Preparation method and application of light-cured 3D printing AlN-based ultra-thin precise porous structure ceramic

Abstract

The application discloses a slurry formula of a photocured 3D printing preparation AlN-based ultrathin precise porous structure ceramic for an electrostatic chuck and a printing method thereof, adopts three resins of o-phenylphenoxyethyl acrylate, 1,6-hexanediol diacrylate and ethoxylated pentaerythritol tetraacrylate, and prepares the slurry in a formula ratio of 5:3:2, so that the curing depth of the photocured 3D printing AlN porous structure ceramic slurry can be significantly improved under the condition of 50% solid content. It is favorable to print the AlN ultrathin precise porous structure ceramic body with high precision and no defects. Further, in combination with reasonable selection of a sintering temperature, the application can obtain the AlN ultrathin precise porous structure ceramic applied to the electrostatic chuck.

Description

Technical Field

[0001] This invention belongs to the field of ceramic additive manufacturing technology, specifically relating to a method for preparing AlN-based ultrathin precision porous ceramics by photopolymerization 3D printing and its application. Background Technology

[0002] An electrostatic chuck is a fixture that uses electrostatic adsorption to hold and fix the adsorbed material. Suitable for vacuum and plasma environments, its main function is to adsorb ultra-clean thin wafers (such as silicon wafers) and maintain good flatness, suppressing deformation of the adsorbed material during processing and regulating its temperature. Electrostatic chucks are widely used in core semiconductor manufacturing processes and are one of the core components in critical processes such as ion implantation, etching, and vapor deposition. Especially in the essential vapor deposition stage of chip production, this stage has high requirements for the overall thermal uniformity and flatness of the chuck body; the temperature difference across the entire chuck body must not exceed 5% to ensure consistent deposition layer thickness. Currently, a combination of embedded wire heating and gas flow through the vias is often used, with helium gas flowing through the vias to help ensure thermal uniformity. In the working environment of cutting-edge technology fields (such as lithography machines), the requirements for temperature control and flatness of the electrostatic chuck body are extremely high.

[0003] Due to its high thermal conductivity and coefficient of thermal expansion, aluminum nitride (AlN) is considered an ideal material for next-generation semiconductor packaging. This patent proposes a method for preparing an ultrathin, precision porous ceramic structure based on AlN for electrostatic chucks using photopolymerization 3D printing. This ceramic structure can be placed within airflow holes on the surface of the electrostatic chuck. Aluminum nitride is chosen primarily because of its high thermal conductivity, which promotes overall thermal uniformity of the chuck. Furthermore, in this invention, the porous aluminum nitride ceramic not only conducts heat but also allows for control of airflow by adjusting the pore structure and number of pores, thereby further adjusting the overall thermal uniformity and flatness of the electrostatic chuck. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0006] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing AlN-based ultrathin precision porous ceramic structures by photopolymerization 3D printing.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing AlN-based ultrathin precision porous ceramic structures by photopolymerization 3D printing, characterized in that it includes:

[0008] Aluminum nitride photocurable slurry is prepared, wherein the aluminum nitride ceramic slurry comprises aluminum nitride powder, photocurable resin, dispersant, photoinitiator, sintering aid, and defoamer;

[0009] The composition, by mass percentage, is as follows: aluminum nitride powder: 50%–73%, photocurable resin: 20%–30%, dispersant: 1%–5%, photoinitiator: 2%–5%, sintering aid: 3%–8%, defoamer: 1%–2%.

[0010] The above-mentioned aluminum nitride photocurable slurry was added to the slurry chamber of a multi-material photocurable 3D printer, and the model information of the aluminum nitride porous ceramic skeleton was input into the printer for photocurable printing. After degreasing, decarburizing and sintering treatment, photocurable 3D printed AlN-based ultrathin precision porous structure ceramic was obtained.

