JP2001138075A - Method for welding solid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To weld various kinds of metals in a solid state without using a brazing filler material. SOLUTION: In a chlorination processing part 10, a hydrochloric acid vapor blowoff part 18 is arranged above a transfer device 12. By the hydrochloric acid vapor blowoff part 18, hydrochloric acid vapor 22 is sprayed on members 14 to be welded which consist of metal transferred by the transfer device 12, and the surfaces of the members 14 are chlorinated. Chlorinated members 14A, 14B to be welded are stacked on a welding table 36 provided in the chamber 34 of a welding processing part 30. These members 14 are pressed to one another by a welding cylinder 40, are heated by heaters 38, 46, and are welded in the solid-object state. A nitrogen gas is supplied from a nitrogen gas supply part 48 to the chamber 34 to prevent the oxidation of the heated members 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid joining method for joining metals, and more particularly to a solid joining method for joining metals directly in a solid state without using a flux or a brazing material.

[0002]

2. Description of the Related Art Conventionally, when joining materials to be joined between metals such as copper and copper or copper and tin, a brazing material such as solder (joining material) is used.
Is generally performed. On the other hand, in the semiconductor device manufacturing field, an electrode (pad) made of aluminum formed on a semiconductor chip and a gold-plated substrate electrode portion of a package substrate are electrically connected to each other by a fine gold wire (wire) without using a brazing material. It is trying to connect.

[0003]

In the method of joining metal members to be joined using a brazing material, the displacement of the materials to be joined is liable to occur due to melting and joining of the brazing materials, so that fine processing is performed. Not suitable for Also, to melt the brazing material,
A part of the brazing material protrudes around the joint, which impairs the appearance. On the other hand, in the field of manufacturing semiconductor devices, a gold wire is connected to an aluminum electrode (aluminum pad) of a semiconductor chip without using a brazing material. This connection is usually
The tip of the gold wire is melted to form a molten ball, and the molten ball is joined to an aluminum pad.

However, when metals are directly joined without using a brazing material, the metals that can be joined are very limited.
In other words, in recent years, with the miniaturization of patterns due to high integration, copper wiring having excellent conductivity has been used. However, copper is very easily oxidized and easily oxidized when heated, so that a gold wire cannot be directly connected without using a flux, a brazing material, or the like.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and it is an object of the present invention to be able to join various metals in a solid state without using a brazing material.

[0006]

In order to achieve the above object, in a solid joining method according to the present invention, at least one of members to be joined made of the same or different metals to be joined to each other is chlorinated. Thereafter, the two are brought into contact with each other and joined.

According to the present invention having the above-described structure, the member to be joined made of metal is subjected to chlorination treatment, and chlorine which is easily bonded to the metal is present on the surface of the member to be joined. Since the metal bond is diffused and cut, and the cut joint is connected to the other member to be joined, the two members to be joined made of metal can be joined to each other in a solid state without using a brazing material. it can. In addition, since chlorine is not as reactive as fluorine, the degree of chlorination can be easily controlled, and variations in the bonding state (bonding strength) can be reduced.

The chlorination treatment may be performed by exposing the material to be joined to chlorine gas or by exposing the material to be joined to a vapor of hydrochloric acid. Hydrochloric acid is easily available and easy to handle and less dangerous than chlorine gas. And
The joining may be performed by heating and pressurizing the joints of the members to be joined so that the joints of the members to be joined are brought into close contact with each other. By heating, chlorine is more activated and bonding is facilitated. Further, by bringing the members to be joined into close contact with each other by applying pressure, the joining area can be increased and joining can be facilitated, and the joining strength can be increased. If one of the members to be joined to each other is made of gold and the other is made of copper,
For example, gold wires can be directly connected to copper pads and copper wiring of a semiconductor chip, eliminating the need for forming aluminum electrode pads on copper wiring, which was conventionally required, resulting in a large cost for semiconductor devices such as semiconductor chips. Can be reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the solid joining method according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of a solid joining method according to an embodiment of the present invention. In FIG. 1, a chlorination unit 1
0 is provided with a transport device 12 such as a conveyor. The transfer device 12 is a member to be joined 14 such as a semiconductor chip having copper wiring, a mounting board, a copper plate, a tin plate, a gold or silver plate,
Is carried into the chlorination unit 10 as indicated by an arrow 16, and the workpiece 14 after the chlorination treatment is carried out from the chlorination unit 10.

