Ceramic material processing method

Abstract

This invention discloses a ceramic material processing method, which includes: impregnation: impregnating a ceramic blank in a liquid polycarbosilane precursor, so that the liquid polycarbosilane precursor fills the defects of the ceramic blank; cross-linking and curing: making the liquid polycarbosilane precursor thermally decomposed inside the defect, and an oxidative cross-linking reaction occurs. The ceramic material obtained by the invention has few internal defects, high thermal conductivity and low dielectric loss.

Description

[Technical Field]

[0001] This invention relates to the field of ceramic materials, and more specifically to a method for processing ceramic materials. [Previous Technology]

[0002] Aluminum nitride is a structurally stable covalent compound with a hexagonal phase. It has high thermal conductivity, high insulation resistance, and low dielectric loss, exhibiting excellent electrical properties. The theoretical value of the thermal conductivity of aluminum nitride single crystal is 319 W / (m*K). However, in actual production, due to factors such as material purity, internal defects, grain orientation, and sintering process, the thermal conductivity of aluminum nitride is lower than the theoretical value.

[0003] Existing technologies, in order to improve the thermal conductivity of aluminum nitride, involve adding carbon-containing sintering aids during sintering to lower the sintering temperature and remove lattice defects. Commonly used multi-component composite sintering agents include Y₂O₃-CaC₂. However, the introduction of sintering agents brings other problems: as shown in the scanning electron micrograph of Figure 1, the pores present in the aluminum nitride ceramic crystal before sintering are visible; as shown in the scanning electron micrograph of Figure 2, the carbon-containing sintering aid fills the pores. During sintering, due to the high temperature, the pores close rapidly, resulting in a large amount of residual carbon existing on the ceramic crystal surface or at the grain boundaries. These microstructures affect the performance of aluminum nitride, with its actual thermal conductivity reaching a maximum of only about 190 W / (m*K), which is only 0.6 times the theoretical value. At the same time, due to the difference in the density of defects inside the ceramic material at different thicknesses and in different regions, the actual dielectric loss fluctuates by nearly two orders of magnitude from 10⁻² to 10⁻⁴ in different thickness directions and in different regions, thus causing instability in the most important property of the ceramic material. [Summary of the Invention]

[0004] The purpose of this invention is to improve the internal defects that are prone to occur during ceramic sintering, and to obtain ceramic materials with high thermal conductivity, stable and uniform properties, low dielectric loss, high density and low defect density.

[0005] To achieve the above objectives, the present invention provides a method for processing ceramic materials, comprising:

[0006] Immersion: The ceramic green body is immersed in a liquid polycarbonate silane precursor, so that the liquid polycarbonate silane precursor fills the defects of the ceramic green body;

[0007] Cross-linking curing: The liquid polycarbosilane precursor is heated and decomposed inside the defect, resulting in an oxidative cross-linking reaction.

[0008] Optionally, the defect is a micropore and / or a microcrack, and the size of the micropore and / or the microcrack is 0.1 to 5 micrometers.

[0009] Optionally, the ceramic preform is impregnated in liquid polycarbonate silane precursor for 0.5h to 20h.

[0010] Optionally, the ceramic preform is immersed in liquid polycarbonate precursor at a temperature of 25°C to 60°C.

[0011] Optionally, the liquid polycarbonate precursor filling the defects in the ceramic material is crosslinked at 150°C to 300°C.

[0012] Optionally, after the crosslinking and curing, the step of sintering the ceramic blank at 1000°C to 1600°C is further included.

[0013] Optionally, the impregnation and cross-linking curing steps are performed alternately several times. After cross-linking curing, the porosity of the ceramic material is detected until the porosity of the ceramic material no longer changes.

[0014] Optionally, the impregnation and cross-linking curing steps are performed alternately 5-10 times.

[0015] Optionally, the ceramic material comprises any one or more of aluminum nitride, aluminum oxide, silicon carbide, and silicon nitride.

[0016] Optionally, when cracks and / or pores appear in the interior and / or surface of the ceramic material, the method further includes the steps of: immersing the ceramic material in a liquid polycarbonate silane precursor, so that the liquid polycarbonate silane precursor fills the cracks and / or pores; and causing the liquid polycarbonate silane precursor to decompose upon heating, resulting in an oxidative crosslinking reaction to repair the pores and / or cracks.

[0017] Optionally, the ceramic material is used in ceramic assemblies or ceramic moving parts in the semiconductor field.

[0018] Optionally, the ceramic material is used for components of the plasma etching chamber, the components including at least one of an electrostatic chuck, a focusing ring, an edge ring, an insulating ring, a ceramic window, a ceramic plate, an inner liner, a gas nozzle, a gas distribution plate, a gas pipe flange, a plasma confinement ring, a grounding ring, and a moving ring.

