Patent Publication Number: US-2022229103-A1

Title: Electrical characteristic inspection device for semiconductor device and electrical characteristic inspection method for semiconductor device

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to an electrical characteristic inspection device for a semiconductor device and an electrical characteristic inspection method for the semiconductor device. 
     Description of the Background Art 
     In the conventional electrical characteristic inspection device, by providing a circuit for adjusting an inductive inductance for the semiconductor device in the inspection device, the measurement current and the measurement voltage are supplied based on a measurement condition corresponding to the inspection contents to be conducted (for example, see Japanese Patent Application Laid-Open No. 2009-168630). Further, in the conventional electrical characteristic inspection device, when an abnormality in the supplied measurement current or measurement voltage is detected, the inspection device is protected by using a cutoff switch to conduct inspection. 
     SUMMARY 
     In the conventional electrical characteristic inspection device, while the measurement condition is created using a circuit for adjusting the inductive inductance for the semiconductor device in the inspection device, a mechanism for adjusting the floating inductance is not incorporated therein. 
     The floating inductance existing in the inspection device affects the increase/decrease of surge voltage and current change speed di/dt during inspection. In order to create a precise measurement condition considering such floating inductance, adjustment of wiring length in the inspection device and adjustment such as replacement of inductor are required, making it difficult to create a precise measurement condition. 
     An object of the present disclosure is to provide a technique capable of creating a precise measurement condition in a facilitated manner relating to an electrical characteristic inspection for a semiconductor device. 
     The electrical characteristic inspection device for a semiconductor device according to the present disclosure includes a storage unit, a control unit, an inductive inductance control circuit unit, and a floating inductance control circuit unit. The storage unit stores a measurement condition of the semiconductor device being an inspection subject. The control unit reads out the measurement condition corresponding to inspection contents to be executed. The inductive inductance control circuit unit sets inductive inductance for the semiconductor device. The floating inductance control circuit unit sets floating inductance for the semiconductor device. Based on the measurement condition read out from the storage unit, the control unit adjusts the inductive inductance by controlling the inductive inductance control circuit unit and adjusts the floating inductance by controlling the floating inductance control circuit unit. The control unit adjusts the floating inductance in addition to the inductive inductance; therefore, an adjustment of a wiring length and an adjustment such as the inductor replacement in the inspection device. are not required, ensuring to create a precise measurement condition in a facilitated manner in consideration of the floating inductance existing in the inspection device. 
     These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating an example of a configuration of an electrical characteristic inspection device for a semiconductor device according to Embodiment; 
         FIG. 2  is a flowchart illustrating an example of an electrical characteristic inspection method for the semiconductor device according to Embodiment; 
         FIG. 3  is a circuit diagram illustrating an example of a configuration of a floating inductance control circuit unit included in the electrical characteristic inspection device for the semiconductor device according to Embodiment; 
         FIG. 4  is a table illustrating a relationship between a switching state of subtraction adjustment switches and the inductance of a primary inductor included in the floating inductance control circuit unit; 
         FIG. 5  is a table illustrating a relationship between a switching state of addition adjustment switches and the inductance of a secondary inductor included in the floating inductance control circuit unit; and 
         FIG. 6  is a diagram illustrating waveforms of a measurement voltage and a measurement current in the RBSOA test. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 
     Hereinafter, Embodiment will be described with reference to the drawings.  FIG. 1  is a block diagram illustrating an example of a configuration of an electrical characteristic inspection device  100  for a semiconductor device according to Embodiment. 
     As illustrated in  FIG. 1 , the electrical characteristic inspection device  100  is an inspection device that inspects a semiconductor device  108  being an inspection subject, and includes a storage unit  101 , a control unit  102 , a power supply unit  103 , an inductive inductance control circuit unit  104 , a gate driver  105 , a floating inductance control circuit unit  106 , a signal input unit  107 , and a measurement unit  109 . 
     The storage unit  101  is, for example, a Random Access Memory (RAM) or a Read Only Memory (ROM), and stores a plurality of measurement conditions of the semiconductor device  108 . 
