Method for manufacturing ceramic thin-film metallized substrate, method for manufacturing chip-on-submount and method for manufacturing semiconductor module

Abstract

To provide a manufacturing method that enables efficient production of small substrates from large ceramic thin-film metallized substrates with conductive circuits.SOLUTION: A method for manufacturing a ceramic thin-film metallized substrate according to the embodiment comprises: a) a process for roughening a ceramic substrate surface with an etchant diluted between 10% and 50%; b) a process for forming a thin-film metallization on the ceramic substrate; and c) a process for forming a circuit with the etchant.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments are generally directed to a method for manufacturing a ceramic thin film metallized substrate, a chip-on-substrate The present invention relates to a method for manufacturing a mount and a method for manufacturing a semiconductor module. [Background technology]

[0002] In recent years, the number of LEDs used in general lighting, including laser diodes (LDs), and headlamp LEDs has increased. Low-power LEDs and deep UV LEDs (sterilization lamps, resin curing lamps) that require high heat dissipation Optical semiconductor elements capable of emitting high-performance light such as GaN, GaN, and GaN are being developed. Accordingly, the demand for ceramic substrates that combine heat dissipation and electrical insulation properties is increasing year by year. In particular, as the heat generated by optical semiconductor elements increases with their increasing performance, Therefore, ceramic substrates tend to become smaller and thinner.

[0003] Among ceramic substrates, aluminum nitride substrates (AlN) have high heat dissipation properties, and the insulating support The support member is made of aluminum nitride sintered body, and has a titanium (Ti) layer and a white layer on the upper and lower surfaces. A photoreaction element panel having a metal layer formed by sequentially depositing a gold (Pt) layer and a gold (Au) layer. According to Patent Document 1, a nitride alloy is used in a package. The thermal conductivity of aluminum sintered body is 55 to 250 W / m K, and the thermal conductivity is about 20 W / m K. / m·K compared to aluminum oxide sintered body, the heat generated by the optical semiconductor element during operation is insulated The heat is dissipated to the outside through the support member and the metal substrate. As a result, the optical semiconductor element is always kept at an appropriate temperature. As a result, it can be operated normally and stably for a long period of time.

[0004] In order to reduce the manufacturing costs of ceramic substrates that have both heat dissipation and electrical insulation properties, In order to reduce manufacturing costs, larger shapes are being produced. A manufacturing method for dividing a fabricated aluminum nitride substrate into submounts for semiconductor laser devices. For example, the thermal conductivity is 200 W / m K, the thickness is 0.5 mm, and the thickness is 1 mm from the 2-inch substrate. A manufacturing method for cutting corners into square shapes has been disclosed (Patent Document 2).

[0005] The metal layer formed on these insulating substrates improves the surface properties of the metal coating surface and enhances adhesion. In order to achieve this, the ceramic substrate surface is polished and wrapped, and then it is The metal layer is then formed after etching with acid or alkali to increase the specific surface area. In the etching process, treatment with acid or alkali is disclosed (Patent According to Patent Document 3, the acid solution with a 20% dilution concentration kept at 40°C is 5 to 60 Etching can be achieved by immersing the material in the solution for about 10 minutes. Etching can be performed using a strong alkaline solution containing dissolved NaCO, etc., or a weak alkaline solution containing dissolved NaCO, etc. Cut.

[0006] To reduce manufacturing costs, it is advantageous to process from a larger substrate. As the semiconductor products they are built into become smaller and more powerful, the size of these products is becoming smaller. However, as the size of the board increases, However, the bonding strength between the ceramic substrate and the thin-film metallization of the individual products is large. It is required to manufacture it uniformly over the entire surface. Also, etching is required to increase the bonding strength. When the treatment conditions are strengthened, the roughened ceramic substrate surface is affected even by the thin metallized surface. This hinders the visibility of the substrate surface. The law becomes difficult.

