Apparatus and method of inspecting the surface of a wafer
View Patent ↗An apparatus for inspecting a surface of a wafer includes an illumination device for illuminating an imaging area of the wafer with at least one broad-band spectrum, and an optical imaging device with a detector for polychromatic imaging of the imaging area of the wafer based on the illumination, wherein the imaging device includes a filter arrangement for selecting a plurality of narrow-band spectra. In addition, a method for inspecting the surface of a wafer, includes the steps of leveling a plurality of narrow-band spectra to a common intensity range, illuminating an imaging area of the wafer with at least one broad-band spectrum, and imaging a plurality of narrow-band spectra from the imaging area based on the illumination.
1. An apparatus for inspecting a surface of a wafer, comprising:
an illumination device for illuminating an imaging area of the wafer with an illumination light beam having at least one broad-band spectrum so as to form an imaging beam; and
an optical imaging device with a detector for polychromatic imaging of the imaging beam corresponding to the imaging area of the wafer, wherein the imaging device includes a filter arrangement disposed in the imaging beam for selecting a plurality of narrow-band spectra, the narrow band spectra including spectra corresponding to the colors red, green and blue of the visible range and each having a spectral width of less than 20 nm, and the detector being a three-chip camera which has sensitivity peaks corresponding to the narrow band spectra.
2. The apparatus as recited in claim 1 , wherein the illumination device has a further filter arrangement which levels an intensity of the spectra.
3. The apparatus as recited in claim 1 , wherein the filter arrangement attenuates the shorter-wave spectra to a greater degree.
4. The apparatus as recited in claim 1 , wherein the illumination device and the imaging device are configured for bright-field imaging.
5. The apparatus as recited in claim 1 , wherein the illumination device comprises three lasers.
6. The apparatus as recited in claim 1 , wherein the narrow-band spectra comprise a spectral width of less than 10 nm.
7. The apparatus as recited in claim 1 , wherein the narrow-band spectra comprise a spectral width of less than 5 nm.
8. The apparatus as recited in claim 1 , wherein the narrow-band spectra comprise a spectral width of less than 1 nm.
9. A method for inspecting the surface of a wafer, comprising:
leveling a plurality of narrow-band spectra to a common intensity range;
illuminating an imaging area of the wafer with an illumination beam of a polychromatic light source having at least one broad-band spectrum so as to form a detection beam;
selecting a plurality of narrow-band spectra from the detection beam with a filter arrangement, the narrow band spectra including spectra corresponding to the colors red, green and blue of the visible range and each having a spectral width of less than 20 nm; and
imaging the plurality of narrow-band spectra with a three-chip camera having sensitivity peaks corresponding to the narrow band spectra.
10. The method as recited in claim 9 , wherein the illuminating includes illuminating the imaging with a plurality of narrow-band spectra at a first angle, and further comprising mirroring the imaging area based on the illumination at an angle by the wafer with respect to the first angle.
11. The method as recited in claim 9 , further comprising performing an equalization step so as to attenuate shorter wavelengths to a greater degree.
12. The method as recited in claim 9 , wherein the imaging is performed in a bright-field mode.
13. The method as recited in claim 9 , wherein ther illumination is performed using three lasers.
14. The method as recited in claim 9 wherein during imaging, sensitivity peaks of the imaging device are overlapped with the spectra of the illumination device.