Waferscale electrostatic quadrupole array for multiple ION beam manipulation

Abstract

We report on the first through-wafer silicon-based Electrostatic Quadrupole Array (ESQA) to focus high energy ion beams. This device is a key enabler for a waferbased accelerator architecture that lends itself to orders-ofmagnitude reduction in cost, volume and weight of charged particle accelerators. ESQs are a key building block in developing compact Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) [1]. In a MEQALAC electrostatic forces are used to focus ions, and electrostatic field scaling permits high beam current densities by decreasing the beam aperture size for a given peak electric field set by breakdown limitations. Using multiple parallel beams, each totaling to an area A, can result in higher total beam current compared to a single aperture beam of the same area. Smaller dimensions also allow for higher focusing electric field gradients and therefore higher average beam current density. Here we demonstrate that Deep Reactive Ion Etching (DRIE) micromachined pillar electrodes, electrically isolated by silicon-nitride thin films enable higher performance ESQA with waferscale scalability. The fabricated ESQA are able to hold up to1 kV in air. A 3×3 array of 12 keV argon ion beams are focused in a wafer accelerator unit cell to pave the way for multiple wafer accelerator.

Multi-beam RF Accelerators for Ion Implantation

“…We have recently reported on the development of multi-beam RF accelerators that we assemble from stacks of low cost wafers [5], [6]. We form RF-acceleration structures and electrostatic quadrupole (ESQ) focusing elements on printed circuit board and silicon wafers with 10-cm diameter using standard microfabrication techniques [7]. In this article we report on the use of compact GaN based RF amplifiers to accelerate ions in an array of 3 × 3 beams with energy gains of up to 5.1 kV per RFacceleration unit.…”