Above the transfer device 12, a hydrochloric acid vapor blowing section 18 is provided. This hydrochloric acid vapor blowing section 18
The hydrochloric acid vapor 22 supplied from the hydrochloric acid vapor supply unit 20 is connected to the hydrochloric acid vapor supply unit 20 via a pipe, and is sprayed on the member 14 to pass below. Further, the periphery of the hydrochloric acid vapor spraying section 18 and the transporting device 12 below this section,
While enclosed by a not-shown enclosure,
A pipe for connecting excess hydrochloric acid vapor 22 inside to the abatement apparatus is connected.

The member 14 is exposed to hydrochloric acid vapor 22 when passing below the hydrochloric acid vapor blowing section 18 to chlorinate its surface. The chlorination time depends on the concentration of hydrochloric acid in the hydrochloric acid vapor supply section 20, but it is sufficient if the chlorination treatment is performed at room temperature for several seconds or more. Further, when the chlorination treatment is performed by heating the member to be joined 14, the treatment time can be shortened.

The chlorinated workpiece 14 is carried into the bonding section 30. The joining processing unit 30 includes the base 3
A chamber 34 is provided on the top 2. A joining table 36 is provided on the base 32 in the chamber 34. On the joining table 36, the members to be joined 14A and 14B which have been subjected to the chlorination treatment are arranged in an overlapping manner. The joining table has a built-in heater 38 so that the member to be joined 14 disposed on the upper surface can be heated to a predetermined temperature. Above the joining table 36, a joining cylinder 40 attached to the chamber 34 is provided. The joining cylinder 40 has a pressure plate 44 attached to the tip of a rod 42. The pressure plate 44 has a built-in heater 46 so that the member 14B can be heated to a predetermined temperature when the member 14B is pressed.

Further, the chamber 34 is connected to a nitrogen gas supply unit 48, and by introducing nitrogen gas from the nitrogen gas supply unit 48, the inside can be made to have a nitrogen gas atmosphere. Thereby, the member to be joined 14 (14
A, 14B) is a material that is easily oxidized,
To prevent oxidation when the member to be joined 14 is heated,
Solid joining is ensured.

At least one of the joining surfaces of the members 14A and 14B arranged on the joining table 36 has been chlorinated. Also, the members to be joined 14A, 1
4B is heated by heaters 38 and 46 incorporated in the joining table 36 and the pressure plate 44 so that the joining portion (joining surface) has a predetermined temperature. The heating temperature is lower than the lower one of the melting points of the members 14A and 14B. Then, the members to be joined 14A and 14B are pressurized by the joining cylinder 40 in a heated state, and the joining surfaces are brought into close contact with each other. The pressurizing pressure is applied to the member 14 to be joined.
Are pressures that do not cause deformation by pressure. The joining time (pressing time) varies depending on the material of the member to be joined 14 and the degree of the chlorination treatment, but is about several tens seconds to several minutes.

After the members 14A and 14B made of metal are chlorinated in this manner, the members 14A and 14B
Can be easily joined in a solid state by applying pressure while heating. That is,
By heating the chlorinated workpiece 14,
The chlorine existing on the surface of the member 14 to be joined becomes more active, and the time for solid joining can be reduced.
A good bonding state can be obtained and bonding strength can be increased. In addition, since the bonding is performed under pressure, the contact area of the bonding surface increases, so that the bonding can be performed more easily, and the bonding strength increases.

The members 14A and 14B may be made of the same metal such as copper and copper, silver and silver, or the like.
Different metals such as copper and gold, copper and silver, copper and tin, tin and silver, gold and silver, and the like may be used. When chlorinating one of the two members to be joined, it is desirable to chlorinate the metal having the smaller work function. For example, when joining copper and gold, when chlorinating either one, it is better to chlorinate copper. In the above embodiment, the case where the chlorination treatment is performed using hydrochloric acid vapor is described, but the chlorination treatment may be performed using chlorine gas. Further, in the above-described embodiment, the case where the chlorination treatment is performed while the member to be bonded 14 is transported by the return device 12 has been described. And a plurality of members to be joined may be chlorinated simultaneously by introducing hydrochloric acid vapor.

