JPH0731228B2 - Measuring method of device characteristic measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring method of an element characteristic measuring apparatus for measuring electric characteristics of semiconductor elements and other elements.

[0002]

2. Description of the Related Art An element characteristic measuring apparatus for measuring the electrical characteristics of a device under test such as a semiconductor supplies a test signal of voltage or current to the device under test, and the current flowing through the device under test or the device under test is measured. Is measured, and the measured value is converted into a digital value and stored in the memory. Data of a plurality of measurement points is obtained by executing this measurement operation for a predetermined range while sequentially incrementing the value of the test signal. Here, the measurement point is a measurement point defined based on the value of the test signal of the voltage or current supplied to the device under test and the value of the current or voltage of the device under test at that time, For example, it corresponds to a coordinate point on the orthogonal coordinate plane of the current axis to the voltage axis (or the voltage axis to the current axis). Note that the measurement points are not limited to coordinate points having voltage values and current values as elements, and various variable values (gain values, gain values, derived from the current values and voltage values by calculation).
It may be a coordinate point having an element such as an impedance value and an admittance value), and is determined according to the measurement mode of the device characteristic measuring device. In this way, by displaying the data of the plurality of measurement points stored in the memory on the two-dimensional coordinate plane, various electrical characteristics of the device under test can be displayed.

When measuring the characteristics of the device under test, the user sets the range of the voltage value or current value of the test signal and sets the increment value (eg voltage value or current value) between the measurement points. Set. In this case, the CPU (computer) incorporated in the device characteristic measuring apparatus obtains the number of actually measurable points from the range of the voltage value or the current value of the test signal and the increment value between the measurement points, and the numerical value is obtained. It is known to display on the screen.
The number of measurement points is literally the number of points measured, and is determined by the range of the test signal (from the measurement start value to the measurement end value) and the increment value of the test signal between each measurement, and the It indicates the degree. Therefore, the user can adjust the number of measurement points by setting the increment value in consideration of the required measurement accuracy and the desired measurement time, etc., and display the characteristics at the optimum measurement density. I can.

[0004]

However, in such a conventional device characteristic measuring apparatus, the number of measurement points cannot be set directly, so that the set time is required when the measurement is performed at a desired number of measurement points. It may be complicated and complicated. For example, if you are displaying the characteristics at 1000 measurement points and you want to quickly obtain rough measurement results at 200 measurement points by changing the device settings, set the increment value to any value. If it is difficult to calculate whether the desired number of measurement points is reached or not, it is necessary to reduce the number of measurement points from 1000 to 200 even when adjusting the number of measurement points by sequentially adjusting the increment value using a dial or the like. Since the dial must be continuously rotated for a considerable time, there is a problem in that quick measurement cannot be performed.

Therefore, an object of the present invention is to directly input an arbitrary number of measurement points in the entire measurement range without having to set an increment value of a test signal between measurement points to be continuously measured, It is an object of the present invention to provide a measuring method of an element characteristic measuring device capable of quickly and automatically executing measurement with optimum accuracy.

[0006]

SUMMARY OF THE INVENTION The present invention provides data of a measurement point defined by a value of a test signal of voltage or current supplied to a device under test and a value of current or voltage of the device under test at that time. The value of the test signal is sequentially changed to obtain for a plurality of measurement points, which is a measurement method of an element characteristic measuring apparatus that displays the characteristics of the element under measurement on the screen based on the data of these plurality of measurement points, It consists of the following steps. (1) Calculate the theoretical value of the increment value between the measurement points of the test signal based on the set number of measurement points and the start value and end value of the test signal. (2) Obtain the settable increment value of the test signal that is closest to the theoretical value of the increment value. (3) Calculate and display the number of actual measurable points from this actually settable increment value.

[0007]

[Operation] When the user directly sets the number of measurement points, the theoretical value of the optimum increment value according to the set number is calculated, and the settable increment value that is the closest to this value is used to set the value. The actual number of measurement points is automatically and quickly set to the same value as the number of measured points or the closest value.

