Substrate with axially symmetrical edge purge plenum

Abstract

The invention relates to a susceptor assembly for supporting a wafer in a semiconductor manufacturing tool and chamber. The base assembly may have an edge sweeping system including an axially symmetrical first plenum volume including at least a first axial sub-volume, a first radial sub-volume, and a second radial sub-volume. The first axial sub-volume may be fluidly interposed between the first radial sub-volume and the second radial sub-volume. An optional second plenum volume may also be provided, and the second plenum volume may be used to fluidly connect a region of the wafer support as part of the susceptor assembly with a vacuum port, allowing the wafer support to provide a vacuum gripping function.

Description

Related Applications

[0001] The PCT application form is filed concurrently with this specification as a part of this application. Each application identified in the concurrently filed PCT application form to which this application claims the benefit or priority is incorporated herein by reference in its entirety and for all purposes. Background Art

[0002] Semiconductor processing tools typically require the supply of various reactant gases to a wafer processing space located within one or more semiconductor processing chambers. Semiconductor wafers processed in such chambers are typically supported on a pedestal (e.g., a platform) that may have a chuck or other system suitable for securing the wafer in position on its wafer support surface during processing operations.

[0003] Discussed herein are various improvements to susceptors used in some semiconductor processing systems. Summary of the invention

[0004] The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description that follows. Other features, aspects, and advantages will become apparent from the description, drawings, and claims.

[0005] In some implementations, an apparatus including a susceptor assembly may be provided. The susceptor assembly may include a wafer support having a bottom side and an opposite top side, the top side being configured to support a wafer of diameter D during a semiconductor processing operation so that the wafer is centered on a central axis of the susceptor assembly. The susceptor assembly may have a first plenum volume that is substantially axially symmetric about the central axis of the susceptor assembly. The first plenum volume may include a first axial sub-volume, a first radial sub-volume, and a second radial sub-volume. The first axial sub-volume may fluidly connect the first radial sub-volume and the second radial sub-volume, and may be fluidly interposed between the first radial sub-volume and the second radial sub-volume. Both the first radial sub-volume and the second radial sub-volume may extend radially inward from the first axial sub-volume toward the central axis. The first radial sub-volume may also extend radially inward to a position outside a cylindrical region centered on the central axis and having a diameter of D. Instead, the second radial subvolume may extend radially inward to a position inside the cylindrical region centered on the central axis and having a diameter D. The second radial subvolume may be further from the top side of the wafer support than the first radial subvolume.

[0006] In some implementations, the apparatus may further include a purge inlet fluidly connected to the first plenum volume within the base assembly. The first plenum volume may be configured such that when gas flows into the base assembly via the purge inlet, the gas flows radially outward from the second radial sub-volume to the first axial sub-volume relative to the central axis, then flows from the first axial sub-volume to the first radial sub-volume, and then exits the base assembly via the first radial sub-volume.

[0007] In some implementations, the second radial subvolume can be free of obstructions over an arc totaling at least about 320° about the central axis.

[0008] In some implementations, the base assembly may further include: a ring structure having a circumferential wall portion and a flange portion, the flange portion extending radially inward from the circumferential wall portion to a nominally circular opening having a diameter greater than D. The base assembly may further include: a lower structure having an annular portion, the annular portion having an upper surface, the upper surface facing toward the bottom side of the wafer support and spaced apart from the bottom side of the wafer support. In some such implementations, the first axial sub-volume may be radially interposed between the circumferential wall portion and the outermost surface of the wafer support, the first radial sub-volume may be interposed between the flange portion and the wafer support, and the second radial sub-volume may be interposed between the lower structure and the wafer support.

[0009] In some implementations, the lower structure may include a plurality of protrusions extending from the upper surface of the lower structure and contacting the bottom side of the wafer support. In some further implementations, the protrusions may occupy a total arc of less than 40° around the central axis.

[0010] In some such implementations, each protrusion can have a corresponding lift pin hole extending therethrough, each protrusion can have a contact surface that contacts the wafer support, and both the contact surface of each protrusion and the portion of the wafer support that contacts the protrusion at the contact surface of the protrusion can be flat.

[0011] In some implementations, the first air-filled chamber volume may also include a second axial sub-volume, the second radial sub-volume may be fluidly interposed between the first axial sub-volume and the second axial sub-volume, the lower structure may also include a tubular portion, the tubular portion having an upper end adjacent to the annular portion, the tubular portion may support the annular portion, and the second axial sub-volume may be at least partially defined by the inner surface of the tubular portion.

[0012] In some implementations, the apparatus may further include a first flexible sealing element and a support collar. The first flexible sealing element may be located in a load path that includes the tubular portion and spans between the support collar and the annular portion of the underlying structure, and the first flexible sealing element may apply a compressive load to the annular portion of the underlying structure, thereby pressing the annular portion of the underlying structure into contact with the wafer support.

[0013] In some implementations, the first plenum volume may further include a second axial sub-volume, and the second radial sub-volume may be fluidly interposed between the first axial sub-volume and the second axial sub-volume.

[0014] In some implementations, the pedestal assembly may further include a second plenum volume, one or more vacuum outlets, and one or more vacuum ports. Within the pedestal assembly, the second plenum volume may be fluidly isolated from the first plenum volume, the one or more vacuum ports may lead from the bottom side of the wafer support to the top side of the wafer support, and the second plenum volume may fluidly connect the one or more vacuum ports with the one or more vacuum outlets and may be fluidly interposed between the one or more vacuum ports and the one or more vacuum outlets.

[0015] In some implementations, the device may further include a tubular element that partially defines the second plenum volume.

[0016] In some implementations, the apparatus may further include a stem portion. The stem portion may support the wafer support, the tubular element may surround the stem portion, and the second plenum volume may be further defined at least in part by the stem portion.

