Method of manufacturing a solid state heater

Abstract

A solid state heater and a method of manufacturing the heater are disclosed. The heater includes a monolithic assembly that includes portions that are graphite and other portions that are silicon carbide. Electrical current is conducted through the graphite portions of the monolithic structure between two or more terminals. Silicon carbide does not conduct electricity, but is effective at conducting heat throughout the monolithic assembly. In certain embodiments, the solid state heater is generated using chemical vapor conversion (CVC). A coating can be applied to the monolithic assembly, if desired, to protect the monolithic assembly from harsh environments.

Description

Technical Field

[0001] Embodiments of this disclosure relate to a method of manufacturing a solid-state heater. Background Technology

[0002] Fabricating semiconductor devices involves multiple discrete and complex processes. In some processes, it may be advantageous to perform one or more of these processes at elevated temperatures.

[0003] For example, within an ion source, different gases can be optimally ionized at different temperatures. Larger molecules are preferably ionized at lower temperatures to ensure the formation of larger molecular ions. Other substances can be optimally ionized at higher temperatures.

[0004] Similarly, other processes in the fabrication of semiconductor devices involve raising the temperature, which can be beneficial. These raised temperatures can be achieved using heaters. In some embodiments, these heaters can be radiant heaters, such as heating lamps. In other embodiments, these heaters can be resistance heaters.

[0005] In some applications, forming the heater can be challenging. For example, the space available for the heater may be limited. Furthermore, the environment in which the heater is placed may be harsh, such as inside an arc chamber.

[0006] Therefore, it would be advantageous if a durable solid-state heater existed that could withstand harsh environments and could be formed into various shapes and sizes. Furthermore, it would be advantageous if such a solid-state heater were relatively easy to manufacture. Summary of the Invention

[0007] A solid-state heater and a method of manufacturing the heater are disclosed. The heater includes a monolithic assembly comprising a portion of graphite and other portions of silicon carbide. Current is conducted between two or more terminals through the graphite portion of the monolithic structure. Silicon carbide does not conduct electricity, but it is effective at conducting heat throughout the monolithic assembly. In some embodiments, the solid-state heater is generated using chemical vapor conversion (CVC). If desired, a coating may be applied to the monolithic assembly to protect it from harsh environmental conditions.

[0008] According to one embodiment, a solid-state heater is disclosed. The solid-state heater includes: an integral assembly having: a first portion comprising silicon carbide; and a second portion comprising graphite; wherein the second portion forms a continuous conductive path; and an electrical contact electrically connected to the continuous conductive path. In some embodiments, the continuous conductive path includes a serpentine pattern. In some embodiments, the solid-state heater includes a coating disposed on the integral assembly. In other embodiments, the coating comprises silicon carbide. In some embodiments, the front and back surfaces of the integral assembly are planar.

[0009] According to another embodiment, a method for manufacturing a solid-state heater is disclosed. The method includes: machining a graphite assembly to form a machined graphite assembly having a thin portion and a thicker portion; subjecting the machined graphite assembly to a chemical vapor conversion (CVC) process in which silicon monoxide is introduced into a processing chamber housing the machined graphite assembly, wherein the CVC process produces a monolithic assembly having a first portion in which graphite is converted into silicon carbide and a second portion in which graphite remains present; and connecting electrical contacts to the second portion. In some embodiments, the first portion is formed in a region less than a diffusion depth from the surface of the graphite assembly. In some embodiments, the second portion comprises graphite farther from either surface of the graphite assembly than the diffusion depth. In some embodiments, the thickness of the thin portion is less than or equal to twice the diffusion depth. In some embodiments, the thickness of the thicker portion is greater than twice the diffusion depth. In some embodiments, the method includes: grinding the front and / or rear surfaces of the monolithic assembly. In some embodiments, after the grinding, the front and / or rear surfaces of the monolithic assembly are planar. In some embodiments, the method further includes applying a coating to the monolithic assembly. In some embodiments, applying the coating includes subjecting the monolithic assembly to a chemical vapor deposition (CVD) process.

