JP2001284698A - Light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a high-frequency radiating noise radiated from a light emitting element without taking a space. SOLUTION: A mesh-like magnetic loss film (15) is partly formed at least on a surface of a light emitting window (13) in the light emitting element (10) having the window (13). In this case, as the film (15), a granular magnetic thin film can be used. The film may, for example, be a sputtered film formed by a sputtering method using a mask or may be a knitted film formed by knitting wires.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device having a light emitting window.

[0002]

2. Description of the Related Art In recent years, highly integrated semiconductor elements that operate at high speed have become remarkably popular. For example, random access memory (RAM), read only memory (ROM), microprocessor (MPU), central processing unit (CP)
U) or an image processor arithmetic logic unit (IPAL)
U) and the like. In these active elements, the operation speed and signal processing speed are increasing at a rapid pace, and electric signals propagating through high-speed electronic circuits are accompanied by abrupt changes in voltage and current. It is the main cause of noise.

On the other hand, electronic components and electronic devices are progressing at a rapid pace, as it is not known that the flow of weight reduction, thinning, and miniaturization will stop. Along with that, the degree of integration of semiconductor devices,
The mounting density of electronic components on printed wiring boards has been remarkably increased. Therefore, electronic elements and signal lines that are densely integrated or mounted are extremely close to each other, and high-frequency radiation noise is likely to be induced along with the above-described increase in signal processing speed.

[0004] Such high-frequency radiation noise is, for example,
The light may be emitted from a light emitting element such as a laser diode used in an optical pickup for an optical disk drive. This is because a laser diode may operate at high speed, and in such a case, not only light (infrared rays) but also high-frequency radiation noise is emitted from the laser diode.

[0005]

However, no countermeasures have been taken in the past for high frequency radiation noise radiated from the light emitting element.

Accordingly, it is an object of the present invention to provide a light emitting device capable of suppressing high frequency radiation noise.

Another object of the present invention is to provide a light-emitting element which can achieve the above-mentioned suppression effect without taking up space.

[0008]

The present inventors have previously invented a composite magnetic material having a large magnetic loss at a high frequency and arranged it near an unnecessary radiation source, so that the above-described semiconductor element or electronic device can be obtained. A method has been found for effectively suppressing unnecessary radiation generated from a circuit or the like. Recent studies have shown that the mechanism of the unwanted radiation attenuation using such magnetic loss is due to the addition of an equivalent resistance component to the electronic circuit that is the unwanted radiation source. . Here, the magnitude of the equivalent resistance component depends on the magnitude of the magnetic loss term μ ″ of the magnetic material. More specifically, the magnitude of the resistance component equivalently inserted into the electronic circuit is: When the area of the magnetic body is constant, μ ″ is substantially proportional to the thickness of the magnetic body.
Therefore, in order to obtain a desired unnecessary radiation attenuation with a smaller or thinner magnetic body, a larger μ ″ is required. For example, a magnetic loss body is used in a minute area such as the inside of a mold of a semiconductor device. In order to take measures against unnecessary radiation, the magnetic loss term μ ″ needs to be an extremely large value, and a magnetic material having a much larger μ ″ than conventional magnetic loss materials has been required. Has been made in view of the current situation.

In the course of research on a soft magnetic material by a sputtering method or a vapor deposition method, the present inventors have developed a method of forming a granular magnetic material in which fine magnetic metal particles are homogeneously dispersed in a non-magnetic material such as ceramics. Focusing on the excellent permeability characteristics, we studied the microstructure of magnetic metal particles and the surrounding nonmagnetic material, and as a result, when the concentration of magnetic metal particles in the granular magnetic material is in a specific range, in the high frequency region It has been found that excellent magnetic loss characteristics can be obtained. M-
Many studies have been made on a granular magnetic material having a composition of XY (M is a magnetic metal element, Y is O or any of N and F, and X is an element other than M and Y), and many studies have been made so far. Is known to have a large saturation magnetization. In the M-XY granular magnetic material, the magnitude of the saturation magnetization depends on the volume ratio occupied by the M component. Therefore, in order to obtain a large saturation magnetization, it is necessary to increase the ratio of the M component. Therefore, in a general use such as a magnetic core of a high-frequency inductor element or a transformer, the ratio of the M component in the M-XY granular magnetic material is substantially equal to the saturation magnetization of the bulk metal magnetic material including only the M component. It is limited to a range where a saturation magnetization of 80% or more can be obtained.

