SILICON CARBIDE BODY WITH LOCALIZED DIAMOND REINFORCEMENT | Patent Publication Number 20230150885
US 20230150885 A1Jiwen WANG
Jon COPPOLA
Nicholas COOMBS
A reaction-bonded silicon carbide (SiC) body is produced by: providing a preform including ceramic elements and carbon, and one or more surface features; providing a powder which includes diamond particles and carbon; locating the powder in the surface feature(s); and infiltrating the preform and the powder with molten silicon (Si) to form reaction-bonded SiC in the preform, and to form reaction-bonded SiC coatings on the diamond particles. The present disclosure also relates to a device/component which includes: a main body portion and discrete elements located at least partially within the main body portion. The main body portion may include reaction-bonded SiC and Si, but not diamond, while the discrete elements include diamond particles, reaction-bonded SiC coatings surrounding the diamond particles, and Si. According to the present disclosure, diamond may be advantageously located only where it is needed.
1. A method of making a reaction-bonded silicon carbide body, comprising: providing a preform including ceramic particles and carbon, wherein the preform includes one or more surface features; providing a powder, wherein the powder includes diamond particles and carbon; locating the powder in the one or more surface features; infiltrating the preform and the powder with molten silicon, to form reaction-bonded silicon carbide in the preform, and to form reaction-bonded silicon coatings on the diamond particles. 11-12. (canceled) 16. A vacuum wafer chuck, comprising: a main body portion, including reaction-bonded silicon carbide and elemental silicon, and not including diamond; and discrete pins for supporting a semiconductor wafer, wherein the pins are located at least partially within the main body portion, and wherein the pins include diamond particles, reaction-bonded silicon carbide coatings surrounding the diamond particles, and elemental silicon.
This application is a divisional of U.S. patent application Ser. No. 17/248,309 filed Jan. 19, 2021. The aforementioned application is hereby incorporated by reference in its entirety.
U.S. Pat. No. 9,469,918, issued Oct. 18, 2016, refers to a multilayer substrate which includes a diamond layer and a composite layer, where the diamond layer is grown on the composite layer, and where the composite layer includes diamond and silicon carbide (SiC), and, optionally, silicon (Si). According to U.S. Pat. No. 9,469,918, the composite layer may be formed by mixing diamond particles with SiC particles or a SiC-forming precursor. The entire disclosure of U.S. Pat. No. 9,469,918 is expressly incorporated herein by reference.
United States Patent Application Publication No. 2021/0002534, based on International Application No. PCT/EP2019/056457, filed Mar. 14, 2019, refers to SiC-bound hard diamond material particles. According to United States Patent Application Publication No. 2021/0002534, diamond particles may be embedded in a matrix of reaction-formed SiC. The entire disclosure of United States Patent Application Publication No. 2021/0002534 is expressly incorporated herein by reference.
The present disclosure relates to a method of making a reaction-bonded silicon carbide (SiC) body, where the method includes: providing a preform including ceramic elements and carbon, wherein the preform includes one or more openings; providing a powder, wherein the powder includes diamond particles and carbon; locating the powder in the one or more surface features; and infiltrating the preform and the powder with molten silicon (Si), to form reaction-bonded (SiC) in the preform, and to form reaction-bonded SiC coatings on the diamond particles.
The present disclosure also relates to a reaction-bonded SiC body which includes: a main body portion and discrete elements located at least partially within the main body portion. According to one aspect of the present disclosure, the main body portion may include reaction-bonded SiC and elemental Si, but not diamond, while the discrete elements include diamond particles, reaction-bonded SiC coatings surrounding the diamond particles, and elemental Si. The present disclosure is applicable to a variety of devices, including, for example, a vacuum wafer chuck.
According to the present disclosure, reaction-bonded SiC parts may be provided with localized diamond reinforcement; diamond may be located where it is needed but only where it is needed, which is advantageous because, although diamond has many desirable characteristics, it may be difficult to machine (cut, grind, shape, etc.), and it may be expensive. Thus, if desired, a SiC+carbon preform may be machined to have surface features such as openings, recesses, trenches, cavities, or dimples. The surface features are at least partially filled with diamond powder. Then, the assembly is reactivity infiltrated with molten Si. The result is a dense, reaction-bonded SiC body with diamond reinforcement at only select, desirable locations.
The same reference numbers or other feature designators are used in the figures to designate the same or similar features.
