| CPC H01L 24/05 (2013.01) [H01L 24/03 (2013.01); H10F 39/024 (2025.01); H10F 39/805 (2025.01); H10F 39/811 (2025.01); H01L 2224/05011 (2013.01); H01L 2224/05576 (2013.01); H01L 2924/01013 (2013.01); H01L 2924/01029 (2013.01)] | 8 Claims |

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1. A semiconductor device, comprising:
a pad including a concave portion on a surface, wherein the pad is for a solder connection;
a diffusion layer at the concave portion, wherein the diffusion layer comprises a first metal;
a melting layer adjacent to the diffusion layer, wherein
the melting layer comprises a second metal, and
the melting layer diffuses and melts into a solder upon the solder connection; and
a diffusion prevention layer between the pad and the diffusion layer, wherein
the diffusion prevention layer comprises a third metal,
the diffusion prevention layer prevents diffusion of the pad into the solder upon the solder connection, and
the diffusion layer remains on a surface of the diffusion prevention layer upon the solder connection.
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