JPH07312382A - Probe device - Google Patents

Abstract

PURPOSE:To provide a probe device with a structure for detecting the contact state of a probe needle for a pad during inspection process. CONSTITUTION:The device is provided with a discrimination processing part 20 including an image sensor 18 for picking up the image of the needle trace of a probe needle which is formed by the contact with an electrode pad, a calculation part 22 for calculating the area and the position of the needle trace on an electrode pad according to an output signal from the image sensor 18, a storage part 22 for storing at least one of the calculated needle trace and the needle trace area, and a judgment part 28 for judging whether the contact state between the probe needle and the electrode pad is proper or not based on at least either of the needle trace position and the needle trace area stored at the storage part 22, thus nearly automatically judging whether the contact state is proper or not according to the formed needle trace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe device for inspecting electrical characteristics of a semiconductor wafer.

[0002]

2. Description of the Related Art In a semiconductor manufacturing apparatus, when an element is completed on a wafer, a probe needle is brought into contact with the electrode pad of the element to inspect the electrical characteristics of the element.

In such inspection of electrical characteristics, good contact of the probe needle with the electrode pad of the device is required, and it is necessary to suppress so-called increase in contact resistance.

Therefore, conventionally, when the probe needle comes into contact with the electrode pad of the element once, the element is moved in the direction of further pushing up the probe needle from that state, and so-called overdrive is executed to The oxide film formed on the surface is removed to directly contact the probe needle with the electrode.

[0005]

By the way, in an inspection process which is continuously performed using a probe needle, the contact resistance (electrical resistance) increases when the contact area of the probe needle with respect to the element is small. Therefore, there is a possibility that the product is determined to be a defective product although it is a non-defective product.

Therefore, it can be considered to judge the quality of the contact state between the two from the state of the trace of the needle formed on the electrode pad.

Such needle traces are generally substantially elliptical. This is because the needle tip slides on the electrode due to overdrive that is performed once the electrode pad is contacted.

However, when the contact state is determined from the formation state of the needle trace, the shape of the needle trace is not uniform, so that a detection error is likely to occur and the product may be determined as a defective product although it is a good product. .

That is, when observing the traces of the actually formed needle, the following shape may be obtained.

That is, a part of the elliptical shape is not formed at a predetermined position of the electrode pad due to the passivation edge projecting around the electrode pad, or a part of the elliptical shape is missing. , Some of them are overlapped by being formed a plurality of times. Therefore, the present situation is that the reliability for determining the contact state between the probe needle and the electrode pad based on the formation state of all these needle marks is not so high.

The formation of needle marks a plurality of times means, for example, a case where the wiring is repaired after the first inspection, so-called repair processing is performed, and the inspection step is performed again.

Therefore, an object of the present invention is to detect the contact state of the probe needle with respect to the electrode pad during the inspection process in view of the problem in the above-mentioned conventional probe device, and to prevent the detection accuracy from being lowered. An object of the present invention is to provide a probe device having a structure capable of performing the above.

[0013]

In order to solve the above-mentioned problems, the present invention according to claim 1 provides a probe apparatus comprising a probe needle capable of contacting an electrode pad of an element formed on a semiconductor wafer, An image sensor that captures the needle trace of the probe needle formed by contacting the electrode pad, and a calculation that calculates the area of the needle trace and the position of the needle trace on the electrode pad based on the output signal from the image sensor. Section, a storage unit that stores the area and the needle trace position calculated by the calculation unit, and contact between the probe needle and the electrode pad based on at least one of the needle trace position and the needle trace area stored in the storage unit. The present invention is characterized by including a determination processing unit having a determination unit that determines whether the state is good or bad.

According to a second aspect of the present invention, in the first aspect, the determination section obtains the barycentric position based on the needle trace position stored in the storage section, and the barycentric position is within the electrode pad. It is characterized in that it is determined that the contact between the probe needle and the electrode pad is defective when it is not within the predetermined range.

According to a third aspect of the present invention, in the first aspect, the determination unit makes contact between the probe needle and the electrode pad when the contour of the needle trace position stored in the storage unit is not within a predetermined range. It is characterized by making a defect determination of the state.

