Prober and method for inspecting probe

Abstract

To provide a prober and a probe inspection method capable of performing alignment with high accuracy even when high-voltage measurement is performed.SOLUTION: A prober 100 for performing an electrical test on a wafer includes: a wafer chuck 20 having a holding surface for holding a wafer W; a probe card 25 having a plurality of probes 26 on a surface facing the holding surface; an alignment device for positioning the wafer chuck with respect to the probe card; and a control device. The control device includes a memory, a processor, and a program stored in the memory and configured to be executable by the processor, the program including an instruction to switch position control of the alignment device from full-closed control to semi-closed control at first timing related to a start of the electrical test.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a prober for performing electrical tests on wafers and a probe inspection method. [Background technology]

[0002] A prober is known as a device used to check the operation of semiconductor chips formed on a wafer. This check is an electrical test called wafer-level inspection. Specifically, the electrode pads of the semiconductor chip are connected to a test head via probes, and the test head supplies power and test signals, and the test head measures the signals output by the semiconductor chip.

[0003] Wafer-level inspection requires highly accurate contact of multiple probes with the electrode pads of a semiconductor chip, i.e., highly accurate alignment (positioning) between the probes (probe card) and the electrode pads of the semiconductor chip.

[0004] As such a technique, Patent Document 1 discloses a prober and a probe alignment method that are capable of performing alignment with high accuracy. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-175805 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the applications of power semiconductors have expanded. Power semiconductors are used in power converters such as inverters and converters, and can be used at higher voltages, currents, and frequencies. Demand for power semiconductors is expanding, particularly with the spread of electric vehicles such as EVs (electric vehicles) and PHEVs (plug-in hybrid vehicles). In order to conduct electrical tests on such semiconductor chips, there is an increasing demand for probers to be able to stably perform tests at higher voltages.

[0007] The inventors have found that when a prober measures high voltage, sparks occur inside the device, particularly inside the wafer, and this affects the operation of the wafer alignment device. Specifically, they have found that the sparks appear as noise (contaminate) in the output signal of the position detection means (e.g., linear scale) of the alignment device. This noise can sometimes exceed the alarm threshold of the position detection means. Noise that exceeds the alarm threshold often stops the operation of the alignment device and the prober itself.

[0008] FIG. 7 is a diagram showing an example of an output signal of a linear scale (position detection means) in a conventional prober. The horizontal axis 50 represents time, and the vertical axis 51 represents the magnitude of the output signal. FIG. 7 shows the effect that a spark has on an output signal 52 of the linear scale. That is, when a spark occurs inside the device, a large amplitude noise 53 is generated in the output signal 52. When this exceeds the alarm thresholds of the upper limit 54 and / or the lower limit 55 (part indicated by reference numeral 56), the operation of the prober is generally stopped. If the operation of the prober is stopped, the inspection efficiency of the wafer W will be significantly reduced.

[0009] The present disclosure aims to solve at least some of the problems associated with the prior art, such as those described above. Specifically, one of the objectives of the present disclosure is to provide a prober and a probe inspection method that are capable of performing high-precision alignment even when performing high-voltage measurements. [Means for solving the problem]

[0010] One embodiment of the prober of the present disclosure is a prober that performs electrical testing on a wafer, and includes a wafer chuck having a holding surface that holds the wafer, a probe card having a plurality of probes on a surface opposite the holding surface, an alignment device that positions the wafer chuck relative to the probe card, and a control device, wherein the control device includes a memory, a processor, and a program stored in the memory and configured to be executable by the processor, the program including an instruction to switch the position control of the alignment device from full-closed control to semi-closed control at a first timing related to the start of the electrical test.

