JP3276389B2 - Voltage 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 voltage measuring device, and more particularly to a device for measuring a voltage of a fine wiring having a line width of several hundred nm or less inside an integrated circuit.

[0002] With the increase in integration and speed of integrated circuits,
In this operation test, it may be necessary to measure the voltage of fine wiring inside the integrated circuit.

For this purpose, it is necessary to bring the probe into contact with the fine wiring with high precision. Furthermore, it is necessary to be able to cope with a high frequency band.

[0004]

2. Description of the Related Art A conventional voltage measuring apparatus has a structure in which a voltage probe is provided on a tungsten probe and a moving mechanism for moving and positioning the probe is provided.

[0005]

This voltage measuring device is:
The probe is used in contact with a pad, and the minimum wiring to be measured is limited to a width of about several μm, depending on the size of the tip of the probe and the accuracy of the moving mechanism.

Further, since the voltage value acquisition circuit section has a general configuration using electronic components, the frequency band is also limited to several MHz.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a voltage measuring device which can measure a voltage of a fine wiring inside an integrated circuit.

[0008]

According to the first aspect of the present invention, a cantilever, a cantilever supporting portion for supporting a base portion of the cantilever, and a probe at the tip of the cantilever constitute a part of an atomic force microscope. The probe has a configuration in which the cantilever and the probe are electrically conductive, and the probe is provided with a voltage value acquisition circuit unit. A voltage measuring point is determined, and then the probe of the probe is brought into contact with the fine wiring to measure a voltage through the voltage value acquiring circuit section.

According to a second aspect of the present invention, the voltage value acquiring circuit of the first aspect has an integrated structure.

[0010]

According to the first aspect of the present invention, the probe of the atomic force microscope in which the probe is conductive acts so that the function of the atomic force microscope can be used to position the probe at the voltage measurement position. , So as to enable contact with the fine wiring.

The structure in which the voltage value acquisition circuit section is integrated and disposed near the probe acts to reduce the capacitance of the signal transmission path.

[0012]

FIG. 1 shows a voltage measuring apparatus according to an embodiment of the present invention.

The voltage measuring apparatus 1 has a structure obtained by adding a voltage measuring function to an atomic force microscope. The voltage measurement function
It is mainly provided by making the cantilever and the probe of the probe conductive.

Reference numeral 2 denotes an atomic force microscope, which has the same configuration as a general atomic force microscope except for a probe, and includes a probe 3, a displacement sensor 4, a fine movement mechanism 5, an AD converter 6, a computer 7, and a display. Device 8, operation panel 9, and stage 10
Etc.

The voltage measuring apparatus 1 has a configuration in which a trigger generator 11, a delay circuit 12, and the like are added to the above-mentioned atomic force microscope 2.

As shown in an enlarged manner in FIG. 2, the probe 3 includes a cantilever 13 made of Au and this cantilever 1.
Si cantilever support 14 for supporting the base of 3
And a W-shaped probe 15 at the tip of the cantilever 13 and an integrated voltage acquisition circuit 16 on the lower surface of the cantilever support 14.

The cantilever 13 has a length L of about 200 μm.
m, and the spring constant is 1 N / m or less.

The tip 15a has a tip 15a having a radius of 0.1 μm.
m or less, sharp enough, and only a few tens of nanometers wide
It is possible to normally contact a fine wiring of only m.

Both the probe 15 and the cantilever 13 have conductivity.

As shown in FIG. 3, the voltage value acquiring circuit 16 has a structure in which a sample and hold circuit 19 having a switch 17 and a capacitor 18 and an amplifier 20 at the next stage are integrated.

Next, using the above-mentioned voltage measuring device 1, I
Regarding the operation of measuring the voltage of the wiring on the surface of the C chip,
This will be described with reference to FIG. First, the IC chip 21
Is mounted on the stage 10 and fixed (step 30).
On the surface of the IC chip 2, as shown in FIG.
2 _-1 , 22 _-2 , 22 _-3 ... are formed. This line width W is as narrow as several hundred nm. Assume position P ₁ is a voltage measurement position.

Next, a voltage measuring point is determined (step 3).
1).

The probe 3 is used as a probe of the atomic force microscope ₂ to detect the fine wiring _22-2 on the IC chip 2, and then the probe 15 is opposed to the position P ₁ .

More specifically, the probe 3
Is moved so that a part of the surface of the IC chip 2 is scanned close to the surface.

At this time, the deflection of the cantilever 13 on the order of nm due to the pressure generated at the probe 15 is detected by the displacement sensor 4.
The output is processed by the computer 7 via the AD converter 6, and an image 23 (FIG. 6) of the portion scanned by the probe 15 is obtained on the display device 8, and the fine wiring _22-2 is detected. You.

[0026] Then, by operating the operation panel 9, on the image 23, sets the position P _1a corresponding to the position P ₁ of the.

[0027] Thus, the fine movement mechanism 5 is driven, the probe 3 is moved, the probe 15 is opposed to the position P ₁ on the fine wire _22-2.

Here, the fine movement mechanism 5 has a structure using a piezoelectric element, and can control the position of the probe 3 on the order of nm. Thus, the probe 15 is accurately positioned to face the position P _1.

Next, the probe 3 by small downward, contacting the probe 15 to the position P ₁ on the wiring pattern _22-2 (step 32).

As described above, since the tip of the probe 15 is sufficiently thin and the probe 15 is positioned with high accuracy, the probe 15 contacts the position P ₁ on the wiring pattern 22 with high accuracy.

Subsequently, a voltage is obtained by using the probe 3 as a voltage obtaining probe (step 33).

