Ceramic substrate, ceramic circuit board, semiconductor device, method for manufacturing a ceramic substrate, and method for manufacturing a ceramic divided substrate

Abstract

A ceramic substrate according to the embodiments is characterized by having two or more peaks in the 98-106 eV range in a spectrum obtained by measuring a laser irradiation region of a laser machining surface via XPS. Also provided are a ceramic circuit substrate and a semiconductor device comprising the ceramic substrate, and manufacturing methods for the ceramic circuit substrate and a ceramic divided substrate.

Description

Technical Field

[0001] Embodiments generally relate to a ceramic substrate, a ceramic circuit board, a semiconductor device, a method for manufacturing a ceramic substrate, and a method for manufacturing a ceramic divided substrate.

Background Art

[0002] In recent years, with the development of semiconductor devices that require large currents, such as power electronics and next-generation power semiconductors, the demand for ceramic substrates having both heat dissipation properties and electrical insulation properties has been increasing year by year. In particular, as the heat generation of elements increases with miniaturization and high performance, the thickness of the ceramic substrate tends to become thinner in order to efficiently dissipate heat. On the other hand, in order to reduce the manufacturing cost of ceramic substrates, manufacturing is being carried out in a larger shape. Among ceramic substrates, a silicon nitride substrate having high strength, high toughness, and high heat dissipation properties has a substrate with a size of 220 mm × 220 mm × 0.32 mm disclosed (Patent Document 1).

[0003] As one method of dividing a silicon nitride substrate as a ceramic substrate manufactured in a large size to reduce the manufacturing cost into product sizes to be used, a method of taking a large number using a scribe line formed by laser processing is disclosed (Patent Document 2). According to Patent Document 2, when dividing due to taking a large number by laser processing, microcracks in the silicon nitride substrate do not occur more than necessary, and scribe line processing for taking a large number can also be performed easily and at low cost.

[0004] On the other hand, due to the significant reduction in the size and thickness of the substrate before division, issues arising from laser processing of ceramic substrates with high strength and toughness have become apparent. For example, since the ceramic substrate has high strength and thus requires a large force to break along the scribe line, it is necessary to deeply penetrate the laser into the thickness direction of the ceramic substrate. However, to form a scribe line deeply in the thickness direction in this way, a large amount of energy is required. When the energy of the laser is converted into scribing energy, a part of it is converted into thermal energy. When the conversion ratio to this thermal energy is large, the thermal effect becomes large. Therefore, due to this thermal effect, oxidation of the silicon compound often progresses.

[0005] On the laser-processed surfaces up to now, when the processed surface was measured by XPS (X-ray Photoelectron Spectroscopy), two or more peaks in the range of 528 eV or more and 536 eV or less were not observed at every location. Therefore, locations that are easily divided and those that are not easily divided are mixed, and there has been a problem that division may occur during transportation or cleaning.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In recent years, with the increase in the junction temperature of power semiconductor chips, the high reliability of ceramic circuit boards has been demanded. For this reason, a high-strength and thin ceramic circuit board that combines heat dissipation and electrical insulation without compromising high reliability has been demanded.

[0008] The embodiment solves such problems and relates to a ceramic substrate with excellent cost performance that enables efficient production of a small substrate from a high-strength, thin, and large ceramic substrate having both heat dissipation and electrical insulation properties.

Means for Solving the Problems

[0009] The ceramic substrate according to the embodiment is a ceramic substrate having a scribe line, wherein a laser processing surface including the scribe line is formed by laser irradiation, and among the spectra obtained by measuring the laser irradiation region of the laser processing surface by XPS (X-ray Photoelectron Spectroscopy), there are two or more peaks in the range of 98 eV or more and 106 eV or less.

Brief Description of the Drawings

[0010]

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[0011] The scribing line according to the embodiment refers to the scribing line before dividing the ceramic laser scribing substrate into ceramic divided substrates, and the scribing line marks after dividing into ceramic divided substrates (hereinafter referred to as "scribing line"). The ceramic substrate having the scribing line according to the embodiment is characterized in that the scribing line is formed by laser irradiation, and two or more peaks are observed in the range of 98 eV or more and 106 eV or less in the spectrum obtained by measurement using X-ray Photoelectron Spectroscopy (XPS). The two or more peaks within the said range indicate that two or more peaks, such as three or four, may be observed. Note that the "division" of the ceramic laser scribing substrate is also referred to as the "break" of the ceramic laser scribing substrate.

[0012] Fig. 1 shows a plan view of an example of a ceramic substrate according to the embodiment. Reference numeral 1 is a ceramic laser scribing substrate, reference numeral 2 is a ceramic multi-piece substrate, reference numeral 3 is a scribing line which is a non-through hole, reference numeral 4 is each individual ceramic divided substrate to be a product, reference numeral 5 is a peripheral portion not used as a product, reference numeral 7 is a through hole, reference numeral 71 is a through hole which is an example of the through hole 7, and reference numeral 72 is a notch which is an example of the through hole 7. The ceramic laser scribing substrate 1 generally consists of a ceramic multi-piece substrate 2 and a peripheral portion 5. Note that in this specification, the ceramic substrate means the ceramic laser scribing substrate 1, the ceramic multi-piece substrate 2, or the ceramic divided substrate 4.

[0013] In addition, the laser processing in the present invention may be performed in any shape. This shape may be the scribe line 3 as described above, the formation of the notch portion 72 suitable for screwing, or even drilling. The notch portion 7 is formed by overlapping a plurality of dots by laser on the sintered substrate. By ensuring that two or more peaks are observed in any observation region within the range of 98 eV or more and 106 eV or less, for example, in the case of a screwing portion, it leads to a reduction in intensity unevenness on the processed surface and can increase the torque. Similarly, when formed as a scribe line, it will not break during conveyance, and furthermore, the occurrence of defects during splitting can be suppressed.

[0014] Fig. 1 shows an example in which a large number of ceramic divided substrates 4, two vertically and four horizontally, a total of eight, are taken by laser scribing. The ceramic laser scribed substrate 1 is not limited to such a form. It is also possible to process one ceramic divided substrate 4 into a product shape by the scribe line 3, or to take a large number of ceramic divided substrates 4 in a quantity exceeding two vertically and four horizontally. Also, it is not necessary to form scribe lines 3 on all four sides of the ceramic divided substrate 4, and it is sufficient if there is at least one scribe line 3. In Fig. 1, the ceramic divided substrate 4 has a rectangular shape in the plan view, but it may have a substantially polygonal shape, a substantially circular shape, or a shape with rounded corners of a substantially polygon. Also, this scribe line 3 may be provided on both the front and back of the ceramic laser scribed substrate 1. Also, it may be the formation of the scribe line 3 by combining a laser and other methods. In the laser processing of the invention, only one of the continuous oscillation or pulse oscillation methods may be used, or both oscillation methods may be combined. Furthermore, the shape of the ceramic laser scribed substrate 1 may be circular as shown in Fig. 5. Also, the ceramic laser scribed substrate 1 may have a shape such that the shape after breaking has a notch at the corner as shown in Fig. 4.

