JPH10284547A - Pressure welding tool for lead material bonding for ic chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure welding tool for lead material bonding for IC chip, with which there is no substrate crack nor solder release. SOLUTION: Concerning the pressure welding tool in the structure bonding the main body of tool, which is constituted by performing the vapor-phase synthesization and deposition of polycrystal diamond film on the surface of substrate, to a shunk part with built-in heater while using a solder material, the substrate for the main body of this tool is composed of hard metal having the composition of inevitable impurity containing tungsten carbide in 90 to 98 wt.% as a dispersed phase forming component and Co as remaining bound phase forming component, besides, this solder material is composed of Cu alloy having the composition of Cu and inevitable impurity while containing Ag in 5 to 15 wt.% and P in 1 to 10 wt.% and further, the shunk part is composed of Ni alloy having the composition of Ni and inevitable impurity while containing Cr in 10 to 25 wt.% and Fe in 5 to 15 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to
The present invention relates to a pressure welding tool for bonding a lead material of an IC chip, in which accumulation of residual stress with time is extremely small, and therefore, even when the size is increased, cracking of the base material or brazing peeling due to the residual stress does not occur.

[0002]

2. Description of the Related Art Conventionally, in general, when manufacturing an IC chip, as shown in, for example, a schematic explanatory view of FIG. The tip of a lead material such as a Cu alloy is heated to 500 to 1000 ° C. by a built-in heater via a bump such as an Au-In alloy (solder material) formed on the surface of an IC chip in the same arrangement as the lead material. Bonding is performed by reducing the pressure with a heated pressure welding tool. In addition, as a pressure welding tool used for bonding a lead material of an IC chip,
For example, as described in Japanese Patent No. 2520971, a tool body has a thickness of 0.5 to 5 mm, and
A hot filament method, a microwave plasma CVD method, and a high-frequency plasma CV are applied to the surface of a substrate made of an iC-based sintered body, a Si ₃ N ₄ -based sintered body, or an AlN-based sintered body.
The tool body is formed by forming a polycrystalline diamond film having an average layer thickness of 5 to 300 μm by using a vapor phase synthesis method such as a method D. The tool body is made of a Kovar alloy, an Invar alloy, and a W
There is known a structure in which a brazing member made of various Ag alloys or Cu alloys is joined to a shank portion having a built-in heater made of a C-base cemented carbide or the like.

[0003]

On the other hand, in recent years, high integration of semiconductor devices has been remarkable, and as a result, the area of IC chips has increased, and the press-fitting tools used for manufacturing the same have tended to increase in size. In addition to the above-described conventional press-welding tools, in many other press-welding tools, the larger the size of the press-welding tool, the more likely it is that cracks will occur in the body of the tool body constituting the press-welding tool in practical use,
At present, peeling tends to occur at the brazing portion between the base and the shank portion, and shortening of service life is inevitable.
This is considered to be caused by the repetition of the working mode, that is, the step of pressing the welding tool heated to 500 to 1000 ° C. to the lead material at room temperature and heating the bumps to the melting temperature via this lead material to perform the bonding. In this case, the press-welding tool, especially the substrate constituting the same, is subjected to rapid repetition of heating and cooling. At the same time, the residual stress generated at the same time accumulates over time, and the residual stress in the substrate is reduced by the press-welding tool. It is understood that the larger the size, the larger the size of the residual stress, and finally, the accumulated and increased residual stress causes substrate cracking and brazing peeling.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, as a result of conducting research to develop a press-welding tool in which the generation of residual stress is small and the residual stress does not accumulate over time, the base of the press-welding tool is used as a dispersed phase forming component by using tungsten carbide ( Hereinafter, indicated by WC): 90 to
98%, the balance being a cemented carbide having a composition consisting of Co and inevitable impurities as a binder phase forming component,
In addition, the brazing material is made of Ag: 5 to 15%, P: 1 to 10%
And the remainder is made of a Cu alloy having a composition consisting of Cu and unavoidable impurities.
r: 10 to 25%, Fe: 5 to 15%, and the remainder is composed of a Ni alloy having a composition of Ni and unavoidable impurities (more than% by weight, the following% indicates% by weight). The press-welding tool has a structure in which the base suppresses the generation of residual stress, and the brazing material acts to suppress the accumulation of residual stress. Research results have shown that, in combination with the excellent heat resistance provided by the shank portion, use over an extremely long period is possible.

The present invention has been made on the basis of the above-mentioned research results. A tool body formed by vapor-phase synthesis deposition of a polycrystalline diamond film on the surface of a substrate is provided by using a brazing material and a shank having a built-in heater. In the press-welding tool having a structure joined to the part, the base of the tool main body contains 90 to 98% of tungsten carbide as a dispersed phase forming component, and the balance is composed of Co as a bonding phase forming component and unavoidable impurities. The brazing material is made of a Cu alloy containing Ag: 5 to 15%, P: 1 to 10%, and the rest having a composition of Cu and unavoidable impurities. Further, the above-mentioned shank portion is composed of a Ni alloy containing Cr: 10 to 25% and Fe: 5 to 15%, and the remainder is composed of a Ni alloy having a composition consisting of Ni and unavoidable impurities. The present invention is characterized by a pressure welding tool for bonding lead material of an IC chip which does not cause delamination.

