JP2003183838A - Oxide film-forming apparatus and magnetic recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide film-forming apparatus for forming and controlling an oxide film having a thickness on the order of nanometer, which is the main element of a magnetoresistive sensor. <P>SOLUTION: The metal oxide film-forming apparatus having at least one metal thin film-forming chamber and at least one metal thin film-oxidizing chamber has an infrared source, a sample-supporting board, a spectroscope, an infrared detector, an infrared spectrum-treating means, a system for vacuum- transporting the sample from the metal thin film-oxidizing chamber to the sample-supporting board, a means for applying an infrared ray at an angle of incidence of 0.5-20° against the surface of the sample on the sample-supporting board wherein the sample is obtained by oxidizing in the metal thin film- oxidizing chamber, a metal thin film formed in the metal thin film-forming camber, and a means for measuring the infrared reflectance of the sample. Based on the measured reflectance, the thickness and/or the binding state of the oxide film on the metal thin film is controlled. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention oxidizes a metal thin film having one or more layers formed on a substrate, measures the reflectance of infrared light, and measures the film thickness of the metal oxide film and the bond between metal atoms and oxygen atoms. The present invention relates to an oxide film forming device for managing the state.

[0002]

2. Description of the Related Art In the field of magnetic files, an element is formed by laminating an insulating layer and a metal layer and forming a pattern. Aiming at higher performance and higher performance of the device, the number of films to be formed is increasing as the film to be formed becomes extremely thin. Further, improvement of performance by forming an oxide film having a thickness of nm in a multi-layered film is being studied. Since the thickness of the nm oxide film and the bond between metal atoms and oxygen atoms greatly affect the characteristics of the device, a method of controlling and controlling the thickness of the nm oxide film is required.

"Solid surface-micro area analysis / evaluation technology"
As described in, the absorption spectrum of infrared light is a powerful method to know the binding state of organic substances and the like. Particularly, the high-sensitivity reflection absorption method is an effective method for measuring the infrared absorption spectrum of an organic thin film on a smooth metal substrate. The high-sensitivity reflection (absorption) method uses P-polarized light in which the vibration direction of the electric field vector of light is parallel to the incident surface. When P-polarized light is reflected on the substrate surface, the electric field vectors of the incident light and the reflected light are combined to form a strong standing wave, so S-polarized light (the oscillation direction of the electric field vector of light is perpendicular to the incident surface). The sensitivity is increased as compared with the case where the light is reflected. Maximum of 5 for P-polarized light and S-polarized light
There is a difference in absorbance by several orders of magnitude. In addition, P-polarized light can increase sensitivity by about one to two digits compared to the transmission method.

However, it has been considered difficult to measure the absorption of a nm thin film even by using the above-mentioned reflection absorption method because the absorption of the thin film is very small. Recently, Ap
In plied Physics Letters Vol.78 pp.3103, the result of evaluating the nm oxide film using infrared light was reported. In this paper, about 50 nm cobalt is deposited on a silicon substrate, 0.5-2.5 nm thick aluminum is stacked on top of it, then aluminum is plasma-oxidized, and finally 4 nm titanium is deposited as a cap film. The sample is irradiated with radiant light and the reflectance of infrared light from the sample is measured to determine the film thickness of aluminum oxide.

[0005]

[Problems to be Solved by the Invention] Applied Physics Lett
The prior art described in ers Vol.78 pp.3103 uses synchrotron radiation, so it is difficult to incorporate it into an oxide film forming apparatus. In addition, the conventional technique has about 50 below the metal oxide film to be measured.
By placing a cobalt film of nm, the measurement is performed in the same state as when the metal substrate is below the metal oxide film. But,
It is not possible to add a process of forming a thick metal film such as a 50 nm cobalt film in the process of making an actual device.

Further, in the above-mentioned conventional technique, after forming the metal oxide film, it is necessary to form a cap film so that the oxidation does not proceed. It is difficult to measure a metal oxide film without being affected by the oxidation of the cap film. Further, it is impossible to add a process such as re-oxidizing after measuring the thickness of the metal oxide film.

In addition, since the magnetoresistive sensor used in the magnetic recording / reproducing apparatus has been improved in performance by using an oxide film, the film thickness of the oxide film and the coupling state greatly affect the performance.
Therefore, it is important to control and manage the thickness of the oxide film and the bonding state in the oxide film formation process.

