# Patent

## Title
Variable conductance gas distribution apparatus and method

## Abstract

Variable conductance gas distribution systems, reactors and systems including the variable conductance gas distribution systems, and methods of using the variable conductance gas distribution systems, reactors, and systems are disclosed. The variable conductance gas distribution systems allow rapid manipulation of gas-flow conductance through the gas distribution system.

## Background
FIELD OF DISCLOSURE
The present disclosure generally relates to gas-phase apparatus and methods. More particularly, the disclosure relates to gas distribution apparatus, reactors and systems including the apparatus, and methods of using the apparatus, reactors, and systems.
BACKGROUND OF THE DISCLOSURE
Gas-phase reactors, such as chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), atomic layer deposition (ALD), and the like can be used for a variety of applications, including depositing and etching materials on a substrate surface. For example, gas-phase reactors can be used to deposit and/or etch layers on a substrate to form semiconductor devices, flat panel display devices, photovoltaic devices, microelectromechanical systems (MEMS), and the like.
A typical gas-phase reactor system includes a reactor including a reaction chamber, one or more precursor gas sources fluidly coupled to the reaction chamber, one or more carrier or purge gas sources fluidly coupled to the reaction chamber, a gas distribution system to deliver gases (e.g., the precursor gas(es) and/or carrier or purge gas(es)) to a surface of a substrate, and an exhaust source fluidly coupled to the reaction chamber.
Many gas distribution systems include a showerhead assembly for distributing gas(es) to a surface of the substrate. The showerhead assembly is typically located above the substrate and is designed to provide laminar flow to the substrate surface. The showerhead assembly is generally designed, in connection with a reaction chamber, to provide desired residence times for gas-phase reactants.
During substrate processing, purge gases are often used to facilitate removal of one or more reactants and/or products from a reaction chamber. For example, during a typical ALD process, a first reactant (also referred to herein as a precursor) is introduced to the reaction chamber and allowed to react with a surface of a substrate for a first residence time, and the first reactant is evacuated from the reaction chamber using the exhaust system and a purge gas. A second reactant is then introduced to the reaction chamber to react with a surface of the substrate for a second residence time, which may be the same as or different from the first residence time. The second reactant is then evacuated from the reaction chamber using the exhaust system and a purge gas. These steps can be repeated until a desired amount of material is deposited onto a substrate surface.
During the purge steps, it may be desirable to allow considerably more gas—relative to a reactant—to flow through a reaction chamber. Unfortunately, ALD and other gas-phase reactors and systems are generally designed to restrict gas flow to optimize reactant flow rates and residence times to obtain desired film deposition rates and uniformity. As a result, the time required to sufficiently purge a reactant or other gas from a reaction chamber is undesirably long. Consequently substrate throughput can be undesirably slow and costs associated with processing the substrates can be undesirably high. Therefore, improved gas-phase methods and apparatus that allow rapid purging and desired reactant flow rates are desired.
SUMMARY OF THE DISCLOSURE
Various embodiments of the present disclosure provide variable conductance gas distribution systems and methods. The variable conductance gas distribution systems are suitable for use in a variety of gas-phase processes, such as chemical vapor deposition processes (including plasma-enhanced chemical vapor deposition processes), gas-phase etching processes (including plasma-enhanced gas-phase etching processes), gas-phase cleaning (including plasma-enhanced cleaning processes), and gas-phase treatment processes (including plasma-enhanced gas-phase treatment processes). As set forth in more detail below, exemplary systems and methods are particularly well suited for processes that use multiple reactants (e.g., in multiple sequences), such as atomic layer deposition processes.
In accordance with various embodiments of the disclosure, a variable conductance gas distribution system includes a gas inlet, a first member in fluid communication with the gas inlet, and a second member in fluid communication with the gas inlet. The first member and the second member include one or more features that interact with or engage with each other to control an amount of gas flowing through the variable conductance gas distribution system. In accordance with various aspects of these embodiments, the variable conductance gas distribution system further includes a mechanism to move at least one of the first member and the second member relative to the other member to manipulate an amount of gas flow. For example, the first member and the second member can be spaced apart to provide greater fluid conductance (e.g., for purging a reaction chamber of a reactor), and can be moved closer together or be engaged to provide lesser fluid conductance (e.g., for providing a reactant to the reaction chamber). One or more gases can flow from a gas inlet, between one or more features on the first member and one or more features on the second member, to a reaction chamber.
In accordance with further exemplary embodiments of the disclosure, a reactor includes a gas distribution system as described herein.
In accordance with yet additional exemplary embodiments of the disclosure, a reactor system includes a gas distribution system as described herein.
And, in accordance with yet additional exemplary embodiments of the disclosure, a gas-phase method includes using a variable conductance gas distribution system. Exemplary methods include the steps of using a variable conductance gas distribution system, introducing a first gas (e.g., a reactant gas) to a reaction chamber of a reactor, moving a first member of the variable conductance gas distribution system relative to a second member of the variable conductance gas distribution system to increase fluid conductance of the variable conductance gas distribution system, and using the variable conductance gas distribution system, introducing a second gas (e.g., a purge gas) to a reaction chamber of a reactor. A mechanism, such as a servo motor, pneumatic actuator, electric solenoid, or piezoelectric actuator, can be used to move the first member relative to the second member and thereby manipulate an amount of gas flow.
Both the foregoing summary and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure or the claimed invention.



