JPH07221150A - Evaluation of deterioration of insulating film and device - Google Patents

Abstract

PURPOSE:To provide a highly reliable method of evaluating the deterioration of an insulating film, which can identify a change in the structure of the insulating film, which accompanies the deterioration of its electrical characteristics, and an insulating film deterioration evaluation device. CONSTITUTION:An insulating film deterioration evaluation device is characterized by providing the device with a sample holding part 1a for holding a sample 7 having an insulating film, insulating film deteriorating means 5, 6, 8, 9 and 10 for deteriorating electrically the insulating film, infrared ray emission means 2, 3a, 3b and 3c for emitting infrared ray on the insulating film and an infrared ray detecting means 4 for detecting transmission of the infrared ray to the insulating film or reflected infrared ray.

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 evaluating deterioration of an insulating film, and more particularly to a method and an apparatus for evaluating the film quality of an insulating film such as a gate oxide film in a MIS type semiconductor device.

[0002]

2. Description of the Related Art Improving the reliability of a gate oxide film of a MOS type semiconductor device is an important factor for improving the yield of VLSI. In particular, in the case of an EEPROM in which information is stored / erased by passing a tunnel current through the oxide film, a highly reliable gate oxide film that does not deteriorate or break when a high electric field is applied is essential.

Conventionally, deterioration of an oxide film has been grasped by an electrical evaluation method. The contents are classified into the following three. First, deterioration of the oxide film is observed as a change in the flat band voltage of the MOS capacitor, a change in the threshold voltage of the MOS transistor, and a decrease in mutual conductance. Secondly, in the thin film tunnel oxide film of 10 nm or less used in the EEPROM, a leakage current is generated in a low electric field region of 6 MV / cm or less by applying a high electric field of about 12 MV / cm. This is a deterioration mode of the oxide film which appears only in the thin oxide film. Thirdly, if the charge is continuously injected into the oxide film, dielectric breakdown of the oxide film occurs. Dielectric breakdown is observed as an irreversible and rapid increase in the gate current flowing through the oxide film.

Conventionally, the detection / evaluation of deterioration / destruction of an oxide film has been performed by electrical measuring means, for example, the measurement of the capacitance-voltage characteristic of a MOS capacitor and the measurement of the current-voltage characteristic. FIG. 8 is a schematic diagram showing the measuring means. As shown in this figure, a grounded stage 82 is installed inside the sample chamber 81, and the sample is placed on it. The sample is composed of, for example, a silicon substrate 83, a silicon oxide film 84, and a gate electrode 85 made of polysilicon. Reference numeral 86 is a capacitance voltage measuring device, 87 is a current voltage measuring device, and 88 is an input switch for these devices.
These electrical evaluations have been widely used as a standard method for characterization of oxide films because they enable easy measurement with high sensitivity.

Although the above-mentioned electrical evaluation method is certainly a method with high sensitivity, it is not sufficient as an evaluation means for improving the quality of the oxide film. In other words, in order to form a highly reliable oxide film, the phenomenon occurring in the oxide film when an electric field is applied is accurately grasped, the cause of the deterioration of the oxide film is clarified, and the result is applied to the oxide film formation process. Feedback is essential. However, it is difficult to grasp the phenomenon occurring in the oxide film on the atomic structure level based on the measurement result by the electrical evaluation. Therefore, the electrical evaluation method could not give a direction as to how to change the oxide film process to form an excellent oxide film.

Conventionally, no method has been known for evaluating the deterioration phenomenon of an insulating film such as an oxide film when a high electric field is applied in association with the structural change of the insulating film at the atomic level. The reason is that changes in the atomic structure that appear with changes in the electrical properties of the insulating film are minute, and measurement is forced at or below the sensitivity limit or near the sensitivity limit of the measuring device that captures the atomic structure of the insulating film. This is probably because reliable measurement could not be performed. Therefore, it is difficult to accurately feed back the measurement result to the insulating film formation process.