[0010] According to another embodiment, a method for manufacturing a solid-state heater is disclosed. The method includes: subjecting a graphite assembly to a chemical vapor deposition (CVD) process to apply a silicon carbide coating to the surface of the graphite assembly; selectively removing the silicon carbide coating from a portion of the surface to form a silicon carbide mask; subjecting the graphite assembly having the silicon carbide mask to a chemical vapor conversion (CVC) process, in which silicon monoxide is introduced into a processing chamber housing the graphite assembly having the silicon carbide mask, wherein the CVC process produces a monolithic assembly having a first portion in which graphite is converted into silicon carbide and a second portion in which graphite remains present; and connecting electrical contacts to the second portion. In some embodiments, the first portion is formed in an area not covered by the silicon carbide mask, and the second portion is formed in an area located below the silicon carbide mask. In some embodiments, the method further includes: grinding the surface of the monolithic assembly to remove the silicon carbide mask. In some embodiments, the method further includes: applying a coating to the monolithic assembly. In some embodiments, the first portion is formed in a region less than the diffusion depth from the surface of the graphite assembly, not covered by the silicon carbide mask. In some embodiments, the thickness of the graphite assembly is less than twice the diffusion depth. Attached Figure Description

[0011] For a better understanding of this disclosure, reference is made to the accompanying drawings, which are incorporated herein by reference and in which:

[0012] Figure 1 A sequence of methods for generating a solid-state heater is shown according to one embodiment.

[0013] Figure 2 Showing according to Figure 1 The illustrated embodiment is a graphite plate that can be used to generate a solid-state heater.

[0014] Figure 3 Show Figure 2 The cross-section of the graphite plate shown.

[0015] Figure 4 The image shows a cross-section of a graphite plate after a chemical vapor conversion process.

[0016] Figure 5 The image shows a cross-section of a graphite plate after the grinding process.

[0017] Figure 6 This shows a solid-state heater with electrical contacts added.

[0018] Figure 7 A sequence that can be used to generate a solid-state heater according to another embodiment is shown.

[0019] Figure 8 The image shows a cross-section of a graphite plate with a SiC coating after a chemical vapor deposition process.

[0020] Figure 9 This shows some sections after the SiC coating has been removed to create a silicon carbide mask. Figure 8 The cross-section of the graphite plate shown.

[0021] Figure 10 This shows the process after chemical vapor phase conversion. Figure 9 The cross-section of the integrated component is shown.

[0022] Figure 11 Showing the results after the grinding process Figure 10 The cross-section of the integrated component is shown.

[0023] Figure 12 Showing the results after the chemical vapor deposition process Figure 11 The cross-section of the integrated component is shown.

[0024] Figure 13 A simulated thermal diagram of a solid-state heater is shown. Detailed Implementation

[0025] As described above, heaters are used throughout the semiconductor fabrication process. This disclosure describes a solid-state heater constructed as a single, monolithic assembly. Throughout this disclosure, "monolithic assembly" is defined as a single, integral assembly comprising both graphite and silicon carbide. This definition excludes structures created by combining different components together or otherwise attaching two different components to each other.

[0026] Figure 1 A series of processes that can be used to produce solid-state heaters are illustrated. First, as shown in box 100, a graphite assembly is machined to produce thin and thicker portions. The graphite assembly can be of any shape, such as rectangular, circular, elliptical, or another suitable shape. In some embodiments, the graphite assembly can be a graphite plate having any length and width. In other words, the size of the graphite assembly is not limited by this disclosure. Furthermore, the thickness of the graphite assembly is not limited by this disclosure. For example, in some embodiments, the graphite assembly is a graphite plate having a thickness of 2 mm or greater. In this disclosure, a "plate" is a rectangular prism in which the thickness is less than the length and width.

[0027] As described above, the graphite assembly is machined to create thin and thick portions. In some embodiments, the thin portion may have a thickness less than or equal to twice the diffusion depth of the chemical vapor conversion (CVC) process. This diffusion depth is a function of the porosity of the graphite assembly, the duration of the CVC process, and other factors. For example, in some embodiments, the diffusion depth may be approximately 700 micrometers. In this embodiment, the maximum thickness of the thin portion may be 1.4 millimeters. The thicker portion is defined as a portion of the graphite assembly having a thickness greater than twice the diffusion depth.

[0028] The thicker portion of the machined graphite assembly serves as the conduction path for current to flow through the solid-state heater. In some embodiments, the graphite assembly is machined such that the thicker portion forms a serpentine shape, but other shapes are also possible.

