Method for preparing focus-adjustment data for focusing lens system of optical defect-inspection apparatus, and focus adjustment wafer used in such method
View Patent ↗In a method for preparing focus-adjustment data for a focusing lens system of an optical defect-inspection apparatus, a wafer having a plurality of defects is positioned in place with respect to a focal plane defined by the focusing lens system at a positioning step, and the detects on the wafer are optically and electronically detected at a detecting step. Then, defects having a predetermined size are extracted among the detected defects at extracting step, and a number of the extracted defects is counted as defect-number data. The positioning, detecting, extracting and counting steps are repeated whenever the focus-adjustment wafer is relatively shifted from the focal plane by a predetermined distance, and a defect-number distribution is produced based on the defect-number data thus obtained.
1. A method for preparing focus-adjustment data for a focusing lens system of an optical defect-inspection apparatus, said method comprising:
positioning a wafer having a plurality of defects in place with respect to a focal plane defined by said focusing lens system;
optically and electronically detecting the plurality of defects on said wafer;
extracting a number of defects having a predetermined size among the plurality of defects;
counting the number of defects having the predetermined size as defect-number data;
repeating said positioning, said detecting, said extracting, and said counting whenever said focus-adjustment wafer is relatively shifted from said focal plane by a predetermined distance to be a different focus value;
producing a defect-number distribution based on said defect-number data thus obtained;
calculating a peak value of said defect-number distribution; and
calculating a vertical offset value by comparing said peak value with a peak value of a defect-number distribution obtained in a similar manner to said method in an optical defect-inspection apparatus which is identical to said optical defect-inspection apparatus.
2. A focus-adjustment wafer used in an optical defect-inspection apparatus to carry out a focus-adjustment of a focusing lens system of the optical defect-inspection apparatus, said focus-adjustment wafer comprising:
a wafer substrate comprising a plurality of first chip areas defined thereon; and
a plurality of defects formed on or in each of said first chip areas on said wafer substrate,
wherein said plurality of defects has various sizes falling within a size range,
wherein a distribution of the plurality of defects in said various sizes has at least one maximum value in a middle of said size range, and
wherein each of said defects comprises a pyramid-shaped defect.
3. The focus-adjustment wafer as set forth in claim 2 , wherein said size range is from about 0.05 μm to about 0.5 μm.
4. The focus-adjustment wafer as set forth in claim 2 , wherein said plurality of defects is formed on or in said wafer substrate at a density in a range between several/cm 2 and hundreds/cm 2 .
5. The focus-adjustment wafer as set forth in claim 2 , wherein said pyramid-shaped defect comprises a solid defect on each of said first chip areas.
6. The focus-adjustment wafer as set forth in claim 2 , wherein said pyramid-shaped defect comprises a hollow defect in each of said first chip areas.
7. The focus-adjustment wafer as set forth in claim 2 , further comprising a plurality of patterns formed on or in at least one of said plurality of first chip areas on said wafer substrate.
8. The focus-adjustment wafer as set forth in claim 7 , wherein each of said patterns comprises a rectangular-like parallelepiped pattern.
9. The focus-adjustment wafer as set forth in claim 8 , wherein said rectangular-like parallelepiped pattern comprises a solid pattern on each of said first chip areas.
10. The focus-adjustment wafer as set forth in claim 8 , wherein said rectangular-like parallelepiped pattern comprises a hollow pattern on each of said first chip areas.
11. The focus-adjustment wafer as set forth in claim 2 , further comprising:
said wafer substrate further comprising a plurality of second chip areas defined thereon; and
a plurality of patterns formed on or in each of said second chip areas on said wafer substrate.
12. The focus-adjustment wafer as set forth in claim 11 , wherein said plurality of first chip areas and said plurality of second chip areas are alternately arranged side by side.
13. A focus-adjustment wafer used in an optical defect-inspection apparatus to carry out a focus-adjustment of a focusing lens system of the optical defect-inspection apparatus, said focus-adjustment wafer comprising:
a wafer substrate comprising a plurality of first chip areas and a plurality of second chip areas defined thereon;
a plurality of defects formed on or in each of said first chip areas on said wafer substrate; and
a plurality of patterns formed on or in each of said second chip areas on said wafer substrate,
wherein each of said patterns is configured as a circular column,
wherein the plurality of defects on each of the first chip areas is configured as a cone-shaped defect having a size equivalent to a diameter of said circular column,
wherein said plurality of defects has various sizes falling within a size range,
wherein a distribution of the plurality of defects in said various sizes has at least one maximum value in a middle of said size range;
wherein a portion of said plurality of defects comprises a solid defect,
wherein a remaining portion of said plurality of defects comprises a hollow defect,
wherein a portion of said plurality of patterns comprises a solid pattern, and
wherein a remaining portion of said plurality of patterns comprises a hollow pattern.