JP7474407B2 - Prober and probe inspection method - Google Patents

Description

The present invention relates to a prober and a probe inspection method for inspecting the electrical characteristics of multiple semiconductor devices (chips) formed on a semiconductor wafer, and in particular to a multi-stage prober and a probe inspection method equipped with multiple measurement units.

The semiconductor manufacturing process involves many steps, and various inspections are performed at each manufacturing step to ensure quality and improve yield. For example, when multiple semiconductor device chips are formed on a semiconductor wafer, wafer-level inspection is performed in which the electrode pads of the semiconductor device of each chip are connected to a test head, power and test signals are supplied from the test head, and the signals output by the semiconductor device are measured by the test head to electrically inspect whether they are operating normally.

After wafer-level inspection, the wafer is attached to a frame and cut into individual chips using a dicer. Of the cut chips, only those that are confirmed to be functioning properly are packaged in the next assembly process; malfunctioning chips are removed from the assembly process. The packaged final products then undergo shipping inspection.

Wafer-level testing is performed using a prober that contacts the electrode pads of each chip on the wafer with a probe. The probes are electrically connected to the terminals of the test head, and power and test signals are supplied from the test head to each chip via the probes, while the output signals from each chip are detected by the test head to measure whether they are operating normally.

In the semiconductor manufacturing process, wafers are becoming larger and more miniaturized (integrated) in order to reduce manufacturing costs, and the number of chips formed on a single wafer is becoming very large. As a result, the time required to inspect a single wafer using a prober is also increasing, and there is a demand for improving throughput. In order to improve throughput, multi-probing is being used, in which multiple probes are provided to enable simultaneous inspection of multiple chips. In recent years, the number of chips inspected simultaneously has been increasing, and attempts are being made to inspect all chips on a wafer simultaneously. As a result, the allowable error in aligning the contact between the electrode pads and the probes is decreasing, and there is a demand for improving the positional accuracy of the movement of the prober.

On the other hand, the easiest way to increase throughput is to increase the number of probers. However, increasing the number of probers causes the problem that the installation area for the probers in the production line also increases. Furthermore, increasing the number of probers increases the equipment costs accordingly. For this reason, there is a demand to increase throughput while suppressing increases in installation area and equipment costs.

Against this background, for example, Patent Document 1 proposes a multi-stage prober equipped with multiple measurement units. In this prober, an alignment device that aligns the wafer and probe card relative to each other is configured to be able to move between each measurement unit. This allows the alignment device to be shared by each measurement unit, saving space and reducing costs.

The prober described in Patent Document 1 employs a vacuum suction method for holding the wafer chuck against the probe card. In this vacuum suction method, the internal space (sealed space) formed between the wafer chuck and the probe card is depressurized by a decompression means, and the wafer chuck is pulled toward the probe card, whereby a contact operation is performed in which the electrode pads of each chip on the wafer come into contact with each probe on the probe card.

JP 2016-032110 A

In the prober described in Patent Document 1, before decompression of the internal space formed between the wafer chuck and the probe card begins, the lifting mechanism of the alignment device raises the wafer chuck toward the probe card, and each probe of the probe card is brought into contact with the electrode pad of each chip on the wafer at a predetermined pressure.

However, when the lifting mechanism of the alignment device brings each probe of the probe card into contact with the electrode pads of each chip on the wafer, depending on the degree of so-called overdrive, more contact pressure than necessary may be applied when the internal space is depressurized, which may result in damage to the wafer.

The present invention was made in consideration of these circumstances, and aims to provide a prober and a probe inspection method that can achieve good contact between the electrode pads on the wafer and the probes without damaging the wafer.

To achieve the above objective, the following invention is provided.

The prober according to the first aspect of the present invention comprises a wafer chuck for holding a wafer, a probe card having a plurality of probes on a surface facing the wafer chuck, an annular seal member forming an internal space between the wafer chuck and the probe card, a mechanical lifting means having a wafer chuck fixing part for removably fixing the wafer chuck and for lifting and lowering the wafer chuck fixed to the wafer chuck fixing part, a suction means for adsorbing and holding the wafer chuck to the probe card side by reducing the pressure in the internal space, a lifting control means for controlling the lifting operation by the mechanical lifting means, the lifting control means for moving the wafer chuck to a contact position where the probes contact the electrode pads of the wafer, and a suction control means for controlling the suction operation by the suction means, the suction control means for moving the wafer chuck from the contact position to an overdrive position where the probes contact the electrode pads of the wafer in an overdrive state.

In the prober according to the second aspect of the present invention, in the first aspect, the suction control means starts the suction operation by the suction means before the internal space becomes sealed.

In the prober according to the third aspect of the present invention, in the first or second aspect, the suction control means sets the amount of suction by the suction means based on the moving speed of the wafer chuck by the mechanical lifting means.

The probe inspection method according to the fourth aspect of the present invention is a probe inspection method in a prober including a wafer chuck for holding a wafer, a probe card having a plurality of probes on a surface facing the wafer chuck, an annular seal member forming an internal space between the wafer chuck and the probe card, a mechanical lifting means having a wafer chuck fixing part for removably fixing the wafer chuck and for raising and lowering the wafer chuck fixed to the wafer chuck fixing part, and a suction means for adsorbing and holding the wafer chuck to the probe card side by reducing the pressure of the internal space, the method including a step of moving the wafer chuck toward the probe card by the mechanical lifting means, a wafer chuck moving step of moving the wafer chuck to a contact position where the probes contact the electrode pads of the wafer, and a step of reducing the pressure of the internal space by the suction means, a suction step of moving the wafer chuck from the contact position to an overdrive position where the probes contact the electrode pads of the wafer in an overdrive state.

The probe inspection method according to the fifth aspect of the present invention is the fourth aspect, in which the suction process is started before the internal space becomes sealed.

