JPH08153763A - Method for measuring semiconductor device - Google Patents

Abstract

PURPOSE: To accurately measure the voltage between the drain electrode and source electrode of a vertical semiconductor device, such as the MOSFET, etc., in a semiconductor wafer when a large current is made to flow to the MOSFET by providing a measurement electrode on the surface of an n<-1> -layer so as to measure the potential at the drain electrode. CONSTITUTION: In a MOSFET, a measurement element 12 is formed on the surface of an N<+> -area 11 provided so that the area can make ohmic contact with an n<-> -layer 4 and drain-side and source-side measurement probes 17 and 15 are respectively connected with the electrode 12 and a source electrode 9. A conducting probe 13 and stage 14 are electrically connected to each other by press-contacting the probe 13 with a semiconductor wafer. An electric current is made to flow between the probe 13 and stage 14 and the voltage across the drain and source electrodes of the MOSFET is detected with the probes 17 and 15.

Description

Detailed Description of the Invention

[0001]

This invention relates to a power MOSFE.
The present invention relates to a semiconductor device measuring method for measuring electrical characteristics such as on-voltage of a vertical semiconductor device such as a T, an IGBT, a power transistor, a thyristor, and a diode in a semiconductor wafer state.

[0002]

2. Description of the Related Art FIG. 4 is a diagram for explaining an example of a conventional measuring method for measuring an electrical characteristic such as an on-voltage of a semiconductor device in a semiconductor wafer by using a MOSFET. n ⁺
An n ⁻ layer 4 is formed on the layer 3, a p well region 5 and an n ⁺ region 6 are formed in the surface layer of the n ⁻ layer 4, and a source electrode 9 is formed on the surface of the n ⁺ region 6. However, the gate electrode 8 is formed on the surface of the p-well region 5 via the gate insulating film 7.
However, the drain electrode 10 is formed on the surface of the n ⁺ layer 3 to form a vertical MOSFET. In order to pass the main current I ₀ , the source electrode 9 is in contact with the conducting probe 13 and the drain electrode 10 is in contact with the stage 14, and the conducting probe 13 and the stage 14 are connected to the power supply 18. Here, the outer diameter of the stage 14 is substantially the same as that of the semiconductor wafer 1 (described later in FIG. 2A), but a suction groove for sucking the semiconductor wafer 1 is provided, and the semiconductor wafer 1 is distorted. Therefore, the contact with the semiconductor wafer 1 is local, and this contact portion is schematically shown. Further, in order to measure the voltage, a source side measurement probe 15 is connected to the source electrode 9, a drain side measurement probe 16 is connected to the drain electrode 10, and these probes are connected to a voltmeter 19. Further, the energization probe 13, the stage 14, the source side measurement probe 15
The drain side measurement probe 16 is electrically connected to the semiconductor wafer by pressure contact. In order to eliminate the voltage drop V ₀ which such contact resistance due to the main current I ₀ is to provide a separate measuring probe energized probe 13 and the stage 14 flow the main current I ₀ from the measurement. The main current I ₀ flows from the drain electrode 10 toward the source electrode 9.

[0003]

However, when the main current I ₀ flows from the drain electrode 10 toward the source electrode 9 in the direction of the arrow, it separates from the drain electrode 10 immediately below the n ⁺ region 6 forming the source region 6. Since the stage 14 and the drain side measurement probe 16 normally contact the drain electrode 10, the main current I ₀ flows laterally in the drain electrode 10 made of an extremely thin metal film as shown by the arrow V.
_{Since 0} occurs, and the voltage between the source electrode 9 and the drain electrode 10 is measured including this potential drop V ₀ , it cannot be measured accurately.

