Thermally structured ceramic pedestal

Abstract

A component for use in controlled atmosphere chambers, such as a shaft of a pedestal in a semiconductor processing chamber, includes an outer wall and a thermally structured infill pattern of radial walls extending from the outer wall radially inward. A hollow internal bore is formed within and along a length of the component. The component may be formed using an additive manufacturing process such that complex geometries can be created to reduce thermal losses during operation.

Description

THERMALLY STRUCTURED CERAMIC PEDESTALCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Patent Application No. 63 / 663,350, filed on June 24, 2024. The disclosure of the above application is incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure relates to ceramic pedestals for use in semiconductor manufacturing equipment, and more specifically to shafts for such ceramic pedestals and their method of manufacture.BACKGROUND

[0003] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0004] In the processing of semiconductor wafers, a pedestal is arranged within a processing chamber to support a semiconductor wafer for etching. The pedestal is often made from a ceramic material and generally includes a heater plate and a shaft secured to a lower portion of the heater plate. The shaft is generally hollow and is configured to receive a variety of electrical connections to power the heater plate and to monitor a variety of system parameters throughout the etching process.

[0005] Because semiconductor wafers must be manufactured to extremely tight tolerances, the thermal uniformity of the pedestal, and more specifically of an upper surface of the heater plate proximate the semiconductor wafer, must be tightly controlled. Accordingly, a variety of approaches have been employed to reduce the impact of heat sinks / losses during fabrication of semiconductor wafers. For example, multiple zone heaters have been used across and throughout the thickness of the heater plate, and a variety of materials have been used in the construction of the pedestal to provide more uniform temperatures during the etching process. Additional, or secondary heaters have also been provided within the shaft or on a bottom side of the heater plate, however, volume and cost constraints limit the ability to provide additional heaters to reduce thermal losses.

[0006] These challenges associated with providing thermal uniformity along upper surfaces of heated pedestals, along with other thermal loss issues within semiconductor processing equipment, are addressed by the present disclosure.SUMMARY

[0007] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0008] In one form of the present disclosure, a shaft for use in controlled atmosphere chambers, the shaft including an outer wall, and a thermally structured infill pattern of radial walls extending from the outer wall radially inward. A hollow internal bore is formed within and along a length of the shaft.

[0009] In variations of this shaft, which may be implemented individually or in any combination: the shaft further includes an inner wall, wherein the thermally structured infill pattern of radial walls extends between the outer wall and the inner wall; a plurality of cavities are formed between the thermally structured infill pattern of radial walls, the outer wall, and the inner wall, and the plurality of cavities are under vacuum; the shaft is formed using an additive manufacturing process; the thermally structured infill pattern of radial walls defining a plurality drain passageways; the thermally structured infill pattern of radial walls extends along a portion of the length of the shaft; thermally structured infill pattern of radial walls define a non-constant geometry along the length of the shaft; the shaft further includes a plurality of zones of thermally structured infill pattern of radial walls extending along the length of the shaft; the thermally structured infill pattern of radial walls defines a honeycomb pattern; the thermally structured infill pattern of radial walls defines a plurality of concentric rings; the thermally structured infill pattern of radial walls defines a lattice structure; the shaft is formed from a ceramic material; the ceramic material is one of an aluminum nitride (AIN) material or an aluminum oxide (AI2O3) material; the ceramic material is graded along a length of the shaft; the shaft further includes a plurality of axial passageways integrally formed in the shaft and configured to receive electrical leads; the plurality of axial passageways extend along an interior portion of the shaft, along the inner wall; further comprising at least one sensor embedded within the thermally structured infill pattern of radial walls; the at least one sensor is a temperature sensor; the shaft further includes a solid upper end portion and a solid lower end portion flanking the thermally structured infill pattern of radial walls; and the thermally structured infill pattern of radialwalls extend perpendicular from the outer wall.

[0010] According to another form of the present disclosure, a pedestal for use in controlled atmosphere chambers includes a plate and a shaft secured to a lower end portion of the plate. The shaft comprises an outer wall and a thermally structured infill pattern of radial walls extending from the outer wall radially inward. A hollow internal bore is formed within and along a length of the shaft. The plate and the shaft are formed using an additive manufacturing process such that the pedestal is a single unitized piece.

