JP2000068343A - Method and equipment for judging conductivity type of semiconductor material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to judge the conductivity type with stability by applying a voltage between the semiconductor material to be measured and a metal probe electrode through an electrostatic coupling electrode, and judging the conductivity type of the semiconductor material to be measured by inspecting the rectification characteristic at the contact. SOLUTION: An electrostatic coupling electrode 3 is fabricated in form of a flat plate and is so installed as to be electrostatic coupled with the semiconductor material 1 to be measured while being connected to a rectangular wave generator 4. On the other hand, a metal probe electrode 2 is fabricated in form of a needle and is so installed as to be Schottky bonded with the semiconductor material 1 to be measured. The rectification characteristic in the metal probe electrode 2 is judged by a judging means 5 constituted of an amplifier 6, a (positive) peak value detection circuit 7, a (negative) peak value detection circuit 8, a differential amplifier 9, and a conductivity type detector 10. As a result, ohmic bonding between electrodes which has been used in the conventional method for judging the rectification characteristic is eliminated and therefore a stable and reliable bonding can be secured and stable judgement is possible. Moreover, an easy method for judgement can be established.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for determining the P-type and N-type conductivity types of semiconductor materials such as silicon wafers and silicon single crystal bars.

[0002]

2. Description of the Related Art Semiconductor materials such as silicon wafers and silicon single crystal rods include P-type and N-type as is well known. The P-type and N-type discrimination methods include a thermoelectromotive force discrimination method, a photoelectromotive force discrimination method, a Hall effect discrimination method, a rectification discrimination method, and the like.
There are various methods.

The rectification determination method is a conduction determination method using a Schottky junction between a metal and a semiconductor. It is known that when a metal and a semiconductor are brought into contact, rectification characteristics are exhibited. Here, the work function of metal is φm, and the work function of semiconductor is φs
When a metal and an n-type semiconductor satisfy φm> φs, and when a metal and a p-type semiconductor satisfy φm <φs, a rectifying effect occurs. A junction in which this rectifying effect occurs is called a Schottky junction. When the relationship between the work functions of the metal and the semiconductor is reversed, that is, when an ohmic junction is formed, no rectification characteristics are generated.

In the conductivity type discriminating method utilizing the Schottky junction (effect), as shown in FIG.
B is brought into contact with the surface of the semiconductor material C to be measured. One of the electrodes A is a metal probe so as to obtain rectification characteristics, and the other electrode B is a metal plate having no rectification characteristics. A voltage is applied between A and B from an AC power supply through a transformer D, and the rectification direction at that time is determined by a zero detector E, so that the semiconductor material C to be measured is P-type or N-type. Is determined. In this case, stainless steel is used for the electrode A so that rectification characteristics easily occur,
Osmium or the like is used for the electrode B.

[0005]

SUMMARY OF THE INVENTION The rectification determination method includes:
The point for obtaining good performance is to prevent the rectification characteristic from occurring at the contact point of the electrode A and the rectification characteristic at the contact point of the electrode B.
In many cases, it is difficult to make an ohmic junction. As an example, a thin but highly insulating oxide film may be present on the surface of the semiconductor material C. In order to obtain a good ohmic junction, it is necessary to break through this oxide film and bring the electrode B into contact with the semiconductor material C to be measured. The semiconductor material C on which a diffusion layer or an epi (epitaxial) layer is formed is difficult to be damaged and damaged. However, if good ohmic contact cannot be obtained, it is difficult to stably determine the conductivity type of the semiconductor material C. Therefore, there is a need for an improved method of contacting the electrode B with the semiconductor material C to be measured.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is a method of determining the conductivity type of a semiconductor material which does not require ohmic contact between a semiconductor material to be measured and a metal plate. Is to provide.

According to a first aspect of the present invention, there is provided a method for determining the conductivity type of a semiconductor material, comprising: a metal probe electrode in contact with a semiconductor material to be measured; A voltage is applied between the capacitance-coupled electrode 3 and the rectification characteristic at the contact portion between the semiconductor material 1 for measurement and the metal probe electrode 2 to check the conductivity type of the semiconductor material 1 for measurement. It is characterized in that it is determined.

According to a second aspect of the present invention, there is provided an apparatus for determining the conductivity type of a semiconductor material, comprising: a needle-shaped metal probe electrode which is in point contact with the semiconductor material to be measured;
And a voltage generator 4 for generating a voltage for applying a voltage between the electrodes 2 and 3
And a determination means 5 for determining the conductivity type of the semiconductor material 1 to be measured by examining rectification characteristics at a contact portion between the semiconductor material 1 to be measured and the metal probe electrode 2.

According to a third aspect of the present invention, there is provided an apparatus for determining the conductivity type of a semiconductor material, wherein the determining means 5 includes a metal probe electrode
, An amplifier 6 for amplifying the voltage detected by the above, a + peak value detection circuit 7 for holding a positive peak voltage of the amplified voltage, and a-peak value detection for holding a negative peak voltage of the amplified voltage. It comprises a circuit 8, a deviation amplifier 9 for amplifying the deviation between the two detection circuits 7, 8, and a polarity display 10 for displaying the polarity of the voltage output from the deviation amplifier 9.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the conductivity type discriminating method of the present invention will be described. In this conductivity type discriminating method, as shown in an equivalent circuit shown in FIG. 2, a flat capacitive coupling electrode 3 is provided on a semiconductor material 1 to be measured so as to be capacitively coupled to the semiconductor material 1. A metal probe electrode 2 is provided so as to generate a Schottky effect between the semiconductor material 1 and a voltage is applied between the electrodes 2 and 3. At this time, different rectifying effects occur between the semiconductor material 1 for measurement and the metal probe electrode 2 in FIG. 2 according to the conductivity type of the semiconductor material 1. This difference in the rectification effect can be identified by measuring the voltage value appearing across the resistor 11. For example, when a rectangular wave voltage shown in FIG. 3A is applied between the electrodes 2 and 3, when the semiconductor material 1 to be measured is a P-type, the rectification direction and the current direction match when the voltage rises. When the voltage falls, the rectification direction and the current direction do not coincide with each other, so that the voltage pattern shown in FIG. 3B is generated, and when the voltage is N-type, the voltage pattern shown in FIG. 3C is generated.

