A rotating silicon target based on a composite substrate and a method for producing the same

Abstract

The application relates to a rotating silicon target based on a composite substrate and a preparation method thereof, and belongs to the technical field of composite materials. High-precision forming of a tubular high-temperature-resistant composite substrate is realized by using a high-residual-carbon benzoxazine prepreg and an automatic winding process. High-temperature pyrolysis and purification of the composite substrate are realized through high-temperature heat treatment. Finally, the rapid integrated preparation of a new rotating silicon target is completed through a high-temperature infiltration process in a state of embedding high-purity silicon particles on the periphery of the composite substrate. Compared with the silicon target obtained by a conventional metal substrate and a spraying process, the new composite substrate silicon target has the advantages that the thermal matching of the corresponding silicon layer and the composite substrate is good, the combination is strong, the silicon layer obtained by the infiltration process has high density and high purity, and the urgent demand for high-quality rotating silicon targets in the booming development of emerging semiconductor and other high-tech fields is met.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a rotating silicon target based on a composite substrate and its preparation method. Background Technology

[0002] Sputtering targets are indispensable emerging high-tech materials in the field of preparing various functional thin films using sputtering processes. They are widely used in high-tech fields such as semiconductor integrated circuits, display panels, photovoltaic cells, and optical coatings. Among them, high-purity silicon sputtering targets are a class of high-end sputtering materials that have attracted much attention and have great application prospects. Utilizing the unique physical and chemical properties of sputtered silicon atomic thin films, they can be used to prepare a wide range of devices, including single-crystal silicon, silicon wafers, liquid crystal displays, transistors, diodes, silicon-based circuit boards, magnetic materials, filters, and mirrors. Compared with traditional planar silicon targets, rotating silicon targets have advantages such as high target utilization, high sputtering rate, good film uniformity, low maintenance frequency, and low cost. They have become the main application target widely recognized in the market, and the demand is increasing day by day.

[0003] Currently, rotating silicon sputtering targets typically use stainless steel tubes as substrates, and a silicon layer of approximately 6-10 mm thickness is prepared on the substrate surface using high-purity silicon powder and plasma spraying. However, due to limitations in the process, the resulting silicon targets have low density, high oxygen content, and exhibit significant thermal mismatch and reliability issues caused by the large difference in thermal expansion coefficients between the metal substrate and the silicon layer. This results in shortcomings in practical applications, such as low sputtering rates, low component purity, and poor structural uniformity, significantly restricting the practical application of silicon sputtering targets. There is an urgent need to develop novel methods for preparing rotating silicon sputtering targets with high density and purity, and good thermal matching with the silicon layer, to meet the pressing demand for high-purity silicon-based materials in emerging high-tech fields such as semiconductors. Summary of the Invention

[0004] The purpose of this invention is to provide a rotating silicon target based on a composite substrate and its preparation method. Through molding method and process design, using benzoxazine prepreg, high-precision molding of the composite substrate is achieved. Through high-temperature pyrolysis, purification and melt infiltration processes, rapid integrated preparation of the rotating silicon target is achieved.

[0005] The above-mentioned objectives of the present invention are mainly achieved through the following technical solutions: A rotating silicon target based on a composite substrate and its preparation method include the following steps: (1) Fix the continuous fiber cloth on the deposition fixture for deposition treatment; (2) Mix benzoxazine resin with inert filler and age it to obtain prepreg resin. Coat the prepreg resin to obtain adhesive film. (3) The continuous fiber cloth obtained in step (1) after deposition treatment and the adhesive film obtained in step (2) are combined to obtain benzoxazine prepreg tape; (4) Wrap the benzoxazine prepreg tape obtained in step (3) around the molding fixture, lay it up and cure it to obtain a cured and shaped composite substrate; (5) Decompose the cured composite substrate obtained in step (4); (6) The composite substrate obtained in step (5) is subjected to high-temperature purification treatment; (7) The composite substrate obtained in step (6) is subjected to high-temperature melting and infiltration to obtain a rotating target; (8) Process, clean, dry and package the rotating target material obtained in step (7).

