JPH02166746A - Measuring apparatus - Google Patents

Abstract

PURPOSE:To decrease variations of electric resistance in measurement and to improve measuring accuracy by forming voltage applying electrodes and voltage measuring electrodes on the surfaces which are obtained by dividing a mounting surface into 2N (N is an integer of 2 or more) surfaces, and forming N pieces of these electrodes alternately on the mounting surfaces. CONSTITUTION:Voltage applying electrodes 2 and applied voltage measuring electrodes 3 comprising, e.g., gold and the like, are formed on a main body 1 of a mounting-table made in a disk shape. The voltage applying electrodes 2 and the voltage measuring electrodes 3 are formed on the surfaces which are obtained by dividing the surface of the mounting-table main body 1 into quadrants. Two electrodes are alternately formed on the surfaces of the mounting-table main body 1. Specified voltages are applied to connector electrodes on the rear surface of a semiconductor wafer from the voltage applying electrodes 2. The applied voltages are measured with the voltage measuring electrodes 3. Since the number of the divisions is more than conventional two divisions, the area of one electrode surface is small. There is a room for selecting the different kind of electrode in the shortest distance. Loss in electric resistance is made less, and the measuring accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a measuring device used for testing and measuring semiconductor chips.

(Prior Art) Of the wafer mounting tables disposed in a probe device and used for testing and measuring semiconductor chips formed on a semiconductor wafer, the following table is used for testing and measuring semiconductor chips such as power transistors, for example. A wafer mounting table called a Kelvin chuck is known.

This type of Kelvin chuck has conventionally been constructed by forming two types of electrodes on the surface of a mounting table main body which is made of, for example, an aluminum alloy and has a disk shape. One of them is a voltage applying electrode, the other is a voltage measuring electrode,
Examples include a configuration in which these two types of electrodes are divided into two parts concentrically or in two parts on the left and right sides on the diameter line.

Then, a predetermined voltage is applied from the voltage application electrode to the collector electrode formed on the back surface of the semiconductor wafer, and a probe needle or the like is brought into contact with the emitter small pole and base electrode formed on the surface of the semiconductor wafer, and test measurements are performed. It is carried out.

Further, the voltage measurement electrode measures the voltage applied from the voltage application electrode to the collector electrode formed on the back surface of the semiconductor wafer.

(Problems to be Solved by the Invention) When testing each semiconductor chip on a semiconductor wafer using the above wafer mounting table, two types of electrodes formed on the wafer mounting table, namely voltage application It is necessary to use electrodes and voltage measuring electrodes.

At this time, as described above, each electrode is placed 2 times on the wafer mounting table.
In the case of a divided structure, one semiconductor chip can be divided into two parts.
Contact with the seed electrode is rather rare (only when located across the border of the picture electrode), and semiconductor chips in most areas on the semiconductor wafer are in direct contact with only one of the electrodes. become. In this way, when the semiconductor chip directly contacts only one of the electrodes, the other electrode and the semiconductor chip are electrically connected along the back surface of the semiconductor wafer.

Here, the conductive portion on the back surface of the semiconductor wafer naturally has electrical resistance, and this electrical resistance increases as the distance required for conduction becomes longer. Furthermore, when the wafer mounting table is simply divided into two and provided with two types of electrodes as described above, each semiconductor chip on the semiconductor wafer is connected to the other electrode through the back surface of the semiconductor wafer rather than the other electrode that does not come into direct contact with the other semiconductor chip. The length of the conductive part led to each chip is
It is very long in most areas of the semiconductor wafer. Therefore, an increase in electrical resistance due to the length of the conductive portion often causes errors in the measurement results.

On the other hand, by forming two types of electrodes by subdividing the wafer mounting table, it is possible to form a groove bottom so that each chip of the semiconductor wafer always comes into contact with two types of fMh. First patent application: 1986-92828
In this case, the cost of the mounting table becomes relatively high, and depending on the semiconductor chip and the content of the test, there are many devices that can perform accurate tests without reducing the electrical resistance very much.