FIG. 2 is a diagram schematically showing a cross section of a part of a semiconductor device manufactured by applying the solid bonding method according to the present invention. In FIG. 2, a semiconductor chip 50 as a semiconductor device has a so-called multilayer wiring structure. The semiconductor chip 50 includes a transistor 54 and a resistor (not shown) on a silicon substrate 52 made of single crystal silicon.
Elements such as capacitors are formed. The illustrated transistor 54 has a gate electrode 58 above a silicon substrate 52 via a gate oxide film 56 made of a silicon oxide film.
And a MOS transistor in which a source 60 and a drain 62 are provided on both sides of the gate electrode 58. The transistor 54 is isolated from other transistors and the like by an element isolation region 64 formed of a silicon oxide film formed around the transistor 54, and the upper part is covered with a first interlayer insulating film 66.

On the first interlayer insulating film 66, a first wiring layer 70 including a plurality of metal wirings 68 (68A, 68B,...) Is formed. Elements such as the transistor 54 formed below the first interlayer insulating film 66 are electrically connected to each metal wiring 68 of the first wiring layer 70. That is, contact holes 72 penetrating the first interlayer insulating film 66 are formed in the first interlayer insulating film 66 at positions corresponding to the gate electrode 58, the source 60, the drain 62 of the transistor 54, and other elements (not shown). (Only the contact hole 72 corresponding to the source 62 is shown in FIG. 2), and the element under the first interlayer insulating film 66 is connected to the element via the connection wiring 74 provided in the contact hole 72. The metal wiring 68 of the first wiring layer 70 is electrically connected.

The first wiring layer 70 is covered with a second interlayer insulating film 76. Further, a contact hole 78 is formed through the second interlayer insulating film 76. The connection hole 80 is provided inside the contact hole 78. The connection wiring 80 is formed by replacing each metal wiring 68 of the first insulating layer 70 and an element (not shown) formed in the second interlayer insulating film 76 with a second wiring formed on the second interlayer insulating film 76. The metal wiring 84 (84A, 84B,
……).

The second wiring layer 82 is covered with a third interlayer insulating film 86. On this third interlayer insulating film 86, a third wiring layer 88 is formed. This third wiring layer 8
8 are formed (90A, 90B,...).
)), An electrode pad 92 serving as an external electrode is provided at an appropriate position.
Is provided. The element provided in the third interlayer insulating film 86 is connected to the metal wiring 90 of the third wiring layer 88 via a connection wiring 96 disposed in a contact hole 94 formed through the third interlayer insulating film 86. Metal wiring 84 of second wiring layer 82
And are connected. The third wiring layer 88 is covered with a passivation film 98 made of an insulator for protecting the surface of the semiconductor chip 50. A connection hole 100 is formed in the passivation film 98 at a position corresponding to the electrode pad 92, and one end of the gold wire 102 is connected to the electrode pad 92 via the connection hole 100. The other end of the gold wire 102 is connected to a conductive portion of a mounting board (not shown).

Each of the wiring layers 70 and 8 of the semiconductor chip 50
2, 88, the connection wires 74, 80, 96 and the electrode pads 92 are made of copper in this embodiment. Then, the metal wiring 6 of each wiring layer 70, 82, 88
8, 84, 90, electrode pad 92 and connection wiring 74, 8
Nos. 0 and 96 form contact holes and wiring grooves for each layer, deposit copper by electroless plating or the like in these contact holes and wiring grooves, and simultaneously form connection wiring, metal wiring, and electrode pads. Formed by a dual damascene method.

The gold wire 102 is connected to the electrode pad 92 and the conductive portion of the mounting board by the solid bonding method of the present invention. That is, the connection of the gold wire 102 to the electrode pad 92 is performed as follows.

First, as shown in FIG. 3A, a photoresist is applied so as to cover the entire upper surface of the passivation film 98 of the semiconductor chip 50, and a hole 104 is formed at a position corresponding to the electrode pad 92 by a photolithography method. The provided resist film 106 is formed. After that, the resist film 1
The passivation film 98 is etched using the mask 06 as a mask, and a connection hole 100 is formed in the passivation film 98 above the electrode pad 92 as shown in FIG.
After exposing a part of the electrode pad 92, the photoresist film 106 is removed.

