JP2003059987A - Semiconductor wafer prober and method for measuring electric characteristic of semiconductor chip using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abnormal measurement of the electrical characteristics of a semiconductor chip due to increase in the contact resistance of a probe without lowering productivity of semiconductor wafer significantly. SOLUTION: The semiconductor wafer prober 100 comprises a probe card 12 provided with a probe 11, a stage 20, a polishing mechanism 30, a contact resistance measuring section 50, and a tester 60. When the electrical characteristics of a semiconductor chip are measured using it, contact resistance of the probe 11 is measured, at first, at the contact resistance measuring section 50 and a management value of contact resistance is determined. Subsequently, a confirmation frequency of contact resistance is set, electrical characteristics of the semiconductor chip are measured, contact resistance of the probe 11 is measured at a confirmation frequency set in the way of measurement, and that measurement is compared with the management value. The probe is polished if the measurement is not lower than the management value, otherwise electrical characteristics of the semiconductor chip are measured continuously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer prober for measuring electrical characteristics of a plurality of semiconductor chips formed on a semiconductor wafer and a method for measuring electrical characteristics of semiconductor chips using the semiconductor wafer prober. Specifically, a semiconductor wafer prober is equipped with a contact resistance measurement unit that measures the contact resistance of the measurement probe, and while measuring the electrical characteristics of the semiconductor chip, the contact resistance of the probe can be left on the test board with the probe card set. By making it possible to confirm at any frequency, it is possible to prevent abnormal measurement of the electrical characteristics of the semiconductor chip due to an increase in the contact resistance of the measurement probe without significantly reducing productivity, and a semiconductor wafer prober and it. The present invention relates to a method for measuring electrical characteristics of a semiconductor chip used.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor device, a semiconductor chip is formed on a semiconductor wafer by a wafer process, and then the electrical characteristics of a plurality of semiconductor chips formed on these semiconductor wafers are measured. A measuring probe test is performed. Conventionally, this probe test is performed using a semiconductor wafer prober 1 as shown in FIG. 7, for example. As shown in FIG. 7, the semiconductor wafer prober 1 includes a probe card 12 provided with a measurement probe 11, a holding stage 20 for holding a wafer 20a, and a polishing mechanism 30 for polishing the tip of the probe 11. And a measurement tester 40.
The probe card 12 is mounted on the test board 10 for use.

The probe card 12 is provided with a probe 11 having a plurality of needle-like terminals for making contact with the electrode pads of the semiconductor chip. This probe card 12
Is connected to the tester 40 via the test board 10 and the cable 40a. The electric signal from the tester 40 is input to the semiconductor chip via the probe card 12,
Further, the signal from the semiconductor chip is transferred to the tester 40 via the probe card 12.

The stage 20 can hold a wafer 20a to be measured by vacuum suction. Further, a horizontal (X, Y direction) drive unit 21 and a vertical (Z direction) drive unit 22 are provided so that the stage 20 can move in three-dimensional directions of X, Y, Z.

The polishing mechanism 30 comprises a polishing plate 30a and a polishing stage 30b on which the polishing plate 30a is mounted. The polishing stage 30b is joined to the holding stage 20 by a joining jig 30c. The polishing mechanism 30 is for polishing the tip of the probe 11.

When the electrical characteristics of a semiconductor chip in a wafer state are measured using the semiconductor wafer prober 1 as shown in FIG. 7, first, the surface of the wafer 20a is faced up, and the wafer 20a is mounted on the stage 20 by vacuum suction. Hold on the surface. Next, the stage 20 is moved horizontally by the horizontal drive unit 21 to determine the position of the semiconductor chip to be measured, and then the stage 20 is moved to the vertical drive unit 22.
Then, the electrode pad of the semiconductor chip and the probe 11 are brought into contact with each other to measure.

At this time, from the tester 40 to the probe 11
An input signal having a predetermined waveform is applied to the semiconductor chip in a state where a power supply voltage is applied to the semiconductor chip through the semiconductor chip to operate the semiconductor chip. Further, the output signal from the semiconductor chip returns to the tester 40. The tester 40 compares the waveform of the output signal of the semiconductor chip at this time with a pre-programmed normal signal waveform to determine whether the semiconductor chip is good or bad.

As described above, after the measurement of one semiconductor chip is completed, the vertical drive unit 22 of the stage 20 is lowered to its original position, and the horizontal drive unit 21 driven in the horizontal direction is moved to the measurement position of the next semiconductor chip. By moving the stage 20 again by the vertical drive unit 22, the next semiconductor chip is measured.

