JPH03107772A - Resistance measuring device - Google Patents

Abstract

PURPOSE:To attain a measurement in nondestructive condition by placing a pressure sensitive conductive sheet on a sample to be measured and bringing more than four electrodes held by electrode holding plates into pressurized contact with the sample to be measured together with the pressure sensitive conductive sheet. CONSTITUTION:One surface of the pressure sensitive conductive sheet 3 is abutted to the plate-shaped sample A to be measured to make the part applied with a pressure in the thickness direction to be a conductive state. By the insulated electrode holding plates 2 confronted with the other surface of this sheet 3 keeping a specified space S, more than four electrodes 21-24 projecting into the space S from the surface are held. These holding plates 2 and the sheet 3 are brought into contact with pressure to the sample A by a pressure applying plate 5 and a pressing force with contact is given. Then, the pressurized parts with contact of electrodes 21-24 applied with pressure come into the conductive states and a current flows to the sample A from two electrodes, then a potential generated between other two electrodes is detected and the resistance is measured. In this case, the sheet 3 is required to contain conductive particles with 1-100mum diameter in 5-20 cubic % and the thickness of sheet is required to be 0.1-2mm, for the purpose of forming a conducting path at the time of pressurized contact.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a resistance measuring device, and in particular, a method for non-destructively measuring the resistance of a flat sample such as a wafer having an ion-implanted layer, a transparent electrode sheet, or a thermal head. The present invention relates to a device suitable for measurement.

[Prior Art] In the development of semiconductor devices, etc., the electrical characteristics of the formed device may deviate from the designed values due to changes in the resistivity of silicon, etc. during the thermal process of the wafer. To monitor this, the resistivity of the ion-implanted layer is measured.Normally, this measurement is performed using the so-called four-probe method, in which a metal needle probe is placed against the sample to be measured. When measuring by pressing and measuring at multiple points, after measuring one point, turn the probe from the point to be measured and move the probe to the next point to be measured. The procedure of aligning the probe, pressing the probe against the point to be measured, and then performing measurement was repeated.

[Problems to be Solved by the Invention] This four-probe method has the advantage of being easy to measure and can provide highly accurate measurement results, but on the other hand, the metal needle probe described above has a sharp tip. Therefore, there was a problem in that it was inevitable that the surface of the square, which was the sample to be measured, would be damaged. For these reasons, the conventional method has a problem in that it cannot be used for evaluation in the manufacturing process except for measuring parts for monitoring.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a resistance measuring device capable of non-destructively measuring resistance without damaging the surface of a sample to be measured.

[Means for Solving the Problem] In order to achieve the above object, the resistance measuring device of the present invention has the following features:
One side is brought into contact with a flat plate-shaped sample to be measured, and the particle size is 1~
A pressure-sensitive conductive sheet containing 5 to 20% by volume of 200μ-tone conductive particles and having a thickness of 0.1 to 2IIII and whose portion becomes conductive when pressure is applied in the thickness direction, and the pressure-sensitive conductive sheet an insulating electrode holding plate facing the other side of the sheet and provided with a predetermined gap; and four or more electrode holding plates held by this electrode holding plate and protruding from the surface of the electrode holding plate within the above distance. An electrode, a pressure-contact force applying means for press-contacting the electrode holding plate together with the pressure-sensitive conductive sheet to the sample to be measured and applying a pressure-contact force, and a resistance using four of the four or more electrodes. The method is characterized by comprising a measuring means for measuring.

[Function] According to the present invention, a pressure-sensitive conductive sheet plate is placed on the sample to be measured, and four or more electrodes held on the electrode holding plate are placed on the sample to be measured together with the pressure-sensitive conductive sheet. Pressed against the sample.

Then, the portion of the pressure-sensitive conductive sheet to which pressure is applied, that is, the portion where four or more electrodes are in pressure contact, becomes conductive. Therefore, the resistance is measured by passing a current through the sample to be measured from two of the electrodes and detecting the potential difference generated between the other two electrodes.

Therefore, measurement can be performed without causing any damage to the surface of the sample to be measured, that is, in a non-destructive state.

[Example] Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a cross-sectional view showing an embodiment of a resistance measuring device using a four-probe method for measuring a flat plate-shaped sample according to the present invention. This stage is made of an insulating material such as resin. Stage 1 is fixed to a main frame (not shown). 2 is an insulating probe electrode holding plate made of resin such as epoxy resin, polyester, polyimide, or a composite material of these with glass fiber or inorganic filler, or glass or ceramic; The measuring electrodes, which are provided with two electrodes 21, 22, 23 and 24, can also be formed on the electrode holding plate 2 by means of rivet-like conductors or by plating, etching, vapor deposition, printing or the like. Below the electrode holding plate 2, there is a pressure sensitive conductive sheet 3 which becomes conductive in the thickness direction when pressure is applied in the thickness direction. It is kept in the same state. and,
The tips of the four electrodes 21, 22, 23 and 24 mentioned above are between! +IS protrudes into the inside and is in contact with the pressure-sensitive conductive sheet 3. The upper side of the electrode holding plate 2 includes wiring to four electrodes 21, 22, 23 and 24, and is covered with an insulating resist 25 such as epoxy resin.

