KR20050030545A - Inorganic nitride member and marking method for the same - Google Patents

Abstract

A marking method of an inorganic nitride member and the inorganic nitride member are provided to enhance the definitude of a mark by forming a high reflectivity region of a character-like structure on the inorganic nitride member. A member(5) is made of nitride and an inorganic compound, wherein the inorganic compound is made of nitride and a first element. By forming a first region with a relatively high atomicity of nitride compared to that of the first element and a second region with a relatively low atomicity of nitride compared to that of the first element on a surface of the member, a relatively high reflectivity region(20a,20b,20c) and a relatively low reflectivity region are arranged on the member.

Description

Inorganic nitride member and marking method for the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a marking method and an inorganic nitride member of an inorganic nitride member, and in particular, a marking method and an inorganic nitride member on a surface of a member. It relates to an inorganic nitride member formed.

Conventionally, marking is performed on various board | substrates, such as a silicon substrate, in order to manage a production process and to improve productivity. In particular, from the viewpoint of performing sheet management at present, a method of simply marking all substrates is desired.

There is a marking method in which a symbol or the like is written in a substrate by cutting a substrate surface to form a plurality of hole-shaped dots or forming grooves. In order to form dots and grooves on the substrate surface, a method of mechanically cutting the substrate surface with a drill or the like has been used in the past. As in recent years, a method capable of forming finer holes or grooves, in place of a mechanical method, a method of irradiating a laser beam such as CO ₂ laser or a harmonic YAG laser is used.

Since the marking method as described above is a method of cutting a substrate, cutting chips and the like that appear during processing contaminate the lines of the subsequent process. Moreover, since it is a method of damaging a board | substrate, the mechanical strength of the board | substrate after processing falls. For example, cracks are liable to occur starting from the groove of the marking.

As described below, Patent Document 1 discloses a marking method in which a hole or a groove is not formed in a substrate with respect to a silicon substrate. The surface of the silicon substrate is irradiated with a laser to melt the silicon. When the molten region solidifies, it becomes a minute protrusion on the substrate surface. Instead of holes and grooves, such projections can be used to produce marks.

By the way, there is a gallium nitride substrate as a board | substrate which is marketed recently and attracts attention. As a new substrate, a general marking method for gallium nitride substrates has not yet been established.

Patent Literature 2 proposes a marking method in which a gallium nitride substrate is irradiated with a CO ₂ laser (wavelength of 10.6 μm) to form a plurality of dots having a depth of several μm on the surface of the substrate. The CO ₂ laser is irradiated with a peak intensity of 170 W and a pulse width of 100 Hz.

Patent Literature 2 also proposes a marking method in which a third harmonic (wavelength 355 nm) of a YAG laser is irradiated to a gallium nitride substrate to form a dot at a depth of 70 μm inside the substrate.

[Patent Document 1] Japanese Patent Application Laid-Open No. 10-0004040

[Patent Document 2] Japanese Patent Publication No. 2003-209032

Consider marking the gallium nitride substrate. Of the method disclosed in Patent Document 2, in the method using a CO ₂ laser, a hole is formed on the substrate surface. As described above, the marking method for forming a recess such as a hole on the substrate surface includes problems such as cutting debris at the time of processing contaminating a later process, a problem that the mechanical strength of the substrate is reduced due to the formation of the recess, and the like. Follow. Further, if the irradiation of CO ₂ laser on the gallium nitride substrate, and also concerns a crack due to thermal reaction caused in the substrate. Since the mark formed by this method is recognized by the step which exists in the surface of a board | substrate, it cannot be said that it has the outstanding visibility.

Among the methods disclosed in Patent Document 2, in the method using a YAG laser, a mark is formed inside the substrate. Since gallium nitride substrates are dark brown and translucent, the visibility of the marks formed inside the substrate is not excellent.

Also in the marking on a gallium nitride substrate, the method which does not form a recessed part in the surface of a board | substrate is preferable. Moreover, it is preferable that the mark which is excellent in visibility can be formed.