In the semiconductor wafer prober 1 as shown in FIG. 7, in order to accurately measure the electrical characteristics of the semiconductor chip, the measuring probe 11 is attached to the electrode pad of the semiconductor chip.
Must be contacted with a contact resistance of a certain value or less. Further, since the probe 11 is a consumable item, the tip changes with time due to damage due to measurement (for example, a film is attached to the surface or tip deformation), and the contact resistance shifts to a higher direction. Therefore, conventionally, the tip of the probe 11 is polished by the polishing plate 30a at a frequency that can be arbitrarily set to suppress an increase in the contact resistance of the probe 11.

[0010]

However, when measuring the electrical characteristics of a semiconductor chip using the above-mentioned semiconductor wafer prober 1, the probe 1 may be used in any state.
It is difficult to predict whether the contact resistance of 1 will increase, and the operator is afraid that a measurement abnormality will occur,
Since the probe 11 is frequently polished, the tip of the probe 11 is abraded by repeated polishing, and its performance cannot be maintained. Further, in order to confirm the contact resistance after polishing, the probe 11 must be removed once and measured with a dedicated probe tester, which causes a work of setting the probe 11 again on the semiconductor wafer prober 1, resulting in a significant decrease in productivity. To do. On the contrary, if the frequency of polishing is reduced in order to extend the life of the probe 11, there is a problem that a measurement abnormality occurs due to a defective contact resistance and a yield is reduced.

Therefore, the present invention is directed to a semiconductor wafer prober and a semiconductor wafer prober which can prevent abnormal measurement of electrical characteristics of a semiconductor chip due to an increase in contact resistance of a measurement probe without significantly lowering the productivity of the semiconductor wafer. Another object of the present invention is to provide a method for measuring the electrical characteristics of a semiconductor chip.

[0012]

A semiconductor wafer prober according to the present invention is a semiconductor wafer in which a measuring probe is brought into contact with an electrode pad of a semiconductor chip formed on the semiconductor wafer to measure the electrical characteristics of the semiconductor chip. A contact resistance measurement including a holding stage for holding a semiconductor wafer, a test board for setting a probe card having a measuring probe, and a contact resistance measuring wafer for measuring the contact resistance of the measuring probe. Section, a tester connected to the test board via a cable for measuring the electrical characteristics of the semiconductor chip and the contact resistance of the measuring probe, and a measurement probe for measuring the electrical characteristics of the semiconductor chip. Contact the electrode pad of the specified semiconductor chip on the semiconductor wafer. And a drive means for moving the contact resistance measuring unit so that the measuring probe contacts the surface of the contact resistance measuring wafer when measuring the contact resistance of the measuring probe. It is a thing.

A method of measuring the electrical characteristics of a semiconductor chip according to the present invention is a method of measuring the electrical characteristics of a semiconductor chip by bringing a measuring probe into contact with an electrode pad of the semiconductor chip formed on a semiconductor wafer. And
Before measuring the electrical characteristics of the semiconductor chip, the contact resistance of the measuring probe is measured using the contact resistance measuring unit, and the control value of the contact resistance is determined based on the result of this measurement. For each measurement of the electrical characteristics of, measure the contact resistance of the measurement probe,
When the measured value of the contact resistance is equal to or higher than the control value, the measurement probe is polished, and when the measured value of the contact resistance is lower than the control value, the measurement of the electrical characteristics of the semiconductor chip is continued.

In the present invention, the semiconductor wafer prober is provided with the contact resistance measuring section for measuring the contact resistance of the measuring probe, so that the contact resistance of the measuring probe can be measured while the electrical characteristics of the semiconductor chip are being measured. The probe card can be checked at any frequency with it set, and it is possible to prevent abnormal measurement of the electrical characteristics of the semiconductor chip due to an increase in the contact resistance of the probe without reducing productivity. It will be possible.

Further, since the contact resistance can be confirmed before the probe is polished and the necessity of polishing can be confirmed, the number of times of probe polishing can be suppressed and the life of the probe can be extended.

Further, since data collected at each frequency can be trend-managed by using a method such as stored program control, an increase in contact resistance due to deterioration of the tip of the probe can be found in advance. It is possible to prevent occurrence of measurement abnormality. Also,
Costs can be reduced because there is no need for a probe tester dedicated to probes, which is expensive equipment.