The present inventors have proposed a granular magnetic material having a composition of M-XY (M is a magnetic metal element, Y is O or any of N and F, and X is an element other than M and Y). As a result of examining the ratio of the components in a wide range, it was found that in any composition system, when the magnetic metal M was in a specific concentration range, a large magnetic loss was exhibited in a high frequency region, and the present invention was reached.

The highest region where the ratio of the M component shows a saturation magnetization of 80% or more with respect to the saturation magnetization of the bulk metal magnetic material consisting of only the M component is a high saturation magnetization which has been actively studied conventionally. And is a region of a low loss MXY granular magnetic material. Since the material in this region has a large real part magnetic permeability (μ ′) and a large saturation magnetization, it is used for a high-frequency micro magnetic device such as the above-described high-frequency inductor. , The electrical resistivity is small. Therefore, when the film thickness is increased, the magnetic permeability at a high frequency deteriorates due to the occurrence of eddy current loss in a high frequency region, so that it is not suitable for a relatively thick magnetic film used for noise suppression. The region showing the saturation magnetization where the ratio of the M component is 80% or less and 60% or more of the saturation magnetization of the bulk metal magnetic material composed of only the M component is because the electric resistivity is relatively large, approximately 100 μΩ · cm or more. Even if the thickness of the material is about several μm, the loss due to the eddy current is small, and the magnetic loss is almost a loss due to natural resonance. Therefore, since the frequency dispersion width of the magnetic loss term μ ″ becomes narrow, it is suitable for noise suppression (high-frequency current suppression) in a narrow band frequency range.
60 of saturation magnetization of bulk metal magnetic material consisting only of M component
%, The region exhibiting a saturation magnetization of 35% or more has an electric resistivity of approximately 500 μΩ · cm or more, so that the loss due to the eddy current is extremely small and the magnetic interaction between the M components becomes small. Then, the thermal disturbance of the spin becomes large, and the frequency at which the natural resonance occurs fluctuates, and as a result, the magnetic loss term μ ″ shows a large value in a wide range. Suitable for suppression.

On the other hand, a region in which the ratio of the M component is smaller than the region of the present invention becomes superparamagnetic because almost no magnetic interaction occurs between the M components.

A guide for designing a material when a high-frequency current is suppressed by disposing a magnetic loss material in the immediate vicinity of an electronic circuit is given by a product μ ″ · δ of a magnetic loss term μ ″ and a thickness δ of the magnetic loss material. Therefore, in order to obtain effective suppression of a high-frequency current having a frequency of several hundred MHz, it is necessary to roughly set μ ″ · δ ≧ 1000 (μ
m) is required. Therefore, a magnetic loss material of μ ″ = 1000 requires a thickness of 1 μm or more, and a material having low electric resistance that easily causes eddy current loss is not preferable. In the composition system of the present invention, the ratio of the M component shows saturation magnetization in which the saturation magnetization is 80% or less of the saturation magnetization of the bulk metal magnetic material composed of only the M component, and a region where superparamagnetism does not appear, that is, only the M component. A region showing 35% or more of the saturation magnetization of the bulk metal magnetic material is suitable.

The present invention is an application of a magnetic loss film such as the above-mentioned granular magnetic thin film. here,
“Granular magnetic thin film” refers to a particle having a very small average particle diameter of several nanometers to several tens of nanometers, and has a fine structure in which each particle is separated by a grain boundary made of a ceramic component. It refers to a magnetic thin film that exhibits a very large magnetic loss at a high frequency of MHz to several GHz, and is also called a “microcrystalline thin film” in this technical field.

That is, according to the present invention, in a light emitting device having a light emitting window, a light emitting device having a magnetic loss film formed on at least a part of the surface of the light emitting window can be obtained. The magnetic loss film preferably has a mesh shape. As the magnetic loss film, a granular magnetic thin film can be used. The granular magnetic thin film may be, for example, a sputtered film formed by a sputtering method using a mask or a knitted film formed by knitting with a line.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, a light emitting device 10 according to one embodiment of the present invention will be described. Illustrated light emitting element 1
Reference numeral 0 denotes a laser diode used for an optical pickup for an optical disk drive. The illustrated light emitting element (laser diode) 10 includes a base 11, a laser diode chip 12 mounted on the base 11, and a resin-made resin attached to the base 11 so as to cover the laser diode chip 12. It has a light emitting window 13 and three legs 14 extending from the base 11 in a direction opposite to the light emitting window 13.