The probe inspection method according to the sixth aspect of the present invention is the fourth or fifth aspect, in which the suction step sets the amount of suction by the suction means based on the moving speed of the wafer chuck by the mechanical lifting means.

The present invention makes it possible to achieve good contact between the electrode pads on the wafer and the probes without damaging the wafer.

FIG. 1 is an external view showing the overall configuration of a prober according to an embodiment of the present invention; FIG. 2 is a plan view showing the overall configuration of the prober according to the present embodiment; FIG. 2 is a schematic diagram showing the configuration of a measurement unit in the prober of the present embodiment; FIG. 4 is a schematic diagram showing the configuration of a measurement section in the measurement unit shown in FIG. 3 . FIG. 2 is a functional block diagram showing the configuration of a control device of the prober according to the present embodiment. 1 is a flowchart showing a contact operation in the prober of the present embodiment. FIG. 2 is a diagram for explaining a contact operation in the prober of the present embodiment; FIG. 2 is a diagram for explaining a contact operation in the prober of the present embodiment; FIG. 1 is a timing chart showing an example of a contact operation in the prober of the present embodiment. FIG. 11 is a timing chart showing another example of the contact operation in the prober of the present embodiment. FIG. 11 is a timing chart showing another example of the contact operation in the prober of the present embodiment.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings.

Figures 1 and 2 are an external view and a plan view showing the overall configuration of the prober 10 of this embodiment.

As shown in Figures 1 and 2, the prober 10 of this embodiment includes a loader section 14 that supplies and retrieves a wafer W (see Figure 4) to be inspected, and a measurement unit 12 arranged adjacent to the loader section 14. The measurement unit 12 has multiple measurement sections 16, and when a wafer W is supplied from the loader section 14 to each measurement section 16, each measurement section 16 inspects the electrical characteristics of each chip on the wafer W (wafer-level inspection). The wafer W inspected by each measurement section 16 is then retrieved by the loader section 14. The prober 10 also includes an operation panel 22, a control device 60 (see Figure 5), which will be described later, and the like.

The loader section 14 has a load port 18 on which the wafer cassette 20 is placed, and a transport unit 24 that transports the wafer W between each measurement section 16 of the measurement unit 12 and the wafer cassette 20. The transport unit 24 is equipped with a transport unit drive mechanism (not shown) and is configured to be movable in the X and Z directions and rotatable in the θ direction (around the Z direction). The transport unit 24 also has a transport arm 26 that is configured to be freely extended and retracted back and forth by the transport unit drive mechanism. An adsorption pad (not shown) is provided on the upper surface of the transport arm 26, and the transport arm 26 holds the wafer W by vacuum adsorbing the back surface of the wafer W with this adsorption pad. As a result, the wafer W in the wafer cassette 20 is taken out by the transport arm 26 of the transport unit 24 and transported to each measurement section 16 of the measurement unit 12 while being held on its upper surface. In addition, the inspected wafer W is returned to the wafer cassette 20 from each measurement section 16 by the reverse route.

Figure 3 is a schematic diagram showing the configuration of the measurement unit 12 in the prober 10 of this embodiment. Figure 4 is a schematic diagram showing the configuration of the measurement section 16 in the measurement unit shown in Figure 3.

As shown in FIG. 3, the measurement unit 12 has a stacked structure (multi-tier structure) in which multiple measurement sections 16 are stacked in multiple tiers, and each measurement section 16 is arranged two-dimensionally along the X and Z directions. In this embodiment, as an example, four measurement sections 16 are stacked in the X direction in three tiers in the Z direction.

The measurement unit 12 is equipped with a housing (not shown) having a lattice shape in which multiple frames are combined in a lattice shape. This housing is formed by combining multiple frames extending in the X direction, Y direction, and Z direction in a lattice shape, and components of the measurement section 16 are arranged in each space formed by these frames.

Each measurement unit 16 has the same configuration, and includes a head stage 30, a probe card 32, and a wafer chuck 34, as shown in FIG. 4. Each measurement unit 16 is also provided with a test head (not shown). The test head is supported above the head stage 30 by a test head holder (not shown).

The head stage 30 is supported by a frame member (not shown) that constitutes part of the housing, and a probe card 32 is removably attached and fixed to the head stage 30. The probe card 32 attached and fixed to the head stage 30 is arranged to face the wafer holding surface 34a of the wafer chuck 34. The probe card 32 is replaced depending on the wafer W (device) to be inspected.

The probe card 32 is provided with a number of probes 36, such as cantilevers or spring pins, arranged to correspond to the position of the electrode pads of each chip on the wafer W to be inspected. Each probe 36 is electrically connected to a terminal of a test head (not shown), and power and test signals are supplied from the test head to each chip via each probe 36, while the output signal from each chip is detected by the test head to measure whether it is operating normally. Note that the connection configuration between the probe card 32 and the test head is not an essential part of the present invention, so a detailed description will be omitted.

The probe 36 has spring characteristics, and contacts the electrode pad with a predetermined contact pressure by raising the contact point from the tip position of the probe 36. When the probe 36 contacts the electrode pad in an overdrive state during electrical testing, the tip of the probe 36 sinks into the surface of the electrode pad and forms a needle mark on the surface of the electrode pad. Note that overdrive refers to a state in which the electrode pad, i.e., the surface of the wafer W, is raised by a distance α to a position higher than the tip position of the probe 36 so that the electrode pad and the probe 36 are in reliable contact, taking into account the inclination of the wafer W and the arrangement surface of the tip of the probe 36, and the variation in the tip position of the probe 36. The amount of movement by which the surface of the wafer W is further raised from the tip position (contact position) of the probe 36, i.e., the above distance α, is referred to as the overdrive amount.