     The control unit  102  is, for example, a processor, and reads out a measurement condition corresponding to the inspection contents to be performed from the storage unit  101 , and based on the read measurement condition, controls the power supply unit  103 , the inductive inductance control circuit unit  104 , the gate driver  105 , and the floating inductance control circuit unit  106 . The control unit  102  also controls the signal input unit  107  and the measurement unit  109 . 
     The power supply unit  103  supplies the electric power required for the inspection. Specifically, the electric power supplied from the power supply unit  103  is supplied to the semiconductor device  108  via the signal input unit  107 . 
     The inductive inductance control circuit unit  104  sets the inductive inductance L for the semiconductor device  108 . A known technique is used for the inductive inductance control circuit unit  104 . The inductive inductance control circuit unit  104  has, for example, a plurality of inductors and switches, and the inductors to be connected are switched by switching the switches. 
     The induct inductance L is set according to the contents of the L load test of the semiconductor device  108 . The inductive inductance L is several hundred pH or more and several mH or less, and has a large inductance component. Therefore, in order to a create precise measurement condition, the floating inductance set by the floating inductance control circuit unit  106  to be described later is required to be adjusted. The gate driver  105  sets the gate voltage VGE and the gate resistance Rg of the semiconductor device  108  being the inspection subject based on the measurement condition read out from the storage unit  101  by the control unit  102 . The gate driver  105  has, for example, a plurality of resistance elements and a switch, and the resistance elements to be connected are switched by switching the switch. 
     The floating inductance control circuit unit  106  sets the floating inductance Ls for the semiconductor device  108  based on the measurement condition read out from the storage unit  101  by the control unit  102 . Although not illustrated in  FIG. 1 , the floating inductance control circuit unit  106  has a plurality of inductors and switches, and the inductors to be connected are switched by switching the switches. The details of the floating inductance control circuit unit  106  will be described later. 
     Here, the measurement condition is information including numerical values set for a VCE, the gate voltage VGE, the gate resistance Rg, the inductive inductance L, and the floating inductance Ls. 
     The signal input unit  107  supplies the electric power supplied from the power supply unit  103  to the semiconductor device  108  via the inductive inductance control circuit unit  104 , the gate driver  105 , and the floating inductance control circuit unit  106 . The signal input unit  107  may be provided, for example, in a test head (not illustrated) included in the electrical characteristic inspection device  100 . 
     The measurement unit  109  detects the voltage to be measured and the current to be measured of the semiconductor device  108  via the signal input unit  107 . The control unit  102  may determine a fracture in the semiconductor device  108  in response to the change in the voltage to be measured. Also, the control unit  102  may determine a fracture in the semiconductor device  108  in response to the change in the current to be measured. 
     The semiconductor device  108  being the inspection subject is an electronic device that operates a predetermined action in response to a given current and voltage, and is, for example, an Insulated Gate Bipolar Transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOS-FET), or semiconductor element such as a diode. Further, the semiconductor device  108  includes a semiconductor device in which these electronic devices are combined and housed in one package, and a semiconductor device in which these electronic devices are mounted on a substrate to realize a predetermined function. 
     Next, with reference to  FIG. 2 , an electrical characteristic inspection method for semiconductor device method using the electrical characteristic inspection device  100  will be described.  FIG. 2  is a flowchart illustrating an example of an electrical characteristic inspection method for the semiconductor device. 
     As illustrated in  FIG. 2 , when the electrical characteristic inspection is started, the control unit  102  reads out the measurement condition corresponding to the inspection contents to be conducted from the storage unit  101  (Step S 1 ). Next, the control unit  102  causes the power supply unit  103  to set the VCE based on the measurement condition read out from the storage unit  101  (Step S 2 ). 
     Next, the control unit  102  causes the inductive inductance control circuit unit  104  to set the inductive inductance L based on the measurement condition read out from the storage unit  101  (Step S 3 ). Here, the control unit  102  adjusts the inductive inductance L by switching the switches of the inductive inductance control circuit unit  104 . 
