JPS6036031B2 - How to measure semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring a semiconductor device, and more particularly to a method for measuring characteristics of a MOS field effect semiconductor device.

In recent years, in order to improve the mutual conductance of MOS field effect transistors (hereinafter abbreviated as FET), it is necessary to reduce the thickness of the gate insulating film to several hundred amps. , or to protect against electrostatic damage, or for other purposes, the proportion of devices such as diodes integrated between the gate and source has increased.

However, if the gate and source are damaged for some reason, it is necessary to electrically investigate whether the damaged part is in the additional element part or in the gate insulating film part, especially in dual-gate structure FETs. Extremely complex measurements are now required. FIG. 1 is an equivalent circuit diagram of an example of a conventional dual gate MOSFET.

One gate G. , ○2 and the source S are provided with two reversely connected diodes D, , D2, respectively.

FIG. 2 is a breakdown waveform diagram of a normal diode between G2 and S of the MOSFET shown in FIG.

FIG. 3 is a breakdown waveform diagram of an abnormal diode between G2 and S of the MOSFET shown in FIG. When the dual gate MOSFET is normal and has no defects, it exhibits the breakdown voltage characteristics shown in Figure 2, but if the diode's PN junction is damaged or the gate insulating film is damaged, leakage current will occur. Then, the waveform becomes as shown in FIG. It is extremely difficult and complicated to determine whether this leakage current is due to damage to the PN junction of the diode or dielectric breakdown of the gate insulating film.
There is a drawback that increasing the number of measurements increases the possibility that the destruction will progress and further induce destruction to other parts. The present invention eliminates the above-mentioned drawbacks and makes it possible to easily and accurately determine whether the damaged part of an FET with damage between the gate and source is in the additional element part or in the gate insulating film, regardless of whether it has a single or dual structure. The purpose of the present invention is to provide a method for measuring a semiconductor device that can be used to determine whether or not a semiconductor device is being used.

The method for measuring a semiconductor device of the present invention is to connect a resistor between the gate and source of the h40S field effect semiconductor device in which an additional element such as a diode is integrated between the gate and source, and to connect the resistor between the drain and source. By connecting a voltage source and an ammeter in series and measuring and comparing the drain current when the resistance value of the resistor connected between the gate and source is increased and when it is decreased, it is possible to detect the additional element and the insulating film. It is characterized by detecting which of the two has deteriorated.

The present invention will be explained by examples.

FIG. 4 is an equivalent circuit diagram of a measuring circuit used in the present invention.

A voltage source VD and a current meter 1 are connected between the drain D and source S of the dual gate MOSFET.

A voltage is applied between the gate G and the source S by connecting the gate G2 and the source S, a resistor R is connected between the gate G2 and the source S, and the resistor R
Depending on whether the drain current changes when the value of is changed, it is determined whether the damaged part is in the additional diode part or in the gate insulating waist part. The drain-source voltage is almost equal to the gate ○2 and the drain part, and the gate C
If there is a defect in the insulating film 2 that allows current to flow, the current will flow there, and this current will create a potential difference across the resistance between the gate ○2 and the source, and the drain current will change depending on the size of this resistance. Therefore, the above method is established.
FIG. 5 is a Vo-lo characteristic diagram measured by the method of the present invention.

In FIG. 5, 1'o is the drain current when the resistance R is 100KQ, and lo is the drain current when the resistance R is zero.

When the gate insulating film has dielectric breakdown, lo and 1 as shown in the figure.
′o. If the diode were damaged it would not make this difference. If the damaged part is at the gate G, connect a relatively large resistor in series with the source terminal, or connect another element, FET, diode, etc. in series, and use the above method as is. The difference in drain current can be increased.

The most expected effect of this measurement method is that when deterioration occurs during device manufacturing, the cause can be easily identified and countermeasures can be taken quickly. It is a very effective means of investigation.

[Brief explanation of drawings]

Figure 1 is an equivalent circuit diagram of an example of a secondary dual gate MOSFET, Figure 2 is a breakdown waveform diagram of a normal diode between G2 and S of the MOSFET in Figure 1, and Figure 3 is a diagram of the breakdown waveform of a normal diode between G2 and S of the MOSFET in Figure 1. A breakdown waveform diagram of an abnormal diode between ○2 and S of a MOSFET, FIG. 4 is an equivalent circuit diagram of a measuring circuit used in the present invention, and FIG. 5 is a V measured by the method of the present invention. -1. It is a characteristic diagram. D...Drain, G,, G21'' gate, S... Source, D,, D2... Diode, A.
...Ammeter, R...Resistance, Vo...Voltage source, Vc,
...Variable voltage source. Younger brother series 2 series 3 nails 4th bundle 5

Claims (1)

[Claims] 1 In a Mos-type field effect semiconductor device that integrates additional elements such as diodes between the gate and source,
When a resistor is connected between the sources, a voltage source and an ammeter are connected in series between the drain and the source, and the resistance value of the resistor connected between the gate and the source is increased, and the drain current and resistance value are decreased. 1. A method for measuring a semiconductor device, comprising: detecting which of the additional elements and the gate insulating film is degraded by measuring and comparing the drain currents of the semiconductor devices.