The wafer chuck 34 fixes the wafer W by vacuum suction. The wafer chuck 34 has a wafer holding surface 34a on which the wafer W to be inspected is placed, and the wafer holding surface 34a is provided with a plurality of suction ports 40 (only one is shown in FIG. 4). The suction port 40 is connected to a suction device (vacuum source) 44 such as a vacuum pump via a suction path 42 formed inside the wafer chuck 34. A wafer suction solenoid valve 46 is provided in the suction path connecting the suction device 44 and the suction path 42. The wafer suction solenoid valve 46 is controlled by a wafer suction solenoid valve control unit 110 (see FIG. 5).

Outside the wafer holding surface 34a of the wafer chuck 34, an elastic ring-shaped seal member (chuck seal rubber) 48 is provided so as to surround the wafer W held on the wafer holding surface 34a. When the wafer chuck 34 is moved (raised) toward the probe card 32 by the Z-axis movement/rotation unit 72 described below, the ring-shaped seal member 48 comes into contact with the underside of the head stage 30, forming an internal space S (see FIG. 7) surrounded by the wafer chuck 34, the probe card 32, and the ring-shaped seal member 48. The ring-shaped seal member 48 is an example of an annular seal member of the present invention.

The head stage 30 is provided with a suction port 50 for reducing the pressure of the internal space S formed between the probe card 32 and the wafer chuck 34. The suction port 50 is connected to the suction device 44 via a suction path 52 formed inside the head stage 30. A vacuum electro-pneumatic regulator 54 is provided in the suction path connecting the suction device 44 and the suction path 52. The vacuum electro-pneumatic regulator 54 is a control valve that adjusts the internal pressure (degree of vacuum) of the internal space S. The vacuum electro-pneumatic regulator 54 is controlled by the suction control unit 114 (see FIG. 5) described later. The suction device 44 and the vacuum electro-pneumatic regulator 54 are examples of the suction means of the present invention.

Inside the wafer chuck 34, a heating/cooling mechanism (not shown) is provided as a heating/cooling source so that the electrical characteristics of the wafer W to be inspected can be inspected at a high temperature (e.g., up to 150°C) or at a low temperature (e.g., down to -40°C). Any suitable known heater/cooler can be used as the heating/cooling mechanism, and various types are possible, such as a double-layer structure with a heating layer of a surface heater and a cooling layer with a cooling fluid passage, or a single-layer heating/cooling device with a cooling tube wrapped around a heater embedded in a thermal conductor. Also, instead of electrical heating, a device that circulates a thermal fluid or a Peltier element may be used.

The wafer chuck 34 is supported and fixed in a removable manner by the alignment device 70, which will be described later. The alignment device 70 moves the wafer chuck 34 in the X, Y, Z, and θ directions to perform relative alignment between the wafer W held by the wafer chuck 34 and the probe card 32.

The alignment device 70 is equipped with a Z-axis moving/rotating unit 72 that detachably supports and fixes the wafer chuck 34 and moves the wafer chuck 34 in the Z-axis direction while rotating it in the θ direction around the Z-axis, an X-axis moving stage 74 that supports the Z-axis moving/rotating unit 72 and moves it in the X-axis direction, and a Y-axis moving stage 76 that supports the X-axis moving stage 74 and moves it in the Y-axis direction.

The Z-axis moving/rotating unit 72, the X-axis moving stage 74, and the Y-axis moving stage 76 are each configured to move or rotate the wafer chuck 34 in a predetermined direction by a mechanical driving mechanism including at least a motor. The mechanical driving mechanism is, for example, a ball screw driving mechanism that combines a servo motor and a ball screw. The mechanical driving mechanism is not limited to a ball screw driving mechanism, and may be configured as a linear motor driving mechanism or a belt driving mechanism. The Z-axis moving/rotating unit 72, the X-axis moving stage 74, and the Y-axis moving stage 76 are configured so that the moving distance, moving direction, moving speed, and acceleration of the wafer chuck 34 can be changed by the respective control units described later. In this embodiment, the specific configuration is as follows.

The Z-axis moving/rotating unit 72 is an example of the mechanical lifting means of the present invention, and includes a Z-axis drive motor 122 (e.g., a stepping motor, a servo motor, a linear motor, etc.) (see FIG. 5) for moving the wafer chuck 34 in the Z-axis direction, and a Z-axis encoder (e.g., a rotary encoder or a linear scale, etc.) (not shown) for detecting the movement distance of the wafer chuck 34 in the Z-axis direction. The Z-axis drive motor 122 is controlled based on a motor control signal from the Z-axis movement control unit 106 (see FIG. 5), which will be described later, and drives the wafer chuck 34 to move to the target position at the desired movement speed or acceleration. In addition, the Z-axis encoder outputs an encoder signal according to the movement of the wafer chuck 34.

The Z-axis movement/rotation unit 72 also includes a rotary drive motor 124 (e.g., a stepping motor, servo motor, linear motor, etc.) (see FIG. 5) for rotating the wafer chuck 34 in the θ direction, and a rotary encoder (e.g., a rotary encoder, etc.) (not shown) for detecting the rotation angle of the wafer chuck 34 in the θ direction. The rotary drive motor 124 is controlled based on a motor control signal from a θ rotation control unit 108 (see FIG. 5) described later, and drives the wafer chuck 34 to move to a target position at a desired rotational speed or acceleration. The rotary encoder also outputs an encoder signal in response to the rotation of the wafer chuck 34.

