Patent Application
20080099147
1. Field of the Invention
The invention relates to an apparatus for processing substrates, such as semiconductor wafers, and more particularly, to an apparatus for distribution of process fluids over a substrate.
2. Description of the Related Art
Semiconductor processing systems generally include a process chamber having a pedestal for supporting a substrate, such as a semiconductor wafer, within the chamber proximate a processing region. The chamber forms a vacuum enclosure defining, in part, the processing region. A gas distribution assembly or showerhead provides one or more process gases to the processing region. The gases are then heated and/or energized to form a plasma which performs certain processes upon the substrate. These processes may include deposition processes, such as chemical vapor deposition (CVD), to deposit a film upon the substrate or an etch reaction to remove material from the substrate, among other processes.
In processes that require multiple gases, the gases may be combined within a mixing chamber that is then coupled to the gas distribution assembly via a conduit. For example, in a conventional thermal CVD process, two process gases are supplied to a mixing chamber along with two respective carrier gases where they are combined to form a gaseous mixture. The gaseous mixture may be introduced directly to the chamber, or may travel through a conduit within an upper portion of the chamber to the distribution assembly. The distribution assembly generally includes a plate having a plurality of holes such that the gaseous mixture is evenly distributed into the processing region above the substrate. In another example, two gases pass through the distribution assembly separately, and allowed to combine before reaching the processing region and/or the substrate. As the gaseous mixture enters the processing region and is infused with thermal energy, a chemical reaction occurs between the process gases, resulting in a chemical vapor deposition reaction on the substrate.
Although it is generally advantageous to mix the gases prior to release into the processing region, for example, to ensure that the component gases are uniformly distributed into the processing region, the gases tend to begin reduction, or otherwise react, within the mixing chamber or distribution plate. Consequently, deposition on or etching of the mixing chamber, conduits, distribution plate, and other chamber components may result prior to the gaseous mixture reaching the processing region. Additionally, reaction by products may accumulate in the chamber gas delivery components or on the inside surface of the distribution plate, thus generating, and/or increasing the presence of, unwanted particles.
Temperature control of the gases as they are released into the processing region is advantageous for controlling the reactivity of the gases. For example, cooling the gases can be helpful in controlling unwanted reactions prior to release into the processing region. The gases refrain from reacting until they come into contact with a heated substrate. In other circumstances, heating of gases may be necessary. For example, hot gas purging or cleaning may help remove contaminants from a processing chamber. Thus, integrating a temperature control aspect into a gas distribution plate is useful.
While some gas distribution devices have been developed to minimize gas mixing prior to entry into the processing region, the devices may tend to prematurely deteriorate during processing. For example, conventional distribution devices may be made of materials that expand and contract during processing, leading to deterioration of the device or other parts of the processing chamber. The conventional devices may also require sealing with large elastomeric seals, such as large diameter o-rings that may deteriorate over time, which may lead to leaks within the device. Further, conventional devices that deliver two or more gases to the processing region may not mix uniformly in the processing region, thus leading to non-uniform deposition on the substrate.
Therefore, there is a continuing need for a gas distribution device that delivers at least two gases into a processing region without commingling of the gases prior to reaching the processing region while controlling the temperature of the gases. In addition, there is a need for a gas distribution device that seals without the use of large o-rings.
Embodiments described herein relate to an apparatus and method for delivering process fluids to a processing chamber for deposition of a film on a substrate, etching a substrate, and other processes.
In one embodiment, an apparatus for delivering a process fluid to a processing chamber is described. The apparatus includes a first manifold having a plurality of isolated fluid channels at least partially formed therein, and a second manifold coupled to the first manifold, wherein a portion of the plurality of isolated fluid channels include a first and second gas channel in communication with the second manifold.
In another embodiment, a lid assembly for a processing chamber is described. The lid assembly comprises an upper manifold having fluidly isolated first and second flow paths defined therethrough, and a lower manifold with a top side coupled to the upper manifold, and a bottom side having a first plurality of outlets fluidly coupled to the first flow path and a second plurality of outlets fluidly coupled to the second flow path, respectively, wherein the lower manifold comprises a plurality of concentric rings having an inner surface in sealing contact with an outer surface of an adjoining ring adapted to form a material to material seal therebetween.