Further, in clarifying the structural change of the insulating film due to the application of the electric field, the following points should be noted.
One physical measurement method for evaluating the structure of the insulating film only gives the result of looking at the structure of the insulating film from a certain side, and in order to accurately grasp the phenomenon actually occurring in the insulating film, , Multi-faceted evaluation must be performed by combining several measurement methods.

In general, physical measurement for structural evaluation, for example, XPS (Xray Photoelectron)
Spectroscopy) and ESR (Electro
nSpin Resonance) and the like have lower sensitivity than electrical measurement, and therefore the insulating film needs to be sufficiently deteriorated in order to capture the structural change accompanying the deterioration of the insulating film. At that time, even after a local dielectric breakdown occurs in a part of the insulating film, the electric field may be continuously applied and further deteriorated, so that the physical evaluation method may fall within the range of sensitivity. In addition, in the electrical evaluation method, since a large current flows when insulation breakdown occurs in a part of the insulating film, it is not possible to evaluate the progress of deterioration after the insulation breakdown. It is necessary to compensate for this defect and provide a measure of insulating film deterioration that can be commonly used by several evaluation methods.

[0009]

As described above, conventionally, the phenomenon of deterioration of the electrical characteristics of the insulating film represented by the gate oxide film of the MOS type semiconductor device is associated with the structural change of the insulating film at the atomic level. No evaluation method is known, and no direction can be given regarding how to change the insulating film formation process to form an excellent oxide film.

Further, when the phenomenon actually occurring in the insulating film due to the application of an electric field is accurately grasped and the structural change of the insulating film is clarified, a multifaceted evaluation is performed by combining several measuring means. Although it must be done, conventionally, such an evaluation method has been very difficult.

An object of the present invention is to detect structural changes associated with changes in the electrical characteristics of an insulating film at the atomic level, and to measure even if a local dielectric breakdown occurs. An evaluation method and apparatus are provided.

[0012]

In order to solve the above problems, the present invention electrically deteriorates an insulating film, irradiates the deteriorated insulating film with infrared light, and transmits light from the insulating film. Alternatively, there is provided a method for evaluating deterioration of an insulating film, which comprises detecting reflected infrared light and evaluating the deterioration of the insulating film.

Further, according to the present invention, the insulating film is irradiated with infrared light, and transmitted or reflected infrared light from the insulating film is detected, and then the insulating film is electrically deteriorated. Irradiating the insulating film with infrared light again, detecting transmitted or reflected infrared light from the insulating film, and evaluating deterioration of the insulating film from the infrared light detected before and after deterioration An insulating film deterioration evaluation method is provided.

In the present invention, the substrate having an insulating film is irradiated with infrared light, and transmitted or reflected infrared light from the insulating film and a substrate portion other than the insulating film is detected, and then the insulating film is formed. Is electrically deteriorated, and after the deterioration, the infrared rays are irradiated again to the base, and the infrared rays transmitted or reflected from the base part other than the insulating film after the deterioration are detected, and the detected insulation is detected. After the amount of change in the infrared light transmitted or reflected from the base portion other than the film before and after the deterioration becomes a predetermined value or less, the insulating film after the deterioration is irradiated with infrared light again,
Detects transmitted or reflected infrared light from this insulating film,
There is provided a method for evaluating the deterioration of an insulating film, which comprises evaluating the deterioration of the insulating film from the infrared light detected before and after the deterioration.

In the method for evaluating the deterioration of the insulating film according to the present invention described above, the following modes are preferable. (1) A method for detecting infrared light transmitted or reflected from the insulating film is an infrared spectroscopy method using Fourier transform.

(2) The insulating film is a gate insulating film, a tunnel insulating film, or a capacitor insulating film. (3) The insulating film is a silicon oxide film.

(4) The base portion other than the insulating film is made of silicon. (5) A method of electrically deteriorating the insulating film is to sandwich the insulating film between a plurality of electrodes and apply a voltage between the electrodes, or to irradiate the insulating film with an electron beam. To do by doing.

