Patent ID: 8258625

Claim:
A semiconductor device including a connection structure for connecting a fine pitch electrode at 50 μm pitch or less disposed on a semiconductor element and a pad or a wiring disposed on a substrate for mounting the semiconductor element, wherein the connection structure includes a structure connected on one side thereof to the fine pitch electrode and connected on the other side thereof to the pad or the wiring disposed on the substrate by way of a bump having a longitudinal elastic modulus (Young's modulus) of 65 GPa or more and 600 GPa or less and a buffer layer including at least one of tin, aluminum, indium, or lead as a main ingredient, wherein a protruding shape is provided on at least one of opposing surfaces of the bump and the pad or the wirings disposed on the substrate to provide unevenness to said at least one of the opposing surfaces, wherein the bump and the buffer layer are connected to one another by applying an ultrasonic wave in a state that a load is applied to the buffer layer disposed on the pad or the wiring, and wherein the bump and the pad or the wiring are connected to each other and the buffer layer is provided between the bump and the pad or the wiring and is comprised of a plurality of structures having a protruding shape corresponding to the protruding shape of the at least one surface of the bump or the pad or the wiring to provide unevenness to the buffer layer.