Abstract
The performance of modern chips is strongly related to the multi-layer interconnect structure that interfaces the semiconductor layer with the outside world. The resulting demand to continuously reduce the k-value of the dielectric in these interconnects creates multiple integration challenges and encourages the search for novel materials. Here we report a strategy for the integration of metal-organic frameworks (MOFs) as gap-filling low-k dielectrics in advanced on-chip interconnects. The method relies on the selective conversion of purpose-grown or native metal-oxide films on the metal interconnect lines into MOFs by exposure to organic linker vapor. The proposed strategy is validated for thin films of the zeolitic imidazolate frameworks ZIF-8 and ZIF-67, formed in 2-methylimidazole vapor from ALD ZnO and native CoOx, respectively. Both materials show a Young’s modulus and dielectric constant comparable to state-of-the-art porous organosilica dielectrics. Moreover, the fast nucleation and volume expansion accompanying the oxide-to-MOF conversion enable uniform growth and gap-filling of narrow trenches, as demonstrated for 45 nm half-pitch fork-fork capacitors.
Highlights
The performance of modern chips is strongly related to the multi-layer interconnect structure that interfaces the semiconductor layer with the outside world
Route B is interesting for Co metallization since cobalt wires may not need a metal diffusion barrier[44] and at the same time form a CoOx precursor skin layer through surface oxidation[43]. In this proof-of-concept study, we focus on Zn(II)based zeolitic imidazolate frameworks (ZIFs)-8 and its isostructural Co(II)-based analogue ZIF-67 to demonstrate the feasibility of Routes A and B, respectively
The crystalline structure and composition of the films were confirmed by GI-X-ray diffraction (XRD) (Fig. 2b) and X-ray photoelectron spectroscopy (XPS) (Supplementary Table 1)
Summary
The performance of modern chips is strongly related to the multi-layer interconnect structure that interfaces the semiconductor layer with the outside world. The proposed strategy is validated for thin films of the zeolitic imidazolate frameworks ZIF-8 and ZIF-67, formed in 2-methylimidazole vapor from ALD ZnO and native CoOx, respectively Both materials show a Young’s modulus and dielectric constant comparable to state-of-the-art porous organosilica dielectrics. The nonzero resistance (R) and capacitance (C) associated with the metal wires and the insulating medium between them induce cross-talk noise, limit the speed of signal propagation, and contribute to the power consumption of a chip[3] Both R and C tend to increase with further interconnect miniaturization, an effect noticeable at wire diameters and spacings below 50 nm. The common challenge shared between these alternative metallization approaches is gap filling the narrow trenches
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