Surface Chemistry in the Atomic Layer Deposition of TiN Films from TiCl₄ and Ammonia

Abstract

The surface chemistry of atomic layer depositions (ALD) of titanium nitride films using alternate doses of TiCl4 and NH3 was characterized by using X-ray photoelectron spectroscopy. The nature of the species deposited by each half-reaction was explored first. Evidence was obtained for the partial loss of chlorine atoms and the reduction of the metal during the adsorption of the TiCl4. Subsequent ammonia treatment removes most of the remaining chlorine and leads to the formation of a nitride. Both half-reactions were proven self-limited, stopping after the deposition of submonolayer quantities of the materials. Repeated ALD cycles were shown to lead to the buildup of thick films. However, those films display a Ti3N4 layer on top of the expected TiN. The data suggest that the reduction of the Ti4+ species may therefore occur during the TiCl4, not NH3, dosing step. The incorporation of impurities in the films was also investigated. Chlorine is only deposited on the surface, and in negligible quantities. This Cl appears to originate from readsorption of the HCl byproduct, and could be removed by light sputtering, heating, or further ammonia treatment. Oxygen incorporation, on the other hand, was unavoidable and was determined to possibly come from diffusion from the underlying substrate.

Synthesis of heterogeneous catalysts with well shaped platinum particles to control reaction selectivity

“…The initial catalyst corresponds to a 1.0 wt % load of Pt nanoparticles on a silica xerogel after calcination to 475 K. The similarity of the two images suggests minimal deterioration of the shape of the supported Pt particles upon their exposure to the catalytic conditions. electron energy analyzer with multichannel detection (66). A constant bandpass energy of 100.8 eV was used, corresponding to a spectral resolution of Ϸ2.0 eV.…”

Initial Stage Growth during Plasma‐Enhanced Atomic Layer Deposition of Cobalt

“…So far, analysis techniques such as Rutherford backscattering (RBS), ellipsometry, and X-ray photoelectron spectroscopy (XPS) have been used for the study of initial growth during ALD. [17][18][19][20] Because any single analysis tool for the study of initial growth has limitations, such as thickness resolution and complicated model dependency, complementary techniques would be needed. XRR enables the simultaneous acquirement of various physical properties such as thickness, density, and roughness.…”

Electronic devices fabricated at CMOS backend-compatible temperatures

“…CMOS front-end CMOS back-end (Al) [20] polymer substrates [22] CMOS back-end (Cu) [19] III-V materials [17] c-Si solar cell [18] PMA [24,25] Si 3 N 4 LPCVD thermal oxidation of silicon TiN ALD [26] Si-ND LPCVD [27] Al 2 O 3 ALD [28] SiO 2 TEOS-LPCVD [23] SiO 2 ICPECVD [29] organic electronics [21] a-Si solar cell [18] …”

“…[ [17][18][19][20][21][22][23][24][25][26][27][28][29] The performance advantages provided by the mentioned process steps are demonstrated using electronic devices realized at CMOS backendcompatible temperatures, i.e. temperatures well below 450 °C.…”

“…To prevent this unwanted diffusion into the blocking Al 2 O 3 layer, the wafer was transferred to reactor 2, where a 6-nm thick ALD layer of TiN was deposited in 150 ALD-cycles at 425 °C. The following overall reaction between TiCl 4 (Titaniumchloride) and NH 3 has been considered to take place: 4 3 6 TiCl 8 NH 6 TiN 24 HCl N 2 + → + + (3.4) where ammonia serves as a reducing agent and as a nitrogen source [26,[53][54][55].…”