JP2003329568A - Scanning capacitive microscope and measuring method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning capacitive microscope which can reduce the effect of an interface energy level and a deep energy level on a capacitance measurement and stably estimate the capacitance, and to provide a measuring method using the scanning capacitive microscope. <P>SOLUTION: The scanning capacitive microscope, which measures a capacitance generated by a probe 5 and a semiconductor sample 200, is provided with a light source 9 projecting light, which has a photon energy higher than the band gap energy of a material making up the semiconductor sample 200, onto a contact section of the probe 5 and the semiconductor sample 200, and thereby reducing the effect of the deep energy level of the semiconductor sample 200 and the effect of the interface energy level generated in an interface between the surface of the semiconductor sample 200 and its natural oxide film, or measuring them separately, and enabling the measurement while preventing the contact between the probe 5 and the semiconductor sample 200 from becoming unstable. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning capacitance microscope used for evaluating the impurity concentration and the like in a minute region of a semiconductor device and the like, and a measuring method using this microscope.

[0002]

2. Description of the Related Art A conventional scanning capacitance microscope will be described. FIG. 6 is a configuration diagram showing a conventional scanning capacitance microscope, and FIG. 7 is a partially enlarged view in which a broken line portion u in FIG. 6 is enlarged. 6 and 7, 101 is a probe, 102 is a sample stage, 103 is an AC bias power supply, 104 is a DC bias power supply, 105 is a capacitance sensor,
106 is a lock-in amplifier, 107 is a signal output terminal, 1
08 is a semiconductor sample to be measured.

The operating principle of the scanning capacitance microscope of FIGS. 6 and 7 is as follows. Semiconductor sample to be measured 1
08 is brought into contact with the probe 101, and the DC bias power source 104 and the AC bias power source 103 cause the semiconductor sample 108
An electric field is applied between the probe 101 and the probe 101. This electric field is
The semiconductor sample 1 acts on the MOS structure formed between the probe 101 covered with the conductor or the conductor thin film and the semiconductor sample 108 having the natural oxide film 108A on the surface.
A depletion layer 108B corresponding to the bias potential is generated on the surface of 08.

The thickness of the depletion layer 108B is evaluated by measuring the capacitance between the probe 101 and the sample stage 102. In reality, the capacitance change dC with respect to the potential dV applied to the signal output terminal 107 is calculated by the capacitance sensor 105.
And the lock-in amplifier 106 detect dC / d
The measurement is performed by obtaining the V signal. That is,
When the impurity concentration in the semiconductor sample 108 is high, dC
If the / dV signal becomes small and the impurity concentration is low,
There is a relationship that the dC / dV signal becomes large. Based on this relationship, the impurity concentration is evaluated.

Further, the probe 1 is attached to the surface of the semiconductor sample 108.
01 by two-dimensional scanning, the position information and the dC
The in-plane distribution of the impurity concentration in the semiconductor sample 108 is evaluated by displaying the / dV signal as an image.

[0006]

In the conventional scanning capacitance microscope described above, since the magnitude of the dC / dV signal is simply measured and imaged, it is present at the interface between the semiconductor sample surface and the natural oxide film. It was impossible to avoid the influence of the trapped interface states and the deep trapped charges existing in the semiconductor sample. In particular, when the semiconductor sample is a compound semiconductor, the density of the interface state is inevitably high, and a deep level may be introduced at a high concentration. Therefore, there is a problem that it is difficult to associate the dC / dV signal with the impurity concentration of the semiconductor sample.

Further, the semiconductor sample to be observed has p within the observation plane.
In the case of a semiconductor cross section including an n-junction, a heterojunction, etc., A applied to acquire the dC / dV signal
The shape of the depletion layer in the semiconductor sample is modulated by the C bias voltage. As a result, the deep level charge state in the semiconductor sample changes with a specific time constant. This allows
There is a problem that hysteresis occurs and a ghost occurs in the scanning direction of the probe of the observed image.

