U.S. patent application number 11/664058 was filed with the patent office on 2008-02-28 for au alloy bonding wire.
Invention is credited to Jun Chiba, Hiroshi Murai, Satoshi Teshima.
Application Number | 20080050267 11/664058 |
Document ID | / |
Family ID | 36118949 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080050267 |
Kind Code |
A1 |
Murai; Hiroshi ; et
al. |
February 28, 2008 |
Au Alloy Bonding Wire
Abstract
Provided is a thin Au alloy bonding wire having desired
strength, good bondability and stability over time, and improved
circularity of a squashed ball and sphericity of a melted ball. The
Au alloy bonding wire contains, in an Au alloy matrix containing
0.05 to 2 mass % in total of at least one selected from Pd and Pt
of high purity in Au of high purity, as trace elements, 10 to 100
ppm by mass of Mg, 5 to 100 ppm by mass of Ce, and 5 to 100 ppm by
mass of each of at least one selected from Be, Y, Gd, La, Eu and
Si, the total content of Be, Y, Gd, La, Eu and Si being 5 to 100
ppm by mass, or as trace elements, Mg, Be, and at least one
selected from Y, La, Eu and Si, or as trace elements, 10 to 100 ppm
by mass of Mg, 5 to 30 ppm by mass of Si, 5 to 30 ppm by mass of
Be, and 5 to 30 ppm by mass of at least one selected from Ca, Ce
and Sn.
Inventors: |
Murai; Hiroshi; (Saga,
JP) ; Chiba; Jun; (Saga, JP) ; Teshima;
Satoshi; (Saga, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
36118949 |
Appl. No.: |
11/664058 |
Filed: |
September 28, 2005 |
PCT Filed: |
September 28, 2005 |
PCT NO: |
PCT/JP05/17819 |
371 Date: |
March 29, 2007 |
Current U.S.
Class: |
420/508 ;
257/E23.025; 420/510 |
Current CPC
Class: |
H01L 2924/01057
20130101; H01L 2924/01065 20130101; H01L 2924/01015 20130101; H01L
2924/01033 20130101; H01L 2924/20752 20130101; H01L 2224/85439
20130101; H01L 2924/01203 20130101; H01L 2924/01032 20130101; H01L
2924/01079 20130101; H01L 2224/48639 20130101; H01L 2924/01042
20130101; H01L 2924/01024 20130101; H01L 2924/01064 20130101; H01L
2924/01051 20130101; H01L 2924/01058 20130101; B23K 35/3013
20130101; H01L 2924/20751 20130101; H01L 2924/01077 20130101; H01L
24/45 20130101; H01L 2924/0105 20130101; H01L 2924/01046 20130101;
H01L 2924/01063 20130101; H01L 2224/45144 20130101; H01L 2924/01205
20130101; H01L 2924/01023 20130101; C22C 5/02 20130101; H01L
2924/01044 20130101; H01L 2924/01078 20130101; H01L 2924/14
20130101; H01L 2924/19043 20130101; H01L 2924/01021 20130101; H01L
2924/01066 20130101; H01L 2924/01025 20130101; H01L 2924/0103
20130101; H01L 2924/01028 20130101; H01L 2924/10253 20130101; H01L
2924/181 20130101; H01L 2924/00011 20130101; H01L 24/43 20130101;
H01L 2924/01083 20130101; H01L 2924/01105 20130101; H01L 2924/01027
20130101; H01L 2224/05624 20130101; H01L 2924/01004 20130101; H01L
2924/01047 20130101; H01L 2924/01327 20130101; H01L 2924/01082
20130101; H01L 2224/45015 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/01029 20130101; H01L 2924/01202
20130101; H01L 2924/01013 20130101; H01L 2924/1576 20130101; H01L
2924/0107 20130101; H01L 2924/0102 20130101; H01L 2924/014
20130101; H01L 2224/48624 20130101; H01L 2224/45144 20130101; H01L
2924/01046 20130101; H01L 2224/45144 20130101; H01L 2924/01014
20130101; H01L 2224/45144 20130101; H01L 2924/01063 20130101; H01L
2224/45144 20130101; H01L 2924/01004 20130101; H01L 2224/45144
20130101; H01L 2924/01058 20130101; H01L 2224/45144 20130101; H01L
2924/01064 20130101; H01L 2224/45144 20130101; H01L 2924/01012
20130101; H01L 2224/45144 20130101; H01L 2924/01039 20130101; H01L
2224/45144 20130101; H01L 2924/01057 20130101; H01L 2224/45144
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/01201 20130101; H01L 2224/05624 20130101; H01L 2924/00014
20130101; H01L 2224/45015 20130101; H01L 2924/20752 20130101; H01L
2224/45015 20130101; H01L 2924/20751 20130101; H01L 2224/45144
20130101; H01L 2924/0102 20130101; H01L 2224/45144 20130101; H01L
2924/01066 20130101; H01L 2224/45144 20130101; H01L 2924/0103
20130101; H01L 2224/45144 20130101; H01L 2924/0105 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01012
20130101; H01L 2924/01039 20130101; H01L 2924/01046 20130101; H01L
2924/01058 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01012 20130101; H01L 2924/01046 20130101; H01L
2924/01058 20130101; H01L 2924/01064 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01012 20130101; H01L
2924/01046 20130101; H01L 2924/01057 20130101; H01L 2924/01058
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01012 20130101; H01L 2924/01058 20130101; H01L 2924/01063
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01004 20130101; H01L 2924/01012
20130101; H01L 2924/01039 20130101; H01L 2924/01078 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01004
20130101; H01L 2924/01012 20130101; H01L 2924/01057 20130101; H01L
2924/01078 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01046 20130101; H01L 2924/01063 20130101; H01L 2924/01078
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01004 20130101; H01L 2924/01012 20130101; H01L 2924/01014
20130101; H01L 2924/01046 20130101; H01L 2924/01078 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01012
20130101; H01L 2924/01058 20130101; H01L 2924/01064 20130101; H01L
2924/01078 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01012 20130101; H01L 2924/01057 20130101; H01L
2924/01058 20130101; H01L 2924/01078 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/01058 20130101; H01L 2924/01078
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01004 20130101; H01L 2924/01012 20130101; H01L 2924/01063
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01004 20130101; H01L 2924/01012
20130101; H01L 2924/01039 20130101; H01L 2924/01046 20130101; H01L
2924/01078 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01046 20130101; H01L 2924/01057 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01004 20130101; H01L
2924/01012 20130101; H01L 2924/01046 20130101; H01L 2924/01063
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01004 20130101; H01L 2924/01012 20130101; H01L 2924/01014
20130101; H01L 2924/01046 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01012 20130101; H01L 2924/01046
20130101; H01L 2924/01058 20130101; H01L 2924/01063 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01012
20130101; H01L 2924/01014 20130101; H01L 2924/01046 20130101; H01L
2924/01058 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01012 20130101; H01L 2924/01039 20130101; H01L
2924/01058 20130101; H01L 2924/01078 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/01046 20130101; H01L 2924/01058
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01004 20130101; H01L 2924/01012
20130101; H01L 2924/01046 20130101; H01L 2924/01057 20130101; H01L
2924/01078 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/01039 20130101; H01L 2924/01057
20130101; H01L 2924/01063 20130101; H01L 2924/01064 20130101; H01L
2924/01078 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/01039 20130101; H01L 2924/01046
20130101; H01L 2924/01057 20130101; H01L 2924/01064 20130101; H01L
2924/01078 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/01039 20130101; H01L 2924/01057
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01004 20130101; H01L 2924/01012
20130101; H01L 2924/01014 20130101; H01L 2924/01046 20130101; H01L
2924/01058 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01058 20130101; H01L 2924/01064 20130101; H01L 2924/01078
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01004 20130101; H01L 2924/01012 20130101; H01L 2924/01014
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01012 20130101; H01L 2924/01046
20130101; H01L 2924/01058 20130101; H01L 2924/01063 20130101; H01L
2924/01078 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/0102 20130101; H01L 2924/01046
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01004 20130101; H01L 2924/01012 20130101; H01L 2924/01014
20130101; H01L 2924/01046 20130101; H01L 2924/0105 20130101; H01L
2924/01058 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/0102 20130101; H01L 2924/01058
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01004 20130101; H01L 2924/01012
20130101; H01L 2924/01014 20130101; H01L 2924/0105 20130101; H01L
2924/01078 20130101; H01L 2224/45144 20130101; H01L 2924/013
20130101; H01L 2924/01004 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/0102 20130101; H01L 2924/01046
