Simultaneous plating of varying size features on semiconductor substrate
View Patent ↗Techniques for simultaneously plating features of varying sizes on a semiconductor substrate are provided. In one aspect, a method for electroplating includes: placing a shield over a wafer, offset from a surface of the wafer, which covers portions of the wafer and leaves other portions of the wafer uncovered; and depositing at least one metal onto the wafer by electroplating to simultaneously form metallurgical features of varying sizes on the wafer based on the shield altering local deposition rates for the portions of the wafer covered by the shield. An electroplating apparatus is also provided.
1. A method for electroplating, the method comprising the steps of:
placing a shield over a wafer, offset from a surface of the wafer, which covers portions of the wafer and leaves other portions of the wafer uncovered; and
depositing at least one metal onto the wafer by electroplating to simultaneously form metallurgical features of varying sizes on the wafer based on the shield altering local deposition rates for the portions of the wafer covered by the shield.
2. The method of claim 1 , wherein the metallurgical features are selected from the group consisting of: pads, pedestals, pillars, and combinations thereof.
3. The method of claim 1 , wherein the metallurgical features have varying diameters.
4. The method of claim 1 , wherein the metallurgical features have varying heights.
5. The method of claim 4 , further comprising the steps of:
placing a different shield over the wafer, offset from the surface of the wafer, which covers select metallurgical features and leaves other metallurgical features uncovered; and
simultaneously depositing varying amounts of solder onto the metallurgical features by electroplating through the patterned structure based on the different shield altering local deposition rates for the select metallurgical features covered by the different shield.
6. The method of claim 5 , wherein the solder is selected from the group consisting of: tin-silver (SnAg) solder, tin-silver-copper (SnAgCu) solder, and combinations thereof.
7. The method of claim 1 , wherein the at least one metal comprises copper.
8. The method of claim 7 , wherein the seed layer comprises a material selected from the group consisting of: copper (Cu), copper titanium (CuTi), copper manganese (CuMn), and combinations thereof.
9. The method of claim 1 , wherein the shield is formed from an insulator.
10. The method of claim 9 , wherein the insulator is selected from the group consisting of: plastic, glass, and combinations thereof.
11. The method of claim 1 , wherein the shield is offset a distance d from the surface of the wafer, the method further comprising the step of:
varying the distance d the shield is offset from the surface of the wafer.
12. The method of claim 1 , wherein the shield is attached to an adjustable standoff structure that is configured to be raised or lowered to vary the distance d the shield is offset from the surface of the wafer.
13. The method of claim 1 , wherein at least one portion of the shield comprises a raised topography, wherein the portion of the shield that comprises the raised topography is at a distance d 2 from the surface of the wafer, and other portions of the shield are at a distance d 1 from the surface of the wafer, and wherein d 1 >d 2 .
14. The method of claim 1 , further comprising the steps of:
depositing a seed layer onto the wafer;
creating a patterned structure on the wafer over the seed layer using a photoresist;
placing the shield over the patterned structure;
depositing the at least one metal onto the wafer by the electroplating through the patterned structure to simultaneously form the metallurgical features of varying sizes on the wafer;
removing the patterned structure; and
etching the seed layer.
15. The method of claim 14 , wherein the seed layer comprises copper (Cu).
16. An electroplating apparatus, comprising:
a vessel containing an electrolyte;
a wafer immersed in the electrolyte; and
a shield positioned over the wafer, offset from a surface of the wafer, which covers portions of the wafer and leaves other portions of the wafer uncovered, wherein the shield is configured to alter local deposition rates during electroplating for the portions of the wafer covered by the shield.
17. The electroplating apparatus of claim 16 , wherein the shield is formed from an insulator.
18. The electroplating apparatus of claim 17 , wherein the insulator is selected from the group consisting of: plastic, glass, and combinations thereof.
19. The electroplating apparatus of claim 16 , wherein the shield is offset a distance d from the surface of the wafer, and wherein the electroplating apparatus further comprises:
an adjustable standoff structure, to which the shield is attached, configured to vary the distance d the shield is offset from the surface of the wafer.
20. The electroplating apparatus of claim 16 , wherein at least one portion of the shield comprises a raised topography, wherein the portion of the shield that comprises the raised topography is at a distance d 2 from the surface of the wafer, and other portions of the shield are at a distance d 1 from the surface of the wafer, and wherein d 1 >d 2 .