[0007] In addition, the ceramic substrate surface is roughened by immersing it in an acid or alkaline solution and then thin-filming it. In the etching process for forming circuits using film metallization, ceramics are immersed in the etching solution. The substrate is exposed. The surface and internal structure of the ceramic substrate changes depending on the composition and manufacturing method. The acid and alkaline solutions used for roughening and the etching solution used in the etching process are This causes a difference in the effect on the mixed substrate. This results in excessive roughening during the etching process. This knowledge may lead to changes in the surface condition of the ceramic substrate. To form a thin film metallization on a ceramic substrate, a process is required to roughen the ceramic substrate. It has become clear that control of both the etching process and the thin film metallization is necessary. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 3199611 [Patent Document 2] Patent No. 4528510 [Patent Document 3] JP 2004-172644 A [Patent Document 4] JP 2003-183077 A Summary of the Invention [Problem to be solved by the invention]

[0009] In recent years, there has been a rapid development of optical semiconductor elements capable of emitting high-performance light, such as laser diodes and LEDs. With the development of ceramic circuit boards, which have heat dissipation, electrical insulation, and circuit conductivity, Demand is increasing year by year. In particular, as the elements become smaller and more powerful, heat generation increases. There is a demand for high reliability of laminated circuit boards. Ceramic thin-film metallized substrate (substrate) with conductive circuit and heat dissipation and electrical insulation properties. Mount) is required.

[0010] The embodiment is intended to solve such a problem, and is a large ceramic substrate having a conductive circuit formed thereon. Cost-effective, enabling efficient production of small substrates from thin-film metallized substrates The present invention relates to an excellent method for producing a ceramic thin-film metallized substrate. [Means for solving the problem]

[0011] The method for producing a ceramic thin film metallized substrate according to the embodiment has a yield of 10% or more and 50% or less. roughening the surface of the ceramic substrate with an etching solution diluted to 100%; forming a thin film metallization on a substrate; and forming a circuit using the etching solution; This is a manufacturing method for forming a pattern circuit by [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a top view showing an example of a metallized ceramic thin film substrate according to the embodiment before cutting. [Diagram 2] FIG. 2 is a top view showing an example of a ceramic thin film metallized substrate according to the embodiment. [Diagram 3] FIG. 2 is a side view showing an example of a ceramic thin film metallized substrate according to the embodiment. [Figure 4] FIG. 2 is a bottom view showing an example of a ceramic thin film metallized substrate according to the embodiment. [Diagram 5]4A to 4C are cross-sectional views showing an example of a manufacturing process for a pattern circuit of a ceramic thin film metallized substrate according to an embodiment of the present invention. [Figure 6] FIG. 2 is a cross-sectional view showing an example of a chip-on-submount substrate according to the embodiment. [Figure 7] FIG. 1 is a cross-sectional view showing an example of a semiconductor module according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a method for manufacturing a ceramic thin-film metallized substrate, a chip-on Detailed description of embodiments of the method for manufacturing a submount and the method for manufacturing a semiconductor module will explain.

[0014] The pattern circuit provided on the ceramic thin film metallized substrate according to the embodiment is a ceramic The conductive and insulating parts are shown by thin-film metallization on the surface of the mixed circuit board, and are divided according to product size. This refers to both the circuit before and after division (hereafter referred to as "pattern circuit"). The formation of a circuit is a process in which conductive and insulating parts are formed on the surface of a ceramic substrate by thin-film metallization. This refers to the pattern circuit that is formed before dividing the ceramic substrate. (hereinafter referred to as "pattern circuit formation").

[0015] The method for producing a ceramic thin film metallized substrate according to the embodiment is as follows: a) Roughen the ceramic substrate surface with an etching solution diluted to 10% to 50%. The process and b) forming a thin film metallization on the ceramic substrate; c) forming a circuit using the etching solution; The following describes the manufacturing method of the ceramic thin-film metallized substrate according to the embodiment. Manufacturing method of a chip-on-submount, a manufacturing method of a semiconductor module, This will be explained in detail.

[0016] FIG. 1 shows a top view of an example of a ceramic thin-film metallized substrate according to an embodiment before cutting. 1 is the ceramic thin-film metallized substrate before cutting, and 2 is the ceramic thin-film metallized substrate The plate is shown in FIG. 3, and the ceramic thin-film metallized substrate is shown in FIG. The ceramic thin-film metallized substrate is cut (divided) into a plurality of cut ceramic thin-film metallized substrates 3. The large-scale ceramic thin-film metallized substrate 2 is shown in FIG. The ceramic thin film substrate is circular, but it may be rectangular. The thin-film metallized substrate 3 has a substantially rectangular shape in plan view, but may have a substantially polygonal shape. .