The waveform pattern of the voltage applied in the present invention is not limited to a rectangular wave as shown in FIG. 3A, and a voltage of a desired pattern can be applied as needed.
When it is desired to increase the capacitance, a dielectric can be arranged between the capacitance coupling electrode 3 and the semiconductor material 1 to be measured.

FIG. 1 shows an embodiment of the conductivity type discriminating apparatus of the present invention. The capacitance coupling electrode 3 shown in FIG. 1 is formed in a plate shape and provided so as to be capable of capacitive coupling with the semiconductor material 1 to be measured. The metal probe electrode 2 is formed in a needle shape and used for measurement. The semiconductor material 1 is provided so as to be capable of Schottky bonding. The capacitive coupling electrode 3 is connected to a rectangular wave oscillator (voltage generator) 4 for generating a rectangular wave voltage shown in FIG. 3A, for example, and applies a rectangular wave voltage to the semiconductor material 1 to be measured. You can do it. On the other hand, the metal probe electrode 2 is connected to an amplifier 6 and further connected to a + peak value detection circuit 7 and a −peak value detection circuit 8 which are connected in parallel.
Is connected to a conductivity type detector 10 via a deviation amplifier 9. The amplifier 6 amplifies the voltage detected by the metal probe electrode 2. The + peak value detector 7 and the -peak value detector 8 generate a + (plus) peak voltage value from the input voltage. This is a circuit capable of holding a peak voltage value of-(minus). Deviation amplifier (differential amplifier) 9
Is to take the deviation of the outputs of both the + peak value detection circuit 7 and the −peak value detection circuit 8 and output the polarity of the voltage value at the metal probe electrode 2 as a result. The conductivity type detector (polarity display) 10 is for displaying the polarity obtained by the deviation amplifier 9, and is, for example, a zero detector in which the direction of movement of the needle is reversed by the positive or negative of the voltage, or according to the positive or negative. An LED or the like whose lighting color changes is used.

In the embodiment shown in FIG. 1, the rectifying characteristic of the metal probe electrode 2 is determined by an amplifier 6, a + peak value detection circuit 7, a −peak value detection circuit 8, a deviation amplifier 9, and a conductivity type detector 10. However, other circuits can be used for the determination means 5.

[0014]

According to the conductivity type discriminating method and discriminating apparatus of the present invention, the ohmic junction of the electrodes used in the conventional rectification discriminating method becomes unnecessary, the coupling becomes stable and reliable, and stable discrimination is possible. Becomes Further, since the contact with the semiconductor material is made only by the metal probe having a stylus pressure of several grams, it is possible to determine not only the thin silicon wafer but also the semiconductor material on which the diffusion layer and the epi layer are formed.

According to the conductivity type discriminating apparatus of the present invention, the discriminating method can be easily realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of an apparatus for determining the conductivity type of a semiconductor material according to the present invention.

FIG. 2 is a circuit diagram illustrating the principle of the method for determining the conductivity type of a semiconductor material according to the present invention.

FIGS. 3A to 3C are explanatory diagrams showing an example of a P-type and N-type discrimination method according to the conductivity type discrimination method of the present invention.

FIG. 4 is a circuit diagram showing an example of a conventional rectification determination device.

[Explanation of symbols]

 Reference Signs List 1 semiconductor material to be measured 2 metal probe electrode 3 capacitance coupling electrode 4 voltage generator 5 determination means 6 amplifier 7 + peak value detection circuit 8-peak value detection circuit 9 deviation amplifier 10 polarity display

Claims (3)

[Claims] A metal probe electrode (2) in contact with a semiconductor material (1) to be measured and a capacitance coupling electrode (3) capacitively coupled to the semiconductor material (1) to be measured. To determine the conductivity type of the semiconductor material to be measured (1) by examining the rectification characteristics at the contact portion between the semiconductor material to be measured (1) and the metal probe electrode (2). A method for determining the conductivity type of a semiconductor material, characterized in that: 2. A needle-shaped metal probe electrode (2) that is in point contact with a semiconductor material (1) to be measured, and a capacitive coupling that is capacitively coupled to the semiconductor material (1) to be measured. Electrode (3)
A voltage generating means (4) for generating a voltage for applying a voltage between the two electrodes (2, 3); and a rectification characteristic at a contact portion between the semiconductor material to be measured (1) and the metal probe electrode (2). And a determination means (5) for determining the conductivity type of the semiconductor material to be measured (1) by examining the semiconductor material to be measured. 3. An amplifier (6) for amplifying a voltage detected by a metal probe electrode (2), and a + peak value for holding a positive peak voltage of the amplified voltage. A detection circuit (7), a minus peak value detection circuit (8) for holding a peak voltage of a negative value of the amplified voltage, and a deviation amplifier (9) for amplifying a deviation between the two detection circuits (7, 8).
3. The apparatus according to claim 2, further comprising a polarity indicator (10) for displaying the polarity of the voltage output from the deviation amplifier (9).