| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure foreign substances on a wafer by deposited on the surface a fixed no. of silica grains having a grain size variation factor within specified range per unit area to form a calibrating wafer providing nearly the actual contaminated condition. SOLUTION: On the surface of a calibrating wafer a fixed number of silica grains having a grain size variation factor of less than 3% per unit area is deposited with a standard grain dispersion liq. having a concn. of 1×10<4> -1×10<9> grains/ml usually. If this concn. is less than 1×10<4> gramis/ml, it is difficult to form a grain aerosol of 0.5 grains/cm<3> , resulting in a too small number of grains deposited on the substrate surface. If the concn. of this liq. exceeds 1×10<9> grains/ml, the grain aerosol much contains aggregated grains, each composed of two or more combined unit grains, resulting in a difficult control of the no. of deposited grains.
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