Wafer Boat

Abstract

To provide a wafer boat configured to be placed on a pedestal of a vertical batch furnace.SOLUTION: The invention provides a wafer boat configured to be placed on a pedestal of a vertical batch furnace, the pedestal having a substantially flat support surface. The wafer boat comprises a support ring defining a substantially flat bottom end surface of the wafer boat, and an alignment ring substantially concentric with the support ring. One of the support surface of the pedestal and a bottom side of the alignment ring is provided with a plurality of alignment elements protruding accordingly upwards from the support surface or downwards from the alignment ring, while the other thereof is provided with a plurality of alignment openings configured to accommodate therein the plurality of alignment elements. The support ring downwardly protrudes beyond the alignment ring so that, when the wafer boat is placed on the pedestal, the support ring is supported on the support surface while the alignment ring is separated from the support surface of the pedestal.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure generally relates to a wafer boat configured to support a plurality of wafers and be positioned on a pedestal of a vertical batch furnace.

Background Art

[0002] Most vertical batch furnaces are provided with a pedestal for supporting a wafer boat and moving the wafer boat into a process chamber. Typically, the wafer boat is positioned on a small cylindrical foot on the pedestal. The pedestal may vertically move the wafer boat to a process position within the process chamber.

Summary of the Invention

[0003] [[ID=ID=18]] The summary of this invention is provided to introduce the selected concepts in a simplified form. These concepts are described in more detail in the "Mode for Carrying Out the Invention" of the exemplary embodiments of the present disclosure below. This "Summary of the Invention" is not intended to identify the main features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0004] It is understood that in order to obtain uniform processing of the wafers in the wafer boat, for example, uniform deposition of material on the surfaces of the wafers in the wafer boat, it may be necessary to position the wafer boat linearly and concentrically with respect to the process chamber. Therefore, when the wafer boat is positioned on the pedestal of the vertical batch furnace, the bottom or contact surface may need to have a high level of flatness. A high level of flatness prevents tilting of the wafer boat and allows for linear alignment between the wafer boat and the process chamber. Without a sufficient level of flatness, it may cause tilting of the wafer boat with respect to the process chamber, which may result in, for example, non-uniform deposition in the process.

[0005] Furthermore, it is sometimes desirable to have a small contact surface between the wafer boat and the pedestal. A small contact surface can minimize heat conduction from the wafer boat to the pedestal, and therefore minimize heat loss.

[0006] Therefore, the objective may be to provide a wafer boat that can achieve a sufficient level of flatness, allows the pedestal to rotate together with the wafer boat fixed on the pedestal, and has an alignment system relative to the pedestal that can minimize heat loss.

[0007] For that purpose, a wafer boat as described in claim 1 may be provided. More specifically, a wafer boat may be provided that supports a plurality of wafers and is configured to be set on a pedestal of a vertical batch furnace. The pedestal may have a substantially flat support surface. The wafer boat may define a central wafer boat axis, which may extend substantially vertically when the wafer boat is set on the pedestal. The wafer boat may include a support ring and an alignment ring. The support ring may define a substantially flat bottom end surface of the wafer boat. The alignment ring may be substantially concentric with the support ring. A plurality of alignment elements may be provided on either the support surface of the pedestal or the bottom side of the alignment ring, projecting upward from the support surface or downward from the alignment ring, respectively. A plurality of alignment openings may be provided on the other of the support surface and the alignment ring, configured to accommodate the plurality of alignment elements therein. The support ring may protrude downward beyond the alignment ring in the direction of the central wafer boat axis, so that when the wafer boat is fixed on the pedestal, the support ring may be supported on the support surface, while the alignment ring may be spaced away from the support surface of the pedestal.

[0008] Furthermore, an assembly for aligning and rotating the wafer boat described in claim 17 may be provided. The assembly may comprise the wafer boat and a pedestal according to this specification. The pedestal may comprise a substantially flat support surface and a plurality of alignment elements projecting upward from the support surface, configured to be housed in a plurality of alignment openings within an alignment ring, or a plurality of alignment openings configured to house a plurality of alignment elements on the alignment ring.

