CN101928156B - Ceramic substrate and manufacturing method thereof - Google Patents

Abstract

The invention provides a ceramic substrate and a method for manufacturing the same. The ceramic substrate comprises a ceramic main body; and a flat buffer layer disposed on the ceramic main body for maintaining the warpage of the ceramic substrate less than 0.5%, wherein the ceramic main body has a coefficient of thermal expansion CTE_mCoefficient of thermal expansion CTE with the flat buffer layer_pSatisfies the relation (1) | CTE_m-CTE_p|≤3×10^-6The relation (1)/. degree.C.

Description

Ceramic substrate and manufacturing method thereof

technical field

The invention relates to a ceramic substrate, in particular to a ceramic substrate with a flat surface.

Background technique

Ceramic materials have been widely used in communications, computers, medicine, and even military applications in recent years due to their good mechanical, thermal conductivity, and high temperature resistance, especially excellent dielectric properties. Among them, ceramic substrates made of ceramic materials can be further applied to the preparation process of semiconductors, storage elements, light-emitting diodes, and optoelectronic products, such as processing various micro-electromechanical devices on the surface of ceramic substrates or as solar cells, light-emitting diodes, etc. The carrier substrate is one of the very popular applications at present.

However, one of the disadvantages of traditional ceramic materials is that their surface roughness is too high, and there will be many pits of different sizes on the surface. This phenomenon will cause poor flatness on the surface of ceramic substrates made of ceramic materials. In particular, When the surface of the ceramic substrate is processed by the semiconductor preparation process, or the film layer required for solar cells or light-emitting diodes is formed on it, the high surface roughness average of the ceramic substrate often leads to a significant decrease in the yield of the preparation process. reduce.

In order to solve the problem of excessive surface roughness of ceramic substrates, the currently used methods are: general mechanical polishing (mechanical polishing), chemical mechanical planarization (CMP), chemical etching, coated glass (spin -on glass) method, or boron phosphorosilicate glass (Boron Phosphorous Silicated Glass, BPSG) high temperature reflow method. Generally speaking, the mechanical grinding method is used to improve the flatness of the surface of the ceramic substrate. Due to the relationship between the ceramic material itself, new pits will be generated during the mechanical grinding process; the chemical mechanical grinding method, in addition to the chemical slurry used is relatively The substrate itself is quite expensive, the preparation process is complicated and difficult to control, and it lacks an effective chemical-mechanical grinding end point detection system, and the grinding process is easy to introduce pollutants; the B ₂ required for the preparation process of borophosphosilicate glass (BPSG) Both H ₆ and PH ₃ are toxic gases, and are only suitable for isolation before metallization; as for the coating glass preparation process, it can only provide local flatness and adhesion to ceramic substrates. ) is not good, and there is still the problem of residual solvent outgassing (outgassing). To sum up, the known ceramic substrate flattening methods not only require considerable cost, but also are limited by the thermal expansion coefficient of the original substrate, and cannot be compatible with high-temperature preparation processes. limits.

In order to solve the above problems, vitrified (Vitreous) substances are used as coatings (or buffer layers) of certain ceramic substrates to improve the surface properties of ceramic substrates (chemical resistance, impervious to liquid and gas, relatively Smooth, wear-resistant, and increased mechanical strength), thereby increasing its practicality and increasing added value. A higher manufacturing process temperature can make the device have better bonding and better electrical performance, so the requirements for the coefficient of thermal expansion (coefficient of thermal expansion, CTE) of the ceramic substrate are also getting higher and higher. For example, optical components that include ceramic substrates, if the ceramic substrate has a high thermal expansion coefficient, the difference in thermal expansion coefficient between the ceramic substrate and other optical materials (glass or quartz) can cause stress (causing deformation or distortion) , resulting in a change in the optical properties originally set; in addition, when a ceramic substrate is used as a light-emitting diode (LED) or a solar cell (solar cell) carrier substrate, the excessive difference in thermal expansion coefficient will cause the film deposited on it later Layers or components produce warping or arching, and their rough surfaces will cause components to fail.