According to a fourth aspect of the present invention, in the first aspect, the determination section determines whether the contact state with the probe needle electrode pad is defective when the needle trace area stored in the storage section is a predetermined value or less. It is characterized by performing.

According to a fifth aspect of the present invention, in the first aspect, when the detection section detects that the needle mark is partially missing based on the image information from the image sensor, the missing section in the image is detected. And an interpolating section for interpolating, and obtaining the needle trace area or the area centroid based on the above interpolation result.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, in the determination unit, when the contact of the probe needle is repeated a plurality of times at the same position of the electrode pad, the needle mark formed at each time is If there is no defect and part of both needle traces do not overlap, the quality of the contact state of the probe needle is judged by obtaining the needle trace position and the needle trace area formed last. It is characterized by that.

According to a seventh aspect of the present invention, in the sixth aspect, the determining portion is A, which is a non-overlapping area of the needle trace area formed last time, and the overlapping portion. When the area is C, the area of the needle trace area formed at the end that does not overlap is B, and the area of the overlapping portion is C,
The feature is that the needle trace area S formed at the end is obtained by S = (A + C + B + C)-(A + C).

[0020]

According to the first aspect of the present invention, the quality of the contact state is determined based on at least one of the position and the area of the needle trace formed on the electrode pad. As a result, if the position of the needle trace is not located on the electrode pad, or if it is located but does not have a predetermined area, the direct contact between the electrode pad and the probe needle is not sufficient, and a contact failure state occurs. Can be determined.

According to the second aspect of the present invention, it is possible to detect the case where the needle trace is dislocated from the electrode pad by obtaining the area centroid of the needle trace based on the position information of the needle trace. As a result, even if a part of the needle trace is located on the electrode pad, if the area center of gravity of the needle trace is not within the predetermined range of the electrode pad, the contact state is set only by not increasing the contact resistance. It can be determined that it is not.

According to the third aspect of the present invention, the contact state can be determined by detecting that the contour is located in the electrode pad based on the contour of the needle trace.

This makes it possible to determine the contact state by coping with the contour formation state.

According to the fourth aspect of the invention, when the needle trace area is less than a predetermined value, it can be determined that the removal of the oxide film by the probe needle is not complete. The contact state can be determined by coping with.

According to the fifth aspect of the invention, when the needle trace formed on the electrode pad is not the elliptical shape as described above and a portion is missing, the needle trace area is virtually from the remaining portion. Can be extracted and the contact state can be determined.

According to the sixth aspect of the present invention, the contact state can be determined by coping with the case where the probe needle and the electrode pad are contacted a plurality of times. In particular, when needle marks are formed in a separated state on the electrode pad, the coping method described above is applied to the last needle mark.

According to the seventh aspect of the invention, the area of the overlap portion on the side of the previous needle trace is included in the previous area from the sum of the area of the needle trace formed last time and the area of the needle trace formed last. By subtracting from the total sum, the final needle trace area including the area of the remaining overlap portion is obtained. Therefore, by subtracting one needle trace area from the total area of overlapping needle traces, it is possible to accurately determine the last formed needle trace area even in the overlapping needle trace formation state. You can

As described above, in the present invention, the contact state between the probe needle and the electrode pad can be accurately determined by using the image recognition included in the inspection process only by determining the formation state of the needle trace.

[0029]

Embodiments of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 shows a schematic structure of a probe device according to the present invention.

That is, the probe apparatus 10 is provided with a mounting table 12 for mounting a so-called semiconductor wafer W having a large number of elements (semiconductor chips) formed on a substrate.

The mounting table 12 has X, Y, and Z axes when the orthogonal coordinate axes on the mounting table plane are the X and Y axes, the vertical direction is the Z axis, and the circumferential direction of the Z axis is the θ direction. And is movable in the θ direction.

Further, the mounting table 12 is provided with a mechanism for temporarily fixing the mounted semiconductor wafer W, for example, vacuum suction, and moves in the above-mentioned direction while suction-holding the semiconductor wafer W. be able to.

