JP2005106500A - Method and device for inspecting electric characteristic of electric component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely confirm formation of electromigration in trouble investigation in a semiconductor maker and a semiconductor production department, by stopping inspection under the condition where the electromigration is formed. <P>SOLUTION: When connecting a resistor R and an electric power source E in series to measuring points T1, T2 to impress a voltage to the measuring points, phenomena of bringing a measured voltage by a voltmeter VM into 0V or into a power source voltage (5V) are continuously and repeatedly appeared in the case of generating the electromigration. A value of the resistor R is switched therein when the measured voltage becomes a prescribed value or less, so as to maintain the electromigration, and the impression of the voltage from the power source E is stopped under this condition to finish the inspection. The inspection is stopped under the condition where the electromigration is formed between the measuring points to be fed back to the trouble investigation in the semiconductor maker and the semiconductor production department. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inspection method and apparatus for inspecting electrical characteristics between lead terminals of an electrical component such as a semiconductor device. More specifically, the present invention examines whether or not electromigration occurs between the lead terminals, and performs electromigration. The present invention relates to a method and an apparatus for inspecting electrical characteristics between lead terminals of an electrical component that is kept in a state when the above occurs.

It is known that electromigration causes phenomena such as deterioration of wiring and connection portions, disconnection of wiring, or deterioration of insulation between lead terminals, resulting in a short circuit state.
In particular, with the improvement in the degree of integration of semiconductor devices, the above-mentioned electromigration problem has come to be regarded as important in ensuring the reliability of semiconductor devices.
For this reason, an electromigration test is performed at the stage of accepting and shipping a semiconductor device, and a semiconductor device in which electromigration occurs is picked up and fed back to a semiconductor manufacturer or a semiconductor manufacturing department to improve quality.

Various methods for evaluating electromigration have been proposed. For example, in Patent Document 1, a variable resistance is connected in series to a metal wiring sample, and a voltmeter is connected in parallel to the metal wiring sample. A semiconductor measurement device that evaluates electromigration by measuring the voltage between metal wiring samples and decreasing the resistance value and causing a constant current to flow through the metal wiring as the resistance value of the metal wiring sample increases is proposed. Has been.
Japanese Utility Model Publication No. 6-70237

As described above, due to electromigration, the insulation state between the lead terminals of the semiconductor device may be deteriorated or short-circuited. This is considered to be caused by organic phosphorus in a package of a semiconductor device or the like.
In order to inspect the occurrence of the electromigration, at present, as shown in FIG. 8, a load resistance (for example, 50 kΩ) R and a power source E (for example, 5 V) are connected in series between the lead terminals T1 and T2, and the lead terminal A voltmeter VM is connected in parallel between them, and the voltage between the lead terminals is measured by the voltmeter VM to detect a decrease in the voltage between the lead terminals.
By the way, when the voltage between the lead terminals T1 and T2 is observed with the voltmeter VM as described above, when electromigration occurs, the measured voltage becomes 0V or the power supply voltage (5V). It was found that the phenomenon occurred continuously and repeatedly.
When the measurement voltage is 0 V, the resistance value between the lead terminals T1 and T2 is 0 (Ω) (referred to as state 1), and electromigration is completely formed. When the measurement voltage is 5 V, for example, the resistance value between the lead terminals T1 and T2 is ∞ (Ω) (referred to as state 2), and electromigration is not completely formed. is there. State 1 and state 2 repeatedly appeared at intervals of several tens of ms.

As described above, when electromigration occurs, the semiconductor device in which electromigration has occurred is fed back to a semiconductor manufacturer or semiconductor manufacturing department to improve quality. However, if the state where electromigration is formed and the state where it is not formed repeatedly appear alternately as described above, even if it is found that electromigration occurs at the stage of inspection, it is fed back to the semiconductor manufacturer and the semiconductor manufacturing department. When investigating a fault, the lead terminals may not necessarily be short-circuited, and it may be impossible to confirm that electromigration has been formed at the stage of the fault investigation.
The present invention has been made in consideration of the above circumstances, and by stopping the inspection by stopping the supply of voltage between the lead terminals while maintaining the formation of electromigration, the semiconductor manufacturer and the semiconductor It is to make sure that the electromigration is formed in the trouble investigation in the manufacturing department.

