Snap Vectors To The Pixel Grid
If you are creating vector objects that require straight edges, make sure that your vectors snap to the pixel grid. Otherwise, you could end up with anti-aliased edges.
To make sure that your pixels snaps to the pixel grid, go to the Preferences Panel (PC: Ctrl K, Mac: Command K). Under the Tools tab, enable “Snap Vector Tools and Transforms to Pixel Grid.”
In Photoshop CS6, this checkbox is found in the General tab.