The material 40 illustrated in
Diamond has many desirable characteristics for a variety of useful applications. Such characteristics include extremely high hardness for wear resistance, very low coefficient of friction for sliding applications, very high stiffness (Young's modulus) for structural applications, and extreme thermal stability (high thermal conductivity and low coefficient of thermal expansion (CFE)). Tables 1 through 3 list desirable characteristics of diamond compared to other materials:
Then, after the trenches 106 are filled with diamond powder, molten Si is simultaneously infiltrated into the body 102 and the trenches 106 to create the material 20 illustrated in
In other words, the illustrated multi-component block 100 may have hard, thermally-conductive diamond-reinforced composite material 40 where needed (and only where needed), and reaction-bonded SiC 20 (without diamond) in other areas for ease of machining. The body 102 and the features 104 illustrated in
In the illustrated example, the reactions that occur in the trenches 106, which involve Si+diamond, are different from the reactions that occur simultaneously elsewhere in the body 102, which involve Si+carbon but no diamond. As a result, the residual elemental Si content in the diamond-reinforced region (within the trenches 106) is lower than in the rest of the block 100. For example, the residual elemental Si in the diamond-reinforced region within the trenches 106 may be about 6.8% while the residual Si in the Si—SiC (and no diamond) region may be about 23.2%.
The lower residual Si content in the diamond-reinforced region may yield improved properties (hardness, stiffness, inertness, etc.), but the combination of diamond particles and low elemental Si content may make machining especially difficult, such that it may be especially advantageous to locate the diamond-containing features 104 only where needed. However, avoiding difficult machining is only one of many reasons why localizing diamond-containing features is advantageous. Another advantage of providing diamond reinforcement only where it can be put to effective use is reduced cost. In other words, it is advantageous to use high-cost diamond powder only where it is needed.
Moreover, although the body 206 has a continuous region formed of monolithic reaction bonded SiC, the discrete (that is, separated) positioning of the diamond-reinforced pins 202 should prevent bi-metallic strip non-uniformity. In other words, an advantageous feature of providing localized diamond-containing elements according to the present disclosure is that bi-metallic strip stresses can be prevented.
A method of making the reaction-bonded SiC body 206 (
The openings 300 are then filled with a suitable amount, for example, about 30 μm, of powder 304 which contains diamond particles 42, and then the entire assembly (the dimpled preform 302 and the powder 304 within the dimples 300) is subjected to a reaction bonding process, that is, infiltrated with molten Si. The reaction bonding process converts the material of the preform 302 to the material 20 illustrated in
Referring now to
Referring now to
The present disclosure may be applicable to a variety of semiconductor wafer handling components, including vacuum wafer chucks, electrostatic chucks, wafer arms/end effectors, and susceptors. The present disclosure may also be applicable to a variety of other applications, especially where low wear, low friction, high mechanical stiffness, and/or extreme thermal stability in local areas is/are desired, including optics and optical mounts, thermal management/heat sink devices, high energy laser (HEL) components, bearing seals, cylinder liners, gun barrels, lapping/grinding substrates, and artificial joints (hips, knees, etc.).
The present disclosure is applicable to a reaction-bonded SiC vacuum wafer chuck with standing-proud diamond-reinforced pins for wafer contact (to provide high wear resistance and stiffness, low friction, and high purity) while all areas requiring machining are free of diamond for ease of manufacture. The present disclosure is not limited, however, to the devices and processes described herein. The present disclosure may also be applicable to a reaction-bonded SiC heat sink with local areas of diamond reinforcement only at locations (e.g., directly under a die) where high heat flux is desired to maximize performance, while the rest of the device does not contain diamond so as to be more easily machinable during a manufacturing process. Moreover, the present disclosure may be applicable to a reaction-bonded SiC lapping/grinding plate with local diamond reinforcement at a wear face, where the reinforcing elements are in the form of discrete buttons (or other shapes) while other portions of the device are free of diamond for ease of machining.
What have been described above are examples. This disclosure is intended to embrace alterations, modifications, and variations to the subject matter described herein that fall within the scope of this application, including the appended claims. As used herein, the term “includes” means including but not limited to. The term “based on” means based at least in part on. Additionally, where the disclosure or claims recite “a,” “an,” “a first,” or “another” element, or the equivalent thereof, it should be interpreted to include one or more than one such element, neither requiring nor excluding two or more such elements.
What is claimed as new and desired to be protected by Letters Patent of the United States is: