductor die, the encapsulant including a polymer resin; and an adhesion layer between the encapsulant and the through via, the adhesion layer including an adhesive compound having an aromatic compound and an amino group, the amino group bonded to the polymer resin of the encapsulant, the aromatic compound bonded to the metal of the through via, the aromatic compound being chemically inert to the semiconductor material of the semiconductor die.