Properties of hafnium oxide films grown by atomic layer deposition from hafnium tetraiodide and oxygen

Abstract

Polycrystalline monoclinic HfO2 films were atomic layer deposited on Si(100) substrates by a nonhydrous carbon-free process of HfI4 and O2. The oxygen to hafnium ratio corresponded to the stoichiometric dioxide within the limits of accuracy of ion beam analysis. A 1.5–2.0 nm thick SiO2 interface layer formed between the HfO2 films and Si substrates. Hysteresis of the capacitance–voltage curves was observed in Al/HfO2/p-Si(100) structures with oxide grown in the substrate temperature range of 570–755 °C. The hysteresis ceased with an increase in O2 pressure. The effective permittivity of the dielectric layers varied between 12 and 16. The breakdown voltages were found to be lower in the case of higher oxygen doses and higher HfO2 deposition temperatures.

Development of an Automated Vapor/Liquid Hybrid Deposition System to Form High-kDielectrics

“…For C and H, the ion intensity was converted to the atomic concentration taking the sensitivity of each element into account. The C concentration seen in Figure 4b is comparable to that reported for HfO 2 films prepared by conventional CVD and ALD, [15][16][17] even though the VALID process was performed at room temperature. The H concentration was more than 10 22 atoms per cm 3 .…”

The Atomic Layer Deposition of HfO2 and ZrO2 using Advanced Metallocene Precursors and H2O as the Oxygen Source

“…Among the most frequently used precursors for HfO 2 and ZrO 2 ALD are ones containing either halide or amido ligands, both of which have the potential to incorporate impurity elements into the film. These precursors present additional problems; halides may cause substrate etching, film defect formation, and possibly impurity element incorporation via the action of hydrogen halide generated during film growth, [17][18][19] whereas amido ligands possess low energy decomposition pathways that could lead to loss of self-limiting growth at modest temperatures. [52] Our precursors contain methylcyclopentadienyl, methyl, and (in the case of (MeCp) 2 Hf(OMe)(Me) and (MeCp) 2 Zr(OMe)(Me)) methoxy ligands, minimizing the number of undesired elements, while avoiding the deleterious effects associated with traditional ligand systems.…”

“…Although some precursors offer such conditions to varying extents, improvement in one or more of these areas for the growth of HfO 2 and ZrO 2 would be a notable advance. To date, a variety of ligand types have been used for the ALD of HfO 2 and ZrO 2 , including some traditional examples such as halides, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] alkylamides, [20][21][22][23][24][25][26][27][28] and alkoxides, [29][30][31][32][33][34][35][36][37][38][39][40] as well as others. [41][42][43] Recent studies, however, have demonstrated the ALD growth of these materials using hafnocene-and zirconocene-based precursors, and the potential viability of the resulting films in device applications.…”

Atomic Layer Deposition of Hafnium Dioxide Films from Hafnium Hydroxylamide and Water

“…In the case of ALD, halide precursors have been used. [11,14] Although these show good self-limiting growth behavior and have given pure oxide films, they are solid sources with high melting points and fine particle sizes, and so there is the risk of particle transport to the substrate. The chemical purity of metal halides can be questionable as they are difficult to purify, and halide contamination is a serious potential problem in microelectronics applications.…”