JPH09102514A - Bump bonding method and structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce temperature and load applied to a connection body by reducing joint work man-hour and not depositing flux on the surface of the connection body. SOLUTION: A metal film 31 with wetting property and corrosion resistance is formed for AuSn by making connection to an electrode terminal 4 of multilayer ceramic substrate 2, Sn film 32 is formed on the metal film 31, and Au bump 33 is formed at the electrode terminal 12 of a semiconductor element 5. Then, the electrode terminal 4 and the electrode terminal 12 are aligned, the Au bump 33 and the Sn film 32 are adhered before being heated to approximately 280 deg.C in a reduced atmosphere or a non-active atmosphere, thus causing AuSn eutectic reaction between the Au bump 33 and the Sn film 32, forming AuSn eutectic layer 34 between the Au bump 33 and the metal film 31, and electrically and mechanically joining the electrode terminal 4 and the electrode terminal 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bump bonding for directly connecting a first connecting portion of a connecting body such as a semiconductor element or a circuit device to a second connecting portion of a connected body such as a wiring board via a bump. A method and bump bonding structure.

[0002]

2. Description of the Related Art FIG. 4 is a schematic sectional view showing an apparatus having a conventional bump bonding structure. As shown in the figure,
Multilayer ceramic substrate 2 via bump 3 on circuit wiring board 1
, The semiconductor element 5 is connected to the electrode terminal 4 of the multilayer ceramic substrate 2 via the solder bump 6, the seal cap 7 is fixed to the multilayer ceramic substrate 2 by the cap sealing portion 8, and the semiconductor element is connected by the seal cap 7. 5 is sealed.

FIG. 5 is an explanatory view of a conventional bump bonding method and structure. In this method and structure, an insulating film 9 for preventing a short circuit at the time of solder reflow is formed on the multilayer ceramic substrate 2 and is connected to the electrode terminal 4 to have Ni, Pd, Pt having solder wettability and solder corrosion resistance. ,
A metal film 10 made of Cu or the like is formed, and an Au film 11 for preventing oxidation of the metal film 10 is formed on the metal film 10. On the other hand, an insulating film 13 for preventing a short circuit during solder reflow is formed on the semiconductor element 5, and a metal film 14 having solder wettability and solder corrosion resistance is formed by connecting to an electrode terminal 12 of the semiconductor element 5. The solder bumps 6 are formed on the metal film 14. Then, the electrode terminals 4 and 12 are aligned with each other, the solder bumps 6 and the Au film 11 are brought into close contact with each other, flux is applied or dropped, and solder reflow is performed to join them. In this case, the Au film 11 diffuses and disappears in the solder at the same time as the solder reflow, and the solder bump 6 is directly bonded to the metal film 10.

FIG. 6 is an explanatory view of another conventional bump bonding method and structure. In this method and structure,
The Ni film 17 and the solder layer 18 are formed on the surface of the Cu ball 16.
The Cu ball bump 15 on which is formed is attached to the electrode terminal 12, the electrode terminal 4 and the electrode terminal 12 are aligned, and the Cu ball bump 15 and the Au film 11 are brought into close contact with each other.
Flux is applied or dropped, and solder reflow is performed for joining. In this case, the Cu ball 16 acts as a standoff for maintaining the distance between the multilayer ceramic substrate 2 and the semiconductor element 5.

FIG. 7 is an explanatory view of another conventional bump bonding method and structure. In this method and structure,
An Au bump 25 is formed on the terminal connection lead 24 of the film carrier 23 in which a wiring pattern made of Cu is formed on a flexible insulating film, and the Au bump 25 and the electrode terminal 22 of the semiconductor element 21 are aligned with each other. Then, thermocompression bonding is performed by the bonding tool 26.

FIG. 8 is an explanatory view of another conventional bump bonding method and structure. In this method and structure,
Au bumps 27 are formed on the electrode terminals 22 of the semiconductor element 21, the Au bumps 27 are aligned with the terminal connection leads 24, and thermocompression bonding is performed by a bonding tool 26.

As a method of forming the Au bumps 25 and 27, a lift-off method is used in which bumps are directly formed at predetermined positions by a plating technique, or Au balls formed by plating or the like on a glass substrate are formed at predetermined positions by thermocompression bonding or the like. There are various methods such as a transfer bump method for transferring to a bump to form a bump, and a method for forming a bump by bonding an Au ball formed by melting the tip of an Au wire to a predetermined position by thermocompression bonding, thermosonic waves or the like. is there.