Further, according to the present invention, a sample holding portion for holding a sample having an insulating film, an insulating film deterioration means for electrically deteriorating the insulating film, and a red for irradiating the insulating film with infrared light. There is provided an apparatus for evaluating the deterioration of an insulating film, comprising an external light irradiating unit and an infrared light detecting unit for detecting infrared light transmitted or reflected by the insulating film.

In the above-described apparatus for evaluating the deterioration of an insulating film according to the present invention, the following modes are preferable. (1) The insulating film degrading means for electrically degrading the insulating film is a counter electrode in which the sample is sandwiched and a predetermined voltage is applied by a power source, or an electronic bias is applied to the insulating film. -Be an electron beam irradiation means for irradiating a beam.

(2) A temperature evaluation means for evaluating the temperature of the insulating film is provided. (3) The apparatus is connected to an insulating film forming apparatus for forming the insulating film and an insulating film removing apparatus for removing the insulating film evaluated as defective.

[0021]

With the method and apparatus for evaluating deterioration of an insulating film according to the present invention, the transmittance (or reflectance) of infrared light transmitted or reflected by making infrared light emitted from an infrared light source incident on the insulating film of the sample. It is possible to evaluate how the absorption peak due to the natural vibration of the atoms forming the insulating film changes before and after the electric field is applied to the sample by measuring the wave number dependence of (1). From this evaluation result, it is possible to know the changes in the bond length and the bond angle before and after the deterioration of the insulating film.

Therefore, the result of the change of the insulating film can be used to give a direction as to how to change the insulating film forming process to form an excellent oxide film.

Further, since the deterioration of the insulating film can be measured in a non-contact manner, it can be measured even if a local dielectric breakdown occurs. In the present invention, it is desirable not to move the position of the sample before and after applying an electric field to the sample, which can eliminate the spectrum change due to the position error.

[0024]

Embodiments of the method and apparatus for evaluating the deterioration of an insulating film according to the present invention will be described below in detail with reference to the drawings. First Embodiment FIG. 1 is a schematic diagram showing the configuration of an insulating film deterioration evaluation apparatus according to the first embodiment of the present invention. As shown in this figure, a sample chamber 1a is provided inside the evaluation apparatus 1, and a sample 7 is placed inside this sample chamber 1a. Two electrodes 5 and 6 also serving as a sample stand are closely attached to the sample 7 so as to sandwich the sample 7, and lead wires 8 and 9 are drawn out from these electrodes 5 and 6 to the outside. There is. These lead wires 8 and 9 are connected to the power supply device 10 so that a predetermined voltage can be applied between the electrodes 5 and 6. Here, a hole is formed in each of the central portions of the electrodes 5 and 6 for transmitting infrared light.

FIG. 2 is an enlarged view showing the structure of the above-mentioned sample table portion. As shown in this figure, the electrode 5 is composed of a combination of a metal outer plate 11 and a middle plate 13. On the other hand, the portion of the electrode 6 is a metal outer plate 14
Made of. These metal outer plates 11 and 14
Are clamped and fixed by the insulating plate 15. Middle plate 13
Is movable, and the inner plate 13 and the outer plate 11 are connected by a total of four metal screws 12. As the sample 7 sandwiched by the electrodes 5 and 6, a silicon substrate 16 having a surface on which a silicon oxide film 17 and a gate electrode 18 are sequentially laminated is used. The sample 7 is fixed to the sample stage so that the holding surface of the middle plate 13 is in close contact with the front surface of the gate electrode 18 and the holding surface of the outer plate 14 is in close contact with the back surface of the silicon substrate 16, respectively, so that the gate electrode 18 of the sample is fixed. Electrical contacts are made to the back surface of the silicon substrate 16 and. In this figure, 19 is a metal outer plate 11,
The infrared light is transmitted through a hole formed in the center of the middle plate 13 and the outer plate 14.