BRIEF DESCRIPTION OF THE DRAWING FIGURES
A more complete understanding of exemplary embodiments of the present disclosure can be derived by referring to the detailed description and claims when considered in connection with the following illustrative figures.
FIG. 1 illustrates a gas-phase reactor system, with a variable conductance gas distribution system in an open position, in accordance with exemplary embodiments of the disclosure.
FIG. 2 illustrates a gas-phase reactor system, with a variable conductance gas distribution system in a closed position, in accordance with exemplary embodiments of the disclosure.
FIG. 3 illustrates a top plan view of a portion of a variable conductance gas distribution system in accordance with exemplary embodiments of the disclosure.
FIG. 4 illustrates a bottom plan view of a portion of a variable conductance gas distribution system in accordance with further exemplary embodiments of the disclosure.
FIG. 5 illustrates a variable conductance gas distribution system in a closed position in accordance with additional exemplary embodiments of the disclosure.
FIG. 6 illustrates features of a variable conductance gas distribution system in an open position in accordance with yet additional exemplary embodiments of the disclosure.
FIG. 7 illustrates a variable conductance gas distribution system in a further open position in accordance with yet additional exemplary embodiments of the disclosure.
FIG. 8 illustrates a method in accordance with yet further exemplary embodiments of the disclosure.