[0011] One embodiment of the probe inspection method of the present disclosure is a probe inspection method including: using an alignment device to position a wafer chuck, having a wafer held on its holding surface, relative to a probe card having a plurality of probes on a surface opposite the holding surface; performing an electrical test on the wafer using the probes that have been brought into contact with the wafer; and switching the position control of the alignment device from full-closed control to semi-closed control at a first timing related to the start of the electrical test. [Effects of the Invention]

[0012] According to the present disclosure, at least one of the problems of the conventional techniques can be solved. One of the specific effects is that a prober and a probe inspection method that can perform alignment with high accuracy even when performing high-voltage measurement can be provided. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram showing a system configuration of a prober according to an embodiment; [Figure 2] FIG. 4 is an explanatory diagram of the function of a control switching unit during full-closed control. [Figure 3] FIG. 4 is an explanatory diagram of the function of a control switching unit during semi-closed control. [Figure 4]FIG. 1 is a flow diagram showing the procedure of an electrical test (wafer-level inspection) using a prober. [Figure 5] FIG. 10 is a flow diagram of another example of a procedure for electrical testing (wafer-level inspection) using a prober. [Figure 6] FIG. 10 is a flow diagram of another example of a procedure for electrical testing (wafer-level inspection) using a prober. [Figure 7] FIG. 10 is a diagram illustrating an example of an output signal of a linear scale (position detection means) in a conventional prober. DETAILED DESCRIPTION OF THE INVENTION

[0014] A first embodiment of the prober of the present disclosure is a prober that performs electrical testing on a wafer, and includes a wafer chuck having a holding surface that holds the wafer, a probe card having a plurality of probes on a surface opposite the holding surface, an alignment device that positions the wafer chuck relative to the probe card, and a control device, wherein the control device includes a memory, a processor, and a program stored in the memory and configured to be executable by the processor, and the program includes an instruction to switch the position control of the alignment device from full-closed control to semi-closed control at a first timing related to the start of the electrical test.

[0015] According to the above prober, the alignment device is switched from full-closed control to semi-closed control at the first timing related to the start of the electrical test. When wafer-level inspection (electrical testing) is performed, the alignment device is controlled by semi-closed control that does not use the output signal of the position detection means. Therefore, even in tests that apply high voltage, the alignment device and prober are prevented from stopping due to noise mixed in the output signal of the position detection means. Furthermore, since the control is switched from the fully closed control at the first timing related to the start of the electrical test, in other words, positioning is performed under the fully closed control until the first timing, the positioning accuracy is also improved.

[0016] Generally, semi-closed control is said to have lower positioning accuracy than fully closed control. However, in the above-mentioned prober, since the control is switched to semi-closed loop control only at the first timing, the positioning accuracy is high up to that point. Furthermore, wafer-level inspection (electrical testing) is generally performed with the electrode pads of the semiconductor chip on the wafer in contact with the probes of the probe card. In other words, once the electrical testing begins, the alignment device is mainly required to stop the wafer at a predetermined position. Therefore, the positioning accuracy required during the electrical testing is not as high as that required before the electrical testing begins. In other words, although the above-mentioned prober may employ semi-closed loop control in some areas, when looking at the overall process of wafer-level inspection, it can perform electrical tests requiring high voltage application more stably than conventional techniques, and also has higher positioning accuracy.

[0017] A second embodiment of the prober of the present disclosure is a prober in which, in the first embodiment, the alignment device is equipped with a position detection means for detecting the position of the wafer chuck, a driving means for driving the wafer chuck, and a feedback sensor provided on the driving means.

[0018] The alignment device includes a position detection means and a feedback sensor. Therefore, around the first timing, the position control of the wafer chuck is switched from full-closed control based on the output signal of the position detection means to semi-closed control based on the output signal of the feedback sensor. The output signal of the feedback sensor is less likely to generate large noise even when a high voltage is applied, resulting in more stable operation of the prober.

[0019] A third embodiment of the prober of the present disclosure is the prober of the first or second embodiment, wherein the first timing is before application of a measurement voltage for the electrical test.