SUMMARY OF THE INVENTION An object of the present invention is to provide an oxide film forming apparatus which enables on-process evaluation of the film thickness and bonding state of a metal oxide film. Another object of the present invention is to provide a magnetic recording / reproducing apparatus using a magnetoresistive sensor manufactured by the oxide film forming apparatus.

[0009]

An apparatus for forming a metal oxide film according to the present invention is an apparatus for forming an infrared light source and a sample, which comprises one or more metal thin film forming chambers and one or more metal thin film oxidizing chambers. Table, spectroscope, infrared light detector, means for processing infrared light spectrum, mechanism for vacuum-transporting sample from the metal thin film oxidation chamber to the sample support, metal deposited in the metal thin film deposition chamber A sample obtained by oxidizing a thin film in the metal thin film oxidation chamber,
In the sample support table, infrared light is applied to the sample surface.
It has means for incidence in the angle range of 0.5 ° to 20 °, and means for measuring the reflectance of infrared light from the sample. From the reflectance, the thickness of the oxide film on the metal thin film and / or the oxide film It is characterized by managing the combined state.

In the present invention, the reason why infrared light is incident on the surface of the sample in the angle range of 0.5 ° to 20 ° is that absorption of P-polarized light is large in the angle range of 0.5 ° to 20 °, which is different from the transmission method. This is due to the effect of increasing the sensitivity by one to two digits in comparison. Particularly, the angle range of 0.5 ° to 2 ° is more preferable because the absorption of P-polarized light is maximized. Thus, when a thin film is evaluated by the reflection absorption method, the absorption from the sample largely depends on the incident angle. Therefore, in order to quantitatively evaluate the infrared absorption amount, it is necessary to control the angle between the sample and the incident infrared light with high accuracy.

The reflectance of infrared light measured is 500 / cm.
It is preferably in the wave number region of ˜1200 / cm. Generally, 50
The absorption of the window material on the lower wave number side than 0 / cm reduces the signal intensity, making it difficult to measure the absorption of the sample. Further, the absorption of the metal oxide film is found on the lower wave number side than about 1200 / cm. However, the position of absorption shifts depending on the metal that oxidizes. From the above, the wave number region is set to 500 / cm to 1200 / cm. In addition, as a metal thin film, aluminum,
Iron, nickel, cobalt, and alloys thereof are preferably exemplified.

The oxide film forming apparatus further includes a laser oscillator, an optical system for making laser light incident on a sample, a detector for detecting laser light reflected by the sample placed on the sample support, and a sample support. The sample and incident infrared rays have a goniometer for adjusting the angle and position of the sample stage, a means for processing the signal from the detector and a means for driving the goniometer, and using the laser beam and the laser beam reflected on the sample surface. It is preferable to adjust the angle formed by the light.

Further, the magnetic recording / reproducing apparatus of the present invention comprises a magnetic recording medium, a magnetoresistive sensor for reading a magnetic signal written in the medium, a write head for writing a magnetic signal, the magnetoresistive sensor and a write head. Magnetic recording equipped with an arm mounted on the tip end to drive the magnetic recording medium in the radial direction, a control unit for controlling the magnetic recording medium and arm driving means, and signal processing means for processing read and write signals of magnetic signals. In the reproducing apparatus, a magnetoresistive sensor in which the film thickness and the bonding state of the oxide film are controlled and managed by the metal oxide film forming apparatus according to any one of claims 1 to 4 is mounted.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows one embodiment of the present invention. A metal thin film is formed on a sample by a DC sputtering method on a substrate placed on a film formation sample support base 2 inside the film formation chamber 1. Next, open the gate valve 39, and using the arm of the sample moving robot 4,
The sample is moved from the film formation sample support base 2 to the sample moving chamber 3 and the gate valve 39 is closed. After that, the gate valve 40 is opened, the sample is moved onto the oxidation chamber sample support base 6, and the gate valve 40 is closed. The oxidizing chamber 5 can expose the sample to an oxygen atmosphere, or can generate plasma while introducing oxygen to oxidize the sample surface by plasma. After oxidizing the sample, the gate valve 40 is opened again, the sample is moved to the sample moving chamber 3, the gate valve 40 is closed, the gate valve 41 is opened, and the sample 9 is moved onto the sample support 8. By this work, the sample
9 is not exposed to the atmosphere except for the purpose of oxidation.