[0011] In variations of this pedestal, which may be implemented individually or in any combination: the pedestal further includes a hub disposed at an upper end portion of the shaft; and the hub is integrally formed with the shaft using the additive manufacturing process.

[0012] In yet another form of the present disclosure, a component for use in controlled atmosphere chambers includes an outer wall configured to be resistant to a chemical environment, and a thermally structured infill pattern of radial walls extending from the outer wall radially inward.

[0013] In variations of this component, which may be implemented individually or in any combination: the component is a shaft of a pedestal for use in a semiconductor processing chamber; and the component is a hub secured to an upper end portion of a shaft of a pedestal for use in a semiconductor processing chamber.

[0014] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.DRAWINGS

[0015] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

[0016] FIG. 1A is a top perspective view of a pedestal for use in semiconductor processing equipment constructed in accordance with the teachings of the present disclosure;

[0017] FIG. 1 B is a bottom perspective view of the pedestal of FIG. 1A;

[0018] FIG. 2 is a side cross-sectional view of the pedestal of FIGS. 1A and 1 B;

[0019] FIG. 3 is an exploded bottom perspective view of the pedestal of FIG. 2B;

[0020] FIG. 4 is a side view of the pedestal of FIGS. 1A and 1 B illustrating a thermally structured area of a shaft in accordance with the teachings of the present disclosure;

[0021] FIG. 5A is a perspective view of one form of a thermally structured area of a shaft constructed accordance with the teachings of the present disclosure;

[0022] FIG. 5B is a side view of the thermally structured area of the shaft of FIG. 5A;

[0023] FIG. 5C is a perspective view of another form of a thermally structured area of a shaft constructed accordance with the teachings of the present disclosure;

[0024] FIG. 6 is a cutaway perspective view of another form of a thermally structured area of a shaft constructed accordance with the teachings of the present disclosure; and

[0025] FIG. 7 is an enlarged perspective view of a cutaway area of the thermally structured area of the shaft of FIG. 6.

[0026] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.DETAILED DESCRIPTION

[0027] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0028] Referring to FIGS. 1-3 a pedestal for use in semiconductor processing equipment, or more generally in controlled atmosphere chambers, is illustrated and generally indicated by reference numeral 100. The pedestal 100 generally comprises a plate 110 and a shaft 120 secured to a lower surface 112 of the plate 110. The pedestal 100 in this form includes an optional hub 130, which may be a separate piece as shown, or integral with the shaft 120 and / or the plate 110. The hub 130 generally provides a larger mounting area for the shaft 120 to the plate 110and can be used to tailor the thermal properties of the pedestal 100 as set forth in greater detail below. In this form, the shaft 120 is secured to the hub 130, which is secured to the lower surface 112 of the plate 110 as shown. It should be understood that the shaft 120 may be directly secured to the lower surface 112 of the plate, without using a hub 130, while remaining within the scope of the present disclosure. The shaft 120 also includes a base portion 114, which in this variation is integrally formed with the shaft 120. The base portion 114 provides a larger area for mounting the pedestal 100 within the controlled atmosphere chamber.

[0029] The shaft 120 includes a hollow internal bore 122 formed within and along the length of the shaft 120, which is used for routing of electrical leads (not shown), along with mounting of other functional components (e.g., sensors, mechanical attachments). The shaft 120 may also include embedded passageways 124 rather than, or in addition to the hollow internal bore 122 for the routing of electrical leads and mounting of the other functional components. The shaft 120 further includes an outer wall 126, which is a hermetic interface between a chamber environment and the hollow internal bore 122. In other words, the outer wall 126 comprises a material that is impervious to processing gases in the chamber environment. Further, an inner wall 128 extends along the hollow internal bore 122, which is generally a continuous surface, but may not necessarily be limited thereto.

