JPH06112256A - Bonding wire for semiconductor element - Google Patents

Abstract

(57) [Summary] [Purpose] The strength of the Au wire is improved by adding Pd, Pt, Rh, Ir, Os, and Ru, and at the same time, the addition amount is kept in an appropriate range to prevent A point peeling in the high temperature storage test. Reduce the incidence. [Structure] High-purity Au with Pd, Pt, Rh, Ir, O
At least one of s and Ru is contained in an amount of 0.0003 to 0.1 wt% and at least one of Sc, Y and rare earth elements is contained in an amount of 0.0001 to 0.05 wt%, and is melt cast. The wire diameter is 25 after the wire is processed and then annealed on the way and then wire-drawn.
A μm bus bar was molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor element bonding Au wire used for connecting a chip electrode of a semiconductor element and an external lead on a substrate, and more particularly to a wire suitable for a wire bonding method and a bump connecting method. .

[0002]

2. Description of the Related Art Conventionally, for example, the tip of an Au wire hung from the tip of a capillary is melted by an electric torch to form a ball, and the ball is made of Al or A on the chip.
a bump connection method in which bump electrodes are formed by crimping and cutting on electrodes made of l alloy,
A wire bonding method is known in which, after joining, the chip electrode and the external lead are connected to each other by guiding the external electrode to the external lead in a loop shape and crimping and cutting the external lead.

Further, as an Au wire useful for this type of bonding, as disclosed in JP-B-62-22448, among Pd, Pt, Rh, Ir, Os, Ru (that is, Pt group element). One or more of Ca, Be, Ge, Ni, Fe, Co and Ag are added at the same time as one or more of the above are added.

[0004]

However, in the above-mentioned conventional bonding wire, although the strength of the Au wire can be improved by adding the above-mentioned elements, the bonding surface between the Al electrode on the chip and the ball (that is, A Point) Au and A
There has been a problem that the interdiffusion of 1 is hindered, and as a result, the occurrence rate of A-point peeling in the high temperature storage test after bonding becomes high.

The present invention has been made in view of such conventional circumstances, and an object thereof is to improve the strength of Au wire by adding a Pt group element, and at the same time, peel off at point A in a high temperature storage test. To reduce the incidence of.

[0006]

In order to achieve the above object, the semiconductor element bonding wire of the present invention comprises high purity Au and at least one of Pd, Pt, Rh, Ir, Os and Ru. Of 0.003 to 0.1 wt%, and at least one of Sc, Y and rare earth elements,
It is characterized by containing 0.0001 to 0.05 wt%.

[0007]

According to the above structure, Pd, Pt, Rh, I
When the amount of r, Os, Ru added is within the range of 0.0003 to 0.1 wt% and at least one of Sc, Y and rare earth elements is added at the same time, the breaking strength of the Au wire is improved. At the same time, the mutual diffusion of Au and Al at the bonding surface between the ball and the underlying metal layer of the chip electrode is moderated,
The joint strength at the joint surface, that is, at the point A is improved.

However, Pd, Pt, Rh, Ir, O
If the addition amount of s and Ru is less than 0.0003 wt%, satisfactory rupture strength cannot be obtained, and the mutual diffusion of Au and Al on the joint surface becomes excessive, resulting in deterioration of joint strength. Further, if the addition amount of Pd, Pt, Rh, Ir, Os, and Ru exceeds 0.1 wt%, mutual diffusion of Au and Al on the joint surface is hindered, the joint strength is lowered, and A point peeling occurs. The rate is high.

Further, if the added amount of Sc, Y, or a rare earth element is less than 0.0001 wt%, the above-mentioned effect cannot be obtained, and if the total added amount of these added elements exceeds 0.05 wt%, ball formation is achieved. At this time, the shape of the ball is not stable, the bonding strength between the ball and the chip electrode is reduced, and the occurrence rate of A point peeling increases.

