Growth mechanism and continuity of atomic layer deposited TiN films on thermal SiO2

Abstract

In atomic layer deposition (ALD), film thickness control by counting the number of deposition sequences is poor in the initial, nonlinear growth region. We studied the growth of TiN films formed by sequentially controlled reaction of TiCl4 and NH3 on thermal SiO2 during the transient, nonlinear period. Using low-energy ion scattering and Rutherford backscattering spectroscopy analysis, we have found that a three-dimensional growth of islands characterizes the ALD TiN growth on SiO2. Growth at different temperatures (350 °C and 400 °C) affects the extent of the transient region and the rapid closure of the film. At 400 °C, a reduced growth inhibition and an earlier start of three-dimensional growth of islands results in film closure at about 100 cycles, corresponding to a TiN thickness of 24±3 Å. At 350 °C the minimum thickness at which the TiN layer becomes continuous is 34±3 Å, deposited with 150 cycles.

Dielectric Spectroscopic Detection of Early Failures in 3-D Integrated Circuits

“…(1) The silanols can also react with to generate well-defined charge transfer species (as depicted by Equation 2). In fact reactions are essential for metal barrier films to bind to the isolation liner dielectric [27]. Thus, the "hard failed" that persists after extensive annealing could also be silo-metal complexes formed by the condensation of silanols with the tantalum in the barrier layers, as depicted in equation (3) (2) Based on these observations we propose that the early failures involve RF scattering by dangling bonds in the liner oxide (ozone/TEOS film).…”

Integration of Low‐ k Dielectric Films in Damascene Processes

“…However, there are still some problems to be solved before ALD can be successfully applied and integrated into future ultra low-k process fl ows. The starting surface condition plays an important role for the growth behavior during the initial stages of growth [125,131,132]. This is attributed to either a different density of functional, reactive groups on the substrate surface (e.g., -OH versus -NH 2 ligands) or to a different reactivity of these groups with the precursor molecules.…”

“…This is attributed to either a different density of functional, reactive groups on the substrate surface (e.g., -OH versus -NH 2 ligands) or to a different reactivity of these groups with the precursor molecules. If the density of functional groups and/or the reactivity is too low, the nucleation of the ALD fi lm is severely hampered which could result in an island-type growth behavior rather than layer-by-layer growth during the initial cycles of growth [132]. The growth behavior of ALD layers can be studied using Rutherford backscattering spectroscopy (RBS) or X-ray fl uorescence (XRF) [131] by measuring the total number of deposited Ta atoms.…”

“…HF-dip decoration studies have been used to show a good barrier conformality and continuity performance in high-aspect-ratio SiO 2 structures [123,134]. Although the HF-dip test illustrates that the ALD barrier does not show evidence of pinholes on SiO 2 , it does not guarantee pinhole-free growth behavior on a CVD SiOC die- [132]. A less expensive method is time-of-fl ight secondary ion mass spectroscopy (TOF-SIMS) [135].…”

Probing ultrathin film continuity and interface abruptness with x-ray photoelectron spectroscopy and low-energy ion scattering

“…We employ here ex situ angle-resolved XPS and LEISS to examine each layer, and results from AFM will also be presented. In appropriate sections, we will refer to previous work conducted on films deposited by ALD (or similar techniques) and examined via the use of LEISS, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] ARXPS, [24][25][26][27][28] and SIMS. 17 The goal here is to compare and contrast the effectiveness of ex situ analysis of ultrathin films using ARXPS and LEISS to determine thin film uniformity and continuity.…”