[0009] A vertical batch furnace assembly for processing wafers as described in claim 19 may be further provided. The vertical batch furnace assembly may further comprise a process chamber, a wafer handling space, and a wafer boat handling device. The process chamber may be configured to apply heat treatment or chemical treatment to a batch of wafers. The wafer handling space may be provided with assemblies according to this specification. The wafer boat handling device may be configured to transfer assemblies between the wafer handling space and the process chamber.

[0010] To summarize the invention and its advantages achieved beyond the prior art, certain objectives and advantages of the invention have been described above. Naturally, it should be understood that not all of these objectives or advantages can necessarily be achieved by any particular embodiment of the invention. Therefore, those skilled in the art will recognize that the invention may be embodied or practiced in a manner that achieves or optimizes one or a group of advantages as taught or suggested herein, without necessarily achieving other objectives or advantages as taught or suggested herein.

[0011] Various embodiments are claimed in the dependent claims, which will be further illustrated with reference to the examples shown in the figures. The embodiments may be applied in combination or separately from each other.

[0012] All of these embodiments are intended to be within the scope of the present invention as disclosed herein. These embodiments and other embodiments will be readily apparent to those skilled in the art from the following “Modes for Carrying Out the Invention” of certain embodiments with reference to the following appended drawings, and the present invention is not limited to any particular embodiment disclosed.

[0013] While this specification specifically identifies and concludes with claims that are clearly defined, the advantages of the embodiments of this disclosure can be more readily determined from the descriptions of certain embodiments of this disclosure, when read in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 shows a cross-sectional perspective view of an embodiment of the wafer boat described herein. [Figure 2] Figure 2 shows a detailed view of the bottom of Figure 1. [Figure 3] Figure 3 shows a perspective cross-sectional view of the bottom details of an embodiment of the wafer boat as shown in Figure 2, while it is fixed on the pedestal, which is also shown in the cross-sectional view. [Figure 4] Figure 4 shows a bottom view of an embodiment of the wafer boat described herein. [Modes for carrying out the invention]

[0015] In this application, similar or corresponding features are indicated by similar or corresponding reference numerals. The descriptions of various embodiments are not limited to the examples shown in the figures, and the reference numerals used in the embodiments and claims for carrying out the invention are not intended to limit the descriptions of embodiments but are included for clarity.

[0016] While certain embodiments and examples are disclosed below, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments and / or uses of the invention, as well as obvious modifications and equivalents thereof. Therefore, the scope of the disclosed invention is not intended to be limited by the specific disclosed embodiments described below. The examples presented herein are not intended to represent the actual appearance of any particular material, structure, or apparatus, but are merely idealized representations used to describe embodiments of the disclosure.

[0017] As used herein, the term “wafer” may refer to any underlying material(s) on which a device, circuit, or film may be formed.

[0018] In its most common form, the disclosure may provide a wafer boat 10. The wafer boat may be configured to support a plurality of wafers, and may be configured to be stationary on a pedestal 12 of a vertical batch furnace. The pedestal 12 may have a substantially flat support surface 14. The wafer boat 10 may define a central wafer boat axis 16, which may extend substantially vertically when the wafer boat 10 is stationary on the pedestal 12. The wafer boat 10 may include a support ring 18 and an alignment ring 22. The support ring 18 may define a substantially flat bottom end surface 20 of the wafer boat 10. The alignment ring 22 may be substantially concentric with the support ring 18. A plurality of alignment elements 24 may be provided on either the support surface 14 of the pedestal 12 or the bottom side of the alignment ring 22, projecting upward from the support surface 14 or downward from the alignment ring 22, respectively. The other of the support surface 14 and the alignment ring 22 may be provided with a plurality of alignment openings 26 configured to accommodate a plurality of alignment elements 24 therein. The support ring 18 may project downward beyond the alignment ring 22 in the direction of the central wafer boat axis 16, so that when the wafer boat 10 is set on the pedestal 12, the support ring 18 may be supported on the support surface 14, while the alignment ring 22 may be spaced away from the support surface 14 of the pedestal 12.