[0017]

1 shows the structure of a semiconductor wafer prober 100 according to an embodiment of the present invention. This semiconductor wafer prober 100 is for measuring the electrical characteristics of a plurality of semiconductor chips formed on a semiconductor wafer. In FIG. 1, parts corresponding to those in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, the semiconductor wafer prober 100 polishes the probe card 12 provided with the measurement probe 11, the holding stage 20 for holding the semiconductor wafer 20a, and the tip of the probe 11. The polishing mechanism 30 includes a contact resistance measuring unit 50 that measures the contact resistance of the probe 11, and a tester 60 that measures the electrical characteristics of the semiconductor chip and the contact resistance of the probe 11. Probe card 1
2 is mounted on the test board 10 for use.

The probe card 12 is provided with a probe 11 having a plurality of needle terminals for contacting the electrode pads of the semiconductor chip. This probe card 12
Is connected to the tester 60 via the test board 10 and the cable 60a. The electric signal from the tester 60 is input to the semiconductor chip via the probe card 12,
Further, the signal from the semiconductor chip is transferred to the tester 60 via the probe card 12.

The stage 20 can hold the wafer 20a to be measured by vacuum suction. Further, the stage 20 is provided with a horizontal (X, Y direction) drive unit 21 and a vertical (Z direction) drive unit 22 as drive means so that the stage 20 can move in three-dimensional directions of X, Y, Z. The movement of the stage 20 is controlled by a control signal from the tester 60, although a control line is not shown.

The polishing mechanism 30 comprises a polishing plate 30a and a polishing stage 30b on which the polishing plate 30a is mounted. The polishing stage 30b is joined to the holding stage 20 by a joining jig 30c. The polishing mechanism 30 is for polishing the tip of the probe 11.

The contact resistance measuring section 50 includes a contact resistance measuring wafer 50a and the measuring wafer 50.
and a contact resistance measuring stage 50b to which a is mounted. This measuring stage 50b is connected to the joining jig 5
It is joined to the holding stage 20 by 0c. On the surface of the measurement wafer 50a, a layer having a small specific resistance value (for example, a film obtained by vapor deposition of Al or Au) is formed. The measuring wafer 50a is fixed to the measuring stage 50b by vacuum suction or a mechanical fixing mechanism.

The tester 60 sends and receives and processes an electrical signal for measuring the electrical characteristics of the semiconductor chip to be measured and the contact resistance of the probe 11.

Such a semiconductor wafer prober 100
When measuring the electrical characteristics of the semiconductor chip by using, the contact resistance of the probe 11 is first measured by the contact resistance measuring unit 50, and the control value of the contact resistance is determined based on the measured contact resistance. The contact resistance confirmation frequency is set, then the electrical characteristics of the semiconductor chip are measured, and in the middle of this measurement, the contact resistance of the probe 11 is measured at the confirmation frequency set as described above, and this measured value is managed. Compared with the value, when the measured value is above the control value, the probe 11 is polished, and when the measured value is less than the control value,
Continue measuring the electrical characteristics of the semiconductor chip.

A method of measuring the electrical characteristics of this semiconductor chip will be further described with reference to FIGS.
FIG. 2 shows the configuration of the measurement probe 11, and FIG. 3 is a flowchart showing the measurement process. First, as shown in FIG. 1, with the surface of the wafer 20a facing upward, the wafer 20a is held on the stage 20 by vacuum suction.

Next, step S1 shown in FIG. 3 is performed. The probe card 12 determined to be proper in advance is set on the test board 10 of the semiconductor wafer prober 100, the stage 20 is horizontally moved by the horizontal drive unit 21, and the contact resistance measurement unit 50 is moved below the probe 11.
In addition, the vertical drive unit 22 uses the contact resistance measurement stage 5
0b is moved upward, the probe 11 is brought into contact with the contact resistance measuring wafer 50a, and the contact resistance of the probe 11 is measured. For example, in the case of the probe configuration as shown in FIG. 2, between 11a-11b, 11b-11c
, 11c-11d, 11d-11e, 11e-1
Between 1f, 11f-11g, 11g-11h, 11h
Each resistance value between −11a is measured, and the measurement result is stored in the memory in the tester 60. The contact resistance control value is determined from the resistance value obtained here, and the tester 60
Keep it in the internal memory.

In this case, the resistance R between the probes is as shown in FIG.
As shown in, the sum of the contact resistance (R11a) of the probe (for example, 11a), the contact resistance (R11b) of the probe (for example, 11b), and the resistance r of the surface of the contact resistance measuring wafer 50a between the both probes. Is. Contact resistance of each probe (eg R11a)
Is usually about 0.5Ω, and the resistance r on the surface of the contact resistance measuring wafer 50a is almost zero.

