Inspection apparatus and inspection method

Abstract

This invention provides an inspection apparatus and method capable of shortening measurement time. The inspection apparatus includes: an electrical power supply unit that applies a predetermined output voltage to a plurality of inspected objects; a switching unit that switches the inspected objects for which current is to be measured; a measurement unit that measures the current of the inspected object selected by the switching unit; and a control unit that controls the switching unit, wherein the control unit switches between a sequential mode and a scanning mode based on a set value for current measurement. The sequential mode is a mode in which current is measured a predetermined number of times on one inspected object, and then the switching unit is switched to measure the current of other inspected objects a predetermined number of times. The scanning mode is a mode in which the process of measuring the current of one inspected object and then the switching unit is switched to measure the current of other inspected objects a predetermined number of times is repeated.

Description

Technical Field

[0001] This invention relates to an inspection apparatus and an inspection method. Background Technology

[0002] Patent Document 1 discloses a device inspection circuit for inspecting the electrical characteristics of a semiconductor device that is to be inspected.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-25519 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, in inspection apparatuses that measure the electrical characteristics of multiple semiconductor devices, it is necessary to reduce the measurement time.

[0008] In one aspect, the present invention provides an inspection apparatus and inspection method that shortens measurement time.

[0009] Technical solutions for solving technical problems

[0010] To solve the aforementioned technical problems, according to one approach, an inspection device is provided, comprising: an electrical power supply unit that applies a predetermined output voltage to a plurality of inspected objects; a switching unit that switches between the inspected objects whose current is to be measured; a measuring unit that measures the current of the inspected object selected by the switching unit; and a control unit that controls the switching unit, wherein the control unit switches between a sequential mode and a scanning mode based on a set value for current measurement, wherein the sequential mode is a mode in which the switching unit is switched to measure the current of other inspected objects a predetermined number of times after a predetermined number of current measurements are performed on one inspected object, and the scanning mode is a mode in which the process of measuring the current of other inspected objects is repeated a predetermined number of times after a predetermined number of current measurements are performed on one inspected object, and the switching unit is switched to measure the current of other inspected objects.

[0011] Invention Effects

[0012] In one respect, it is possible to provide inspection devices and inspection methods that shorten measurement time. Attached Figure Description

[0013] Figure 1 This is an example of a cross-sectional schematic diagram illustrating the structure of the inspection device according to this embodiment.

[0014] Figure 2 This is an example of a circuit diagram showing the circuit structure of the inspection device according to this embodiment.

[0015] Figure 3 This is an example of a timing diagram illustrating a current measurement method.

[0016] Figure 4 This is an example of a graph showing the relationship between the average number of measurements and the current measurement time.

[0017] Figure 5 This is a flowchart illustrating an example of computer control.

[0018] Explanation of reference numerals in the attached figures

[0019] 1. Semiconductor device (subject to inspection)

[0020] 2 Current Sense Amplifier

[0021] 3 Current sensing resistor

[0022] 4 Amplifiers

[0023] 5. Digital-to-analog converter

[0024] 6 Switching Unit

[0025] 7. Analog-to-digital converter (measurement section)

[0026] 8. Controller (Control Unit)

[0027] 9. Power Supply Department

[0028] 10 Inspection device

[0029] 14 Testers

[0030] 18 Computers

[0031] W chip. Detailed Implementation

[0032] Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are used to label the same components, and sometimes repeated descriptions are omitted.

[0033] <Inspection Device>

[0034] use Figure 1 The inspection device 10 of this embodiment will be described. Figure 1 This is an example of a cross-sectional schematic diagram illustrating the structure of the inspection device 10 of this embodiment.

[0035] Inspection apparatus 10 is an apparatus for inspecting the electrical characteristics of each of multiple semiconductor devices (DUTs) formed on a wafer (substrate) W. Furthermore, the substrate having the DUTs is not limited to the wafer W, but includes carriers on which semiconductor devices are disposed, glass substrates, chip units, etc. Inspection apparatus 10 includes: a receiving chamber 12 that receives a chuck 11 for mounting the wafer W; a loader 13 disposed adjacent to the receiving chamber 12; and a tester 14 disposed to cover the receiving chamber 12.

[0036] The housing 12 has a shell shape with an internal cavity. Inside the housing 12, a chuck 11 for mounting the wafer W and a probe card 15 arranged opposite to the chuck 11 are housed. The probe card 15 has: electrode pads arranged corresponding to the electrodes of each semiconductor device of the wafer W; and a plurality of needle-shaped probes (contact terminals) 16 arranged corresponding to the solder bumps.

