Reaction sintering silicon carbide ceramic component and manufacturing method thereof

Abstract

Reactive sintered silicon carbide ceramic components and methods of making the same are described. In some embodiments, the methods described herein may use diamond powder at the interface of two or more preformed portions.

Description

Technical Field

[0001] Aspects of the present disclosure relate to ceramic components for use in the semiconductor industry. More specifically, some embodiments of the present disclosure relate to reaction bonded silicon carbide (RB-SiC) ceramic components that include internal channels. Background Art

[0002] Conventional methods of manufacturing ceramic components used in the semiconductor industry can be problematic, particularly when internal channels are included.

[0003] By comparing such a system with some aspects of the present disclosure set forth in the remainder of this application with reference to the accompanying drawings, further limitations and disadvantages of conventional traditional methods will become apparent to those skilled in the art. Summary of the invention

[0004] The present application provides a method for manufacturing a reaction-sintered silicon carbide ceramic component having one or more internal channels, the method comprising: producing a SiC+carbon preform block having surface channels; placing diamond powder on a bonding surface of the preform block; assembling the preform blocks; and reaction-sintering the preform blocks to generate a ceramic component having internal channels, wherein the reaction-sintering results in the formation of a bond line between the preform blocks.

[0005] The present application also provides a reaction-sintered silicon carbide ceramic component manufactured by the above method of the present invention.

[0006] A system and / or method for manufacturing a ceramic component for use in the semiconductor industry, substantially as shown and / or described in conjunction with at least one of the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] These and other advantages, aspects and novel features of the present disclosure, as well as details of illustrative embodiments thereof, will be more fully understood from the following description and drawings.

[0008] Figure 1 Schematic diagram of reaction sintered silicon carbide. A is a preform, a is carbon, b is SiC particles; and B is a reaction sintered ceramic, c is SiC formed by reaction, and d is Si.

[0009] Figure 2 An exemplary preform bonded with a SiC-based glue is shown. A is the body and cover preform; B is the bonded (glued) preform; C is the reaction sintered ceramic; D is the channel shown by X-ray; E is the microstructure of the bond line.

[0010] Figure 3Shown is a cross section of a RB-SiC flow-through component made by bonding two preform halves with a SiC based glue followed by reaction sintering. Excess glue droplets can be seen in the channels.

[0011] Figure 4 The steps of using diamond powder at the interface of the preformed parts to produce a component with internal channels are shown. A is a semi-preform produced with a channel pattern; B is the bonding surface coated (simple brushing) with diamond powder; C is the semi-preform assembled and reaction sintered.

[0012] Figure 5 A control sample with a reaction sintered semi-preform without diamond at the interface is shown. An unacceptable Si bond line is shown.

[0013] Figure 6 The microstructure of the bond of samples prepared with two different diamond particle sizes at the interface is shown. A and B are the microstructures with 6 μm dry diamond powder at the bond interface (more reactive); C and D are the microstructures with 22 μm dry diamond powder at the bond interface (less reactive). DETAILED DESCRIPTION

[0014] Reaction-sintered silicon carbide (RB-SiC) ceramic components containing internal channels are important to the semiconductor industry. Exemplary components include, but are not limited to, water-cooled wafer tables, water-cooled collector mirrors, and water-cooled high-energy laser mirrors. Conventional components can be prepared by forming preform pieces / components (e.g., two half preforms) with surface channels, bonding the preform pieces with SiC-based glue or adhesive (caulk-like material), and heat treatment (such as, for example, ceramic firing, reaction sintering, etc.) to produce a one-piece ceramic body finished component with internal channels.

[0015] During the conventional preform bonding operation described above, beads of excess SiC-based glue may squeeze into the channels of the finished component. If the channel size is large (5 to 10 mm), the excess glue may not be a problem. However, many next-generation designs have extremely small channel sizes (e.g., <1 mm; in some embodiments, 0.25-1.0 mm or 0.5-1.0 mm). Excess glue drops may restrict flow or even block such small-sized channels, making it difficult to manufacture components with ultra-small channels. Therefore, an alternative bonding method is needed.

[0016] Glass bonding of RB-SiC blocks can be done to try to avoid the problem of excess glue, but this type of bonding has poor corrosion resistance, poor thermal conductivity, poor electrical conductivity, and / or poor temperature rise strength.