[0011] The photocurable resin according to claim 1 is characterized in that: the photocurable resin is a mixture of monofunctional photocurable monomers, difunctional photocurable monomers, tetrafunctional photocurable monomers and high refractive index photocurable monomers; wherein the volume ratio of monofunctional photocurable monomers, difunctional photocurable monomers and tetrafunctional photocurable monomers is 5:3:2.

[0012] In a preferred embodiment of the preparation method described in this invention, the monofunctional photocurable monomer is o-phenylphenoxyethyl acrylate; the difunctional photocurable monomer is 1,6-hexanediol diacrylate; and the tetrafunctional photocurable monomer is ethoxylated pentaerythritol tetraacrylate.

[0013] In a preferred embodiment of the preparation method described in this invention, the dispersant is a polymer copolymer dispersant, the defoamer is defoamer 204, the photoinitiator is bis(2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and the sintering aid is yttrium trioxide powder.

[0014] As a preferred embodiment of the preparation method described in this invention, the method for preparing the aluminum nitride slurry includes adding aluminum nitride powder, photocurable resin, dispersant, photoinitiator, sintering aid and defoamer to anhydrous ethanol and placing them in a ball mill jar, using zirconia ball milling beads as the ball milling medium, ball milling and mixing, placing them in a drying oven to dry, and then grinding them through a 100-mesh sieve to obtain a mixed powder with an average particle size of 2.5 μm.

[0015] In a preferred embodiment of the preparation method described in this invention, the aluminum nitride powder and the sintering aid yttrium oxide powder are mixed in a ratio of 95:5.

[0016] As a preferred embodiment of the preparation method described in this invention, the ball mill has a predetermined rotation speed of 350 rpm and a predetermined grinding time of 10 h ± 0.5 h; the drying oven has a predetermined temperature of 80 °C; the drying oven has a predetermined drying time of 6 h; the aluminum nitride powder has an average particle size of 1.8–2 μm, and the yttrium oxide powder has an average particle size of 50 nm.

[0017] As a preferred embodiment of the preparation method described in this invention, the following steps are taken: the degreasing process of the aluminum nitride porous ceramic green body is carried out in a protective atmosphere, which is nitrogen; the aluminum nitride porous ceramic green body is placed in a central ring tube furnace, the degreasing temperature ranges from 25℃ to 600℃, the heating rate is 0.1℃ / min to 1℃ / min, and the temperature is held at 150℃, 250℃, 350℃ and 450℃ for 60 to 240 min respectively;

[0018] The exposure intensity of the photopolymerization printing process is 30mW / cm². 2 The printing layer thickness was 20 μm; the exposure time was 4 s; and a porous aluminum nitride ceramic green body was obtained after layer-by-layer printing.

[0019] As a preferred embodiment of the preparation method described in this invention, the degreased aluminum nitride porous ceramic green body is subjected to decarburization treatment and placed in a low-temperature muffle furnace. The decarburization temperature ranges from 25°C to 700°C, and the heating rate is 0.5°C / min to 5°C / min. The green body is held at 400°C and 700°C for 60 min, respectively.

[0020] The high-temperature sintering is either pressureless sintering or gas pressure sintering; the high-temperature sintering uses a protective atmosphere, which is generally an inert gas such as nitrogen; the high-temperature sintering temperature is 1800–1850℃, and the holding time is 4–5 hours.

[0021] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing photopolymer 3D printed AlN-based ultrathin precision porous ceramics, and to apply the photopolymer 3D printed ultrathin precision AlN porous ceramics obtained therefrom in electrostatic chucks.

[0022] Beneficial effects of this invention:

[0023] This invention employs a novel photosensitive resin reactive diluent formulation: o-phenylphenoxyethyl acrylate: 1,6-hexanediol diacrylate: ethoxylated pentaerythritol tetraacrylate in a 5:3:2 ratio to prepare the photocurable printing slurry. This improves the curing depth of the photocurable 3D printing AlN ceramic slurry and reduces its viscosity, facilitating the rapid printing of high-precision, defect-free AlN-based ultrathin porous ceramic preforms. Furthermore, by rationally selecting the sintering temperature, this invention can obtain AlN-based ultrathin porous ceramic preforms for electrostatic chucks, improving the flatness of the chuck body while ensuring thermal uniformity and controlling airflow. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments and comparative examples will be briefly introduced below. Obviously, the drawings described below are only some embodiments and comparative examples of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0025] Figure 1 The morphology of the complete precision ceramic green sample obtained by photocuring and printing the aluminum nitride paste prepared in Example 1 of the present invention.