[0019] By utilizing the support ring 18 and the alignment ring 22, the pedestal 12 may exert different forces on the wafer boat 10 during and after placement on the pedestal 12. The pedestal 12 may exert a vertical force to support and lift the wafer boat 10. The pedestal 12 may also exert a transverse horizontal force to rotate the wafer boat 10. The pedestal 12 may further exert a force in a horizontal plane to move the wafer boat 10 in the horizontal plane. The pedestal 12 may also exert a horizontal force relative to the pedestal 12 to move the wafer boat 10 to the correct position on the pedestal 12.

[0020] The protruding alignment elements 24 and alignment openings 26 may form an alignment system that allows the wafer boat 10 to be positioned at the correct position and rotation angle relative to the pedestal 12 and, consequently, to the process chamber. Precise positioning can be achieved by carefully selecting the positioning of the alignment elements 24 and the corresponding alignment openings 26. When the wafer boat 10 is positioned on the pedestal 12, the alignment elements 24 may slide into the alignment openings 26, aligning the wafer boat 10 with the pedestal 12.

[0021] When positioned on the pedestal 12, the support ring 18 is configured to receive vertical support forces. Simultaneously, the alignment openings 26 or alignment elements 24 within or on the alignment ring 22 can receive horizontal forces from the pedestal 12. The matching alignment elements 24 and alignment openings 26 may enable the transmission of rotational movement to the wafer boat 10. The alignment elements 24 may be implemented, for example, as protrusions or rods, and the openings as matching holes. Naturally, the engagement between the alignment elements 24 and the alignment openings 26 may also be used to induce translational movement to the wafer boat 10, or a combination of translational movement and rotation.

[0022] The wafer boat 10 may have its bottom end surface 20 of its support ring 18 resting on the support surface 14 of the pedestal 12. There may be a single contact surface between the wafer boat 10 and the pedestal 12. In contrast, each of the small feet of a known wafer boat may have a contact surface independent of the contact surface of another small foot. It may be difficult to achieve a sufficient level of flatness using these independent contact surfaces. Since there may be a single contact surface, it may be easier to manufacture the surface and achieve a sufficient level of flatness required for the alignment of the wafer boat 10 than to use multiple contact surfaces of multiple corresponding feet.

[0023] Conductive heat loss can only move through the bottom surface 20 to the support ring 18. By using the support ring 18, it is possible to select the radial width of the ring 18 so that this conductive heat loss is minimized.

[0024] In an embodiment, the support ring 18 may be annular and may also have an inner radius 28 and an outer radius 30. The difference between the inner radius 28 and the outer radius 30 may be less than 10 mm, and preferably may be 4 - 5 mm.

[0025] Thanks to the small radial width, the relatively thin support ring 18 may have a relatively small bottom surface 20. The radial width may need to be sufficient to provide support to the wafer boat, while the small bottom surface may minimize the heat conduction loss from the wafer boat 10 to the pedestal 12.

[0026] In an embodiment, the support ring 18 and the alignment ring 22 may be integrally formed.

[0027] Using such an integrally formed mounting, the support ring 18 and the alignment ring 22 may be fixed relative to each other, which means that relative alignment when constructing the wafer boat 10 is no longer necessary. Furthermore, friction and wear between components during use are avoided. This means that no very small particles or debris that may contaminate the wafers within the wafer boat are generated.

[0028] In an embodiment, the alignment element 24 may be provided on the support surface 14. A plurality of alignment openings 26 may be provided within the alignment ring 22 and may also extend through the support ring 18. Alternatively, the alignment element 24 may be provided on the bottom side of the alignment ring 22, and a plurality of alignment openings 26 may be provided within the support surface 14 of the pedestal 12. Also, it may be possible that one or more of the plurality of alignment elements 24 are provided on the support surface 14, while another portion of the plurality of alignment elements 24 is provided on the bottom side of the alignment ring 22.