Next, the semiconductor chip 50 provided with the connection holes 100 is exposed to hydrochloric acid vapor as described above, and the electrode pads 9 are formed.
The exposed part 2 is chlorinated. This chlorination treatment is performed, for example, by converting semiconductor chip 50 into vapor generated from 37% by mass of hydrochloric acid.
For 5 to 10 seconds. Thereafter, the chlorinated semiconductor chip 50 is carried into a bonding step (not shown). Further, as shown in FIG.
02 of the bonding apparatus holding 02
8 is inserted into a connection hole 100 formed in the passivation film 98. Then, the gold wire 102 is pressed against the upper surface of the electrode pad 92 by the capillary 108,
The gold wire 102 is solid-bonded to the electrode pad 92 made of copper.

When bonding the gold wire 102 and the electrode pad 92 at room temperature, the gold wire 102 is preferably pressed against the electrode pad 92 and ultrasonic vibration is applied. By applying the ultrasonic vibration, the contact portion between the gold wire 102 and the electrode pad 92 generates heat, and the bonding can be performed easily and reliably. When the bonding is performed by heating the semiconductor chip 50, the bonding is performed in an atmosphere in which the electrode pad 92 made of copper is not oxidized, such as a nitrogen atmosphere or a vacuum state. Of course, even in the case where the bonding is performed without heating, it is preferable to perform the bonding in an atmosphere where copper is not oxidized.

[0027]

EXAMPLES Example 1 Solid bonding experiments were carried out by chlorinating various metals, and the strength of the solid bonding was determined as the shear strength. For comparison, solid bonding experiments were performed when no treatment was performed, when flux was applied, and when fluorination was performed.

The samples used were pellets of gold, tin, and copper, and substrates of gold, silver, copper, and aluminum, and solid bonding was performed between these pellets and the substrate. However,
The gold pellet used was a copper pellet having a diameter of 2 mm and a thickness of 2 mm, which was plated with nickel and then plated with gold to a thickness of 3.2 μm. And the tin pellet has a diameter of 2
mm, pure tin and copper pellets with a thickness of 1 mm have a diameter of 2 m
m, pure copper having a thickness of 2 mm was used. The gold substrate used was a copper plate having a length and width of 10 mm and a thickness of 0.5 mm, plated with nickel, and then plated with gold to a thickness of 3.2 μm. A silver substrate is a pure silver plate having a length and width of 10 mm and a thickness of 0.5 mm. A copper substrate has a length and width of 10 mm.
mm, a pure copper plate having a thickness of 0.5 mm, and an aluminum substrate having a length and width of 10 mm and a thickness of 1.0 mm were used.

The fluorination treatment was performed by a method as shown in FIG. That is, the volume is 1000 mL
A 50% by mass hydrofluoric acid (HF) solution 112 is placed inside a fluororesin-based container 110. Thereafter, the surface treatment container 114 containing the sample (pellet and substrate) is placed on the support base 1.
16, the support base 116 is suspended in the fluororesin container 110 by the suspender 118, and the surface treatment container 11 is
4 is kept out of contact with hydrofluoric acid 112.
Further, the upper opening 120 of the fluororesin container 110 was covered with an aluminum foil 122 and exposed to hydrofluoric acid vapor (HF vapor) 124 at room temperature for 10 seconds. The surface treatment container 114 was formed in a box shape as shown in FIG. 4 (2) using aluminum foil, and the samples 126 were arranged at the bottom so that the samples 126 did not overlap.

The chlorination treatment was performed using hydrochloric acid in the same manner as shown in FIG. However, the hydrochloric acid used was 35% by mass, and the amount of hydrochloric acid put in the fluororesin container 110 was 100 mL. In addition, the processing time (sample 126
Is exposed to hydrochloric acid vapor) for 30 seconds.

The bonding process was performed as shown in FIG. 5 when a gold pellet or a copper pellet was bonded to a substrate. An intermediate stage 132 was disposed on a stage 130 having a built-in heater to prevent thermal oxidation of the substrate, and a substrate 134 was set on the intermediate stage 132. The upper jig 136 attached to a pressure cylinder (not shown)
Has a built-in heater and has a length of 5 mm and a width of 5 m on the lower surface.
m, a copper plate 138 having a thickness of 1 mm is mounted.
Is lowered integrally with the upper jig 136 as shown by an arrow 140,
The substrate 134 and the pellet 142 were indirectly thermocompression-bonded with the copper plate 138. In addition, the nozzle 144
Nitrogen gas 146 is blown at 1 L / min to prevent thermal oxidation of the sample.