[0017] In some implementations, the apparatus may further include a first flexible sealing element, a second flexible sealing element, and a support collar. The first flexible sealing element may be located in a first load path that includes the tubular portion and spans between the support collar and the annular portion of the underlying structure, the second flexible sealing element may be located in a second load path that includes the tubular element and also spans between the support collar and the annular portion of the underlying structure, the first flexible sealing element may apply a compressive load to the annular portion of the underlying structure, thereby pressing the annular portion of the underlying structure into contact with the wafer support, and the second flexible sealing element may be configured to cause a compressive load to be applied to the annular portion of the underlying structure, thereby also pressing the annular portion of the underlying structure into contact with the wafer support.

[0018] In some implementations, the ring structure, the lower structure, and the wafer support may all be made of ceramic material.

[0019] In some implementations, the ring structure can be made of aluminum nitride and the underlying structure can be made of aluminum oxide.

[0020] In some implementations, the wafer support may also include a plurality of low contact area (LCA) features distributed throughout a portion of the top side of the wafer support, and each LCA feature may be a protrusion from a recessed portion of the top side of the wafer support.

[0021] In some implementations, the apparatus can further include a showerhead configured to direct the one or more process gases toward the top side of the wafer support when the one or more process gases flow into the showerhead.

[0022] In some implementations, the apparatus may further include a semiconductor processing chamber, the wafer support being located within the semiconductor processing chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In the following discussion, reference is made to the following drawings; the drawings are not intended to be limiting in scope but are provided merely to facilitate the following discussion.

[0024] Figure 1 Depicted is a cross-sectional side view of an exemplary susceptor assembly embodying an axisymmetric purge gas plenum volume.

[0025] Figure 2 and Figure 1 The same, but most of the reference numerals have been deleted and structural features are shown in light grey; the various elements shown in black are the various plenum volumes and sub-volumes.

[0026] Figure 3 Show Figure 1 Detailed view of the corresponding region of FIG, where the ring structure and adjacent structures can be seen.

[0027] Figure 4 A perspective view of an exemplary underlying structure is shown alone.

[0028] Figure 5 and Figure 6 Depicted in Figure 1 Detailed view of the portion of the support collar visible in FIG.

[0029] Figure 7 Depicted in exploded view Figure 1 An exemplary base assembly of .

[0030] Figure 8 Depicted in the context of a semiconductor processing chamber Figures 1 to 7 A cross-sectional view of the base assembly.

[0031] Fig. 9 Depicted Figure 8 Detailed view of the circled portion.

[0032] The above-mentioned drawings are provided to facilitate understanding of the concepts discussed in the present disclosure and are used to depict some implementation schemes that fall within the scope of the present disclosure, but are not intended to be limiting - implementation schemes that conform to the present disclosure and are not depicted in the drawings are still considered to fall within the scope of the present disclosure. DETAILED DESCRIPTION

[0033] As previously mentioned, semiconductor processing tools or chambers typically use a susceptor to support a wafer during processing operations. Such a susceptor may incorporate various subsystems to facilitate processing operations, including, for example, electrodes that may be used to generate RF energy to ignite a plasma within the chamber, heaters and cooling systems for thermal management of the wafer, lift pin mechanisms for raising or lowering the wafer from the susceptor, and / or clamping systems for clamping the wafer in place during processing operations.

[0034] In some cases, reactants involved in a particular processing operation may flow into the space between the underside of the wafer being processed and the wafer support surface of the pedestal upon which the wafer rests. This may occur even though there is no pressure differential between the interior of the chamber and the underside of the wafer that would draw such gas beneath the wafer. For example, molecules of such gas may simply diffuse into the space between the wafer and the wafer support surface even when the edge of the wafer rests on a continuous and unbroken portion of the wafer support surface. In systems that clamp the wafer to the pedestal using a vacuum chuck, such as by pulling a vacuum on the underside of the wafer so that the region between the wafer and the wafer support surface is at a lower pressure than that of the processing chamber, the pressure differential created between the underside of the wafer and the chamber atmosphere may actually serve to draw process gas from the chamber beneath the wafer.

[0035] Process gases reaching the underside of the wafer may cause undesired deposition or etching on the edge of the wafer, for example, on the underside of the wafer adjacent the edge, or on the bevel of the wafer (the outer edge of the wafer typically has a rounded profile (called a bevel) to avoid hard / sharp edges that may be easily damaged or may produce burrs). One technique for preventing or reducing the possibility of process gases reaching the underside of the wafer or the bevel of the wafer is to provide a purge gas, such as nitrogen, helium, argon, etc. (a gas selected to be non-reactive with the process gas used) around the perimeter of the wafer.

[0036] The inventors of the present invention have determined that the pedestal assemblies discussed herein can be used to provide uniform edge sweeping of a wafer around the entire perimeter of the wafer. For example, a pedestal having a circle of sweep gas ports surrounding the wafer and directing sweep gas to the wafer can be used. However, due to the fact that the sweep gas is introduced at discrete locations near the wafer, the sweep gas will always exhibit a concentration that varies around the perimeter of the wafer, resulting in corresponding local variations in the effectiveness of the sweep gas with respect to preventing unnecessary exposure of the underside and bevel regions of the wafer to the process gas. This results in corresponding variations in the degree to which the process gas is able to affect the underside and / or bevel of the wafer over the circumference.

[0037] To address this problem, the inventors have conceived a susceptor assembly as discussed herein to allow purge gas to be delivered around the entire periphery of the wafer in an almost completely uniform manner, thereby avoiding or mitigating the possibility of circumferential variation in the amount of purge gas delivered. Such a susceptor assembly can be made of a first plenum volume that is generally axially symmetric, wherein the first plenum volume has at least a first radial sub-volume, a first axial sub-volume, and a second radial sub-volume. The first axial sub-volume can fluidly connect the first radial sub-volume to the second radial sub-volume. Both the first radial sub-volume and the second radial sub-volume can extend radially inward from the first axial sub-volume, wherein a portion of the wafer support of the susceptor assembly is interposed between the first radial sub-volume and the second radial sub-volume. This configuration allows purge gas to flow through the first plenum volume, for example, from the second radial sub-volume to the first axial sub-volume, then from the first axial sub-volume to the first radial sub-volume, and then be directed toward the edge of the wafer in a uniformly distributed manner.

