JPH0711558B2 - Method for measuring characteristics of semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention measures the characteristics of a semiconductor device such as a diode, a transistor, or a thyristor (hereinafter, the semiconductor device is represented by a diode) to determine whether the diode is a non-defective product or a non-defective product. The present invention relates to a method for measuring characteristics of a semiconductor device, which is used to discriminate non-defective products or the like.

(Prior Art) As a conventional semiconductor device characteristic measuring method, for example, as shown in FIG. 8, when a reverse voltage (VR) is applied to a diode and a predetermined reverse current value (iR) is reached, Measurement of the withstand voltage of the object to be measured (hereinafter, abbreviated as PRV) characteristics, a predetermined forward current (iF) is passed through the diode, and the forward voltage drop (hereinafter, FD
V) is measured and, for example, the reverse voltage (VR) is measured when the reverse current value (iR) reaches 2 μA. If VR <100 V, the product is defective and 100 ≤ VR <200V, 20
When 0V ≦ VR <400V, ..., classification (G1), (G
2),…, and if it is a general-purpose diode with a current capacity of 1 to 3A class, for example, the voltage drop value (VF) when forward current (iF) is 3A is less than 1V. In some cases, the product is judged to be non-defective, and in the case of 1V or higher, it is judged to be defective.

However, in such a conventional measurement method, only the voltage when the predetermined reverse current value (iR) is reached is measured once, and the voltage when the predetermined forward current (iF) is applied is measured. Since only the drop value is measured once to determine whether the diode is a good product or a defective product, it is not possible to detect a defective product that exhibits an abnormality such as a change in the PRV waveform of the diode, a so-called reverse drift waveform, or a loop waveform. However, there is a problem that defective products such as changes in the FDV waveform, so-called forward drift waveform, and flutter of the FDV waveform cannot be detected. Furthermore, when PRV and FDV characteristics are measured again, There is a problem that a defective product having an unstable characteristic cannot be detected because the measured value of the second time is different.

As a measurement method to solve these problems, it is possible to measure the PRV characteristic and the FDV characteristic while visually observing the waveform with a measuring instrument such as a curve tracer, but with such a measuring method, automatic measurement is performed. Since this is not possible, the work efficiency is poor, and there is a problem that the measurement time per diode cannot be measured at a high speed with a general measurement speed of 1 second or less.

(Object of the Invention) The present invention has been made in view of these problems, and a change in the PRV waveform of a diode, for example, a defective product exhibiting an abnormality such as a reverse drift waveform, a loop waveform, and a diode. FDV waveform changes such as, for example, forward drift waveform, FDV waveform wobble and other defective products can be detected at high speed, and further, defective products whose characteristics change after the first measurement An object of the present invention is to provide a method for measuring the characteristics of a semiconductor device, which can be surely detected by the measurement.

(Structure of the Invention) In order to achieve the above object, in the present invention, in a method for measuring characteristics of a semiconductor device, which is performed by passing a current in a forward direction and a reverse direction, a method of measuring a reverse withstand voltage waveform of the semiconductor device, The forward voltage drop waveform of the semiconductor device is measured at least twice each, and the forward voltage drop waveform is measured at least once between the first and second reverse withstand voltage waveform measurements. A characteristic of the semiconductor device is determined by comparing each of the measured reverse voltage waveforms and each of the measured forward voltage drop waveforms. It lies in the characteristic measurement method.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 to 7 show an embodiment of the present invention.
The figure shows a measurement sequence, and FIG. 7 is a schematic circuit diagram of a measurement apparatus used in the measurement method of the present invention.

As shown in Fig. 1, the diode measurement is the first PR
V waveform measurement (1), 1st FDV waveform measurement (2), 2nd FDV waveform measurement (20) and 2nd PRV waveform measurement (10)
Are performed in order.

In the first PRV waveform measurement (1), the reverse voltage (VR) applied to the diode was changed from 0V between T0 and T5.
Increase to 1500V, from 1500V from T5 to T7
Lower to 0V.

The reverse current value (iR) is 0 until T3 when iR = 10 μA.
For each 625 μA increase, the reverse voltage (VR) at that time is measured, and the measured value is stored. The measured value is used for the backward soft waveform test.

Measure the reverse voltage (VR) at T2 when iR = 1.25 μA,
The measured value is stored. The measured value is used as the PRV of the diode and is used for reverse breakdown voltage classification.

From T3 time to T4 time when iR = 20 μA, every time the reverse current value (iR) increases by 1.25 μA, the reverse voltage (VR) at that time is measured and the measured value is stored. The measured value is used for the backward drift test described later.