[0020] Setting the first timing to be before (specifically, immediately before) the application of the measurement voltage for the electrical test means that positioning is performed under full-closed control until the application of the measurement voltage. With the above prober, the positioning accuracy is further improved and the operation of the prober is more stable.

[0021] A fourth embodiment of the prober of the present disclosure is a prober according to the first or second embodiment, which includes a test head that supplies test signals to the wafer via the plurality of probes, and the first timing is immediately after the control device receives a signal to start measurement by the test head.

[0022] Setting the first timing to immediately after receiving the measurement start signal means that positioning is performed under full-closed control until immediately before the application of a high voltage that would cause noise in the output signal of the position detection device. With this prober, the positioning accuracy is further improved and the operation of the prober is more stable.

[0023] A fifth embodiment of the prober of the present disclosure is the prober of the first or second embodiment, wherein the first timing is after the wafer chuck has been positioned at a predetermined position for the start of the electrical test.

[0024] By setting the first timing after positioning (typically immediately after), the timing to switch to semi-closed loop control can be determined using only the control sequence of the alignment device, without waiting for a signal related to the start of an electrical test. This makes it easier to control the prober. Of course, switching to semi-closed loop control may also be performed based on a test start signal provided by the test head.

[0025] A sixth embodiment of the prober of the present disclosure is a prober in which, in the first or second embodiment, the alignment device is configured to be able to move the wafer chuck in the Z-axis direction opposite the probe card and in the XY-axis directions approximately parallel to the probe card, and the first timing is before the wafer chuck is moved upward in the Z-axis direction toward the probe card.

[0026] A wafer held on a wafer chuck has multiple semiconductor chips formed on it. Electrical testing is performed by contacting probes with the electrode pads of each of the multiple semiconductor chips. For this purpose, multiple probes are arranged on a probe card. Therefore, precise positioning of the wafer and probes is essential for accurate wafer-level inspection. In particular, high positioning accuracy is required in the X and Y axes to align the positions of multiple probes and electrode pads.

[0027] On the other hand, position control in the Z-axis direction is typically performed to bring the probe, which is an elastic body, into contact with the electrode pad. This requires a slightly lower level of precision than control in the X- and Y-axes. Therefore, even if the control is switched to semi-closed loop control before (typically immediately before) position control in the Z-axis direction, the effect on measurement precision of the prober as a whole is kept to a minimum.

[0028] A seventh embodiment of the prober of the present disclosure is a prober in the sixth embodiment, wherein the program further includes an instruction to position the alignment device in the XY axis direction before starting the electrical test and before switching to semi-closed control.

[0029] In the above prober, positioning in the X and Y axes is performed using full-closed control, which allows for even greater positioning accuracy.

[0030] An eighth embodiment of the prober of the present disclosure is a prober in which, in the first or second embodiment, the program includes an instruction to switch the position control of the alignment device from semi-closed control to fully closed control at a second timing related to the end of the electrical test.

[0031] During the electrical test, there is a risk of noise being generated in the position detection means due to the application of high voltage. However, after the electrical test is completed, there is almost no risk of this happening, so by switching to full-closed control at the second timing, positioning accuracy is further improved.

[0032] A ninth embodiment of the prober of the present disclosure is the prober of the eighth embodiment, wherein the second timing is after the electrical test is completed and before the wafer chuck starts to move.

[0033] As described above, the purpose of positioning the alignment device relative to the wafer chuck during electrical testing is to stop it in place (at a predetermined position). Therefore, the influence of semi-closed control on positioning accuracy is minimized. In the above prober, before (typically just before) the wafer chuck starts moving (from a stopped state), the control is switched to full-closed control, which has higher positioning accuracy. Therefore, the positioning accuracy and stability of the prober as a whole are improved.

[0034] A first embodiment of the probe inspection method of the present disclosure is a probe inspection method including: using an alignment device to position a wafer chuck, having a wafer held on its holding surface, relative to a probe card having a plurality of probes on a surface opposite the holding surface; performing an electrical test on the wafer using the probes that have been brought into contact with the wafer; and switching the position control of the alignment device from full-closed control to semi-closed control at a first timing related to the start of the electrical test.

