Metrology integrated with vacuum processing

A method of wafer characterization, the method comprising:

• directing light through illumination optics and an illumination vacuum window of a vacuum chamber to an optical spot on a wafer placed on a wafer chuck in the vacuum chamber, the illumination optics comprising an illumination corrector lens, the illumination vacuum window being slanted relative to the wafer chuck;
• detecting the light from the optical spot through collection optics and a collection vacuum window of the vacuum chamber, the collection optics comprising a collection corrector lens, the collection vacuum window being slanted relative to the wafer chuck;
• and
• adjusting a relative position of the optical spot on the wafer by rotating the wafer via a wafer stage, moving the optical spot via a transfer module, or a combination thereof, wherein
• the illumination corrector lens and the collection corrector lens are configured to reduce chromatic aberration,
• the wafer stage is positioned below and mechanically coupled to the wafer chuck and configured to rotate the wafer chuck, and
• the transfer module is configured to move the illumination optics and the collection optics parallel to the illumination vacuum window and the collection vacuum window respectively,
• wherein the wafer stage, the illumination optics and the collection optics are outside the vacuum chamber,
• wherein the wafer stage and the wafer chuck are mechanically connected via a journal bearing that extends through a bottom portion of the vacuum chamber with a vacuum seal.