[0029] Figure 2 A graphite assembly 200 in the form of a graphite plate is shown. In this figure, a thin portion 210 has been formed as a shallow channel on one surface of the graphite assembly 200. This can be done using standard milling practices. In other embodiments, shallow channels can be machined into both surfaces of the graphite assembly. The unmachined portions of the graphite assembly 200 may be referred to as the thicker portions 220. It should be noted that in this embodiment, the thicker portions 220 of the graphite assembly 200 form a serpentine pattern. In this figure, the thin portion 210 is less than 1.4 mm, while the thicker portion 220 is 2.0 mm. It should be noted that other dimensions may also be used, as long as the thin portion 210 is less than twice the diffusion depth and the thicker portion 220 is greater than twice the diffusion depth.

[0030] Reference Figure 1 After the graphite component has been machined, it undergoes a chemical vapor conversion (CVC) process, as shown in box 110. In this CVC process, the machined graphite component 200 is placed in a processing chamber. Silica (SiO) is introduced into the processing chamber. The silica reacts with the graphite component as shown in the following equation: SiO + 2C → SiC + CO. In other words, one silica molecule reacts with two carbon atoms in the machined graphite component 200 to form a silicon carbide molecule and release a carbon monoxide molecule. This process continues until no exposed carbon remains in the machined graphite component 200. The diffusion depth refers to the depth to which the graphite component, measured from the outer surface, has been converted into silicon carbide. In other words, when the depth is greater than the diffusion depth, the graphite component will retain graphite. Figure 3 Showing the process before chemical vapor phase conversion Figure 2 The cross-section of the graphite component 200 shown is illustrated. Figure 4 This shows the process after chemical vapor phase conversion. Figure 3The mechanical component is shown. It should be noted that the mechanical graphite component has been transformed into a monolithic component 300, which has a first portion 310 of silicon carbide and a second portion 320 containing graphite. Similarly, the thickness measured from the front surface to the second portion 320 is defined as the diffusion depth 315. It should be noted that if the thin portion 210 is less than twice the diffusion depth 315, the entire thin portion 210 would constitute the first portion 310 containing silicon carbide. However, since the thicker portion 220 is more than twice the diffusion depth 315, the interior of the thicker portion 220 still retains the second portion 320 containing graphite. In this figure, the second portion 320 has a thickness of approximately 600 micrometers.

[0031] It should be noted that by placing shallow channels, a first part 310 can be generated to separate the two second parts 320 from each other.

[0032] Silicon carbide and graphite have very different properties. Silicon carbide has a resistivity 100 times that of graphite. Specifically, silicon carbide has a resistivity of approximately 10⁻⁶. 2 Ohm-cm to 10 6 Resistivity in ohm-cm (depending on purity). Graphite has a resistivity of about 0.01 ohm-cm. Graphite has a thermal conductivity of up to about 85 W / mK, while chemical vapor conversion silicon carbide has a thermal conductivity of about 170 W / mK.

[0033] Next, as Figure 1 As shown in box 120, the monolithic component 300 is ground to the desired thickness as needed. This is also... Figure 5 As shown in the diagram. In some embodiments, the monolithic component 300 is ground to a depth such that the second portion 320 is exposed on one or both surfaces of the monolithic component 300. Figure 5 In this process, the front surface has been ground to expose the second portion 320, while the back surface has been ground to a smaller depth. In some embodiments, both the top and back surfaces are ground to be planar.

[0034] Next, as shown in box 130, electrical contacts are added to the integral assembly 300 to transform the integral assembly 300 into a solid-state heater. In some embodiments, holes are drilled into the second portion 320 at at least two locations. In some embodiments, the second portion 320 forms a continuous conductive path, and electrical contacts are disposed at opposite ends of this continuous conductive path. Figure 6 A monolithic assembly 300 is shown, wherein a second portion 320 forms a serpentine path. A first portion 310 is disposed between adjacent portions of the serpentine path. Electrical contacts 330 in the form of drill holes are formed at opposite ends of the serpentine path.

[0035] Finally, as shown in box 140, a coating is applied to the monolithic component 300 as needed. For example, in one embodiment, a silicon carbide layer may be deposited on the surface of the monolithic component 300. This deposition may be performed using a chemical vapor deposition (CVD) process or any suitable process. The coating is not limited to silicon carbide. In other embodiments, different materials may be used as the coating. The coating may be used to electrically isolate the exposed second portion 320 from the external environment.

[0036] It should be noted that this method can be useful when the total thickness of the solid-state heater is desired to be greater than twice the diffusion depth or when a thick conductive path is desired. It should also be noted that the thickness of the thicker portion 220 is not limited by this method.

[0037] although Figures 1 to 6 This illustrates one method for generating a solid-state heater; however, other methods utilizing chemical vapor phase conversion processes may also be used.

[0038] For example, in another embodiment, masks are applied to some portions of the graphite assembly to create a monolithic assembly. Figure 7 A series of processes for producing a solid-state heater using this method are illustrated. First, as shown in box 500, a silicon carbide coating is applied to at least one surface of a graphite assembly. The graphite assembly may be planar. For example, the graphite assembly may be a graphite plate. In some embodiments, a chemical vapor deposition (CVD) process is used to deposit the silicon carbide coating on top of the graphite assembly 600. Figure 8 An example is shown in which a silicon carbide coating 605 is disposed on the front surface of a graphite assembly 600.

[0039] Next, as shown in box 510, some portions of the silicon carbide coating 605 are selectively removed to produce a silicon carbide mask 607. The silicon carbide coating 605 can be removed using, for example, a polishing process. Figure 9 An example of a graphite assembly 600 having a silicon carbide mask 607 is shown.

[0040] Next, the graphite assembly 600 with silicon carbide mask 607 is subjected to a chemical vapor conversion process, as shown in box 520. Figure 10 As shown, after the chemical vapor conversion process is completed, a monolithic component 700 is generated. The monolithic component 700 has a first portion 710 containing silicon carbide and a second portion 720 containing graphite. It should be noted that in this embodiment, the area of ​​the graphite component 600 disposed under the silicon carbide mask 607 is the second portion 720, while the exposed area of ​​the graphite component 600 is the first portion 710. It should be noted that in some embodiments, the initial thickness of the graphite component 600 may be less than twice the diffusion depth to ensure that the first portion 710 extends through the thickness of the monolithic component 700.

[0041] Next, as shown in box 530, the monolithic assembly 700 may undergo a polishing process to remove the silicon carbide mask 607 from the front surface. Therefore, after the polishing process, the monolithic assembly 700 may be a planar assembly having a first portion 710 and a second portion 720 disposed on one surface, such as... Figure 11 As shown in the image.

[0042] Next, as shown in box 540, electrical contacts are added to the integral assembly 700 to transform the integral assembly 700 into a solid-state heater. In some embodiments, holes are drilled into the second portion 720 at at least two locations. In some embodiments, the second portion 720 forms a continuous conductive path, and electrical contacts are disposed at opposite ends of this continuous conductive path. This continuous conductive path may be a serpentine path. A first portion 710 is disposed between adjacent portions of the serpentine path. Electrical contacts, which may be in the form of drill holes, are formed at opposite ends of the serpentine path.

[0043] Finally, as shown in box 550, a coating is applied to the monolithic component 700 as needed. For example, in one embodiment, a silicon carbide layer 730 may be deposited on at least one surface of the monolithic component 700, such as... Figure 12 As shown in the diagram. This deposition can be performed using a chemical vapor deposition (CVD) process or any suitable process. The coating is not limited to silicon carbide. In other embodiments, different materials can be used as the coating. The coating can be used to electrically isolate the exposed second portion 720 from the external environment.

[0044] It should be noted that this process can be useful when the total thickness of the desired solid-state heater is less than twice the diffusion depth.

[0045] Therefore, a solid-state heater is disclosed. The solid-state heater includes a monolithic assembly having a first portion comprising silicon carbide and a second portion comprising graphite. This monolithic assembly can be manufactured using a chemical vapor conversion process. The second portion forms a continuous conductive path. Electrical contacts are provided at opposite ends of this continuous conductive path. In some embodiments, the continuous conductive path is formed as a serpentine path. In some embodiments, a coating is applied to the outer surface of the monolithic assembly to isolate the monolithic assembly from the external environment.

[0046] This system offers several advantages. First, it allows for the creation of a single, integrated assembly that can be used as a heater. The combination of materials within this integrated assembly ensures that current is conducted through the graphite. However, due to the relatively high thermal conductivity of silicon carbide, heat can diffuse throughout the entire heater. Figure 13 Show Figure 6The simulated thermal diagram of the solid-state heater is shown. The second part, as the hotter part of the solid-state heater, is clearly visible; however, heat is also distributed to the first part, resulting in a temperature change of less than 45°C across the surface of the solid-state heater.

