JP2007123430A - Semiconductor wafer and semiconductor inspecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor wafer and a semiconductor inspecting method for realizing Kelvin connection to the rear surface of wafer with a simplified structure without complication of an inspection apparatus for the inspection of electrical characteristics of a chip formed on a semiconductor wafer. <P>SOLUTION: A rear surface potential measuring electrode 5 to be connected electrically to the rear surface of wafer for measurement of potential at the rear surface is provided on the front surface of a semiconductor wafer 2, and this rear surface potential measuring electrode 5 and the rear surface are electrically connected through the semiconductor wafer 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to inspection of electrical characteristics of chips formed on a semiconductor wafer, and in particular, the surface electrode and wafer appearing at this time by passing an inspection current between the surface electrode of the chip or the like formed on the semiconductor wafer and the back surface of the wafer. The present invention relates to an inspection of electrical characteristics for measuring a voltage between back surfaces.

  In the manufacturing process of a semiconductor device, a semiconductor chip formed on a semiconductor wafer is inspected to find a defective chip, and the defective chip is not subjected to a subsequent assembly process, thereby improving manufacturing efficiency. . Such inspection includes inspection of electrical characteristics of each semiconductor chip. In the inspection of electrical characteristics, an inspection current is passed between the front surface electrode of the semiconductor chip and the back surface of the wafer, and the surface that appears at this time. The voltage between the electrode and the back surface of the wafer is also measured (the voltage measured in this way is referred to as “measured voltage” in the following description of the present specification). As such a voltage to be measured, for example, in a semiconductor wafer in which a gate and a source of a field effect transistor are formed on the surface and a drain corresponding to the other surface is formed, a gate electrode and a wafer formed on the wafer surface The forward voltage (ON resistance) between the back surface is measured.

  FIG. 1A is an explanatory diagram of a conventional semiconductor inspection method for measuring the measured voltage. As shown in FIG. 1A, a semiconductor inspection apparatus 1 includes a wafer chuck (sample stage) 10 that holds a wafer 2 and pads (electrodes) provided on a chip (not shown) formed on the wafer 2. ) A probe card 30 provided with probes (needles) 31f and 31s for making a voltage measurement by applying an inspection current to the pad 3 in contact with 3 and a voltage at the time when an inspection current is supplied from the pad 3 of the chip to the back surface. And a tester circuit 40 for measuring. As the semiconductor inspection apparatus 1, a probe head type that does not include the probe card 30 is also used.

The probes 31f and 31s provided on the probe card 30 are separately provided for the force probe 31f and the sense probe 31s so that the voltage drop caused by the contact resistance between the probe and the pad does not affect the measurement voltage. Kelvin connection is employed as disclosed in Patent Document 1 below.
The tester circuit 40 causes an inspection current to flow from the pad 3 to the back surface of the wafer 2 via the force probe 31f by the power source 42, and senses a voltage generated between the pad 3 and the back surface of the wafer 2 at that time. By measuring with the voltmeter 41 through the probe 31s, the measured voltage appearing between the front surface electrode and the back surface electrode of the semiconductor chip is obtained.
The voltmeter 41 in the tester 40 is connected in series with a high impedance internal resistance Ri in order to prevent a voltage drop due to the resistance value of the voltmeter itself, and the inspection current hardly passes through the voltmeter 41. Therefore, it is possible to obtain a measurement value without being affected by the contact resistance between the sensing probe 31s and the pad 3.

FIG. 1B is an equivalent circuit diagram of an inspection circuit by the semiconductor inspection apparatus 1 of FIG. In FIG. 1B, R1f represents the contact resistance between the force probe 31f and the pad 3, R1s represents the contact resistance between the sense probe 31s and the pad 3, and R2 represents the back surface of the wafer 2. Side contact resistance.
As can be seen from FIG. 1B, in the configuration of the conventional semiconductor inspection apparatus 1, the series circuit connecting the voltmeter 41, the pad 3 and the wafer 2 has a contact resistance on the back side of the wafer 2 through which an inspection current flows. R2 is included. For this reason, there is a problem that the measurement accuracy is deteriorated because the voltage drop caused by the contact resistance R2 is included in the measurement result.