[0030] In one form, the plate 110, shaft 120, and optional hub 130 are each made of a ceramic material. In one variation, the ceramic material is an aluminum nitride (AIN), however, other ceramic materials such as aluminum oxide (AI2O3) or beryllium oxide (BeO), among others, may also be used while remaining within the scope of the present disclosure. In one form, the pedestal 100, shaft 120, and hub 130 are made from the same material, e.g., AIN ceramic. In other forms, a different material, including a graded material (i.e., higher thermal conductivity towards the top of the shaft 120 and lower towards the bottom of the shaft 210), may be used for one or more of the plate 100, the shaft 120, and / or the hub 130. Further details of such materials and their combinations are set forth in greater detail below.

[0031] Referring specifically to FIG. 2, the plate 110 contains one or more electrically functioning elements 140 used in a semiconductor manufacturing process, which are embedded within the plate 110 as shown. In one form, the electrically functioning elements 140 include by way of example a heating circuit 142 (having one or more zones) and an RF antenna 144 (having one or more electricallyindependent / isolated sections). The heating circuit 142 in one form is a resistive heater by way of example, including but not limited to a foil heater or a thermally sprayed heater, among others. It should be understood that a variety of electrically functioning elements 140 may be embedded within or operatively engaged with the pedestal assembly 100 while remaining within the scope of the present disclosure. Such electrically functioning elements 140 are described in greater detail in PCT Published Application WO 2023 / 158675, which is commonly owned with the present application and the contents of which are incorporated herein by reference in their entirety.

[0032] Referring also to FIG. 3, the hub 130 has an upper portion 150 that is joined to the plate 110 with an upper joining layer 152. Similarly, a lower portion 154 of the hub 130 is joined to the shaft 120 with a lower joining layer 156. In another form without the hub 130, the upper joining layer 152 and the lower joining layer 156 are used to directly join the shaft 120 to the lower surface 112 of the plate 110. The upper joining layer 152 and the lower joining layer 156 as illustrated and described herein provide hermetically sealed interfaces between the plate 110 and the hub 130, (or between the plate 110 and the shaft 12), and also between the hub 130 and the shaft 120. Generally, the interface is hermetic to meet application requirements within a chamber of semiconductor processing equipment.

[0033] Referring now to FIG. 4, the shaft 120 is shown with an innovative thermally structured area 200, which is configured to reduce thermal losses down through the shaft 120, in the direction of arrow A, during semiconductor processing operations. Generally, the thermally structured area 200 has a reduced thermal conductivity, which is achieved through an innovative combination of materials, processes, and structural configurations as set forth in greater detail below. And while the thermally structured area 200 is illustrated along only a portion of the length of the shaft 120, it should be understood that the thermally structured area 200 may extend along the entire length, or in predetermined areas (i.e., zones 200' and / or 200", having progressively lower thermal conductivities towards the bottom of the shaft 120) while remaining within the scope of the present disclosure.

[0034] With reference to FIGS. 5A and 5B, one form of the thermally structured area 200 is shown, which includes a thermally structured infill pattern of radial walls 210 in a honeycomb pattern. The thermally structured infill pattern of radial walls 210 generally reduces the thermal conductivity of the shaft 120 in this area and thus reduces thermal losses during operation. The structure of a honeycomb patternalso provides sufficient structural support for the plate 110, as well as sufficient load transfer between the plate 110 and the remainder of the shaft 120. Thus, the thermally structured area 200 is advantageously configured to provide reduced thermal conductivity (compared with a solid shaft proximate the plate 110) while also providing sufficient structural support.

[0035] As shown, the thermally structured infill pattern of radial walls 210 extend from the outer wall 126 (shown transparent for purposes of clarity) radially inward. In one form, the shaft 120 and its thermally structured area 200 are a single piece and are formed using an additive manufacturing (AM) process. In this way, the relatively complex structural configuration of a honeycomb pattern can be manufactured more easily than with traditional methods (e.g., casting). For example, the AM process may include, by way of example, powder sintering, binder jetting, photopolymerization (DLP - digital light processing), or extrusion, among others. For such AM processes, the thermally structured infill pattern of radial walls 210 would include drain passageways (not shown) in predetermined areas to remove excess material after the thermally structured area 200 is formed.