[0008]

However, in the bump bonding method and structure described with reference to FIGS. 5 and 6, it is necessary to perform the solder reflow process to form the solder bumps 6 and the Cu ball bumps 15 on the semiconductor element 5. Since it is necessary to perform the solder reflow process in order to mount the semiconductor element 5 on the multilayer ceramic substrate 2, it is necessary to perform the solder reflow process twice.
In addition, since the use of flux is indispensable in the solder reflow process, flux cleaning must be performed after each of the two solder reflow processes, resulting in a large number of joining work steps. Further, since the flux adheres to the surface of the semiconductor element 5, it is difficult to completely remove the flux from the surface of the semiconductor element 5. Especially, when the semiconductor element 5 is an optical semiconductor element, the cleaning of the flux is incomplete. If so, the optical coupling loss increases.

In the bump bonding method and structure described with reference to FIGS. 7 and 8, the temperature of the bonding tool 26 at the time of thermocompression bonding is 350 ° C. or higher, so that it is applicable when the semiconductor element 5 has low heat resistance. Cannot be done and a large weight is applied to the semiconductor element 5,
It cannot be applied when the semiconductor element 5 is made of a compound semiconductor having a low compressive fracture strength.

The present invention has been made in order to solve the above-mentioned problems, and the number of man-hours required for bonding is small, flux does not adhere to the surface of the connecting body, and the temperature and weight applied to the connecting body are low. Methods and bump bonding structures are provided.

[0011]

To achieve this object, according to the present invention, bump bonding for directly connecting a first connecting portion of a connecting body and a second connecting portion of a connected body via bumps. In the method, an Au bump is formed on one of the first and second connection portions, and an Sn film is formed on the other of the first and second connection portions, and the Au bump and the Sn film are formed. Heat closely.

Further, in the bump bonding method for directly connecting the first connecting portion of the connecting body and the second connecting portion of the connected body through bumps, either one of the first and second connecting portions is provided. Au bumps are formed on the above, a Sn film is formed on the other of the first and second connection portions, an Au film is formed on the Sn film, and the Au bumps and the Au film are closely contacted and heated. .

In the bump bonding structure in which the first connecting portion of the connecting body and the second connecting portion of the connected body are directly connected via the bump, either one of the first and second connecting portions is provided. Au bumps are formed on the substrate, and the Au bumps and the other of the first and second connecting portions are connected via an AuSn eutectic layer.

[0014]

1 is an explanatory view of a bump bonding method and structure according to the present invention. In this method and structure, as shown in FIG. 1A, Ni which is connected to the electrode terminal 4 and has wettability and corrosion resistance to AuSn,
A metal film 31 made of Pd, Pt, Cu or the like is formed, and an Sn film 32 is formed on the metal film 31. On the other hand, the semiconductor element 5
Au bumps 33 are formed on the electrode terminals 12 by the above-described lift-off method, transfer bump method, or the like. Then, the electrode terminals 4 and 12 are aligned with each other, the Au bumps 33 and the Sn film 32 are brought into close contact with each other, and heated to a temperature exceeding 280 ° C. Then, an AuSn eutectic reaction occurs between the Au bump 33 and the Sn film 32, and an AuSn eutectic layer 34 is formed between the Au bump 33 and the metal film 31, as shown in FIG. 1B. The electrode terminal 4 and the electrode terminal 12 are electrically and mechanically joined.

In this bump bonding method and structure, since it is not necessary to perform the flux applying step and the flux cleaning step, the number of man-hours required for joining is small, and the semiconductor element 5 does not adhere to the flux. Even in the case of a semiconductor device, the optical coupling loss does not increase. Further, the temperature of the AuSn eutectic layer is about 280 ° C., which is considerably lower than the temperature of the semiconductor element 5 at the time of thermocompression bonding in the bump bonding method and structure described with reference to FIGS. It can also be applied when the is low. In addition, since a small weight for adhering the Au bump 33 and the Sn film 32 to the semiconductor element 5 may be applied to the semiconductor element 5 at the time of bonding, a large weight is not applied to the semiconductor element 5, so that the semiconductor element 5 has a compressive fracture strength. It can also be applied to the case of a compound semiconductor having a low In addition, since the plurality of electrode terminals 4 and 12 can be joined together, the joining work efficiency is good.