  In order to solve this problem, in the semiconductor inspection apparatus disclosed in Patent Document 2 below, a plurality of through holes are provided in a wafer stage for holding a wafer, contact pins are arranged in each of the holes, and the pins are pressed by pressing from the back side. The tip is slightly protruded from the surface of the stage and is in contact with the back surface of the wafer. On the other hand, a force contact piece and a sense contact piece for pushing up the contact pin are provided on the back side of the stage, and these contact pieces move directly under the chip to be inspected to press the contact pin separately to force contact. Kelvin connection is realized also on the back surface of the wafer by separately bringing the pins in contact with the pins and the pins in contact with the sensing contact pieces into contact with the back surface of the wafer.

JP-A-11-64385 JP 2004-311799 A Japanese Patent Laid-Open No. 2003-322395

  However, in the configuration of Patent Document 2, it is desired that at least one force pin and a sense pin abut on the back surface of each chip disposed on the wafer. Therefore, a large number of contact pins are arranged at a fine pitch. When pressed from the back side, it is necessary to arrange it so as not to fall out from the back side while protruding to the stage surface. In addition, it is necessary to incorporate a drive mechanism in the stage that moves the contact piece that pushes up the contact pin to directly below each chip. For this reason, the configuration of Patent Document 2 has a problem that the stage mechanism becomes very complicated.

  In view of the above problems, the present invention provides a semiconductor wafer capable of realizing Kelvin connection to the back surface of the wafer with a simple configuration without complicating the inspection apparatus in the inspection of the electrical characteristics of the chip formed on the semiconductor wafer. It is another object of the present invention to provide a semiconductor inspection method.

In order to achieve the above object, in the present invention, a back surface potential measurement electrode is provided on the surface of a semiconductor wafer and is electrically connected to the back surface of the wafer and used for potential measurement of the back surface. The back surface potential measurement electrode and the back surface are conducted through the semiconductor wafer.
When inspecting the electrical characteristics of the chip formed on the surface of the semiconductor wafer, the first force terminal is brought into contact with the measurement site on the chip and the second force terminal is brought into contact with the back surface of the semiconductor wafer. On the other hand, a first sense terminal is brought into contact with the measurement site, and a second sense terminal is brought into contact with the back surface potential measurement electrode. In this way, the force terminal and the sense terminal are brought into contact with the measurement site, the back surface, and the back surface potential measurement electrode, whereby the force terminal and the sense terminal are Kelvin connected to the measurement site and the back surface.

The back surface potential measurement electrode may be provided so that the back surface potential measurement electrode itself penetrates the semiconductor wafer and reaches the back surface thereof.
Furthermore, the back surface potential measurement electrode may be formed in a chip region formed on the surface of the semiconductor wafer, may be formed outside the chip region, or may be formed in a street region between a plurality of chip regions. .

  According to the present invention, a semiconductor wafer and a semiconductor inspection method that realize Kelvin connection to the back surface of the wafer with a simple configuration are realized. This makes it possible to improve the accuracy of the inspection of the electrical characteristics of the chip with an inexpensive configuration.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 2 is a view showing a state of inspection of electrical characteristics of the semiconductor wafer according to the embodiment of the present invention. As shown in FIG. 2, the semiconductor inspection apparatus 1 is provided with an XY movable table 20 and a wafer chuck (sample stage) 10 such as a vacuum chuck that is provided on the table 20 and holds the semiconductor wafer 2.
Above the chuck 10, probes 31f and 31s for contacting the pad 3 on the chip 4 formed on the surface of the wafer 2 held on the chuck 10 and electrically connecting the pad 3 to the tester circuit 40 are provided. A provided probe card 30 is provided. The semiconductor inspection apparatus 1 may be a probe head type that does not include the probe card 30.

The probe 31 f provided on the probe card 30 is for a force for applying a voltage to the pad 3 that is electrically connected to the power source 42 in the tester circuit 40 in order to flow an inspection current from the pad 3 to the back surface of the wafer 2. The probe 31 s is a first sense that connects the pad 3 to one terminal of a voltmeter 41 in order to measure a voltage between the pad 3 and the back surface of the wafer 2 (the voltage to be measured with respect to the chip 4). Probe. A high impedance internal resistance Ri is connected in series to the voltmeter 41 in the tester circuit 40, and the semiconductor inspection apparatus 1 provides Kelvin between the force probe 31 f and the first sense probe 31 s and the pad 3. Connecting.
Here, the force probe 31f provided in the probe card 30 constitutes a first force terminal according to the claims of the present application, and the first sense probe 31s provided in the probe card 30 is claimed in the present application. The first sense terminal according to the range is formed.