[0006] In step (1), the continuous fiber cloth is fixed by wrapping or laying flat, the carbon source is propane or propylene, the deposition temperature is 900~1200℃, the pressure is 200~3000Pa, and the time is 10~100h.

[0007] In step (1), the fibers used in the continuous fiber cloth are polyacrylonitrile carbon fibers or silicon carbide fibers, and the fiber cloth specifications are satin, twill, or plain weave.

[0008] In step (2), the benzoxazine resin has a carbon residue rate of ≥60%, and the inert filler includes at least one of graphite powder or SiC powder. The mass fraction of the inert filler in the prepreg resin is 0~50%. The resin is aged at 80~120℃ and under stirring conditions for 2~4 hours.

[0009] In step (3), the prepreg is laminated using a prepreg laminating machine at a temperature of 80-120°C and a speed of 1-10 m / s.

[0010] In step (4), the composite substrate forming fixture is mounted on the automatic winding machine, and a release agent is applied to the surface of the composite substrate forming fixture 2-4 times. The benzoxazine prepreg tape with a width of 50-100mm is wound onto the composite substrate forming fixture at a winding speed of 1-3m / min to complete the layup. High-temperature release cloth and high-temperature breathable felt are laid on the surface of the composite substrate after the layup is completed. After encapsulation, the temperature is raised to 180~240℃ at a rate of 0.5~1℃ / min and a pressure of 0.1~0.5MPa for curing treatment for 1~3h.

[0011] In step (5), the pyrolysis treatment heating rate is 0.5~2℃ / min, the pyrolysis temperature is 800~1200℃, and the time is 1~6h.

[0012] In step (6), under the protection of inert gas, the temperature is increased to 1500~2000℃ for high-temperature purification treatment for 2~5 hours at a rate of 1~3℃ / min.

[0013] In step (7), the periphery of the composite substrate is filled with high-purity silicon particles with a particle size of 1~10mm and a purity of ≥99.99%, and the substrate is subjected to high-temperature melting and infiltration at 1450~1600℃ for 0.5~2h under vacuum.

[0014] A rotating silicon target based on a composite substrate is prepared by the preparation method according to any one of claims 1 to 9.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention achieves high-precision molding of tubular high-temperature resistant composite substrates by using benzoxazine prepreg and winding process; achieves high-temperature pyrolysis and purification of composite substrates by high-temperature heat treatment; and completes rapid integrated preparation of novel rotating silicon targets by high-temperature melt infiltration process. Compared with conventional metal substrates and silicon targets obtained by spraying process, which have large thermal mismatch between the substrate and silicon layer and low silicon layer density, the silicon target of this invention has good thermal matching and strong bonding between the silicon layer and the composite substrate, and the silicon layer obtained by melt infiltration process has high density and purity, which meets the urgent demand for high-quality rotating silicon targets in the booming development of emerging high-tech fields such as semiconductors.

[0016] (2) In the preferred embodiment of the present invention, 0~50wt% of inert fillers such as graphite powder and SiC powder are used to effectively suppress the volume change of the resin during the high-temperature pyrolysis process and achieve high-precision molding of the composite substrate. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to specific embodiments: This invention employs benzoxazine prepreg and an automatic winding process to form a high-precision tubular high-temperature resistant composite material substrate, which is then subjected to high-temperature treatment under graphite tooling clamping conditions to complete the high-temperature pyrolysis and purification of the composite material substrate. The design utilizes a contour-following high-temperature melting infiltration tooling to rapidly and integrally prepare a novel rotating silicon target material by embedding high-purity silicon particles around the composite material substrate through a high-temperature silicon melting process.

[0018] The purpose of this invention is to propose a rapid method for fabricating rotating silicon targets based on composite substrates, the technical solution of which includes the following: 1. Tooling design and manufacturing.