[0035] According to the probe inspection method, the position control of the alignment device is switched from full-closed control to semi-closed control at the first timing related to the start of the electrical test. When wafer-level inspection (electrical testing) is performed, the alignment device is controlled by semi-closed control that does not use the output signal of the position detection means. Therefore, even in tests that apply high voltage, the alignment device and prober are prevented from stopping due to noise generated by the position detection means. Furthermore, since the control is switched from the fully closed control at the first timing related to the start of the electrical test, in other words, positioning is performed under the fully closed control until the first timing, the positioning accuracy is also improved.

[0036] 1 is a block diagram showing the system configuration of a prober 100 according to an embodiment. The prober 100 includes a prober control unit 10, an XY stage 22, a Zθ stage 21, a wafer chuck 20, probes 26, a probe card 25, a servo amplifier 30, and the like.

[0037] The prober control unit 10 includes a memory and a processor. The prober control unit 10 is typically a computer and is a control device for the prober 10. The prober control unit 10 executes a program stored in the memory using the processor, issues commands to the servo amplifier 30, etc., and controls the operation (operation sequence) of the prober 10. The prober control unit 10 includes a communication unit 10-1 and a drive control unit 10-2. These functions are realized by instructions included in a program stored in a memory included in the prober control unit 10, related hardware, and related software.

[0038] The communication unit 10-1 is a function realized by hardware such as a communication interface and software such as related drivers, etc. Based on instructions included in the program of the prober control unit 10, the communication unit 10-1 establishes a connection between the prober control unit 10 and the test head 29, and performs signal transmission and reception, data conversion, etc. The drive control unit 10-2 controls the alignment device (XY stage 22 and Zθ stage 21) based on commands included in the program of the prober control unit 10 to adjust the position of the wafer W. The alignment device is directly controlled by a servo amplifier 30. The servo amplifier 30 operates based on commands from the drive control unit 10-2. In other words, the servo amplifier 30 constitutes a part of the control device.

[0039] The servo amplifier 30 includes a position information acquisition unit 30-1, a control switching unit 30-2, and a motor control unit 30-3, all of which are functions of the servo amplifier 30, and will be described in detail later.

[0040] The wafer chuck 20 has a holding surface that holds the wafer W. The relative position of the wafer W held on the holding surface and the probe card 25 is adjusted by an XY stage 22 and a Zθ stage 21. In other words, the XY stage 22 and the Zθ stage 21 constitute an alignment device that positions the wafer chuck 20 relative to the probe card 25. The XY stage 22 adjusts the position of the wafer W in the direction along the surface (XY axis direction). The XY axis direction is also approximately parallel to the probe card 25. The Zθ stage 21 adjusts the position of the wafer W in the direction in which the surface faces (Z axis direction) and in the θ axis direction. The θ axis is a rotation axis centered on the Z axis.

[0041] The XY stage 22 includes a servo motor 27 as a driving means, a linear scale 24 as a position detection means, and a rotary encoder 28 as a feedback sensor. However, the driving means, position detection means, and feedback sensor of the alignment apparatus are not limited to those described above. For example, the driving means is not particularly limited as long as it can drive the XY stage 22. It may be, for example, a stepping motor, a brushless motor, or a vector-controlled inverter motor with a sensor. Furthermore, the position detection means is not particularly limited as long as it detects the position of the wafer chuck 20 (or the position of the XY stage 22) and the output signal can be used for feedback control of the driving means. For example, the linear scale may be optical, magnetic, capacitive, or a combination of these. Other position detection means include a laser interferometer. Furthermore, the feedback sensor is not particularly limited as long as it is a device that can measure the rotation angle of the motor, which is the driving means. A magnetostrictive displacement sensor or the like may be used instead of a rotary encoder.

