JPH0536768A - Probe apparatus - Google Patents

Abstract

PURPOSE:To prevent a drop, in the accuracy of a needle alignment operation, which is caused due to an irregularity in the mounting state of a body to be inspected by a method wherein a target which is used to align a first optical position detection means with a second optical position detection means is installed in the peripheral part of a chuck. CONSTITUTION:The following are fixed to an alignment bridge 11: a fixed camera 13 used to detect the position of a chip formed on a semiconductor wafer, and an electrostatic-capacity type sensor 14 used to detect the height of the surface or the like of the wafer. An ascending and descending mechanism 24 is fixed to the side face of a Y-stage 21b, and the ascending and descending mechanism 24 holds a moving camera 23 which can be raised and lowered freely in the up-and-down direction. A small piece 25 on which a target 25a has been formed is installed on the side face of a chuck. Thereby, the positional relationship caused by an irregularity in the mounting state of the wafer can be corrected, and the accuracy of an automatic needle alignment operation can be enhanced. When the alignment operation not only in the horizontal plane but also in the height direction is executed and the camera is focused, the reliability of an inspection can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe device used for inspection of semiconductor wafers.

[0002]

2. Description of the Related Art A plurality of chips, which are regularly arranged at regular intervals, are formed on the surface of an object to be inspected, for example, a semiconductor wafer, and various signal lines in the chips are provided at predetermined places in each chip. A plurality of continuous pads are formed. The electrical characteristics of the chip are inspected while the corresponding probe needles of the inspection device are in contact with each pad in the chip, and the defective chip is identified by marking or the like. Usually, a probe device is combined with this type of inspection device in order to automate the inspection.

The latest version of this probe device is a chuck that holds a semiconductor wafer to be inspected and that can move up and down in the vertical direction, a stage that holds this chuck and that can move in a horizontal plane, and a chuck that holds this chuck. A fixed camera fixed on the alignment bridge side to detect the position of any chip arranged on the surface of the semiconductor wafer of
And a moving camera for detecting the position of a probe needle that is held on the stage so as to be able to move up and down and is brought into contact with a predetermined position in a chip formed on the surface of the semiconductor wafer.

[0004]

The above-mentioned conventional automatic needle alignment device is premised on that the positional relationship (distance) between the tip detected by the fixed camera and the moving camera detecting the probe needle is constant. There is. However, the above positional relationship may slightly change due to expansion and contraction of the wafer or chuck due to thermal expansion or contraction when inspecting at high temperature or low temperature, or variation in the mounting state of the wafer on the chuck. However, there is a problem in that the accuracy of needle matching is reduced accordingly.

[0005]

SUMMARY OF THE INVENTION The automatic needle alignment apparatus of the present invention has a position and height in the horizontal plane of an arbitrary chip arranged on the surface of an object to be inspected such as a semiconductor wafer held by a chuck on a stage. A first optical position detecting means for optically detecting the position of the probe needle held on the stage and brought into contact with a predetermined position in the chip formed on the surface of the object to be inspected in the horizontal plane. It is provided with a second optical position detecting means for detecting, and a target which is provided in the peripheral portion of the chuck and is used for alignment and focusing between the first and second optical position detecting means. The operation of the present invention will be described in detail with the following examples.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing the structure of an automatic needle alignment device according to an embodiment of the present invention, 11 is an alignment bridge, 12 is a probe card, 13 is a fixed camera, 14 is a capacitance type sensor, 21 is a stage, 22 is a chuck,
Reference numeral 23 is a moving camera, and 24 is an elevating mechanism for the moving camera. That is, in this embodiment, the semiconductor wafer is the object to be inspected, the fixed camera 13 is the first optical position detecting means, and the moving camera 2 is the second optical position detecting means.
3 are illustrated respectively. Further, X, Y, and Z are orthogonal coordinate systems set in the drawing for convenience of explanation. In addition,
This kind of automatic needle alignment device includes a conventional mechanism such as a drive mechanism for a stage or a chuck, or a processor for controlling the drive mechanism, a camera, a prober, etc. and processing data fetched from them. Since the structure of these conventional parts is well known, illustration thereof is omitted to avoid complication.

Both the alignment bridge 11 and the probe card 12 are fixed to the prober of the inspection apparatus. A fixed camera 13 for detecting the position of a chip formed on a semiconductor wafer and a capacitance type sensor 14 for detecting the height of the wafer surface are fixed to the alignment bridge 11. Probe card 1
An opening is formed in the central portion of 2, and a large number of probe needles are projected obliquely downward from the peripheral portion of the opening.

