No abstract

No abstract

No abstract

This paper presents a 2.4 GHz 20 W 8-channel radio frequency (RF) source module with improved channel output balance. The proposed RF source module is composed of an RF source generation/DC control part, a power amplification part, and a power dividing part. A 2-stage power amplifier (PA) is combined with gallium nitride high-electron-mobility transistors, including a 25 W transistor and 2-way combined 120 W transistors as the drive and main PA, respectively. In addition, a structure was applied to improve the channel output balance compared to that of the previous module, and the differences of the phase and magnitude of the output power between channels are alleviated within 0.35° and 0.18 dB, respectively. A water jacket was implemented under the drive and main PAs for liquid cooling; however, unlike in the previous work, it was designed by optimizing the size of the water jacket and reducing unnecessary materials using a brazing process. The output power at each channel was 43 dBm, and the drain efficiency was more than 50% at 2.4 GHz. The total module size was 244 mm × 247.4 mm × 30 mm, and its volume was reduced by approximately 58.4% compared to that of the previous module.

This paper presents a novel multi-channel type RF source module with solid-state power amplifiers for plasma generators. The proposed module is consisted of a DC control part, RF source generation part, and power amplification part. A 2-stage power amplifier (PA) is combined with a gallium arsenide hetero bipolar transistor (GaAs HBT) as a drive PA and a gallium nitride high electron mobility transistor (GaN HEMT) as a main PA, respectively. By employing 8 channels, the proposed module secures better area coverage on the wafer during semiconductor processes such as chemical vapor deposition (CVD), etching and so on. Additionally, each channel can be maintained at a constant output power because they have a gain factor tunable by a variable gain amplifier (VGA). For that reason, it is possible to have uniform plasma density on the wafer. The operating sequence is controllable by an external DC control port. Moreover, copper–tungsten (CuW) heat spreaders were applied to prevent RF performance degradation from heat generated by the high power amplifier (HPA), and a water jacket was implemented at the bottom of the power amplification part for liquid cooling. Drawing upon the measurement results, the output power at each channel was over 43 dBm (20 W) and the drain efficiency was more than 50% at 2.4 GHz.