Connection structure and method for fabricating the same

Abstract

There is provided a connection structure between a Si electrode (Si member) and an Al wire (Al member). Between the Si electrode and the Al wire, a first part and second parts are present in interposed relation. Each of the first and second parts is in contact with the Si electrode and with the Al wire. In the first part, a Si oxide layer and an Al oxide layer are present. The Si oxide layer is in contact with the Si electrode. The Al oxide layer is interposed between the Si oxide layer and the Al wire. In some of the second parts, Al is present. In the others of the second parts, a Si portion and an Al portion are present.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing a connection structure 1;

FIG. 2 is an enlarged plan view of the area enclosed by the broken circle shown in FIG. 1;

FIG. 3A is an enlarged cross-sectional view showing the structure of a second part of the connection structure according to a first embodiment of the present invention and FIG. 3B is an enlarged cross-sectional view showing the structure of another second part of the connection structure according to the first embodiment;

FIG. 4A is an enlarged cross-sectional view of a first part and FIG. 4B is an enlarged cross-sectional view of the portion of a Si electrode to which an Al wire has not been bonded;

FIG. 5 is a view schematically showing an embodiment of a system for applying a voltage between the Si electrode and the Al wire bonded thereto;

FIG. 6 is a graph showing the result of examining an I-V characteristic;

FIG. 7 is a schematic view when a connection portion is viewed from above the Si electrode;

FIGS. 8A and 8B are cross-sectional views each partly illustrating a method for fabricating a connection structure;

FIG. 9A is an enlarged cross-sectional view showing the structure of a second part of a connection structure according to a second embodiment of the present invention and FIG. 9B is an enlarged cross-sectional view showing the structure of another second part of the connection structure according to the second embodiment;

FIG. 10A is an enlarged cross-sectional view showing the structure of a second part of a connection structure according to a third embodiment of the present invention and FIG. 10B is an enlarged cross-sectional view showing the structure of another second part of the connection structure according to the third embodiment;

FIG. 11 is an enlarged cross-sectional view showing the structure of a second part of a connection structure according to a fourth embodiment of the present invention; and

FIGS. 12A to 12D are cross-sectional views showing the process steps of fabricating a CSP according to a fifth embodiment of the present invention.

Claims

1. A connection structure between a Si member made of Si and an Al member made of Al, the connection structure comprising: a first part and a second part each interposed between the Si member and the Al member in contact relation with each of the Si member and the Al member, whereina Si oxide layer and an Al oxide layer are present in the first part such that the Si oxide layer is in contact with the Si member and the Al oxide layer is interposed between the Si oxide layer and the Al member andat least one of Si and Al is present in the second part.

2. The connection structure of claim 1, wherein the second part is made of Al.

3. The connection structure of claim 1, wherein the second part is made of Si.

4. The connection structure of claim 1, wherein an Al portion made of Al and a Si portion made of Si are present in the second part,the Al portion extends from the Al member toward the Si member, andthe Si portion extends from the Si portion toward the Al member and is in contact with the Al portion.

5. The connection structure of claim 4, wherein the Al portion contains Si andthe Si portion contains Al.

6. The connection structure of claim 1, wherein the second part has Al and Si mixed therein.

7. The connection structure of claim 1, wherein the Si member is a Si electrode,the Al member is an Al wire,each of the first and second parts is present in a connection portion in which the Al wire is connected to a surface of the Si electrode, andthe second parts are present in dotted relation at the surface of the Si electrode and at a peripheral portion of the connection portion.

8. The connection structure of claim 1, wherein the Si member is a Si electrode,the Al member is an Al wire containing Si;each of the first and second parts is present in a connection portion in which the Al wire is connected to the Si electrode,the connection portion has a generally ellipsoidal outer configuration at the surface of the Si electrode, andthe second parts are present in dotted relation inside the connection portion longitudinally thereof.

9. The connection structure of claim 7, wherein a portion of the Al wire which is in contact with the first part and the second part is deformed andthe deformed portion of the Al wire has a width which is 1.5 times or more a width of a portion of the Al wire which is not deformed.

