Semiconductor testing apparatus and semiconductor testing method

Abstract

A test stage (51) holds a wafer (63) on which a plurality of semiconductor elements (26, 27) are arranged, and has a function of a positive electrode electrically connected to the positive electrodes of the plurality of semiconductor elements (26, 27). Constant current sources (1, 2) supply constant currents to the test stage (51). A first probe (53) connects the negative electrode of the semiconductor element (27) to the negative electrode (42) of the constant current source. Electrodes (31, 32) are arranged on the outer periphery of the test stage (51), are connected to one of the constant current sources (1, 2), and function as two current supply points. A collector sensing terminal (33) is arranged on the outer periphery of the test stage (51). A voltmeter (3) measures the voltage between the collector sensing terminal (33) and the negative electrode (42) of the constant current source.

Description

Technical Field

[0001] This disclosure relates to semiconductor testing apparatus and semiconductor testing methods. Background Technology

[0002] The performance of semiconductor components is ensured through characteristic tests conducted during the testing process of manufacturing. These characteristic tests include applying high voltage or high current to semiconductor components and screening.

[0003] Characterization tests include tests performed in the form of modules and tests performed in the form of semiconductor devices. To reduce manufacturing costs, characterization tests are preferably performed in the form of wafers. However, there is a problem: the reproducibility of the measurement results is low due to the difference between the resistance that varies depending on the contact between the test stage on which the wafer is placed and the back side of the wafer, and the resistance along the path from the test stage to the measurement point.

[0004] Patent document 1 discloses a structure that reduces the contact resistance between the test stage and the back side of the wafer as a test method for semiconductor transistors.

[0005] In Patent Document 1, the density of the adsorption pores set on the test stage is set to 100 pores / cm². 2 The above measures can reduce the contact resistance between the test stage and the back electrode of the wafer. This, in turn, can mitigate the problem of low measurement reproducibility.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2015-26765 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] However, the test method described in Patent Document 1 cannot eliminate the influence of the resistance difference along the path from the test stage to the measurement point. Therefore, there is a problem that the measurement error causes deviation in the plane of the wafer.

[0011] Therefore, the purpose of this disclosure is to provide a semiconductor testing apparatus and a semiconductor testing method that can reduce the deviation of in-plane measurement error in tests performed in the wafer state of semiconductor devices.

[0012] means for solving problems

[0013] The semiconductor testing apparatus disclosed herein is used for performing characteristic tests on semiconductor devices. The semiconductor device has a positive electrode on its back side, a negative electrode on its front side, and a control electrode. It is turned on or off according to a control signal input to the control electrode. The semiconductor testing apparatus comprises: a test stage for fixing a wafer on which multiple semiconductor devices are disposed, and having a positive electrode electrically connected to the positive electrodes of the multiple semiconductor devices; N constant current sources, where N is a natural number greater than 2; a first probe for connecting the negative electrode of a semiconductor device to the negative electrode of a constant current source; N electrodes disposed on the outer periphery of the test stage, each connected to one of the N constant current sources, functioning as N current supply points; a collector sensing terminal disposed on the outer periphery of the test stage; and a voltmeter for measuring the voltage between the collector sensing terminal and the negative electrode of the constant current source.

[0014] The semiconductor testing apparatus disclosed herein is used for performing characteristic tests on semiconductor devices. The semiconductor device has a positive electrode on its back side, a negative electrode and a control electrode on its front side, and is turned on or off according to a control signal input to the control electrode. The semiconductor testing apparatus comprises: a test stage for fixing a wafer on which multiple semiconductor devices are disposed, and having a positive electrode electrically connected to the positive electrodes of the multiple semiconductor devices; a constant current source; a first probe for connecting the negative electrode of the semiconductor device to the negative electrode of the constant current source; N electrodes disposed on the outer periphery of the test stage and connected to the constant current source, functioning as current supply points, where N is a natural number greater than 2; a variable resistor and a galvanometer disposed between the constant current source and each of the N electrodes; a collector sensing terminal disposed on the outer periphery of the test stage; and a voltmeter for measuring the voltage between the collector sensing terminal and the negative electrode of the constant current source.

[0015] The semiconductor testing method disclosed herein is a semiconductor testing apparatus for performing characteristic tests on semiconductor devices. The semiconductor device has a positive electrode on its back side, a negative electrode and a control electrode on its front side, and is turned on or off according to a control signal input to the control electrode. The semiconductor testing apparatus includes: a test stage serving as the positive electrode; N constant current sources, where N is a natural number greater than or equal to 2; N electrodes disposed on the outer periphery of the test stage and connected to one of the N constant current sources, functioning as N current supply points; a collector sensing terminal disposed on the outer periphery of the test stage; a first probe; a second probe; and a voltmeter. The semiconductor testing method includes the following steps: fixing a wafer with multiple semiconductor devices disposed on the test stage; connecting the positive electrodes of the multiple semiconductor devices to the test stage; connecting the negative electrode of the semiconductor device to the negative electrode of the constant current source via the first probe; connecting the control electrode of the semiconductor device to a drive circuit via the second probe; starting to supply constant current from the N constant current sources; and measuring the voltage between the collector sensing terminal and the negative electrode of the constant current source using the voltmeter.

[0016] The effects of the invention

[0017] According to this disclosure, in tests performed in the wafer state of semiconductor devices, it is possible to reduce the deviation of in-plane measurement errors of the wafer. Attached Figure Description

[0018] Figure 1 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 1.

