JP2014139965A - Withstanding voltage measurement device and withstanding voltage measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a withstanding voltage measurement device which sufficiently prevents creeping discharge from a probe with a simple method.SOLUTION: A withstanding voltage measurement device 100 is used for measuring a withstanding voltage of a semiconductor element which is formed at a semiconductor substrate 200 and has an electrode part. A stage 120 is provided in an airtight container 110 and is used for supporting the semiconductor substrate 200. The probe 130 is provided in the airtight container 110, is formed so as to move relative to the stage 120, and contacts with the electrode part thereby obtaining electric connection with the electrode part. An introduction part 140 is provided at the airtight container 110 and is used for introducing a gas into the airtight container 110. A discharge part 150 is provided at the airtight container 110 and is used for discharging the gas from the airtight container 110.

Description

  The present invention relates to a withstand voltage measuring apparatus and a withstand voltage measuring method, and more particularly to a withstand voltage measuring apparatus and a withstand voltage measuring method for measuring the withstand voltage of a semiconductor element formed on a semiconductor substrate.

  The breakdown voltage is one of important characteristics for a semiconductor device, particularly a power semiconductor device. Therefore, in the semiconductor device manufacturing method, the breakdown voltage of the semiconductor element formed on the semiconductor substrate may be measured. When the conditions of the withstand voltage measurement are inappropriate, the semiconductor element may be destroyed by the occurrence of creeping discharge from the measurement probe on the semiconductor substrate. Therefore, it is required to prevent such discharge. JP-A-5-322961 discloses a method in which an inert liquid such as Fluorinert (trademark) or an inert gas is placed in a test tank having an open side where a probe is disposed.

JP-A-5-322961

  When an inert liquid is used in the technique described in the above publication, the handling of the inert liquid is complicated. For example, it may be necessary to replenish the evaporated liquid, prevent liquid spillage during transportation of the semiconductor substrate, and remove the inert liquid from the semiconductor substrate after the pressure resistance measurement.

  When an inert gas is used in the technique described in the above publication, there is a problem due to the open portion of the test tank. For example, the occurrence of creeping discharge may not be sufficiently prevented due to the mixing of water vapor into the test tank. In addition, there is a problem that it is necessary to pay attention to the influence on the working environment due to leakage of the inert gas outside the test tank.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to sufficiently prevent creeping discharge from a probe at the time of withstand voltage measurement by a simple method.

  The breakdown voltage measuring apparatus of the present invention is for measuring the breakdown voltage of a semiconductor element. The semiconductor element is formed on a semiconductor substrate and has an electrode part. The pressure-resistant measuring device has an airtight container, a stage, a probe, an introduction port, and a discharge port. The stage is provided in an airtight container and supports the semiconductor substrate. The probe is for obtaining an electrical connection with the electrode part by contacting the electrode part. The probe is provided in the airtight container and is configured to be movable relative to the stage. The introduction port is for introducing gas into the hermetic container and is provided in the hermetic container. The discharge port is for discharging gas from the hermetic container and is provided in the hermetic container.

  According to this pressure | voltage resistant measuring apparatus, the atmosphere in an airtight container can be adjusted by gas replacement using an inlet and an outlet. Thereby, the atmosphere around the probe can be easily and sufficiently managed. Therefore, creeping discharge from the probe can be sufficiently prevented by a simple method.

  The said pressure | voltage resistant measuring apparatus may have a heating part for heating a semiconductor substrate. Water can be removed from the semiconductor substrate by heating by the heating unit. Therefore, creeping discharge can be prevented more reliably.

  The said pressure | voltage resistant measuring apparatus may have a detection part for detecting the dew point temperature in an airtight container. By using the detection unit, it is possible to manage more reliably so that the amount of moisture on the semiconductor substrate does not become excessively large. Therefore, creeping discharge can be prevented more reliably.

  In the pressure-resistant measuring device, each of the introduction port and the discharge port may have a valve. By closing the valve after the gas replacement in the airtight container is performed, it is possible to prevent the outside air from flowing into the airtight container after the gas replacement. Therefore, creeping discharge can be prevented even in a state where gas replacement is stopped.