Therefore, designing a ceramic substrate with a lower surface roughness and a better overall thermal expansion coefficient to solve the above-mentioned problems is actually the focus of research in ceramic material technology.

Contents of the invention

The purpose of the present invention is to provide a ceramic substrate with relatively low surface roughness and relatively matched overall thermal expansion coefficient.

To sum up, the present invention proposes a ceramic substrate, which has a ceramic body and a flat buffer layer formed thereon, and the flat buffer layer can adjust its thermal expansion coefficient by changing its composition to match that of a substrate with a lower thermal expansion coefficient. Ceramic body. In addition to reducing the surface roughness of the ceramic substrate through the flat buffer layer, since the thermal expansion coefficient of the flat buffer layer can be adjusted to be close to the thermal expansion coefficient of the subsequent film layer or element, it can ease the residue caused by the difference in thermal expansion coefficient. stress. In addition, the flat buffer layer can also serve as a barrier layer to prevent impurities from diffusing to subsequent film layers or components.

The ceramic substrate of the present invention comprises a ceramic body; and a planar buffer layer (planar buffer layer, PBL) is disposed on the ceramic body, wherein the planar buffer layer is composed of the following components: 30-95 parts by weight of silicon oxide ; 1-40 parts by weight of alumina; 2-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides; and 0.1-46 parts by weight of zirconium dioxide (ZrO ₂ ), zinc oxide (ZnO), titanium dioxide ( TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), tungsten oxide (WO _x ), tin oxide (SnO ₂ ) and germanium dioxide (GeO ₂ ), where x is 2 or 3 ; wherein in order to maintain the warpage of the ceramic substrate<0.5%, the coefficient of thermal expansion CTE _m of the ceramic body and the coefficient of thermal expansion CTE _p of the flat buffer layer conform to the relationship (1)

|CTE _m -CTE _p |≤3×10 ^-6 /°C Relational formula (1).

The advantage of the present invention is that it can provide a flat buffer layer with an adjustable thermal expansion coefficient to be formed on the surface of the ceramic body with a lower thermal expansion coefficient. Since the flat buffer layer can achieve the purpose of regulating the thermal expansion coefficient by changing the composition, the present invention The flat buffer layer has a coefficient of thermal expansion of less than 7×10 ^-6 /°C, more preferably between 2×10 ^-6 /°C and 7×10 ^-6 /°C, and it is very suitable that the coefficient of thermal expansion is not greater than 10×10 ^-6 /°C ceramic body. In addition, the formed ceramic substrate is very suitable for application in solar cells, light emitting diodes, IC packaging, micro-electromechanical systems, electronic devices, or thin film transistors.

Through several examples and comparative examples below, to further illustrate the methods, features and advantages of the present invention, but not intended to limit the scope of the present invention, the scope of the present invention should be based on the scope of the appended claims .

Detailed ways

The invention provides a ceramic substrate. By changing the thermal expansion coefficient of the coating, the thermal expansion coefficient of the coating is similar to that of the bearing element, so as to slow down the thermal stress caused by the difference in the thermal expansion coefficient between the ceramic body and the subsequent film, and avoid the defects caused by the subsequent preparation process. , so it is called a planar buffer layer (PBL), which is used to improve the above problems, and can be applied to solar cells, light-emitting diodes, IC packaging, micro-electromechanical, electronic devices, or thin-film transistors. Generally, the thermal expansion coefficient of the ceramic body is usually high. If the thermal expansion coefficient of the coating is too low, the two will easily warp during the bonding process. Through experiments and calculation results, we found that when |CTE _m -CTE _p |＞3× 10 ^-6 /°C, no matter which PBL material is used, the warpage of the substrate will still be greater than 0.5% under different thicknesses, which will cause troubles in the subsequent preparation process. implementation structure.