On the other hand, a probe card 14 is arranged above the mounting table 12. This probe card 14
Are aligned with the probe needles 14A arranged corresponding to the arrangement of the electrode pads of each element (semiconductor chip), and are supported by the ring insert 16.

Further, above the probe card 14, at a position where the element and the probe needle 14A can be seen,
An image sensor 18, which is composed of an image pickup means, such as a CCD, is arranged.

The image sensor 18 recognizes the positional information of the electrode pad of the element and also the probe needle 14A.
It has a function of confirming the contact state between the electrode pad and the electrode pad, and any means may be provided at any place as long as it has this function.

That is, in the image sensor 18, the probe needle 14A is brought into contact with the electrode pad row of each chip formed on the semiconductor wafer of the probe needle 14A to perform overdrive, and the chip is inspected by pressing contact. The position of the formed needle trace in each electrode pad and the size of the needle trace are detected, and the needle trace information is output to the discrimination processing unit 20.

As shown in FIG. 2, the discrimination processing section 20 includes a calculation section 22, an interpolation processing section 24, and an area comparison section 2.
6 and a determination unit 28, and is connected so that the output of the image sensor 18 is input to the calculation unit 22.

A control unit 30 for controlling the sequence of the inspection process is connected to the determination unit 28. The control unit 30 is connected to a storage unit 32 that stores the position, size, etc. of the needle trace, and a display unit 34 that displays the stored content as needed. Further, the control unit 30 is provided with a member required for a process required in the inspection process, that is, an operation for bringing the probe needle and the electrode pad into contact with each other, for example, a lifting operation of the mounting table 12 and a detection of the lifting operation position. Each is connected to the output side.

Calculation unit 2 provided in the discrimination processing unit 20
2 has a function of calculating the area and center of gravity of the needle marks located on each electrode pad based on the image signal output from the image sensor 18. In addition, the interpolation processing unit 24
When a part of the trace of the needle formed on the electrode pad is missing as an output signal of the image sensor 18, the missing part is interpolated by a method such as a pattern recognition technique to calculate the area and the area centroid in the calculation unit 22. It has the required function.

Further, the area comparison unit 26 stores the position information of the needle trace area and the area center of gravity in the case of being formed on the electrode pad in a normal state in advance in the storage device, and the stored information and the actual information after the inspection are stored. It has a function of comparing the needle trace area and the area center of gravity. Then, the determination unit 28 has a function of determining, based on the output from the area comparison unit 26, the state of formation of the needle trace of the chip actually inspected, in other words, the quality of the contact state between the probe needle and the electrode pad. .

Storage unit 32 connected to control unit 30
The needle trace position and needle trace area when normal needle trace formation is performed are registered, and the needle trace position and needle trace area output to the control unit via the determination unit 28 are also stored in the storage unit. Is stored. The needle trace position and the needle trace area output from the control unit via the determination unit 28 are temporarily stored in the storage unit as the previous one when the needle trace inspection is performed a plurality of times, for example.

By the way, in this embodiment, for example,
The image sensor is intended to recognize only the traces of needles formed on the base material of the electrode pad such as aluminum. Therefore, it cannot be recognized by color. Therefore, the image sensor 18 outputs and recognizes a pixel signal based on the difference in luminance or the difference in density between the recess formed in the needle mark portion on the electrode pad and the other flat portion. ing.

On the other hand, as a trace of a needle formed on an electrode pad, there is one having the following formation state. First, regarding the case of a normal needle trace, in this case, the contour of the needle trace is entirely within the electrode pad, and the needle trace area is a predetermined value or more. With respect to such a formation state, (1) when a part of the needle trace P is included in the passivation edge E located in the peripheral portion of the electrode pad D (FIG. 3), (2) between the needle traces P When some of them overlap (Fig. 4), (3) some of the needle traces P are missing (Fig. 5), and (4) only some of the needle traces P remain (Fig. 6) There is.

The following method is used to detect the formation state of the needle trace P in such a state and judge whether the contact state between the probe needle and the electrode pad D is good or bad.

First, in the case of (1), the area of the needle trace located in the electrode pad D is obtained, and the barycentric position of the area is obtained. Such processing is calculated by the calculation unit 22 based on the pixel signal from the image sensor 18.

