ECLIPSE: Multiscale Modeling of Crossed-Field Discharges with Speed-Limited Particle-in-Cell Simulation

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This project aims to develop and demonstrate computer simulation techniques for optimizing plasma-based magnetron sputtering. Magnetron sputtering is used to produce thin coatings essential to many important products, including integrated circuits and solar cells. Magnetron sputtering devices coat a substrate material by using energetic ions to knock/sputter atoms off the cathode material and onto the substrate. Improving these devices will lead to more reliable, higher quality coatings, lower production costs, and increased performance - cheaper, faster electronics and more efficient solar panels. The key to improvement is controlling the sputtered atoms, which requires controlling the density, energy, and distribution of ions. Computer simulations enabled by this project will allow investigation of system details that are all but inaccessible via experiment, as well as faster exploration of design changes for clean energy technologies. As such, this project is being supported under the ECosystem for Leading Innovation in Plasma Science and Engineering (ECLIPSE) program.The cathode-bombarding ions are accelerated within a plasma produced by an electric discharge; a magnetic field reduces electron loss to maintain the plasma. The plasma is difficult to model: it is non-equilibrium, partially ionized, moderately collisional, with multiple ion species and plasma-surface interactions in a chamber with complicated geometry. Particle-in-cell (PIC) computer simulation has the power to simulate all these effects. However, the large computational cost poses severe challenges for design optimization, which requires many simulations to explore a wide range of conditions. In this project multiple plasma modeling techniques will be developed and tested to speed-up PIC simulation of magnetron sputtering, including non-uniform grid spacing, energy-conserving PIC algorithms that allow grid cells larger than the plasma Debye length, and the speed-limited PIC algorithm, which reduces the number of time steps needed to complete a simulation. These techniques are expected to be especially effective when used together, and they will be applicable to a wide range of low-temperature plasma simulations beyond magnetron sputtering.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.