In the pressure welding tool of the present invention, the thickness of the polycrystalline diamond film formed on the surface of the substrate by the ordinary vapor phase synthesis method is such that the thickness of the substrate is 2 to 5 mm, It is preferable that the thickness is 30 to 100 μm. When forming the polycrystalline diamond film, as a pretreatment, the substrate is subjected to (a) surface etching treatment for removing a bonding phase forming component on the surface, b)
Surface treatment, (c) heat treatment for coarsening surface WC grains at a temperature of 1300 to 1550 ° C. for a predetermined period of time in an Ar atmosphere of 70 to 150 atm, and above (a) to (c)
The surface treatment is preferably performed to improve the adhesion of the polycrystalline diamond film.

Next, the reason why the compositions of the base, the brazing material and the shank constituting the press-welding tool of the present invention are determined as described above will be described. (1) Substrate The WC of the cemented carbide constituting the substrate has a good thermal conductivity and an action of suppressing the generation of residual stress. However, if the ratio is less than 90%, the desired effect on the action is obtained. Cannot be obtained, and the ratio of the binder phase forming component becomes relatively large, and the material tends to be deformed. On the other hand, if the ratio exceeds 98%, the ratio of the binder phase forming component becomes relatively small, resulting in sintering. The ratio is determined to be 90 to 98% since the desired strength cannot be ensured due to a decrease in the property.

(2) Brazing filler metal (a) Ag The Ag component has a function of lowering the melting point of the brazing filler metal, thereby increasing its fluidity and enabling satisfactory brazing with a small amount of brazing filler metal. In the coexistence with the Cu component, which is the main component of, there is an effect of absorbing the residual stress, thereby suppressing the accumulation of the residual stress with time, and promoting heat transfer from the heated shank portion to the base. Content is 5%
If the content is less than 15%, the desired effect cannot be obtained. On the other hand, if the content exceeds 15%, the strength of the brazed portion decreases, so that the content is 1 to 15%, preferably 7%. １３13%.

(B) The PP component has the effect of lowering the melting point of the brazing material and improving its own strength, thereby improving the strength of the brazed portion. If the desired effect cannot be obtained in the above-mentioned action, and if the content exceeds 10%, the brazed portion rapidly becomes brittle,
The content was determined to be 1 to 10%, preferably 3 to 8%.

(3) Shank section The shank section has its own 50 heaters by a built-in heater.
It is required to have excellent heat resistance and oxidation resistance because it has a role of heating to 0 to 1000 ° C. and maintaining the temperature of the brazed tool body at the same temperature. Therefore, the Cr component of the Ni alloy constituting the shank portion is:
Although it is contained as a component for improving heat resistance and oxidation resistance, if the proportion is less than 10%, desired heat resistance and oxidation resistance cannot be secured, while the proportion is 25%.
, The strength is reduced, so the ratio is set to 10 to 25%. Similarly, the Fe component has the effect of improving the strength. However, if the proportion is less than 5%, the desired strength cannot be ensured. On the other hand, if the proportion exceeds 15%, the heat resistance and the acid resistance are reduced. Since the tendency to decrease in chemical properties appears, the proportion is 5 to 15
%.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The press-contact tool of the present invention will be specifically described with reference to embodiments. First, for the purpose of producing a substrate, as raw material powder, fine WC powder having an average particle size in the range of 0.5 to 3 μm, coarse WC powder having an average particle size in the range of 3 to 10 μm, and Average particle size: 1.2 μmCo
Powders are prepared, and each of these raw material powders is blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 1 ton / cm ^2. The powder is sintered in a vacuum of 1 × 10 ⁻³ torr at a predetermined temperature in the range of 1450 to 1550 ° C. for 1 hour, and the resulting cemented carbide is machined to a length of 12 mm. × Width: 4 mm × Thickness: 2.5 mm to produce a cemented carbide substrate, and then the surface of the cemented carbide substrate is subjected to (a) a surface etching treatment by immersion in a 5% nitric acid aqueous solution for 5 minutes ( Hereinafter, referred to as surface treatment a).
(B) Ultrasonic surface scratching treatment (hereinafter, referred to as surface treatment b) for 10 minutes in alcohol containing diamond powder having a mean particle size of 10 μm dispersed therein, (c) 1480 ° C. in an Ar atmosphere at 100 atm. 1 hour holding surface W
After subjecting the C grains to coarsening heat treatment (hereinafter referred to as surface treatment c) and at least one of the surface treatments a to c in combination shown in Table 1, one of the gas phase synthesis methods The reaction gas composition: CH ₄ (flow rate: 10 cc / min) + H
₂ (flow rate: 500 cc / min), atmospheric pressure: 50 torr, microwave output: 2 kw, substrate temperature: 900 ° C., and vapor phase synthesis was carried out under the following conditions. Tool bodies A to G were manufactured by forming a thick polycrystalline diamond film.

