Method and apparatus for removing residual material from an alignment mark of a semiconductor wafer

A method of exposing an alignment mark defined in a first side of a semiconductor wafer, comprising the steps of:

• engaging a second side of said wafer with a wafer chuck;
• positioning said wafer in a chamber having a photochemical reactant gas present therein during said engaging step;
• configuring a light source unit so that laser beams generated by said light source unit are only impinged on a localized portion of said first side of said wafer such that a reactant specie is generated from said photochemical reactant gas;
• impinging said laser beams only on said localized portion of said wafer;
• and
• removing material from said localized portion of said first side of said wafer with said reactant specie so as to expose said alignment mark.

An apparatus for exposing an alignment mark defined in a first side of a semiconductor wafer, comprising:

• a chamber having a photochemical reactant gas present therein;
• a wafer chuck configured to engage said wafer by a second side of said wafer so as to position said wafer within said chamber;
• and
• a light source unit configured such that light beams generated by said light source unit are only impinged on a localized portion of said first side of said wafer when said wafer is positioned within said chamber, wherein (i) said wafer chuck and said wafer are positioned relative to said light source so that said light beams are only impinged on said localized portion of said first side of said wafer and (ii) impingement of said light beams on said first side of said wafer causes a reactant specie to be generated from said photochemical reactant gas so as to remove material from said localized portion of said first side of said wafer thereby exposing said alignment mark.