Flip chip interconnection
View Patent ↗Methods for forming flip chip interconnection, in which the bump interconnect is defined at least in part by an underfill. The underfill includes a material that is thermally cured; that is, raising the temperature of the underfill material can result in progressive curing of the underfill through stages including a gel stage and a fully cured stage. According to the invention, during at least an early stage in the process the semiconductor chip is carried by a thermode, which is employed to control the temperature of the assembly in a specified way. Also, flip chip interconnections and flip chip packages made according to the methods of invention.
1. A method for forming flip chip interconnection between a semiconductor die and a substrate, comprising:
mounting the substrate to a carrier, the substrate having a plurality of interconnect sites on conductive traces formed on a die attach surface of the substrate;
forming a plurality of bumps on an active surface of the semiconductor die, the bumps containing fusible material;
mounting a backside of the semiconductor die, opposite the active surface, to a thermode placement tool which generates thermal energy under control of a temperature controller;
depositing a resin material between the semiconductor die and substrate sufficient to cover the interconnect sites;
aligning the bumps of the semiconductor die to the interconnect sites of the substrate;
bringing the bumps into contact with the resin material;
applying a force with the thermode placement tool to bring the bumps into contact with the interconnect sites, the force being sufficient to displace the resin material and deform the bumps against the interconnect sites;
after deforming the bumps against the interconnect sites using the force of the thermode placement tool, employing the thermode placement tool to heat the semiconductor die and bring the resin material to a gel stage;
selecting a first temperature of the thermode placement tool to partially cure without completely curing the resin material and stabilize the semiconductor die to the substrate;
after partially curing the resin material, removing the force applied to the semiconductor die;
after removing the force applied to the semiconductor die, heating an entirety of the fusible material of the bumps to a molten state using the thermal energy from the thermode placement tool, wherein the partially cured resin material prevents flow of the fusible material to adjacent interconnect sites and conductive traces;
re-solidifying the fusible material to form metallurgical bond between the bumps and interconnect sites; and
after re-solidifying the fusible material, substantially curing the resin material.
2. The method of claim 1 wherein the gel stage is resilient enough to allow some compression, and is sufficiently firm to contain the molten fusible material.
3. The method of claim 1 , wherein the first temperature is applied a predetermined time after the force is applied.
4. The method of claim 1 , further including selecting a second temperature after the force is removed to heat the entirety of the fusible material to the molten state.
5. The method of claim 4 , wherein the second temperature is at least 170 degrees Centigrade.
6. A method for forming flip chip interconnection between a semiconductor die and a substrate, comprising:
mounting the substrate to a carrier, the substrate having a plurality of interconnect sites on conductive traces formed on a die attach surface of the substrate;
forming a plurality of bumps on an active surface of the semiconductor die, the bumps containing fusible material;
mounting a backside of the semiconductor die, opposite the active surface, to a thermode placement tool which generates thermal energy under control of a temperature controller;
depositing a resin material between the semiconductor die and substrate sufficient to cover interconnect sites;
aligning the bumps of the semiconductor die to the interconnect sites of the substrate;
applying a force with the thermode placement tool to bring the bumps into contact with the interconnect sites, the force being sufficient to displace the resin material and deform the bumps against the interconnect sites;
after deforming the bumps against the interconnect sites using the force of the thermode placement tool, employing the thermode placement tool to heat the semiconductor die and bring the resin material to a gel stage;
partially curing the resin material to stabilize the semiconductor die to the substrate;
after partially curing the resin material, removing the force applied to the semiconductor die;
after removing the force applied to the semiconductor die, disengaging the semiconductor die from the thermode placement tool;
placing the semiconductor die and substrate in a reflow oven;
heating an entirety of the fusible material of the bumps to a molten state using the thermal energy from the reflow oven, the partially cured resin material preventing flow of the fusible material to adjacent interconnect sites and conductive traces;
re-solidifying the fusible material to form metallurgical bond between the bumps and interconnect sites; and
after re-solidifying the fusible material, substantially curing the resin material.
