Comparison of TiN and TiAlN as a diffusion barrier deposited by atomic layer deposition method

Abstract

Atomic Layer Deposited TiN and TiAlN films were produced on p-type (100)

Si substrate by metal organic sources like tetrakis(ethylmethylamido)titanium

(TEMAT) and DMAH-EPP with ammonia (NH3). ALD method has a lot of

advantages over other CVD processes and these are excellent thickness

uniformity, conformal step coverage, very low pinhole density, and complete

elimination of particle generation. Ti source, Al source and reactant gas were

separately supplied and Ar purge gas was added between each source and

reactant supply to suppress the direct reaction between sources and reactant.

The films were grown at process pressures about 2 Torr and temperatures

between 150-300 C. Our primary goal was to evaluate how TiN and TiAlN

process can be achieved by atomic layer deposition mechanism. The growth

rate of ALD TiN and TiAlN was measured and it was affected by source volume.

Film composition and chemical states were determined, using Auger electron

spectroscopy (AES). The crystallinity was measured by X-ray diffraction. The

interface structure and thin film structure was observed by transmission

electron microscope. Growth temperature affected film composition and the

chemical states of C, N, Al and Ti. Excellent bottom coverage could be

achieved. This excellent bottom coverage could be explained by the fact that

the TiN deposition was completely surface controlled reaction. We compared

these TiN thin film data with other deposition method, such as PECVD, LPCVD

and MOCVD. The TiN film growing method based on the thermodynamic

consideration will be discussed and atomic size computer modeling will be

studied.