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Ultrahigh-Purity Copper and Process for Producing the Same, and Bonding Wire Comprising Ultrahigh-Purity Copper

a technology bonding wire, which is applied in the direction of process efficiency improvement, basic electric elements, and electrolysis components, can solve the problems of easy cracks in silicon during bonding, and achieve the effect of reducing hardness, thinning bonding wire, and efficient manufacturing of ultrahigh purity copper

Inactive Publication Date: 2009-11-05
JX NIPPON MINING& METALS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0018]As described above, the present invention yields a significant effect of being able to efficiently manufacture ultrahigh purity copper having a purity level of 8N (99.999999 wt %) or higher. It is thereby possible to reduce the hardness and obtain a copper material that is compatible with thinning (wire drawing).
[0019]In particular, thinning of a bonding wire for a semiconductor element is enabled. In addition, the present invention yields a superior effect of being able to prevent the generation of cracks in the silicon during bonding, inhibit the heat generation caused by the low resistance of the wires, and prevent the oxidization during heat treatment.
[0020]Since the improvement of corrosion resistance (oxidation resistance) will not require the heating atmosphere to be a strict Ar+H2 atmosphere, an additional effect is yielded in that the labor efficiency is also favorable.

Problems solved by technology

Although such heterophase deposits are extremely trivial in the ultrahigh purity copper, rupture will occur during the thinning process with such heterophase deposits as the origin.
In addition, since the Cu will harden, cracks will easily occur in the silicon during bonding.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0029]A bulk copper raw material having a purity level of 4N was used as the anode, and a copper plate was used as the cathode to perform electrolysis. The content of raw material impurities is shown in Table 1. As shown in Table 1, the copper raw material (4N) primarily contained large amounts of O, P and S. Table 1 also shows the hardness and recrystallization temperature at this impurity level. The hardness at a purity level of 4N was 45 Hv, and the recrystallization temperature was 450° C. The diameter of the wire rod capable of being subject to thinning was 200 μm. The wires at this level were hard and generated cracks in the silicon during bonding (adhesion).

[0030]A nitric acid series electrolytic solution having a bath temperature of 30° C. was used, and 1 ml / L of hydrochloric acid was additionally added thereto. Electrolysis was performed at a pH of 1.3, and a current density of 1 A / dm2. The electrolytic solution was circulated, the electrolytic solution of the circuit was t...

example 2

[0034]A bulk copper raw material having a purity level of 4N level was used as the anode, and a copper plate was used as the cathode to perform electrolysis. The content of raw material impurities is shown in Table 2. As shown in Table 2, the copper raw material (4N) primarily contained large amounts of O, P and S. Table 2 also shows the hardness and recrystallization temperature at this impurity level. The hardness at a purity level of 4N was 47 Hv, and the recrystallization temperature was 450° C. The diameter of the wire rod capable of being subject to thinning was 200 μm.

[0035]A nitric acid series electrolytic solution having a bath temperature of 25° C. was used, and 1 ml / L of hydrochloric acid was additionally added thereto. Electrolysis was performed at a pH of 2.0, and a current density of 1.5 A / dm2. The electrolytic solution was circulated, and, as with Example 1, the electrolytic solution of the circuit was temporarily cooled with a cooler to a temperature of 5° C., and a ...

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Abstract

Provided is ultrahigh purity copper having a hardness of 40 Hv or less, and a purity of 8N or higher (provided that this excludes the gas components of O, C, N, H, S and P). With this ultrahigh purity copper, the respective elements of O, S and P as gas components are 1 wtppm or less. Also provided is a manufacturing method of ultrahigh purity copper based on two-step electrolysis using an electrolytic solution comprised of copper nitrate solution, including the procedures of adding hydrochloric acid in an electrolytic solution comprised of copper nitrate solution; circulating the electrolytic solution; and performing two-step electrolysis while eliminating impurities with a filter upon temporarily setting the circulating electrolytic solution to a temperature of 10° C. or less. The present invention provides a copper material that is compatible with the thinning (wire drawing) of the above, and is capable of efficiently manufacturing ultrahigh purity copper having a purity of 8N (99.999999 wt %) or higher, providing the obtained ultrahigh purity copper, and providing a bonding wire for use in a semiconductor element that can be thinned.

Description

TECHNICAL FIELD[0001]The present invention relates to ultrahigh purity copper having a purity of 8N (99.999999 wt %) or higher that can be subject to thinning without breaking, and the manufacturing method of such ultrahigh purity copper. The present invention also relates to a bonding wire comprised of such ultrahigh purity copper.BACKGROUND ART[0002]Conventionally, a gold wire has been used as the bonding wire for electrically connecting a silicon chip as the semiconductor element and the lead frame. Nevertheless, from the perspective that a gold wire is expensive and the strength thereof is inferior to copper, proposals have been made for switching to a copper wire (Non-Patent Documents 1 and 2).[0003]High purity copper is characterized in that it is soft since the recrystallization temperature is low, it has favorable workability since there is hardly any brittleness in the intermediate temperature range, and it has high thermal conductivity since the electrical resistance is sm...

Claims

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Application Information

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IPC IPC(8): C22C9/00C25D21/06C25D3/38
CPCC22B15/0073C22B15/0084C22B15/0089C22C9/00C25C1/12C25C7/06H01L24/43H01L24/45H01L2224/05624H01L2224/43H01L2224/45147H01L2224/45565H01L2224/456H01L2224/45644H01L2924/01004H01L2924/01005H01L2924/01006H01L2924/01007H01L2924/01011H01L2924/01012H01L2924/01013H01L2924/01014H01L2924/01015H01L2924/01016H01L2924/01018H01L2924/0102H01L2924/01029H01L2924/01033H01L2924/0104H01L2924/01046H01L2924/01047H01L2924/01075H01L2924/01078H01L2924/01079H01L2924/01082H01L2924/01094H01L2924/01105H01L2924/01208H01L2924/10253H01L2924/14H01L2924/01019H01L2924/01072H01L2224/45144H01L2224/48624H01L2224/43848H01L2924/01008H01L2924/01205H01L2924/00011H01L2924/00014H01L2224/45647H01L2224/48824H01L2924/00H01L2924/00015H01L2924/013H01L2224/45015Y02P10/20H01L2924/20105H01L2924/20106H01L2924/20107H01L2924/2011H01L2924/20111H01L2924/01001
Inventor SHINDO, YUICHIROTAKEMOTO, KOUICHI
Owner JX NIPPON MINING& METALS CORP
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