Wire-bonding method for chips with copper interconnects by introducing a thin layer

Abstract

A wire-bonding method for chips with copper interconnects by introducing a thin layer is provided for solving the problem of oxidizing a copper bonding-pad during bonding processing in order not to deteriorate the bonding strength and yield rate thereof. The wire-bonding method of the present invention comprises: a step for providing a chip with a copper bonding-pad; another step for providing an aqueous solution to form a Cuprous oxide thin layer on the copper bonding-pad; and yet another step for setting a plurality of copper interconnects on the copper bonding-pad and providing an ultrasonic power for removing the Cuprous oxide layer to have the interconnects bonded on the copper bonding-pad.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to the application field regarding IC packaging, particularly to a wire-bonding method for chips with copper interconnects by introducing a thin layer. [0003] 2. The Prior Arts [0004] In the VLSI (Very Large Scale Integration) era today, an IC chip is made through several steps including wafer fabricating process, wafer test, VLSI forming process, and finally, IC packaging test. [0005] The packaging test usually comprises a wafer attachment process, a wire-bonding process, etc., in which the wire-bonding process is conducted by a wire bonder for connecting a chip to a plurality of pins with metallic interconnects under a high-temperature and ultrasonic environment. The bonded interconnects serve as a bridge for transmitting signal and / or electric power between a chip and the external circuits. Since, almost all the makers have made different efforts to try minimizing the volume of chip ...

AI Technical Summary

Benefits of technology

[0008] The primary object of the present invention is to provide a wire-bonding method for chips with copper interconnects by introducing a thin layer to prevent the problem of oxidizing a copper bonding-pad during a bonding process.

[0010] The wire-bonding method for chips with copper interconnects by introducing a thin layer is advantageous in that a Cuprous oxide layer formed on the copper bonding-pad can prevent the pad from being oxidized further, and the layer is removable by ultrasonic power to ensure a better wire bonding.

[0011] With a proper control of pH value, the aqueous solution can work to produce the Cuprous oxide layer on the copper bond-pad in a low cost.

Problems solved by technology

On the other hand, the performance of deep sub-micron integrated circuit cannot be further improved since the delay of signal in the interconnect would exceed the delay of signal in the device.

However, one of the disadvantages of copper is that copper is readily oxidized at low temperature, and unlike the oxidation of aluminum, the oxidation rate of copper is fast, and no self-protective oxide layer forms to prevent further oxidation.

These ways are capable of avoiding oxidation of the copper bonding-pad and enhancing the strength of bonding points though, they are both expensive and troublesome.

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