JP2002119043A - Semiconductor device and its inspecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device and its inspecting method, by which residual life of the device can be evaluated precisely. SOLUTION: The control unit 142 of an inverter 140 measures the thermal resistance of an IGBT element 141. A center computer 200 evaluates the residual life on the basis of the measured thermal resistance, and necessity of an exchange of the semiconductor device is communicated on the basis of this evaluation result of the residual life.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and an inspection method thereof, and more particularly to a semiconductor device suitable for evaluating a remaining life and an inspection method thereof.

[0002]

2. Description of the Related Art As a conventional semiconductor device and its inspection method, for example, as described in Japanese Patent Application Laid-Open No. 5-56629, a semiconductor device such as a power converter is disclosed.
There is known an apparatus that sets an expected life, compares the set expected life with actual operation results, and outputs maintenance and inspection information when the expected life is reached.

[0003]

However, since the degree of fatigue deterioration of the semiconductor device varies, the conventional semiconductor device and the inspection method thereof show the degree of fatigue deterioration of the target semiconductor device. However, there is a problem that the remaining life cannot be accurately evaluated because it is not possible to grasp the remaining life.

An object of the present invention is to provide a semiconductor device capable of accurately evaluating the remaining life and a method of inspecting the semiconductor device.

[0005]

Means for Solving the Problems (1) In order to achieve the above object, the present invention provides a semiconductor device having a semiconductor element, which has a measuring section for measuring the thermal resistance of the semiconductor element. With this configuration, the remaining life can be accurately evaluated.

(2) In the above (1), preferably,
The semiconductor device is an inverter that controls a motor, has a plurality of semiconductor elements, and the measurement unit turns on the first semiconductor element and turns off the first semiconductor element when other semiconductor elements are turned off. Measuring a first voltage drop of the semiconductor device,
Further, after turning on / off the second semiconductor element connected in series via the first semiconductor element and the motor, the second semiconductor element of the first semiconductor element when the second semiconductor element is turned off. The voltage drop is measured, and the thermal resistance of the first semiconductor element is measured based on the first voltage drop and the second voltage drop.

(3) In order to achieve the above object, the present invention provides a semiconductor device inspection method for evaluating a remaining life of a semiconductor device having a semiconductor device, the method comprising: The remaining life is evaluated, and the necessity of replacement of the semiconductor device is notified based on the evaluation result of the remaining life. By such a method,
The remaining life can be accurately evaluated.

(4) In the above (3), preferably,
The rate of increase in thermal resistance is determined based on the measured thermal resistance of the semiconductor element, and the life expectancy of the semiconductor device is determined based on the rate of increase in thermal resistance to evaluate the remaining life. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor device according to an embodiment of the present invention and a method for inspecting the semiconductor device will be described below with reference to FIGS. First, a system configuration of an inspection system for implementing the semiconductor device inspection method according to the present embodiment will be described with reference to FIG. The inspection system according to the present embodiment will be described as an example of a system that controls a motor of a hybrid electric vehicle using a semiconductor device. FIG. 1 is a system configuration diagram of an inspection system for implementing a semiconductor device inspection method according to an embodiment of the present invention.

The inspection system according to the present embodiment includes a hybrid vehicle 100 and a computer 200. The vehicle 100 includes an internal combustion engine 1 as a power source.
10 and a motor 120. Motor 120
Is arranged between the internal combustion engine 110 and the wheels 130. The motor 120 starts the vehicle 100, acts as a starter for the internal combustion engine 110, assists running of the internal combustion engine 110, and also acts as a generator. The inverter 140, which is a semiconductor device, sends a current from the battery 150 to the motor 120 to generate a driving force on the motor 120, and conversely, makes the motor 120 work as a generator, and
Charge.

The inverter 140 has a control unit therein, as described later. The control unit receives a detection result of the depression amount of the accelerator 160 and the rotation speed of the wheel 130 during operation,
Based on this, a control signal is output to control not only the rotation of the motor 120 but also the rotation of the internal combustion engine 110 and perform an appropriate operation, thereby reducing fuel consumption and exhaust gas.