     Next, the control unit  102  causes the gate driver  105  to set the gate voltage VGE and the gate resistance Rg based on the measurement condition read out from the storage unit  101  (Step S 4 ). 
     Next, the control unit  102  causes the floating inductance control circuit unit  106  to set the floating inductance Ls based on the measurement condition read out from the storage unit  101  (Step S 5 ). The method of adjusting the floating inductance Ls will be described later. 
     The setting based on the measurement condition in Steps S 2  to S 5  does not necessarily to be performed in this order and may be performed in any order. 
     Next, the control unit  102  starts measurement by supplying electric power to the semiconductor device  108  being the inspection subject via the signal input unit  107 , and causes the measurement unit  109  to measure the voltage to be measured and the current to be measured (Step. S 6 ). Then, the control unit  102  completes the electrical characteristic inspection after outputting the measurement result and the determination of the result to the display unit (not illustrated) included in the electrical characteristic inspection device  100 . 
     Here, when there are a plurality of measurement conditions read out in Step S 1 , after the measurement based on one measurement condition is completed, the process may return to Step S 2  to perform the setting and measurement based on the next measurement condition. 
     The details of the floating inductance control circuit unit  106  will be described with reference to  FIGS. 3 to 5 .  FIG. 3  is a circuit diagram illustrating an example of a configuration of the floating inductance control circuit unit  106 .  FIG. 4  is a table illustrating the relationship between a switching state of the subtraction adjustment switches  206 - 1  to  206 - 10  and the inductance Ls 1  of the primary inductor  201  included in the floating inductance control circuit unit  106 .  FIG. 5  is a table illustrating the relationship between a switching state of the addition adjustment switches  203 - 1  to  203 - 3  and the inductance Ls 2  of the secondary inductor  204  included in the floating inductance control circuit unit  106 . 
     As illustrated in  FIG. 3 , the floating inductance control circuit unit  106  includes a primary inductor  201 , addition adjustment inductors  202 - 1  to  202 - 3 , addition adjustment switches  203 - 1  to  203 - 3 , a secondary inductor  204 , subtraction adjustment switches  206 - 1  to  206 - 10 , and subtraction adjustment inductors  207 - 1  to  207 - 9 . 
     When the addition adjustment inductors  202 - 1  to  202 - 3  are not distinguished, they are described as an addition adjustment inductor  202 . Similarly, when the addition adjustment switches  203 - 1  to  203 - 3 , the subtraction adjustment switches  206 - 1  to  206 - 10 , and the subtraction adjustment inductors  207 - 1  to  207 - 9  are not distinguished, they are respectively described as addition adjustment switches  203 , subtraction adjustment switches  206 , and subtraction adjustment inductors  207 . 
     Also, as illustrated in  FIG. 1 , although the floating inductance control circuit unit  106  is arranged between the inductive inductance control circuit unit  104  and the signal input unit  107 , the arrangement of the floating inductance control circuit unit  106  may be changed in accordance with a type of the semiconductor device  108  being the inspection subject or a configuration of circuits arranged around the floating inductance control circuit unit  106  as long as the adjustment of the floating inductance Ls would not be affected. 
     As illustrated in  FIG. 3 , the primary inductor  201  constitutes a transformer  205  with the secondary inductor  204 , and is capable of subtracting the inductance Ls 1  of the primary inductor  201  for adjustment by the interaction with the secondary inductor  204 . 
     The subtraction adjustment inductors  207 - 1  to  207 - 9  are connected in series. The subtraction adjustment switches  206 - 1  to  206 - 10  switch the connection state between the secondary inductor  204  and the subtraction adjustment inductors  207 - 1  to  207 - 9 . The number of subtraction adjustment inductors  207  to be connected in series with the secondary inductor  204  can be changed by the ON/OFF combination of the subtraction adjustment switches  206  as illustrated in  FIG. 4 . 