Referring to Table 1, it shows the thermal expansion coefficient range (4.9～9.0) of the coating composition disclosed by the known technology as the ceramic main body, and its low thermal expansion coefficient part (<7.0) has added alkali metal group, lead oxide or Iron oxide, which has a low softening temperature, is easy to combine with the ceramic body, and this type of element is easy to diffuse into the subsequent film during the high-temperature preparation process, resulting in attenuation of component performance:

Table 1

known technology ingredients Coefficient of thermal expansion (x10 ^-6 /°C) CA820980 13-22% PbO, 5-15% Bi ₂ O ₃ , 0.5-2% TiO ₂ , 0.5-2% K ₂ O, 0.25-1% As ₂ O ₃ >5.8 JP5654253  ＜10%PbO,＜2%ZnO, 0.5～20SrO ＞5.5 JP5988337 3~8% B ₂ O ₃ , 20~28% (CaO+SrO+BaO), <6% (MgO, ZnO, TiO ₂ ) 7.0～9.0 JP60131881 0.5-7% B ₂ O ₃ , 1-13% BaO, 3-20% CaO, 0.5-25% SrO, 0.1-5% Y ₂ O ₃ 5.1～6.7 JP60155550 <7% B ₂ O ₃ , 1-13% BaO, 2-20CaO, <2% MgO, 0.5-5% La ₂ O ₃ , <25% SrO, <5% Y ₂ O ₃ 5.2～6.7 JP6296344 1~15% BaO, 10~25CaO, <2% MgO, 0~15% SrO, 0.5~5% P ₂ O ₅ 5.9～7.1 US4634634 <8mol% B ₂ O ₃ , 15.5～28mol% BaO, <10mol% CaO, <2mol% MgO, <10mol% others (<10%SrO...) 4.9～8.7 JP1188443 1~7% B ₂ O ₃ , 23~35% BaO, 1~20CaO, 1~5% ZnO 6.3～7.3 JP375237 3-25% BaO, 5-15% CaO, 0.5-5% MgO, 5-30% SrO, 0-5% La ₂ O ₃ 6.5～6.8 JP3164444 0.5-5% B ₂ O ₃ , 5-25% BaO, 2-15CaO, <1% MgO, 2-30% SrO, 0.5-10% ZrO ₂ , <3% ZnO 5.5～6.3 JP3183639 1~20% BaO, 5~25% CaO, 0~5% MgO, 1~20% SrO, 2~6% ZrO ₂ 5.6～7.0

It is known that when a coating layer of a ceramic substrate body is formed on a ceramic substrate body with a low thermal expansion coefficient (for example, a ceramic material with a thermal expansion coefficient close to glass (CTE: 2.6 to 3.3×10 ^-6 /°C)), The difference in its thermal expansion coefficient will cause hidden dangers (distortion, cracking, deformation, etc.) to its subsequent application.

A ceramic substrate provided by the present invention includes: a ceramic body; and a flat buffer layer disposed on the ceramic body, wherein the coefficient of thermal expansion CTE _m of the ceramic body and the coefficient of thermal expansion CTE _p of the flat buffer layer conform to the relational expression (1)

|CTE _m -CTE _p |≤3×10 ^-6 /℃ Relational formula (1);

Wherein the warpage of the ceramic substrate is less than 0.5%; the softening temperature of the ceramic body is not less than 800°C; the softening temperature of the flat buffer layer is not less than 500°C.

The ceramic substrate of the present invention includes: a planar buffer layer (PBL) disposed on the ceramic body. The flat buffer layer is composed of the following components: 30-95 parts by weight of silicon oxide; 1-40 parts by weight of aluminum oxide; and 2-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides. The composition of the flat buffer layer of the above-mentioned ceramic substrate may further include: 0.1-46 parts by weight of zirconium dioxide (ZrO ₂ ), zinc oxide (ZnO), titanium dioxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), oxide Lanthanum (La ₂ O ₃ ), tungsten oxide (WO _x ), tin oxide (SnO ₂ ) and germanium dioxide (GeO ₂ ), wherein x is 2 or 3. Wherein the coefficient of thermal expansion CTE _m of the ceramic body and the coefficient of thermal expansion CTE _p of the flat buffer layer conform to the relational formula (1)

|CTE _m -CTE _p |≤3×10 ^-6 /°C Relational formula (1).