When the pellet 142 is a gold pellet or a copper pellet, the upper and lower heaters (not shown) were set at 300 ° C. The maximum temperature of the bonding surface at this time was 247.6 ° C. And at the time of joining,
Apply a pressure (joining pressure) of about 31.3 N / mm ² to the upper jig 1
36, the pellet 142 and the substrate 134 are brought into close contact. The bonding time (pressing time) is 60 seconds.

When bonding the tin pellet to the substrate, the substrate 1
34 was set directly on the stage 130. Also,
The set temperatures of the upper and lower heaters are set to 20 so that the tin does not melt.
It was brought to 0 ° C. At this time, the maximum temperature of the bonding surface is 185.9.
° C. And the joining pressure is about 6.28 N / mm
² , and the bonding time is 60 seconds.

In the flux treatment, as shown in FIG. 6, the flux 148 is directly applied to the surface of the substrate 134, and the pellet 142 is disposed thereon. The used flux is Superflux SR-104 manufactured by Senju Metal Co., Ltd. And flux 148
At the time of coating, a mixed gas 152 of nitrogen gas and air is blown from the nozzle 150 to the coating section.

The measurement of the shear strength as the joining strength was performed as shown in FIG. That is, an Instron type tensile tester was used as a shear tester, and the substrate 13 on which the pellet 142 was bonded was placed on the table 154.
4 is arranged, and the substrate 134 is fixed to the table 154 by the fixture 156. Thereafter, the pressing tool 158 of the testing machine is moved in parallel with the surface of the substrate 134 as indicated by an arrow 160, and a horizontal force is applied to the pellet 142 to cause the pellet 14 to move.
2 was peeled off from the substrate 134. Note that the distance between the lower end of the pressing tool 158 and the upper surface of the substrate 134 is 0.1 mm.
5 mm, the moving speed of the pressing tool 158 is 0.5 mm / min
It is.

8 to 17 show the results of the measured bonding strength (shear strength). FIG. 8 shows the measurement results of the shear strength per 1 mm ^{2 of} each sample after the gold (Au) pellet and the gold (Au) substrate were solid-bonded. For untreated, flux is applied to both the pellet and the substrate, fluorination treatment with HF vapor, H
It is the result of having measured the shear strength when the solid joining was performed in a state where the chlorination treatment with Cl vapor was not performed.

In the case of a gold pellet and a gold substrate, solid bonding to some extent is possible even if it is untreated. In the case of fluorination treatment using HF vapor, the average value of the shear strength is large, but the dispersion is large and the bonding is unstable. On the other hand, when chlorination treatment with HCl vapor is performed, the shear strength is increased and the variation in the shear strength is relatively small. Therefore, the chlorination treatment with HCl vapor can provide better solid bonding as a whole than the fluorination treatment with HF vapor. However, in the case of treatment with HF vapor or treatment with HCl vapor, both the pellet and the substrate are treated. The same applies to the following cases.

FIG. 9 shows the measurement results of the shear strength per 1 mm ^{2 of} each sample when the gold pellet and the silver (Ag) substrate were solid-bonded. In this combination, solid bonding can be performed favorably even in the case of no treatment, as in the case of HF treatment and HCl treatment. This is considered to be due to the formation of the Au-Ag alloy. Also in this case, the variation in the treatment with HCl vapor is smaller than that in the treatment with HF vapor.

FIG. 10 shows the measurement results of the shear strength per 1 mm ^{2 of} each sample when the gold pellet and the copper (Cu) substrate were solid-bonded. Untreated, the combination of the gold pellet and the copper substrate could not be solid-bonded. Further, when the fluorination treatment with HF vapor was performed, the dispersion was large, the solid bonding was unstable, and the shear strength was inferior to that of the chlorination treatment with HCl vapor.