In order to solve the above problems, in the present invention, as shown in FIG. 1A, a resistor R and a power source E are connected in series with measurement points T1 and T2, and a voltmeter is connected in parallel with measurement points T1 and T2. In the measurement circuit to which the VM is connected, the value of the resistor R can be switched. When the current flows between the measurement points T1 and T2 due to electromigration and the voltage between the measurement points T1 and T2 decreases, the resistance value of the resistor is increased and the power supply is maintained in a state where electromigration is maintained. Then, the voltage application is stopped and the inspection is finished.
Electromigration grows from the + side terminal as shown schematically in FIG. 1A and reaches the − side terminal, and the measurement points are short-circuited (state 1 described above), but the measurement points are short-circuited. If the current flowing between the measurement points increases and the short-circuit state due to electromigration is eliminated, the phenomenon that the measurement points are again in an insulating state (state 2 described above) is repeated. It is thought that it appears alternately repeatedly.
Therefore, as described above, the state of electromigration can be maintained by switching the value of the resistance R according to the voltage between the measurement points.
FIG. 1B is a diagram showing changes in voltage at the measurement points T1 and T2 monitored by the voltmeter VM, and the horizontal axis is time t. The horizontal axis shows the internal resistance between the measurement points T1 and T2 with time t.
As shown in B of the figure, the internal resistance between the measurement points T1 and T2 rapidly decreases when it exceeds a certain value (50 (kΩ) in the figure). At this time, the value of the resistance R is set to 50. By increasing (kΩ) → 70 (kΩ) → 90 (kΩ), the decrease rate of the internal resistance between the measurement points T1 and T2 is reduced as shown in FIG. Can be maintained.
As described above, since the state 1 and the state 2 repeatedly appear at intervals of several tens of ms, it is difficult to determine the timing to end the inspection even if the inspection is finished in a state where the electromigration is formed, If data is acquired at intervals of several tens of ms or less, the amount of information becomes enormous. However, by increasing the value of the resistance R as described above, the electromigration formation state can be maintained for a certain period of time. The timing at which the test is terminated by stopping the application of the voltage between the measurement points in a state where is formed can be determined relatively easily. Further, by maintaining the state in which electromigration is formed, data acquisition becomes relatively easy.
Further, a series circuit of a power source and a resistor is connected between a plurality of lead terminals of the semiconductor device, and voltage measuring means for measuring voltages between the plurality of lead terminals is provided, and each of the voltage measured by the voltage measuring means is measured. The measurement voltage is compared with a preset determination value, and when at least one of the measurement voltages is smaller than the determination value, the determination value is changed. You may make it output the voltage between the measurement points and the determination value which became smaller than the determination value.
As a result, it is possible to observe the transition of the voltage between the lead terminals where the voltage drop is the greatest among the lead terminals of the semiconductor device, and it is output compared to the case where the measurement voltage between all measurement points is output. There are few data, and data can be easily organized and analyzed.

In the present invention, when the voltage between the measurement points is reduced by electromigration as described above, the resistance value of the resistor connected in series between the measurement points is increased, and the power supply is maintained in the state where electromigration is maintained. Since the application of the voltage is stopped and the inspection is finished, the inspection can be finished with the electromigration formed, and the electromigration is formed in the failure investigation in the semiconductor manufacturer or the semiconductor manufacturing department. It can be confirmed with certainty.
For this reason, there is a problem in that, even when electromigration occurs in the acceptance and shipment inspection of a semiconductor device, the electromigration cannot be confirmed when performing a fault investigation by feeding back to the semiconductor manufacturer or the semiconductor manufacturing department. Therefore, it is possible to reliably investigate the cause of the occurrence of electromigration.
Further, each measurement voltage measured by the voltage measuring means is compared with a predetermined determination value, and when at least one of the measurement voltages becomes smaller than the determination value, the determination value Between the lead terminals of the semiconductor device with the largest voltage drop by outputting the voltage between the measurement points where the measurement voltage is smaller than the above judgment value and the judgment value. The transition of the voltage can be observed, and since the output data is small, the data can be easily organized and analyzed.

