MULTI-DIE-TO-WAFER HYBRID BONDING
Integrated circuit structures and methods for a high precision die-to-wafer bonding technology for fabricating 3-D stacked IC dies. Embodiments include precise alignment structures and methods, and also provide fast fabrication techniques using simultaneous multi-die picking and placing of individual dies from a die-source wafer onto a recipient wafer. Stacked-die yields are improved over wafer-to-wafer bonding technologies by enabling testing and selection of known-good die-source dies before bonding onto the recipient wafer, and by providing optional physical alignment structures on the recipient wafer and/or die-source wafer. Embodiments enable, for example, fabrication of high-power, high-performance devices on ICs formed on GaAs or GaN die-source wafers and bonding individual die-source IC dies to ICs that include CMOS control and driver circuitry formed on an SOI recipient wafer. The resulting 3-D stacked IC dies may offer advantages that include scalability, reliability, and form-factor reduction.
1 . A method of fabricating 3-D stacked integrated circuit (IC) dies, the method including:
(a) fabricating die-source IC dies on a die-source wafer;
(b) forming conductive vias on a bonding surface of each die-source IC die;
(c) singulating the die-source IC dies;
(d) testing the die-source IC dies before and/or after singulating the die-source IC dies to determine known-good die-source IC dies;
(e) picking known-good die-source IC dies from the singulated dies;
(f) contacting the picked known-good die-source IC dies to corresponding recipient-wafer ICs formed as part of a recipient wafer, thereby bonding the known-good die-source IC dies to the corresponding recipient-wafer ICs on the recipient wafer to form 3-D stacked IC dies; and
(g) forming alignment structures on a bonding surface of the recipient wafer, the alignment structures shaped and positioned to guide placement of the picked known-good die-source IC dies with respect to the corresponding recipient-wafer ICs.
2 . The method of claim 1 , wherein the alignment structures have sloped side surfaces that may be contacted by edges of the picked known-good die-source IC dies.
3 . The method of claim 2 , further including forming the alignment structures in one of: a grid pattern configured to border and contact all sides of the picked known-good die-source IC dies, an edge-engagement pattern configured to contact only part of the edges of the picked known-good die-source IC dies, a corner-engagement pattern configured to contact only the four corners of the picked known-good die-source IC dies, or a sparse corner-engagement pattern configured to contact only two opposite corners of the picked known-good die-source IC dies.
4 . The method of claim 1 , further including forming the alignment structures in a grid pattern configured to border and contact all sides of the picked known-good die-source IC dies.
5 . The method of claim 1 , further including forming the alignment structures in an edge-engagement pattern configured to contact only part of the edges of the picked known-good die-source IC dies.
6 . The method of claim 1 , further including forming the alignment structures in a corner-engagement pattern configured to contact only the four corners of the picked known-good die-source IC dies.
7 . The method of claim 1 , further including forming the alignment structures in a sparse corner-engagement pattern configured to contact only two opposite corners of the picked known-good die-source IC dies.
8 . A 3-D stacked integrated circuit (IC) die including:
(a) a die-source IC die including a bonding surface and conductive vias; and
(b) a recipient-wafer IC die including:
(1) a bonding surface and conductive vias in aligned contact with the bonding surface and conductive vias of the die-source IC die; and
(2) an alignment structure formed on the bonding surface of the recipient-wafer IC die and shaped and positioned to guide placement of the bonding surface and conductive vias of the die-source IC die into bonding engagement with the bonding surface and conductive vias of the recipient-wafer IC die.
9 . The invention of claim 8 , wherein the alignment structure has sloped side surfaces that may be contacted by edges of the die-source IC die.
10 . The invention of claim 9 , wherein the alignment structure is configured as one of: a grid pattern configured to border and contact all sides of the die-source IC die, an edge-engagement pattern configured to contact only part of the edges of the die-source IC die, a corner-engagement pattern configured to contact only the four corners of the die-source IC die, or a sparse corner-engagement pattern configured to contact only two opposite corners of the die-source IC die.
11 . The invention of claim 8 , wherein the alignment structure is configured in a grid pattern configured to border and contact all sides of the die-source IC die.
12 . The invention of claim 8 , wherein the alignment structure is configured in an edge-engagement pattern configured to contact only part of the edges of the die-source IC die.
13 . The invention of claim 8 , wherein the alignment structure is configured in a corner-engagement pattern configured to contact only the four corners of the die-source IC die.
14 . The invention of claim 8 , wherein the alignment structure is configured in a sparse corner-engagement pattern configured to contact only two opposite corners of the die-source IC die.
15 . The invention of claim 8 , wherein the die-source IC die is formed from a compound semiconductor material die-source wafer.
16 . The invention of claim 8 , wherein the die-source IC die is formed from a silicon-based die-source wafer.
17 . The invention of claim 8 , wherein the die-source IC die is formed from a gallium arsenide or gallium nitride die-source wafer.
18 . The invention of claim 8 , wherein the recipient-wafer IC die is formed on a compound semiconductor material recipient wafer.
19 . The invention of claim 8 , wherein recipient-wafer IC die is formed on a silicon-based recipient wafer.
20 . The invention of claim 8 , wherein the recipient-wafer IC die includes CMOS circuits formed on a silicon-on-insulator recipient wafer.