CONCENTRATION MEASUREMENT OF INPURITY IN SEMICONDUCTOR

摘要

PURPOSE:To enable the inspection of carbon concentration easily and at a high accuracy by cooling a standard silicon wafer and a silicon wafer to be measured below a specified temperature when the concentration of carbon in the silicon wafer is measured employing infrared rays. CONSTITUTION:A liquid helium is cooled in a cylindrica inner cylinder 1 while an outer cylinder 2 with an upper cylindrical part and a lower square part is made vacuum inside to an extent of 10-3Torr. A standard silicon wafer 5 and a silicon wafer 6 to be measured are retained separately at tips of two supporting bars 8 while both 5 and 6 are cooled below 80 deg.K so that infrared rays irradiate in the direction of the arrow to transmit them. A double transmission window 7 comprising quartz and potassium is formed between the outer cylinder 2 and the outside air to enable the measurement of the standard silicon wafer and the silicon wafer being measured as cooled to a specific temperature from outside. The installation of such a cooling equipment can more than double the measuring accuracy of the carbon concentration by cooling them below 80 deg.K.