[0037] The chuck 11 has a fixing mechanism (not shown) for securing the wafer W to the chuck 11. This prevents the wafer W from shifting position relative to the chuck 11. Furthermore, a moving mechanism (not shown) is provided in the receiving chamber 12 for moving the chuck 11 horizontally and vertically. This adjusts the relative position of the probe card 15 and the wafer W, ensuring that the electrode pads and solder bumps corresponding to the electrodes of each semiconductor device contact the probes 16 of the probe card 15.

[0038] Loader 13 removes a wafer W containing a semiconductor device from FOUP (not shown), which serves as a transport container, and places it into chuck 11 inside storage chamber 12. In addition, inspected wafer W is removed from chuck 11 and stored in FOUP.

[0039] The probe card 15 is connected to the tester 14 via the interface 17. When each probe 16 contacts the electrode pad or solder bump that corresponds to the electrode of each semiconductor device on the wafer W, each probe 16 supplies electrical power from the tester 14 to the semiconductor device via the interface 17, or transmits signals from the semiconductor device to the tester 14 via the interface 17.

[0040] The tester 14 includes a test board (not shown) that reproduces a portion of the circuit structure of a motherboard equipped with semiconductor devices. The test board determines the quality of the semiconductor devices based on signals received from them and is connected to a computer 18 for control. In the tester 14, the circuit structures of various motherboards can be reproduced by changing the test board.

[0041] Next, use Figure 2 The circuit structure of the inspection device 10 in this embodiment will be described. Figure 2 This is an example of a circuit diagram showing the circuit structure of the inspection device 10 in this embodiment.

[0042] The inspection apparatus 10 is an inspection device for inspecting the electrical characteristics of multiple semiconductor devices 1. Figure 2 In the example shown, the inspection device 10 will be described as an inspection device for inspecting 16 semiconductor devices 1. Furthermore, in the following description, the 16 semiconductor devices 1 will also be referred to as DUT1, DUT2, ..., DUT16.

[0043] Tester 14 of inspection device 10 (see reference) Figure 1 The device includes a current-sensing amplifier 2, a current-sensing 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. Furthermore, the current-sensing amplifier 2, the current-sensing resistor 3, and the amplifier 4 form a power supply unit 9 that supplies power to the semiconductor device (DUT) 1. Sixteen power supply units 9 are provided corresponding to the semiconductor device 1.

[0044] The computer 18 issues commands to the controller 8, such as an FPGA (Field Programmable Gate Array), to control the tester 14.

[0045] 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 specified output voltage to the semiconductor device 1 based on the input analog signal.

[0046] Furthermore, the output of amplifier 4 is connected to a current sensing resistor 3 for measuring the current supplied from amplifier 4 to semiconductor device 1. When a predetermined output voltage is applied to semiconductor device 1, a potential difference corresponding to the current supplied from amplifier 4 to semiconductor device 1 is generated in current sensing resistor 3. Current sensing amplifier 2 amplifies the potential difference of current sensing resistor 3 and outputs the amplified voltage signal (analog signal) to ADC7 via switching unit 6.

[0047] That is, the power supply unit 9 receives a set voltage signal (digital signal) from the controller 8. Furthermore, based on the input set voltage signal (digital signal), the power supply unit 9 applies a predetermined output voltage to the semiconductor device 1. Additionally, as a signal corresponding to the current supplied to the semiconductor device 1, an amplified voltage signal (analog signal) is output to the ADC 7 via the switching unit 6.

[0048] The switching unit 6, controlled by the controller 8, switches the power supply unit 9 connected to the ADC 7 among a plurality of power supply units 9. In other words, the switching unit 6 switches the semiconductor device 1 whose current is to be measured among a plurality of semiconductor devices 1. The switching unit 6 has a plurality of relay switches that are controlled to open and close by the controller 8. One end of each relay switch is connected to the corresponding power supply unit 9. The other end of each 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 switches.

[0049] The ADC7 receives an amplified voltage signal (analog signal) from the power supply unit 9 (current sense amplifier 2) selected by the switching unit 6. The ADC7 converts the analog signal into a digital signal and outputs it to the controller 8. Furthermore, the controller 8 outputs a digital signal to the computer 18. Thus, the controller 8 measures the current supplied to the semiconductor device 1. In other words, the ADC7, controller 8, and computer 18 constitute a measurement unit for measuring the current supplied to the semiconductor device 1 selected by the switching unit 6.