  The said pressure | voltage resistant measuring apparatus may have a voltage source which can be connected to a probe and can generate the voltage of 600V or more. Thereby, a high voltage of 600 V or more can be used for the withstand voltage measurement. Even when such a high voltage is used, creeping discharge is sufficiently prevented according to the pressure resistance measuring device.

  In the pressure-resistant measuring device, the hermetic container may have a window that transmits light so that the position of the semiconductor element can be observed from the outside of the hermetic container. Accordingly, the position of the semiconductor element can be observed from the outside of the hermetic container while maintaining the hermeticity of the hermetic container.

  The withstand voltage measuring method of the present invention is for measuring the withstand voltage of a semiconductor element. The semiconductor element is formed on a semiconductor substrate and has an electrode part. The breakdown voltage measuring method includes the following steps. A semiconductor substrate is supported in the hermetic container. Next, a voltage is supplied to the probe while the probe is brought into contact with the electrode portion.

  According to the pressure resistance measuring method, the atmosphere around the probe can be easily and sufficiently managed by using the airtight container. Therefore, creeping discharge from the probe can be sufficiently prevented by a simple method.

  In the breakdown voltage measurement method, the semiconductor substrate may be heated after the step of supporting the semiconductor substrate and before the step of supplying a voltage to the probe. Thereby, moisture is removed from the semiconductor substrate by heating. Therefore, creeping discharge can be prevented more reliably.

  In the pressure resistance measuring method, after the step of supporting the semiconductor substrate, an inert gas is introduced into the hermetic container from the inlet provided in the hermetic container, and the gas in the hermetic container from the outlet provided in the hermetic container. By discharging the gas, the atmosphere in the hermetic container may be an inert gas atmosphere. The dew point temperature in the hermetic container is detected, and according to the result, the space between each of the inlet and the outlet and the hermetic container may be closed. Thereby, the gas replacement in the hermetic container can be stopped while preventing the outside air from flowing into the hermetic container. Therefore, creeping discharge can be prevented even in a state where gas replacement is stopped.

  In the above withstand voltage measuring method, heating of the semiconductor substrate may be started after the step of supporting the semiconductor substrate and before the step of supplying a voltage to the probe. The heating of the semiconductor substrate may be stopped after the step of setting the atmosphere in the hermetic container to an inert gas atmosphere and before the step of detecting the dew point temperature in the hermetic container. Thereby, when the pressure | voltage resistance measurement is performed after the moisture removal by heating is completed, it can manage more reliably so that the moisture content on a semiconductor substrate may not become large too much. Therefore, creeping discharge can be prevented more reliably.

  As described above, according to the present invention, creeping discharge from the probe can be sufficiently prevented by a simple method.

It is sectional drawing which shows schematically the structure of the pressure | voltage resistant measuring apparatus in Embodiment 1 of this invention. It is a top view which shows the example of a structure of the semiconductor substrate in which the semiconductor element was formed. It is a fragmentary sectional view showing an example of composition of a semiconductor substrate in which a semiconductor element was formed. It is a flowchart of the pressure | voltage resistant measuring method in Embodiment 1 of this invention. It is a fragmentary sectional view which shows roughly one process of the pressure | voltage resistant measuring method in Embodiment 1 of this invention. It is a figure which shows the modification of the process shown in FIG. It is a fragmentary sectional view which shows roughly 1 process of the pressure | voltage resistant measuring method in Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
As shown in FIG. 1, the withstand voltage measuring apparatus 100 is for measuring the withstand voltage of a semiconductor element formed on a wafer 200 (semiconductor substrate). As shown in FIGS. 2 and 3, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) element 210 (semiconductor element) formed on the wafer 200 includes a drain electrode 221, a source electrode 222 (electrode part), and a gate electrode 223. And have.

