JP5432700B2 - Semiconductor device inspection equipment - Google Patents

Description

  The present invention relates to a semiconductor device inspection apparatus having electrodes on both sides of a substrate.

  A power semiconductor device is known as a representative example of a semiconductor device having electrodes on both sides of a substrate. As an example of a power semiconductor device, an insulated gate bipolar transistor (insulated gate bipolar transistor) abbreviated as IGBT will be described. FIG. 6A is a cross-sectional structure diagram of the IGBT. A gate terminal 10 and an emitter terminal 12 exist on one surface of the substrate, and a collector terminal 14 exists on the other surface. The collector terminal 14 is the back surface itself of the substrate. FIG. 6B is a symbol for the IGBT.

  In order to inspect the electrical characteristics of the IGBT, it is necessary to bring an inspection contact into contact with both surfaces of the substrate. FIG. 7 is a side view of a conventional inspection apparatus for inspecting an IGBT, and a part thereof is shown in cross section. This inspection apparatus inspects an IGBT formed on a wafer in a wafer state. In FIG. 7, a wafer 18 is placed on the chuck top 16. The probe 20 is brought into contact with the gate terminal and the emitter terminal on the surface of the wafer 18. The probe 20 is electrically connected to the tester 22. The collector terminal on the back surface of the wafer 18 is in electrical contact with the chuck top 16. The chuck top 16 is electrically connected to the tester 22 via a cable 24. The chuck top 16 is placed on a movable stage 28 via an insulator 26. The movable stage 28 can move in the XYZ directions and can rotate about the vertical axis. Since the movable stage 28 moves, the cable 24 connected to the movable stage 28 is routed through the cable bear 30 and then connected to the tester 22. A conventional inspection apparatus of the type shown in FIG. 7 is disclosed in, for example, Japanese Patent Laid-Open No. 5-333098 (Patent Document 1).

  In the inspection apparatus of FIG. 7, the length of the cable 24 requires about 2 m, for example. As the cable 24 becomes longer, its resistance and inductance increase, and the load increases with respect to the current flowing through the cable 24. Therefore, there is a possibility that the inspection accuracy is lowered. Further, when inspecting the dynamic characteristics of the IGBT, a high-frequency signal may be applied to the IGBT, but the output waveform of the IGBT is distorted due to the length of the cable 24. This point will be described below. FIG. 8A shows a waveform 32 of a high-frequency input pulse signal (applied to the gate terminal of the IGBT). FIG. 8B shows the waveform of the output signal of the IGBT (current flowing between the emitter terminal and the collector terminal of the IGBT). In contrast to the original output waveform 34 of the IGBT (which requires some time for the rise and fall of the signal), the actual output waveform 36 is the original waveform due to the influence of the electrical path and the like between the IGBT and the tester. It is more than 34. When the cable 24 becomes long as described above, the rounding of the waveform becomes large, and the inspection accuracy of the dynamic characteristics is remarkably lowered.

  An inspection apparatus shown in FIG. 9 is also known as another conventional example. FIG. 9 is a side view of another conventional inspection apparatus, and a part thereof is shown in cross section. In this inspection apparatus, the wafer 18 is clamped and supported at the peripheral portion without placing the wafer 18 on the chuck top. In this way, the probes 20a and 20b can be brought into contact with both the front surface and the back surface of the wafer 18. The upper and lower probes 20a, 20b and the tester 22 are connected by cables 24a, 24b. The wafer 18 can move in the XY direction (that is, in a horizontal plane), and thereby the relative positional relationship between the probes 20a and 20b and the wafer 18 can be changed. When the wafer 18 is moved, the probes 20a and 20b are retracted in the vertical direction. In this type of inspection apparatus, since the cable is not connected to the movable chuck top, the length of the cable is shorter than that of the conventional example of FIG. A conventional inspection apparatus of the type shown in FIG. 9 is disclosed in, for example, Japanese Patent Laying-Open No. 2005-303098 (Patent Document 2).

  Since the inspection apparatus shown in FIG. 9 moves the wafer by clamping the peripheral portion of the wafer, the wafer moving mechanism becomes more complicated than the conventional apparatus shown in FIG. Further, since it is difficult to control the temperature of the wafer, it is not suitable for an inspection in which the wafer is heated to a high temperature or a low temperature.