In the marking method disclosed in Patent Literature 1, no recess is formed on the substrate surface. However, this is a marking method effective for a silicon substrate, and in the same manner, it is impossible to form projections on the gallium nitride substrate surface.

One object of the present invention is to provide a novel marking method for an inorganic nitride member such as a gallium nitride substrate.

Another object of the present invention is to provide a marking method capable of producing a mark having high visibility on an inorganic nitride member such as a gallium nitride substrate.

Another object of the present invention is to provide a marking method in which an inorganic nitride member such as a gallium nitride substrate or the like can be prevented from being damaged and a mark can be produced.

Another object of the present invention is to provide an inorganic nitride member such as a gallium nitride substrate having a mark having high visibility on its surface.

According to one aspect of the present invention, on the surface of a member made of an inorganic compound of a first element other than nitrogen and nitrogen, a region where the ratio of the number of atoms of nitrogen to the number of atoms of the first element is relatively high. By forming a low and low region, there is provided a method for marking an inorganic nitride member, comprising the step of disposing a region having a relatively high reflectance and a region on the surface of the member.

According to another aspect of the invention, a member comprising (a) a step of emitting a laser beam from a laser light source and (b) a laser beam emitted from the laser light source comprising an inorganic compound of a first element other than nitrogen and nitrogen Irradiate the first region partitioned on the surface of the member to release nitrogen atoms out of the member, and determine the ratio of the number of atoms of nitrogen to the number of atoms of this first element in the first region. A marking method for an inorganic nitride member is provided, comprising the step of making the ratio of the number of atoms of nitrogen to the number of atoms of the first element in a region not irradiated with a laser beam.

According to another aspect of the present invention, there is provided an inorganic nitride member in which a mark is formed by adjoining at least two zones having different nitrogen atomic densities as a member made of an inorganic compound of a first element other than nitrogen and nitrogen.

<Example>

First, a novel conception method for marking gallium nitride substrates found by the present inventors will be described.

The gallium nitride substrate is dark brown and translucent. Since the gallium contained in the gallium nitride substrate is a metal element, the region of the substrate is first released of nitrogen to the gallium-rich region (compared to the ratio of the number of nitrogen atoms to the number of gallium atoms in the original substrate). When a region having a small ratio of the number of nitrogen atoms to the number of gallium atoms) is formed, the region has a higher reflectance than the original substrate surface. By making a gallium-rich region into a desired shape, a mark with high visibility can be produced on the substrate surface.

The present inventors considered using a laser in order to produce such a mark. By irradiating a gallium nitride substrate with a laser beam, it was thought that the gallium-rich region could be formed by heating the substrate surface to pyrolyze gallium nitride, releasing nitrogen preferentially out of the substrate as a gas.

In the case of using a pulsed laser beam, it is possible to predict the pulse width and peak intensity suitable for processing by the following considerations.

When a gallium nitride substrate was irradiated with a pulse of a CO ₂ laser, a large number of cracks were cracked in the substrate. This is assumed to be due to the pulse width of the CO ₂ laser being long in microsecond order, as described below.

In order to process the object with a laser, it is necessary to perform laser irradiation with a peak intensity above a certain threshold value. For example, considering the pulse laser of the peak intensity just above the threshold value, the longer the pulse width, the larger the pulse energy. Since the CO ₂ laser has a long pulse width in microsecond order, it is considered that the pulse energy tends to be too large even with a pulse having a moderate intensity.

Light energy irradiated to the substrate is converted into heat and diffused in the substrate. In the substrate, a temperature gradient occurs from the beam irradiation area to the non-irradiation area, and thermal stress is generated. When the gallium nitride substrate was irradiated with a CO ₂ laser, excessive thermal energy was irradiated to the substrate, so that a high thermal stress was generated near the beam irradiation area, and it is thought that a crack occurred. In manufacturing the mark as described above, it is intended to prevent the occurrence of such a crack.