Next, this will be described in detail. The potential distribution when the main current is applied to the MOSFET, for example, is shown by the dotted line in FIG. The main current I ₀ flows into the drain electrode 10 from a position in contact with the stage, flows laterally in the drain electrode 10 as indicated by an arrow, and then enters the n ⁺ layer 3. Since the drain electrode 10 is formed of a metal film having a thickness of several μm,
Since the resistance in the lateral direction is large, the voltage drop V ₀ due to the main current I ₀ of several A to 100 A running in the lateral direction.
Is a source of error in the measurement of the voltages of the drain electrode 10 and the source electrode 9. That is, when the voltage between the source electrode and the drain electrode is measured by bringing the drain side measuring probe 16 of the drain electrode 10 into contact as in the conventional case, this voltage drop V ₀ is added, and this voltage drop V ₀ is semiconductor. It is different for each semiconductor device in the wafer, and accurate voltage cannot be measured.

An object of the present invention is to provide a method for measuring a semiconductor device which eliminates the above-mentioned drawbacks and can measure the voltage between the source electrode and the drain electrode with high accuracy.

[0006]

In order to achieve the above-mentioned object, the present invention has one first electrode for passing a main current on one main surface of a semiconductor wafer and the other main surface for the other. A method for measuring a voltage between a first electrode and a second electrode when a main current is applied to each semiconductor device of a semiconductor wafer in which a plurality of vertical semiconductor devices having a second electrode are arranged in parallel, A measurement electrode for measuring the potential of the second electrode is provided on the first electrode, and the voltage corresponding to the voltage between the first electrode and the second electrode is measured by the first electrode and the measurement electrode. Further, this measurement electrode is provided in the vicinity of the first electrode of the semiconductor device, or is formed on a region where the semiconductor device is not formed, and the voltage between the first electrode and the second electrode is equivalent to the voltage between the first electrode and the measurement electrode. It is effective to measure the applied voltage. Further, this measurement electrode may be provided on a scribe line not forming a semiconductor device or on the outer peripheral portion of a semiconductor wafer, and a voltage corresponding to the voltage between the first electrode and the second electrode may be measured by the first electrode and the measurement electrode. .

[0007]

The potential distribution when the main current I ₀ is applied to the semiconductor device is as shown in FIG. As in the present invention, the measuring electrode 12 is provided on the surface of the n ⁻ layer via the n ⁺ region 11, and the drain side measuring probe 17 and the source side measuring probe 15 are used to connect the drain electrode 10 and the source electrode 9 with a voltmeter. When the voltage is measured, the potential of the measuring electrode 12 becomes the potential VD at the boundary between the n ⁺ layer 3 and the drain electrode 10, and the influence of the potential drop V ₀ due to the current flowing laterally through the drain electrode 10 can be removed. Therefore, between the measurement electrode 12 and the source electrode 9
Can be accurately measured even when the main current I ₀ is large. If the drain side measurement probe 16 and the source side measurement probe 1 are in contact with the drain electrode 10, as in the conventional example.
When the voltage is measured at 5, the voltage drop V ₀ is added and the accuracy is poor.

[0008]

EXAMPLE FIG. 1 is a cross section of a MOSFET provided with a measuring electrode.
The figure is shown. The reference numerals are the same as those in the conventional example of FIG.
Differences from the conventional example will be described. The measurement electrode 12 is n
⁺It is formed on the surface of the layer 11 and is connected to the measurement electrode 12 on the drain side.
The measuring probe 17 is in contact. In addition, with the measurement electrode 12
n^-N so that layer 4 is in ohmic contact⁺Shape region 11
Is made. Other parts are the same as those in FIG. This
The rain side measuring probe 17 and the source electrode 9 are connected to each other.
The source side measurement probe 15 is connected to a voltmeter 19. Well
Similarly to the conventional example, the energization probe 13, the stage 14,
Source side measurement probe 15 and drain side measurement probe
The bump 17 is electrically connected to the semiconductor wafer by pressure contact.
ing. Depending on this measuring method, from several A to 100 A
Lateral direction inside the drain electrode 10 when main current is applied
Voltage drop V due to current flowing through ₀Can be removed from the measurement,
Therefore, the drain voltage of the MOSFET in the semiconductor wafer 1 is
The voltage between the pole 10 and the source electrode 9 can be measured with high accuracy, and
An accurate on-resistance value of MOSFET can be obtained.