  As another conventional example, an inspection apparatus shown in FIG. 10 is also known. FIG. 10 is a side view of still another conventional inspection apparatus, and the chuck top is shown in cross section. This inspection apparatus inspects the IGBT after being divided into chips, not in a wafer state. This type of conventional inspection apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-101944 (Patent Document 3) and Japanese Patent Application Laid-Open No. 2007-40926 (Patent Document 4). According to Patent Document 3, it is explained that when an electric circuit is connected to a tester via a chuck top as shown in the conventional example of FIG. 7, the electric circuit becomes complicated and inspection cannot be performed properly. In order to solve this problem, a metal film for mounting a chip is arranged on a ceramic chuck top. This metal film is in contact with the collector terminal on the back surface of the IGBT chip, and the surface of this metal film and the tester are electrically connected to form an electric circuit with a small load. A similar structure is also disclosed in Patent Document 4, and FIG. 10 shows the structure disclosed in Patent Document 4. In FIG. 10, the ceramic chuck top 38 is provided with a plurality of conductive portions 40. An IGBT chip 42 is placed on the conductive portion 40. The probe 20 is brought into contact with the gate terminal and the emitter terminal on the surface of the chip 42. The collector terminal on the back surface of the chip 42 is in contact with the conductive portion 40. The pogo pin 44 is brought into contact with the surface of the conductive portion 40 outside the chip 42. By using such a contact structure, the IGBT can be measured with a high voltage and a large current. The pogo pin 44 cannot take a large current value per one, but a large current can be measured by increasing the number of pogo pins 44.

JP-A-5-333098 JP 2005-303098 A JP 2008-101944 A JP 2007-40926 A

  The conventional apparatus shown in FIG. 10 is considered to have a shorter electrical path between the IGBT collector terminal and the tester than the conventional apparatus shown in FIG. However, the conventional apparatus shown in FIG. 10 inspects a semiconductor device after being divided into chips, and is not suitable for inspecting a semiconductor device in a wafer state as it is. Considering that the method of FIG. 10 is applied to the inspection of semiconductor devices on a wafer, there are the following problems. For example, when a semiconductor device existing near the center of the wafer is to be inspected, the vicinity of the center of the wafer is positioned below the probe 20 (the chuck top is moved like that). On the other hand, it is necessary to bring pogo pins into contact with the conductive portions exposed to the outside of the wafer. Therefore, the probe 20 and the pogo pin 44 are far away from each other. In general, the alignment of the electrode of the semiconductor device on the wafer and the probe is performed by the movement of the chuck top on which the wafer is placed, but the pogo pin cannot be aligned only by this movement. This is because the positional relationship between the probe and the pogo pin changes each time depending on the position of the semiconductor device on the wafer. Therefore, it is necessary to newly provide a moving mechanism for aligning the pogo pins on the probe base side. After all, in order to apply the method of FIG. 10 to a semiconductor device on a wafer, the inspection apparatus must be changed greatly and complicatedly, and such a change is not realistic.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to replace a semiconductor device having electrodes on both sides of a substrate with a large substrate in a state where a plurality of semiconductor devices are formed. An object of the present invention is to provide an inspection apparatus capable of accurately inspecting the electrical characteristics (for example, as a wafer). Another object of the present invention is to provide an inspection apparatus capable of accurately inspecting dynamic characteristics of a power semiconductor device.

  The inspection apparatus of the present invention inspects the electrical characteristics of a semiconductor device having electrodes on both sides of a substrate, and has the following configuration. (A) A probe capable of contacting an electrode present on the first surface of the substrate. (A) A chuck top for supporting the substrate, comprising a conductive flat support surface capable of contacting an electrode existing on a second surface opposite to the first surface of the substrate. (C) A drive mechanism that changes the relative positional relationship between the chuck top and the probe in a two-dimensional direction in a plane parallel to the support surface and in a direction perpendicular to the support surface. (D) A conductive chuck lead plate that is separated from the support surface and faces parallel to the support surface, and has a larger outer dimension than the outer dimension of the support surface. (E) a contact that is fixed to the chuck top and is electrically connected to the support surface, the tip of which protrudes toward the chuck lead plate rather than the height of the support surface; A contactor whose tip can contact the chuck lead plate when a relative positional relationship between the chuck top and the chuck lead plate changes in a direction perpendicular to the support surface. (F) A first electrical path for electrically connecting the probe and the tester. (G) A second electrical path for electrically connecting the support surface and the tester via the contact and the chuck lead plate.

