Patent Application
20180209043
Embodiments of the present invention generally relate to methods and apparatus for processing a substrate.
In some processes, such as epitaxial deposition of a layer on a substrate, process gases may be laterally flowed across a substrate surface in the same direction. For example, the one or more process gases may be flowed across a substrate surface between an inlet port and an exhaust port disposed on opposing ends of a process chamber to grow an epitaxial layer atop the substrate surface.
In some epitaxial deposition chambers, an additional side flow may be introduced in a direction perpendicular to the main gas flow path to provide additional control over the process. However, the inventors have observed that the tuning capability of the additional side flow is limited and the effective area of the additional side flow on the substrate is often restricted locally near the inject nozzles.
In addition, the inventors have observed that flow expansion at the inject nozzles of the main gas flow path can cause some of the gases to expand upward and move away from the wafer as soon as they enter the chamber. Thus, current processing apparatus and methods may fail to yield deposited films having suitable material quality, such as low defect density, composition control, high purity, morphology, in-wafer uniformity, and/or run to run reproducibility.
Accordingly, the inventors have provided improved methods and apparatus for processing substrates.
Apparatus for processing a substrate in a process chamber are provided here. In some embodiments, a gas injector for use in a process chamber includes a first set of outlet ports that provide an angled injection of a first process gas at an angle to a planar surface, and a second set of outlet ports proximate the first set of outlet ports that provide a pressurized laminar flow of a second process gas substantially along the planar surface, the planar surface extending normal to the second set of outlet ports.
In some embodiments, a process chamber for processing a substrate and having the gas injector disposed therein, may include a substrate support disposed therein to support the substrate at a desired position within the process chamber such that a processing surface of the substrate forms the planar surface; a second gas injector to provide a third process gas over the processing surface of the substrate in a second direction different from the gas flow provided by the gas injector, wherein the second gas injector includes one or more nozzles that adjust at least one of a gas flow speed, a gas flow shape, and a gas flow direction of the third process gas; and an exhaust port disposed opposite the gas injector to exhaust the first, second, and third process gases from the process chamber.
In some embodiments, an apparatus for processing a substrate may include a process chamber having a substrate support disposed therein to support a processing surface of a substrate at a desired position within the process chamber; a first injector to provide a first process gas over the processing surface of the substrate in a first direction; a second injector to provide a second process gas over the processing surface of the substrate in a second direction different from the first direction, wherein the second injector includes one or more that adjust at least one of a gas flow speed, a gas flow shape, and a gas flow direction of the third process gas; and an exhaust port disposed opposite the first injector to exhaust the first and second process gases from the process chamber.
Other and further embodiments of the present invention are described below.
Embodiments of the present invention, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the invention depicted 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.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Methods and apparatus for depositing a layer on a substrate are disclosed herein. The inventors have observed that undesirable thickness and/or compositional non-uniformities in epitaxial layers grown on a substrate surface exist during conventional processes. The inventors have further observed that such non-uniformities in thickness and composition may become even more undesirable at smaller critical dimensions and/or higher degrees of compositional loading (i.e., when growing large varieties of epitaxial layers on a substrate). Embodiments of the inventive methods and apparatus disclosed herein may advantageously overcome thickness and/or compositional non-uniformities in deposited layers by generating a flow interaction between process gases utilized for deposition. In some embodiments, edge and overall substrate surface uniformity may be improved by introducing additional gas side flow in a direction perpendicular to the main gas flow path and varying gas speeds, gas distribution areas, and gas flow directions through the use of adjustable injection nozzles.
In addition, the inventors have observed that by changing the initial velocity, mass flow rate, and/or mass of the main gas flow jet stream, the reaction location on the substrate and the rate of deposition can be tuned. For example, angled injection of a second process gas towards the surface of the substrate, while a first process gas is provided across the surface of the substrate, advantageously increases the downwards momentum of the second species of gas, which improves the mixing between first and second species of process gases. Furthermore, by providing pressurized laminar gas flow of the first process gas across the surface of the substrate through the use of restricted plenums, the concentration gradient across the substrate will be smoothed, which will enhance flow uniformity in the chamber.