In this embodiment, the bonding work was performed in air. However, if the bonding film is heated in a reducing atmosphere or an inert atmosphere at the time of bonding, the Sn film 32 and AuSn are formed.
Oxidation of the AuSn eutectic layer 34 after the eutectic reaction can be prevented, so that a better bonded state can be obtained than when working in air. Further, in this embodiment, the metal film 31 and the Sn film 32 are formed on the electrode terminals 4 of the multilayer ceramic substrate 2, and the Au bumps 33 are formed on the electrode terminals 12 of the semiconductor element 5.
However, a Au bump may be formed on the electrode terminal 4 and a metal film or Sn film having wettability and corrosion resistance to AuSn may be formed on the electrode terminal 12.

FIG. 2 is an explanatory view of another bump bonding method and structure according to the present invention. In this method and structure, the metal film 31 is formed by connecting to the electrode terminal 4, the Sn film 32 is formed on the metal film 31, and the Au film 35 is formed on the Sn film 32. On the other hand, the Au bump 33 is formed on the electrode terminal 12 of the semiconductor element 5. Then, the electrode terminal 4 and the electrode terminal 12 are aligned and the Au bump 33 and the Au bump 33 are aligned.
It is brought into close contact with the film 35 and heated to a temperature higher than 280 ° C. Then, the Au bump 33, the Au film 35, and the Sn film 32 are formed.
And an AuSn eutectic reaction occurs between them and an AuSn eutectic layer (not shown) is formed between the Au bumps 33 and the metal film 31, and the electrode terminals 4 and 12 are electrically and mechanically To be joined.

Also in this bump bonding method and structure, the number of man-hours required for bonding is small, the flux does not adhere to the semiconductor element 5 and the heat resistance of the semiconductor element 5 is low. Can also be applied to the case where the compound semiconductor is made of a compound semiconductor having a low compressive fracture strength, and the bonding work efficiency is excellent. Further, since the Au film 35 is formed on the Sn film 32, the surface oxidation of the Sn film 32 can be suppressed while the semiconductor element 5 is stored, and the heating for bonding can be reduced. Even if it is not performed in an atmosphere or an inert atmosphere, S
Since the surface oxidation of the n film 32 can be suppressed, the bonding work can be easily performed, and a good bonding state can be obtained.

In this embodiment, the metal film 31 and the Sn film 3 are formed on the electrode terminals 4 of the multilayer ceramic substrate 2.
2, the Au film 35 is formed, and the electrode terminal 12 of the semiconductor element 5 is formed.
Although the Au bump 33 is formed on the electrode terminal 4, the Au bump may be formed on the electrode terminal 4 and the electrode terminal 12 may be formed with a metal film, Sn film, or Au film having wettability and corrosion resistance to AuSn.

FIG. 3 is an explanatory view of another bump bonding method and structure according to the present invention. In this method and structure, as shown in FIG. 3A, the Sn film 41 is formed on the terminal connection lead 24 of the film carrier 23, the Au bump 27 is formed on the electrode terminal 22 of the semiconductor element 21, and the electrode terminal is formed. 22 and the terminal connection lead 24 are aligned, the bonding tool 26 is brought into close contact with the terminal connection lead 24, and heated to a temperature higher than 280 ° C., the AuSn eutectic crystal is formed between the Au bump 27 and the Sn film 41. A reaction takes place,
As shown in FIG. 3B, the AuSn eutectic layer 42 is formed between the Au bumps 27 and the terminal connection leads 24, and the electrode terminals 22 and the terminal connection leads 24 are electrically and mechanically joined. .

In this bump bonding method and structure, the number of man-hours required for bonding is small and flux does not adhere to the semiconductor element 5. Further, the AuSn eutectic temperature is about 280 ° C., which is considerably lower than the temperature of the semiconductor element 5 at the time of thermocompression bonding in the bump bonding method and structure described with reference to FIGS. It can be applied even when it is low. In addition, at the time of bonding, a small weight may be applied to the semiconductor element 5 such that the Au bump 27 and the Sn film 41 are brought into close contact with each other.
Since a large weight is not applied to the semiconductor element 5, it can be applied to the case where the semiconductor element 5 is made of a compound semiconductor having a low compressive fracture strength. Moreover, since the plurality of electrode terminals 22 and the terminal connection leads 24 can be collectively bonded, the bonding work efficiency is good.