In the light emitting element (laser diode) 10 having such a structure, in the present invention, a mesh-shaped magnetic loss film 15 is formed below the surface of the light emitting window 13 (on the base 11 side). Here, the reason why the magnetic loss film 15 is provided only under the surface of the light emitting window 13 is that the laser diode chip 1
This is to prevent the laser light emitted from 2 from interfering with the transmission through the light emitting window 13.

Here, as the magnetic loss film 15, the present inventors have already filed an application (20 filed on Jan. 24, 2000).
A granular magnetic thin film (hereinafter, referred to as “prior application”) of Japanese Patent Application No. 52507 (2000) can be used.
Such a granular magnetic thin film can be manufactured by a sputtering method, a reactive sputtering method, or an evaporation method as described in the specification of the prior application. In other words, the granular magnetic thin film may be a sputtered film formed by a sputtering method or a reactive sputtering method,
Alternatively, a vapor deposition film formed by a vapor deposition method may be used. When manufacturing a granular magnetic thin film, actually, the sputtered film or the deposited film is heat-treated in a vacuum magnetic field at a predetermined temperature for a predetermined time.

The detailed manufacturing method of the granular magnetic thin film is described in detail in the above-mentioned prior application, so please refer to it. Here, in the present invention, since the magnetic loss film (granular magnetic thin film) 15 needs to be formed in a mesh shape, such a film is formed by a sputtered film formed by a sputtering method using a mask or a knitted line. What is necessary is just a knitting film formed by performing the knitting.

The granular magnetic thin film thus formed exhibits a very large magnetic loss at a high frequency of several tens of MHz to several GHz even if the thickness is small (for example, 2.0 μm or less). The inventors have already confirmed by experiments.

The present inventors have found that the granular magnetic thin film according to the present invention, which exhibits a magnetic loss term μ ″ dispersion in the quasi-microwave band, has the same high-frequency current suppression as a composite magnetic sheet having a thickness of about 500 times. The effect has already been confirmed by experiments, and therefore, the granular magnetic thin film according to the present invention has
It can be said that it is promising as a material used for EMI countermeasures such as a semiconductor integrated device that operates with a high-speed clock near 1 GHz.

Next, a sputtering manufacturing apparatus will be described as an example of an apparatus for manufacturing a granular magnetic thin film as the magnetic loss film 15 with reference to FIG. This sputtering manufacturing apparatus includes a vacuum container (chamber) 18,
A gas supply device 22 and a vacuum pump 23 are connected to the chamber 18. In the champ 18, a substrate 23 and a target 25 are arranged to face each other with a shutter 21 interposed therebetween. The target 25 is composed of the components X, Y, or the components M in which the chips 24 composed of the components X are arranged at predetermined intervals. Chip 24 and target 25
Is connected to one end of an RF power source 26,
The other end of the power supply 26 is grounded.

Next, an example of manufacturing a granular magnetic thin film (sample 1) manufactured by using the sputtering manufacturing apparatus having such a configuration will be described.

First, the diameter φ of the target 25 is 10
Size of chip 24 on 0 mm Fe disk = 5 m long
A total of 120 Al ₂ O ₃ chips of mx 5 mm wide x 2 mm thick were provided. Then, the vacuum container 1 is
While keeping the inside of the chamber 8 at a degree of vacuum of about 1.33 × 10 ⁻⁴ Pa, the gas supply device 22 puts A into the vacuum vessel 18.
By supplying r gas, the inside of the vacuum vessel 18 is brought into an Ar gas atmosphere. In this state, high-frequency power is supplied from the RF power supply 26. Under such conditions,
A magnetic thin film was formed on a glass substrate serving as the substrate 23 by a sputtering method. Then, the obtained magnetic thin film was further
By performing a heat treatment in a vacuum magnetic field at a temperature of 2 ° C. for 2 hours, the above-mentioned sample 1 of the granular magnetic thin film was obtained.

When the sample 1 thus obtained was subjected to fluorescent X-ray analysis, the film composition was Fe ₇₂ Al ₁₁ O ₁₇ , the film thickness was 2.0 μm, and the DC resistivity was 530 μΩ · c.
m. Further, the anisotropic magnetic field H _k of sample 1 18 (O
a e), the saturation magnetization M _s was 1.68T (tesla). Further, even if the magnetic loss term is “μ” on the complex magnetic permeability characteristic of the sample 1, a frequency band in which 50% or more of the maximum value “μ” _{max is} equivalent to a half width μ corresponding to a half width standardized by its center frequency. ₅₀ was 148%. The ratio {M _s (M _s (M _s (M)) of the saturation magnetization M _s (M-X-Y) of the sample 1 to the saturation magnetization M _s (M) of the metal magnetic material composed only of the composition M was used. MX-
Y) / M _s (M)} × 100% was 72.2%.