[0050] In addition, the inspection device 10 inspects multiple (in) Figure 2 In this example, there are 16 semiconductor devices 1. Therefore, the inspection device 10 has multiple (in the example) semiconductor devices 1. Figure 2 In this example, there are 16 power supply units 9. On the other hand, the inspection device 10 has one ADC 7 for each power supply unit 9. Thus, by switching the channel of the switching unit 6, the inspection device 10 can use one ADC 7 to measure the current supplied to the multiple semiconductor devices 1.

[0051] Next, use Figure 3 The method for measuring current is explained. Figure 3 This is an example of a timing diagram illustrating a current measurement method. Here, the inspection device 10 performs n current measurements on a semiconductor device 1 and averages them. This allows for high-precision current measurement. Specifically, the inspection device 10 performs n averaged current measurements on each of 16 semiconductor devices 1 (DUT1 to DUT16). In the following explanation, the time required to perform n current measurements on each of the 16 DUTs will be referred to as the "current measurement time".

[0052] Here, the time from the start of current measurement to the point where the next current measurement is allowed for the same semiconductor device 1 is defined as the interval time t1.

[0053] Furthermore, when switching the channel of switching unit 6, a waiting time is required for switching unit 6, etc. The time from the time the channel of switching unit 6 is switched until the current measurement begins is set as the channel waiting time (CH WAIT)t2.

[0054] In addition, the measurement time of semiconductor device 1 is set as t3.

[0055] In addition, the interval time t1 and the average number of times n are specified by the user, for example, according to the inspection of the semiconductor device 1, and are input into the computer 18. Furthermore, the channel waiting time t2 and the measurement time t3 are preset values ​​in the computer 18, for example, according to the characteristics of the inspection device 10 (e.g., the response time of the switching unit 6, the ADC7, etc.).

[0056] Figure 3 (a) is an example of a timing diagram illustrating a sequential current measurement method. In this sequential current measurement method, current measurements are repeatedly performed n times on a DUT1, the channel of the switching unit 6 is switched, and then current measurements are repeatedly performed n times on DUT2. This process is repeated up to DUT16. That is, in this sequential current measurement method, after a predetermined number of current measurements are performed on a semiconductor device 1, the switching unit 6 is switched to perform a predetermined number of current measurements on other semiconductor devices 1.

[0057] In the sequential current measurement method, firstly, 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. Here, when t1 > t3, the second measurement of DUT1 is performed after an interval time t1. On the other hand, when t1 ≤ t3, the second measurement of DUT1 is performed immediately after the first measurement of DUT1. Hereafter, the measurement of DUT1 is performed until n times.

[0058] Next, the channel of switching unit 6 is switched to measure DUT2. After a channel waiting time t2, the first measurement of DUT2 is performed. Thereafter, the same procedure as with DUT1 is followed, and the measurement of DUT2 is performed until the nth measurement is completed.

[0059] By performing the measurement from DUT1 to DUT16, the inspection device 10 completes the current measurement of DUT1 to DUT16.

[0060] The current measurement time in the sequential method can be calculated using the following equations (1) and (2).

[0061] When t1 > t3, (t1 × n + t2) × 16 ……(1)

[0062] When t1≤t3, (t3×n+t2)×16……(2)

[0063] Figure 3(b) is an example of a timing diagram illustrating the scanning current measurement method. In the scanning current measurement method, the channel of the switching unit 6 is switched to perform a first current measurement on DUT1 to DUT16. Then, the channel of the switching unit 6 is switched again to perform a second current measurement on DUT1 to DUT16. This process is repeated until the number of measurements reaches n. That is, in the scanning current measurement method, the process is repeated a predetermined number of times. This process involves switching the switching unit 6 to perform current measurements on other semiconductor devices 1 after a current measurement of one semiconductor device 1 has been performed.

[0064] In the scanning current measurement method, firstly, 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. Next, the channel of the switching unit 6 is switched to measure DUT2. After a channel waiting time t2, the first measurement of DUT2 is performed. This process is repeated from DUT1 to DUT16, completing the first measurement of DUT1 to DUT16.

[0065] Here, when t1 > (t2 + t3) × 16, the second measurement of DUT1 to DUT16 is performed after an interval of t1. On the other hand, when t1 ≤ (t2 + t3) × 16, the second measurement of DUT1 to DUT16 is performed immediately after the first measurement. The measurements of DUT1 to DUT16 are then performed until the total number of measurements is n.

[0066] The current measurement time in the scanning mode (n checks for each of the 16 DUTs) can be calculated using the following equations (3) and (4).