[0019] The beneficial effects of the present invention are as follows:

[0020] (1) By using liquid polycarbon silane for ceramization at low temperature, the internal defects (dislocations, pores, impurities, lattice distortion) that are prone to occur in the traditional preparation process of aluminum nitride ceramic blanks are improved, the grain orientation and the influence on the subsequent sintering process of ceramic blanks are improved, and the purity of aluminum nitride material affected by additives is also improved, thereby preparing aluminum nitride ceramics with fewer defects, extremely high thermal conductivity and low dielectric loss.

[0021] (2)The use of carbon-containing sintering aids is reduced, which avoids the rapid closure of the pore channels of aluminum nitride during the sintering process of ceramic blanks due to the high thermal conductivity of aluminum nitride, resulting in residues on the aluminum nitride crystal surface and grain boundaries, thereby affecting the mechanical, thermal and electrical properties of the final sintered ceramic material.

[0022] (3)The method provided by the present invention can also be used to repair defects generated in sintered ceramic materials.

Implementation Method

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] The microstructure of aluminum nitride has a significant impact on its thermal conductivity. The thermal conduction mechanism of aluminum nitride is phonon heat transfer, and its thermal conductivity is affected by grain boundaries, crystal planes, second phases, defects, electrons, and the scattering control of the phonons themselves within the crystal. The thermal conductivity of aluminum nitride is directly proportional to the mean free path of the phonons; the larger the mean free path, the higher the thermal conductivity. From a microstructural perspective, the interaction between phonons and the interaction between phonons and impurities or grain boundary defects all induce scattering, affecting the mean free path of the phonons and thus their thermal conductivity. Therefore, to improve the thermal conductivity of aluminum nitride, it is necessary to reduce the content of defects and impurities in the aluminum nitride crystal.

[0028] The liquid polycarbosilane precursor used in this invention is a precursor of silicon carbide ceramics, with the chemical formula [(CH 2RSiH) x(CH 2R'SiH) y(CH 2R''SiH) z] n, a density of 0.94 g / cm 3, a complex viscosity of <0.1 Pa·s, and a number-average molecular weight between 1000±300 g / mol. At low temperatures and even room temperature, this liquid polycarbonate precursor exhibits fluidity, allowing it to penetrate the voids within crystals. Furthermore, the low thermal decomposition temperature of liquid polycarbonate allows the polymeric portion to decompose and volatilize upon heating, resulting in cross-linking and solidification. This forms ceramicized silicon carbide at crystal boundaries and faces, filling defects. Because adjacent aluminum nitride grains are filled with ceramicized silicon carbide, the mutual compression between aluminum nitride grains is reduced, thereby minimizing dislocations and lattice distortions caused by compression. This results in a more perfect crystal structure, uniform grain distribution, near-ideal thermal conductivity, and excellent electrical properties. Simultaneously, the liquid polycarbonate precursor avoids the use of metal-containing additives, preventing the formation of colored metal oxides during sintering and reducing potential defects such as spots on the ceramic. In addition, the liquid polycarbonate precursor can also repair cracks or pores generated after high-temperature sintering of ceramic blanks.

[0029] As shown in Figure 3, the ceramic material processing method provided by the present invention includes:

[0030] S1, Impregnation: The ceramic blank is impregnated in a liquid polycarbonate silane precursor, so that the liquid polycarbonate silane precursor fills the defects of the ceramic blank;

[0031] Optionally, as shown in FIG4, the defect filled in the impregnation step is micropores 5 and / or microcracks 4, the size of the micropores 5 and / or microcracks 4 being 0.1 to 5 micrometers.

[0032] Optionally, the ceramic material includes any one or more of aluminum nitride, aluminum oxide, silicon carbide, and silicon nitride.

[0033] Optionally, the ceramic green body is immersed in liquid polycarbonate silane precursor at 25℃~60℃ for 0.5h~20h, so that the liquid polycarbonate silane precursor can fully enter the defects of the ceramic green body.

[0034] S2, cross-linking and curing: the liquid polycarbosilane precursor is heated and decomposed inside the defect, resulting in an oxidative cross-linking reaction.

[0035] Optionally, the liquid polycarbonyl silane precursor filling the defects in the ceramic preform is crosslinked at 150°C to 300°C. Due to the decomposition at low temperature, the ceramized SiC can occupy the gaps between AlN grains, thereby reducing the compression between different AlN grains, and thus reducing the lattice distortion 7 and dislocation 6 caused by compression.

[0036] In some embodiments, the above-described impregnation step and cross-linking curing step are performed alternately 5-10 times to ensure that all defects in the ceramic green body are filled and repaired. In other embodiments, the impregnation step and cross-linking curing step are performed alternately several times. After cross-linking curing, the porosity of the ceramic green body is detected until the porosity of the ceramic green body no longer changes.

