Flared baffle liner for chemical vapor deposition system

Abstract

A baffle liner for a chemical vapor deposition (CVD) system includes an upper portion having a cylindrical shape and a lower portion having an outwardly flared shape. The outwardly flared shape reduces deposition within the reaction chamber by providing an outwardly sloping wall surface that occupies the horizontal gap between the inner and outer liner contained within the reaction chamber.

Description

Cross-reference to related applications

[0001] This application claims priority and benefit to U.S. Patent Application Serial No. 63 / 555,738, filed February 20, 2024, the entire contents of which are expressly incorporated herein by reference. Technical Field

[0002] This technology generally relates to semiconductor manufacturing technology, and more specifically to chemical vapor deposition processes and related systems having a flared baffle liner for restricting the migration of reactants from the reaction volume outward. Background Technology

[0003] Some semiconductor manufacturing processes may require complex techniques to grow epitaxial layers to form multilayer semiconductor structures used to fabricate high-performance devices such as light-emitting diodes (LEDs), laser diodes, optical detectors, power electronics, and field-effect transistors. In these processes, epitaxial layers are grown using a process collectively known as chemical vapor deposition (CVD). One type of CVD process is called metal-organic chemical vapor deposition (MOCVD). In MOCVD, reactive gases are introduced into a controlled environment within a reaction chamber, allowing the reactive gases to react on a substrate (often called a "wafer") to grow a thin epitaxial layer.

[0004] During epitaxial layer growth, multiple process parameters, such as temperature, pressure, and gas flow rate, are controlled to achieve the desired quality of the epitaxial layer. Different layers are grown using different materials and process parameters. Suitable substrates for this reaction can be wafers with metallic, semiconductor, and / or insulating properties.

[0005] In a CVD process chamber based on a rotating disk reactor architecture, one or more wafers are placed within a rapidly rotating disk (often referred to as a "wafer carrier"), exposing the top surface of each wafer. This ensures that the top surface of the wafer is uniformly exposed to the atmosphere within the reaction chamber for semiconductor material deposition. The wafer carrier is typically fabricated from a highly thermally conductive material (such as graphite) and is usually coated with a protective layer made of materials such as silicon carbide or tantalum carbide. Each wafer carrier has a set of circular recesses or cavities on its top surface for placing the individual wafers. As the wafer carrier rotates, reactive gases are introduced into the chamber from a gas distribution device located upstream of the wafer carrier. The flowing gas proceeds downstream towards the wafer carrier and wafers, ideally exhibiting laminar flow.

[0006] Traditionally, reactor systems are designed with cylindrical baffles with a large horizontal gap between their outer side and the reactor jar (outer shell). While the airflow is directed downwards and towards the exhaust port, reactants can escape through this large gap (via diffusion, backflow, etc.) and reach the reactor periphery. These reactants can then generate particulate matter through airflow recirculation, condensation, etc., creating defects at various locations within the reactor (e.g., within the passageways, along the reactor walls), which can then migrate to the wafer surface. Defects on the wafer significantly reduce device yield. Therefore, it is necessary to reduce the amount of reactants and particulate matter that can penetrate the horizontal gap. Summary of the Invention

[0007] This disclosure provides a baffle liner that overcomes the defects of conventional baffle liners, and in particular, the shape of the baffle liner greatly reduces deposition growth in horizontal gaps.

[0008] More specifically, a baffle liner for a chemical vapor deposition (CVD) system includes an upper portion having a cylindrical shape and a lower portion having an outwardly flared shape. The outwardly flared shape reduces deposition by providing an outwardly sloping wall surface to occupy the horizontal gap between the inner and outer liners. The flared shape maintains a desired radial dimension in the upper portion while providing the dimension required to achieve the desired effect in the lower portion.

[0009] Therefore, the chemical vapor deposition (CVD) system includes a reaction chamber and multiple walls, each wall including an outer liner and an inner liner concentric with and radially inward of the outer liner. A first annular space is defined between the outer liner and the inner liner. A baffle liner is disposed between the outer liner and the inner liner and is movable between a raised position and a lower position. The baffle liner includes an upper portion having a cylindrical shape and a lower portion having an outwardly flared shape.

[0010] The baffle liner has an elevated position including an operating position and a lowered position including a non-operating position, which allows the wafer carrier to be inserted into or removed from the reaction chamber. Attached Figure Description

[0011] A more complete understanding of this disclosure can be achieved by reading the following detailed description of various embodiments in conjunction with the accompanying drawings, in which: Figure 1 This is a partial cross-sectional view of a CVD system, in which the flared baffle liner is shown in an elevated position; Figure 2 This is a partial cross-sectional view of a CVD system, in which the flared baffle liner is shown in a lowered position; Figure 3 This is a magnified view of the flared baffle lining relative to the outer and inner linings; Figure 4These are top and side perspective views of the flared baffle lining; and Figure 5 This is a side view of the flared baffle lining.