[0038] The first plenum volume may be maintained substantially free of any radial obstructions, such as features that may block gas flow along a plane parallel to and coincident with the central axis of the susceptor assembly. However, where such radial obstructions may be necessary, their effects may be minimized, for example, by limiting the proximity of such radial obstructions to the first axial subvolume and / or by limiting the total angle of the arc occupied by such obstructions around the central axis of the susceptor assembly. For example, in some implementations, three columns or protrusions may extend through the second radial subvolume to allow lift pins of the susceptor assembly to pass through the wafer support of the susceptor assembly. However, the size or number of such features may be limited to reduce or minimize the destructive effects that such features may have on gas flowing through the first plenum volume. For example, in some embodiments, such features may block an arc of up to 20°, 30°, or 40°.

[0039] By using a first plenum volume that includes radial subvolumes above and below the wafer support, and connecting the radial subvolumes with axial subvolumes (all subvolumes being substantially axially symmetric about the central axis of the susceptor assembly), the flow path of the purge gas leaving the susceptor assembly can remain axially symmetric over a majority of its length, e.g., extending from a portion of the first radial subvolume closest to the central axis through the first axial subvolume and at least a portion (if not all) of the second radial subvolume. Providing such a relatively long axisymmetric flow path allows any circumferential variation in the concentration of the purge gas at the location where the purge gas is introduced into the first plenum volume to become uniform before the purge gas leaves the first plenum volume; generally, the longer such a flow path, the less circumferential variation in the purge gas delivered from the first plenum volume.

[0040] Figure 1 Depicted is a cross-sectional side view of an exemplary susceptor assembly embodying an axisymmetric purge gas plenum volume. Figure 2 and Figure 1 The same as the 1000A, but most of the reference numerals have been deleted and the structural features are shown in light grey; the various elements shown in black are the various plenum volumes and sub-volumes. Figure 1 As shown, the pedestal assembly 108 may include various structures defining a substantially axisymmetric first plenum volume 130 within the pedestal assembly. The first plenum volume 130 may include at least a first radial sub-volume 136, a first axial sub-volume 132, and a second radial sub-volume 138. The first radial sub-volume 136 may be defined, for example, in part by a top side 124 of the wafer support 110 (as opposed to a bottom side 126 of the wafer support 110) and an underside of a flange portion of a ring structure 144 surrounding the wafer support 110. For example, the flange portion of the ring structure 144 may be vertically offset from the portion of the wafer support 110 directly below it, thereby forming a circumferential vertical gap between the wafer support 110 and the ring structure 144 having the first radial sub-volume 136 therein. The ring structure 144 may have an opening in the middle that is, for example, nominally circular and has a diameter that is larger (eg, on the order of one or several millimeters) than the diameter D of a wafer to be processed using such a susceptor assembly 108 .

[0041] Similarly, the second radial subvolume 138 can be defined, for example, in part, by the bottom side 126 of the wafer support 110 and the upper surface of the underlying structure 152. For example, the underlying structure 152 can be generally vertically offset from the bottom side 126 of the wafer support 110, thereby forming a vertical gap between the bottom side 126 and the underlying structure 152 having the second radial subvolume 138 therein.

[0042] The first axial subvolume 132 may similarly be partially defined by an inwardly facing surface of a circumferential wall portion of the ring structure 144, wherein the inwardly facing surface surrounds an outermost surface of the wafer support 110. The first axial subvolume 132 may also be partially defined by an outwardly facing surface of the wafer support 110. Thus, the first axial subvolume may be located in a radial gap between the circumferential wall portion of the ring structure 144 and an outer periphery of the wafer support 110.

[0043] The first radial subvolume 136 can extend generally radially inward to a position outside the cylindrical region 142, and the second radial subvolume 138 can extend generally radially inward to a position inside the cylindrical region 142. In some cases, the second radial subvolume can be completely free of any obstructions between its outermost edge and the cylindrical region. In some such implementations, the cylindrical region can have a radius that is less than 90%, 85%, 75%, 60%, 50%, or 40% of the distance from the central axis 128 to the outermost portion of the wafer support 110.

[0044] In this example, the wafer support 110 is designed to be used as a vacuum chuck. To this end, the wafer support 110 is equipped with a vacuum port 120, a low contact area (LCA) feature 116, and a sealing ring 122. The sealing ring 122 is a generally annular and raised portion of the top side 124 of the wafer support 110, which is machined, polished, ground, etc. to provide a flat surface that can contact the edge area of ​​the wafer placed thereon to form a generally tight seal around the periphery of the wafer. The LCA feature 116 can be, for example, a protrusion, bump, boss, or convex portion in an otherwise recessed portion of the top side 124 of the wafer support 110, which is distributed on the top side 124 in a generally uniform manner. The LCA features 116 may generally have their topmost surfaces at the same height as the top surface of the seal ring 122, thereby allowing the wafer to be supported by the LCA features 116 throughout its diameter so that the wafer is clamped to the seal ring 122 and LCA features 116 without significant bowing / sagging when a vacuum is drawn on the back side of the wafer via the vacuum port 120. It should be understood that other LCA feature 116 patterns may also be used, depending on the requirements of a particular processing scheme.

[0045] However, in other implementations, the wafer support 110 may omit the vacuum port 120, the LCA feature 116, and / or the seal ring 122. For example, the wafer support 110 may not have the ability to clamp the wafer in place at all, or may have an electrostatic clamping feature that allows the wafer support 110 to be used as an electrostatic chuck (ESC). For example, one or more electrodes may be embedded within the material of the wafer support 110 and provided with a DC potential that may electrostatically attract the wafer against the top side 124 of the wafer support 110.