Every time the reverse current (iR) changes by 6.25 μA from the time of iR = 25 μA to T5 when iR = 100 μA and from T5 to T6 when iR = 20 μA, the reverse voltage (VR ) Is measured and the measured value is stored. The measured value is used for a reverse loop waveform test described later.

In the first FDV waveform measurement (2), the forward current (iF) flowing through the diode is increased from 0A to 3A from T7 to T8, and the forward current (iF) is increased by 0.1875A. For each time, the voltage drop value (VF) at that time is measured and the measured value is stored.

The second FDV waveform measurement (20) is performed from T9 to T10 as in the first FDV waveform measurement (2).

The second PRV waveform measurement (10) is performed from T11 to T19 as in the first PRV waveform measurement (1).

As described above, the PRV waveform measurement and the FDV waveform measurement are performed twice for the same diode, and the above-mentioned respective measurement values obtained by praying are prayed and the following tests (A) to (H) are performed. To do.

(A). Reverse soft waveform test Figure 2 shows the reverse voltage-reverse current waveform (1a) obtained by the first PRV waveform measurement (1). In the figure, point (a1) is iR = 0.625. The point of μA and the point (a2) indicate the point of iR = 1.25 μA.

Change in reverse current iR from point (a1) to point (a2) ΔiR
= 0.625 μA, the smaller the change amount ΔVR of the reverse voltage (VR) from point (a1) to point (a2), the more the waveform (1a)
Shows a sharp rise, and the larger ΔVR, the softer the rise of the waveform (1a). Since the diode is required to have a sharp rise, it is determined whether or not ΔVR is a predetermined value or more.

From such data analysis, i.e. iR = 10μA from T0
Until each time, the measurement is performed for each measurement point, and if even one measurement point where ΔVR is a predetermined value or more is detected, the diode is determined to be a defective product. This is the reverse soft waveform test. Also, the same reverse soft waveform test was performed for the second time.
It is also performed for each measurement value obtained from T11 to T14 by PRV waveform measurement (10).

(B). Reverse drift test In Fig. 3, (1a) is the first PRV waveform measurement (1)
The reverse voltage-reverse current waveform from T0 to T4 obtained by (10a) is the second PRV waveform measurement (1
It is a reverse voltage-reverse current waveform from T11 to T15 obtained by (0).

Each measured value of the reverse voltage (VR) measured every time iR increased by 1.25 μA from T0 to T4, and the reverse voltage measured in the same manner from T11 to T15 ( (VR) is compared with each measurement value at each measurement time, and if any one of the measurement points where the VR variation ΔVR is equal to or more than a predetermined value is detected, the diode is determined as a defective product. This is the reverse drift test. What is important here is that at least the first measurement of the forward voltage drop waveform is performed between the first measurement and the second measurement of the reverse withstand voltage waveform. By making this order, for example, the semiconductor device in which the solder connection between the semiconductor chip and the lead wire is incomplete is the first FDV
Since the junction temperature of the semiconductor chip rises due to the current of the waveform measurement (1), the diode becomes the specified ΔVR value or more by the second PRV waveform measurement (10) and is selected as a defective product.

Also, if the surface treatment near the PN junction interface of the semiconductor chip is incomplete, the PRV waveform changes due to instability in the opposite direction, and defective products with incomplete surface treatment should be selected. You can

(C). Reverse loop test In Fig. 4, (1b) is the first PRV waveform measurement (1)
It is the reverse voltage-reverse current waveform from T4 o'clock to T5 o'clock obtained by (1C) is the reverse voltage-reverse current waveform from T5 o'clock to T6 o'clock.

As shown in Fig. 4, when the diode has the characteristic of showing a loop waveform, iR is 6. between T4 and T5.
Each measured value of reverse voltage (VR) measured every 25 μA increase, and each measured value of reverse voltage (VR) measured each time iR decreases 6.25 μA between T5 and T6 And are compared at each measurement time, and if even one measurement point at which the VR variation ΔVR is equal to or greater than a predetermined value is detected, the diode is determined as a defective product. This is the reverse looped test. Also, the same reverse looped test
The PRV waveform measurement (10) is also performed for each measurement value obtained from T15 to T17.

(D). Reverse breakdown voltage classification In Fig. 1, the reverse voltage (VR) at T2 and T13 when iR = 1.25 µA is set as the PRV of the diode, and V
If R <100V, the diode is considered defective and 100 ≤ VR
When <200V, 200V ≤ VR <400V, 400V ≤ VR <600V, ..., the diodes are (G1), (G2), (G4), ..., respectively.
are categorized. This is the reverse breakdown voltage classification.