[0015] The ceramic substrates 1, 2 and the portion of the ceramic divided substrate 4 of the ceramic circuit substrate 10 (shown in FIG. 6) are characterized in that two or more peaks are observed in the range of 98 eV or more and 106 eV or less in the spectrum obtained by measurement with XPS.

[0016] When the ceramic substrates 1, 2, 4 are silicon nitride substrates, the three-point bending strength can be made as high as 600 MPa or more, and further 700 MPa or more. Also, there are those with a thermal conductivity of 50 W / m·K or more, and further 80 W / m·K or more. Examples of those with a thermal conductivity of 80 W / m·K or more include those with about 130 W / m·K. When the ceramic substrates 1, 2, 4 are aluminum nitride substrates, the thermal conductivity can be made as high as 170 W / m·K or more, and further 230 W / m·K or more. Also, there are those with a three-point bending strength of 350 MPa or more, and further 450 MPa or more. In particular, in recent years, there are also silicon nitride substrates and aluminum nitride substrates having both high strength and high thermal conductivity.

[0017] The ceramic substrates 1, 2, 4 may be single plates, or may have a three-dimensional structure such as a multilayer structure (a structure of ceramic-conductor part-ceramic-conductor part). Also, the ceramic substrates 1, 2, 4 are preferably Si-containing ceramic substrates. Examples of Si-containing ceramics include those having as a main component any one or more of sialon, silicon nitride, and silicon carbide. It is more preferable to use a silicon nitride substrate as these Si-containing ceramics.

[0018] The scribe line 3 is processed by a laser. The laser used at this time is preferably selected from any of a semiconductor laser, a fiber laser, an excimer laser, a femtosecond laser, a YAG laser, a YVO laser, a CO2 laser, a DDL laser, and a blue laser. When using a YAG laser, second harmonic, third harmonic, or fourth harmonic may be used as necessary. Particularly preferably, a laser with a wavelength of 1200 nm is used. Lasers with a wavelength of 1200 nm or less include fiber lasers, excimer lasers, femtosecond lasers, YAG lasers, YVO lasers, etc. Among these laser types, it is more preferable to use a fiber laser. When using such a laser, a condenser lens or a mirror may be used as necessary. When using a condenser lens, it is preferable to use it under appropriate conditions according to the position and thickness of the substrate in terms of its type and arrangement. By optimizing the conditions of the condenser lens in this way, the depth of focus can be adjusted. As described above, when forming the scribe line 3, it is preferable to move the substrate (for example, the sintered substrate after the sintering process) that is the basis of the ceramic laser scribed substrate 1 to form a groove shape. As methods for adjusting the laser light to control the groove shape, there are two types: a method of adjusting the direction by a mirror and a method of adjusting the laser itself. However, in either case, there is a possibility that the position accuracy cannot be maintained depending on the distance of the optical path, etc. Also, the energy irradiated varies depending on the length of the optical path, and since the laser is a precision machine, there is a possibility that the oscillation energy of the laser changes over time if the laser itself is moved many times. If such a problem occurs, there is a possibility that the peak obtained by XPS cannot be controlled either.

[0019] Therefore, it is preferable to place the sintered substrate itself on a stage and move the stage itself. A method of moving the mirror when using a mirror may also be used, but in this case, the longer the distance from the mirror to the object to be processed, the greater the possibility of deterioration in position accuracy. Also 、The fiber laser complies with the definition in JIS Z 3001-5 (2013). The fiber laser may be one in which Nd, Er, or Ho is doped into a YAG crystal, or one using KLN, PPLN, sapphire, ruby, etc. The fiber diameter is preferably 100 μm or less. Also, the diameter accuracy is preferably an error of 0.001 mm or less, and it is preferable that both the parallelism and perpendicularity are controlled.

[0020] In addition, in the laser including the fiber laser, if necessary, a crystal capable of wavelength conversion such as BBO (beta barium borate) may be used to be used as the second harmonic, third harmonic, fourth harmonic, etc. Also, when using a fiber laser, for the index type, it is more preferable to use either a step index or a grating index. Here, the step index means that the refractive index in the core is uniform, while the grating index means that the refractive index in the core is non-uniform and the intensity distribution becomes higher at the center. Therefore, at the same output, deeper processing is possible with the grating index. Also, the oscillation mode may be a single mode or a multi-mode, but it is more preferable to use a single mode. Here, the heat-affected zone (HAZ) will be described. This heat-affected zone spreads in a substantially concentric circle.

[0021] Also, an assist gas may be used for forming the scribeline. The assist gas preferably used at this time is nitrogen or air. This assist gas is preferably jetted from the jet port before the laser light is oscillated from the laser irradiation port. This is because the speed of light is much faster than the speed of sound, so when jetted simultaneously with oscillation, air resistance occurs, and it takes time for the assist gas to reach the surface of the sintered substrate, resulting in a time difference. In such a case, the effect obtained by using the assist gas may be reduced.

[0022] Also, it is preferable to perform dust collection regardless of the presence or absence of assist gas. By performing dust collection, it is possible to remove the fine dust at high temperature generated by laser irradiation. By performing dust collection in this way, it is possible to inhibit the generation of bubbles that may occur when the generated fine dust is redeposited. FIG. 7 schematically shows a method of dust collection in laser processing. Reference numeral 1 denotes a ceramic laser scribing substrate, reference numeral 11 denotes a metal circuit, reference numeral 14 denotes a laser processing machine, reference numeral 15 denotes fine particles generated by laser irradiation, and reference numeral 16 denotes a dust collector. As shown in FIG. 7 、 When irradiating the ceramic laser scribing substrate 1 on which the metal circuit 11 is formed with a laser from the laser processing machine 14, dust collection of the fine particles 15 is simultaneously performed by the dust collector 16. Thereby, it is possible to suppress a phenomenon in which the fine particles 15 cover the laser output port and destabilize the laser output or the like. By stabilizing the laser output in this way, it is also possible to suppress the change over time of the laser product in the laser irradiation region.

[0023] Also, in the formation of the scribe line 3, it may be obtained by multiple laser irradiations. When forming the scribe line 3 by multiple laser irradiations at the same location in this way, it is preferable to leave an interval of 1 millisecond or more until the next laser processing in the laser processing. That is, the laser is applied to the same location ProcessingWhen performing irradiation, for example, it refers to the case where the time interval between the n-th (n is a natural number) irradiation and the (n + 1)-th irradiation is 1 μs or more. Also, the plurality of time intervals that appear over time may be the same or different. For example, the interval between the n-th irradiation and the (n + 1)-th irradiation and the interval between the (n + 1)-th irradiation and the (n + 2)-th irradiation may be different or the same. By leaving a time interval when irradiating in multiple times like this, the thermal energy remaining in the sintered substrate due to irradiation can be reduced, and then the next laser irradiation can be performed. It is more preferable that this interval is 3 minutes or less. This is because if the interval is longer than 3 minutes, it may take a long time for manufacturing and the yield may deteriorate. Also, the laser oscillation may be either continuous wave (CW: Continuous Wave) or pulse wave (PW: Pulse Wave), or a combination of continuous wave and pulse wave. When using a pulse wave, it is more preferable that the pulse width is short, on the order of nanoseconds or less. If the pulse width is long, the influence of laser irradiation becomes excessive, and oxidation progresses, so there is a possibility that two or more peaks will not be observed in the range of 98 eV or more and 106 eV or less.