20130101; H01L 2924/0105 20130101; H01L 2924/01078 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01004
20130101; H01L 2924/01012 20130101; H01L 2924/01014 20130101; H01L
2924/0102 20130101; H01L 2924/01046 20130101; H01L 2924/01058
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01004 20130101; H01L 2924/01012
20130101; H01L 2924/01014 20130101; H01L 2924/0102 20130101; H01L
2924/01046 20130101; H01L 2924/01058 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01004 20130101; H01L
2924/01012 20130101; H01L 2924/01014 20130101; H01L 2924/0102
20130101; H01L 2924/0105 20130101; H01L 2924/01078 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01004
20130101; H01L 2924/01012 20130101; H01L 2924/01014 20130101; H01L
2924/0102 20130101; H01L 2924/0105 20130101; H01L 2924/01058
20130101; H01L 2924/01078 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01004 20130101; H01L 2924/01012
20130101; H01L 2924/01014 20130101; H01L 2924/0102 20130101; H01L
2924/01046 20130101; H01L 2924/0105 20130101; H01L 2924/01058
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01004 20130101; H01L 2924/01012 20130101; H01L 2924/01014
20130101; H01L 2924/0102 20130101; H01L 2924/01046 20130101; H01L
2924/0105 20130101; H01L 2924/01058 20130101; H01L 2924/01078
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01004 20130101; H01L 2924/01012 20130101; H01L 2924/01014
20130101; H01L 2924/01058 20130101; H01L 2924/01078 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01004
20130101; H01L 2924/01012 20130101; H01L 2924/01014 20130101; H01L
2924/0102 20130101; H01L 2924/01046 20130101; H01L 2924/01078
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01004 20130101; H01L 2924/01012 20130101; H01L 2924/01057
20130101; H01L 2924/01058 20130101; H01L 2924/01078 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01004
20130101; H01L 2924/01012 20130101; H01L 2924/01078 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01004
20130101; H01L 2924/01012 20130101; H01L 2924/01039 20130101; H01L
2924/01064 20130101; H01L 2924/01078 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01004 20130101; H01L
2924/01039 20130101; H01L 2924/01078 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01012 20130101; H01L
2924/01057 20130101; H01L 2924/01078 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01012 20130101; H01L
2924/01058 20130101; H01L 2924/01078 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01012 20130101; H01L
2924/0102 20130101; H01L 2924/01078 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01012 20130101; H01L
2924/01014 20130101; H01L 2924/0102 20130101; H01L 2924/01046
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01012 20130101; H01L 2924/0102 20130101; H01L 2924/01046
20130101; H01L 2924/01058 20130101; H01L 2924/01064 20130101; H01L
2224/45144 20130101; H01L 2924/013 20130101; H01L 2924/01012
20130101; H01L 2924/0103 20130101; H01L 2924/01058 20130101; H01L
2924/01063 20130101; H01L 2924/01078 20130101; H01L 2224/45144
20130101; H01L 2924/013 20130101; H01L 2924/01004 20130101; H01L
2924/0103 20130101; H01L 2924/01046 20130101; H01L 2924/01063
20130101; H01L 2224/45144 20130101; H01L 2924/013 20130101; H01L
2924/01012 20130101; H01L 2924/0103 20130101; H01L 2924/01046
20130101; H01L 2924/01064 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/01012 20130101; H01L 2924/01014
20130101; H01L 2924/01039 20130101; H01L 2924/01046 20130101; H01L
2924/01057 20130101; H01L 2924/01058 20130101; H01L 2924/01063
20130101; H01L 2924/01064 20130101; H01L 2224/45144 20130101; H01L
2924/013 20130101; H01L 2924/00013 20130101; H01L 2224/48624
20130101; H01L 2924/00 20130101; H01L 2924/1576 20130101; H01L
2924/01028 20130101; H01L 2924/1576 20130101; H01L 2924/01404
20130101; H01L 2924/181 20130101; H01L 2924/00 20130101; H01L
2924/00011 20130101; H01L 2924/01006 20130101; H01L 2224/48639
20130101; H01L 2924/00 20130101 |
Class at
Publication: |
420/508 ;
420/510 |
International
Class: |
C22C 5/02 20060101
C22C005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 2004 |
JP |
2004-287524 |
Claims
1. An Au alloy bonding wire comprising an Au alloy in which trace
elements are contained in an Au alloy matrix containing 0.05 to 2
mass % in total of at least one selected from Pd and Pt of high
purity of at least 99.9 mass % in Au of high purity of at least
99.99 mass %; wherein said trace elements comprise 10 to 100 ppm by
mass of Mg, 5 to 100 ppm by mass of Ce, and 5 to 100 ppm by mass of
each at least one selected from Be, Y, Gd, La, Eu and Si, the total
content of Be, Y, Gd, La, Eu and Si being 5 to 100 ppm by mass.
2. An Au alloy bonding wire comprising an Au alloy in which trace
elements are contained in an Au alloy matrix containing 0.05 to 2
mass % in total of at least one selected from Pd and Pt of high
purity of at least 99.9 mass % in Au of high purity of at least
99.99 mass %; wherein saidtrace elements comprise 10 to 100 ppm by
mass of Mg, 5 to 100 ppm by mass of Be, and at least one selected
from Y, La, Eu and Si, the content of each of Y, La, Eu and Si
among the trace elements being 5 to 100 ppm by mass, and the total
content of Y, La, Eu and Si being 100 ppm by mass or lower.
3. An Au alloy bonding wire comprising an Au alloy in which trace
elements are contained in an Au alloy matrix containing 0.05 to 2
mass % in total of at least one selected from Pd and Pt of high
purity of at least 99.9 mass % in Au of high purity of at least
99.99 mass %; wherein said trace elements comprise 10 to 100 ppm by
mass of Mg, 5 to 30 ppm by mass of Si, 5 to 30 ppm by mass of Be,
and 5 to 30 ppm by mass of either of Ca and Sn.
4. An Au alloy bonding wire comprising an Au alloy in which trace
elements are contained in an Au alloy matrix containing 0.05 to 2
mass % in total of at least one selected from Pd and Pt of high
purity of at least 99.9 mass % in Au of high purity of at least
99.99 mass %; wherein said trace elements comprise 10 to 100 ppm by
mass of Mg, 5 to 30 ppm by mass of Si, 5 to 30 ppm by mass of Be,
and 5 to 30 ppm by mass each of, and 10 to 60 ppm by mass in total
of, two selected from Ca, Ce and Sn.
5. An Au alloy bonding wire comprising an Au alloy in which trace
elements are contained in an Au alloy matrix containing 0.05 to 2
mass % in total of at least one selected from Pd and Pt of high
purity of at least 99.9 mass % in Au of high purity of at least
99.99 mass %; wherein said trace elements comprise 10 to 100 ppm by
mass of Mg, 5 to 30 ppm by mass of Si, 5 to 30 ppm by mass of Be,
and 5 to 30 ppm by mass each of, and 15 to 90 ppm by mass in total
of, all three of Ca, Ce and Sn.
6. The Au alloy bonding wire according to any of claims 1 through
5, wherein the total content of said trace elements is 100 ppm by
mass or lower.
7. The Au alloy bonding wire according to any of claims 1 through
5, having a wire diameter of 23 .mu.m or smaller.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to Au alloy bonding wires for
wire bonding of semiconductor devices used for connecting external
leads of circuit boards to electrodes on semiconductor integrated
circuit devices, and more specifically relates to an Au alloy
bonding wire according to which the bondability for a first bond
and a second bond is improved, and an Au alloy bonding wire
according to which the sphericity of a melted ball and the
circularity of a squashed ball are improved.
[0003] 2. Description of the Related Art
[0004] Conventionally, as wires of diameter approximately 25 to 35
.mu.m for connecting external leads to semiconductor chip
electrodes used in semiconductor apparatuses, Au alloy bonding
wires containing high-purity gold of purity not lower than 99.99
mass % are widely used. Ordinarily, in a method of connecting an Au
alloy bonding wire, for a first bond, a combined ultrasonic-thermo
compression bonding method is mainly used. With this method, a tip
of the wire is heated and thus melted through arc heat input, thus
forming a ball by the surface tension, and then the ball portion is
squashed onto an electrode of a semiconductor device that has been
heated to a range of 150 to 300.degree. C. Then, for a subsequent
second bond, the bonding wire is directly wedge-joined onto the
external lead side through ultrasonic compression bonding.