(E). Forward drift test In Fig. 5, (2a) is the first FDV waveform measurement (2).
Is a forward voltage-reverse voltage waveform obtained by
(20a) is a forward current-forward voltage waveform obtained by the second FDV waveform measurement (20).

In the first FDV waveform measurement (2), each measured forward voltage drop value (VF) was measured every time iF increased by 0.1875A from T7 to T8, and the second FDV waveform Measurement (2
In (0), the forward voltage drop value (VF) measured in the same way from T9 to T10 is compared for each measurement time, and if the amount of change in VF ΔVF is greater than or equal to the specified value, If even one measurement point is detected, the diode is determined as a defective product. This is the reverse drift test.

(F). Forward Fluctuation Test In Fig. 6, (2b) is the first FDV waveform measurement (2).
Is a forward voltage-reverse voltage waveform obtained by
The waveform (2b) includes a flared portion (2c). The diode showing the waveform (2b) having such a fluttered portion (2c) is discriminated as a defective product.

The forward flapping test detects the flapping portion (2c).

In FIG. 6, iF (a) to iF (f) have an iF of 0.1875A.
It shows the forward current value at each measurement point that increased by
(A) to VF (f) indicate the measured values of the forward voltage drop at the measurement points corresponding to the if (a) to if (f).

If the diode is good, VF (a) <VF (b) ... <VF
(F). However, in the waveform (2b) shown in FIG. 6, VF (a) <VF (b)> VF (c) <VF (d)> VF
(E) <VF (f).

That is, the magnitude relationship between adjacent measurement points is sequentially compared to obtain the characteristic that VF (a) <VF (b) ... <VF (f) over the entire forward current-forward voltage waveform (2b). If it is found, it is determined as a non-defective product.

Although illustration is omitted, defective products are selected according to the change rate of ΔVF even when the waveform changes abruptly on the way.

A similar forward flutter test is also performed on the forward current-forward voltage waveform obtained by the second FDV waveform measurement (20).

(G). Forward voltage classification As shown in FIG. 5, for example, the forward current if of the waveform 2a is
Forward voltage drop VF when (1) is applied to the diode
If (1) is within the range of 0.6V <VF (1) <0.9V, the diode is determined as a good product. This is the forward voltage classification.

(H). Reverse Short Circuit Test In the second FRV waveform measurement (10), apply reverse voltage (VR) from T17 to T18 and finally check whether the diode is short-circuited. If the diode is short-circuited, VR becomes zero volt, and the reverse current (iR) is limited by the protective resistance of the measuring instrument and flows for several amperes.
Is detected, the diode is determined as a defective product. This is the reverse short test.

Next, the measuring device (3) used in the above measuring method
It will be described with reference to the drawings.

As shown in FIG. 7, the measuring device (3) has a CPU (30).
, Interface (31), D / A converter for current setting (32), reverse constant current amplifier (33), forward constant current amplifier (34), and diode under test (4) are set. Measuring terminal (35), sample resistance (36),
D / A converter (37) and interface (38),
(39) consists of

When the first PRV waveform measurement (1) is performed by the measuring device (3), the CPU (30) operates according to a pre-programmed procedure, and the operation of the CPU (30) is the interface (3).
1) is transmitted to the D / A converter (32) for current setting, and by the operation of the converter (32), the reverse constant current amplifier (33) causes the reverse current value (for example iR = Reverse voltage (VR) until 0.625 μA)
Is applied to the diode (4) to be measured. The reverse current of the diode (4) flows through the sample resistor (36),
The voltage at point a) is fed back to the amplifier (33). On the other hand, the reverse voltage value (VR) when iR becomes 0.625 μA is sent to the CPU (30) via the A / D converter (37) and the interface (31) and stored.

Such reverse voltage (VR) measurement and storage operations are
Controlled by the CPU (30), in Fig. 1, from T0 to T
Each time iR rises by 0.625μA between 3 o'clock, every iR rises by 1.25 μA between T3 o'clock and T4 o'clock, and between T4 o'clock T5 o'clock.
Every time iR rises by 6.25 μA, iR is 6. between T5 and T6.
It is carried out every time 25 μA is lowered. In this way, the first PRV waveform measurement (1) shown in FIG. 1 is performed by the measuring device (3). Similarly, the second PRV waveform measurement (10) shown in FIG. 1 is performed by the measuring device (3).

