Characterization of Low-Temperature Silicon Nitride LPCVD from Bis(tertiary-butylamino)silane and Ammonia

Abstract

Low pressure chemical vapor deposition ͑LPCVD͒ of silicon nitride from bis͑tertiary-butylamino͒silane ͑BTBAS͒ and ammonia precursors has been demonstrated at 550-600°C in a 200 mm vertical batch furnace system. Deposition rates of 4-30 Å/min are achieved with a film thickness variation below 2% 1-sigma. Silicon nitride depositions using BTBAS and NH 3 were found to retain a significant mass-transfer limiting component at temperatures Ͻ600°C. Substantial carbon and hydrogen incorporation are detected in low-temperature BTBAS silicon nitride, relative to dichlorosilane based silicon nitride deposited at higher temperature. These impurities result in the formation of a SiNCH solid solution with carbon substitution of nitrogen and disproportionate occupation of silicon and nitrogen sites by interstitial hydrogen. Optical and physical properties of silicon nitride are significantly altered by the addition of carbon and hydrogen impurities. Etch resistance of BTBAS-derived silicon nitride was found to diminish at elevated hydrogen levels. However, increasing etch resistance is observed in silicon nitride films with higher carbon levels. The data from this study indicate that carbon and hydrogen impurity concentrations may be tuned to produce silicon nitride with specific material properties.

In Situ Infrared Absorption Study of Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride

“…Silicon nitride (Si 3 N 4 ) thin films are important for applications in microelectronics such as dielectric layers in complementary metal oxide semiconductor devices, − gate spacers, ,− and diffusion barriers. − In particular, deposition of conformal thin films at low temperatures (<300 °C) is necessary for nanopatterned, three-dimensional substrates developed to satisfy scaling requirements. , Atomic layer deposition (ALD) has emerged as one of the best methods to achieve Si 3 N 4 deposition with adequate thickness control, conformality for highly patterned substrates, and chemical specificity. − A number of precursors have been developed for the growth of Si 3 N 4 for both thermal and plasma-enhanced processes. ,,− Among them, aminosilanes are particularly attractive because, unlike chlorosilanes, they generate noncorrosive halogenated products. ,, However, thermal processes with chlorosilanes or aminosilanes and either ammonia (NH 3 ) or hydrazine (N 2 H 4 ) require temperatures above 300 °C, which is not acceptable for several applications. ,,,,− Therefore, efforts have turned to plasma-enhanced processes that allow for low-temperature growth. ,,,,, For example, Knoops et al developed a plasma-enhanced atomic layer deposition (PEALD) process using bis­( t -butylamino)­silane (BTBAS) as a precursor and nitrogen plasma as a coreactant and demonstrated a large temperature window that allowed tunability of the film composition/properties by varying the growth conditions. , Although PEALD silicon nitride growth from aminosilane precursors shows great promise, the underlying reaction mechanisms and relationships between growth conditions and film composition must be understood to develop reliable industrial processes. , Some theoretical attempts have been made to underst...…”

An innovative GC-MS, NMR and ESR combined, gas-phase investigation during chemical vapor deposition of silicon oxynitrides films from tris(dimethylsilyl)amine

“…13 Contrary to HMDSz, upon addition of Si-H bonds in the precursor molecule, deposition temperatures can be effectively decreased, as illustrated through the bis(tertiary-butylamino)silane (BTBAS) precursor, which contains two Si-H bonds and allows the deposition of SiNx at 600-675°C, 15 with temperatures down to 550°C also being reported. 16 The presence of additional Si-H bonds is thus expected to decrease the minimum deposition temperature even further.…”

Role of Surface Termination in Atomic Layer Deposition of Silicon Nitride

“…The spacer thickness should be uniform, conformal and pitch-independent. Moreover, the deposition process should use a low temperature, should have a sufficiently high throughput, and should preferably be chlorine-free for some applications. − The latter seems to be vital when using III–V channel materials in upcoming technology nodes. Currently, there exist no deposition processes for SiN x that satisfy all the above requirements.…”