  On the other hand, the front surface of the wafer chuck 10 is in contact with the back surface of the wafer 2 and the back surface of the wafer 2 is connected to the power source 42 of the tester circuit 40 to form a force terminal. The front surface of the wafer chuck 10 applies an inspection current between the pad 3 and the back surface of the wafer 2 by applying a voltage between the pad 3 and the back surface of the wafer 2 together with the force probe 31f. Therefore, the surface of the wafer chuck 10 forms a second force terminal according to the claims of the present application.

  Furthermore, a back surface potential measuring electrode 5 electrically connected to the back surface of the wafer 2 is provided on the front surface of the wafer 2. The back surface potential measurement electrode 5 will be described in detail below. On the other hand, the probe card 30 is provided with a second sense probe 32 s that contacts the back surface potential measurement electrode 5. The second sense probe 32 s is connected to the other terminal of the voltmeter 41 in the tester circuit 40. The pad 3 is electrically connected to one terminal of the voltmeter 41 by the first sensing probe 31s, and the back surface of the wafer 2 is electrically connected to the other terminal of the voltmeter 41 by the second sensing probe 32s. Thus, the potential difference between the pad 3 and the back surface of the wafer 2 is measured. Here, the second sense probe 32s forms a second sense terminal according to the claims of the present application.

FIG. 3A is a view for explaining the basic principle of the semiconductor inspection method according to the embodiment of the present invention. The back surface potential measuring electrode 5 is electrically connected to the back surface of the wafer 2 by the connecting portion 51 penetrating the semiconductor wafer 2 and has the same potential as the back surface of the wafer 2. Such a connection part 51 may be formed by doping a corresponding part of the wafer 2 with a donor or an acceptor to increase the conductivity of this part, or by burying a good conductor after the wafer 2 is drilled. Also good.
On the other hand, most of the inspection current If flowing into the pad 3 from the force probe 31 f is collected on the surface of the wafer chuck 10 and returned to the power source 42. Accordingly, since the inspection current If does not flow into the second sensing probe 32s, the Kelvin connection by the force electrode 11f and the sensing electrode 11s is also realized on the back surface of the wafer 2.

FIG. 3B is an equivalent circuit diagram of FIG. As understood from comparison with the conventional equivalent circuit diagram shown in FIG. 1B, by realizing the Kelvin connection to the front surface of the wafer chuck 10 and the back surface of the wafer 2 by the second sensing probe 32s, A force circuit Cf that allows current to flow from the pad 3 to the back surface of the wafer 2 by the power source 42 is separated from a sense circuit Cs that measures a voltage between the pad 3 and the back surface of the wafer 2 by the voltmeter 41. Here, the resistor R2 shown in FIG. 3 is a contact resistance between the back surface of the wafer 2 and the surface of the wafer chuck 10, and the resistor R2s is a contact resistance between the second sensing probe 32s and the back surface of the wafer 2.
For this reason, the superposition of the voltage drop caused by the contact resistance R2 on the back surface of the wafer described above with reference to the equivalent circuit shown in FIG. 1B is prevented from being superimposed on the measurement voltage, and the measurement accuracy is improved. It becomes possible to do.

As shown in FIG. 3A, the inner wall of the intermediate portion where the potential of the back surface potential measuring electrode 5 reaches the back surface of the through hole penetrating from the front surface of the semiconductor wafer 2 to the back surface. In order to prevent the potential from being influenced by the potential of the back surface potential measuring electrode 5 and the surface of the semiconductor wafer 2, or between the back surface potential measuring electrode 5 and the connection portion 51 and the inner wall in the middle of the through hole. An insulating means 52 such as an insulating film may be provided.
When the back surface potential measuring electrode 5 is provided far from the pad 3, the voltage drop between the back surface portion of the wafer 2 through which the back surface potential measuring electrode 5 is conducted and the pad 3 becomes the measured value. The back surface of the wafer 2 is a low-resistance semiconductor, and the inspection current If is collected on the surface of the wafer chuck 10 so that the back surface potential measuring electrode 5 is conductive. Since almost no current flows between the back surface portion and the pad 3, the influence is slight and does not cause a problem.
Further, in FIG. 3A, the back surface potential measuring electrode 5 is electrically connected to the back surface of the wafer 2 by the connecting portion 51 penetrating the semiconductor wafer 2, but the back surface potential measuring electrode 5 itself is connected to the semiconductor. You may provide so that the wafer 2 may be penetrated and it may reach the back surface.

