Bonded structure with enhanced adhesion strength
A first bonding material layer is formed on a first substrate and a second bonding material layer is formed on a second substrate. The first and second bonding material layers include a metal. Ions are implanted into the first and second bonding material layers to induce structural damages in the in the first and second bonding material layers. The first and second substrates are bonded by forming a physical contact between the first and second bonding material layers. The structural damages in the first and second bonding material layers enhance diffusion of materials across the interface between the first and second bonding material layers to form a bonded material layer in which metal grains are present across the bonding interface, thereby providing a high adhesion strength across the first and second substrates.
1. A bonded structure comprising a vertical stack, from bottom to top, of a first substrate, a structurally damaged bonded material layer of a first structurally damaged metallic material layer and a second metallic material layer, and a second substrate, wherein said structurally damaged bonded material layer includes metal grains extending across an interface between said first structurally damaged metallic material layer and said second metallic material layer, wherein said first structurally damaged metallic material layer includes a first metallic composition comprising an ionic species and an elemental metal, and said second metallic material layer includes a second metallic composition comprising an elemental metal, wherein said first metallic composition is different from said second metallic composition.
2. The bonded structure of claim 1 , wherein said first metallic composition is a first alloy including a first elemental metal and a second elemental metal in which an atomic concentration of said first elemental metal is greater than 50%, and said second metallic composition is a second alloy of said first elemental metal and said second elemental metal in which an atomic concentration of said first elemental metal is less than 50%.
3. The bonded structure of claim 2 , wherein said first elemental metal and said second elemental metal are selected from Cu, Ag, Au, Al, W, Ta, and Ti.
4. The bonded structure of claim 1 , wherein said ionic species is selected from Si and Ge.
5. The bonded structure of claim 1 , wherein said ionic species is selected from groups VA, VIA, VIIA, and VIIIA in the Periodic Table of Elements.
6. The bonded structure of claim 1 , further comprising:
at least one first semiconductor device located in said first substrate;
at least one second semiconductor device located in said second substrate; and
a set of conductive structures that conductively connects said at least one first semiconductor device to said at least one second semiconductor device including a conductive via structure extending at least through said structurally damaged bonded material layer.
7. The bonded structure of claim 1 , wherein said first structurally damaged metallic material layer has a first constant thickness and a single contiguous first metallic composition throughout, and said second metallic material layer has a second constant thickness and a single contiguous second metallic composition throughout.
8. The bonded structure of claim 1 , further including at least one first dielectric material portion and at least one second dielectric material portion embedded in said structurally damaged bonded material layer, wherein said at least one first dielectric material portion vertically contacts one of said at least one second dielectric material portion.
9. The bonded structure of claim 1 , wherein said second metallic material layer is structurally damaged.
10. The bonded structure of claim 9 , wherein said second metallic composition further comprises an ionic species.
11. The bonded structure of claim 9 , wherein at least one of said first or second structurally damaged metallic material layers is amorphous.
12. The bonded structure of claim 11 , wherein both said first structurally damaged metallic material layer and said second structurally damaged metallic material layers are amorphous.