Stacked semiconductor die assemblies with high efficiency thermal paths and molded underfill
Semiconductor die assemblies having high efficiency thermal paths and molded underfill material. In one embodiment, a semiconductor die assembly comprises a first die and a plurality of second dies. The first die has a first functionality, a lateral region, and a stacking site. The second dies have a different functionality than the first die, and the second dies are in a die stack including a bottom second die mounted to the stacking site of the first die and a top second die defining a top surface of the die stack. A thermal transfer structure is attached to at least the lateral region of the first die and has a cavity in which the second dies are positioned. An underfill material is in the cavity between the second dies and the thermal transfer structure, and the underfill material covers the top surface of the die stack.
1. A method of manufacturing a semiconductor device, comprising:
attaching a thermal transfer frame to an outer region of a first semiconductor die, the first die having a stacking area, the outer region extending laterally in a first direction from the stacking area, the thermal transfer frame having a cavity extending laterally in a second direction generally perpendicular to the first direction, and a die stack of second semiconductor dies mounted on the stacking area of the first semiconductor die is within the cavity of the thermal transfer frame; and
filling the cavity with an underfill material such that the underfill material extends to at least a top surface of the die stack.
2. The method of claim 1 , further comprising disposing an adhesive over at least a portion of the first semiconductor die, wherein attaching the thermal transfer frame to the outer region of the first semiconductor die includes attaching the thermal transfer frame directly to the adhesive.
3. The method of claim 1 wherein filling the cavity with the underfill material includes covering sides of the die stack up to at least the top surface of the die stack.
4. The method of claim 1 , further comprising, after filling the cavity, mounting a conductive lid over the thermal transfer frame, underfill material and die stack.
5. The method of claim 1 wherein the cavity includes an inner side wall spaced laterally apart from sides of the die stack.
6. The method of claim 1 wherein the thermal transfer frame has an upper surface and filling the underfill material comprises placing a mold platen against the upper surface of the frame and injecting the underfill material into the cavity.
7. The method of claim 6 wherein the mold platen includes an inlet positioned over the die stack, and wherein filling the cavity with the underfill material includes flowing the underfill material through the inlet.
8. The method of claim 6 wherein the mold platen is spaced apart from the top surface of the die stack, and wherein the underfill material covers the top surface.
9. A method of manufacturing a semiconductor device, comprising:
attaching a die stack to a first die, the die stack having a top surface and including a plurality of second dies,
disposing a thermal transfer frame over an outer region of the first die and at least partially surrounding the die stack, the first die having a stacking area, the outer region extending laterally in a first direction from the stacking area, the thermal transfer frame having an upper surface at an elevation above the top surface of the die stack, the thermal transfer frame having a cavity extending laterally in a second direction generally perpendicular to the first direction; and
at least partially encapsulating the die stack with an underfill material such that the underfill material extends to at least the top surface of the die stack.
10. The method of claim 9 wherein the cavity surrounds the die stack, and wherein at least partially encapsulating the die stack with the underfill material includes filling the cavity with the underfill material such that an upper surface of the thermal transfer frame is substantially co-planar with a topmost surface of the underfill material.
11. The method of claim 9 wherein the semiconductor device includes a support substrate, the method further comprising disposing an adhesive over the support substrate and surrounding at least a portion of the die stack, wherein disposing the thermal transfer frame to the first die includes attaching the thermal transfer frame directly to the adhesive.
12. The method of claim 9 wherein the thermal transfer frame includes an inner sidewall defining an opening larger than a length the top surface of the die stack, and wherein at least partially encapsulating the die stack with the underfill material includes covering sides of the die stack up to at least the top surface of the die stack.
13. The method of claim 9 , further comprising, after filling the cavity, attaching a conductive lid to one or more of the thermal transfer frame, underfill material and die stack using an adhesive.
14. The method of claim 9 wherein the underfill material extends above the top surface of the die stack.
15. The method of claim 9 wherein the cavity surrounds the die stack, and wherein at least partially encapsulating the die stack with the underfill material includes placing a mold platen against the upper surface of the thermal transfer frame and injecting the underfill material into the cavity through the mold platen.
16. The method of claim 15 wherein the mold platen is spaced apart from the top surface of the die stack, and wherein the underfill material covers the top surface of the die stack.