AMINOSILANES

Aminosilanes are the best choice as Si source for the deposition of hafnium silicates (HfSiO) and hafnium silicon oxynitrides (HfSiON). [534]

Trisilylamine (SiH3)3N

Trisilylamine (SiH3)3N (TSA) is a highly volatile (315 torr @ 25°C) C-free and Cl-free precursor for Si3N4 and oxynitride with low T capabilities (700- 575°C). It provides extremely clean process (no NH4Cl) with high step coverage capabilities and tunable Si/N ratio. Silicon nitride films exhibit very low H content ( < 4 1021 at/cm3 @600°C). [568]

Trisilylamine (SiH3)3N (TSA) was applied for the CVD deposition of si3N4 layers at 550-800°C.

N,N,N',N'-tetraethylsilanediamine SiH2(NEt2)2

N,N,N',N'-tetraethylsilanediamine SiH2(NEt2)2 (SAM.24) is a newly designed precursor for low temperature ALD of SiO2 and silicate-based high-k films. [568] SAM.24 has been designed and optimized to best fulfills all the requirements of the ideal SiO2 ALD precursor, namely:

- Self limited growth characteristics under a wide temperature range

- High growth per cycle by optimization of ligand steric hindrance

- Low film contamination, even at low T ([C] < 0,3 atomic% @ 250°C)

- High volatility

- Constant film properties and composition over a wide temperature range

(WER change < 10% for films deposited between 200 and 300°C)

- Lower cost (materials) of ownership from a simpler synthesis process than usual aminosilanes[568]

Bis-tert-butylamidosilane SiH2(NHtBu)2

Low temperature Si3N4 LPCVD utilizes bis-tert-butylamidosilane SiH2(NHtBu)2 (BTBAS) at 575-675°C.

Tris(dimethylamido)silane SiH(NMe2)3

Fig. 1H NMR spectrum of SiH(NMe2)3 precursor

Tris(dimethylamido)silane (3DMAS) SiH(NMe2)3 can be used for the deposition of silicates, silicon nitride, high-k dielectric by CVD [Praxair]

Tetrakis(dimethylamido)silane Si(NMe2)4

Fig. TGA curves of different Si amide precursors (SiH(NMe2)4, Si(NMe2)4, Si(NEt2)4)

Tetrakis(dimethylamido)silane Si(NMe2)4 (4DMAS) can be used for the deposition of various silicon containing films, like SiO2 and SiN, and more commonly as a silicon source for mixed oxides in high-k materials, such as Hf-Si-O. 4DMAS can be used both in ALD or MOCVD mode for the deposition of mixed oxide high-k’s. 4DMAS is a colourless liquid that reacts mildly in moist air, and rapidly with water, with the evolution of dimethylamine and silicon oxide/hydroxide formation. 4DMAS is the least reactive and most stable aminosilane, with the highest decomposition and deposition temperature. [568]

 The NMR spectrum of tris-dimethylamido silane SiH(NMe2)3 precursor is presented in Fig.

Tetrakis(diethylamido)silane Si(NEt2)4

Tetrakis(diethylamido)silane Si(NEt2)4 (TDEAS) completely volatilizes at 250°C/ 1atm He, according to TGA [568]

The comparison of TGA curves of different Si precursors is given in Fig. [568]

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