The thickness of the flat buffer layer is not greater than 200 μm, preferably between 5˜150 μm. It is worth noting that the planar buffer layer of the present invention does not contain alkali metal oxides (for example: Na ₂ O, or K ₂ O), so as to avoid diffusion of alkali gold atoms during processing; in addition , the flat buffer layer of the present invention does not contain lead oxide to meet the safety requirements. In order to increase the high-temperature stability of the ceramic substrate, boron oxide, phosphorus oxide and alkaline earth oxides of 2-35 parts by weight in the composition of the flat buffer layer have a higher softening temperature, and when this ratio is less than 1.56, zirconium dioxide (ZrO ₂ ), zinc oxide (ZnO), titanium dioxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), tungsten oxide (WO _x ), tin oxide (SnO ₂ ) and germanium dioxide (GeO ₂ ) are among the ingredients to achieve a higher softening temperature. In addition, the ratio of boron oxide to silicon oxide can also be adjusted. When it is greater than 0.182, it has a higher softening temperature. When the ratio is less than 0.182, zirconium dioxide (ZrO ₂ ), zinc oxide (ZnO ), titanium dioxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), tungsten oxide (WO _x ), tin oxide (SnO ₂ ) and germanium dioxide (GeO ₂ ) among the ingredients , reaching a higher softening temperature.

The coefficient of thermal expansion of the ceramic main body may not be greater than 10×10 ^-6 /°C, and the coefficient of thermal expansion of the flat buffer layer is less than 7×10 ^-6 /°C, or even between 2×10 ^-6 /°C and 7×10 ^-6 /°C, according to other embodiments of the present invention, the thermal expansion coefficient of the flat buffer layer may also be between 2×10 ^{-6 /} °C and 4.8× ^{10 -6} /°C, and the surface of the ceramic substrate covered by the flat buffer layer has an average The roughness is less than 150nm. The ceramic body may include graphite, silicon nitride, silicon carbide, silicon oxide, aluminum oxide, mullite, granite, marble, or a mixture thereof, and the flat buffer layer includes silicon oxide and oxide The total weight percentage W1 of aluminum and the total weight percentage W2 of graphite, silicon nitride, silicon carbide, silicon oxide, aluminum oxide, mullite, granite, and marble contained in the ceramic body conform to the relational formula (2)

0.5≤W1/W2≤2 Relational formula (2).

The softening temperature of the ceramic body used in the present invention may not be less than 800°C, and the softening point of the flat buffer layer may not be less than 500°C.

In the ceramic substrate of the present invention, the flat buffer layer can also be composed of the following components: 30-75 parts by weight of silicon oxide; 5-40 parts by weight of aluminum oxide; and 0.1-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth family of oxides. The composition of the flat buffer layer of the above-mentioned ceramic substrate may further include: 25-46 parts by weight of zirconium dioxide, zinc oxide, titanium dioxide, yttrium oxide, lanthanum oxide, tungsten oxide WO _x , tin oxide and germanium dioxide, where x is 2 or 3. The average surface roughness of the ceramic substrate is less than 100nm. The thickness of the flat buffer layer is not greater than 150 μm.

In the ceramic substrate of the present invention, the flat buffer layer may also be composed of the following components: 76-95 parts by weight of silicon oxide; 1-25 parts by weight of aluminum oxide; and 4-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth family of oxides. The composition of the flat buffer layer of the above-mentioned ceramic substrate may further include: 0.1-40 parts by weight of zirconium dioxide, zinc oxide, titanium dioxide, yttrium oxide, lanthanum oxide, tungsten oxide WO _x , tin oxide and germanium dioxide, wherein x is 2 or 3. The average surface roughness of the ceramic substrate is less than 100nm. Wherein the thickness of the flat buffer layer is not greater than 150 μm.