  The pressure resistance measuring apparatus 100 (FIG. 1) includes an airtight container 110, a camera 112, a stage 120, a probe 130, a voltage source 134, a gate control unit 135, an introduction port 140 (introduction unit), and a discharge port 150. (Discharge port), heater 160 (heating unit), and sensor 170 (detection unit).

  Here, the “airtight container” is a container having at least airtightness that can control the dew point temperature independently from the outside. Therefore, the airtightness that the vacuum vessel has is not always necessary. In other words, strict airtightness that can substantially prevent leakage even under a large pressure difference of about atmospheric pressure is not always necessary. On the other hand, in the absence of such a pressure difference, airtightness that prevents easy passage of airflow between the inside and outside of the container is necessary. For example, it has airtightness equivalent to or higher than that of a general desiccator. It is desirable. The material of the hermetic container is preferably a metal or a resin, such as stainless steel or an acrylic resin.

  The stage 120 is provided in the hermetic container 110 and is for supporting the wafer 200. The stage may have a vacuum chuck 121 for fixing the wafer 200.

  The probe 130 is provided in the airtight container 110. One of the functions of the probe 130 is to obtain an electrical connection with the source electrode 222 by contacting the source electrode 222. The probe 130 may have a base 131 and needles 132 and 133, for example. Each of the needles 132 and 133 is for obtaining an electrical connection with the source electrode 222 and the gate electrode 223, and is attached to the base 131.

  In the present embodiment, the stage 120 is provided on the moving mechanism 122 so as to be movable in the airtight container 110. Accordingly, the stage 120 and the probe 130 are configured to be relatively displaceable. In other words, the probe 130 is configured to be movable relative to the stage 120. The moving mechanism 122 is preferably a so-called XYZ stage that enables three-dimensional displacement.

  The inlet 140 is provided in the hermetic container 110 and is used for introducing gas into the hermetic container 110. The discharge port 150 is provided in the hermetic container 110 and is for discharging gas from the hermetic container 110. Each of the inlet 140 and the outlet 150 has gate valves 141 and 151.

  The heater 160 is for heating the wafer 200. The heater 160 is disposed in the hermetic container 110 and may be disposed in the stage 120. A heater power supply 161 disposed outside the hermetic container 110 may be connected to the heater 160.

  The sensor 170 is provided in the hermetic container 110 in order to detect the dew point temperature in the hermetic container 110. The sensor 170 may be a dew point thermometer designed specifically for direct measurement of the dew point temperature, or has a thermometer and a hygrometer to calculate the dew point temperature from the temperature and humidity. May be. The sensor 170 may be connected to a reading unit 171 provided outside the hermetic container 110.

  The voltage source 134 is connected to the probe 130. Specifically, the voltage source 134 is connected to apply a voltage between the needle 132 of the probe 130 and the stage 120. The voltage that can be generated by the voltage source 134 is preferably about 600 V or more, more preferably about 1 kV or more, and further preferably about 3 kV or more.

  The gate control unit 135 is connected to apply a voltage between the needles 132 and 133 of the probe 130. The gate controller 135 only needs to be capable of generating a voltage that can control the gate voltage of the MOSFET element 210. The gate controller 135 can be omitted when gate voltage control is not required as in a diode.

  The hermetic container 110 has a window 111 that transmits light so that the position of the MOSFET element 210 can be observed from the outside of the hermetic container 110. The window 111 is made of a material that transmits light to a sufficient extent for this purpose, for example, glass or transparent resin. The window 111 is preferably provided with a light shielding portion (not shown) for performing light shielding so that light does not enter through the window 111 during pressure resistance measurement. This light-shielding portion is, for example, a cover that can be attached and detached outside the window 111 or a shutter provided outside or inside the window 111. The camera 112 is arranged so that the wafer 200 can be observed through the window 111 as indicated by a broken line in FIG. The camera may be provided in the airtight container 110, and in this case, the window 111 is not necessary.

