Semiconductor device
Circuit elements are formed in a semiconductor chip ( 1 ) and an electrode pad ( 11 ) for connection with outside is formed on the periphery of a surface of the semiconductor chip ( 1 ). On the other hand, a wiring ( 21 ) is formed on one surface of an insulating substrate ( 2 ) and an external connecting terminal ( 22 ) is formed on the other surface thereof, being connected to the wiring ( 21 ). The electrode pad ( 11 ) of the semiconductor chip ( 1 ) and the wiring ( 21 ) are bonded by an Au—Sn alloy layer ( 3 ) at the connection section thereof. As a result, there is obtained a semiconductor device of a CSP type with a structure capable of connecting the semiconductor chip and the insulating substrate to each other without applying a large pressure and a high temperature thereto, and forming a circuit element even below the electrode pad and in the vicinity thereof to enable high integration.
1. A semiconductor device comprising:
a semiconductor chip in which circuit elements are formed and on the periphery of which an electrode pad having a bump consisting essentially of Au thereon for connection with outside is formed;
an insulating substrate on one surface of which a wiring is formed, said wiring having an Au layer on a surface of a connecting section with said bump, and on the other surface of which a ball like external connecting terminal is formed being connected to said wiring, said ball like external connecting terminal being directly connected to a wiring board; and
a Sn coat provided on a surface of said bump or a surface of said Au layer of said wiring,
wherein said bump and said connecting section of said wiring are bonded with each other through an Au—Sn alloy layer which is made of said Sn coat and the Au of said bump or said wiring and said wiring comprises a first layer made of a Cu film and a second layer made of Au formed by electroplating on said first layer with said first layer disposed between said second layer and said insulating substrate.
2. The semiconductor device according to claim 1 , wherein an intermediate metal layer is provided between said electrode pad and said bump, said intermediate metal layer comprising a first layer made of Ti or Cr and a second layer made of W, Pt, Ag, Cu or Ni.
3. The semiconductor device according to claim 1 , wherein an intermediate metal layer is provided between said electrode pad and said bump, said intermediate metal layer comprising Ti—W alloy layer.
4. The semiconductor device according to claim 1 , wherein said alloy layer is composed of an alloy layer containing Au at a content of 65 wt % or more.
5. The semiconductor device according to claim 1 , wherein said Sn coat is provided only on a bonding section of said wiring in a spot manner.
6. The semiconductor device according to claim 1 , wherein a gap between said semiconductor chip and said insulating substrate is filled with insulating resin made of epoxy resin or elastomer.
7. The semiconductor device according to claim 6 , wherein there is formed a package for covering said semiconductor chip on said insulating substrate, said package made of resin.
8. The semiconductor device according to claim 1 , wherein a plurality of ball like external connecting terminals, each of which is said ball like external connecting terminal, are provided, and said ball like external connecting terminals are distributed all over said insulating substrate, so that said semiconductor device is directly mounted on a wiring board while said plurality of ball like external connecting terminals are connected to wirings of said wiring board.