In another embodiment, an apparatus for delivering a process fluid to a processing chamber is described. The apparatus includes a manifold assembly with a top side and a bottom side, the top side having a plurality of fluidly isolated circular channels partially formed thereon, and the bottom side having annular outlets formed therein; and a lid plate having a top, a bottom, and an edge, wherein the bottom of the lid plate is coupled to the top side of the manifold assembly, and the lid plate has at least two gas passages and a plurality of thermal control fluid passages formed therethrough in fluid communication with the plurality of circular channels.
In another embodiment, a lid assembly for a processing chamber is described. The lid assembly includes an upper manifold having a plurality of fluidly isolated channels partially formed therein, and a lower manifold coupled to the upper manifold, wherein a first portion of the plurality of fluidly isolated channels comprise first and second gas channels in fluid communication with the lower manifold, and a second portion of the plurality of fluidly isolated channels comprise a plurality of thermal control channels.
In another embodiment, an apparatus for delivering a process fluid to a processing chamber is described. The apparatus includes a manifold assembly with a top side and a bottom side, the top side having a plurality of fluidly isolated circular channels partially formed thereon, and the bottom side having annular outlets formed therein, and a lid plate having a top, a bottom, and an edge, wherein the bottom of the lid plate is coupled to the top side of the manifold assembly, and the lid plate has at least two gas passages and a plurality of thermal control fluid passages formed therethrough in fluid communication with the plurality of circular channels.
In another embodiment, a method for making a gas distribution plate is described. The method includes providing a lid plate having a plurality of radial gas passages formed therein, providing a first manifold having a plurality of circular channels formed therein, wherein a portion of the plurality of circular channels define first and second gas channels, providing a second manifold having a plurality of annular grooves formed therein, wherein a the first and second gas channels are in fluid communication with the plurality of annular grooves, and coupling the first and second manifolds to form a gas distribution plate.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. Nonetheless, the teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is also contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.
In one embodiment, a lower surface of the lid assembly 105 and the upper surface of the substrate 104 define a processing region 106. Lower manifold 114 of lid assembly 105 is in fluid communication with processing region 106. In a specific embodiment, the processing chamber 100 includes an annular member, such as a shadow ring 109, which circumscribes a portion of the substrate support 102 adjacent the substrate 104. The shadow ring 109 is adapted to contact the substrate support 102 as the substrate support is raised to a processing position. When the substrate support 102 is raised, a peripheral portion of the shadow ring 109 substantially isolates the lower portion of the substrate support 102 from the processing region 106. This isolation prevents or minimizes the introduction of process gases in portions of the interior volume 101. The reduction in the volume of the interior volume 101, as defined by the processing region 106, reduces the volume of process gases provided to the processing chamber 100.
In one embodiment, the volume of processing region 106 is defined by the distance between the top surface of substrate 104 and the lowest surface of lid 105. Substrate support 102 may be raised and lowered before and after processing to allow entry and exit of substrates. Vacuum is maintained in, and any undeposited gases are evacuated from, process chamber 101 through annular vacuum channel 124 and vacuum portal 111, which is coupled to a vacuum pump (not shown).
Substrate support 102 may be formed of conducting or non-conducting materials, such as a metal (e.g. aluminum, steel, stainless steel, nickel, chromium, an alloy thereof or combinations thereof or ceramic material. Depending on the specific embodiment, substrate 104 may be heated to a desired temperature prior to and/or during a pretreatment step, a deposition step, post-treatment step or other process step used during the fabrication process.
In one example, substrate support 102 may be heated using an embedded heating element (not shown) such as a resistance heater or a conduit formed within substrate support 102 to supply a heating fluid. In another example, substrate support 102 may be heated using radiant heaters such as, for example, lamps (not shown).
Temperature sensors, such as one or more thermocouples (not shown), may also be embedded in substrate support 102 to monitor the temperature of substrate support 102. The measured temperature may be used in a feedback loop to control a power supply for the heating element, such that the temperature of substrate 104 may be maintained or controlled at a desired temperature which is suitable for the particular process application. Substrate lift pins (not shown) may also be disposed in substrate support 102 and are used to raise and lower substrate 104 from the support surface to facilitate transfer of the substrate into and out of the processing chamber 100.