The stage 21 is an X stage 21a which is movable in the X direction along two rails extending in the X direction.
And a Y stage 21b movable on the X stage 21a in the Y direction along two rails extending in the Y direction.
It consists of and. This X, Y stage 21a, 2
1b can be freely moved in the X and Y directions within a horizontal plane by a conventional drive mechanism including a pulse motor and the like. The chuck 22 mounted on the Y stage 21b is
It is freely raised and lowered in the vertical direction (Z direction) by a conventional lifting mechanism, and is freely rotated by a conventional rotating mechanism around a center line passing through the center and parallel to the Z axis.

A lifting mechanism 24 is provided on the side surface of the Y stage 21b.
Is fixed, and a moving camera 23 that can move up and down is held in the lifting mechanism 24. The moving camera 23 is composed of a high magnification section and a low magnification section. A small piece 25 that horizontally projects in the radial direction is fixed to the side surface of the chuck 22. This small piece 25 is shown in FIG.
As shown in the enlarged perspective view of FIG.
5b, a target 25a defined by the center of a cross mark drawn by using a conductive thin film such as an ITO thin film or chrome on the surface of the glass piece 25b, and a conductive transparent metal that covers the periphery of the cross thin film. , For example IT
It is composed of an O thin film 25c. Target 25
The small piece 25 on which a is formed can be moved on the optical axis of the high-magnification portion of the moving camera 23 by the rotation of the chuck 22 and can be retracted therefrom.

The chuck 22 is conveyed to a specific place such as near the wafer cassette by the driving mechanism of the stage 21, and the semiconductor wafer to be inspected placed on the chuck 22 is placed on the chuck 22 by a vacuum suction mechanism or the like. Retained. As shown in FIG. 3, the chuck 22 on which the semiconductor wafer W to be inspected is mounted is fixed on the fixed camera 13 of the alignment bridge 11 by the drive mechanism of the stage 21.
Be transported below. Here, the target 25 a is moved by the rotation of the chuck 22 so that the high magnification portion 23 of the moving camera 23 is moved.
Positioned near the center of the field of view of a, the chuck rotation angle (θ0) is stored.

Next, as shown in FIG.
The stage 21 is positioned in the (X, Y) plane so that a is located at the center of the visual field of the fixed camera 13. In this positioning, the height of the chuck 22 is adjusted so that the sharpness of the image of the target 25a is maximized, so that the target 25a is positioned at the focal point of the fixed camera 13. Then, target 2
The height of the moving camera 23 is adjusted by the elevating mechanism 24 so that the sharpness of the image of 5a is maximized, so that the target 25a is positioned at the focal point of the lens of the moving camera 13. With this positioning completed,
The centers and the focal points of the fields of view of the fixed camera 13 and the moving camera 23 are matched with each other with the target 25a interposed. In this state, the coordinate positions (X, Y, Z) in the (X, Y, Z) coordinate system of the stage 21 and the chuck 22 by the drive mechanism are set.
0, Y0, Z0) and the height (h0) of the moving camera 23 in the lifting system by the lifting mechanism 24 are read by the processor,
Retained.

When the alignment of the fixed camera 13 and the movable camera 23 is completed, the stage 22 is moved in the (X, Y) direction as shown in FIG. An image of the chip C to be inspected is captured by the fixed camera 13. The stage 21 is positioned in the (X, Y) plane such that a specific portion of the captured image of the chip C is located near the center of the visual field of the fixed camera 13. In parallel with this, chip C
By adjusting the height of the chuck 22 to a state in which the sharpness of the image of the specific portion of 10 is maximized, the specific portion is positioned at the focus of the fixed camera 13. With this positioning completed, the stage 2 by the drive mechanism
1 or the amount of movement of the chuck 22 from the origin (X1, Y1, Z
1) is read by the processor. On the processor, Dx
= LX1-X01, Dy = lY1-Y01, Dz = lZ
1-Z01 is calculated and saved. As can be seen by comparing FIGS. 3 and 4 with each other, as described above, (Dx, Dy,
Each of Dz) is nothing but the (X, Y, Z) component of the distance between the target 25a and the specific portion of the chip C.