Ceramic substrate of the present invention, its flat buffer layer also can be made up of following composition:

30-85 parts by weight of silicon oxide; 1-40 parts by weight of aluminum oxide; and 2-30 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides. The composition of the flat buffer layer of the above-mentioned ceramic substrate may further include: 0.1-50 parts by weight of zirconium dioxide (ZrO ₂ ), zinc oxide (ZnO), titanium dioxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), oxide Lanthanum (La ₂ O ₃ ), tungsten oxide (WO _x ), tin oxide (SnO ₂ ) and germanium dioxide (GeO ₂ ), where x is 2 or 3.

Ceramic substrate of the present invention, its flat buffer layer also can be made up of following composition:

30-55 parts by weight of silicon oxide; 8-30 parts by weight of aluminum oxide; and 7-33 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides. The composition of the flat buffer layer of the above-mentioned ceramic substrate may further include: 0.1-46 parts by weight of zirconium dioxide (ZrO ₂ ), zinc oxide (ZnO), titanium dioxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), oxide Lanthanum (La ₂ O ₃ ), tungsten oxide (WO _x ), tin oxide (SnO ₂ ) and germanium dioxide (GeO ₂ ), where x is 2 or 3.

According to the ceramic substrate of the present invention, its flat buffer layer may also consist of the following components:

56-77 parts by weight of silicon oxide; 10-30 parts by weight of aluminum oxide; and 12-22 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides. The composition of the flat buffer layer of the above-mentioned ceramic substrate may further include: 0.1-10 parts by weight of zirconium dioxide (ZrO ₂ ), zinc oxide (ZnO), titanium dioxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), oxide Lanthanum (La ₂ O ₃ ), tungsten oxide (WO _x ), tin oxide (SnO ₂ ) and germanium dioxide (GeO ₂ ), where x is 2 or 3.

In addition, according to the ceramic substrate described in other preferred embodiments of the present invention, the flat buffer layer is composed of the following components:

78-95 parts by weight of silicon oxide; 1-10 parts by weight of aluminum oxide; and 15-17 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides. The composition of the flat buffer layer of the above-mentioned ceramic substrate may further include: 0.1-5 parts by weight of zirconium dioxide (ZrO ₂ ), zinc oxide (ZnO), titanium dioxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), oxide Lanthanum (La ₂ O ₃ ), tungsten oxide (WO _x ), tin oxide (SnO ₂ ) and germanium dioxide (GeO ₂ ), where x is 2 or 3.

Hereinafter, several embodiments are listed to illustrate the planar buffer layer and the ceramic substrate comprising the same according to the present invention.

Preparation of Flat Buffer Layer Composition

Example 1

According to the ingredients and compositions shown in Table 2, planar buffer layers 1-33 (thickness 20 μm) were prepared respectively.

Table 2

Composition of flat buffer layer SiO ₂ (wt%) Al ₂ O ₃ (wt%) B ₂ O ₃ (wt%) P ₂ O ₅ (wt%) CaO(wt%) MgO(wt%) BaO(wt%) SrO(wt%) ZnO(wt%) ZrO ₂ (wt%) TiO ₂ (wt%) GeO ₂ (wt%) Y ₂ O ₃ (wt%) La ₂ O ₃ (wt%) WOx(wt%) SnO ₂ (wt%) 1 34 8 6 0 2 2 2 0 0 0 0 0 0 44 0 2 2 40 10 7 0 0 0 0 0 0 1 0 0 1 41 0 0 3 41 12 8 0 5 4 0 2 0 0 0 28 0 0 0 0 4 45 17 7 5 8 0 8 0 2 3 2 0 3 0 0 0