[0019] The preparation of rotating silicon targets based on composite substrates includes three types of fixtures: composite substrate forming fixtures, pyrolysis fixtures, and silicon target conformal high-temperature melting and infiltration fixtures. Among them, the composite substrate forming fixture is used for high-precision forming of composite substrates and is made of cylindrical metal material with a smooth surface. The pyrolysis fixture is mainly used for high-temperature pyrolysis and surface shaping of composite substrates during the heat treatment stage. It is made of high-temperature resistant graphite material and adopts a segmented structure with positioning structures between them for easy disassembly and assembly. The silicon target conformal high-temperature melting and infiltration fixture is used to hold the high-purity silicon particles wrapped around the composite substrate and realize in-situ melting and infiltration. It is made of high-purity and high-density graphite material to ensure melting and infiltration purity and process stability.

[0020] 2. Continuous fiber cloth deposition.

[0021] The continuous fiber cloth is fixed on the deposition fixture by means of wrapping or laying it flat, and then moved into the deposition furnace. Using propane or propylene gas as the carbon source, it is continuously deposited for 10 to 100 hours under the conditions of 900~1200℃ and 200~3000Pa to complete the surface protection of the continuous fiber cloth.

[0022] In this step, the fibers used in the continuous fiber cloth can be polyacrylonitrile carbon fibers of grades such as T300-1K, T300-3K, T700-6K, and T700-12K, or silicon carbide fibers of grades such as Nicalon, Hi-Nicalon, Hi-Nicalon-S, and Tyranno. The fiber cloth specifications can be various structural forms such as satin weave, twill weave, and plain weave.

[0023] 3. Preparation of benzoxazine prepreg.

[0024] A high-strength benzoxazine resin with a curing shrinkage rate and a carbon residue of ≥60% is used, filled with 0-50 wt% of inert fillers such as graphite powder and SiC powder. The resin is aged at 80-120℃ with stirring for 2-4 hours to obtain a prepreg resin with moderate viscosity and good film-forming properties. The prepreg resin is then coated using a coating machine to obtain a film of the designed thickness. Next, the film is laminated with a high-strength continuous fiber cloth that has undergone deposition treatment at 80-120℃ and a speed of 1-10 m / s using a prepreg laminating machine to complete the preparation of the benzoxazine prepreg. This invention effectively suppresses the volume change of the resin during high-temperature pyrolysis by filling it with 0-50 wt% of inert fillers such as graphite powder and SiC powder, achieving high-precision molding of the composite substrate.

[0025] 4. Contouring layup of composite substrate.

[0026] The composite substrate forming fixture is mounted onto the automatic winding machine. A release agent is applied to its surface 2-4 times. Then, a benzoxazine prepreg tape with a width of 50-100mm is wound uniformly onto the metal cylinder forming fixture at a winding speed of 1-3m / min. The edges of the tape are butted together to gradually achieve the conformal layup of the composite substrate.

[0027] 5. Curing of the composite substrate.

[0028] High-temperature release cloth and high-temperature breathable felt are laid on the surface of the composite substrate after the coating is completed. Then, the substrate is sealed in a vacuum bag and then heated to 180-240℃ in an autoclave at a rate of 0.5-1℃ / min and a pressure of 0.1-0.5MPa for 1-3 hours to obtain a cured composite substrate.

[0029] 6. Cracking of composite substrate.

[0030] The cured and shaped composite substrate is placed into a pyrolysis fixture, and then heated to 800~1200℃ for 1~6 hours in a heat treatment device under inert gas protection at a rate of 0.5~2℃ / min to complete the high-temperature pyrolysis of the composite substrate.

[0031] 7. High-temperature treatment of composite substrate.

[0032] The composite substrate, which has undergone high-temperature pyrolysis, is placed in a high-temperature furnace along with the tooling. Under inert gas protection, the temperature is increased to 1500-2000℃ at a rate of 1-3℃ / min for 2-5 hours to complete the high-temperature purification treatment of the composite substrate.

[0033] 8. High-temperature melting and casting.

[0034] The high-temperature purified composite substrate is placed in a melting and infiltration mold, and the surrounding area is filled with high-purity silicon particles with a particle size of 1~10mm and a purity of ≥99.99%. The high-temperature melting and infiltration is carried out under vacuum and 1450~1600℃ conditions for 0.5~2h to achieve high-temperature melting and infiltration of the high-purity silicon layer and its tight bonding with the composite substrate.

[0035] 9. Precision machining and cleaning.