Further, in order to verify the magnetic loss characteristics of the sample 1, the magnetic permeability μ characteristics (μ-f characteristics) with respect to the frequency f were examined as follows. That is, the measurement of the μ-f characteristic is as follows.
This was performed by inserting the sample 1 into the detection coil processed into a strip shape and measuring the impedance while applying a bias magnetic field. Based on this result, the frequency characteristic (μ ″ -f characteristic) of the magnetic loss term μ ″ was obtained.

FIG. 3 is a graph showing the μ ″ -f characteristic of the sample 1. In FIG. 3, the horizontal axis represents the frequency f (MHz),
The vertical axis represents the magnetic loss term μ ″. From FIG. 3, the magnetic loss term μ ″ of the sample 1 has a slightly steep variance, a very large peak value, and a resonance frequency of 70 μm.
It can be seen that it is as high as around 0 MHz.

Further, a verification experiment was conducted on the high-frequency electromagnetic interference suppression effect of the sample 1 using a high-frequency electromagnetic interference suppression effect measuring device 30 as shown in FIG. However, the high-frequency electromagnetic interference suppression effect measuring device 30 connects the microstrip line 31 and a network analyzer (HP8753D) (not shown) to both sides in the longitudinal direction of the microstrip line 31 having a line length of 75 mm and a characteristic impedance Zc = 50Ω. And the magnetic sample 33 is arranged just above the sample arrangement portion 31a of the microstrip line 31 so that the transmission characteristics S between the two ports can be improved.
₂₁ can be measured.

This high frequency electromagnetic interference suppression effect measuring device 30
In the case where the high-frequency current is suppressed by applying an equivalent resistance component to the transmission line in which the magnetic loss material is disposed immediately adjacent to the transmission line as in the configuration of This is considered to be substantially proportional to the product μ ″ · δ of the size of the term μ ″ and the thickness δ of the magnetic body.

FIG. 5 shows a high-frequency current suppression effect measuring device 30.
The transmission characteristics S ₂₁ (d) for the frequency f (MHz) showing the result of measuring the high-frequency current suppression effect of the sample magnetic material by
B).

FIG. 5 shows that the transmission characteristic S ₂₁ of the sample 1 is 10
It can be seen that the frequency decreases from 0 MHz or higher, reaches a minimum value of -10 dB near 2 GHz, and then increases. This result, transmission characteristics S ₂₁ magnetic loss term μ of the magnetic material "as well as dependent on the dispersion of the product μ the size of the inhibitory effect was described above"
・ It turns out that it depends on δ.

By the way, as shown in FIG. 6, it is assumed that such a magnetic material as the sample 1 has a dimension 1 and is configured as a distributed constant line having a magnetic permeability μ and a dielectric constant ε. be able to. In this case, as an equivalent circuit constant per unit length (Δl), a unit inductance ΔL, a unit resistance ΔR in a form of series connection, a unit capacitance ΔC interposed between these and a ground line, a unit ground It has a conductance ΔG. When converted them to sample dimensions based on the transmission characteristic S _21, sample 1, the inductance L, resistance R, and the capacitance C as the equivalent circuit constant,
It can be regarded as an equivalent circuit having the ground conductance G.

As described in the examination of the effect of suppressing high-frequency electromagnetic interference, when the transmission characteristics S21 are arranged on the microstrip line 31 made of a magnetic material, the change in the transmission characteristic S21 is mainly in series with the inductance L in the equivalent circuit. Added resistance R
Therefore, the value of the resistor R can be obtained and its frequency dependence can be examined.

FIG. 7 shows the frequency f (MHz) calculated based on the value of the resistance R added in series to the inductance L of the equivalent circuit shown in FIG. 6 in the transmission characteristic S ₂₁ shown in FIG. 4) shows the characteristics of the resistance value R (Ω) with respect to the above-mentioned values.

From FIG. 7, it can be seen that the resistance value R monotonically increases in the quasi-microwave band region, and becomes several tens of ohms at 3 GHz, and its frequency dependence shows the frequency dispersion of the magnetic loss term μ ″ having a maximum near 1 GHz. It can be understood that this is a result of reflecting that the ratio of the sample size to the wavelength monotonically increases in addition to the above-mentioned product μ ″ · δ.

