JP7632974B2 - Inspection device and inspection method - Google Patents

Description

This disclosure relates to an inspection device and an inspection method.

Patent document 1 discloses a device inspection circuit that inspects the electrical characteristics of a semiconductor device to be inspected.

JP 2018-25519 A

However, there is a demand for shorter measurement times in testing equipment that measures the electrical characteristics of multiple semiconductor devices.

In one aspect, the present disclosure provides an inspection device and an inspection method that shortens measurement time.

In order to solve the above problem, according to one aspect, an inspection device is provided that has a power supply unit that applies a predetermined output voltage to a plurality of test objects, a switching unit that switches between the test objects for which current is to be measured, a measurement unit that measures the current of the test object selected by the switching unit, and a control unit that controls the switching unit, and the control unit switches between a sequential mode in which current measurements are performed a predetermined number of times on one test object, and then the switching unit is switched to perform a predetermined number of current measurements on other test objects, based on a set value related to current measurement, and a scan mode in which current measurements are performed on one test object, and then the switching unit is switched to perform current measurements on other test objects, and this is repeated a predetermined number of times.

According to one aspect, it is possible to provide an inspection device and an inspection method that shortens the measurement time.

FIG. 2 is a schematic cross-sectional view illustrating an example of a configuration of an inspection device according to the present embodiment. 1 is an example of a circuit diagram showing a circuit configuration of an inspection device according to an embodiment of the present invention. 4 is an example of a time chart illustrating a current measuring method. 13 is an example of a graph showing the relationship between the number of averaging operations and the current measurement time. 10 is a flowchart showing an example of control of a computer.

Below, a description will be given of a mode for carrying out the present disclosure with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicate descriptions may be omitted.

<Inspection equipment>
An inspection device 10 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is an example of a schematic cross-sectional view illustrating the configuration of the inspection device 10 according to this embodiment.

The inspection apparatus 10 is an apparatus that inspects the electrical characteristics of each of a plurality of semiconductor devices (devices under test, DUT) formed on a wafer (substrate) W. Note that the substrate having the device under test is not limited to the wafer W, but may include a carrier on which a semiconductor device is arranged, a glass substrate, a single chip, etc. The inspection apparatus 10 includes a storage chamber 12 that houses a chuck 11 on which the wafer W is placed, a loader 13 that is arranged adjacent to the storage chamber 12, and a tester 14 that is arranged to cover the storage chamber 12.

The accommodation chamber 12 has a hollow housing shape. Inside the accommodation chamber 12, a chuck 11 on which the wafer W is placed and a probe card 15 arranged opposite the chuck 11 are accommodated. The probe card 15 has a large number of needle-shaped probes (contact terminals) 16 arranged in correspondence with the electrode pads and solder bumps provided in correspondence with the electrodes of each semiconductor device on the wafer W.

The chuck 11 has a fixing mechanism (not shown) that fixes the wafer W to the chuck 11. This prevents the wafer W from shifting relative to the chuck 11. The accommodation chamber 12 is also provided with a moving mechanism (not shown) that moves the chuck 11 horizontally and vertically. This adjusts the relative positions of the probe card 15 and the wafer W, and brings the electrode pads and solder bumps provided corresponding to the electrodes of each semiconductor device into contact with each probe 16 on the probe card 15.

The loader 13 removes a wafer W on which a semiconductor device is placed from a FOUP (not shown), which is a transport container, and places it on a chuck 11 inside the storage chamber 12. It also removes the inspected wafer W from the chuck 11 and stores it in the FOUP.

The probe card 15 is connected to the tester 14 via the interface 17, and when each probe 16 contacts an electrode pad or solder bump provided corresponding to the electrode of each semiconductor device on the wafer W, each probe 16 supplies power from the tester 14 to the semiconductor device via the interface 17, or transmits a signal from the semiconductor device to the tester 14 via the interface 17.

The tester 14 has a test board (not shown) that reproduces part of the circuit configuration of the motherboard on which the semiconductor device is mounted, and the test board is connected to a computer 18 that judges the quality of the semiconductor device based on signals from the semiconductor device and controls it. By replacing the test board, the tester 14 can reproduce the circuit configuration of multiple types of motherboards.

