Wafer chuck inclination correcting method and probe apparatus
A method for correcting inclination of a wafer chuck includes obtaining in advance a correction amount for each of the semiconductor chips which corrects the inclination of the wafer chuck in the case of applying a contact load to at least each one of the semiconductor chips and storing each of the correction amounts in a data storage unit; calculating a total correction amount for correcting the inclination of the wafer chuck by calculating the correction amount of each of the semiconductor chips bringing into contact with the probes when the semiconductor wafer comes into electrical contact with the probes and adding the calculated correction amounts; and correcting the inclination of the wafer chuck based on the total correction amount.
1. A method for correcting a first inclination of a wafer chuck which occurs when electrical characteristics of a plurality of semiconductor chips of a semiconductor wafer are tested by bringing the semiconductor wafer held by the wafer chuck into electrical contact with a multiplicity of probes of a probe card at least once, the probe card having a size which covers substantially all the semiconductor chips, the method comprising the steps of:
(a) measuring first displacements for each of the semiconductor chips by applying a load to each of the semiconductor chips and storing the first displacements in a data storage unit;
(b) calculating a contact load of each of the semiconductor chips occurring when the semiconductor wafer comes into electrical contact with the probes;
(c) calculating second displacements of each of the semiconductor chips based on the first displacements and the contact load of a corresponding semiconductor chip and storing the second displacements as a correction amount of each of the semiconductor chips in the data storage unit;
(d) overdriving the wafer chuck to render the probes to make electrical contact with at least a part of the semiconductor chips;
(e) obtaining correction amounts of semiconductor chips which contact with the probes of the probe card having the size which covers substantially all the semiconductor chips by said overdriving and calculating a total correction amount by adding the obtained correction amounts; and
(f) correcting the first inclination of the wafer chuck prior to a measurement of the electrical characteristics of substantially all the semiconductor chips to arrive at a second inclination by adjusting an incline of the wafer chuck based on the total correction amount obtained by adding the obtained correction amounts.
2. The method of claim 1 , wherein, the first displacements include a vertical displacement occurring at a center of the semiconductor wafer and the contact load is obtained based on the vertical displacement.
3. The method of claim 2 , wherein the first displacements are obtained by an optical unit.
4. The method of claim 3 , wherein the optical unit includes a camera.
5. The method of claim 1 , wherein the step (d) to the step (f) are repeatedly performed.
6. The method of claim 2 , wherein the step (d) to the step (f) are repeatedly performed.
7. The method of claim 3 , wherein the step (d) to the step (f) are repeatedly performed.
8. The method of claim 4 , wherein the step (d) to the step (f) are repeatedly performed.
9. A probe apparatus comprising:
a wafer chuck for holding a semiconductor wafer having a plurality of semiconductor chips;
a probe card, provided above the wafer chuck, having a size which covers substantially all the semiconductor chips;
a control unit for controlling a moving amount of the wafer chuck and correcting a first inclination of the wafer chuck which occurs when the semiconductor wafer and the probe card are brought into electrical contact with each other,
wherein electrical characteristics of the semiconductor chips are tested by bringing the probe card into electrical contact with the semiconductor wafer at least once under the control of the control unit,
wherein the control unit includes a data storage unit and is configured to perform (a) measuring first displacements for each of the semiconductor chips by applying a load to each of the semiconductor chips and storing the first displacements in the data storage unit; (b) calculating a contact load of each of the semiconductor chips occurring when the semiconductor wafer comes into electrical contact with the probes; (c) calculating second displacements of each of the semiconductor chips based on the first displacements and the contact load of a corresponding semiconductor chip and storing the second displacements as a correction amount of each of the semiconductor chips in the data storage unit; (d) overdriving the wafer chuck to render the probes to make electrical contact with at least a part of the semiconductor chips; (e) obtaining correction amounts of semiconductor chips which contact with the probes of the probe card having the size which covers substantially all the semiconductor chips by said overdriving and calculating a total correction amount by adding the obtained correction amounts; and (f) correcting the first inclination of the wafer chuck prior to a measurement of the electrical characteristics of substantially all the semiconductor chips to arrive at a second inclination by adjusting an incline of the wafer chuck based on the total correction amount obtained by adding the obtained correction amounts.
10. The probe apparatus of claim 9 , wherein, the first displacements include a vertical displacement occurring at a center of the semiconductor wafer and the contact load is obtained based on the vertical displacement.