A new RTP system concept is proposed and demonstrated. The system uses a vertical cylindrical quartz tube, while the wafer is placed horizontally. Linear halogen lamps are arranged in a hexagonal shape, and the hexagonal-shaped lamp groups are stacked vertically. Each lamp group is controlled independently, allowing a temperature difference within +/- 1.5-degrees-C to be achieved over a 6-in wafer in steady state. Oxidation under optimal power condition results in a 1.37% standard deviation for an average oxide thickness of 110.4 angstrom. The temperature nonuniformity during the transient has been greatly improved by using dynamic control. The convection loss in the system has been evaluated and its radial dependence is found to be smoother in this chamber than in a conventional rectangular chamber. The ray-tracing simulation in three-dimensional space did result in a better comprehension of the optically complex system. The system efficiency has turned out to be lower than in the case of a conventional rectangular chamber. A large portion of the radiation energy is absorbed by the reflectors. There is a strong side heating to the vertical edge of the wafer. Both are due to multiple horizontal reflections of the rays on the reflectors without hitting the wafer. The temperature profiles calculated from the ray-tracing results show an excellent agreement with experiments and confirm the accuracy of the ray-tracing simulation. The main advantages of this new system concept are its excellent temperature uniformity and the good accessibility of the wafer for technological treatments and in situ measurements.