Wafer level surface passivation of stackable integrated circuit chips
View Patent ↗An electrically insulative conformal coating is applied at least to the active (front) side and one or more sidewalls of the die during wafer processing. Also, a die has an electrically insulative conformal coating applied to at least the active (front) side and sidewalls. Also, assemblies include a stack of such die, electrically interconnected die-to-die; and assemblies include such a die or a stack of such die, electrically interconnected to underlying circuitry (for example in a substrate or a circuit board).
1. A method for making a passivated semiconductor die, the method comprising
providing a wafer having a front side in which semiconductor chip active regions are formed, the semiconductor chip active regions being bounded by saw streets, the semiconductor chip active regions having interconnect pads arranged in an interconnect margin along an interconnect edge thereof;
cutting the wafer front side on all streets to form grooves to a depth greater than a die thickness;
applying a conformal coating to the front side and the grooves; and
thinning the wafer to the die thickness.
2. A method for making a passivated semiconductor die, the method comprising
providing a wafer having a front side in which semiconductor chip active regions are formed, the semiconductor chip active regions being bounded by saw streets, the semiconductor chip active regions having interconnect pads arranged in an interconnect margin along an interconnect edge thereof;
cutting the wafer front side on streets that are fronted by interconnect margins to a depth greater than a die thickness to form die edges and sidewalls;
cutting the wafer front side on streets that are not fronted by interconnect margins to a depth less than the eventual die thickness to form die edges and a part of die sidewalls;
applying a conformal coating to the front side, the die edges, the sidewalls and the part sidewalls;
thinning the wafer to the die thickness; and
cutting through the wafer on streets that are not fronted by interconnect margins.
3. The method of claim 2 , further comprising, prior to cutting through the wafer on streets that are not fronted by interconnect margins,
cutting openings through the conformal coating between the die.
4. The method of claim 2 , further comprising, prior to cutting through the wafer on streets that are not fronted by interconnect margins, forming openings exposing at least portions of interconnect pads.
5. A method for making a passivated semiconductor die, the method comprising
providing a wafer having a front side in which semiconductor chip active regions are formed, the semiconductor chip active regions being bounded by saw streets, the semiconductor chip active regions having interconnect pads arranged in an interconnect margin along an interconnect edge thereof;
cutting the wafer front side on streets that are fronted by interconnect margins to a depth greater than a die thickness to form die edges and sidewalls;
cutting the wafer front side on streets that are not fronted by interconnect margins to a depth less than the eventual die thickness to form die edges and a part of die sidewalls;
applying a conformal coating to the front side, the die edges, the sidewalls and the part sidewalls;
thinning the wafer to the die thickness;
applying a die attach film to the wafer backside; and
cutting through the wafer on streets that are not fronted by interconnect margins.
6. The method of claim 5 , further comprising, prior to cutting through the wafer on streets that are not fronted by interconnect margins, cutting through the die attach film on streets that are fronted by interconnect margins.
7. The method of claim 6 , further comprising cutting through the die attach film on streets that are not fronted by interconnect margins.
8. The method of claim 7 wherein cutting through the die attach film and cutting through the wafer on streets that are not fronted by interconnect margins are carried out sequentially.
9. The method of claim 6 , further comprising, subsequent to cutting through the wafer on streets that are not fronted by interconnect margins, cutting through the die attach film on streets that are not fronted by interconnect margins.
10. The method of claim 6 wherein cutting through the die attach film and cutting through the wafer on streets that are not fronted by interconnect margins are carried out in a continuous operation.
11. The method of claim 6 wherein cutting through the die attach film and cutting through the wafer on streets that are not fronted by interconnect margins are carried out sequentially.
12. The method of claim 5 , further comprising, prior to cutting through the wafer on streets that are not fronted by interconnect margins, forming openings exposing at least portions of interconnect pads.
13. A method for making a passivated semiconductor die, the method comprising
providing a wafer having a front side in which semiconductor chip active regions are formed, the semiconductor chip active regions being bounded by saw streets, the semiconductor chip active regions having interconnect pads arranged in an interconnect margin along an interconnect edge thereof;
thinning the wafer to a die thickness;
cutting through the wafer on streets that are fronted by interconnect margins to form die edges and sidewalls;
cutting the wafer front side on streets that are not fronted by interconnect margins to a depth less than the die thickness to form die edges and a part of die sidewalls;
applying a conformal coating to the front side, the die edges, the sidewalls and the part sidewalls; and
cutting through the wafer on streets that are not fronted by interconnect margins.
14. The method of claim 13 , further comprising, prior to cutting through the wafer on streets that are not fronted by interconnect margins, forming openings exposing at least portions of interconnect pads.
15. The method of claim 13 , further comprising, prior to cutting through the wafer on streets that are not fronted by interconnect margins, cutting openings through the conformal coating between the die.
16. The method of claim 13 , further comprising, subsequent to thinning the wafer, applying a die attach film to the wafer backside.
17. The method of claim 16 , further comprising cutting through the die attach film on streets that are fronted by interconnect margins.
18. The method of claim 16 , further comprising cutting through the die attach film on streets that are not fronted by interconnect margins.
19. A method for making a passivated semiconductor die, the method comprising
providing a wafer having a front side in which semiconductor chip active regions are formed, the semiconductor chip active regions being bounded by saw streets, the semiconductor chip active regions having interconnect pads arranged in an interconnect margin along an interconnect edge thereof;
thinning the wafer to a die thickness;
cutting through the wafer on streets that are fronted by interconnect margins to form die edges and sidewalls;
applying a conformal coating to the front side, the die edges and the sidewalls; and
cutting through the wafer on streets that are not fronted by interconnect margins.
20. The method of claim 19 , further comprising, prior to applying the conformal coating
cutting the wafer front side on streets that are not fronted by interconnect margins to a depth less than the die thickness to form die edges and a part of die sidewalls;
wherein applying the conformal coating further comprises applying the conformal coating to the part sidewalls.
21. The method of claim 19 , further comprising, prior to cutting through the wafer on streets that are not fronted by interconnect margins, forming openings exposing at least portions of interconnect pads.
22. The method of claim 19 , further comprising, prior to cutting through the wafer on streets that are not fronted by interconnect margins, cutting openings through the conformal coating between the die.
23. The method of claim 19 , further comprising, subsequent to thinning the wafer, applying a die attach film to the wafer backside.
24. The method of claim 23 , further comprising cutting through the die attach film on streets that are fronted by interconnect margins.
25. The method of claim 23 , further comprising cutting through the die attach film on streets that are not fronted by interconnect margins.