JPH0536767A - 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 wafer 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 11 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, an automatic needle alignment operation can be realized with high accuracy. In addition, it is possible to shorten the time required for an alignment operation.

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 probe device is premised on that the positional relationship (distance) between the chip detected by the fixed camera and the moving camera detecting the probe needle is constant. However, the expansion and contraction of the wafer and the chuck due to the thermal expansion when performing the inspection in a high temperature or low temperature state, or the variation of the above-mentioned positional relationship due to the variation of the mounting state of the wafer on the chuck, etc., Along with this, there is a problem that the accuracy of needle matching is lowered.

[0005]

The probe device of the present invention is a first optical device for optically detecting a position in a horizontal plane of an arbitrary chip arranged on the surface of an object to be inspected which is being held by a chuck on a stage. An optical position detecting means, and a second optical position detecting means for detecting a position in a horizontal plane of a probe needle held on the stage and brought into contact with a predetermined position in a chip formed on the surface of the object to be inspected, A target fixed to the periphery of the chuck and used to align the first and second optical position detecting means with each other. The operation of the present invention will be described in detail with the following examples.

[0006]

1 is a perspective view showing the configuration of a probe device according to an embodiment of the present invention, in which 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, 23
Is a moving camera, and 24 is a lifting mechanism for the moving camera. In this embodiment, a semiconductor wafer is illustrated as an object to be inspected, a fixed camera 13 is illustrated as the first position detecting means, and a moving camera 23 is illustrated as the second optical position detecting means. Further, X, Y, and Z are orthogonal coordinate systems set in the drawing for convenience of explanation. It should be noted that this type of probe 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, and the like, and processing data captured from these. 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 conductive thin film on the surface of the glass piece 25b, for example, a target 25a defined by the center of a cross mark drawn by using an ITO thin film or chrome, and a conductive transparent thin film 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. 4, and the semiconductor wafer W is first inspected. The image of the chip C to be captured 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 and the coordinate position (X1, Y1, Z1) of the chuck 22 is read by the processor. In the processor, Dx = 1x1
-X01, Dy = lY1-Y01, Dz = lZ1-Z0
l is calculated and saved. As will be apparent by comparing FIG. 3 and FIG. 4, each of the above (Dx, Dy, Dz) is the (X, Y, Z) component of the distance between the target 25a and the specific portion of the chip C. Nothing else.

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 stage 21 is positioned in the (X, Y) plane so that the image of the tip portion of the specific probe needle included in the captured image of the probe card 12 is located at the center of the visual field of the moving camera 23. In this positioning, first, the low magnification portion 23 of the moving camera 23
The rough positioning by b is performed, and then the high magnification portion 23
Highly accurate positioning is performed by a. This (X, Y)
In parallel with the in-plane positioning, the elevating mechanism 24 reaches a state where the sharpness of the image of the tip portion of the specific probe needle is maximized.
The height of the moving camera 23 is adjusted by this, and the tip portion of this specific probe needle is positioned at the focal point of the moving camera 13.

When this positioning is completed, the chuck 25
The rotation angle of is restored to θ0. When this positioning is completed, the coordinate position (X2, Y2) of the stage 21 by the drive mechanism and the moving camera 23 by the elevating mechanism 24 are moved.
The height of (h2) is read by the processor and (h2-h
0) -Dz is calculated. Here, (h2-h0) is the height from the target 25a detected by the moving camera 23 to the tip portion of the specific probe needle, and Dz is the height from the target 25a to the chip C on the wafer surface as described above. That's it. Next, the current coordinate position (X2, Y
2, Z2) to (Dx, Dy, (h2-h0) -Dz +
δZ), where δZ> 0, only (X,
The feeding in the Y direction and the feeding of the chuck 22 in the Z direction are performed. When the feeding in the horizontal and vertical directions is completed, the specific portion of the chip C (specific pad in this example) is δZ (>) at the tip portion of the specific probe needle of the probe card 12.
Contact is made while maintaining an appropriate contact pressure due to 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.

When the inspection of all the chips of the first wafer is completed in this way, the chuck 22 is conveyed to the vicinity of the wafer cassette or the like, and a new wafer to be inspected next is placed there. In this automatic alignment of the new wafer, the distance (Dx, Dy, Dz) between the target 25a and the specific portion of the chip C has already been detected in the automatic alignment of the first wafer. Therefore, if the accuracy of needle alignment does not pose a problem, the alignment of the visual field of the fixed camera 13 and the visual field of the moving camera 23 shown in FIG. 3 is omitted, and the positioning of the chip C shown in FIG. 4 is immediately performed. You can also start. 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, the above distance (caused by the expansion or contraction of the wafer or the chuck due to the thermal expansion or contraction in the case of performing the inspection in the high temperature or the low temperature state, or the variation in the mounting state of the wafer on the chuck). If Dx, Dy, Dz) fluctuates, the accuracy of needle matching decreases. Therefore, in the probe apparatus of the present invention, as a best measure, all the wafers to be inspected, and as a suboptimal method, the alignment between the cameras shown in FIG. , The distance between the target 25a and the chip C (D
x, Dy, Dz) is detected and updated to the latest value.

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.

An example in which the height of the tip surface and the height of the tip of the probe needle are detected by the fixed camera 13 and the moving camera 23, respectively, and the lifting height of the chuck required to bring them into contact with each other is calculated. explained. However, considering the elasticity of the probe needle, there is no problem if the chuck rise value at the time of contact is too large, so the height detection by the fixed camera and the moving camera is omitted, and only a large fixed value of the chuck is made at the time of contact. It can also be raised.

Although the semiconductor wafer is exemplified as the object to be inspected, other suitable object to be inspected such as a liquid crystal substrate may be used.

As described in detail above, the probe device of the present invention is used for aligning a fixed camera for alignment with a moving camera for detecting the position of a probe needle in a horizontal plane. Since it is equipped with a target, it is possible to realize highly accurate automatic needle alignment.

Further, since the moving camera is composed of a low-magnification portion for rough alignment and a high-magnification portion for highly accurate alignment, the time required for alignment can be greatly reduced. it can.

[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 shows a fixed camera 13 (first optical position detecting means).
FIG. 6 is a perspective view for explaining the alignment of the moving camera 23 (second optical position detecting means).

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 wafer C Chips arranged on the 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; and a first optical position for optically detecting a position in the plane of an arbitrary chip arranged on the surface of an object to be inspected, which is held by the chuck.
Optical position detecting means, and a second optical position for detecting a position in the plane of the probe needle held by the stage and brought into contact with a predetermined position in a chip formed on the surface of the object to be inspected. A probe apparatus comprising: a detection means; and a target provided on the chuck and used for aligning the first and second optical position detection means with each other. 2. The probe device according to claim 1, wherein the second optical position detecting means comprises a low magnification portion and a high magnification portion.