The metal thin film formed in the film forming chamber 1 may be iron, nickel, cobalt, or an alloy thereof, in addition to aluminum. In addition to the DC sputtering method, RF sputtering method, vacuum deposition, molecular beam epitaxy can be used as film forming means.
(MBE), CVD method, etc. can also be used.

Next, the structure of the infrared light reflectance measuring instrument using the reflection absorption method will be described. Infrared light generated by the infrared light source 10 that uses a W filament is shaped by the slit 11,
The collimator mirror 12 collimates the light. The front mirror 13 changes the optical path so that the incident angle to the sample is about 4 °, and the polarization element 14
Adjust the polarization so that only P-polarized light is incident on the sample.
The infrared light reflected by the sample 9 is reflected by the rear-end mirror 15 and enters the beam splitter 16. One of the infrared rays split by the beam splitter 16 is reflected by the fixed mirror 17 and returns to the beam splitter 16. The other infrared light is reflected by the movable mirror 18 and returns to the beam splitter 16. The infrared light reflected by the fixed mirror 17 and the movable mirror 18 interferes with each other by the beam splitter 16, and
Enter detector 20 via 19. The wavelength dependency of the reflectance is derived by measuring the intensity of the detector 20 while changing the position of the movable mirror 18 and performing a Fourier transform with a calculator (not shown). The optical system downstream from the rear-view mirror is called a Michelson interference optical system and is generally used as an optical system for infrared sensitive spectroscopy. As a window material used for a window for introducing infrared light from the pre-analysis chamber 42 into the analysis chamber 7 and a window for introducing reflected light into the post-analysis chamber 42, KBr, NaCl, and CaF that are common in infrared light experiments are used. ₂ , LiF, etc. were used. In addition, in order to reduce the influence of infrared light absorption of carbon dioxide and moisture in the air, the pre-analysis chamber 42 and post-analysis chamber 43
The inside of the chamber is evacuated by a vacuum pump (not shown) so that the experiment can be performed.

When the sample 9 whose oxide film has been evaluated by the infrared reflectance measuring instrument is not sufficiently oxidized, the gate valve 41 is opened again, and the sample transfer chamber 3 is moved to the sample transfer chamber 3 by using the arm of the sample transfer robot 4. 9 is moved and the gate valve 41 is closed. Next, the gate valve 40 is opened, and the sample is moved onto the sample support base 6 for the oxidation chamber. Finally, the gate valve 40 is closed and the sample is subjected to additional oxidation in the oxidation chamber 5. According to the procedure described above, the sample is moved to the sample support base 8 in the measurement chamber 7, the infrared light reflectance is measured, and the oxide film is evaluated again. The same operation is repeated until the oxidation of the sample reaches the desired state. When the desired oxide film is formed, the sample 9 is moved to the film forming chamber 1 via the sample moving chamber 3 to form a new metal thin film.

Next, a method of adjusting the sample in the measuring chamber 7 will be described with reference to FIG. As described in the prior art, the absorbance (reflectance) of P-polarized infrared light is very sensitive to the incident angle. Therefore, in this embodiment, a sample adjusting mechanism using laser light is added. The laser light generated by the laser oscillator 21 is incident on the sample 9 using the prism element 22. The laser light reflected on the surface of the sample 9 is transmitted through the prism element 22 and detected by the two-dimensional detector 23. The prism element 22 directly reflects a part of the laser light toward the two-dimensional detector 23.
If the reflected light and the laser light reflected and returned by the sample match, the laser light will enter the sample vertically. X swivel stage 25 and Y swivel stage
24 is adjusted so that the number of laser beams on the two-dimensional detector 23 becomes one. Next, the movable aperture 26 is put in the optical path of infrared light. The Z stage 27 is moved up and down, and the position of the Z stage 27 is determined so that the output of the detector 20 becomes maximum. At this time, the movable mirror 18 is not moved. When the adjustment is completed, remove the movable aperture 26 from the optical path. With this function, infrared light can be easily incident on the sample 9 with an angle accuracy of 1 degree or less.

In measuring the infrared light reflectance, it is necessary to perform reference measurement in order to remove infrared light absorption of the optical system. When the metal film under the oxide film is thick, a gold mirror is usually placed on the sample support 9 and the infrared light reflectance is measured and used as a reference. If the metal film under the oxide film is thin or if it is a laminated film,
The effect needs to be removed. In this embodiment, after film formation,
Before oxidation, the sample is moved to the measurement chamber 7 and the infrared light reflectance is measured and used as a reference, whereby it is possible to measure the infrared light reflectance without the influence of a thin metal film or a laminated film. It has become possible.

