Analysis of the boundaries of ZrO₂ and HfO₂ thin films by atomic force microscopy and the combined optical method

Abstract

In this paper an atomic force microscopy analysis of the microrough upper boundaries of ZrO 2 and HfO 2 thin films is presented. Within this analysis the values of the width, root-mean-square value of heights and power spectral density function of these boundaries are determined for ZrO 2 and HfO 2 exhibiting different thicknesses. The thickness dependences of the quantities mentioned are introduced. The values of the thicknesses of the films are evaluated using the combined optical method. This optical method is also used to describe boundary microroughness within the effective medium theory. A discussion of the results concerning the microroughness of the upper boundaries of both the ZrO 2 and HfO 2 thin films is also introduced.

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

“…In the case of Hf(O t Bu) 4 , precursor decomposition prevented self-limiting growth, whilst the Hf(O t Bu) 2 (mmp) 2 and Hf(mmp) 4 complexes suffered from low oxide growth rates at temperatures below 300±325 C, possibly due to the steric shielding of the Hf center by the bulky bidentate [mmp, ±OCMe 2 CH 2 OMe] ligands. [18] At higher growth temperatures, the Hf(O t Bu) 2 (mmp) 2 and Hf(mmp) 4 complexes decomposed, leading to the breakdown of self-limiting growth. Hafnium nitrate, Hf(NO 3 ) 4 , has also been investigated as an ALD source.…”

“…[18] At higher growth temperatures, the Hf(O t Bu) 2 (mmp) 2 and Hf(mmp) 4 complexes decomposed, leading to the breakdown of self-limiting growth. Hafnium nitrate, Hf(NO 3 ) 4 , has also been investigated as an ALD source. [12] It was used at substrate temperatures below 180 C, due to its low thermal stability.…”

“…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. The use of high purity metal alkoxides potentially offers significant process advantages over halide precursors, and a range of Hf alkoxides, including Hf(O t Bu) 4 , [19] Hf(O t Bu) 2 -(mmp) 2 , [20] and Hf(mmp) 4 [21] have been investigated for the ALD of HfO 2 . In the case of Hf(O t Bu) 4 , precursor decomposition prevented self-limiting growth, whilst the Hf(O t Bu) 2 (mmp) 2 and Hf(mmp) 4 complexes suffered from low oxide growth rates at temperatures below 300±325 C, possibly due to the steric shielding of the Hf center by the bulky bidentate [mmp, ±OCMe 2 CH 2 OMe] ligands.…”

“…The use of high purity metal alkoxides potentially offers significant process advantages over halide precursors, and a range of Hf alkoxides, including Hf(O t Bu) 4 , [19] Hf(O t Bu) 2 -(mmp) 2 , [20] and Hf(mmp) 4 [21] have been investigated for the ALD of HfO 2 . In the case of Hf(O t Bu) 4 , precursor decomposition prevented self-limiting growth, whilst the Hf(O t Bu) 2 (mmp) 2 and Hf(mmp) 4 complexes suffered from low oxide growth rates at temperatures below 300±325 C, possibly due to the steric shielding of the Hf center by the bulky bidentate [mmp, ±OCMe 2 CH 2 OMe] ligands. [18] At higher growth temperatures, the Hf(O t Bu) 2 (mmp) 2 and Hf(mmp) 4 complexes decomposed, leading to the breakdown of self-limiting growth.…”

“…[11±14] In the case of CVD, oxygen-containing chemicals such as b-diketonates, [15] hafnium nitrate, [16] hafnium tert-butoxide, [8,9] and mononuclear alkoxide complexes such as Hf(O t Bu) 2 (mmp) 2 , and Hf(mmp) 4 (mmp = 1-methoxy-2-methyl-2-propanolate, OCMe 2 -CH 2 OMe), [10,17,18] can be regarded as the most common class of the metal precursors. In the case of ALD, halide precursors have been used.…”