JP2004063877A - Wafer-positioning correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer-positioning correction method for correcting alignment of an electrode pad and a probe, by observing a track of the probe on the electrode pad of a semiconductor device. <P>SOLUTION: In the method for correcting position deviation of an electrode pad 10a of a wafer 10 and a probe 4a of a probe card 4 in a probe unit 1, the track of the probe on the electrode pad is observed by a color camera 8, it is decided whether the track is positioned properly on the electrode pad; and when the position of the track deviates from a proper position, the position deviation is corrected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for correcting the alignment between an electrode pad of a semiconductor device and a stylus connected to a tester in a probe device for measuring electrical characteristics of a large number of semiconductor devices formed on a wafer.
[0002]
[Prior art]
Many semiconductor devices on which the same electric element circuits are formed are formed on the surface of the wafer. Before cutting the electric element circuits into individual semiconductor devices (chips), the electric characteristics of each electric element circuit are determined. In order to inspect for defects, the quality is determined by a probe device. This probe device generally has a stylus corresponding to each semiconductor device on a wafer, and sequentially associates a probe card connected to a tester with each semiconductor device on the wafer, and puts a stylus on an electrode pad of the semiconductor device. It is configured to make electrical measurement by making contact.
[0003]
By the way, in order to perform accurate electrical measurements, the probe pads of the probe card must be securely brought into contact with the electrode pads of the semiconductor device. Therefore, the stage on which the wafer is mounted is controlled with high accuracy, and the measurement is performed. It is necessary to accurately align the electrode pad with the stylus beforehand. For this reason, in the conventional probe device, a probing area in which an electrode pad of a semiconductor device is brought into contact with a probe of a probe card to perform an electrical characteristic test, and a test head in which a probe card having a probe is detachably fixed. An imaging means (alignment device) having a CCD camera is arranged at a distant position, and an alignment (alignment) area for aligning a wafer below the imaging means is arranged at a constant distance in a plane. Have been. Therefore, the chuck portion of the stage to which the wafer is supplied first moves to the alignment area to position the wafer, and then the moved wafer is moved to the probing area immediately below the stylus by moving the stage. In this case, an electrical measurement is performed. For this reason, a mechanical error of a moving mechanism for moving the stage or the like is included in the moving amount, so that there has been a problem that incorrect positioning is performed.
[0004]
On the other hand, the camera used for the imaging means (alignment device) uses a monochrome camera with high resolution because it needs to perform high-precision positioning. However, in this monochrome camera, when the electrode pads of the semiconductor device are gold bumps, solder bumps, aluminum bumps, or the like, there is a disadvantage that the needle mark on the pad, which is the contact mark between the electrode pad and the stylus, cannot be seen. there were. Therefore, the wafer after the alignment is moved to the probing area, and after probing the first semiconductor device on the wafer, it is determined whether the stylus is in contact with the correct position on the electrode pad of the semiconductor device. However, even if the inspection is performed using the needle trace, the monochrome camera cannot observe the needle trace, and it is difficult to correct the contact position between the stylus and the electrode pad. Conventionally, since the trace of the needle is not visible, the probe is contacted with the electrode pad a plurality of times to make the trace of the needle deeper and confirmed. The probability of becoming was high.
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to correct the alignment between the wafer and the probe of the probe card by observing the trace of the probe on the electrode pad of the semiconductor device. SUMMARY OF THE INVENTION It is an object of the present invention to provide a wafer alignment correction method which can be achieved.
[0006]
[Means for Solving the Problems]
The present invention provides, as means for solving the above-mentioned problems, a method for correcting the alignment of a wafer described in the claims.
According to the method for correcting the positioning of a wafer according to claim 1, the trace of the stylus of the stylus of the probe card attached to the electrode pad of the semiconductor device is observed by a color camera, and the trace of the stylus is located at an appropriate position on the electrode pad. It is determined whether or not the needle mark is attached, and if the position of the needle mark is deviated from an appropriate position, the position deviation is corrected. In this method, needle traces are observed with a color camera, so needle traces can be clearly observed even on electrode pads made of gold bumps, solder bumps, aluminum bumps, etc., which were difficult to see with conventional monochrome cameras. The displacement between the stylus and the electrode pad can be corrected. In the conventional monochrome camera, the stylus is hard to see, so the stylus and the electrode pad are brought into contact multiple times to make the stylus deeper, causing damage to the semiconductor device. In a camera, a needle mark can be observed without contacting a plurality of times, so that the yield of semiconductor devices can be improved.
