# Patent

## Title
Process feed management for semiconductor substrate processing

## Abstract

Embodiments related to managing the process feed conditions for a semiconductor process module are provided. In one example, a gas channel plate for a semiconductor process module is provided. The example gas channel plate includes a heat exchange surface including a plurality of heat exchange structures separated from one another by intervening gaps. The example gas channel plate also includes a heat exchange fluid director plate support surface for supporting a heat exchange fluid director plate above the plurality of heat exchange structures so that at least a portion of the plurality of heat exchange structures are spaced from the heat exchange fluid director plate.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of and claims priority to U.S. patent application Ser. No. 13/284,642 entitled “PROCESS FEED MANAGEMENT FOR SEMICONDUCTOR SUBSTRATE PROCESSING,” filed Oct. 28, 2011, the disclosure of which is hereby incorporated herein by reference.


BACKGROUND
Supplying process reactants to semiconductor processing tools can be difficult. For example, ambient gases may diffuse into low pressure portions of the process tool, potentially contaminating process reactants. Further, some process reactants may condense on various process tool surfaces under some processing conditions. Contamination and/or condensation of process reactants may lead to substrate quality problems as well as potential process control problems.
SUMMARY
Various embodiments are disclosed herein that relate to managing the process feed conditions for a semiconductor process module. For example, one embodiment provides a gas channel plate for a semiconductor process module. The example gas channel plate includes a heat exchange surface including a plurality of heat exchange structures separated from one another by intervening gaps. The example gas channel plate also includes a heat exchange fluid director plate support surface for supporting a heat exchange fluid director plate above the plurality of heat exchange structures so that at least a portion of the plurality of heat exchange structures are spaced from the heat exchange fluid director plate.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically shows a semiconductor process module according to an embodiment of the present disclosure.
FIG. 2 schematically shows an exploded isometric view of a portion of the semiconductor process module of FIG. 1
FIG. 3 schematically shows a larger isometric view taken along line 3 of the portion of the semiconductor process module shown in FIG. 2.
FIG. 4 schematically shows a cross-section taken along line 4 of the portion of the semiconductor process module shown in FIG. 3.
FIG. 5 schematically shows a larger isometric view taken along line 5 of the portion of the semiconductor process module shown in FIG. 3.
FIG. 6 schematically shows a cross-section taken along line 6 of the portion of the semiconductor process module shown in FIG. 5.
FIG. 7 schematically shows a larger isometric view taken along line 7 of the portion of the semiconductor process module shown in FIG. 2.
FIG. 8 schematically shows a cross-section taken along line 8 of the portion of the semiconductor process module shown in FIG. 7.
FIG. 9 schematically shows a cross-section taken along line 9 of the portion of the semiconductor process module shown in FIG. 7.
FIG. 10 schematically shows a sectioned isometric view of a showerhead volume profile according to an embodiment of the present disclosure.
FIG. 11 schematically shows a sectioned isometric view of a showerhead volume profile according to another embodiment of the present disclosure.
FIG. 12 schematically shows a sectioned isometric view of a two-piece showerhead according to an embodiment of the present disclosure.
FIG. 13 schematically shows a heat exchange fluid channel formed above a gas channel plate according to an embodiment of the present disclosure.
FIG. 14 schematically shows a blower and duct for providing air to a heat exchange plenum assembly according to an embodiment of the present disclosure.
FIG. 15 schematically shows an exploded isometric view of a heat exchange plenum assembly according to an embodiment of the present disclosure.
FIG. 16 schematically shows a sectioned isometric view of air flow distribution from a heat exchange plenum assembly to a heat exchange fluid channel formed above a gas channel plate according to an embodiment of the present disclosure.
FIG. 17 shows a flowchart for a method of processing a semiconductor substrate in a semiconductor process module according to an embodiment of the present disclosure.