[0037] As shown in Figure 5, the ceramic material processing method provided by the present invention further includes:

[0038] S3, Sintering: Sinter the ceramic blank at 1000℃~1600℃.

[0039] Due to the microcracks and / or micropores that may occur on the surface and / or inside the ceramic blank during the preparation process or after a period of use, as shown in Figure 6, the ceramic material processing method provided by the present invention further includes:

[0040] S4, Repair: The ceramic material is immersed in liquid polycarbonate precursor, so that the liquid polycarbonate precursor fills the cracks and / or the pores; the liquid polycarbonate precursor is heated and decomposed to undergo an oxidative crosslinking reaction to repair the pores and / or the cracks.

[0041] It should be understood that the processing method provided by the present invention is not limited to repairing cracks and / or pores on the surface and / or inside of ceramic blanks caused by high-temperature sintering, but can also repair cracks and / or pores on the surface and / or inside of any ceramic material for various reasons.

[0042] Optionally, the ceramic material provided by the present invention is used in ceramic assemblies or ceramic moving parts in the semiconductor field, especially components of plasma etching chambers, wherein the components include at least one of electrostatic chuck, focusing ring, edge ring, insulating ring, ceramic window, ceramic plate, inner liner, gas nozzle, gas distribution plate, gas pipe flange, plasma confinement ring, grounding ring, and moving ring.

[0043] Example 1

[0044] S1, Impregnation: The aluminum nitride ceramic blank is impregnated in liquid polycarbonate silane precursor at 25°C for 0.5h, so that the liquid polycarbonate silane precursor fills the defects of the aluminum nitride ceramic blank;

[0045] S2, Crosslinking and Curing: At 150°C, the liquid polycarbonate precursor is thermally decomposed inside the defect, resulting in an oxidative crosslinking reaction.

[0046] The above impregnation step and cross-linking curing step are performed alternately 5 times to ensure that all defects in the ceramic blank are filled and repaired.

[0047] As shown in Figure 7, the ceramic material prepared by the method described in Example 1 has a low defect density and few cracks.

[0048] Example 2

[0049] S1, Impregnation: The aluminum nitride ceramic blank is impregnated in liquid polycarbonate silane precursor at room temperature for 1 hour, so that the liquid polycarbonate silane precursor fills the defects of the ceramic blank;

[0050] S2, Crosslinking and Curing: At 300°C, the liquid polycarbonate precursor is thermally decomposed inside the defect, resulting in an oxidative crosslinking reaction.

[0051] The above impregnation step and cross-linking curing step are performed alternately several times. After each cross-linking curing, the porosity of the ceramic blank is detected until the porosity of the ceramic material no longer changes.

[0052] S3, Sintering: Sintering ceramic blanks at 1000℃.

[0053] Since S1 and S2 pretreat the ceramic green body before sintering through liquid polycarbonate silane precursor, they fill the defects in the ceramic green body, effectively suppressing the growth of aluminum nitride grains during sintering, reducing the probability of grain dislocations and lattice distortion between crystal lattices, and perfecting the crystal structure.

[0054] Example 3

[0055] S1, Impregnation: The alumina ceramic blank is impregnated in liquid polycarbonate precursor at 50°C for 0.5h, so that the liquid polycarbonate precursor fills the defects of the alumina ceramic blank;

[0056] S2, Crosslinking and Curing: At 200°C, the liquid polycarbonate precursor is thermally decomposed inside the defect, resulting in an oxidative crosslinking reaction.

[0057] The above impregnation step and cross-linking curing step are performed alternately several times. After each cross-linking curing, the porosity of the alumina ceramic blank is detected until the porosity of the ceramic material no longer changes.

[0058] S3, Sintering: Sintering alumina ceramic blanks at 1600℃.

[0059] S4, Repair: The alumina ceramic material is immersed in liquid polycarbonate silane precursor, so that the liquid polycarbonate silane precursor fills the cracks and / or the pores; the liquid polycarbonate silane precursor is heated and decomposed to undergo an oxidative crosslinking reaction to repair the pores and / or the cracks.

[0060] When the sintering temperature is too high, micron or nano-level cracks and / or pores inevitably form on the surface and / or inside of the ceramic blank due to high-temperature sintering. In this case, the method provided by the present invention is continued to be used to immerse the sintered ceramic material in liquid polycarbonate silane precursor, and then heat it to cause oxidative crosslinking, so as to repair the pores and / or cracks.