Based on the calculated area and the position of the center of gravity of the area, the contact state between the probe needle and the electrode pad is determined as described above. By the way, in the case of a normal contact state, the calculated area is equal to or larger than a predetermined value, and the area center of gravity is included in a predetermined range. Therefore, if even one of these conditions is not satisfied, it can be determined that the contact is poor.

Next, in the case of (2), paying attention to the fact that the overlapping portion forms a part of the last and last needle trace areas, and the last and last needle trace areas were formed. By subtracting the previously formed needle trace including one of the overlaps from the total area of the needle traces P, the finally formed needle trace area including the remaining overlap is obtained. Explaining with reference to FIG. 4, the area S1 of the needle trace formed last time corresponds to the non-overlapping area A and the overlapping area C, and the area S2 of the needle trace formed last is It corresponds to a non-overlapping area B and an overlapping area C. Therefore, the area (S2) of the lastly formed needle trace is (S2) = (A + C + B + C)-(A + C) with reference to FIG.

From the area and the center of gravity of the area, the contact state is judged based on the above-mentioned criteria for judging the contact failure.

In the case of (3), as described above, it is assumed that the needle trace shape on the electrode resembles an elliptical shape due to sliding due to overdrive in the contact transient phenomenon between the probe needle and the electrode, and the output of the image sensor 18 From the pixel signal from, the defective portion is interpolated by, for example, the normally used linear interpolation method, quadratic interpolation method, or Newton's successive approximation method to obtain an approximate needle trace area as an ellipse, and Compare the area and the position of the center of gravity of the area under different contact conditions.

In the case of (4), it is assumed that it is similar to the case of (3) above, that is, it is similar to an ellipse, and an arbitrary coordinate position (reference numeral P1 in FIG. 6) in the contour of a part thereof. ~ P4
The position and center of gravity of the ellipse having a part thereof are obtained based on the position
The area and the position of the center of gravity of the area under normal contact are compared.

In the cases of (3) and (4), it is not only premised that the needle marks are formed in the electrode pad, but also in the case of (1), a part of the needle marks is formed. Is also assumed to be located outside the electrode pad, that is, at the so-called passivation edge.

Further, in determining the needle trace area, the area when it is recognized as a normal contact is set as a threshold value.

The detection of the needle trace is performed during the execution of the inspection process, and thereby, it is performed to determine the quality of the contact state depending on the replacement time of the probe needle or the installation state of the probe card.

The present embodiment is configured as described above, and the operation of the present invention will be described below with reference to the flow chart for explaining the operation of the determination processing section 20.

First, it is judged whether or not there is a needle mark inspection instruction when the inspection process of the chip formed on the semiconductor wafer or the selected chip is executed (step 101). The semiconductor wafer provided on the mounting table with respect to the probe needles is driven in the Z-axis direction, that is, upward, and each probe needle comes into contact with the electrode pad, and a predetermined amount of overdrive is executed to perform inspection. To be executed. Then, a needle mark is formed on the electrode pad by executing the overdrive (step 102).

After forming the needle trace, it is judged whether or not the needle trace is formed for the first time (step 103).

In the case of the first trace formation, the image sensor 18 takes an image of the electrode pad of the element on the mounting table on which the trace of the semiconductor wafer is formed (step 104).

Next, based on the pixel signal from the image sensor 18, it is judged whether or not there is a defective portion in the needle trace (step 105). If there is a defective portion, the needle trace area other than the defective portion is calculated, and it is determined whether this area is equal to or larger than the minimum interpolable area (step 10).
6). The presence / absence of a defective portion is determined, for example, on the basis of the case where a pixel signal is usually output according to the contour of a continuous needle trace, whereas the continuous pixel signal is not output.

In the determination of such an area, there is a possibility that an error with the actual needle trace area may increase as the defective portion becomes the maximum. Therefore, only the area having the minimum area required for interpolation is determined. Is a process performed to extract

If the area is equal to or larger than the minimum area in step 106, interpolation processing is performed (step 107).

The area and center of gravity of the needle trace after the interpolation processing are calculated (steps 107 and 108).

