Testing device, testing method, and non-transitory storage medium storing testing program

1 . A testing apparatus comprising:

(a) a stage having an upper surface and configured to support a test object that includes an electrode having an upper surface;

(b) a probe assembly including a probe needle having a tip;

(c) a motor-driven actuator mechanically coupled to the probe assembly and configured to move the probe needle along a vertical axis toward and away from the stage;

(d) a laser displacement sensor oriented to direct laser light to the electrode and to output measurement data indicative of a distance from the laser displacement sensor to the upper surface of the electrode; and

(e) a controller comprising a processor and a non-transitory memory storing instructions that, when executed by the processor, cause the controller to:

(i) with the probe needle positioned above the stage and separated from the test object, control the laser displacement sensor to measure a thickness T defined as a distance from the upper surface of the stage to the upper surface of the electrode;

(ii) determine a movement amount P according to P=D1−T+D2, where D1 is a stored distance from the tip to the upper surface of the stage when the probe needle is positioned above the stage and separated from the test object, and D2 is a predetermined overdrive amount; and

(iii) drive the motor-driven actuator to move the probe needle by the movement amount P such that the tip contacts the electrode and, after contact, advances by the predetermined overdrive amount to slide on a surface of the electrode toward a central portion of the electrode.

2 . The testing apparatus according to claim 1 , further comprising:

the stage,

wherein the controller is

configured to position the probe needle

above the stage and separated from the test object, and to drive the motor-driven actuator to move the probe needle by the movement amount P determined in accordance with the thickness T, the stored distance D1 from the tip to the upper surface of the stage, and the predetermined overdrive amount D2.

3 . The testing apparatus according to claim 2 , wherein the controller is configured to determine the movement amount P by adding the predetermined overdrive amount D2 to a difference between the stored distance D1 and the thickness T, according to P=D1−T+D2, and to drive the motor-driven actuator to move the probe needle by the movement amount P.

4 . The testing apparatus according to claim 1 , wherein

the test object includes a plurality of the electrodes, and

the laser displacement sensor is configured to measure the thickness T by directing the laser light to at least one electrode of the plurality of the electrodes.

5 . The testing apparatus according to claim 4 , wherein

the probe assembly includes a plurality of the probe needles, and

the controller is configured to drive the motor-driven actuator such that the plurality of probe needles move in accordance with the thickness T to come into contact with the plurality of the electrodes.

6 . The testing apparatus according to claim 4 , wherein

the laser displacement sensor is configured to measure the thickness T by directing the laser light to a central portion of the at least one electrode of the plurality of the electrodes.

7 . The testing apparatus according to claim 1 , wherein the test object is a light modulator.

8 . The testing apparatus of claim 1 , wherein the test object includes a plurality of electrodes and the probe assembly includes a plurality of probe needles corresponding to the plurality of electrodes, and wherein the controller is configured to control the laser displacement sensor to measure the thickness T by directing the laser light to only one of the plurality of electrodes and to determine the movement amount P for moving the plurality of probe needles based on the thickness measured for the one electrode.

9 . The testing apparatus of claim 1 , wherein the controller is further configured, after driving the motor-driven actuator so the probe needle contacts the electrode, to (i) apply a predetermined voltage between the probe needle and the electrode, (ii) measure a current responsive to the predetermined voltage, and (iii) determine whether electrical contact between the probe needle and the electrode is established based on a measured current-voltage characteristic, before performing a subsequent electrical test of the test object.

10 . A testing method comprising:

supporting, on a stage having an upper surface, a test object

including an electrode having an upper surface;

positioning a probe needle above the stage and separated from the test object;

directing laser light from a laser displacement sensor to the electrode and outputting measurement data indicative of a distance from the laser displacement sensor to the upper surface of the electrode;

measuring, based on the measurement data, a thickness T defined as a distance from the upper surface of the stage to the upper surface of the electrode;

determining a movement amount P according to P=D1−T+D2, where D1 is a stored distance from a tip of the probe needle to the upper surface of the stage when the probe needle is positioned above the stage and separated from the test object, and D2 is a predetermined overdrive amount; and

driving a motor-driven actuator mechanically coupled to a probe assembly to move the probe needle by the movement amount P such that the tip contacts the electrode and, after contact, advances by the predetermined overdrive amount to slide on a surface of the electrode toward a central portion of the electrode.

11 . A non-transitory storage medium storing a testing program for causing a computer to function as:

a measurement control unit configured to control a laser displacement sensor to direct laser light to an electrode of a test object and to output measurement data indicative of a distance from the laser displacement sensor to an upper surface of the electrode, and to measure, based on the measurement data, a thickness T defined as a distance from an upper surface of a stage to the upper surface of the electrode; and

a movement control unit configured to determine a movement amount P according to P=D1−T+D2, where D1 is a stored distance from a tip of a probe needle to the upper surface of the stage when the probe needle is positioned above the stage and separated from the test object, and D2 is a predetermined overdrive amount, and to drive a motor-driven actuator to move the probe needle by the movement amount P such that the tip contacts the electrode and, after contact, advances by the predetermined overdrive amount to slide on a surface of the electrode toward a central portion of the electrode.