Other

Kuroda Precision Industries Ltd.

Super Silicon Crystal Research Institute Corp.

Nobuaki Iguchi

Kohzo Abe

A pair of optical profile measuring systems are located at positions facing to both surfaces of a wafer vertically supported at its edge. A thickness gauge having one or more sensors is located between the optical systems for measuring thickness at several points on the wafer . Each optical system comprises a light emitter for discharging a measuring light beam , a collimator lens for rectifying the light beam into a collimated beam, an optical flat for transmitting the collimated light beam , a light detector receiving the light beams reflected on a surface of the wafer and on a referential plane of the optical flat through the collimator lens and a computer for processing interference fringes which occur between the surface of the wafer and the referential plane of the optical flat . Profiles of main and backside surfaces of the wafer are calculated from interference fringes corresponding to both surfaces of a wafer , and a real shape of the wafer is determined from the profiles in consultation with thickness values measured by the thickness gauge

Optical instrument for measuring shape of wafer

A pair of optical profile measuring systems 10, 20 are provided at positions faced to both sides of a wafer 1 vertically supported at its edge. Each system 10, 20 includes a light emitter 11, 21 for discharging a measuring light beam 12, 22, a collimator lens 14, 24 for rectifying the light beam 12, 22 into a collimated beam, an optical flat 15, 25 for transmitting the collimated light beam 12, 22, a light detector 16, 26 receiving the light beams 12, 22 reflected on a surface of the wafer 1 and on a referential plane of the optical flat 15, 25 through the collimator lens 14, 24 and a computer 17, 27 for processing interference fringes which occur between the surface of the wafer 1 and the referential plane of the optical flat 15, 25. Profiles of main and back surfaces of the wafer as well as its thickness variation are easily measured utilizing light interference fringes corresponding to both sides of a wafer.

Growing community of inventors

Kawasaki, Japan

Nobuaki Iguchi