WAFER BUMPING USING PRINTED UNDER BUMP METALIZATION
Methods, systems, and apparatuses for printing under bump metallization (UBM) features on chips/wafers are provided. A wafer is received that has a surface defined by a plurality of integrated circuit regions. Each integrated circuit region has a passivation layer and a plurality of terminals on the surface of the wafer accessible through openings in the passivation layer. A plurality of UBM features are formed on the surface of the wafer in the form of an ink such that each UBM feature is formed electrically coupled with a corresponding terminal of the plurality of terminals. An ink jet printer may be used to print the ink in the form of the UBM feature. A UBM feature may be formed directly on a corresponding terminal, or on routing that is coupled to the corresponding terminal. A bump interconnect may be formed on the UBM feature.
1 . A method, comprising:
receiving a wafer having a surface defined by a plurality of integrated circuit regions, each integrated circuit region having a passivation layer and a plurality of terminals on the surface of the wafer accessible through openings in the passivation layer; and
printing a plurality of under bump metallization (UBM) features in the form of an ink on the surface of the wafer such that each UBM feature is formed electrically coupled with a corresponding terminal of the plurality of terminals.
2 . The method of claim 1 , wherein said printing comprises:
printing a UBM feature in the form of an ink directly on at least one terminal of the plurality of terminals.
3 . The method of claim 1 , further comprising:
forming a plurality of routing interconnects on the surface of the wafer such that each routing interconnect has a first portion in contact with a respective terminal of the plurality of terminals and has a second portion that extends over the passivation layer;
wherein said printing comprises
printing a plurality of UBM features in the form of an ink on the plurality of routing interconnects such that each UBM feature is formed on the second portion of a respective routing interconnect of the plurality of routing interconnects.
4 . The method of claim 1 , further comprising:
forming a plurality of bump interconnects on the plurality of UBM features.
5 . The method of claim 4 , wherein said forming comprises:
printing the plurality of bump interconnects in the form of an ink on the plurality of UBM features
6 . The method of claim 1 , wherein the ink includes a metal paste, wherein said printing comprises:
printing the metal paste on the surface of the wafer to form the plurality of UBM features.
7 . The method of claim 1 , wherein said printing comprises:
ink jet printing the plurality of UBM features on the surface of the wafer.
8 . The method of claim 1 , wherein said printing comprises:
printing a first ink on a first region of the surface of the wafer to form a first UBM feature electrically coupled to a first terminal; and
printing a second ink on a second region of the surface of the wafer to form a second UBM feature electrically coupled to a second terminal;
wherein the second ink is different from the first ink.
9 . The method of claim 1 , wherein said printing comprises:
printing a plurality of layers of ink to form at least one of the UBM features.
10 . The method of claim 9 , wherein said printing comprises:
printing a first ink on the surface of the wafer to form a first layer of the plurality of layers of ink of a first UBM feature; and
printing a second ink on the first layer to form a second layer of the plurality of layers of ink of the first UBM feature;
wherein the second ink is different from the first ink.
11 . The method of claim 1 , further comprising:
singulating the wafer to form a plurality of integrated circuit packages that each include at least one integrated circuit region of the plurality of integrated circuit regions.
12 . An integrated circuit (IC) package, comprising:
an integrated circuit die having a plurality of terminals on a surface of the integrated circuit die;
a passivation layer on the surface of the integrated circuit die having a plurality of openings that provide access to the plurality of terminals; and
a plurality of under bump metallization (UBM) features printed on the integrated circuit die, each UBM feature being electrically coupled to a corresponding terminal of the plurality of terminals, and each UBM feature comprising a solidified ink.
13 . The IC package of claim 12 , wherein at least one UBM feature is formed directly on a corresponding terminal of the plurality of terminals.
14 . The IC package of claim 12 , further comprising:
a plurality of routing interconnects each having a first portion and a second portion, the first portion of each routing interconnect being in contact with a respective terminal of the plurality of terminals though a respective opening in the passivation layer and the second portion of each routing interconnect extending over the passivation layer;
wherein each UBM feature is printed on the second portion of a respective routing interconnect of the plurality of routing interconnects.
15 . The IC package of claim 12 , further comprising:
a plurality of bump interconnects printed on the plurality of UBM features.
16 . The IC package of claim 15 , wherein the plurality of bump interconnects is arranged in an array of bump interconnects.
17 . The IC package of claim 12 , wherein the ink includes a metal paste.
18 . The IC package of claim 17 , wherein the metal paste is a nanopaste.
19 . The IC package of claim 18 , wherein the metal paste includes at least one of silver or copper.
20 . The IC package of claim 12 , wherein a first UBM feature of the plurality of UBM features is printed on a first region of the surface of the integrated circuit die using a first ink, the first UBM feature being electrically coupled to a first terminal;
wherein a second UBM feature of the plurality of UBM features is printed on a second region of the surface of the integrated circuit die using a second ink, the second UBM feature being electrically coupled to a second terminal; and
wherein the second ink is different from the first ink.
21 . The IC package of claim 12 , wherein at least one UBM feature comprises a stack of layers of solidified ink.
22 . The IC package of claim 21 , wherein a first UBM feature of the plurality of UBM features includes a first UBM layer formed of a first ink printed on the surface of the wafer and a second UBM layer formed of a second ink printed on the first UBM layer;
wherein the second ink is different from the first ink.
23 . A system for processing a wafer to form integrated circuit (IC) packages, comprising:
an ink jet printer configured to print a plurality of under bump metallization (UBM) features on the surface of a wafer in the form of an ink, the wafer having a surface defined by a plurality of integrated circuit regions, each integrated circuit region having a passivation layer and a plurality of terminals on the surface of the wafer accessible through openings in the passivation layer.
24 . The system of claim 23 , further comprising:
a solder bump applicator configured to form a plurality of bump interconnects on the plurality of UBM features such that each bump interconnect of the plurality of bump interconnects is formed on a respective UBM feature.
25 . The system of claim 23 , wherein the ink jet printer is configured to print using a metal paste as the ink.
26 . The system of claim 25 , wherein the ink jet printer is configured to print using a nanopaste as the metal paste.
27 . The system of claim 25 , wherein the metal paste includes at least one of silver or copper.
28 . The system of claim 23 , wherein the ink jet printer includes a plurality of print heads configured to spray ink.