A family of slurries useful in modifying exposed surfaces of wafers for semiconductor fabrication are provided along with methods of modifying exposed surfaces of wafers for semiconductor fabrication utilizing such a family of working slurries, and semiconductor wafers. The modified pig model displays one or more phenotypes associated with Alzheimer’s disease. The deep portion of the high voltage isolation trench has a bottom surface and shares a continuous wall surface with the shallow portion that extends from the bottom surface to the principal surface of the substrate.