JPH08264602A - Lsi voltage measuring method - Google Patents

Abstract

PURPOSE: To provide a technology for easily measuring an accurate LSI voltage. CONSTITUTION: The voltage of the ground pad PAD2 provided separately from a ground pad PAD1 for supplying power is measured, and the reference level of measuring the voltage by voltage measuring means is so calibrated as to be lowered by a drop voltage ΔV due to the contact resistance of the pad PAD1 with a probe needle 11. The influence of the voltage ΔV due to the contact resistance of the pad PAD1 with the needle 11 is excluded from the result of the LSI voltage measurement by such a calibration, thereby improving the accuracy of measuring an LSI voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a semiconductor integrated circuit (LS).
Regarding the voltage measurement technique of I), especially in probe inspection,
The present invention relates to a technique effectively applied to voltage measurement performed via a pad of an LSI.

[0002]

2. Description of the Related Art A single wafer has a plurality of semiconductor integrated circuit chip forming regions, and a plurality of semiconductor integrated circuit chips can be obtained by cutting this region by dicing. For dicing, a scribing method in which a cutting groove is mechanically created by cutting a laser or diamond needle chip, or a deep diamond is cut by high-speed rotation of a thin diamond wheel, and it is also possible to divide into individual semiconductor integrated circuit chips at the time of cutting There is a saw method.

Before dicing as described above, that is,
In order to test a semiconductor integrated circuit in a wafer state, a wafer prober used by being connected to a test apparatus is used. In the wafer prober, signals are input and output from the test equipment and power is supplied through the probe needles that are in contact with the pads on the surface of the semiconductor integrated circuit. Test the circuit one after another.

As an example of the document describing the wafer prober, "LSI Handbook (No. 6) issued by Ohmsha Co., Ltd. on November 30, 1984.
Page 53).

[0005]

In the voltage measurement by the test device, the contact resistance between the probe needle and the ground pad greatly affects the voltage measurement result. That is, when the contact resistance between the probe needle and the ground pad is large, the voltage drop there becomes so large that it cannot be ignored, and the measurement error becomes large. In particular, in a mode in which a large amount of current flows through the LSI, a large voltage drop occurs due to the contact resistance between the probe needle and the ground pad, so that the ground of the LSI and the ground of the test apparatus do not have the same potential, and L
The SI output voltage cannot be measured accurately. Therefore, conventionally, when the contact resistance between the probe needle and the ground pad is considered to be large, the operation of the test device is stopped and the probe needle pressure is manually adjusted so that the contact resistance becomes as small as possible. Was doing.

However, in such a method, the LS
The present inventor has found that the number of man-hours required for the I test is large and accurate probe inspection is also difficult.

An object of the present invention is to provide a technique for facilitating accurate LSI voltage measurement.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0009]

The outline of the representative one of the inventions disclosed in the present application will be briefly described as follows.

That is, when the voltage of the LSI (20) is measured by the LSI tester including the voltage measuring means (33) in which the reference potential in the voltage measurement of the LSI (20) is made common with the ground level of the power supply section, A power supply current is passed from the operation power supply unit to the LSI through the first ground pad (PAD1) provided in the LSI, and the second ground pad (PAD2) provided in the LSI separately from the first ground pad is used as a voltage measurement point. As the voltage measuring means (3
The voltage is measured according to 3), and the reference level of the voltage measuring means is calibrated or the measurement result of the voltage measuring means is corrected based on the measured value. This correction can be performed by subtracting the measured voltage value of the contact resistance from the measured voltage value of the LSI.

[0011]

According to the above-mentioned means, the power supply current is supplied to the LSI through the first ground pad, so that the first
The voltage drop caused by the contact resistance between the ground pad and the probe needle that is in contact with the ground pad is obtained by measuring the voltage of the second ground pad, and the reference level of the voltage measuring means is calibrated or the voltage measuring means is based on the voltage drop. Correcting the measurement result of 1) achieves improvement in accuracy of the LSI voltage measurement result.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 functionally shows a configuration example of an LSI test apparatus.

As shown in FIG. 2, the LSI test apparatus 30 includes a display section 31, a power supply section 32, a voltage measuring means 33,
The current measuring unit 34 and the operation unit 35 are included.

The power supply unit 32 functions as a power supply for the internal circuit of the LSI test apparatus 30 and the LSI to be measured.
It also has a function as a power supply for the operation of. With the function of the LSI as a power supply for operation, a power supply voltage required for the operation of the LSI, such as 5V or 3.3V, can be supplied to the LSI to be measured. The power supply voltage is supplied to the LSI to be measured through the pads formed on the LSI. That is, the probe needle provided at the tip of the probe pulled out from the power supply unit 32 is connected to the high potential side power (Vcc) pad of the LSI or the ground (Vss).
By making contact with the pad, it is possible to supply the power supply voltage to the LSI to be measured.