By the way, it is known that the gallium nitride laminated | stacked on sapphire can irradiate the pulse which has the pulse width of a femtosecond order, and cuts gallium nitride. Cutting gallium nitride indicates that the gallium nitride substrate is cut (or a hole is made in the gallium nitride substrate) with such a short pulse width pulse. In other words, the irradiation of such a pulse indicates that gallium and nitrogen constituting the gallium nitride substrate are almost completely removed from the substrate. This is assumed to be due to the relatively high peak intensity of such a short pulse.

In order to produce such marks, gallium nitride on the surface of the substrate is thermally decomposed to release nitrogen out of the substrate. Therefore, it is not desirable that gallium and nitrogen be removed almost equally out of the substrate (the holes in the gallium nitride substrate). And as such a short pulse width, the pulse which is the peak intensity of the grade which does not produce the cutting of gallium nitride as mentioned above is considered. Such pulses will have too little pulse energy to be able to thermally decompose gallium nitride sufficiently.

To summarize the above considerations. In order to produce such marks, it is necessary to make the pulse width short enough so that heat storage to the extent that the cracks are induced does not occur. On the other hand, too short is not preferable. The pulse width may be a length between microseconds and femtoseconds. The peak intensity should be such that the size is such that no hole is formed in the gallium nitride substrate.

In addition, the conditions of the wavelength to irradiate are considered as follows. The light emission wavelength of gallium nitride is 400 nm, and even if light of this wavelength is irradiated, absorption to a board | substrate is small. Since light absorption of gallium nitride exists in a wavelength range shorter than this wavelength, it is preferable to use a wavelength of 400 nm or less for processing.

Based on such considerations, the inventors conducted laser irradiation experiments on gallium nitride substrates in order to obtain more detailed knowledge for producing such marks. In this experiment, the gallium nitride substrate was irradiated with the fifth harmonic (wavelength 209 nm), the fourth harmonic wave (262 nm), the third harmonic wave (wavelength 349 nm), and the second harmonic wave length (523 nm) of the YLF laser. Was performed. The relationship between the pulse energy density (and irradiation intensity) on the substrate surface and the good / poor processing of the pulses when one pulse of each wavelength was irradiated was investigated. The cross section of the laser beam was circularly shaped into pinholes, and the pinholes were imaged on the substrate surface. The diameter of the beam cross section on the substrate surface was 70-80 micrometers.

When the 5th harmonic (wavelength 209 nm) was irradiated on the conditions which the pulse energy density of a substrate surface becomes 1.1 J / cm <2>, the board | substrate surface fell and the recessed part was formed. The region with high reflectance was not formed clearly. No preferential release of nitrogen occurs, and gallium and nitrogen are thought to have been removed out of the substrate together. This is presumably because absorption of gallium nitride for this wavelength is large.

Next, with reference to FIGS. 1-4, the result which irradiated 4th-2nd harmonic is demonstrated. 1 to 4 show a state in which a gallium nitride substrate irradiated with a laser is observed with a reflective optical microscope.

FIG. 1 shows the result when the fourth harmonic wave (wavelength 262 nm) is irradiated. FIG. 1 (A) shows the case where irradiation was carried out under the condition that the pulse energy density of the substrate surface is 0.24 J / cm 2. On the surface of the board | substrate 10, the beam irradiation trace 11a which looks bright (white in drawing) by the reflection type optical microscope is formed.

The brighter beam irradiation trace 11a is considered to indicate that the release of nitrogen occurs in the region irradiated with the laser beam, thereby forming a gallium-rich region. The gallium-rich region becomes bright due to the reflective optical microscope because of its high reflectance.

FIG. 1B shows a case where irradiation is performed at a pulse energy density of 11.71 J / cm 2 on the substrate surface. As in FIG. 1A, a bright beam irradiation trace 11b is formed on the surface of the substrate 10.