In the conventional scanning capacitance microscope,
In a metal-oxide film-semiconductor structure (MOS structure) in which a natural oxide film on the surface of a semiconductor sample is used as an insulating layer, a depletion layer generated in the semiconductor near the oxide film is evaluated. For this reason,
When the natural oxide film is not mechanically or chemically stable, it is difficult to observe. Furthermore, if the natural oxide film is destroyed by the scanning of the probe, an incomplete Schottky junction is formed between the probe and the surface of the semiconductor sample, and stable evaluation is difficult as in the above. There was a problem that became.

As described above, in the conventional scanning capacitance microscope, when the compound semiconductor is evaluated, the influence of the interface level and the deep level is unavoidable, and a stable MOS structure is provided between the probe and the surface of the semiconductor sample. There is a problem that it is not formed and stable evaluation is difficult.

The present invention solves the above-described problems, reduces the influence of interface states and deep levels on capacitance measurement, and enables stable capacitance evaluation, and a scanning capacitance microscope and measurement using this microscope. The purpose is to provide a method.

[0011]

In order to avoid the influence of the interface level and the deep level in the above problem, the invention of claim 1 is a scan for measuring the capacitance formed by a probe and a sample. In a scanning capacitance microscope, the scanning capacitance microscope is characterized in that it has an irradiation means for irradiating the contact portion between the probe and the sample with light having a photon energy equal to or higher than the band gap energy of the material forming the sample. is there.

According to a second aspect of the present invention, in the scanning capacitance microscope according to the first aspect, the structure of the probe for contacting a sample to perform capacitance measurement is covered with a conductor or a conductive film, and The conductor or the conductive film is covered with one or more insulating films.

According to a third aspect of the present invention, in the scanning capacitance microscope according to the second aspect, the probe is contacted with the probe so that the native oxide film on the surface of the sample comes off during the sweeping process of the probe. It is characterized by having an adjusting means for adjusting the needle pressure applied to the needle.

According to a fourth aspect of the present invention, in the scanning capacitance microscope according to the third aspect, when the capacitance of an arbitrary measurement point on the sample is evaluated, at least the probe is placed on the measurement point before the measurement is started. It is characterized in that it has means for measuring the capacity after sweeping once or more.

According to a fifth aspect of the present invention, in the scanning capacitance microscope according to any one of the second to fourth aspects, the atmosphere around the probe and the sample is an inert gas such as nitrogen or argon, or It is characterized by being a reducing gas such as hydrogen or a vacuum.

According to a sixth aspect of the present invention, in the scanning capacitance microscope according to the fifth aspect, the atmosphere around the probe and the sample is an inert gas such as nitrogen or argon, or a reducing gas such as hydrogen. , Or a chamber for maintaining a vacuum, a preliminary chamber for surface treatment of the sample or a chamber for transferring the sample from another device, a connecting means for connecting the respective chambers, and the chamber for the sample. It is characterized in that it has a conveying means capable of conveying without exposing the space to the atmosphere.

According to a seventh aspect of the present invention, in a measuring method using a scanning capacitance microscope for measuring an electrostatic capacity formed by a probe and a sample, the probe is covered with a conductor or a conductive film. Moreover, by using the conductor or the conductive film covered with one or more insulating films, the probe is brought into contact with the sample, and the photon energy higher than the band gap energy of the material forming the sample is applied. The light having the light is applied to the contact portion between the probe and the sample, and applied to the probe to such an extent that the native oxide film on the surface of the sample in contact with the probe is peeled off in the sweeping process of the probe. Scanning characterized in that when the stylus pressure is adjusted and the capacity of an arbitrary measurement point on the sample is evaluated, the probe is swept at least one or more times at the measurement point before the measurement is started and then the capacity is measured. It is a measuring method using a scanning capacitance microscope.

According to the present invention described above, the influence of the deep level in the semiconductor and the influence of the interface state formed at the interface between the semiconductor surface and its natural oxide film are reduced or measured separately, and This enables measurement while avoiding instability of contact between the probe and the sample. These points are as follows.