[0046] In this example, the lower structure 152 includes an annular portion 154 and a tubular portion 158, and the upper end of the tubular portion 158 can be adjacent to the annular portion 154. The annular portion 154 can be radially radiated outward from the tubular portion 158 in the form of a large diameter flange. The annular portion 154 can extend to the ring structure 144 and contact the bottom thereof, thereby supporting the ring structure 144. Figure 3 Show Figure 1 Detailed view of the corresponding area of ​​FIG. 1 , in which the ring structure 144 and adjacent structures can be seen. Figure 3 As shown, the ring structure 144 has a circumferential wall portion 146, such as a thick-walled tube that is generally short and has a large diameter, which is connected to a flange portion 148 that radiates radially inward from the circumferential wall portion 146. Figure 3 (and Figure 1 ), which is a cylindrical feature protruding from the underside of the flange portion 148. The indexing post or feature 150 is relatively small, e.g., only occupies an arc of one or two degrees around the circumference of the ring structure 144, and is intended to engage with a corresponding radial slot 118 in the wafer support 110. Multiple (e.g., three) indexing posts or features 150 may be included on the ring structure 144, thereby allowing the position of the ring structure 144 relative to the wafer support 110 to be constrained. For example, the radial slot 118 may be sized to be only slightly larger than the indexing post or feature 150, such that the indexing post or feature 150 can translate radially within the radial slot 118, but not tangentially (except for a slight dimensional difference between the width of the radial slot 118 and the dimension of the indexing post or feature 150 in the same direction). This configuration may be used to guide the ring structure 144 so that it is centered about the central axis 128 of the susceptor assembly 108 (and wafer support 110).

[0047] In some implementations, index post or feature 150 may have a sufficient vertical height (or radial slot 118 may have a sufficient vertical depth) such that the bottom of index post or feature 150 may contact the bottom of radial slot 118, thereby allowing ring structure 144 to sit on and be supported by wafer support 110. In other implementations, such as Figure 3 As shown, the ring structure 144 may not be supported by the wafer support 110, but may sit directly on the lower structure 152. For example, the bottom surface of the circumferential wall portion 146 of the ring structure may be machined, polished, ground, etc. to form a contact seal with the upper surface 156 of the lower structure 152, thereby preventing or at least hindering the flow of purge gas from the first plenum volume 130 through the interface between the ring structure 144 and the lower structure 152.

[0048] In the depicted example, the ring structure 144 is vertically positioned relative to the wafer support 110 and, therefore, the flange portion 148 relative to the wafer 106 (eg, Figure 3The vertical positioning of the lower structure 152 (shown in dotted outline in FIG. 1 ) is controlled by the vertical positioning of the lower structure 152 relative to the wafer support 110, wherein the lower structure 152 supports the ring structure. A plurality (e.g., three or more) of protrusions 160 may be provided to protrude upwardly from the annular portion 154 of the lower structure 152 (or to protrude downwardly from the bottom side 126 of the wafer support 110) to provide a positive stop that limits potential upward movement of the lower structure 152 relative to the wafer support 110, thereby providing a feature for vertically positioning the lower structure 152 relative to the wafer support 110. In the depicted example, the lower structure 152 (or more accurately, the protrusions 160 that are part of the lower structure 152 in this example) are pressed against the bottom side 126 of the wafer support 110 by a compressive force provided by a first flexible seal 164 (discussed later). This configuration can be used to vertically position the ring structure 144 and the underlying structure 152 relative to the wafer support 110 to form the first radial sub-volume 136 and the second radial sub-volume 138, while still allowing radial translational motion between all three structures to accommodate potential mismatches in thermal expansion rates between the materials used in these structures.

[0049] As previously mentioned, in some implementations, features such as protrusion 160 may be designed to occupy an arc of less than a total of 20°, 30°, or 40°. Figure 4 A perspective view of an exemplary lower structure 152 is shown separately. The central axis 128 of the base assembly 108 is shown, which is also the central axis 128 of the protrusion 160. It can be seen that each of the three protrusions 160 blocks (or partially blocks) an angular area spanning an arc angle θ1, θ2, or θ3, respectively. In implementations such as those discussed above, the sum of θ1, θ2, and θ3 will be less than an arc of 20°, 30°, or 40°.

[0050] In this example, the protrusion 160 also serves as a conduit through which lift pins can be inserted to reach the underside of the wafer 106 supported by the wafer support 110. For example, the wafer support 110 can have a lift pin hole 112 with a corresponding mating lift pin hole 112 extending through the protrusion 160 and the annular portion 154 of the lower structure 152. The size of the lift pin hole 112 can be larger than the diameter of the lift pin used by the susceptor assembly, thereby allowing the lift pin to extend through the lower structure 152 and the wafer support 110 to reach the wafer 106. In this case, the top surface or contact surface of the protrusion 160 (as well as the surface on the bottom side 126 of the wafer support 110 that can contact the protrusion 160) can also be machined, polished, ground, etc. to be flattened to form a contact seal between the protrusion 160 and the bottom side 126 of the wafer support 110, thereby preventing or reducing the chance of purge gas leaking out of the first plenum volume 130 through the lift pin hole 112. In implementations where the protrusion 160 protrudes from the bottom side 126 of the wafer support 110, the bottom surface of the protrusion 160 and the upper surface 156 of the underlying structure 152 may be machined, polished, ground, etc. to form a contact seal.

[0051] In the depicted example, the first plenum volume 130 also includes a second axial sub-volume 134 that is used to extend the length of the flow path through the first plenum volume 130 further than even the length provided by the first radial sub-volume 136, the first axial sub-volume 132, and the second radial sub-volume 138. This provides additional flow path length that can be used to further even out the circumferential pressure and flow rate of the purge gas as it exits the first plenum volume 130 (e.g., near the edge of the wafer 106).

[0052] As described above, the lower structure 152 in this example is pressed against the bottom side 126 of the wafer support 110 by the first flexible seal 164. The first flexible seal 164 can be, for example, a metal bellows seal that is compressed between the lower structure 152 (e.g., its tubular portion 158) and the support collar 172. Thus, the first flexible seal 164 can act as both a seal and a spring, thereby providing a compressive force or compressive load that can be used to press the lower structure 152 into contact with the wafer support 110 (e.g., with the annular portion 154). The support collar 172 can also be used to support the wafer support 110, for example, via the rod 114. The rod 114 can, for example, be connected to the wafer support 110, or even an integral part of the wafer support 110. As shown, the rod 114 is a separate component that is joined to the wafer support 110, for example, by diffusion bonding, and is used to structurally support the wafer support 110. It should be understood that, more generally, the first flexible seal 164 can be in a load path that includes the tubular portion and spans between the support collar 172 and the annular portion 154 of the lower structure 152, and the first flexible seal 164 can be configured to exert a compressive load on the annular portion 154 of the lower structure 152, thereby pressing the lower structure 152 into contact with the wafer support 110. The first flexible seal 164 can be positioned, for example, as shown, but can alternatively be interposed between the tubular portion 158 of the lower structure 152 and the annular portion 154 of the lower structure 152.