It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve the understanding of illustrated embodiments of the present disclosure.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE DISCLOSURE
The description of exemplary embodiments provided below is merely exemplary and is intended for purposes of illustration only; the following description is not intended to limit the scope of the disclosure or the claims. Moreover, recitation of multiple embodiments having stated features is not intended to exclude other embodiments having additional features or other embodiments incorporating different combinations of the stated features.
A set forth in more detail below, various embodiments of the disclosure relate to variable conductance gas distribution systems, reactors and reactor systems that include a variable conductance gas distribution system, and to methods of using the variable conductance gas distribution systems, and reactors. The variable conductance gas distribution systems, reactors, and methods can be used for a variety of gas-phase processes, such as deposition, etch, clean, and/or treatment processes.
FIG. 1 illustrates a gas-phase reactor system 100 in accordance with exemplary embodiments of the disclosure. System 100 includes a reactor 102, including a reaction chamber 104, a substrate holder 106, and a variable conductance gas distribution system 108, a vacuum source 110, a first reactant gas source 112, a second reactant gas source 114, a purge gas source 116, one or more flow control units 118-122, a gas inlet 124, and optionally a remote plasma unit 128. Although not illustrated, system 100 may additionally include direct and/or additional remote plasma and/or thermal excitation apparatus for one or more reactants and/or within reaction chamber 104.
Reactor 102 may be used to deposit material onto a surface of a substrate 126, etch material from a surface of substrate 126, clean a surface of substrate 126, treat a surface of substrate 126, deposit material onto a surface within reaction chamber 126, clean a surface within reaction chamber 104, etch a surface within reaction chamber 104, and/or treat a surface within reaction chamber 104. Reactor 102 can be a standalone reactor or part of a cluster tool. Further, reactor 102 can be dedicated to deposition, etch, clean, or treatment processes, or reactor 102 may be used for multiple processes—e.g., for any combination of deposition, etch, clean, and treatment processes. By way of examples, reactor 102 may include a reactor typically used for chemical vapor deposition (CVD) processes, such as atomic layer deposition (ALD) processes.
Substrate holder 106 is designed to hold substrate or workpiece 126 in place during processing. In accordance with some exemplary embodiments, reactor 102 includes a direct plasma apparatus; in this case substrate holder 106 can form part of a direct plasma circuit. Additionally or alternatively, substrate holder 106 can be heated, cooled, or be at ambient process temperature during processing. By way of example, substrate holder 106 can be heated during substrate 146 processing, such that reactor 102 is operated in a cold-wall, hot-substrate configuration.
Although gas inlet 124 is illustrated in block form, gas inlet 124 may be relatively complex and be designed to mix gas (e.g., vapor) from reactant sources 112, 114 and/or carrier/purge gases from one or more sources 116 prior to distributing the gas mixture to reaction chamber 104. Further, gas inlet 124 can be configured to provide vertical (as illustrated) or horizontal flow of gases to chamber 104. An exemplary gas distribution system is described in U.S. Pat. No. 8,152,922 to Schmidt et al., issued Apr. 10, 2012, entitled “Gas Mixer and Manifold Assembly for ALD Reactor,” the contents of which are hereby incorporated herein by reference, to the extent the contents do not conflict with the present disclosure. Gas inlet can optionally include an integrated manifold block designed to receive and distribute one or more gases to reaction chamber 104. An exemplary integrated inlet manifold block is disclosed in U.S. Pat. No. 7,918,938 to Provencher et al., issued Apr. 5, 2011, entitled “High Temperature ALD Inlet Manifold,” the contents of which are hereby incorporated herein by reference, to the extent the contents do not conflict with the present disclosure.
Remote plasma unit 128 can be an inductively coupled plasma unit or a microwave remote plasma unit. In the illustrated example remote plasma unit 128 can be used to create reactive or excited species for use in reaction chamber 104. Although system 100 is illustrated with remote plasma unit 128, systems in accordance with other exemplary embodiments of the disclosure do not include a remote plasma unit. In addition to or as an alternative to using remote plasma unit 128 to form excited species, system 100 can include another excitation source, such as a thermal or hot filament source, a microwave source, or the like.
Vacuum source 110 can include any suitable vacuum source capable of providing a desired pressure in reaction chamber 104. Vacuum source 110 may include, for example, a dry vacuum pump alone or in combination with a turbo molecular pump.
Reactant gas sources or precursors 112 and 114 can each include one or more gases, or materials that become gaseous, that are used in deposition, etch, clean, or treatment processes. Exemplary gas sources include noble gases liquid vapors and vaporized solid sources. Although illustrated with two reactant gas sources 112, 114, systems in accordance with the disclosure can include any suitable number of reactant sources.
Purge gas source 116 includes one or more gases, or materials that become gaseous, that are relatively unreactive in reactor 102. Exemplary purge gases include nitrogen, argon, helium, and any combinations thereof. Although illustrated with one purge gas source, systems in accordance with the present disclosure can include any suitable number of purge gas sources. Further one or more purge gas sources can provide one or more carrier gases and/or system 100 can include additional carrier gas sources to provide a carrier gas to be mixed with one or more gases from a reactant source, such as sources 112, 114.
Flow controllers 118-122 can include any suitable device for controlling gas flow. For example, flow controllers 118-122 can be mass flow controllers. In addition, system 100 can include valves 130-134 to further control or shut off a gas source.
Variable conductance gas distribution system 108 is configured to manipulate a gas flow rate of a gas flowing between gas inlet 124 toward substrate 126 and vacuum source 110. In the illustrated example, variable conductance gas distribution system 108 includes a first member 136 and a second member 138. First member 136 includes one or more features 140-142 and a coupling element 158. Second member 138 includes one or more second features 148-158 and a coupling element 160. A mechanism 162 can cause first member 136 and second member 138 to move relative each other to increase or decrease a conductance of gas flowing between features 140-142 and features 148-152. By way of examples, mechanism 162 can cause first member 136 and second member 130 to move from a closed or “0” position to a distance of about 10 mm, or from about 0 to about 6 mm.