DETAILED DESCRIPTION
Modern semiconductor devices may include integrated structures formed by the deposition of films in high-aspect ratio cavities or under low thermal budget conditions. Typical chemical vapor deposition (CVD), thermal growth, and/or physical vapor deposition (PVD) approaches may not be suited to the process integration constraints for such structures. Atomic layer deposition (ALD) processes are sometimes used to address these challenges. In ALD processes, thin layers of film are deposited by alternately adsorbing two or more reactants to the substrate without supplying the reactants to the substrate process environment concurrently. By supplying each reactant separately, only deposited film layers and the surface active species of one reactant chemisorbed to those film layers are present on the substrate when the other reactant is supplied. Consequently, highly conformal films may be formed on the substrate surface, even in high-aspect ratio features.
The layer-by-layer nature of ALD processes may present challenges to enhance substrate throughput during manufacturing. For example, some approaches to increase throughput include selecting process reactants based on reactivity characteristics that may enhance surface decomposition reactions on the substrate relative to other process reactants. However, the presence of ambient gases, such as oxygen and/or water vapor, may lead to increases in gas phase decomposition as the reactivity of process reactants increases, potentially leading to substrate non-uniformity defects, small particle defects that may decorate the substrate surface, and/or film composition contamination.
Other approaches to enhance throughput include supplying the substrate with a quantity of reactant suitable to provide acceptable substrate coverage of surface active species in a short-duration, high-concentration pulse. However, because some process reactants, such as those including metals, may have higher molecular weights than the carrier gases with which they may be mixed, it may be more difficult to distribute the process reactant on the substrate surface with suitable coverage as pulse duration decreases. Consequently, cross-substrate concentration gradients may form in the gas phase above the substrate during process reactant exposure phases that may lead to substrate non-uniformity defects. In some settings, process reactants may condense on process surfaces even under vacuum conditions. Such reactant condensation upstream of the substrate may lead to small particle defect decoration on the substrate surface. Additionally or alternatively, some process reactants may undergo gas phase or surface decomposition upstream of the substrate, potentially leading to film contamination or other process quality problems. While the problems that may result from process reactants like those described above, such as organometallic reactants having low vapor pressures, are described herein in the context of ALD processes, it will be understood that similar issues may exist for some process reactants used m some low-pressure CVD deposition processes, low-pressure etch processes, and so on.
The disclosed embodiments relate to hardware and methods for managing the process feed conditions for a semiconductor process module. For example, one embodiment provides a network of purge gas channels included in a gas channel plate or a showerhead for a semiconductor process module. The example purge gas channels fluidly communicate with an ambient environment via gaps positioned between the ambient environment and a gasket sealing the gas channel plate or the showerhead to another portion of the semiconductor process module. Consequently, ambient gas diffusion or permeation across the gasket and into the low pressure reactor may be mitigated, potentially reducing film impurities and/or particle defects.
Another embodiment provides a semiconductor process module including a showerhead volume upstream of a substrate. The example showerhead volume includes contours configured to form a radially symmetric profile within the showerhead volume with respect to an axial centerline of a process feed inlet opening into the showerhead volume. The example showerhead volume contours are shaped so that opposing surfaces of the semiconductor process module forming the outer edges of the showerhead volume are closer to one another than those same surfaces at a central region of the showerhead volume. Thus, though process feed is distributed to the substrate via showerhead gas distribution holes distributed across the showerhead, the process feed velocity may remain approximately constant as the radial distance from the process feed inlet increases, potentially enhancing substrate uniformity.
Another embodiment provides a heat exchanger for a showerhead volume of a semiconductor process module. The example heat exchanger includes a heat exchanger fluid director plate and a gas channel plate. The example gas channel plate includes a plurality of heat exchange structures separated from one another by intervening gaps. The example heat exchange fluid director plate is supported above a heat exchange surface of the gas channel plate to form a heat exchange fluid channel into which the plurality of heat exchange structures protrude so that heat exchange fluid may flow between and above a portion of the heat exchange structures. Consequently, condensation of process reactants within the showerhead volume may potentially be reduced, as may gas phase and/or surface reaction of process reactants upstream of the substrate. In turn, defect generation caused by gas phase and/or condensed phase reactions may potentially be avoided. It will be understood that the various embodiments described herein are not intended to be limited to solving the example problems referenced within this disclosure, which are provided for illustrative purposes.
The disclosed embodiments may be fabricated from virtually any suitable materials. For example, various structural portions may be fabricated from aluminum, titanium, and/or stainless steel that may provide suitable mechanical, thermal, and/or chemical properties relevant to a particular portion of a selected embodiment. Other portions may be made from suitable ceramics or polymers. For example, various gaskets may include synthetic elastomer and/or fluoroelastomer materials that may provide enhanced chemical resistance to some the process feeds, such as halogenated inorganic compounds, relative to alternative sealing materials. Accordingly, it will be understood that descriptions of example materials or fabrication techniques are provided for illustrative purposes alone. Such descriptions are not intended to be limiting.
FIG. 1 schematically shows a cross-section of an embodiment of a semiconductor process module 100. Semiconductor process module 100 may be used for processing semiconductor substrates via any suitable process, e.g., film deposition, film etch, and the like. While the embodiment of semiconductor process module 100 depicted in FIG. 1 shows a single module, it will be appreciated that any suitable number of process modules may be included in a processing tool so that substrates may be transferred between process modules without being exposed to ambient conditions. For example, some processing tools may include just one module while other processing tools may include two or more modules. While not shown in FIG. 1, various load locks, load ports, and substrate transfer handling robots may be used to transfer substrates between ambient conditions and semiconductor process module 100 before, during, and after substrate processing.
As shown in FIG. 1, semiconductor process module 100 includes a low pressure reactor 102 for processing semiconductor substrates. The process feed is supplied to reactor 102 via a pulse valve manifold 104. Pulse valve manifold 104 delivers the process feeds, including reactant gases and/or inert gases, to reactor 102 via suitable valves and distribution plumbing that manage the flow of the process feed during various portions of substrate processing and/or module maintenance processing events. The process feed is supplied from pulse valve manifold 104 to reactor 102 via a process feed inlet 106.
Process feed inlet 106 opens into a central region of showerhead volume 108 formed between a gas channel plate 110 and a showerhead 112. For example, in some embodiments, an axial centerline of process feed inlet 106 may be aligned with a central axis of showerhead volume 108, so that process feed may potentially be uniformly distributed radially within showerhead volume 108. Showerhead volume 108 provides a space for the process feed flow to develop upon exit from process feed inlet 106, potentially providing time and space for the velocity and flow of the process feed to adjust from the higher velocity conditions likely present within pulse valve manifold 104 to the comparatively lower velocity conditions likely selected for substrate processing. In some embodiments, showerhead volume 108 may enclose a volume of between 100,000 and 800,000 mm3. In one non-limiting example, showerhead volume 108 may enclose a volume of between 300,000 and 500,000 mm3 upstream of a single 300-mm diameter substrate.
In the embodiment shown in FIG. 1, the process feed flows radially from process feed inlet 106 toward the outer edges of showerhead volume 108 while being drawn downward toward showerhead distribution holes 114. In some embodiments, the showerhead volume contours may be shaped so that opposing surfaces of gas channel plate 110 and showerhead 112 that form showerhead volume 108 are closer to one another at the outer edges of showerhead volume 108 than those same surfaces at a central region of showerhead volume 108.
Showerhead distribution holes 114 direct the process feed toward substrate process environment 116 where substrate processing occurs. A susceptor 118 supports a substrate (not shown) within substrate process environment 116 during processing operations. Susceptor 118 may include a heater used to adjust a temperature of the substrate before, during, and/or after substrate processing. Susceptor 118 is mounted on an elevator 120 so that the substrate may be raised and lowered within lower reactor 122 to facilitate substrate transfer in and out of semiconductor process module 100. A lift pin 124 is included to raise and lower the substrate from susceptor 118 during substrate transfer operations.
Portions of unreacted process feed, carrier gases, and gases produced during substrate processing are exhausted from substrate process environment 116 via process exhaust outlet 126. In the embodiment shown in FIG. 1, the process exhaust outlet 126 is formed at least in part by a gap extending around an outer circumference of substrate process environment 116 between showerhead 112 and flow control ring 128. Thus, in the depicted embodiment, a portion of process exhaust flows in radial direction away from a center of substrate process environment 116 toward the process exhaust outlet 126. Other portions of the process exhaust may also flow into lower reactor 122, sealed to showerhead 112 via purge plate 130 with a gasket, via a gap formed between a susceptor 120 and flow control ring 128.