Both beam irradiation traces 11a and 11b shown in FIGS. 1A and 1B have a circular shape corresponding to the beam spot (pinhole formed on the substrate surface). A region having a high reflectance is formed in the shape of the beam spot.

2 and 3 show the results when the third harmonic (wavelength 349 nm) is irradiated. 2 (A) and (B) show a case where irradiation was carried out under the conditions that the pulse energy densities on the surface of the substrate were 2.0 J / cm 2 and 11.7 J / cm 2, respectively. Similarly to FIG. 1, brightly visible beam irradiation traces 12a and 12b are formed on the surface of the substrate 10. The beam irradiation traces 12a and 12b have a circular shape corresponding to the beam spot. A region having a high reflectance is formed in the shape of the beam spot.

3 (A) and 3 (B) show a case where irradiation was performed under conditions such that the pulse energy density of the substrate surface was 0.25 J / cm 2 and 0.56 J / cm 2, respectively. In FIGS. 3A and 3B, the beam irradiation traces 13a and 13b formed on the surface of the substrate 10 do not have a circular shape corresponding to the beam spot.

Although the beam irradiation traces 13a and 13b have an appearance almost reflecting the circular shape of the beam spot, a plurality of regions having high reflectance (regions that appear white in the drawing) are distributed discretely. This is presumably because the emission of nitrogen has only occurred in the portion where the light intensity of the beam cross section is high because the energy density of the irradiated pulse is low.

In FIG. 4, the result when the 2nd harmonic (wavelength 523 nm) is irradiated on the conditions which the pulse energy density of a substrate surface becomes 3.4 J / cm <2> is shown. The beam irradiation trace 14 on the surface of the substrate 10 is formed only in a very small portion of the beam irradiation area, and its outer circumference has irregular irregularities. For this wavelength longer than 400 nm, absorption of gallium nitride is small, and it is speculated that thermal decomposition of gallium nitride hardly occurred. In addition, the scale of FIG. 4 differs from FIGS. 1-3, and the beam irradiation trace 14 is expanded compared with the beam irradiation trace 11a etc. shown in FIGS.

The beam irradiation traces 11a and 11b and the third harmonic formed by irradiating the fourth harmonic at 0.24 J / cm 2 and 11.7 J / cm 2, respectively, among the beam irradiation traces formed in the experiment described with reference to FIGS. 1 to 4. Beam irradiation traces 12a and 12b formed by irradiating at 2.0 J / cm 2 and 11.7 J / cm 2, respectively, are suitable for use as marks because of their high contrast to the original substrate surface and excellent visibility. In addition, these beam irradiation traces are favorably controlled in shape.

On the other hand, the beam irradiation traces 13a and 13b formed by irradiating the third harmonic at 0.25 J / cm 2 and 0.56 J / cm 2, respectively, have lower uniformity than the beam irradiation traces 11a, 11b, 12a and 12b. , The contrast to the original substrate surface is low. Further, the beam irradiation trace 14 formed by irradiating the second harmonic at 3.4 J / cm 2 does not have good visibility because the region having high reflectance is narrow.

From the above experiments, it is considered that the fourth harmonic (wavelength 262 nm) can perform good processing when irradiated at a pulse energy density of about 0.2 J / cm 2 or more. The upper limit of the pulse energy density which can be processed favorably is considered to be about 12 J / cm <2> or more. And if the pulse energy density is too high, a crack will generate | occur | produce on the surface of a board | substrate, or a hole will be formed without a region with high reflectance. Therefore, the pulse energy density needs to be suppressed to the extent that cracks do not occur or holes are formed.

When the third harmonic (wavelength 349 nm) is irradiated at a pulse energy density of about 1 J / cm 2 or more, it is considered that good processing can be performed. The upper limit of the pulse energy density which can be processed favorably is considered to be about 12 J / cm <2> or more. And if the pulse energy density is too high, a crack will generate | occur | produce on the surface of a board | substrate, or a hole will be formed without a region with high reflectance. Therefore, the pulse energy density needs to be suppressed to the extent that cracks do not occur or holes are formed.

