Thin-film resistor (TFR) having a TFR element providing a diffusion barrier for underlying TFR heads
A thin-film resistor (TFR) module is formed in an integrated circuit device. The TFR module includes a pair of metal TFR heads (e.g., copper damascene trench structures), a TFR element formed directly on the metal TFR heads to define a conductive path between the pair of TFR heads through the TFR element, and TFR contacts connected to the TFR heads. The TFR heads may be formed in a metal interconnect layer, along with various interconnect elements of the integrated circuit device. The TFR element may be formed by depositing and patterning a TFR element/diffusion barrier layer over the TFR heads and interconnect elements formed in the metal interconnect layer. The TFR element may be formed from a material that also provides a barrier against metal diffusion (e.g., copper diffusion) from each metal TFR head and interconnect element. For example, the TFR element may be formed from tantalum nitride (TaN).
1. A method of forming a TFR module in an integrated circuit structure, the method comprising:
forming a pair of metal TFR heads spaced apart from each other in the integrated circuit structure;
depositing a TFR element/diffusion barrier layer directly on the pair of metal TFR heads;
selectively etching the TFR element/diffusion barrier layer to define a TFR element covering a full top surface of each of the pair of metal TFR heads, the TFR element defining a conductive path between the pair of metal TFR heads through the TFR element, and the TFR element providing a barrier against metal diffusion from the metal TFR heads; and
forming a respective TFR contact connected to each of the pair of metal TFR heads through a respective area of the TFR element.
2. The method of claim 1 , wherein the TFR element/diffusion barrier layer comprises TaN.
3. The method of claim 1 , wherein the TFR element/diffusion barrier layer comprises SiCr, SiCCr, TiN x O y , TiN, TiW, TiW 2 N, or TiZrN.
4. The method of claim 1 , wherein the TFR element:
(a) has a sheet resistance in the range of 200 Ω/square to 2 Ω/square; and
(b) has a temperature coefficient of resistance (TCR) in the range of −100 ppm/° C. to +100 ppm/° C.
5. The method of claim 1 , wherein the pair of metal TFR heads are formed in a common metal interconnect layer.
6. The method of claim 1 , wherein forming TFR contacts connected to each of the pair of metal TFR heads comprises:
forming vias respectively connected to the pair of metal TFR heads; and
forming TFR contacts in a metal layer above the metal TFR heads and connected to the metal TFR heads by the respective vias.
7. The method of claim 1 , wherein the pair of metal TFR heads comprise copper TFR heads.
8. The method of claim 1 , comprising forming the pair of metal TFR heads using a copper damascene process.
9. The method of claim 1 ,
comprising forming a dielectric barrier layer on the TFR element/diffusion barrier layer before etching the TFR element/diffusion barrier layer, such that the dielectric barrier layer is etched along with the TFR element/diffusion barrier layer.
10. The method of claim 1 ,
comprising forming a dielectric barrier layer on the TFR element/diffusion barrier layer after etching the TFR element/diffusion barrier layer.
11. A method of forming an integrated circuit structure, comprising:
forming a plurality of metal structures in a metal layer, the plurality of metal structures defining a pair of metal TFR heads and an interconnect element spaced apart from the pair of metal TFR heads;
depositing a TFR element/diffusion barrier layer on the plurality of metal structures, the TFR element/diffusion barrier layer comprising a material that provides a barrier against metal diffusion;
patterning the TFR element/diffusion barrier layer to define:
(a) a TFR element in contact with the pair of metal TFR heads, the TFR element defining a conductive path between the metal TFR heads through the TFR element; and
(b) an interconnect diffusion barrier region on the interconnect element, the interconnect diffusion barrier region spaced apart from the TFR element; and
forming TFR contacts connected to each of the pair of metal TFR heads.
12. The method of claim 11 , wherein the TFR element/diffusion barrier layer comprises TaN.
13. The method of claim 11 , wherein the TFR element/diffusion barrier layer comprises SiCr, SiCCr, TiN x O y , TiN, TiW, TiW 2 N, or TiZrN.
14. The method of claim 11 , wherein the TFR element:
(a) has a sheet resistance in the range of 200 Ω/square to 2 Ω/square; and
(b) has a temperature coefficient of resistance (TCR) in the range of −100 ppm/° C. to +100 ppm/° C.
15. The method of claim 11 , wherein forming the plurality of metal structures in the metal layer comprises forming a plurality of copper trench elements in a copper interconnect layer.
16. The method of claim 11 , wherein forming the plurality of metal structures in the metal layer comprises forming a plurality of copper damascene structures.
17. The method of claim 11 , comprising forming a dielectric barrier layer on the TFR element/diffusion barrier layer before patterning the TFR element/diffusion barrier layer, such that the dielectric barrier layer is etched along with the TFR element/diffusion barrier layer.
18. The method of claim 11 , comprising forming a dielectric barrier layer on the TFR element/diffusion barrier layer after patterning the TFR element/diffusion barrier layer.