[0026] Figure 2 The image shows the morphology of the ceramic green sample obtained by photocuring and printing using a slurry prepared with the same proportion of a different resin as in Example 1 of the present invention.

[0027] Figure 3 The image shows the morphology of the ceramic green sample obtained by photocuring and printing using a slurry prepared with the same proportion of a different resin as in Example 1 in Comparative Example 2 of this invention.

[0028] Figure 4 The image shows the morphology of the ceramic green sample obtained by photocuring and printing using a slurry prepared with the same proportion of a different resin as in Example 1 in Comparative Example 3 of this invention.

[0029] Figure 5 The image shows the morphology of the ceramic green sample obtained by photocuring and printing using a slurry prepared with the same proportion of a different resin as in Example 1 in Comparative Example 4 of this invention.

[0030] Figure 6 The image shows the morphology of the ceramic green sample obtained by photocuring and printing using a slurry prepared with the same proportion of a different resin as in Example 1 in Comparative Example 5 of this invention.

[0031] Figure 7The image shows the morphology of the ceramic green sample obtained by photocuring and printing using a slurry prepared with the same proportion of a different resin as in Example 1 in Comparative Example 6 of this invention.

[0032] Figure 8 This is a viscosity comparison of three different resin formulations in Example 1 and Comparative Examples 1, 2, and 3 with the same proportions.

[0033] Figure 9 This is a comparison of the viscosity of three different resin formulations (Examples 4, 5, and 6) with the same proportions.

[0034] Figure 10 The precision structure obtained after sintering at 1850°C in Example 1 is shown.

[0035] Figure 11 The image shows a SEM image of Example 1 after sintering at 1850°C.

[0036] Figure 12 The image shows the SEM image of Example 1 after sintering at 1800°C. Detailed Implementation

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0039] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0040] Unless otherwise specified, all raw materials used in this invention are commercially available in the field, as detailed in Table 1.

[0041] The 3D printer used in this invention is the MicroArch S230A micro-nano ceramic 3D printer developed by BMF Percision Tech Co., Ltd. The ceramic printing layer thickness used for testing was 20 μm, and the exposure energy was 30 mW / cm². 2 The exposure time is 4 seconds.

[0042] Table 1

[0043]

[0044] Example 1

[0045] This embodiment provides a method for preparing ultrathin, precision AlN porous ceramic structures by photopolymerization 3D printing, specifically:

[0046] 1) Preparation of aluminum nitride photocurable slurry:

[0047] Weigh 8.46g of monofunctional photosensitive resin reactive diluent o-phenylphenoxyethyl acrylate, 5.08g of difunctional photosensitive resin reactive diluent 1,6-hexanediol diacrylate, 3.38g of tetrafunctional photosensitive resin reactive diluent ethoxylated pentaerythritol tetraacrylate, 1g of photoinitiator phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 0.7g of defoamer 204, 47.5g of aluminum nitride powder, 2.5g of yttrium oxide sintering aid, and 1g of dispersant SP-710 into a plastic container, add 20g of zirconia ball milling beads, and ball mill at 350 rpm for 10 hours to obtain a photocurable slurry.

[0048] 2) Perform photopolymerization 3D printing:

[0049] The printer used was a MicroArch S230A micro-nano ceramic printer (Mofang Precision Technology Co., Ltd.), with an exposure intensity of 30mW / cm². 2 The single exposure time was 4 seconds, the single layer thickness was 20 micrometers, and cubic porous ceramic samples with wall thicknesses of 120 μm, 90 μm, and 60 μm were printed. The printed parts were ultrasonically cleaned twice with anhydrous ethanol for 1 minute each time.

