JPH05136249A - Wafer automatic alignment device - Google Patents

Abstract

PURPOSE:To provide a positioning device capable of positioning a probe card with a wafer in mechanical and automatic mode and processing in short time without an individual difference with regards to an automatic positioning device capable placing a probe-implanted probe card in contact with a chip pad of a wafer. CONSTITUTION:A central coordinate of a wafer pad 14 on a stage 10 is read by means of a first camera 23 installed to a probe head 20 while tip coordinates of probes (22-1, 22-2) on a probe card 21 are read by means of a second camera 15 separately installed on the stage. This device calculates these coordinate values and provides a movement to a stage transfer device in automatic mode so that the tip of the probe may be aligned to the center of the pad.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for automatically aligning a probe card having a contact needle implanted therein with a chip pad of a wafer so that the probe card can be brought into contact therewith. Probe card and I
When the pads on the C chip are aligned with each other, they can move in parallel with each other, so even if it is possible in principle to do so by an automatic adjustment mechanism, the IC chip is becoming smaller and smaller. Finally, the operator needs to make adjustments using the microscope. Therefore, it takes a long time to perform the alignment, but there are individual differences in accuracy.
It was desired to develop a technique for solving such a drawback.

[0002]

2. Description of the Related Art Conventionally, in the process of manufacturing a semiconductor integrated circuit, it is necessary to check the electrical characteristics before mounting an IC chip on a package. Therefore, the contact needle corresponding to each pad of the IC chip is pressed, and the chip is checked by a dedicated device connected to the contact needle.
FIG. 4 is a cross-sectional view of a stage for moving an IC chip and a probe card for moving and pressing a contact needle as a conventional device, and FIG. 5 is a rear view of only the probe card. In FIG. 4, 10 is a wafer stage,
Reference numeral 11 is a wafer, and 12 is a chuck for the wafer. Further, 20 is a probe head, 21 is a probe card, and 22-1, 22-2, ... Are contact needles made of, for example, tungsten. 23 shows a microscope.

Although not shown in FIG. 4, both the stage 10 and the probe head 20 have their movement origins defined, and by moving from that position in the X and Y directions and in parallel with each other by a desired distance, As a positional relationship between the two, it is easy to bring the probe head directly above the IC on the stage. This operation is an automatic operation mechanism.
However, since accurate alignment cannot be performed, fine adjustment is required as described later.

As shown in FIG. 4, a probe card 21 is attached to the probe head 20, and the wafer 11 on the stage 10 and the probe card 21 are opposed to each other. The probe card 21 is composed of a printed board, has a void in the center thereof, and the IC chip is observed by the optical microscope 23. The stage 10 on which the wafer is placed is moved by a predetermined amount of X and Y coordinates from the movement origin by the automatic operation mechanism, and at that position, the stage 10 on which the wafer is placed is observed by the microscope or camera 23 from the back surface of the probe card 21. Move it to the positive or negative direction by a slight amount. Since the wafer 11 has a notch when the IC chip is cut in the next step, it is confirmed whether the notch and the movement of the stage in the X direction are in the same direction. Then, the stage 10 is rotated clockwise or counterclockwise so as to be in the same direction. Then, the operator aligns the center of each pad of the IC with the tip of the probe contact needle while operating the microscope. Alternatively, the image is taken by the operator on the CRT screen and the operator operates it while watching the image on the screen.

[0005]

However, there is a drawback in that the accuracy of alignment varies among individuals because the operator operates it. Further, when the IC chip has many pads, it is necessary to use a multi-pin contact needle of the opposing probe card. Since the pads are located around the IC chip, a large number of contact needles of the probe card are provided for the IC chip having many pads. Therefore, if the magnification of the microscope is increased too much within the field of view of the microscope, only the central portion of the IC chip will be displayed. Since it is visible, it is troublesome to move the stage or the microscope camera again in order to observe the pad. When one side of the IC chip is aligned, the alignment of the pad and the contact needle on the other side may be defective. Further, the operator operates while looking at the microscope or the CRT screen on which the image is transferred, which causes a drawback that the adjustment takes a long time.

An object of the present invention is to improve the above-mentioned drawbacks and to provide an alignment device which aligns a probe card with respect to a wafer by mechanical and automatic operation and which can be processed in a short time without individual differences. ..

