Plasma Enhanced Atomic Layer Deposition of SiN:H Using N₂ and Silane

Abstract

As the nano-electronics industry looks to transition to both three dimensional transistor and interconnect technologies at the < 22 nm node, highly conformal dielectric coatings with precise thickness control are increasingly being demanded. Plasma Enhanced Chemical Vapor Deposition (PECVD) currently fills this role for most applications requiring low temperature processing, but does not always meet step coverage and thickness precision requirements. We present results for a hybrid technique, Plasma Enhanced Atomic Layer Deposition (PEALD), that utilizes typical PECVD process gases and tooling while delivering improved topography coverage and thickness control. Specifically, we show that alternating SiH4 gas / N2 plasma exposures applied in an atomic layer deposition sequence can be used to deposit SiN films in a self limiting fashion.

Characteristics of silicon nitride deposited by very high frequency (162 MHz)-plasma enhanced atomic layer deposition using bis(diethylamino)silane

“…Moreover, the use of nitrogen gas as the reactive gas for silicon nitride PEALD, in order to reduce hydrogen-related problems, is known to present challenges in terms of the depositition of silicon nitride with a high nitrogen content. This is particularly true for the conventional PEALD system, using capacitively coupled plasmas (CCP), given that nitrogen molecules are not easily dissociated, due to their high dissociated energy with a triple bond (24.3 eV) [15][16][17].…”

Hollow Cathode Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride Using Pentachlorodisilane

“…In particular, plasma-enhanced ALD (PEALD) has demonstrated the ability to grow SiN x films at low temperatures (≤400 °C). 10,11 As summarized in our review paper published recently, 7 the silicon precursors investigated for the ALD SiN x process include chlorosilanes (e.g., SiCl 4 , SiH 2 Cl 2 , SiH 3 Cl, Si 2 Cl 6 , and Si 3 Cl 8 ), 8,10,12−37 aminosilanes (e.g., 3DMAS, BTBAS, and DSBAS), 11,35,38−43 silane (SiH 4 ), 44,45 neopentasilane, 46 trisilylamine (TSA). 9,46−49 A high-quality SiN x with an excellent wet etch resistance can be obtained using an N 2 plasma-based ALD process (e.g., DSBAS and N 2 plasma).…”

“…Nevertheless, increasing the number of H atoms in the precursor molecule can possibly increase the hydrogen impurities in the deposited SiN x films because of the incorporation of the less reactive Si−H bonds from the precursors. 44,57 Because of the relatively weak and reactive Si− Si bonds (e.g., the BDE of the Si−Si bond was reported to be 54 kcal/mol), 56 the reactivity of the disilane type of the ALD precursor, HCDS, is higher than the above-mentioned monosilane type of precursors. However, alternative chlorodisilane precursors with higher reactivity than HCDS have not been reported or suggested.…”

“…As summarized in our review paper published recently, the silicon precursors investigated for the ALD SiN x process include chlorosilanes (e.g., SiCl 4 , SiH 2 Cl 2 , SiH 3 Cl, Si 2 Cl 6 , and Si 3 Cl 8 ), ,,− aminosilanes (e.g., 3DMAS, BTBAS, and DSBAS), ,,− silane (SiH 4 ), , neopentasilane, and trisilylamine (TSA). ,− A high-quality SiN x with an excellent wet etch resistance can be obtained using an N 2 plasma-based ALD process (e.g., DSBAS and N 2 plasma) . Unfortunately, in high-aspect-ratio structures, obtaining a high conformality (e.g., ≥95%) that is comparable to a thermal ALD process or an NH 3 plasma-based ALD process remains a big challenge for an N 2 plasma-based ALD process.…”

Plasma-Enhanced Atomic Layer Deposition of SiN–AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid

“…%), which may require a high-temperature post-treatment for its elimination. PEALD of SiN based on silane (SiH 4 ) has also been explored to avoid the Cl contamination issue, but while this has been demonstrated, the reactant volumes and times are excessive and wet etch rate (WER) values are insufficient for process needs. − Recently, PEALD of SiN at low temperatures (<400 °C) exhibiting low WERs (<20 Å/min in 100:1 H 2 O:HF) utilizing trisilylamine, , bis­( tert -butylamino)­silane, and tris­(dimethylamino)­silane (3DMAS) have all been reported. To improve thin film properties (crystallinity, morphology, density, and trap density), rapid thermal annealing (RTA) is commonly used.…”