JPH0256948A - Measurement of electrostatic energy - Google Patents

Abstract

PURPOSE:To measure the potential of applied electrostatic energy at an arbitrary time by previously finding the correlation of electrostatic energy with each diode in which a plurality of diodes are formed on a semiconductor board to previously deteriorate. CONSTITUTION:Six junction diodes 21-26 are formed on an N-type silicon substrate 1 to have pads 3 at both the ends thereof respectively. Since the deterioration of withstand voltage occurs in the concentration of current, the correlation between surge withstand voltage for deteriorating the withstand voltage and N-layer 6 area occurs in the diodes 21-26. Such a semiconductor substrate 1 is assembled to carry together, the withstand voltage of the diodes 21-26 is measured to detect the withstand voltage of which diode is deteriorated. Therefore, we can know till which time point and how many potentials of electrostatic energy are applied. Thereby, when a semiconductor device is assembled and carried, we can measure how many potential of the electrostatic energy are applied without the use of a practical element of a semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring electrostatic energy applied to a semiconductor device including an MO3 element, for example, during an assembly process or during transportation.

[Conventional technology]

In semiconductor devices, destruction may occur due to electrostatic energy. Particularly in MO3 devices, the gate insulating film is easily destroyed by electrostatic energy.Therefore, an input protection circuit is used to prevent electrostatic damage, but the input protection circuit itself may be destroyed by large electrostatic energy. There is.

Furthermore, since electrostatic energy is likely to be applied to the MO3 element during the assembly process or during transportation, it is difficult to completely prevent electrostatic damage using a human protection circuit.
Therefore, it is necessary to perform quality control by measuring how much electrostatic energy is applied to the MO3 element in which step in the assembly and transportation of the MO3 element.

[Problem to be solved by the invention]

Conventionally, it has been possible to measure the amount of static electricity charged on semiconductor device packages and the like. However, since the phenomenon in which electrostatic energy is applied to the MO3 element occurs instantaneously, it has been difficult to measure its magnitude using an actual MO3 element. Furthermore, it is difficult to measure the amount of electrostatic energy under the same conditions as the MOS elements during assembly and transportation.

The invention! IB relates to an electrostatic energy measurement method that can measure how much electrostatic energy is applied during assembly and transportation of a semiconductor device, without using practical elements of the semiconductor device.

[Means to solve the problem]

In order to solve the above problems, the method of the present invention is achieved by changing the area of the PN junction between the semiconductor layer of one conductivity type and the semiconductor layer of the other conductivity type, or by changing the impurity concentration of at least one layer. A plurality of PN junction diodes whose withstand voltage deteriorates only when electrostatic energy of different magnitudes is applied are formed, and the withstand voltage of each diode is measured at a predetermined time to detect a diode whose withstand voltage has deteriorated. Electrostatic energy is measured by utilizing the correlation with electrostatic energy.

[Effect]

In a PN junction diode formed by semiconductor layers of different conductivity types, junction breakdown occurs due to concentration of current due to the application of electrostatic energy, and the breakdown voltage deteriorates or a short circuit occurs. Therefore, by changing the PN junction area to change the applied electrostatic energy, which increases in proportion to the junction area, or by changing the impurity concentration of at least one layer to change the allowable electrostatic energy amount, a predetermined amount of electrostatic energy can be achieved. A PN junction diode whose breakdown voltage deteriorates only when electrostatic energy is applied can be obtained. Therefore, P
If multiple N-junction diodes are formed, by detecting which diode's breakdown voltage has deteriorated at a certain point, it is possible to know the amount of electrostatic energy applied during the assembly process or transportation up to that point. can.

〔Example〕

FIG. 1 conceptually shows a plan view of an electrostatic energy detecting element used in an embodiment of the present invention.
PN junction diodes 21.22, 23°24.25
．． 26 are formed, each having a pad 3 at both ends. Figures 2 (al) and (b) show these diodes in a plane perspective view and a cross-sectional view, respectively, in which a P-type layer 2 with a low impurity concentration is formed on an N-type silicon substrate 1 by diffusion, and an oxide film is formed on the N-type silicon substrate 1 by diffusion. 4.

Near both ends of the second layer 2, a P-type contact layer 5 and an N-type layer 6 with high impurity concentrations are formed by diffusion using the oxide film 4 as a mask. 4
The opening of A7 contacts the A7 electrode 7 connected to the pad 3. The impurity concentration 1 area of the two layers 2 in each of the PN junction cross-sectional views 21 to 26 is the same, but the area of the N-swelled diffusion layer 6 is different.