Next, a breakdown voltage measuring method using the breakdown voltage measuring apparatus 100 (FIG. 1) will be described.
The wafer 200 is supported in the hermetic container 110 (FIG. 4: Step S11). Specifically, the wafer 200 is carried into the hermetic container 110 and further placed on the stage 120. As a result, the potential of the drain electrode 221 located on the back surface of the wafer 200 becomes the potential of the stage 120. Further, the wafer 200 is fixed to the stage 120. This fixing can be performed by the vacuum chuck 121.

  Next, when the moving mechanism 122 is driven, a relative displacement between the stage 120 and the probe 130 occurs, so that the needles 132 and 133 are brought into contact with the source electrode 222 and the gate electrode 223, respectively, as shown in FIG. . In this way, a voltage is supplied to the probe 130 while the probe 130 is in contact with the source electrode 222 (FIG. 4: step S17). Specifically, a voltage is supplied between the needle 132 of the probe 130 and the stage 120. As a result, a voltage for measuring the withstand voltage is applied between the drain electrode 221 and the source electrode 222 of the MOSFET element 210. This voltage is about 600V or more, for example. Further, the gate voltage is adjusted by the gate controller 135 as necessary. Thereby, the breakdown voltage of the MOSFET element 210 is measured.

  In the above method, the wafer 200 may be heated after the step of supporting the wafer 200 (FIG. 4: step S11) and before the step of supplying voltage to the probe 130 (FIG. 4: step S17) (see FIG. 4). FIG. 4: Step S12). The lower limit of the heating temperature of the wafer 200 is preferably about 50 ° C. or higher, and more preferably about 100 ° C. or higher. The upper limit of the heating temperature of the wafer 200 is preferably about 200 ° C. or less, more preferably about 150 ° C. or less.

In the above method, after the step of supporting the wafer 200 (FIG. 4: step S11), an inert gas is introduced into the hermetic container 110 from the inlet 140 provided in the hermetic container 110, and is provided in the hermetic container 110. By discharging the gas in the airtight container 110 from the exhaust port 150, the atmosphere in the airtight container 110 may be changed to an inert gas atmosphere (FIG. 4: step S13). The inert gas is, for example, N ₂ gas, SF ₆ gas, or a rare gas. Ar gas is particularly suitable as the rare gas.

  In the above method, the dew point temperature in the airtight container 110 may be detected (FIG. 4: step S15). Then, depending on the result of the step of detecting the dew point temperature, that is, the detected dew point temperature, the space between the inlet 140 and the outlet 150 and the airtight container 110 may be closed by the gate valves 141 and 151 (FIG. 4: Step S16). Specifically, the gate valves 141 and 151 may be closed when the dew point temperature becomes equal to or lower than a predetermined temperature. The lower limit of the predetermined dew point temperature is preferably about −150 ° C. or more, more preferably about −100 ° C. or more. The upper limit of the predetermined dew point temperature is preferably about 0 ° C. or less, more preferably about −20 ° C. or less.

  In the above method, even if heating of the wafer 200 is started after the step of supporting the wafer 200 (FIG. 4: step S11) and before the step of supplying voltage to the probe 130 (FIG. 4: step S17). Good (FIG. 4: step S12). And after the process (FIG. 4: step S13) which makes the atmosphere in the airtight container 110 an inert gas atmosphere, and before the process (FIG. 4: step S15) which detects the dew point temperature in the airtight container 110, The heating of the wafer 200 may be stopped (FIG. 4: step S14).

  According to the pressure resistance measuring apparatus 100 of the present embodiment, the atmosphere in the airtight container 110 can be adjusted by gas replacement using the inlet 140 and the outlet 150. Thereby, the atmosphere around the probe 130 can be managed easily and sufficiently. Therefore, creeping discharge from the probe 130 can be sufficiently prevented by a simple method.

  Water can be removed from the wafer 200 by heating with the heater 160. Therefore, creeping discharge can be prevented more reliably.

  Using the sensor 170, it is possible to more reliably manage the amount of moisture on the wafer 200 so as not to become excessively large. Therefore, creeping discharge can be prevented more reliably.

  By closing the gate valves 141 and 151 after the gas replacement in the hermetic container 110 is performed, it is possible to prevent the outside air from flowing into the hermetic container 110 after the gas replacement. Therefore, creeping discharge can be prevented even in a state where gas replacement is stopped.