Next, as shown in FIG. 5, after the chuck 22 is rotated and the target 25a is retracted out of the field of view of the moving camera 23, the chuck 22 is conveyed below the probe card 12 by the drive mechanism of the stage 21. Then, the image of the probe card 12 is captured by the moving camera 23. The image of the tip portion of the specific probe needle included in the captured image of the probe card 12 is positioned at the approximate center of the visual field of the moving camera 23 (X, Y).
Positioning of the stage 21 in the plane is performed. At the time of this positioning, first, rough positioning is performed by the low-magnification section 23b of the moving camera 23, and then highly accurate positioning is performed by the high-magnification section 23a. This (X,
Y) In parallel with the in-plane positioning, the height of the moving camera 23 is adjusted by the elevating mechanism 24 to a state where the sharpness of the image of the tip portion of the specific probe needle is maximized. The tip portion is positioned at the focal point of the moving camera 13.

When this positioning is completed, the chuck 25
The rotation angle of is returned to θ0. With this positioning completed, the amount of movement (X2, Y2) of the stage 21 from the origin by the drive mechanism and the height (h2) of the moving camera 23 by the elevating mechanism 24 are read by the processor, and (h
2-h0) -Dz is calculated. Where (h2-h
0) is the target 2 detected by the moving camera 23.
5a to the tip portion of a specific probe needle, and Dz is the height from the target 25a to the chip C on the wafer surface as described above. Next, from the current coordinate position (X2, Y2, Z2 to (Dx, Dy, (h2-h0)
Only −Dz + δZ), where δZ> 0, the stage 21 is fed in the (X, Y) direction and the chuck 22 is fed in the Z direction. When the feeding in the horizontal and vertical directions is completed, the specific portion of the chip C (specific pad in this example) is δ on the tip portion of the specific probe needle of the probe card 12.
Contact while maintaining an appropriate contact pressure due to Z (> 0). At the same time, the other pads in the chip C are also brought into contact with the tip portions of the corresponding probe needles of the probe card 12 with an appropriate contact pressure to complete automatic needle alignment, and subsequently the inspection of the electrical characteristics by the inspection device is started. It

When the automatic needle alignment and the inspection of the electrical characteristics for the first chip C are completed in this way, the chuck 22 moves while the horizontal movement amount of the stage 21 is increased or decreased by a value equal to the chip interval. By raising and lowering between the contact height and the contact release height that is lower than the contact height by a predetermined value, automatic needle alignment is sequentially repeated for all chips to be inspected while interposing an inspection process of electrical characteristics.

In this way, when the inspection of all the chips of the first semiconductor wafer is completed, the chuck 22 is conveyed to the vicinity of the wafer cassette or the like, and the new semiconductor wafer to be inspected next is held therein. At the time of automatic needle alignment with this new semiconductor wafer, the target 25
Distance between a and a specific part of the chip C (Dx, Dy, Dz)
Has already been detected during the first automatic needle alignment of the wafer, the alignment between the fixed camera 13 field of view and the movable camera 23 field of view shown in FIG. Then, the positioning of the chip C shown in FIG. 4 can be started immediately. Similarly, for the third and subsequent new wafers, the process of aligning the field of view of the camera in FIG. 3 can be omitted.

However, due to the expansion and contraction of the semiconductor wafer and the chuck due to the thermal expansion and contraction when the inspection is performed in the high temperature or the low temperature, or the variation in the mounting state of the wafer on the chuck, the distance ( Dx, Dy, D
If z) fluctuates, the accuracy of needle matching decreases. Therefore, in the probe device of the present invention, the best measure is to perform all the wafers to be inspected, and the second best method is to perform the alignment between the fields of view of the cameras shown in FIG. The distance (Dx, Dy, Dz) between the target 25a and the chip C is detected and updated to the latest value.

According to another embodiment of the present invention, the height of the target 25a surrounded by the conductive transparent thin film is detected with high accuracy by the capacitance type sensor 14, and the height of the target 25a is detected by the fixed camera 13. The height and the height of the chip surface are calibrated based on the value detected by the capacitance type sensor 14. Thereafter, the calibrated value is used to detect the target 25a and the chip height by the fixed camera 13. With this configuration, the heights of the chip and the target can be detected with high accuracy only by the fixed camera 13 and the moving camera 23. As a result, the time for automatic needle alignment is shortened as compared with the case where the position detection in the horizontal plane for each wafer is performed by the cameras 13 and 23 and the height detection is performed by the capacitance type sensor 14. This is because focusing is required to maintain the accuracy even in the position adjustment in the horizontal plane, and thus the fixed camera 13 does not substantially spend time for detecting the height.

In the above, the configuration has been exemplified in which the specific portion in the chip or the tip portion of the specific probe needle of the probe card is placed in the center of the visual field of the fixed camera or the moving camera to perform the positioning. However, such a positioning may be performed by pattern matching using a characteristic key pattern formed on the surface of the inspection object.

