TY - JOUR
T1 - New strategies for conformal, superconformal, and ultrasmooth films by low temperature chemical vapor deposition
AU - Abelson, John R.
AU - Girolami, Gregory S.
N1 - Funding Information:
The authors thank the following colleagues for their key roles in generating the present results. In the group of Girolami: Do-Young Kim, Scott Daly, Noel Chang, Luke Davis, Justin Mallek, Tracy Codding, and Sumeng Liu. In the group of Abelson: Jack Sung, Emily Klein, Yu Yang, Navneet Kumar, Sreenivas Jayaraman, Angel Yanguas-Gil, Shaista Babar, Andrew Cloud, Elham Mohimi, Tushar Talukdar, and Zhejun Zhang. Girolami and Abelson particularly acknowledge the National Science Foundation (NSF) for its vital role in supporting the development of this new area of CVD. Abelson constructed a dedicated vacuum system for this work and equipped it with in situ diagnostic tools under Grant No. NSF DMR 0315428. Abelson and Girolami were jointly funded under Grant Nos. DMR 0420768, CHE 0076061, and CHE 0750422; Girolami was supported to develop CVD precursors under Grant Nos. CHE 1112360, CHE 1362931, and CHE 1665191; Abelson was supported to conduct growth studies under Grant Nos. DMR 1005715, DMR 1410209, and CMMI 1825938. They authors acknowledge Intel Corporation and the Semiconductor Research Corporation (SRC) for support of portions of this research under Grant No. 2015-IN-2607 and thank Scott Clendenning and Jeff Bielefeld of Intel Corporation for expert guidance. Materials characterization was carried out in part in the Materials Research Laboratory Central Research Facilities, University of Illinois.
Publisher Copyright:
© 2020 Author(s).
PY - 2020/5/1
Y1 - 2020/5/1
N2 - In the following review, the authors describe how the kinetics of film growth can be controlled in innovative ways to achieve the deposition of conformal, superconformal, area-selective, and ultrasmooth films by lowtemperature CVD. Illustrative experimental data and kinetic models are given for the growth of a variety of materials, including transition metals, metal oxides, and metal diborides. Key results are as follows: (i) For precursors that exhibit site blocking on the growth surface, CVD can afford a high degree of conformal coverage on very high aspect ratio features. (ii) The problem of conformal coverage has been solved analytically and presented as a conformal zone diagram. (iii) "Nonconformal" precursor molecules can be made to afford highly conformal films by adding a suitable neutral molecule to enhance surface site blocking. (iv) An inhibitor that adsorbs strongly to the growth material, but not to the substrate surface, can be used to moderate the size distribution of nuclei such that the film is ultrasmooth at coalescence. (v) An inhibitor that binds preferentially to hydroxyl sites on an oxide surface can be used to completely suppress film nucleation and afford area-selective growth. (vi) Superconformal growth, which affords a V-shaped coating and complete fill of a deep trench, can be achieved using one of three approaches, depending on the precursor chemistry. (vii) The science and technology of CVD can further be expanded by the chemical design of new precursors that have a favorable combination of high partial pressure, suitable reactivity at low substrate temperature, and ligand groups that desorb cleanly.
AB - In the following review, the authors describe how the kinetics of film growth can be controlled in innovative ways to achieve the deposition of conformal, superconformal, area-selective, and ultrasmooth films by lowtemperature CVD. Illustrative experimental data and kinetic models are given for the growth of a variety of materials, including transition metals, metal oxides, and metal diborides. Key results are as follows: (i) For precursors that exhibit site blocking on the growth surface, CVD can afford a high degree of conformal coverage on very high aspect ratio features. (ii) The problem of conformal coverage has been solved analytically and presented as a conformal zone diagram. (iii) "Nonconformal" precursor molecules can be made to afford highly conformal films by adding a suitable neutral molecule to enhance surface site blocking. (iv) An inhibitor that adsorbs strongly to the growth material, but not to the substrate surface, can be used to moderate the size distribution of nuclei such that the film is ultrasmooth at coalescence. (v) An inhibitor that binds preferentially to hydroxyl sites on an oxide surface can be used to completely suppress film nucleation and afford area-selective growth. (vi) Superconformal growth, which affords a V-shaped coating and complete fill of a deep trench, can be achieved using one of three approaches, depending on the precursor chemistry. (vii) The science and technology of CVD can further be expanded by the chemical design of new precursors that have a favorable combination of high partial pressure, suitable reactivity at low substrate temperature, and ligand groups that desorb cleanly.
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U2 - 10.1116/6.0000035
DO - 10.1116/6.0000035
M3 - Review article
AN - SCOPUS:85083333497
SN - 0734-2101
VL - 38
JO - Journal of Vacuum Science and Technology A
JF - Journal of Vacuum Science and Technology A
IS - 3
M1 - 030802
ER -