[0017] FIG. 2 shows an example of a top view of the ceramic thin-film metallized substrate 3 after cutting according to the embodiment. 4 is a thin metallization, and 5 is a ceramic substrate. The ceramic substrate 5 is aluminum nitride. For miniature substrates, the thermal conductivity must be 160W / m K or higher, or even 240W / m K. As another example of the ceramic substrate 5, aluminum oxide can be used. The ceramic substrate 5 may be a single plate. The polymer may have a three-dimensional structure such as a multi-layer structure.

[0018] FIG. 3 is a side view of the ceramic thin-film metallized substrate shown in FIG. 2. 6 is a thin-film metallized substrate. FIG. 4 is a bottom view of the thin-film metallized substrate of FIG. 2. In FIG. 4, the bottom surface of the ceramic substrate is A thin metallization is formed on the entire surface, but a circuit may be formed on the same surface as on the top surface. It is acceptable to use a ceramic substrate without metallization. In this case, the heat sink is joined by brazing or soldering, forming a thin metallized layer. If not, it is bonded to the heat sink with an adhesive such as resin.

[0019] FIG. 5 shows one of the steps of manufacturing a pattern circuit of a ceramic thin film metallized substrate according to an embodiment. 7 is a cross-sectional view showing an example of a ceramic substrate 5 after polishing. (B) is a surface that has been polished by lapping or polishing. (B) is a ceramic surface that has been roughened. (C) is a cross-sectional view of the substrate. 8 is the roughened ceramic substrate surface. The resist 9 is applied to the roughened surface of the substrate 5. (D) shows the substrate 5 after pre-baking. The ceramic substrate 5 is exposed to light through a mask 10, and the unmasked portion is exposed to light. (E) shows the state where the resist 11 is irradiated with ultraviolet light after exposure. The photoresist 11 is exposed to light on the ceramic substrate. The exposed resist 11 is formed on the surface of the ceramic substrate 5 by photolithography (development). (G) shows the exposed resist 11 and the thin film on the surface of the ceramic substrate 5. This shows the state after the metallization 12 has been formed. (H) shows the state after the exposed resist 11 has been removed (lift-off). By this, a thin metallized film 4 is formed on the surface of the ceramic substrate 5. .

[0020] In the process (B) of roughening the polished ceramic substrate surface, the resist surface of (F) is The ceramics are placed in a diluted solution of the etching solution used in the etching (development) process. The surface of the ceramic substrate is roughened by immersing the substrate 5 in a liquid different from the etching liquid. When roughening, the components that are eroded are different, so it is necessary to control the degree of erosion by each liquid. In contrast, the same solution is required for the roughening step (B) and the etching step (F). By using the same ceramic substrate, the composition of the ceramic substrate is the same. Plates often consist of a ceramic main component and a grain boundary phase, and the ratio of these to corrosion varies depending on the process. is carried out in the same proportion.

[0021] In this case, if the substrate surface is the same, the more dilution there is, i.e., the thinner the diluted etching solution is, the more the etching rate will be. Conversely, if the dilution is small and the diluted etching solution is concentrated, the roughening effect will be small. If the dilution rate is increased, the etching effect becomes stronger and the roughening becomes larger. If there is, the roughening effect is small if the immersion time is short, and the etching effect is small if the immersion time is long. If the amount of dilution and the time of immersion are the same, the amount of dilution will be If the temperature of the etching solution is low, the roughening effect is small, and if the temperature is high, the etching effect is small. The fruits become larger and the roughening becomes greater.

[0022] The diluted etching solution used in the process (B) for roughening the ceramic substrate surface is a resist The etching solution used in the step (F) of etching (developing) the surface is 10% or more and 50% or less. % or less. Diluting the etching solution to less than 10% will cause roughening. The effect of the immersion is reduced, so the immersion time is longer and the manufacturing time increases. If the solution is diluted with , the roughening effect will be greater, and adjustments can be made by shortening the immersion time. In addition, the roughening reaction is an exothermic reaction. Therefore, adjusting the liquid temperature to a low temperature puts a strain on the process. If so, it is preferably 10% or more and 45% or less, more preferably 20% or more and 35% or less. be.

[0023] The time for immersing the ceramic substrate in the diluted etching solution should be between 20 and 240 seconds. If the immersion time is less than 20 seconds, it is difficult to sufficiently immerse the entire surface of the board or the entire lot. Furthermore, if the time exceeds 240 seconds, the time required to roughen the surface of the ceramic substrate becomes too long. Therefore, the manufacturing capacity is not increased by immersing the ceramic substrate in a diluted etching solution. The time is preferably 30 seconds or more and 180 seconds or less, more preferably 40 seconds or more and 120 seconds or less. be.