[0050] See the photo of the printed ceramic body. Figure 1 The uniform wall thickness and absence of obvious cracks indicate that the printing result is good.

[0051] 3) Defatting:

[0052] A two-step degreasing method was used to degrease the printed preform. The specific steps are as follows: The printed sample was placed in a boron nitride crucible, and the crucible was placed in a tube furnace for degreasing treatment. The first step was low-temperature degreasing, in which the temperature was first increased from room temperature to 250°C at a rate of 1°C / min under a nitrogen atmosphere, and held at 150°C and 250°C for 1 hour each, before cooling to room temperature. The second step was high-temperature degreasing, in which the temperature was increased to 250°C at a rate of 1°C and held for 1 hour, then increased to 600°C at a rate of 0.1°C / min, and held at 350°C and 450°C for 1 hour and 4 hours respectively, before cooling to room temperature.

[0053] 4) Sintering

[0054] After degreasing, sintering is carried out under a nitrogen atmosphere at a temperature of 1850℃ for 5 hours.

[0055] like Figure 10 , 11 As shown, a relatively complete precision structure and microstructure are obtained after sintering.

[0056] Comparative Example 1

[0057] Using formulations of different resins, the relationship between curing depth and exposure energy was tested. A slurry with a mass fraction of 50% AlN photocurable ceramic printing paste was prepared, with other additive proportions the same as in Example 1. The resin formulation used was N-acryloylmorpholine, 1,6-hexanediol diacrylate, and ethoxylated pentaerythritol tetraacrylate in a ratio of 5:3:2. Figure 2 As shown, AlN slurry using this resin formulation is difficult to achieve high curing depth under low exposure intensity, and it is difficult to achieve effective photocuring.

[0058] Comparative Example 2

[0059] Using formulations of different resins, the relationship between curing depth and exposure energy was tested. A 50% (w / w) AlN photocurable ceramic printing paste was prepared, with other additive proportions the same as in Example 1. The resin formulation used was propylene oxide neopentyl glycol acrylate, 1,6-hexanediol diacrylate, and ethoxylated pentaerythritol tetraacrylate in a ratio of 5:3:2. Figure 3 As shown, AlN slurry using this resin formulation is difficult to achieve high curing depth under low exposure intensity, and it is difficult to achieve effective photocuring.

[0060] Comparative Example 3

[0061] Using formulations of different resins, the relationship between curing depth and exposure energy was tested. A slurry with a mass fraction of 50% AlN photocurable ceramic printing paste was prepared, with other additive proportions the same as in Example 1. The resin formulation used was dioctyl phthalate, 1,6-hexanediol diacrylate, and ethoxylated pentaerythritol tetraacrylate in a ratio of 5:3:2. Figure 4 As shown, AlN slurry using this resin formulation is difficult to achieve high curing depth under low exposure intensity, and it is difficult to achieve effective photocuring.

[0062] Comparative Example 4

[0063] Using formulations of different resins, the relationship between curing depth and exposure energy was tested. A 50% (w / w) AlN photopolymer printing ceramic paste was prepared, with other additive proportions the same as in Example 1. The resin formulation used a 6:4 ratio of 1,6-hexanediol diacrylate to ethoxylated pentaerythritol tetraacrylate. Figure 5As shown, AlN slurry using this resin formulation is difficult to achieve high curing depth under low exposure intensity, and it is difficult to achieve effective photocuring.

[0064] Comparative Example 5

[0065] Using formulations of different resins, the relationship between curing depth and exposure energy was tested. A 50% (w / w) AlN photocurable ceramic printing paste was prepared, with other additive proportions the same as in Example 1. The resin formulation used a 6:4 ratio of 1,6-hexanediol diacrylate to o-phenylphenoxyethyl acrylate. Figure 6 As shown, AlN slurry using this resin formulation is difficult to achieve high curing depth under low exposure intensity, and it is difficult to achieve effective photocuring.