The X-axis moving stage 74 is equipped with an X-axis drive motor 118 (e.g., a stepping motor, a servo motor, a linear motor, etc.) (see FIG. 5) for moving the wafer chuck 34 in the X-axis direction, and an X-axis encoder (e.g., a rotary encoder or a linear scale, etc.) (not shown) for detecting the movement distance of the wafer chuck 34 in the X-axis direction. The X-axis drive motor 118 is controlled based on a motor control signal from the X-axis movement control unit 102 (see FIG. 5), which will be described later, and drives the wafer chuck 34 to move to the target position at the desired movement speed or acceleration. In addition, the X-axis encoder outputs an encoder signal according to the movement of the wafer chuck 34.

The Y-axis moving stage 76 is equipped with a Y-axis drive motor 120 (e.g., a stepping motor, a servo motor, a linear motor, etc.) (see FIG. 5) for moving the wafer chuck 34 in the Y-axis direction, and a Y-axis encoder (e.g., a rotary encoder or a linear scale, etc.) (not shown) for detecting the movement distance of the wafer chuck 34 in the Y-axis direction. The Y-axis drive motor 120 is controlled based on a motor control signal from the Y-axis movement control unit 104 (see FIG. 5), which will be described later, and drives the wafer chuck 34 to move to the target position at the desired movement speed or acceleration. In addition, the Y-axis encoder outputs an encoder signal in response to the movement of the wafer chuck 34.

The alignment device 70 is provided for each stage (see FIG. 3), and is configured to be movable between the multiple measurement units 16 arranged on each stage by an alignment device drive mechanism (not shown). That is, the alignment device 70 is shared between the multiple measurement units 16 (four in this example) arranged on the same stage, and moves between the multiple measurement units 16 arranged on the same stage. The alignment device 70 that has moved to each measurement unit 16 is fixed in a predetermined position by a positioning and fixing device (not shown), and the wafer chuck 34 is moved in the X, Y, Z, and θ directions to perform relative alignment between the wafer W held on the wafer chuck 34 and the probe card 32. Although not shown, the alignment device 70 is equipped with a needle position detection camera and a wafer alignment camera to detect the relative positional relationship between the electrode pads of each chip of the wafer W held on the wafer chuck 34 and the probe 36. The alignment device drive mechanism is also composed of mechanical drive mechanisms such as a ball screw drive mechanism, a linear motor drive mechanism, and a belt drive mechanism.

The wafer chuck support surface 72a of the Z-axis moving/rotating part 72 constituting the upper surface of the alignment device 70 is provided with an elastic ring-shaped seal member (Z-axis seal rubber) 78 formed in a ring shape along the outer periphery. In addition, a suction port 80 is provided inside the ring-shaped seal member 78 of the wafer chuck support surface 72a. The suction port 80 is connected to the suction device 44 through a suction path 82 formed inside the wafer chuck 34. In the suction path connecting the suction device 44 and the suction path 82, a chuck fixing solenoid valve 84 and a throttle valve 86 are provided in this order from the suction device 44 side. The chuck fixing solenoid valve 84 is controlled by a chuck fixing solenoid valve control unit 112 (see FIG. 5) described later. The wafer chuck support surface 72a of the Z-axis moving/rotating part 72 is an example of the wafer chuck fixing part of the present invention. In addition, the suction port 80 provided on the wafer chuck support surface 72a is an example of a component of the wafer chuck fixing part.

Positioning pins 88 are provided on the outside of the ring-shaped seal member 78 on the wafer chuck support surface 72a of the Z-axis moving/rotating unit 72 so that the relative positional relationship of the wafer chuck 34 to the alignment device 70 is always constant. The positioning pins 88 are provided at three locations at equal intervals along the circumferential direction centered on the central axis of the wafer chuck 34 (only two are shown in FIG. 4). V-blocks 90, which are positioning members, are provided on the underside of the wafer chuck 34 at positions corresponding to each of the positioning pins 88. When the wafer chuck 34 is fixed by vacuum suction, the corresponding positioning pins 88 are engaged in the V-grooves of each V-block 90 to restrict the horizontal movement of the wafer chuck 34 (X-direction and Y-direction), thereby positioning the alignment device 70 and the wafer chuck 34 relative to each other.

In this embodiment, the alignment device 70 fixes the wafer chuck 34 by vacuum suction, but any fixing means other than vacuum suction may be used as long as it is capable of fixing the wafer chuck 34, and for example, the wafer chuck 34 may be fixed by mechanical means, etc.

Figure 5 is a functional block diagram showing the configuration of the control device 60 of the prober 10 of this embodiment.

The control device 60 stores data necessary for the operation and processing of each part of the prober 10. The control device 60 is realized by a general-purpose computer such as a personal computer or a microcomputer.

The control device 60 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input/output interface. In the control device 60, various programs such as a control program stored in the ROM are expanded into the RAM, and the programs expanded into the RAM are executed by the CPU, thereby realizing the functions of each part in the control device 60 shown in FIG. 5, and various calculation processes and control processes are executed via the input/output interface.

As shown in FIG. 5, the control device 60 includes an overall control unit 100, an X-axis movement control unit 102, a Y-axis movement control unit 104, a Z-axis movement control unit 106, a θ rotation control unit 108, a wafer suction solenoid valve control unit 110, a chuck fixing solenoid valve control unit 112, and a suction control unit 114.

The overall control unit 100 provides overall control over each component of the prober 10. Specifically, the overall control unit 100 controls the operation (contact operation) of bringing the electrode pads of each chip on the wafer W to be inspected into contact with each probe 36 on the probe card 32. In addition to the contact operation, the overall control unit 100 also controls the movement of the alignment device 70 between each measurement unit 16, and controls the operation of wafer-level inspection using the test head. Note that controls other than the contact operation are not characteristic of the present invention, so detailed explanations will be omitted.