A communication device 170 is connected to the inverter 140. The communication device 170 wirelessly exchanges data and instructions with the computer 200.
When receiving the command from the computer 200, the communication device 170 transmits the command to the inverter 140. In addition, based on a command from the computer 200, the inverter 140 internally measures the thermal resistance of the semiconductor device as described later with reference to FIG. The measurement result of the thermal resistance is transmitted to the computer 20 via the communication device 170.
0 is transmitted. The computer 200 evaluates the remaining life of the semiconductor device based on the thermal resistance detected by the inverter 140, as described later with reference to FIG.

Next, the internal structure of the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG. 2 is a sectional view showing the internal configuration of the semiconductor device according to the embodiment of the present invention.

The inverter 140 is a semiconductor element I
GBT (Insulated Bipolar Transistor) element 141a,
141b and 141c and a control unit 142 are provided. The control unit 142 is an IGBT
The conduction of the element 141 is controlled, and the thermal resistance of the IGBT element 141 is measured as described later. The IGBT element 141 and the control unit 142
Built inside.

Next, the internal configuration of the IGBT element 141, which is a semiconductor element incorporated in the semiconductor device according to the present embodiment, will be explained with reference to FIG. FIG. 3 is a cross-sectional view showing an internal configuration of an IGBT element which is a semiconductor element incorporated in the semiconductor device according to the embodiment of the present invention.

The IGBT element 141 has a base 141J
, An insulating plate 141K, an IGBT chip 141L, and a case 141M. IGBT chip 141L
Are joined to the insulating plate 141K by the solder 141N. The insulating plate 141K is joined to the base 141J by the solder 141P. Case 141M
Is attached to the base 141J and covers and protects the IGBT chip 141L.

Next, the fatigue crack generated in the IGBT element incorporated in the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG. 4 is an explanatory diagram of a fatigue crack generated in an IGBT element incorporated in a semiconductor device according to one embodiment of the present invention.

During operation of the vehicle, a current flows through the IGBT element 141, generating heat and increasing the temperature. As a result, a thermal stress is generated at the joint of the solder 141P that joins the insulating plate 141K and the base 141J in the IGBT element 141. By repeating this thermal stress, the solder 141P
A fatigue crack 141P 'is generated and grows at the joint of. In the case of a hybrid vehicle, in addition to the self-heating of the IGBT element, it is affected by the heat of the internal combustion engine.
The BT element 141 is used in a very severe condition.

The fatigue crack growth behavior was determined by the IGBT element 141.
Have a certain range of variation inherently. Therefore, the thermal resistance increasing behavior also has a certain range of variation. Conventionally, since the service life cannot be evaluated accurately, in order to prevent equipment failure, the guaranteed service life is set to the minimum service life of this variation, and when this service life is reached, use is stopped and the equipment is discarded. ing. However, in practice, depending on the sample, even if it is used only for the guaranteed life, it is often enough to use it, and these devices are discarded even though they can be used, thus wasting resources.

Next, the circuit configuration of the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG. 5 is a circuit diagram of a semiconductor device according to an embodiment of the present invention. In addition,
1 and 2 denote the same parts.

The main circuit configuration of the inverter 140 is as follows.
, 141f, a control unit 142, and a current sensor 144. The six IGBT elements 141a,.
A bridge circuit is configured. IGBT element 141a and IGBT element 141b correspond to an upper arm and a lower arm for controlling the U-phase current of motor 120. IGBT
The element 141c and the IGBT element 141d
Corresponding to the upper arm and the lower arm for controlling the V-phase current. IGBT element 141e and IGBT element 141d
Corresponds to an upper arm and a lower arm for controlling the W-phase current of the motor 120.