Pressure within reactor 102 is controlled at least in part by one or more pressure control devices (not shown), such as a throttle valve, fluidly coupled with upper reactor exhaust 132 and lower reactor exhaust 134. However, it will be appreciated that pressure within reactor 102 may also be controlled by suitable manipulation of various gas feeds to and bypasses around reactor 102. Accordingly, such feeds and bypasses may also be considered pressure control devices within the scope of the present disclosure.
FIG. 2 schematically shows an exploded isometric view of portions of the embodiment of semiconductor process module 100 shown in FIG. 1. As shown in FIG. 2, a system process controller 202 (described in more detail below) for controlling various aspects of semiconductor process module 100 is provided. System process controller 202 and pulse valve manifold 104 are shown in FIG. 2 as being mounted above gas channel plate 110, showerhead 112, and a heat exchange plenum assembly 204 (described in more detail below) via a support plate 206. A lift point 208 is provided for raising portions of semiconductor process module 100, such as pulse valve manifold 104, for maintenance procedures.
FIG. 2 also shows a plurality of showerhead access covers 210 positioned around showerhead 112. Though not shown in FIG. 2, it will be appreciated that other suitable covers may be provided to shield access to portions of pulse valve manifold 104, portions of upper reactor 104, and/or portions of lower reactor 102. Such access covers may include ventilation ports to permit the passage of air while generally restricting casual tool and/or user access.
FIG. 3 schematically shows a sectioned isometric view of gas channel plate 110 and showerhead 112 taken along line 3 of the embodiment shown in FIG. 2. As shown in FIG. 3, gas channel plate 110 is connected to showerhead 112 by a plurality of clips 302 adapted to maintain a predetermined gap 304 between gas channel plate 110 and showerhead 112. Retaining gas channel plate 110 and showerhead 112 with clips 302 may help to maintain a relative position between the respective parts when semiconductor process module 100 is at ambient pressure.
When semiconductor process module 100 is under vacuum, ambient gases, such as oxygen and water vapor, may diffuse into low pressure environments like showerhead volume 108 and/or process environment 116, potentially contaminating the process feed, generating small particle defects, causing film contamination, impurity incorporation, and/or substrate non-uniformity defects. As used herein, a low pressure environment refers to portions of semiconductor process module 100 that experience sub-ambient pressure during process and/or maintenance operations. For example, showerhead volume 108 may exhibit a pressure within a range of 0.5 to 20 Torr in some non-limiting process settings. As another example, process environment 116 may experience a pressure within a range of 0.5 to 5 Torr in some non-limiting process settings. By reducing the pressure below an ambient pressure within showerhead volume 108 or process environment 116, a low pressure environment is created within that respective portion of semiconductor process module 100.
In some embodiments, gap 304 may act as an exit path for purge gases used to dilute the concentration of ambient gases, reducing their chemical potential for permeation from the outer perimeter (e.g., from an ambient side) of a gasket positioned between showerhead 112 and gas channel plate 110. For example, FIG. 3 shows a purge gas inlet 306 fluidly connected to a network of purge gas channels that that supply purge gas to gap 304. As shown in FIG. 3, a suitable purge gas, like nitrogen, argon, helium, or the like, may be delivered via annular purge channel 308 and a plurality of vertical purge channels 310 to form a near-continuous annular curtain of dry gas emerging from gap 304. Consequently, moisture and/or oxygen permeation across a seal between showerhead 112 and gas channel plate 110 into reactor 102 may be mitigated, potentially reducing film impurities and/or particle defects.
FIG. 4 shows a cross-section taken along line 4 of the embodiment of FIG. 3 illustrating a portion of a purge gas channel 400. Purge gas channel 400 fluidly communicates with an ambient environment via gap 304 at a location between the ambient environment and a gasket 402 disposed between showerhead 112 and gas channel plate 110. So positioned, a positive flow of purge gas from purge gas inlet 306 toward gap 304 may prevent the diffusion of ambient gas toward and/or across gasket 402 and into substrate process environment 116.
As shown in FIG. 4, purge gas channel 400 receives purge gas via a horizontal purge feed 404 from purge gas inlet 306 and distributes the purge gas around gas channel plate 110 via annular purge channel 308. Portions of the purge gas are diverted to vertical purge channels 310 formed at intervals around the outer edge of gas channel plate 110. Vertical purge channels 310 are connected to horizontal purge channels 406 at preselected intervals. Almost any suitable number of vertical purge channels 310 may be provided at virtually any suitable interval. In some embodiments, eighteen vertical purge channels 310 may be evenly spaced around annular purge channel 308. Horizontal purge channels direct the purge gas to gap 304, where the gas emerges into the ambient environment.
The purge gas channels described herein may be formed in almost any suitable manner. Non-limiting examples of techniques for forming the various annular purge gas channels include milling and/or casting. The various vertical purge gas channels may also be formed by drilling, casting, or other suitable techniques. It will be understood that the fabrication of the purge gas channels may leave openings that may result in fugitive emissions of purge gas, potentially leading to pressure drop within the purge system and/or reduced flow rate from gap 304. In some embodiments, some or all of these openings may be fitted with removable and/or permanent closures or seals. For example, FIG. 4 depicts a flexible cord or gasket 408 that may seal an opening above annular purge channel 308 and a cap 410 used to seal horizontal purge feed 404 in some embodiments. Such seals and caps may avoid or reduce fugitive emissions of purge gas from openings used to fabricate the purge gas channels.
Ambient gases may also contaminate the low pressure environment by diffusion from confined spaces after maintenance activity. Such “virtual leaks” can be difficult to trace, as the ambient gas results from gas trapped in so-called “dead volumes,” or volumes that are exposed to the low pressure environment but that are not readily purged or pumped down. Thus, in some embodiments, some seals and gaskets may be positioned within a preselected distance of a low pressure environment such as showerhead volume 108, process environment 116, suitable portions of the process feed upstream of showerhead volume 108 and suitable portions of the process exhaust downstream of process environment 116.
For example, FIG. 4 schematically shows gasket 402 positioned near showerhead volume 108 so that a low pressure environment formed within showerhead volume 108 may pump away residual ambient gases that may be trapped between mating surfaces of showerhead 112 and gas channel plate 110 on a low pressure side of gasket 402. In some embodiments, a seal or gasket may be positioned within a range of 0.5 to 20 mm of a low pressure environment. For example, in some non-limiting scenarios, a gasket may be positioned within a range of 0.5 to 20 mm from a nearest outer edge of showerhead volume 108. In some other scenarios, a gasket may be positioned within 4 mm of a nearest outer edge of showerhead volume 108, within an acceptable tolerance.
As another example, in some embodiments, a seal or gasket sealing showerhead volume 108 may be positioned within a preselected distance of a showerhead distribution hole 114. In the embodiment shown in FIG. 4, gasket 402 is shown positioned near showerhead distribution hole 114. Positioning a gasket near showerhead distribution hole 114 may allow the low pressure environment to rapidly pump away residual ambient gases that may be trapped between mating surfaces of showerhead 112 and gas channel plate 110 on a low pressure side of gasket 402. In some embodiments, a seal or gasket may be positioned within a range of 0.5 to 20 mm of a showerhead distribution hole 114. For example, in some non-limiting scenarios, a gasket may be positioned 5 mm from a nearest showerhead distribution hole 114, within an acceptable tolerance.
It will be appreciated that the approaches to managing ambient gas exposure to the low pressure environment may also be applied to other portions of semiconductor process module 100. For example, purge gas channels may also be included in other portions of semiconductor process module 100 to prevent ambient gas diffusion into substrate process environment 116 and/or low pressure environments. For example, in some embodiments, gas channel plate 110 may include a purge gas channel fluidly communicating with an ambient environment at a location between the ambient environment and a gasket disposed between the gas channel plate and a pulse valve manifold positioned upstream of the gas channel plate.
FIG. 5 schematically shows a sectioned isometric view taken along line 5 of the embodiment shown in FIG. 3. The embodiment shown in FIG. 5 shows an island 312 included in gas channel plate 110 used to mount pulse valve manifold 104 to gas channel plate 110. As shown in FIG. 5, island 312 includes a purge gas inlet 502 fluidly connected to a network of purge gas channels for distributing purge gas within island 312, including an annular purge channel 504 and a plurality of vertical purge channels 506 that supply purge gas to the ambient environment via scallop-shaped gaps 508. In the embodiment depicted in FIG. 5, gaps 508 positioned on an ambient side of a groove 510 adapted retain a gasket sealing island 312 to pulse valve manifold 104 potentially allow a purge gas to prevent ambient gases from permeating beyond the gasket and into the low pressure environment.
FIG. 6 shows a cross-section taken along line 6 of the embodiment shown in FIG. 5, illustrating a portion of a purge gas channel 600. In the embodiment depicted, purge gas enters purge gas channel 600 via purge gas inlet 502 and is distributed to annular purge channel 504 via a horizontal purge feed 602. Annular purge channel 504 distributes the purge gas around island 312 to vertical purge channels 506, which divert portions of the purge gas toward gaps 508 at preselected intervals. Virtually any suitable number of vertical purge channels 506 may be provided at almost any suitable interval. In some embodiments, six vertical purge channels 506 may be evenly spaced around annular purge channel 504 within island 312. As shown in FIG. 6, gaps 508 opening on to each vertical purge channel 506 permit purge gas to flow from purge gas channel 600 into the ambient environment at a position between the ambient environment and sealing groove 510. FIG. 6 also depicts a flexible cord or gasket 604 that may seal an opening above annular purge channel 504 and a cap 606 used to seal horizontal purge feed 602 in some embodiments. Such closures may avoid or reduce fugitive emissions of purge gas from openings used to fabricate the purge gas channels.