[0061] Example 4

[0062] S1, Impregnation: Yttrium oxide ceramic material that has been used for a period of time and has cracks and / or pores on its surface and / or inside is impregnated in liquid polycarbonate precursor at 30°C for 0.5h, so that the liquid polycarbonate precursor fills the cracks and / or pores of the yttrium oxide ceramic material.

[0063] S2, Crosslinking and Curing: At 200°C, the liquid polycarbonate precursor is thermally decomposed inside cracks and / or pores, resulting in an oxidative crosslinking reaction.

[0064] Optionally, the yttrium oxide ceramic material repaired in this embodiment 4 includes components of a plasma etching chamber coated with yttrium oxide after a period of use, such as at least one of the following: electrostatic chuck, focusing ring, edge ring, insulating ring, ceramic window, ceramic plate, inner liner, gas nozzle, gas distribution plate, gas pipe flange, plasma confinement ring, grounding ring, and moving ring.

[0065] In summary, before sintering, the processing method of the present invention continuously impregnates the ceramic blank in liquid polycarbonate silane precursor, allowing the liquid polycarbonate silane precursor to fill the voids in aluminum nitride. Then, the ceramic blank is heated to crosslink and solidify the liquid polycarbonate silane precursor. This process is repeated multiple times, thereby effectively reducing the internal defects of aluminum nitride ceramic materials and ultimately obtaining ceramic materials with good thermal and electrical properties and perfect crystal structure.

[0066] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above. Therefore, the scope of protection of the present invention should be defined by the appended claims. [Simplified Explanation of the Diagram]

[0023] Figure 1 is a microstructure diagram of aluminum nitride ceramic crystal under a scanning electron microscope. Figure 2 is a microstructure diagram of ceramic material after using a carbon-containing sintering aid under a scanning electron microscope. Figure 3 is a flowchart of a ceramic material processing method provided by the present invention. Figure 4 is a schematic diagram of microstructural defects in aluminum nitride ceramic. Figure 5 is a flowchart of a ceramic material processing method provided by the present invention. Figure 6 is a flowchart of another ceramic material processing method provided by the present invention. Figure 7 is a microstructure diagram of ceramic material prepared using the method described in Example 1 of the present invention under a scanning electron microscope.

Claims

1. A method for processing ceramic materials, comprising: Impregnation: The ceramic preform is impregnated in liquid polycarbonate silane precursor, so that the liquid polycarbonate silane precursor fills the defects of the ceramic preform; Crosslinking and curing: The liquid polycarbonate silane precursor is heated and decomposed inside the defects, resulting in an oxidative crosslinking reaction.

2. The ceramic material processing method as described in claim 1, wherein, The defect is a micropore and / or a microcrack, the size of which is 0.1 to 5 micrometers.

3. The ceramic material processing method as described in claim 1, wherein, The ceramic preform is immersed in liquid polycarbonate silane precursor for 0.5h to 20h.

4. The ceramic material processing method as described in claim 1, wherein, The ceramic preform is immersed in liquid polycarbosilane precursor at a temperature of 25°C to 60°C.

5. The ceramic material processing method as described in claim 1, wherein, The liquid polycarbonate precursor filling the defects in the ceramic material is crosslinked at 150°C to 300°C.

6. The ceramic material processing method as described in claim 1, wherein, The process after cross-linking and curing includes the step of sintering the ceramic preform at 1000°C to 1600°C.

7. The ceramic material processing method as described in claim 1, wherein, The impregnation and cross-linking curing steps are performed alternately several times. After cross-linking curing, the porosity of the ceramic material is detected until the porosity of the ceramic material no longer changes.

8. The ceramic material processing method as described in claim 1, wherein, The impregnation and cross-linking curing steps are performed alternately 5-10 times.

9. The ceramic material processing method as described in claim 1, wherein, The ceramic material includes any one or more of aluminum nitride, aluminum oxide, silicon carbide, and silicon nitride.

10. The ceramic material processing method as described in claim 1, wherein, When cracks and / or pores appear inside and / or on the surface of the ceramic material, the method further includes the steps of: immersing the ceramic material in a liquid polycarbonate silane precursor, so that the liquid polycarbonate silane precursor fills the cracks and / or pores; and causing the liquid polycarbonate silane precursor to decompose upon heating, resulting in an oxidative crosslinking reaction to repair the pores and / or cracks.

11. The ceramic material processing method as described in claim 1, wherein, The ceramic material is used in ceramic assemblies or ceramic moving parts in the semiconductor field.

12. The ceramic material processing method as described in claim 11, wherein, The ceramic material is used in components of the plasma etching chamber, the components including at least one of the following: electrostatic chuck, focusing ring, edge ring, insulating ring, ceramic window, ceramic plate, inner liner, gas nozzle, gas distribution plate, gas pipe flange, plasma confinement ring, grounding ring, and moving ring.

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