[0008]

FIG. 2 is a block diagram showing the configuration of an embodiment of an element characteristic measuring apparatus suitable for using the measuring method of the present invention. CPU (central processing unit) 100 is a bus 102
Program data in a ROM (Read Only Memory) 104 or input data by an operation of the input device 106, and the bus 10 according to these data.
Control other building blocks via 2. Input device 10
4 is an operation panel having push buttons and control knobs,
An input device that combines a display screen and a push button for selecting an item, or a touch screen that uses the display screen or other well-known input device may be used. The measurement circuit 108 is a CPU
It includes at least three measuring units controlled by 100 to function as a variable voltage source, a variable current source, a voltage measuring circuit and a current measuring circuit and control grounding or opening of the measuring terminals. Under the control of the CPU 100, the measurement circuit 108 supplies a test signal to the DUT (device under test) 110 from the output terminal of the first set. In FIG. 3, DUT1
Reference numeral 10 denotes a bipolar transistor. For example, in order to measure the collector-emitter voltage VCE-collector current IC characteristic of this transistor, a constant voltage is supplied to the collector, a stepped bias current is supplied to the base, and the emitter is grounded. . As a result, the X and Y analog signals corresponding to VCE and IC, respectively, are output from the second set of output terminals of the measuring circuit 108 for each step of the bias current.

ADC (analog / digital converter) 11
2 is a clock generator 1 controlled by the CPU 100
At the timing of the sampling clock fs from 14, the X and Y analog signals are converted into X and Y digital data, respectively. The X and Y digital data from the ADC 112 is address-controlled by the CPU 100 and stored in the memory 116. The display control circuit 118 displays the characteristics of the DUT 110 on the display device 120 such as a cathode ray tube based on the X and Y digital data read from the memory 116 based on the horizontal axis data and the vertical axis data, respectively. In the example of this block diagram, the DUT 110 is a bipolar transistor, and the display characteristics are, for example, collector-emitter voltage VCE-collector current IC.
Display the characteristics of. In such an element characteristic measuring device, in addition to this characteristic measurement, the function of each measuring unit connected to each terminal of the DUT 110 is independently controlled to obtain I
Various characteristics such as CBO-VCBO characteristics, β-IC characteristics, IC-VBE characteristics can be measured and displayed.

FIG. 3 is a diagram showing a display example of measurement results of the device characteristic apparatus of FIG. In this case, the characteristic curve is displayed in the graph display area that occupies most of the screen, and the setting information related to this measurement operation is displayed in the auxiliary display area below the screen. In the graph display area, the horizontal axis represents the emitter-collector voltage VCE of the transistor, and the vertical axis represents the collector current IC. A stepped bias current is supplied to the base of the DUT transistor, and the voltage-current characteristic is measured at each step. Since the display of "STEPS" displayed in the auxiliary display area on the lower side of the display screen is "5", it can be seen that the step-like bias current of 5 steps is supplied to the DUT. In the display on the left side of this "STEPS" display, select "LP
"U:" is displayed on the measurement unit (Low Powe) that supplies a stepped bias current to the base of the transistor (DUT).
r Unit) setting, the start value (START) of the stepped current is 0.0000 μA, and the end value (STOP)
Is 10.000 μA, and the increment value (INCREM
ENT) is 2.000 μA. In the display just above that, the display of "HPU:" indicates the setting of the measurement unit (High Power Unit) that applies a voltage to the collector of the transistor, and the start value is 0.00 mV and the end value is 1.0 mV.
000 V and the increment value are 10.00 mV. These setting values are
It can be arbitrarily set within the allowable range by using the keyboard of the input device 106 of FIG.