     As a result, based on the principle of the current transformer, the inductance Ls 1  of the primary inductor  201  is finely adjusted in units of 0.1 [pH] by the ON/OFF combination of the subtraction adjustment switches  206  as illustrated in  FIG. 4 . Of the subtraction adjustment switches  206 , a subtraction adjustment switch  206  which is not stated in the “ON subtraction adjustment switch” in  FIG. 4 , is OFF. 
     Further, the floating inductance control circuit unit  106  has a shield function for insulating the transformer  205  composed of the primary inductor  201  and the secondary inductor  204  against disturbance. Specifically, noise countermeasures are taken by physically providing a sufficient distance between the subtraction adjustment inductors  207  and the addition adjustment inductors  202 , or by arranging a shield. 
     The addition adjustment inductors  202 - 1  to  202 - 3  are connected in series, and are connected in parallel with the addition adjustment switches  203 - 1  to  203 - 3 , respectively. The addition adjustment switches  203 - 1  to  203 - 3  switch the connection state between the primary inductor  201  and the addition adjustment inductors  202 - 1  to  202 - 3 . The number of addition adjustment inductors  202  connected in series with the primary inductor  201  can be changed by the ON/OFF combination of the addition adjustment switches  203  as illustrated in  FIG. 5 . Of the addition adjustment switches  203 , an addition adjustment switch  203  which is not stated in the “ON addition adjustment switch” in  FIG. 5 , is OFF. 
     As a result, by combining ON/OFF of the addition adjustment switches  203  as illustrated in  FIG. 5 , the inductance Ls 2  of the addition adjustment inductors  202  can be added to the inductance Ls 1  of the primary inductor  201  for adjustment. In  FIG. 5 , it is illustrated that when the addition adjustment inductor  202 - 1  is 1 [pH], the addition adjustment inductor  202 - 2  is 2 [pH], and the addition adjustment inductor  202 - 3  is 4 [pH], the inductance Ls 2  can be added in a unit of 1 [pH] while being roughly adjusted. 
     Depending on the combination of ON/OFF of the addition adjustment switches  203 , the addition adjustment inductors  202  may perform addition by stepwisely increasing the inductance Ls 2  in a manner of 1 [pH], 2 [pH], and 4 [pH]. 
     In present Embodiment, the floating inductance Ls can be set by finely adjusting the floating inductance by subtraction and roughly adjusting the floating inductance by addition. That is, the floating inductance Ls is calculated by adding the inductance Ls 1  and the inductance Ls 2 . 
     Next, with reference to  FIG. 6 , a case where a Reverse Biased Safe Operating Area (RBSOA) test is conducted using an IGBT having a collector terminal, an emitter terminal and a gate terminal on the semiconductor device  108  being the inspection subject will be described.  FIG. 6  is a diagram illustrating waveforms of a measurement voltage and a measurement current in the RBSOA test. 
     Here, the VGE illustrated in  FIG. 6  indicates the voltage between the gate terminal and the emitter terminal of the semiconductor device  108  being the inspection subject. VCE indicates the voltage between the collector terminal and the emitter terminal of the semiconductor device  108 . Ic indicates the collector current between the collector terminal and the emitter terminal of the semiconductor device  108 . 
     As illustrated in  FIG. 6 , in a first period, the semiconductor device  108  is in a non-conducting state in which no voltage is applied to the gate terminal. Therefore, the inductive inductance control circuit unit  104  does not supply the measurement current Ic to the semiconductor device  108 . Further, a divided voltage of the power supply voltage is applied as a voltage VCE between the collector terminal and the emitter terminal of the semiconductor device  108 . 
     In a second period, the semiconductor device  108  is brought into a conductive state by the application of a voltage to the gate terminal. When the semiconductor device  108  is brought into a conductive state, the measurement current Ic flows between the collector terminal and the emitter terminal. The measurement current Ic is supplied via the inductive inductance control circuit unit  104 ; therefore, the current value rises at a rate of change corresponding to the inductive inductance L of the inductive inductance control circuit unit  104 , and energy is accumulated in the inductive inductance control circuit unit  104 . Further, when the semiconductor device  108  is brought into a conductive state, the voltage VCE between the collector terminal and the emitter terminal of the semiconductor device  108  approaches 0. 