[0053] The depicted base assembly 108 also includes a tubular element 162 radially interposed between the tubular portion 158 of the lower structure 152 and the stem 114. Thus, the second axial subvolume 134 is defined in part by the inner surface of the tubular portion 158 of the lower structure 152 and the outer surface of the tubular element 162. The tubular element 162 may also have an inner surface that partially delimits a second plenum volume 140. The second plenum volume 140 may also be defined in part by the outer surface of the stem 114, and the second plenum volume 140 may fluidly connect the vacuum port 120 with one or more vacuum outlets 168 (a single vacuum outlet 168 is shown in this example, but more may be used) in the support collar 172. The tubular element 162 can be configured such that it is pressed against the bottom side 126 of the wafer support 110 by a second flexible seal 166 (which can be similar in nature to the first flexible seal 164), wherein the second flexible seal 166 applies a compressive load on the tubular element 162. It should be understood that the first flexible seal 164 and the second flexible seal 166 can also be arranged in other positions. For example, the second flexible seal 166 can alternatively be inserted between the tubular element 162 and the bottom side 126 of the wafer support 110. Similarly, if the annular portion 154 and the tubular portion 158 of the lower structure 152 are two separate components, the first flexible seal 164 can alternatively be inserted between the annular portion 154 and the tubular portion 158 (wherein the tubular portion 158 is connected to the support collar 172 or an extension of the support collar 172 to form a sealing interface). It should be understood that, more generally, the second flexible seal 166 can be located in a load path that includes the tubular element 162 and also spans between the support ring 172 and the annular portion 154 of the underlying structure 152, and the second flexible seal 166 can be configured to apply a compressive load on the tubular element 162, thereby pressing the tubular element 162 into contact with the wafer support 110.

[0054] In implementations of the base assembly that do not use vacuum clamping or gripping functionality, the vacuum port 120, vacuum outlet 168, and tubular element 162 may be omitted if desired. In such implementations, the second axial subvolume 134 of the first plenum volume 130 (if present) may instead be partially defined by the inner surface of the tubular portion 158 of the lower structure 152 and the outer surface of the stem 114.

[0055] Figure 5 and Figure 6 A detailed view of a portion of the support collar 172 is depicted. Figure 5 and Figure 6As shown, the support collar 172 is constructed of two separate components, a first component 174 and a second component 176, which are held together by a first fastener 188 to allow various internal cavity features in the support collar 172 to be machined. In this multi-component implementation, the support collar may also include one or more first O-ring seals 182, which may be used to seal between these components, such as in locations that may be subject to pressure differentials generated from the vacuum environment of the second plenum volume 140 and the purge gas environment of the first plenum volume 130.

[0056] The depicted support collar 172 includes an annular plenum 194 fluidly connected to a plurality of inclined channels 196, which in turn are fluidly connected to the first plenum volume 130. If the depicted support collar 172 were machined as a single component, both the annular plenum 194 and the inclined channels 196 would be difficult or impossible to machine, but would be relatively simple to machine in a multi-part assembly. However, it should be understood that the support collar 172 could also be a one-piece component, such as a cast component (e.g., using investment casting), or an additively manufactured component, such as using direct metal laser sintering, in which case the internal features can still be utilized but a multi-part approach is not required. In other implementations, features for fluidly connecting the first plenum volume 130 to a purge gas source and, if present, the second plenum volume 140 to a vacuum pump or vacuum source can be implemented in a manner different from the exemplary support collar 172.

[0057] In the depicted support collar 172, the vacuum outlet 168 is a straight, vertical hole through the support collar 172 and is in fluid connection with the second plenum volume 140. Figure 5 It can be seen that the vacuum outlet 168 leaves the top end of the support collar 172 at a position covered by a clamp 190, which is pressed against the support collar 172 by a second fastener 186. The clamp 190 (which can be used to clamp the stem 114 to the support collar 172) is actually a multi-piece clamp, such as two C-shaped members, which have an annular recess on the underside. The annular recess allows airflow from the second plenum volume 140 to the vacuum outlet 168 (indicated by the gray arrow). The clamp 190 can, for example, apply a compressive load on a shoulder 192 of the stem 114 to clamp it to the support collar 172. If desired, one or more second O-rings 184 can be inserted between the stem 114 and the support collar 172 to provide an airtight seal between the second plenum volume 140 and the interior of the stem 114.

[0058] like Figure 6As shown, the support collar 172 may also include one or more purge inlets 170. Each purge inlet 170 may provide a fluid connection between a purge gas source (e.g., a gas line to a fitting that supplies purge gas) and features within the support collar 172 (e.g., annular plenum 194 and angled passage 196), which may be used to flow the purge gas (indicated by white arrows) to the first plenum volume 130 and then toward the wafer edge.

[0059] Figure 7 Depicted in exploded view Figure 1 1. An exemplary base assembly of FIG. 1. The visibility of the radial groove 118 is more obvious here, as is the LCA feature 116, the vacuum port 120, the lift pin hole 112, and the clamp 190. During assembly, the second O-ring 184 can be set into the circular groove in the first part 174 of the support collar 172. Next, the stem 114 can be inserted into the first part 174 of the support collar 172 so that the shoulder 192 of the stem 114 contacts the second O-ring 184. Next, the clamp 190 can be placed around the stem 114 to contact the shoulder 192 of the stem 114 and the first part 174 of the support collar 172. Next, the second fastener 186 can be inserted into the hole in the clamp 190 and screwed into the corresponding threaded hole in the first part 174 of the support collar 172. At this point, the first part 174 of the support collar can be fixedly connected to the stem 114. If the stem 114 is not already attached to the wafer support 110 , the stem 114 may then be connected to the wafer support 110 .