In a graphite crucible, Ag alloy melts having the compositions shown in Table 2 were prepared, cast into ingots, and hot-rolled into hot-rolled sheets having a thickness of 0.2 mm. Cold rolled on the rolled sheet, thickness: 0.05mm
The brazing materials a to g were respectively manufactured.

Further, in the same graphite crucible, a Ni alloy melt having the composition shown in Table 3 is prepared, precision cast (lost wax method), and then machined to obtain the same size as the surface size of the substrate. The shank parts A to O having the brazing surfaces of No. 1 to No. 3 were manufactured.

Next, the above-mentioned tool body, brazing material, and shank portion are set in combinations shown in Table 5,
The press-welding tool 1 of the present invention is obtained by brazing the tool main body to the shank portion via a brazing material under a condition of holding at a predetermined temperature in the range of 850 to 950 ° C. for 10 minutes in an Ar atmosphere.
To 7 were each manufactured.

For the purpose of comparison, the tool body has a polycrystalline diamond film having an average layer thickness of 50 μm in all cases, but the substrate is made of Si ₃ N ₄ -5% Y ₂ O ₃ -3.
% Al ₂ Si ₃ N ₄ groups sintered body having a composition consisting of O ₃ (hereinafter referred to as tool body H), AlN-3% Y 2 O 3 -
AlN-based sintered body having a composition of 2% CaO (hereinafter, referred to as tool body I) and SiC-based sintered body having a composition of SiC-2% B ₄ C (hereinafter, tool body J)
And a shank portion of Fe-19.7% N
i-19.3% Co-0.95% Mn The shank portion (hereinafter referred to as shank portion) of a Fe-Ni-Co alloy having a composition of Mn and Cu-32% Z as a brazing material.
Cu-Zn-Ag having a composition consisting of n-30% Ag
Comparative welding tools 1 to 3 were manufactured under the same conditions except that an alloy brazing material (hereinafter, referred to as brazing material g) was used.

With respect to the press-welded tools 1 to 7 of the present invention and the comparative press-welded tools 1 to 3 obtained as described above, the front end face of the polycrystalline diamond film was machined to a length of 15 mm × width: 5 mm and the surface roughness was set to Rmax. Then, an accelerated durability test was performed under the following conditions in a state of polishing to 0.8 μm. That is, in the accelerated durability test, oxygen-free copper and an Al alloy (containing 2% of Si) were used instead of the IC chip and the lead material shown in FIG. 1, and both had a surface of 20 mm × 10 mm and a thickness of 10 m.
m dimension, one surface dimension is 0.5mm x
Using a water-cooled box in which 0.5 mm is provided and two protrusions each having a height of 3 mm are arranged in two rows along the length direction by 10 pieces, and the above various press-welding tools are provided on the surface of the water-cooled box on which the protrusions are provided. While heating at 600 ° C., one cycle was performed for 8 seconds with a load of 10 kg, and 3 seconds of the cycle was used as a press contact time, and the number of cycles until the service life was reached was measured. Table 4 shows the results of these measurements.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

[Table 4]

[0021]

According to the results shown in Table 4, in the press-welding tools 1 to 7 of the present invention, the generation of residual stress is suppressed by the combination of the tool body, the brazing material, and the shank as described above, and the residual stress is reduced. Because accumulation over time is prevented,
While excellent durability is exhibited over a long period of time without occurrence of substrate cracking or brazing peeling, the comparative pressure welding tools 1 to 3
It is evident that in any case, the service life can be reached in a relatively short time due to cracking of the substrate or delamination. As described above, the press-welding tool of the present invention can be used for a long period of time without causing cracks in the substrate or peeling off by brazing even if the tool is enlarged, so that it is sufficiently satisfactory for high integration of semiconductor devices. Corresponding.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a use mode of a pressure welding tool.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C30B 29/04 C30B 29/04 A H01L 21/603 H01L 21/603 C

Claims (1)

[Claims] 1. A press-welding tool having a structure in which a tool body formed by vapor-phase synthetic deposition of a polycrystalline diamond film on a surface of a base is joined to a shank portion with a built-in heater using a brazing material. Tungsten carbide as a dispersed phase forming component: 90 to 98
Wt%, the balance being Co as the binder phase forming component.
And a cemented carbide having a composition consisting of unavoidable impurities. The brazing material contains Ag: 5 to 15% by weight, P: 1 to 10% by weight, and the remainder consists of Cu and unavoidable impurities. The shank portion is composed of a Cu alloy having a composition of 10 to 25% by weight of Cr, 5 to 15% by weight of Fe, and a balance of Ni and unavoidable impurities. A pressure welding tool for bonding a lead material of an IC chip, wherein the tool is free from cracking of a base and brazing peeling.