SiO₂ Atomic Layer Deposition Using Tris(dimethylamino)silane and Hydrogen Peroxide Studied by in Situ Transmission FTIR Spectroscopy

Abstract

The atomic layer deposition (ALD) of silicon dioxide (SiO 2 ) was initially explored using a variety of silicon precursors with H 2 O as the oxidant. The silicon precursors were (N,N-dimethylamino)trimethylsilane) (CH 3 ) 3 SiN(CH 3 ) 2 , vinyltrimethoxysilane CH 2 dCHSi(OCH 3 ) 3 , trivinylmethoxysilane (CH 2 dCH) 3 SiOCH 3 , tetrakis(dimethylamino)silane Si(N(CH 3 ) 2 ) 4 , and tris(dimethylamino)silane (TDMAS) SiH(N(CH 3 ) 2 ) 3 . TDMAS was determined to be the most effective of these precursors. However, additional studies determined that SiH* surface species from TDMAS were difficult to remove using only H 2 O. Subsequent studies utilized TDMAS and H 2 O 2 as the oxidant and explored SiO 2 ALD in the temperature range of 150-550 °C. The exposures required for the TDMAS and H 2 O 2 surface reactions to reach completion were monitored using in situ FTIR spectroscopy. The FTIR vibrational spectra following the TDMAS exposures showed a loss of absorbance for O-H stretching vibrations and a gain of absorbance for C-H x and Si-H stretching vibrations. The FTIR vibrational spectra following the H 2 O 2 exposures displayed a loss of absorbance for C-H x and Si-H stretching vibrations and an increase of absorbance for the O-H stretching vibrations. The SiH* surface species were completely removed only at temperatures >450 °C. The bulk vibrational modes of SiO 2 were observed between 1000-1250 cm -1 and grew progressively with number of TDMAS and H 2 O 2 reaction cycles. Transmission electron microscopy (TEM) was performed after 50 TDMAS and H 2 O 2 reaction cycles on ZrO 2 nanoparticles at temperatures between 150-550 °C. The film thickness determined by TEM at each temperature was used to obtain the SiO 2 ALD growth rate. The growth per cycle varied from 0.8 Å/cycle at 150 °C to 1.8 Å/cycle at 550 °C and was correlated with the removal of the SiH* surface species. SiO 2 ALD using TDMAS and H 2 O 2 should be valuable for SiO 2 ALD at temperatures >450 °C.

Plasma-Assisted ALD for the Conformal Deposition of SiO2: Process, Material and Electronic Properties

“…A reaction involving the breaking of the Si-H bond in the precursor is very unlikely. 24 We propose therefore similar surface chemical reactions during the first ALD half cycle as reported by Burton et al 19 for the SiH(N(CH 3 ) 2 ) 3 precursor which is comparable to the present precursor:…”

“…20 In this respect, the use of precursors with amino ligands has also shown promising results, in particular when combined with H 2 O 2 , O 3 , or O 2 plasma as the oxidant. [21][22][23][24] Very recently, also SiH 4 has been used as Si precursor during plasma-assisted ALD with CO 2 plasma as oxidant. 25 SiO 2 films grown with ALD have been reported to exhibit low carbon content, and a high electrical breakdown field.…”

Impact of Aminosilane Precursor Structure on Silicon Oxides by Atomic Layer Deposition

“…In ALD processes the precursor structure plays a large role in the deposition process and film performance. A wide variety of molecular structures have been assessed ranging from chlorosilanes 4,5 and alkoxysilanes 6 to aminosilanes 7,8 and alkylaminosilanes 9 . Aminosilanes provide breadth of structural variations and may be more desirable than chlorosilanes from safety and operability perspectives.…”

High-reflective coatings for ground and space based applications

“…In order to verify this conclusion an FTIR spectrum of a SiO 2 film coated on silicon was recorded (not shown here). Typical Si-O-Si and Si-OH bonds could be identified, but no organic residuals -indicating a complete oxidation reaction of the precursor material [20,21]. In the FTIR spectrum a broad peak around 3387 cm -1 corresponding to a water absorption band [22] revealed that there is physically absorbed water within the films or pores of the films, respectively.…”