As another example, in some embodiments, a purge plate 130 may include purge gas channels configured to prevent diffusion of ambient gases across gaskets sealing showerhead 112 to purge plate 130 and/or lower reactor 122 to purge plate 130. For example, FIG. 7 shows a close-up of the embodiment of purge plate 130 shown in FIG. 2 taken along line 7. As shown in FIG. 7, purge plate 130 includes a purge gas inlet 702 fluidly connected to a purge gas channel for distributing purge gas within purge plate 130. For reference, the embodiment of purge plate 130 shown in FIG. 7 includes an upper surface 704 that interfaces with showerhead 112 and a lower surface 706 that interfaces with lower reactor 122.
The purge gas channel shown in FIG. 7 includes an annular purge channel 708 that is fluidly connected with a plurality of upwardly extending vertical purge channels 710 that purge an ambient environment around a gasket that seals upper surface 704 to showerhead 112. Annular purge channel 708 is also fluidly connected with a plurality of downwardly extending vertical purge channels 712 that purge an ambient environment around a gasket that seals lower surface 706 to lower reactor 122.
FIGS. 8 and 9 show cross-sections of the embodiment shown in FIG. 7 taken along lines 8 and 9, respectively, illustrating portions of a purge gas channel 800. As shown in FIG. 8, purge gas enters purge gas channel 800 via purge gas inlet 702 and is distributed to annular purge channel 708 via a horizontal purge feed 802. Annular purge channel 708 distributes the purge gas around purge plate 130 to vertical purge channels 710 and 712, which divert portions of the purge gas toward gaps 904, shown in FIG. 9 as 904a and 904b, at preselected intervals. Virtually any suitable number of vertical purge channels 710 and 712 may be provided at almost any suitable interval. In some embodiments, fourteen pairs of vertical purge channels 710 and 712 may be evenly spaced around annular purge channel 708 within purge plate 130.
The embodiment shown in FIG. 9 shows gaps 904a and 904b coupling vertical purge channels 710 and 712 with the ambient environment at positions between the ambient environment and gaskets provided to seal purge plate 130 to adjacent surfaces. So positioned, gaps 904a and 904b allow purge gas to sweep ambient gases away from the gaskets, potentially reducing permeation of ambient gases across those gaskets. Thus, purge gas flowing toward showerhead 112 will flow into gap 904a at a position between the ambient environment and gasket 906a, and purge gas flowing toward lower reactor 122 will flow into gap 904b at a position between the ambient environment and gasket 906b. FIGS. 8 and 9 also depict a flexible cord or gasket 804 that may be used to seal an opening above annular purge channel 708 and a cap 806 that may be used to seal horizontal purge feed 802 in some embodiments. Such closures may avoid or reduce fugitive emissions of purge gas from openings used to fabricate the purge gas channels.
Process feed conditions within pulse valve manifold 104 may be adapted to high speed, high pressure delivery of various process feed species to enhance substrate throughput and process speed. However, the rapid expansion of process feed from these conditions into lower pressure conditions within showerhead volume 108 may potentially contribute to substrate process control problems and/or substrate quality excursions. For example, the process feed may experience transient cooling as process feed pressure drops in the vicinity of process feed inlet 106, potentially cooling surfaces surrounding process feed inlet 106. In turn, this may cause condensation of some species of the process feed onto gas channel plate 110 near process feed inlet 106. Further, in some settings, rapid expansion of the process feed may alter fluid mixing of various reactants and inert species included in the process feed. Accordingly, in some embodiments, flow expansion structures may be provided upstream of process feed inlet 106 to transition flow conditions within the process feed.
FIG. 10 schematically shows a sectioned isometric view of an embodiment of showerhead volume 108 formed between a diffusion surface 1012 of gas channel plate 110 and showerhead 112. As shown in FIG. 10, an optional flow expansion structure 1002 is provided upstream of process feed inlet 106. In some embodiments, flow expansion structure 1002 may assist in transitioning and mixing higher velocity process feed flows exiting pulse valve manifold 104 (shown in FIG. 1) into slower velocity flows within showerhead volume 108 prior to distribution to process environment 116 via showerhead distribution holes 114. For example, in embodiments used in ALD processes, higher velocity pulse trains provided from pulse valve manifold 104 may be transitioned to a slower flow velocity, at least in part, by transmission of the pulse train through flow expansion structure 1002 before a subsequent expansion at the process feed inlet 106.
In the embodiment shown in FIG. 10, a centerline of a flow path included in flow expansion structure 1002 is aligned with a centerline of process feed inlet 106, so that fluid flow within flow expansion structure 1002 may transition smoothly between a smaller upstream diameter and a larger downstream diameter of flow expansion structure 1002. In some embodiments, an upstream diameter of flow expansion structure 1002 may be approximately 5⁄8 of an inch and a downstream diameter may be approximately 1 inch.
Virtually any suitable manner of expanding fluid flow within flow expansion structure 1002 may be employed without departing from the scope of the present disclosure. As shown in FIG. 10, flow expansion structure 1002 includes a concentric conical expansion shape formed on an inner surface 1006 of the flow expansion structure. Other non-limiting examples of expansion shapes that may be formed on inner surface 1006 include bell-shaped expansion shapes, spiral expansion shapes, and the like, implementations of which may have upstream and downstream diameters that may be concentric or eccentric with one another.
In the embodiment shown in FIG. 10, flow expansion structure 1002 is retained in gas channel plate 110 by a support ledge. A gasket 1050 forms a seal between the support ledge and flow expansion structure 1002. In some embodiments, gasket 1050 may be provided within a predetermined distance, such as a predetermined vertical distance, of showerhead volume 108. This may reduce an interfacial volume formed between mating surfaces of flow expansion structure 1002 and gas channel plate 110 on a low pressure side of gasket 1050, so that residual ambient gases within that interfacial volume may be rapidly pumped away.
The example shown in FIG. 10 also depicts a gasket 1052 for sealing flow expansion structure 1002 to pulse valve manifold 104 (not shown). In some embodiments, gasket 1052 may be provided within a predetermined distance of inner surface 1006. This may reduce an interfacial volume formed between mating surfaces of flow expansion structure 1002 and pulse valve manifold 104 on a low pressure side of gasket 1052, which may potentially have the effect of rapidly pumping away residual ambient gases within that interfacial volume.
An optional impingement plate 1010 is shown in FIG. 10 that may protect showerhead 108 from particles entrained in the process feed and/or assist in redirecting flow of process feed toward outer edges of showerhead volume 108. In some embodiments, impingement plate 1010 may include holes aligned with showerhead distribution holes 114 to avoid formation of a shadow on center portion of a substrate disposed beneath impingement plate 1010. As shown in FIG. 10, impingement plate may be fastened to flow expansion structure 1002 by attachment to a retaining position formed on inner surface 1006 and supported by one or more mounting structures 1008. In embodiments that exclude flow expansion structure 1002, impingement plate 1010 may be attached to a suitable retaining position formed on an inner surface of process feed inlet 106.
As the process feed entering showerhead volume 108 via process feed inlet 106 expands, the velocity and flow orientation of the process feed changes. In the embodiment shown in FIG. 10, the process feed spreads radially from process feed inlet 106 toward outer edges of showerhead volume 108 and showerhead distribution holes 114. Without wishing to be bound by theory, a radial pressure distribution may develop within the embodiment of showerhead volume 108 depicted in FIG. 10. This pressure distribution may result from frictional forces as the process feed flows across diffusion surface 1012 and along an upper surface 1014 of showerhead 112. Radial pressure variation may also result from flow of the process feed out of showerhead volume 108 via showerhead distribution holes 114. In turn, the process feed velocity may diminish as the distance from the process feed inlet 106 increases. Further, because various species within the process feed, such as reactant gases and carrier gases, may have different molecular weights, diffusion rates of those species within showerhead volume 108 may also be affected by local changes in pressure and gas density. Consequently, process feed distribution to the substrate may be time and position variant, potentially leading to substrate non-uniformity defects.
Accordingly, in some embodiments, showerhead volume 108 may be contoured to enhance the flow of the process feed toward the radial edges of showerhead volume 108. In the embodiment shown in FIG. 10, diffusion surface 1012 includes a radially symmetric profile with respect to an axial centerline of the process feed inlet 106, so that diffusion surface 1012 becomes closer to showerhead 112 as a distance from the axial centerline of the process feed inlet 106 increases. In other words, the surfaces of gas channel plate 110 and showerhead 112 are closer together at the outer edges of showerhead volume 108 than they are at a central region of showerhead volume 108. Thus, as portions of the process feed are distributed via showerhead distribution holes 114, the process feed pressure within a fluid element moving radially outward in showerhead volume 108 may remain approximately constant (within an acceptable tolerance). In turn, the velocity and concentration characteristics of that fluid element may remain approximately constant.