[0005] In order for a semiconductor device such as a transistor or
IC to be usable, after the bonding with bonding wires as described
above, sealing with an epoxy resin is carried out with an object of
protecting the semiconductor chip, the bonding wires, and the lead
frame or the like at a portion where the semiconductor chip is
attached.
[0006] Recently, there are increased demands to make semiconductor
devices more compact and finer, and to improve the performance and
reliability thereof. Among this, the properties required of gold
bonding wires have become more multifarious, and it has become that
even when gold bonding wires are made still finer to cope with the
increased number of pins of semiconductor chips and the
accompanying reduction in pitch therebetween, still better long
term reliability of the bonding is required with regard to the
necessary strength, the circularity of the ball for the first bond,
the bonding reliability for the second bond, and so on.
[0007] In particular, as semiconductor devices are being made still
more compact and finer and of yet higher performance, the size of
the semiconductor devices is decreased. Accompanying this, the
number of input/output terminals per unit area is increased, and
the Al pad pitch (the spacing between pad centers) is also
decreased from 100 .mu.m to 80 .mu.m and further to 60 .mu.m. The
diameter of bonding wires has thus also started to decrease from 25
.mu.m to 23 .mu.m or smaller, and in some cases trials have even
been carried out into a wire diameter in the order of 10 .mu.m.
[0008] However, as the diameter of bonding wires decreases, the
absolute rigidity of the wire itself decreases, and hence problems
have started to arise that were not a problem with a wire diameter
of 25 .mu.m.
[0009] For example, if the rigidity decreases as a result of the
wire diameter being decreased, then a so-called "leaning" troubles
in which wires stringing between the first bond and the second bond
fall down sidewise and hence the gap between adjacent wires
decreases arises with eventual contacting.
[0010] Moreover, as the density is increased, the amount of heat
generated at the bonds increases. If there is prolonged use in a
high-temperature ambience, then growth of an intermetallic compound
at the interface between the Au wire and the Al pad at the first
bond will proceed rapidly, and as a result the problem of the ball
bondability decreasing due to the intermetallic compound produced
will become marked.
[0011] Furthermore, corrosion under the influence of components
contained in the molding resin also becomes a problem.
[0012] To solve these problems, trials have been carried out into
adding various elements in varied proportions. Au alloy wires have
been introduced from pure Au wires by adding a noble metal element
such as Pd to the Au so as to increase the rigidity, and attempts
have been made to improve various properties by adding one or a
plurality of trace elements. In one example, growth of an
intermetallic compound has been suppressed by retarding Au--Al
interdiffusion at the interface between the bonding wire (ball) and
the Al alloy to which the bonding wire is joined.
[0013] In the case of adding trace elements to an Au alloy wire,
the higher the concentration of the trace elements is made relative
to the Au alloy wire, the higher the absolute rigidity of the Au
alloy wire becomes, and the better various properties become, but
on the other hand, undesirable properties also appear. An example
is that in the case that the loop formability improves, the Au ball
formability worsens due to the elements added to the Au alloy
matrix. The wedge bondability may also worsen. Furthermore, the
drawback of the Au alloy ball hardness increasing due to the
elements added to the Au alloy matrix may also arise.
[0014] There are thus problems such as the melted ball or the
squashed ball becoming misshapen, and hence it becomes difficult to
carry out ball bonding at a small pitch of spacing, or the rate of
chip cracking increasing; trace elements can therefore not be added
in large amounts. For example, in the case that Ca alone is added
to secure strength, the Ca may partially deposit out on the surface
of the fine wire, the deposited Ca then being oxidized to form a
surface oxide film, and as a result there have been problems of the
ball shape and bondability for the first bond not being stable, and
hence the circularity of the squashed ball becoming poor, and the
wedge bondability for the second bond becoming poor.
[0015] Moreover, in a complicated case in which many types of
elements are added, these elements may function in a complicated
manner in the Au alloy and may be deposited out on the surface of
the melted ball, whereby good initial bonding cannot be obtained,
and there is an increased tendency for it is no longer possible to
obtain a reliable first bond and good bondability for the second
bond.
[0016] In sum, the present status of the matter is that a balance
can be obtained by selecting the kinds and amounts of the alloying
elements so as to accomplish the wire properties required of the
fine wire; as the wire properties required of the fine wire become
upgraded, there is no foreseeable end to the search for
combinations.
[0017] Following is a brief summary of the additive elements to the
bonding wire alloy described in several prior art documents.
[0018] Japanese Patent No. 3064692 describes a "semiconductor
device bonding wire in which 1 wt % of high-purity Pd is added to
high-purity Au, and, in addition, 0.0001 to 0.005 wt %, as a total,
of at least one selected from Fe, Si, Be, Ca, Ge, Y, Sc and other
rare earth elements is added". Here, a "bonding wire of diameter 25
.mu.m" is given as a working example.
[0019] Japanese Patent Application Laid-open No. 9-321075 describes
a "bonding wire characterized by containing 0.0003-0.003 wt % of
Ca, containing 0.0005 to 0.01 wt % of Mg, and containing 0.01 to
2.0 wt %, as a total, of at least one selected from Pt, Pd and Cu,
the balance comprising Au and unavoidable impurities". Here, an
"alloy wire of diameter 0.025 mm" is given as a working
example.
[0020] Japanese Patent Application Laid-open No. 11-222639
describes an "fine wire comprising a gold alloy for bringing
semiconductor components into contact with one another,
characterized in that the gold alloy comprises 0.5 to 0.9 wt % of
copper, 0.05 to 0.95 wt % of platinum, and the balance of gold",
and further describes such a gold alloy to which is added "0.0001
to 0.1 wt % of at least one selected from the group consisting of
alkaline earth metals and rare earth metals". Here, the "alkaline
earth metal(s) is/are beryllium, magnesium and/or calcium", and the
"rare earth metal is cerium". Here, "a diameter of 30 .mu.m" is
given as a working example.
[0021] Japanese Patent Application Laid-open No. 11-87396 describes
an "fine wire for bringing semiconductor structural members into
contact with one another comprising a gold alloy containing cerium
misch metal, characterized in that the gold alloy comprises 0.05 to
0.95 wt % of platinum, 0.001 to 0.1 wt % of cerium misch metal, 0
to 0.1 wt % of an alkaline earth metal, and the balance of gold,
wherein at least 50 wt % of the rare earth metal is cerium", and
moreover states that "the alkaline earth metal comprises a mixture
of beryllium and calcium", and "the platinum is partially or wholly
replaced with palladium". Here, regarding prior art, it is stated
that "The diameter of the wire can be approximately 10 to 200
.mu.m, and is usually approximately 20 to 60 .mu.m. This is
selected in accordance with the purpose of use", and "a wire having
a diameter of 30 .mu.m" and "a wire having a diameter of 25 .mu.m
and a wire having a diameter of 30 .mu.m" are given as working
examples.
[0022] Japanese Patent Application Laid-open No. 11-214425
describes a "gold alloy wire for wire bonding of a semiconductor
device characterized by adding 0.1 to 3.0 wt % of at least one
selected from Zn, Co, Mo and Cr, and 1 to 100 ppm by weight of at
least one selected from La, Eu, Be, Y and Ca to high-purity gold",
and further states that it is possible to "add 1 to 500 ppm by
weight of at least one selected from Bi, Yb, Sb, Mg, In, Ru and
Ir", and moreover "further add 0.01 to 2.0 wt % of at least one
selected from Pd, Pt, Cu and Ag". Here, "a diameter of 30 .mu.m" is
given as a working example.