[0019] Figure 2 This is a simplified diagram of the path involved in measuring the saturation voltage of the semiconductor element 27 in Embodiment 1.

[0020] Figure 3 This is a simplified diagram of the path involved in measuring the saturation voltage of the semiconductor element 26 in Embodiment 1.

[0021] Figure 4 This is a flowchart illustrating the steps of the saturation voltage test of the semiconductor element in Embodiment 1.

[0022] Figure 5 This is a diagram illustrating an example of a semiconductor testing apparatus according to Embodiment 2.

[0023] Figure 6 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 3.

[0024] Figure 7 This is a flowchart illustrating the steps of the saturation voltage test of the semiconductor element in Embodiment 3.

[0025] Figure 8 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 4.

[0026] Figure 9 This is a simplified diagram of the path involved in measuring the saturation voltage of the semiconductor element 27 in Embodiment 4.

[0027] Figure 10 This is a simplified diagram of the path involved in measuring the saturation voltage of the semiconductor element 26 in Embodiment 4.

[0028] Figure 11 This is a flowchart illustrating the measurement steps for measuring the saturation voltage in Embodiment 4.

[0029] Figure 12 This is a diagram illustrating an example of the semiconductor testing apparatus of Embodiment 5.

[0030] Figure 13 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 6.

[0031] Figure 14 This is a flowchart illustrating the steps of the saturation voltage test of the semiconductor element in Embodiment 6.

[0032] Figure 15 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 7.

[0033] Figure 16 This is a flowchart illustrating the steps of the saturation voltage test of the semiconductor element in Embodiment 7. Detailed Implementation

[0034] The embodiments will now be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be labeled with the same reference numerals, and their descriptions will generally not be repeated.

[0035] Implementation method 1.

[0036] Figure 1 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 1. The test of collector-emitter saturation voltage (hereinafter referred to as saturation voltage), a representative high-current test, will be used as an example for explanation.

[0037] Reference Figure 1 The semiconductor testing apparatus includes a test stage 51, a first probe 53, a second probe 54, a drive circuit 55, a first constant current source 1, a second constant current source 2, a first electrode 31, a second electrode 32, a collector sensing terminal 33, and a negative electrode 42 of the constant current source.

[0038] The test stage 51 holds the wafer 63. Multiple semiconductor elements are arranged on the wafer 63. Any self-extinguishing type semiconductor element can be used. All semiconductor elements arranged on the wafer 63, or a portion of all semiconductor elements, can be inspected. Semiconductor elements 27 and 26 represent multiple semiconductor elements arranged in a row.

[0039] Semiconductor elements 26 and 27 have a positive electrode on their back side and a negative electrode and a control electrode on their front side. Semiconductor elements 26 and 27 are turned on or off according to a first control signal input from the drive circuit 55 to the control electrode. For example, if semiconductor elements 26 and 27 are MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), the positive electrode is the drain, the negative electrode is the source, and the control electrode is the gate. If semiconductor elements 26 and 27 are IGBTs (Insulated Gate Transistors), the positive electrode is the collector, the negative electrode is the emitter, and the control electrode is the gate. The negative electrode and control electrode are arranged on the front side of semiconductor elements 26 and 27, and the positive electrode is arranged on their back side.

[0040] In semiconductor elements 26 and 27, current flows from the positive electrode on the back side to the negative electrode on the front side. To perform characteristic tests on these semiconductor elements 26 and 27 in the state of wafer 63, the negative electrode on the front side of semiconductor elements 26 and 27 (the emitter in the case of an IGBT) is electrically connected to the negative electrode 42 of the constant current source via a needle-shaped first probe 53. Furthermore, the control electrode on the front side of semiconductor elements 26 and 27 (the gate in the case of an IGBT) is electrically connected to the drive circuit 55 of the semiconductor testing apparatus via a needle-shaped second probe 54. Figure 1 The image shows the state in which the first probe 53 and the second probe 54 are connected to the semiconductor element 27 when the subject is a semiconductor element 27.

[0041] The positive electrode (collector in the case of IGBT) on the back side of semiconductor elements 26 and 27 is directly electrically connected to the test stage 51 (conductor) which has a positive electrode function.

[0042] The first constant current source 1 and the second constant current source 2 supply a fixed current.

[0043] The first electrode 31 is disposed on the outer periphery of the test stage 51. The first electrode 31 is connected to the first constant current source 1. The first electrode 31 functions as the first current supply point for supplying current to the test stage 51. The second electrode 32 is disposed on the outer periphery of the test stage 51. The second electrode 32 is connected to the second constant current source 2. The first electrode 31 and the second electrode 32 are electrically connected to the positive terminals on the back sides of the semiconductor elements 26 and 27.

[0044] The on-resistance (equivalent resistance) of semiconductor element 27 in the saturation voltage test is shown by resistor 17, and the on-resistance (equivalent resistance) of semiconductor element 26 is shown by resistor 16.

[0045] The first constant current source 1 is electrically connected to the negative terminal 42 of the constant current source via the first probe 53, through the resistor 10, the first electrode 31, the resistor 13, and the semiconductor element 27. The first constant current source 1 is also electrically connected to the negative terminal 42 of the constant current source via the first probe 53, through the resistor 10, the first electrode 31, the resistor 12, and the semiconductor element 26.

[0046] Resistor 10 is the resistance of the electrical wiring between the first constant current source 1 and the first electrode 31.