10. The connection structure of claim 1, wherein a portion of the Al member which is in contact with the first part and the second part is deformed andthe deformed portion of the Al member contains at least Si.

11. The connection structure of claim 1, wherein a portion of the Si member which is in contact with the first part and the second part contains at least Al.

12. The connection structure of claim 1, wherein the Si member has a part thereof in contact with the first part and the second part,a natural oxide film is present on a portion of a surface of the Si member which is not in contact with the first and second parts, andthe natural oxide film has a thickness larger than a thickness of the Si oxide layer.

13. A connection structure between a Si member made of Si and an Al member made of Al, the connection structure comprising: an interposed layer composed of a Si oxide layer and an Al oxide layer between the Si member and the Al member such that the Si member, the Si oxide layer, the Al oxide layer, and the Al member are stacked in this order, whereinthe interposed layer has a penetrating portion which extends from the Al member through the interposed layer to reach the Si member andthe penetrating portion is made of at least one of Al and Si.

14. The connection structure of claim 13, wherein the penetrating portion is made of Al.

15. The connection structure of claim 13, wherein the penetrating portion is made of Si.

16. The connection structure of claim 13, wherein an Al portion made of Al and a Si portion made of Si are present in the penetrating portion,the Al portion extends from the Al member toward the Si member, andthe Si portion extends from the Si member toward the Al member and is in contact with the Al portion.

17. The connection structure of claim 16, wherein the Al portion contains Si andthe Si portion contains Al.

18. The connection structure of claim 13, wherein the penetrating portion has Al and Si mixed therein.

19. The connection structure of claim 13, wherein the Si member is a Si electrode,the Al member is an Al wire containing Si,the interposed layer is present in a connection portion in which the Al wire is connected to a surface of the Si electrode, andthe penetrating portions are present in dotted relation at the surface of the Si electrode and at a peripheral portion of the connection portion.

20. The connection structure of claim 13, wherein the Si member is a Si electrode,the Al member is an Al wire containing Si,the interposed layer is present in a connection portion in which the Al wire is connected to a surface of the Si electrode,the connection portion has a generally ellipsoidal configuration at the surface of the Si electrode, andthe penetrating portions are present in dotted relation inside the connection portion longitudinally thereof.

21. The connection structure of claim 19, wherein a portion of the Al wire which is in contact with the interposed layer is deformed andthe deformed portion of the Al wire has a width which is 1.5 times or more a width of a portion of the Al wire which is not deformed.

22. The connection structure of claim 13, wherein a portion of the Al member which is in contact with the interposed layer is deformed andthe deformed portion of the Al member contains at least Si.

23. The connection structure of claim 13, wherein a portion of the Si member which is in contact with the interposed layer contains at least Al.

24. The connection structure of claim 13, wherein the Si member has a part thereof in contact with the interposed layer,a natural oxide film is present on a portion of a surface of the Si member which is not in contact with the interposed layer, andthe natural oxide film has a thickness larger than a thickness of the Si oxide layer.

25. The connection structure of claim 1, wherein each of the Al oxide layer and the Si oxide layer has a substantially uniform thickness.

26. The connection structure of claim 1, wherein a total combined thickness of the Al oxide layer and the Si oxide layer is not less than 0.1 nm and not more than 10 nm.

27. The connection structure of claim 1, wherein the Si is polycrystalline silicon.

28. A method for fabricating a connection structure between a Si member and an Al member, the method comprising: a bonding step of pressing the Al member against the Si member by using a solderless vibrating member and applying an ultrasonic wave to the solderless vibrating member to bond the Al member to the Si member; anda voltage applying step of applying a voltage between the Si member and the Al member bonded thereto, whereinthe bonding step includes forming an interposed layer composed of an Al oxide layer and a Si oxide layer between the Al member and the Si member andthe voltage applying step includes partially removing the interposed layer to bring the Al member and the Si member into contact with each other.

29. The method of claim 28, wherein the voltage applying step includes applying a voltage of 1 V or more.

30. The method of claim 28, wherein a member made of polycrystalline silicon is used as the Si member.