  The contacts can be preferably arranged as a contact group consisting of a plurality of contacts close to each other, and the contact groups can be arranged at equal intervals in the circumferential direction at the periphery of the chuck top. .

  The probe is supported by a probe base, and the chuck lead plate is preferably fixed to the probe base via an electrical insulator.

  The present invention is particularly suitable for inspection of dynamic characteristics of a power semiconductor device (for example, inspection at a high voltage and a large current). The power semiconductor device is, for example, an IGBT or a power MOSFET. In the case of the power MOSFET, the one having the drain electrode on the back surface of the substrate becomes the inspection object of the inspection apparatus of the present invention.

  The present invention includes a chuck lead plate facing the support surface of the chuck top, and an electrical path between the electrode on the back side of the substrate of the semiconductor device and the tester, a contact provided on the chuck top, a chuck lead plate, With this configuration, the electrical path between the electrode on the back side of the substrate of the semiconductor device and the tester is shortened as compared with the conventional apparatus, and a highly accurate inspection is possible. Therefore, compared with the conventional apparatus, for example, the rounding of the output waveform is reduced in the dynamic characteristic inspection of the power semiconductor device.

FIG. 1 is a side view of an embodiment of an inspection apparatus according to the present invention. FIG. 2 is a plan view of the chuck top. FIG. 3 is a plan view of the chuck lead plate. FIG. 4 is a plan view showing the relative positional relationship between the chuck lead plate and the chuck top. FIG. 5 is an example of an electric circuit when inspecting an IGBT using the inspection apparatus of the present invention. FIG. 6 is a cross-sectional structure diagram and a symbol of the IGBT. FIG. 7 is a side view of a conventional inspection apparatus. FIG. 8 shows the input waveform and output waveform of the IGBT. FIG. 9 is a side view of another conventional inspection apparatus. FIG. 10 is a side view of still another conventional inspection apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view of an embodiment of an inspection apparatus according to the present invention, and a part thereof is shown in cross section. This inspection device is roughly divided into an upper device 46 that is always stationary with respect to the space and a lower device 48 that is movable with respect to the space, and the tester 22 is connected to the upper device 46. The upper device 46 includes a probe base 50. The probe 20 is attached to the probe base 50 through some adjustment mechanisms. A conductive chuck lead plate 54 is fixed to the lower surface of the probe base 50 via a ceramic support 52. The support 52 is an electrical insulator. The chuck lead plate 54 is obtained by applying gold plating (or nickel plating or rhodium plating) to the surface of an aluminum or copper disc having a thickness of 5 mm.

  The lower device 48 includes a chuck top 49. The chuck top 49 is obtained by applying gold plating to the surface of a copper disk having a thickness of 10 to 15 mm. A wafer 18 to be inspected can be placed on the upper surface of the chuck top 49. The upper surface of the chuck top 49 is a support surface 56 that supports the wafer 18, and this support surface 56 corresponds to a conductive flat support surface in the present invention. The chuck top 49 is placed on the movable stage 28 via a ceramic insulator 26. The movable stage 28 is movable in the left-right direction (X direction) in the drawing, the front-rear direction (Y direction) perpendicular to the paper surface, and the up-down direction (Z direction) in the drawing. The movable stage 28 can be rotated (θ rotation) around a rotation center line extending in the Z direction. The XY direction corresponds to a two-dimensional direction in a plane parallel to the support surface 56 of the chuck top 49, and the Z direction corresponds to a direction perpendicular to the support surface 56. Such a structure of the movable stage 28 is well known in an inspection apparatus such as a wafer prober, and a detailed description thereof will be omitted. The movable stage 28 is a “driving mechanism that changes the relative positional relationship between the chuck top and the probe in a two-dimensional direction in a plane parallel to the support surface of the chuck top and a direction perpendicular to the support surface” in the present invention. Applicable. Instead of moving the chuck top using the movable stage, the relative positional relationship between the chuck top and the probe can be changed by moving the probe base in the same manner with the chuck top stationary.

