Thin Film Microstructure
Phase, Texture, Grain Size, Stress
Jordan Valley X-ray diffraction technology (XRD) provides an ideal metrology solution for thin film microstructure applications, including phase, texture, grain size and stress. Jordan Valley’s XRD mode offers many advantages, including:
- Unique information on the microstructure of polycrystalline materials
- Non-contacting, non-destructive
- Single and multiple layers
- Control penetration depth (grazing incidence)
XRD Overview
Metal Barrier Phases: Ta or TaN
Requirement:
- Maintain low resistivity of the barrier layer
- Different Ta and TaN phases have different resistivity: Taα = 35 Ω-cm and Taβ = 175 Ω-cm
In-line Monitor:
- Ratio of Taα and Taβ phases
Taα also promotes growth of (111) texture in Cu
Phase issues with Ta/TaN barriers
PVD Ta Phase & Texture
Barrier properties depend on crystal structure and composition, not just thickness. Phase variations are a known problem in Ta/TaN barriers.
- &alpha-Ta; (bcc) has low ρ so a good barrier choice - β-Ta (tetragonal) is undesired
- This is a root cause of some process problems
- XRD is already adopted at major semiconductor manufacturers
[1] C.C. Wang et al, Proc. Characterisation and Metrology for ULSI Tech. 2003, p.519
[2] D. Edelstein et al, Proc. IITC SF 2001, p.9-11
[3] H. Donohue et al, Proc. IITC, SF 2002 p.179