Next, the circuit configuration of the inspection device 10 according to this embodiment will be described with reference to FIG. 2. FIG. 2 is an example of a circuit diagram showing the circuit configuration of the inspection device 10 according to this embodiment.

The inspection device 10 is an inspection device that inspects the electrical characteristics of multiple semiconductor devices 1. In the example shown in FIG. 2, the inspection device 10 will be described as an inspection device that inspects 16 semiconductor devices 1. In the following description, the 16 semiconductor devices 1 will also be referred to as DUT1, DUT2, ..., DUT16.

The tester 14 of the inspection device 10 (see FIG. 1) has a current sense amplifier 2, a current detection resistor 3, an amplifier 4, a digital-to-analog converter (DAC) 5, a switching unit 6, an analog-to-digital converter (ADC) 7, and a controller (control unit) 8. The current sense amplifier 2, the current detection resistor 3, and the amplifier 4 form a power supply unit 9 that supplies power to the semiconductor device (DUT) 1. There are 16 power supply units 9 provided, corresponding to the semiconductor devices 1.

The computer 18 issues commands to a controller 8, such as an FPGA (Field Programmable Gate Array), to control the tester 14.

The controller 8 outputs a set voltage signal (digital signal) to each DAC 5. The DAC 5 converts the digital signal into an analog signal and outputs it to the amplifier 4. The amplifier 4 applies a predetermined output voltage to the semiconductor device 1 based on the input analog signal.

A current detection resistor 3 is connected to the output of the amplifier 4 to measure the current supplied from the amplifier 4 to the semiconductor device 1. When a predetermined output voltage is applied to the semiconductor device 1, a potential difference corresponding to the current supplied from the amplifier 4 to the semiconductor device 1 is generated across the current detection resistor 3. The current sense amplifier 2 amplifies the potential difference across the current detection resistor 3 and outputs the amplified voltage signal (analog signal) to the ADC 7 via the switching unit 6.

That is, the power supply unit 9 receives a set voltage signal (digital signal) from the controller 8. The power supply unit 9 applies a predetermined output voltage to the semiconductor device 1 based on the input set voltage signal (digital signal). The power supply unit 9 also outputs an amplified voltage signal (analog signal) to the ADC 7 via the switching unit 6 as a signal corresponding to the current supplied to the semiconductor device 1.

The switching unit 6 is controlled by the controller 8, and switches the power supply unit 9 connected to the ADC 7 from among the multiple power supply units 9. In other words, the switching unit 6 switches the semiconductor device 1 for measuring the current from among the multiple semiconductor devices 1. The switching unit 6 has multiple relay switches whose opening and closing is controlled by the controller 8. One end of the relay switch is connected to the corresponding power supply unit 9. The other end of the relay switch is connected to the ADC 7. The controller 8 switches the power supply unit 9 connected to the ADC 7 by switching the relay switch.

The ADC 7 receives an amplified voltage signal (analog signal) from the power supply unit 9 (current sense amplifier 2) selected by the switching unit 6. The ADC 7 converts the analog signal into a digital signal and outputs it to the controller 8. The controller 8 also outputs the digital signal to the computer 18. In this way, the controller 8 measures the current supplied to the semiconductor device 1. In other words, the ADC 7, the controller 8, and the computer 18 constitute a measurement unit that measures the current supplied to the semiconductor device 1 selected by the switching unit 6.

The inspection device 10 also inspects multiple (16 in the example of FIG. 2) semiconductor devices 1. For this reason, the inspection device 10 has multiple (16 in the example of FIG. 2) power supply units 9 corresponding to the semiconductor devices 1. On the other hand, the inspection device 10 has one ADC 7 for the multiple power supply units 9. This allows the inspection device 10 to measure the current supplied to the multiple semiconductor devices 1 with one ADC 7 by switching the channel of the switching unit 6.

Next, the current measurement method will be described with reference to FIG. 3. FIG. 3 is an example of a time chart illustrating the current measurement method. Here, the inspection device 10 performs n current measurements on one semiconductor device 1 and averages the measurements. This allows for accurate current measurement. That is, the inspection device 10 performs n current measurements for each of the 16 semiconductor devices 1 (DUT1 to DUT16), averaging the measurements. In the following description, the time required to perform n current measurements on each of the 16 DUTs is referred to as the "current measurement time."