In one embodiment, fluids, such as gases, are introduced to the processing chamber-100 though control valves, such as valve 107A, coupled to inlet 116 of lid assembly 105. Valve 107A is adapted to couple with a process fluid source F1. Valve 107A may be any control valve for controlling fluid or gas flow, such as a pneumatically, magnetically, or electrically-actuated valve. Control valves may be biased open or closed, and actuated open or closed in short intervals to provide pulses of gases or continuous streams. Suitable valves are available from Fujikin, Inc., of Osaka, Japan, and Veriflo Corp., of Richmond, Calif.
Atomic layer deposition (ALD) processes utilize control valves, such as the valve 107A, to generate pulses of gas to the processing region 106. For example, valve 107A may be configured to provide an opened/closed cycle within a range from 10 milliseconds to 5 seconds. In one example, the valve may be quickly pulsed for less than about 1 second, such as within a range from about 10 milliseconds to about 1 second, for example, from about 50 milliseconds to 700 milliseconds, or from about 100 milliseconds to about 500 milliseconds. In another example, the valve may be pulsed slower, such as for more than about 1 second, such as within a range from about 1 second to about 5 seconds, for example, from about 1.5 seconds to 4 seconds, or from about 2 seconds to about 3 seconds.
The embodiments shown in
Referring to
The lid plate 112 may be formed from materials such as aluminum, stainless steel, nickel, alloys or combinations thereof, or a ceramic material. In one embodiment, when passages 117 and 202 are drilled, the open end of the passages 117, 202 are sealed by plugs 118 and 203. Plugs 118, 203 may be formed from a metal, such as those listed above, ceramic, or organic or inorganic polymer material. Plugs 118, 203 are typically made of a material having a similar coefficient of expansion as the material of lid plate 112. Other methods of forming inlets and manifolds in lid plate 112, such as casting, welding, or brazing, may not require plugs to prevent gas escaping.
In one embodiment, lid plate 112 includes two gas inputs 116 and 200 fluidly coupled to valves 107A, 107B, through which two fluids, which may be in gas or vapor phase, are introduced to chamber 100. The inputs 116 and 200 are connected to passages 117 and 202, respectively, which are in fluid communication with processing region 106. Thus, gas from source F1 passes through valve 107A coupled with input 116 into passage 117. Gas from source F1 then passes from passage 117 into openings 220A and flows into channels 119 formed in the upper manifold 113. Gas from source F2 passes through valve 107B coupled with input 200 into passage 202. Gas from source F2 then passes from passage 202 into opening 220B and flows into channels 204 formed in the upper manifold 113, and as gas from sources F1 and F2 reach upper manifold 113, the gases remain separated in two distinct flow paths.
In one embodiment, upper gas channels 119 and 204 are arranged in a pattern of circular channels in upper manifold 113. The circular channels 119, 204 are coupled to the lower manifold through holes 205A and 205B, as will be explained in detail below.
Each of the upper gas channels 119, 204 and fluid channels 301, 302 define conduits having one side adapted to be sealed by a lower surface of the lid plate 112 when coupled thereto. Upper gas channels 119, 204 and fluid channels 301, 302 may have a cross-sectional shape including U-shaped having rounded corners, a U-shape having substantially square corners, or a combination thereof. In a center portion of the upper gas manifold 113, each of the upper gas channels 119, 204 are separated by fluid channels 301. Annular walls between upper gas channels 119, 204 and fluid channels 301 provide separate flow paths for respective gases and fluids. The upper gas channels 119, 204 and fluid channels 301, 302 are separated and sealed when the lid plate 112 is coupled to the upper manifold 113 to prevent contamination between the thermal control fluid and the gases.
The configuration of fluid channels 301, 302, and gas channels 119, 204 are not limited to the number and configuration as shown. Greater or fewer fluid channels 301, 302, and gas channels 119, 204 may be used, and the shape of the fluid channels 301, 302, and gas channels 119, 204 may be formed in the upper manifold 113 in any shape desired. For example, more inner channels 301 and fewer outer channels 302 may be used, or vice versa. Other embodiments may have channels with different cross-sectional shapes, such as complete circles. Still other embodiments may include more vertical configurations, such as layers of channels formed within one of the lid plate 112 and/or upper manifold 113.