At the upper right position in the auxiliary area, a numerical value "606" representing the number of actual measurement points is shown together with the display of "ACTUAL POINTS:". The number of 606 represents the number of measurement points at which the measurement is actually performed in the measurement operation during the display of the device characteristic measuring device. The user
Using the keyboard of the input device 106 of FIG. 2, the number of arbitrary measurement points is input in order to execute the measurement operation with desired measurement accuracy. In this case, it is assumed that the numerical value "600" is input. The CPU 100 of FIG.
When the input value of 00 is detected, the theoretical value of the increment value is calculated based on the following formula 1. In addition, DU
The start value of the voltage applied to T is Vstart and the end value is Vsto
p, the theoretical value of the increment value is ΔVth, the number of steps is Ns, and the number of measurement points input by the user is Np.

[0012]

## EQU1 ## ΔVth = (Vstop−Vstart) (Ns + 1) /
(Np-Ns-1)

Here, Vstop = 1000 mV, Vstart
= 0 mV, Ns = 5, Np = 600 is calculated, and the theoretical value of the increment value ΔVth = 10.101 m
V is obtained. The CPU 100 obtains a settable increment value that is closest to the theoretical value of this increment value. In this case, the minimum adjustment resolution of the increment value of the voltage applied to the DUT is 0.25 mV. Theoretical value 1
The increment value that can be set between 0.101 mV is
The values are 10.25 mV and 10.00 mV, and the closest value is 10.00 mV. Therefore, 10.00 mV is selected as the actually set increment value ΔVactual. From the theoretical value ΔVth of this increment value, the number Np (actual) of measurement points at which the measurement operation is actually executed is calculated according to the following mathematical expression 2.

[0014]

## EQU00002 ## Np (actual) = (Ns + 1) (Vstop-Vstart
+ ΔVactual) / ΔVactual

As a result of this calculation, Np (actual) = 606 is obtained, and "606" is displayed as the actual number of measurement points, as shown in FIG. In addition, although the characteristic curves displayed in the graph display area are apparently five,
Actually, six are displayed. The measuring unit LPU which supplies the step-like bias current has a starting value of 0 μA to
Since the increment value of μA is sequentially increased over 5 steps and the end value reaches 10 μA, 0, 2, 4, 6,
Six current values of 8 and 10 μA are taken, and characteristic curves corresponding to these six current values are displayed. The characteristic curve when the bias current is 0 μA is displayed on the horizontal axis so that it is difficult to recognize in FIG. 3, but the characteristic curves corresponding to other bias currents are 5 in order from the bottom.
Note that the steps are displayed. After all, since 606 measurement points are measured for the 6 characteristic curves, each characteristic curve includes 101 measurement points. In addition, like a diode, D with 2 terminals
In the case of UT, since the measurement with the step-like bias current is not performed, the number of steps is irrelevant to the measurement, and only one characteristic curve is displayed.

FIG. 1 is a flow chart showing the procedure of an embodiment of a measuring method of the device characteristic measuring apparatus of the present invention. First, in step 10, the CPU 100 reads the data of the start value, the end value, the increment value of the test signal and the number of steps of the step bias signal (only when necessary) from the register in which they are stored. These data are
It is either an initial value (default value) when the element characteristic measuring apparatus is started when the power is turned on, a value input by the user from the input device 106, or a value calculated by the measuring method of the present invention. In the next step 12, the actual number of measurement points is calculated from the read data and displayed. Only the processing of steps 10 and 12 described above is conventionally performed except that the value calculated by the method of the present invention is used, and is a technique well known to those skilled in the art.