[0036] The surface and end connection area of ​​the rotating silicon target material that has undergone high-temperature melting and infiltration are precision machined, and then cleaned, dried and packaged to finally complete the preparation of a new type of rotating silicon target material based on a composite substrate.

[0037] The prepreg prepared by this invention has a resin content of 50%~70wt% and a fiber volume content of 30~40% in the molded composite substrate, providing a porous skeleton support for subsequent efficient diffusion and melting infiltration and strong bonding between the substrate and silicon layers.

[0038] Example 1 First, benzoxazine resin and 20% graphite powder were stirred and aged at 90℃ for 3 hours to obtain prepreg resin. Then, a coating was applied at 80℃, and the mixture was composited at 100℃ with T300-3K carbon fiber satin fabric that had undergone carbon deposition via pyrolysis at 900℃ for 50 hours using propane gas to obtain benzoxazine prepreg. Next, contour layup was performed on a composite substrate forming fixture using an automatic winding machine and strip butt bonding method. The composite was then cured in an autoclave at 220℃ and 0.3MPa for 2 hours. Finally, the cured composite substrate was placed under the clamping of a pyrolysis fixture. The silicon target was pyrolyzed at 1000℃ for 4 hours in a pyrolysis furnace, followed by high-temperature purification at 1600℃ for 3 hours in a high-temperature treatment furnace. Then, the composite substrate was placed in a melting and infiltration mold, and high-purity silicon particles with a particle size of 1-3mm were embedded around it. The silicon target was then melted and infiltrated at 1500℃ under vacuum for 1 hour to obtain a rotating silicon target blank for the composite substrate. Finally, the blank was precision machined to complete the rapid preparation of the rotating silicon target based on the T300-3K carbon fiber reinforced composite substrate. The purity of the obtained silicon target was 99.97% and the density was 99.3%.

[0039] Example 2 First, benzoxazine resin and 30% SiC powder were stirred and aged at 90℃ for 3 hours to obtain prepreg resin. Then, a coating was applied at 80℃, and the mixture was composited at 100℃ with T700-12K carbon fiber plain weave fabric that had undergone carbon deposition via pyrolysis at 950℃ for 30 hours using propane gas to obtain benzoxazine prepreg. Next, contour layup was performed on a composite substrate forming fixture using an automatic winding machine and strip butt bonding method, followed by curing at 200℃ and 0.4MPa for 3 hours in an autoclave. Finally, the cured composite substrate was clamped under a pyrolysis fixture. The silicon target was pyrolyzed at 900℃ for 6 hours in a pyrolysis furnace, followed by high-temperature purification at 1800℃ for 2 hours in a high-temperature treatment furnace. Then, the composite substrate was placed in a melting and infiltration mold, and high-purity silicon particles with a particle size of 3-6mm were embedded around it. The silicon target was then melt-infiltrated at 1550℃ under vacuum for 1 hour to obtain a rotating silicon target blank for the composite substrate. Finally, the blank was precision machined to complete the rapid preparation of the rotating silicon target based on the T700-12K carbon fiber reinforced composite substrate. The purity of the obtained silicon target was 99.99% and the density was 99.6%.

[0040] Example 3 First, benzoxazine resin and 20% SiC powder were stirred and aged at 100℃ for 2 hours to obtain a prepreg resin. Then, a coating was applied at 90℃, and the prepreg was composited with Hi-Nicalon silicon carbide fiber satin fabric deposited by pyrolysis of propane gas at 1000℃ for 20 hours at 105℃ to obtain a benzoxazine prepreg. Next, contour layup was performed on a composite substrate forming fixture using an automatic winding machine and strip butt bonding method, and cured in an autoclave at 240℃ and 0.3MPa for 2 hours. Finally, the cured composite substrate was clamped in a pyrolysis fixture. The substrate was placed in a pyrolysis furnace and pyrolyzed at 1000℃ for 4 hours, followed by high-temperature purification treatment at 1500℃ for 2 hours in a high-temperature treatment furnace. Then, the composite substrate was placed in a melting and infiltration mold, and high-purity silicon particles with a particle size of 1-3 mm were embedded around it. The substrate was then melted and infiltrated at 1450℃ under vacuum for 2 hours to obtain a rotating silicon target blank of the composite substrate. Finally, the blank was precision machined to complete the rapid preparation of the rotating silicon target based on the Hi-Nicalon silicon carbide fiber reinforced composite substrate. The purity of the obtained silicon target was 99.94% and the density was 99.1%.