The control unit 142 has six I
By controlling the on / off of the GBT element 141, the current supplied from the battery 150 to the motor 120 is controlled, and the motor 120 is rotated. ON / OFF of a large current by the IGBT element 141 is controlled by controlling a small current gate current supplied to the gate terminal of the IGBT 141. The wiring for flowing the gate current is omitted from the drawing to avoid complication of the drawing, but is wired from the control unit 142 to the gate terminal of each of the IGBT elements 141a,. Control unit 14
2, IGBT elements 141a,.
If is controlled.

The current sensor 144 detects a current flowing through the motor 120 in a U-phase. The current detected by the current sensor 144 is taken into the control unit 142.

Although not shown in the drawings, the control unit 142 supplies the IGBT elements 141a,.
A connection for measuring a voltage drop at both ends of 141 f (between the source terminal and the drain terminal) is provided. The control unit 142 includes the IGBT elements 141a,.
Each IGBT element 141 is obtained by using the voltage drop of 1f.
a,..., 141f can be determined. How to determine the thermal resistance will be described later with reference to FIGS.

Next, the operation of the control unit 142 of the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG. 6 is a flowchart illustrating a processing operation of the control unit 142 of the semiconductor device according to the embodiment of the present invention.

In step s100, control unit 142 receives an inspection request signal from center computer 200 via communication device 170.

When receiving the inspection request signal, step s1
At 10, the control unit 142 determines whether or not the vehicle is stopped, and then, when the vehicle is stopped, enters an inspection mode and measures the thermal resistance. Details of the method of measuring the thermal resistance will be described later with reference to FIG. In the inspection mode, the clutch between the motor 120 and the wheel 130 is disengaged.

Next, in step s120, the control unit 142 transmits the thermal resistance measurement result to the center computer 200 via the communication device 170.

Next, the life of the semiconductor device according to the present embodiment will be explained with reference to FIGS. FIG.
8 is an explanatory diagram of the life of the semiconductor device according to the embodiment of the present invention.

As described with reference to FIG. 4, during the operation of the vehicle, due to the repetition of thermal stress applied to the IGBT element 141, the fatigue crack 141
P 'occurs and grows. Due to the generation of the fatigue crack 141P ′, the joining dimension of the solder 141P joining the insulating plate 141K and the base 141J decreases from the initial value L0 to the remaining joining dimension L.

Here, FIG. 7 shows a usage period Y of the semiconductor device.
And the relationship between the remaining joint dimension L and the remaining joint dimension L. At the beginning of the use period Y, the remaining joint dimension L is an initial value L0,
Keep it for a while. However, for example, the use period Y0
, It was found that when fatigue cracks occur, the remaining joint dimension L decreases with the passage of time.

Due to the decrease in the joint size L, the heat initially flowing as shown by the arrow Q1 in FIG. 3 is reduced and flows as shown by the arrow Q2 in FIG. To increase.

Here, FIG. 8 shows the rate of increase of thermal resistance Δr,
The relationship of the use period Y is shown. Increase rate of thermal resistance Δr
Is 0 until the use period Y0 at which fatigue cracks occur. After the use period Y0, the increase rate Δr of the thermal resistance increases at a substantially constant rate. When the rate of increase Δr in thermal resistance reaches a certain limit value Δrc (use period Yc), the life of the semiconductor device is reached. Therefore, in the present embodiment, the life of the semiconductor device is evaluated by measuring the thermal resistance and further obtaining the rate of increase in the thermal resistance.

Next, the details of the process of measuring the thermal resistance in the control unit 142 of the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG. 9 is a flowchart showing a measurement processing operation of the thermal resistance in the control unit of the semiconductor device according to the embodiment of the present invention. Steps s112 to s118 show the details of step s110 in FIG. In the following example, a method of measuring the thermal resistance of the IGBT element 141a in FIG. 5 will be described, but other IGBT elements 141b,.
41f can be measured similarly.

In step s112, the control unit 142 turns on the IGBT element 141a,
The other IGBT elements 141b,..., 141f are turned off.