Therefore, Pd, Pt, Rh, Ir, Os,
The amount of Ru added is in the range of 0.0003 to 0.1 wt% and S
c, Y, addition amount of rare earth element is 0.0001 to 0.05
Each was set in the range of wt%.

[0011]

EXAMPLES Specific examples and comparative examples will be described below. High-purity Au (99.99% or more), Pd, P
t, Rh, Ir, Os, Ru, Sc, Y, La, Ce,
Ca, Be, Ge, Ni, Fe, Co, and Ag were added based on the contents shown in Table 1 and melt-cast, then groove roll processed, and then annealed in the middle to obtain a wire. Each sample was formed by forming a bus bar having a wire diameter of 25 μm by drawing and further removing stress sufficiently.

Sample No. 1 in Table 1 1-9 are high purity Au
Of Pd, Pt, Rh, Ir, Os, Ru (hereinafter referred to as additive element I), and at the same time, Sc, Y, a rare earth element (hereinafter referred to as additive element II).
It is a product of the present invention to which at least one of the above is added.

Further, the sample No. Sample Nos. 10 to 12 are high-purity Au, which is a comparative product in which at least one of the additional elements I is added and the additional element II is not added. 1
3 to 15 include Ca, Be, Ge, Ni, Fe, Co and Ag as well as adding at least one kind of the additional element I.
It is a comparative product to which at least one of the above is added.

In Table 1, L is a representative rare earth element.
a and Ce are selected, but other rare earth elements are La and C
It is omitted because it is the same as e.

Each of the samples prepared as described above was heat-treated to have a predetermined elongation, and then the breaking strength and the rate of peeling at point A were measured.

The breaking strength of each sample was 100 m between gauge marks.
The breaking load when a tensile test was carried out at a tensile speed of 10 mm / min at m was measured.

As for the occurrence rate of A-point peeling, after bonding each sample on a chip electrode of an Al thin film (thickness of 0.8 μm) under predetermined conditions, the sample was left under high temperature conditions where Al easily diffuses (200 ° C. × 300). Time), then point C (loop part)
Was pulled to calculate the rate at which the bonding wire was peeled from the bonding surface with the chip. These results are also shown in the table.

[0018]

[Table 1]

[0019]

[Table 2]

Sample No. From the measurement results of 1 to 9, the additive element I (Pd, Pt, Rh, I
(r, Os, Ru) within the range of 0.0003 to 0.1 wt% and at least one additive element II (Sc, Y, rare earth element) is simultaneously added, the desired breaking strength is obtained. At the same time, it was confirmed that peeling did not occur at the joint surface (point A) between the ball and the underlying metal layer of the chip electrode, and the joint strength at the joint surface was improved.

Sample No. From the measurement results of 10 to 12, it can be confirmed that when only the additional element I is added, the fracture strength varies depending on the type of the additional element and the difference in the addition amount, but the occurrence rate of A-point peeling is high. It was

Further, the sample No. From the measurement results of 13 to 15, in addition to the above-mentioned additional element I, Ca, Be, Ge, N
When i, Fe, Co, and Ag were added, it was confirmed that the occurrence rate of A-point peeling was high, although some breaking strength was obtained.

[0023]

Since the semiconductor element bonding wire according to the present invention is constructed as described above, Pd, Pt, R
While maintaining the effect of improving the breaking strength by the addition of h, Ir, Os, and Ru as it is, by limiting the addition amount within a predetermined range and adding Sc, Y, and a rare earth element in a predetermined amount, after bonding, The incidence of peeling at point A in the high temperature storage test can be significantly reduced.

Therefore, a predetermined strength can be obtained after bonding, and the bonding strength between the ball and the chip electrode can be remarkably improved to provide a semiconductor element bonding wire which is extremely useful for the wire bonding method and the bump connecting method. It was

Claims (1)

[Claims] 1. High-purity Au with Pd, Pt, Rh, I
0.0003 of at least one of r, Os and Ru
A bonding wire for a semiconductor device, which contains 0.0001 to 0.05 wt% of at least one of Sc, Y, and a rare earth element.