[0060] Separately, the second part 176 can be prepared by installing the first and second flexible seals 164, 166 into corresponding circular seats or grooves in the second part 176 of the support collar 172. The tubular element 162 can then be disposed in the same groove or seat that accommodates the second flexible seal 166 so as to sit on the second flexible seal, and the tubular portion 158 of the lower structure 152 can also be similarly disposed in the same groove or seat that accommodates the first flexible seal 164 so as to sit on the first flexible seal 164.

[0061] Next, the first section 174 of the support collar 172 (now with the attached stem 114 and wafer support 110) can be inserted through the tubular member 162 and into the second section 176 of the support collar 172 until the first section 174 bottoms out against the second section 176 and the tubular member 162 and the underlying structure 152 are compressed against the bottom side 126 of the wafer support 110 by the compression of the first and second flexible seals 164, 166. At this point, the first fastener 188 can be inserted through the hole in the second section 176 and threaded into the corresponding threaded hole in the first section 174, thereby clamping the first and second sections 174, 176 together and forming the assembled support collar 172. The ring structure 144 can then be placed over the wafer support 110, thereby seating on the underlying structure 152. Of course, during such assembly, the indexing features (eg, posts) 150 may be aligned with the radial slots 118 , and the lift pin holes 112 in the wafer support 110 may be aligned with corresponding lift pin holes 112 in the underlying structure 152 .

[0062] Of course, it should be understood that the above-described assembly process can be modified as desired depending on the specific design of the components used. For example, if an integral support collar 172 is used, the clamp 190 can have a plurality of studs extending through the support collar 172 so that nuts can be screwed onto their exposed ends, thereby allowing the clamp 190 to be tightened even when access to the clamp 190 is blocked by the presence of the tubular element 162 and / or the underlying structure 152.

[0063] Figure 8 Depicted in the context of a semiconductor processing chamber Figures 1 to 7 A cross-sectional view of the base assembly. Fig. 9 Depicted Figure 8 Detailed view of the circled portion.

[0064] like Figure 8 and Fig. 9 As shown, the exemplary susceptor assembly 108 discussed herein may be (at least partially) housed within a chamber 102, which may be part of a semiconductor processing tool, such as a system housing multiple processing chambers or having processing chambers capable of simultaneously housing multiple wafers for processing operations.

[0065] The chamber 102 may also at least partially house a showerhead 104. The showerhead 104 may be positioned so as to be centered above the pedestal assembly 108 and may have a plurality of gas distribution ports distributed across its underside (e.g., in a manner similar to how the LCA features 116 are distributed across the top side 124 of the wafer support 110). The gas distribution ports may provide one or more process gases via one or more plenums within the showerhead 104, which may then flow into a space between the showerhead 104 and the pedestal assembly 108. Thus, the wafer 106 (which may be supported on the wafer support 110 of the pedestal assembly 108) may be exposed to the process gases to perform one or more process operations.

[0066] The chamber 102 may also include a plurality of lift pins 178, which may be supported, for example, on a lift pin collar 180. In some cases, the lift pin collar 180 may be fixedly mounted relative to the chamber 102 - in which case the base assembly 108 may be configured to be vertically movable up and down relative to the chamber 102, for example using a translation drive mechanism configured to drive the base assembly 108 in this manner. In other cases, the lift pin collar 180 may be connected to one or more vertical actuators, which may be used to drive the lift pins 178 to move vertically up and down relative to the chamber 102 (and the base assembly 108). In yet another implementation, both the lift pin collar 180 and the base assembly 108 may be connected to separate vertical translation systems that allow either component or assembly to move vertically independently of the other. Such a system can allow the wafer 106 to be lifted off the wafer support 110 by vertically moving the lift pins 178 relative to the wafer support 110. It should be understood that the showerhead 104 can also be configured to be able to move vertically (or the pedestal assembly 108 can be understood to be able to move relative to the showerhead 104) to allow the gap between the showerhead 104 and the pedestal assembly 108 to increase, thereby facilitating the use of the lift pins 178 to lift the wafer 106 off the wafer support 110.

[0067] like Fig. 9 As shown, process gas delivered from the showerhead 104 (indicated by the gray arrows) can enter a relatively small and confined space formed between the underside of the showerhead 104 and the top side 124 of the wafer support (more correctly, between the showerhead 104 and the wafer 106 supported by the wafer support 110). This confined space (which can be referred to as a microvolume) reduces the amount of volume that needs to be filled with process gas in order to expose the wafer to the process gas, reduces the time taken to purge the volume, and provides a microenvironment, wherein the microenvironment allows multiple wafers to be processed using different processes within the same chamber.

[0068] Concurrently with the flow of process gas, a purge gas (indicated by white arrows) may flow through the susceptor assembly, such as via the first plenum volume, and to near the edge of the wafer and around the periphery of the wafer.

[0069] In some cases, pedestal assemblies such as those discussed herein may be equipped with a heating system embedded within the wafer support, or may be exposed to other heat sources, which may cause the wafer support to reach temperatures of hundreds of degrees Celsius, such as 500°C or higher, 600°C or higher, or 700°C or higher. In such cases, one or more of the ring structure, lower structure, wafer support, rod, tubular element, and various other components may be made of materials that can withstand such high temperatures and the chemical environment within the processing chamber. For example, the ring structure, lower structure, wafer support, rod, and tubular element may each be made of a ceramic material, such as aluminum oxide (aluminum oxide), aluminum nitride, or other similar ceramic materials. In some cases, such components may be made of different types of such materials, such as the lower structure may be aluminum oxide, while the wafer support and / or the ring structure may be made of aluminum nitride. In such cases, it may be desirable to have a floating or non-anchored connection between these components, such as in the above example, where the ring structure is simply placed on the lower structure to accommodate different amounts of thermal expansion in these components when transitioning between room temperature and these high temperatures.