[0007]
In the method of correcting and positioning a wafer according to claim 2, the stage holding the wafer is moved under the color camera, the center of the needle mark is aligned with the cross on the screen of the color camera, the position is registered, and then the position on the screen is registered. The method according to claim 1, wherein the center of the electrode pad is aligned with the cloth, the position is registered, and the positional deviation between the center position of the needle mark and the center position of the electrode pad is corrected. The operation and effect are the same as those of the first aspect.
[0008]
Hereinafter, a method for correcting the alignment of a wafer according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a probe device for carrying out the wafer alignment correction method of the present invention. The probe device 1 mainly includes a stage 2, a stage driving motor 3, a probe card 4 provided with a stylus 4a, a tester 5, an alignment optical device 6, a stage-side CCD camera 7 for imaging the stylus 4a, and a color camera. 8 and a control unit 9.
[0009]
At an upper portion of the stage 2, a chuck portion 2a for mounting and holding the wafer 10 is provided. The stage 2 is configured to be movable in the X, Y, and Z directions and in the θ rotation direction about the Z axis by a stage driving motor 3 controlled by the control unit 9, and is held by the chuck unit 2 a of the stage 2. The wafer 10 can be moved three-dimensionally.
[0010]
On the surface of many semiconductor devices of the wafer 10, bump-shaped electrode pads 10a are formed, and only one electrode pad 10a is shown in FIG. 1 for convenience of explanation. Many electrode pads 10a, such as hundreds and thousands, are formed. These electrode pads 10a are made of gold bumps, solder bumps, aluminum bumps or the like. Further, the probe card 4 is provided with a stylus 4 a corresponding to the electrode pad 10 a of each semiconductor device of the wafer 10. Therefore, by bringing the stylus 4a of the probe card 4 connected to the tester 5 into contact with the electrode pad 10a of the wafer 10, the electrical characteristics of each semiconductor device can be inspected.
[0011]
Further, a CCD camera 7 that captures an image of the stylus 4a from below and detects the position of the tip of the needle is attached to the chuck 2a of the stage 2. The stage 2 is moved, the CCD camera 7 is moved, the position of the tip of the stylus 4a is measured while focusing, and the result is input to the control unit 9.
[0012]
The alignment optical device 6 includes an imaging unit such as a CCD camera, and recognizes a pattern of a semiconductor device on the wafer 10 and inputs the pattern to the control unit 9. The control unit 9 uses a known image processing technique based on the information obtained by the alignment optical device 6 and the position information of the tip of the stylus 4a obtained by the CCD camera 7, and Positioning with the electrode pads 10a is automatically performed. In this case, as the CCD camera, a monochrome camera having a high resolution and capable of performing high-accuracy alignment is used.
[0013]
Further, the probe device of the present invention is provided with a color camera 8 which is a feature of the present invention. As shown in FIG. 3, the color camera 8 observes the stylus trace 10b of the stylus 4a left on the electrode pad 10a of the wafer 10 after the probing is performed, and determines the position of the stylus trace 10b. It is checked whether or not the pad is at an appropriate position on the pad 10a. If the position is out of position, the position information is input to the control unit 9, and the position is checked while being observed on the display 11 connected to the control unit 9. This is to correct the deviation.
[0014]
Next, a description will be given, with reference to the flowchart of FIG.
First, using the CCD camera 7 and the alignment optical device 6, the positioning of the stylus 4a and the electrode pad 10a of the wafer 10 is performed by a commonly known method. That is, the stage 2 is moved to a position where the stylus 4a of the probe card 4 and the CCD camera 7 face each other, the stylus 4a is imaged by the CCD camera 7, the position of the tip of the stylus 4a is measured, and the result is controlled. Input to section 9. Next, after aligning the position of the CCD camera 7 with the position of the alignment optical device 6, the wafer 10 is fixedly held on the chuck portion 2 a of the stage 2, and the stage 2 is moved below the alignment optical device 6 by the stage driving motor 3. After moving, the pattern of the semiconductor device (the position of the electrode pad) on the wafer 10 is imaged by the alignment optical device 6, and the data is input to the control unit 9.
