Patent ID: 11946869
Assignee: COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 6:
7. A method for sorting wafers in an as-cut state or in a surface-shaped state, the wafers being made of a semiconductor material, the method comprising:
providing a reference sample made of the same semiconductor material and having a known thermal donor concentration;
measuring with a photoluminescence tool a photoluminescence signal of the reference sample for at least one first photon energy comprised between 0.65 eV and 0.8 eV, the photoluminescence signal of the reference sample exhibiting a first intensity peak in a first photon energy range of 0.65 eV to 0.8 eV;
determining, from the photoluminescence signal of the reference sample, a first experimental relationship between the thermal donor concentration and a first parameter representative of the first intensity peak;
measuring with the photoluminescence tool a photoluminescence signal of each wafer for at least the first photon energy;
determining from the photoluminescence signal of each wafer a specific value of said first parameter;
determining the thermal donor concentration of each wafer from the specific value of said first parameter by using said first experimental relationship;
determining the majority free carrier concentration of each wafer;
calculating a value of the bulk carrier lifetime of each wafer from the thermal donor concentration and the majority free carrier concentration of each wafer;
comparing the value of the bulk carrier lifetime of each wafer to a threshold value; and
excluding the wafer when the value of the bulk carrier lifetime is lower to the threshold value.