Semiconductor device and method of forming multi-layered UBM with intermediate insulating buffer layer to reduce stress for semiconductor wafer
View Patent ↗A semiconductor wafer has a contact pad. A first insulating layer is formed over the wafer. A second insulating layer is formed over the first insulating layer and contact pad. A portion of the second insulating layer is removed to expose the contact pad. A first UBM layer is formed over and follows a contour of the second insulating layer and contact pad to create a well over the contact pad. A first buffer layer is formed in the well over the first UBM layer and the contact pad. A second UBM layer is formed over the first UBM layer and first buffer layer. A third UBM layer is formed over the second UBM layer. A bump is formed over the third UBM layer. The first buffer layer reduces stress on the bump and contact pad. A second buffer layer can be formed between the second and third UBM layers.
1. A method of making a semiconductor device, comprising:
providing a semiconductor wafer including a contact pad;
forming a first conductive layer over the contact pad;
forming a first buffer layer over the first conductive layer and the contact pad;
forming a second conductive layer over the first conductive layer and first buffer layer with a first surface of the first buffer layer disposed over the first conductive layer and the second conductive layer disposed over a second surface of the first buffer layer opposite the first surface of the first buffer layer and the second conductive layer electrically connected to the first conductive layer; and
forming a bump over the second conductive layer.
2. The method of claim 1 , wherein the first buffer layer reduces stress on the bump and contact pad.
3. The method of claim 1 , further including:
forming a first insulating layer over the semiconductor wafer;
forming the first conductive layer to follow a contour of the first insulating layer and the contact pad to create a well over the contact pad; and
forming the first buffer layer in the well over the contact pad.
4. The method of claim 1 , further including forming a second buffer layer over the second conductive layer.
5. The method of claim 1 , further including forming a third conductive layer over the second conductive layer and electrically connected to the second conductive layer.
6. The method of claim 5 , wherein forming the bump includes:
forming a photoresist layer over the third conductive layer;
removing a portion of the photoresist layer to expose the third conductive layer;
depositing a bump material over the third conductive layer; and
reflowing the bump material to form the bump.
7. The method of claim 5 , wherein the first, second, and third conductive layer are stacked under a bump metallization layers.
8. A method of making a semiconductor device, comprising:
providing a semiconductor die including a contact pad;
forming a first conductive layer over the contact pad;
forming a first buffer layer over the first conductive layer and the contact pad;
forming a second conductive layer over the first conductive layer and the first buffer layer with the first buffer layer disposed between first conductive layer and second conductive layer; and
forming an electrical interconnect over the second conductive layer.
9. The method of claim 8 , further including:
forming a first insulating layer over the semiconductor die; and
forming a second insulating layer over the first insulating layer and contact pad.
10. The method of claim 8 , wherein the electrical interconnect includes a bump.
11. The method of claim 8 , wherein the first buffer layer reduces stress on the electrical interconnect and the contact pad.
12. The method of claim 8 , further including:
forming a first insulating layer over the semiconductor die;
forming the first conductive layer to follow a contour of the first insulating layer and contact pad to create a well over the contact pad; and
forming the first buffer layer in the well over the contact pad.
13. The method of claim 8 , further including forming a second buffer layer over the second conductive layer.
14. The method of claim 8 , further including forming a third conductive layer over the second conductive layer and electrically connected to the second conductive layer.
15. The method of claim 14 , wherein forming the electrical interconnect includes:
forming a photoresist layer over the third conductive layer;
removing a portion of the photoresist layer to expose the third conductive layer;
depositing a bump material over the third conductive layer; and
reflowing the bump material to form the electrical interconnect.
16. A method of making a semiconductor device, comprising:
providing a semiconductor die including a contact pad;
forming a first conductive layer over the contact pad;
forming a second conductive layer over the first conductive layer;
forming a third conductive layer over the second conductive layer;
forming a first buffer layer between the first conductive layer and third conductive layer; and
forming an electrical interconnect over the third conductive layer.
17. The method of claim 16 , wherein the first, second, and third conductive layer are stacked under a bump metallization layers.
18. The method of claim 16 , further including forming a second buffer layer over the second conductive layer prior to forming the third conductive layer.
19. The method of claim 16 , further including:
forming a first insulating layer over the semiconductor die; and
forming a second insulating layer over the first insulating layer and contact pad.
20. The method of claim 16 , wherein the first buffer layer reduces stress on the electrical interconnect and the contact pad.
21. The method of claim 16 , further including:
forming a first insulating layer over the semiconductor die;
forming the first conductive layer to follow a contour of the first insulating layer and the contact pad to create a well over the contact pad; and
forming the first buffer layer in the well over the contact pad.
22. A method of making a semiconductor device, comprising:
providing a semiconductor die including a contact pad;
forming a plurality of stacked conductive layers including a seed layer, an adhesion layer, and a wetting layer over the contact pad; and
forming a first buffer layer between the plurality of stacked conductive layers, wherein the first buffer layer is formed within a well over one of the plurality of stacked conductive layers.
23. The method of claim 22 , further including forming a second buffer layer between the plurality of stacked conductive layers.
24. The method of claim 22 , further including forming a first insulating layer over the semiconductor die.
25. The method of claim 22 , further including forming a second insulating layer over the first insulating layer.
26. The method of claim 22 , further including depositing a bump material over the plurality of stacked conductive layers.
27. A method of making a semiconductor device, comprising:
providing a semiconductor die;
forming a first conductive layer over the semiconductor die;
forming a first buffer layer over the first conductive layer;
forming a second conductive layer over the first conductive layer and first buffer layer with the first buffer layer disposed between first conductive layer and second conductive layer and the second conductive layer electrically connected to the first conductive layer; and
forming an interconnect structure over the second conductive layer.
28. The method of claim 27 , further including:
forming a first insulating layer over the semiconductor die; and
forming a second insulating layer over the first insulating layer.
29. The method of claim 27 , wherein the interconnect structure includes a bump.
30. The method of claim 27 , further including forming a second buffer layer over the second conductive layer.
31. The method of claim 30 , further including forming a third conductive layer over the second conductive layer and second buffer layer and electrically connected to the second conductive layer.