JP2668768B2 - Probe device for measuring electrical characteristics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe device for measuring electrical characteristics such as minute current and current capacity of a sample such as a wafer substrate in a process development process in the field of manufacturing semiconductor devices and the like.

[0002]

2. Description of the Related Art In recent years, in the field of manufacturing semiconductor devices, higher integration and ultra-miniaturization have been demanded. In particular, in the memory business, high integration and miniaturization have been unavoidable with the increase in storage capacity. Taking a dynamic random access memory (DRAM) as an example, the capacity is increased by means such as reducing the size of a capacitance and a transistor constituting each bit cell. Therefore, even if a leak current slightly smaller than the capacitance occurs, the bit information is greatly affected and the true value cannot be held, which also affects the refresh cycle time compensation. Therefore, in the process development analysis process in the semiconductor device manufacturing field, evaluation of electrical characteristics such as a minute current and a current capacity of a sample such as a wafer substrate is indispensable.

FIG. 4 shows an outline of the configuration of a system using a manual prober used for such an evaluation test as an example. In the figure, 10 is a shield box for reducing the influence from the outside, 11 in the shield box 10 is a sample stand on which a sample X such as a wafer to be measured is placed, and 13a and 13b are the sample stand 11 The measurement needles 14a and 14b which are brought into contact with the sample X above are manipulators for moving the measurement needles 13a and 13b on the sample X. Further, 14a 'and 14b' are manipulator bases, and 15 is a measurement needle which is brought into contact with the sample X. A measuring instrument for measuring currents and the like input from 13a and 13b outside the shield box, and 16 is a microscope provided above the sample table 11.

In this apparatus, first, a sample X is placed on a sample stage 11.
While manipulating the manipulator 14 while observing it with a microscope 16.
The measurement needles 13a and 13b are moved by using a and 14b, and are brought into contact with a target place of the sample X. After this set,
A minute electrical characteristic of the sample X is measured by a measuring device 15 such as a constant voltage / current ammeter.

[0005]

In the above arrangement, the sample X and the measuring needles 13a and 13b are not connected to the shield box 10a.
Since it is shielded from the outside world by the outside world, it should not be affected by the outside world, but the data actually obtained indicates that the heating / cooling device such as the heater 12 capable of heating / cooling the sample is the sample table 11 itself. In particular, noise N ₁ enters from the heater 12 and the like, and leak I ₂ from the measurement electrode 11a, which is a conductive portion of the sample contact surface of the sample table 11, to the probe station 11f is generated. the voltage drop of the measuring electrodes, and there is a leakage current I ₂ of a certain amount. Therefore, it has been difficult to accurately measure minute electrical measurement data.

The present invention has been made in view of the above problems of the prior art, and can reduce the influence of radio waves from the outside at the time of measurement, and can also reduce noise N ₁ , which is generated from the sample stage 11 itself.
An object of the present invention is to provide a probe device capable of measuring a minute electric characteristic capable of minimizing the effects of N ₂ and leakage currents I ₁ and I ₂ .

[0007]

The inventor of the present invention first measures noises which affect the measurement lines of the measuring needles 13a and 13b, the measuring electrode 11a of the sample stand 11 and the like for the measurement of minute electrical characteristics. _When the causes of ₁ , N ₂ and leaks I ₁ , I _2, etc. were investigated, it was confirmed from the external environment due to capacitive coupling between the conductive substances with electric potential floating around the sample to be measured. induction effect of noise _{N 2} by the sample base 11
Heating and cooling of the sample heating and cooling heaters 12
Influence of noise N ₁ generated from the cooling device, the measurement needle 1
It has been found that leak I ₁ between the measurement line 1 of 3a and 13b and the shield (ground), leak I ₂ between the measurement electrode 11a of the sample stage 11 and the shield, and the like are the causes. Then, as a result of earnest studies on means for reducing such a cause to the minimum, the inventors have come up with a configuration of the present invention described below.