[0023] Japanese Patent Application Laid-open No. 2003-133362
describes "gold alloy bonding wires" for the case that "the molding
resin is a resin having a bromine concentration of not exceeding
0.1 mass % and contains 0.01 mass % or more as a total
concentration (R.sub.p) of at least one element selected from P, Mg
and Al", including a "gold alloy bonding wire" having
"C.sub.1=0.005 to 1.5 mass %", or a "gold alloy bonding wire"
having "C.sub.1=0.005 to 1.5 mass %" and "C.sub.2=0.001 to 0.06
mass %" and "C.sub.3=0.001 to 0.05 mass %", assuming that "C.sub.1
is the total concentration of at least one element selected from
Cu, Pd, Pt, Zn and Ag", "C.sub.2 is the total concentration of at
least one element selected from Ca, Ce, Eu, Dy and Y", and "C.sub.3
is the total concentration of at least one element selected from
La, Gd, Tb, Mg and Ni". Here, "a wire diameter of smaller than 18
.mu.m" is mentioned, but "a final wire diameter of 20 .mu.m" is
shown in the working example.
SUMMARY OF THE INVENTION
[0024] It is an object of the present invention to provide a
bonding wire according to which, despite being a fine wire having a
diameter of not more than 23 .mu.m, trace elements in an Au alloy
matrix of Au--Pd or the like can be dispersed uniformly without
segregation, Au--Al interdiffusion can be delayed, leaning does not
occur, the sphericity of a melted ball is maintained, and moreover
a squashed ball has good circularity. Moreover, it is another
object of the present invention to provide a bonding wire according
to which, due to the content of the trace elements in a suitable
amount, even if ball bonding is carried out in the air, there is no
formation of an oxide film on the surface of the fine wire or the
melted ball, the bondability is good, and there is little tendency
for an intermetallic compounds to be produced over time.
Furthermore, it is another object of the present invention to
provide a bonding wire according to which the wedge bondability of
a second bond through ultrasonic compression bonding, which has not
been considered much with ball bonding hitherto, is improved. These
objects are valid even in the case that the total amount added of
trace elements is not larger than 100 ppm.
[0025] The inventors have carried out extensive studies to attain
the above objects, and as a result have accomplished the present
invention.
[0026] That is, according to the present invention, Au alloy
bonding wires as follows are provided. [0027] (1) An Au alloy
bonding wire comprising an Au alloy in which trace elements are
contained in an Au alloy matrix containing 0.05 to 2 mass % in
total of at least one selected from Pd and Pt of high purity of at
least 99.9 mass % in Au of high purity of at least 99.99 mass %,
wherein the trace elements comprise 10 to 100 ppm by mass of Mg, 5
to 100 ppm by mass of Ce, and 5 to 100 ppm by mass each of at least
one selected from Be, Y, Gd, La, Eu and Si, the total content of
Be, Y, Gd, La, Eu and Si being 5 to 100 ppm by mass. [0028] (2) An
Au alloy bonding wire comprising an Au alloy in which trace
elements are contained in an Au alloy matrix containing 0.05 to 2
mass % in total of at least one selected from Pd and Pt of high
purity of at least 99.9 mass % in Au of high purity of at least
99.99 mass %, wherein the trace elements comprise 10 to 100 ppm by
mass of Mg, 5 to 100 ppm by mass of Be, and at least one selected
from Y, La, Eu and Si, the content of each of Y, La, Eu and Si
being 5 to 100 ppm by mass, and the total content of Y, La, Eu and
Si being not exceeding 100 ppm by mass. [0029] (3) An Au alloy
bonding wire comprising an Au alloy in which trace elements are
contained in an Au alloy matrix containing 0.05 to 2 mass % in
total of at least one selected from Pd and Pt of high purity of at
least 99.9 mass % in Au of high purity of at least 99.99 mass %,
wherein the trace elements comprise 10 to 100 ppm by mass of Mg, 5
to 30 ppm by mass of Si, 5 to 30 ppm by mass of Be, and 5 to 30 ppm
by mass of either of Ca and Sn. [0030] (4) An Au alloy bonding wire
comprising an Au alloy in which trace elements are contained in an
Au alloy matrix containing 0.05 to 2 mass % in total of at least
one selected from Pd and Pt of high purity of at least 99.9 mass %
in Au of high purity of at least 99.99 mass %, wherein the trace
elements comprise 10 to 100 ppm by mass of Mg, 5 to 30 ppm by mass
of Si, 5 to 30 ppm by mass of Be, and 5 to 30 ppm by mass of each
of, and 10 to 60 ppm by mass in total of, two selected from Ca, Ce
and Sn. [0031] (5) An Au alloy bonding wire comprising an Au alloy
in which trace elements are contained in an Au alloy matrix
containing 0.05 to 2 mass % in total of at least one selected from
Pd and Pt of high purity of at least 99.9 mass % in Au of high
purity of at least 99.99 mass %, wherein the trace elements
comprise 10 to 100 ppm by mass of Mg, 5 to 30 ppm by mass of Si, 5
to 30 ppm by mass of Be, and 5 to 30 ppm by mass of each of, and 15
to 90 ppm by mass in total of, all three of Ca, Ce and Sn. [0032]
(6) The Au alloy bonding wire according to any of (1) through (5),
wherein the total content of the trace elements is not exceeding
100 ppm by mass. [0033] (7) The Au alloy bonding wire according to
any of (1) through (5), having a diameter of not exceeding 23
.mu.m.
ADVANTAGES OF THE INVENTION
[0034] According to the Au alloy of the present invention, even for
a fine bonding wire of a diameter not exceeding 23 .mu.m, as in the
case that that the diameter is greater than 23 .mu.m, an effect of
retarding Au--Al interdiffusion, an effect of improving wedge
bondability, an effect of suppressing leaning, an effect of
improving the sphericity of the melted ball, and an effect of
improving the circularity of a squashed ball can all be attained.
In the present invention, it is needless to add the trace elements
in an amount exceeding 300 ppm by mass as is conventional, and
hence a bonding wire can be realized according to which, even if
ball bonding is carried out in air, an oxide film will never be
formed on the surface of the fine wire on the melted ball.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] Au alloy bonding wires of the present invention contain, as
a matrix alloy, (i) Au and (ii) Pd and/or Pt; desired properties
are obtained through selection and adjustment of trace elements
contained in this matrix alloy. The Au alloy bonding wires can be
classified broadly into two groups in terms of the properties to be
obtained.
[0036] For the first group, bondability and stability over time
(long term reliability) for the first bond and the second bond are
predominantly aimed for, and a first invention and a second
invention are stipulated.
[0037] For the second group, an improvement in the circularity of a
squashed ball, and an improvement in the sphericity of a melted
ball which greatly affects the circularity of the squashed ball,
are predominantly aimed for, and third to fifth inventions are
stipulated.
[0038] In the first invention (claim 1) belonging to the first
group, as the additive trace elements contained in the matrix
alloy, (iii) Mg and Ce are taken as the essential additive trace
elements, and these are combined with (iv) at least one element
selected from Be, Y, Gd, La, Eu and Si. In the second invention
(claim 2) belonging to the first group, as the additive trace
elements contained in the matrix alloy, (v) Mg and Be are taken as
the essential additive trace elements, and these are combined with
(vi) at least one element selected from Y. La, Eu and Si without
containing Ce.
[0039] In the third invention (claim 3) belonging to the second
group, the matrix alloy is the same as in the inventions belonging
to the first group, and as the additive trace elements contained in
the matrix alloy, (vii) Mg, Si and Be are taken as the essential
additive trace elements, and these are combined with (viii) either
of Ca and Sn. In the fourth invention (claim 4) belonging to the
second group, as the additive trace elements contained in the
matrix alloy, (vii) Mg, Si and Be are taken as the essential
additive trace elements, and these are combined with (viii) two
elements selected from Ca, Ce and Sn. In the fifth invention (claim
5) belonging to the second group, as the additive trace elements
contained in the matrix alloy, (vii) Mg, Si and Be are taken as the
essential additive trace elements, and these are combined with (ix)
the three elements Ca, Ce and Sn.
[0040] In the matrix alloy used in the present invention, Au is
high-purity Au, the purity thereof being at least 99.99 mass %,
preferably at least 99.999 mass %. In addition, the Pd and/or Pt is
of high purity, the purity thereof being at least 99.9 mass %,
preferably at least 99.99 mass %.
[0041] If the alloy contains a large amount of the Pd and/or Pt,
then a ball will become harder, and chip cracking will become prone
to occur. The total content of the Pd and Pt in the matrix alloy is
thus not exceeding 2 mass %, preferably not exceeding 1.5 mass %,
of the matrix alloy. Moreover, to produce stable effects, the lower
limit of this content is 0.08 mass %, preferably 0.2 mass %.
