A planarization apparatus and method that thins and planarizes a substrate by grinding and polishing the rear surface of the substrate with high throughput, and that fabricates a semiconductor substrate with reduced adhered contaminants. A planarization apparatus that houses various mechanism elements in semiconductor substrate loading/unloading stage chamber, a rear-surface polishing stage chamber, and a rear-surface grinding stage chamber. The throughput time of the rear-surface polishing stage that simultaneously polishes two substrates is typically about double the throughput time of the rear-surface grinding stage that grinds one substrate.