[0029] In one embodiment shown in the figures, the alignment element 24 may be provided on the support surface 14. Multiple alignment openings 26 may be embodied as slots 26 through the alignment ring 22 and optionally the support ring 18. Each slot 26 may be a substantially straight slot 26 having a slot axis 32. Each slot axis 32 may extend through the center point of the alignment ring 22 and optionally the support ring 18, and may also extend radially outward. Multiple slots 26 may comprise three slots 26 that are circumferentially spaced apart over an intermediate angle of substantially 105° to 135° along the circumference of the alignment ring. The intermediate angles may be, for example, substantially 110°, substantially 120°, and substantially 130°.

[0030] The slots 26 and alignment elements 24 may be arranged so that the placement of the wafer boat 10 on the pedestal 12 can be unique. Since the slots 26 may have an elongated shape, the protruding alignment elements 24 may be movable in the longitudinal direction of the slot 26 but not in the width direction. By carefully selecting the placement of the slots 26, the position of the wafer boat 10 relative to the pedestal 12 may be precisely determined, while the fixation may not be overly restricted. As shown in the embodiment of Figure 4, the wafer boat 10 may be aligned with its center point by having a slot axis 32 extending through a center point. Three slots 26 may be sufficient to precisely align the wafer boat 10 with respect to the pedestal 12 and prevent relative movement to each other. By distributing the three angles approximately evenly, but not perfectly evenly, a single rotational position of the wafer boat 10 relative to the pedestal 12 is possible.

[0031] In alternative embodiments, the alignment element 24 may be provided on the alignment ring 22, and the multiple alignment openings 26 may be embodied as slots within the support surface 14.

[0032] This configuration of the alignment element 24 and the alignment opening 26 may have the same effects and advantages as an embodiment in which the alignment element 24 is provided on the pedestal 12 and the slot 26 is provided within the alignment ring 22.

[0033] In this embodiment, the width of each slot 26 may be such that each alignment element 24 fits snugly into its respective slot 26, allowing radial movement of the elements within the associated slot 26 while preventing tangential movement of the elements in the alignment ring 22.

[0034] By having multiple slots 26, particularly three slots 26, at an angle to each other, the position of the wafer boat 10 relative to the pedestal 12 is defined without excessive constraint. These effects apply equally to embodiments in which the protruding alignment element 24 is provided on the support surface 14 and the alignment opening 26 is provided within the alignment ring 22, as well as embodiments in which the protruding alignment element 24 is provided on the alignment ring 22 and the alignment opening 26 is provided within the support surface 14.

[0035] In one embodiment shown in Figure 1, the wafer boat 10 may further include at least two, preferably three, posts 34 connected to and extending upward from the alignment ring 22, parallel to the central wafer boat axis 16. Each post 34 may have a plurality of slits 34 for supporting a plurality of wafers. The wafer boat may further include an upper plate 36 connected to the upper ends of at least two of the posts 32. The wafer boat 10 may also include a bottom plate 38 extending inward from the alignment ring 22 and which may be concentric with the alignment ring 22. The support ring 18, the alignment ring 22, and the bottom plate 38 may be integrally formed.

[0036] Similar to the integrally formed support ring 18 and alignment ring 22, the integrally formed support ring 18, alignment ring 22, and bottom plate 38 may be fixed to each other, which means that relative alignment is no longer required when constructing the wafer boat 10.

[0037] Furthermore, friction and wear between components during use are avoided. This means that no particles or fragments that could contaminate the wafers within the wafer boat are generated.

[0038] The posts 34 may extend vertically. The upper plate 36 may stabilize the upward-extending posts 34. The multiple slits 34 may be evenly spaced so that the supported wafers are at equal distances from each other. This may further facilitate a uniform deposition process.

[0039] In the embodiment shown in the figure, the support ring 18 may be configured to face radially outward from the alignment ring 22.

[0040] In this embodiment, the support ring 18, which can generally act as the base of the wafer boat, may have a larger diameter than the alignment ring 22. Having a larger diameter means that the support ring 18 can provide greater stability to the wafer boat 10.

