Epitaxial Growth of (001)ZrN Thin Films on (001)Si by Low Temperature Process

Abstract

We have prepared (001)ZrN films epitaxially grown on (001)Si substrates by a low temperature process using an ultrahigh vacuum magnetron sputtering system, and evaluated their epitaxial relationships and film qualities, using X-ray diffraction (XRD) analysis, X-ray pole figure, grazing incidence angle X-ray reflectivity (GIXR), transmission electron microscopy (TEM) and atomic force microscopy (AFM). It is clarified that (001)ZrN films grow epitaxially on (001)Si even at room temperature with the directional relationship of ZrN(001)[110]∥Si(001)[110], and the lattice mismatch at the interface between (001)ZrN and (001)Si is relaxed due to the existence of a very thin transition layer. It is also revealed from GIXR and AFM that the epitaxial ZrN films have a high film density and a flat surface morphology, irrespective of substrate temperature.

Epitaxial growth of (111)ZrN thin films on (111)Si substrate by reactive sputtering and their surface morphologies

“…It was also found that the film resistivities were strongly dependent on the N 2 flow ratio and that the film crystallinities were dependent on P DC and T s . The optimum sputtering conditions obtained were as follows: an N 2 flow ratio of 3% and a P DC of 15 W. Furthermore, it was found that epitaxial growth of high-quality stoichiometric (0 0 1)ZrN films with a resistivity of 17 mO cm comparable to that of bulk ZrN ð13:6 mO cmÞ was achieved on (0 0 1)Si at T s ¼ 500 C under the sputtering conditions described in our recent paper [11]. However, the epitaxial growth of (1 1 1)ZrN films at relatively low temperatures has not yet been reported.…”

“…Sample preparation was carried out after evacuation to less than 3 Â 10 À8 Torr using the same UHV DC magnetron sputtering system as in our previous study [11]. As substrate, n-(1 1 1)Si wafers were used.…”

“…The sputtering gas pressure was kept constant at 2 Â 10 À3 Torr (total gas flow: 10.5 sccm). ZrN films with a thickness of 40 nm were deposited on (1 1 1)Si under the same optimum sputtering conditions of N 2 flow ratio (3%) and sputtering power (15 W) as were used in our previous studies [10,11]. However, T s was varied from RT to 500 C to determine the best epitaxial growth temperature.…”

“…In addition, we have reported that the epitaxial growth of (0 0 1)HfN on (0 0 1)Si and that of (1 1 1)HfN on (1 1 1)Si are possible because the lattice mismatch at the interfaces between the twodimensional superlattice cells of HfN and Si is small even though the misfit between each basic lattice constant is large (17%) [13,14]. Thus, it was expected that (1 1 1)ZrN films could be grown epitaxially on (1 1 1)Si in similar fashion to the (0 0 1)ZrN/(0 0 1)Si system [11].…”

“…In the present study, we investigated whether (1 1 1)ZrN films with a thickness of 40 nm can be grown epitaxially on (1 1 1)Si by a low-temperature sputtering process below 500 C, using the same sputtering system as in our previous paper [11], and assessed the epitaxial relationship and film properties such as film density, interface thickness and surface morphology.…”