Multi-Dimensional EMI Shielding for High-Voltage Power Supplies in Lithography Machines

As the core equipment in semiconductor manufacturing, lithography machines' nanoscale lithography accuracy directly determines chip yield. The high-voltage power supply, serving as the power core of lithography machines, faces electromagnetic interference (EMI) as a key bottleneck restricting its performance. In the working environment of lithography machines, high-frequency switching (10kHz-1MHz) of switching tubes in the high-voltage power supply generates conducted and radiated interference. Additionally, electromagnetic pulses formed by high-voltage discharge couple to optical systems and precision transmission components, leading to overlay accuracy deviations exceeding 2nm, which severely affects chip manufacturing quality.
To address this issue, a multi-dimensional EMI shielding system must be established. At the structural level, a high-conductivity copper alloy (conductivity ≥98% IACS) is used to fabricate the shielding enclosure. Beryllium copper conductive gaskets are embedded at the seams, controlling gaps within 0.1mm. Meanwhile, ferrite absorbing materials (initial permeability ≥2000) are attached inside to absorb radiation in the 100MHz-1GHz frequency band. In circuit design, the high-voltage power circuit and control circuit are laid out in separate PCB areas. The control circuit is covered with a grounded shielding layer, adopting a hybrid grounding method of "single-point grounding for low frequencies + multi-point grounding for high frequencies". EMI filters (common-mode inductors 10mH-100mH, differential-mode capacitors 0.1μF-1μF) are configured at the input and output ends. For system-level shielding, electromagnetic isolation barriers are used to achieve spatial isolation between the high-voltage power supply and the optical module of the lithography machine, with an isolation distance ≥30cm.
Testing in accordance with the IEC 61000-6-4 standard shows that after shielding, the radiated disturbance of the power supply is ≤40dBμV/m in the 30MHz-1GHz band, and the conducted disturbance is ≤60dBμV in the 150kHz-30MHz band, meeting the EMC requirements of lithography machines. In practical applications, the lithography overlay accuracy is stabilized within 2nm, and the chip yield is increased by 3%, verifying the effectiveness of the multi-dimensional EMI shielding scheme.