  A conductive pogo pin base 58 is fixed to the periphery (side surface in this embodiment) of the chuck top 49. A plurality of pogo pins 60 are fixed to the pogo pin base 58. The pogo pin 60 is electrically connected to the chuck top 49 via the pogo pin base 58. The pogo pin 60 protrudes above the height of the support surface 56 of the chuck top 49, and its tip is spring-biased upward. The pogo pin 60 can be retracted by pushing its tip downward. The pogo pin 60 corresponds to the contact in the present invention. At the same time that the chuck top 49 rises and the wafer 18 and the probe 20 come into contact, the pogo pins 60 and the chuck lead plate 54 come into contact.

  The probe 20 is electrically connected to the tester 22 via an electrical path in the upper device 46 and the first cable 47. The electrical path between the probe 20 and the tester 22 is the first electrical path in the present invention. On the other hand, the support surface 56 of the chuck top 49 is electrically connected to the tester 22 via the chuck top 49, the pogo pin base 58, the pogo pin 60, the chuck lead plate 54, and the second cable 55. The electrical path between the support surface 56 of the chuck top 49 and the tester 22 is the second electrical path in the present invention. The first electrical path is usually composed of a plurality of signal lines. Taking the IGBT inspection as an example, the first electrical path includes at least a signal line connected to the gate terminal and a signal line connected to the emitter terminal. The second electrical path is usually a single signal line. Taking the IGBT inspection as an example, the second electric path is constituted by a signal line connected to the collector terminal. In addition, when adopting a driving method in which the chuck top 49 is stationary in the X and Y directions and the probe base 50 is moved in the X and Y directions, the first cable 47 and the second cable can be obtained by mounting the tester 22 on the probe base 50. 55 is not long.

  By adopting the structure shown in FIG. 1, the length of the electrical path connecting the terminal on the back surface of the wafer and the tester is dramatically shortened compared with the conventional apparatus shown in FIG. 7 without greatly changing the structure of the prober. be able to. Further, since the wafer 18 is placed on the chuck top 49, it is easy to heat or cool the wafer 18 using the chuck top 49.

  FIG. 2 is a plan view of the chuck top. Four pogo pin bases 58 are fixed to the side surface of the chuck top 49 at equal intervals in the circumferential direction. Six pogo pins 60 are fixed to each pogo pin base 58. The six pogo pins 60 close to each other constitute a pogo pin group, and four sets of the pogo pin group are provided. By increasing the number of pogo pins 60, a large current can flow even via pogo pins.

  In FIG. 2, in order to compare the size with the chuck top 49, the chuck lead plate 54 and the wafer 18 are indicated by imaginary lines. The outer diameter of the wafer 18 is, for example, 150 mm. In this case, the outer diameter of the chuck top 49 is about 160 mm, and the outer diameter of the chuck lead plate 54 is about 300 mm.

  FIG. 3 is a plan view of the chuck lead plate 54. In the center of the chuck lead plate 54, a circular opening 62 through which the probe 20 passes is formed. The connector 63 on the chuck lead plate 54 is for connecting a cable connecting the chuck lead plate 54 and the tester. The chuck top 49 and the wafer 18 are indicated by imaginary lines. FIG. 3 shows a state in which the chuck top 49 is drawn in a state of moving in the right direction of the drawing, and a semiconductor device near the left end of the wafer 18 on the chuck top 49 is inspected. The type and number of the probes 20 vary depending on the inspection item. For example, one probe is used for the gate terminal of the IGBT and a plurality of probes (for generating current) are prepared for the emitter terminal.

