Electromagnetic Topology Optimization Design of High-Voltage Power Supply for Lithography Machines

In the semiconductor lithography process, the lithography machine has triple performance requirements for high-voltage power supplies: high precision, low interference, and high stability. Its core function is to provide kilovolt-level or even megavolt-level stable voltage for the optical system and workpiece stage drive module of the lithography machine. The voltage ripple must be controlled at the millivolt level, and the electromagnetic compatibility (EMC) index is directly related to the nanoscale precision of lithography imaging. Even microvolt-level electromagnetic interference coupled to the optical path system may cause deviations in wafer patterns. Therefore, the electromagnetic topology optimization of high-voltage power supplies has become a key design link.
The core logic of electromagnetic topology optimization is to construct a design system from three dimensions: interference source suppression, propagation path blocking, and sensitive component protection. In the stage of topology selection, it is necessary to avoid the defects of traditional hard-switching topologies. Compared with forward and half-bridge topologies, the phase-shifted full-bridge topology reduces switching losses by more than 60% through soft-switching technology, and at the same time alleviates the phenomenon of voltage stress concentration, reducing the generation of high-frequency electromagnetic interference (EMI) from the source. In addition, a modular topology splitting design is adopted to physically isolate the high-voltage generation unit from the control unit, avoiding electromagnetic coupling between control signals and high-voltage circuits, and controlling the noise level of the control terminal within 50μV.
Grounding and shielding design are key implementation links in electromagnetic topology optimization. For the complex current paths inside the high-voltage power supply, a hybrid scheme of star grounding + multi-point grounding is adopted: the high-voltage power circuit uses multi-point grounding to shorten the return path of large currents and reduce common-mode interference caused by ground impedance; the control signal circuit uses an independent star grounding, which is centrally connected to a single-point grounding electrode to avoid the impact of ground loops on weak control signals. In terms of shielding structure, a double-layer composite shielding design is adopted: the inner layer uses permalloy with high magnetic permeability to absorb low-frequency magnetic field interference generated inside the power supply; the outer layer uses red copper with high electrical conductivity to block external high-frequency electric field interference, and the shielding effectiveness can be improved to more than 40dB.
The integrated topology design of the filter network further improves the anti-interference capability. The traditional discrete filtering scheme has the problems of large parasitic parameters and discontinuous filtering frequency bands. By deeply integrating the EMI filter with the high-voltage topology, an LC series differential-mode filter network is designed at the high-voltage input end to suppress differential-mode interference introduced from the power grid side; an RC snubber network is connected in parallel at both ends of the power switch tube to suppress voltage spikes generated during the switching process; a common-mode filter network composed of a common-mode inductor and a ceramic capacitor is used at the control signal input end to block the propagation of common-mode interference. At the same time, an electromagnetic topology model is established using simulation tools to simulate the electromagnetic distribution characteristics under different working conditions, and the filter parameters are iteratively optimized to make the overall EMI radiation value of the power supply comply with the EN 55032 Class B standard.
The electromagnetic topology optimization of the high-voltage power supply for lithography machines is not only a technical means to improve the performance of the power supply itself, but also a core support to ensure the stability of the lithography process. Through the coordinated optimization of topology structure, grounding shielding, and filter network, the balance between high-precision power supply and low electromagnetic interference of the high-voltage power supply can be achieved, providing key impetus for the breakthrough of semiconductor chips towards smaller processes.