Stuart Sherwin Email & Phone Number

Berkeley, Ca

As a Graduate Student Researcher in Electrical Engineering and Computer Science, I am working on Computational Imaging and EUV Lithography, in order to enable manufacturing integrated circuit patterns at sub-10nm resolution. I have worked primarily on projects related to EUV photomasks for designing and measuring the multilayer mirror substrate and absorber. I have conducted experiments at the Advanced Light Source at Lawrence Berkeley National Lab through the Center for X-Ray Optics. Experiments include reflectometry, scatterometry, phase imaging, and full-field microscope metrology using 13.5nm EUV light, to measure the at-wavelength amplitude and phase electromagnetic effects. I have also published an analysis of the feasibility of an etched multilayer EUV phase-shift mask based on rigorous E&M calculation, which could dramatically improve the image quality of resolution-limitted features. Another analysis explored using PyTorch to optimize the reflection function of the multilayer mirror substrate to mitigate mask 3D effects (heuristic optimization was verified by rigorous E&M calculation). Work on metrology of full-field imaging systems is another research direction, where I have contributed to methods of Fourier-domain in-image aberration and wavefront measurement using psuedo-random weak-phase surfaces such as the atomic-scale roughness on an EUV multilayer mirror, or an optical diffuser in index-matching oil.

I worked in the 5D Process Control division for two years developing techniques and software for lithographic overlay control optimization. I wrote software to allow users to minimize overlay error with minimal metrology sampling. I worked on the interaction between spatial modeling, sample plan reduction, and optimal feedback + feedforward control strategies. I also contributed to the PWG-FF (Patterned Wafer Geometry Feed-Forward) project to enable the pre-correction of overlay variation due to the stress and strain wafers undergo during many steps in the semiconductor manufacturing processes.

My work at KLA-Tencor focused on calibration algorithm development and data analysis in Matlab for the Reflected Electron Beam Lithography (REBL) program. I worked extensively on algorithms to measure the magnification and rotation as well as current density, uniformity, and contrast of the electron beam. I also wrote a simplex optimization algorithm with noise control to optimize the contrast and efficiency of an array of microscopic electron optical lenslets. In an effort to understand the effects of small calibration errors on print quality I also created a print simulator, and used it to develop an analytic model. I was also closely involved with print analysis, taking on tasks such as processing SEM images, using simulations to try to understand observed effects, applying theoretical lithographic models to aid in analysis, and designing print experiments. In addition to my work on algorithms, I also worked in the cleanroom on failure analysis of critical CMOS chips used in REBL, including driving the chips to failure in a vacuum chamber followed by optical inspection, as well as thermal imaging with an IR camera.

At Professor Hartmut Haeffner's experimental Physics lab, I contributed to research on ion-trapped quantum computing. I prepared, ran, and analyzed electromagnetic simulations used in designing the experimental RF ion-trap aparatus. I used the Comsol Multiphysics Matlab API to study the impact of including a nano-wire to couple qubits would have on the capacitive coupling between the electrodes used in the experiment to create an electrodynamic potential well for trapping ions.

This summer internship was at the DARPA-funded REBL program to develop an electrol-beam lithography tool for advanced semiconductor manufacturing capable of sub 20-nm resolution, which contained many novel technologies for electron projection optics, precision stages, metrology, and computational image correction. I worked on algroithms to calibrate the electron beam, such as the magnification, rotation, current density, contrast, and uniformity. I also ran numerical lithographic simulations to develop error budgets for calibration of these beam parameters, and compared these simulations to the tool performance as I designed and analyzed lithographic experiments to quantify capabilities of the REBL system.

Goleta, California

I worked at this Atomic Force Microscope (AFM) company for two summers developing their inertial motor system for moving the sample to a new position between scans. The first summer I designed experiments to probe the parameter space, of controling the piezoelectric inertial motor voltage and position. The second summer I worked on testing new geometries and materials for the sample-holder and also vastly improved the controls of the inertial motor system with an open-loop feedback algorithm that used feedback from an optical camera to move the AFM tip to any point the user clicked on the display of the camera’s image.

I worked in Professor Adrian Lee's experimental Physics lab assembling detectors (Bolometers) for a Cosmic Microwave Background experiment. I had many tasks including: attaching metal strain reliefs to Printed Circuit Boards (PCBs) with epoxy; measuring and recording properties of circuit elements; soldering resistors; micro-soldering Striplines to PCBs; wire-bonding inductors to PCBs.

I worked in Professor Chris Palmstrom's Materials Science lab for two Summers. The first Summer I designed and assembled a relay box to protect Molecular Beam Epitaxy (MBE) machines in the event of power, vacuum, or cooling water loss. The second Summer I designed and assembled pneumatic Gate Valve controls for an MBE chamber. I also made a gas manifold to the control gas flow through an annealing furnace.

Phd, Electrical Engineering And Computer Science

Ba, Physics

Activities and Societies: President of Wolf House, Berkeley Student Cooperative (Spring 2011, Spring and Fall 2013)

Ba, Applied Mathematics