A light source 2 for generating infrared light is provided inside the evaluation device 1 outside the sample chamber 1a. The infrared light generated by the light source 2 is made incident on the inside of the sample chamber 1a by the mirrors 3a, 3b, 3c, passes through the holes formed at the central portions of the electrodes 5, 6 and is made incident on the sample 7, Through.
The transmitted infrared light is incident on the infrared light detection unit 4, and the change in the infrared absorption characteristics of the sample 7 can be accurately measured by the information of the infrared light detected by the detection unit 4. Has become. The above-mentioned Mira-3a is a semi-transparent mirror and has a function of separating infrared light from the light source 2 into transmitted light to the Mira-3b and reflected light to the Mira-3c.
The Mira-3b is fixedly arranged, and the Mira-3c is installed so as to reciprocate in the direction of the arrow in FIG.

As described above, the apparatus for evaluating the deterioration of the insulating film according to this embodiment is FT-IR (F-F) using Fourier transform.
ourour Transform-Infrar
ed) The infrared spectroscopic device has a structure in which an electrode unit to which a voltage can be applied is arranged.

Next, a method for evaluating the deterioration of the capacitor insulating film of the MIS capacitor by using the above-mentioned evaluation device for the deterioration of insulating film will be described. First, the evaluation device 1 shown in FIG.
A sample 7 having a MOS capacitor formed therein is sandwiched by two electrodes 5 and 6 inside a sample chamber 1a inside and placed on a sample table.

The sample 7 was manufactured as follows. That is, a p-type silicon substrate having a plane orientation of (100) formed by the Czochralski method is oxidized at 900 ° C. in a dry oxygen atmosphere to form a 90 nm thermal oxide film, and then a 200 nm polycrystalline film is formed thereon. Deposit a silicon film,
Phosphorus diffusion was performed at 900 ° C. for 30 minutes. Then, the polycrystalline silicon film was patterned to form a MOS capacitor. Here, the reason why polycrystalline silicon is used for the gate is that polycrystalline silicon is transparent to infrared light and the infrared absorption of the silicon oxide film can be measured. Further, the thickness of the polycrystalline silicon film is reduced to 200 nm in order to suppress spectrum distortion due to the interference effect of infrared light.

Next, the sample 7 placed on the sample table as described above.
An electric field is applied to the MOS capacitor. That is, the power supply device 10 applies a predetermined voltage between the electrodes 5 and 6 so that an electric field of, for example, 7 MV / cm is applied to the capacitor insulating film (silicon oxide film) of the MOS capacitor.

Further, the MOS to which the electric field is applied as described above
Infrared light is emitted from the light source 2 to the capacitor portion, and the infrared light transmitted through the MOS capacitor is detected by the infrared light detecting section 4. With the information on the infrared light detected in this way, the change in the infrared absorption characteristics of the sample 7 can be accurately measured.

The apparatus for evaluating the deterioration of the insulating film in this embodiment has a structure in which the sample stage is fixedly incorporated in the FT-IR infrared spectroscope, and the sample is subjected to the above-mentioned test before and after applying an electric field. Since it is kept fixed on the sample table,
It is possible to accurately measure changes in infrared absorption characteristics.
That is, after measuring the infrared absorption characteristics of the sample in the initial state inside the FT-IR infrared spectroscope, the sample is removed from the sample stage, and the sample is put on the sample by a prober or the like outside the FT-IR infrared spectroscope. Compared with the case where an electric field is applied to the sample and then the sample is returned to the FT-IR infrared spectrometer again to measure the infrared absorption characteristics of the sample, the error in the infrared absorption spectrum due to misalignment is reduced. be able to.

Next, the sample (MOS
The infrared absorption characteristics of the capacitor will be described. MOS
An electric field of 7 MV / cm was applied to the capacitor insulating film (silicon oxide film) of the capacitor for 1 hour and 40 minutes, and the spectrum of the difference in the infrared light absorptivity before and after the application of the electric field was examined. FIG. 3 is a characteristic diagram showing this result. In this figure, the physical quantity (difference spectrum) on the vertical axis indicates the Si—O—Si stretching vibration (2
The absorption wave number distribution of (O vibration in the direction parallel to the direction connecting two Si atoms) is subtracted from that before the electric field is applied. Therefore, for example, when the peak of the absorption wave number appears on the lower wave number side (the lower frequency side) than the valley, the absorption peak wave number of the stretching vibration changes to the lower wave number side from before the electric field is applied to after the electric field is applied. Will be there.