The control unit 9 calculates the position of the electrode pad 10a with respect to the position of the stylus 4a based on the input data, and moves the stage 2 so that the stylus 4a appropriately contacts the electrode pad 10a. Control. In this manner, first, the first semiconductor device of the wafer 10 is aligned with the stylus 4a, and the stylus 4a of the probe card 4 contacts the electrode pad 10a of the first semiconductor device on the wafer. Then, the electrical characteristics are measured. Thereby, a needle mark is formed on the electrode pad 10a. The above operation is a normal alignment operation performed up to step S1 in FIG.
[0015]
The method for correcting the alignment of a wafer according to the present invention performs the following steps S2 to S6. That is, the stage 2 (chuck portion 2a) is moved below the color camera 8 to observe the stylus trace 10b of the stylus 4a attached to the electrode pad 10a of the first semiconductor device (step S2). Next, as shown in FIG. 3, the center of the needle mark 10b is aligned with the cross (+) on the screen of the display 11, and the position is registered in the control unit 9 (step 3S). Next, the center of the electrode pad 10a is aligned with the cross on the screen, and the position is registered in the control unit 9 (step S4). The control unit 9 calculates the center-to-center distance between the center of the needle mark 10b and the center of the electrode pad 10a based on the shift amounts x and y (step S5). Based on the calculation result, the stage 2 is moved by a small amount (x, y), and thereafter, a normal probing operation is performed (step S6). As described above, the alignment of the wafer is corrected so that the stylus 4a comes into contact with an appropriate position (center position) of the electrode pad 10a of the wafer 10.
[0016]
In the above method, the center of the needle mark 10b is aligned with the cross on the screen (step S3), and then the cross on the screen is aligned with the center of the electrode pad 10a (step S4), but the order is reversed. You can go to In addition, although the description is made by observing the needle mark 10b of the electrode pad 10a in the first semiconductor device, in the case where the position of the electrode pad 10a and the stylus 4a seems to have shifted, In this case, the positional deviation can be corrected.
Further, in the above description of the embodiment, the alignment optical device 6 including the monochrome camera and the color camera 8 are provided separately, but the color camera 8 may be incorporated in the alignment optical device 6.
[0017]
As described above, in the present invention, it is possible to accurately observe the trace of the stylus on an electrode pad such as a gold bump, a solder bump, and an aluminum bump, and it Since accurate alignment can be corrected, the electrical characteristics of the semiconductor device can be measured with high accuracy, and the yield of defective products can be improved.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a prober apparatus that employs a wafer alignment correction method according to an embodiment of the present invention.
FIG. 2 is a flowchart of a wafer alignment correction method according to the embodiment of the present invention.
FIG. 3 is a diagram for explaining a procedure for aligning the center of an electrode pad with the center of a needle mark.
[Explanation of symbols]
2 stage 2a chuck unit 3 stage drive motor 4 probe card 4a probe 5 tester 6 alignment optical device 7 CCD camera 8 color camera 9 control unit 10 wafer 10a electrode pad 11 display

Claims (2)

After positioning the wafer on which the semiconductor device is formed, the probe of the probe card is brought into contact with the electrode pad of the semiconductor device, and the probe device for inspecting its electrical characteristics is displaced between the electrode pad and the probe. In the wafer position correction method for correcting
Observe the stylus trace of the stylus attached to the electrode pad by a color camera, determine whether the stylus trace is attached to an appropriate position on the electrode pad, the position of the stylus trace A method for correcting the positioning of a wafer, comprising correcting the positional deviation when the position is deviated from an appropriate position. Moving the stage holding the wafer under the color camera;
Aligning the center of the needle mark with a cross on the screen of the color camera, and registering the position thereof;
Aligning the center of the electrode pad with the cross on the screen and registering its position;
Correcting the positional deviation between the center position of the needle mark and the center position of the electrode pad,
2. The method according to claim 1, further comprising the step of:

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