[0041] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0042] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A rotating silicon target based on a composite substrate and its preparation method, characterized in that: Includes the following steps: (1) Fix the continuous fiber cloth on the deposition fixture for deposition treatment; (2) Mix benzoxazine resin with inert filler and age it to obtain prepreg resin. Coat the prepreg resin to obtain adhesive film. (3) The continuous fiber cloth obtained in step (1) after deposition treatment and the adhesive film obtained in step (2) are combined to obtain benzoxazine prepreg tape; (4) Wrap the benzoxazine prepreg tape obtained in step (3) around the molding fixture, lay it up and cure it to obtain a cured and shaped composite substrate; (5) Decompose the cured composite substrate obtained in step (4); (6) The composite substrate obtained in step (5) is subjected to high-temperature purification treatment; (7) The composite substrate obtained in step (6) is subjected to high-temperature melting and infiltration to obtain a rotating target; (8) Process, clean, dry and package the rotating target material obtained in step (7).

2. The rotating silicon target based on a composite substrate and its preparation method according to claim 1, characterized in that: In step (1), the continuous fiber cloth is fixed by wrapping or laying flat, the carbon source is propane or propylene, the deposition temperature is 900~1200℃, the pressure is 200~3000Pa, and the time is 10~100h.

3. The rotating silicon target based on a composite substrate and its preparation method according to claim 1, characterized in that: In step (1), the fibers used in the continuous fiber cloth are polyacrylonitrile carbon fibers or silicon carbide fibers, and the fiber cloth specifications are satin, twill, or plain weave.

4. The rotating silicon target based on a composite substrate and its preparation method according to claim 1, characterized in that: In step (2), the benzoxazine resin has a carbon residue rate of ≥60%, and the inert filler includes at least one of graphite powder or SiC powder. The mass fraction of the inert filler in the prepreg resin is 0~50%. The resin is aged at 80~120℃ and under stirring conditions for 2~4 hours.

5. The rotating silicon target based on a composite substrate and its preparation method according to claim 1, characterized in that: In step (3), the prepreg is laminated using a prepreg laminating machine at a temperature of 80-120°C and a speed of 1-10 m / s.

6. The rotating silicon target based on a composite substrate and its preparation method according to claim 1, characterized in that: In step (4), the composite substrate forming fixture is mounted on the automatic winding machine, and a release agent is applied to the surface of the composite substrate forming fixture 2-4 times. The benzoxazine prepreg tape with a width of 50-100mm is wound onto the composite substrate forming fixture at a winding speed of 1-3m / min to complete the layup. High-temperature release cloth and high-temperature breathable felt are laid on the surface of the composite substrate after the layup is completed. After encapsulation, the temperature is raised to 180~240℃ at a rate of 0.5~1℃ / min and a pressure of 0.1~0.5MPa for curing treatment for 1~3h.

7. The rotating silicon target based on a composite substrate and its preparation method according to claim 1, characterized in that: In step (5), the pyrolysis treatment heating rate is 0.5~2℃ / min, the pyrolysis temperature is 800~1200℃, and the time is 1~6h.

8. The rotating silicon target based on a composite substrate and its preparation method according to claim 1, characterized in that: In step (6), under the protection of inert gas, the temperature is increased to 1500~2000℃ for high-temperature purification treatment for 2~5 hours at a rate of 1~3℃ / min.

9. The rotating silicon target based on a composite substrate and its preparation method according to claim 1, characterized in that: In step (7), the periphery of the composite substrate is filled with high-purity silicon particles with a particle size of 1~10mm and a purity of ≥99.99%, and the substrate is subjected to high-temperature melting and infiltration at 1450~1600℃ for 0.5~2h under vacuum.

10. A rotating silicon target based on a composite substrate, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 9.