[0041] In this embodiment, the support ring 18 and the alignment ring 22 may be made of quartz.

[0042] The wafer boat 10 and alignment system may need to withstand large temperature differences, which can lead to high stress within the wafer boat material. Quartz may be suitable for meeting this requirement. In addition to the alignment ring 22 and support ring 18, other components of the wafer boat 10 may also be made of quartz. Possible examples include the posts 32, the top plate 36 and / or the bottom plate 38.

[0043] The disclosure may also provide assemblies 10, 12 for aligning and rotating the wafer boat 10. The assemblies 10, 12 may comprise the wafer boat 10 and the pedestal 12 as described herein. The pedestal 12 may comprise a substantially flat support surface 14 and a plurality of alignment elements 24 projecting upward from the support surface 14, configured to be housed within a plurality of alignment openings 26 of an alignment ring 22, or a plurality of alignment openings 26 configured to house a plurality of alignment elements 24 on the alignment ring 22.

[0044] The effects and benefits of assemblies 10 and 12 are similar to those described above in relation to wafer boat 10, and these effects and benefits are inserted here by reference.

[0045] In this embodiment, the alignment element 24 may be a pin that extends upward from the pedestal support surface 14.

[0046] Therefore, the assembly may provide a combination of pins and openings, or a combination of pins and slots, into which the wafer boat 10 and pedestal 12 may be aligned.

[0047] This disclosure may provide a vertical batch furnace assembly for processing wafers. The vertical batch furnace assembly may further comprise a process chamber, a wafer handling space, and a wafer boat handling device. The process chamber may be configured to apply heat treatment or chemical treatment to a batch of wafers. The wafer handling space may be provided by assemblies 10, 12 according to this specification. The wafer boat handling device may be configured to transfer assemblies 10, 12 between the wafer handling space and the process chamber.

[0048] The effects and benefits of the vertical batch furnace assembly are similar to those described above in relation to assemblies 10, 12 and wafer boat 10, and these effects and benefits are inserted by reference.

[0049] While exemplary embodiments of the present invention have been described above with partial reference to the accompanying drawings, it should be understood that the present invention is not limited to these embodiments. Variations of embodiments of the present disclosure can be understood and achieved by those skilled in the art who practice the claimed invention from a review of the drawings, disclosure, and the accompanying claims.

[0050] Throughout this specification, any reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in relation to an embodiment is included in at least one embodiment of the present invention. Therefore, the occurrence of the phrase “in one embodiment” or “in an embodiment” in various places throughout this description does not necessarily all refer to the same embodiment.

[0051] Furthermore, it should be noted that one or more specific features, structures, or characteristics from the various embodiments described above may be used and practiced independently of each other, and may be combined in any preferred manner to form new embodiments not expressly described. The reference numbers used in the embodiments and claims for carrying out the invention do not limit the description of the embodiments or the claims. The reference numbers are used for clarity only. [Explanation of symbols]

[0052] 10-Wafer Boat 12-Pedestal 14-Support surface 16-Central wafer boat shaft 18-Support ring 20-bottom end surface 22-Alignment Rings 24-pin 26-slot 28 - Inner radius (of the support ring) 30 - Outer radius (of the support ring) 32-slot shaft 32-Post 34-Slit 36-Top Plate 38 - Bottom plate

Claims

1. A wafer boat (10) configured to support multiple wafers and to be set on a pedestal (12) of a vertical batch furnace, wherein the pedestal (12) has a flat support surface (14), and the wafer boat (10) defines a vertically extending central wafer boat axis (16) when the wafer boat (10) is set on the pedestal (12), and the wafer boat (10) - A support ring (18) that defines the flat bottom end surface (20) of the wafer boat (10), - The device comprises the support ring (18) and the alignment ring (22) which are concentric with each other. The support surface (14) of the pedestal (12) or the bottom side of the alignment ring (22) is provided with a plurality of alignment elements (24) projecting upward from the support surface (14) or downward from the alignment ring (22), and the other side of the support surface (14) and the alignment ring (22) is provided with a plurality of alignment openings (26) configured to accommodate the plurality of alignment elements (24) therein. A wafer boat in which the support ring (18) protrudes downward beyond the alignment ring (22) in the direction of the central wafer boat axis (16), so that when the wafer boat (10) is set on the pedestal (12), the support ring (18) is supported on the support surface (14), while the alignment ring (22) is spaced apart from the support surface (14) of the pedestal (12).

