| 摘要 |
PURPOSE:To enhance the reliability of a P/W test and to enhance the yield of a product by a method wherein a defective chip is marked and, at the same time, it is recognized whether the chip has been marked surely, and in case the chip has not been marked, it is marked again. CONSTITUTION:A gate circuit 7 is used to irradiate a wafer 6 with a laser 2; a first electric signal M1 with an intensity value P1 of its reflected beam detected by an optical detector 4 is passed in accordance with a keying control signal from a control signal input terminal 11. A comparator 9 is used to radiate a laser beam 3 of the laser 2 toward a bad mark 5 added onto a defective chip out of chips 6a; it compares a second electric signal M2 with an intensity value P2 of its reflected beam detected by the detector 4; it outputs an instruction signal to execute a marking operation again when P1<=P2. A laser marker 1 applies a laser beam 1a onto the corresponding defective chip during an operation of a switching circuit 10, and applies the bad mark 5 again. By this setup, the reliability of a P/W test can be enhanced; the yield of a product can be enhanced. |