From the above results, the sample exhibiting the magnetic loss term μ ″ dispersion in the quasi-microwave band exhibits the same high-frequency current suppressing effect as the composite magnetic sheet having a thickness of about 500 times,
It can be said that it is effective to apply to measures for suppressing high-frequency electromagnetic interference at GHz.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the spirit of the present invention.
Of course, deformation is possible. For example, in the embodiment of the present invention, only a manufacturing example by a sputtering method using a mask has been described as a method for manufacturing a granular magnetic thin film.
Other manufacturing methods such as a vacuum evaporation method, an ion beam evaporation method, and a gas deposition method may be used, and the manufacturing method is not limited as long as the magnetic loss film according to the present invention can be uniformly formed.

In the embodiment of the present invention, a heat treatment in a vacuum magnetic field is performed after the film is formed. However, any composition or film forming method that can obtain the performance of the present invention with an as-deposited film can be used. For example, the present invention is not limited to the post-film formation processing described in the embodiment.

Further, in the above-described embodiment, a laser diode is taken as an example of the light emitting element 10 and the magnetic loss film 15 is formed in the light emitting window 13 of the laser diode. Of course, the infrared I / O unit may be applied to the light emitting window, or the active matrix type liquid crystal display using the thin film transistor (TFT) as the light emitting element may be applied to the display window. In the above-described embodiment, only the example in which the mesh-shaped magnetic loss film 15 is formed on a part of the surface of the light emitting window 13 of the light emitting element 10 is described.
A mesh-shaped magnetic loss film 15 may be formed on the entire surface of the substrate. Further, instead of the mesh shape, a stripe shape, a lattice shape, or a checkered pattern may be formed. Anyway, it suffices if the magnetic loss film 15 can be formed with a gap. Furthermore, in the above-described embodiment, the case where the magnetic loss film 15 has a mesh shape has been described as an example. However, when the magnetic loss film 15 is provided only below the surface of the light emitting window 13, a laser diode is used. The laser light emitted from the chip 12 is
Of course, the entire film may be covered so as not to hinder transmission of the light.

In the above embodiment, the magnetic loss film 1
Although the case where 5 is a granular magnetic thin film has been described as an example, the invention is not limited thereto, and any film may be used as long as it shows a very large magnetic loss at a high frequency of several tens MHz to several GHz.

[0042]

As described above, according to the present invention, since the mesh-shaped magnetic loss film is formed on at least a part of the surface of the light emitting window of the light emitting element, the space from the light emitting element can be reduced without taking up space. High-frequency radiation noise emitted can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing an example of a light emitting device (laser diode) according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a sample manufacturing apparatus using a sputtering method.

FIG. 3 is a diagram illustrating an example of frequency dependence of a magnetic loss term μ ″ according to a sample 1 as a magnetic loss film.

FIG. 4 is a perspective view showing a measurement system for observing the suppression effect of a high-frequency current suppressor made of a sample 1 as a magnetic loss film.

FIG. 5 shows the transmission characteristics of sample 1 as a magnetic loss film (S ₂₁ )
FIG. 4 is a diagram showing frequency characteristics of the multiplexed signal;

FIG. 6 is a diagram showing an equivalent circuit of a magnetic body that is a magnetic loss film.

FIG. 7: Transmission characteristics of sample 1 as a magnetic loss film (S ₂₁ )
FIG. 9 is a diagram illustrating frequency characteristics of a resistance value R calculated by the calculation.

[Explanation of symbols]

 Reference Signs List 10 light emitting element (laser diode) 11 base 12 laser diode chip 13 light emitting window 14 foot 15 magnetic loss film (granular magnetic thin film)

Continued on the front page F term (reference) 5E049 AA01 AC00 BA27 CB06 CB10 EB05 GC04 5F041 AA21 DA42 DA46 DA55 DA58 5F073 BA04 EA29 FA30

Claims (5)

[Claims] 1. A light-emitting element having a light-emitting window, wherein a magnetic loss film is formed on at least a part of a surface of the light-emitting window. 2. The light emitting device according to claim 1, wherein said magnetic loss film has a mesh shape. 3. The light emitting device according to claim 1, wherein the magnetic loss film is a granular magnetic thin film. 4. The light emitting device according to claim 3, wherein the granular magnetic thin film is a sputtered film formed by a sputtering method using a mask. 5. The light emitting device according to claim 3, wherein the granular magnetic thin film is a knitted film formed by knitting with a wire.