And when the 3rd harmonic is used, the lower limit of the pulse energy density which can perform favorable process is high compared with the 4th harmonic. This is assumed to be because the light absorption coefficient of gallium nitride for the third harmonic is smaller than the light absorption coefficient of gallium nitride for the fourth harmonic.

The beam irradiation traces (regions with high reflectance) formed in the experiments described above were almost on the same plane as the region on which the laser was not irradiated on the surface of the substrate, as observed by the reflective optical microscope. Therefore, when irradiating a laser on the conditions of the experiment demonstrated with reference to FIGS. And since it is thought that nitrogen was discharged | emitted from the board | substrate by beam irradiation, there is no possibility that the beam irradiation trace may have a recess of extremely small depth.

The present inventors made the following conclusions about the laser irradiation conditions suitable for marking based on the above-mentioned considerations and experiments. The pulse width is preferably set to 1 Hz to 100 Hz, and the peak intensity at the surface to be processed is preferably 1 × 10 ⁶ W to 1 × 10 ⁸ W. In addition, the wavelength is preferably set to 245 nm to 390 nm.

Here, the lower limit of the wavelength of 245 nm is a value existing between the fifth harmonic (wavelength 209 nm) and the fourth harmonic wave (262 nm) of the YLF laser. An upper limit of 390 nm is a value existing between the third harmonic (wavelength 349 nm) and 400 nm which is a light emission wavelength of gallium nitride.

Next, with reference to FIG. 5A, an example of the laser processing apparatus for marking a gallium nitride substrate is demonstrated.

The laser light source 1 emits a pulsed laser beam. As the laser light source 1, for example, an Nd: YLF laser, an Nd: YAG laser, an Nd: YVO ₄ laser, or the like including a generation unit of third harmonic or fourth harmonic can be used. The pulse width is, for example, 20 nm.

The laser beam emitted from the laser light source 1 is incident on the mask 2 having a circular or rectangular through hole, for example, and a cross section is shaped. The laser beam which exited the mask 2 is reflected by the repeating mirror 3, converged by the lens 4, and irradiated to the surface of the board | substrate 5. The substrate 5 is a gallium nitride substrate. A mark is produced by irradiating a laser beam to the board | substrate 5. The marking method will be described later with reference to FIG. 6.

The optical path length from the mask 2 to the lens 4 and the optical path length from the lens 4 to the surface of the substrate 5 have a reduction ratio in which the through holes of the mask 2 are suitable for the surface of the substrate 5. It is adjusted to form an image (mask imaging method). The reduction factor is, for example, about tens of times. When the shape of the through hole of the mask 2 is circular with a diameter of 1 mm, the shape of the through hole on the surface of the substrate 5 is, for example, circular with a diameter of 70 µm.

By the mask imaging method, a laser beam is irradiated to the area | region on the substrate surface which has a shape similar to the through-hole of the mask 2. In the beam irradiation region, nitrogen is released, and the reflectance is increased. By using the mask imaging method, it is possible to form a region having a high reflectance in a shape similar to the through hole of the mask 2 on the substrate surface.

By the way, the light intensity in the cross section of the laser beam radiate | emitted from the laser light source 1 is not uniform normally, but has distribution, such as high in the center of a beam, low in the periphery, etc. If the light intensity is nonuniform, there may be areas in the beam spot on the surface of the substrate where the light intensity exceeds and does not exceed the threshold of the emission reaction of nitrogen. As a result, a bad situation may occur in which a region having a high reflectance is not uniformly formed in the beam spot.

By the mask 2, only the area | region where the light intensity of a beam cross section is substantially uniform (for example, the center area | region of the Gaussian beam whose light intensity distribution in a beam cross section is Gaussian distribution) can be irradiated to the board | substrate 5. Thereby, the region with a high reflectance can be formed uniformly in a beam spot.