A material used to form first member 136, second member 138, and components thereof can vary according to application. By way of examples, first member 136 and second member 138 are formed of nickel, nickel-plated aluminum, a high-nickel stainless steel material, such as Hastalloy alloy (e.g., c22), or the like.
FIG. 1 illustrates variable conductance gas distribution system 108 in an “open,” relatively high conductance position. In this case, a gas, such as a purge gas, can flow with relatively low restriction between gas inlet 124 and vacuum source 110. FIG. 2 illustrates variable conductance gas distribution system 108 in a “closed,” relatively restrictive/low conductance position, which can be used when one or more reactant gases, such as one or more gases from source 112 and/or 114 are introduced to reaction chamber 104.
FIG. 3 illustrates a top view of variable conductance gas distribution system 108 in a closed position. In the illustrated example, coupling element 158 of first member 136 retains features 140-142 and can be used to simultaneously move features 140-142 or to retain features 140-142 in a stationary position. Similarly, with reference to FIG. 4, which illustrates a bottom view of variable conductance gas distribution system 108, coupling element 160 of second member 138 retains features 148-152, and can be used to simultaneously move features 148-152 or retain features 148-152 in a stationary position. Coupling element 136 and/or coupling element 138 can optionally include structures 144, 146 to couple features to a respective coupling element. Variable conductance gas distribution system 108 can include apertures 302 to allow gas to flow through variable conductance gas distribution system 108, even when variable conductance gas distribution system 108 is in a closed position. However, other exemplary variable conductance gas distribution systems in accordance with this disclosure do not include the apertures. In this case, features of first member 136 and features of second member 138 may form a seal.
With reference again to FIGS. 1 and 2, operation of variable conductance gas distribution system 108 is illustrated as moving first member 136 using mechanism 162, while retaining second member 138 in a stationary position. However, other variable conductance gas distribution system 108 in accordance with the disclosure can move both first member 136 and second member 138, or move only second member 138 to manipulate a conductance of variable conductance gas distribution system 108. Further, although features 140-142 and features 148-152 are illustrated as respectively moving (or remaining stationary) in unison, other embodiments of variable conductance gas distribution system 108 include individually moving one or more features or one or more members individually or together.
Features 140-142, 148-152 are illustrated as tapered, generally having frustum shaped (e.g., frusto-triangular shape in cross section). However, the features 140-152 can have any suitable shape. However, to facilitate control of gas conductance, features 140-152 can desirably include a slanted surface. For example, an angle θ of a sidewall between a base of a feature and the top of the feature can range from about 10 to about 80 degrees or about 30 to about 60 degrees.
Variable conductance gas distribution system 108 can include any suitable number of features. By way of examples, first member 136 can include 1-10 or more features, and second member 138 can include 1-10 or more features, with the features associated (e.g., attached to) first member 136 generally alternating with the features of second member 138. Further, although features 140-142, 148-152 are illustrated as concentric circles or hollow circles in cross-section as viewed from the top or bottom of variable conductance gas distribution system 108 (see FIGS. 3 and 4), the features can include other suitable cross sections, such as square and rectangular.
FIGS. 5-7 illustrate another variable conductance gas distribution system 500, including first features 502-506 and second features 508-510 coupled to a coupling element 512. Variable conductance gas distribution system 500 is similar to variable conductance gas distribution system 108, except variable conductance gas distribution system 108 includes three first features 502-506 (compared to two features 140-142 of variable conductance gas distribution system 108) and two second features 508-510 (compared to three features 148-152 of variable conductance gas distribution system 108).
FIG. 5 illustrated variable conductance gas distribution system 500 in a closed position. In this position, variable conductance gas distribution system 500, similar to variable conductance gas distribution system 108, can allow no (if variable conductance gas distribution system 500 does not include apertures) or relatively low gas flow. As illustrated in FIG. 6, a first member 601 and a second member 604 can be moved apart (e.g., about 0 mm to about 0.3 mm or about 0.3 mm to about 20 mm) to allow gas to flow between first features 502-506 and second features 508-510 (e.g., for introduction of one or more reactants to a reaction chamber). As illustrated in FIG. 7, first member 602 and second member 604 can be moved further apart to increase a conductance of variable conductance gas distribution system 500 (e.g., for a purge process).
Turning now to FIG. 8, a gas-phase method 800 is illustrated. Method 800 includes the steps of using a variable conductance gas distribution system, introducing a reactant gas to a reaction chamber of a reactor (step 802), moving a first member of the variable conductance gas distribution system relative to a second member of the variable conductance gas distribution system to increase fluid conductance of the variable conductance gas distribution system (step 804), and using the variable conductance gas distribution system, introducing a purge gas to a reaction chamber of a reactor (step 806). Method 800 can also include a step of moving the first member relative to the second member to decrease conductance of a variable conductance gas distribution system (step 808). Steps 802-806 or 802-808 can be repeated a desired number of times—for example, until a desired amount of material is deposited, removed, cleaned, or treated. Further, although illustrated with initially introducing a reactant gas, method 800 can suitably begin with moving the first and/or second members to a desired position and/or by introducing a purge gas to a reaction chamber.
Although exemplary embodiments of the present disclosure are set forth herein, it should be appreciated that the disclosure is not so limited. For example, although the methods and reactor systems are described in connection with various specific configurations, the disclosure is not necessarily limited to these examples. Various modifications, variations, and enhancements of the exemplary systems and methods set forth herein may be made without departing from the spirit and scope of the present disclosure.
The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various systems, components, and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.