Therefore, an object of the present invention is to improve the reliability of measurement results by reducing the length required for electrical conduction between the chip supported on the mounting table and the electrodes that do not come into direct contact with the chip. The object of the present invention is to provide a measuring device that can be improved.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a mounting surface on which a semiconductor chip to be measured is mounted.
In an apparatus comprising a voltage applying electrode for applying a voltage to the semiconductor chip, and a voltage measuring electrode for measuring characteristics of the chip, the voltage applying electrode and the voltage measuring electrode 1 have a pole and a 2N (N is an integer of 2 or more) is formed on a plane divided into planes, and these electrodes are formed alternately on each of the N planes on the above-mentioned placement plane.

(Function) In the present invention, the voltage application electrode and the voltage measurement 7 have poles, and the wafer mounting table surface is 2N (N is an integer of 2 or more), that is, 4,
6.8. The electrodes are formed on a plane divided into two planes, and each of these electrodes has N planes alternately on the above-mentioned mounting plane. Therefore, compared to the conventional two-division method, the area of each electrode surface is smaller, and two different types of electrodes are always present on both sides of one electrode. When a semiconductor chip on a semiconductor wafer comes into direct contact with one 71i ti,
The other electrode of the set of electrodes required for 1 illumination of the chip is one of the electrodes on both sides of the one electrode, which has a short straight line distance to the position of the chip. 'FMh.

However, with the conventional two-part type wafer mounting table, when a semiconductor chip directly contacts one electrode, the Ii! of that chip! A set of electrodes used at -1 constant is
Since this was determined regardless of the position of the semiconductor chip, the length required for conduction to trace the back surface of the semiconductor wafer and reach other electrodes may be extremely long depending on the formation position of the semiconductor chip, resulting in poor measurement accuracy. It had gotten significantly worse.

In the case of the present invention, the area of one electrode surface becomes smaller in inverse proportion to the number of divisions, and moreover, the area of one electrode surface becomes smaller in inverse proportion to the number of divisions. Since the electrodes are used as a set of electrodes, the conductive length that traces the backside of the semiconductor wafer to reach the electrode part can be made shorter than in the conventional two-part method, which reduces the electrical resistance. It can be held down to improve measurement accuracy.

(Example) Hereinafter, an example of the measuring device of the present invention will be specifically described with reference to the drawings.

In the wafer mounting table, a voltage applying electrode 2 and an applied voltage measuring electrode 3 made of, for example, gold are formed on the surface of a mounting table main body 1 having a disk shape. The mounting table main body 1 has an outer diameter of 135 mm and a thickness of 20 mm to correspond to, for example, measuring a 5-inch semiconductor wafer. Further, as the material of the mounting table main body 1, a material with high insulation resistance is preferable, and steatite porcelain is a ceramic type material.

Titanium oxide porcelain, magnesium titanate porcelain, alumina ceramics, etc. can be used, and as the glass type, lead glass, borosilicate glass, quartz glass, etc. can be used, or Micalex type can be used. These have a volume resistivity of 1013 Ωcm under the temperature condition of 25°C.
The surface resistivity is 1010Ω or more. In this embodiment, ceramic-based alumina ceramics having a glossy volume resistivity of 10+4 Ω is used.

Further, a plurality of vacuum grooves 1a are formed concentrically on the surface of the mounting table main body 1, and the vacuum grooves 1a
A semiconductor wafer placed on the mounting table main body 1 can be vacuum-suctioned via the mounting table main body 1.

The voltage applying electrode 2 and the voltage measuring electrode 3 are formed on each surface of the mounting table main body 1 divided into four at an angle of 90 degrees, and these electrodes are formed on the surface of the mounting table main body 1. The structure is such that two surfaces are formed alternately on each side. These electrodes 2 and 3 are formed by, for example, gold plating or gold metallization on the surface of the mounting table main body 1, and between each of the electrodes 2 and 3 is a masking portion 4 having a predetermined width of, for example, 1 n+n+ to 2 times. This creates isolation between the two. Although the central part of the mounting table main body 1 may be divided into four parts, in the case of this embodiment, the opposing voltage measuring electrodes 3 are connected at the central part. Moreover, the voltage application electrodes 2, 2 are
Application electrode connection terminals 2a, 2a formed with gold plating or the like in the same way as the electrodes 2 are formed on opposing peripheral edges of the mounting table main body 1.
(Only one side is shown in Figure 1), and similarly,
The voltage measurement electrodes 3, 3 are also provided with measurement electrode connection terminals 3a, 3a formed on opposing peripheral edges of the mounting table main body 1. And these connection terminals 2a, 2a, 3a.