  FIG. 4 is a plan view showing the relative positional relationship between the chuck lead plate 54 and the chuck top 49. The chuck top 49 is indicated by an imaginary line. As for what is drawn with the chuck top 49 moved to the right side, the wafer 18 on it is also indicated by an imaginary line. The chuck lead plate 54 is stationary with respect to the space, but the chuck top 49 moves in the XY direction depending on where the semiconductor device to be inspected is located on the wafer 18. That is, the chuck top 49 moves so that the semiconductor device to be inspected is located below the opening 62 of the chuck lead plate 54. The outer dimensions of the chuck lead plate 54 are considerably larger than the outer dimensions of the chuck top 49 so that the pogo pins fixed to the periphery of the chuck top 49 can reliably contact the chuck lead plate 54 even if the chuck top 49 moves. It has become.

  What can be suitably inspected by the inspection apparatus of the present invention includes, for example, switching characteristics of a power semiconductor device, reverse recovery time (Trr) of the diode, L load test, and the like. FIG. 5 is an example of an electric circuit when inspecting an IGBT using the inspection apparatus of the present invention. A signal line 66 is provided between the gate terminal G of the IGBT 64 and the tester 22, and a signal line 68 is provided between the emitter terminal E and the tester 22. The two signal lines 66 and 68 correspond to the first electric path in the present invention. There is a signal line 70 between the collector terminal C of the IGBT 64 and the tester 22. This signal line 70 corresponds to the second electric path in the present invention. The input signal source 72, the power source 74, the load 76, and the voltmeter 78 are inside the tester 22. When a high-frequency pulse signal is applied from the input signal source 72 between the gate terminal G and the emitter terminal E, the collector and the emitter are brought into conduction, a current flows through the load 76, and the voltage generated at both ends of the load 76 at that time is a voltage. Measure with a total of 78. The dynamic characteristics of the IGBT 64 can be evaluated by examining the output waveform measured by the voltmeter 78 with respect to the input high frequency pulse signal.

DESCRIPTION OF SYMBOLS 10 Gate terminal 12 Emitter terminal 14 Collector terminal 16 Chuck top 18 Wafer 20, 20a, 20b Probe 22 Tester 24, 24a, 24b Cable 26 Insulator 28 Movable stage 30 Cable bear 32 Input waveform 34 Original output waveform 36 Actual output waveform 38 Ceramic chuck top 40 Conductive portion 42 Tip 44 Pogo pin 46 Upper device 47 First cable 48 Lower device 49 Chuck top 50 Probe base 52 Support 54 Chuck lead plate 55 Second cable 56 Support surface 58 Pogo pin base 60 Pogo pin 62 Opening 63 Connector 64 IGBT
66, 68, 70 Signal line 72 Input signal source 74 Power supply 76 Load 78 Voltmeter

Claims (3)

An inspection apparatus for inspecting electrical characteristics of a semiconductor device having electrodes on both sides of a substrate, the inspection apparatus having the following configuration.
(A) A probe capable of contacting an electrode present on the first surface of the substrate.
(A) A chuck top for supporting the substrate, comprising a conductive flat support surface capable of contacting an electrode existing on a second surface opposite to the first surface of the substrate.
(C) A drive mechanism that changes the relative positional relationship between the chuck top and the probe in a two-dimensional direction in a plane parallel to the support surface and in a direction perpendicular to the support surface.
(D) A conductive chuck lead plate that is separated from the support surface and faces parallel to the support surface, and has a larger outer dimension than the outer dimension of the support surface.
(E) a contact that is fixed to the chuck top and is electrically connected to the support surface, the tip of which protrudes toward the chuck lead plate rather than the height of the support surface; A contactor whose tip can contact the chuck lead plate when a relative positional relationship between the chuck top and the chuck lead plate changes in a direction perpendicular to the support surface.
(F) A first electrical path for electrically connecting the probe and the tester.
(G) A second electrical path for electrically connecting the support surface and the tester via the contact and the chuck lead plate.   The inspection apparatus according to claim 1, wherein the contacts are arranged as a contact group composed of a plurality of contacts that are close to each other, and the contact groups are arranged at equal intervals in the circumferential direction at the periphery of the chuck top. Inspection apparatus characterized by being arranged.   3. The inspection apparatus according to claim 1, wherein the probe is supported by a probe base, and the chuck lead plate is fixed to the probe base via an electrical insulator.

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