In the scanning capacitance microscope according to the first aspect, the measurement portion of the sample is irradiated with light having a photon energy higher than the band gap energy of the material forming the sample to generate electron-hole pairs. The capacitance is evaluated in the state where electrons or holes are always trapped in the interface level and the deep level.

Generally, the emission time constant of electrons or holes trapped in the interface level and the deep level is smaller than that of a shallow donor or acceptor formed by an n-type or p-type impurity. It is known to be several orders of magnitude larger. Therefore, by the above-mentioned light irradiation, in the interface level and the deep level in which electrons or holes are captured, by appropriately setting the measurement conditions during the measurement of the capacitance-voltage characteristics,
It becomes possible to keep the state of trapping electrons or holes.

Under such conditions, the interface level and the deep level can be regarded as mere fixed charges.
The dC / dV signal reflects only the shallow donor or acceptor concentration to be observed. That is, when measuring the impurity concentration distribution of the compound semiconductor sample with the scanning capacitance microscope, it becomes possible to eliminate the influence of the interface level and the deep level.

Further, in order to solve the problem that stable evaluation is difficult when evaluating a compound semiconductor in the above-mentioned problems, according to the scanning capacitance microscope of claim 2, the capacitance is measured by contacting the sample. Since the structure of the probe for measurement is covered with one or more insulating films on the conductor or conductive film, a MOS structure is formed between the probe and the sample surface through this insulating film. It

At this time, the unstable natural oxide film existing on the surface of the compound semiconductor sample can be scraped off by bringing the probe into contact and performing a scanning operation. Therefore, in the scanning capacitance microscope according to the second aspect, the insulating film of the probe is always in contact with the surface of the clean compound semiconductor sample, and the stable MOS structure is formed. Therefore, stable measurement is possible.

Furthermore, by providing a chamber for keeping the atmosphere around the probe and the sample to be an inert gas such as nitrogen or argon, a reducing gas such as hydrogen, or a vacuum, the sample being measured is naturally It is possible to suppress the change of the state of the oxide film or the re-formation of the natural oxide film, and it becomes possible to perform evaluation with higher stability.

In addition, a preliminary chamber for surface treatment of the sample or a chamber for transporting the sample from another device can be connected to the chamber, and the sample can be transported between both chambers without being exposed to the atmosphere. By having the mechanism, it becomes possible to evaluate a clean surface without a natural oxide film.

That is, the scanning capacitance microscope having the above-mentioned configuration is
It operates as a device having the following features. (1) When measuring the impurity concentration distribution of a compound semiconductor sample, by eliminating the effects of the interface level and the deep level,
Accurate impurity concentration measurement is possible. (2) The impurity concentration distribution can be measured even when the sample to be observed is a semiconductor cross section including a pn junction, a hetero junction, or the like in the observation plane. (3) When measuring the impurity concentration distribution of a compound semiconductor sample, stable measurement can always be performed. (4) Accurate impurity concentration measurement can be performed without oxidizing the surface after the crystal growth or the crystal surface treatment process.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment] FIG. 1 shows a scanning capacitance microscope according to the present embodiment. The scanning capacitance microscope of FIG. 1 includes a signal output terminal 1, a lock-in amplifier 2, a capacitance sensor 3, a lever 4, a probe 5, an AC bias power source 6, a DC bias power source 7, a sample stage 8, and a light source 9 as an irradiation unit. Is equipped with.

The probe 5 is made by being covered with a conductor or a conductor thin film. The probe 5 contacts the semiconductor sample 200 which is a compound semiconductor to be measured at the time of capacitance measurement. The AC bias power supply 6 and the DC bias power supply 7 apply an electric field between the semiconductor sample 200 and the probe 5. This electric field acts on the MOS structure formed between the probe 5 and the semiconductor sample 200 having a natural oxide film on the surface thereof, and produces a depletion layer corresponding to the bias potential on the surface of the semiconductor sample 200 ( (See FIG. 7).

Lock-in amplifier 2 and capacitance sensor 3
Detects the capacitance change dC with respect to the potential dV applied by the AC bias power supply 6. Then, the measurement is performed by obtaining the dC / dV signal from the lock-in amplifier 2. These are similar to FIGS. 6 and 7.