[0036] The thermally structured infill pattern of radial walls 210 extends between the outer wall 126 and the inner wall 128. A plurality of cavities 220 are formed between the thermally structured infill pattern of radial walls 210, the outer wall 126, and the inner wall 128. When the shaft 120 is joined to the plate 110 using a bonding process (e.g., brazing) that is under vacuum, the cavities 220 are advantageously also under vacuum, which improves the performance of the thermally structured area 200 such that thermal losses down the shaft 120 during operation are further reduced.

[0037] As further shown, one or more axial passageways 230 are integrally formed in the shaft 120, and also through the thermally structured area 200, which are configured to receive electrical leads for connecting the electrically functioning elements 140 (FIG. 2) to a power supply (not shown). The axial passageways 230 in this form extend along an interior portion of the shaft 120, along the inner wall 128. However, the axial passageways 230 may be formed between the outer wall 126 and the inner wall 128 rather than protruding into the hollow internal bore 122 of the shaft 120 as shown. In this form, the shaft 120 may optionally include at least one sensor 300 embedded within the thermally structured infill pattern of radialwalls 210. Such a sensor 300 may include, by way of example, a temperature sensor (e.g., thermocouple) or other environmental sensor such as a gas sensor.

[0038] The thermally structured area 200 in this form also includes a solid upper end portion 240 and a solid lower end portion 250 flanking the thermally structured infill pattern of radial walls 210. However, it should be understood that the thermally structured infill pattern of radial walls 210 may extend all the way to the lower surface 112 of the plate 110 and / or all the way to the base portion 114 (FIG. 2) while remaining within the scope of the present disclosure. Also in this form, the thermally structured infill pattern of radial walls 210 extend perpendicular from the outer wall 126 as shown. However, it should be understood that the thermally structured infill pattern of radial walls 210 may extend at any angle towards the hollow internal bore 122 of the shaft 120 while remaining within the scope of the present disclosure.

[0039] Referring to FIG. 5C, another form of the thermally structured area 270 is shown without the inner wall 128. In this form, the cavities 220 are exposed to the hollow internal bore 122 of the shaft 120 as shown. Additionally, drain passageways 410 are also provided when the thermally structured area 200 in this variation is formed using an AM process. Without the inner wall 128, the thermally structured area 200 in this form may be used to further tailor thermal properties, i.e., reduce thermal conductivity, as well as house other functional components such as temperature sensors, by way of example. It should be understood that the specific pattern of thermally structured infill pattern of radial walls 210 shown (i.e., honeycomb pattern) is not limiting, and thus other patterns / configurations of thermally structured infill pattern of radial walls 210 may be employed without the internal wall 128 while remaining within the scope of the present disclosure.

[0040] Referring now to FIGS. 6 and 7, another form of a thermally structured area 201 includes a thermally structured infill pattern of radial walls 400 that define a plurality of concentric rings. In this form, the thermally structured area 201 also includes drain passageways 410 for the applicable AM process, as well as axial passageways 420 for electrical leads as previously described. Similar to the previous form, the thermally structured infill pattern of radial walls 400 extends between the outer wall 126 and the inner wall 128, and a plurality of cavities 430 are formed between the thermally structured infill pattern of radial walls 400, the outer wall 126, and the inner wall 128. The inner wall 128 is also optional in this form of the presentdisclosure, and previous variations illustrated and described relative to the honeycomb pattern may also be employed and are not further described for purposes of clarity.

[0041] In one form of the present disclosure, the plate 110 and the shaft 120 are formed using an additive manufacturing process such that the pedestal 100 is a single unitized piece. Further, the optional hub 130 may also be integrally formed with the plate 110 and the shaft 120. It should also be understood that the teachings of the present disclosure may be applied to any component that is used within a controlled atmosphere chamber, and thus the teachings herein are not limited to a pedestal for use in semiconductor processing chambers. In addition, the innovative thermally structured area 200 and the thermally structured infill pattern of radial walls 210 may be applied to any component, such as by way of example the hub 130, and is not limited to application to the shaft 120 as illustrated and described herein.