[0024] The temperature of the diluted etching solution in which the ceramic substrate is immersed is about room temperature, 10°C. The liquid temperature is set to less than 10°C to offset the exothermic reaction that occurs during immersion. Cooling is required to prevent this, making it difficult to control the liquid temperature. Also, if the temperature exceeds 40°C, reactions due to exothermic reactions may occur. The temperature of the solution must be adjusted to control the reaction rate, which places a burden on the process. The liquid temperature is preferably 15° C. or higher and 35° C. or lower, more preferably 20° C. or higher and 30° C. or lower. .

[0025] The process of manufacturing thin film metallization on a ceramic substrate involves applying a resist to the ceramic substrate. Regarding baking after application, the temperature is between 70℃ and 90℃, and the time is between 80 and 100 seconds. The purpose of baking is to dry the resist uniformly, but the temperature is lower than 70°C. If the time is shorter than 80 seconds, the resist will become liquid or semi-dried in some places, and the exposure The pattern cannot be exposed to light. On the other hand, if the temperature exceeds 90°C and the time is If the time exceeds 00 seconds, excessive thermal crosslinking of the resist will occur, and the pattern will be exposed to light in the same way. Furthermore, the baking temperature must be between 75°C and 85°C, and the baking time must be between 85 seconds and 95 seconds. Seconds or less is preferable.

[0026] The cumulative exposure dose after baking is 20 mJ / cm 2 More than 30mJ / cm 2 The following is the exposure The purpose is to expose the resist through a mask, causing the resist in the exposed areas to change in quality. The pattern shape is exposed to the ceramic substrate. The cumulative dose is 20 mJ / cm m 2 If it is smaller than this, there will be some areas where the pattern shape cannot be exposed sufficiently. 30mJ / cm 2 If it is larger than this, the exposure will reach the inside of the resist under the mask, This is because there are areas where the scanning accuracy is poor. Furthermore, the cumulative exposure dose after baking is 22mJ / cm 2 More than 28mJ / cm 2 It is preferable that:

[0027] After exposure, etching (development) is performed to remove the exposed part of the resist on the ceramic substrate. (F) The ceramic substrate with the exposed resist area was then ashed. After that, a thin metallized film is formed on the surface (G). The method for forming the thin metallized film is the vapor deposition method. The metal that forms the thin film metallization is, for example, an adhesion layer, a barrier layer, etc. The adhesive layer is used to bond the metal to the surface of the ceramic substrate. The barrier layer is a metal layer formed on the surface of the adhesive layer and a surface layer of titanium (Ti). This metal layer is formed between the two metals to prevent diffusion of metals between them. The surface layer is a metal layer formed to bond with other parts. Examples of metals include gold (Au), nickel (Ni), and copper (Cu). Then, the resist is peeled off (lift-off) to form a thin-film metallized pattern circuit. (H).

[0028] When applying thin-film metallization to the back side of the pattern circuit, it is necessary to perform ashing in the same manner as for the front side. If a bonding layer is formed after the thin metallization, it is recommended to use solder, etc. The bonding layer is formed by bonding the gold and tin (Au-Sn) solder layer. After forming the circuits using these thin film metallization and bonding layers, the product is cut to size. The cutting is performed by using a dicer or the like. After such cutting, the ceramic thin-film metallized substrate 3 is The chip-on-submount 13 is characterized in that a semiconductor element is mounted via a bonding layer. This is preferable.

[0029] FIG. 6 shows an example of a chip-on-submount according to an embodiment. In FIG. 6, 5 is a ceramic substrate. The chip is a semiconductor device. The chip-on-submount 13 is attached to the heat sink via a bonding layer. This is suitable for the semiconductor module 16 that is characterized by being mounted.

[0030] FIG. 7 shows an example of a semiconductor module (semiconductor device) according to the embodiment. In FIG. Wire bonding, 18 is the bonding layer that bonds the chip-on-submount and the heat sink 1 is the solder, 19 is a lead frame, and 20 is a heat sink.

[0031] In FIG. 7, the chip-on-submount 13 is mounted on the heat sink 20 via the bonding layer 18. The semiconductor element 15 and the thin film metallization 4 are electrically connected by wire bonding 17. In addition to the semiconductor element 15, the thin film metallization 4 and the lead are connected by wire bonding 17. The wire bonding 17 and the lead frame 19 are connected. The semiconductor device is mounted on the chip-on-submount 13 connected by the bonding layer 18 and the heat sink 20. The semiconductor module 16 is not limited to this structure. For example, wire bonding 17 and lead frame 19 are either one or the other. Also, the semiconductor element 15, the wire bonding 17 and the lead frame 1 A plurality of 9 may be provided in each semiconductor module 16.