[0047] Resistor 13 is the sum of the resistive components of the current flowing through the test stage 51 when the first constant current source 1 supplies power to the semiconductor element 27, and the contact resistance between the test stage 51 and the positive electrode on the back of the semiconductor element 27. When the resistive components of the test stage 51 are uniform, the current flows through the shortest path between the first electrode 31 and the semiconductor element 27. However, if the test stage 51 has defects, the current may not flow through the shortest path. The same applies to the resistive components from other electrodes to the semiconductor element.

[0048] Resistor 12 is the sum of the resistive components of the current flowing in the test stage 51 when the first constant current source 1 supplies power to the semiconductor element 26, and the contact resistance between the test stage 51 and the positive terminal on the back of the semiconductor element 26.

[0049] The second constant current source 2 is electrically connected to the negative terminal 42 of the constant current source via the first probe 53, through the resistor 11, the second electrode 32, the resistor 14, and the semiconductor element 27. The second constant current source 2 is also connected to the negative terminal 42 of the constant current source via the first probe 53, through the resistor 11, the second electrode 32, the resistor 15, and the semiconductor element 26.

[0050] Resistor 11 is the resistance of the electrical wiring between the second constant current source 2 and the second electrode 32.

[0051] Resistor 14 is the sum of the resistive components of the current flowing in the test stage 51 when the second constant current source 2 supplies power to the semiconductor element 27, and the contact resistance between the test stage 51 and the positive terminal on the back of the semiconductor element 27.

[0052] Resistor 15 is the sum of the resistive components of the current flowing in the test stage 51 when the second constant current source 2 supplies power to the semiconductor element 26, and the contact resistance between the test stage 51 and the positive terminal on the back of the semiconductor element 26.

[0053] The negative terminal (emitter in the case of an IGBT) on the front side of semiconductor element 27 is connected to the negative terminal 42 of the constant current source via the first probe 53, thereby electrically connecting semiconductor element 27 to the negative terminal 42 of the constant current source. Similarly, the negative terminal (emitter in the case of an IGBT) on the front side of semiconductor element 26 is connected via the first probe 53, thereby electrically connecting semiconductor element 26 to the negative terminal 42 of the constant current source.

[0054] The equivalent resistance when the saturation voltage of semiconductor element 27 was measured is resistor 17. The equivalent resistance when the saturation voltage of semiconductor element 26 was measured is resistor 16. For example, when the sum of the current of the first constant current source 1 and the current of the second constant current source 2 is 500A and the saturation voltage of semiconductor element 27 is 1V, resistor 17 is 0.002Ω.

[0055] The collector sensing terminal 33 is disposed on the outer periphery of the test stage 51. The collector sensing terminal 33 is disposed closer to the first electrode 31 than the second electrode 32. The collector sensing terminal 33 is electrically connected to the positive electrode on the back side of the semiconductor devices 26 and 27.

[0056] The voltmeter 3 measures the voltage between the collector sensing terminal 33 and the negative terminal 42 of the constant current source. Using the first constant current source 1, the second constant current source 2, and the voltmeter 3, the saturation voltage of the semiconductor element 27 can be measured at four terminals. Since only a small current flows between the collector sensing terminal 33 and the first electrode 31, and the resistance is also small at the two points between the conductors, the collector sensing terminal 33 and the first electrode 31 can be considered to be at the same potential.

[0057] By moving the test stage 51 arbitrarily, the needle-shaped first probe 53 and second probe 54 can make electrical contact with any semiconductor element on the wafer 63.

[0058] When measuring the saturation voltage of semiconductor element 27, the drive circuit 55 applies a voltage to the control electrode of semiconductor element 27 through the second probe 54, thereby turning semiconductor element 27 into a conducting state. By contacting the first probe 53 with the negative electrode on the front side of semiconductor element 27 and measuring the voltage between the collector sensing terminal 33 and the negative electrode 42 of the constant current source, the saturation voltage of semiconductor element 27 can be measured.

[0059] When measuring the saturation voltage of semiconductor element 26, the drive circuit 55 applies a voltage to the control electrode of semiconductor element 26 through the second probe 54, thereby turning semiconductor element 26 into a conducting state. By contacting the first probe 53 with the negative electrode on the front side of semiconductor element 26 and measuring the voltage between the collector sensing terminal 33 and the negative electrode 42 of the constant current source, the saturation voltage of semiconductor element 26 can be measured.

[0060] Although it is assumed that there is no voltage drop along the path from semiconductor element 27 to the negative electrode 42 of the constant current source, in reality, the needle-shaped first probe 53 and the wiring have a resistive component. Therefore, the voltmeter 3 can also measure the voltage between the tip of the needle of the first probe 53 and the collector sensing terminal 33 instead of measuring the voltage between the collector sensing terminal 33 and the negative electrode 42 of the constant current source.

[0061] The first electrode 31 and the second electrode 32 are preferably located at a point symmetrical position about the center of the test stage 51. When the resistance of the test stage 51 is uniform, and neglecting the contact resistance between the positive electrode on the back side of the semiconductor element and the test stage 51, the magnitudes of resistors 12, 13, 14, and 15 are proportional to the distance from the electrode to the semiconductor element. If the first electrode 31 and the second electrode 32 are arranged at a point symmetrical position about the center of the test stage 51, then when semiconductor elements 26 and 27 are located at a point symmetrical position about the center of the test stage 51, the values ​​of resistors 13 and 15 become the same, and the values ​​of resistors 14 and 12 become the same. Therefore, the saturation voltage of semiconductor element 26 becomes the same as that of semiconductor element 27. However, even without point symmetry, it is possible to reduce the deviation of the saturation voltage measurement error caused by the semiconductor testing apparatus, such as the resistance 13, within the wafer 63 plane.

