Solid-state pulsed power module (SSPPM) design for a dense plasma focus (DPF) device for semiconductor lithography applications

摘要

A Dense Plasma Focus (DPF) is being developed at CYMER as a light source for Extreme Ultraviolet (EUV) Lithography applications. The paper describes the Solid State Pulsed Power Module (SSPPM) for driving this device and the application specific requirements for this power system. Based on the same technology used to power CYMER excimer lasers, the SSPPM employs IGBT switching and magnetic pulse compression to generate the pulse delivered to the DPF. The current design generates a 4 kV, ～30 ns risetime pulse. Two separate charging systems have been used to date. A simple resistive charger allows continuous operation at rep-rates up to 40 Hz while a resonant charging system currently provides burst mode operation with rep-rates of at least 1 kHz. Although relatively small in stored energy compared to many previous DPF machines (the initial capacitor stores 18 3), this system must run at very high rep-rates of at least 5 kHz. High rep-rate operation and tight control of the output radiation (<2% 3σ pulse-to-pulse energy repeatability of in-band radiation) are required in order to provide the tight exposure dose control required for semiconductor lithography. This further translates into the requirement for even tighter control and adjustment of the amplitude of the SSPPM output pulse in order to try and maintain a constant radiation output level. Energy recovery is implemented in the SSPPM to recover pulse reflections from the DPF which would normally be dissipated within the DPF and SSPPM as excess heat, lowering the thermal management requirements and reducing the charging system output. Test data from the current generation system are presented along with a discussion of the plans for further evolution of the design towards the final application goals of 5 kHz continuous operation.