A cable 7 is connected to 3a and connected to a tester (not shown).

The wafer mounting table at the bottom of the groove is used as a chuck top of a probe device for testing the electrical characteristics of semiconductor wafers. Then, it is used for testing and measuring semiconductor chips, such as power transistors, which are formed on a semiconductor wafer and have electrodes on the back surface.

Next, the effect will be explained.

First, a semiconductor wafer is placed on the mounting table main body 1, and the semiconductor wafer is vacuum-adsorbed onto the mounting table main body 1 via the vacuum groove 1a. Next, a predetermined -u pressure is applied from the voltage applying electrode 2 to the connector electrode on the back surface of the semiconductor wafer, and the applied voltage is measured by the voltage measuring electrode 3.

On the other hand, probe needles of a probe device are brought into contact with the electrodes of each semiconductor chip formed on the front surface side of the semiconductor wafer, such as emitter electrodes and base electrodes, and the electrical characteristics of each chip on this semiconductor wafer are inspected. I will do it.

Here, when using this kind of Kelvin specification wafer mounting table, ■ electrical measurement using a relatively large current of 2OA to 5OA (power transistor, MOS power FE
(for T, etc.) or ■1600V to 200
Two types of electrical measurements can be made using relatively high voltages of 0V. In this embodiment, these two types of tests, one for large current and one for high voltage, can be carried out appropriately.

Here, to explain the function of the voltage applying electrode 2 and the voltage measuring electrode 3 formed on the mounting table main body 1, the back surface of each chip of the semiconductor wafer supported on the mounting table main body 1 is It comes into direct contact with either the voltage applying electrode 2 or the voltage measuring electrode 3. Conductivity between the electrode and the chip on the side where the back surface of the chip does not come into direct contact is achieved by tracing the back surface of the semiconductor wafer. Particularly in the case of a test performed using a large current, the longer the length required for conduction to trace the back surface of the semiconductor wafer, the greater the electrical resistance, which has a large effect on measurement accuracy.

In this embodiment, first, since the number of divisions is greater than the conventional two-division method, the area of one electrode surface is small, and therefore the length from an arbitrary point on one electrode surface to a different electrode surface is small. Becomes shorter. Moreover, of the other two different types of electrodes adjacent to one electrode, the one with the shorter straight distance between the chips is used as a set of electrodes, compared to the conventional two-part method. Therefore, there is room to select different types of electrodes with the shortest distance.

In this way, in the case of this embodiment, compared to the conventional two-part Kelvin chuck, the length of the conductive part that traces the back surface of the semiconductor wafer can be shortened, so the loss due to electrical resistance can be reduced. As a result, measurement accuracy can be improved. This effect is particularly effective when testing using a large current.

Next, the effect when this chuck top is used for high voltage testing will be explained.

In such a high voltage use test, the voltage applying electrode 2 or voltage 1111 + constant electrode 3 on the chuck top,
The problem is the voltage resistance between it and the ground (stage base). When the chuck top of this example was measured alone in an environment of a temperature of 25° C. and a humidity of 40%, the following data were obtained.

・DC test...DC4500V.

Leak current 0.5 mmA, OK for - minutes ・AC test...AC2200V Leak bulb 0.5 mL LIA, OK for - minutes Like this,
The reason why the withstand voltage data of the chuck top of this example is superior to that of the conventional one described later is that the mounting table main body 1 on which the voltage applying electrode 2 and the voltage measuring electrode 3 are formed
This is because alumina ceramics having a high resistance of 1014 Ωcm is used as the base material, and the thickness of the mounting table main body 1 is set to be as thick as 20WIIl.

In the conventional device, the above two types of electrodes insulated by epoxy resin are arranged on an aluminum alloy, and the thickness of the aluminium alloy, which has a relatively low resistance value and serves as the main body of the mounting table, is different from that in this embodiment. It was thinner than the thickness of the stand main body 1. Therefore, the withstand voltage data between the electrode and ground are as follows: - Withstand voltage characteristics: 3000VDC.

1 minute (single unit not including cable) - Insulation properties are 1 x 109Ω (500VDC), and the device of this example has better withstand voltage characteristics between electrodes and ground, and is therefore superior in that it can reduce leakage current during testing. ing.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention.