FIG. 11 shows the measurement results of the shear strength per 1 mm ^{2 of} each sample after the tin (Sn) pellets and the gold substrate were solid-bonded. In this combination, when untreated, when using flux, HF
There is no significant difference between the treatment with steam and the treatment with HCl vapor. However, the treatment with HF vapor resulted in slightly lower shear strength than in the other cases.

FIG. 12 shows the measurement results of the shear strength per 1 mm ^{2 of} each sample after solid bonding of the tin pellet and the silver substrate. In this combination, solid bonding could not be performed when untreated. In addition, there was almost no difference between the case of using the flux, the case of the fluorination treatment with the HF vapor, and the case of the chlorination treatment with the HCl vapor.

FIG. 13 shows the measurement results of the shear strength per 1 mm ^{2 of} each sample after solid bonding of the tin pellet and the copper substrate. Even in this case, when untreated, bonding could not be performed. In addition, there was almost no difference between the case using the flux, the case using the HF vapor, and the case using the HCl vapor. However, the combination of the tin pellet and the copper substrate is H
When the treatment with the F vapor and the HCl vapor is performed, the shear strength is slightly inferior to the case of the combination of the tin pellet and the silver substrate.

FIG. 14 shows the measurement results of the shear strength per 1 mm ^{2 of} each sample when the copper (Cu) pellet and the gold substrate were solid-bonded. In this combination, if untreated, bonding cannot be performed. Further, when other fluxes are used, treatment with HF vapor, and treatment with HCl vapor, the average value of the shear strength does not cause a large difference between them.

FIG. 15 shows a solid contact between a copper pellet and a silver substrate.
1mm of each sample when combined ^Two Shear strength per hit
5 shows the measurement results. In this combination
Can not be solid bonded if untreated
Was. When the treatment with HF vapor is performed,
If flux is used, or if HCl vapor is used
It is lower than in the case of
Good.

FIG. 16 shows the measurement results of the shear strength per 1 mm ^{2 of} each sample when the copper pellet and the copper substrate were solid-bonded. In this combination,
In the case of no treatment and the case of fluorination treatment with HF vapor, solid joining could not be performed. When chlorination with HCl vapor was performed, solid bonding could be performed, but the average value of the shear strength was lower and the variation was larger than when flux was used.

The solid bonding between the aluminum substrate and the gold pellet, tin pellet or copper pellet is performed not only when untreated but also when a flux is used.
No joining could be made in any of the steam treatments.

FIG. 17 shows the average values of the shear strengths shown in FIGS. 8 to 16. The crosses in FIG. 17 indicate that solid joining could not be performed. The symbol △ indicates that the average shear strength is 9.807 N /
mm ² (1 kgf / mm ² ) or less, and the symbol “○” indicates that the average shear strength is 9.807 to 29.420 N.
/ Mm ² (1-3 kgf / mm ² ),
The symbol ◎ indicates that the average shear strength is 29.420 N / mm ^2.
(3 kgf / mm ² ) or more, and the symbol ● indicates that the material was broken during the measurement of the shear strength.

As described above, when the chlorination treatment using HCl vapor is performed, the shear strength is increased and the variation in the shear strength is small as compared with the case where the fluorination treatment is performed using HF vapor. Therefore, a metal that has been chlorinated with HCl vapor can perform more stable and good solid bonding than a fluorination treatment with HF vapor.

Example 2 Using a gold pellet and a copper substrate, the relationship between the time of chlorination treatment with HCl vapor and the shear strength after solid joining was examined. Gold pellets have a diameter of 2
After plating a nickel pellet on a copper pellet having a thickness of 2 mm and a thickness of 2 mm, a gold plate plated with a thickness of 3.2 μm is used. The copper substrate is a pure copper plate having a length and width of 10 mm and a thickness of 0.5 mm. Was. For comparison, the relationship between the time of fluorination treatment with HF vapor and the shear strength after solid bonding was examined using the same gold pellets and copper substrate as described above.

The chlorination treatment, fluorination treatment, solid joining method and measurement of the shear strength are the same as those in Example 1 except for the chlorination treatment and the fluorination treatment time. Also,
In order to know the chlorination time and the degree of chlorination, and the fluorination time and the degree of fluorination, during the chlorination and fluorination of the sample, the copper pellet and the solder plating plate were simultaneously chlorinated. A fluorination treatment and a fluorination treatment were performed, and these were pressed against a pH test paper wetted with pure water to measure the pH value.