[0024] The ceramic substrates 1, 2, and 4 are preferably Si-containing ceramics, and the scribe line 3 is formed by laser processing. Among the spectra obtained by measuring the laser irradiation region, which is the side surface of the laser processing, by XPS, 98e V or more and 106e V or less, it is characterized in that two or more peaks are observed. Also, the upper limit of the number of peaks is not particularly limited, but it is preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. Let the peak intensity of the strongest peak in the range of 98 eV or more and less than 101 eV be I2, and 101e V or more and 106e VWhen the peak intensity of the strongest peak below is defined as I3, the ratio of peak intensities, I3 / I2, is 0.4 or more and 12 or less. Furthermore, it is preferably that I3 / I2 is 0.6 or more and 4.5 or less. More preferably, I3 / I2 is 0.9 or more and 4.1 or less. Even more preferably, I3 / I2 is 0.9 or more and 1.7 or less.

[0025] Here, the peak intensity is defined. The peak intensity is the height of the peak at that time minus the height of the baseline. The baseline is, as shown in Figure 2, a straight line connecting the ends of the peak. The end of this peak is the point where the slope of the spectrum first becomes 0 (minimum value) when looking in one direction from the strongest part of the peak. However, when the minimum value exists between the maximum values and the minimum value is separated from any of the maximum values by less than twice the half-width, it is preferable to use the minimum value that exceeds another maximum value. Also, when it is difficult to measure such a minimum value, the height of one end is used as the height of the baseline. This I2 refers to the intensity of the Si-Si peak, and I3 refers to the Si-O peak intensity. Therefore, adjusting the intensity ratio of Si-O to Si-Si to 2.5 or less means reducing the oxidation of Si due to the thermal effect of laser processing.

[0026] In order to control the peak intensity in this way, it is preferable to perform laser processing on the sintered substrate while performing dust collection in an environment with a humidity of 30% or more and 80% or less and a temperature of 28°C or less. More preferably, the humidity is 35% or more and 75% or less. When laser processing is performed in an environment with a humidity of less than 30%, static electricity may occur, and there is a risk that minute bubbles are likely to be formed due to the repulsion between charged fine particles, which is not preferable. On the other hand, if it is larger than 80%, there is a risk that water molecules in the atmosphere absorb the energy of the laser and the silicon compound hydrates. Therefore, when such a hydrate is formed, the absolute value of the Si-O peak may decrease. This is because the non-bonding electron pair of oxygen is used for bonding with a hydrogen atom instead of bonding with Si. In addition, the hydrates generated by the absorption of the laser energy form hydrogen bonds between molecules. Hydrogen bonds are bonds with a bonding energy weaker than that of covalent bonds.

[0027] Therefore, when a large amount of hydrate is generated, there is a risk that the strength on its side will decrease. Therefore, it is not preferable for a large amount of silicon hydrate to be generated. Here, humidity is the amount of water vapor in the atmosphere relative to the saturated water vapor amount, and the saturated water vapor amount increases as the temperature rises. Therefore, even at the same humidity, the higher the temperature, the larger the amount of water molecules present in the same volume. Therefore, if the temperature is higher than 28°C, there is a risk that the effect of controlling the humidity to 80% or less cannot be sufficiently obtained due to the increase in the saturated water vapor amount. Therefore, the temperature during laser processing is preferably 28°C or less.

[0028] Also, the timing of irradiating the laser to the substrate that is the basis of the ceramic laser scribed substrate 1 is not particularly limited, but it is preferably after sintering. This is because, in the case of a sintered substrate after sintering, it is easy to maintain the position of the scribe line with less change in size in the subsequent process. Further, the conductor portion may be joined after forming the scribe line on the sintered substrate, or the scribe line may be formed after joining the conductor portion to the sintered substrate. Here, after joining the conductor portion means that it may be after the etching process or before the etching process, and it is not necessary to have an etching process. Examples of the method without an etching process include a method of joining a conductor portion with a circuit shape previously imparted by punching or the like. Also, the condensing distance is preferably 0.5 mm or more and preferably 30 mm or less. If the distance between the irradiation port and the substrate is less than 0.5 mm, the plume emitted adheres to the irradiation port, and the energy of the laser processing or the like tends to become unstable, and there is a risk that the position accuracy cannot be sufficiently maintained.

[0029] Also, due to the instability of the output, there is a possibility that the peaks observed by XPS may also change. On the other hand, if it is too far beyond 30 mm, although the adhesion of the plume can be suppressed, there is a risk that the subtle difference in the angle between the laser and the ceramic substrates 1, 2, and 4 will greatly affect the position accuracy. Also, a more preferable range for the condensing distance is 1 mm or more and 15 mm or less. For the same molecular density, the amount of water molecules present per the same distance is the same. Therefore, the farther the distance from the irradiation port, the greater the influence of the water molecules on the output energy of the laser. Also, there is a risk that the influence received from the environment in which the laser processing is performed, such as humidity and temperature, becomes excessive. As a result, there is a possibility that the peaks observed by XPS may also change.

[0030] At this time, XPS used Quantera SXM manufactured by PHI. Therefore, it is preferable to use one with performance equivalent to or better than this. For the X-ray source, single crystal spectroscopic AlKα rays were used. The X-ray output at this time was 4.5 W. Also, the analysis area was 20 μm in diameter.

[0031] The absolute value (peak difference) of the value obtained by subtracting the value of the peak intensity of the strongest peak in the non-irradiated region within the range from the value of the peak intensity of the strongest peak in the irradiated region within the range of 528 eV or more and 536 eV or less is 2500 or less, more preferably 1600 or less. More preferably, the peak difference is 1500 or less. Even more preferably, the peak difference is 800 or more and 1500 or less. Also, the absolute value of the peak intensity of the strongest peak in the irradiated region within the range of 528 eV or more and 536 eV or less is preferably 1000 or more. The fact that this value is 1000 or more indicates that the energy density of the laser is high and that the magnitude of the thermal influence on the non-irradiated region is suppressed. As described above, increasing the energy density can reduce the width of the scribing groove and also improve the ratio of the area of the obtained ceramic divided substrate 4 to the area of the entire ceramic laser scribed substrate 1. Also, the absolute value of the peak intensity of the strongest peak in the irradiated region within the range of 528 eV or more and 536 eV or less is preferably 3500 or less. This is because if it exceeds 3500 and becomes too large, the increase in the oxidation number of the Si component may progress too much and the value of I3 / I2 may become uncontrollable.