[0042] Besides, Pd and Pt also have an effect on the long-term
reliability of the first bond. A high temperature storage at
175.degree. C. has indicated the durations of: [0043] at least 2000
hours at a content of 0.2 mass % or larger; [0044] at least 1500
hours at a content of 0.08 mass % or larger; and [0045] at least
1000 hours at a content of 0.05 mass % or larger.
[0046] In the case of adding both Pd and Pt to the matrix alloy,
there are no particular limitations in the proportion between the
amount of Pd added and the amount of Pt added. This is because both
Pd and Pt exhibit approximately the same matrix effect on Au.
[0047] Among the trace elements dispersed in the matrix alloy (Au
alloy), the purity of Mg should be at least 99.9 mass %, preferably
at least 99.99 mass %. For both the inventions belonging to the
first group and the inventions belonging to the second group, the
content of Mg in the matrix alloy is 10 to 100 ppm by mass,
preferably 40 to 80 ppm by mass.
[0048] It has been found that in the-Au alloy matrix, Mg is an
element capable of improving the circularity for the first bond and
the wedge bondability for the second bond formed by ultrasonic
compression bonding. If 10 to 100 ppm by mass of Mg is contained,
then the above effects of improving the circularity and the wedge
bondability are exhibited. With less than 10 ppm by mass, the
circularity and the wedge bondability cannot be improved, and at
above 100 ppm by mass, Mg is deposited out on the ball surface and
oxidized, and hence the bondability for the first bond worsens. Mg
further improves the wedge bondability for the second bond with 40
ppm by mass or higher, and moreover with 80 ppm by mass or lower
the sphericity of the melted ball is more stable.
[0049] The sphericity for the melted ball in the present invention
is defined as the ratio "across diameter to downward diameter"
obtained by measuring the respective diameters of the melted ball
as viewed from the wire-free end of the melted ball. The value of
this sphericity is in a range of 0.99 to 1.01, preferably 0.995 to
1.005. Further, the circularity of the squashed ball is defined as
the ratio "compression-bonded diameter in perpendicular direction
to squashed diameter in parallel direction" upon measuring the
respective squashed diameters parallel to and perpendicular to the
direction of ultrasonic wave application. The value of this
circularity is in the range of 0.98 to 1.02, preferably 0.99 to
1.01.
[0050] Among the trace elements contained in the matrix alloy (Au
alloy), the purity of Ce should be at least 99.9 mass %, preferably
at least 99.99 mass %.
[0051] The content of Ce in the matrix alloy is 5 to 100 ppm by
mass for the first group, and 5 to 30 ppm by mass for the second
group.
[0052] Among the trace elements contained in the Au alloy matrix,
the purity of Be should be at least 98.5 mass %, preferably at
least 99.9 mass %.
[0053] The content of Be in the matrix alloy is 5 to 100 ppm by
mass for the first group, and 5 to 30 ppm by mass for the second
group.
[0054] Be in the Au alloy matrix improves the circularity for the
first bond. If the Be content is less than 5 ppm by mass, then the
above effect of improving the circularity cannot be obtained,
whereas if the Be content is greater than 30 ppm by mass, the
result is that an increased amount of the oxide is formed on the
surface of the melted ball and hence the bondability for the first
bond worsens.
[0055] Among the trace elements contained in the Au alloy matrix,
the purity of Si should be at least 99.99 mass %, preferably at
least 99.999 mass %.
[0056] The content of Si in the matrix alloy is 5 to 100 ppm by
mass for the first group, and 5 to 30 ppm by mass for the second
group.
[0057] Si in the Au alloy matrix is an element that maintains the
loop formability, and the circularity of the squashed ball. If the
Si content is less than 5 ppm by mass, then the loop formability
cannot be maintained, whereas if the Si content is greater than 30
ppm by mass, then it would be difficult to obtain good
circularity.
[0058] Among the trace elements contained in the Au alloy matrix,
the purity of Gd should be at least 99 mass %, preferably at least
99.5 mass %.
[0059] The content of Gd in the matrix alloy is 5 to 100 ppm by
mass for the first group.
[0060] Gd in the Au alloy matrix is an element that maintains the
loop formability, and the circularity of the squashed ball. If the
Gd content is lower than 5 ppm by mass, then the loop formability
cannot be maintained, whereas if the Gd content is greater than 30
ppm by mass, then it would be difficult to obtain good
circularity.
[0061] Among the trace elements contained in the Au alloy matrix,
the purity of Ca should be at least 99 mass %, preferably at least
99.5 mass %. The content of Ca in the matrix alloy is 5 to 30 ppm
by mass.
[0062] Ca in the Au alloy matrix improves the strength of the wire.
It has been found that, even for an fine wire having a diameter of
not exceeding 23 .mu.m, Ca increases the rigidity of the fine wire
itself, whereby the loop formability can be maintained, and
moreover the circularity of the squashed ball in the first bonding
can be maintained. If the Ca content is lower than 5 ppm by mass,
then the above effect of improving the circularity cannot be
obtained. If the Ca content is greater than 30 ppm by mass, then a
depression will be prone to be formed in the base of the melted
ball, and hence for a bonding wire that is used in ball bonding by
forming a melted ball and then connecting to an electrode of a
semiconductor device, the Ca content in the matrix alloy is
preferably in the range of 5 to 30 ppm by mass.
[0063] Moreover, if a prescribed amount of Ca is added, then a wire
for which good loop formability and circularity are simultaneously
fulfilled can be obtained.
[0064] Furthermore, if the total content of all the trace elements
in the Au alloy matrix is greater than 100 ppm by mass, then oxides
are prone to be produced on the surface of the melted ball, and
hence the bondability for the first bond will worsen.
[0065] Among the trace elements contained in the matrix alloy (Au
alloy), the purity of each of the elements Ce, Y, Eu, La and Sn
should be at least 99.9 mass %, preferably at least 99.99 mass
%.
[0066] The content of each trace elements in the matrix alloy is 5
to 100 ppm by mass, preferably 5 to 80 ppm by mass for La, and 5 to
30 ppm by mass for the other elements.
[0067] As described above, it has been found that, even for a fine
wire of diameter not exceeding 23 .mu.m, Ce, Y, Gd, Be, La, Si and
Eu in the Au alloy matrix are elements that increase the rigidity
of the fine wire itself, whereby the loop formability can be
maintained, and moreover the circularity of the squashed ball in
the first bonding can be maintained.
[0068] If the amount of each element among Ce, and Y, Gd, Be, La,
Si and Eu is smaller than 5 ppm by mass, then it will not be
possible to maintain the loop formability of the alloy wire of
Au--Pd or the like, and moreover it will be difficult to maintain
the circularity of the squashed ball in the first bonding.
Moreover, if the amount of each of the above elements is larger
than 100 ppm by mass, or the total amount of these elements is
larger than 100 ppm by mass, then the melted ball will become
misshapen, or the rigidity of the fine wire itself will become too
high, and hence the semiconductor chip will become prone to
breaking. If the content of each of the above elements is not more
than 30 ppm by mass, then the circularity of the squashed ball will
be yet more stable.
[0069] Moreover, the trace elements may be deposited out on the
surface of the melted ball of the Au alloy matrix of Au--Pd or the
like and oxidized, resulting in the bondability for the first bond
worsening, or the circularity of the squashed ball worsening. The
order of the effect of improving the circularity has been found to
be, from the best to the worst, Si, Be, La, Ce, Ca, Eu, Y and Gd.
That is, in combinations with Ce, the order is Ce--Si, Ce--Be,
Ce--La, Ce--Y, and Ce--Gd. Moreover, in combinations with Be, the
order is Be--Si, Be--Ca, Be--Eu, and Be--Y.
[0070] The trace elements Mg, Ce, Y, Gd, Be, Ca, Eu, La and Si used
in the present invention are added in trace amounts in a suitable
combination to the alloy of high-purity Au--Pd or the like, and
hence can be contained uniformly in the Au alloy without
segregation; there is thus no unintentional deposition out to form
an oxide film on the surface of the Au alloy as with Zn or a large
amount of Ca being added alone. Accordingly, by combining Mg, Ce,
Y, Gd, Be, Ca, Eu, La and Si in amounts in suitable ranges as
above, in addition to an effect of retarding interdiffusion in the
Au alloy bonding wire, an effect of improving the wedge
bondability, and an effect of improving the sphericity of the
melted ball, an effect of loop formation for the fine wire, and an
effect of improving the circularity of the squashed ball can all be
attained.
