Laser polishing semiconductor wafer
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsTakeshi Noguchi, Yoshihiro Hirata, Junichi Arima, Eisuke Tanaka, Reiji Tamaki, Masanori Obata
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Abstract
The rough ground rear surface 13b of a semiconductor wafer 11 is mirror-polished by localized irradiation with a focused laser beam 21. The wafer is moved relative to the beam, and the melt puddle formed by the beam thereafter recrystallizes at its trailing edge 24 to leave a mirror smooth rear surface 13c.
Claims5
In the manufacture of semiconductor devices, a method for mirror-polishing the rear surface (13b) of a semiconductor wafer (11) rough ground to a predetermined thickness (Tb) without damaging an electronic component (12) formed on the front surface of the wafer, said mirror-polishing method comprising the steps of:
- (a) disposing the semiconductor wafer in an inert atmosphere,
- (b) preheating the semiconductor wafer to a temperature of 200.degree.-400.degree. C.,
- (c) locally irradiating the rear surface of said semiconductor wafer with an energy beam (21) to form a melt puddle (22) on said surface;
- (d) moving said beam with respect to said wafer to attendantly move the irradiating area and thus the melt puddle over the rear surface of said wafer, and
- (e) recrystallizing the melt puddle at the trailing edge (24) of a liquid-solid interface thereof to leave a smooth and mirror-polished rear wafer surface (13c), wherein
- (f) said semiconductor wafer is maintained preheated in said inert atmosphere during the irradiating, moving and recrystallizing steps.
Dependencies are inferred from the claim text.