While the embodiment in FIG. 10 shows contours of showerhead volume 108 formed by diffusion surface 1012 of gas channel plate 110, it will be appreciated that some embodiments of showerhead volume 108 may include contours formed in gas channel plate 110 and/or showerhead 112. For example, FIG. 11 schematically shows a sectioned isometric view of another embodiment of a showerhead volume 1100 formed between an upper surface 1102 of showerhead 112 and a diffusion surface 1104 of gas channel plate 110. In the embodiment shown in FIG. 11, upper surface 1102 and diffusion surface 1104 are depicted as being parallel with one another, each surface including a radially symmetric profile with respect to an axial centerline of the process feed inlet 106, so that the surfaces remain the same distance apart as a distance from the axial centerline of the process feed inlet 106 increases. For example, in some embodiments, the distance between upper surface 1102 and a lower surface 1150 of showerhead 112 defining an upper surface of process environment 116 may be contoured to provide a preselected residence time distribution of fluid flowing through showerhead distribution holes 114. In one non-limiting scenario, the distance between upper surface 1102 and lower surface 1150 may be configured so that a residence time of a fluid element flowing through a showerhead distribution hole 114 at the center of showerhead 112 (shown in FIG. 11 at 114a) may be within ten percent of a residence time of a fluid element flowing through a showerhead distribution hole 114 positioned at an outer edge of showerhead 112 (shown at 114b). In some settings, providing a constant residence time (within an acceptable tolerance) for fluid flowing within showerhead distribution holes 114 may provide an approximately constant delivery of reactive process feed to the surface of the substrate. In turn, film deposition on the substrate may have enhanced thickness uniformity. In still other embodiments, the diffusion surface of gas channel plate 110 may be configured as a plane surface while a surface of showerhead 112 exposed to showerhead volume 108 may be contoured.
It will be appreciated that almost any suitable contour may be applied to the showerhead volumes described herein without departing from the scope of the present disclosure. In some embodiments, a linearly-shaped radially symmetric profile may be formed on a portion of diffusion surface 1012 and/or upper surface 1014 of the showerhead exposed to showerhead volume 108, the linearly-shaped portion being disposed at an angle of between 0 and 5 degrees with respect to a reference plane positioned parallel with the substrate, such as a reference plane defining a widest portion of showerhead volume 108. For example, where diffusion surface 1012 of gas channel plate 110 is contoured, the linearly shaped portion may be formed at a negative angle of between 0 and −5 degrees with respect to the reference plane. Where upper surface 1014 of showerhead 112 is contoured, the linearly-shaped portion may be formed at a positive angle of between 0 and 5 degrees with respect to the reference plane. Thus, in the embodiment shown in FIG. 10, diffusion surface 1012 may have linear portion being disposed at an angle of between 0 and −5 degrees with respect to a reference plane defining a widest portion of showerhead volume 108. In the embodiment shown in FIG. 11, diffusion surface 1104 may have linear portion being disposed at an angle of between 0 and −5 degrees and upper surface 1102 may have linear portion being disposed at an angle of between 0 and +5 degrees with a reference plane defining a widest portion of showerhead volume 108.
In some other embodiments, non-linear shapes may be formed into portions of a diffusion surface and/or surfaces of a showerhead exposed to a showerhead volume. For example, a portion of a diffusion surface may exhibit a Gaussian-shaped or bell-shaped profile when viewed in cross-section with respect to a reference plane positioned parallel to a substrate, such as a reference plane defining a widest portion of a showerhead volume. The various contours described herein may be formed over any suitable portion of the surfaces on which they are formed. For example, a contour formed on gas channel plate 110 and/or showerhead 112 may be formed so that more than 95% of a surface of respective part exhibits a contour as described herein. Such contours may be formed in almost any suitable manner. For example, the contours may be formed by milling, casting, water jet cutting and/or laser cutting.
While the embodiments illustrated in the figures depict contoured surfaces of example showerheads 112 and gas channel plates 110 that are integrated into those respective items, it will be understood that in some embodiments contoured surfaces may be prepared as separate parts that may be installed into and removed from their respective parts. For example, a first set of contours configured for a first process chemistry may be fitted to a gas channel plate 110 and/or a showerhead 112 and later removed and replaced by a second set of contours configured for a second process chemistry. This may allow for the rapid development and testing of various contours, for example using suitable three-dimensional printing technology, without the replacement of entire showerhead and/or gas channel plate assemblies.
As shown in FIGS. 10 and 11, showerhead 112 includes an annular exhaust passage 1016 integrated within a single body. Annular exhaust passage 1016 conducts the process exhaust from substrate process environment 116 via process exhaust outlet 126 toward upper reactor exhaust 132 (as shown in FIG. 1).
In some embodiments, showerhead 112 may comprise an exhaust body configured to gather process exhaust that is separate from a body that distributes the process feed to the substrate. While a single-body showerhead may potentially avoid some dead volumes formed near the outer region of process environment 116, it will be appreciated that a two-piece showerhead may offer other advantages. For example, a two-piece showerhead 112 may allow differently profiled gas distribution bodies to be retrofitted to semiconductor process module 100 without moving the exhaust collection body. In turn, re-calibration of a gap included in the process exhaust outlet 126 may be minor relative to procedures for replacement of a single-body showerhead. FIG. 12 schematically shows a section isometric view of an embodiment of a two-piece showerhead 1200 including a gas distribution body 1202 and an annularly-shaped exhaust passage body 1204. As shown in FIG. 12, gas distribution body 1202 includes a plurality of showerhead distribution holes 114 that distribute process feed to substrate process environment 116. In the embodiment illustrated in FIG. 12, gas distribution body 1202 is sealed to gas channel plate 110 via gasket 402 and to exhaust passage body 1204 via gasket 1206. In some embodiments, gasket 1206 may be positioned within a predetermined distance of process environment 116, which may reduce the potential to trap ambient gases between gas distribution body 1202 and exhaust passage body 1204. Exhaust passage body 1204 is depicted as being sealed to purge plate 130 via gasket 906. Exhaust passage body 1204 includes an annular exhaust passage 1208 that conducts process exhaust from process environment 116 via a gap formed between exhaust passage body 1204 and flow control ring 128.
Some low vapor pressure species included in process feeds supplied to a substrate during substrate processing may condense on process surfaces under some process conditions. For example, some species may condense on surfaces within showerhead volume 108. Accordingly, in some embodiments, semiconductor process module 100 may include heat exchange structures thermally coupled with showerhead volume 108 to adjust a temperature of showerhead volume 108. As used herein, being thermally coupled means that causing a change in temperature of at a heat exchange structure will cause in a change in temperature at a surface of showerhead volume 108 and vice-versa. Such temperature changes may be determined by various suitable techniques, such as infrared- or thermocouple-based temperature measurement techniques.
Such heat exchange structures may be included on a heat exchange surface of gas channel plate 110 that project into a heat exchange fluid. Other heat exchange mechanisms, such as heaters, may also be thermally coupled with showerhead volume 108. In turn, the temperature of showerhead volume 108 may be adjusted during substrate processing so that process feed condensation might potentially be avoided.
FIG. 13 schematically shows a close-up sectioned isometric view of a portion of an embodiment of gas channel plate 110. The embodiment shown in FIG. 13 depicts a heater groove included in gas channel plate 110, shown as heater groove 1302a. A heater is included in the heater groove, shown as heater 1304a. Heater 1304a provides heat to gas channel plate 110 and to various surfaces in thermal contact with gas channel plate 110, such as diffusion surface 1012, showerhead 112, and so on. In turn, condensation of process feed on diffusion surface 1012, flow expansion structure 1002 (shown in FIG. 10), and/or surfaces of showerhead volume 108 may potentially be avoided.
In some embodiments, a plurality of heaters may be provided in gas channel plate 110 and showerhead 112, each controlled and powered independently from one another. For example, FIG. 13 shows a heater 1304b included in a heater groove 1302b included in showerhead 112, heater 1304b being independent from and controlled separately from heater 1304a. Such an arrangement may be used to provide locational “zone” heating to different portions of gas channel plate 110 and/or showerhead 112. In combination with suitable heater control, zone heating permit the creation of various temperature profiles within showerhead volume 108, showerhead 112, and gas channel plate 110. For example, gas channel plate 110 may be maintained at a lower temperature than showerhead 112, potentially preventing the accumulation of reaction byproducts in exhaust passage 1016. As another example, an arrangement of annularly-nested independently-zoned heaters provided within gas channel plate 110 may allow the creation of a radial temperature profile extending from process feed inlet 106 toward the outer edges of showerhead volume 108. In turn, a central region of showerhead volume 108 may be maintained at a comparatively higher temperature than the outer edges. This approach may potentially prevent condensation of a low-vapor pressure process species near process feed inlet 106, where the partial pressure of that species may be higher.
It will be understood that almost any suitable heater may be employed without departing from the scope of the present disclosure. In some embodiments, a flexible, cable-style heater may be provided that is configured to fit into a heater groove cut into gas channel plate 110. In some embodiments, a heater may include positive temperature coefficient materials configured to exhibit an increase in electrical resistance as temperature increases beyond a predetermined threshold, potentially reducing a risk of damage from temperature excursions exceeding a predetermined ceiling relative to alternate style heaters. In the embodiment shown in FIG. 13, a heater is powered by electricity supplied via a heater power connection 1306 which receives power from a heater controller via a heater power lead (shown as heater power lead 1308 in FIGS. 10-12).
As introduced above, a heater groove is formed into gas channel plate 110 and/or showerhead 112 to receive heat from a heater. Viewed as a cross-section, the sidewalls and bottom of a heater groove may make contact with a heater at several locations, potentially improving heat transfer from heater relative to configurations where a heater makes contact on one side only, such as a heater resting on a surface. It will be understood that the heater groove may be formed into gas channel plate 110 and/or showerhead 112 in virtually any suitable manner. For example, a heater groove may be milled and/or cast in some embodiments. Further, the heater groove may be shaped into virtually any suitable form. Non-limiting examples of shapes for a heater groove include annular, serpentine paths having twists in at least two directions, and spiral paths that may or may not include branches. Such shapes may be arranged in almost any suitable position within gas channel plate 110 and/or showerhead 112. For example, in some embodiments, heater grooves may be positioned around a center of gas channel plate 110 and/or showerhead 112 in a radially-symmetric arrangement.