[0062] Figure 2 This is a simplified diagram of the path involved in measuring the saturation voltage of the semiconductor element 27 in Embodiment 1. Figure 3 This is a simplified diagram of the path involved in measuring the saturation voltage of the semiconductor element 26 in Embodiment 1.

[0063] Reference Figure 2 and Figure 3 The calculation method for the saturation voltage (also known as Vce(sat)) used in typical high-current tests will be explained. Since variable-based calculations would be cumbersome, real numbers will be substituted into the resistance values ​​here. The semiconductor elements 26 and 27 of the test object will be described below as IGBTs.

[0064] Assume the positional relationship between semiconductor element 27 and the first electrode 31, and the positional relationship between semiconductor element 26 and the second electrode 32, are point-symmetric about the center point of the test stage 51. Assume the saturation voltages of semiconductor elements 26 and 27 are the same. Assume resistors 10, 11, 12, 13, 14, 15, 16, and 17 are all 0.007Ω.

[0065] When a fixed voltage, such as 15V, is applied to the gate of semiconductor element 27 to turn it on, and a large current, such as 300A, flows through the collector of semiconductor element 27, the collector-emitter voltage of semiconductor element 27 is its saturation voltage. However, directly measuring the voltage between the collector and emitter electrodes of semiconductor element 27 is difficult. Therefore, in a typical saturation voltage test, the voltage between the collector sensing terminal 33 and the negative terminal 42 of the constant current source is measured, and this voltage is set as the saturation voltage of semiconductor element 27. This saturation voltage is the value of the voltage drop including resistor 13.

[0066] In conventional saturation voltage tests, there is usually one constant current source and one or two current supply points. With one current supply point, the further the semiconductor element is from the current supply point, the greater the resistance of the test stage 51, resulting in a higher measured saturation voltage than the true value. Therefore, with one current supply point, the measurement error of the semiconductor element's saturation voltage deviates within the wafer 63 plane. With two current supply points, current is supplied from one constant current source through two current paths. Therefore, if the sum of the wiring resistance and the resistance of the test stage is not equal in the two current paths, the current becomes unbalanced. However, the resistance of the test stage varies depending on the position of the semiconductor element, making it difficult to equalize the resistances of the two current paths.

[0067] In this embodiment, by using the first constant current source 1 and the second constant current source 2, for example, half of the desired current (300A in this case), i.e., 150A, can be fixedly directed to the first electrode 31. Therefore, the measurement error based on the resistor 13 can be reduced to 1 / 2. As a result, the deviation of the measurement error of the saturation voltage of the semiconductor element caused by the aforementioned current within the wafer 63 plane can be reduced.

[0068] exist Figure 2 With the resistance value shown, and a current flowing to the collector of the semiconductor element of 300A, the saturation voltage of the semiconductor element 27 is 3.6V. Figure 3 With the resistance value shown, the saturation voltage of semiconductor element 26 is 5.1V. Figure 2 and Figure 3 In the case where there is only one constant current source, the difference between the saturation voltage of semiconductor element 26 and the saturation voltage of semiconductor element 27 is improved by 6%.

[0069] Figure 4 This is a flowchart illustrating the steps of the saturation voltage test of the semiconductor element in Embodiment 1.

[0070] In step S02, the semiconductor testing apparatus is connected to the semiconductor element of the test object. For example, if the test object is a semiconductor element 27 as an IGBT, the emitter on the front side of the semiconductor element 27 is electrically connected to the negative terminal 42 of the constant current source through a needle-shaped first probe 53, the gate on the front side of the semiconductor element 27 is electrically connected to the drive circuit 55 of the semiconductor testing apparatus through a needle-shaped second probe 54, and the collector on the back side of the semiconductor element 27 is directly electrically connected to the test stage 51 (conductor) which has a positive electrode function.

[0071] In step S03, the driving circuit 55 turns on the semiconductor element of the object being tested.

[0072] In step S04, current is supplied from the semiconductor testing device. That is, the first constant current source 1 and the second constant current source 2 output the same current (150A).

[0073] In step S05, voltmeter 3 measures the saturation voltage of the semiconductor element of the test subject by measuring the voltage between the collector sensing terminal 33 and the negative terminal 42 of the constant current source. If the measured saturation voltage is within the standard range, the process proceeds to step S06. If the measured saturation voltage is outside the standard range, the process proceeds to step S07.

[0074] In step S06, the semiconductor components of the tested object are determined to be qualified.

[0075] In step S07, the semiconductor components of the tested object are determined to be unqualified. In the case of unqualification, for example, the semiconductor components of the tested object can be marked with ink. Alternatively, the qualified and unqualified status can be recorded electronically.

[0076] After steps S06 and S07, the process proceeds to step S08.

[0077] In step S08, the current supply from the semiconductor testing apparatus is stopped. That is, the current output from the first constant current source 1 and the second constant current source 2 is stopped. The drive circuit 55 cuts off the semiconductor element of the test object.

[0078] In step S09, the connection between the semiconductor testing device and the semiconductor element of the test subject is disconnected.

[0079] In step S10, the test stage 51 moves to the measurement position of the next semiconductor element. Steps S01 to S10 are repeated until all semiconductor elements on wafer 63 have been measured. Alternatively, in the case of a sampling test, only semiconductor elements at predetermined positions are measured.