7. The method of claim 6 , further including re-melting the fusible material.
8. The method of claim 7 , wherein the fusible material is re-melted in a reflow oven.
9. The method of claim 6 , wherein a pitch between the bumps is 60 micrometers.
10. A method for forming flip chip interconnection between a semiconductor die and a substrate, comprising:
mounting the semiconductor die and the substrate to a thermode placement tool;
depositing a resin material between the semiconductor die and the substrate sufficient to cover interconnect sites formed on the substrate;
aligning bumps formed on the semiconductor die to the interconnect sites of the substrate;
applying a force with the thermode placement tool to bring the bumps into contact with the interconnect sites;
heating the semiconductor die to bring the resin material to a gel stage;
partially curing the resin material to stabilize the semiconductor die to the substrate;
after partially curing the resin material, removing the force applied to the semiconductor die;
after removing the force applied to the semiconductor die, disengaging the semiconductor die from the thermode placement tool;
placing the semiconductor die and substrate in a reflow oven;
heating the bumps to a molten state using the thermal energy from the reflow oven, the partially cured resin material preventing flow of the bumps to adjacent interconnect sites and conductive traces;
re-solidifying the bumps to form metallurgical bond between the bumps and interconnect sites; and
after re-solidifying the bumps, substantially curing the resin material.
11. The method of claim 10 , wherein a first temperature is applied a predetermined time after the force is applied.
12. The method of claim 10 , wherein the bumps contain fusible material.
13. The method of claim 12 , further including selecting a second temperature after the force is removed to heat the entirety of the fusible material to the molten state.
14. The method of claim 13 , wherein the second temperature is at least 170 degrees Centigrade.
15. The method of claim 12 , further including re-melting the fusible material.
16. The method of claim 15 , wherein the fusible material is re-melted in a reflow oven.
17. The method of claim 10 , wherein a pitch between the bumps is 60 micrometers.
18. A method for forming flip chip interconnection between a semiconductor die and a substrate, comprising:
mounting the semiconductor die and the substrate to a thermode placement tool;
depositing a resin material between the semiconductor die and the substrate sufficient to cover interconnect sites formed on the substrate;
aligning bumps formed on the semiconductor die to the interconnect sites of the substrate;
applying a force with the thermode placement tool to bring the bumps into contact with the interconnect sites;
heating the resin material to a gel stage;
partially curing the resin material to stabilize the semiconductor die to the substrate;
disengaging the semiconductor die from the thermode placement tool;
placing the semiconductor die and the substrate in a reflow oven;
heating the bumps to a molten state using the thermal energy from the reflow oven, the partially cured resin material preventing flow of the bumps to adjacent interconnect sites and conductive traces;
re-solidifying the bumps to form metallurgical bond between the bumps and interconnect sites; and
substantially curing the resin material.
19. The method of claim 18 , wherein a first temperature is applied a predetermined time after the force is applied.
20. The method of claim 18 , wherein the bumps contain fusible material.
21. The method of claim 20 , further including selecting a second temperature after the force is removed to heat the entirety of the fusible material to the molten state.
22. The method of claim 21 , wherein the second temperature is at least 170 degrees Centigrade.
23. The method of claim 20 , further including re-melting the fusible material.
24. The method of claim 23 , wherein the fusible material is re-melted in a reflow oven.
25. The method of claim 18 , wherein a pitch between the bumps is 60 micrometers.
26. A method for forming flip chip interconnection between a semiconductor die and a substrate, comprising:
mounting the semiconductor die and the substrate to a thermode placement tool;
depositing a resin material between the semiconductor die and the substrate sufficient to cover interconnect sites formed on the substrate;
aligning bumps formed on the semiconductor die to the interconnect sites of the substrate;
applying a force with the thermode placement tool to bring the bumps into contact with the interconnect sites;
heating the resin material to a gel stage;
partially curing the resin material to stabilize the semiconductor die to the substrate;
removing the force applied to the semiconductor die;
heating the bumps to a molten state, the partially cured resin material preventing flow of the bumps to adjacent interconnect sites and conductive traces;
re-solidifying the bumps to form metallurgical bond between the bumps and interconnect sites; and
after re-solidifying the bumps, substantially curing the resin material.
27. The method of claim 26 , wherein a first temperature is applied a predetermined time after the force is applied.
28. The method of claim 26 , wherein the bumps contain fusible material.
29. The method of claim 28 , further including selecting a second temperature after the force is removed to heat the entirety of the fusible material to the molten state.
30. The method of claim 29 , wherein the second temperature is at least 170 degrees Centigrade.
31. The method of claim 28 , further including re-melting the fusible material.
32. The method of claim 31 , wherein the fusible material is re-melted in a reflow oven.
33. The method of claim 26 , wherein a pitch between the bumps is 60 micrometers.