[0032] Also, the absolute value of the value obtained by subtracting the value of the peak intensity of the strongest peak in the non-irradiated region within the range from the value of the peak intensity of the strongest peak in the irradiated region within the range of 395 eV or more and 400 eV or less (peak difference) is preferably 2500 or less. More preferably, the peak difference is 2200 or less. Even more preferably, the peak difference is 300 or more and 2000 or less. The peak in this range is a peak derived from an oxide. The fact that the peak difference is 300 or more indirectly indicates that the thermal influence on the non-irradiated region is small and that the influence of the laser remains in the irradiated region.

[0033] Furthermore, it is preferable that the absolute value (peak difference) of the value obtained by subtracting the value of the peak intensity of the strongest peak in the non-irradiated region of the irradiation region from the value of the peak intensity of the strongest peak in the irradiation region within the range of 282 eV or more and 288 eV or less is 2500 or less. More preferably, the peak difference is 1200 or less. 。Non The irradiation region is centered at a measurement location that is 0.05 mm or more away from the laser processing surface. This peak indicates the presence of carbon in the 1S orbital. The presence of carbon in the 1S orbital means having a bond with carbon, and the bond with carbon is derived from a single bond.

[0034] Therefore, the small peak differences among the peak intensities of these three types indicate that the changes in their contents are small with or without laser irradiation. Therefore, it is preferable that the peak differences among the peak intensities of these three types are 2500 or less. Further, it is more preferable that the peak differences among the peak intensities of these types are 2000 or less. Also, it is preferable that this peak difference is within a certain range. Therefore, it is more preferable that the peak difference is 1000 or less. Here, the peak difference is the absolute value of the value obtained by subtracting the peak intensity in the non-irradiated region of the laser within that range from the peak intensity in the irradiated region of the laser within that range. 3 The peak difference C of the peak intensities in the range of E [eV] or more and F [eV] or less

[0035] is represented by the following formula. E-F C = |(peak intensity in the range of E [eV] or more and F [eV] or less in the irradiated region) E-F - (peak intensity in the range of E [eV] or more and F [eV] or less in the non-irradiated region)| The peak difference can be indirectly obtained by comparing the obtained peak heights and determining the magnitude of the difference between the irradiated region and the non-irradiated region of the peak height.

[0036] ​Moreover, it is more preferable that the ceramics to be scribed are mainly composed of one or more of alumina, zirconia, silicon nitride, sialon, and aluminum nitride. Here, the main component means containing 50 wt% or more. It is more preferable that the ceramics to be scribed are Si-containing ceramics. Also, it is more preferable that the type of ceramics is mainly composed of silicon nitride or sialon or silicon carbide. Furthermore, it is more preferable that the main component is silicon nitride.

[0037] Also, it is preferable that the ceramic substrates 1, 2, and 4 are Si-containing ceramics. The Si-containing ceramics are more preferably silicon nitride or silicon carbide or sialon. The thickness of the ceramic substrates 1, 2, and 4 used at this time is not particularly limited, but is preferably 0.1 mm or more and 3.00 mm or less, and more preferably 0.2 mm or more and 2.5 mm or less. 。 If the substrate is less than 0.1 mm thick, it is likely to break during transportation after laser processing, which may have an adverse effect on transportation. On the other hand, if it is more than 3 mm thick, oxidation progresses too much during laser processing, and there is a possibility that two or more peaks cannot be observed on any laser processing surface.

[0038] When the ceramic substrates 1, 2, and 4 are Si-containing ceramics, according to the XPS spectrum, when the peak intensity of the strongest peak at 98 eV or more and less than 101 eV is defined as I2, and the peak intensity of the strongest peak at 101 eV or more and 106 eV or less is defined as I3, it is preferable that the ratio of the peak intensities, I3 / I2, is 2.5 or less. This I2 refers to the intensity of the Si-Si peak, and I3 refers to the peak intensity of Si-O. Therefore, adjusting the intensity ratio of the Si-O and Si-Si peaks to 2.5 or less means reducing the increase in the oxidation number of Si due to the thermal effect of laser processing.

[0039] Also, the peaks thus obtained are subjected to waveform separation, and their integral values are compared. Here, the integral value indicates the area of the peak. Therefore, this integral value depends on the peak intensity and the full width at half maximum. The method of waveform separation shall refer to the spectrum of the non-irradiated region and the main peak in the range of 98 eV or more and 106 eV or less.

[0040] Let the peak integral value of the strongest peak in the range of 98 eV or more and less than 101 eV be S2, and the peak integral value of the strongest peak in the range of 101 eV or more and 106 eV or less be S3. Then, it is preferable that S3 / S2, which is the ratio of the peak intensities, is 0.8 or more and 4.2 or less. By controlling not only the peak intensity but also the integral value of the peak in this way, the production ratio of the compound or single substance capable of forming the Si-Si bond and the compound capable of forming the Si-O bond can be further controlled.

[0041] In the scribeline 3 obtained by the laser, its depth may be appropriately changed depending on its use and the like. For example, the laser processing depth D (shown in Figure 3) can be appropriately changed by changing the energy density and the like. As described above, as a method of changing the laser processing depth D, it may be by changing the moving (scanning) speed of the sintered substrate. Examples of the method of changing the scanning speed include changing the speed at which the sintered substrate is moved. Also, the scanning speed can be appropriately changed as needed, but if it is too slow, there is a risk that the thermal influence due to the laser energy will become excessive. Therefore, it is preferable to have a scanning speed of a certain level or more.

[0042] The laser processing surface of the ceramic laser scribed substrate 1 shown in Figure 3 6In this case, the opening end 81 and the opening end 82 are respectively set as two end portions on the perpendicular line of the laser scanning direction L at the opening (laser irradiation side) of the laser recess 8. On the other hand, it is preferable that the minimum angle (angle θ) of the deepest portion formed by the deepest portion at the laser processing depth D of the laser recess 8 and the two opening ends 81 and 82 is 3 degrees or more and less than 90 degrees. Further, it is more preferable that the angle θ is 5 degrees or more and 60 degrees or less. Furthermore, it is preferable that the angle θ is 5 degrees or more and 45 degrees or less. As a more preferable range, the angle θ is 5 degrees or more and less than 30 degrees. As described above, by controlling the angle θ, when dividing the ceramic laser scribed substrate 1 along the scribe line 3 or forming the notch 72, the wasted portions (ears) are reduced, and it leads to an improvement in the positional accuracy at the time of break (division) or separation. Also, as described above, not only the positional accuracy at the time of division or separation is improved, but even if the angle θ becomes a sharp acute angle due to the presence of formed layers with different strengths at the time of division or the like, it can be prevented from being divided when it is not desired to be divided. Also, on the laser processed surface of such a ceramic laser scribed substrate 1 6 In addition to the non-penetrating laser recess 8, and / or, a partially penetrating laser recess (not shown) may be provided. That is, in one ceramic laser scribed substrate 1, a laser processing mark that penetrates and a non-penetrating portion may coexist.

