Bonded assembly containing oxidation barriers and/or adhesion enhancers and methods of forming the same
A method of forming a bonded assembly includes providing a first semiconductor die containing a first substrate, first semiconductor devices, and first bonding pads that are electrically connected to a respective node of the first semiconductor devices, forming a first oxidation barrier layer on physically exposed surfaces of the first bonding pads, providing a second semiconductor die containing a second substrate, second semiconductor devices, and second bonding pads that are electrically connected to a respective node of the second semiconductor devices, and bonding the second bonding pads to the first bonding pads with at least the first oxidation barrier layer located between the respective first and second bonding pads.
1. A method of forming a bonded assembly, comprising:
providing a first semiconductor die comprising a first substrate, first semiconductor devices, and first bonding pads that are electrically connected to a respective node of the first semiconductor devices, located in a first bonding dielectric layer, and comprise physically exposed surfaces located above a horizontal plane including a bottom surface of the first bonding dielectric layer;
forming a first carbon-based oxidation barrier layer on the physically exposed surfaces of the first bonding pads by performing a selective deposition process that selectively deposits a first carbon-based oxidation barrier material that includes carbon at a weight percentage greater than 50% without forming the first carbon-based oxidation barrier layer on physically exposed surfaces of the first bonding dielectric layer;
providing a second semiconductor die comprising a second substrate, second semiconductor devices, and second bonding pads that are electrically connected to a respective node of the second semiconductor devices; and
bonding the second bonding pads to the first bonding pads with at least the first carbon-based oxidation barrier layer located between the respective first and second bonding pads, wherein metal-to-metal bonding occurs between the second bonding pads and the first bonding pads while the first carbon-based oxidation barrier material, or individual atoms or groups of atoms of the carbon-containing material formed by breakage of the first carbon-based oxidation barrier material, diffuse into the first bonding pads and into the second bonding pads during a bonding process and carbon atoms from the first carbon-based oxidation barrier material are distributed in surface regions of the second bonding pads and the first bonding pads.
2. The method of claim 1 , wherein:
the second bonding pads are located within a second bonding dielectric layer.
3. The method of claim 2 , wherein the carbon-based oxidation barrier layer has a thickness in a range from 0.3 nm to 3 nm.
4. The method of claim 3 , wherein the first carbon-based oxidation barrier layer includes a material selected from amorphous carbon, diamond-like carbon, graphene, and carbon nanotubes.
5. The method of claim 4 , wherein:
bonding the second bonding pads to the first bonding pads comprises performing an anneal process in which residual oxygen atoms on, or in, the first bonding pads combine with the first carbon-based oxidation barrier material; and
the first carbon-based oxidation barrier material diffuses into the first bonding pads during the bonding.
6. The method of claim 4 , wherein the first carbon-based oxidation barrier layer is formed by a selective chemical vapor deposition process that nucleates the first carbon-based oxidation barrier material on the physically exposed surfaces of the first bonding pads without nucleating the first carbon-based oxidation barrier material on the physically exposed surfaces of the first bonding dielectric layer.
7. The method of claim 6 , wherein the selective chemical vapor deposition process comprises a process selected from a thermal chemical vapor deposition process or a plasma enhanced chemical vapor deposition process (PECVD).
8. The method of claim 3 , wherein the first carbon-based oxidation barrier layer comprises a monolayer of a first self-assembly material (SAM) including an alkane compound having a first end with affinity to a material of the first bonding pads and without affinity to a material of the first bonding dielectric layer.
9. The method of claim 8 , wherein bonding the second bonding pads to the first bonding pads comprises performing an anneal process in which the first carbon-based oxidation barrier material decomposes.
10. The method of claim 8 , wherein the first carbon-based oxidation barrier layer is formed by a self-assembly process in which the first carbon-based oxidation barrier material is attached to the physically exposed surfaces of the first bonding pads without attachment to the physically exposed surfaces of the first bonding dielectric layer.
11. The method of claim 8 , further comprising selectively forming a second carbon-based oxidation barrier layer comprising a second monolayer of a self-assembly material (SAM) on physically exposed surfaces of the second bonding pads without forming the second carbon-based oxidation barrier material on physically exposed surfaces of the second bonding dielectric layer, wherein the first and second carbon-based oxidation barrier layers bond to each other and function as adhesion layers.
12. The method of claim 2 , wherein:
the first bonding dielectric layer and the second bonding dielectric layer comprise silicon oxide; and
the second bonding dielectric layer is bonded to the first bonding dielectric layer during bonding the second bonding pads to the first bonding pads via oxide-to-oxide bonding.
13. The method of claim 2 , further comprising selectively forming a second carbon-based oxidation barrier layer on physically exposed surfaces of the second bonding pads without forming the second carbon-based oxidation barrier material on physically exposed surfaces of the second bonding dielectric layer,
wherein the second bonding pads are bonded to the first bonding pads with the first carbon-based oxidation barrier layer and the second carbon-based oxidation barrier layer therebetween; and
wherein the second carbon-based oxidation barrier material diffuse into the first bonding pads and the second bonding pads during bonding.
14. The method of claim 1 , wherein each of the first bonding pads and the second bonding pads comprises a metallic material portion consisting essentially of Cu, a copper alloy including copper at an atomic concentration greater than 70%, CoW, CoWP, CoMoP, NiW, or NiWP.
15. The method of claim 1 , wherein:
one of the first semiconductor die and the second semiconductor die comprises a memory die including a three-dimensional array of memory elements; and
another one of the first semiconductor die and the second semiconductor die comprises a logic die including a peripheral circuitry configurated to operate the three-dimensional array of memory elements.
16. The method of claim 1 , wherein the first carbon-based oxidation barrier layer is formed by a coating process in which the first carbon-based oxidation barrier material is chemically bonded to the physically exposed surfaces of the first bonding pads without attachment to the physically exposed surfaces of the first bonding dielectric layer.