[0017] The present disclosure provides a method for forming a bond between silicon carbide (RB-SiC) ceramic components without the use of an adhesive (such as a caulking-like SiC-based glue); thus, no droplets are formed that could clog small channels. The bond is formed by placing dry diamond powder between two or more preform blocks and then reaction sintering the blocks to produce a finished component. In some embodiments, there are two preform blocks; in further embodiments, there are two semi-preforms. In other embodiments, there are more than two preform blocks. After the preform blocks are reaction sintered with each other (i.e., reactively infiltrated with molten Si), the diamond powder expansively reacts with Si to form SiC (via Si+C→SiC), resulting in a bond line (i.e., interface) that is rich in SiC and has most of the silicon reacted away. A strong bond line is formed without droplets of glue entering the channel. Advantages of this manufacturing method may include (1) the ability to produce Si-free bond lines with enhanced corrosion resistance and performance; and / or (2) reduced manufacturing labor. In some embodiments, a majority (>50%) of the silicon in the bond line is reacted; in other embodiments, 75% or more of the silicon is reacted.

[0018] In the disclosed method, dry diamond powder is used, that is, pure diamond powder without additional additives is used. In some embodiments, no vehicle or carrier is used for the diamond powder (i.e., no solvent). In addition, the reaction sintering occurs under vacuum (this will remove any residual moisture, such as room humidity, etc.). In other embodiments, the reaction can be carried out in an inert atmosphere and / or humidity controlled environment.

[0019] The disclosed method does not use glue or adhesives and also avoids the problems associated with glass bonding or other bonding techniques.

[0020] Figure 1 Schematic diagram of reaction bonded silicon carbide (RB-SiC, also called SiSiC). Figure 1 , reaction sintered SiC ceramics are produced by reactively infiltrating molten Si into a preform of SiC+carbon. During infiltration, the molten Si reacts with carbon to form additional SiC (Si+C→SiC), which bonds the structure together. The final composite material consists of the original SiC, the SiC formed by the reaction, and the residual Si.

[0021] In the manufacture of the reaction-bonded silicon carbide (RB-SiC) ceramic components described herein, a preform is used. The preform is made of a slurry (SiC+C-based binder + deionized water) and is formed into a desired shape, including internal and external features. The preform can be made into green parts and then further processed to ultimately form a finished ceramic component. In some embodiments, there are internal channels in the finished component.

[0022] Figure 2 Exemplary preforms bonded with SiC-based glue (a caulking-like mixture of SiC particles and carbon-based additives) are shown. Specifically, these preform assemblies have been reaction sintered by first gluing the two parts of the assembly and then performing a reaction sintering process to produce a ceramic assembly with internal channels. In some embodiments, the preform includes a body portion and a cover portion, such as Figure 2 shown.

[0023] Figure 2 Also shown is the microstructure of the bond line after bonding the preforms with a SiC based glue. The microstructure shows a fully dense bond line, indicating a sealed part. This allows the fluid to be used to control the temperature of the part during use in a vacuum environment.

[0024] SiC-based glue used for preform bonding can be formulated to have a caulking-like consistency. Such glue may include SiC powder, a high carbon content organic liquid, and a rheology modifier. In practice, more glue than is required is applied to the interface. This excess glue prevents any gaps in the bond line. However, the excess glue can squeeze into the channels, forming droplets of glue along the bottom, top, and / or sidewalls of the channels. Such droplets formed by the excess glue can affect the flow characteristics, especially in component designs with small channels (e.g., <1 mm, see above). Figure 3 shows a cross section of a RB-SiC flow-through component made by bonding two semi-preforms with a SiC-based glue followed by reaction sintering. Figure 3 In the figure, excess glue droplets can be seen in the channel.

[0025] Conventional reaction-sintered SiC materials with internal channels are typically assembled as follows: (1) preforms are bonded with a SiC-based glue; and (2) the preform assembly is reaction-sintered to produce a flow-through ceramic (i.e., a material with internal channels). As described above, a problem with conventional methods is that excess glue forms droplets that squeeze into the channels.

[0026] In the present disclosure, a method for manufacturing a reaction-sintered silicon carbide (RB-SiC) ceramic component containing one or more internal channels (without excess material present in the channels) is disclosed. Thus, the disclosed method does not use glue or adhesives. Instead, the method includes the steps of connecting (assembling) two or more preform parts with dry diamond powder and reaction sintering the preform parts. In the disclosed method, diamond reacts with Si (whereas SiC does not react in conventional methods). In the method, the parts become bonded due to the Si+C (diamond) → SiC reaction. The interface between the parts contains a bond line. Since the expansion of diamond when reacting to form SiC is very high, a bond line with low residual Si content (with 25% silicon or less by weight) is produced. Since there is no "glue", there are no glue drops entering the channels, so the channels are essentially clear of excess material (e.g., there is no excess silicon in the channels). Changing the time and temperature can produce different results.

[0027] Carbon can exist in many forms, such as carbon black, graphite, and diamond. Diamond is a high density form of carbon and contains more moles of carbon in a given specific volume relative to other forms of carbon. Therefore, the expansion (volume increase) in the reaction of Si + diamond → SiC is high and can fill the gaps between the preforms. The supply of silicon exceeds the amount that diamond can react with. Table 1 is a table showing the properties of various forms of carbon.