The substrate 5 is supported by the XY stage 6. The XY stage 6 can move the incidence position of the laser beam with respect to the board | substrate 5 by moving the board | substrate 5 in the plane parallel to the surface of the board | substrate 5. The control apparatus 7 controls the XY stage 6 so that the board | substrate 5 may be located in a desired place at a desired timing.

And even if the through-hole of the mask 2 is not imaged on the board | substrate surface, a favorable marking can be performed to some extent. In this case, the shape of the beam spot on the substrate surface does not accurately reflect the shape of the through hole. However, with the mask 2, only the region where the light intensity of the beam cross section is almost uniform can be selected and irradiated to the substrate 5.

In addition, even if the mask 2 is omitted in the laser processing apparatus of FIG. In this case, however, the shape of the beam spot does not change other than the shape corresponding to the cross section of the laser beam emitted from the laser light source 1. Since it is impossible to select and irradiate a region where the light intensity of the beam cross section is almost uniform, the nonuniformity of the light intensity in the beam spot on the substrate cannot be reduced. However, even when the light intensity distribution of the beam cross section is not uniform, when the output of the laser is increased, the threshold of the nitrogen emission reaction can be exceeded even in a region where the light intensity in the beam cross section is relatively weak.

5B is a schematic diagram showing another example of a laser processing apparatus for marking a gallium nitride substrate. Hereinafter, the difference from the laser processing apparatus of FIG. 5A is demonstrated.

The laser beam emitted from the laser light source 1 and passing through the mask 2 enters the galvano scanner 8 and vibrates in a two-dimensional direction in a traveling direction. The laser beam exiting the galvano scanner 8 is converged by the fθ lens 4a and irradiated onto the surface of the substrate 5 supported by the XY stage 6.

The galvano scanner 8 can move the incident position of the laser beam with respect to the board | substrate 5 by vibrating the advancing direction of a laser beam. The controller 7a controls the galvano scanner 8 so as to vibrate the laser beam in the desired travel direction at the desired timing. The controller 7a also controls the XY stage 6 so that the substrate 5 is positioned at a desired position at a desired timing. The incident position of the laser beam on the substrate 5 may be moved while simultaneously operating the galvano scanner 8 and the XY stage 6.

Next, with reference to FIG. 6, the marking method by the Example of this invention is demonstrated. FIG. 6 is a plan view of the substrate 5 supported by the XY stage 6 shown in FIG. 5A.

On the surface of the board | substrate 5, the mark 20 comprised from several dot 20a, 20b, 20c, etc. is formed. Each dot is a region with high reflectance. The mark 20 expresses the character "12A" which consists of two Arabic numerals and one English character.

The mark 20 is produced by the method as demonstrated below. First, the substrate 5 is positioned by moving the XY stage so that the laser beam is irradiated to the position of the dot 20a. When the substrate 5 is aligned, one shot of the pulsed laser beam is irradiated.

In the beam irradiation area, the pyrolysis reaction of gallium nitride is induced to release nitrogen out of the substrate. In this way, a dot 20a is formed at the beam irradiation position, which is a region rich in gallium and high in reflectance.

Next, the substrate 5 is positioned by moving the XY stage so that the laser beam is irradiated to the position of the dot 20b. When the substrate 5 is aligned, one shot of the pulsed laser beam is irradiated. Similar to the dot 20a, the dot 20b which is a region with high reflectance is formed.

Subsequently, the substrate 5 is positioned by moving the XY stage so that the laser beam is irradiated to the position of the dot 20c. When the substrate 5 is aligned, one shot of the pulsed laser beam is irradiated. Similar to the dot 20a, the dot 20c which is a region with high reflectance is formed. Thereafter, the marks 20 are formed by forming each other dot in the same procedure.