(Film Forming Example 1) An example of an aluminum oxide film measured by using Example 1 will be described with reference to FIG. Figure 3
Is Ta (5nm) / NiFe (5nm) / MnPt on the Si substrate in the deposition chamber 1 etc.
(25nm) / CoFe (3nm) film, then aluminum film
A sample 28 having a 0.4 nm film thickness, a sample 29 having a 0.6 nm film thickness, a sample 30 having a 0.8 nm film thickness, and a sample 31 having a 1.0 nm film thickness are respectively provided in the oxidation chamber 5
It is a measurement result of infrared light reflectance of the sample plasma-oxidized by. The vertical axis represents the natural logarithm of the obtained infrared light reflectance. In this sample, the conditions of plasma oxidation are adjusted so that all aluminum is oxidized. The absorption near 950 / cm increases as the thickness of aluminum oxide increases. From this, it can be seen that the peak around 950 / cm is the infrared absorption peak of aluminum oxide.

FIG. 4 shows the relationship between the peak intensity (infrared absorption amount) and the film thickness of the formed aluminum film. There is a good correlation between the thickness of the formed aluminum film and the peak intensity of aluminum oxide. The reason that Fig. 4 does not have a perfect linear relationship is probably because the film thickness increased due to oxidation. Theoretically, the size of the infrared absorption peak plotted in natural logarithm is proportional to the film thickness, so that the film thickness of aluminum oxide can be obtained by using this example.

(Film Forming Example 2) Next, an example of examining the infrared light reflectance of a sample obtained by changing the oxidation method will be described with reference to FIG.
Figure 5 shows Ta (5nm) / NiFe (5nm) / MnPt (25nm) / Co on Si substrate.
After depositing Fe (3 nm), aluminum is deposited to 1.0 nm without oxidation 32, natural oxidation under low oxygen concentration (natural oxidation weak 33),
This is the infrared light reflectance of a sample that has been subjected to plasma oxidation 35 by adding natural oxidation under high oxygen concentration (natural oxidation strength 34). It can be seen that the position of the peak is moved in addition to the depth of the peak as compared with FIG. As shown in FIG. 4, the peak intensity (absorption amount) indicates the aluminum oxide film thickness. Therefore, FIG.
Shows the difference between the peak position and the sample. The peak position has moved to the high wave number (high energy) side due to natural oxidation. In infrared absorption, the peak moves to the higher wavenumber side as the bond between atoms becomes stronger. As a result, it is found that the natural oxidation oxidizes only the aluminum atoms near the surface, so that the thickness of the oxide film does not become so thick, but the bonding between the aluminum atoms and the oxygen atoms becomes strong. In addition, the oxide film formed by plasma oxidation oxidizes up to the aluminum inside the sample that is naturally oxidized under high oxygen concentration, but the aluminum oxide formed by plasma oxidation is more bonded than the aluminum oxide naturally oxidized under high oxygen concentration. Is considered to be weak. Thus, information on the bond between the oxygen atom and the metal atom can be obtained from the peak position of the infrared light reflectance.

Strong natural oxidation 34 in FIG. 5 is a sample in which natural oxidation weak 33 is added with natural oxidation under a high oxygen concentration. By using the oxide film forming apparatus of the present invention, the sample of natural oxidation weak 33 which is insufficiently oxidized is additionally oxidized,
It is possible to make it a state of strong natural oxidation of 34.

(Embodiment 2) FIG. 7 shows another embodiment of the present invention. In Example 1 described above, FT-IR using a Michelson interferometer was used for measuring the infrared light reflectance. FIG. 7 shows an optical system that uses the spectroscopic element 36 to measure the reflectance while scanning the wavelength. The infrared light generated by the infrared light source 10 is shaped by the slit 11, and the wavelength is selected by the spectroscopic element 36. Front mirror
At 13, the optical path is changed so that the incident angle to the sample is about 4 °, and at the polarizing element 14, the polarization is adjusted so that only P-polarized light enters the sample. The infrared light reflected by the sample 9 is reflected by the rear-end mirror 15 and enters the detector 20 via the condenser mirror 19. Spectroscopic element 36
The wavelength dependence of the reflectance is measured by measuring the intensity of the detector 20 while changing the selected wavelength with. The film forming chamber (not shown), the oxidation chamber (not shown), and the sample transfer chamber (not shown) are shown in FIG.
It is similar to the embodiment shown in FIG. The procedures for film formation on the substrate, oxidation, and sample preparation in the analysis chamber are the same as those in the above-mentioned embodiment.
Although there is a difference in measuring the infrared light reflectance by the wavelength dispersion method, since the measured infrared light reflectance is the same as described above, the thickness of the oxide film and the analysis of the bonding state are also different from those of the above-mentioned examples. Is the same.

(Embodiment 3) FIG. 8 shows another embodiment of the present invention. In this example, a Michelson interferometer was used for the incident optical system with infrared reflectance. The infrared light generated by the infrared light source 10 is shaped by the slit 11, converted into parallel rays by the collimator mirror 12, and incident on the beam splitter 16. One of the infrared rays split by the beam splitter 16 is reflected by the fixed mirror 17 and returns to the beam splitter 16. The other infrared light is reflected by the movable mirror 18 and returns to the beam splitter 16. Fixed mirror
Infrared light reflected by 17 and movable mirror 18 is beam splitter
It interferes at 16 and enters the front mirror 13. The front mirror 13 changes the optical path so that the incident angle to the sample is about 4 °, and the polarization element 14
Adjust the polarization so that only P-polarized light is incident on the sample.
The infrared light reflected by the sample 9 is reflected by the rear-end mirror 15 and is focused by the condenser mirror 19.
Enter detector 20 via. The wavelength dependency of the reflectance is derived by measuring the intensity of the detector 20 while changing the position of the movable mirror 18 and performing a Fourier transform with a calculator (not shown).
Film formation on the substrate in the film formation chamber 1, the oxidation chamber 5, and the sample transfer chamber 3,
The procedures for oxidation, sample preparation in the analysis room, and analysis of the oxide film thickness and bonding state are the same as those in the above-described embodiment.

(Example of Magnetic Recording / Reproducing Apparatus) Finally, a magnetic recording / reproducing apparatus equipped with a magnetoresistive sensor in which an oxide film is formed and controlled by the oxide film forming apparatus of the present invention will be described. The magnetoresistive sensor is Ta (5nm) / NiFe (5nm) / MnPt (25nm) / CoFe (3nm) on the substrate by the oxide film forming apparatus of the present invention.
After forming the film, aluminum is formed to a thickness of 0.5 nm, plasma-oxidized, and the oxide film is formed and controlled so that the intensity and position of the infrared peak corresponding to the desired oxide film thickness are obtained.
m) / NiFe (5 nm) / Ta (5 nm) / Ru (10 nm) was deposited. The obtained wafer was subjected to head processing. Since each magnetic recording / reproducing device incorporating this sensor controls the thickness of the nm oxide film of the magnetoresistive sensor and the coupling state, the sensitivity of each sensor is stable and shows a good yield as a recording device. It was According to the invention, nm, which is the main element of the magnetoresistive sensor
Since the oxide film can be formed and the film thickness and the coupling state can be controlled in-process, the performance of each sensor can be suppressed within an allowable range, and a magnetic recording / reproducing device with stable performance can be produced.

[0027]

According to the present invention, in a film forming apparatus having one or more metal thin film forming chambers and one or more metal thin film oxidizing chambers, and a means for measuring infrared light reflectance After depositing a metal thin film in the metal thin film deposition chamber, oxidize it in the metal thin film oxidation chamber, measure the infrared light reflectance from the sample without exposing it to the atmosphere, and measure the oxide film on the metal thin film. The thickness and the bonding state can be evaluated, and the film thickness and the bonding state of the oxide film on the metal thin film can be evaluated without being affected by the oxidation of the cap film or the cap film.

Further, there is an effect that it becomes possible to oxidize a sample which is insufficiently oxidized again. Furthermore, by using the infrared light reflectance of a sample having the same film structure that is not oxidized as a reference, it is possible to measure the infrared light reflectance without the influence of the laminated film other than the oxide film. There is.

Next, the problem that the absorption amount of the infrared reflection absorption method largely depends on the incident angle is solved by controlling the angle between the sample and the incident infrared light with high precision by using laser light. Has the effect of suppressing the amount of absorption to a small value and allowing the amount of absorption to be quantified and the oxide film thickness to be evaluated. Finally, according to the present invention, since the formation and management of the nm oxide film, which is the main element of the magnetoresistive sensor, can be performed on-process, the performance of each sensor can be suppressed within the allowable range, and the performance is improved. There is an effect that a stable magnetic recording / reproducing apparatus can be produced.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an infrared light reflectance measuring unit of the present invention.