Here, the time from when the current measurement starts until the next current measurement is permitted for the same semiconductor device 1 is defined as the interval time t1.

When switching the channel of the switching unit 6, a waiting time is required for the switching unit 6, etc. The time from switching the channel of the switching unit 6 to starting current measurement is defined as the channel waiting time (CH WAIT) t2.

Furthermore, the measurement time for one measurement of semiconductor device 1 is set to t3.

The interval time t1 and the number of averaging times n are specified by the user according to, for example, the inspection of the semiconductor device 1, and are input to the computer 18. The channel waiting time t2 and the time for one measurement t3 are values that are preset according to, for example, the characteristics of the inspection device 10 (e.g., the response time of the switching unit 6 and the ADC 7, etc.), and are stored in advance in the computer 18.

Figure 3(a) is an example of a time chart explaining the sequential current measurement method. In the sequential current measurement method, current measurements are repeatedly performed n times on one DUT 1, the channel of the switching unit 6 is switched, and then current measurements are repeatedly performed n times on DUT 2. This is repeated up to DUT 16. In other words, in the sequential current measurement method, after current measurements are performed a predetermined number of times on one semiconductor device 1, the switching unit 6 is switched and current measurements are performed a predetermined number of times on another semiconductor device 1.

In the sequential current measurement method, first, the channel of the switching unit 6 is switched to measure DUT1. After a channel waiting time t2, the first measurement of DUT1 is performed. If t1>t3, then the second measurement of DUT1 is performed after the interval time t1 has elapsed. On the other hand, if t1≦t3, then the second measurement of DUT1 is performed immediately after the first measurement of DUT1. The measurement of DUT1 is continued until n measurements have been performed.

Next, the channel of the switching unit 6 is switched to measure DUT2. After the channel waiting time t2, the first measurement of DUT2 is performed. Thereafter, similar to the case of DUT1, measurements of DUT2 are performed until the number of n measurements has been reached.

By performing this process for DUT1 to DUT16, the current measurements of DUT1 to DUT16 by the inspection device 10 are completed.

The current measurement time in the sequential method can be calculated using the following equations (1) and (2).
In the case of t1>t3, (t1×n+t2)×16 ... (1)
In the case of t1≦t3, (t3×n+t2)×16 ... (2)

Figure 3(b) is an example of a time chart explaining the scan-type current measurement method. In the scan-type current measurement method, the channel of the switching unit 6 is switched to perform a first current measurement on DUT1 to DUT16, and then the channel of the switching unit 6 is switched to perform a second current measurement on DUT1 to DUT16. This is repeated until the number of measurements reaches n. In other words, in the scan-type current measurement method, after performing a current measurement on one semiconductor device 1, the switching unit 6 is switched to perform a current measurement on another semiconductor device 1, and this is repeated a predetermined number of times.

In the scan-type current measurement method, first, the channel of the switching unit 6 is switched to measure DUT1. After a channel wait time t2, the first measurement of DUT1 is performed. Next, the channel of the switching unit 6 is switched to measure DUT2. After a channel wait time t2, the first measurement of DUT2 is performed. This is performed for DUT1 to DUT16, completing the first measurement of DUT1 to DUT16.

Here, if t1 > (t2 + t3) x 16, the second measurement of DUT1 to DUT16 is performed after the interval time t1 has elapsed. On the other hand, if t1 ≤ (t2 + t3) x 16, the second measurement of DUT1 to DUT16 is performed immediately after the first measurement of DUT1 to DUT16. The measurements of DUT1 to DUT16 are continued until n measurements have been made.