The light source 9 includes a light bulb 9A, a reflecting mirror 9B, and a DC power source 9C. The DC power source 9C supplies a DC voltage to the light bulb 9A. The light bulb 9A emits light having a photon energy equal to or higher than the band gap energy of the material forming the semiconductor sample 200. The light bulb 9A, together with the reflecting mirror 9B, irradiates the generated light on the contact portion between the probe 5 and the semiconductor sample 200. At this time, the light source 9 irradiates the contact portion between the probe 5 and the semiconductor sample 200 with light having a photon energy that is equal to or higher than the band gap energy of the material forming the semiconductor sample 200, so that the surface of the semiconductor sample 200 is irradiated. On the other hand, the light bulb 9A is arranged at a position where the irradiation light can be incident at a shallow incident angle.

As described above, in this embodiment, the contact portion between the probe 5 and the semiconductor sample 200, which is the measuring portion of the semiconductor sample 200, has a photon energy equal to or higher than the band gap energy of the material forming the semiconductor sample 200. Irradiate with light. This produces electron-hole pairs,
Capacitance evaluation is performed with electrons or holes always trapped at the interface level and the deep level.

Generally, the emission time constant of electrons or holes trapped in the interface level and the deep level is smaller than that of a shallow donor or acceptor formed by an n-type or p-type impurity. It is known to be several orders of magnitude larger. Therefore, at the interface level and the deep level at which electrons or holes are captured by the light irradiation from the light source 9, the capacitance −
By setting the measurement conditions appropriately during the measurement of the voltage characteristics, it becomes possible to keep the state in which the electrons or holes are trapped.

Under such conditions, the interface level and the deep level can be regarded as mere fixed charges, and dC /
The dV signal reflects only the shallow donor or acceptor concentration to be observed. That is, when measuring the impurity concentration distribution of the semiconductor sample 200 with the scanning capacitance microscope, it becomes possible to eliminate the influence of the interface level and the deep level.

In this embodiment, the light source 9A is used as the light source.
Was used. As a kind of the light bulb 9A, a halogen lamp, a metal halide lamp, a mercury lamp, or the like having a large light amount is effective. Also, various laser light sources can be used instead of the light bulb 9A. In this case, the controllability can be further improved.

A conventional scanning capacitance microscope may also be equipped with a light bulb as a light source for observing the sample, but the contact portion between the probe and the semiconductor sample is behind the probe itself, or The effect of the present invention could not be exerted because, for example, a sufficient amount of light cannot be incident on this contact portion.

[Second Embodiment] In the present embodiment, the structure of the probe is different from that of the first embodiment. This embodiment will be described with reference to FIG. 2A and 2B are explanatory views for explaining a scanning capacitance microscope according to a second embodiment of the present invention, and FIG. 2A mainly shows a tip end structure of a probe 12 of a lever 11, and FIG. FIG. 2B, which is a partially enlarged view in which the broken line portion m in a) is enlarged, shows the state of the contact portion between the probe 12 and the semiconductor sample 210 on the sample stage 13. The other parts are the same as the structure of the first embodiment.

In this embodiment, as in the case of the first embodiment, light having a photon energy equal to or higher than the band gap energy of the material forming the semiconductor sample 210 is applied to the contact portion between the probe 12 and the semiconductor sample 210. Has been done. In the present embodiment, the probe 12 is covered with a conductor or a conductor thin film as in the first embodiment. Furthermore, in the present embodiment, the tip of the conductive probe 12 is covered with the insulating film 12A. The tip of the probe 12 may be covered with one or more insulating films.

The probe 12 is swept during the capacitance measurement. In the process of sweeping the probe 12, the natural oxide film 211 on the surface of the semiconductor sample 210 is peeled off, so that the insulating film 12A formed at the tip of the probe 12 is in contact with the original surface of the semiconductor sample 210. . Therefore, according to the present embodiment,
It is possible to perform stable capacitance evaluation without being affected by the unstable natural oxide film 211.