The voltage measuring means 33 is an L to be measured.
By bringing the probe needle into contact with the voltage measuring pad or the like provided in SI, the voltage value of the voltage measuring pad or the like can be measured. This voltage measurement result is displayed on the display unit 31.
Digitally displayed on.

The current measuring means 34 is an L to be measured.
Enables measurement of current flowing through SI. This current measurement includes current measurement between the pads with which the probe needles are in contact, and measurement of the current supplied from the power supply unit 32 to the LSI to be measured. This current measurement result is displayed on the display unit 31.
Digitally displayed on.

The operation unit 35 enables mode switching of the LSI test apparatus 30 and setting of measurement conditions. In particular, in the present embodiment, the operation portion 35 is provided with a switch 351 for calibrating the voltage measuring means 33. This switch 351 is, as described in detail later,
When pressed down while measuring the voltage due to the contact resistance between the pad and the probe needle, the voltage measuring means 33 calibrates the reference level.

Other functions of the LSI test apparatus 30 include an oscillating means 36 for generating a predetermined signal waveform such as a sine wave supplied through a signal input pad of the LSI, and an LSI to be measured. It includes a power measuring unit 37 capable of measuring the power of a signal obtained from a predetermined output pad, and a logic determining unit 38 capable of logically determining a predetermined pad of an LSI to be measured.

FIG. 1 shows a state of probe inspection of an LSI to be measured.

The LSI 20 to be measured is not particularly limited, but is a communication LSI, and includes the internal circuit 10 and a plurality of pads PAD1 to PAD1 drawn from the internal circuit 10.
A PAD 4 is provided. A plurality of probes are connected to the LSI test apparatus 30, and the probe needles 11 to 14 provided at the tips of the probes are connected to the pad P of the LSI 20.
By contacting AD1 to PAD4, LSI2
It is possible to supply operating power to 0, measure voltage, and the like. Although not particularly limited, the pad PAD1 is used for the first ground and the pad PAD4 is used for supplying the high potential side power supply Vcc. By bringing the probe needle 14 into contact with the pad PAD4 and bringing the probe needle 11 into contact with the pad PAD1, it is possible to supply operating power to the LSI 20 from the power supply section 32 incorporated in the LSI test apparatus 30. Further, the LSI 20 is provided with the above-mentioned ground pad PAD1.
In addition to the pad P, which has the same potential as the pad PAD1
AD2 is provided. The probe needle 12 contacting this pad PAD2 is taken out from the voltage measuring means 33. That is, the pad PAD1 is used for power supply, and the LSI2 is connected via the pad PAD1.
Although the power supply current IGND of 0 flows, the pad PAD2, which is set to the same potential as the pad PAD1, has a voltage drop due to a contact resistance between the pad PAD1 and the probe needle 11
This pad P is used for the measurement of
The power supply current of the LSI 20 does not flow through AD2. Usually, the current required for voltage measurement is extremely small, so that in the voltage measurement of the voltage drop due to the contact resistance between the pad PAD1 and the probe needle 11, the voltage drop due to the contact resistance between the pad 2 and the probe needle 12 is extremely small. It is small and negligible. Therefore, the voltage drop ΔV can be measured with high accuracy.

Next, the case where the voltage of the pad PAD3 is measured will be described.

Voltage measuring means 33 in the LSI test apparatus 30
The probe needle 13 provided at the tip of the probe pulled out from the contact with the pad PAD3 makes it possible to measure the voltage of the pad PAD3 for voltage measurement. Here, the ground of the voltage measuring means 33 and the power supply unit 3
The second ground is shared inside the LSI test apparatus 30. For this reason, the voltage value measured through the probe needle 13 is not only the pure output voltage VOUT from the internal circuit 10, but also the pad PAD1 and the probe needle 1 described above.
It is assumed that the voltage drop ΔV due to the contact resistance with 1 is superposed, and may be measured by the voltage measuring unit 33 as VOUT + ΔV.

However, the voltage of the pad PAD2 is measured before the voltage of the pad PAD3 is measured, and the reference level of the voltage measurement in the voltage measuring means 33 is calibrated based on the measurement result. The influence of the drop voltage ΔV can be eliminated. That is,
When the voltage of the pad PAD2 is measured and the switch 351 is pressed in that state, the reference level of the voltage measurement in the voltage measuring means 33 is lowered by the drop voltage ΔV due to the contact resistance between the pad PAD1 and the probe needle 11. Be shifted. With such a reference level calibration,
In the voltage measurement performed later, the influence of the drop voltage ΔV due to the contact resistance between the pad PAD1 and the probe needle 11 is excluded from the measurement result. Specifically, in the voltage measurement of the pad PAD3, the voltage display on the display unit 31 performed based on the voltage measurement result by the voltage measurement means 33 is (VOUT + ΔV) −ΔV = VOUT (1) , An accurate measurement of the pure output voltage VOUT from the internal circuit 10 and its display is possible.

According to the above embodiment, the following operational effects can be obtained.