[0067] When t1 > (t2 + t3) × 16, t1 × n ……(3)

[0068] When t1≤(t2+t3)×16, then ((t2+t3)×16)×n……(4)

[0069] Thus, the current measurement time for sequential and scanning modes is determined by four parameters (set values): interval time t1, channel waiting time t2, measurement time t3, and average number of measurements n. Figure 4 This is an example of a graph showing the relationship between the average number of measurements (n) and the current measurement time. The horizontal axis represents the average number of measurements (n), and the vertical axis represents the current measurement time. Furthermore, the solid line represents the current measurement time in the scanning mode, and the dashed line represents the current measurement time in the sequential mode. Figure 4In the example, when the average number of times n is less than n1, the current measurement time in the scanning method is shorter than the current measurement time in the sequential method. Furthermore, when the average number of times n is greater than or equal to n1, the current measurement time in the sequential method is shorter than the current measurement time in the scanning method.

[0070] Based on the set parameters (interval time t1, channel waiting time t2, measurement time t3, average number of times n), the computer 18 selects the measurement method with the shorter measurement time between the sequential method and the scanning method, and performs the inspection using the selected measurement method.

[0071] Figure 5 This is a flowchart illustrating an example of the control of computer 18.

[0072] In step S101, the computer 18 receives parameter (set values) input. For example, based on the inspection of the semiconductor device 1, the user inputs the interval time t1 and the average number of times n into the computer 18. In addition, the channel waiting time t2 and the measurement time t3 can be pre-input into the computer 18 or input by the user.

[0073] In step S102, the computer 18 calculates the current measurement time in a sequential manner based on the parameters and equations (1) and (2).

[0074] In step S103, the computer 18 calculates the current measurement time of the scanning mode based on the parameters and equations (3) and (4).

[0075] In step S104, the computer 18 selects a measurement method based on the calculated current measurement time.

[0076] In step S105, the computer 18 performs current measurement of the semiconductor device 1 (DUT1 to DUT16) using the selected measurement method.

[0077] According to the inspection apparatus 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. That is, according to the inspection apparatus 10 of this embodiment, the sequential mode and the scanning mode are switched according to the inspection conditions, thereby shortening the current measurement time.

[0078] The inspection device 10 has been described above, but the present invention is not limited to the above embodiments, etc. Various modifications and improvements can be made within the scope of the spirit of the present invention as described in the claims.

Claims

1. An inspection device, characterized in that, include: The power supply unit applies a specified output voltage to multiple inspected objects; The switching unit switches the inspected object whose current is to be measured; A measuring unit that measures the current of the object under inspection selected by the switching unit; and The control unit that controls the switching unit The control unit switches between sequential mode and scanning mode based on the set values ​​for current measurement. The sequential method involves performing a predetermined number of current measurements on one inspected object, then switching the switching unit to perform a predetermined number of current measurements on other inspected objects. The scanning method is a process of repeatedly performing the process a predetermined number of times. This process involves switching the switching unit to measure the current of other objects after measuring the current of one object being inspected.

2. The inspection device as described in claim 1, characterized in that: The control unit calculates the current measurement time in the sequential mode and the current measurement time in the scanning mode based on the set value, and switches between the sequential mode and the scanning mode based on the calculated current measurement time.

3. The inspection device as described in claim 1 or 2, characterized in that: The set value includes: The interval time is the time from the start of a current measurement to the point where the next current measurement is permitted for the same object under inspection; and Average number of times, which is the number of times the current measurement is repeatedly performed on a subject under inspection.

4. The inspection device as described in claim 3, characterized in that: The set value includes: The measurement time of the subject being examined; and The waiting time from the start of the switch to the start of current measurement.

5. The inspection device as described in any one of claims 1 to 4, characterized in that: The power supply unit is provided in multiple ways corresponding to the multiple objects being inspected.

6. An inspection method for an inspection device, wherein the inspection device applies a predetermined output voltage to a plurality of objects to be inspected and measures the current of a selected object to be inspected, the inspection method being characterized in that it includes: Based on the set values ​​for current measurement, the steps are as follows: calculating the current measurement time in the sequential mode and the current measurement time in the scanning mode. The sequential mode is a method of performing a predetermined number of current measurements on one inspected object and then performing a predetermined number of current measurements on other inspected objects. The scanning mode is a method of repeatedly performing the process a predetermined number of times, which is a process of performing current measurements on one inspected object and then performing current measurements on other inspected objects. The step of selecting the sequential method or the scanning method based on the calculated current measurement time; and The step of measuring the current of the object under inspection in the selected manner.

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