Methods for forming through-substrate conductor filled vias, and electronic assemblies formed using such methods
View Patent ↗Through substrate vias for back-side electrical and thermal interconnections on very thin semiconductor wafers without loss of wafer mechanical strength during manufacturing are provided by: forming desired device regions with contacts on the front surface of an initially relatively thick wafer; etching via cavities partly through the wafer in the desired locations; filling the via cavities with a conductive material coupled to some device region contacts; mounting the wafer with its front side facing a support structure; thinning the wafer from the back side to expose internal ends of the conductive material filled vias; applying any desired back-side interconnect region coupled to the exposed ends of the filled vias; removing the support structure and separating the individual device or IC assemblies so as to be available for mounting on a further circuit board, tape or larger circuit.
1. A method for forming through-substrate conductor filled vias for back-side electrical or thermal interconnections or both on a thinned substrate, comprising:
providing desired device regions with contacts on a front surface of an initial substrate having a back side;
forming via cavities to a depth from the front surface partly through the initial substrate in desired locations;
filling the via cavities with a conductive material coupled to some device region contacts;
mounting the initial substrate with its front surface coupled to a support structure;
thinning the initial substrate from the back side to provide a final substrate that is thinner than the initial substrate and on whose back surface are exposed internal ends of the conductive material filled vias;
applying any desired back-side interconnect region coupled to the one or more exposed ends of the conductive material filled vias; and
removing the support structure and separating individual device or IC assemblies of the final substrate so as to be available for mounting on a further circuit board, tape or larger circuit.
2. The method of claim 1 , further comprising, prior to the filling step, providing one or more refractory liners in the via cavities.
3. The method of claim 2 , wherein the one or more refractory liners comprise a dielectric liner.
4. The method of claim 2 , wherein the one or more refractory liners comprise a barrier layer for inhibiting diffusion of the conductive material into the final substrate.
5. The method of claim 2 , wherein the one or more refractory liners comprise an adhesion layer for attachment of the conductive material to the final substrate in the via cavities.
6. The method of claim 2 , wherein the via cavities have a width w and the one or more refractory liners have a thickness less than about 20% of w.
7. The method of claim 1 , wherein the final substrate has a thickness of about 20 micrometers or less and the back-side interconnect region has a thickness of at least about 30% to 50% of the final substrate thickness.
8. The method of claim 1 , wherein the initial substrate has a first thickness and the final substrate has a second thickness and the second thickness is less than or equal about 20% of the first thickness.
9. The method of claim 8 , wherein the initial substrate has a first thickness and the final substrate has a second thickness and the second thickness is less than or equal about 10% of the first thickness.
10. The method of claim 9 , wherein the initial substrate has a first thickness and the final substrate has a second thickness and the second thickness is less than or equal about 5% of the first thickness.
11. An electronic assembly formed by a process, comprising:
providing an initial substrate having an active device region proximate a first surface thereof;
forming via cavities extending part-way through the initial substrate from the first surface;
filling the via cavities with a conductive material at least partly coupled to some part of the active device region;
mounting the initial substrate on a temporary support structure with the first surface facing the temporary support structure and a rear face of the initial substrate exposed;
removing material from the rear face until a new surface of the initial substrate is exposed, resulting in a thinned substrate, wherein interior ends of the via cavities filled with the conductive material are exposed at the new surface;
providing a further interconnect region on the new surface making contact to at least some of the interior ends of the via cavities filled with the conductive material, resulting in a final substrate;
removing the temporary support structure from the final substrate;
separating individual device or IC assemblies of the final substrate; and
mounting the individual device or IC assemblies on a further circuit board, tape or larger circuit.
12. The device of claim 11 , wherein the thinned substrate has a thickness less than or equal to about 20% of a thickness of the initial substrate.
13. The device of claim 11 , wherein the via cavities have a refractory liner.
14. The device of claim 13 , wherein the refractory liner comprises one or more of an insulating material, a barrier material, or an adhesion material.
15. The device of claim 11 , wherein the further interconnect region has a thickness of 30% to 50% of the thickness of the thinned substrate.
16. A method for forming electronic assemblies, comprising:
providing an initial semiconductor substrate of a first thickness and having a region of active devices proximate a first surface thereof;
forming via cavities extending part-way through the initial semiconductor substrate from the first surface;
filling the via cavities with a conductive metal coupled to some of the active devices;
mounting the initial semiconductor substrate on a temporary support structure with the first surface facing the temporary support structure and a rear face of the initial semiconductor substrate exposed;
removing material from the rear face until a new surface of the initial semiconductor substrate is exposed, wherein interior ends of the metal filled via cavities are exposed at the new surface, and wherein removing the material from the rear face results in a thinned semiconductor substrate of a second thickness and still having the region of active devices proximate the first surface;
providing a further interconnect region on the new surface making contact to some or all of the interior ends of the via cavities filled with the conductive metal, resulting in a final substrate;
removing the temporary support structure from the final substrate;
separating individual device or IC assemblies of the final substrate; and
mounting the individual device or IC assemblies on a further circuit board, tape or larger circuit.
17. The method of claim 16 , further comprising, during or after the providing the initial semiconductor substrate step, forming one or more interconnect levels on the first surface coupling some of the active devices to each other or to locations that can be contacted by part of the conductive metal during the filling step or both.
18. The method of claim 16 , wherein the removing material step removes at least 80% of the first thickness.
19. The method of claim 16 , wherein the further interconnect region has a third thickness at least equal to 30% to 50% of the second thickness.
20. The method of claim 16 , wherein the removing material step comprises chemical-mechanical-polishing.