[0071] Hitherto, joint addition of Mg and a rare earth element to
an Au--Pd alloy bonding wire has been disclosed in the literature
(Japanese Patent Application Laid-open No. 11-222639, Japanese
Patent Application Laid-open No. 11-87396, Japanese Patent
Application Laid-open No. 11-214425, Japanese Patent Application
Laid-open No. 2003-133362), and there is a case in which this joint
addition has actually been carried out (Japanese Patent Application
Laid-open No. 2003-133362). However, with the Au alloy containing
Zn described in Japanese Patent Application Laid-open No.
11-222639, an oxide film readily forms on the fine wire, and hence
the finer the fine wire, the more difficult it becomes to make the
squashed ball circular. Moreover, with an Au alloy containing more
than 30 ppm by mass of Ca, the Ca deposits out onto the surface
irregularly and oxidizes regardless of whether or not other added
elements are present, and hence with the Au alloy matrix there is
the problem that good bonding reliability for the first bond and
good circularity of the squashed ball cannot be obtained.
[0072] Hitherto, it was not known that Mg and so on are elements
having good dispersibility in an Au alloy matrix of high-purity
Au--Pd or the like, and are trace elements for which there is no
formation of an oxide film on the surface of the fine wire or the
melted ball even if ball bonding is carried out in the air. It was
not predictable that by combining suitable ones selected from Mg,
Ce, Y, Gd, Be, La, Si, Ca and Eu in amounts in suitable ranges as
in the present invention, these trace elements would all have good
dispersibility in the Au alloy matrix, with deposition out onto the
surface not occurring, and hence stability in the quality as a
bonding wire could be obtained.
WORKING EXAMPLES
[0073] Following is a more detailed description of the present
invention by way of working examples and comparative examples.
Working Examples 1 to 81
[0074] The composition of each sample is shown in Table 1 for the
working examples of the first group (Working Examples 1 to 57) and
in Table 2 for the working examples of the second group (Working
Examples 58 to 81). Trace elements were added such that the amounts
(ppm by mass) thereof would be as in Table 1 or Table 2 to an alloy
of high-purity Au of purity 99.999 mass % or more and high-purity
Pd and/or Pt of purity 99.99 mass %, or more and melt-casting was
carried out in a vacuum melting furnace. Drawing into a wire was
then carried out, and then final heat treatment was carried out at
a wire diameter of 25 .mu.m, 20 .mu.m or 15 .mu.m, and the
elongation was adjusted to 4%. The ultimate elongation and tensile
strength of each bonding wire were evaluated by carrying out
tensile testing on 10 of each of the wires cut in a length of 10
cm, and then calculating the average values.
[0075] Connection was carried out in which each type of fine wire
was subjected to first bonding to a 50 .mu.m-square Al pad (Al film
thickness approximately 1 .mu.m) on an Si chip by way of ball
bonding with a joint ultrasonic-thermocompression bonding method in
the air, and was then subjected to second bonding to an Ag-plated
42 alloy lead using wedge bonding with a joint
ultrasonic-thermocompression bonding method. At this time, the loop
span was made to be 5 mm, and the loop height was made to be 200
.mu.m, and a X200-pin QFP (package)" having 200 Al pads was used.
In the first bonding, all of the balls were formed within the 50
.mu.m-square Al pad. Moreover, in the second bonding, the wires
were all firmly joined onto leads. Out of the connected wires, the
evaluation of each item was carried out using 40 wires freely taken
from the thus connected wires. The evaluation results are shown in
Table 4 for the working examples of the first group, and Table 5
for the working examples of the second group.
Comparative Examples 1 to 23
[0076] The compositions of the samples in these comparative
examples having a formulation of the trace elements differing from
those of the working examples are each shown in Table 3. Note that
Comparative Examples 1 to 17 are comparative examples corresponding
to the first group, and Comparative Examples 18 to 23 are
comparative examples corresponding to the second group.
[0077] The fine wires of Au alloys were subjected, in the same
manner as in the working examples, to a final heat treatment to
adjust the elongation to 4% at a wire diameter of 25, 20 or 15
.mu.m and subjected to evaluation in the same manner as in Example
1. The results of evaluation are shown in Table 6.
[0078] The properties of each bonding wire of the working examples
and comparative examples were evaluated as follows.
[0079] For the evaluation of the "quality of bonding" for the first
bonding and the second bonding, 5000 loops were formed, and the
case where there were no defects such as separation was taken as
good and indicated by "", the case that defects occurred for one
and only one wire was indicated by ".largecircle.", and the case
where defects occurred for two or more wires was indicated by
".DELTA.".
[0080] For the "amount of Au--Al formed", the Al pad was dissolved
in a 10% aqueous NaOH solution, the bonding surface was observed
with a scanning electron microscope, and the proportion of the area
where an Au--Al alloy had been formed on the bonding surface was
determined. The case where Au--Al had formed on at least 70% of the
bonding surface was taken as very good and indicated by "", the
case where Au-Al had formed on at least 50% but less than 70% of
the bonding surface was taken as good and indicated by
".largecircle.", and the case where Au-Al had formed on less than
50% of the bonding surface was taken as normal and indicated by
".DELTA.".
[0081] For the evaluation of the "sphericity of melted ball", the
across and down diameters of the underside of the melted ball (with
the wire being on the upper side) were measured, and the case where
the ratio therebetween was in the range of 0.995 to 1.005 was
indicated by "", and the case where the ratio therebetween was in
the range of 0.99 to 1.01 excluding the above range was indicated
by ".largecircle.". The case where the ratio was outside these
ranges was indicated by ".DELTA.". The measurement was carried out
by selecting ten samples in each case; the average value is shown.
However, for Working Examples 58, 62 and 72, the number of samples
was increased to 50, whereby the extent of variation for the second
group could be determined more accurately.
[0082] For the evaluation of the "circularity of squashed ball",
the squashed diameter was measured parallel to and perpendicular to
the direction in which the ultrasonic waves were applied, and the
case where the ratio therebetween was in a range of 0.99 to 1.01
was indicated by "", and the case where the ratio therebetween was
in a range of 0.98 to 1.02 excluding the above range was indicated
by ".largecircle.". The case where the ratio was outside these
ranges was indicated by ".DELTA.". The measurement was carried out
by selecting 200 samples for the first group and 5000 samples for
the second group; the average value is shown.
[0083] For the "pull test" evaluation, the approximate center of
the loop span was hooked upward, and the load at breakage was
measured. When the wire diameter was 25 .mu.m, the case where the
load was 6.times.10 mN or larger was indicated by "", the case
where the load was in the range of 4.times.10 to 6.times.10 mN was
indicated by ".largecircle.", and the case where the load was
smaller than 4.times.10 mN was indicated by ".DELTA.".
[0084] Besides, when the wire diameter was 20 .mu.m, the case where
the load was 6.times.10 mN or larger was indicated by "", the case
where the load was in a range of 2.5.times.10 to 4.times.10 mN was
indicated by ".largecircle.", and the case twhere the load was
smallers than 2.5.times.10 mN was indicated by ".DELTA.". Further,
when the wire diameter was 15 .mu.m, the case where the load was
2.times.10 mN or larger was indicated by "", the case where the
load was in the range of 1.times.10 to 2.times.10 mN was indicated
by ".largecircle.", and the case where the load was smaller than
1.times.10 mN was indicated by ".DELTA.".