The chamber body 110 generally includes an upper portion 102, a lower portion 104, and an enclosure 120. The upper portion 102 is disposed on the lower portion 104 and includes a lid 106, a liner 116, one or more optional upper lamps 136, and an upper pyrometer 156. In one embodiment, the lid 106 has a dome-like form factor, however, lids having other form factors (e.g., flat or reverse curve lids) are also contemplated. The lower portion 104 is coupled to the first inlet port 114, the first injector 180, the second injector 170 and an exhaust port 118 and comprises a baseplate assembly 121, a lower chamber liner 131, a lower dome 132, the substrate support 124, a pre-heat ring support 122, a pre-heat ring 125 supported by pre-heat ring support 122, a substrate lift assembly 160, a substrate support assembly 164, a heating system 151 including one or more lower lamps 152 and 154, and a lower pyrometer 158. Although the term “ring” is used to describe certain components of the process chamber, such as the pre-heat ring support 122 and pre-heat ring 125, it is contemplated that the shape of these components need not be circular and may include any shape, including but not limited to, rectangles, polygons, ovals, and the like.
The first injector 180 is configured to provide a first process gas over a processing surface of the substrate 123 in a first direction 208. As used herein, the term process gas refers to both a singular gas and a mixture of multiple gases. Also as used herein, the term “direction” can be understood to mean the direction in which a process gas exits an injector port. In some embodiments, the first direction 208 is generally pointed towards the opposing exhaust port 118.
The first injector 180 may comprise a single outlet port wherein the first process gas is provided therethrough (not shown), or may comprise one or more sets of outlet ports 214, wherein each set of outlet ports 214 may include one or more outlet ports 210. In some embodiments, each set of outlet ports 214 may include about 1 to 15 outlet ports 210, although greater outlet ports may be provided (e.g., one or more). The first injector 180 may provide the first process gas, which may for example be a mixture of several process gases. Alternatively, a first set of outlet ports 214 in the first injector 180 may provide one or more process gases that are different than at least one other set of outlet ports 214. In some embodiments, the process gases may mix substantially uniformly within a plenum the first injector 180 to form the first process gas. In some embodiments, the process gases may generally not mix together after exiting the first injector 180 such that the first process gas has a purposeful, non-uniform composition. Flow rate, process gas composition, and the like, at each outlet port 210 in the one or more sets of outlet ports 214 may be independently controlled. In some embodiments, some of the outlet ports 210 may be idle or pulsed during processing, for example, to achieve a desired flow interaction with a second process gas provided by the second injector 170, as discussed below. Further, in embodiments where the first injector 180 comprises a single outlet port, the single outlet port may be pulsed for similar reasoning as discussed above.
In some embodiments, as shown in
In some embodiments as shown in
In some embodiments, the first process gas 322 flowed through the first set of outlet ports 302 may be different gas species than a second process gas flowed through the second set of outlet ports 304, 306, 308. In some embodiments, the first process gas may include one or more Group III elements in a first carrier gas. Exemplary first process gases include one or more of trimethylgallium, trimethylindium, or trimethylaluminum. Dopants and hydrogen chloride (HCl) may also be added to the first process gas. In some embodiments, the second process gas may include one or more Group III/V elements in a second carrier gas. Exemplary second process gases include one or more of diborane (B2H6), arsine (AsH3), phosphine (PH3), tertiarybutyl arsine, tertiarybutyl phosphine, or the like. Dopants and hydrogen chloride (HCl) may also be added to the second process gas.
Although different dimensions and geometries of injector 180 features may be used, some exemplary ranges of dimensions and cross-sectional geometries used in accordance with at least some embodiments are described below with respect to
In some embodiments, the second set of outlet ports 304, 306, 308 may have a rectangular cross-section, although in other embodiments different cross-sectional geometries may used. The size and shape of the outlet ports 304, 306, 308 may be defined by lip 320 and a bottom of wall 310 which contacts preheat ring support 122 to form a bottom portion of outlet ports 304, 306, 308. In some embodiments, injector 180 may be coupled to and supported by inlet port 114. In some embodiments, injector 180 may also be supported by preheat ring support 122. In some embodiments, the width 332 of the outlet ports 304, 306, 308 may be about 40 mm to about 80 mm. In some embodiments, the height 340 of the opening of outlet ports 304, 306, 308 may be about 3 mm to about 10 mm. In some embodiments, the height 340 may be based on how far lip 320 extends downward to block the opening of outlet ports 304, 306, 308. In some embodiments, the bottom of outlets ports 304, 306, 308 may be disposed at a height 342 of about 1.5 mm to about 5 mm above substrate 123.
Referring back to
In some embodiments, the second injector 170 may comprise a single adjustable nozzle 402 as shown in
Alternatively, the second inlet port may 170 comprise a plurality of adjustable nozzles 404, 406 as shown in
Returning to
The substrate support 124 further includes a lift mechanism 172 and a rotation mechanism 174 coupled to the substrate support assembly 164. The lift mechanism 172 can be utilized for moving the substrate support 124 along the central axis 200. The rotation mechanism 174 can be utilized for rotating the substrate support 124 about the central axis 200.
