Multilayer MIM capacitor
An improved semiconductor capacitor and method of fabrication is disclosed. A MIM stack, comprising alternating first-type and second-type metal layers (each separated by dielectric) is formed in a deep cavity. The entire stack can be planarized, and then patterned to expose a first area, and selectively etched to recess all first metal layers within the first area. A second selective etch is performed to recess all second metal layers within a second area. The etched recesses can be backfilled with dielectric. Separate electrodes can be formed; a first electrode formed in said first area and contacting all of said second-type metal layers and none of said first-type metal layers, and a second electrode formed in said second area and contacting all of said first-type metal layers and none of said second-type metal layers.
1. A layered structure formed within a cavity comprising:
a plurality of metal layers insulated from each other, said plurality comprising a set of first-type metal layers and a set of second-type metal layers, wherein adjacent pairs of said plurality include a first-type metal layer and a second-type metal layer;
a first electrode contacting each said second-type metal layers and insulated from each said first-type metal layers; and
a second electrode contacting each said first-type metal layers and insulated from each said second-type metal layers.
2. The structure of claim 1 wherein said plurality of metal layers includes a stack of metal layers having at least three metal layers and further comprising a dielectric layer separating said stack from the surface of said cavity.
3. The structure of claim 1 wherein either said set of first-type metal layers or said set of second-type metal layers comprises TiN and the other set comprises TaSiN, wherein the set of metal layers comprising TiN can be selectively etched by a first etch chemistry and the other set of metal layers comprising TaSiN can be etched by a second etch chemistry distinct from the first etch chemistry.
4. The structure of claim 1 , wherein said cavity has a substantially circular cross section.
5. The structure of claim 1 , wherein each of the first-type metal layer and the second-type metal layer is separated by a dielectric layer, and wherein each dielectric layer is formed of the same dielectric material.
6. The structure of claim 1 , wherein each adjacent pair of the first-type metal layer and the second-type metal layer is insulated from one another by a layer comprising high-K dielectric material selected from the group consisting of aluminum oxide, zirconium silicate, hafnium oxide, hafnium silicate, and zirconium oxide.
7. The structure of claim 1 , wherein the thickness of at least one of the first-type metal layer or the second-type metal layer is in the range of 50A and 200A.
8. The structure of claim 6 , wherein the high-K dielectric layer has a thickness in the range of about 15A to about 50A.
9. The structure of claim 1 , further comprising:
a dielectric material separating and insulating the first electrode from each said first-type metal layers and separating and insulating the second electrode from each said second-type metal layers.
10. The structure of claim 9 , wherein the cavity has a substantially circular cross-section, the structure further comprising a final dielectric layer filling the cavity and contacting an innermost first-type metal layer, wherein the first electrode contacts the final dielectric layer and the second-type metal layers, and wherein the second electrode contacts the final dielectric layer and the first-type metal layers.
11. A layered structure formed within a cavity comprising:
a plurality of metal layers insulated from each other, said plurality comprising a set of first-type metal layers and a set of second-type metal layers, wherein adjacent pairs of said plurality include a first-type metal layer and a second-type metal layer,
wherein relative to said second-type metal layers said first-type metal layers can be selectively etched by a first etch chemistry, and relative to said first-type metal layers said second-type metal layers can be selectively etched by a second etch chemistry;
a first electrode contacting each said second-type metal layers and insulated from each said first-type metal layers; and
a second electrode contacting each said first-type metal layers and insulated from each said second-type metal layers.