Next, in step s114, the control unit 142 turns on the IGBT element 141d. As a result, the current flows from the battery 150 to the IG
The battery 150 passes through the BT element 141a, the current sensor 22, the motor 120, and further passes through the IGBT element 141d.
Flowing back to. So, control unit 1
Reference numeral 42 detects a voltage drop Va of the IGBT element 141a when the IGBT element 141d is turned on for a short time.

Next, in step s116, immediately after the detection of the voltage drop Va, the control unit 142 repeats turning on and off the IGBT element 141d at a high frequency for a certain period. Here, the effective current value of the element 1 is controlled by controlling the ratio between the ON time and the OFF time. Immediately after this, the IGBT element 141d is turned on for a short time, and the voltage drop V of the IGBT element 141a at this time is turned on.
b is detected.

Next, in step s118, the control unit 142 sets the voltage difference (Vb
-Va) is converted to a temperature rise and divided by the calorific value to determine the thermal resistance. Here, the calorific value is obtained by multiplying the voltage drop ((Vb−Va) / 2) by the effective current value. The conversion of the voltage difference into a temperature rise is performed in advance by taking into account the relationship between the voltage drop and the temperature. Control unit 14
2 is another IGBT element 141 by a similar method.
, 141f are also measured.

According to the measurement method described above, the target IGB
The amount of heat generated by the T element can be accurately controlled,
Thermal resistance can be determined accurately. Further, since the inspection can be performed without removing the IGBT element 141 from the inverter 140 and without removing the inverter 140 itself from the vehicle 100, the trouble of the inspection can be reduced.

As the current control IGBT element, an IGBT element having a different phase from the measurement target IGBT element and having the arm in the opposite position is used, and the measurement target IGBT element or the IGBT element which performs on / off control is a current By using the IGBT element of a certain phase of the sensor, even if only one current sensor 144 is used, the current of each element can be measured, so that the number of current sensors 144 used can be reduced.

Next, the method for evaluating the life of the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG.
4 is a flowchart showing a life evaluation operation of the semiconductor device according to one embodiment of the present invention.

The center computer 200 evaluates the life of the IGBT 141 using the thermal resistance of the IGBT 141, which is a semiconductor device, measured by the control unit 142. The center computer 200 compares the measured value of the thermal resistance sent from the control unit 142 via the communication device 170 with the previously measured characteristic, and uses the method described below to calculate the remaining life. Is determined. The determination result is transmitted to the user.

In step s200, the center computer 200 has an initial warranty life YI and an inspection interval ΔY
I, critical thermal resistance increase rate Δrc, thermal resistance increase rate measurement accuracy Δ
rD, the ratio rB of the thermal resistance of the assumed crack initiation portion to the total thermal resistance, and the initial thermal resistance Ro are input.

Next, in step s210, the center computer 200 counts the use period Y.

Further, in step s220, when the use period Y becomes longer than the initial guaranteed life YI, the center computer 200 sends an inspection request signal to the inverter 140. Inverter 140 measures thermal resistance RI by the method described with reference to FIGS. Then, the inspection result RI of the thermal resistance transmitted from the inverter 140 is received, and the thermal resistance increase rate ΔrI = (RI−
Ro) / Ro is calculated.

Next, in step s230, the center computer 200 obtains a new life expectancy value Yc based on the following equation (1) based on the thermal resistance increase rate ΔrI. Yc = YI (1 + Δrc / rB) (1+ (ΔrI + ΔrD) / rB) (1) The fact that Yc is obtained by this equation means that the result of measuring the thermal resistance increasing behavior of the IGBT element is as shown in FIG. That's what I understand.

Next, in step s240, the center computer 200 determines whether or not the difference (Yc-YI) between the new life expectancy value Yc and the initial guaranteed life YI is smaller than the inspection interval ΔYI. The inspection interval ΔYI can be arbitrarily determined, but is set, for example, to one year or two years. If the difference (Yc−YI) is smaller than the inspection interval ΔYI, the process proceeds to step s250. If the difference (Yc−YI) is not smaller than the inspection interval ΔYI, the process proceeds to step s260.