In some embodiments, a retainer, shown as retainers 1310a and 1310b in FIG. 13, may be provided above heater 1304a and 1304b, respectively to apply a downward force to the heaters, potentially enhancing conduction between the heater groove and the heater. Further, in some of such embodiments, the retainer may have heat transfer properties that further enhance heat transfer from the heater to gas channel plate 110 and/or showerhead 112. For example, the retainer may be formed from a flexible aluminum wire that may help conduct heat from a top surface of the heater to upper sidewalls of the heater groove.
Additionally or alternatively, in some embodiments, a temperature of gas channel plate 110 may be adjusted using a suitable heat exchange fluid supplied to heat exchange surfaces thereon. For example, in one scenario, cool air may be provided to moderate heating provided by the heater. In another scenario, warm air may be provided in place of or to supplement heating provided by the heater. In each scenario, use of a heat exchange fluid may potentially smooth a thermal profile within gas channel plate 110, so that hot and/or cold spots may be avoided. Virtually any suitable heat exchange fluid may be employed without departing from the scope of the present disclosure. Example suitable heat exchange fluids include, but are not limited to, gases like air and nitrogen, and liquids like water and heat transfer oils.
The embodiment depicted in FIG. 13 shows a plurality of heat exchange structures 1312 separated from one another by gaps 1314 on a heat exchange surface 1316 of gas channel plate 110. Heat exchange structures 1312 and gaps 1314 provide surface area for heat transfer and flow space, respectively, for the heat exchange fluid.
It will be understood that heat exchange structures 1312 may have almost any suitable shape. The embodiment shown in FIG. 13 illustrates heat exchange structures 1312 as rectangularly-shaped, block-like structures projecting outward from heat exchange surface 1316. In some embodiments, heat exchange structures 1312 may be rectangular prisms that are 4 mm wide by 6 mm deep, within an acceptable tolerance, and that may have heights that vary between 12 mm and 5 mm, so that the volume of heat exchange structures 1312 may vary with position as described in more detail below. In some embodiments, gaps 1314 between heat exchange structures 1312 may be approximately 6-7 mm wide. Additionally or alternatively, in some embodiments, gaps 1314 may be sized so that they are no wider than one-half of a thickness of gas channel plate 110 at a location on gas channel plate 110 where heat exchange structures 1312 are positioned on gas channel plate 110. For example, in some embodiments, gaps 1314 may be sized according to a preselected ratio defined as of a distance from a base of heat exchange structure 1312 to diffusion surface 1012 divided by a distance between adjacent heat exchange structures 1312. In some embodiments, the ratio may be greater than 2. For example, in some non-limiting scenarios, the ratio may be in a range between 3 and 5. Spacing heat exchange structures 1312 in this way may avoid the formation of local hot and/or cold spots on diffusion surface 1012. Other non-limiting heat exchange structures may include outwardly projected fin- or vane-shaped structures, honeycomb or mesh type baffled structures, and stacked plates.
In some embodiments, the volume of heat exchange structures 1312 may vary according to a radial position on heat exchange surface 1316. By varying the volume according to radial position, it is possible that the amount of heat exchanged with the heat exchange fluid may be regulated. In the embodiment shown in FIG. 13, volume of heat exchange structures 1312 increases with radial distance from a center of gas channel plate 110. In one scenario according to this embodiment, less heat may be transferred to the heat exchange fluid near the center of the gas channel plate relative to an amount of heat transferred near the outer edge. As a result, the center region of the diffusion surface may be maintained at a comparatively higher temperature than the outer region. This approach may potentially prevent condensation of a low-vapor pressure process species near the process feed inlet, where the partial pressure of that species may be higher. Further, by transitioning to a lower temperature near the outer edge of the diffusion surface, the defect generation caused by gas phase reactions may potentially be avoided.
Heat exchange structures 1312 may be formed in any suitable manner and from any suitable material. For example, in some embodiments, heat exchange structures 1312 may be formed from aluminum, stainless steel, or titanium. Heat exchange structures 1312 may also be formed during fabrication of gas channel plate 110 or added at a later time. For example, in some embodiments, heat exchange structures 1312 may be machined into gas channel plate 110. In some other embodiments, heat exchange structures 1312 may be separate parts that may be added, subtracted, and rearranged on heat exchange surface 1316.
Heat exchange structures 1312 may be distributed in virtually any suitable arrangement on gas channel plate 110. In the embodiment shown in FIG. 13, heat exchange structures 1312 are distributed in an annular region, being radially arranged about a centerline of gas channel plate 110. FIG. 3 and FIGS. 10-12 also show examples of heat exchange structures 1312 arranged in circular patterns around process feed inlet 106 in an annular region of gas channel plate 110.
As shown in FIG. 13, heat exchange structures 1312 project into a heat exchange fluid channel 1318 formed between heat exchange surface 1316 and a heat exchange fluid director plate 1320 supported by a heat exchange fluid director plate support surface of gas channel plate 110. Thus, heat exchange fluid director plate 1320 and gas channel plate 110 form a heat exchanger in the region of heat exchange fluid channel 1318, where heat exchange fluid director plate 1320 directs heat exchange fluid in between of heat exchange structures 1312 and also across the tops of at least a portion of heat exchange structures 1312.
The broad flow direction arrows illustrated in FIG. 13 depict an example flow of heat exchange fluid from an inlet 1324 into heat exchange fluid channel 1318 where heat is exchanged with heat exchange structures 1312 and then exhausted via an outlet 1326. By arranging heat exchange structures 1312 in circular patterns around a center of gas channel plate 110 and directing the heat exchange fluid radially outward from inlet 1324, the heat exchange fluid flowing in heat exchange fluid channel 1318 may flow co-currently with process feed flowing within showerhead volume 108. Consequently, a temperature of the process feed at the edge of showerhead volume 108 may be at least as great as a temperature of the heat exchange fluid exiting outlet 1326. This may potentially avoid decomposition reactions within the process feed or on the various surfaces defining showerhead volume 108.
While the flow direction arrows in FIG. 13 depict a flow of heat exchange fluid flowing radially outward in a circularly symmetric flow, it will be appreciated that virtually any suitable flow of heat exchange fluid may be employed without departing from the scope of the present disclosure. For example, in some embodiments, heat exchange fluid may be directed radially inward from an outer edge of gas channel plate 110 toward island 312. In some of such embodiments, the locations of inlet 1324 and outlet 1326 may be reversed or otherwise suitable relocated. In still other embodiments, heat exchange fluid may be directed in other directions around and/or across heat exchange surface 1316 so that it flows around and/or above heat exchange structures 1312.
In some embodiments, heat exchange fluid director plate 1320 may be included in heat exchange plenum assembly 204. Heat exchange plenum assembly 204 may provide ambient air as a heat exchange fluid to heat exchange surface 1316 via heat exchange fluid channel 1318 and then exhaust the air back into the ambient environment. FIG. 14 schematically shows heat exchange plenum assembly 204 fluidly coupled to an embodiment of a blower 1402 by a flexible duct 1404. As shown in FIG. 14, blower 1402 draws ambient air into intake 1406. The air is delivered by flexible duct 1404 to heat exchange plenum assembly 204. After passing over the heat exchange surface of the gas channel plate (not shown), the air is exhausted via exhaust holes 1408 into the ambient environment.
FIG. 15 schematically shows an exploded isometric view of an embodiment of a heat exchange plenum assembly 1500. As shown in FIG. 15, heat exchange plenum assembly 1500 includes a heat exchange fluid director plate 1502 and a cover plate 1504. Heat exchange fluid director plate 1502 includes a ring-shaped inner wall 1506, a ring-shaped outer wall 1508 having a larger diameter than inner wall 1506, and a floor ring 1510 that connects inner wall 1506 and outer wall 1508. Outer wall 1508 includes opening 1512 to receive an inlet duct 1514 coupled to a blower (not shown). Inlet duct 1514 may include an optional switch 1516 used to control the blower. Floor ring 1510 includes one or more openings adjacent to inner wall 1506 that form inlets 1518.
In some embodiments, heat exchange fluid director plate 1502 is configured to be supported by a heat exchange fluid director plate support surface included on gas channel plate 110. For example, in some embodiments, inner wall 1506 may be sized to fit snugly about and/or be physically connected with island 312 of gas channel plate 110 for supporting heat exchange fluid director plate 1502. Additionally or alternatively, in some embodiments, heat exchange fluid director plate 1502 may be supported by island 312 via retainer 1520 and/or cover plate 1504. By supporting heat exchange fluid director plate 1502 on island 312, floor ring 1510 of heat exchange fluid director plate 1502 may be spaced from heat exchange surface 1316 of gas channel plate 110 so that heat exchange fluid channel 1318 is formed above heat exchange structures 1312. In turn, heat exchange fluid flowing in heat exchange fluid channel 1318 may flow between and above heat exchange structures 1312 while flowing from inlet 1324 to outlet 1326, as shown in FIG. 13. Consequently, heat exchange fluid channel 1318 may accommodate heat exchange structures 1312 of varying heights as described above, and may also exchange heat along top surfaces of heat exchange structures 1312 in contact with the heat exchange fluid.