FIG. 2 is a diagram illustrating a configuration example of the measurement circuit according to the embodiment of the present invention. In the figure, D1 to Dm are semiconductor devices to be inspected, and voltmeters VM11 to VM1n and VMm1 to VMmn are connected in parallel to the lead terminals 11 to 1n and m1 to mn of the semiconductor devices D1 to Dm, respectively. The switches SW11 to SW1n, the switches SWm1 to SWmn, resistors R1 to R3 that are switched and connected by these switches, and the power source E are connected in series to the lead terminals 11 to 1n and m1 to mn of the semiconductor devices D1 to Dm. Is connected. The resistance value of the resistor R1 is, for example, 50 kΩ, 70 kΩ, and 90 kΩ, and the voltage of the power source E is, for example, 5V.
As described above, the switches SW11 to SW1n and the switches SWm1 to SWmn are switched according to the measurement voltages measured by the voltmeters VM11 to VM1n and VMm1 to VMmn, and are switched to the lead terminals 11 to 1n and m1 to mn. The resistors connected in series are resistance R1 → resistance R2 → resistance R3.

FIG. 3 is a diagram illustrating a configuration example of an inspection control system that controls switching of the switches SW11 to SW1n and the switches SWm1 to SWmn and records an inspection result.
The measured voltages V11 to V1n and Vm1 to Vmn between the lead terminals of the semiconductor devices D1 to Dm measured by the voltmeters VM11 to VM1n and VMm1 to VMmn are converted into digital signals by the AD converter 20, The data is taken into the processing device 30 at a sampling period.
As will be described later, the processing device 30 compares the measurement voltages V11 to V1n and Vm1 to Vmn of each lead terminal with preset determination values, and the measurement voltages V11 to V1n and Vm1 of each semiconductor device are determined based on the determination values. When the voltage of at least one lead terminal in Vmn becomes small, the measured voltage, the judgment value, and the time elapsed since the start of inspection (called elapsed time) are output to the file 50 for recording the inspection results. At the same time, the determination value is set to a value smaller than the measurement voltage by a predetermined value (for example, 0.1 V).
Each time a predetermined time (for example, 60 seconds) elapses, the determination value is returned to the initial value (for example, 4.9 V), and then the determination value is set to the immediately preceding value.
When the above processing is repeated and the measured voltage becomes smaller than a first set value (for example, 3.0 V), switching signals of the switches SW11 to SW1n and switches SWm1 to SWmn are output via the output interface 40, and the measured voltage is When the value of the resistor connected in series to the lead terminal that has become smaller than the first set value is increased (for example, 50 kΩ to 70 kΩ), and when the value is smaller than the second set value (for example, 2.5 V), the switch SW11 to SW1n and switches SWm1 to SWmn are switched to further increase the value of the resistor connected in series to the lead terminal whose measured voltage is smaller than the second set value (for example, 70 kΩ to 90 kΩ).
When the measured voltage becomes smaller than a third set value (for example, 2.0 V), among the switch switches SW11 to SW1n and switches SWm1 to SWmn, the switch whose measured voltage is smaller than the third set value is selected. Switch to off state. The elapsed time when the measured voltage becomes smaller than the first to third set values, the measured voltage at that time, and the determination value are output to the file 50.

FIG. 4 is a functional block diagram showing the processing contents of the processing device 30, and FIG. 5 is a flowchart showing the processing contents in the processing device 30. The processing in the processing device 30 will be described with reference to FIGS. Although FIG. 4 shows one semiconductor device D1, when there are a plurality of semiconductor devices to be inspected, the same processing is performed for other semiconductor devices.
First, the first timer 36 and the second timer 37 shown in FIG. 4 are started (step S1 in FIG. 5). The first timer 36 is a timer that starts at the start of the inspection and times up when the inspection end time comes (for example, the time is up 48 hours after the start of the inspection). The second timer 37 is, for example, 60 It is a timer that times up every second.
Next, the voltages V11 to V1n between the lead terminals of the semiconductor element D1 are output together with the elapsed time (step S2 in FIG. 5). That is, the measured value / judgment value recording means 38 shown in FIG. 4 outputs the voltages V11 to V1n and the time to the file 50 that stores the inspection result.