[0032] The bonding layers 14 and 18 that bond the semiconductor element 15 and the heat sink 20 are Examples of solder include solder and brazing material. Lead-free solder is preferable. Solder has a melting point of 4 50℃ or less. Brazing material refers to materials with a melting point of over 450℃. High-temperature brazing filler metals are those that are heated to temperatures above 100℃. High-temperature brazing filler metals are mainly composed of silver (Ag). Can be obtained.

[0033] While semiconductor elements 15 are becoming smaller, the amount of heat generated by the chips is steadily increasing. Therefore, in the cut ceramic thin-film metallized substrate 3 on which the semiconductor element 15 is mounted, In order to improve the performance of semiconductor modules16, it is important to improve heat dissipation. In addition, a plurality of semiconductor elements 15 are mounted in the semiconductor module 16. If even one of the body elements 15 exceeds the intrinsic temperature of the element, the resistance will rise to the negative side temperature. This causes a thermal runaway in which the power flows in a concentrated manner, resulting in instant destruction. Therefore, it is effective to improve the heat dissipation. The body module 16 is used for a wide range of products, from laser diodes to LEDs for general lighting and headlamps. High power LEDs and deep ultraviolet LEDs (sterilizing lamps, resin curing lamps) that require high heat dissipation. Lasers and LEDs are becoming increasingly powerful. Improving the reliability of Module 16 directly translates into improved reliability for laser equipment and LED lighting. This will lead to improvement.

[0034] Next, the aluminum nitride of the ceramic thin-film metallized substrate 3 after cutting according to the embodiment is This section describes a method for forming a thin metallized pattern circuit on an aluminum nitride substrate. The manufacturing method of the pattern circuit formation on the substrate is not particularly limited as long as it has the above-mentioned configuration. Although not essential, the following methods can be used to obtain a good yield:

[0035] First, an aluminum nitride substrate is prepared. In particular, Considering the heat dissipation of the entire ceramic thin-film metallized substrate 3 after cutting, it is preferable to use aluminum nitride. The thermal conductivity of the substrate is preferably 170 W / m K or more. When conducting the thin-film metallized side that forms the through hole and the thin-film metallized side on the opposite side, An aluminum nitride substrate having through holes such as via holes is prepared. When the through holes are provided in the substrate, the through holes may be provided in advance in the stage of the molded body. A step of forming a through hole in the aluminum substrate may be performed. The step of forming the through hole may be performed by a laser. The surface of these aluminum nitride substrates is processed by machining, drilling, etc. The aluminum nitride is lapped using fixed or loose abrasive grains. The arithmetic mean roughness of the substrate surface is generally 0.1 μm or less.

[0036] The etching solution used in the etching process described below is diluted to a specified ratio and placed in a container and kept at a constant temperature. The etching solution contains tetramethylammonium hydroxide. For example, AD-10 manufactured by Tama Chemical Industry Co., Ltd. and S manufactured by Tokuyama Corporation are used. D-1, etc. The aluminum nitride substrate is placed in a cassette of fluororesin and diluted etched. The aluminum nitride substrate is immersed in the etching solution, and the diluted etching solution reacts with the entire surface of the aluminum nitride substrate by shaking or stirring. After the specified time of immersion, the sample is removed from the container, washed with water and dried.

[0037] A resist 9 is applied to the aluminum nitride substrate. A coater or the like is used for the application. The resist is a phenolic resin-based photoresist. The aluminum nitride substrate is baked. A dedicated heating device may be used for baking, or a If the printer is equipped with a baking function, you can bake it as is. The material is heated at a given temperature and time and then cooled.

[0038] Next, the baked aluminum nitride substrate is placed in an exposure device and exposed to light. By irradiating ultraviolet light or the like through the mask 10 with the turns, the unmasked The desired portion is exposed to light. The baking is performed by holding the portion at a specified heating temperature for a specified period of time, and then cooling the portion.

[0039] Next, the resist 9 other than the exposed resist 11 is removed by etching (development). A thin metallization 12 is applied to the aluminum nitride substrate with the exposed resist 11. Metallization can be done by deposition or sputtering. The exposed resist 11 is peeled off (lifted off) from the aluminum substrate to form a pattern with a thin metallization film 4. A turn circuit is formed.