[0042] If the driving means is a pulse motor, the feedback sensor can be omitted. In this case, the semi-closed control can be replaced by position control using only pulse commands from the servo amplifier 30. Furthermore, the full-closed control can be position control that uses linear scale information from the linear scale 24 and feeds it back to the servo amplifier 30. Although not shown, the Zθ stage 21 preferably includes a driving unit, a position detection device, and a feedback sensor, similar to the XY stage 22. The above-described hardware components of the Zθ stage 21 may be the same as those of the XY stage 22.

[0043] The probe card 25 has a plurality of probes 26. The probes 26 are each connected to a terminal of a test head 29. During wafer-level testing, the probes 26 come into contact with electrode pads of a semiconductor chip formed on the wafer W. The contact position is adjusted by an alignment device. As a result, the terminals of the test head 29 are electrically connected to the electrode pads via the probes 26 . The test head 29 supplies power and test signals to the electrode pads. The test head 29 also detects outputs from the electrode pads. In this way, wafer-level inspection (electrical testing) is performed.

[0044] Next, one embodiment of the procedure for carrying out an electrical test will be described. Fig. 4 is a flow diagram showing the procedure for an electrical test (wafer-level inspection) using the prober 100. First, in step S1, the servo amplifier 30 controls the servo motor 27 to position the XY stage 22. The servo amplifier 30 performs the positioning in response to a command from the drive control unit 10-2. When the communication unit 10-1 of the prober control unit 10 receives a signal from the test head 29 to start an electrical test, the drive control unit 10-2 sends the command. Specifically, the XY stage 22 holding the wafer W on the wafer chuck 20 is positioned by driving a ball screw 23 with a servo motor 27 .

[0045] When the ball screw 23 is rotated by the servo motor 27, the XY stage 22 is moved to a predetermined position. Whether the amount of movement is as instructed, that is, the position of the XY stage 22 (i.e., the position of the wafer chuck 20), is detected by the linear scale 24. Also, whether the amount of rotation of the servo motor 27 is as instructed is detected by the rotary encoder 28 of the servo motor 27. The detected linear scale information 62 and encoder information 61 are input to the position information acquisition unit 30-1 of the servo amplifier 30.

[0046] The position information acquiring unit 30-1 transmits the acquired position information to the motor control unit 30-3 via the control switching unit 30-2. The motor control unit 30-3 transmits motor command information 64 to the servo motor 27 based on the position information, and drives the XY stage 22 to a predetermined position corresponding to the probe card 25. At this time, the position of the XY stage 22 is controlled by full-closed control using linear scale information 62 detected by the linear scale 24. In other words, the positioning of the alignment device in the X and Y axes directions is performed by full-closed control. As will be described in detail later, the position information acquisition unit 30-1 transmits the linear scale information 62 and encoder information 61 as position information to the control switching unit 30-2. The control switching unit 30-2 transmits only the linear scale information 62 as the selected position information 63 to the motor control unit 30-3.

[0047] Next, in step S2, the control switching unit 30-2 of the servo amplifier 30 switches the positioning of the alignment device to semi-closed control based on the control switching command 60 of the drive control unit 10-2. In other words, at the timing (an example of a first timing) when the positioning of the alignment device in the X and Y axes directions associated with the start of the electrical test is completed, the drive control unit 10-2 transmits the control switching command 60 to the control switching unit 30-2. The timing at which positioning in the X and Y axes is completed may be immediately before the wafer chuck 20 is moved upward in the Z axis direction, or immediately after the servo amplifier 30 receives a command to lift the Zθ stage 21. The command to lift the Zθ stage 21 may be received from the drive control unit 10-2 based on the driving status of the alignment device, or may be received from the drive control unit 10-2 based on a higher-level command received from the test head 29. When the control is switched to semi-closed control, the control switching unit 30-2 transmits only the encoder information 61 as the selected position information 63 to the motor control unit 30-3.

