High-temperature electrostatic chuck enabled by BN dielectrics

An electrostatic chuck (ESC) is the preferred wafer-handling apparatus in ion implantation. To establish a proper Johnsen–Rahbek (J–R) chuck force, the resistivity of the dielectric layer between the wafer and electrode needs to be controlled in the range of 109–1013 Ω-cm. In this study, we present the properties of pyrolytic boron nitride (PBN) and the performance of ESCs based on this dielectric material at elevated temperature. A ceramic layer of PBN with hexagonal lattice structure was prepared by chemical vapor deposition with BCl3 and NH3 at a temperature > 1500 °C. PBN presents a resistivity higher than most of commonly used ceramics, which enables J–R function up to 1050 °C. Adding carbon into PBN (C-PBN) achieves a much flatter resistivity slope that is suitable for wide chuck operation from sub-zero to 800 °C. Subsequently, an ESC was constructed through multilayer CVD coating and patterning technologies. Thanks to PBN’s high resistivity and high dielectric strength, electrical breakdown is effectively prevented under intense heat. Typical chucking force of 104 Pa could be established with a voltage of ± 1 kV. As the result of high thermal shock resistance and lower thermal mass, the PBN-based ESC can reach 600 °C at a fast ramping speed of 23 °C/sec without cracking or delamination. Due to the intimate wafer–chuck contact, a consistent wafer thermal profile with good uniformity of 1.1–1.5% was achieved at temperature of 600–800 °C on a 200-mm wafer using single-zone heating. In summary, the dual-functioned PBN ESC achieved high chuck force, high heating power, good thermal uniformity, and fast response, which provided a viable solution to the wafer heating and handling challenges in the SiC ion implantation application.