Namely, minute electrical characteristic measurement according to the present invention
The probe device has a triple electrode structure in which an insulator including the measurement electrode on the sample contact surface is inserted in the configuration of the sample table, and a measurement line for connecting the measurement instrument to the measurement electrode is provided. Regarding the configuration, the same triple electrode structure in which an insulator is inserted with the measurement line as the central axis electrode, and the intermediate electrode of the sample stand is connected to the intermediate axis electrode of the measurement line to connect to the measuring instrument for guarding As a result, the measuring device controls the intermediate electrode so that it has the same potential as the measuring electrode via the guard buffer so that the measuring line is not affected, and therefore the leak I ₂ itself disappears. . In addition, the shielding effect is large, and noises N ₁ and N
₂ will also be minimized. On the other hand, the lowermost electrode of the sample stage is connected to the outermost axis electrode of the measurement line and connected to the chassis of the measuring instrument so that the same potential as the chassis of the measuring instrument is established (usually grounded on the measuring instrument side). In this way, the structure of the sample stage has a triple-electrode structure, and the measurement line that connects the measuring instrument to the measurement electrode of the sample stage also has a triple-electrode structure. Electrode and the intermediate electrode are at the same potential) and low
Noise (due to the double shielding effect of the middle electrode and the lowermost electrode) has become possible. The conventional sample stage has a double structure in which an insulator including the measurement electrode on the sample contact surface is inserted, and when the lowermost electrode is connected to the chassis of the measuring instrument, only a single shield effect is obtained and noise is reduced. effect becomes large, and had further a potential difference between the measuring electrode and the lowermost electrode (the ground in the normal measuring instrument side) occurs, leakage I ₂ occurs which depends on the specific resistance of the insulator. In a sample stage provided with a heating device or a cooling device such as a heating / cooling heater, the specific resistance of the ceramic-based insulating material decreases due to a rise in temperature. leak I ₂ increases occurring between. On the other hand, in the present invention, since the guard intermediate electrode is provided with the same potential as that of the measurement electrode by providing the above guard intermediate electrode, no leak occurs even if the specific resistance value of the insulator decreases, In addition, because it is low noise due to the double shield effect,
The ability of the measuring device can be fully exhibited, and measurement of minute electrical characteristics becomes possible.

[0009]

EXAMPLES Specific examples of the present invention will be described below. FIG.
3 to 3 show the configuration of a manual type probe device according to an embodiment of the present invention for measuring a minute electric characteristic of a semiconductor wafer substrate as a sample X. In FIG. 1, reference numeral 10 denotes a shield box for reducing the influence from the outside world, reference numeral 11 in the shield box 10 denotes a sample table on which a semiconductor wafer substrate X to be measured is mounted, and reference numeral 12 denotes a heating built in the sample table 11. Heaters, 13a and 13b
Is a measuring needle which is brought into contact with the wafer substrate X on the sample table 11, and 14a and 14b are manipulators for moving the measuring needles 13a and 13b on the wafer substrate X.
a 'and 14b' are manipulator bases, 15 is a measuring instrument (system 251 / SMU, manufactured by Keithley Co.) for measuring the current and the like input to the measuring needles 13a and 13b brought into contact with the wafer substrate X, and 16 is a sample table 11 is a microscope provided above 11.

In the above structure, the measurement line 1 connected to the measuring device 15 for measuring the current, the current capacity and the like from the measuring needles 13a and 13b is insulated by using the measurement line 1 as the central axis electrode as shown in FIG. It has a triple electrode structure with a body interposed. Among them, the middle axis electrode 1a is connected to the guard of the measuring device 15, and the outermost axis electrode 1b is grounded to the shield box 10 and the chassis of the measuring device 15. It has been confused.

Further, the sample table 11 itself and the measurement line 2 connecting the measuring electrode 11a of the sample table 11 described later and the measuring instrument 15 are also constituted by a triple electrode structure in which an insulator is similarly inserted. There is. That is, as shown in FIG. 3, the conductive portion of the sample contact surface is connected to the measuring line 2 which is the central axis electrode communicating with the measuring instrument 15 as the measuring electrode 11a, and the measuring electrode 11a is connected to the measuring electrode 11a. Insulator 1 between
The intermediate electrode 11c provided with the first electrode 1b interposed therebetween is connected to the intermediate axis electrode 2a of the measurement line 2 and connected to the guard of the measuring instrument 15, and the lowermost electrode provided with the insulator 11d inserted thereunder. The lower electrode 11e is connected to the outermost axis electrode 2b of the measurement line 2 and is connected to the chassis of the measuring instrument 15, and the outermost axis electrode 2b is connected to the shield box 10 and grounded. .