[0085] For the "overall evaluation", the cases in which, out of the
above six evaluation items, there were three or more "" marks and
no ".DELTA." marks were taken as particularly good and indicated by
"", cases where there were two or fewer "" but no ".DELTA." were
taken as good and indicated by ".largecircle.", and cases where
there was one or more ".DELTA." were taken as normal and indicated
by ".DELTA.". TABLE-US-00001 TABLE 1 Example Pd Pt Mg Ce Be Y Gd La
Eu Si Sn Ca Zn No. Au mass % mass ppm 1 balance 0.5 10 10 10 2
balance 1 10 80 50 3 balance 1.5 10 10 50 4 balance 0.5 10 80 80 5
balance 1 10 10 80 6 balance 0.5 10 80 50 7 balance 0.5 0.5 10 10
10 8 balance 1 0.5 10 80 10 9 balance 0.5 30 30 10 10 balance 1 30
30 10 11 balance 1.5 30 30 10 12 balance 0.5 30 50 10 13 balance 1
30 50 10 14 balance 0.5 30 10 30 15 balance 1 30 10 30 16 balance
1.5 30 80 50 17 balance 1 30 80 50 18 balance 1.5 30 10 80 19
balance 0.5 30 30 10 20 balance 1 30 30 10 21 balance 0.5 30 50 10
22 balance 0.5 0.5 30 50 10 23 balance 0.5 1 30 10 30 24 balance
0.5 30 10 50 25 balance 1 30 80 50 26 balance 1.5 30 10 80 27
balance 0.5 80 80 10 28 balance 1 80 80 10 29 balance 0.5 80 80 10
30 balance 1 80 30 10 31 balance 1.5 80 50 10 32 balance 0.5 80 10
30 33 balance 1 80 30 30 34 balance 1.5 80 50 50 35 balance 0.5 80
50 50 36 balance 0.5 0.5 80 10 80 37 balance 0.5 80 30 10 38
balance 1 80 30 10 39 balance 1.5 80 50 10 40 balance 0.5 80 50 10
41 balance 0.5 0.5 80 10 30 42 balance 1 0.5 80 10 50 43 balance
0.5 80 80 50 44 balance 1 80 10 80 45 balance 1.5 10 30 10 10 10 10
10 46 balance 0.5 30 80 30 30 30 47 balance 1 50 10 20 20 20 20 48
balance 0.5 50 30 10 10 10 10 10 49 balance 1 80 80 30 30 30 50
balance 0.5 1.5 80 10 20 20 20 20 51 balance 0.08 50 10 10 10 52
balance 0.1 40 20 20 10 53 balance 0.1 0.05 40 15 20 54 balance 1
0.7 20 60 10 55 balance 0.6 1 20 50 20 56 balance 1 50 10 10 57
balance 0.5 20 10 20
[0086] TABLE-US-00002 TABLE 2 Pd Pt Mg Ce Be Y Gd La Eu Si Sn Ca Zn
Example No. Au mass % mass ppm 58 balance 1 50 10 10 10 59 balance
1 80 20 10 20 60 balance 1.5 30 10 10 20 10 61 balance 0.5 50 20 15
10 10 62 balance 1 20 20 20 10 63 balance 0.5 80 10 10 20 64
balance 0.5 0.5 20 20 20 25 20 65 balance 1 0.5 20 10 10 10 15 66
balance 0.5 30 25 15 20 25 67 balance 1 30 20 10 20 10 68 balance
1.5 30 25 10 20 25 25 69 balance 0.5 30 20 20 10 20 70 balance 1 30
10 15 20 20 25 71 balance 0.2 50 10 10 10 10 72 balance 1 20 15 15
15 10 10 73 balance 1 0.5 30 25 10 20 15 25 74 balance 1 50 20 20
10 25 75 balance 1.5 80 10 15 20 20 10 76 balance 0.5 25 15 10 10
10 25 77 balance 1 80 10 20 20 20 78 balance 0.08 80 25 20 20 10 20
79 balance 0.5 0.5 80 20 20 10 10 10 80 balance 0.5 1 15 10 10 20
10 81 balance 0.1 50 10 10 10 10
[0087] TABLE-US-00003 TABLE 3 Comp. Example Pd Pt Mg Ce Be Y Gd La
Eu Si Sn Ca Zn No. Au mass % mass ppm 1 balance 1 10 80 50 50 2
balance 0.5 10 80 80 80 3 balance 0.5 10 150 80 50 4 balance 1 10
10 10 5 balance 1.5 10 10 80 6 balance 0.5 30 10 10 7 balance 1 30
30 8 balance 0.5 30 10 9 balance 1 30 10 10 balance 0.5 30 50 11
balance 1 30 150 10 12 balance 1.5 30 10 150 13 balance 0.5 80 150
10 14 balance 1 150 80 10 15 balance 1.5 50 10 30 30 30 30 30 16
balance 1.5 80 10 80 80 17 balance 0.01 20 80 15 18 balance 1 6 3 5
16 19 balance 0.2 0.2 52 8 28 120 20 balance 1.3 0.3 130 18 18 22
46 21 balance 1 83 38 13 23 25 53 22 balance 0.01 35 55 23 balance
1 2 46 8 10 16 8 8
[0088] TABLE-US-00004 TABLE 4 wire molten press-bond Example
diameter ball ball first Au--Al second No. (.mu.m) sphericity
circularity bond formed bond pull test overall 1 25
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.largecircle. .largecircle. .circleincircle. 2 25 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. 3 25 .circleincircle. .largecircle.
.circleincircle. .largecircle. .largecircle. .largecircle.
.largecircle. 4 20 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 5 20
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. 6 20 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. 7 15 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 8 15 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 9 15
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.largecircle. .largecircle. .circleincircle. 10 25 .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .largecircle.
.largecircle. .circleincircle. 11 25 .circleincircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.largecircle. .circleincircle. 12 25 .circleincircle. .largecircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 13 20 .circleincircle. .largecircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 14 20 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 15 20 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 16 20 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 17 15
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. 18 15 .largecircle.
.circleincircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. 19 15 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 20 15 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 21 15 .circleincircle. .largecircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 22 15 .circleincircle. .largecircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 23 15 .circleincircle. .circleincircle.
.circleincircle. .largecircle. .largecircle. .largecircle.
.circleincircle. 24 25 .circleincircle. .largecircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 25 25 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 26 25
.largecircle. .circleincircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. 27 25 .largecircle.
.largecircle. .largecircle. .largecircle. .circleincircle.
.circleincircle. .largecircle. 28 25 .largecircle. .largecircle.
.largecircle. .largecircle. .circleincircle. .circleincircle.
.largecircle. 29 25 .largecircle. .largecircle. .largecircle.
.largecircle. .circleincircle. .circleincircle. .largecircle. 30 25
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 31 25
.circleincircle. .largecircle. .circleincircle. .largecircle.
.circleincircle. .circleincircle. .circleincircle. 32 20
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 33 20
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 34 20
.circleincircle. .largecircle. .circleincircle. .largecircle.
.circleincircle. .circleincircle. .circleincircle. 35 20
.circleincircle. .largecircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 36 20
.largecircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. .circleincircle. .circleincircle. 37 20
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 38 20
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 39 20
.circleincircle. .largecircle. .circleincircle. .largecircle.
.circleincircle. .circleincircle. .circleincircle. 40 25
.circleincircle. .largecircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 41 25
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 42 25
.circleincircle. .largecircle. .circleincircle. .largecircle.
.circleincircle. .circleincircle. .circleincircle. 43 25
.largecircle. .largecircle. .largecircle. .largecircle.
.circleincircle. .circleincircle. .largecircle. 44 25 .largecircle.
.circleincircle. .largecircle. .largecircle. .circleincircle.
.circleincircle. .circleincircle. 45 25 .circleincircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.largecircle. .circleincircle. 46 25 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. 47 15 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .largecircle.
.circleincircle. 48 15 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .largecircle.
.circleincircle. 49 15 .largecircle. .largecircle. .largecircle.
.largecircle. .circleincircle. .largecircle. .largecircle. 50 25
.circleincircle. .circleincircle. .circleincircle. .largecircle.
.circleincircle. .circleincircle. .circleincircle. 51 15
.circleincircle. .circleincircle. .largecircle. .circleincircle.
.circleincircle. .largecircle. .circleincircle. 52 15 .largecircle.
.largecircle. .circleincircle. .circleincircle. .largecircle.
.circleincircle. .circleincircle. 53 20 .largecircle. .largecircle.
.circleincircle. .largecircle. .circleincircle. .circleincircle.
.circleincircle. 54 20 .largecircle. .largecircle. .largecircle.
.circleincircle. .largecircle. .largecircle. .largecircle. 55 25
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .circleincircle. .largecircle. 56 25 .circleincircle.
.circleincircle. .largecircle. .circleincircle. .circleincircle.
.largecircle. .circleincircle. 57 15 .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .largecircle.
.largecircle. .circleincircle.
[0089] TABLE-US-00005 TABLE 5 wire press-bond Example diameter
molten ball ball first Au--Al second No. (.mu.m) sphericity
circularity bond formed bond pull test overall 58 25
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. 59 20
.largecircle. .largecircle. .circleincircle. .largecircle.
