Methods of forming solder connections and structure thereof
View Patent ↗A method comprises depositing a first metal containing layer into a trench structure, which contacts a metalized area of a semiconductor structure. The method further includes patterning at least one opening in a resist to the first metal containing layer. The opening should be in alignment with the trench structure. At least a pad metal containing layer is formed within the at least one opening (preferably by electroplating processes). The resist and the first metal layer underlying the resist are then etched (with the second metal layer acting as a mask, in embodiments). The method includes flowing solder material within the trench and on pad metal containing layer after the etching process. The structure is a controlled collapse chip connection (C4) structure comprising at least one electroplated metal layer formed in a resist pattern to form at least one ball limiting metallurgical layer. The structure further includes an underlying metal layer devoid of undercuts.
1. A controlled collapse chip connection (C4) structure comprising:
a back end of the line metallization layer on a semiconductor structure;
a metal layer formed in direct contact with the back end of the line metallization layer;
an electroplated metal layer formed in a resist pattern to form ball limiting metallurgical layers, formed directly on the metal layer which is devoid of undercuts; and
a lead free solder bump on the electroplated metal layer.
2. The structure according to claim 1 , comprising a multitude of electroplated metal layers that are separated by the resist pattern.
3. A structure comprising a passivated layer with a trench over at least a metallized layer in a structure, a first metal containing layer within the trench and contacting a back of the end process metal layer, an electroplated metal layer dimensionally controlled by a patterned resist overlying and contacting the first metal containing layer and a solder material reflowed directly in contact with the electroplated metal containing layer to form a solder bump, wherein the first metal containing layer is devoid of an undercut.
4. The structure according to claim 3 , wherein the first metal containing layer is provided on the passivation layer.
5. The structure according to claim 3 , wherein the electroplated metal is copper.
6. A structure comprising:
a first metal containing layer deposited into a trench structure, which contacts a metalized area within the structure;
at least an electroplated pad metal containing layer or bilayer in contact with a portion of the first metal containing layer, wherein the at least the pad metal containing layer or the bilayer is formed within the trench structure; and
solder material within the trench structure and on the electroplated pad metal containing layer to form a solder bump extending within the trench structure.
7. The structure according to claim 6 , further comprising a passivation layer under the first metal layer and an opening in the passivation layer which has formed the trench structure.
8. The structure according to claim 7 , wherein the passivation layer comprises at least one of silicon nitride, silicon oxide and polyimide.
9. The structure according to claim 6 , wherein the first metal containing layer comprises at least one of the class of refractory metals or their alloys including titanium, tungsten, titanium-tungsten alloy.
10. The structure according to claim 6 , wherein the first metal containing layer comprises a physical vapor deposition metal.
11. The structure according to claim 6 , wherein the electroplated pad metal containing layer comprises copper or copper with a diffusion barrier metal including nickel or alloys of nickel.
12. The structure according to claim 6 , wherein the electroplated pad metal containing layer or bilayer comprises an electroplated metal.
13. The structure according to claim 6 , wherein the electroplated pad metal containing layer is between about 2 to about 3 μm thick.
14. The structure according to claim 6 , wherein a longitudinal dimension of the electroplated pad metal layer is controlled by a resist.
15. The structure according to claim 6 , wherein the solder material comprises lead-free tin containing material or lead reduced tin containing material.
16. The structure according to claim 6 , wherein a longitudinal size of a solder connection is based on a longitudinal dimension of the electroplated pad metal containing layer or at least one opening in a resist.
17. The structure according to claim 6 , wherein a ball limiting metallurgical (BLM) layer comprises a remaining first metal containing layer after an etching and the electroplated pad metal containing layer.
18. The structure according to claim 6 , wherein the electroplated pad metal containing layer or bilayer is arranged to act as a mask to an underlying layer during an etching.
19. The structure according to claim 6 , wherein the solder material comprises a multitude of solder connections formed from a mold comprising solder material.