Mechanism Investigation of Temperature Dependent Growth and Etching Process of GeCl4 on SiGe Surface: ab-initio Study

• Main Authors: Park, Ji Young, Kim, Gyeom, Kim, Jin Bum, Lee, Sang-Moon, Kim, Sae-jin, Ko, Hyoungsoo, Lee, Seungmin, Lee, Seung Hun, Jang, Inkook, Kim, Dae Sin
• Format: Conference Proceeding
• Language: English
• Subjects: Ab-initio; Atomic layer deposition; Deposition; Etch; Etching; Germanium; GSM; Precursor; Surface Reaction; Temperature; Temperature dependence; Thermodynamics
• ISSN: 1946-1577
• DOI: 10.1109/SISPAD54002.2021.9592526

Herein, we unveil the deposition and etch mechanism of GeCl 4 on the SiGe surface. At the high temperature, GeCl 4 is dissociated to GeCl 2 and then worked as a deposition source. Thus, the rate determinant step of surface growth is GeCl 4 dissociation, and a novel precursor that quickly dissociates to GeCl2 will be a proper precursor target to Ge growth at the low-temperature process. Otherwise, at the low temperature, GeCl 4 works as an etching gas by reacts with surface Ge/Si atoms and forms Ge_{2} H_{n} {Cl}_{6-n} or GeSiH_{n} Cl_{6-n} (n=2,3) molecules. From the etch mechanism analysis, the first activation energy of Ge desorption is lower, 65.8 (kcal/mol), than GeCl 4 dissociation (101 kcal/mol), but the etched surface has higher energy, -6.7 (kcal/mol), than the Ge doped, -19.2 (kcal/mol). This energy profile successfully explains the experimental observation, deposition at high temperature, etch at low temperatures. Additionally, we figured out that the GeCl 3 intermediate shows the most tightly bind to surface atoms.