Further, the electrode holding plate 2 is connected to an elastic plate 4 made of foamed polyurethane or foamed rubber for uniformly applying pressure, with an insulating resist 25 interposed therebetween, and the elastic plate 4 is connected to a pressure plate 5. . The pressure plate 5 is held by a rod 51 that is vertically movably supported by a main frame (not shown), and the rod 51 is connected to a piston of an air cylinder (not shown).

6 is a power supply, and in this embodiment, among the four electrodes mentioned above,
The electrodes 21% 24 at both ends are connected by a wiring 63 with a resistor 61 and an ammeter 62 interposed therebetween. Reference numeral 7 denotes a voltmeter, which is connected to the electrodes 22 and 23 by wiring 71.

The material of the pressure-sensitive conductive sheet 3 used in the present invention is, for example, an elastomer made by mixing conductive particles into an insulating elastic body, and the conductive particles are mainly arranged in the pressure contact direction to form a conductive path. be able to. Insulating elastic materials include silicone rubber, urethane rubber, neoprene rubber,
Examples of the conductive particles include acrylic rubber, polybutadiene rubber, butyl rubber, polyisoprene rubber, fluororubber, and phosphazene rubber. Metal particles and those plated with precious metals,
Examples include polymer particles such as polystyrene and inorganic particles such as zirconia, alumina, silica, and titania plated with noble metals. Further, it is necessary that the conductive particles have a particle diameter in the range of 1 to 200 μ-.

When the particle size is less than 1 μm, it becomes difficult to obtain a sufficient contact state for measurement. Also, if it exceeds 200 μ■,
There is a risk of damaging the sample to be measured.

Moreover, the pressure-sensitive conductive sheet 3 has a thickness of 0.1 to 21 m.
Furthermore, it is necessary for the mixed amount of conductive particles to be 5 to 20% by volume in order to form a conductive path during pressure bonding, and the hardness is preferably 20 to 55 (JIS-AHs). As the piezoconductive sheet, for example, JSR PCR 305-02 manufactured by Nippon Synthetic Rubber Co., Ltd. can be used.

When measuring the resistivity or sheet resistance of such a wafer using the above-mentioned resistance measuring device, first stage 1
Place wafer A on top. Then, the pressure plate 5 including the electrode holding plate 2 is lowered using an air cylinder (not shown) or the like.
The pressure-sensitive conductive sheet 3 and the surface of the wafer A are brought into contact with each other and pressurized, for example, until the gap S between the electrode holding plate 2 and the pressure-sensitive conductive sheet 3 disappears, whereby the pressure-sensitive conductive sheet 3 The respective electrodes are electrically connected via the wafer A and the wafer A. At this time, the pressing force applied to the pressure-sensitive conductive sheet is usually 5 to 1000 g/am', preferably 10 to
500g/ss" using an air cylinder, etc.

Adjust the pressure. If the contact force is less than 5 g/mm, sufficient conductivity necessary for measurement cannot be obtained, and too much
If it exceeds og/■■2, the wafer A, which is the sample to be measured, will be damaged.

Thus, while the current is measured with the ammeter 62 while the pressure contact force is applied, the potential difference generated between the electrodes 22 and 23 is detected with the voltmeter 7.

In addition, in the resistance measuring device according to the present invention, the electrodes are 4
If more than one is installed, a scanner etc. will be used to check the
means for selecting four predetermined electrodes from a group of electrodes, passing a current between any two of these electrodes, measuring the voltage between at least two other electrodes, and then sequentially measuring the voltage by switching the electrodes; You can prepare.

This enables high-speed switching between electrodes for current flow and electrodes for measuring voltage using a scanner, etc., without having to repeatedly separate, move, and pressurize the pressure-sensitive conductive sheet, electrode, etc. from the sample to be measured. Measurements can be taken.

Furthermore, the resistance measuring device according to the present invention has a spreading resistance (
This method can be applied to the Spreading Re5fstance method. This is done by using one electrode of the resistance measuring device of the present invention, and using the voltage and current values applied between the electrode and another electrode placed on the back side of the sample to be measured, as well as the value of the diameter of the electrode. This is a method of measuring This method is
The resolution is determined by the diameter of the electrode, but it is possible to measure resistance in a very narrow area.

(Experiment Example 1) Using a measuring device as shown in Fig. 1, as a sample to be measured, as shown in Fig. 2, length x width (axb) - 4 hv x 40
4000mm thick Sn formed on i+m glass plate
The resistance of the transparent electrode for liquid crystal made of ow was measured at 15 points (■ to ■) as shown in FIG. The electrode holding plate 2 is provided with an electrode having a diameter of 0.81 at the tip that contacts the pressure-sensitive conductive sheet 3, and the elastic plate 4 is made of a commercially available thickness of 1.
A 0 mm foamed rubber plate was used.