Next, when the first FDV waveform measurement (2) is performed by the measuring device (3), the CPU (30) operates according to a preprogrammed procedure, and the operation of the CPU (30) operates the interface (31). Via the D / A converter (3
2), the forward constant current amplifier (34) sends a pre-programmed forward current (for example, if = 0.1875A) to the diode under test (4) by the operation of the converter (32). The sample resistor (36) detects whether or not a predetermined current flows through the diode (4), and the potential at the point (3a) is fed back to the amplifier (34). On the other hand, the forward voltage drop value (VF) of the diode (4) when a forward current of 0.1875A flows is measured at the measurement terminal (35).
Is detected by and is sent to the CPU (30) via the A / D converter (37) and the interface (31) and stored therein.

The measurement and storage operation of such a forward voltage drop value (VF) is controlled by the CPU (30), and as shown in FIG.
From time to T8, each time the forward current (if) rises by 0.1875A. In this way, the first FDV waveform measurement (2) shown in FIG. 1 is performed by the measuring device (3). Similarly, the second FDV waveform measurement (20) shown in FIG. 1 is performed by the measuring device (3).

Then, a large number of reverse voltage values (VR) and a large number of forward voltage drop values (VF) stored in the CPU (30) are stored in the CPU (3
Data is analyzed in 0) and various tests (A) to
The calculation for (H) is performed in the CPU (30).

Then, the signal for discriminating the non-defective product or defective product of the diode to be measured (4) and the classification signal are output from the CPU (30) to the interface (38).

To set the measurement conditions, the panel of the measuring device is input to the CPU (30) via the interface (38).

The diode measurement sequence does not have to be limited to the order and the number of times shown in FIG. 1, and the point is that the PRV waveform measurement and the FDV waveform measurement are included at least twice each, and the PRV waveform measurement is performed. It is sufficient that at least the first FDV waveform measurement is included between the first and second times.

(Effect of the Invention) According to the semiconductor device characteristic measuring method of the present invention, the measurement of the reverse withstand voltage waveform of the semiconductor device and the measurement of the forward voltage drop waveform of the semiconductor device are performed at least twice each. , And, while comparing each of the measured reverse withstand voltage waveforms, and because each of the measured forward voltage drop waveforms are being compared, a change in the reverse withstand voltage (PRV) waveform of the semiconductor device, For example, a defective product exhibiting abnormalities such as a backward drift waveform and a loop waveform, and a defective product exhibiting a change in the forward voltage drop (FDV) waveform of a semiconductor device, for example, a forward drift waveform and a flutter of the FDV waveform can be processed at high speed. It is possible to detect, and furthermore, a defective product whose characteristics change after the first measurement can be reliably detected in the second measurement. Further, it is possible to select a semiconductor device or the like in which the solder connection between the semiconductor chip and the lead wire is incomplete, or an incomplete surface stabilization treatment in the vicinity of the PN junction portion of the semiconductor chip as a defective product.

[Brief description of drawings]

1 to 7 show an embodiment of the present invention.
FIG. 4 is a waveform diagram showing a measurement sequence, FIG. 2 is a waveform diagram for explaining a backward soft waveform test, FIG. 3 is a waveform diagram for explaining a backward drift test, and FIG. Waveform diagram for loop test, FIG. 5 is a waveform diagram for explaining the forward drift test, and FIG. 6 is
FIG. 7 is a waveform diagram for explaining the forward flapping test, FIG. 7 is a schematic circuit diagram showing a measuring device used in the measuring method according to one embodiment, and FIG. 8 is a waveform diagram showing a conventional measuring method. is there. (1) …… First reverse withstand voltage waveform measurement (2) …… First forward voltage drop waveform measurement (10) …… Second reverse withstand voltage waveform measurement (20) …… Second time Forward voltage drop waveform measurement

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 54-127286 (JP, A) JP 51-132086 (JP, A) JP 57-34506 (JP, B2)

Claims (1)

[Claims] 1. A method of measuring a characteristic of a semiconductor device, which is performed by passing a current in a forward direction and a reverse direction, wherein a reverse withstand voltage waveform of the semiconductor device and a forward voltage drop waveform of the semiconductor device are measured. , At least two times each, performing at least the first forward voltage drop waveform between the first and second measurements of the reverse withstand voltage waveform, and measuring the reverse voltage waveform A characteristic measuring method for a semiconductor device, characterized in that the characteristics of the semiconductor device are determined by comparing each of them and comparing each of the measured forward voltage drop waveforms.