More specifically, in FIG.
Generates a trigger indicated by reference numeral 35 in FIG.

On the other hand, the trigger 35 is
, The voltage at the position P ₁ of the fine wiring _22-1 rises as indicated by reference numeral 36.

On the other hand, the trigger 35 is delayed via the delay circuit 12 having a delay time t ₁ . The delayed trigger 35a is applied to the voltage value acquisition circuit unit 16 in the probe 3 via the line 25 and to the AD converter 6 via the line 26.

In the voltage acquisition circuit section 16 of FIG. 3, the switch 17 is closed by the trigger 35a,
In the meantime, the voltage V ₁ is read and sampled and held, and the voltage V ₁ is amplified through the amplifier 20 and supplied to the AD converter 6 through the line 2.

In the AD converter 6, the voltage V ₁ is sampled by a trigger 35 a applied via a line 26, converted into a digital signal, processed by the computer 7, and displayed on the display device 8.

As described above, the fine wiring 2 of the IC chip 21
Voltage position P ₁ of 2 _-2 is measured.

Here, since the voltage value acquisition circuit section 16 is integrated and disposed near the cantilever, the signal transmission path is very short, so that the capacitance of the transmission path is considerably small.

For this reason, the voltage can be measured up to a signal having a higher frequency than the conventional one, for example, a signal having a high frequency of several GHz or more.

In FIG. 2, 27 is a power supply line, and 28 is a ground line.

Next, a method of manufacturing the probe 3 of FIG. 2 will be described with reference to FIGS.

First, as shown in FIG. 1A, an Au film pattern 41 (which becomes the cantilever 13) is formed on the upper surface of the Si substrate 40.

Next, as shown in FIG. 2B, the voltage value acquisition circuit section 16 is integrated and formed on the upper surface of the Si substrate 40 by a semiconductor manufacturing technique.

Next, as shown in FIG. 4C, a protective film 42 is formed on the surface, and the W probe 15 is attached to the Au film pattern 4.
Attach and attach to one end with a conductive adhesive.

Finally, as shown in FIG. 2D, the portion of the Au film pattern 41 of the Si substrate 40 is removed by etching or the like.

Thus, the probe 3 shown in FIG. 2 is manufactured.

Next, a modified example of the probe 3 will be described with reference to FIG.
This will be described with reference to FIG.

In each of the figures, substantially the same parts as those of the probe 3 shown in FIG. 2 are denoted by the same reference numerals.

The probe 3A of FIG. 9 has a configuration in which an integrated voltage value acquisition circuit section 16A is provided on the cantilever 13.

According to this configuration, the signal transmission path can be effectively shortened, and the capacitance of the signal transmission path can be reduced.

The probe 3B of FIG. 10 has a configuration in which an integrated voltage value acquisition circuit section 16B is provided on the upper surface of the cantilever support section 14.

In FIGS. 9 and 10, reference numeral 43 denotes a conductive film.

[0053]

As described above, according to the first aspect of the present invention, it is possible to measure the voltage of a fine wiring formed on the surface of an IC chip.

According to the second aspect of the present invention, a high-frequency voltage of several GH or more can be measured.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a voltage measuring device of the present invention.

FIG. 2 is an enlarged perspective view of a probe in FIG.

FIG. 3 is a circuit diagram of an integrated voltage value acquisition circuit unit in FIGS. 1 and 2;

FIG. 4 is a diagram showing a procedure of voltage measurement by the device of FIG. 1;

FIG. 5 is a diagram showing fine wiring on an IC chip.

FIG. 6 is a view showing an image of the fine wiring of FIG. 5 obtained by an atomic force microscope.

FIG. 7 is a diagram illustrating voltage acquisition.

FIG. 8 is a diagram illustrating a method of manufacturing the probe of FIG. 2;

FIG. 9 is a view showing a modification of the probe of FIG. 2;

FIG. 10 is a diagram showing a modification of another example of the probe of FIG. 2;

[Explanation of symbols]

Reference Signs List 1 voltage measuring device 2 atomic force microscope 3, 3A, 3B probe 4 displacement sensor 5 fine movement mechanism 6 AD converter 7 computer 8 display device 9 operation panel 10 stage 11 trigger generator 12 delay circuit 13 Au cantilever 14 Si cantilever Supporting part 15 W probe 16 Integrated voltage acquisition circuit part 17 Switch 18 Capacitor 19 Sample hold circuit 20 Amplifier 21 IC chip _22-1 , 22 _-2 , 22 _-3 Fine wiring 23 Fine wiring image 30 to 33 Step 40 Si substrate 41 Au film pattern 42 Protective film 43 Conductive film

Continuation of front page (72) Inventor Yoshiro Goto 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-5-223855 (JP, A) JP-A-4-330752 (JP, A) JP-A-5-102272 (JP, A) JP-A-4-72505 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/66 G01R 1/073 G01R 31 / 26

Claims (2)

(57) [Claims] 1. A cantilever (13) which forms part of an atomic force microscope (2), a cantilever support (14) for supporting a base of the cantilever, and a probe (15) at the tip of the cantilever. The cantilever (13) and the probe (15) of the probe (3) are made conductive, and the probe is provided with a voltage value acquisition circuit section (16). A voltage measuring point on the fine wiring is determined by using the probe as an atomic force microscope, and then the probe of the probe is brought into contact with the fine wiring to measure a voltage through the voltage value acquiring circuit. Voltage measuring device. 2. A voltage value acquisition circuit section according to claim 1, wherein:
Is a voltage measuring device having an integrated structure.