[0048] An example of a method for switching between the fully closed control and the semi-closed control will now be described in detail. FIG. 2 is an explanatory diagram of the function of the control switching unit 30-2 during full-closed control. The control switching unit 30-2 passes one of the pieces of position information acquired by the position information acquisition unit 30-1 as selected position information 63 to the motor control unit 30-3 for feedback control. The position information acquisition unit 30-1 acquires encoder information 61 from the rotary encoder 28 and linear scale information 62 from the linear scale 24. The state where the control switching unit 30-2 transmits the linear scale information 62 as the selected position information 63 to the motor control unit 30-3 is the fully closed control state. 3 is an explanatory diagram of the function of the control switching unit 30-2 during semi-closed control. In this case, the control switching unit 30-2 transmits the encoder information 61 as the selected position information 63 to the motor control unit 30-3. In this way, the semi-closed control and the fully closed control can be easily switched.

[0049] Next, in step S3, the servo amplifier 30, having received a command from the drive control unit 10-2, controls the servo motor 27 to raise and position the Zθ stage 21. Specifically, the wafer W held by the wafer chuck 20 is raised in the Z-axis direction by the Zθ stage 21, and the probes 26 are brought into contact with the wafer W (electrode pads thereof). At this time, the Zθ stage 21 is rotated as necessary to position the electrode pads and the probes. In this state, the electrode pads of the wafer W and the terminals of the test head 29 are electrically connected via the probes 26, completing preparations for the electrical test.

[0050] Next, in step S4, the communication unit 10-1 transmits a notification that preparations for the electrical test (wafer-level inspection) are complete (contact state has been achieved) to the test head 29. After confirming the contact state based on the contact completion signal from the prober control unit 10, the test head 29 starts the electrical test. Specifically, a voltage is applied to an electrode pad formed on the wafer W. In a contact state, the electrode pad and the terminal of the test head 29 are connected via the probe 26. For semiconductors used in power devices, the applied voltage tends to be higher. The test head 29 receives and analyzes signals output from the semiconductor chip to test whether the semiconductor chip operates normally.

[0051] The position control of the alignment device continues under semi-closed control even during testing. The position control of the alignment device is required not only to move the wafer chuck 20 to a predetermined position, but also to prevent the Zθ stage 21 and the XY stage 22 from being displaced due to vibration caused by the upward movement of the Zθ stage 21, impact at the time of contact, disturbance during contact (high voltage measurement), and the like. In other words, position control is performed even when a (high) voltage for measurement is applied. In the prober of this embodiment, semi-closed control is used at this time, which ensures greater resistance to noise and higher stability.

[0052] Next, in step S5, the electrical test is completed. The application of voltage from the test head 29 to the electrode pads is completed. Wafer-level inspection is typically performed on each wafer W. When inspection of one wafer W is completed, the alignment device returns the inspected wafer W to a transport unit (not shown) and receives a new wafer W from the transport unit. For this reason, when inspection of one wafer W is completed, the alignment device is controlled to move the wafer W away from the probe card 25. Therefore, the following steps are for removing and replacing the wafer W.

[0053] Next, in step S6, the control switching unit 30-2 of the servo amplifier 30 switches the positioning of the alignment device to fully closed control. This switching is performed based on a control switching command 60 from the drive control unit 10-2. This control switching command 60 is typically generated when the communication unit 10-1 of the prober control unit 10 receives a signal indicating the end of the electrical test from the test head 29. In other words, the drive control unit 10-2 sends a command to the control switching unit 30-2 at the timing when the prober control unit 10 receives the signal indicating the end of the electrical test from the test head 29 (which is an example of the second timing). The method of switching from semi-closed control to fully closed control is the reverse of the above order.

[0054] The second timing in this example can also be defined as follows in addition to the above. Immediately before the Zθ stage 21 descends after the electrical test is completed Immediately after the servo amplifier 30 receives a command to lower the Zθ stage 21

[0055] The command to lower the Zθ stage 21 can typically be received from the drive control unit 10-2 based on a higher-level command received from the test head 29.