[0012] While various modifications and variations can be made to the embodiments of this disclosure, their specific details are illustrated by way of example in the accompanying drawings and will be described in detail herein. However, it should be understood that this disclosure is not intended to limit it to the specific embodiments described. Rather, it is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter defined by the appended claims. Detailed Implementation

[0013] Reference Figures 1 to 5 This paper illustrates a chemical vapor deposition (CVD) system 100, which includes a reaction chamber 101 (sometimes referred to herein as a "process chamber" or "reactor") configured to define a process environment space. The reactor region of system 100 is typically formed of vacuum-grade stainless steel or other suitable metal. The reaction chamber 101 is typically defined by a cylindrical wall having an upper end and a lower end away from the upper end. Figures 1 to 2 This is a partial view of system 100, depicting half of system 100 to illustrate the teachings of this disclosure.

[0014] System 100 includes a base plate 110, which represents the bottom of system 100. The base plate 110 has a plurality of through holes to allow certain components, such as drive shafts that rotate wafer carrier 115, to pass through. As is known in the art, wafer carrier 115 accommodates one or more wafers for processing.

[0015] Multiple linings Between the wafer carrier 115 and the base plate 110, there are different components defining the wall structure of the system 100. For example, as described herein, multiple liners and an outer casing structure may be present. More specifically, to prevent undesirable reactions with the chamber body (reaction chamber 101), liners are used to shield and isolate portions of the metal chamber components from the processing area. In the illustrated embodiment, the system 100 includes multiple liners 120, 130 that shield the processing volume (reaction chamber 101) from the influence of the metal wall surrounding the processing volume (reaction chamber 101). This metal wall may include a reactor casing (welded component), generally indicated as 140, and the multiple liners 120, 130 are located radially inside the reactor casing 140. The multiple liners 120, 130 and the reactor casing 140 are concentric with each other, wherein liner 120 is an inner liner 120 and liner 130 is an outer liner 130. These three structures 120, 130, and 140 may be in a ring shape, with the inner liner 120 and the outer liner 130 spaced apart by a first distance. The inner liner 120 is located close to (adjacent to the wafer carrier 115 and / or related processing equipment).

[0016] Figure 3 This is a partial enlarged view of the top regions of the three structures 120, 130, and 140. In one embodiment, the height of the inner liner 120 is greater than the height of the outer liner 130 and the reactor outer cover 140, and the height of the outer liner 130 may be less than the height of the reactor outer cover 140.

[0017] airflow flange An airflow flange 150 is provided to introduce the reaction gas into the reaction chamber 101 at a specified location. Therefore, the airflow flange 150 defines the flow path for introducing the reaction gas into the reaction chamber 101. The airflow flange 150 is located in the upper region of the reaction chamber 101.

[0018] Cold plate The reaction chamber 101 has one or more gas injectors for injecting one or more gases into the reaction chamber 101. In one embodiment, a gas dispensing and injection head may be provided, which includes a manifold assembly, which may be formed of a single plate or more typically of multiple plates stacked on top of each other. An element 160, referred to herein as a “cold plate” or “diffuser,” covers the downstream surface of the manifold assembly. The cold plate 160 may be provided with coolant passages connected to a circulating coolant source. The cold plate defines the downstream surface of the dispensing and injection head. The cold plate 160 defines a plurality of first gas inlets, which define ports communicating with the interior of the reaction chamber 101. It should be understood that other types of gas injectors may be used.

[0019] Flared baffle lining According to this embodiment, a flared baffle liner 200 is provided, which in the raised position ( Figure 1 ) and lower position ( Figure 2 The flared baffle liner 200 is disposed in the annular space between the inner liner 120 and the outer liner 130.

[0020] System 100 includes multiple passage regions designed to provide space for the movement of components, such as the insertion and removal of wafer carriers. For example, system 100 includes a first passage region 230 located radially outside the cold plate 160. This first passage region 230 is a volume within the passage channel. A second region 240 exists radially outside the flared baffle liner 200 but within the reactor casing 140. This second region 240 is configured and designed to accommodate the insertion and removal of wafer carriers 115. This second region 240 represents a volume outside the baffle but prior to the passage channel.

[0021] Traditional baffle liners do not have a flared bottom section; instead, they are straight and cylindrical, as in the case of the upper part 210. This results in a large horizontal gap (annular) between the outer side of the baffle and the reactor casing 140.

[0022] However, the applicant observed that this type of conventional baffle liner allows deposition growth to occur in and around the second region 240, as well as in other regions. Specifically, the flared baffle liner 200 disclosed herein is designed to prevent backflow into the interior of the passageway 230 and the volume (region 240) between the baffle and the outer casing. Typically, significant deposition occurs in certain areas of the first passageway 230 and the second region 240.

[0023] In other words, the straight-walled characteristics of conventional baffle liners allow for deposition growth because, as the gas flow is directed downwards and toward the exhaust port, reactants may escape (through diffusion and backflow) through this gap (second passage region 240) and reach the periphery of the reactor (system 100). These reactants can then generate particulate matter through gas recirculation, condensation, etc., and create defects at many locations in the reactor (passage channels, reactor walls), which can transfer to the wafer surface. Numerous particles and parasitic deposits have been observed within passage region 240. The adverse effect is that deposits in and around the second passage region 240 can contaminate the wafer during insertion and removal of the wafer carrier 115. Defects on the wafer significantly reduce device yield.

[0024] This is undesirable, and therefore such deposition growth needs to be greatly reduced, especially in the cross-sectional area where the wafer is located during operation.

[0025] More specifically, an objective of this disclosure and system 100 is to prevent substances that are prone to parasitic growth from entering the passage region 240 via convection and back diffusion. Further, an objective of this disclosure and system 100 is to provide independent control over the lateral / passage purging and to provide temperature control within the passage region 240.

[0026] The design of the flared baffle liner 200 achieves these objectives. More specifically, the flared baffle liner 200 includes a top edge 202 and an opposing bottom edge 204. The flared baffle liner 200 has an upper portion 210 terminating at the top edge 202 and a lower portion 220 terminating at the bottom edge 204. The upper portion 210 has a cylindrical shape, while the lower portion 220 has a flared (sloping) shape. As shown, the lower portion 220 has an outwardly flared shape, thereby defining a flared or angled end section. Therefore, the lower portion 220 flares outward toward the outer liner 130, and the bottom edge 204 may be adjacent to the outer liner 130. This results in the outer diameter of the flared baffle liner 200 at the bottom edge 204 being larger than the outer diameter at the top edge 202. The angle of the lower flare 220 is less than 90 degrees and can be between 40 and 60 degrees, for example 45 degrees (measured relative to the reference horizontal plane (the horizontal plane including the bottom edge of the lining)).

[0027] In one embodiment, an angled end section (lower flared portion 220) extends from the cylindrical section (upper portion 210), maintaining the same overall height as a conventional cylindrical baffle / liner. The flared section (lower flared portion 220) is angled outward and blocks significant amounts of material from migrating into the external reactor volume. By restricting reactant migration outward from the reaction volume, the tendency to deposit is significantly reduced, thereby improving the defect rate.

[0028] As shown in the figure, the height of the upper part 210 is much greater than the height of the lower part 220 because the flared part of the flared baffle liner 200 only occupies a small portion of the entire baffle liner.

[0029] It should be understood that the flared baffle liner 200 can be formed as a single part or as two parts. For example, when the flared baffle liner 200 is formed as two parts, the (cylindrical) upper portion 210 is formed as the first part, and the (flared) lower portion 220 is formed as the second part. In one embodiment, the upper portion 210 may be formed of molybdenum, and similarly, the lower portion 220 may be formed of molybdenum. Alternatively, the flared baffle liner 200 may be made as a single part and made of different refractory metals. Fasteners (e.g., rivets) can be used to connect the two parts, or other techniques can be used.

[0030] The movement of the flared baffle liner 200 is achieved using conventional means, such as a motor (not shown) operatively coupled to the flared baffle liner 200. For example, a stepper motor can be used to precisely move the flared baffle liner 200 between a raised position and a lowered position.

[0031] As mentioned above, such as Figures 1 to 2As shown, the flared baffle liner 200 moves between a raised position and a lowered position. The raised position is where the flared baffle liner 200 is positioned, allowing it to reduce deposition buildup in passage areas (e.g., passage areas 230 and 240). The lowered position allows the wafer carrier to be removed. Therefore, the raised position of the flared baffle liner 200 is its normal operating position, while the lowered position is a non-operating position used to define an open space to allow the wafer carrier to be inserted into or removed from the reaction chamber 101.

[0032] Therefore, the flared baffle liner 200 is configured to move within the reactor to perform multiple functions. The applicant has found that the flared design provides improved results in resisting reactants and particles compared to simply using, for example, larger conventional baffles; moreover, the flared baffle liner 200 also meets and achieves additional requirements that determine the upper and lower configuration of the liner 200.

[0033] Example Based on modeling, the applicant observed that when using a conventional straight baffle liner in a CVD system, the deposition rate was 3 micrometers per hour (μm / hr) (within the second passage region 240). In contrast, when using a flared baffle liner 200 in system 100, the deposition rate was 0.25 micrometers per hour. This represents a reduction in deposition rate of over 91%, resulting in a significant decrease in the amount of material deposited within the same timeframe.