[0042] Unless otherwise expressly indicated herein, all numerical values indicating mechanical / thermal properties, compositional percentages, dimensions and / or tolerances, or other characteristics are to be understood as modified by the word “about” or "approximately" in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

[0043] The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. For example, the thermally structured infill pattern of radial walls 200 in one form may define a non-constant geometry along the length of the shaft 120, or may define a lattice structure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.

[0044] As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

Claims

CLAIMSWhat is claimed is:1 . A shaft for use in controlled atmosphere chambers, the shaft comprising: an outer wall; and a thermally structured infill pattern of radial walls extending from the outer wall radially inward, wherein a hollow internal bore is formed within and along a length of the shaft.

2. The shaft according to Claim 1 , further comprising an inner wall, wherein the thermally structured infill pattern of radial walls extends between the outer wall and the inner wall.

3. The shaft according to Claim 1 , wherein a plurality of cavities are formed between the thermally structured infill pattern of radial walls, the outer wall, and the inner wall, and the plurality of cavities are under vacuum.

4. The shaft according to Claim 1 , wherein the shaft is formed using an additive manufacturing process.

5. The shaft according to Claim 4, wherein the thermally structured infill pattern of radial walls defining a plurality drain passageways.

6. The shaft according to Claim 1 , wherein the thermally structured infill pattern of radial walls extends along a portion of the length of the shaft.

7. The shaft according to Claim 1 , wherein the thermally structured infill pattern of radial walls define a non-constant geometry along the length of the shaft.

8. The shaft according to Claim 1 , further comprising a plurality of zones of thermally structured infill pattern of radial walls extending along the length of the shaft.

9. The shaft according to Claim 1 , wherein the thermally structured infill pattern of radial walls defines a honeycomb pattern.

10. The shaft according to Claim 1, wherein the thermally structured infill pattern of radial walls defines a plurality of concentric rings.

11. The shaft according to Claim 1, wherein the thermally structured infill pattern of radial walls defines a lattice structure.

12. The shaft according to Claim 1, wherein the shaft is formed from a ceramic material.

13. The shaft according to Claim 12, wherein the ceramic material is one of an aluminum nitride (AIN) material or an aluminum oxide (AI2O3) material.

14. The shaft according to Claim 12, wherein the ceramic material is graded along a length of the shaft.

15. The shaft according to Claim 1, further comprising a plurality of axial passageways integrally formed in the shaft and configured to receive electrical leads.

16. The shaft according to Claim 15, wherein the plurality of axial passageways extend along an interior portion of the shaft, along an inner wall.

17. The shaft according to Claim 1 , further comprising at least one sensor embedded within the thermally structured infill pattern of radial walls.

18. The shaft according to Claim 17, wherein the at least one sensor is a temperature sensor.

19. The shaft according to Claim 1 , further comprising a solid upper end portion and a solid lower end portion flanking the thermally structured infill pattern of radial walls.

20. The shaft according to Claim 1, wherein the thermally structured infill pattern of radial walls extend perpendicular from the outer wall.

21. A pedestal for use in controlled atmosphere chambers, the pedestal comprising: a plate; and a shaft secured to a lower end portion of the plate, the shaft comprising: an outer wall; and a thermally structured infill pattern of radial walls extending from the outer wall radially inward, wherein a hollow internal bore is formed within and along a length of the shaft, and wherein the plate and the shaft are formed using an additive manufacturing process such that the pedestal is a single unitized piece.

22. The pedestal according to Claim 21 , further comprising a hub disposed at an upper end portion of the shaft.

23. The pedestal according to Claim 22, wherein the hub is integrally formed with the shaft using the additive manufacturing process.

24. A component for use in controlled atmosphere chambers, the component comprising: an outer wall configured to be resistant to a chemical environment; and a thermally structured infill pattern of radial walls extending from the outer wall radially inward.

25. The component according to Claim 24, wherein the component is a shaft of a pedestal for use in a semiconductor processing chamber.

26. The component according to Claim 24, wherein the component is a hub secured to an upper end portion of a shaft of a pedestal for use in a semiconductor processing chamber.

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