(1) Before the voltage of the pad PAD3 is measured, the voltage of the pad PAD2 is measured, and the reference level for voltage measurement in the voltage measuring means 33 is calibrated based on the measurement result. Since the influence of the voltage drop ΔV can be eliminated, the output voltage VOUT from the internal circuit 10 can be accurately measured easily.

(2) The voltage of the pad PAD2 is measured,
When the switch 351 is pushed down in that state, the reference level for voltage measurement in the voltage measuring means 33 becomes the pad P.
Drop voltage Δ due to contact resistance between AD1 and probe needle 11
It is shifted by V. By such calibration, in the voltage measurement performed later, the influence of the drop voltage ΔV due to the contact resistance between the pad PAD1 and the probe needle 11 is eliminated from the measurement result, so that the output voltage VOUT from the internal circuit 10 is reduced. Accurate measurement and the resulting display are possible.

(3) Accurate LS due to the above effects
Since the I voltage can be easily measured, when the contact resistance between the probe needle and the ground pad seems to be large, the operation of the test equipment is stopped so that the contact resistance can be minimized as much as possible. Thus, it is not necessary to adjust the probe stylus pressure, and it is possible to reduce the number of LSI test work steps.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited thereto, and it goes without saying that various modifications can be made without departing from the scope of the invention. Yes.

For example, in the above embodiment, the pad PAD2
Voltage is measured, and in that state, the switch 351 is pressed to calibrate the reference level for voltage measurement in the voltage measuring means 33 so as to be lowered by the drop voltage ΔV due to the contact resistance between the pad PAD1 and the probe needle 11. However, it is conceivable that the voltage measuring means 33 is not calibrated. That is, the probe needle 13
Since it is clear that the voltage value measured via VOUT + ΔV, the voltage of the pad PAD2 is measured, and if ΔV is obtained as a result, the reference level of the voltage measuring means 33 need not be calibrated. An accurate output voltage VOUT from the internal circuit 10 can be obtained by the calculation of the equation (1).

The pad PAD2 is the pad PAD1.
Although it may be provided in the LSI 20 in advance only for measuring the drop voltage ΔV due to the contact resistance between the probe needle 11 and the probe needle 11, another pad can be used. That is, the pad PAD
As long as it has the same potential as 1, another pad such as an existing bonding pad may be used, which can be used as the second ground pad.

In the above description, the case where the invention made by the present inventor is mainly applied to the voltage measurement of the communication LSI which is the background field of application has been described.
The present invention is not limited to this, and can be applied to voltage measurement of various semiconductor integrated circuits.

The present invention can be applied under the condition that the voltage is measured at least via the pad provided in the LSI.

[0033]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, L via the first ground pad
The voltage drop due to the contact resistance between the first ground pad and the probe needle in contact with the SI is caused by the supply current flowing through SI, and the voltage drop of the second ground pad is obtained. Since the accuracy of the LSI voltage measurement result can be improved by calibrating the measurement means or correcting the measurement result of the voltage measurement means, accurate LSI voltage measurement can be easily performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of LSI voltage measurement to which a method according to an embodiment of the present invention is applied.

FIG. 2 is a functional block diagram of an LSI test apparatus that enables the LSI voltage measurement.

[Explanation of symbols]

 10 internal circuit 11, 12, 13, 14 probe needle 20 LSI 30 LSI test device 31 display unit 32 power supply unit 33 voltage measuring unit 34 current measuring unit 35 operating unit 36 oscillating unit 37 power measuring unit 38 logic determination unit 351 switch PAD1 PAD4 pad

Claims (3)

[Claims] 1. An LSI test apparatus comprising: a power supply unit for generating a power supply for operating an LSI; and a voltage measuring unit in which a reference potential in the voltage measurement of the LSI is shared with a ground level of the power supply unit. In the voltage measuring method, a power supply current is passed from the operation power supply unit to the LSI via a first ground pad provided on the LSI, and a second ground pad provided on the LSI separately from the first ground pad. The voltage measuring point is used as a voltage measuring point to measure the voltage, and the reference level of the voltage measuring means is calibrated based on the measured value.
I voltage measuring method. 2. An LSI test apparatus comprising: a power supply unit for generating a power supply for operating an LSI; and a voltage measuring unit in which a reference potential in the voltage measurement of the LSI is shared with a ground level of the power supply unit. In the LSI voltage measuring method, a probe needle pulled out from the ground of the power supply unit is brought into contact with a first ground pad provided on the LSI to supply a power supply current to the LSI, and the same potential as the first ground pad of the LSI. Measuring the voltage generated by the contact resistance between the first ground pad and the probe needle in contact therewith via the second ground pad, and correcting the voltage measurement value of the LSI based on the measurement result. An LSI voltage measuring method characterized by: 3. The voltage measurement value of the LSI is corrected by subtracting the measurement value of the voltage generated by the contact resistance between the first ground pad and the probe needle in contact with the first ground pad from the voltage measurement value of the LSI. The LSI according to claim 2,
Voltage measurement method.