[0007]

FIG. 1 is a diagram showing the principle configuration of the present invention. In FIG. 1, 10 is a stage, 11
Is a wafer, 13 is an IC chip, 14 is a pad on the chip, 15 is a second camera, 16 is a data storage unit, 17 is a data calculation unit, 18 is a stage moving device, 20 is a probe head, 21 is a probe card, 22 Reference numerals -1,22-2 to 1,2--2 denote contact needles, 23 denotes a first camera, 24 denotes a data storage unit, and 25 denotes a probe head moving device in the θ direction. Stage (1
0) A probe card in which a plurality of contact needles (22-1) (22-2), which can contact pads (14) on each chip (13) of a wafer (11) placed on (0), are implanted. A prober head (20) including a (21) and a first camera (23) mounted so that the wafer (11) can be observed from the center of the probe card (21) is provided in parallel with the stage (10). The probe card (20) contact needles (22-1) (22-2) to the pad (14) on the wafer (13) are aligned so that the contact needles (22-1) (22-2) to The invention has the following configuration. That is, the probe head
The first camera (23) of (20) is provided on the side of the probe card (21) and is provided on the stage (10) to observe the direction of the probe card (21), the second camera (15) and the first camera ( The storage unit (24) for storing the values obtained by reading the central coordinates of each pad (14) of the wafer (11) mounted on the stage (10) by the second camera (15) by the second camera (15). 20) Contact needle (22-1) (22-2)
~ Storage unit (16) for storing the values obtained by reading the coordinates of the tip, a calculation unit (17) for calculating the coordinate values of both storage units, and a moving device (18) for moving the stage based on the calculation result. ,,.

[0008]

The pad 14 of the predetermined IC chip 13 is observed by the first camera 23. The position coordinates of the first camera 23 when observing a predetermined position of the pad 14, for example, the center,
The central coordinate value of 4 is stored in the data storage unit 24. Next, the stage 10 side is moved and the specific contact needle of the probe card 21 is observed by the second camera 15. At this time, the contact needle corresponding to the pad 14 is selected. The position coordinate of the second camera 15 is stored in the data storage unit 16 when the tip of the contact needle comes to the center of the visual field. The data in the data storage unit 24 is transferred to the arithmetic unit 17, and the arithmetic unit 17 performs an operation for obtaining a difference value from the data stored in the data storage unit 16.
Next, the moving device 18 moves the stage 10 by the difference value obtained.
When the pad is moved, the pad 14 is positioned directly below the corresponding contact needle. Therefore, the pad and the contact needle are automatically aligned.

[0010]

FIG. 2 is a diagram showing a case where a probe card is provided with a target mark to facilitate observation of a contact needle by a second camera as an embodiment of the present invention. FIG. 2 is a top view of the probe card, 22-1 to 22-4 are contact needles, and 26-1 to 26.
-4 indicates a target. The target mark 26 is engraved on the substrate of the probe card 21 at the beginning of manufacture, for example, as a cross mark on a white background in the vicinity of the contact needle implantation portion. It can be made by photographic technology. The target marks 26-2 and 26-4 are located on the X axis and the Y axis with respect to the mark 26-1, respectively. The relationship between the target mark 26 and the contact needle 22 can be defined when the probe card is manufactured. That is, the position of the target mark 26-1 is the origin 0,
The tip coordinate Pa of the contact needle 22-1 is (Xa, Ya), the contact needle 22.
The tip coordinate Pb of -2 is (Xb, Yb), the tip coordinate Pc of the contact needle 22-3 is (Xc, Yc), the tip coordinate Pd of the contact needle 22-4.
Can be respectively defined as (Xd, Yd).

By using at least two contact needles for one chip and bringing them into contact with pads having a diagonal positional relationship on the chip, it can be said that the alignment is performed with respect to the remaining pads. This is because the arrangement on the chip is done regularly, and it is not necessary to perform alignment for all pads.

When the target mark 26 is observed by the second camera, its coordinates are obtained and stored in the data storage unit 16. Further, when the coordinates are obtained by observing the pad 14 with the first camera 23, both coordinates are obtained as coordinates from the moving origin set in advance in the moving device 18. In the calculation in the calculation unit 17, the tip coordinates of the contact needle are corrected and calculated with respect to the coordinates at which the target mark 26 is observed, and then the difference from the coordinate position of the pad 14 is calculated.