Returning to FIG. 15, in some embodiments, one or more inlets 1518 may be distributed around a base of inner wall 1506, so that heat exchange fluid may be supplied in an annular flow to gas channel plate 110. In such embodiments, the assembly of heat exchange fluid director plate 1502 to cover plate 1504 via retainer 1520 and gasket 1522 forms an annular fluid flow space between inner wall 1506, outer wall 1508, cover plate 1504, and floor ring 1510. Thus, a heat exchange fluid may enter via opening 1512, travel around the annular flow space, and be distributed to heat exchange fluid channel 1318 via inlets 1518 where it may be redirected to travel radially outward toward the edges of gas channel plate 110. For example, FIG. 16 schematically shows a sectioned isometric view of an embodiment of a portion of inlet duct 1514 directing air toward an annular region 1602 formed between heat exchange fluid director plate 1502 and cover plate 1504. In the embodiment shown in FIG. 16, air flows radially outward from annular region 1602 via heat exchange fluid channel 1318 where it is exhausted from semiconductor process module 100 via exhaust holes 1408.
In some embodiments, heat exchange plenum assembly 1500 may include a flow restrictor positioned at outlet 1326 of heat exchange fluid channel 1318 and configured to adjust the flow of heat exchange fluid therein. For example, FIG. 15 shows an embodiment of a flow restrictor ring 1524 coupled to heat exchange fluid director plate 1502. As shown in FIG. 15, flow restrictor ring 1524 includes at least one restriction orifice 1526 positioned to restrict flow through outlet 1326 and a clearance opening 1528 configured to receive inlet duct 1514.
In some embodiments, the height of flow restrictor ring 1524 may be adjusted to vary the heat exchange characteristics of heat exchange fluid channel 1318. For example, given constant inlet and outlet cross-sectional areas, increasing the height of flow restrictor ring 1524 may increase the residence time of the heat exchange fluid within the heat exchange fluid channel 1318, potentially varying the radial temperature profile of the gas channel plate. It will be appreciated that adjustments to the cross-sectional areas of the inlet and outlet may have a similar effect.
It will be appreciated that thermal management of showerhead volume 108 may be systematically controlled by suitable temperatures sensors and heater and/or heat exchanger controllers in some embodiments. Thus, a temperature of gas channel plate 110, showerhead 112, flow expansion structure 1002 and/or other portions of semiconductor process module 100 thermally coupled with showerhead volume 108 may be adjusted during substrate processing, potentially avoiding condensation and/or gas phase reactions of the process feed.
For example, FIG. 16 shows a temperature sensor 1604 included in showerhead 112 and thermally coupled with showerhead volume 108. While temperature sensor 1604 is physically positioned in showerhead 112 in the embodiment shown in FIG. 16, it will be appreciated that one or more temperature sensors 1604 may be provided at suitable locations in showerhead 112 and/or gas channel plate 110. In some embodiments, a plurality of temperature sensors 1604 may be provided in various locations around showerhead 112 and/or gas channel plate 110 to provide a thermal map of those parts and nearby portions of showerhead volume 108. Virtually any suitable temperature sensor 1604 may be employed without departing from the scope of the present disclosure. Non-limiting examples include bi-junction thermocouples and resistance thermometers.
Temperature information collected by one or more temperature sensors 1604 may be provided to a thermal controller 1606 with which the temperature sensors 1604 are electrically connected. In some embodiments, thermal controller 1606 may include a heater controller for controlling heaters 1304 and/or a blower controller for controller blower 1402. In some embodiments, thermal controller 1606 may be included in system controller 202. In turn, thermal controller 1606 may adjust power supplied to heater 1304 via heater power connection 1306. Additionally or alternatively, in some embodiments, thermal controller 1606 may adjust operation of blower 1402 in response to temperature information provided by temperature sensors 1604. For example, thermal controller 1606 may turn blower 1402 off or on or vary the blower speed to adjust an amount of air delivered.
It will be understood that the hardware described herein may be used to adjust the temperature of the process feeds a showerhead volume in a semiconductor processing module and, in turn, deliver the process feeds from the showerhead volume to the substrate to process a substrate within the module.
FIG. 17 shows a flow chart for an embodiment of a method 1700 for processing a substrate in a processing environment of a reactor included in semiconductor processing module. Method 1700 may be performed by any suitable hardware and software. It will be appreciated that portions of the processes described in method 1700 may be omitted, reordered, and/or supplemented without departing from the scope of the present disclosure.
Method 1700 includes, at 1702, supporting the substrate with a susceptor within the reactor and, at 1704, supplying process feed to the reactor via a showerhead positioned above the substrate. For example, in an ALD process, the process feed may be supplied to the reactor via the showerhead so that a suitable coverage of a surface active species derived from the process feed is generated on a process surface of the substrate.
At 1706, method 1700 includes adjusting a temperature of the process feed within a showerhead volume upstream of the showerhead by supplying a heat exchange fluid to a heat exchange fluid channel into which a plurality of heat exchange structures extend so that the heat exchange fluid flows between and above the heat exchange structures within the heat exchange fluid channel, the heat exchange structures being thermally coupled with the showerhead volume.
In some embodiments, adjusting the temperature at 1706 may include, at 1708, receiving a temperature of a heat exchange surface from which the heat exchange structures extend from a temperature sensor thermally coupled with the heat exchange surface. For example, process feed temperature information may be received from one or more temperature sensors. If a temperature of the process feed is judged to be too low relative to a predetermined temperature, action may be taken to raise the temperature of the heat exchange surface so that a temperature of the process feed within the showerhead may be raised. Alternatively, if a temperature of the heat exchange surface is judged to be too high relative to a predetermined temperature, a different action may be taken to lower the temperature of the heat exchange surface so that the temperature of the process feed within the showerhead volume may be lowered.
For example, in some embodiments, method 1700 may include, at 1710, adjusting a power supplied to a heating element included in the heat exchange surface. In a scenario where the heat exchange surface exceeds the predetermined temperature, the power supplied to the heater may be reduced. Alternatively, in a scenario where the heat exchange surface is less than the predetermined temperature, the power supplied to the heater may be increased. It will be appreciated that almost any suitable method of controlling the heater power may be employed without departing from the scope of the present disclosure, including control schemes that include one or more of proportional, derivative, and integral elements.
As another example, in some embodiments, method 1700 may include, at 1712, adjusting power supplied to a blower or pump configured to supply heat exchange fluid to the heat exchange surface. In a scenario where the heat exchange surface exceeds the predetermined temperature, the power supplied to the blower or pump may be reduced. Alternatively, in a scenario where the heat exchange surface is less than the predetermined temperature, the power supplied to the blower or pump may be increased. It will be appreciated that almost any suitable method of controlling the blower or pump power may be employed without departing from the scope of the present disclosure, including control schemes that include one or more of proportional, derivative, and integral elements.
In some embodiments, the heater and the blower or pump may be operated concurrently. For example, in one scenario, a blower may provide cool air continuously while a heater power is adjusted to vary heat input to the heat exchange surface. In another scenario, a heater may provide a continuous heat input while a blower power is adjusted to vary cooling provided to the heat exchange surface. In yet another scenario, both heater and blower power may be adjusted concurrently to control heating and cooling of the heat exchange surface.
In some embodiments, method 1700 may be performed by a system process controller comprising a data-holding subsystem comprising instructions executable by a logic subsystem to perform the processes described herein. Virtually any suitable system process controller may be employed without departing from the scope of the present disclosure.
For example, FIG. 2 shows an embodiment of a system process controller 202 provided for controlling semiconductor process module 100. System process controller 202 may operate process module control subsystems, such as gas control subsystems, pressure control subsystems, temperature control subsystems, electrical control subsystems, and mechanical control subsystems. Such control subsystems may receive various signals provided by sensors, relays, and controllers and make suitable adjustments in response.
System process controller 202 comprises a computing system that includes a data-holding subsystem and a logic subsystem. The data-holding subsystem may include one or more physical, non-transitory, devices configured to hold data and/or instructions executable by the logic subsystem to implement the methods and processes described herein. The logic subsystem may include one or more physical devices configured to execute one or more instructions stored in the data-holding subsystem. The logic subsystem may include one or more processors that are configured to execute software instructions.
In some embodiments, such instructions may control the execution of process recipes. Generally, a process recipe includes a sequential description of process parameters used to process a substrate, such parameters including time, temperature, pressure, and concentration, etc., as well as various parameters describing electrical, mechanical, and environmental aspects of the tool during substrate processing. The instructions may also control the execution of various maintenance recipes used during maintenance procedures and the like. In some embodiments, such instructions may be stored on removable computer-readable storage media, which may be used to store and/or transfer data and/or instructions executable to implement the methods and processes described herein. It will be appreciated that any suitable removable computer-readable storage media may be employed without departing from the scope of the present disclosure. Non-limiting examples include DVDs, CD-ROMs, floppy discs, and flash drives.
It is to be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, the various acts illustrated may be performed in the sequence illustrated, in other sequences, or omitted in some cases.
The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.