[0070] Control of the pedestal assembly described herein, for example, may be facilitated by the use of a controller, which may be included as part of a semiconductor processing tool having a pedestal assembly. The systems discussed above may be integrated with electronic components for controlling their operation before and after semiconductor wafer or substrate processing. The electronic components may be referred to as "controllers" that may control various components or sub-portions of the one or more systems. Depending on the processing requirements and / or system type, the controller may be programmed to control any of the systems disclosed herein, including controlling: the operation of various valves (which may control the flow of purge and / or gas evacuation for vacuuming), the operation of heater elements within the pedestal assembly, the operation of various valves that may control the flow of process gases, the operation of a vertical lift mechanism for moving the pedestal assembly and / or showerhead and / or lift pins up and down, the operation of an electrostatic chuck or clamping electrode, or various other components that may be included in a pedestal assembly as described herein or may be provided in association with such a pedestal assembly.

[0071] Broadly speaking, a controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. The integrated circuits can include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). The program instructions can be instructions sent to the controller in the form of various individual settings (or program files) that define operating parameters for implementing specific operations using the base assembly described herein.

[0072] In some implementations, the controller may be part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the "cloud" or all or part of a wafer fab host system that may allow remote access to wafer processing. The computer may enable remote access to the system to monitor the current progress of a manufacturing operation, check the history of past manufacturing operations, check trends or performance criteria for multiple manufacturing operations, change parameters of a current process, set processing steps to follow the current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system via a network (which may include a local network or the Internet). The remote computer may include a user interface that enables input or programming of parameters and / or settings, which are then sent from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, for example, by including one or more discrete controllers networked together and working toward a common purpose, such as the processes and controls described herein. An example of a controller distributed for this purpose would be one or more integrated circuits located on a chamber (e.g., a VTM) that is remotely located (e.g., located at the platform level or as part of a remote computer) and combined to control the purge gas flow operations for the pedestal assembly described herein.

[0073] The pedestal assembly described herein may be connected to, but is not limited to, one or more other devices, including a plasma etching chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a chamfer edge etching chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etching (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, or any other semiconductor processing system that may be associated with or used for the manufacture and / or preparation of semiconductor wafers.

[0074] As described above, depending on one or more processing steps to be performed by the tool, the controller can communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the factory, a host computer, another controller, or tools used in material transport of wafer containers (e.g., FOUPs) to and from tool locations and / or load ports in a semiconductor manufacturing facility.

[0075] For purposes of this disclosure, the term "fluidically connected" is used to refer to volumes, plenums, holes, etc., which can be connected to each other directly or through one or more intermediate components or volumes to form a fluid connection, similar to the term "electrically connected" used to refer to components that are connected together to form an electrical connection. The term "fluid interposition" (if used) can be used to refer to a component, volume, plenum, or hole that is fluidly connected to at least two other components, volumes, plenums, or holes, so that fluid flowing from one of those other components, volumes, plenums, or holes to the other or another of those components, volumes, plenums, or holes will first flow through the "fluid interposition" component and then reach the other or another of those components, volumes, plenums, or holes. For example, if a pump is fluidly interposed between a reservoir and an outlet, fluid flowing from the reservoir to the outlet will first flow through the pump and then reach the outlet. The term "fluidically adjacent", if used, refers to the placement of one fluid element relative to another fluid element such that no possible structure is fluidly interposed between the two elements that could interrupt fluid flow between the two fluid elements. For example, in a flow path having a first valve, a second valve, and a third valve sequentially positioned there along, the first valve is fluidly adjacent to the second valve, the second valve is fluidly adjacent to both the first and third valves, and the third valve is fluidly adjacent to the second valve.

[0076] Any ordinal numbers (if any) used in the present disclosure and claims, such as (a), (b), (c) ... or (1), (2), (3) ... or the like, should be understood as not expressing any particular order or sequence unless such order or sequence is explicitly indicated. For example, if there are three steps labeled (i), (ii), and (iii), it should be understood that the steps can be performed in any order (or even simultaneously, if there are no other restrictions), unless otherwise indicated. For example, if step (ii) involves the operation of an element produced in step (i), step (ii) can be considered to occur at a point after step (i). Similarly, if step (i) involves the operation of an element produced in step (ii), it should be understood to be the opposite. It should also be understood that the use of the ordinal number "first" (e.g., "first item") in this document should not be interpreted as implicitly or inherently suggesting that there must be a "second" case (e.g., "second item").

[0077] It should be understood that the phrases "for each <item> in one or more <items>," "each <item> in one or more <items>," and the like, if used herein, include both single-item groups and multi-item groups, i.e., the phrase "for...each" is used in the sense that it is used in a programming language to refer to each item in any group of items referenced. For example, if the group of items referenced is a single item, then "each" will refer only to that single item (although dictionary definitions of "each" often define the term to mean "each of two or more things"), and does not mean that there must be at least two of those items. Similarly, the terms "set" or "subset" by themselves should not be taken to necessarily cover multiple items - it should be understood that a set or subset may cover only one member or multiple members (unless the context dictates otherwise).

[0078] Unless otherwise indicated, when the term "between" used in this article is used with a numerical range, it should be understood to include the starting and ending values ​​of the range. For example, between 1 and 5 should be understood to include numbers 1, 2, 3, 4 and 5, not just numbers 2, 3 and 4.

[0079] The term "operably connected" should be understood to refer to a state in which two components and / or systems are directly or indirectly connected so that, for example, at least one component or system can control the other. For example, a controller may be described as being operably connected to a resistive heating unit, including a controller connected to a sub-controller of the resistive heating unit, the sub-controller being electrically connected to a relay, the relay being configured to controllably connect or disconnect the resistive heating unit from a power source capable of providing an amount of electricity that can be supplied to the resistive heating unit to produce a desired degree of heating. Because of the electrical current involved, the controller itself may not be able to directly provide such power to the resistive heating unit, but it should be understood that the controller is still operably connected to the resistive heating unit.

[0080] It should be understood that the examples and implementations described herein are for illustrative purposes only, and that those skilled in the art will associate various modifications or variations therewith. Although various details have been omitted for clarity, various design alternatives may be implemented. Therefore, the present examples are considered to be illustrative rather than restrictive, and the present disclosure is not limited to the details set forth herein, but may be modified within the scope of the present disclosure.

