Test apparatus and test method for testing a device based on quiescent current

1. A test apparatus that tests a device under test, comprising:

a power supply section that supplies power to a power supply terminal of the device under test;

a power supply control section that controls the power supply section to output the power at a plurality of voltage levels;

a current measuring section that measures, at each voltage level, a current value of a quiescent current of the device under test, the quiescent current being supplied to the power supply terminal of the device under test by the power supply section; and

an analyzing section that analyzes whether a defect is present in the device under test by using at least three current values from among the current values measured by the current measuring section at the plurality of voltage levels.

2. The test apparatus according to claim 1 , further comprising a pattern generating section that generates a pattern supplied to the device under test, wherein

the current measuring section measures the quiescent current at each voltage level while the device under test is being supplied with the pattern generated by the pattern generating section.

3. The test apparatus according to claim 2 , wherein

the pattern generating section generates a plurality of the patterns, and

the current measuring section measures the quiescent current for each of the plurality of patterns.

4. A test apparatus that tests a device under test, comprising:

a power supply section that supplies power to a power supply terminal of the device under test;

a power supply control section that controls the power supply section to output the power at a plurality of voltage levels;

a current measuring section that measures, at each voltage level, a current value of a quiescent current of the device under test, the quiescent current being supplied to the power supply terminal of the device under test by the power supply section; and

an analyzing section that analyzes whether a defect is present in the device under test by using at least three current values from among the current values measured by the current measuring section at the plurality of voltage levels, wherein

the analyzing section obtains a resistance value related to the defect based on a quiescent current expression including (i) a first current term whose value increases exponentially in relation to an applied voltage, and (ii) a second current term whose value increases proportionally with the applied voltage, the quiescent current expression being a mathematical expression representing the quiescent current supplied to the power supply terminal.

5. The test apparatus according to claim 4 , wherein

the analyzing section obtains the resistance value from a relational expression by using three expressions to eliminate the first current term, the three expressions being (i) a first expression in which a first current value corresponding to a first voltage level is substituted for the quiescent current expression, (ii) a second expression in which a second current value corresponding to a second voltage level is substituted for the quiescent current expression, and (iii) a third expression in which a third current value corresponding to a third voltage level is substituted for the quiescent current expression.

6. A test method for testing a device under test, comprising the steps of:

applying a first voltage to a power supply terminal of the device under test and obtaining a first current value corresponding to the first voltage by measuring a quiescent current of the device under test supplied to the power supply terminal;

applying a second voltage to the power supply terminal of the device under test and obtaining a second current value corresponding to the second voltage by measuring the quiescent current of the device under test supplied to the power supply terminal;

applying a third voltage to the power supply terminal of the device under test and obtaining a third current value corresponding to the third voltage by measuring the quiescent current of the device under test supplied to the power supply terminal; and

analyzing whether a defect is present in the device under test by using the first current value, the second current value, and the third current value.

7. The test method according to claim 6 , wherein

said analyzing includes obtaining a resistance value related to the defect based on a quiescent current expression including (i) a first current term whose value increases exponentially in relation to an applied voltage, and (ii) a second current term whose value increases proportionally with the applied voltage, the quiescent current expression being a mathematical expression representing the quiescent current supplied to the power supply terminal.