Wafer bonding method and bonded device structure
In an embodiment, a structure includes: a first device including a first dielectric layer and a first alignment mark in the first dielectric layer, the first alignment mark including a first magnetic cross, the first magnetic cross having a first north pole and a first south pole; and a second device including a second dielectric layer and a second alignment mark in the second dielectric layer, the second alignment mark including a second magnetic cross, the second magnetic cross having a second north pole and a second south pole, the first north pole aligned with the second south pole, the first south pole aligned with the second north pole, the first dielectric layer bonded to the second dielectric layer by dielectric-to-dielectric bonds, the first alignment mark bonded to the second alignment mark by metal-to-metal bonds.
1 . A structure comprising:
a first device comprising a first dielectric layer and a first alignment mark in the first dielectric layer, the first alignment mark comprising a first magnetic cross, the first magnetic cross having a first north pole and a first south pole, the first north pole comprising first adjacent arms of the first magnetic cross, and the first south pole comprising second adjacent arms of the first magnetic cross; and
a second device comprising a second dielectric layer and a second alignment mark in the second dielectric layer, the second alignment mark comprising a second magnetic cross, the second magnetic cross having a second north pole and a second south pole, the first north pole aligned with the second south pole, the first south pole aligned with the second north pole, the first dielectric layer bonded to the second dielectric layer by dielectric-to-dielectric bonds, the first alignment mark bonded to the second alignment mark by metal-to-metal bonds.
2 . The structure of claim 1 , wherein the first alignment mark comprises a first grid of first magnetic crosses, the first magnetic cross being one of the first magnetic crosses, wherein alternating rows of the first magnetic crosses within the first grid are offset.
3 . The structure of claim 2 , wherein the first magnetic crosses comprise first arms, and the first arms of the first magnetic crosses in adjacent rows of the first grid overlap.
4 . The structure of claim 1 , wherein the first device further comprises first bonding pads in the first dielectric layer, the second device further comprises second bonding pads in the second dielectric layer, the first bonding pads are bonded to the second bonding pads by metal-to-metal bonds, and the first bonding pads and the second bonding pads comprise a conductive material that is different from a magnetic material of the first alignment mark and the second alignment mark.
5 . The structure of claim 4 , wherein the magnetic material has a greater resistivity and greater transparency than the conductive material.
6 . The structure of claim 4 , wherein the first alignment mark and the second alignment mark have a stronger magnetization than the first bonding pads and the second bonding pads.
7 . A structure comprising:
a first device comprising a first dielectric layer, a first bonding pad in the first dielectric layer, and a first alignment mark, the first alignment mark comprising a first magnetic cross; and
a second device comprising a second dielectric layer, a second bonding pad in the second dielectric layer, and a second alignment mark, the second alignment mark comprising a second magnetic cross, the first magnetic cross being aligned with the second magnetic cross, the first bonding pad and the second bonding pad comprising a conductive material, the first alignment mark and the second alignment mark comprising a magnetic material, the magnetic material being different from the conductive material, the magnetic material having greater transparency than the conductive material at infrared light, the first dielectric layer bonded to the second dielectric layer by dielectric-to-dielectric bonds, the first bonding pad bonded to the second bonding pad by metal-to-metal bonds.
8 . The structure of claim 7 , wherein the infrared light has a wavelength of light in a range of 0.3 μm to 3 μm.
9 . The structure of claim 7 , wherein the magnetic material has a greater resistivity than the conductive material.
10 . The structure of claim 7 , wherein the magnetic material is cobalt-iron-nickel doped with boron, silicon, or molybdenum.
11 . The structure of claim 7 , wherein the first magnetic cross comprises first arms, the second magnetic cross comprises second arms, the first magnetic cross has a magnetization direction that is at a non-zero angle with the first arms of the first magnetic cross, and the second magnetic cross has a magnetization direction that is at a non-zero angle with the second arms of the second magnetic cross.
12 . The structure of claim 7 , wherein the first magnetic cross comprises four arms that protrude from a central portion, a first pair of adjacent arms of the four arms forms a north pole of the first magnetic cross, and a second pair of adjacent arms of the four arms forms a south pole of the first magnetic cross.
13 . The structure of claim 7 , wherein the first magnetic cross comprises four arms that protrude from a central portion, each arm having a length along a direction radiating from the central portion and a width along a direction perpendicular to the direction radiating from the central portion, the length being greater than the width.
14 . The structure of claim 7 , wherein the first magnetic cross comprises four arms that protrude from a central portion, each arm having a length along a direction radiating from the central portion and a width along a direction perpendicular to the direction radiating from the central portion, the length being less than the width.
15 . The structure of claim 7 , wherein the first device further comprises a semiconductor substrate, an interconnect structure, and conductive vias, wherein the first dielectric layer is over the interconnect structure, the interconnect structure is over the semiconductor substrate, the conductive vias extend into the interconnect structure, and the conductive vias are electrically coupled to metallization patterns of the interconnect structure.
16 . The structure of claim 7 , wherein the first alignment mark is one of a plurality of alignment marks disposed at edges of the first device.
17 . A structure comprising:
a first device comprising a first dielectric layer and a first alignment mark in the first dielectric layer, the first alignment mark comprising a first magnetic cross, the first magnetic cross comprising first arms that protrude from a first central portion, a first pair of adjacent arms of the first arms forming a first north pole of the first magnetic cross, a second pair of adjacent arms of the first arms forming a first south pole of the first magnetic cross, each of the first arms having a first width, each of the first arms having a first length, the first length being different than the first width; and
a second device comprising a second dielectric layer and a second alignment mark in the second dielectric layer, the second alignment mark comprising a second magnetic cross, the second magnetic cross comprising second arms that protrude from a second central portion, a first pair of adjacent arms of the second arms forming a second north pole of the second magnetic cross, a second pair of adjacent arms of the second arms forming a second south pole of the second magnetic cross, the first north pole aligned with the second south pole, the first south pole aligned with the second north pole.
18 . The structure of claim 17 , wherein the first length is greater than the first width.
19 . The structure of claim 17 , wherein the first length is less than the first width.
20 . The structure of claim 17 , wherein the first device further comprises a first bonding pad in the first dielectric layer, the second device further comprises a second bonding pad in the second dielectric layer, the first bonding pad and the second bonding pad comprising a conductive material, the first alignment mark and the second alignment mark comprising a magnetic material, the magnetic material having greater transparency than the conductive material at infrared light.