[0080] As explained above, according to the semiconductor testing apparatus and semiconductor testing method of Embodiment 1, by fixing the current flowing in the first electrode 31, the deviation of the measurement error in the plane of the wafer 63 during high-current tests such as the measurement of the saturation voltage of the semiconductor element can be reduced.

[0081] Implementation method 2.

[0082] Although the true value of the saturation voltage of the semiconductor element 27 is equal to the voltage across the resistor 17, it is difficult to directly measure the potential between the collector electrode and the emitter electrode of the semiconductor element 27. Therefore, in Embodiment 1, the voltage between the collector sensing terminal 33 and the negative electrode 42 of the constant current source is measured and this voltage is set as the saturation voltage of the semiconductor element 27.

[0083] The saturation voltage of semiconductor element 27 deviates from its true value due to the resistive component of the path from resistor 17 to the negative electrode 42 of the constant current source. To mitigate this deviation, the resistive component must be reduced. In Embodiment 1, by having two constant current sources and two current supply points, the current flowing to the first electrode 31 is halved. This allows the voltage drop based on resistor 13 to be reduced to half.

[0084] In this embodiment, there are N constant current sources and N current supply points. N is a natural number greater than or equal to 3. The N electrodes are arranged at equal angular intervals on the outer periphery of the test stage 51. Each of the N electrodes is connected to one of the corresponding constant current sources among the N constant current sources, thus functioning as N current supply points.

[0085] Figure 5 This is a diagram illustrating an example of a semiconductor testing apparatus according to Embodiment 2. Figure 5 The case where N=4 is shown. This semiconductor testing apparatus, based on the structure of the semiconductor testing apparatus in Embodiment 1, further includes a third constant current source 101, a fourth constant current source 102, a third electrode 131, and a fourth electrode 132. Resistor 110 is the resistance of the electrical wiring between the third constant current source 101 and the third electrode 131. Resistor 111 is the resistance of the electrical wiring between the fourth constant current source 102 and the fourth electrode 132. A diagram illustrating the resistive components within the test stage 51 is omitted.

[0086] Electrode 31 is connected to constant current source 1. Electrode 32 is connected to constant current source 2. Electrode 131 is connected to constant current source 101. Electrode 132 is connected to constant current source 102. Electrodes 31, 31, 32, and 42 are arranged at 90° intervals on the outer periphery of the test stage 51.

[0087] According to this embodiment, the current flowing to the first electrode 31 becomes 1 / N, therefore, the voltage drop based on resistor 13 is reduced to 1 / N. Thus, the deviation of the saturation voltage caused by resistor 13 from the true value can be reduced to 1 / N. As a result, the measurement error based on resistor 13 can be reduced to 1 / N.

[0088] Implementation method 3.

[0089] Figure 6 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 3. The semiconductor testing apparatus of Embodiment 3 differs from that of Embodiment 1 in that the semiconductor testing apparatus of Embodiment 3 has only one constant current source 1, and includes a first variable resistor 71, a second variable resistor 72, a first ammeter 81, and a second ammeter 82.

[0090] A first variable resistor 71 and a first ammeter 81, connected in series, are disposed between the constant current source 1 and the first electrode 31. A second variable resistor 72 and a second ammeter 82, connected in series, are disposed between the constant current source 1 and the second electrode 32.

[0091] The first ammeter 81 measures the current flowing to the first variable resistor 71. The second ammeter 82 measures the current flowing in the second variable resistor 72. Alternatively, the first ammeter 81 and the second ammeter 82 can be replaced by an oscilloscope to measure the transient voltage of the current transformer.

[0092] Figure 7 This is a flowchart illustrating the steps of the saturation voltage test of the semiconductor element in Embodiment 3.

[0093] The difference between the flowchart of Embodiment 3 and the flowchart of Embodiment 2 is that the flowchart of Embodiment 3 includes step S04a between step S04 and step S05.

[0094] In step S04a, the magnitude of the current flowing to the first variable resistor 71 is measured using the first ammeter 81. The magnitude of the current flowing to the second variable resistor 72 is measured using the second ammeter 82. The resistance values ​​of the first variable resistor 71 and the second variable resistor 72 are adjusted so that the values ​​of the first ammeter 81 and the second ammeter 82 are equal. This ensures that the magnitude of the current flowing to the first electrode 31 is equal to the magnitude of the current flowing to the second electrode 32.

[0095] In this embodiment, by making the current flowing to the first electrode 31 equal to the current flowing to the second electrode 32, the deviation of the in-plane measurement error of the wafer 63 in high-current tests such as saturation voltage measurement can be reduced.

[0096] A variation of implementation method 3.

[0097] In Embodiment 3, the magnitude of the resistance component between the semiconductor element of the test subject and the first electrode 31, and the resistance component between the semiconductor element of the test subject and the second electrode 32 are determined in advance. For example, the in-plane distribution of the voltage drop in a wafer with a known resistance value for semiconductor elements such as TEG (Test Element Group) wafers is obtained. Since the current value and the resistance value of the semiconductor element are known, the resistance component between the semiconductor element of the test subject and the first electrode 31, and the resistance component between the semiconductor element of the test subject and the second electrode 32, can be determined.

[0098] By adjusting the values ​​of the first variable resistor 71 and the second variable resistor 72, the current flowing to the first electrode 31 and the second electrode 32 is always equal, thereby achieving the same effect as in embodiment 3.

[0099] Implementation method 4.

