Data processing: measuring – calibrating – or testing – Testing system – Of circuit
Reexamination Certificate
1999-09-02
2002-06-11
Hilten, John S. (Department: 2863)
Data processing: measuring, calibrating, or testing
Testing system
Of circuit
C324S1540PB, C324S1540PB, C324S1540PB, C463S041000, C716S030000
Reexamination Certificate
active
06405148
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system and a method for testing semiconductor devices such as transistors and diodes, and more specifically, to an automatic classification system and method for automatically classifying semiconductor devices by determining current-voltage characteristics (hereinafter referred as “the I-V characteristics”)thereof with small memory capacity, as well as to a recording medium which is readable by a computer, storing the program for causing the automatic classification system to function and executing the method.
2. Description of the Related Art
At the final stage of manufacturing of field effect transistors (FETs), an examination test of the FETs is generally required. Conventionally, in the examination test, the drain-leakage current of FET is detected by a current measuring unit or a current tester. In the measurement, a specific voltage of predetermined level is applied between source and drain electrodes of FET with gate electrode being open, and the drain-leakage current is measured at the specific voltage. Then, the measured drain-leakage current at the specific voltage was compared with a standard value, and the FET having drain-leakage current not satisfying the standard value is rejected as defective device.
In such a testing, it is possible to screening out defective FET from acceptable FET, according to the detected drain-leakage current measured at the specific voltage, but it is not possible to determine the reason why the defective FET have been resulted to be poor in the manufacturing process. Or, it is not possible to determine the pattern of a characteristic-curve which shows how the drain-leakage current is related to the voltage applied between source and drain electrodes. Therefore, in order to examine the failure mode of the defective devices for further qualification, an I-V curve tracer is required to obtain the I-V characteristics, in addition to the screening device measuring only the drain-leakage current at the specific voltage. The I-V curve tracer measures again the drain-leakage currents of defective FETs supplying sawtooth voltages between source and drain electrodes of each of defective FETs, continuously changing the supply voltages in a certain voltage span. In this case, the classification task of the I-V characteristics must be done manually.
Such a method of manual classification using the results of continuous measurement by the I-V curve tracer requires a tremendous amount of time and labor for classification. In addition, as it takes a long time to analyze the failure modes of the defective devices, it is difficult to quickly respond in case such a failure or trouble is found in the semiconductor device.
Further, since the measurement is carried out with supply voltages continuously changing in the certain voltage span, by the I-V curve tracer, a vast amount of memory capacity has been required for storing the measured data with continuously changing supply voltages.
SUMMARY OF THE INVENTION
The present invention is intended to solve the problems described above and one object of the present invention is to provide an automatic semiconductor device classification system capable of significantly reduce time required for measuring, storing, calculating and classifying I-V characteristics of many semiconductor devices respectively located in respective exposure areas, step-and-repeatedly arranged on a surface of a large-diameter semiconductor wafers so as to manufacture a plurality of semiconductor devices.
Another object of the present invention is to provide an automatic semiconductor device classification system, capable of classifying I-V characteristics curves of the semiconductor devices without using the I-V curve tracer or the equivalent measuring instruments.
Yet another object of the present invention is to provide an automatic semiconductor device classification system, capable of reducing the number of required testing steps and the “turn-around-time” of the semiconductor devices.
Yet another object of the present invention is to provide a relatively low cost automatic semiconductor device classification system, having a simple system organization and is able to reduce the computer resource (i.e. memory capacity)required for the automatic classification of I-V characteristics.
Yet another object of the present invention is to provide an automatic semiconductor device classification system, having a simple system organization and is able to determine the I-V characteristics of a plurality of semiconductor devices in respective chip areas arranged on surfaces of semiconductor wafers, and thereby produce a classification map of the semiconductor wafer showing the respective I-V characteristics easily and quickly.
Yet another object of the present invention is to provide an automatic semiconductor device classification system, which is capable of significantly reducing time and labor required for analyzing failure modes of semiconductor devices.
Yet another object of the present invention is to provide an automatic semiconductor device classification system in which a shorter development period of a new-type semiconductor device and a quicker remedy response to a failure or trouble occurred in the device can be easily achieved.
Yet another object of the present invention is to provide a method for automatically classifying semiconductor devices in which the amount of time required for sorting-out or for classifying the I-V characteristics of a large number of semiconductor devices can be significantly reduced.
Yet another object of the present invention is to provide a method for automatically classifying semiconductor devices in which the I-V characteristics of the semiconductor devices can be classified into predetermined categories, without using the I-V curve tracer or the equivalent measuring instruments.
Yet another object of the present invention is to provide a method for automatically classifying semiconductor devices in which the turn-around-time” of the semiconductor devices can be reduced.
Yet another object of the present invention is to provide a method for automatically classifying semiconductor devices in which the amount of data required for the computation of the automatic classification can be significantly reduced.
Yet another object of the present invention is to provide a method for automatically classifying semiconductor devices in which a classification map of the I-V characteristics of semiconductor devices arranged on surfaces of semiconductor wafers can be quite easily produced.
Yet another object of the present invention is to provide a method for automatically classifying semiconductor devices in which the amount of time and labor required for analyzing failure modes of the semiconductor devices can be significantly reduced.
Yet another object of the present invention is to provide a method for automatically classifying semiconductor devices in which a shorter development period of a new-type semiconductor and a quicker response to failures or troubles can be easily achieved.
Yet another object of the present invention is to provide a recording medium which is readable by a computer and which stores a program for the automatic classification of I-V characteristics, the program being suitable for operating the aforementioned automatic classification system and the method of the semiconductor devices.
In order to achieve the objects described above, a first aspect of the present invention inheres in the automatic semiconductor device classification system comprising a current measuring unit, a data memory, and a processor connected to the data memory and the current measuring unit. The current measuring unit includes a voltage controller and an ammeter. The current measuring unit measures discrete current vs. voltage relations (hereinafter referred as “the I-V relations”) between predetermined electrodes of a semiconductor device, using discrete output voltages of the voltage controller. The data memory stores the disc
Hayashi Hideaki
Sawada Yoshinobu
Sonobe Hironori
Takeda Toyohiko
Hilten John S.
Kabushiki Kaisha Toshiba
Le John
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