The X-axis movement control unit 102 controls the drive of the X-axis drive motor 118 provided on the X-axis moving stage 74 to move the X-axis moving stage 74 in the X-axis direction, thereby moving the wafer chuck 34 in the X-axis direction. The Y-axis movement control unit 104 controls the drive of the Y-axis drive motor 120 provided on the Y-axis moving stage 76 to move the Y-axis moving stage 76 in the Y-axis direction, thereby moving the wafer chuck 34 in the Y-axis direction. The Z-axis movement control unit 106 is an example of the elevation control means of the present invention, and controls the drive of the Z-axis drive motor 122 provided on the Z-axis moving/rotating unit 72 to elevate the Z-axis moving/rotating unit 72, thereby moving the wafer chuck 34 in the Z-axis direction. The θ rotation control unit 108 controls the drive of the rotation drive motor 124 provided on the Z-axis moving/rotating unit 72 to rotate the Z-axis moving/rotating unit 72 in the θ direction, thereby rotating the wafer chuck 34 in the θ direction.

The wafer suction solenoid valve control unit 110 controls the ON/OFF (open/close) of the wafer suction solenoid valve 46 to adjust the suction pressure by the suction port 40 and selectively switch between fixing and not fixing the wafer W to the wafer chuck 34.

The chuck fixing solenoid valve control unit 112 controls the ON/OFF (open/close) of the chuck fixing solenoid valve 84 to adjust the suction pressure by the suction port 80 and selectively switches between fixing and not fixing the wafer chuck 34 to the Z-axis movement/rotation unit 72.

The suction control unit 114 controls the operation of the vacuum electropneumatic regulator 54 to continuously adjust the internal pressure (degree of vacuum) of the internal space S. The suction control unit 114 is an example of the suction control means of the present invention.

Next, the contact operation (one example of a probe inspection method) in the prober 10 of this embodiment will be described with reference to Figures 6 to 9. This operation is performed under the control of the overall control unit 100.

Figure 6 is a flow chart showing the contact operation in the prober 10 of this embodiment. Figures 7 and 8 are diagrams for explaining the contact operation in the prober 10 of this embodiment. Figure 9 is a timing chart showing an example of the contact operation in the prober 10 of this embodiment. Note that "chuck height" in Figure 9 indicates the height position of the wafer chuck 34 (specifically, the position of the wafer holding surface 34a in the Z-axis direction). Also, "chuck suction pressure" in Figure 9 indicates the absolute value of the suction pressure (negative pressure) applied to the suction port 50 when the suction control unit 114 controls the operation of the vacuum electropneumatic regulator 54. Also, "Z-axis height" in Figure 9 indicates the height position of the Z-axis moving/rotating unit 72 (specifically, the position of the wafer chuck support surface 72a in the Z-axis direction).

(Pre-action)
The pre-contact action will now be described.

First, as a preliminary operation for the contact operation, the alignment device 70 is moved to the measurement section 16 where the inspection will be performed, and then the wafer chuck 34 is transferred to the alignment device 70 while being positioned and fixed by a positioning and fixing device (not shown). Note that the transfer operation of the wafer chuck 34 before the start of the contact operation is not an essential part of the present invention, so a detailed explanation will be omitted.

(Step S10: Wafer chuck fixing process)
After the wafer chuck 34 is delivered to the alignment device 70, as indicated by reference numeral 500A in Fig. 7, the chuck fixing solenoid valve control unit 112 turns on the chuck fixing solenoid valve 84 (open state) to attract and fix the wafer chuck 34 to the wafer chuck support surface 72a (see Fig. 4) of the Z-axis moving and rotating unit 72. At this time, the positioning pin 88 of the Z-axis moving and rotating unit 72 is engaged with the V-groove of the V-block 90 of the wafer chuck 34, thereby performing relative positioning between the alignment device 70 and the wafer chuck 34.

After that, when the wafer W is supplied (loaded) to the wafer chuck 34 supported and fixed by the alignment device 70, the wafer suction solenoid valve control unit 110 turns the wafer suction solenoid valve 46 ON (open state) and suction-fixes the wafer W to the wafer holding surface 34a (see FIG. 4).

(Step S12: Alignment process)
Next, under the control of the overall control unit 100, the X-axis movement control unit 102, the Y-axis movement control unit 104, and theta rotation control unit 108 control the X-axis drive motor 118, the Y-axis drive motor 120, and the rotation drive motor 124 based on the results of imaging by the needle position detection camera and the wafer alignment camera, to perform relative alignment between the wafer W held on the wafer chuck 34 and the probe card 32.

(Step S14: Suction process)
Next, the suction control unit 114 controls the operation of the vacuum electropneumatic regulator 54 to start suction through the suction port 50 (time T1 in FIG. 9). As a result, the chuck suction pressure (negative pressure applied to the suction port 50) gradually increases from pressure value 0 toward the set pressure value P1. Note that it is preferable that the timing at which the set pressure value P1 is reached is at least before or simultaneously with the timing at which the wafer chuck release process described below starts (time T3 in FIG. 9). This allows the wafer chuck 34 to be stably transferred from the alignment device 70 (Z-axis moving/rotating unit 72) to the head stage 30 (probe card 32 side).

The above-mentioned set pressure value P1 is set to a value at which the wafer chuck 34 rises to the appropriate overdrive amount (appropriate OD position H2) of the probe card 32 when the wafer chuck release process described below is performed in a state in which an internal space S (sealed space) is formed between the probe card 32 and the wafer chuck 34. The suction control unit 114 controls the operation of the vacuum electro-pneumatic regulator 54 so that the pressure (negative pressure) of the set pressure value P1 (negative pressure) is applied to the suction port 50.