     In a third period, the semiconductor device  108  is brought into a non-conducting state due to the cutoff of the voltage applied to the gate terminal by the gate driver  105 . When the semiconductor device  108  is brought into the non-conducting state, the measurement current Ic stops flowing between the collector terminal and the emitter terminal of the semiconductor device  108 . The measurement current Ic at this time may be returned by a freewheel diode or the like to consume energy. Further, when the semiconductor device  108  is brought into the non-conducting state, the voltage VCE between the collector terminal and the emitter terminal rises to a value obtained by adding a surge voltage to the divided voltage of the power supply voltage. 
     In a fourth period, a tail current Ic flows between the collector terminal and the emitter terminal of the semiconductor device  108 . The magnitude of the tail current Ic depends on the magnitude of the floating inductance Ls existing in the circuit, and the larger the floating inductance Ls, the larger the tail current Ic. Further, the larger the tail current Ic, the longer the time for the tail current Ic to flow. 
     Meanwhile, the maximum value of the voltage VCE between the collector terminal and the emitter terminal of the semiconductor device  108  also depends on the magnitude of the floating inductance Ls existing in the circuit, and the larger the floating inductance Ls, the larger the surge voltage VCE. The adjustment of the floating inductance Ls in this manner ensures control of the surge voltage VCE and tail current Ic during inspection. 
     As described above, the electrical characteristic inspection device  100  according to Embodiment includes the storage unit  101  that stores a measurement condition of the semiconductor device  108  being the inspection subject, the control unit  102  that reads out the measurement condition corresponding to inspection contents to be executed from the storage unit  101 , the inductive inductance control circuit unit  104  that sets the inductive inductance L for the semiconductor device  108 , the floating inductance control circuit unit  106  that sets the floating inductance Ls for the semiconductor device  108 , in which, based on the measurement condition read out from the storage unit  101 , the control unit  102  adjusts the inductive inductance L by controlling the inductive inductance control circuit unit  104 , and adjusts the floating inductance Ls by controlling the floating inductance control circuit unit  106 . 
     Therefore, the control unit  102  adjusts the floating inductance Ls in addition to the inductive inductance L; therefore, an adjustment of a wiring length and an adjustment such as the inductor replacement in the electrical characteristic inspection device  100  are not required, ensuring to create a precise measurement condition in a facilitated manner in consideration of the floating inductance Ls existing in the electrical characteristic inspection device  100 . 
     As described above, the control unit  102  is capable of easy adjustment of the floating inductance Ls; therefore, in the electrical characteristic inspection device  100 , accurate reproduction of the inspection under the same measurement condition as the previously performed inspection is ensured. 
     Further, the floating inductance control circuit unit  106  includes the primary inductor  201 , the secondary inductor  204  constituting the transformer  205  with the primary inductor  201 , the plurality of addition adjustment inductors  202  connectable to the primary inductor  201 , the addition adjustment switches  203  that adjust the inductance Ls 2  of the secondary inductor  204  by switching the connection state between the primary inductor  201  and each of the addition adjustment inductors  202 , the plurality of subtraction adjustment inductors  207  connectable to the secondary inductor  204 , and the subtraction adjustment switches  206  that adjust the inductance Ls 1  of the primary inductor  201  by switching the connection state between the secondary inductor  204  and each of the subtraction adjustment inductors  207 , in which the control unit  102  adjusts the floating inductance Ls by the inductance Ls 1  of the primary inductor  201  and the inductance Ls 2  of the secondary inductor  204  by controlling the addition adjustment switches  203  and the subtraction adjustment switches  206 . 
     Therefore, the adjustment of the floating inductance Ls in a facilitated manner is ensured by the interaction between the primary inductor  201  and the secondary inductor  204 . 
     Further, the floating inductance control circuit unit  106  has a shield function for insulating the transformer  205  against disturbance; therefore, the adjustment accuracy of the floating inductance Ls is improved by suppressing the disturbance to the transformer  205 . 
     Embodiment can be appropriately modified. 
     While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.