In this embodiment, the bonding work was performed in air. However, if the bonding film is heated in a reducing atmosphere or an inert atmosphere at the time of bonding, the Sn film 41 and AuSn are formed.
Oxidation of the AuSn eutectic layer 42 after the eutectic reaction can be prevented, so that a better bonded state can be obtained than when working in air. Further, in this embodiment, the Au bump 27 is formed on the electrode terminal 22 and the Sn film 41 is formed on the terminal connecting lead 24. However, the Sn film is formed on the electrode terminal 22 and the Au bump is formed on the terminal connecting lead 24. May be formed. In addition, in this embodiment, the Sn film 41 is only formed on the terminal connection lead 24.
If the Au film is formed on the film carrier 23, it is possible to prevent the surface of the Sn film 41 from being oxidized while the film carrier 23 is stored, and heating for bonding is performed in a reducing atmosphere or an inert atmosphere. Even if not performed, the Sn film 41
Since it is possible to suppress the surface oxidation of the, it is possible to easily carry out the joining work and to obtain a good joined state. Also, in this embodiment,
Although the plurality of electrode terminals 22 and the terminal connection leads 24 are collectively bonded by the bonding tool 26, thermosonic bonding for bonding the terminal connection leads 24 one by one by heating and applying pressure while applying ultrasonic vibration. If the terminal connection lead 24 and the electrode terminal 22 are bonded by the method, the terminal connection lead 24 can be bonded at a lower temperature without being crushed.

In the above embodiment, the first
In the above description, the connection parts are the electrode terminals 12 and 22, and the second connection parts are the electrode terminals 4 and the terminal connection leads 24. However, the present invention is also applicable to the case where the first and second connection parts are other. It is clear that can be applied.

[0024]

As described above, in the bump bonding structure and the bump bonding method according to the present invention, it is not necessary to perform the flux applying step and the flux cleaning step. Since it does not adhere and the AuSn eutectic temperature is about 280 ° C., it can be applied even when the heat resistance of the connector is low, and moreover, when bonding the Au bump and the Sn film to the connector. Since it is sufficient to apply a small weight to the connection body, it can be applied even when the compressive fracture strength of the connection body is low.

Further, an Au bump is formed on one of the first and second connecting portions, and S is formed on the other of the first and second connecting portions.
When the n film is formed, the Au film is formed on the Sn film, and the Au bump and the Au film are closely contacted with each other and heated, the Sn film is not required to be heated in a reducing atmosphere or an inert atmosphere for Sn bonding. Since the surface oxidation of the film can be suppressed, the joining work can be easily performed, and a good joining state can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a bump bonding method and structure according to the present invention.

FIG. 2 is another bump bonding method according to the present invention,
It is explanatory drawing of a structure.

FIG. 3 is another bump bonding method according to the present invention,
It is explanatory drawing of a structure.

FIG. 4 is a schematic cross-sectional view showing a device having a conventional bump bonding structure.

FIG. 5 is an explanatory diagram of a conventional bump bonding method and structure.

FIG. 6 is an explanatory diagram of another conventional bump bonding method and structure.

FIG. 7 is an explanatory diagram of another conventional bump bonding method and structure.

FIG. 8 is an explanatory diagram of another conventional bump bonding method and structure.

[Explanation of symbols]

 2 ... Multilayer ceramic substrate 4 ... Electrode terminal 5 ... Semiconductor element 12 ... Electrode terminal 21 ... Semiconductor element 22 ... Electrode terminal 23 ... Film carrier 24 ... Terminal connection lead 27 ... Au bump 32 ... Sn film 33 ... Au bump 34 ... AuSn Crystal layer 35 ... Au film 41 ... Sn film 42 ... AuSn eutectic layer

Claims (3)

[Claims] 1. A bump bonding method for directly connecting a first connecting portion of a connecting body and a second connecting portion of a connected body via bumps, wherein either one of the first and second connecting portions is provided. A bump bonding method comprising: forming an Au bump on the substrate, forming an Sn film on the other of the first and second connecting portions, and closely heating the Au bump and the Sn film. 2. A bump bonding method for directly connecting a first connecting portion of a connecting body and a second connecting portion of a connected body via bumps, wherein either one of the first and second connecting portions is provided. Au bumps are formed on the above, a Sn film is formed on the other of the first and second connection portions, an Au film is formed on the Sn film, and the Au bumps and the Au film are closely contacted and heated. A bump bonding method characterized by the above. 3. A bump bonding structure for directly connecting a first connecting portion of a connecting body and a second connecting portion of a connected body via bumps, wherein either one of the first and second connecting portions is provided. A bump bonding structure in which an Au bump is formed on the substrate and the Au bump is connected to the other of the first and second connecting portions via an AuSn eutectic layer.