Fast Polarity-Reversal High-Voltage Circuit for Electrostatic Chucks

Next-generation 300 mm plasma tools demand wafer de-chucking and polarity reversal in under 220 ms to support aggressive throughputs while preventing particle generation from residual charge. Fast polarity-reversal circuits therefore switch bipolar electrostatic chucks from +1200 V / –1200 V to the opposite state in <180 ms with peak current >160 A and final voltage matching within ±1.8 V between zones.

The circuit employs two independent resonant converters—one positive, one negative—each capable of 2.5 kV open-circuit voltage, feeding a common low-inductance bus through anti-parallel silicon carbide MOSFET switches. Polarity reversal is executed by simultaneously disabling the active converter and enabling the opposite one with pre-charged output capacitors, achieving zero-voltage crossing in 42–68 µs and full opposite voltage in 138–172 µs total.

Voltage matching between zones uses real-time calibration: during every reversal, electrode currents are integrated and compared; any imbalance >2.8 µC triggers a 12–28 µs compensation pulse from the lagging converter before final settling. Resulting zone-to-zone differential after reversal remains <1.4 V across 28-zone chucks.

Charge recovery exceeds 95 %: energy from the collapsing polarity is captured through synchronous rectification back to the 400 V DC rail, while the rising polarity draws from the same rail, minimizing peak facility demand to <280 W at 22 wpm.

Dielectric absorption compensation uses a learning table updated from the previous 200 wafers: a small opposite-polarity overdrive pulse of 8–22 % amplitude for 28–46 µs counteracts soakage tail, reducing final residual surface potential to <0.42 V measured by on-chuck Kelvin probe.

Arc-free reversal is ensured by pre-reversal resistance test at 180 V: if any zone shows <22 GΩ (indicating conductive particle bridge), the circuit executes a 900 V cleaning pulse train before proceeding with normal reversal.

These fast-reversal circuits routinely achieve complete polarity flip in 158–189 ms with inter-zone matching <1.1 V and residual charge <2.8 nC, enabling end-effector entry speeds >720 mm/s and contributing to total wafer exchange <3.6 s in the most advanced EUV and 3 nm logic etch modules.