On the other hand, in the case where there is no defective portion and the needle mark for which interpolation processing has been performed, the area and the position of the area centroid are calculated (steps 108 and 109).

The calculated needle trace area is compared with a threshold value corresponding to the area when it can be judged by the area comparison unit 26 of the discrimination processing unit 20 that a normal contact is made (step 110). Since the threshold value in this case is targeted at the area of the needle trace on the electrode pad, it also includes, for example, the case where a part of the needle trace is on a portion other than the electrode, that is, on the passivation edge. The reason for including the case where it is on the passivation edge is that even if a part of the needle trace is on the passivation edge, the area on the edge is extremely small and almost all of the needle trace is included in the electrode. This is because it is assumed that there are cases where the

In addition to comparing the areas of needle traces,
It is determined whether or not the position of the area center of gravity of the needle trace is within a predetermined range (step 111). The predetermined range used for determining the area center of gravity position corresponds to a range in which normal contact can be determined even if there is some deviation from the center of the area of the electrode.

The area of the needle trace formed on the electrode in steps 110 and 111 is not less than the threshold value,
Then, it is determined that the contact of the probe needle on the electrode is good only when the position of the area center of gravity is satisfied within the predetermined range.

On the other hand, if it is determined in step 103 that the element used in the inspection process is not the one used in the first inspection process, the cumulative total of the previous needle trace area and area center of gravity for this element is accumulated. Is read from the storage unit 32 (step 112).

As described above, the case where the inspection process which is not the first time is executed is, for example, the case where the repair process is performed on the wiring portion of the element. In this case, since the first needle trace is already formed on the element, it is premised that the area and the area centroid of the needle trace are stored in the storage unit 32.

Then, the needle trace is imaged again (step 113), and the presence or absence of the defective portion is determined based on the pixel signal from the image sensor 18 (step 11).
4). In this case, the presence / absence of the defective portion is determined based on the same criteria as in step 105.

If the trace of the needle has a defect, interpolation processing is executed for the defect (step 115).

When there is no missing portion in the needle trace and the needle trace for which the interpolation processing has been executed, it is judged whether or not it overlaps with the previous needle trace (step 11).
6).

Whether or not they are overlapped is determined by
For example, it is determined whether or not there is a portion that makes the coordinate position the same as the previous needle mark position by the pixel signal from the image sensor 18.

If it is determined in step 116 that they do not overlap, the area of the needle mark formed last and the position of the center of gravity of the area are calculated, and the process proceeds to step 110.

On the other hand, if it is determined in step 116 that they overlap, the area of the needle trace formed last is obtained (step 116). In this case, since the overlapping portion is common between the previous time and this time, by subtracting the previous needle track area from the total area of the needle tracks formed by the previous time and this time, As described above, the area of the needle mark formed this time is obtained (step 117).

As described above, according to this embodiment, not only the repair-processed element but also the case where the probe needle is replaced is included as the opportunity to form the needle traces a plurality of times. .

[0076]

As described above, according to the first aspect of the invention, the quality of the contact state is determined based on at least one of the position and the area of the needle trace formed on the electrode pad. It As a result, if the position of the needle trace is not located on the electrode pad, or if it is located but does not have a predetermined area, the direct contact between the electrode pad and the probe needle is not sufficient, and a contact failure state occurs. It is possible to determine that

According to the second aspect of the present invention, the case where the needle trace is dislocated from the electrode pad can be detected by obtaining the area centroid of the needle trace based on the position information of the needle trace. As a result, even if a part of the needle trace is located on the electrode pad, if the area center of gravity of the needle trace is not within the predetermined range of the electrode pad, the contact state is set only by not increasing the contact resistance. It can be determined that it is not.

According to the third aspect of the present invention, the contact state can be determined by detecting that the contour is located in the electrode pad based on the contour of the needle trace. This makes it possible to determine the contact state by coping with the contour formation state.

In the invention according to claim 4, it can be judged that the removal of the oxide film by the probe needle is not complete when the needle trace area is less than a predetermined value, whereby the remaining condition of the oxide film or the contact pressure is determined. The contact state can be determined by coping with.