As can be seen from the distribution of the difference spectrum shown in FIG. 3, the absorption peak wave number (near 1080 cm ^-1 ) of the Si-O-Si stretching vibration is changed to the low wave number side by the electric field application. . This is Si-O
It is considered that the bond length of the bond was increased and the interatomic bond strength was weakened, or the angle of the Si—O—Si bond was decreased. When the change is observed together with the absorption peak wave number of the bending vibration of Si-O-Si (the vibration of O in the direction perpendicular to the direction connecting two Si atoms), the change in either bond length or bond angle is dominant. It is possible to know specifically. That is, when the absorption peak wave number of the stretching vibration is changing to the low wave number side, if the absorption peak wave number of the bending vibration is changing to the high wave number side, the change of the bond angle of the Si—O bond is dominant. On the contrary, when the absorption peak wave number of the stretching vibration is changing to the high wave number side, if the absorption peak wave number of the bending vibration is changing to the low wave number side, the change in the bond distance of the Si—O bond is dominant. Is.

Further, the relationship between the application time of the electric field stress and the magnitude of the difference spectrum when the electric field was continuously applied to the above sample was examined. FIG. 4 is a characteristic diagram showing the relationship. From this figure, it is understood that the difference spectrum becomes larger as the electric field stress time becomes longer. From this,
It was found that the magnitude of the difference spectrum of Si-O-Si stretching vibration can be used as a measure of oxide film deterioration.

According to the evaluation method and apparatus of this embodiment,
Since the deterioration of the oxide film is measured in a non-contact manner, the deterioration of the oxide film can be continuously measured even if a local dielectric breakdown occurs in a part of the oxide film. That is, it is possible to provide a measure of deterioration regardless of whether or not the insulating film is locally destroyed. Furthermore, since the deterioration of the insulating film can be measured without physically destroying the sample, the structural change of the insulating film due to the application of the electric field can be continuously measured for one sample many times.

Furthermore, as shown in the above embodiment, the present invention can detect the structural change of the oxide film when the electric field stress of 7 MV / cm is applied. This is due to the fact that the present invention causes a problem in the tunnel oxide film.
It covers the range (7 MV / cm or more) of the electric field in which the ler-Nordheim tunnel current flows, and shows that it is effective as an evaluation method of the tunnel oxide film.

Second Embodiment Next, a second embodiment of the present invention will be described. In this example, the temperature of the sample was evaluated by measuring the infrared absorption spectrum, and after the temperature difference of the sample before and after the application of the electric field was within a predetermined range, the infrared absorption spectrum after the oxide film was deteriorated. To measure.

When an electric field is applied to the sample, power is consumed and the temperature of the sample rises. Along with this, the spectrum of infrared absorption changes. FIG. 6 is a characteristic diagram showing the relationship between the magnitude of the difference spectrum and the wave number of infrared light when the electric field stress application time reaches 6000 seconds. In this figure, the magnitude of the difference spectrum including the temperature rise is shown. As can be seen from FIG. 6, it has been found that the amount of change in the spectrum is as large as or more than the amount of change in the spectrum due to deterioration of the oxide film. Therefore, in order to strictly evaluate the deterioration of the oxide film due to the application of the electric field, it is necessary to measure the infrared absorption characteristics by equalizing the temperatures of the sample before and after the application of the electric field.

In this embodiment, the absorption peak of the silicon substrate existing in the wave number region (around 700 cm ^-1 ) where the infrared absorption of the silicon oxide film does not exist is used as a temperature monitor. That is, first, the temperature of the silicon substrate is changed and the relationship between the substrate absorption peak wave number and the substrate temperature is measured in advance. Next, when the electric field is actually applied to the sample (the silicon substrate on which the MOS capacitor is formed) or after the electric field is applied, the relationship between the absorption peak wave number of the silicon substrate and the silicon substrate Determine the temperature of. Since the temperature of the sample capacitor insulating film is almost equal to the temperature of the silicon substrate, the temperature of the capacitor insulating film can be obtained by the above method.