The fixed camera 13 is used to detect the position (X1, Y1, Z1) of the chip to be inspected first. However, instead of such an actual chip, a dummy chip including a specific pattern suitable for position detection is created at a specific location on the wafer, and the fixed camera 13 is used to detect the position of the dummy chip. The position (X1, Y1, Z1) of the first chip to be inspected from the detection result and the predetermined positional relationship on the wafer.
May be calculated.

Further, the structure in which the height of the chip surface and the height of the target are detected by the fixed camera 13 while raising and lowering the chuck has been illustrated, but by using the zoom mechanism of the lens system of the fixed camera 13, the height of the chip surface can be increased. And the height of the target may be detected. Similarly, as for the moving camera 23, instead of providing the elevating mechanism 24, a zoom mechanism of a lens system is used to make the target 2
It is also possible to adopt a configuration in which focusing is performed on 5a or the tip portion of the probe needle.

Although the semiconductor wafer has been exemplified as the object to be inspected, the probe device of the present invention can be applied to other suitable objects to be inspected such as a liquid crystal substrate.

As described in detail above, the probe device of the present invention has a fixed camera for detecting the position and height of the tip and a fixed camera for detecting the position and height of the probe needle. Since the moving camera is aligned and focused using the target provided on the chuck, the wafer or chuck expands or contracts due to thermal expansion when inspecting at high temperature or low temperature, or onto the chuck. It is possible to correct variations in the positional relationship due to variations in the mounting state of the wafer, and the accuracy of automatic needle alignment is greatly improved.

Further, according to the probe apparatus of the present invention, not only the positioning in the horizontal plane but also the positioning in the height direction is performed, and the positioning accuracy in the height direction is enhanced by the focusing of the camera using the target. Therefore, there is an advantage that the contact pressure between the pad in the chip and the probe needle becomes constant and the reliability of the inspection is improved.

Further, according to the probe device of another embodiment of the present invention, by making the target conductive, it is possible to detect the height by the capacitance type sensor, whereby the height detection value by the camera is detected. Since it is calibrated, it is possible to perform the alignment in the horizontal direction and the height direction with high accuracy only by the camera, and there is an effect that the time for needle alignment is shortened.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of only a portion of the probe device according to an embodiment of the present invention that is necessary for explanation.

FIG. 2 is a target 25 formed on the small piece 25 of FIG.
It is a perspective view which shows an example of the structure of a.

FIG. 3 is a perspective view for explaining alignment of visual fields of a fixed camera 13 and a moving camera 23.

FIG. 4 is a perspective view for explaining detection of a chip position on a wafer to be inspected using a fixed camera 13.

5 is a perspective view for explaining the detection of the position of the probe needle of the probe card 12 by the moving camera 23. FIG.

[Explanation of symbols]

11 alignment bridge 12 probe cards 13 Fixed camera (first optical position detecting means) 14 Capacitive sensor 21 stages 22 chuck 23 Moving camera (second optical position detecting means) 24 Moving camera lifting mechanism 25 Small piece with target 25a formed on the surface W Inspected semiconductor wafer C Chips arranged on the semiconductor wafer to be inspected

Claims (2)

[Claims] 1. A chuck which holds an object to be inspected provided with a plurality of chips on a surface and can be raised and lowered in a direction perpendicular to the surface, and a plane which holds the chuck and is parallel to the surface of the chuck. A movable stage; first optical position detecting means for optically detecting the position and height in the plane of an arbitrary chip arranged on the surface of the object to be inspected held by the chuck; Second optical position detecting means for detecting the position and height in the plane of the probe needle held on the stage and brought into contact with a predetermined position in the chip formed on the surface of the object to be inspected; And a target used for aligning and focusing the first and second optical position detecting means with each other. 2. A chuck which holds an object to be inspected provided with a plurality of chips on a surface and can be raised and lowered in a direction perpendicular to the surface, and a plane which holds the chuck and is parallel to the surface of the chuck. A movable stage; first optical position detecting means for optically detecting the position and height in the plane of an arbitrary chip arranged on the surface of the object to be inspected held by the chuck; Second optical position detecting means for detecting the position and height in the plane of the probe needle held on the stage and brought into contact with a predetermined position in the chip formed on the surface of the object to be inspected; A conductive target which is provided on the peripheral portion of the first optical position detecting means and is used for alignment and focusing of the first and second optical position detecting means, and a chip detected by the first optical position detecting means. High To detect the heights of the conductive targets detected during focusing of the first optical position detecting means. And the probe device.