Batch process fabrication of package-on-package microelectronic assemblies
View Patent ↗A microelectronic assembly can be made by joining first and second subassemblies by electrically conductive masses to connect electrically conductive elements on support elements of each subassembly. A patterned layer of photo-imageable material may overlie a surface of one of the support elements and have openings with cross-sectional dimensions which are constant or monotonically increasing with height from the surface of that support element, where the masses extend through the openings and have dimensions defined thereby. An encapsulation can be formed by flowing an encapsulant into a space between the joined first and second subassemblies.
1. A method of fabricating a microelectronic assembly, comprising:
joining first and second subassemblies to form an assembly, the assembly comprising a first support element and a second support element, the first support element having an outwardly-facing first surface facing a first direction, and the second support element having an outwardly-facing first surface facing a second direction opposite from the first direction, the first support element having electrically conductive first elements at an inwardly-facing second surface thereof, and the second support element having electrically conductive second elements at an inwardly-facing second surface thereof, at least one microelectronic element being mounted overlying the second surface of one of the first and second support elements, a patterned layer of photo-imageable material overlying the second surface of one of the first or second support elements, the patterned layer having openings with cross-sectional dimensions which are constant or increase with height from the surface of the respective support element over which the patterned layer lies, and the assembly further comprising masses of bonding material extending from the first elements through the respective openings and electrically coupled with the respective second elements, the masses having cross-sectional dimensions defined by the cross-sectional dimensions of the respective openings; and
flowing an encapsulant into a space between the first and second subassemblies to form an encapsulation contacting surfaces of at least portions of the masses.
2. The method as claimed in claim 1 , wherein one of:
the assembly comprises first terminals at the first surface of the first support element, and second terminals at the first surface of the second support element, the first terminals being electrically coupled with the second terminals through the first elements, the second elements, and the masses therebetween respectively, or
the assembly includes one of:
first terminals at the first surface of the first support element, the first terminals being electrically coupled with the second elements through the masses therebetween respectively; or
the second terminals at the first surface of the second support element, the second terminals being electrically coupled with the first elements through the masses therebetween respectively.
3. The method as claimed in claim 2 , wherein the microelectronic element has a face facing away from the second support element, and the flowing of the encapsulant forms a first encapsulation in contact with at least one of: the face of the microelectronic element or a second encapsulation formed on the face of the microelectronic element.
4. The method as claimed in claim 3 , wherein the flowing of the encapsulant forms a first encapsulation in contact with a second encapsulation formed on the face of the microelectronic element.
5. The method as claimed in claim 2 , wherein the assembly includes the second terminals but not the first terminals, and the second terminals are electrically coupled with the first elements through the masses therebetween respectively.
6. The method as claimed in claim 2 , wherein the first subassembly further comprises a second microelectronic element mounted to the first surface of the first support element, and a second encapsulation contacting the first surface of the first support element and surfaces of the second microelectronic element, the second microelectronic element being electrically coupled with the second terminals through the first elements and through the masses which are electrically coupled therebetween respectively.
7. The method as claimed in claim 1 , further comprising forming the patterned layer by depositing a first layer of photo-imageable material, and depositing a temporary layer comprising a temporary layer of a photo-imageable material, photolithographically patterning the temporary layer to form apertures, using the patterned temporary layer to pattern the first layer to form the openings in accordance with the apertures in the temporary layer, then filling the openings with the masses, and then removing the temporary layer such that the masses project to heights greater than a height of the first layer above the second surface of the support element over which it lies.
8. The method as claimed in claim 7 , further comprising heating the masses to a reflow temperature prior to the joining of the first and second subassemblies, wherein the heating reflows portions of the masses projecting above the surface of the first layer, the reflowed portions being bulbous.
9. A method of fabricating a microelectronic assembly, comprising:
joining first and second subassemblies to form an assembly, the assembly comprising a first support element and a second support element, the first support element having an outwardly-facing first surface facing a first direction, and the second support element having an outwardly-facing first surface facing a second direction opposite from the first direction, the first support element having electrically conductive first elements at an inwardly-facing second surface thereof, and the second support element having electrically conductive second elements at an inwardly-facing second surface thereof, at least one microelectronic element being mounted overlying the second surface of one of the first and second support elements, a patterned layer of polymeric material overlying the second surface of one of the first or second support elements, the patterned layer having openings with cross-sectional dimensions which are constant or increase with height from the surface of the respective support element over which the patterned layer lies, and the assembly further comprising masses of bonding material extending from the first elements through the respective openings and electrically coupled with the respective second elements, the masses having cross-sectional dimensions defined by the cross-sectional dimensions of the respective openings; and
flowing an encapsulant into a space between the first and second subassemblies to form an encapsulation contacting surfaces of at least portions of the masses.
10. The method as claimed in claim 9 , wherein one of:
the assembly comprises first terminals at the first surface of the first support element, and second terminals at the first surface of the second support element, the first terminals being electrically coupled with the second terminals through the first elements, the second elements, and the masses therebetween respectively, or
the assembly includes one of:
first terminals at the first surface of the first support element, the first terminals being electrically coupled with the second elements through the masses therebetween respectively; or
the second terminals at the first surface of the second support element, the second terminals being electrically coupled with the first elements through the masses therebetween respectively.
11. The method as claimed in claim 10 , wherein the polymeric material is a photoresist material.
12. The method as claimed in claim 10 , wherein the microelectronic element has a face facing away from the second support element, and the flowing of the encapsulant forms a first encapsulation in contact with at least one of: the face of the microelectronic element or a second encapsulation formed on the face of the microelectronic element.
13. The method as claimed in claim 12 , wherein the flowing of the encapsulant forms a first encapsulation in contact with a second encapsulation formed on the face of the microelectronic element.
14. The method as claimed in claim 10 , wherein the assembly includes the second terminals but not the first terminals, and the second terminals are electrically coupled with the first elements through the masses therebetween respectively.
15. The method as claimed in claim 10 , wherein the first subassembly further comprises a second microelectronic element mounted to the first surface of the first support element, and a second encapsulation contacting the first surface of the first support element and surfaces of the second microelectronic element, the second microelectronic element being electrically coupled with the second terminals through the first elements and through the masses which are electrically coupled therebetween respectively.
16. The method as claimed in claim 9 , further comprising forming the patterned layer by depositing a first layer of polymeric material, and depositing a temporary layer comprising a temporary layer of a photo-imageable material, photolithographically patterning the temporary layer to form apertures, using the patterned temporary layer to pattern the first layer to form the openings in accordance with the apertures in the temporary layer, then filling the openings with the masses, and then removing the temporary layer such that the masses project to heights greater than a height of the first layer above the second surface of the support element over which it lies.
17. The method as claimed in claim 16 , further comprising heating the masses to a reflow temperature prior to the joining of the first and second subassemblies, wherein the heating reflows portions of the masses projecting above the surface of the first layer, the reflowed portions being bulbous.