By using the marking method described above, by increasing the reflectance of a desired region of the gallium nitride substrate surface, it is possible to produce a mark excellent in visibility as compared with a mark formed by digging a hole or a groove in the substrate surface or a mark formed inside the substrate.

Since no holes or grooves are formed in the substrate, unlike the marking method of digging holes or grooves in the substrate, the mechanical strength of the substrate is not impaired. Moreover, generation | occurrence | production of a crack can be suppressed by performing laser irradiation, setting a pulse width etc. suitably. In this manner, damage to the substrate can be suppressed, so that the yield of processing can be improved. Since no holes or grooves are formed in the substrate, it is possible to prevent the substrate from being contaminated by the by-products.

In one shot of the pulsed laser beam, since the reflectance of the substrate surface can be made high, the processing speed can be increased, and productivity can be improved.

The mark 20 is composed of a region having high reflectance (dots 20a to 20c, etc.). The area outside the mark 20 on the substrate surface has a low reflectance. In this way, the marks 20 can be recognized as marks because the regions having different reflectances are adjacent to the substrate surface. By forming a mark with high visibility on the substrate, it becomes easy to identify one substrate and another substrate. The difference in reflectance between two zones on the substrate surface corresponds to the fact that the ratio (or nitrogen atom density) of the number of nitrogen atoms to the number of gallium atoms in the two zones is different from each other.

The number, size, and arrangement of dots constituting the mark can be appropriately selected depending on the mark to be produced. You may comprise a mark with one dot.

Dots are not limited to circles. Arbitrary shapes, such as a square, may be sufficient. The shape of a dot can be changed, for example by changing the shape of the through-hole of a mask. The area | region which raises a reflectance is not limited to dot-shaped dot, Arbitrary shapes, such as linear shape and surface shape, may be sufficient. For example, a plurality of dots are formed along a desired linear region so that neighboring dots are in contact with (or partially overlapping) each other, whereby a linear region having a high reflectance can be formed.

In a region having a high reflectance (laser irradiated), a region having a low reflectance (not irradiated laser) may form a pattern in which one or a plurality of discrete portions exist. For example, it is also possible to form the mark which consists of a zone with low reflectance by arrange | positioning a some area with low reflectance in a letter shape.

Consider the case where the gallium-rich region is formed on the outer surface of the substrate. In the above description, regarding the light incident from the outside of the substrate, a mark was produced using the high reflectance of the gallium-rich region. On the other hand, with respect to the light incident on the back surface of the substrate, the gallium-rich region has a lower transmittance than the original substrate. Therefore, the mark produced by the above-described method functions as a mark even when viewed as transmitted light incident on the back surface of the substrate.

As described above, the marking on the gallium nitride substrate has been described. The marking using a reaction of releasing nitrogen from the surface of the substrate is also effective for substrates of other inorganic nitrides such as aluminum nitride (especially metal nitrides composed of metal elements and nitrogen). That is, on the surface of the inorganic nitride substrate made of an inorganic compound of elements other than nitrogen and nitrogen, a region having a relatively high ratio and a low ratio of the number of atoms of nitrogen to the number of atoms of elements other than nitrogen is formed to form a reflectance. By forming these relatively high and low regions, it is possible to produce a mark excellent in visibility.

In addition, the object in which a mark is formed is not limited to a board | substrate, Various members which consist of inorganic nitrides may be sufficient.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various changes, improvements, combinations, and the like are possible.

By forming a region having a high reflectance in the shape of letters, for example, on the surface of the inorganic nitride member, a mark excellent in visibility can be produced. With respect to the plurality of inorganic nitride members in which such a mark is formed, it is easy to identify a member and another member.

The inorganic nitride member can be irradiated with a laser to prevent the formation of deep recesses in the member when nitrogen is released. The mechanical strength of the member can be prevented from being damaged, and the member can be marked.

FIG. 1A is a micrograph showing the result of irradiating the fourth harmonic of the YLF laser at a pulse energy density of 0.24 J / cm 2.