The copper pellet for measuring pH has a diameter of 2 m.
m, 2mm thick pure copper pellets, solder plated plate
A pure copper plate having a length and a width of 5 mm plated with a solder (82 solder) of 80% tin and 20% lead was used.

FIG. 18 is a graph showing the relationship between HCl in a gold pellet and a copper substrate.
It shows the relationship between the time of chlorination treatment by steam and the shear strength per unit area when the chlorination treatment is solid-bonded. The symbol “実” indicates the measured value of each sample, and the symbol “値” indicates the average value thereof. From this figure, it can be seen that when solid bonding the gold pellet and the copper substrate, the chlorination treatment with HCl vapor should be performed for about 5 seconds or more.

FIG. 19 is a graph showing the relationship between the chlorination time and the degree of chlorination using HCl vapor. The amount of chlorine (Cl) present on the surfaces of the copper pellet and the solder plating plate was measured as a pH value. These pH values are obtained by averaging three samples.

From this figure, it can be seen that the copper pellet is less likely to be chlorinated as compared with the solder plating plate. In addition, it can be seen that all of them can be sufficiently chlorinated by exposing them to HCl vapor for about 5 seconds or more. In addition, there was almost no difference in the pH value among the three samples for which the average value was obtained. Therefore, chlorination with HCl vapor can be performed very stably.

FIG. 20 shows the relationship between the fluorination time of the gold pellets and the copper substrate with HF vapor and the shear strength per unit area when they are solid-bonded. The symbol “実” indicates the measured value of each sample, and the symbol “値” indicates the average value thereof. In the case of fluorination with HF vapor, if the treatment time is 20 seconds or less, a shear strength that is not so different from that of chlorination treatment with HCl vapor can be obtained. However, when the solid bonding is performed by the fluorination treatment using the HF vapor, the variation is large compared to the case of the chlorination treatment using the HCl vapor, and the bonding state is unstable. Also,
If the fluorination treatment time exceeds 20 seconds, the bonding strength will decrease. Therefore, the chlorination treatment by HCl vapor is HF treatment.
Solid bonding is easier than in the case of fluorination treatment with steam.
It can be performed stably.

FIG. 21 is a graph showing the relationship between the time of fluorination treatment with HF vapor and the degree of fluorination. The amount of fluorine (F) present on the surfaces of the copper pellet and the solder plating plate was measured as a pH value. These pH values are obtained by averaging three samples.

FIG. 21 shows that the copper pellet is less fluorinated than the solder plating plate. Further, it can be seen that the copper pellet is not sufficiently fluorinated even when exposed to HF vapor for about 10 seconds. On the other hand, when the solder plating plate is exposed to HF vapor for about 10 seconds, fluorination is almost completed. Note that fluorination with HF vapor caused variations in the degree of fluorination. In particular, in the case of copper pellets, the pH values differed by about 2 between the three samples. Therefore, fluorination with HF vapor is more difficult to control than chlorination with HCl vapor, and solid bonding is also unstable.

[0058]

As described above, according to the present invention, a member to be joined made of a metal is subjected to chlorination treatment, and chlorine which easily bonds to the metal is present on the surface of the member to be joined, whereby chlorine is removed. Since the metal bond is diffused inside the member to be joined and cut, and the cut joint is joined to the other member to be joined, the two members to be joined made of metal are used in a solid state without using a brazing material. Can be joined together. In addition, since chlorine is not as reactive as fluorine, the degree of chlorination can be easily controlled, and variations in the bonding state (bonding strength) can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a solid joining method according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a cross section of a part of a semiconductor device to which the solid bonding method of the present invention is applied.

FIG. 3 is a main part process view of the method for manufacturing the semiconductor device shown in FIG. 2;

FIG. 4 is an explanatory view of a fluorination treatment method and a surface treatment container of an example.

FIG. 5 is an explanatory diagram of a joining processing method according to the embodiment.

FIG. 6 is a diagram illustrating a method of applying a flux according to an example.

FIG. 7 is an explanatory diagram of a method for measuring shear strength according to an example.

FIG. 8 shows the unit area after solid bonding of a gold pellet and a gold substrate in the case of untreated, in the case of using flux, in the case of fluorination by HF vapor, and in the case of chlorination by HCl vapor. It is a figure which shows the shear strength of.