5 45 11 8 0 0 5 0 0 0 0 0 0 0 31 0 0 6 46 11 8 0 0 5 0 0 0 0 0 0 30 0 0 0 7 47 37 2 2 6 6 0 0 0 0 0 0 0 0 0 0 8 47 36 5 0 12 0 0 0 0 0 0 0 0 0 0 0 9 50 19 13 0 10 5 0 0 0 2 0 1 0 0 0 0 10 50 12 8 1 0 5 0 0 0 0 0 0 twenty four 0 0 0 11 51 twenty four 0 0 10 0 0 0 0 0 0 15 0 0 0 0 12 52 15 4 0 0 19 10 0 0 0 0 0 0 0 0 0 13 52 15 4 0 15 3 6 0 0 0 0 0 0 0 5 0 14 53 13 9 0 0 8 0 0 0 0 0 0 0 18 0 0 15 53 12 8 0 11 0 0 0 0 0 0 15 0 0 0 0 16 53 18 4 0 15 4 5 0 1 0 0 0 0 0 0 0 17 54 18 5 3 0 5 15 0 0 0 0 0 0 0 0 0 18 54 15 4 0 15 3 5 0 0 3 1 0 0 0 0 0 19 54 15 4 0 15 3 5 0 0 0 1 0 0 0 3 0 20 54 28 5 0 0 13 0 0 0 0 0 0 0 0 0 0 twenty one 56 29 12 0 0 1 0 0 2 0 0 0 0 0 0 0 twenty two 60 15 10 0 0 7 0 0 8 0 0 0 0 0 0 0 twenty three 62 15 0 0 0 13 0 0 10 0 0 0 0 0 0 0 twenty four 62 16 4 0 10 2 0 6 0 0 0 0 0 0 0 0 25 63 15 10 0 0 12 0 0 0 0 0 0 0 0 0 0 26 64 17 3 0 8 7 0 0 0 0 0 0 0 0 0 1 27 70 15 0 0 15 0 0 0 0 0 0 0 0 0 0 0 28 70 12.5 0 0 17.5 0 0 0 0 0 0 0 0 0 0 0 29 73 17 6 0 0 4 0 0 0 0 0 0 0 0 0 0 30 77 11 7 3 1 0 1 0 0 0 0 0 0 0 0 0

31 78 7 13 0 0 1 0 1 0 0 0 0 0 0 0 0 32 79 4 3 1 0 0 12 1 0 0 0 0 0 0 0 0 33 84 1 11 4 0 0 0 0 0 0 0 0 0 0 0 0

Flat Buffer Property Measurements

Example 2

For the flat buffer layer 1-33 prepared in Example 1, measure its softening temperature and its coefficient of thermal expansion (CTE) in the temperature range between 20°C and 300°C, please refer to Table 3:

table 3

flat buffer layer Softening temperature (℃) Coefficient of thermal expansion (10 ^-6 /℃) 1 897 2.9 2 925 3.1 3 827 4.4 4 741 3.8 5 866 5.8 6 875 5.4 7 906 4.3 8 892 5.1 9 800 5.3 10 861 1.8 11 894 3.7 12 732 2.8 13 736 4.2 14 822 4.3 15 840 4.2 16 725 3.6 17 718 4.0 18 736 3.9 19 736 3.8

20 876 5.2 twenty one 861 3.7 twenty two 828 3.3 twenty three 855 5.8 twenty four 745 2.6 25 839 4.5 26 756 2.8 27 936 4.3 28 903 4.7 29 942 3.4 30 985 3.9 31 590 2.7 32 850 6.6 33 819 2.6

As shown in Table 3, the thermal expansion coefficient of the flat buffer layer obtained in the embodiment of the present invention can be controlled by a specific composition, and the softening temperature of these flat buffer layers is not less than 550°C.