When observing the contact needle with the second camera as shown in FIG. 1, the tip of the contact needle is directly detected,
It is often difficult to observe. The probe card shown in FIG. 2 can be replaced by determining the position of the tip of the contact needle by observing the position of the target mark 26-1. This will be described below. FIG. 3 shows a schematic view when the chip is observed by the first camera. In FIG. 3, 13 is a chip, 14-1 to 14-4 are pads 19-1 to 19-4, and scratches of contact needles attached to the pads are shown. The scratches 19 are formed when the probe card 21 is brought close to the chip 13 and the state of the moving device 25 is viewed. Therefore, in the initial coordinate detection by the first camera 23, the position of the pad can be quickly obtained by using the scratch 19. Or once you do the automatic alignment,
After bringing the contact needle onto the pad, when the contact needle is brought into contact with the pad for voltage application, etc., the contact needle is pressed and scratched. Then, the pad and the probe card are separated, and the first camera 2
By observing the state of the pad according to 3, it is possible to determine the accuracy of automatic alignment depending on the position of the scratch. At this time, if there is no needle scratch in the center of the pad, the difference can be obtained and the moving device 18 can correct the position to a more accurate position.

In the above description, the coordinate position is obtained by measuring with a known micrometer or by providing an encoder on the XY axes. Further, regarding the movement of the probe card / probe head, the movement of θ in addition to the XY axes can be performed together to perform more accurate alignment.
Even if the probe card is changed because the IC chip has been changed to another type, if the positional relationship between the tip of the contact needle and the first camera is not changed, the next processing operation can be performed quickly and quickly.

[0015]

As described above, according to the present invention, by using the two cameras, the positional relationship between the probe card contact needle and the chip pad is recognized as a coordinate difference, and the moving device automatically detects the moving amount. Since it is given, there is no individual difference among workers, and it has the effect of improving the alignment accuracy on average.
At this time, it is possible to shorten the time and unmanned. By using an object with a target mark engraved in the probe card, it is possible to easily and accurately determine the position coordinates without directly observing the tip of the contact needle when observing with a camera. Since the processing operation is performed by the camera, even an integrated circuit with a large number of pins and a fine pitch does not cause operator fatigue and is effective.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention.

FIG. 2 is a diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 3 is a diagram showing an outline when a chip is observed by a first camera in an example of the present invention.

FIG. 4 is a schematic view showing a conventional alignment device.

FIG. 5 is a back view of a conventional probe card.

[Explanation of symbols]

10 stage 11 wafer 13 IC chip 14 pad on chip 15 second camera 16 data storage unit 17 data operation unit 18 stage moving device 20 probe head 21 probe card 22-1, 22-2 ~ contact needle 23 first camera 24 data Storage unit 25 Probe head moving device

Claims (2)

[Claims] 1. A wafer (1) mounted on a stage (10)
A probe card (21) in which a plurality of contact needles (22-1) (22-2) that can contact the pad (14) on each chip (13) of 1) are implanted
And the wafer (11) from the center of the probe card (21)
A prober head (20) having a first camera (23) attached so that it can be observed is set so as to be movable in parallel with the stage (10), and a probe needle (22-1) of a probe card (21) is set. )(twenty two-
2) to aligning the wafer so that it contacts the pad (14) on each chip (13) of the wafer, the first camera (23) of the probe head (20) is connected to the probe card.
It is mounted on the stage (10) by the second camera (15) which is provided on the side of (21) and observes the direction of the probe card (21) on the stage (10) and the first camera (23). The storage unit (24) for storing the values obtained by reading the center coordinates of the pads (14) of the wafer (11) and the contact needle (22-) of the probe card (21) by the second camera (15).
(1) (22-2) ~ Storage unit that stores the value obtained by reading the coordinates of the tip (1
6), a computing unit (17) for computing the coordinate values of the two storage units, and a moving device (18) for moving the stage based on the computation result.
An automatic wafer alignment device characterized by comprising 2. The probe card according to claim 1, wherein a target mark is engraved near a planting portion of a predetermined contact needle, and coordinate values of the target mark and the tip of the contact needle when attached to the probe head. An automatic wafer alignment apparatus, wherein the difference is calculated in advance and the present position of the stage is calculated by detecting a target mark by a second camera.