The projection has a shape extending along a first surface of a substrate. Furthermore, the projection includes one linear top edge which is located away from the first surface, two main lateral faces which have the top edge in common with each other, the two main lateral faces having lateral edges, each lateral edge individually connecting the first end of the top edge and the first surface, and an auxiliary lateral face which has the lateral edges in common with the respective main lateral faces and forms one corner together with the two main lateral faces, an angle made between the lateral edge and the top edge on the main lateral face is an obtuse angle, and an angle made between the two lateral edges on the auxiliary lateral face is an acute angle.