Next, step S2 is performed. Probe 11
The check frequency of the contact resistance is set to the tester 60 arbitrarily. For example, the content of the instruction to measure the contact resistance of the probe 11 is added to the measurement program each time the electrical characteristics of the semiconductor chip are measured N times. This N may be the total number of chips in the wafer.

Next, step S3 is performed. The number of times of measuring the electrical characteristics of the semiconductor chip is confirmed, and if the number of times is not the set number of times, the measuring operation of the electrical characteristics of the semiconductor chip is executed in step 6. At this time, the stage 20 is moved horizontally by the horizontal drive unit 21 of the stage 20, and the position of the semiconductor chip to be measured is determined.
Is moved upward by the vertical drive unit 22, the electrode pad of the semiconductor chip is brought into contact with the probe 11, and a constant waveform input signal is applied to the semiconductor chip while the power supply voltage is applied from the tester 60 to the semiconductor chip via the probe 11. Then, the semiconductor chip is operated. Also, the waveform of the output signal from the semiconductor chip is measured. Compare and judge the waveform of this output signal with the normal signal waveform programmed in advance,
Determines whether a semiconductor chip is good or bad.

As a result of confirmation in step S3, the set number N
If so, step S4 is performed. A signal is transmitted from the tester 60, the measurement of the electrical characteristics of the semiconductor chip is temporarily stopped, the contact resistance measuring wafer 50a is brought into contact with the probe 11, and the contact resistance between the probes of the probe 11 is measured. Next, in step S5, based on this measurement result, it is compared with the control value held in the tester 60 to judge the suitability of the probe 11. For example, when the resistance R between the probe terminals is compared with the control value and the resistance R is lower than the control value, it is defined as L,
When the resistance R is higher than the control value, it is defined as H. As shown in FIG. 5, R values between 11a and 11b are L and 11b.
The R value between −11c is H, the R value between 11c and 11d is H,
When the R value between 11d and 11e is L, it can be determined that the probe 11c is deteriorated. At this time, the measured value of the contact resistance of the probe 11 is higher than the control value.

According to the result of the comparison, if the resistances R between all the probes are all lower than the control value, the measurement work is continued (step S6). If the resistance R between one or more probes is higher than the control value, step S7 is performed. From the tester 60 to the horizontal drive unit 21,
By sending a control signal to the vertical drive unit 22, the polishing plate 30
A is brought into contact with the probe 11, and the tip of the probe 11 is polished. After polishing, the contact resistance measuring wafer 50a is again measured by the probe 11 to measure the contact resistance again.
And contact resistance is measured by the method described above (step S8). Then, in step 9, the measurement result is compared with the control value held in the tester 60, and if it is below the control value, the measurement operation is continued as it is (step S6). If it is above the control value, probe card 12
Need to be replaced, the measurement work is stopped, and the operator is notified by an alarm (alarm mechanism not shown in FIG. 1) (step 10).

When it is confirmed in step S11 shown in FIG. 3 that all the wafers 20a have been measured, the measurement is completed.

As described above, in the present embodiment, by providing the semiconductor wafer prober 100 with the contact resistance measuring unit 50 for measuring the contact resistance of the probe 11, the contact resistance of the probe 11 can be confirmed during the measurement. It is possible to prevent measurement abnormalities due to an increase in contact resistance of the device.

Further, since the contact resistance of the probe 11 can be confirmed with the probe card 12 still set on the test board 10, the probe card 12 is removed from the test board 10 and the measurement work by the dedicated probe tester is performed. There is no need to set the probe card on the test board of the semiconductor wafer prober again, and a large decrease in productivity can be suppressed.

Further, since the contact resistance can be confirmed before the probe 11 is polished and the necessity of polishing can be confirmed, the number of times the probe 11 is polished can be suppressed and the life of the probe 11 can be extended. Become. Further, since it is possible to manage the tendency of the data collected at each frequency, it is possible to detect an increase in contact resistance due to deterioration of the tip of the probe 11 in advance and prevent occurrence of measurement abnormality. Further, there is no need for a probe tester dedicated to the probe, which is an expensive facility, and the cost can be reduced.