[0100] Figure 8 This is a diagram showing the structure of the semiconductor testing apparatus of Embodiment 4. The difference between the semiconductor testing apparatus of Embodiment 4 and the semiconductor testing apparatus of Embodiment 1 is that the semiconductor testing apparatus of Embodiment 4 includes a voltmeter 3a and an arithmetic unit 69 instead of the voltmeter 3a.

[0101] Voltmeter 3a measures the voltage Vce(sat)A between collector sensing terminal 33 and the negative terminal 42 of the constant current source. At the same time, voltmeter 3a measures the voltage Vce(sat)B between collector sensing terminal 34 and the negative terminal 42 of the constant current source.

[0102] Assume that the collector sensing terminal 34 and the second electrode 32 are at the same potential. By calculating the measured voltages Vce(sat)A and Vce(sat)B, the saturation voltage Vce(sat) of the semiconductor device can be determined.

[0103] Figure 9 This is a simplified diagram of the path involved in measuring the saturation voltage of the semiconductor element 27 in Embodiment 4. Figure 10 This is a simplified diagram of the path involved in measuring the saturation voltage of the semiconductor element 26 in Embodiment 4.

[0104] Reference Figure 9 and Figure 10This section explains the method for calculating the measured values ​​of the saturation voltage, a common measure in high-current tests. Since variable-based calculations can become cumbersome, real numbers are substituted into the resistance values ​​here. That is, let resistor 10 be 0.05Ω, resistor 11 be 0.10Ω, resistor 12 be 0.02Ω, resistor 13 be 0.01Ω, resistor 14 be 0.02Ω, resistor 15 be 0.01Ω, resistor 16 be 0.007Ω, and resistor 17 be 0.007Ω. These are related to... Figure 2 , 3 The same resistance value as the one in the middle.

[0105] Assume the resistance of the test stage 51 is uniform, and the contact resistance between the positive electrode on the back side of the wafer 63 and the test stage 51 is uniform. If the positional relationship between semiconductor element 27 and the first electrode 31, and the positional relationship between semiconductor element 26 and the second electrode 32, are symmetrical about the center point of the test stage 51, then the magnitudes of resistor 13 and resistor 14 become the same.

[0106] In actual test setups, the resistivity of the test stage 51 is not uniform, and the electrical contact resistance between the positive electrode on the back side of the wafer 63 and the test stage 51 is also not uniform. Therefore, the magnitudes of resistor 13 and resistor 14 vary depending on the position of the semiconductor element on the wafer 63. In this embodiment, by averaging the two measured values ​​Vce(sat)A and Vce(sat)B, for example, the deviation between the magnitudes of resistor 13 and resistor 14 can be reduced.

[0107] The arithmetic unit 69 can also change the method of calculating the saturation voltage Vce(sat) of the semiconductor element based on the measured values ​​Vce(sat)A and Vce(sat)B, depending on the position of the semiconductor element.

[0108] For example, a weighted method based on the difference in distance between the semiconductor element and the two electrodes can also be used.

[0109] Alternatively, if the distance from semiconductor element 27 to the first electrode 31 is half the distance from semiconductor element 27 to the second electrode 32, the measured value Vce(sat)A is considered to have less influence from the path resistance and is closer to the true value than the measured value Vce(sat)B. Therefore, the arithmetic device 69 can also set the measured value Vce(sat)A as the saturation voltage Vce(sat) of semiconductor element 27.

[0110] Figure 11 This is a flowchart illustrating the measurement steps for measuring the saturation voltage according to Embodiment 4. The difference between the flowchart of Embodiment 4 and the flowchart of Embodiment 1 is that the flowchart of Embodiment 4 includes step S04b between steps S04 and S05.

[0111] In step S04b, voltmeter 3a measures the voltage Vce(sat)A between collector sensing terminal 33 and the negative terminal 42 of the constant current source. Voltmeter 3a also measures the voltage Vce(sat)B between collector sensing terminal 34 and the negative terminal 42 of the constant current source. For example, the arithmetic unit 69 can calculate the saturation voltage Vce(sat) of the semiconductor element of the test subject by performing calculations (e.g., averaging) on ​​these measured values.

[0112] As explained above, in the semiconductor testing apparatus and semiconductor testing method according to Embodiment 4, the current flowing in the first electrode 31 and the second electrode 32 is fixed, and the saturation voltage is obtained by calculating the measured values ​​at the two points. As a result, the deviation of the in-plane measurement error of the wafer 63 in the high current test can be reduced.

[0113] Implementation method 5.

[0114] Although the true value of the saturation voltage of the semiconductor element 27 is equal to the voltage across the resistor 17, it is difficult to directly measure the potential between the collector electrode and the emitter electrode of the semiconductor element 27. Therefore, in Embodiment 5, the voltage between the collector sensing terminal 33, which has the same potential as the first electrode 31, and the negative electrode 42 of the constant current source, and the voltage between the collector sensing terminal 34, which has the same potential as the second electrode 32, and the negative electrode 42 of the constant current source are measured. The two measured values ​​are calculated, and the calculation result is set as the saturation voltage of the semiconductor element 27.

[0115] The saturation voltage of semiconductor element 27 deviates from its true value due to the resistive component of the path from resistor 17 to the negative electrode 42 of the constant current source. However, to mitigate this deviation, the resistive component must be reduced. In embodiment 5, by having two constant current sources and two current supply points, the current flowing to the first electrode 31 is halved. This allows the voltage drop based on resistor 13 to be reduced to half.

[0116] In this embodiment, there are N constant current sources, current supply points, and collector sensing terminals. N is a natural number greater than or equal to 3.