As a method of peeling off the natural oxide film 211 of the semiconductor sample 210, the needle pressure applied to the probe 12 is adjusted by the adjusting means to the extent that the natural oxide film 211 is peeled off during the sweeping process of the probe 12. Further, in addition to the adjustment of the stylus pressure of the probe 12, the probe 12 is swept at least one reciprocation or more, and then the capacitance is measured.

By such capacitance measurement, more stable measurement becomes possible. In the conventional scanning capacitance microscope, the capacitance is measured while sweeping the probe in one direction. As an example of an effective sweeping method of the probe 12 in the present embodiment, the sweep direction is reversed after sweeping to a point slightly past the target point for evaluating the probe 12, and the capacitance of the target point is measured. The above operation is repeated. This means that
This is because the influence of the reformation of the natural oxide film 211 can be minimized by performing the capacitance measurement immediately after the natural oxide film 211 of the semiconductor sample 210 is peeled off by sweeping the probe 12.

That is, in the present embodiment, the semiconductor sample 2
The structure of the probe 12 for contacting with 10 to measure the capacitance is covered with one or more insulating films 12A on the conductor or conductor thin film. Therefore, a MOS structure is formed between the probe 12 and the surface of the semiconductor sample 210 via the insulating film 12A. At this time, the unstable natural oxide film 211 existing on the surface of the semiconductor sample 210 can be scraped off by bringing the probe 12 into contact and performing a scanning operation. Therefore, in the present embodiment, since the insulating film 12A of the probe 12 is always in contact with the surface of the clean semiconductor sample 210 to form a stable MOS structure, stable measurement is possible.

[Third Embodiment] In this embodiment, the atmosphere to be measured is different from that of the second embodiment. This embodiment will be described with reference to FIG. Note that FIG. 3B is a partially enlarged view in which the broken line portion n of FIG. 3A is enlarged.

In this embodiment, the lever 21 provided with the probe 22, the sample stage 23, and the semiconductor sample 220 on the sample stage 23 are housed in the chamber 24. A replacement gas is supplied to the chamber 24 from the introduction part 24A, and this replacement gas is discharged from the discharge part 24B. The replacement gas may be an inert gas such as nitrogen or argon, or a reducing gas such as hydrogen. Further, the inside of the chamber 24 may be evacuated. The other parts of this embodiment are the same as the structure of the second embodiment.

In this embodiment, the semiconductor sample 220 on the probe 22 and the sample stage 23 is provided by providing the chamber 24 and supplying the replacement gas to the chamber 24.
The atmosphere around the, inert gas such as nitrogen, argon,
Alternatively, a reducing gas such as hydrogen is used.

According to the present embodiment, in the process of sweeping the probe 22 covered with the insulating film 22A, the semiconductor sample 220 is
Since the native oxide film 221 on the surface of the
2A and the semiconductor sample 22 formed on the tip of
The original surface of 0 is in contact. Furthermore, the atmosphere around the probe 22 and the semiconductor sample 220 on the sample stage 23 is
It is possible to prevent the state of the natural oxide film 221 from changing or the natural oxide film 221 from being formed by applying an inert gas such as nitrogen or argon, a reducing gas such as hydrogen, or a vacuum. Therefore, evaluation with higher stability becomes possible.

[Fourth Embodiment] In the present embodiment, a chamber for surface treatment is connected to the chamber of the third embodiment. This embodiment will be described with reference to FIGS. 4 and 5. Note that FIG. 5 is a partially enlarged view in which the broken line portion p of FIG. 4 is enlarged.

In the present embodiment, as in the third embodiment, the lever 31 provided with the probe 32, the sample stage 33, and the semiconductor sample 23 on the sample stage 33.
0 is stored in the chamber 34. Chamber 3
The replacement gas is supplied to the nozzle 4 from the introduction section 34A, and the replacement gas is discharged from the discharge section 34B. The replacement gas may be an inert gas such as nitrogen or argon, or a reducing gas such as hydrogen. Further, the inside of the chamber 34 may be evacuated.