The present invention is characterized in that the user can directly set the number of measurement points in step 14 and subsequent steps. That is, in this step 14, the setting data of the number of measurement points is monitored to detect whether or not the user directly changes the setting value. When the number of measurement points is changed (Yes), the process proceeds to step 16 and the theoretical value (for example, ΔVth) of the increment value of the test signal is calculated according to the above-mentioned formula 1. In the case of the above-described embodiment, the number of measurement points Np directly set by the user is "600", and the start value Vstart and the end value Vstop of the voltage test signal are each 0.00 m.
Since A and 1.000V, as described above, ΔVth =
It becomes 10.101 mV. In the next step 18, a settable increment value ΔVactual that is closest to the theoretical increment value ΔVth is obtained and stored. here,
As described above, ΔVactual = 10.00 mV is set. The reason why the actual setting value is calculated from the theoretical value of the increment value is that if the theoretical value of the increment value is a value that can be actually set, the number of measurement points set by the user can be measured, but it can actually be set. This is because the increment value has a limitation in the adjustment resolution, so that it is not always possible to perform measurement with the number of measurement points equal to the number set by the user. In the next step 20, it is judged whether or not the measurement by the device characteristic measuring device is completed, and when it is completed (Yes), this process is completed. If not completed (No), the process returns to Step 10 to read the newly set increment value (ΔVactual) and other data values. In the next step 12, the actual number of measurement points is calculated and displayed by the above-mentioned formula 2. The number of measurement points is “606” in the above example. If it is determined NO in step 14, the process jumps to step 20 and the number of measurement points is not changed.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described herein, and various modifications and changes can be made as necessary without departing from the gist of the present invention. It will be apparent to those skilled in the art that changes can be made. For example, the example of the voltage signal has been described as the test signal, but it is needless to say that the measurement point can be directly set in the case of the current signal as well.

[0019]

According to the measuring method of the device characteristic measuring apparatus of the present invention, the user can directly input the number of measuring points by taking into consideration the optimum measuring accuracy or measuring time, and Since the number of measurable measurement points that are close to each other can be automatically obtained and displayed, the measurement work with desired measurement accuracy or measurement time can be performed quickly and efficiently. There is no need for the user to reversely set an increment value from a desired number of measurement points to set or to sequentially adjust the increment values to adjust the measurement points as in the conventional case.

[Brief description of drawings]

FIG. 1 is a flow chart showing a procedure of an embodiment of a measuring method of the present invention.

FIG. 2 is a block diagram showing a basic configuration of an element characteristic measuring apparatus suitable for adopting the method of the present invention.

FIG. 3 is a diagram showing a display example on a display screen according to the present invention.

[Explanation of symbols]

 100 CPU 106 Input Device 108 Measurement Circuit 110 DUT 112 ADC (Analog to Digital Converter) 116 Memory 120 Display Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Hosoi 5-931 Kitashinagawa, Shinagawa-ku, Tokyo Sonny Tektronix Co., Ltd. Yoshiyuki Shimonaka (56) Reference JP-A-58-100760 ( JP, A) JP-A-4-16734 (JP, A) JP-A-2-45778 (JP, A)

Claims (2)

[Claims] 1. Data of measurement points respectively defined based on the value of a test signal of voltage or current supplied to the device under test and the value of current or voltage of the device under test at that time In the measuring method of the element characteristic measuring device, which sequentially changes the value and obtains a plurality of the measuring points, and displays the characteristics of the measured element on the screen based on the data of the plurality of measuring points, the setting of the measuring points The theoretical value of the increment value between the measurement points of the test signal is calculated based on the number and the start value and the end value of the test signal, and the settable increment value of the test signal closest to the theoretical value of the increment value. And calculate the number of actual measurement points that can be measured from the settable increment value, and calculate the actual measurement point that can be measured. Method of measuring element characteristics measurement apparatus and displaying the number of. 2. Data of a measurement point defined based on the value of the test signal of the voltage or current supplied to the device under test and the value of the current or voltage of the device under test at that time are used as the value of the test signal. In the measuring method of the device characteristic measuring device for displaying the characteristics of the device under test on the screen based on the data of these plural measuring points, by setting the number of setting of the measuring points. The theoretical value of the increment value between the measurement points of the test signal is calculated based on the start value and end value of the test signal, and the number of steps of the step-like bias signal supplied to the device under test. Of the test signal that is closest to the theoretical value of The method for measuring an element characteristic measuring device, comprising: calculating the number of the measurement points and displaying the actual number of measurable measurement points.