[0040] Next, a thin film metallization was applied to the rear surface of the aluminum nitride substrate (the surface opposite to the surface where the thin film metallization was applied). The back side may be patterned in the same way as the front side, or may be left without a circuit. A thin metallized layer may be formed on the entire surface. The thin film metallization processes on the front and back surfaces may be performed simultaneously or alternately. You can go.

[0041] When a bonding layer 14 such as solder is formed on the surface of the thin metallization by lithography, In the same way as for forming a thin film, resist coating, exposure, etching (development), solder film formation, and peeling are performed. The solder is formed by the lift-off process. The solder is Au-Sn solder, Au-Si (silicon) solder, In addition to forming a bonding layer by lithography, there are other methods to improve the bonding property. It is possible to plate the entire surface. Examples include Au plating on a Pd base.

[0042] Next, the aluminum nitride substrate is cut into product sizes. The aluminum nitride substrate is cut into the product shape. Next, a step of bonding the semiconductor element 15 and the like is performed. A bonding layer is provided at the portion where the two are to be bonded. The bonding layer is preferably made of solder or brazing material. A semiconductor element 15 is then provided thereon.

[0043] Next, the aluminum nitride substrate with the semiconductor element 15 bonded thereto is bonded to a semiconductor module. The heat sink 20 is bonded via a bonding layer. If necessary, a wire is also bonded. The pattern circuit made of thin film metallization 4 is connected to the lead frame 19 by bonding 17. The semiconductor element 15 and the thin film metallization 4 are connected by wire bonding 17. The semiconductor element 15, the lead frame 19, the wire board 19, and the pattern circuit are bonded. The necessary number of bondings 17 shall be provided.

[0044] In the above, a thin metallization film 6 is formed on the back surface of the pattern circuit of the aluminum nitride substrate. The heat sink 20 is then bonded to the heat sink 20 via a bonding layer such as solder in the above-mentioned state. However, the present invention is not limited to this. For example, a thin film is provided on the back of the pattern circuit. If the aluminum nitride substrate does not have the metallized film 6, the heat sink 20 is attached with adhesive. etc. to join.

[0045] (Examples 1 to 7, Comparative Examples 1 to 6) A sintered aluminum nitride substrate with a diameter of 100 mm and a thickness of 0.3 mm (thermal conductivity 240 W / The substrate surface was heated to a temperature of 0.02 to 0.03 μm. Both sides of aluminum oxide were polished. % tetramethylammonium hydroxide and non-ionic surfactant) The mixture was then immersed as shown in Table 1.

[0046] [Table 1]

[0047] As can be seen from Table 1, in Examples 1 to 7, the dilution concentration of the etching solution, aluminum nitride The immersion time and the temperature of the diluted etching solution were within the preferred range. , their values ​​fell outside the preferred range.

[0048] Next, a spin coater was used on the aluminum nitride substrate at a rotation speed of 200 rpm for 10 seconds. 3cm under the conditions of 1000rpm for 15 seconds, 2000rpm for 15 seconds, and 200rpm for 2 seconds 3 The resist was titrated to coat the entire surface of the substrate with an ultraviolet-curable resist. After coating, the substrate was baked using a spin coater. Next, the substrate was cut as shown in Figs. 1 and 2. The final product size is 0.9mm x 0.9mm, and two patterns of 0.6mm x 0.3mm are A glass mask was prepared so that the pattern of the light was exposed with a spacing of 0.1 mm between the light-emitting diodes. The aluminum nitride substrate and the glass mask are placed in the exposure machine (parallel light mask aligner). Next, the aluminum nitride substrate was placed on the spin coater and exposed. The back side (opposite side of the pattern circuit) was baked. Next, the aluminum nitride substrate was placed in the exposure machine. I set it up and took the exposure.

[0049] Next, the exposed aluminum nitride substrate is placed in a solvent-resistant cassette and etched in a thermostatic chamber. The etching was performed by shaking in a etching solution (AD-10) at 25°C for 150 seconds. After washing the aluminum nitride substrate with pure water, it was dried in a spin dryer at 3000 rpm for 3 minutes. The mixture was dried by rotating for 10 min.

