Abstract
Ta-N (10 nm)/Zr (20 nm) film was grown on n-type (100) silicon wafer at various substrate temperatures in a rf magnetron sputtering system, followed by in situ deposition of Cu. The Cu/Ta-N/Zr/Si samples were subjected to thermal annealing up to 800 ℃ under the protection of pure nitrogen gas. In order to investigate the effect of insertion of a thin Zr layer under Ta-N film on Ta-N diffusion barrier performance in Cu metallization, Cu/Ta-N/Zr/Si contact system was characterized by X-ray diffraction (XRD), four-point probe (FPP) measurement, scanning electron microscopy (SEM), and Auger electron spectroscopy (AES) depth profile. The results reveal that the microstructure of Ta-N films deposited on Zr is amorphous at different substrate temperatures. The barrier breakdown temperature of Ta-N/Zr film is about 100°C higher than that of Ta-N. It can effectively prevent the diffusion of Cu after annealed at 800°C. The improvement of diffusion barrier performance may be due to the production of Zr-Si layer with low contact resistivity after annealed at 800°C.
Highlights
Copper metallization has become very popular in the Si industry
3.1 Microstructure of Ta-N/Zr films Fig.1 shows the X-ray diffraction (XRD) pattern for the Ta-N(10 nm)/Zr(20 nm) films deposited at different substrate temperatures
There are only obvious Zr diffraction peaks in the XRD spectrum for the Ta-N(10 nm)/Zr(20 nm) films deposited with different temperatures
Summary
Copper metallization has become very popular in the Si industry. Cu possesses significant advantages over Al in terms of RC delay and electromigration [1, 2]. The sheet resistance was measured by 4-point probe (FPP) for the as-deposited and annealed films. 3.1 Microstructure of Ta-N/Zr films Fig.1 shows the XRD pattern for the Ta-N(10 nm)/Zr(20 nm) films deposited at different substrate temperatures.
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