  Even if the voltage source 134 can generate a voltage of about 600 V or higher, the creeping measurement apparatus 100 can sufficiently prevent creeping discharge. This voltage can be 1 kV or more, and can be about 3 kV or more.

  With the window 111, the position of the MOSFET element 210 can be observed from the outside of the hermetic container 110 while maintaining the hermeticity of the hermetic container 110.

  According to the pressure resistance measuring method of the present embodiment, the atmosphere around the probe 130 can be easily and sufficiently managed by using the airtight container 110. Therefore, creeping discharge from the probe 130 can be sufficiently prevented by a simple method.

  After the step of supporting the wafer 200 (FIG. 4: step S11) and before the step of supplying voltage to the probe 130 (FIG. 4: step S17), the wafer 200 may be heated (FIG. 4: step). S12). Thereby, moisture is removed from the wafer 200 by heating. Therefore, creeping discharge can be prevented more reliably.

  After the step of supporting the wafer 200 (FIG. 4: step S11), the atmosphere in the hermetic container 110 may be an inert gas atmosphere (FIG. 4: step S13). The dew point temperature in the airtight container 110 may be detected (FIG. 4: step S15), and the space between each of the inlet 140 and the outlet 150 and the airtight container 110 may be closed according to this result ( FIG. 4: Step S16). Thereby, the gas replacement in the airtight container 110 can be stopped while preventing the outside air from flowing into the airtight container 110. Therefore, creeping discharge can be prevented even in a state where gas replacement is stopped.

  After the step of supporting the wafer 200 (FIG. 4: step S11) and before the step of supplying voltage to the probe 130 (FIG. 4: step S17), heating of the wafer 200 may be started (FIG. 4). : Step S12). After the step of changing the atmosphere in the hermetic container 110 to an inert gas atmosphere (FIG. 4: step S13) and before the step of detecting the dew point temperature in the hermetic container 110 (FIG. 4: step S15), the wafer 200 The heating may be stopped (FIG. 4: step S14). Thereby, when the pressure resistance measurement is performed after the moisture removal by heating is completed, the moisture amount on the wafer 200 can be managed more reliably so as not to become excessively large. Therefore, creeping discharge can be prevented more reliably.

  The needles 132 and 133 of the probe 130 (FIG. 5) extend in the thickness direction of the wafer 200. Thereby, each of the needles 132 and 133 can be brought into contact with the source electrode 222 and the gate electrode 223 with a strong force. Therefore, the electrical connection of the probe 130 becomes more reliable. A probe 130V (FIG. 6) may be used instead of the probe 130. The needles 132 </ b> V and 133 </ b> V included in the probe 130 </ b> V extend in a direction inclined with respect to the thickness direction of the wafer 200. Thereby, each of the needles 132V and 133V can be brought into contact with the source electrode 222 and the gate electrode 223 without applying excessive force. Therefore, the occurrence of damage to the source electrode 222 and the gate electrode 223 due to the contact of the probe 130 can be suppressed.

(Embodiment 2)
Although the present embodiment has substantially the same configuration as that of the first embodiment, the wafer 200 is not placed directly on the stage 120, but instead the tray 301 containing the wafer 200 is placed. Even in this case, substantially the same effect as in the first embodiment can be obtained. When the electrical connection with the back surface side (the lower surface side in FIG. 7) of the wafer 200 is required in the withstand voltage measurement, the tray 301 is preferably made of a conductor so that the electrical connection can be made through the tray 301. . In order to suppress creeping discharge more reliably, an inert liquid 302 may be placed in the tray 301 so that the surface of the wafer 200 is covered.

(Appendix)
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  For example, the semiconductor element is not limited to a MOSFET but may be a MISFET (Metal Insulator Semiconductor Field Effect Transistor) element. The semiconductor element may be a transistor element other than a MISFET element, for example, a JFET (Junction Field Effect Transistor) element or an IGBT (Insulated Gate Bipolar Transistor) element. The semiconductor element is not limited to a transistor element, and may be a diode element, for example. The semiconductor element is not limited to an element having a single function such as a transistor function or a diode function, and may be a module having a plurality of functions. Depending on the type of semiconductor element, the electrode portion corresponds to an electrode other than the source electrode.