FIG. 1B is a micrograph showing the result of irradiating the fourth harmonic of the YLF laser with a pulse energy density of 11.7 J / cm 2.

FIG. 2A is a micrograph showing the result of irradiating the third harmonic of the YLF laser with a pulse energy density of 2.0 J / cm 2.

FIG. 2B is a micrograph showing the result of irradiating the third harmonic of the YLF laser with a pulse energy density of 11.7 J / cm 2.

FIG. 3A is a micrograph showing the result of irradiating the third harmonic of the YLF laser with a pulse energy density of 0.25 J / cm 2.

3B is a micrograph showing the result of irradiating the third harmonic of the YLF laser at a pulse energy density of 0.56 J / cm 2.

4 is a micrograph showing the result of irradiating the second harmonic of the YLF laser with a pulse energy density of 3.4 J / cm 2.

5A is a schematic view showing an example of a laser processing apparatus used for a marking method.

5B is a schematic view showing another example of the laser processing apparatus used for the marking method.

6 is an example of a mark produced by the marking method according to the embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

1: laser light source

2: mask

3: repeat mirror

4: lens

5: substrate

6: XY stage

7, 7a: controller

8: galvano scanner

4a: fθ lens

10: substrate

11a, 11b, 12a, 12b, 13a, 13b, 14: beam irradiation trace

20a, 20b, 20c: dots

20: Mark

Claims (10)

On the surface of a member made of an inorganic compound of a first element other than nitrogen and nitrogen, the ratio of the number of atoms of nitrogen to the number of atoms of the first element is formed by forming regions with relatively high and low regions. A method of marking an inorganic nitride member, the method comprising: arranging a region having a relatively high reflectance and a region having a low reflectance on a surface of a substrate. (a) emitting a laser beam from the laser light source, (b) irradiating a laser beam emitted from the laser light source to a first region partitioned on the surface of a member made of an inorganic compound of a first element other than nitrogen and nitrogen to release nitrogen atoms out of the member; The ratio of the number of atoms of nitrogen to the number of atoms of this first element in this first region is determined by the ratio of nitrogen to the number of atoms of this first element in the region where the laser beam on the surface of this member is not irradiated. A method for marking an inorganic nitride member, comprising the step of making it smaller than the ratio of the number of atoms. The method of claim 2, The laser light source is a marking method of the inorganic nitride member for emitting a pulsed laser beam having a pulse width of 1 ns to 100 ns. The method according to claim 2 or 3, The laser light source emits a pulsed laser beam, and the peak intensity of the pulsed laser beam on the surface of the member is 1 × 10 ⁶ W to 1 × 10 ⁸ W. The method according to any one of claims 2 to 4, The laser light source emits a pulsed laser beam, The method for marking an inorganic nitride member in the step (b), wherein only one pulse of a pulsed laser beam is irradiated to the first region of the surface of the member. The method according to any one of claims 2 to 5, Moreover, after the step (b), In the region where the laser beam is irradiated by moving the position where the laser beam is incident on the member, irradiating the laser beam emitted from the laser light source to the surface of the member, emitting nitrogen atoms out of the member. The ratio of the number of atoms of nitrogen to the number of atoms of the first element is smaller than the ratio of the number of atoms of nitrogen to the number of atoms of the first element in the region where the laser beam on the surface of this member is not irradiated. A marking method for an inorganic nitride member comprising a step of performing a treatment a plurality of times. The method according to any one of claims 2 to 6, A marking method for an inorganic nitride member, wherein the first element is gallium or aluminum. An inorganic nitride member in which a mark is formed by adjoining at least two zones having different nitrogen atomic densities, wherein the member is made of an inorganic compound of a first element other than nitrogen and nitrogen. The method of claim 8, An inorganic nitride member in which nitrogen atomic densities are different from each other and adjacent regions are formed on the same plane. The method according to claim 8 or 9, An inorganic nitride member, wherein the first element is gallium or aluminum.