[0043] Also, as shown in FIGS. 8 to 10, the ceramic laser scribed substrate 1 including the multi-ceramic substrate 2 has other scribe lines ンとAt least two scribe lines 31 that extend from the intersection point to the protruding edge on the outside, a scribe line 32 between adjacent ceramic substrates 4, and other scribe lines 33 (illustrated only in FIGS. 8 and 9 out of FIGS. 8 to 10) are provided. And it is preferable that the scribe line 32 protrudes outside the intersection points with the scribe lines 31 and 33. For example, in FIG. 8, two lines extending in the left-right direction of the paper surface are the scribe lines 31, in FIG. 9, two lines extending in the up-down direction of the paper surface are the scribe lines 31, and in FIG. 10, a total of four lines including two lines extending in the left-right direction of the paper surface and two lines extending in the up-down direction of the paper surface are the scribe lines 31. As described above, if the scribe line 32 is designed to protrude outside the intersection points with the scribe lines 31 and 33, there is a risk of leading to a displacement of the scribed dot (hereinafter simply referred to as "dot") 3A (illustrated in FIG. 17) or a cracking defect U at the time of breakage caused by the dot 3A (illustrated in FIG. 18). On the other hand, as shown in FIG. 11, the ceramic laser scribed substrate 1 has a protruding width W2 of the scribe line 32 with respect to the protruding width W1 of the scribe line 31, and it is more preferable that the width W2 is 0.1 mm or more. Also, it is preferable that the value (W2 / W1) of the protruding width W2 with respect to the protruding width W1 is 1 / 2 or less. By making W2 / W1 1 / 2 or less as described above, the ceramic laser scribed substrate 1 will not be inadvertently divided (broken) during conveyance, and the tact time can also be shortened. More preferably, W2 / W1 is 1 / 4 or less 。

[0044] Furthermore, as a process separate from the laser processing for splitting, a notch shape such as a screw portion may be provided by laser processing. Also, only the formation of the notch portion 72 may be performed without performing the laser processing for splitting. Therefore, the laser processed surfaces of the ceramic substrates 1, 2, and 4 6 are not particularly limited in their shape. Also, the timing for performing separation such as splitting may be any. For example, such a separation process may be performed in two steps, with another process sandwiched in between

[0045] The scanning speed of the sintered substrate may be freely changed. However, in order for two or more peaks to be observed in the range of 98 eV or more and 106 eV or less regardless of the measurement range, the change amount of the scanning speed is preferably greater than 0 and 1500 mm / s or less. On the other hand, it may be too costly to completely set the change amount of the scanning speed of the sintered substrate to 0. Therefore, it may exceed 0 by controlling the change amount of the scanning speed on the sintered substrate to be as small as possible. This is considering the possibility that it takes some time for the laser output to stabilize.

[0046] In the laser processing of the sintered substrate, fine powders generated by processing called plume or the like may occur. If this plume is too close to the laser irradiation port, it may adhere to the laser irradiation port, leading to instability of the laser output and even the risk of blocking the injection port. Also, in order to suppress the adhesion of these plumes and the like, it is preferable to perform dust collection. Also, assist gas may be used as necessary. Also, when performing this dust collection, it is preferable to use a dust collector or the like. Also, it is preferable that the dust collector has a filter or the like. Furthermore, when using a dust collector having a filter structure as described above, it is preferable that the fine powders and the like adhering to the filter portion are removed as necessary. By removing the fine powders adhering to the filter portion in this way, a dust collection force of a certain level or more can always be maintained. Also, dust collection also has the effect of suppressing the adhesion of fine powders such as the generated plume to the substrate. The deposits generated by the laser processing of the sintered substrate may be removed in a subsequent process. However, if they remain on the surface of the ceramic laser scribed substrate 1, there is a possibility of peeling off. Also, increasing the laser output without performing dust collection can increase the processing speed, but the damage to the laser processing surface 6 becomes larger.

[0047] After laser processing is performed on the sintered substrate, a conductor part such as a metal plate can be joined to the ceramic laser scribed substrate 1 to form a circuit part (for example, the metal circuit 11 shown in FIG. 6). Further, after joining the conductor part to the sintered substrate, a circuit shape may be imparted, and then laser processing may be performed. In these cases, after forming the metal circuit 11 on the ceramic laser scribed substrate 1, the substrate is divided into the ceramic circuit substrates 10 (shown in FIGS. 14 and 15). Alternatively, after dividing the ceramic laser scribed substrate 1 into the ceramic divided substrates 4, the metal circuit 11 may be formed to obtain the ceramic circuit substrates 10. Further, another process may or may not be included between the laser processing step (step S2 shown in FIGS. 14 and 15) and the dividing step (step S8) along the scribe line performed after the laser processing.

[0048] Examples of the metal used for the metal circuit 11 include copper (Cu), copper-based alloys, and aluminum (Al). When copper is used as the metal circuit 11, oxygen-free copper may be used. Further, the metal circuit 11 may be formed through etching, or a conductor part having a circuit shape in advance may be joined. Examples of the method for imparting the circuit shape in advance include what is called punching.

[0049] As shown in FIG. 6, it is preferable that the ceramic divided substrate (product part) 4 and the metal circuit 11 are joined via a joining layer (for example, the brazing material layer 13). Further, when the metal heat sink 12 is joined to the ceramic divided substrate 4, it is also preferable to join it via a joining layer (for example, the brazing material layer 13). Further, as the brazing material layer 13 between the ceramic divided substrate 4 and the metal circuit 11, it is preferable to provide an active metal brazing material containing an active metal such as Ti (titanium). Examples of the active metal other than Ti include Zr (zirconium), Nb (niobium), and Hf (hafnium). Therefore, other active metals may be used instead of Ti. Examples of the method for providing such a joining layer include a method using a brazing paste and a method using an alloy foil.

[0050] Therefore, if a bonding layer can be provided, the method may use foil or brazing paste. Examples of the active metal brazing material include mixtures mainly composed of either Ag (silver) or Cu in addition to Ti. Further, it is preferable to contain Ti in an amount of 0.1 wt% or more and 10 wt% or less, and Cu in an amount of 5 wt% or more and 96 wt% or less. Additionally, if necessary, one or more selected from In (indium), Sn (tin), Al, Si (silicon), C (carbon), Mg (magnesium), Mo (molybdenum), Mn (manganese), W (tungsten), Re (rhenium), and Os (osmium) may be added in a total amount of 1 wt% or more and 35 wt% or less. Ag is the remainder. Therefore, Ag does not necessarily have to be contained. In the active metal bonding method using an active metal brazing material, an active metal brazing paste is applied to the surface of the ceramic divided substrate 4, and the metal circuit 11 is disposed thereon. This is heated and bonded at a temperature of 600°C or higher and 900°C or lower. Also, a method requiring evacuation may be used for bonding, or it may be performed in an inert atmosphere. Examples of the inert atmosphere include a nitrogen atmosphere (mole fraction 80% or more, more preferably mole fraction 85% or more) and a noble gas atmosphere (argon atmosphere, neon atmosphere). According to the active metal bonding method, the bonding strength between the ceramic divided substrate 4 and the metal circuit 11 can be made 16 kN / m or more.

[0051] Also, a metal thin film mainly composed of one selected from Ni (nickel), Ag (silver), and Au (gold) may be provided on the surface of the metal circuit 11. Examples of these metal thin films include plating films and sputtering films. By providing the metal thin film, corrosion resistance and solder wetting properties can be improved. Also, the film may be provided partially or may cover the entire conductor portion. Furthermore, the ceramic circuit board 10 is not limited to only the structure such as the metal plate - ceramic substrate - metal plate shown in FIG. 6, and may have a five-layer structure such as metal plate - ceramic substrate - metal plate - ceramic substrate - metal plate. Also, the metal plate mentioned here may have a circuit shape or a groove shape on its surface.

[0052] In the embodiment shown in FIG. 6, the bonding area between the ceramic divided substrate 4 and the metal heat sink 12 and the bonding area between the ceramic divided substrate 4 and the metal circuit 11 may be different, or may be the same. Also, the thicknesses of these metals may be the same or different. Furthermore, the metal heat sink 12 and the ceramic divided substrate 4 may be bonded without using the brazing material layer 13. Also, a conductor portion other than the brazing material layer 13 may be provided between the metal heat sink 12 and the ceramic divided substrate 4.

[0053] Such a ceramic circuit board 10 is suitable for a semiconductor module characterized by mounting a semiconductor element on a metal circuit 11 via a bonding layer. Also, electronic components such as semiconductor elements may be mounted on the obtained ceramic circuit board 10. Furthermore, in addition to the semiconductor element, wire bonding may be bonded to the metal circuit 11. The wire-bonded ceramic circuit board 10 may be resin-molded to form a semiconductor module. The semiconductor module according to the embodiment is not limited in its structure. For example, either wire bonding or a lead frame may be used. Also, a plurality of semiconductor elements, wire bondings, and lead frames may be provided on the metal circuit 11 respectively.

[0054] Also, examples of the bonding layer for bonding the semiconductor element and the lead frame include solder and brazing material. Solder is preferably lead-free solder. Also, the solder has a melting point of 450° C. or lower. The brazing material has a melting point exceeding 450° C. Also, those with a melting point of 500° C. or higher are called high-temperature brazing materials. Examples of high-temperature brazing materials mainly composed of Ag include Ag paste with controlled particle size and Cu paste mainly composed of copper.

[0055] When sealing the ceramic circuit board 10 with a resin mold, the laser scribed surface may be on the side opposite to the metal circuit 11 (the side of the metal heat sink 12). This is because resin is less likely to enter the recesses generated by laser scribing and there is a possibility of voids forming. Since voids impede heat dissipation, it is preferable to form the scribing lines on the heat sink side to suppress their generation.

[0056] While semiconductor elements are becoming smaller, the amount of heat generated from the chips has been steadily increasing. Therefore, improving heat dissipation is important in the ceramic circuit board 10 on which semiconductor elements are mounted. Also, for the high performance of semiconductor devices (semiconductor modules), multiple semiconductor elements are being mounted on the ceramic circuit board 10. If the true temperature of even a single semiconductor element exceeds the limit, the resistance will change to a negative temperature coefficient on the minus side. Along with this, a phenomenon called thermal runaway occurs where electric power flows intensively and the element is instantaneously destroyed. Therefore, improving heat dissipation is effective. Further, the semiconductor device according to the embodiment can be used in a PCU (Power Control Unit), IGBT (Insulated Gate Bipolar Transistor), or IPM (Intelligent Power Module) module used in inverters such as automobiles (including electric vehicles), electric railway vehicles, industrial machines, and air conditioners. The electrification of automobiles is progressing. Improving the reliability of semiconductor devices directly leads to the safety of automobiles. The same applies to electric railways and industrial equipment.

[0057] Next, the laser scribing method for the silicon nitride substrate among the ceramic substrates 1, 2, and 4 according to the embodiment will be described. The manufacturing method of the silicon nitride substrate is not particularly limited as long as it has the above-described configuration, but the following methods can be mentioned as methods for obtaining a good yield.

[0058] First, prepare a silicon nitride substrate. In particular, considering the heat dissipation of the entire ceramic circuit board 10, it is preferably one with a thermal conductivity of 50 W / m·K or more and a three-point bending strength of 600 MPa or more. Examples of those with a thermal conductivity of 50 W / m·K or more and a three-point bending strength of 600 MPa or more include those with a thermal conductivity of 130 W / m·K and a three-point bending strength of 750 MPa.

[0059] Also, when conducting electrical connection between the metal circuit 11 and the metal heat sink 12 of the ceramic circuit board 10 through a through-hole, prepare a silicon nitride substrate having a through-hole. When providing a through-hole in the silicon nitride substrate, the through-hole may be provided at the pre-form stage. Further, a step of providing a through-hole (for example, through-hole) 71 in the silicon nitride sintered body may be performed. Examples of the step of providing a through-hole include laser processing similar to laser scribing and cutting. Examples of cutting include drilling with a drill or the like.

[0060] Furthermore, the scribe line 3 may be formed by a combination of dots 3A and shallow continuous grooves 3B instead of the continuous grooves 3B shown in FIG. 13 (not shown), or may be formed only by the dots 3A as shown in FIG. 12. Here, the dots 3A are composed of laser processing marks that are separated without overlapping, while the continuous grooves 3B are composed of laser processing marks that at least partially overlap. When the scribe line 3 is formed by the dots 3A, the average value of the widths W3 (shown in FIG. 12) between the locations with the maximum depth for each dot 3A is preferably 50 μm or more and 300 μm or less. More preferably, the average value of the width W3 is preferably 50 μm or more and 150 μm or less. Further, it is preferable to control the width W4 (shown in FIG. 12) of the scribe mark of the dot 3A to be 20 μm or more and 100 μm or less. The depth of the dot 3A is preferably 1 / 6 or more and 2 / 3 or less of the substrate thickness. Also, the depth of the dot 3A is preferably 50 μm or more and 300 μm or less. More preferably, the depth of the dot 3A is preferably 150 μm or more and 250 μm or less. Further, in the laser processing, in addition to the dots 3A (shown in FIG. 12) or the continuous grooves 3B (shown in FIG. 13), it is preferable to irradiate the periphery of the dots 3A or the continuous grooves 3B a plurality of times partially to form auxiliary cut lines (auxiliary continuous grooves or dots). By forming the auxiliary cut lines in addition to the dots 3A or the continuous grooves 3B in step S2 shown in FIGS. 14 to 16 to form the scribe line 3, the defect rate can be further reduced during splitting.

[0061] Before the step of providing the scribe line 3 (step S2) on the ceramic substrates 1, 2, 4, a step of placing the substrate on a stage (step S 1 ) is included, and after the step of providing the scribe line 3 (step S2), a step of cleaning the surface using honing or blasting or the like (step S 3It is preferable to have い。 As shown in FIG. 14, it is more preferable to have a step of cleaning the ceramic circuit board 10 before division (step S7) before the step of dividing the ceramic circuit board 10 (step S8). As shown in FIG. 15, it is even more preferable to have a step of cleaning the ceramic circuit board 10 (step S7) after the step of dividing the ceramic circuit board 10 (step S8). This is because there is a risk of adhesion of minute powders generated during division, and the powders should be cleaned in step S7. Further, the scribe line 3 may be a scribe line for dividing only the peripheral portion as shown in FIG. 19.