In the above embodiment, the case where the electrode is formed in four divisions, which is the minimum division mode of the present invention, has been described, but the present invention is not limited to this.
The surface is divided into two, and a voltage applying electrode 2. If the voltage measurement electrodes 3 are formed in equal numbers and alternately,
The same effect as the above embodiment can be achieved, and the more the number of divisions is increased, the shorter the length required for conduction to trace the back surface of the semiconductor wafer. Resistance loss can be reduced, thereby contributing to improved measurement accuracy. In addition, as for the cable pull-out of the voltage applying electrode and the voltage measuring electrode formed on the mounting table main body 1, as shown in FIG. The structure shown in FIGS. 2(A) and 2(B) may also be used. This is to draw out the cable from the side of the mounting table main body 1, and for this purpose, the voltage application electrode 2. For voltage measurement? A plurality of through poles 5 are formed from the surface of the Ti pole 3 through the mounting table main body 1 and electrically connected to the back side, and a cable is drawn out from the terminal 6 that is electrically connected to the through hole 5 on the back side of the mounting table main body 1 (■ It should be noted that a structure having one through hole 5 is preferable because the conductive length from the electrode surface to the cable can be shortened and the resistance can be reduced accordingly.

Next, a heating section and a cooling section, 1
Refer to Figure 3 for a modification of the present invention in which one part is integrated.
4 (1, I will explain.

On the back side of the wafer mounting table main body 1, there is a seat plate 1 capable of forming a hollow part between the wafer mounting table main body 1 and the wafer mounting table main body 1.
0 is fixed for example. Between this wafer mounting table main body 1 and the seat plate 10, a cold water jacket] 2, which is an example of a cooling section, is tightly supported on the back side of the wafer mounting table main body 1. There is. This cold water jacket 12 has a built-in cold water pipe 12a for one summer, and by passing cold water through this cold water pipe 12a, heat exchange with the above-mentioned sea urchin \\ loading 1i'' table main body 1 is carried out, and the wafer mounting table is cooled. Furthermore, this cold water jacket 1
A heating section, for example, a tape-shaped heater 16 formed on the shield plate 14 is arranged below the shield plate 2 .

By incorporating a cooling section or a heating section into the mounting table main body, the mounting table main body can be set to various temperatures by passing cold water through the cold water jacket 12 or by energizing the tape-shaped heater 16, as shown in section L. can do. Therefore, by placing a semiconductor wafer on such a wafer stand, it is possible to test the electrical characteristics at high or low temperatures, and at various temperatures depending on the actual usage environment of the semiconductor chip. It becomes possible to inspect the electrical characteristics of

In addition, as described above, only one of the ring part and the heating part may be built into the wafer mounting table as necessary, or the cooling part and the heating part may be constructed as shown in 1.17 above. The present invention is not limited to this structure, and various configurations capable of cooling or heating the wafer mounting table can be adopted.

[Effects of the Invention] As described above, according to the present invention, by reducing the variation in the electrical resistance at 411+ time, which differs depending on the formation position of the semiconductor chip on the semiconductor wafer, measurement accuracy can be improved compared to the conventional method. Comparative clothing f+IT that can be improved
It is possible to provide an i measurement device.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing an example of a wafer mounting table to which the present invention is applied, and Fig. 2 (A) and (B) respectively show a modification of the present invention in which cable extraction is realized by a through hole. The schematic perspective view, cross-sectional view, and FIG. 3 of the IFE shown in FIG.
FIG. 2 is a cross-sectional view of a wafer mounting table with a built-in cooling section. 1... Mounting table main body, 2... Voltage application electrode, 2a... Application electrode connection terminal, 3... Voltage allllll definition 3a...
・Measuring electrode connection terminal, 4...Masking part, 5...Through hole, 6...Terminal, 7...Cable, 12
...cold water jacket, 16...tape heater. Agent Patent attorney Inoue - (1 other person) Figures (A) (B) Figures

Claims (1)

[Claims] (1) An apparatus comprising, on a mounting surface on which a semiconductor chip to be measured is mounted, a voltage application electrode for applying a voltage to the semiconductor chip and a voltage measurement electrode for measuring the characteristics of the chip, Place the voltage applying electrode and voltage measuring electrode on the above mounting surface.
A measuring device formed on a surface divided into N (N is an integer of 2 or more), and configured such that these electrodes are alternately formed on each of the N surfaces on the above-mentioned mounting surface. .