Method of making bond pad
A method of making a bonding pad for a semiconductor device includes depositing a first region of the bonding pad on a top metal of the semiconductor device at a first temperature, wherein the first region comprises aluminum, and an entirety of a material of the first region of the bonding pad is different from a material of the top metal. The method further includes depositing a second region of the bonding pad on the first region at a second temperature, wherein the first temperature is different from the second temperature, and the second region is a metallic region.
1. A method of making a bonding pad for a semiconductor device, the method comprising:
depositing a first region of the bonding pad on a top metal of the semiconductor device at a first temperature, wherein the first region comprises aluminum, and an entirety of a material of the first region of the bonding pad is different from a material of the top metal; and
depositing a second region of the bonding pad on the first region at a second temperature, wherein the first temperature is different from the second temperature, and the second region is a metallic region.
2. The method of claim 1 , wherein the first temperature is higher than the second temperature.
3. The method of claim 1 , wherein the first region is deposited at a temperature ranging from 300° C. to 400° C.
4. The method of claim 1 , wherein the second region is deposited at a temperature ranging from 150° C. to 300° C.
5. The method of claim 1 , wherein the first region is deposited in a first chamber and the second region is deposited in a second chamber, wherein the first chamber is different from the second chamber.
6. The method of claim 1 , wherein steps of depositing the first region and depositing the second region are performed using physical vapor deposition.
7. The method of claim 1 , wherein depositing the second region comprises depositing a material different from the material of the first region.
8. The method of claim 1 , wherein depositing the first region comprises depositing an aluminum-copper alloy.
9. A method of making a bonding pad for a semiconductor device, the method comprising:
forming a passivation layer over a dielectric layer, wherein the passivation layer defines an opening exposing at least a portion of a top metal layer;
depositing a first region over the top metal layer, the first region comprising aluminum and having a first average grain size; and
depositing a second region over the first region, the second region comprising aluminum, wherein the second region has a second average grain size different from the first average grain size, and the first region and the second region extend along a top surface of the passivation layer.
10. The method of claim 9 , further comprising forming a buffer layer over the bonding pad, wherein the buffer layer is between the bonding pad and the first region.
11. The method of claim 10 , wherein forming the buffer layer comprises lining sidewalls of the passivation layer.
12. The method of claim 9 , further comprising etching the passivation layer to define the opening.
13. The method of claim 9 , further comprising forming a second passivation layer over a portion of the second region.
14. The method of claim 9 , wherein depositing the second region comprises depositing the second region in a same process as depositing the first region, wherein the first region is deposited at a first temperature of the process, the second region is deposited at a second temperature of the process, and a change from the first temperature to the second temperature is a step-wise change.
15. The method of claim 9 , wherein depositing the second region comprise depositing the second region having the second average grain size at least about 1.5 times smaller than the first average grain size.
16. A method of making a bonding pad for a semiconductor device, the method comprising:
forming a passivation layer over a dielectric layer;
etching the passivation layer to form an opening exposing at least a portion of a top metal layer; and
depositing an aluminum-containing layer in the opening and over a top surface of the passivation layer, wherein depositing the aluminum-containing layer comprises continuously decreasing a temperature from an initial deposition temperature to a final deposition temperature, and a first average grain size of the aluminum-containing layer closest to the top metal layer is different from a second average grain size of the aluminum-containing layer farthest from the top metal layer.
17. The method of claim 16 , wherein depositing the aluminum-containing layer comprises depositing an aluminum-copper alloy.
18. The method of claim 16 , wherein depositing the aluminum-containing layer comprises depositing the aluminum-containing layer at the initial deposition temperature ranging from about 300° C. to about 450° C.
19. The method of claim 16 , wherein depositing the aluminum-containing layer comprises depositing the aluminum-containing layer at the final deposition temperature ranging from about 150° C. to about 300° C.
20. The method of claim 16 , wherein depositing the aluminum-containing layer comprises sputtering, evaporative deposition or pulsed laser deposition.