During processing, the substrate 123 is disposed on the substrate support 124. The lamps 136, 152, and 154 are sources of infrared (IR) radiation (i.e., heat) and, in operation, generate a pre-determined temperature distribution across the substrate 123. The lid 106 and the lower dome 132 are formed from quartz; however, other IR-transparent and process compatible materials may also be used to form these components.
The support systems 130 include components used to execute and monitor pre-determined processes (e.g., growing epitaxial silicon films) in the process chamber 100. Such components generally include various sub-systems. (e.g., gas panel(s), gas distribution conduits, vacuum and exhaust sub-systems, and the like) and devices (e.g., power supplies, process control instruments, and the like) of the process chamber 100. These components are well known to those skilled in the art and are omitted from the drawings for clarity.
The controller 140 generally comprises a central processing unit (CPU) 142, a memory 144, and support circuits 146 and is coupled to and controls the process chamber 100 and support systems 130, directly (as shown in
The method 500 begins at 502 by providing a substrate, such as the substrate 123. The substrate 123 may comprise a suitable material such as crystalline silicon (e.g., Si<100> or Si<111>), silicon oxide, strained silicon, silicon germanium, doped or undoped polysilicon, doped or undoped silicon wafers, patterned or non-patterned wafers, silicon on insulator (SOI), carbon doped silicon oxides, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire, or the like. Further, the substrate 123 may comprise multiple layers, or include, for example, partially fabricated devices such as transistors, flash memory devices, and the like.
At 504, the first process gas may be flowed across the processing surface of the substrate 123 in a first direction, for example, in a first direction 208. The first process gas may be flowed from the first injector 180, or from one or more of the pressurized laminar outlet ports 304, 306, 308 in the first direction 208 and across the processing surface towards the exhaust port 118. The first process gas may be flowed from the first injector 180 in the first direction 208 parallel to the processing surface of the substrate 123. The first process gas may comprise one or more process gases. For example, the first process gases may include trimethylgallium. In some embodiments, the gases injected using pressurized laminar outlet ports 304, 306, 308 may be, for example, gases that have uniform growth rates (i.e., slow cracking rates).
At 506, the second process gas may be flowed through high flow velocity outlet ports 302 down towards the processing surface of the substrate 123 at a downward angle. As discussed above in accordance with the embodiments of the chamber 100, the downward angle may be about 70 degrees to about 90 degrees from vertical. The second process gas may be the same or different from the first process gas. The second process gas may comprise one or more process gases. For example, the second process gases may include tertiarybutyl arsine. In some embodiments, the gases injected using high flow velocity outlet ports 302 may be, for example, gases that have non-uniform growth rates (i.e., fast cracking rates).
At 508, a layer 600 (shown in
The layer 600 may be deposited by one or more processing methods. For example, the flow rates of the first and second process gases may be varied to tailor the thickness and/or composition of the layer 600. Further, the flow rates may be varied to adjust crystallinity of the layer. For example, a higher flow rate may improve crystallinity of the layer. Other process variants can include rotating about and/or moving the substrate 123 along the central axis 200 while one or both of the first and second process gases are flowing. For example, in some embodiments, the substrate 123 is rotated while one or both of the first and second process gases are flowing. For example, in some embodiments, the substrate 123 is moved along the central axis 200 while one or both of the first and second process gases are flowing to adjust the flow rates of each process gas.
Other variants of depositing the layer are possible. For example, the first and second process gases may be pulsed in one of an alternating or cyclical pattern. In some embodiments, selective epitaxial growth of the layer may be performed by alternately pulsing deposition and etch gases from either or both of the first and second injectors 180, 170. Further, pulsing of the first and second process gases could occur in combination with other processing methods. For example, a first pulse of one or both of the first and second process gases may occur at a first substrate position along the central axis 200, and then a second pulse of one or both of the first and second process gases may occur at a second substrate position along the central axis 200. Further, pulsing can occur with the substrate is rotating about the central axis 200.
Thus, methods and apparatus for depositing a layer on a substrate have been disclosed herein. The inventive methods and apparatus advantageously overcome thickness and/or compositional non-uniformities the deposited layer by generating a flow interaction between process gases utilized for deposition. The inventive methods and apparatus further reduce defect/particle formation in the deposited layer, and allow for the tailoring of thickness and/or composition and/or crystallinity of the deposited layer.
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.
This application is a divisional of co-pending U.S. patent application Ser. No. 14/047,047, filed Oct. 7, 2013, which also claims benefit of U.S. provisional patent application Ser. No. 61/719,009, filed Oct. 26, 2012, which are herein incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 61719009 | Oct 2012 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14047047 | Oct 2013 | US |
| Child | 15928622 | US |