[0047] Furthermore, the process for manufacturing solid-state heaters does not limit the conductive paths created within them. For example, conductive paths can have varying widths to create hot and cold areas if desired. Additionally, paths of any desired shape can be created. Moreover, two or more conductive paths can be created within the same solid-state heater. These paths can be completely separated by individual electrical contacts or can share electrical contacts. In practice, these conductive paths can have different lengths and widths, thereby creating different temperature profiles for each conductive path.

[0048] Furthermore, due to the high flexural strength, high tensile strength, and high modulus of elasticity of silicon carbide, using a monolithic assembly increases the rigidity and structural integrity of the solid-state heater. Therefore, silicon carbide protects the less rigid graphite contained within the monolithic assembly.

[0049] The solid-state heaters disclosed herein can be used in various locations within an ion implantation system. For example, the solid-state heater can be located in or near an arc chamber. Alternatively, the solid-state heater can be used as a heating chamber liner.

[0050] In addition, solid-state heaters can be used in other applications. It is estimated that solid-state heaters can be used in atmospheric or oxidizing environments at temperatures up to 900°C. In inert environments (e.g., vacuum or argon), temperatures can reach up to 2500°C. This allows solid-state heaters to be used in other applications where high temperatures are utilized. For example, solid-state heaters can be used in metal processing (e.g., casting and forging). Furthermore, solid-state heaters can be used in other applications that utilize high temperatures (e.g., crystal growth and kilns).

[0051] The scope of this disclosure is not limited to the specific embodiments described herein. In fact, from the foregoing description and accompanying drawings, it will be apparent to those skilled in the art that various other embodiments and modifications of this disclosure, in addition to those described herein, are also possible. Therefore, these other embodiments and modifications are all intended to fall within the scope of this disclosure. Furthermore, although this disclosure has been set forth herein for a specific purpose, in a specific setting, and in the context of a specific implementation, those skilled in the art will recognize that the utility of this disclosure is not limited thereto and that it can be advantageously practiced for any number of purposes and in any number of settings. Therefore, the foregoing claims should be understood in light of the full scope and spirit of this disclosure as set forth herein.

Claims

1. A method for manufacturing a solid-state heater, comprising: The graphite components are machined to produce machined graphite components with thin and thick sections; The mechanical graphite assembly is subjected to a chemical vapor conversion process in which silicon monoxide is introduced into a processing chamber containing the mechanical graphite assembly, wherein the chemical vapor conversion process produces a monolithic assembly having a first portion in which graphite is converted into silicon carbide and a second portion in which graphite remains present. as well as Connect the electrical contacts to the second part. The thickness of the thin portion is less than or equal to twice the diffusion depth, and the thickness of the thicker portion is greater than twice the diffusion depth.

2. The method of claim 1, wherein the first portion is generated in a region less than the diffusion depth from the surface of the graphite assembly, and wherein the second portion comprises graphite farther than the diffusion depth from either surface of the graphite assembly.

3. The method according to claim 1, further comprising: The front and / or rear surfaces of the integrated component are ground.

4. The method of claim 3, wherein after the grinding, the front surface and / or the rear surface of the integral assembly is planar.

5. The method according to claim 1, further comprising: A coating is applied to the integrated component.

6. The method of claim 5, wherein applying the coating comprises subjecting the integral component to a chemical vapor deposition process.

7. A method for manufacturing a solid-state heater, comprising: The graphite assembly is subjected to a chemical vapor deposition process to apply a silicon carbide coating to the surface of the graphite assembly. The silicon carbide coating is selectively removed from certain portions of the surface to form a silicon carbide mask; The graphite assembly having the silicon carbide mask is subjected to a chemical vapor conversion process in which silicon monoxide is introduced into a processing chamber containing the graphite assembly having the silicon carbide mask, wherein the chemical vapor conversion process produces a monolithic assembly having a first portion in which graphite is converted into silicon carbide and a second portion in which the graphite remains. as well as Connect the electrical contacts to the second part. The initial thickness of the graphite component is less than twice the diffusion depth.

8. The method of claim 7, wherein the first portion is formed in a region not covered by the silicon carbide mask, and the second portion is formed in a region located below the silicon carbide mask.

9. The method according to claim 7, further comprising: The surface of the integrated component is ground to remove the silicon carbide mask.

10. The method of claim 7, further comprising: A coating is applied to the integrated component.

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