## Claims

1. A semiconductor process module comprising a reactor, wherein the reactor comprises:
a gas channel plate, the gas channel plate comprising:
a heat exchange surface including a plurality of heat exchange structures separated from one another by intervening gaps;
a heat exchange fluid director plate support surface for supporting a heat exchange fluid director plate above the plurality of heat exchange structures so that at least a portion of the plurality of heat exchange structures are spaced from the heat exchange fluid director plate; and
a purge gas channel fluidly communicating with an ambient environment at a location between the ambient environment and a gasket disposed between a showerhead and the gas channel plate.

2. The semiconductor process module of claim 1, further comprising a process feed inlet for supplying a process feed to a showerhead volume formed between a diffusion surface disposed opposite the heat exchange surface and the showerhead sealably coupled to the gas channel plate.

3. The semiconductor process module of claim 2, where the process feed inlet includes a flow expansion structure upstream of the process feed inlet, the flow expansion structure being aligned with a centerline of the process feed inlet.

4. The semiconductor process module of claim 3, where the flow expansion structure includes a concentric conical expansion formed on an inner surface of the flow expansion structure.

5. The semiconductor process module of claim 2, further comprising a pulse valve manifold positioned upstream of the gas channel plate.

6. The semiconductor process module of claim 2, where the diffusion surface has a radially symmetric profile with respect to a centerline of the gas channel plate, the diffusion surface becoming closer to the showerhead as distance from a centerline of the gas channel plate increases.

7. The semiconductor process module of claim 6, where the radially symmetric profile includes a portion of the diffusion surface being disposed at an angle of between 0 and 5 degrees with respect to a reference plane defining a widest portion of the showerhead volume.

8. The semiconductor process module of claim 2, where the diffusion surface has a radially symmetric profile with respect to a centerline of the gas channel plate, where the radially symmetric profile includes a portion of the diffusion surface disposed at an angle of between 0 and 5 degrees with respect to a reference plane defining a widest portion of the showerhead volume, and where an upper surface of the showerhead facing the showerhead volume is spaced from the portion of the diffusion surface so that the portion of the diffusion surface and a respective portion of the upper surface remain a constant distance apart as distance from a centerline of the gas channel plate increases.

9. The semiconductor process module of claim 2, where the gas channel plate is sealably coupled to the showerhead by a gasket positioned within 20 mm of a showerhead distribution hole included in the showerhead.

10. The semiconductor process module of claim 1, further comprising: a heating element disposed in a spiral groove included in the heat exchange surface; a temperature controller electrically connected with the heating element for adjusting a temperature of the heating element in response to a temperature of the heat exchange surface.

11. The semiconductor process module of claim 10, where the showerhead includes a heating element independent from the heating element included in the heat exchange surface.

12. A semiconductor reactor comprising a gas channel plate, wherein the gas channel plate comprises:
a heat exchange surface including a plurality of heat exchange structures separated from one another by intervening gaps;
a heat exchange fluid director plate support surface for supporting a heat exchange fluid director plate above the plurality of heat exchange structures so that at least a portion of the plurality of heat exchange structures are spaced from the heat exchange fluid director plate; and
a purge gas channel fluidly communicating with an ambient environment at a location between the ambient environment and a gasket disposed between a showerhead and the gas channel plate.

13. The semiconductor reactor of claim 12, further comprising a process feed inlet for supplying a process feed to a showerhead volume formed between a diffusion surface disposed opposite the heat exchange surface and the showerhead sealably coupled to the gas channel plate.

14. The semiconductor reactor of claim 13, where the process feed inlet includes a flow expansion structure upstream of the process feed inlet, the flow expansion structure being aligned with a centerline of the process feed inlet.

15. The semiconductor reactor of claim 14, where the flow expansion structure includes a concentric conical expansion formed on an inner surface of the flow expansion structure.

16. A processing tool comprising the semiconductor process module of claim 1.

17. A gas channel plate for a semiconductor process module, the gas channel plate comprising:
a heat exchange surface including a plurality of heat exchange structures separated from one another by intervening gaps;
a heat exchange fluid director plate support surface for supporting a heat exchange fluid director plate above the plurality of heat exchange structures so that at least a portion of the plurality of heat exchange structures are spaced from the heat exchange fluid director plate; and
a purge gas channel fluidly communicating with an ambient environment at a location between the ambient environment and a gasket disposed between a showerhead and the gas channel plate.