[0117] N electrodes are arranged at equal angular intervals on the outer periphery of the test stage 51. Each of the N electrodes is connected to one of the corresponding constant current sources among the N constant current sources, functioning as N current supply points. The N collector sensing terminals are respectively positioned at a distance from their corresponding electrodes among the N electrodes that is closer to the distances between them and all other electrodes among the N electrodes.

[0118] Figure 12 This is a diagram illustrating an example of the semiconductor testing apparatus of Embodiment 5. Figure 12The case where N=4 is shown. Based on the structure of the semiconductor testing apparatus in Embodiment 4, this semiconductor testing apparatus further includes a third constant current source 101, a fourth constant current source 102, a third electrode 131, a fourth electrode 132, a collector sensing terminal 133, and a collector sensing terminal 134. Resistor 110 is the resistance of the electrical wiring between the third constant current source 101 and the third electrode 131. Resistor 111 is the resistance of the electrical wiring between the fourth constant current source 102 and the fourth electrode 132. Illustrations of the resistive components within the test stage 51 are omitted.

[0119] Electrode 31 is connected to constant current source 1. Electrode 32 is connected to constant current source 2. Electrode 131 is connected to constant current source 101. Electrode 132 is connected to constant current source 102. Electrodes 31, 31, 32, and 42 are arranged at 90° intervals on the outer periphery of the test stage 51.

[0120] Collector sensing terminal 33 is positioned closer to electrode 31 than to electrodes 32, 131, and 132. Collector sensing terminal 133 is positioned closer to electrode 131 than to electrodes 31, 32, and 132. Collector sensing terminal 34 is positioned closer to electrode 32 than to electrodes 31, 131, and 132. Collector sensing terminal 134 is positioned closer to electrode 132 than to electrodes 31, 32, and 131.

[0121] Therefore, the current flowing to the first electrode 31 becomes 1 / N, and thus the voltage drop across resistor 13 is reduced to 1 / N. Consequently, the deviation of the saturation voltage caused by resistor 13 from its true value can be reduced to 1 / N.

[0122] Implementation method 6.

[0123] Figure 13 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 6. The difference between the semiconductor testing apparatus of Embodiment 6 and the semiconductor testing apparatus of Embodiment 1 is that, in the semiconductor testing apparatus of Embodiment 6, the first electrode 31 and the second electrode 32 can move arbitrarily around the outer periphery of the test stage 51.

[0124] In the determination of the saturation voltage of semiconductor element 27, the first electrode 31 and the second electrode 32 are positioned at an angle 91 and equidistant from semiconductor element 27. The angle 91 is, for example, 30 degrees. The mechanism that allows the first electrode 31 and the second electrode 32 to move freely is, for example, a structure in which a movable probe makes electrical contact with the upper front of the test stage 51.

[0125] According to this embodiment, the difference between the values ​​of resistor 13 and resistor 14 can be reduced, thus reducing the deviation of the saturation voltage from the true value without adding additional voltage measurement points. In other words, the deviation of the in-plane measurement error of wafer 63 can be reduced.

[0126] Figure 14 This is a flowchart illustrating the steps of the saturation voltage test of the semiconductor device in Embodiment 6. The difference between the flowchart of Embodiment 6 and the flowchart of Embodiment 1 is that the flowchart of Embodiment 6 includes step S01a before step S02.

[0127] In step S01a, the first electrode 31 and the second electrode 32 move toward a position with the semiconductor element of the test subject as the vertex and at an angle 91 that is equal in distance.

[0128] Implementation method 7.

[0129] Figure 15 This is a diagram showing the structure of the semiconductor testing apparatus according to Embodiment 7. The difference between the semiconductor testing apparatus of Embodiment 7 and the semiconductor testing apparatus of Embodiment 1 is that, in Embodiment 7, the current energized by the constant current source 1 is different from the current energized by the constant current source 2.

[0130] In this embodiment, the output current of the constant current source connected to the electrode closest to the collector sensing terminal 33 among the N electrodes is less than the output current of the other constant current sources among the N constant current sources.

[0131] like Figure 15 As shown, when a current of 300A is applied to semiconductor elements 26 and 27 and the saturation voltage is measured, for example, constant current source 1 connected to electrode 31 closest to collector sensing terminal 33 outputs a current of 10A, and constant current source 2 outputs a current of 290A. The ratio of the output current of constant current source 1 to the output current of constant current source 2 is not limited to this. Since the voltage drop across resistor 13 becomes an error of the saturation voltage, the current flowing through resistor 13 is preferably infinitesimally small.

[0132] The current flowing through resistor 13 is 10A and is Figure 15 Given the wiring resistance and chuck resistance shown, the true value of the saturation voltage is 2.1V (=300A×0.007Ω), while the measured value is 2.2V (=300A×0.007Ω+10A×0.01Ω).

[0133] Since the measured value in Embodiment 1 is 3.6V, Embodiment 7 can reduce the error compared to Embodiment 1.

[0134] Figure 16This is a flowchart illustrating the steps of the saturation voltage test of the semiconductor device in Embodiment 7. The difference between the flowchart of Embodiment 7 and the flowchart of Embodiment 1 is that the flowchart of Embodiment 7 includes step S04a instead of step S04.

[0135] In step S04a, current is supplied from the semiconductor testing device. That is, the output current of the first constant current source 1 is made smaller than the output current of the second constant current source 2. For example, the first constant current source 1 outputs a current of 10A, and the second constant current source 2 outputs a current of 290A.