[0062] Set the silicon nitride substrate on the precision processing table of a laser processing machine such as a fiber laser (step S1). Irradiate the silicon nitride substrate with a laser to form laser processing marks such as the scribe line 3 composed of dots 3A (illustrated in FIG. 12). At this time, dots 3A of a predetermined size are formed according to the conditions of the laser processing machine 14 (illustrated in FIG. 7). Also, the laser processing is preferably performed by moving the precision processing table. This is because when controlling the processing by moving the laser or changing the orientation of the mirror during laser processing, it may become difficult to adjust the scanning speed.

[0063] Join a metal plate (metal circuit 11 and metal heat sink 12) to the silicon nitride substrate on which the scribe line 3 is formed, that is, the ceramic laser scribe substrate 1. The bonding of a silicon nitride substrate and a metal plate is preferably performed by an active metal bonding method. The active metal bonding method shall use an active metal solder material mixed with an active metal such as Ti. Examples of the active metal solder material include a mixture of Ti and Cu. Further, this active metal solder material may contain Ag as required. When Ag is contained, it is preferably 99.5 wt% or less. More preferably, it is 95 wt% or less. By controlling the content of Ag in this way, an effect of making ion migration less likely to occur can be expected. It is known that ion migration is more likely to occur in Ag than in Cu. On the other hand, when there is more silver, the reliability of bonding at high temperatures increases. Therefore, it is more preferable to freely adjust the amount of silver in the range of 0 wt% or more and 95 wt% or less according to requirements and applications. For example, Ti is 0.1 wt% or more and 10 wt% or less, Cu is 0.5 wt% or more and 60 wt% or less, and Ag is the balance.

[0064] Therefore, Ag does not necessarily have to be contained, and it may contain about 95 wt%. Further, if necessary, one or more selected from In, Sn, Al, Si, C, Mg, Mo (molybdenum), Mn (manganese), W (tungsten), Re (rhenium), Os (osmium) may be added in a total amount of 1 wt% or more and 35 wt% or less. The active metal solder material is made into a paste. The paste is a mixture of a solder component and an organic substance, but the solder components need to be uniformly mixed. This is because if the solder components are unevenly distributed, soldering will not be stable and will cause poor bonding.

[0065] The active metal solder paste is applied to the ceramic laser scribed substrate 1. A copper plate is placed thereon. Next, a step of heating and bonding this at 600 °C or higher and 900 °C or lower is performed. The heating step shall be performed in a vacuum or a non-oxidizing atmosphere as required. When performing in a vacuum, 1×10 -2It is preferably below Pa. Examples of the non-oxidizing atmosphere include a nitrogen atmosphere, an argon atmosphere, a helium atmosphere, a neon atmosphere, etc. Here, the non-oxidizing atmosphere is not particularly limited, but refers to one with an oxygen partial pressure of 10% or less. By setting it in a vacuum or a non-oxidizing atmosphere, oxidation of the bonding layer can be suppressed. Thereby, an improvement in bonding strength can be achieved.

[0066] The conductor part to be joined may be either one that has been pre-processed into a pattern shape for circuit formation or a single plate without pattern processing. Also, when using a single plate, etching processing is performed after joining to process it into a pattern shape. At this time, the metal circuit 11 may be formed on the surface opposite to the surface where the scribeline is formed. Through this process, a silicon nitride metal circuit board as the ceramic circuit board 10 can be manufactured.

[0067] Next, a step of joining a semiconductor element or the like to the silicon nitride metal circuit board is performed. A bonding layer is provided at the location where the semiconductor element is to be joined. The bonding layer may be solder or brazing material, or a silver layer using silver paste or the like. Also, it may be a copper layer using copper paste. A bonding layer is provided, and a semiconductor element is provided thereon. Also, if necessary, a lead frame is joined via the bonding layer. Also, if necessary, wire bonding is provided. Also, the semiconductor element, the lead frame, and the wire bonding are provided in necessary numbers. The silicon nitride circuit board on which the semiconductor element, the lead frame, and the wire bonding have been performed is molded with resin to seal the interior.

[0068] A method for laser scribing a silicon carbide substrate among the ceramic substrates 1, 2, and 4 according to the embodiment will be described. First, a silicon carbide substrate is prepared. In particular, considering the heat dissipation of the entire ceramic circuit board 10, it is preferably that the thermal conductivity is 150 W / m·K or more and the three-point bending strength is 400 MPa or more. If the laser scribing of the silicon carbide substrate has the above-described configuration, its manufacturing method is not particularly limited. However, as a method for obtaining a good yield, the same manufacturing process as that of the above-described silicon nitride substrate and silicon nitride circuit board is adopted.

[0069] (Examples 1 to 22, Comparative Examples 1 to 7) For the ceramic substrates 1, 2, and 4, silicon nitride substrates (thermal conductivity: 90 W / m·K, three-point bending strength: 650 MPa) with a length of 200 mm, a width of 180 mm, and thicknesses of 0.32 mm and 0.50 mm were prepared. Also, silicon carbide substrates (thermal conductivity: 300 W / m·K, three-point bending strength: 400 MPa) with a length of 200 mm, a width of 180 mm, and thicknesses of 0.635 mm and 0.80 mm were prepared. Next, as shown in FIG. 1, dust collection was performed on one surface of a substrate (for example, a sintered substrate) that is the basis of the ceramic laser scribing substrate using a fiber laser, and eight laser processes per substrate were performed 200 sheets each under the conditions of Examples 1 to 22 and Comparative Examples 1 to 7. The processing shapes are as shown in Table 2. Note that the scribing lines of Examples 2 to 4, 10 to 12, 18, 21 and Comparative Examples 1 and 4 shown in Table 2 correspond to dots. Also, those that satisfy both conditions of temperature and humidity are described as "〇 (circle)" in the "Temperature · Humidity" column of Table 1, and those that do not satisfy either one are described as "× (cross)".

[0070] Also, those described as "〇 (circle)" in the "Laser Conditions" column of Table 1 indicate that the pulse width was set to be on the order of nanoseconds or less and dust collection was performed. Those that satisfy the condition of "condensing distance" are described as "〇 (circle)" in the "Condensing Distance" column. Also, in the laser processing in the comparative examples, no assist gas was used. In addition, the ceramic substrates after laser processing under each condition were subjected to the following processes (referred to as post-processes) such as conveyance under the same conditions. The post-processes are honing, cleaning, drying, and conveyance. When such processes were carried out, the proportion of those that were partially or broken (divided) along the scribe line or deviated from the break line was shown in Table 2. In addition, the angle θ composed of two locations (both ends), namely, the deepest part of the groove portion and the opening end portion, was obtained. The angle θ was described in the column of "Laser Processing Angle" in Table 2. The measurement results of the examples and comparative examples are shown in Table 1 and Table 2. (In Table 1, the silicon nitride (Si3N4) substrate was denoted as "SiN", and the silicon carbide substrate was denoted as "SiC".