According to the fifth aspect of the invention, when the needle trace formed on the electrode pad is not the elliptical shape as described above and a portion is missing, the needle trace area is virtually from the remaining portion. Can be extracted and the contact state can be determined.

According to the sixth aspect of the invention, the contact state can be determined by coping with the case where the probe needle and the electrode pad are contacted a plurality of times. In particular, even when the needle marks are formed in a separated state on the electrode pad, the coping method described above is applied to the last needle mark.

According to the invention of claim 7, the area of the overlap portion on the side of the previous needle trace is included in the previous area from the sum of the area of the needle trace formed last time and the area of the needle trace formed last. By subtracting from the total sum, the final needle trace area including the area of the remaining overlap portion is obtained. Therefore, by subtracting one needle trace area from the total area of overlapping needle traces, it is possible to accurately determine the last formed needle trace area even in the overlapping needle trace formation state. You can

As described above, according to the present invention, in the step of inspecting an element on a semiconductor wafer, the color of the substrate of the element itself and the formation state of a needle mark formed in a state indistinguishable from each other can be reliably recognized. Instead, it becomes possible to determine the quality of the contact state between the probe needle and the pad substantially automatically by determining the formation state of the needle trace. As a result, the accuracy regarding the determination of the contact state is not reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a schematic configuration of a probe device according to the present invention.

FIG. 2 is a block diagram for explaining the configuration of a control system used in the probe device shown in FIG.

FIG. 3 is a schematic view showing an example of a formation state of needle marks.

FIG. 4 is a schematic view showing another example of a state where needle marks are formed.

FIG. 5 is a schematic diagram showing another example of the formation state of needle marks.

FIG. 6 is a schematic view showing still another example of the formation state of needle marks.

7 is a flow chart for explaining the operation of a control unit used in the apparatus shown in FIG.

[Explanation of symbols]

 10 probe device 18 image sensor 20 control unit 22 calculation unit 24 interpolation processing unit 26 area comparison unit 28 determination unit 32 storage unit 34 display unit

Claims (7)

[Claims] 1. A probe device having a probe needle capable of contacting an electrode pad of an element formed on a semiconductor wafer, wherein an image of a trace of a probe needle formed by contacting the electrode pad is imaged. A sensor, a calculator that calculates the area of the needle trace and the position of the needle trace on the electrode pad based on the output signal from the image sensor, and a storage unit that stores the area and the needle trace position calculated by the calculator. And a determination unit that determines whether the contact state between the probe needle and the electrode pad is good or bad based on at least one of the needle trace position and the needle trace area stored in the storage unit. A probe device characterized by: 2. The determination unit according to claim 1, wherein the determination unit obtains the barycentric position based on the needle trace position stored in the storage unit, and the barycentric position is not within a predetermined range in the electrode pad. In addition, the probe device is characterized by determining that the contact between the probe needle and the electrode pad is poor. 3. The determination unit according to claim 1, wherein the determination unit determines whether the contact state between the probe needle and the electrode pad is defective when the contour of the needle trace position stored in the storage unit is not within a predetermined range. A probe device characterized by the above. 4. The determination unit according to claim 1, wherein the determination unit determines whether the contact state with the probe needle electrode pad is defective when the needle trace area stored in the storage unit is equal to or smaller than a predetermined value. Probe device. 5. The interpolating unit according to claim 1, wherein the detecting unit interpolates a defective portion in the image when a case where a part of the needle trace is missing is detected based on the image information from the image sensor. And a probe device for determining a needle trace area or an area centroid based on the interpolation result. 6. The one of claims 1 to 5, wherein when the contact of the probe needle is repeated a plurality of times at the same position of the electrode pad, the needle trace formed at each time is not missing, When both of the needle traces do not overlap each other, the quality of the contact state of the probe needle is determined by obtaining the needle trace position and the needle trace area formed last. Probe device. 7. The determination unit according to claim 6, wherein the area of the needle trace area formed last time that does not overlap is A, and the area of the overlapping portion is C, and When the area of the non-overlapping area is B and the area of the overlapping portion is C, the needle area S formed at the end is S = (A + C + B + C )-(A + C).