FIG. 2 is a plan view showing the positions where the measuring electrodes of one embodiment are provided. FIG. 1A shows the MO on the semiconductor wafer 1.
A plan view showing the semiconductor devices 2 such as SFETs arranged in parallel is shown, and the measurement electrodes 12 are arranged in the semiconductor device 2, on the scribe line 20 and on the outer peripheral portion 21 of the semiconductor wafer 1 where the semiconductor device 2 is not formed. . FIG. 2B is an enlarged view of the semiconductor device 2, and the measurement electrode 12 is the source electrode 9
It is located near. The gate electrode pad 22 is a current collecting electrode connected to the gate electrode 8 (FIG. 1) and is connected to a bonding wire. The same figure (c) is the same figure (a)
The measurement electrode 1 on the scribe line 20 is an enlarged view in the circle
It is the figure which arranged 2.

Although the MOSFET has been described in the embodiment, the same method can be applied to the measurement when the vertical semiconductor device such as the IGBT, the power transistor, the thyristor and the diode is arranged on the semiconductor wafer.

[0011]

According to the present invention, in a vertical MOSFET arranged on a semiconductor wafer, a measuring electrode for measuring the potential of the drain electrode is provided on the surface of the semiconductor wafer having the source electrode, so that a large main current is applied. However, the voltage between the drain electrode and the source electrode can be accurately measured. In addition to MOSFETs, vertical semiconductor devices such as IGBTs, power transistors, thyristors, and diodes are also accurately measured by the same measurement method between main electrodes (for example, between a collector electrode and an emitter electrode in a transistor, between an anode electrode and a cathode electrode in a thyristor). The voltage of can be measured.

[Brief description of drawings]

FIG. 1 is a sectional view of a MOSFET provided with a measurement electrode.

2A and 2B are plan views of an embodiment, FIG. 2A is a plan view of a semiconductor wafer, FIG. 2B is an enlarged view of a semiconductor device, and FIG. 2C is an enlarged view of a scribe line.

FIG. 3 is a diagram showing a potential distribution

FIG. 4 is a sectional view showing a conventional example.

[Explanation of symbols]

1 semiconductor wafer 2 semiconductor device 3 n ⁺ layer 4 n ⁻ layer 5 p well region 6 source region (n ⁺ ) 7 gate insulating film 8 gate electrode 9 source electrode 10 drain electrode 11 n ⁺ region 12 measurement electrode 13 current probe 14 stage 15 Source-side measurement probe 16 Drain-side measurement probe 17 Drain-side measurement probe 18 Power supply 19 Voltmeter 20 Scribe line 21 Peripheral part 22 Gate electrode pad I ₀ Main current V ₀ Voltage drop

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/336

Claims (4)

[Claims] 1. A plurality of vertical semiconductor devices having one first electrode for passing a main current on one main surface of a semiconductor wafer and having the other second electrode on the other main surface are arranged in parallel. In the method of measuring the voltage between the first electrode and the second electrode when a main current is applied to each semiconductor device of a semiconductor wafer, a measurement electrode for measuring the potential of the second electrode is provided on one main surface, and A method for measuring a semiconductor device, wherein a voltage corresponding to a voltage between a first electrode and a second electrode is measured with one electrode and the measurement electrode. 2. The measurement of a semiconductor device according to claim 1, wherein a measurement electrode is provided in the vicinity of the first electrode of the semiconductor device, and a voltage corresponding to the voltage between the first electrode and the second electrode is measured. Method. 3. A measuring electrode is formed on a region where a semiconductor device is not formed, and a voltage corresponding to a voltage between the first electrode and the second electrode is measured by the first electrode and the measuring electrode. The method for measuring a semiconductor device according to claim 1. 4. A measuring electrode is provided on a scribe line not forming a semiconductor device or on an outer peripheral portion of a semiconductor wafer,
The method for measuring a semiconductor device according to claim 1, wherein a voltage corresponding to a voltage between the first electrode and the second electrode is measured by the first electrode and the measurement electrode.