Further, in the present embodiment, the preliminary chamber 35 can be connected to the chamber 34 via the gate valve (connecting means) 36 for partitioning the chamber connecting portion. The preliminary chamber 35 is for surface treatment of the semiconductor sample 230. The semiconductor sample 230 can be transported between the preliminary chamber 35 and the chamber 34 without being exposed to the atmosphere. In this embodiment, the atmosphere around the probe 32 and the semiconductor sample 230 is an inert gas.

In the preliminary chamber 35, the surface treatment of the semiconductor sample 230 is performed by the chemical treatment using the chemical treatment 300 for surface treatment and the pure water 310 for cleaning. An inert gas is supplied to the auxiliary chamber 35 from the introduction part 35A, and this inert gas is discharged from the discharge part 35B. In FIG. 4, 37A and 37B are airtight gloves for operating the chamber 34 without introducing the outside air, and 38A and 38B are also airtight gloves for operating the chamber 35 without introducing the outside air. Is.

As described above, in FIG. 4, a chamber 34 for keeping the atmosphere around the probe 32 and the semiconductor sample 230 in an inert gas such as nitrogen or argon is used as a preliminary chamber for treating the sample surface with a chemical solution. 35 is connected.

According to this embodiment, the evaluation is performed in the following procedure. First, after removing the natural oxide film 231 on the sample surface with the chemical liquid 300 in the preliminary chamber 35 which is a glove box for chemical liquid treatment, the pure water 3 having a low oxygen concentration is used.
The chemical solution 300 is removed in 10. Next, the gate valve 36 is opened, and the semiconductor sample 230 is moved to the measuring chamber 34 by the carrying means. The gate valve 36 is closed and the measurement is started.

Since the natural oxide film 231 on the surface of the semiconductor sample 230 is removed during the sweeping process of the probe 32, the insulating film 32A formed on the tip of the probe 32 and the original surface of the semiconductor sample 230 are removed. Are in contact with. By forming the atmosphere around the probe 32 and the semiconductor sample 230 on the sample stage 33 into an inert gas such as nitrogen or argon, a reducing gas such as hydrogen, or a vacuum, a natural oxide film 231 is formed. It is possible to prevent such a situation, and a more stable evaluation is possible. That is, according to the present embodiment, the surface of the sample from which the natural oxide film 231 has been removed can be more stably evaluated.

Although FIG. 4 shows an example in which two glove boxes (chamber 34 and spare chamber 35) are connected, instead of the glove box for chemical treatment, a vacuum atmosphere or a non-existent atmosphere such as nitrogen or argon is used. If you use a transfer chamber or a portable transfer box that can transfer samples while maintaining an active gas atmosphere, you can use the scanning-type capacitance without contacting the atmosphere from the inside of the crystal growth equipment or process equipment for surface treatment. The sample can be transported into the microscope.

Although the embodiments of the present invention have been described in detail above, the specific configuration is not limited to these embodiments, and there are design changes and the like within the scope not departing from the gist of the present invention. However, it is included in the present invention.

[0056]

As described above, the present invention has the following effects. (1) When measuring the impurity concentration distribution of a compound semiconductor sample with a scanning capacitance microscope, by irradiating with light having a photon energy higher than the band gap energy of the material forming the sample, the interface level and the deep level It is possible to perform measurement without influence, and it is possible to accurately measure the impurity concentration distribution. (2) The structure of the probe for contacting the sample for capacitance measurement is covered with one or more insulating films on the conductor or conductive film, and further, on the compound semiconductor sample surface. Since it is possible to scrape off the existing unstable natural oxide film by performing a scanning operation by bringing the probe into contact, it is possible to measure the impurity concentration distribution with high stability. (3) In addition to the above effects, by providing an atmosphere around the probe and the sample with an inert gas such as nitrogen or argon, a reducing gas such as hydrogen, or a chamber for maintaining a vacuum, It is possible to prevent the state of the natural oxide film from changing or the formation of the natural oxide film in the sample under measurement, and it is possible to perform evaluation with higher stability. (4) Furthermore, a preliminary chamber for surface treatment of the sample or a chamber for transporting the sample from another device can be connected to the chamber, and the sample can be transported between the two chambers without being exposed to the atmosphere. This makes it possible to evaluate a clean surface without a natural oxide film.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a scanning capacitance microscope according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a scanning capacitance microscope according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining a scanning capacitance microscope according to a third embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining a scanning capacitance microscope according to a fourth embodiment of the present invention.