[0050] Next, the aluminum nitride substrate was subjected to ashing using an asher device. Ashing conditions The deposition was performed for 1 minute at RF power of 400 W and oxygen amount of 500 ccm. The order is titanium (Ti) 0.1μm, platinum (Pt) 0.2μm, and gold (Au) 0.3μm. Next, the aluminum nitride substrate was coated with three layers of metal by vapor deposition. The cassette was placed in a thermostatic chamber and swung at 50°C for 45 minutes to remove the resist. The resist stripper was an alkaline resist stripper based on N-methyl-2-pyrrolidone. The aluminum nitride substrate from which the resist had been removed was washed in pure water. The aluminum substrate was cut with a dicer.

[0051] The products cut with a dicer were analyzed using spectroscopic ellipsometry to measure the 700 nm diameter of the gold surface. The surface reflectance (%) of the nominal was measured.

[0052] The surface visibility of each cut product was checked using a microscope. In order to automatically recognize the corners of the pattern when mounting the element, the aluminum nitride base If the gold surface appears as black dots due to the surface shape of the plate, the pattern matching rate will decrease. Therefore, when black spots that affect the pattern matching rate were observed, the image was judged to be visually unrecognizable.

[0053] The adhesion state of the thin metallization was also checked using a microscope. The product shape that occurred was determined to be defective due to peeling.

[0054] In addition, the aluminum nitride metallized thin film substrate 100 after cutting according to the example and the comparative example A laser die, a semiconductor element, is soldered to one part of the circuit pattern by Au-Sn solder. The electrode element was bonded to fabricate a chip-on-submount.

[0055] The heat sink part of a copper stem part with a heat sink part and two lead terminal parts The chip-on-submount was soldered to the laser diode element and the pattern circuit. The wires and lead terminals were then bonded to the window cap. We then combined these to create a semiconductor module for a laser device.

[0056] The semiconductor module is subjected to a high-temperature continuous current test at 100°C for 200 hours. The laser characteristics of the modules were checked. The modules whose laser characteristics deteriorated after 200 hours were The module failures were of two types: electrical failure and thermal runaway failure. A power failure is a defect in which a semiconductor element is damaged due to an electrical short circuit occurring between pattern circuits. Thermal runaway failure occurs when the heat generated by the semiconductor is not transferred sufficiently to the board, causing the semiconductor element to break down. These two types of defects are classified as module defects. I untagged.

[0057] The substrate reflectance, substrate defect occurrence rate, and module defect occurrence rate for the examples and comparative examples are shown in Table 2. As shown in.

[0058] [Table 2]

[0059] As can be seen from the surface reflectance in Table 2, the aluminum nitride thin film metallized substrate according to the embodiment The surface reflectance of the aluminum nitride substrate was good, at over 50%. The roughened surface caused by etching is not too sensitive and does not affect the thin metallization. This is because of the high reflectance.

[0060] In contrast, in Comparative Examples 2, 4, and 6, the surface reflectance was a low value of less than 50%. The excessive etching conditions caused the roughening of the aluminum nitride substrate, which resulted in the roughened surface. This is because the effect of the surface appears even on the thin metallized surface.

[0061] In addition, as can be seen from the substrate defects in Table 2, the aluminum nitride thin film metallization according to the embodiment The substrate had no visible defects or a low defect rate. This is because the surface effects do not appear until the thin film metallization.

[0062] In contrast, many poor visibility occurred in Comparative Examples 2, 4, and 6. Aluminum nitride substrate As a result, the roughened surface affects the thin metallized surface, resulting in a gold surface. This is because black dot defects occurred in the

[0063] In addition, as can be seen from the substrate defects in Table 2, the aluminum nitride thin film metallization according to the embodiment The substrate had little or no peeling defects. The adhesion strength of thin metallization was improved by roughening the surface of aluminum nitride substrate. This is why.

[0064] In contrast, many peeling defects occurred in Comparative Examples 1, 3, and 5. Therefore, the surface of the aluminum nitride substrate is not sufficiently roughened, and the necessary anchor effect cannot be obtained. This is because the joint strength was weak in some areas.

[0065] In addition, as can be seen from the module failures in Table 2, the aluminum nitride thin film meta according to the embodiment The rise substrate did not experience any electrical continuity failure. The surface roughness of the aluminum nitride substrate became large. This is because the distance between the patterns was secured and the insulation was kept appropriate.