Surface Roughness Measurement of Ceramic Substrates

Example 3

Take a ceramic substrate as the ceramic body of the subsequent ceramic substrate. Please refer to Table 4 for the properties of the ceramic substrate used:

Table 4

ingredients Ra(nm) CTE(10 ^-6 /℃) Warpage(%) Al ₂ O ₃ (ceramic body A) 288.3 8 0.15 Mullite (ceramic body B) 447.6 4 0.21

Next, according to the flat buffer layer composition 1, 5, 7, 10, 16, 21, 26, 32, and 33 described in Table 1, a flat buffer layer is formed on the ceramic body A or B to obtain a ceramic substrate 1- 10. Finally, the average surface roughness (Ra) and warpage (warpage) of the ceramic substrates 1-10 were measured. Please refer to Table 5 for the results.

table 5

ingredients Ra(nm) CTE(10 ^-6 /℃) Warpage(%) Ceramic substrate 1 (ceramic body B & flat buffer layer 1) 13.6 1.1 0.28 Ceramic substrate 2 (ceramic body A & flat buffer layer 5) 19.4 2.2 0.21 Ceramic substrate 3 (ceramic body B & flat buffer layer 7) 54.6 0.3 0.15 Ceramic substrate 4 (ceramic body B & flat buffer layer 10) 34.9 2.2 0.26 Ceramic substrate 5 (ceramic body B & flat buffer layer 16) 9.6 0.4 0.08 Ceramic substrate 6 (ceramic main body B & flat buffer layer 21) 22.4 0.3 0.12 Ceramic substrate 7 (ceramic body B & flat buffer layer 26) 11.4 1.2 0.09 Ceramic substrate 8 (ceramic body B & flat buffer layer 32) 14.9 2.6 0.32 Ceramic substrate 9 (ceramic main body A & flat buffer layer 32) 19.7 1.4 0.20 Ceramic substrate 10 (ceramic main body B & flat buffer layer 33) 94.2 1.4 0.18

As shown in Table 5, the average surface roughness (Ra) of the ceramic substrate with a flat buffer layer according to the present invention is significantly improved compared with the ceramic substrate without a flat buffer layer. In addition, the average surface roughness (Ra) of the ceramic substrate with a flat buffer layer according to the present invention is preferably less than 100 nm.

According to other preferred embodiments of the present invention, the applicable manufacturing process temperature of the ceramic substrate described in the present invention is >400° C., and the overall warpage of the substrate is <0.5%. In addition, the working temperature of the planar layer (the temperature combined with the main body of the substrate) is >600°C, and the softening temperature of the planar layer (the temperature of the subsequent coating or preparation process) is >500°C.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The scope of protection of the invention should be based on the scope defined by the appended claims.

Claims (12)