[0071] [Table 1] TIFF0007693951000001.tif195170

[0072] [Table 2] TIFF0007693951000002.tif189170

[0073] The ceramic substrates 1, 2, and 4 according to Examples 1 to 17 were within the range of the preferred embodiments in terms of conditions in laser processing. On the other hand, the ceramic substrates according to Comparative Examples 1 to 7 were outside the range of the preferred embodiments. Note that the notch portion described in this example is the notch portion indicated by reference numeral 72 in FIG. 1.

[0074] Next, after dividing under each condition, the laser processing surface at the divided location was measured by XPS. Tables 3 and 4 show the measurement results. The apparatus used for the measurement was Quantera SXM manufactured by PHI. In addition, the X-ray source was a single crystal spectroscopic AlKα line. The X-ray output was 4.5 W, the analysis region was φ20 μm, the geometry was 45 degrees, and the pass energy was -69.00 eV (0.125 eV / Step).

[0075]

Table 3

[0076] [Table 4] TIFF0007693951000004.tif193170

[0077] As can be seen from Tables 3 and 4, in the ceramic substrates 1, 2, and 4 according to all Examples 1 to 22, the number of peaks measured by XPS in the range of 98 eV or more and 106 eV or less was within a preferable range.

[0078] When comparing the Examples and Comparative Examples using Tables 1 to 4, regardless of the laser processing angle, the breakage rate of the Comparative Examples in the subsequent process was as high as 4% or more. On the other hand, in the Examples where preferable peaks were observed by XPS, the breakage rate was less than 4% in all cases and was small.

[0079] It can be understood that by observing two or more peaks in the range of 98 eV or more and 106 eV or less, the laser processed surface was strengthened and unnecessary splitting (breakage) did not occur. The two or more peaks were observed on any laser processed surface.

[0080] Also, defects (cracks, chips, cracks) at the broken portions were not observed in the Examples. On the other hand, in the Comparative Examples, there were those in which these defects were observed. These defects are considered to be due to the influence of the destabilization of the output in laser processing (such as adhesion to the irradiation port of the plume).

[0081] Therefore, it was found that it was important to optimize various conditions in laser processing and control the obtained XPS spectrum.

[0082] The above has illustrated several embodiments of the present invention. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof. Also, the above-described embodiments can be implemented in combination with each other.

Explanation of Reference Numerals

[0083] 1...Ceramic substrate (for example, ceramic laser scribing substrate) 2...Ceramic substrate (for example, ceramic multi-piece substrate) 3...Scribe line 4...Ceramic substrate (for example, ceramic divided substrate (product part)) 5...Peripheral part (non-product part) 6...Laser processing surface 7...Through hole 71...Through hole (for example, through hole) 72...Through hole (for example, notch) 8...Laser recess 9...Non-laser irradiation surface (non-laser processing surface) 10...Ceramic circuit board 11...Metal circuit 12...Metal heat sink 13...Solder layer 14...Laser processing machine 15...Fine particles generated by laser irradiation 16...Dust collector W1...Overhang width of the peripheral edge W2...Overhang width of the scribe line

Claims

1. A ceramic substrate comprising a silicon nitride substrate having two or more peaks in the range of 98 eV or more and 106 eV or less in the spectrum obtained by measuring the laser irradiation region of the laser processed surface with XPS (X-ray Photoelectron Spectroscopy).

2. Among the spectra obtained by measuring the laser irradiation region with the XPS, when the peak intensity of the strongest peak in the range of 98 eV or more and less than 101 eV is I2, and the peak intensity of the strongest peak in the range of 101 eV or more and 106 eV or less is I3, the ceramic substrate according to claim 1, characterized in that the ratio of peak intensities I3 / I2 is 0.4 or more and 12 or less.

3. Among the spectra obtained by measuring the laser irradiation region with the XPS, when the peak intensity of the strongest peak in the range of 98 eV or more and less than 101 eV is I2, and the peak intensity of the strongest peak in the range of 101 eV or more and 106 eV or less is I3, the ceramic substrate according to claim 1, characterized in that the ratio of peak intensities I3 / I2 is 0.6 or more and 4.5 or less.

4. The absolute value of the value obtained by subtracting the peak intensity value of the strongest peak in the non-irradiation region of the range from the peak intensity value of the strongest peak in the irradiation region in the range of 528 eV or more and 536 eV or less in the spectra obtained by measuring the laser irradiation region and the non-laser irradiation region with the XPS is 1600 or less. The ceramic substrate according to any one of claims 1 to 3.

5. The absolute value of the value obtained by subtracting the peak intensity value of the strongest peak in the non-irradiation region of the range from the peak intensity value of the strongest peak in the irradiation region in the range of 395 eV or more and 400 eV or less in the spectra obtained by measuring the laser irradiation region and the non-laser irradiation region with the XPS is 2500 or less. The ceramic substrate according to any one of claims 1 to 3.

6. Among the spectra obtained by measuring the laser irradiation area and the non-laser irradiation area with the XPS, the absolute value of the value obtained by subtracting the peak intensity of the strongest peak in the non-irradiation area of the range from the peak intensity of the strongest peak in the irradiation area within the range of 282 eV or more and 288 eV or less is 2500 or less. The ceramic substrate according to any one of claims 1 to 3, characterized in that.

7. A ceramic circuit board, characterized in that a circuit portion is formed on the surface of the ceramic substrate according to claim 1.

8. The ceramic circuit board according to claim 7, characterized in that a metal circuit as the circuit portion is formed on one or more surfaces of the surface irradiated with the laser or the surface opposite to the laser irradiation surface.

9. The ceramic circuit board according to claim 7, characterized in that the circuit portion contains any one or more selected from aluminum, aluminum alloy, copper, and copper alloy.

10. The ceramic circuit board according to claim 9, characterized in that it is molded with resin.

11. A semiconductor device, characterized in that a semiconductor element is mounted on the ceramic circuit board according to claim 7.

12. After forming dots or continuous grooves by a fiber laser on a part of at least one side of the sintered substrate, and then forming auxiliary dots or continuous grooves by the fiber laser one or more times to form a scribe line, the ceramic substrate according to claim 1 is manufactured. A method for manufacturing a ceramic substrate, characterized in that.

13. When performing laser irradiation on the sintered substrate, the humidity is set to 30% or more and 80% or less, and the temperature is set to 28 ° C or less, thereby manufacturing the ceramic substrate according to claim 1. The method for manufacturing a ceramic substrate according to claim 12, characterized in that.

14. Manufacturing a ceramic laser scribed substrate as the ceramic substrate according to claim 1 by forming a scribe line on at least one side of a sintered substrate with a fiber laser, and applying stress to the ceramic laser scribed substrate to divide the ceramic laser scribed substrate, thereby manufacturing a ceramic divided substrate as the ceramic substrate. A method for manufacturing a ceramic divided substrate, characterized by the above steps.

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