- Conference Article
- 10.1109/iedm50572.2025.11353721
Improved On-Resistance of Cryogenic LDMOS Devices Utilizing a Field Plate for Scaling Up Trapped Ion Quantum Computers
- Dec 06, 2025
- Mohammad Abu Zahra + 6 more +6
Integrated cryogenic analog multiplexers are essential for scaling up trapped ion quantum computers (TIQC). They require high-voltage devices, such as LDMOS, to operate within the required voltage range of upto ±40 V. However, at cryogenic temperatures, below 40 K, LDMOS devices exhibit a diode-like behavior, leading to nonlinear on-resistance at low V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</inf>. This negatively affects settling time and transfer function linearity of the required analog multiplexers. Previous work on cryogenic LDMOS focused on characterizing and modeling their behavior. This work explores the use of a field plate to improve the on-resistance performance of LDMOS devices at cryogenic temperatures. Our field plate engineered device was fabricated and measured at cryogenic temperatures alongside a baseline device. Our key findings include: 1) a field plate is essential at cryogenic temperatures; 2) it reduces on-resistance by six orders of magnitude at low V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</inf>; 3) it degrades the breakdown voltage; 4) device nonlinear region span decreases to 40 mV compared to the previous threshold of 400 mV. Finally, TCAD-based cryogenic simulations demonstrate that the remaining threshold stems from an energy barrier in the conduction band at STI corners. These results show for the first time that regaining the linear behavior of LDMOS devices’ on-resistance at cryogenic temperatures can be achieved, which is essential to scale up the number of qubits and hence bring quantum computers to commercial use.
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