Next, the procedure for measuring the deterioration of the insulating film will be described. FIG. 5 is a flowchart showing this measurement procedure. As shown in this flow chart, first, the initial infrared absorption spectrum of the sample (silicon substrate on which the MOS capacitor is formed) before applying the electric field is measured (30). Next, capacitor oxide film (silicon oxide film)
After applying the electric field to (31), the application of the electric field is stopped.
Then, the infrared absorption spectrum of the sample after applying the electric field is measured (32). Immediately after the application of the electric field is stopped, the temperature of the sample is considerably higher than the temperature before the application of the electric field due to the application of the electric field. Therefore, the temperature of the sample is determined by the above-described method, and it is determined whether or not the difference between this temperature and the sample temperature before application of the electric field is below a predetermined value. In practice, the absorption peak wave number of the infrared absorption spectrum of the silicon substrate may be used as a parameter for this determination. In this case, the absorption peak wave number of the silicon substrate is centered on that value before the electric field is applied. It is judged whether or not it falls within the predetermined wave number range (33).

When the absorption peak wave number described above falls within a predetermined wave number range, the temperature difference between the sample before and after the electric field is applied falls within a preset range. The external absorption spectrum is measured and the deterioration of the oxide film is evaluated (34). On the other hand, when the absorption peak wave number does not fall within the predetermined wave number range,
The absorption peak wavenumber of the silicon substrate was repeatedly measured until the temperature difference between the sample before and after the electric field was applied fell within the preset range, and after confirming that it fell within the set range, the infrared absorption spectrum of the capacitor oxide film was confirmed. Similarly, the oxide film deterioration is evaluated. As described above, by measuring the infrared absorption characteristics after the insulating film is deteriorated after the effect of the temperature rise of the sample after applying the electric field becomes negligible, it is possible to reduce the spectrum change due to the temperature error.

According to this embodiment, the temperature of the capacitor oxide film can be simultaneously measured by using the same infrared light as the infrared light used for measuring the infrared absorption spectrum of the capacitor oxide film. Therefore, it is possible to accurately evaluate the deterioration of the insulating film without complicating the evaluation device.

Third Embodiment Next, an evaluation apparatus for deterioration of an insulating film according to a third embodiment of the present invention will be described. FIG. 7 is a schematic diagram showing the configuration. As shown in this figure, the insulating film deterioration evaluation apparatus of the present invention is of a single-wafer type, and includes an insulating film forming chamber 20a that oxidizes silicon wafers 21 one by one, a non-contact insulating film deterioration device 22 and a red film. It is characterized by comprising an insulating film evaluation chamber 20b having an external absorption measuring device 26 therein and a wafer sorting chamber 20c. In this figure, 24
Is a light source for generating infrared light, and 25 is infrared light emitted from the light source 24. An electron beam 23 is emitted from the non-contact insulating film deterioration device 22.

The above-described evaluation apparatus of this embodiment has a wafer screening function as well as an insulating film forming function. By connecting the evaluation apparatus to another process apparatus group in this way, it is possible to realize a continuous manufacturing process. Thus, the wafer can be efficiently screened in a form consistent with the manufacturing process.