Although the contact resistance measuring unit 50 is bonded to the holding stage 20 in the above embodiment, the present invention is not limited to this. For example, as shown in FIG. 6, the contact resistance measuring unit 50 may be installed separately. In this case, the contact resistance measuring stage 50b can be moved in the three-dimensional directions of X, Y, Z so that the horizontal driving unit 51 and the vertical driving unit 52 can be moved.
Driven by. The contact resistance measuring wafer 50a in which the probe 11 is installed on the contact resistance measuring stage 50b by the horizontal driving unit 51 and the vertical driving unit 52.
Can be contacted with.

Although the contact resistance measuring stage 50b is newly provided in the above-mentioned embodiment, the present invention is not limited to this. For example, the polishing stage 30b may be used to place the contact resistance measuring wafer 50a in place of the polishing plate 30a.

Further, for example, by using the polishing stage 30b, the polishing plate 30a and the contact resistance measuring wafer 50a may be permanently provided in each half on the polishing stage 30b. In this case, when the probe 11 needs to be polished, the probe 11 is polished by a polishing device provided separately from the semiconductor wafer prober 100.

For the contact resistance, the stored data is subjected to trend management using a method such as storage program control (SPC), and the tip of the probe is polished before the contact resistance exceeds the control value. May be systematized.

[0040]

According to the present invention, the contact resistance measuring unit for measuring the contact resistance of the probe is installed in the semiconductor wafer prober, and the contact resistance of the probe is measured during the measurement of the electrical characteristics of the semiconductor chip. The probe card can be checked on the test board at any frequency with it set, and it is possible to prevent abnormal measurement of the electrical characteristics of the semiconductor chip due to an increase in the contact resistance of the probe without significantly reducing productivity. .

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a semiconductor wafer prober according to an embodiment.

FIG. 2 is a diagram showing a configuration of a probe.

FIG. 3 is a flowchart of measurement using the semiconductor wafer prober of the embodiment.

FIG. 4 is a diagram showing a configuration of a resistance R between each probe.

FIG. 5 is a diagram showing a comparison result of resistance R between each probe.

FIG. 6 is a diagram showing another example of the semiconductor wafer prober of the embodiment.

FIG. 7 is a diagram showing a configuration of a conventional semiconductor wafer prober.

[Explanation of symbols]

1, 100 ... Semiconductor wafer prober, 11 ...
Probe, 12 ... Probe card, 20 ... Stage, 20a ... Wafer, 21, 51 ... Horizontal driving unit, 22, 52 ... Vertical driving unit, 30 ... Polishing mechanism, 30a. ..Polishing plate, 30b ... Polishing stage,
30c, 50c ... Joining jig, 40, 60 ... Tester, 40a, 60a ... Cable, 50 ... Contact resistance measuring section, 50a ... Contact resistance measuring wafer, 50b ... Contact Resistance measurement stage

Claims (3)

[Claims] 1. A semiconductor wafer prober for measuring the electrical characteristics of a semiconductor chip by bringing a measuring probe into contact with an electrode pad of the semiconductor chip formed on the semiconductor wafer, which holds the semiconductor wafer. A stage, a test board on which a probe card having the measurement probe is set, a contact resistance measurement unit having a contact resistance measurement wafer for measuring the contact resistance of the measurement probe, and a cable to the test board. And a tester for measuring the electrical characteristics of the semiconductor chip and the contact resistance of the measuring probe, and the measuring probe of the semiconductor wafer is used when measuring the electrical characteristics of the semiconductor chip. Keep the above so that it contacts the electrode pad of the specified semiconductor chip. And a driving means for moving the contact resistance measuring unit so that the measuring probe contacts the surface of the contact resistance measuring wafer when measuring the contact resistance of the measuring probe. A semiconductor wafer prober characterized by the above. 2. The semiconductor wafer prober according to claim 1, further comprising a polishing mechanism having a polishing plate for polishing the measurement probe. 3. A measuring method for measuring an electric characteristic of a semiconductor chip by bringing a measuring probe into contact with an electrode pad of the semiconductor chip formed on a semiconductor wafer, wherein the electric characteristic of the semiconductor chip is measured. Before measuring, measure the contact resistance of the measurement probe using the contact resistance measuring unit, determine the control value of the contact resistance based on the measurement result, and measure the electrical characteristics of the semiconductor chip a certain number of times. For each, measuring the contact resistance of the measurement probe, when the measured value of the contact resistance is above the control value,
A method for measuring electrical characteristics of a semiconductor chip, comprising: polishing the measurement probe; and continuing to measure the electrical characteristics of the semiconductor chip when the measured value of the contact resistance is smaller than the control value.