3 and 4, the impurity concentration of the second layer 2 is 5 x
lQ”/aj, impurity concentration of N layer 6 2.0 XlO
In eyes/d, the dimensions of the N layer 6 are 2QnX 2Q4, 3Q4
An example of the relationship between the forward and reverse breakdown voltages of the diode and the applied surge voltage when X30n is shown.

When line 31.41 has dimensions of N layer 6 of 2O-X20μ,
The lines 32 and 42 indicate that the dimensions of the N layer 6 are 30tnaX30tna
This is the case.

Since the half-3 board 1 generally has a capacitance of 100 pP between the ground and the ground, a diode with an N layer 6 of dimensions 20 n x 20 - will have a reduced withstand voltage when a surge voltage of 400 V or more or -300 V or less is applied. The voltage will not increase even if the surge voltage is removed. As described above, this deterioration of the withstand voltage occurs due to concentration of current, so there is a correlation between the area of the N layer 6 and the surge withstand voltage that deteriorates the withstand voltage in the diodes 21 to 26 as well. Therefore, such a ``semiconductor substrate 1'' is
It is assembled in the same assembly process as the O3 element, transported together, and the withstand voltage of each diode 21 to 26 is measured at the appropriate time to detect which diode's withstand voltage has deteriorated. For example, in the above example, a semiconductor substrate on which diodes with different junction areas were formed and a practical MO5 element were created separately, but an IC containing a practical MO3 element was fabricated separately. By incorporating this diode into the IC, it is possible to directly measure the process or point in time when static electricity is applied to the IC itself, and the magnitude of the electrostatic energy.

In addition, since the allowable capacitance changes when the impurity concentration of the PN junction diode is changed, a P- layer 2 is formed by diffusion in the silicon-based Fil as shown in FIG. When forming by diffusion, by changing the impurity concentration of P- layer 2 or N-layer 6, a plurality of diodes composed of layers with different impurity concentrations and the same junction area are formed, and the impurity concentration and breakdown voltage deteriorate. Electrostatic energy can be measured in the same way if the relationship with the applied surge voltage is determined in advance.

(Effects of the Invention) According to the present invention, by utilizing the fact that the breakdown voltage of a PN junction diode deteriorates due to concentration of current when electrostatic energy is applied,
By forming multiple diodes with different electrostatic energy for deterioration on one semiconductor substrate and finding the correlation between the electrostatic energy for deterioration and each diode in advance, the magnitude of the electrostatic energy applied up to a given point can be determined. can be measured. Therefore, it can be useful, for example, to prevent damage to the gate insulating film of an MO3 element on an IC assembly line.

[Brief explanation of the drawing]

FIG. 1 is a conceptual plan view of an electrostatic energy measuring element used in an embodiment of the present invention, and FIG. 2 shows a PN junction diode portion of the element in FIG. The cross-sectional views, FIGS. 3 and 4, respectively show P with different bonding areas.
FIG. 3 is a relationship diagram between the withstand voltage and the applied surge voltage in the forward and reverse directions of an N-junction cross-sectional view. IFN type silicon substrate, ZiP type low impurity concentration diffusion layer,
3: Band, 6: N-type high impurity concentration diffusion layer, 7: M electrode, 21, 22, 23, 24, 25, 26 j P N junction fuge ll1 (V) Fig. 3 Bhuj Jingyu (v) 141! 1 Procedural amendment (-ji vision 1, indication of case 2, name of invention patent application"'i, 3-zt>tgty 贴子电子/rev i+趨・rしまんへ 3, amended person's case and Related address name

Claims (1)

[Claims] 1) By changing the area of the PN junction between the semiconductor layer of one conductivity type and the semiconductor layer of the other conductivity type, or by changing the impurity concentration of at least one layer, the breakdown voltage can be increased by applying different amounts of electrostatic energy. By forming multiple PN junction diodes whose breakdown voltage deteriorates, measuring the breakdown voltage of each diode at a predetermined point in time to detect diodes with degraded breakdown voltage, and utilizing the correlation between the breakdown voltage degradation of the diode and the applied electrostatic energy. A method for measuring electrostatic energy characterized by measuring electrostatic energy.