Next, an evaluation method of insulating film deterioration using the above evaluation apparatus will be described. In the evaluation apparatus shown in FIG. 7, first, an insulating film (silicon thermal oxide film or the like) is formed on the surface of the silicon wafer 21 in the insulating film forming chamber 20a, and the wafer 21 after the insulating film formation is continuously formed. It is transported into the insulating film evaluation chamber 20b. After the transfer, infrared absorption measurement is performed on the insulating film on the surface of the wafer 21. Next, in the insulating film evaluation chamber 20b, the non-contact insulating film deterioration device 22 is used to deteriorate the insulating film. Here, the wafer 21
The insulating film is deteriorated by irradiating the area other than the device forming area on the surface with the electron beam 23. Irradiation with the electron beam 23 causes the same defects in the insulating film as when an electric field is applied, so that the deterioration of the insulating film when an electric field is applied can be artificially generated. Next, the infrared absorption measurement is performed again on the deteriorated insulating film, and the degree of deterioration of the insulating film is judged from the two infrared absorption difference spectra. The insulating film that has deteriorated beyond the reference value is removed in the wafer sorting chamber 20c.

As described above, a non-contact insulating film deterioration measuring mechanism is incorporated in the middle of the insulating film forming process to screen wafers, and defective wafers are found and removed early to eliminate unnecessary processes. Therefore, work efficiency up to device formation can be improved.

The present invention is not limited to the above embodiment. For example, the insulating film to be evaluated is not limited to the silicon oxide film, but a silicon nitride film, a silicon oxynitride film (oxynitride), a transition metal oxide film having a high dielectric constant such as a tantalum oxide film, a strontium titanate film, or a barium titanate film. It is possible to investigate the insulation deterioration characteristics of a high dielectric constant perovskite oxide film such as a film.

Further, in the evaluation apparatus of the present invention, the holes formed in the electrodes for sandwiching the sample in order to irradiate the sample with infrared light are not limited to the embodiment shown in the above embodiment, but may have various shapes. You can Further, for example, instead of the holes, slit-shaped openings may be provided in the electrodes. With this configuration, the infrared light is scanned in one direction along the slit-shaped opening, and the detection unit for detecting the infrared light is also moved in synchronization with the infrared light. It is possible to continuously evaluate deterioration of the insulating film in one direction.

Further, the method of detecting the infrared light applied to the insulating film of the sample is not limited to the method of detecting the infrared light transmitted through the insulating film, and the infrared light reflected on the surface of the insulating film may be detected. It may be a method of detecting. In this case, it is preferable that the above-mentioned slit-shaped opening is provided in the electrode and the infrared light is irradiated obliquely to the surface of the insulating film at an angle of incidence equal to or greater than the angle at which total reflection occurs. Infrared light from the surface can be easily detected. In addition, various modifications can be made without departing from the scope of the present invention.

[0051]

As described above, according to the present invention, by grasping a minute change in the infrared absorption spectrum due to the application of an electric field, the structural change of the insulating film can be regarded as a change in the bond bond length and the bond angle. The evaluation can be performed with good performance, and it is possible to efficiently feed back to the process of forming the insulating film.

Further, since the deterioration of the insulating film is measured in a non-contact manner, it is possible to measure the progress of the deterioration even after the insulating film is locally electrically damaged, and whether or not the insulating film is locally damaged. It is possible to provide a deterioration measure that does not depend on Furthermore, by applying the present invention to wafer screening in an insulating film forming apparatus, the efficiency of LSI manufacturing can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an insulating film deterioration evaluation apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing details of the configuration of the evaluation device in FIG.

FIG. 3 is a characteristic diagram showing a difference spectrum of infrared absorption before and after applying an electric field to a sample.

FIG. 4 is a characteristic diagram showing the relationship between the stress time when an electric field is applied to a sample and the size of the difference spectrum of infrared absorption.

FIG. 5 is a flowchart showing an algorithm for determining a temperature difference used in the second embodiment of the present invention.

FIG. 6 is a characteristic diagram showing a difference spectrum between an infrared absorption spectrum when an electric field is applied to the sample and an infrared absorption spectrum before the electric field is applied.

FIG. 7 is a schematic configuration diagram of a single-wafer type insulating film forming apparatus having a wafer screening function according to a third embodiment of an insulating film deterioration evaluating apparatus according to the present invention.

FIG. 8 is a schematic diagram showing the configuration of a conventional electrical oxide film deterioration measuring device.