.circleincircle. .largecircle. .largecircle. 60 20 .circleincircle.
.circleincircle. .largecircle. .circleincircle. .largecircle.
.circleincircle. .circleincircle. 61 20 .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. 62 15 .circleincircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. 63 15 .largecircle. .largecircle.
.circleincircle. .circleincircle. .circleincircle. .largecircle.
.circleincircle. 64 15 .largecircle. .largecircle. .circleincircle.
.largecircle. .largecircle. .largecircle. .largecircle. 65 25
.circleincircle. .circleincircle. .largecircle. .circleincircle.
.largecircle. .largecircle. .circleincircle. 66 25 .largecircle.
.largecircle. .circleincircle. .largecircle. .largecircle.
.largecircle. .largecircle. 67 25 .circleincircle. .largecircle.
.largecircle. .largecircle. .largecircle. .circleincircle.
.largecircle. 68 20 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 69 20
.largecircle. .largecircle. .circleincircle. .largecircle.
.largecircle. .circleincircle. .largecircle. 70 20 .largecircle.
.largecircle. .circleincircle. .largecircle. .largecircle.
.largecircle. .largecircle. 71 20 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. 72 15 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 73 15 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 74 15
.largecircle. .largecircle. .largecircle. .largecircle.
.circleincircle. .largecircle. .largecircle. 75 15 .largecircle.
.largecircle. .largecircle. .circleincircle. .circleincircle.
.largecircle. .largecircle. 76 15 .circleincircle. .largecircle.
.circleincircle. .largecircle. .largecircle. .largecircle.
.largecircle. 77 15 .largecircle. .largecircle. .largecircle.
.largecircle. .circleincircle. .largecircle. .largecircle. 78 15
.largecircle. .largecircle. .circleincircle. .largecircle.
.circleincircle. .largecircle. .largecircle. 79 15 .largecircle.
.largecircle. .circleincircle. .largecircle. .circleincircle.
.largecircle. .largecircle. 80 15 .circleincircle. .circleincircle.
.largecircle. .circleincircle. .largecircle. .largecircle.
.circleincircle. 81 15 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle.
[0090] TABLE-US-00006 TABLE 6 Comp. wire molten press-bond Example
diameter ball ball first Au--Al second No. (.mu.m) sphericity
circularity bond formed bond pull test overall 1 15 .largecircle.
.DELTA. .largecircle. .largecircle. .largecircle. .largecircle.
.DELTA. 2 25 .largecircle. .DELTA. .largecircle. .largecircle.
.largecircle. .largecircle. .DELTA. 3 20 .DELTA. .DELTA. .DELTA.
.DELTA. .largecircle. .largecircle. .DELTA. 4 15 .largecircle.
.DELTA. .largecircle. .largecircle. .DELTA. .DELTA. .DELTA. 5 25
.largecircle. .DELTA. .largecircle. .largecircle. .largecircle.
.largecircle. .DELTA. 6 20 .largecircle. .DELTA. .largecircle.
.largecircle. .largecircle. .largecircle. .DELTA. 7 15
.largecircle. .DELTA. .largecircle. .largecircle. .largecircle.
.largecircle. .DELTA. 8 25 .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .DELTA. .DELTA. .DELTA. 9 20
.largecircle. .DELTA. .largecircle. .largecircle. .largecircle.
.largecircle. .DELTA. 10 15 .largecircle. .DELTA. .largecircle.
.largecircle. .largecircle. .largecircle. .DELTA. 11 25 .DELTA.
.DELTA. .DELTA. .DELTA. .largecircle. .largecircle. .DELTA. 12 20
.DELTA. .largecircle. .DELTA. .DELTA. .largecircle. .largecircle.
.DELTA. 13 15 .DELTA. .DELTA. .DELTA. .DELTA. .largecircle.
.largecircle. .DELTA. 14 25 .largecircle. .largecircle.
.largecircle. .largecircle. .DELTA. .DELTA. .DELTA. 15 20 .DELTA.
.DELTA. .DELTA. .DELTA. .circleincircle. .largecircle. .DELTA. 16
15 .DELTA. .DELTA. .DELTA. .DELTA. .largecircle. .largecircle.
.DELTA. 17 25 .largecircle. .largecircle. .largecircle.
.circleincircle. .largecircle. .DELTA. .DELTA. 18 20
.circleincircle. .largecircle. .circleincircle. .circleincircle.
.DELTA. .DELTA. .DELTA. 19 15 .DELTA. .DELTA. .DELTA. .DELTA.
.largecircle. .DELTA. .DELTA. 20 15 .DELTA. .DELTA. .largecircle.
.largecircle. .largecircle. .largecircle. .DELTA. 21 15 .DELTA.
.DELTA. .DELTA. .DELTA. .largecircle. .DELTA. .DELTA. 22 15 .DELTA.
.DELTA. .DELTA. .DELTA. .largecircle. .DELTA. .DELTA. 23 15
.circleincircle. .circleincircle. .DELTA. .DELTA. .DELTA. .DELTA.
.DELTA.
[0091] It is clear from the above results that, for the Au alloy
bonding f the present invention, when the amounts added of the
trace elements are within the specified ranges, satisfactory
bonding results are obtained even in the case that the diameter of
the fine wire is 23 .mu.m or smaller.
[0092] In contrast thereto, for each of the comparative examples,
the intended properties were not obtained for reasons as
follows.
[0093] For the comparative examples corresponding to the first
group: [0094] for Comparative Example 1, because the Au alloy
bonding wire contains the trace element Ca, which is not included
under the present invention; [0095] for Comparative Example 2,
because the Au alloy bonding wire contains the trace element Zn,
which is not included under the present invention; [0096] for
Comparative Example 3, because the content of the trace element Ce
exceeds the specified amount; [0097] for Comparative Example 4,
because the Au alloy bonding wire contains the trace element Zn,
which is not included under the present invention, and does not
contain the trace element Mg, which is included under the present
invention; [0098] for Comparative Example 5, because the Au alloy
bonding wire contains the trace element Ca, which is not included
under the present invention; [0099] for Comparative Example 6,
because the Au alloy bonding wire contains the trace element Zn,
which is not included under the present invention; [0100] for
Comparative Example 7, because the Au alloy bonding wire does not
contain a trace element other than Mg and Ce included under the
present invention; [0101] for Comparative Example 8, because the Au
alloy bonding wire does not contain the trace element Mg, which is
included under the present invention; [0102] for Comparative
Example 9, because the Au alloy bonding wire does not contain a
combination with the trace element Ce or Be, which is included
under the present invention; [0103] for Comparative Example 10,
because the Au alloy bonding wire does not contain a trace element
other than Mg and Be included under the present invention; [0104]
for Comparative Example 11, because the content of the trace
element Be exceeds the specified amount; [0105] for Comparative
Example 12, because the content of the trace element Si exceeds the
specified amount; [0106] for Comparative Example 13, because the
content of the trace element Ce exceeds the specified amount;
[0107] for Comparative Example 14, because the content of the trace
element Mg exceeds the specified amount; [0108] for Comparative
Example 15, because the total content of the trace elements exceeds
the specified amount; [0109] for Comparative Example 16, because
the total content of the trace elements exceeds the specified
amount; [0110] for Comparative Example 17, because the content of
the alloying element Pt falls short of the specified amount.
[0111] For the comparative examples corresponding to the second
group: [0112] for Comparative Example 18, because the content of
the trace element Ce falls short of the specified amount; [0113]
for Comparative Example 19, because the content of the trace
element Ca exceeds the specified amount; [0114] for Comparative
Example 20, because the content of the trace element Mg exceeds the
specified amount; [0115] for Comparative Example 21, because the
total content of the trace elements exceeds the specified amount,
and the content of the trace element Ca exceeds the upper limit,
and moreover the the trace elements Be and Si as the objective of
the present invention are not contained in combination; [0116] for
Comparative Example 22, because the content of the alloying element
Pd falls short of the specified amount; [0117] for Comparative
Example 23, because the total content of the alloying elements Pd
and Pt exceeds the specified amount.
[0118] The alloy of the present invention is suitable for bonding
wires used in automotive semiconductor devices, in particular, and
in semiconductors for service under ambience sometimes becoming
hot.
* * * * *