Method of adjusting strobe timing and function testing device for semiconductor device

1. A method of adjusting a strobe timing used for a function test wherein a test pattern is input to a semiconductor device, and an output pattern output from the semiconductor device is compared with an expected result pattern at the strobe timing to determine a pass/fail result of the semiconductor device, comprising the steps of:

a first step of setting a default value of the strobe timing;

a second step of comparing the output pattern output from the semiconductor device in response to the test pattern with the expected result pattern at the default value of the strobe timing;

a third step of setting an initial value of the strobe timing different from the default value set in the second step to a minimum value of the strobe timing in a variation range thereof when the output pattern is not matched to the expected result pattern;

a fourth step of comparing the output pattern in response to the test pattern with the expected result pattern at the strobe timing set in the third step, storing the strobe timing when the output pattern is matched to the expected result pattern, and determining whether the strobe timing exceeds a maximum value in the variation range;

a fifth step of increasing the initial value of the strobe timing set in the third step by a specific value when the strobe timing does not exceed the maximum value, and repeating the fourth step until the strobe timing exceeds the maximum value;

a sixth step of setting the default value of the strobe timing for a next test pattern based on the strobe timing stored in the fourth step, and for repeating a process from the second step; and

a seventh step of calculating a new strobe timing according to the minimum value and the maximum value when there is the stored strobe timing so that the new strobe timing is used as the default value for the next test pattern.

2. A function testing apparatus for a semiconductor device, comprising:

test pattern inputting means for inputting a test pattern to the semiconductor device;

expected result pattern outputting means for outputting an expected result pattern corresponding to the test pattern; and

pass/fail determining means for performing a first process of setting a default value of the strobe timing;

a second process of comparing the output pattern output from the semiconductor device in response to the test pattern with the expected result pattern at the default value of the strobe timing;

a third process of setting an initial value of the strobe timing different from the default value set in the second process to a minimum value of the strobe timing in a variation range thereof when the output pattern is not matched to the expected result pattern;

a fourth process of comparing the output pattern in response to the test pattern with the expected result pattern at the strobe timing set in the third process, storing the strobe timing when the output pattern is matched to the expected result pattern, and determining whether the strobe timing exceeds a maximum value in the variation range;

a fifth process of increasing the initial value of the strobe timing set in the third process by a specific value when the strobe timing does not exceed the maximum value, and repeating the fourth process until the strobe timing exceeds the maximum value;

a sixth process of setting the default value of the strobe timing for a next test pattern based on the strobe timing stored in the fourth step, and for repeating a process from the second process; and

a seventh process of calculating a new strobe timing according to the minimum value and the maximum value when there is the stored strobe timing so that the new strobe timing is used as the default value for the next test pattern.