JPS59139663A - Cu-alloy fine wire for wire bonding on semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the Cu alloy fine wire having strength at high temperature at low cost by a method wherein the titled Cu-alloy fine wire is composed of the specified % of Pd, and one kind or more of Ge, Be and Ca are contained as occasion demands, thereby enabling to let the remainder to contain Cu and inevitable impurities. CONSTITUTION:The breaking strength at high temperature and the tensile strength at high temperature of the Pd ingredient is to be increased by completely solidifying Cu. The content of the Cu is established at 0.1-50%. In the ingredient of Ge, Be and Ca when they are coexisted with Pd, it has a function wherein the strength at high temperature is further increased. The content of Ge, Be and Ca is set at 0.0005-0.5%. After a cold rolling has been performed on the above, it is processed into wire material by performing the prescribed cycles of annealing, wherein annealing at 400 deg.C in vacuum is considered as one cycle. Subsequently, a stripping process is performed on said wire material using dies, a wire-drawing process is performed, and the prescribed cycles of wire-drawing process wherein annealing at 400 deg.C in vacuum is considered as one cycle are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an Ou alloy thin wire suitable for use in wire bonding performed during the manufacture of semiconductor devices.

In general, transistors, ICs, and LSIs are known as semiconductor devices. For example, semiconductor devices such as ICs include (a) one side of a Cu alloy plate or strip ((,
, Ag.

A lead material made of lQi and its alloy with a plating layer formed thereon is prepared.

(b) Press punching is performed on the above-mentioned lead frame to form a lead frame that conforms to the shape of the semiconductor device to be manufactured;
Alternatively, a semiconductor element such as Go is bonded by thermocompression through the plated layer, (d) Au'-! , or Au alloy thin wire, wire bonding is performed by thermocompression bonding or ultrasonic thermocompression bonding method,
(e) the semiconductor element, the Au or Au alloy thin wire;
and the lead frame where the semiconductor element is attached are packed in plastic, (f) finally 5
The lead frame is manufactured by the main steps (a) to (f) above, in which the interconnected portions of the lead frame are cut out to form a lead material.

As mentioned above, when manufacturing semiconductor devices, expensive Au or Au alloy thin wires are used for wire bonding (connection), which is one of the reasons for the high cost of semiconductor devices. Au and Au alloy fine wires do not have sufficient mechanical strength, especially breaking strength, at high points during bonding, so when high-speed wire bonding equipment is used, wires may break or slack may occur in the bonding, resulting in short circuits. This had the problem of not causing a short circuit (short circuit).

From the above-mentioned viewpoint, the present inventors have discovered that a +1(]] wire for wire bonding has the required high-temperature strength,
As a result of conducting research to develop a thin wire for wire bonding that has a low cost for the wire itself, we found that it contains Pd: 0.1 to 50, and is suitable for heavy machinery. If necessary, contain one or more of Ge, Be, and Ca: 0.005 to 0.5%, and the remainder is Cu and non-OIJ silicon impurities.
U alloy fine wire has excellent high temperature strength, and therefore,
When this wire is used for wire bonding of semiconductor devices, it is possible to completely eliminate the above-mentioned problems due to insufficient strength. Au and A to be alloyed
It was discovered that the cost was significantly lower than that of u-alloy.

This invention was made based on the above knowledge, and the reason why the component composition was limited as described above will be explained below.

(a) Pa The Pd component has the effect of completely dissolving in Cu and improving high temperature strength, that is, high temperature breaking strength and high temperature tensile strength, but if its content is less than 0.1%, the above-mentioned On the other hand, if the content exceeds 50%, the desired effect cannot be obtained.
Since the wire drawability deteriorates, the amount of wire drawing is determined to be 0.1 to 50.

(b o, e, Be, and Ca These components have the effect of further improving high-temperature strength when coexisting with Pd, so they are included as necessary, but if the content is 0.005 If the content is less than 0.5%, the desired high-temperature strength improvement effect cannot be obtained; on the other hand, if the content exceeds 0.5%, the hardness will increase significantly, making wire drawing difficult, and may damage semiconductor elements during wiring. Because of this, the quantity was set at 0005 to 0.5 candy.

Finally, we will specifically explain θ in the Cu alloy thin film of the present invention.

Example Molten metals having the components and compositions shown in Table 1 were prepared by the usual vacuum melting method, and cast into billets with a diameter of 55 mm and a length of 150 mm. :5
The dimensions were 0 peep φ x length: 140 mm, and then cold rolling was performed using a grooved roll at a cross-sectional processing rate of 25%, followed by one cycle of annealing at a temperature of 400°C in vacuum. By applying one predetermined curve, the diameter: 8m
After processing the wire into a wire rod with a diameter of mφ, the wire was peeled using a die to obtain a diameter of 5 mmφ, and then the wire was drawn using a die at a cross-sectional processing rate of 50゜, and the wire was heated in a vacuum at a temperature of 5 mm.゛By applying a wire drawing process with one cycle of heating and holding annealing at 400°C,
Diameter: 25μ? Invention Cu alloy fines with n @1 to 11
were manufactured respectively.

Next, the resulting Cu alloy fine I'+M of the present invention
Regarding 1 to 11, for the purpose of evaluating high temperature strength, the work during wire botting y = ! f iy equivalent 25
For the purpose of evaluating the high-temperature breaking strength at 0° C. and the bonding strength after bonding of 81 semiconductor element-\, the shear loads of the bonded portions were measured. These measurement results are also shown in Table 1. Table 1 also shows the measurement results of a thin Au wire with a diameter of 25 μm for the purpose of comparison.

From the results shown in Table 1, the present invention Cu alloy fine) 91~
It is clear that No. 11 has significantly superior high temperature strength and bonding strength compared to the Au thin wire.

As mentioned above, the Cu alloy thin wire of the present invention has excellent high-temperature strength and bonding strength, so when it is used for wire bonding of semiconductor devices, it does not cause breakage or sagging, especially when wire bonding is increased. It is possible to apply thinner wires, and it is possible to use Au and A
It brings about industrially useful effects such as being significantly cheaper than U-alloy thin wire.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo and 1 other person

Claims (1)

[Claims] (1) A fine Cu alloy wire for wire bonding of semiconductor devices, characterized in that it contains 1 to 50% by weight of pa:o, with the remainder consisting of O and inevitable impurities. Contains Pd: 0.1 to 50% by weight, and further contains Go. One or more of Be and Ca 0.0
(Contains 15 to 0.5% by weight, and the balance 9 is Cu and non-01'
A fine Cu alloy for wire bonding of semiconductor devices characterized by having a composition consisting of certain impurities. i
l.