The results thus obtained are shown in Table 1.

As is clear from Table 1, the average sheet resistance value of the 15 points measured was 9.0 (Ω/mouth), and the sheet resistance of the bottom three points ■, [phase], and [phase] was large. It turned out that it was. 10.0 in conventional 4-probe method measurement
(Ω/mouth) was obtained by measuring the end portion of the sample to be measured, and the value is very close to that of the measured sample. Moreover, in this experimental example, no damage was observed on the surface of the sample to be measured.

(Leaving space below) Kazuo Sato (Experiment Example 2) Next, using the measuring device shown in Figure 1 and under the same conditions as Experiment Example 1, the sample shown in Figure 4 was measured. 6 x
The resistance of the metal thin film (TaJ) provided on the thermal head of b = 270mm x 4B+++m was measured at 8 points in the horizontal direction A to H and 1 in the vertical direction, as shown in Figure 5.
303 points, a total of 24 points.

The sheet resistance (Ω/unit) measurement results obtained in this way are shown in Table 2. / As is clear from Table 2, the results are similar to those of the conventional four-probe method measurement. The sheet resistance of the value is obtained. Furthermore, in this experimental example, no damage was observed on the surface of the sample to be measured.

(Leaving space below) Table 2 (Experimental Example 3) Furthermore, using the measuring device shown in Figure 1 and under the same conditions as Experimental Example 1, the sheet resistance (Ω/hole) of a silicon wafer as a sample to be measured was measured. I did it.

The diameter of the tip of the electrode of the measuring device is 0.8 mm. As a comparative example, a conventional four-probe method using a metal needle probe was also conducted. The results are shown in Table 3.

As is clear from Table 3, it can be seen that even in the case of silicon wafers, values almost close to those obtained by conventional four-probe measurement can be obtained. In this case, it was confirmed that no damage occurred to the surface of the silicon wafer.

(Experimental Example 4) Furthermore, using the measuring device shown in Figure 1 and under the same conditions as in Experimental Example 1, boron was implanted and annealed on a silicon wafer as a sample to be measured under each condition shown in the table. The resistivity of the active layer was measured. The diameter of the tip of the probe of the measuring device is 0.8 mm. As a comparative example, conventional four-probe measurement using a metal needle probe was also conducted. The results are shown in Table 4, where the temperature in the table is the annealing temperature (C°C).

(The following is a blank space) 5-2 Collective resistivity (0 cm) As is clear from Table 4, values almost close to those of the conventional four-probe measurement were obtained in this example as well.

In addition, when measuring the sheet resistance of a silicon wafer having an ion-implanted layer, the dose (DO3 amount 10"(cm-")
The above is the limit because destruction of the layer to be measured occurs, but in measurement using the device according to the present invention, the dose amount 1
It was confirmed that measurement of 0''(cab-') is also possible.

(Effects of the Invention) As is clear from the above explanation, the resistance measuring device of the present invention uses the above-described predetermined pressure-sensitive conductive sheet to measure flat samples such as wafers, transparent electrodes, and thermal heads. Since the resistance is measured, it is possible to perform the measurement in a non-destructive state without damaging the sample to be measured, which facilitates the development of various devices and improves productivity.

Furthermore, the resistance measuring device according to the present invention has a simple structure and is advantageous in terms of cost.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the resistance measuring device according to the present invention, Fig. 2 is a perspective view showing an example of the shape of a transparent electrode as a sample to be measured, and Fig. 3 is an example of the point to be measured. Similarly, FIG. 4 is a perspective view showing an example of the shape of a thermal head as a sample to be measured, and FIG. 5 is a plan view showing an example of a point to be measured. DESCRIPTION OF SYMBOLS 1... Stage, 2... Electrode holding plate, 3... Pressure-sensitive conductive sheet, 4... Elastic plate, 5... Pressure plate, 21.22, 23.24... Electrode. Powerless bow ξ power “powerless person 6.7℃9 town father-in-law*1===-pu(
Kahii door 1 right, not shown, h A, 1st figure, 8th electric layer -- cedar house, increasing slope, A, 2nd figure, 1 km long, deaf, -- 1 row north, 1,000 yen. B 3rd
figure

Claims (1)

[Scope of Claims] 1) One surface is in contact with a flat plate-shaped sample to be measured, contains 5 to 20% by volume of conductive particles with a particle diameter of 1 to 200 μm, and has a thickness of 0.1 to 2 mm. a pressure-sensitive conductive sheet whose portion becomes conductive when pressure is applied in a direction; and an insulating electrode holding plate facing the other surface of the pressure-sensitive conductive sheet with a predetermined gap therebetween. and four or more electrodes held by this electrode holding plate and protruding from the surface of the electrode holding plate within the interval, and pressing the electrode holding plate together with the pressure-sensitive conductive sheet against the sample to be measured. A resistance measuring device comprising: a pressing force applying means for applying force; and a measuring means for measuring resistance using four of the four or more electrodes.