[0066] In contrast, in Comparative Examples 2, 4, and 6, electrical continuity failure occurred. Aluminum nitride substrate surface The roughness of the pattern has increased, causing unevenness in the pattern shape, which causes current leakage from the convex parts. In addition, the resist layer does not crosslink sufficiently, and the insulating parts between the patterns are also covered with thin-film metallization. Possible causes include penetration of the

[0067] In addition, as can be seen from the module failures in Table 2, the aluminum nitride thin film meta according to the embodiment The aluminum nitride substrate and the thin metallization did not experience any thermal runaway failure. Because of the excellent bonding between the substrates, it is suitable for semiconductor devices, solder, thin film metallization, and aluminum nitride-based This is because the heat generated by the semiconductor elements was not affected by the operation of the board. do.

[0068] In contrast, in Comparative Examples 1, 3, and 5, thermal runaway failure occurred. No abnormalities were found in the solder joint layer between the conductive element and the thin metallization, but the thin metallization Voids were observed between the rise and the aluminum nitride substrate. This caused the thermal runaway failure. This is because the voids created in the material prevented sufficient heat dissipation. The cause of these voids is However, the surface of the aluminum nitride substrate was not sufficiently roughened, so that the aluminum nitride substrate and This is because there were areas where the bonding strength between the thin metallized films was low, causing voids.

[0069] Although several embodiments of the present invention have been illustrated above, these embodiments are presented as examples. These novel embodiments are provided for illustrative purposes only and are not intended to limit the scope of the invention. , and can be implemented in various other forms, without departing from the spirit of the invention. Various omissions, substitutions, modifications, etc. can be made. These embodiments and their modifications are The scope of the invention and its equivalents as described in the claims are included in the scope and spirit of the invention. In addition, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0070] 1…Ceramic thin-film metallized substrate before cutting 2. Ceramic thin-film metallized substrate 3…Ceramic thin-film metallized substrate after cutting 4, 6, 12...Thin film metallization 5…Ceramics substrate 7…Ceramic substrate surface 8…Roughened ceramic substrate surface 9. Resist 10. Mask 11... Exposed resist 13…Chip-on-submount 14, 18...Joining layer 15...Semiconductor element 16...Semiconductor module 17…Wire bonding 19…Lead frame 20…Heat sink

Claims

1. A ceramic circuit is formed using an etching solution containing tetramethylammonium hydroxide. In the method for manufacturing a thin film etching substrate, the ceramic is aluminum nitride. the law of nature, a) Dilute the etching solution to a concentration of tetramethylammonium hydroxide of 0.24% or less. preparing an etching solution diluted to 1.2% or less; b) roughening the surface of the ceramic substrate with the diluted etching solution; c) The resist layer formed on the surface of the roughened ceramic substrate is etched with the etching solution. An etching step; d) forming a thin film metallization on the etched ceramic substrate; e) lifting off the resist layer to form the circuit; A method for manufacturing a ceramic thin-film metallized substrate, comprising:

2. The temperature of the diluted etching solution is 10° C. or more and 40° C. or less, and the immersion time is 20 2. The ceramic thin film metallization method according to claim 1, wherein the heat treatment is performed for 20 seconds or more and 240 seconds or less. A method for manufacturing a substrate.

3. The thermal conductivity of the ceramic substrate is 170 W / m·K or more, and the arithmetic mean roughness of the surface is The ceramic thin film according to claim 1 or 2, characterized in that the thickness is 0.1 μm or less. A method for manufacturing a film metallized substrate.

4. 10. The thin film metallization is titanium, platinum, or gold. Item 3. A method for producing a ceramic thin film metallized substrate according to item 2.

5. The reflectance of the gold surface of the thin film metallization at 700 nm is 50% or more. The method for producing a ceramic thin film metallized substrate according to claim 4.

6. Chip-on-sub-mount with adhesive layer on pattern circuit of ceramic thin-film metallized substrate The ceramic obtained by the method according to claim 1 or 2 is used in the method for producing a ceramic. A chip-off method comprising the step of forming a bonding layer on a mixed thin-film metallized substrate. A method for manufacturing a submount.

7. It is preferable that the bonding layer in the method for producing the chip-on-submount is a gold-tin solder. The method for manufacturing a chip-on-submount according to claim 6 .

8. A method for manufacturing a semiconductor module in which a semiconductor element is mounted on a chip-on-submount A semiconductor element is mounted on the chip-on-submount obtained by the manufacturing method according to claim 7.

13. A method for manufacturing a semiconductor module, comprising the steps of:

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