[0028]

[0029] As described above, the green body can be prepared by preparing a slurry with water and a carbon-based binder, which is formed in a mold (or cast into bricks for subsequent processing). The slurry is then frozen, dried, or both to remove the solvent and solidify the green body. A drying / carbonization process is then performed, which can occur under a nitrogen atmosphere. In some embodiments, the temperature range of this step is about 500°F to about 700°F. During the carbonization process, the carbon-based binder is decomposed.

[0030] After making the green bodies, two or more preform blocks are assembled to make the finished ceramic component. This step usually takes place in a vacuum furnace. Dry diamond powder is applied to the interface of two or more preform blocks and heated (usually with vacuum). Heating is until the melting temperature of silicon (~1,410°C) or above is reached.

[0031] When used to make components with internal channels, diamond powder is used at the interface of two or more preform blocks instead of SiC-based glue, which allows reaction sintering without excess material in the channels. Diamond powder is applied directly to the bonding surface of the two or more preform blocks, and can also be applied to the surface of the preform blocks by simple brushing (e.g., "painting" with a brush) or by other methods. Other methods of applying diamond powder include, but are not limited to: screen printing; using low vapor pressure liquids as carriers; powder coating (if the particle size of the diamond is small enough); dusting; using aerosols to tackify the surface to adhere diamonds larger than a certain size (10 μm). In some embodiments, masking can be used to prevent diamond powder from entering the channels.

[0032] In some embodiments of the disclosed method, a preform with half channels is prepared and then the bonding surface is coated with diamond powder (by brushing the powder onto the surface). Next, the half preforms are assembled and then reaction sintered. The microstructure of the bond line can then be examined. Figure 4 The steps of using diamond powder at the interface of a prefabricated part for making a component with an internal passage are shown. In some embodiments, the bonding surface includes all of the surface between two or more matching blocks (excluding any internal passage). In other embodiments, the bonding surface may include a portion of the surface between two or more matching blocks (excluding any internal passage).

[0033] For comparison, a control sample was made with nothing at the interface. To make this control, two preforms were placed on top of each other (with only air or space between them) and then processed. In this control sample, the gap was eventually filled with Si metal. The Si bond line is not ideal, and this bond may have low strength; low stiffness and / or be more susceptible to corrosion (Si is more susceptible to corrosion than SiC). Figure 5 A control sample with a reaction sintered semi-preform but without diamond at the interface is shown. Figure 5 The gap in the figure is an uneven surface resulting from machining these parts in the green state. An unacceptable Si bond line is shown. This bond is unacceptable because it is weak and the Si is susceptible to corrosion.

[0034] A further exemplary manufacturing method is generally described below, and the properties of a reaction-bonded silicon carbide (RB-SiC) ceramic component may be evaluated.

[0035] The diamond powder used at the interface can have a variety of particle sizes. In some embodiments, the diamond powder has a particle size of about 3 μm to 200 μm; in other embodiments, the diamond powder has a particle size of about 3 μm to 150 μm; about 3 μm to 100 μm; about 3 μm to 50 μm; about 10 μm to 200 μm; about 50 μm to 200 μm; or about 100 μm to 200 μm. In one embodiment, the diamond powder has a particle size of about 3 μm to 30 μm; in another embodiment, the diamond powder has a particle size of about 3 μm to 10 μm. Assuming that the time above the melting point of Si is constant, larger sizes may form less SiC.

[0036] Figure 6 The microstructure of the bond line of samples prepared with two different diamond grit sizes (6μm and 22μm) at the interface is shown. A satisfactory bonding interface (bond line) is obtained for both samples, although more reaction is seen in the 6μm sample. In this case, satisfactory means complete infiltration (i.e., no pores), and a small amount of Si (which means less corrosion in the expected environment), among other advantages.

[0037] The greater surface area of ​​6 μm diamond powder results in a higher level of Si+C→SiC reaction (more reactions), producing a bond line of SiC and diamond with little or no Si present in the bond line. To improve stiffness and corrosion resistance and to prevent Si from penetrating into any channel features, a bond line with reduced Si presence is desired.

[0038] In some embodiments, the reduction in Si is associated with 25% or less Si remaining by weight, with a lower limit of 0% Si (not detected). In other embodiments, 20% or less Si remaining by weight; 15% or less Si remaining by weight; 10% or less Si remaining by weight; 5% or less Si remaining by weight; 1% or less Si remaining by weight; 0.5% or less Si remaining by weight; or 0.1% or less Si remaining by weight. In some embodiments, the presence of silicon is not detected (0% remaining).