[0066] Comparative Example 6

[0067] Using formulations of different resins, the relationship between curing depth and exposure energy was tested. A slurry with a mass fraction of 50% AlN photocurable ceramic printing paste was prepared, with other additive proportions the same as in Example 1. The resin formulation used a ratio of o-phenylphenoxyethyl acrylate to ethoxylated pentaerythritol tetraacrylate of 6:4. Figure 7 As shown, AlN slurry using this resin formulation is difficult to achieve high curing depth under low exposure intensity, and it is difficult to achieve effective photocuring.

[0068] Comparative Example 7

[0069] The difference from Example 1 is that the sintering temperature is set to 1800°C. Figure 12 SEM test results show that there are many pores and defects inside the sample after sintering at 1800℃.

[0070] and Figure 11 contrast, Figure 12 The samples had poor density and microstructure, and no well-bonded AlN porous ceramic sintered samples were obtained, highlighting the importance of numerical ratio formulation and control of sintering temperature.

[0071] Table 2

[0072]

[0073]

[0074] Figure 8 and Figure 9 The graph shows a comparison of the viscosity of the slurry after mixing in Experimental Example 1 with that after mixing in Comparative Examples 1, 2, 3, 4, 5, and 6. It is clear that the viscosity of Experimental Example 1 is much lower than that of Comparative Examples 1, 2, 3, 4, 5, and 6.

[0075] In summary, this invention employs a novel resin formulation to prepare the photocurable printing slurry, which significantly improves the curing depth of the photocurable 3D printing slurry for AlN-based ceramics. This is beneficial for printing ultra-thin, precision AlN-based ceramic preforms for electrostatic chucks. Furthermore, this invention allows for flexible control of the powder system particle size through processes such as ball milling and sieving, combined with the rational selection of sintering temperature, enabling the production of complete porous AlN ceramics for electrostatic chucks.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing AlN-based ultrathin precision porous ceramic structures by photopolymerization 3D printing, characterized in that: include, 1) Preparation of aluminum nitride photocurable slurry: Weigh 8.46g of monofunctional photosensitive resin reactive diluent o-phenylphenoxyethyl acrylate, 5.08g of difunctional photosensitive resin reactive diluent 1,6-hexanediol diacrylate, 3.38g of tetrafunctional photosensitive resin reactive diluent ethoxylated pentaerythritol tetraacrylate, 1g of photoinitiator phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 0.7g of defoamer 204, 47.5g of aluminum nitride powder, 2.5g of yttrium oxide sintering aid, and 1g of dispersant SP-710 into a plastic container, add 20g of zirconia ball milling beads, and ball mill at 350 rpm for 10 hours to obtain a photocurable slurry; 2) Perform photopolymerization 3D printing: The MicroArch S230A micro-nano ceramic printer was used, with an exposure intensity of 30 mW / cm². 2 The single exposure time was 4 seconds, the single layer thickness was 20 micrometers, and cubic porous ceramic samples with wall thicknesses of 120 μm, 90 μm and 60 μm were printed. The printed parts were ultrasonically cleaned twice with anhydrous ethanol for 1 minute each time. 3) Defatting: A two-step degreasing method was used to degrease the printed blank. The specific steps are as follows: The printed sample was placed in a boron nitride crucible, and the crucible was placed in a tube furnace for degreasing treatment. The first step was low-temperature degreasing, in which the temperature was first increased from room temperature to 250°C at a rate of 1°C / min under a nitrogen atmosphere, and held at 150°C and 250°C for 1 hour each, and then cooled to room temperature. The second step was high-temperature degreasing, in which the temperature was increased to 250°C at a rate of 1°C and held for 1 hour, and then increased to 600°C at a rate of 0.1°C / min, and held at 350°C and 450°C for 1 hour and 4 hours respectively, and then cooled to room temperature. 4) Sintering: After degreasing, sintering is carried out under a nitrogen atmosphere at a temperature of 1850 ℃ and a holding time of 5 h.

Images