  The semiconductor element is not limited to a vertical element having a pair of main electrodes to which different potentials are applied by a voltage source on the upper and lower surfaces of the semiconductor substrate. That is, the semiconductor element may be a lateral element having both a pair of main electrodes on one surface of the semiconductor substrate. In this case, a voltage for measuring the withstand voltage can be applied between the pair of main electrodes only by the probe without passing through the stage.

  100 pressure-resistant measuring device, 110 airtight container, 111 window, 112 camera, 120 stage, 121 vacuum chuck, 122 moving mechanism, 130, 130V probe, 131 base, 132, 132V needle, 134 voltage source, 135 gate control unit, 140 introduction Port (introduction section), 141, 151 Gate valve (valve), 150 Discharge port (discharge section), 160 Heater (heating section), 161 Heater power supply, 170 Sensor (detection section), 171 Reading section, 200 Wafer (semiconductor substrate) ), 210 MOSFET element (semiconductor element), 221 drain electrode, 222 source electrode (electrode part), 223 gate electrode, 301 tray, 302 inert liquid.

Claims (10)

A breakdown voltage measuring device for measuring the breakdown voltage of a semiconductor element formed on a semiconductor substrate and having an electrode part,
An airtight container,
A stage provided in the hermetic container for supporting the semiconductor substrate;
A probe provided in the hermetic container and configured to move relative to the stage, for obtaining an electrical connection with the electrode unit by contacting the electrode unit;
An introduction part for introducing gas into the hermetic container, provided in the hermetic container;
A pressure-resistant measuring device, comprising: a discharge unit provided in the hermetic container for discharging gas from the hermetic container.   The pressure | voltage resistant measuring apparatus of Claim 1 further provided with the heating part for heating the said semiconductor substrate.   The pressure | voltage resistant measuring apparatus of Claim 1 or 2 further provided with the detection part for detecting the dew point temperature in the said airtight container.   Each of the said introduction part and the said discharge part has a pressure | voltage resistant measuring apparatus of any one of Claims 1-3 which has a valve.   The pressure | voltage resistant measuring apparatus of any one of Claims 1-4 further equipped with the voltage source which can be connected to the said probe and can generate the voltage of 600V or more.   The pressure-resistant measuring device according to claim 1, wherein the hermetic container has a window that transmits light so that the position of the semiconductor element can be observed from the outside of the hermetic container. A withstand voltage measuring method for measuring the withstand voltage of a semiconductor element formed on a semiconductor substrate and having an electrode part,
Supporting the semiconductor substrate in an airtight container;
And a step of supplying a voltage to the probe while bringing the probe into contact with the electrode portion after the step of supporting the semiconductor substrate.   The withstand voltage measuring method according to claim 7, further comprising a step of heating the semiconductor substrate after the step of supporting the semiconductor substrate and before the step of supplying a voltage to the probe. After the step of supporting the semiconductor substrate, an inert gas is introduced into the hermetic container from an introduction part provided in the hermetic container, and a gas in the hermetic container is introduced from a discharge part provided in the hermetic container. Exhausting the atmosphere in the hermetic container to an inert gas atmosphere; and
Detecting a dew point temperature in the hermetic container;
The pressure | voltage resistant measuring method of Claim 7 further provided with the process of closing between each of the said introducing | transducing part and the said discharge part, and the said airtight container according to the result of the process of detecting the said dew point temperature. Starting the heating of the semiconductor substrate after the step of supporting the semiconductor substrate and before the step of supplying a voltage to the probe;
And a step of stopping heating of the semiconductor substrate after the step of setting the atmosphere in the hermetic container to an inert gas atmosphere and before the step of detecting the dew point temperature in the hermetic container. 9. The withstand voltage measuring method according to 9.

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