FIG. 5 is a partially enlarged view of a broken line portion p of FIG.

FIG. 6 is a configuration diagram showing a conventional scanning capacitance microscope.

FIG. 7 is a partially enlarged view in which a broken line portion u in FIG. 6 is enlarged.

[Explanation of symbols]

1 signal output terminal 2 Lock-in amplifier 3 capacitance sensor 4, 11, 21, 31 lever 5, 12, 22, 32 probe 12A, 22A, 32A insulating film 6 AC bias power supply 7 DC bias power supply 8, 13, 23, 33 Sample stage 9 light sources 9A light bulb 9B reflector 9C DC power supply 24, 34 chambers 24A, 34A introduction section 24B, 34B discharge part 35 Spare chamber 35A Introduction 35B discharge part 36 gate valve 37A, 37B, 38A, 38B Airtight gloves 200, 210, 220, 230 Semiconductor samples 211, 221, 231 Natural oxide film

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryuzo Iga             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Yasuhiro Kondo             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Tomoo Yamamoto             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 4M106 AA01 AA02 CB01 DH60

Claims (7)

[Claims] 1. A scanning capacitance microscope for measuring an electrostatic capacitance formed by a probe and a sample, wherein light having a photon energy equal to or higher than a band gap energy of a material forming the sample is supplied to the probe and the sample. A scanning capacitance microscope, comprising: an irradiation unit that irradiates a portion that comes into contact with. 2. The structure of the probe for contacting a sample for capacitance measurement is covered with a conductor or a conductive film, and one or more insulating films are formed on the conductor or the conductive film. The scanning capacitance microscope according to claim 1, wherein the scanning capacitance microscope is covered with. 3. An adjusting means for adjusting the stylus pressure applied to the probe so that the native oxide film on the surface of the sample in contact with the probe is peeled off during the sweeping process of the probe. The scanning capacitance microscope according to claim 2. 4. When evaluating the capacity of an arbitrary measurement point on a sample, at least one probe is set on the measurement point before starting the measurement.
The scanning capacitance microscope according to claim 3, further comprising means for performing capacitance measurement after sweeping at least twice. 5. The atmosphere around the probe and the sample is nitrogen,
3. An inert gas such as argon, a reducing gas such as hydrogen, or a vacuum.
4. The scanning capacitance microscope according to any one of 4 above. 6. The atmosphere around the probe and the sample is nitrogen,
An inert gas such as argon, a reducing gas such as hydrogen, or a chamber kept in vacuum, a preliminary chamber for surface treatment of the sample, or a chamber for transporting the sample from another device, and each of the above chambers 6. A connection means that enables connection of the sample and a transfer means that can transfer the sample between these chambers without contacting the atmosphere.
The scanning capacitance microscope according to. 7. A measuring method using a scanning capacitance microscope for measuring an electrostatic capacitance formed by a probe and a sample, wherein the probe is covered with a conductor or a conductive film, and Alternatively, by using the conductive film covered with one or more insulating films, the probe is brought into contact with the sample, and light having a photon energy higher than the band gap energy of the material forming the sample is Irradiate the contact portion between the probe and the sample, and adjust the needle pressure applied to the probe to such an extent that the native oxide film on the surface of the sample in contact with the probe is separated during the sweep process of the probe. When using a scanning capacitance microscope, which is characterized in that, when the capacity of an arbitrary measurement point on a sample is evaluated, the probe is swept at least one or more times at the measurement point before the measurement is started, and then the capacity is measured. The measuring method used.