2. The wafer boat according to claim 1, wherein the support ring (18) is annular and has an inner radius (28) and an outer radius (30), and the difference between the inner radius (28) and the outer radius (30) is less than 10 mm.

3. The wafer boat according to claim 1 or 2, wherein the support ring (18) and the alignment ring (22) are integrally formed.

4. The wafer boat according to any one of claims 1 to 3, wherein the alignment element (24) is provided on the support surface (14) of the pedestal (12), and the plurality of alignment openings (26) are provided within the alignment ring (22) and optionally extend through the support ring (18).

5. The wafer boat according to any one of claims 1 to 4, wherein the plurality of alignment openings (26) are embodied as slots (26) passing through the alignment ring (22) and optionally extend through the support ring (18).

6. The wafer boat according to claim 5, wherein each slot (26) is a straight slot having a slot axis (32), and each slot axis (32) extends through the center point of the alignment ring (22) and optionally through the support ring (18), and extends radially outward.

7. The wafer boat according to claim 6, wherein the plurality of slots (26) comprises three slots (26) spaced apart in the circumferential direction over an intermediate angle of 105° to 135° along the circumference of the alignment ring.

8. The wafer boat according to claim 7, wherein the intermediate angles are 110°, 120°, and 130°.

9. The wafer boat according to any one of claims 1 to 3, wherein the alignment element (24) is provided on the alignment ring (22), and the plurality of alignment openings (26) are embodied as slots in the support surface (14).

10. The wafer boat according to any one of claims 5 to 9, wherein the width of each slot (26) is such that each alignment element fits snugly into its respective slot (26), thereby allowing radial movement of the alignment element within the associated slot (26), while preventing tangential movement of the alignment element in the alignment ring (22).

11. A wafer boat according to any one of claims 1 to 10, further comprising at least two posts (34) connected to and extending upward from the alignment ring (22) and parallel to the central wafer boat axis (16), wherein each post (34) includes a plurality of slits (34) for supporting a plurality of wafers.

12. The wafer boat according to claim 11, further comprising an upper plate (36) connected to the upper ends of the at least two posts (32).

13. The wafer boat according to claim 11 or 12, further comprising a bottom plate (38) extending inward from the alignment ring (22) and concentric with the alignment ring (22).

14. The wafer boat according to claim 13, wherein the support ring (18), the alignment ring (22), and the bottom plate (38) are integrally formed.

15. The wafer boat according to any one of claims 1 to 14, wherein the support ring (18) is configured to face radially outward of the alignment ring (22).

16. The wafer boat according to any one of claims 1 to 15, wherein the support ring (18) and the alignment ring (22) are made of quartz.

17. An assembly (10, 12) for aligning and rotating wafer boats (10), - A wafer boat (10) according to any one of claims 1 to 16, - An assembly comprising a pedestal (12) having a flat support surface (14) and a plurality of alignment elements (24) projecting upward from the support surface (14) and configured to be housed in a plurality of alignment openings (26) within the alignment ring (22), or a plurality of alignment openings (26) on the alignment ring (22) configured to house the plurality of alignment elements (24) therein.

18. The assembly according to claim 17, wherein the alignment element (24) is a pin extending upward from the support surface (14) of the pedestal (12).

19. A vertical batch furnace assembly for processing wafers, - A process chamber configured to apply heat treatment or chemical treatment to a batch of wafers, - A wafer handling space provided in the assembly (10, 12) according to claim 17 or 18, A vertical batch furnace assembly comprising: a wafer boat handling device configured to transfer the assemblies (10, 12) between the wafer handling space and the process chamber.

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