The first comparison means 31 shown in FIG. 4 compares the voltages V11 to V1n between the lead terminals of the semiconductor element with a determination value (initial value is, for example, 4.9 V), and the P / F determination means 32 compares the voltage V11. When any one voltage of ~ V1n is smaller than the determination value, it is determined as FAIL, and when any of the voltages V11 to V1n is higher than the determination value, it is determined as PASS (step S3 in FIG. 5). If there are a plurality of semiconductor devices to be inspected, the determination of FAIL and PASS is performed for each semiconductor device.
When the P / F determination unit 32 determines FAIL, the measurement value / determination value recording unit 38 outputs the current measurement voltage, determination value, and time of the lead terminal determined to be FAIL to the file 50 (FIG. 5). 5 step S4).
Further, the determination value changing means 33 changes the determination value 31a and sets the measured voltage −0.1 V at that time as a new determination value (step S5 in FIG. 5). If the P / F determination means 32 determines PASS, the process goes to step S6 in FIG. 6 without doing anything.
In step S6 of FIG. 5, it is determined whether 60 seconds have elapsed since the timer 37 was started. When 60 seconds have elapsed, the determination value changing unit 33 returns the determination value to the initial value (4.9 V), and similarly to the above, the F / P determination unit 32 determines whether it is FAIL or PASS (step S13 in FIG. 5). , S14). If it is FAIL, the measured value, determination value and time of the lead terminal determined to be FAIL are output (step S15), and the determination value changing means 33 is a value before returning the determination value to the initial value. (Step S16). The timer 37 restarts counting (step S17).

The second comparison unit 34 shown in FIG. 4 has first and second set values (for example, 3.0 V and 2.5 V) in which voltages V11 to V1n between the lead terminals and a voltage for switching the resistance value are set. Then, the voltage for turning off the power is compared with a set power-off setting value (for example, 2.0 V) (steps S7, S8, and S9 in FIG. 5).
When the voltages V11 to V1n are smaller than the first resistance switching set value (3.0V), the switch operating means 35 has the voltage of the switches SW11 to SW1n smaller than the set value (3.0V). The switch connected to the lead terminal is switched to set the resistance connected to the lead terminal to 70 kΩ.
Further, when the voltages V11 to V1n become smaller than the second resistance switching set value (2.5V), the switch operating means 35 causes the voltage of the switches SW11 to SW1n to become smaller than the set value (2.5V). The switch connected to the lead terminal is switched to set the value of the resistor connected to the lead terminal to 90 kΩ.
Further, when the voltages V11 to V1n become smaller than the power-off setting value (2.0V), the switch operating means 35 is a lead terminal whose voltage is smaller than the setting value (2.0V) among the switches SW11 to SW1n. The switch connected to is turned off, and the application of voltage to the lead terminal is stopped.
The above operation is repeated until the first timer 36 expires. When the timer 36 expires, all the switches SW11 to SW1n connected to the lead terminal are turned off, and the inspection is terminated.

In this embodiment, as described above, when the measured voltage between at least one lead terminal among the voltages V11 to V1n between the lead terminals of the semiconductor device becomes smaller than the determination value, the determination value is set to a predetermined value (for example, 0.1V), and the measured voltage, judgment value, and time at that time are output, so the transition of the voltage between the lead terminals with the greatest voltage drop is observed among the lead terminals of the semiconductor device. can do. In particular, the above operation is repeated while decreasing the determination value by a predetermined value, and the measurement voltage, the determination value, and the time are output. Therefore, a fixed amount regardless of the magnitude of the voltage decrease rate between the lead terminals. Data can be obtained.
For example, when the voltage between the lead terminals is acquired and recorded at regular time intervals, if a sufficient amount of data is obtained even when the voltage drop rate between the lead terminals is large, the frequency of recording the voltage is increased. However, as described above, the amount of data to be recorded can be reduced by outputting the measurement voltage, the determination value, and the time while decreasing the determination value by a predetermined value as described above. It can be reduced, and the work for organizing and verifying the data after the fact becomes easy. Further, if any one of the lead terminal voltages V11 to V1n of the semiconductor device is smaller than the determination value, it is determined as FAIL, and the measurement voltage, the determination value, and the time are recorded. Focusing on the lowest lead terminal, the voltage transition of the lead terminal can be recorded.
Further, since the determination value is returned to the initial value every time set in the second timer 37 (for example, 60 seconds), the voltage of the lead terminal other than the lead terminal having the lowest measured voltage is observed and recorded. can do.