[0056] Next, in step S7, the servo amplifier 30 controls the servo motor 27 to lower the Zθ stage 21. This is performed based on a command from the drive control unit 10-2. The drive control unit 10-2 sends the command when the communication unit 10-1 receives a signal from the test head 29 to start the electrical test. Next, the XY stage 22 is controlled (step S8). The wafer chuck 20 is moved to a position where the wafer W is transferred to and from the transfer unit.

[0057] According to the above prober, the position control of the alignment device is switched from full-closed control to semi-closed control at the first timing related to the start of the electrical test. When wafer-level inspection (electrical testing) is performed, the alignment device is controlled by semi-closed control that does not use the output signal of the position detection means. Therefore, even when testing is performed with high voltage applied, the alignment device and prober are prevented from stopping due to noise generated by the position detection means. Furthermore, since the control is switched from the fully closed control at the first timing related to the start of the electrical test (in other words, since positioning is performed under the fully closed control until the first timing), the positioning accuracy is also improved.

[0058] Furthermore, during the electrical test, the application of high voltage may cause noise to be mixed into the output signal of the position detection means. However, after the electrical test is completed, this risk is almost eliminated. Therefore, by switching to full-closed control at the second timing, positioning accuracy is further improved.

[0059] In the above example, the first timing is the timing when the positioning of the alignment device in the XY axis direction is completed in conjunction with the start of the electrical test, and the second timing is the timing when the prober control unit 10 receives a signal from the test head 29 indicating the end of the electrical test. However, the first timing, that is, the timing at which the positioning of the wafer chuck 20 is switched from the fully closed control to the semi-closed control, is not limited to the above. Furthermore, the second timing, i.e., the timing at which the positioning of the wafer chuck 20 is switched from semi-closed control to full-closed control, is not limited to the above. Other examples of the first timing and the second timing will be described below.

[0060] 5 and 6 are flow diagrams showing another example of the procedure for electrical testing (wafer-level inspection) using a prober. The flow in Fig. 5 shows the procedure up to the start of the electrical testing. In the flow of Fig. 5, after positioning the XY stage 22 in step S1, the Zθ stage 21 is raised and positioned in step S3. Step S1 is the same as the corresponding step in the flow of Fig. 4. Step S3 is also the same as the corresponding step in the flow of Fig. 4, except that it is performed under full-closed control.

[0061] After the Zθ stage 21 is raised and positioned, the control is switched to semi-closed loop control in step S2. Then, an electrical test is started in step S4. That is, the first timing in this example is immediately before the electrical test. The term "immediately before the electrical test" can be defined as follows, for example. Immediately after the communication unit 10-1 receives a measurement start signal from the test head 29 Immediately after the prober control unit 10 transmits a contact completion signal to the test head 29 Immediately after the wafer chuck 20 is aligned to the predetermined position for the start of the electrical test

[0062] In the above example, the terms "immediately before" and "immediately after" are used, but this does not imply a time limitation. For example, an operation sequence in which A, B, and C are processed in this order will be described. When we say "D is performed immediately after A," we mean that the operations are performed in the order A, D, B, and C. In other words, when we say "immediately after A," we mean that D is inserted between A and B, which was processed immediately after A. The same applies to "D is performed immediately before B." The above interpretation applies to other parts of this specification as well.

[0063] 6 is a flow diagram of another example of the procedure for electrical testing (wafer-level inspection) using a prober, showing the procedure from the end of the electrical test. In the flow of FIG. 6, after the electrical test is completed in step S5, the Zθ stage 21 is lowered in step S7. This flow differs from the flow of FIG. 4 in that the lowering of the Zθ stage 21 in step S7 is performed under semi-closed loop control.

[0064] Next, the control is switched to the fully closed control in step S6, and then, in step S8, the XY stage 22 is moved.