[0034] baffle The disclosed reactor may include those shown in the figure (e.g.) Figure 1 The baffle assembly 250 is shown in the diagram. The baffle assembly 250 includes an integrated reflective shield, which may be made of 304 stainless steel sheet with a mirror-like single-sided polish or similar reflective material. The baffle assembly 250 is disposed between the water-cooled reactor bottom plate 110 and the reactor's heater assembly. The baffle assembly 250 is designed and configured to reflect thermal radiation back into the heater cavity, thereby achieving a faster vehicle heating rate with minimal heat loss.

[0035] Various embodiments of the systems, apparatus, and methods have been described herein. These embodiments are given by way of example only and are not intended to limit the scope of the claimed invention. Furthermore, it should be understood that the various features of the described embodiments can be combined in various ways to produce many additional embodiments. In addition, while various materials, sizes, shapes, constructions, and positions, etc., for the disclosed embodiments have been described, other materials, sizes, shapes, constructions, and positions, etc., may be used without departing from the scope of the claimed invention, in addition to those disclosed.

[0036] Those skilled in the art will recognize that the subject matter herein may include fewer features than those shown in any single embodiment described above. The embodiments described herein are not intended to be an exhaustive representation of all combinations of features of the subject matter. Therefore, these embodiments are not mutually exclusive combinations of features; rather, as will be understood by those skilled in the art, various embodiments may include combinations of different individual features selected from different individual embodiments. Furthermore, elements described with respect to one embodiment may be implemented in other embodiments, even if not explicitly described in that embodiment, unless otherwise stated.

[0037] While dependent claims may refer in the claims to specific combinations with one or more other claims, other embodiments may also include combinations of dependent claims with the subject matter of each other dependent claim, or combinations of one or more features with other dependent or independent claims. Such combinations are presented herein unless stated not to be contemplated.

[0038] Any reference to the foregoing documents is incorporated such that it does not incorporate any subject matter contrary to the express disclosure herein. Any reference to the foregoing documents is further incorporated such that any claims contained in the documents are not incorporated herein by reference. Any reference to the foregoing documents is further incorporated such that any definitions provided in the documents are not incorporated herein by reference unless expressly included herein.

[0039] For the purposes of interpreting the claims, it is explicitly stated that the provisions of 35 USC § 112(f) are not invoked unless the specific terms “means for…” or “steps for…” are recited in the claims.

Claims

1. A baffle liner for a chemical vapor deposition (CVD) system, comprising: The upper part has a cylindrical shape; as well as The lower part has an outward flaring shape.

2. The baffle lining according to claim 1, wherein, The baffle lining is made of metal.

3. The baffle lining according to claim 1, wherein, The baffle lining is made of molybdenum.

4. The baffle lining according to claim 1, wherein, The baffle lining is composed of a single part.

5. The baffle lining according to claim 1, wherein, The baffle lining consists of two parts, wherein the lower part is separated from and coupled to the upper part.

6. The baffle liner according to claim 5, wherein, The two parts are made of the same material.

7. The baffle lining according to claim 1, wherein, The height of the upper part is greater than the height of the lower part of the outward flare.

8. A chemical vapor deposition (CVD) system, comprising: Reaction chamber; A plurality of walls, comprising an outer liner and an inner liner concentric with and radially inward of the outer liner, wherein a first annular space is defined between the outer liner and the inner liner; and A baffle liner, disposed within the first annular space between the outer liner and the inner liner, and movable between a raised position and a lower position, wherein the baffle liner includes an upper portion having a cylindrical shape and a lower portion having an outwardly flared shape.

9. The CVD system according to claim 8, wherein, The plurality of walls include a reactor outer cover, which is concentric with the outer liner and the inner liner and is located radially outside the outer liner.

10. The CVD system according to claim 8, wherein, The baffle lining is made of metal.

11. The CVD system according to claim 8, wherein, The baffle lining is made of molybdenum.

12. The CVD system according to claim 8, wherein, The baffle lining is composed of a single part.

13. The CVD system according to claim 8, wherein, The baffle lining consists of two parts, wherein the lower part is separated from and coupled to the upper part.

14. The CVD system according to claim 13, wherein, The two parts are made of the same material.

15. The CVD system according to claim 13, wherein, The bottom edge of the baffle lining is adjacent to the outer lining.

16. The CVD system according to claim 8, wherein, The raised position includes the operating position of the baffle liner, and the lowered position includes the non-operating position, which allows the wafer carrier to be inserted into or removed from the reaction chamber.

17. The CVD system according to claim 16, wherein, In the lowered position, the top edge of the baffle liner is located below the wafer carrier.

18. The CVD system according to claim 16, wherein, In the elevated position, the lower portion of the baffle liner is located below the wafer carrier.

19. The CVD system of claim 8 further includes a rotatable wafer carrier disposed in the reaction chamber, the liner being disposed radially outside the wafer carrier.

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