1. A ceramic substrate, comprising: a ceramic body; and A flat buffer layer is disposed on the ceramic body, wherein the coefficient of thermal expansion CTE _m of the ceramic body and the coefficient of thermal expansion CTE _p of the flat buffer layer conform to the relational expression (1) |CTE _m -CTE _p |≤3×10 ^-6 /°C Relational formula (1); Wherein the warpage of the ceramic substrate is <0.5%; The softening temperature of the ceramic body is not less than 800°C; The softening temperature of the flat buffer layer is not less than 500°C; Wherein the average surface roughness of the ceramic substrate is less than 150nm; Wherein the flat buffer layer is composed of the following components: 30-95 parts by weight of silicon oxide; 1-40 parts by weight of aluminum oxide; and 2-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides; Or the flat buffer layer is composed of the following components: 30-75 parts by weight of silicon oxide; 5-40 parts by weight of aluminum oxide; and 0.1-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides; Or the flat buffer layer is composed of the following components: 76-95 parts by weight of silicon oxide; 1-25 parts by weight of aluminum oxide; and 4-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides. 2. The ceramic substrate according to claim 1, wherein the thermal expansion coefficient of the ceramic body is not greater than 10×10 ⁻⁶ /°C. 3. The ceramic substrate according to claim 1, wherein the coefficient of thermal expansion of the flat buffer layer is not greater than 7×10 ⁻⁶ /°C. 4. The ceramic substrate according to claim 1, wherein the flat buffer layer has a thickness not greater than 200 μm. 5. The ceramic substrate of claim 1, wherein the ceramic body comprises graphite, silicon nitride, silicon carbide, silicon oxide, aluminum oxide, mullite, granite, marble, or a mixture thereof. 6. The ceramic substrate according to claim 1, wherein the average surface roughness of the ceramic substrate is less than 100 nm. 7. The ceramic substrate according to claim 1, wherein the flat buffer layer has a thickness not greater than 150 μm. 8. The ceramic substrate according to claim 1, wherein the average surface roughness of the ceramic substrate is less than 100 nm. 9. The ceramic substrate according to claim 1, wherein the ceramic substrate is applied to solar cells, light emitting diodes, IC packaging, micro-electromechanical systems, electronic devices, or thin film transistors. 10. A ceramic substrate comprising: a ceramic body; and A flat buffer layer is disposed on the ceramic body, wherein the coefficient of thermal expansion CTE _m of the ceramic body and the coefficient of thermal expansion CTE _p of the flat buffer layer conform to the relational expression (1) |CTE _m -CTE _p |≤3×10 ^-6 /°C Relational formula (1); Wherein the warpage of the ceramic substrate is <0.5%; The softening temperature of the ceramic body is not less than 800°C; The softening temperature of the flat buffer layer is not less than 500°C; Wherein the average surface roughness of the ceramic substrate is less than 150nm; Wherein the flat buffer layer is composed of the following components: 30-95 parts by weight of silicon oxide; 1-40 parts by weight of aluminum oxide; 2-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides; and 0.1-46 parts by weight Zirconium dioxide, zinc oxide, titanium dioxide, yttrium oxide, lanthanum oxide, tungsten oxide WO _x , tin oxide and germanium dioxide, where x is 2 or 3. 11. A ceramic substrate comprising: a ceramic body; and A flat buffer layer is disposed on the ceramic body, wherein the coefficient of thermal expansion CTE _m of the ceramic body and the coefficient of thermal expansion CTE _p of the flat buffer layer conform to the relational expression (1) |CTE _m -CTE _p |≤3×10 ^-6 /°C Relational formula (1); Wherein the warpage of the ceramic substrate is <0.5%; The softening temperature of the ceramic body is not less than 800°C; The softening temperature of the flat buffer layer is not less than 500°C; Wherein the average surface roughness of the ceramic substrate is less than 150nm; Wherein the flat buffer layer is composed of the following components: 30-75 parts by weight of silicon oxide; 5-40 parts by weight of aluminum oxide; 0.1-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxide; and 25-46 parts by weight Parts of zirconium dioxide, zinc oxide, titanium dioxide, yttrium oxide, lanthanum oxide, tungsten oxide WO _x , tin oxide and germanium dioxide, wherein x is 2 or 3. 12. A ceramic substrate comprising: a ceramic body; and A flat buffer layer is disposed on the ceramic body, wherein the coefficient of thermal expansion CTE _m of the ceramic body and the coefficient of thermal expansion CTE _p of the flat buffer layer conform to the relationship (1) |CTE _m -CTE _p |≤3×10 ^-6 /°C Relational formula (1); Wherein the warpage of the ceramic substrate is <0.5%; The softening temperature of the ceramic body is not less than 800°C; The softening temperature of the flat buffer layer is not less than 500°C; Wherein the average surface roughness of the ceramic substrate is less than 150nm; Wherein the flat buffer layer is composed of the following components: 76-95 parts by weight of silicon oxide; 1-25 parts by weight of aluminum oxide; 4-35 parts by weight of boron oxide, phosphorus oxide and alkaline earth oxides; and 0.1-40 parts by weight Parts of zirconium dioxide, zinc oxide, titanium dioxide, yttrium oxide, lanthanum oxide, tungsten oxide WO _x , tin oxide and germanium dioxide, wherein x is 2 or 3.