The set pressure value P1 may be empirically or experimentally obtained, or may be obtained from a design value. For example, the set pressure value P1 can be determined from the reaction force (the reaction force when the probe 36 is crushed) received from the probe 36 when the wafer chuck 34 is raised to the appropriate overdrive amount of the probe card 32, and the total number of probes 36 provided on the probe card 32. If the total needle pressure of the probe card 32 (the sum of the pressures received from the probes 36) is known, the negative pressure to be applied to the internal space S can be obtained by dividing it by the area of the surface (adsorption surface) surrounded by the ring-shaped seal member 48. However, it is necessary to set the set pressure value P1 taking into account the weight of the wafer chuck 34 and the reaction force caused by crushing the ring-shaped seal member 48.

(Step S16: Z-axis raising step)
7, the Z-axis movement control unit 106 controls the Z-axis drive motor 122 to raise the Z-axis moving/rotating unit 72, thereby moving the wafer chuck 34 toward the probe card 32 (times T2 to T3 in FIG. 9). Specifically, the wafer chuck 34 is moved from a predetermined height position (standby position) H0 to the tip position (contact position) H1 of the probe 36. The Z-axis raising step is an example of a wafer chuck moving step of the present invention.

When the Z-axis lifting process is performed, as the wafer chuck 34 lifts, the ring-shaped seal member 48 comes into contact with the head stage 30 before the wafer chuck 34 reaches the contact position H1. At this time, the internal space S formed between the wafer chuck 34 and the probe card 32 is sealed off from the outside.

In this embodiment, when the wafer chuck 34 is moved toward the probe card 32 in the Z-axis lifting step, the suction step is started before the Z-axis lifting step, so that the wafer chuck 34 is not affected by the reaction force caused by the compression of the internal space S even after the ring-shaped seal member 48 comes into contact with the head stage 30 and the internal space S is sealed. This makes it possible to prevent abnormal contact between the probe card 32 and the wafer W, and to stably move the wafer chuck 34 toward the probe card 32 at a sufficient moving speed to remove the oxide film on the electrode pads.

In addition, in this embodiment, when the Z-axis rising process is performed, the suction control unit 114 preferably controls the operation of the vacuum electro-pneumatic regulator 54 by controlling the amount of suction based on the movement speed (rising speed) of the wafer chuck 34 during the Z-axis rising process.

Specifically, when the area of the surface (adsorption surface) surrounded by the ring-shaped sealing member 48 is A [ ^mm2 ] and the moving speed of the wafer chuck 34 is _Vz [mm/s], the volume (capacity) V [mm3/s] that decreases per unit time of the internal space S formed between the wafer chuck 34 and the probe card 32 as the wafer chuck 34 moves after the ring-shaped sealing member 48 comes into contact with the head stage ³⁰ is expressed by the following equation, so control is performed so that the suction amount is at least equal to or greater than the volume V.

V = A · V _z
As a result, when the wafer chuck 34 is moved toward the probe card 32, even after the ring-shaped sealing member 48 comes into contact with the head stage 30, the gas equivalent to the decrease in volume (capacity) of the internal space S caused by the movement of the wafer chuck 34 is sucked in, so that no reaction force is generated due to compression of the internal space S.

The suction process may be started at least before the ring-shaped seal member 48 comes into contact with the head stage 30 during the Z-axis raising process and the internal space S becomes sealed (see reference numeral 500B in FIG. 7). For example, the suction process may be started between the wafer chuck fixing process and the alignment process, or may be started prior to the wafer chuck fixing process. The suction process may also be started simultaneously with the wafer chuck fixing process or the alignment process.

(Step S18: Wafer chuck height determination process)
Next, the Z-axis movement control unit 106 judges whether or not the height position of the wafer chuck 34 has reached the contact position H1. This judgment is repeated until the height position of the wafer chuck 34 reaches the contact position H1, and when the height position of the wafer chuck 34 has reached the contact position H1, the process proceeds to the next step S20.

A preferred method for detecting the height position of the wafer chuck 34 is to detect the height position of the wafer chuck 34 based on the detection results of a Z-axis encoder provided on the Z-axis movement/rotation unit 72. In addition, this method is not limited to the above, and for example, a distance sensor provided on the wafer chuck 34 or the head stage 30 may be used to detect the distance (relative distance) between the wafer chuck 34 and the probe card 32, and the height position of the wafer chuck 34 may be obtained from the detection results.

(Step S20: Stopping process)
In the above-described wafer chuck height determination step (step S18), when it is determined that the height position of the wafer chuck 34 has reached the contact position H1, the Z-axis movement control unit 106 stops raising the Z-axis movement/rotation unit 72. As a result, each probe 36 of the probe card 32 comes into contact with the electrode pad of each chip on the wafer W with an overdrive amount of 0 (zero).

(Step S22: Wafer chuck release process)
Next, as shown by the symbol 500E in FIG. 8, the chuck fixing solenoid valve control unit 112 turns the chuck fixing solenoid valve 84 OFF (closed state) and releases the fixation of the wafer chuck 34 by the suction port 80 (see FIG. 4) of the Z-axis movement/rotation unit 72 (time T3 in FIG. 9).

At this time, the chuck suction pressure (pressure applied to the suction port 50 by the vacuum electropneumatic regulator 54) is at the set pressure value P1, so when the wafer chuck 34 is released from the Z-axis movement/rotation unit 72, the wafer chuck 34 is released from the Z-axis movement/rotation unit 72 and drawn toward the probe card 32 to the correct OD position H2 (T3-T4 in FIG. 9). This ensures that the electrode pads of each chip on the wafer W to be inspected and each probe 36 on the probe card 32 come into contact with each other at a predetermined contact pressure, without being affected by the inclination of the wafer W relative to the arrangement surface of the tips of the probes 36 or the variation in the tip positions of the probes 36.

In this manner, in this embodiment, the wafer chuck 34 is released while negative pressure is applied to the internal space S, so that at the moment of switching between these processes, the wafer chuck 34 is never in a state where it is not fixed to either side (a free state), and the wafer chuck 34 can be transferred stably.