FIG. 9 shows a unit area after solid bonding between a gold pellet and a silver substrate, when untreated, when using a flux, when fluorinated by HF vapor, and when chlorinated by HCl vapor. It is a figure which shows the shear strength of.

FIG. 10 shows a unit area after solid bonding between a gold pellet and a copper substrate, when untreated, when using a flux, when fluorinated by HF vapor, and when chlorinated by HCl vapor. It is a figure which shows the shear strength of.

FIG. 11 shows a unit area after solid bonding of a tin pellet and a gold substrate in a case where they are untreated, when a flux is used, when a fluorination treatment is performed with HF vapor, and when a chlorination treatment is performed with HCl vapor. It is a figure which shows the shear strength of.

FIG. 12 shows a unit area after solid joining of a tin pellet and a silver substrate after solid bonding in the case of untreated, in the case of using flux, in the case of fluorination by HF vapor, and in the case of chlorination by HCl vapor. It is a figure which shows the shear strength of.

FIG. 13 shows a unit area after solid bonding in the case where a tin pellet and a copper substrate are untreated, when a flux is used, when a fluorination treatment is performed with HF vapor, and when a chlorination treatment is performed with HCl vapor. It is a figure which shows the shear strength of.

FIG. 14 shows a unit area after solid bonding of a copper pellet and a gold substrate after solid bonding in the case of untreated, in the case of using flux, in the case of fluorination by HF vapor, and in the case of chlorination by HCl vapor. It is a figure which shows the shear strength of.

FIG. 15 shows a unit area after solid bonding of a copper pellet and a silver substrate in the case of untreated, in the case of using flux, in the case of fluorination by HF vapor, and in the case of chlorination by HCl vapor. It is a figure which shows the shear strength of.

FIG. 16 shows a unit area after solid bonding of a copper pellet and a copper substrate in an untreated state, in a case of using a flux, in a case of performing a fluorination treatment with HF vapor, and in a case of performing a chlorination treatment with HCl vapor. It is a figure which shows the shear strength of.

FIG. 17 is a diagram showing an average value of shear strength per unit area shown in FIGS. 8 to 16;

FIG. 18 is a diagram showing a relationship between chlorination time and shear strength per unit area when a gold pellet and a copper substrate are chlorinated with HCl vapor and solid-bonded.

FIG. 19 shows the chlorination time and p when the copper pellet and the solder plating plate are chlorinated with HCl vapor.
It is a figure showing the relation with H value.

FIG. 20 is a view showing the relationship between the fluorination time and the shear strength per unit area when the gold pellet and the copper substrate are fluorinated by HF vapor and solid-bonded.

FIG. 21 is a diagram showing the relationship between the time of fluorination treatment and the pH value when fluorination treatment is performed on a copper pellet and a solder plating plate with HF vapor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Chlorination processing part 14 Member to be joined 18 Hydrochloric acid vapor blowing part 20 Hydrochloric acid vapor supply part 22 Hydrochloric acid vapor 30 Bonding processing part 34 Chamber 36 Joining table 38, 40 Heater 40 Joining cylinder 44 Pressure plate 48 Nitrogen gas supply part 50 Semiconductor chip 52 Silicon substrate 54 Transistor 66 First interlayer insulating film 70 First wiring layer 76 Second interlayer insulating film 82 Second wiring layer 86 Third interlayer insulating film 88 Third wiring layer 92 Electrode pad 98 Passivation film 102 Gold wire

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E067 AA07 AA08 BB02 CA02 DA03 DB03 DC01 DC04 DC11 EA05 EB00 5F044 EE04 KK01 KK11 LL00 QQ06

Claims (4)

[Claims] 1. A solid joining method comprising: chlorinating at least one of members to be joined made of the same or different metals to be joined to each other; 2. The solid joining method according to claim 1, wherein the chlorination treatment is performed by exposing the member to be joined to hydrochloric acid vapor. 3. The solid joining method according to claim 1, wherein the joining is performed by heating and pressurizing the joints of the members to be joined to each other so as to bring the joints of the members to be joined into close contact with each other. . 4. The solid joining method according to claim 1, wherein the members to be joined to each other are gold and copper.