[0081] It should be understood that although the above disclosure focuses on one or more specific exemplary implementations, it is not limited to the examples discussed, but is also applicable to similar variations and mechanisms, and such similar variations and mechanisms are also considered to fall within the scope of the present disclosure.

Claims

1. A device comprising: A susceptor assembly comprising a wafer support having a bottom side and an opposing top side, the top side being configured to support a wafer having a diameter D during a semiconductor processing operation such that the wafer is centered on a central axis of the susceptor assembly, wherein: The base assembly has a first plenum volume that is substantially axially symmetric about the central axis of the base assembly, The first plenum volume includes a first axial sub-volume, a first radial sub-volume and a second radial sub-volume, The first axial sub-volume fluidly connects the first radial sub-volume and the second radial sub-volume, and the fluid is interposed between the first radial sub-volume and the second radial sub-volume, The first radial subvolume and the second radial subvolume both extend radially inwardly from the first axial subvolume toward the central axis, The first radial subvolume extends radially inward to a position outside a cylindrical region centered on the central axis and having a diameter D, The second radial subvolume extends radially inward to a position inside the cylindrical region of diameter D centered on the central axis, and The second radial sub-volume is further from the top side of the wafer support than the first radial sub-volume.

2. The apparatus of claim 1 , further comprising a purge inlet fluidly connected to the first plenum volume within the base assembly, wherein the first plenum volume is configured such that when gas flows into the base assembly via the purge inlet, the gas flows radially outwardly from the second radial sub-volume to the first axial sub-volume, then from the first axial sub-volume to the first radial sub-volume, and then exits the base assembly via the first radial sub-volume.

3. The device according to claim 1 or 2, wherein: The second radial subvolume is free of obstructions in an arc totaling at least about 320° about the central axis.

4. The device according to claim 1 or 2, wherein: The base assembly also includes: a ring structure having a circumferential wall portion and a flange portion extending radially inwardly from the circumferential wall portion to a nominally circular opening having a diameter greater than D; as well as a lower structure having an annular portion having an upper surface facing toward and spaced apart from the bottom side of the wafer support, wherein: The first axial subvolume is radially between the circumferential wall portion and the outermost surface of the wafer support, The first radial subvolume is between the flange portion and the wafer support, and The second radial subvolume is between the underlying structure and the wafer support.

5. The device according to claim 4, wherein: The lower structure includes a plurality of protrusions extending from the upper surface of the lower structure and contacting the bottom side of the wafer support.

6. The device according to claim 5, wherein: The convex portion occupies a total arc of less than 40° around the central axis.

7. The device according to claim 5, wherein: Each boss has a corresponding lift pin hole therethrough, Each protrusion has a contact surface that contacts the wafer support, and The contact surface of each protrusion and the portion of the wafer support that contacts the protrusion at the contact surface of the protrusion are both flat.

8. The device according to claim 4, wherein: The first plenum volume further comprises a second axial sub-volume, The second radial sub-volume fluid is interposed between the first axial sub-volume and the second axial sub-volume, The lower structure further comprises a tubular portion having an upper end adjacent to the annular portion, The tubular portion supports the annular portion, and The second axial subvolume is at least partially defined by an inner surface of the tubular portion.

9. The device of claim 8, further comprising a first flexible sealing element and a support collar, wherein: the first flexible sealing element is located in a load path that includes the tubular portion and spans between the support collar and the annular portion of the underlying structure, and The first flexible sealing element applies a compressive load on the annular portion of the underlying structure, thereby pressing the annular portion of the underlying structure into contact with the wafer support.

10. The device according to claim 9, wherein: The first plenum volume further comprises a second axial sub-volume, and The second radial sub-volume of fluid is interposed between the first axial sub-volume and the second axial sub-volume.

11. The device according to claim 8, wherein: The base assembly also includes a second plenum volume, one or more vacuum outlets, and one or more vacuum ports, within the base assembly, the second plenum volume being fluidly isolated from the first plenum volume, The one or more vacuum ports lead from the bottom side of the wafer support to the top side of the wafer support, and The second plenum volume fluidly connects the one or more vacuum ports with the one or more vacuum outlets and is fluidly interposed between the one or more vacuum ports and the one or more vacuum outlets.

12. The device of claim 11, further comprising a tubular element, wherein: The second plenum volume is defined in part by the tubular element.

13. The device of claim 12, further comprising a stem, wherein: The rod portion supports the wafer support member, The tubular element surrounds the stem, and The second plenum volume is further defined at least in part by the stem portion.

14. The device of claim 12, further comprising a first flexible sealing element, a second flexible sealing element, and a support collar, wherein: The first flexible sealing element is located in a first load path that includes the tubular portion and spans between the support collar and the annular portion of the underlying structure, the second flexible sealing element being located in a second load path that includes the tubular element and also spans between the support collar and the annular portion of the underlying structure, the first flexible sealing element applies a compressive load on the annular portion of the underlying structure, thereby pressing the annular portion of the underlying structure into contact with the wafer support, and The second flexible sealing element is arranged to cause a compressive load to be exerted on the annular portion of the underlying structure, thereby also pressing the annular portion of the underlying structure into contact with the wafer support.

15. The device according to claim 4, wherein: The ring structure, the lower structure and the wafer support are all made of ceramic material.

16. The device according to claim 15, wherein: The ring structure is made of aluminum nitride, and the lower structure is made of aluminum oxide.

17. The device according to claim 1, wherein: The wafer support further includes a plurality of low contact area (LCA) features distributed throughout a portion of the top side of the wafer support, and Each LCA feature is a protrusion from a recessed portion of the top side of the wafer support.

18. The apparatus of claim 1, further comprising a showerhead configured to direct one or more process gases toward the top side of the wafer support when the one or more process gases flow into the showerhead.

19. The apparatus of claim 18, further comprising a semiconductor processing chamber, wherein the wafer support is located within the semiconductor processing chamber.

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