Pulse-laser bonding method for through-silicon-via based stacking of electronic components
View Patent ↗There is described a method of forming a through-silicon-via to form an interconnect between two stacked semiconductor components using pulsed laser energy. A hole is formed in each component, and each hole is filled with a plug formed of a first metal. One component is then stacked on another component such that the holes are in alignment, and a pulse of laser energy is applied to form a bond between the metal plugs.
1. A method of forming a through-silicon-via to form an interconnect between two stacked semiconductor components, comprising:
(a) forming a hole in each said component,
(b) forming an isolation layer, an adhesion layer, and a SiO 2 layer in said hole, wherein the SiO 2 layer is removed from the bottom of said hole,
(c) filling each said hole with a plug formed of a first metal such that said metal plug is level with the bottom surface of the respective said component,
(d) stacking one said component on another said component such that said holes are in alignment, and
(e) applying a pulse of laser energy at said holes to form a bond between said metal plugs.
2. A method as claimed in claim 1 wherein a second metal is provided between said plugs, and wherein upon application of said pulse of laser energy intermetallic compounds are formed at the junctions between said metal and said plugs by diffusion bonding.
3. A method as claimed in claim 1 wherein the forming an adhesion layer comprises forming the adhesion layer between each said plug and an inner surface of a respective hole.
4. A method as claimed in claim 3 wherein a said hole is formed with an inner surface that diverges towards an opening in a surface of the component.
5. A method as claimed in claim 4 wherein said inner surface diverges at an angle of between 2° and 15° .
6. A method as claimed in claim 3 wherein said adhesion layer comprises TiW, TiN, TaN, Cr or Ti.
7. A method as claimed in claim 1 further comprising providing an isolation layer on the upper surface of each said component and the inner wall of the via hole.
8. A method as claimed in claim 7 wherein said isolation layer comprises SiO 2 , SiN, polyimide, or benzocyclobutene.
9. A method as claimed in claim 1 further comprising providing a polymer material between said components.
10. A method as claimed in claim 9 wherein said polymer material comprises polyimide, benzocyclobutene, epoxy, a non-conductive adhesive, or silicon rubber.
11. A method as claimed in claim 1 wherein the power of said laser energy is between 1 and 70J.
12. A method as claimed in claim 1 wherein the laser energy pulse has a duration of between 1μs and 20ms.
13. A method as claimed in claim 12 wherein the laser energy pulse has a duration of between 1ms and 10ms.
14. A method as claimed in claim 1 wherein the laser energy pulse is provided by a Nd:YAG laser operating at a wavelength of 1064nm.
15. A method as claimed in claim 1 wherein the first metal is selected from Au, Cu, Sn, In, Ag, Ni, W and solders.
16. A method as claimed in claim 2 wherein the second metal is selected from Sn, In, Cu, Au, Ag, Ni, W and solders.
17. A method as claimed in claim 1 wherein prior to filling said hole with metal, the bottom of said hole is provided with the layer of SiO 2 that is subsequently removed after filling.
18. A through-silicon-via interconnect structure between and interconnecting two stacked semiconductor components wherein said structure comprises respective holes formed in said semiconductor components and with a first said component being stacked on and located above a second said component such that the hole formed in the first said component overlies the hole formed in the second said component and which said holes of said first and second said components are in alignment, each said hole including an isolation layer, an adhesion layer, and a SiO2 layer, and being filled with a plug formed of a first metal such that said metal plug is level with the bottom surface of the respective said component and wherein the SiO2 layer is removed from the bottom of said hole, a second metal being provided between said metal plugs of said first metal, and a bond between said metal plugs and including intermetallic compounds formed by diffusion bonding at the junctions of the metal plugs of the first metal and said second metal using a pulse of laser energy applied at said holes.
19. A through-silicon-via interconnect structure as claimed in claim 18 wherein the inner surfaces of said holes are provided with the adhesion layer.
20. A through-silicon-via interconnect structure as claimed in claim 19 wherein the adhesion layer is formed of TiW, TiN, TaN, Cr or Ti.
21. A through-silicon-via interconnect structure as claimed in claim 19 wherein the inner surfaces of said holes diverge outwardly towards an opening formed in an upper surface of the respective component in which the hole is formed.
22. A through-silicon-via interconnect structure as claimed in claim 21 wherein the inner surfaces diverge at between 2° to 15° .
23. A through-silicon-via interconnect structure as claimed in claim 18 wherein an upper surface of at least the second component is provided with an isolation layer.
24. A through-silicon-via interconnect structure as claimed in claim 23 wherein the isolation layer upon the upper surface of at least the second component is formed of SiO 2 , SiN, polyimide, or benzocyclobytene.
25. A through-silicon-via interconnect structure as claimed in claim 18 wherein a polymer material is provided between the two components.
26. A through-silicon-via interconnect structure as claimed in claim 25 wherein the polymer material comprises polyimide, benzocyclobytene, epoxy, a non-conductive adhesive, or silicon rubber.