Apertures 123 and 207 in rings 121 and 206 are in fluid communication with channels 119 and 204 of upper manifold 113 via openings 205A, 205B, respectively. Thus, gas from inputs 116 and 200 of lid plate 112 flows through upper manifold 113 into lower manifold 114. Gases from sources F1 and F2 flow through inputs 116 and 200, respectively, of lid plate 112. Thermal cooling fluids flow through portals 401 and 402 of lid plate 112. The arrangement of openings and passages in the various components may be varied in numerous ways to create different embodiments. For example, more openings may be provided in any geometrically optimum pattern. Likewise, openings may be aligned, as shown in the figures, or they may be staggered. Openings may also be sized to optimize flow and pressure distributions throughout the apparatus.
Rings 121 and 206 may be formed from hard materials that withstand temperatures in excess of 1000 degrees C. with a low coefficient of thermal expansion. The materials may be hard materials, such as silicon carbide, silicon graphite, sapphire, quartz, a ceramic material or other hard materials.
By extension of the embodiment described in
The rings 121, 206 are adapted to fit together to form lower manifold 114 wherein the extended top portion 408 of one ring abuts the shoulder area 410 of another ring. In one embodiment, the first outer radius 403 of one ring, measured from the centerline 411, is slightly less than the first inner radius 405 of another ring, wherein the diameters of the constituent rings enable a press-fit. The difference between the first inner diameter and the second inner diameter, and the surface finish of the rings, enable a material to material seal to produce a substantial gas-tight seal between adjacent rings.
As the rings 121, 206 are sequentially fitted together, the difference between the second outer radius 407 of one ring and second inner radius 406 of an adjacent ring form annular groove 501 (
In one embodiment, annular grooves 501 terminate in an annular nozzle 502. In some embodiments, geometry of annular nozzles 502 may be designed to create a specific spread pattern of gas within processing volume 106. This spread pattern, substantially triangular or trapezoidal in cross-sectional shape, creates a separation zone 503 and a mixing zone 504, wherein the distinct gases G1 and G2 from sources F1 and F2 are not mixed until reaching the mixing zone 504. This enables enhanced control of reactive species within processing volume 106, which may eliminate or minimize any unwanted deposition on surfaces other than substrate 104. The sidewalls of the nozzles 502 may be angled from about 15 degrees to about 90 degrees, such as about 50 degrees to about 70 degrees, for example, about 60 degrees. In one embodiment, the surface of the nozzles 502 may be modified to change the flow attributes and/or the geometry of the spread pattern and enhance flow characteristics. In one aspect, the surface may be roughened to facilitate a more laminar flow. In another aspect, the surface may be smoothed or not roughened to provide a faster, more turbulent flow of gasses. For example, the nozzles 502 may include a surface that has been bead, ice, or grit blasted.
In operation, gas from source F1 passes through valve 107A coupled with input 116 into passage 117. Gas from source F1 then passes from passage 117 into opening 220A for introduction into the upper manifold 113. Gas from source F2 passes through valve 107B coupled with input 200 into passage 202. Gas from source F2 then passes from passage 202 into opening 220B for introduction into the upper manifold 113 and as gas from sources F1 and F2 reach upper manifold 113, the gases remain isolated in two separate flow paths. Gas from sources F1 and F2 enters the upper manifold 113 through upper gas channels 119 and 204, respectively. Holes 205A, 205B, which are in fluid communication with lower manifold 114, allow gas from sources F1 and F2 to be flowed to apertures 123, 207, respectively, formed in the lower manifold 114 (207 not shown in this view). Apertures 123 and 207 (not shown) are in fluid communication with annular gaps 122 and 208, respectively, which are in communication with annular grooves 501. Gas from sources F1 and F2 flow through the annular grooves 501 and are delivered to the processing region 106 by the annular nozzles 502. In this manner, gas from sources F1 and F2 are not mixed until reaching the mixing zone 504.
The embodiments described herein enable the delivery of two distinct gases to a processing region without mixing until directly above the face of a substrate. The thermal control aspects provided herein also enable temperature control of the various gases provided to the processing region. This provides enhanced control of processes within the chamber, such as deposition, etch processes, and the like. For example, gas mixing may be controlled such that reactions in the processing region may be enhanced. Unwanted deposition on chamber components and particle generation may be minimized. This increases throughput by the reduction of particles and minimizing downtime for chamber cleaning.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