[Explanation of symbols]

 1 Evaluation device, 1a Sample chamber, 2 Infrared light generation light source, 3a, 3b, 3c mirror, 4 Infrared light detection part, 5, 6 electrode, 7 sample, 8, 9 lead wire, 10 power supply device, 11 Metal Made outer plate, 12 metal screw, 13 metal middle plate, 14 metal outer plate, 15 insulating plate, 16 silicon substrate, 17 silicon oxide film, 18 gate electrode, 19 infrared light, 20a insulating film Forming chamber, 20b insulating film evaluation chamber, 20c wafer sorting chamber, 21 silicon wafer, 22 non-contact insulating film deterioration device, 23 electron beam, 24 infrared light generating light source, 25 infrared light, 26 infrared absorption measuring device .

Claims (12)

[Claims] 1. An insulating film is electrically deteriorated, infrared light is irradiated to the deteriorated insulating film, and transmitted or reflected infrared light from the insulating film is detected to detect the insulating film. An insulating film deterioration evaluation method, characterized by evaluating deterioration. 2. The insulating film is irradiated with infrared light, and after detecting transmitted or reflected infrared light from the insulating film, the insulating film is electrically deteriorated and the deteriorated insulating film is formed. Insulation characterized by irradiating infrared light again, detecting transmitted or reflected infrared light from this insulating film, and evaluating deterioration of the insulating film from the infrared light detected before and after deterioration. Evaluation method of film deterioration. 3. A substrate having an insulating film is irradiated with infrared light, and after detecting transmitted or reflected infrared light from the insulating film and a substrate portion other than the insulating film, the insulating film is electrically treated. After the deterioration, the substrate is irradiated with infrared light again, and the infrared light transmitted or reflected from the substrate portion other than the insulating film after the deterioration is detected to detect other than the detected insulating film. After the change amount of the infrared light transmitted or reflected from the base portion before and after the deterioration becomes equal to or less than a predetermined value, the deteriorated insulating film is irradiated with infrared light again, and transmitted or reflected from the insulating film. A method for evaluating the deterioration of an insulating film, which comprises detecting reflected infrared light and evaluating the deterioration of the insulating film from the infrared light detected before and after the deterioration. 4. The insulation film deterioration according to claim 1, wherein the method of detecting the infrared light transmitted or reflected from the insulation film is an infrared spectroscopy method using Fourier transform. Evaluation methods. 5. The method for evaluating the deterioration of an insulating film according to claim 1, wherein the insulating film is a gate insulating film, a tunnel insulating film, or a capacitor insulating film. 6. The method for evaluating deterioration of an insulating film according to claim 1, wherein the insulating film is a silicon oxide film. 7. The method for evaluating the deterioration of an insulating film according to claim 3, wherein the base portion other than the insulating film is made of silicon. 8. A method of electrically deteriorating the insulating film comprises sandwiching the insulating film between a plurality of electrodes and applying a voltage between the electrodes, or by applying an electron beam to the insulating film. The irradiation is performed by irradiating
A method for evaluating deterioration of an insulating film as described. 9. A sample holding part for holding a sample having an insulating film, an insulating film deterioration means for electrically deteriorating the insulating film, and infrared light irradiation for irradiating the insulating film with infrared light. An insulating film deterioration evaluation apparatus comprising: a means; and an infrared light detecting means for detecting infrared light transmitted or reflected by the insulating film. 10. The insulating film degrading means for electrically degrading the insulating film is a counter electrode in which the sample is sandwiched and to which a predetermined voltage is applied by a power source, or with respect to the insulating film. 10. An apparatus for evaluating the deterioration of an insulating film according to claim 9, which is an electron beam irradiation means for irradiating an electron beam. 11. The apparatus for evaluating the deterioration of an insulating film according to claim 9, further comprising temperature evaluation means for evaluating the temperature of the insulating film. 12. The insulating film deterioration device according to claim 9, further comprising an insulating film forming device for forming the insulating film and an insulating film removing device for removing the insulating film evaluated as defective. Evaluation device.