Texas Instruments Corporation

Kejun Zeng

Darvin R Edwards

Bernardo Gallegos

Tz-Cheng Chiu

Amit Sureshkumar Nangia

Robert John Furtaw

Rebecca L Holford

Wei Qun Peng

A method for fabricating a semiconductor device is disclosed. A packaged semiconductor device is provided having copper ball bonds attached to aluminum pads. The packaged device is treated for at least one cycle at a temperature in the range from about 250&#xb0; C. to 270&#xb0; C. for a period of time in the range from about 20 s to 40 s.

Corrosion-resistant copper bonds to aluminum

A metallic interconnect structure () for connecting a gold bump () and a copper pad (), as used for example in semiconductor flip-chip assembly. A first region () of binary AuSnintermetallic is adjacent to the gold bump. A region () of binary AuSnintermetallic is adjacent to the first AuSnregion. Then, a region () of binary gold-tin solid solution is adjacent to the AuSnregion, and a second region () of binary AuSnintermetallic is adjacent to the solid solution region. The second AuSnregion is adjacent to a nickel layer () (preferred thickness about 0.08 &#x3bc;m), which covers the copper pad. The nickel layer insures that the gold/tin intermetallics and solutions remain substantially free of copper and thus avoid ternary compounds, providing stabilized gold bump/solder connections.

Stable gold bump solder connections

A method for reducing gold embrittlement in solder joints, and a copper-bearing solder according to the method, are disclosed. Embodiments of the invention comprise adding copper to non-copper based solder, such as tin-lead solder. The embodiments may further comprise using the copper-bearing solder as a solder interconnect on a gold-nickel pad.

Method and structure to reduce risk of gold embrittlement in solder joints

A metal interconnect structure () comprising a bond pad (), which has copper with at least 70 volume percent composed of crystal grains expanding more than 1 &#x3bc;m in their main direction, and 30 or less volume percent composed of crystal grains, which expand less than 1 &#x3bc;m in their main crystal direction. A body () of tin alloy is in contact with the bond pad.

Solder joints for copper metallization having reduced interfacial voids

Method for assembling a semiconductor device having fatigue-resistant interconnection fillet provides a semiconductor chip with at least one solder bump comprising an alloy of tin and lead with a melting temperature higher than the solder paste used. Further, a solder paste (preferably binary) is provided, which comprises tin and about 2.5 weight percent silver, and has a melting temperature of about 221&#xb0; C. The solder bump is brought in contact with the solder paste, the bump is partially immersed in the paste, and thermal energy is supplied to reflow the solder paste at about 235&#xb0; C. The amount of energy and time after the reflow of the paste is controlled so that the molten paste dissolves a pre-determined amount of the solder bump (lead and tin) to form a ternary alloy of about eutectic composition (about 1.62 weight % Ag, 36.95 weight % Pb, 61.43 weight % Sn) without melting the solder bump.

Method of semiconductor device assembly including fatigue-resistant ternary solder alloy

A metal interconnection structure for semiconductor chips has a metal interface layer (), preferably nickel, deposited over the metal of the chip contact pad (, usually aluminum or copper). A subsequent metal layer () is an alloy of a metal such as copper or gold with nickel, wherein the quantity of nickel is selected so that it diminishes the interdiffusion rate of the nickel from the interface layer () during the reflow and annealing processes. Reflowable metal () for interconnection completes the structure. In another embodiment, the reflowable metal () contains an admixture of the interface metal in a quantity to diminish the interdiffusion rate of metal from the interface layer during the annealing process. In either embodiment, the formation of voids in the interface layer () is diminished.

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Coppell, TX, United States of America

Kejun Zeng