4A and 4B are diagrams showing various arrangement examples of the back surface potential measuring electrode 5. FIG. In the example shown in FIG. 4A, the back surface potential measuring electrode 5 is formed in each chip region for each chip 4 formed on the surface of the semiconductor wafer 2.
In the example shown in FIG. 4B, a back surface potential measuring electrode 5 is formed outside each chip region for each chip 4 formed on the surface of the semiconductor wafer 2. At this time, the back surface potential measuring electrode 5 may be provided in a street region between the chip regions 4.

As shown in FIG. 4A and FIG. 4B, by providing the back surface potential measuring electrode 5 in and near the chip area for each chip 4, the chip 4 to be inspected is provided. It is possible to measure the near back surface potential, and more accurate measurement is possible.
Note that the back surface potential measuring electrode 5 may be provided on only one of the plurality of chips. Further, the back surface potential measuring electrode 5 provided in the street region between the chips may be shared by two chips sandwiching the street.

  INDUSTRIAL APPLICABILITY The present invention can be used for inspection of electrical characteristics of chips formed on a semiconductor wafer, and particularly appears when an inspection current is passed between a surface electrode such as a chip formed on a semiconductor wafer and the back surface of the wafer. It can be used for inspection of electrical characteristics for measuring a voltage between a surface electrode such as a chip and the back surface of the wafer.

(A) is explanatory drawing of the conventional semiconductor test | inspection method which measures the voltage which flows an inspection electric current between surface electrodes, such as a chip | tip formed in the semiconductor wafer, and a wafer back surface, and (B). It is the equivalent circuit schematic of the test | inspection circuit by the semiconductor test | inspection apparatus shown to (A). It is a figure which shows the mode of the test | inspection of the electrical property of the semiconductor wafer which concerns on the Example of this invention. (A) is a figure explaining the basic principle of the semiconductor inspection method based on the Example of this invention, (B) is an equivalent circuit schematic of (A). It is a figure which shows the example of arrangement | positioning of the electrode for back surface potential measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor inspection apparatus 2 Wafer 4 Chip 5 Back surface potential measurement electrode 10 Wafer chuck 20 Stage 30 Probe card 31f Force probe 31s, 32s Sense probe 40 Tester circuit

Claims (6)

A semiconductor wafer having a semiconductor circuit formed on a surface thereof;
A back surface potential measuring electrode that is electrically connected to the back surface and used for back surface potential measurement is provided on the surface,
A semiconductor wafer, wherein the back surface potential measuring electrode and the back surface are conducted through the semiconductor wafer.   The semiconductor wafer according to claim 2, wherein the back surface potential measurement electrode penetrates the semiconductor wafer and reaches the back surface thereof.   The semiconductor wafer according to claim 1, wherein the back surface potential measurement electrode is formed in a chip region formed on a surface of the semiconductor wafer.   The semiconductor wafer according to claim 1, wherein the back surface potential measuring electrode is formed outside a chip region formed on a surface of the semiconductor wafer.   The semiconductor wafer according to claim 4, wherein the back surface potential measuring electrode is formed in a street region between a plurality of chip regions formed on the surface of the semiconductor wafer. In a semiconductor inspection method for inspecting electrical characteristics of chips formed on the surface of a semiconductor wafer,
The first force terminal is brought into contact with the measurement site on the chip, and the second force terminal is brought into contact with the back surface of the semiconductor wafer,
Bringing the first sense terminal into contact with the measurement site;
A back surface potential measuring electrode electrically connected to the back surface of the wafer provided on the front surface of the semiconductor wafer, the back surface potential measuring electrode and the back surface of the semiconductor wafer penetrating the semiconductor wafer. The second sense terminal is brought into contact with the conductive back surface potential measurement electrode,
A semiconductor inspection method, wherein the force terminal and the sense terminal are Kelvin connected to the measurement site and the back surface.

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