In addition, in this embodiment, the suction path connecting the suction path 82 of the Z-axis moving/rotating part 72 and the chuck fixing solenoid valve 84 is provided with a throttle valve 86, so that even if the wafer chuck 34 is released from the fixed position after the internal space S is depressurized, the negative pressure on the lower side (the Z-axis moving/rotating part 72 side) of the wafer chuck 34 is not suddenly lost. Therefore, when the wafer chuck 34 is pulled from both the upper and lower sides (i.e., both sides of the Z-axis moving/rotating part 72 and the probe card 32), the constraint from the lower side (i.e., the fixing force due to suction from the Z-axis moving/rotating part 72) is not suddenly lost, so that abnormal vibrations and abnormal contacts caused by the sudden movement of the wafer chuck 34 can be reduced. Therefore, the wafer chuck 34 can be prevented from suddenly detaching from the Z-axis moving/rotating part 72 when the wafer chuck fixing release process is performed, so that the transfer operation of the wafer chuck 34 can be performed more stably.

In this embodiment, as an example, a configuration in which a throttle valve 86 is provided in the suction path connecting the suction path 82 of the Z-axis moving/rotating unit 72 and the chuck fixing solenoid valve 84 is shown, but it is sufficient that the throttle valve 86 is provided in the path connecting the suction port 80 of the Z-axis moving/rotating unit 72 and the suction device 44, and for example, the throttle valve 86 may be provided in the suction path 82 of the Z-axis moving/rotating unit 72.

(Step S24: Z-axis lowering process)
Next, as indicated by reference symbol 500F in FIG. 8, the Z-axis movement control unit 106 controls the Z-axis drive motor 122 to lower the Z-axis movement/rotation unit 72 to a predetermined height position (standby position) (times T5 to T6 in FIG. 9).

When the wafer chuck 34 is transferred from the alignment device 70 (Z-axis movement/rotation unit 72) to the head stage 30 (probe card 32 side) in this manner, each probe 36 of the probe card 32 comes into contact with the electrode pads of each chip on the wafer W with uniform contact pressure, and the wafer-level inspection is ready to begin. After that, power and test signals are supplied from the test head to each chip on the wafer W via each probe 36, and electrical operation inspection is performed by detecting the signals output from each chip.

After the wafer chuck 34 is transferred from the alignment device 70 (Z-axis movement/rotation unit 72) to the head stage 30 (probe card 32 side), the alignment device 70 moves to another measurement unit 16, where the contact operation is performed in the same procedure, and wafer-level inspection is performed sequentially.

Next, we will explain the effects of this embodiment.

According to this embodiment, the operation of moving the wafer chuck 34 to the contact position H1 is performed by the Z-axis movement/rotation unit 72, and the overdrive thereafter is performed by vacuum suction due to the reduced pressure in the internal space S. As a result, the contact operation by the Z-axis movement/rotation unit 72 is limited to the extent of removing the oxide film on the electrode pads, so good contact can be achieved between the electrode pads on the wafer and the probes without damaging the wafer W.

In addition, according to this embodiment, the suction process is started before the Z-axis lifting process is performed (more precisely, at least before the ring-shaped seal member 48 comes into contact with the head stage 30 and the internal space S is sealed), so that when the wafer chuck 34 is moved toward the probe card 32 in the Z-axis lifting process, it is not affected by the reaction force due to the compression of the internal space S even after the ring-shaped seal member 48 comes into contact with the head stage 30 and the internal space S is sealed. Therefore, since no excessive reaction force (a reaction force that tries to return the wafer chuck 34 to its original position) is generated in the wafer chuck 34, abnormal contact between the probe card 32 and the wafer W can be prevented, and defects such as damage to the probe card 32 and the wafer W can be prevented. In addition, it is possible to stably, efficiently, and accurately move the wafer chuck 34 toward the probe card 32 at a moving speed sufficient to remove the oxide film on the electrode pad. Therefore, good contact can be achieved between the electrode pads on the wafer W and the probes 36 without providing a shutter means in the wafer chuck 34.

In this embodiment, as an example of a preferred embodiment, the suction process is started before the Z-axis raising process is performed. However, this is not necessarily limited to this embodiment. For example, as shown in FIG. 10, the suction process may be started simultaneously with (or after) the Z-axis raising process. Also, as shown in FIG. 11, the suction process may be started simultaneously with (or after) the timing at which the Z-axis raising process is completed (i.e., the timing at which the wafer chuck release process is performed).

In addition, in this embodiment, there is no need to provide a shutter means on the wafer chuck 34, so the wafer chuck 34 does not have any components of the shutter means that act as heat dissipation elements, and the effect on the temperature distribution of the wafer chuck 34 can be eliminated. In addition, the elimination of the effect on the temperature distribution of the wafer chuck 34 improves the flatness of the wafer holding surface 34a of the wafer chuck 34. This allows the parallelism between the wafer W and the probe card 32 to be improved, making it possible to perform wafer-level inspection with high accuracy. In addition, the number of parts mounted on the wafer chuck 34 can be reduced, making it easier to balance the weight of the wafer chuck 34. As a result, it becomes possible to stably perform contact operations using the vacuum suction method without disrupting the weight balance of the wafer chuck 34.

In this embodiment, as an example of a preferred embodiment, a mode in which the wafer chuck 34 is not provided with a shutter means is shown, but this is not necessarily limited to this mode, and the wafer chuck 34 may be provided with a shutter means. The shutter means provided on the wafer chuck 34 is described in the above-mentioned Patent Document 1, so a description thereof will be omitted here.