FIG. 3 Example of measurement of aluminum oxide film thickness

[Fig. 4] Relation between film thickness of aluminum oxide and peak intensity

FIG. 5: Example of measurement of samples with different oxidation conditions

FIG. 6 Relationship between oxidation conditions and peak position

FIG. 7 is an explanatory diagram of an infrared light reflectance measuring unit according to another embodiment.

FIG. 8 is another embodiment of the present invention.

[Explanation of symbols]

1: film forming chamber, 2: film forming sample support, 3: sample moving chamber,
4: Robot for sample movement, 5: Oxidation chamber, 6: Oxidation chamber sample support, 7: Measurement chamber, 8: Sample support, 9: Sample, 10:
Infrared light source, 11: slit, 12: collimator mirror, 13: front mirror, 14: polarizing element, 15: rear mirror, 16: beam splitter, 17: fixed mirror, 18: movable mirror, 19: condensing Mirror, 20: Detector, 21: Laser oscillator, 22: Prism, 23: Two-dimensional detector, 24: Y swivel stage, 25: X swivel stage, 26: Movable aperture, 27: Z stage, 28: Film thickness
Sample with a film thickness of 0.4 nm, 29: Sample with a film thickness of 0.6 nm, 30:
Sample with a film thickness of 0.8 nm, 31: Sample with a film thickness of 1.0 nm,
32: No oxidation, 33: Weak natural oxidation, 34: Strong natural oxidation, 35:
Plasma oxidation, 36: Spectroscopic element, 39: Gate valve, 40:
Gate valve, 41: Gate valve, 42: Pre-analytical chamber, 43:
Post analysis room

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsumi Hirano             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Takao Imagawa             2880 Kozu, Odawara City, Kanagawa Stock Association             Storage Systems Division, Hitachi, Ltd. F-term (reference) 4K029 BA03 BA06 BA09 BA12 BA23                       BA24 BA25 BA26 BD11 EA00                       EA01 GA01 KA01 KA09                 4K030 BA02 BA05 BA07 BA14 DA09                       GA12 JA01 KA39 LA20                 5D034 BA03 DA04

Claims (5)

[Claims] 1. A film forming apparatus having one or more metal thin film deposition chambers and one or more metal thin film oxidation chambers, wherein an infrared light source,
Sample support base, spectroscope, infrared light detector, means for processing infrared light spectrum, mechanism for vacuum transfer of sample from the metal thin film oxidation chamber to the sample support base, film formation in the metal thin film deposition chamber A sample obtained by oxidizing the metal thin film formed in the metal thin film oxidation chamber on the sample support table with infrared light incident on the sample surface in an angle range of 0.5 ° to 20 °, and infrared light from the sample. An apparatus for forming a metal oxide film, comprising a means for measuring the reflectance of light, and managing the film thickness of the oxide film on the metal thin film and / or the bonding state of the oxide film from the reflectance. 2. The measured infrared light reflectance is 500 / cm to 12
The metal oxide film forming apparatus according to claim 1, wherein the wave number region is 00 / cm. 3. The metal oxide film forming apparatus according to claim 1, wherein the metal thin film is selected from aluminum, iron, nickel, cobalt, and alloys thereof. 4. The oxide film forming apparatus comprises a laser oscillator, an optical system for making laser light incident on a sample, a detector for detecting laser light reflected by the sample placed on the sample support, and a sample support. The sample and incident infrared rays have a goniometer for adjusting the angle and position of the sample stage, a means for processing the signal from the detector and a means for driving the goniometer, and using the laser beam and the laser beam reflected on the sample surface. The metal oxide film forming apparatus according to claim 1, wherein the angle formed by the light is adjusted. 5. A magnetic recording medium, a magnetoresistive sensor for reading a magnetic signal written in the medium, a write head for writing a magnetic signal, and the magnetic recording by mounting the magnetoresistive sensor and the write head at a tip portion. 5. A magnetic recording / reproducing apparatus comprising an arm for driving in a radial direction of a medium, a control unit for controlling the magnetic recording medium and an arm driving means, and a signal processing means for processing a read / write signal of a magnetic signal. A magnetic recording / reproducing apparatus having a magnetoresistive sensor in which the film thickness and bonding state of an oxide film are controlled and controlled by the metal oxide film forming apparatus described in 1.