The configuration of the present embodiment described above includes the configuration of the measurement line 1 from the measurement needles 13a and 13b,
Regarding the configuration of the sample stage 11 itself and the configuration of the measurement line 2 connecting the measurement electrode 11a and the measurement device, these were formed into a triple electrode structure in which an insulator was inserted. As a result, the potentials between the central axis electrode and the intermediate axis electrode 1a of the measurement line 1 and between the measurement electrode 11a and the intermediate electrode 11c of the sample stage 11 become the same potential, so that no leaks I ₁ and I ₂ occur, and the intermediate axis electrode 1a and the outermost shaft electrode 1b, and the intermediate electrode 11c and the lowermost electrode 11
Due to the double shielding effect of e, the effects of the noises N ₁ and N ₂ could be reduced to a minimum. Therefore, the measured value of the minute current measured (current capacity etc. can be measured) is not affected by leakage,
It becomes accurate measurement data with little influence of noise. Table 1 below is an example of a minute current measurement that seems to be the most difficult to measure due to the effects of leakage and noise among the measurement items.
The lower limit of the measurable value of the wafer substrate X measured by the conventional configuration and the configuration of the present embodiment is shown.

[0013]

[Table 1]

The micro-current measuring device 15 itself used in this experiment can measure up to 10 femto A or less, but the measuring needles 13a and 13b and the sample table 11 in the conventional structure are provided with an intermediate shaft electrode or an intermediate electrode. Because of the double electrode structure with no insulator interposed, no leakage effect, one or both of the double shielding effect becomes incomplete, and 300 femto A as described above is the lower limit of measurable value became.
On the other hand, in the configuration of the present embodiment, the above-mentioned no leak effect,
Both of the double shield effects were sufficient, and it was possible to measure to near the resolution of the measuring instrument.

[0015]

According to the configuration of the present invention described above in detail, according to the present invention, trial
No occurrence of leakage I _1, I ₂ in the postal board, also double since the shielding effect influences of noise N _1, N ₂ is reduced to a minimum, minute current and current capacity such that accurate and reproducible Can be measured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a manual probe device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a triple electrode structure of a measurement line connected from a measurement needle to a measurement device.

FIG. 3 is an explanatory view showing a configuration of a triple electrode structure of a sample stage and a measurement line connecting a measurement electrode of the sample stage and a measuring instrument.

FIG. 4 is an explanatory diagram showing one configuration of a conventional manual probe device.

[Brief description of reference numerals]

 1, 2 Measurement line 1a, 2a Intermediate axis electrode 1b, 2b Outermost axis electrode 10 Shield box 11 Sample stand 11a Measurement electrode 11b Intermediate electrode 11c Lowermost electrode 13a, 13b Measurement needle 15 Measuring instrument

Continuation of the front page (72) Inventor Akira Morii 1-15-12 Kitakase, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside Vector Semiconductor Co., Ltd. (56) References Hirai 3-95645 (JP, U)

Claims (2)

(57) [Claims] A sample stage on which a sample to be measured is placed;
A probe for contacting the sample on the sample stage, and having an externally connected measuring instrument to evaluate the electrical characteristics of the sample in an electrical characteristic measuring probe device, Regarding the configuration of the measurement line that connects the conductive part of the sample contact surface as the measurement electrode, has a triple electrode structure in which an insulator is inserted including the measurement electrode, and connects the measuring instrument to the measurement electrode , The same triple electrode structure in which an insulator is inserted with the measurement line as the central axis electrode, the intermediate electrode of the sample stage is connected to the intermediate axis electrode of the measurement line to communicate with the measuring instrument for guard, and the sample stage is also used. A probe device for measuring electrical characteristics, wherein the lowermost electrode is connected to the outermost axis electrode of the measurement line and connected to the chassis of the measuring instrument so as to have the same potential as the chassis of the measuring instrument. 2. A probe device for measuring electrical characteristics according to claim 1, wherein a heating device or a cooling device capable of heating or cooling the sample is provided in the configuration of the sample stage. A probe device for measuring electrical characteristics.