[0039] Silicon can also be measured in the opposite way, that is, by the amount of Si that is reacted (removed by reaction) during reaction sintering. In some embodiments, the reduction in Si is associated with the removal of 75% or less Si by weight, with a lower limit of 100% Si removal (not detected). In other embodiments, 80% or less Si by weight is removed; 85% or less Si by weight is removed; 90% or less Si by weight is removed; 95% or less Si by weight is removed; 99% or less Si by weight is removed; 99.5% or less Si by weight is removed; or 99.9% or less Si by weight is removed. In some embodiments, the presence of silicon is not detected (100% removal).

[0040] The smaller surface area of ​​22 μm diamond reacted less, producing a bond line of SiC, diamond, and residual Si. The presence of some Si may be due to the fact that the 6 μm diamond powder fits better between the grains on the bonding surface of the preform than the 22 μm diamond powder.

[0041] For example, the surface area within a given volume (or the surface available for reaction) is calculated as follows:

[0042]

[0043]

[0044]

[0045] Where SA stands for surface area and d stands for diameter. These ratios provide an indication of how reactive various particle sizes may be from strict size parameters.

[0046] For example, advantages of using diamond powder at the interface may include: 1) the ability to form bond lines in internal channel reaction-sintered ceramics without the presence of glue droplets therein (favorable for enhanced flow behavior and the ability to form components with ultra-small channel sizes); 2) the ability to form Si-free bond lines via SiC+diamond→SiC reactions (most if not all of the Si is reacted away; this is beneficial for corrosion resistance and increased stiffness, as well as preventing Si from penetrating into any channel features); and / or 3) increased manufacturing efficiency (no need to prepare SiC-based glue, no labor required to apply the glue to the preform).

[0047] This bonding technique can be used for ceramics that require internal cooling channels. Particularly valuable are applications where channel dimensions are small or Si corrosion can be a problem. Key areas include, but are not limited to, water-cooled thermal management components, water cooled semiconductor wafer chucks and electrostatic chucks, heat exchangers, Petrochem valve bodies and / or high energy laser mirrors.

[0048] As used herein, "and / or" refers to any one or more of the list connected by "and / or". For example, "x and / or y" refers to any element in the three-element set {(x), (y), (x, y)}. In other words, "x and / or y" refers to "one or both of x and y". As another example, "x, y and / or z" refers to any element in the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, "x, y and / or z" refers to "one or more of x, y and z". As used herein, the term "exemplary" refers to serving as a non-limiting example, case or illustration. As used herein, the terms "etc.", "such as" and "for example" list one or more non-limiting examples, cases or illustrations.

[0049] Although the present invention has been described with reference to certain embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the present invention without departing from the scope of the present invention. Therefore, it is intended that the present invention is not limited to the specific embodiments disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A method of manufacturing a reaction-sintered silicon carbide ceramic component having one or more internal channels, comprising: Producing SiC+carbon preform blocks with surface channels; placing diamond powder on the bonding surface of the preform block; assembling the prefabricated blocks; as well as The preform pieces are reaction sintered to produce the ceramic component having an internal channel, wherein the reaction sintering results in the formation of bond lines between the preform pieces.

2. The method of claim 1 wherein no glue or adhesive is used.

3. The method of claim 1, wherein the preform block comprises two halves of a final ceramic component.

4. The method of claim 2, wherein the preform block comprises a body portion and a cover portion. The method of claim 1 , wherein Si is reacted away from the bond line. The method of claim 4 , wherein a majority of Si is reacted away from the bond line.

7. The method of claim 6, wherein 75% or more of Si is reacted away from the bond line.

8. The method of claim 7, wherein 85% or more of Si is reacted away from the bond line.

9. The method of claim 8, wherein 95% or more of the Si is reacted away from the bond line.

10. The method of claim 9, wherein no detectable silicon is present in the bond line.

11. The method of claim 1 , wherein the one or more internal channels do not contain excess silicon.

12. The method of claim 1, wherein the diamond powder has a high surface area.

13. The method of claim 1, wherein the diamond powder has a particle size of about 3 μm to 30 μm.

14. The method of claim 13, wherein the diamond powder has a particle size of about 3 μm to 10 μm.

15. The method of claim 1, wherein the diamond powder is dry.

16. The method of claim 1, wherein no medium or carrier is used for the diamond powder.

17. The method of claim 1, wherein placing the diamond powder comprises applying the powder directly onto the preform block.

18. The method of claim 1, wherein reaction sintering the preform block comprises applying heat to melt silicon.

19. The method of claim 18, wherein applying heat occurs under vacuum.

20. A reaction-sintered silicon carbide ceramic component manufactured by the method of claim 1.

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