## Claims

1. A gas-phase reactor configured for forming semiconductor devices comprising;
a reaction chamber;
a substrate holder disposed within the reaction chamber and configured to hold a semiconductor substrate;
a vacuum source fluidly coupled to the reaction chamber; and
a variable conductance gas distribution system disposed over the substrate holder, the variable conductance gas distribution system comprising:
a gas inlet;
a first member having one or more first features;
a second member having one or more second features; and
a mechanism to move at least one of the first member and the second member relative to the other member to manipulate an amount of gas flow over the semiconductor substrate,

wherein, when the gas distribution system is open, gas flows between the one or more first features and the one or more second features,
wherein when the gas distribution system is closed, a seal forms between the one or more first features and the one or more second features, and
wherein the first member and the second member are spaced apart a first distance for a first process to flow a purge gas through the variable conductance gas distribution system at a first conductance and spaced apart a second distance for a second process to flow one or more reactants through the variable conductance gas distribution system at a second conductance, the first conductance different from the second conductance.

2. The gas-phase reactor of claim 1, wherein the one or more first features are tapered.

3. The gas-phase reactor of claim 1, wherein the one or more first features are frustum shaped.

4. The gas-phase reactor of claim 1, wherein the one or more second features are tapered.

5. The gas-phase reactor of claim 1, wherein the one or more second features are frustum shaped.

6. The gas-phase reactor of claim 1, wherein at least one of the one or more first features and at least one of the one or more second features are concentric with respect to each other.

7. The gas-phase reactor of claim 1, further comprising a reactant gas source coupled to the gas inlet.

8. The gas-phase reactor of claim 1, further comprising a purge gas source coupled to the gas inlet.

9. The gas-phase reactor of claim 1, wherein the mechanism moves the first member and the second member together prior to the gas inlet receiving a reactant gas.

10. The gas-phase reactor of claim 1, wherein the mechanism moves the first member and the second member apart prior to the gas inlet receiving a purge gas.

11. The gas-phase reactor of claim 1, wherein one or more of the first features and the one or more second features comprise apertures to allow gas to flow there through when a seal is formed between the one or more first features and the one or more second features.

12. The gas-phase reactor of claim 1, wherein the mechanism causes the first member to move a distance of between about 0 and about 10 mm.

13. The gas-phase reactor of claim 1, further comprising a coupling element coupled to the one or more first features.

14. The gas-phase reactor of claim 1, further comprising a coupling element coupled to the one or more second features.

15. The gas-phase reactor of claim 1, wherein the first member comprises a plurality of first features concentrically arranged with respect to each other.

16. The gas-phase reactor of claim 1, wherein the second member comprises a plurality of second features concentrically arranged with respect to each other.

17. A gas-phase method, the method comprising the steps of:
using a variable conductance gas distribution system, introducing a reactant gas to a reaction chamber of a reactor;
moving a first member of the variable conductance gas distribution system relative to a second member of the variable conductance gas distribution system to increase fluid conductance of the variable conductance gas distribution system; and
using the variable conductance gas distribution system, introducing a purge gas to the reaction chamber of the reactor,
wherein the first member includes one or more first features and the second member includes one or more second features,
wherein the one or more first features and the one or more second features interact with each other to control an amount of gas flowing through the variable conductance gas distribution system,
wherein when the gas distribution system is closed, a seal forms between the one or more first features and the one or more second features, and
wherein at least one of the one or more first features and the one or more second features comprises an aperture.

18. The gas-phase method of claim 17, further comprising a step of moving the first member of the variable conductance gas distribution system relative to a second member of the variable conductance gas distribution system to decrease fluid conductance of the variable conductance gas distribution system.

19. The gas-phase method of claim 17, wherein the first member comprises a plurality of features that are concentric with respect to each other.