A semiconductor package includes a first semiconductor chip stacked on a second semiconductor chip. The first semiconductor chip includes a first substrate, a first insulating layer on a lower surface of the first substrate, and a first pad exposed through the first insulating layer. The second semiconductor chip includes a second substrate, a second insulating layer on an upper surface of the second substrate contacting the first insulating layer, and a second pad exposed through the second insulating layer contacting the first pad. The first pad has an inclined side surface and a first width that increases toward the first substrate, and the second pad has an inclined side surface and a second width that increases toward the second substrate.