[0065] In this example, the timing (second timing) of switching from semi-closed control to fully closed control is after the Zθ stage 21 has descended. "After the Zθ stage 21 has descended" can be defined, for example, as follows. Immediately before XY stage 22 starts operating Immediately after the wafer chuck 20 has finished descending

[0066] As described above, according to this embodiment, even in a prober that performs high-voltage measurement, there is no need to use an expensive, highly noise-resistant linear scale 24, and it is possible to prevent positional deviation of the XY stage 22, etc. due to impacts at the time of contact or disturbances during contact (high-voltage measurement). Furthermore, the prober of this embodiment performs semi-closed loop control at a timing when noise is likely to be mixed into the output signal of the linear scale 24, thereby suppressing operation stoppages due to errors. This improves the testing efficiency of the wafer W, achieves high throughput, and improves positioning accuracy. Furthermore, switching between full-closed control and semi-closed control can be achieved by updating the program of the control device. In other words, even if a prober has already been installed in a factory, etc., it can be used as the prober of the present disclosure by updating the program.

[0067] It should be noted that the first timing and the second timing described in the flow of Fig. 4 and the flows of Fig. 5 and 6 can be combined. That is, the flow of Fig. 4 up to the start of the electrical test may be replaced with the flow of Fig. 5. Also, the flow of Fig. 4 after the end of the electrical test may be replaced with the flow of Fig. 6. [Explanation of symbols]

[0068] 10...Prober control section 10-1…Communications Department 10-2...Drive control unit 20...Wafer chuck 21...Zθ stage 22...XY stage 23...Ball screw 24...Linear scale 25...Probe card 26...Probe 27...Servo motor 28...Rotary encoder 29...Test head 30...Servo amplifier 30-1...Position information acquisition section 30-2...Control switching unit 30-3...Motor control unit W...wafer

Claims

1. A prober for performing electrical tests on a wafer, a wafer chuck having a holding surface for holding a wafer; a probe card having a plurality of probes on a surface opposite to the holding surface; an alignment device that positions the wafer chuck relative to the probe card; and a control device, the control device includes a memory, a processor, and a program stored in the memory and configured to be executable by the processor; The program includes a command to switch position control of the alignment device from full-closed control to semi-closed control at a first timing related to the start of the electrical test.

2. 2. The prober according to claim 1, wherein said alignment device comprises: a position detecting means for detecting the position of said wafer chuck; a driving means for driving said wafer chuck; and a feedback sensor provided in said driving means.

3. 3. The prober according to claim 1, wherein the first timing is before application of a measurement voltage for the electrical test.

4. a test head that supplies test signals to the wafer via the plurality of probes; 3. The prober according to claim 1, wherein the first timing is immediately after the control device receives a signal to start measurement by the test head.

5. 3. The prober according to claim 1, wherein the first timing is after the wafer chuck is positioned at a predetermined position for starting the electrical test.

6. the alignment device is configured to be able to move the wafer chuck in a Z-axis direction facing the probe card and in X-axis and Y-axis directions substantially parallel to the probe card; 3. The prober according to claim 1, wherein the first timing is before the wafer chuck is moved upward in the Z-axis direction toward the probe card.

7. 7. The prober according to claim 6, wherein the program further includes an instruction to position the alignment device in the X and Y axis directions before starting the electrical test and before switching to the semi-closed loop control.

8. 3. The prober according to claim 1, wherein the program includes a command to switch the position control of the alignment device from semi-closed control to fully closed control at a second timing related to the end of the electrical test.

9. 9. The prober according to claim 8, wherein the second timing is after the electrical test is completed and before the wafer chuck starts to move.

10. positioning a wafer chuck, with a wafer held on a holding surface, relative to a probe card having a plurality of probes on a surface opposite to the holding surface by an alignment device; performing an electrical test on the wafer with the probe in contact with the wafer; and switching position control of the alignment device from full-closed control to semi-closed control at a first timing related to the start of the electrical test.

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