The current measurement time in the scan method (n tests for each of 16 DUTs) can be calculated using the following equations (3) and (4).
If t1>(t2+t3)×16, then t1×n...(3)
When t1≦(t2+t3)×16, ((t2+t3)×16)×n ... (4)

Thus, the current measurement times in the sequential and scan methods are determined by four parameters (set values): interval time t1, channel wait time t2, measurement time per measurement t3, and number of averagings n. Figure 4 is an example of a graph showing the relationship between the number of averagings n and the current measurement time. The horizontal axis indicates the number of averagings n, and the vertical axis indicates the current measurement time. The solid line indicates the current measurement time in the scan method, and the dashed line indicates the current measurement time in the sequential method. In the example of Figure 4, when the number of averagings n is less than n1, the current measurement time in the scan method is shorter than the current measurement time in the sequential method. When the number of averagings n is n1 or more, the current measurement time in the sequential method is shorter than the current measurement time in the scan method.

Based on the set parameters (interval time t1, channel waiting time t2, measurement time per measurement t3, and number of averaging times n), the computer 18 selects the measurement method that will shorten the measurement time from the sequential method and the scan method, and performs the inspection using the selected measurement method.

Figure 5 is a flowchart showing an example of the control of computer 18.

In step S101, the computer 18 accepts input of parameters (setting values). For example, the user inputs the interval time t1 and the number of averaging times n to the computer 18 in accordance with the inspection of the semiconductor device 1. Note that the channel waiting time t2 and the time for one measurement t3 may be input to the computer 18 in advance, or may be input to the computer 18 by the user.

In step S102, the computer 18 calculates the current measurement time using the sequential method based on the parameters and equations (1) and (2).

In step S103, the computer 18 calculates the current measurement time using the scan method based on the parameters and equations (3) and (4).

In step S104, the computer 18 selects a measurement method based on the calculated current measurement time.

In step S105, the computer 18 performs current measurements on the semiconductor device 1 (DUT1 to DUT16) using the selected measurement method.

According to the inspection device 10 of this embodiment, a measurement method that shortens the current measurement time is selected, and the current measurement is performed using the selected measurement method. In other words, according to the inspection device 10 of this embodiment, the current measurement time can be shortened by switching between the sequential method and the scan method depending on the inspection conditions.

The above describes the inspection device 10, but the present disclosure is not limited to the above-described embodiment, and various modifications and improvements are possible within the scope of the gist of the present disclosure described in the claims.

1. Semiconductor device (test object)
2 Current sense amplifier 3 Current detection resistor 4 Amplifier 5 Digital-to-analog converter 6 Switching unit 7 Analog-to-digital converter (measurement unit)
8 Controller (control unit)
9 Power supply unit 10 Inspection device 14 Tester 18 Computer W Wafer

Claims (6)

a power supply unit that applies a predetermined output voltage to a plurality of devices under test;
A switching unit for switching the test object for measuring a current;
a measurement unit that measures a current of the device under test selected by the switching unit;
A control unit that controls the switching unit,
The control unit is
Based on the current measurement settings you have made,
a sequential method in which current measurements are performed a predetermined number of times on one test object, and then the switching unit is switched to perform current measurements a predetermined number of times on another test object;
a scanning mode in which, after performing current measurement on one test object, the switching unit is switched to perform current measurement on another test object, and this process is repeated a predetermined number of times.
Inspection equipment. The control unit is
calculating a current measurement time in the sequential mode and a current measurement time in the scan mode based on the set value;
switching between the sequential mode and the scan mode based on the calculated current measurement time;
2. The inspection device according to claim 1. The set value is
an interval time that is a time from when a current measurement is started until the next current measurement is permitted for the same test object;
and an averaging number, which is the number of times current measurement is repeated for one test object.
3. The inspection device according to claim 1 or 2. The set value is
The measurement time for one measurement of the test object,
A waiting time until starting current measurement after switching the switching unit.
4. The inspection device according to claim 3. The power supply unit is provided in a plurality of units corresponding to the plurality of devices under test.
The inspection device according to any one of claims 1 to 4. 1. A method for testing an inspection apparatus for applying a predetermined output voltage to a plurality of devices under test and measuring a current of a selected device under test, comprising the steps of:
a step of calculating a sequential current measurement time in which current measurement is performed a predetermined number of times on one test object and then a predetermined number of times on another test object based on a set value related to the current measurement, and a scan current measurement time in which current measurement is performed a predetermined number of times on one test object and then a predetermined number of times on another test object;
selecting the sequential mode or the scan mode based on the calculated current measurement time;
and measuring the current of the device under test in a selected manner.
Testing method.

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