FIG. 6 is a diagram illustrating the time transition of the measurement voltage and the determination value (measurement data) between the lead terminals of the semiconductor device obtained by the inspection apparatus of this example. The circles in the figure indicate the time point when the measurement data is output, and the measurement data is not output with a cross.
As shown in the figure, after the measurement voltage is output at the start of measurement and the determination value at that time is output, the measurement voltage is taken into the processing device at a predetermined sampling period, and the FAIL and PASS determination is performed as described above. Each time it becomes smaller than the judgment value, measurement data is output, and the judgment value is changed to a voltage lower by -0.1V than the measurement voltage at that time. Further, the judgment value is returned to 4.9 V every 60 seconds, and when the measured voltage is smaller than 4.9 V, the measured voltage of the lead terminal is output.
FIG. 7 is a diagram showing a temporal transition of measurement data output when a plurality of semiconductor devices are inspected.
As shown in the figure, at the start of measurement, the measurement voltage between all the lead terminals is output, and thereafter, the measurement data between the lead terminals is output every time the FAIL determination is made for each semiconductor device. When the voltage between the lead terminals becomes smaller than 2.0 V, the application of the voltage to the lead terminals is stopped. If the voltage between the lead terminals does not become smaller than 2.0 V, the measurement data is output repeatedly, and for example, when 48 hours have elapsed, the inspection is terminated.

It is a figure explaining the outline | summary of this invention. It is a figure which shows the structural example of the measurement circuit of the Example of this invention. It is a figure which shows the structural example of the test | inspection control system of the Example of this invention. It is a functional block diagram which shows the function structure of the processing apparatus shown in FIG. It is a figure which shows the processing flow in the processing apparatus shown in FIG. It is a figure which shows the time transition of the measurement voltage between the lead terminals of the semiconductor device obtained by the test | inspection apparatus of a present Example, and a judgment value. It is a figure which shows the time transition of the measurement data output when a several semiconductor device is test | inspected. It is a figure which shows a prior art example.

Explanation of symbols

D1 to Dm Semiconductor device 11 to 1n, m1 to mn Lead terminal VM11 to VM1n Voltmeter VMm1 to VMmn Voltmeter SW11 to SW1n Switch SWm1 to SWmn Switch 20 AD converter 30 Processing device 50 File 40 Output interface

Claims (3)

A method for inspecting the electrical characteristics of an electrical component for inspecting the occurrence of electromigration occurring between measurement points of the electrical component,
By connecting a series circuit of a power source and a resistor between the measurement points, and measuring the voltage between the measurement points, the presence or absence of electromigration is inspected,
When the internal resistance between the measurement points becomes smaller due to electromigration, the resistance value of the resistor is increased and the application of voltage from the power supply is stopped in the state where electromigration occurs, and the state where electromigration occurs is maintained. A method for inspecting electrical characteristics of an electrical component, characterized in that: An inspection device for inspecting the occurrence of electromigration,
A series circuit of a power source and a resistor connected between the measurement points of the electrical component, a voltage measurement means for measuring a voltage between the measurement points, and
Means for increasing the resistance value of the resistor when the voltage measured by the voltage measuring means becomes smaller than a preset first value due to the occurrence of electromigration;
Means for stopping the application of the voltage between the measurement points and maintaining the state in which electromigration has occurred when the measured voltage becomes smaller than a preset second value. A device for inspecting the electrical characteristics of a featured electrical component. A semiconductor device inspection device for inspecting the occurrence of electromigration,
A series circuit of a power source and a resistor connected between a plurality of lead terminals of the semiconductor device;
Voltage measuring means for measuring voltages between the plurality of lead terminals,
A determination means for comparing each measured voltage measured by the voltage measuring means with a predetermined determination value, and generating an output when the measured voltage becomes smaller than the determination value;
Determination value changing means for changing the determination value when at least one of the measurement voltages becomes smaller than the determination value;
Means for increasing the resistance value of the resistor connected in series to the lead terminal when the measured voltage becomes lower than a preset first value due to the occurrence of electromigration;
Means for stopping the application of the voltage to the lead terminal and holding the state in which electromigration has occurred when the measured voltage becomes smaller than a preset second value;
A semiconductor comprising recording means for recording a judgment value when the judgment means generates an output, and a voltage between the lead terminals measured by the voltage measurement means when the judgment means generates an output. Equipment inspection device.

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