[0136] This disclosure allows for the combination of various embodiments within the scope of the invention, or for appropriate modifications or omissions to various embodiments.

[0137] The embodiments disclosed herein are merely illustrative in all respects and should not be considered limiting. The scope of this disclosure is set forth in the claims rather than in the foregoing description, and includes all modifications within the same meaning and scope as the claims.

[0138] Explanation of reference numerals in the attached figures

[0139] 1, 2, 101, 102 constant current sources; 3, 3a voltmeter; 10, 11, 12, 13, 14, 15, 16, 17, 110, 111 resistors; 26, 27 semiconductor components; 31, 32, 131, 132 electrodes; 33, 34, 133, 134 collector sensing terminals; 42 negative electrode; 51 test stage; 53, 54 probes; 55 drive circuit; 63 wafer; 69 computing device; 71, 72 variable resistors; 81, 82 ammeters.

Claims

1. A semiconductor testing apparatus for testing the characteristics of a semiconductor element, the semiconductor element having a positive electrode on its back side, a negative electrode and a control electrode on its front side, and being turned on or off according to a control signal input to the control electrode, wherein... The semiconductor testing apparatus includes: The test stage is used to fix a wafer on which multiple semiconductor elements are disposed, and has the function of a positive electrode electrically connected to the positive electrode of the multiple semiconductor elements. There are N constant current sources, where N is a natural number greater than 2; The first probe connects the negative terminal of the semiconductor element to the negative terminal of the constant current source; N electrodes are arranged on the outer periphery of the test stage and are respectively connected to one of the N constant current sources to function as N current supply points. A collector sensing terminal, disposed on the outer periphery of the test stage; and A voltmeter that measures the voltage between the collector sensing terminal and the negative terminal of the constant current source.

2. The semiconductor testing apparatus according to claim 1, wherein, The semiconductor testing apparatus includes a second probe that connects the control electrode of the semiconductor element to the drive circuit.

3. The semiconductor testing apparatus according to claim 1 or 2, wherein, The N electrodes are arranged at equal angular intervals on the outer periphery of the test stage.

4. The semiconductor testing apparatus according to claim 1 or 2, wherein, N=2, and the two electrodes are configured to be movable on the outer periphery.

5. The semiconductor testing apparatus according to claim 1 or 2, wherein, The semiconductor testing apparatus includes N collector sensing terminals disposed on the outer periphery of the testing stage. The distance between each of the N collector sensing terminals and its corresponding electrode among the N electrodes is less than the distance between each terminal and all other electrodes among the N electrodes. The voltmeter measures the voltage between each of the N collector sensing terminals and the negative terminal of the constant current source.

6. The semiconductor testing apparatus according to claim 5, wherein, The semiconductor testing apparatus also includes a computing device that averages the N voltages measured by the voltmeter.

7. The semiconductor testing apparatus according to claim 1 or 2, wherein, The current output from the constant current source connected to the electrode closest to the collector sensing terminal among the N electrodes is less than the current output from the other constant current sources.

8. A semiconductor testing apparatus for performing characteristic tests on a semiconductor element, the semiconductor element having a positive electrode on its back side, a negative electrode and a control electrode on its front side, and being turned on or off according to a control signal input to the control electrode, wherein... The semiconductor testing apparatus includes: The test stage is used to fix a wafer on which multiple semiconductor elements are disposed, and has the function of a positive electrode electrically connected to the positive electrode of the multiple semiconductor elements. Constant current source; The first probe connects the negative terminal of the semiconductor element to the negative terminal of the constant current source; N electrodes are arranged on the outer periphery of the test stage and connected to the constant current source to function as current supply points, where N is a natural number greater than 2. A variable resistor and a galvanometer are configured between the constant current source and each of the N electrodes; A collector sensing terminal, disposed on the outer periphery of the test stage; and A voltmeter that measures the voltage between the collector sensing terminal and the negative terminal of the constant current source.

9. The semiconductor testing apparatus according to claim 8, wherein, The resistance values ​​of the N variable resistors are adjusted such that the current flowing between the constant current source and each of the N electrodes is equal.

10. A semiconductor testing method, comprising a semiconductor testing apparatus for performing characteristic tests on a semiconductor element, wherein the semiconductor element has a positive electrode on its back side, a negative electrode and a control electrode on its front side, and is turned on or off according to a control signal input to the control electrode, wherein... The semiconductor testing apparatus comprises: a test stage serving as a positive electrode; N constant current sources, where N is a natural number greater than or equal to 2; N electrodes disposed on the outer periphery of the test stage and each connected to one of the N constant current sources, functioning as N current supply points; a collector sensing terminal disposed on the outer periphery of the test stage; a first probe; a second probe; and a voltmeter. The semiconductor testing method comprises the following steps: A wafer configured with multiple semiconductor elements is fixed on the test stage, and the positive electrodes of the multiple semiconductor elements are connected to the test stage. The negative terminal of the semiconductor element is connected to the negative terminal of the constant current source through the first probe; The control electrode of the semiconductor element is connected to the driving circuit via the second probe; The N constant current sources begin supplying constant current; as well as The voltage between the collector sensing terminal and the negative terminal of the constant current source is measured using the voltmeter.

11. The semiconductor testing method according to claim 10, wherein, The step of starting to supply constant current includes the following steps: making the current output from the constant current source connected to the electrode closest to the collector sensing terminal among the N electrodes less than the current output from the other constant current sources.

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