Computational Fluid Dynamic Analysis of a High-Pressure Spatial Chemical Vapor Deposition (HPS-CVD) Reactor for Flow Stability

Abstract

High indium-content group-III nitrides are of interest to further expand upon our ability to produce highly efficient optical emitters at longer visible/IR wavelengths or to broaden bandgap engineering opportunities in the group-III nitride material system. Current synthesis approaches are limited in their capabilities, in part due to the low decomposition temperature of indium nitride. A new high-pressure spatial chemical vapor deposition (HPS-CVD) has been proposed which can operate at pressures up to 100 atmospheres, thereby significantly raising the growth temperature of indium nitride more than 100 kelvins and permitting the investigation of the impact of pressure on precursor stability and reactivity. This study systematically analyzes an HPS-CVD reactor design using computational fluid dynamic modeling in order to understand favorable operating conditions for growth of group III nitrides. Specifically, the relationship between inlet gas type (nitrogen, hydrogen, or ammonia), inlet gas velocity, gas flow rate, and rotational speed of the wafer carrier is evaluated for conditions under which a smooth and dominant vortex-free flow are obtained over the wafer. Heater power was varied to maintain a wafer temperature of 1250–1300 K. Favorable operating conditions were identified that were simultaneously met for all three gas types, providing a stable operating window for a wide range of gas chemistries for growth; at one atmosphere, a disk rotational speed of 50 rpm and a flow rate of 12 slm for all gas types is desired.

Numerical Analysis of a High-Pressure Spatial Chemical Vapor Deposition (HPS-CVD) Reactor for Flow Stability at High Pressures

“…This article is a continuation of the previous study discussed in [46], wherein the authors investigate the flow patterns of ammonia, hydrogen, and nitrogen in a vertical MOCVD reactor. The objectives of this study for operating pressures greater than 1 atm up to 30 atm are (i) to identify smooth flow regimes inside the reactor chambers by selecting appropriate rotational speeds and inlet velocity values while maintaining the wafer temperature within the range of 1200-1300 K and (ii) to define an operating condition matrix (rotational speed (rpm) vs. inlet flow velocity) to provide a basis for future experimental studies.…”

“…This study focuses on a vertical HPS-CVD reactor equipped with a rotating wafer carrier disk, as illustrated in Figure 1a in [46]. The design of this reactor minimizes the prereactions of the precursors and mitigates their interaction to the period of diffusion through the boundary layer.…”

“…The reactor is composed of various components including a shroud, six chambers, and a wafer carrier disk that accommodates multiple wafers, heaters, insulated zones, susceptors, a disk, and a shaft (refer to Figure 1b,c in [46]). The reactor has six independent precursor zones separated by barriers and a mixing layer where deposition occurs.…”

“…As the reactor used in this study is identical to the one presented in [46], details regarding the dimensions and other geometrical features of the reactor can be found there. The working fluid (nitrogen/hydrogen/ammonia) is considered Newtonian, compressible, and to have temperature-dependent properties.…”

“…This paper discusses the design and CFD-based optimization of a new super-atmospheric, vertical MOCVD reactor with spatially separated precursor zones, referred to as a highpressure spatial CVD (HPS-CVD) reactor. The current authors reported on a systematic study of this reactor in a publication analyzing the performance of this reactor at one atmospheric pressure [46]. They explored the effects of the inlet velocity, inlet chamber area, rotational speed of the susceptor, and turbulent model on the flow behavior within the chamber.…”