In step s240, Yc-YI <
In the case of ΔYI, the service life expires before the next inspection time.
00 transmits a message to the user that the inverter needs to be replaced.

In step s240, Yc-YI <
If it is not ΔYI, the service life is later than the next inspection time, and therefore, in step s260, the center computer 200 sends a notification that the service can be continuously used.

Next, in step s270, the center computer 200 newly sets the guaranteed life YI to (initial guaranteed life YI + inspection interval ΔYI), and returns to before step s220.

By checking the life of the semiconductor device according to the procedure described above, it is possible to extend the use period and prevent wasteful use of resources. In addition, since the inspection is performed automatically, the user can save the trouble of performing the inspection by himself. In addition, since it is possible to centrally grasp the remaining life of each inverter in use at one location, for example, in the case of commercial vehicles, operation plans such as allocating vehicles with a long remaining life to long-distance driving applications etc. It is possible to achieve appropriateness.

As described above, according to the present embodiment, the present invention makes it possible to accurately evaluate the remaining life of a semiconductor device and to extend the use period of the semiconductor device, thereby wasting resources. Prevention of use was made possible.

[0053]

According to the present invention, the remaining life can be accurately evaluated.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an inspection system for carrying out a semiconductor device inspection method according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an internal configuration of the semiconductor device according to the embodiment of the present invention;

FIG. 3 is a cross-sectional view showing an internal configuration of an IGBT element which is a semiconductor element incorporated in the semiconductor device according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram of a fatigue crack generated in an IGBT element incorporated in a semiconductor device according to one embodiment of the present invention.

FIG. 5 is a circuit diagram of a semiconductor device according to an embodiment of the present invention.

FIG. 6 is a flowchart illustrating a processing operation of the control unit 142 of the semiconductor device according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram of a life of the semiconductor device according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram of a life of the semiconductor device according to the embodiment of the present invention.

FIG. 9 is a flowchart showing a thermal resistance measurement processing operation in the control unit of the semiconductor device according to the embodiment of the present invention.

FIG. 10 is a flowchart showing a life evaluation operation of the semiconductor device according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 ... Vehicle 110 ... Internal combustion engine 120 ... Motor 130 ... Wheel 140 ... Inverter 141 ... IGBT element 141L ... IGBT chip 141K ... Joint 141J ... Base 142 ... Control unit 150 ... Battery 170 ... Wireless device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H007 AA05 AA06 CA01 CB04 CB05 DB02 DB12 DC08 FA09 HA04 5H740 AA08 BA11 BB05 BB09 BB10 MM00 MM08 MM11 NN17 PP01 PP05

Claims (4)

[Claims] 1. A semiconductor device having a semiconductor element, comprising: a measuring unit for measuring a thermal resistance of the semiconductor element. 2. The semiconductor device according to claim 1, wherein the semiconductor device is an inverter for controlling a motor, has a plurality of semiconductor elements, and the measuring section turns on the first semiconductor element, A first voltage drop of the first semiconductor element when another semiconductor element is turned off is measured, and a second semiconductor element connected in series with the first semiconductor element via the motor After turning on and off, a second voltage drop of the first semiconductor element when the second semiconductor element is turned off is measured, and the second voltage drop is measured based on the first voltage drop and the second voltage drop. A semiconductor device, wherein the thermal resistance of the semiconductor element is measured. 3. A semiconductor device inspection method for evaluating a remaining life of a semiconductor device having a semiconductor element, wherein the remaining life is evaluated based on the measured thermal resistance of the semiconductor element, and the evaluation result of the remaining life is obtained. A method for inspecting a semiconductor device, comprising the step of notifying the necessity of replacement of the semiconductor device based on the information. 4. The method for inspecting a semiconductor device according to claim 3, wherein the rate of increase in thermal resistance is determined based on the measured thermal resistance of the semiconductor element, and the life of the semiconductor device is determined based on the rate of increase in thermal resistance. A method for inspecting a semiconductor device, comprising: obtaining a predicted value; and evaluating a remaining life.