In addition, in this embodiment, a negative pressure is applied to the internal space S before the wafer chuck release process is performed. Therefore, when the wafer chuck 34 is released from the suction port 80 (see FIG. 4) of the Z-axis moving/rotating unit 72 in the wafer chuck release process, the unstable state (free state) in which the wafer chuck 34 is not fixed to either side at the moment of switching between these processes is eliminated, and the wafer chuck 34 can be transferred stably.

In this embodiment, as an example of a preferred embodiment, the chuck suction pressure is set to the set pressure value P1 before the wafer chuck release process is performed. However, this is not necessarily limited to this embodiment. For example, as shown in FIG. 10 and FIG. 11, the chuck suction pressure may be set to the set pressure value P1 after the wafer chuck release process is performed.

In this embodiment, the Z-axis moving/rotating unit 72 may move the wafer chuck 34 up and down (in the Z direction) between the contact position and a position below the contact position to bring the electrode pads on the wafer W into contact with the probes 36 multiple times. The Z-axis moving/rotating unit 72 in this embodiment is configured with a mechanical drive mechanism including at least a motor (Z-axis drive motor 122), so that the moving distance and moving speed of the wafer chuck 34 can be adjusted with high precision. In addition, the Z-axis moving/rotating unit 72 can move the wafer chuck 34 at a moving speed that is sufficiently faster than the case where the wafer chuck 34 is moved toward the probe card 32 by reducing the pressure of the internal space S. Therefore, when the electrode pads on the wafer W are brought into contact with the probes 36, the oxide film (insulator) on the electrode pads can be removed by the contact of the probes 36, and good contact can be achieved between the electrode pads on the wafer W and the probes 36 without damaging the wafer W.

In addition, in this embodiment, a throttle valve 86 that limits the flow rate of gas is provided in the path connected to the suction port 80 of the Z-axis moving/rotating unit 72. This makes it possible to prevent the wafer chuck 34 from suddenly detaching from the Z-axis moving/rotating unit 72 when the chuck fixing solenoid valve 84 is turned OFF (when open to the atmosphere), making it possible to perform the transfer operation of the wafer chuck 34 more stably.

The prober and probe inspection method according to the present invention have been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the spirit of the present invention.

10... prober, 12... measurement unit, 14... loader section, 16... measurement section, 18... load port, 20... wafer cassette, 22... operation panel, 24... transport unit, 26... transport arm, 30... head stage, 32... probe card, 34... wafer chuck, 34a... wafer holding surface, 36... probe, 40... suction port, 42... suction path, 44... suction device, 46... solenoid valve for wafer suction, 48... ring-shaped seal member, 50... suction port, 54... vacuum electro-pneumatic regulator, 56... communication path, 60... control device, 70... alignment device, 72... Z-axis movement/rotation section, 72a... wafer chuck support surface, 74... X-axis movement stage, 76 ...Y-axis moving stage, 78...ring-shaped seal member, 78...ring-shaped seal member, 80...suction port, 82...suction path, 84...electromagnetic valve for fixing chuck, 86...throttle valve, 88...positioning pin, 90...V-block, 92...Z-axis moving mechanism, 94...θ rotation mechanism, 100...overall control unit, 102...X-axis moving control unit, 104...Y-axis moving control unit, 106...Z-axis moving control unit, 108...θ rotation control unit, 110...electromagnetic valve for suction of wafer, 112...electromagnetic valve for fixing chuck, 114...suction control unit, 118...X-axis driving motor, 120...Y-axis driving motor, 122...Z-axis driving motor, 124...rotation driving motor, W...wafer, S...internal space

Claims (4)

a wafer chuck for holding the wafer;
a probe card having a plurality of probes on a surface facing the wafer chuck;
a mechanical lifting means for lifting and lowering the wafer chuck;
a suction means for suction-holding the wafer chuck to the probe card side by reducing the pressure in an internal space between the wafer chuck and the probe card;
a lift control means for controlling a lift operation by the mechanical lift means, the lift control means moving the wafer chuck to a contact position where the probes come into contact with the electrode pads of the wafer;
a suction control means for controlling a suction operation by the suction means, the suction control means moving the wafer chuck from the contact position to an overdrive position where the probe contacts the electrode pad of the wafer in an overdrive state;
Equipped with
the movement of the wafer chuck within the overdrive range is performed by reducing the pressure in the internal space by the suction means, not by the mechanical lifting means;
The suction control means starts a suction operation by the suction means before the internal space is sealed ,
after starting the suction operation by the suction means, the mechanical lifting means raises the wafer chuck to seal the internal space;
Prover. the suction control means sets the amount of suction by the suction means based on the moving speed of the wafer chuck by the mechanical lifting means.
2. The prober of claim 1. a wafer chuck for holding the wafer;
a probe card having a plurality of probes on a surface facing the wafer chuck;
a mechanical lifting means for lifting and lowering the wafer chuck;
a suction means for suction-holding the wafer chuck to the probe card side by reducing the pressure in an internal space between the wafer chuck and the probe card;
A probe inspection method in a prober comprising:
a wafer chuck moving step of moving the wafer chuck toward the probe card by the mechanical lifting means to a contact position where the probes contact the electrode pads of the wafer;
a step of reducing the pressure of the internal space by the suction means, the suction step being for moving the wafer chuck from the contact position to an overdrive position where the probes contact the electrode pads of the wafer in an overdrive state;
Equipped with
the movement of the wafer chuck within the overdrive range is performed by reducing the pressure in the internal space by the suction means, not by the mechanical lifting means;
The suction operation by the suction means is started before the internal space is sealed ,
after starting the suction operation by the suction means, the mechanical lifting means raises the wafer chuck to seal the internal space;
Probe testing method. the suction step sets a suction amount by the suction means based on a moving speed of the wafer chuck by the mechanical lifting means;
The probe inspection method according to claim 3 .

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