Patent Description:
The field relates generally to apparatus and methods for wafer processing, and more particularly to apparatus and methods for semiconductor wafer chemical vapor deposition processes.

Epitaxial chemical vapor deposition (CVD) is a process for growing a thin layer of material on a semiconductor wafer so that the lattice structure is identical to that of the wafer. Epitaxial CVD is widely used in semiconductor wafer production to build up epitaxial layers such that devices can be fabricated directly on the epitaxial layer. The epitaxial deposition process begins by introducing a cleaning gas, such as hydrogen or a hydrogen and hydrogen chloride mixture, to a front surface of the wafer (i.e., a surface facing away from the susceptor) to pre-heat and clean the front surface of the wafer. The cleaning gas removes native oxide from the front surface, permitting the epitaxial silicon layer to grow continuously and evenly on the surface during a subsequent step of the deposition process. The epitaxial deposition process continues by introducing a vaporous silicon source gas, such as silane or a chlorinated silane, to the front surface of the wafer to deposit and grow an epitaxial layer of silicon on the front surface. A back surface opposite the front surface of the susceptor may be simultaneously subjected to hydrogen gas. The susceptor, which supports the semiconductor wafer in the deposition chamber during the epitaxial deposition, is rotated during the process to allow the epitaxial layer to grow evenly.

However, epitaxial CVD growth rates are generally not uniform across the surface of each wafer because of non-uniform flow rates within the reactor. A lack of uniformity causes degradation in the flatness of the wafer and may be a result of variability or local flowrate deviations within the deposition chamber during the epitaxial deposition. Accordingly, there exists a need for a practical, cost-effective apparatus to improve local flowrate deviations to improve uniformity of epitaxial CVD growth rates.

<CIT> discloses a CVD apparatus for epitaxial layer growth with a preheat ring for process gas preheating. The process gas horizontally flows over the wafer and at the side of the process gas inlet, the surface of the preheat ring is profiled and includes fins or protrusions.

This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below.

In one aspect, a reaction apparatus for contacting a process gas with a semiconductor wafer is provided. The reaction apparatus includes an upper dome, a lower dome, an upper liner, a lower liner, and a preheat ring. The lower dome attached to the upper dome. The upper dome and the lower dome define a reaction chamber. The lower liner is positioned below the upper liner. The upper liner and the lower liner define a process gas inlet for channeling the process gas into the reaction chamber. The preheat ring is positioned within the reaction chamber for heating the process gas prior to contacting the semiconductor wafer. The preheating ring is attached to an inner circumference of the lower liner. The preheat ring includes an annular disk and an edge bar. The annular disk has an inner edge, an outer edge, a first side, and a second side opposite the first side. The inner edge and the outer edge define a radial distance therebetween. The edge bar positioned on the first side and extending from the outer edge toward the inner edge an edge bar radial thickness. The radial distance is greater than the edge bar radial thickness.

In another aspect, a preheat ring positioned within a reaction apparatus for heating a process gas prior to contacting a semiconductor wafer during a wafering process is provided. The preheat ring includes an annular disk and an edge bar. The annular disk has an inner edge, an outer edge, a first side, and a second side opposite the first side. The inner edge and the outer edge define a radial distance therebetween. The edge bar is positioned on the first side and extends from the outer edge toward the inner edge an edge bar radial thickness. The radial distance is greater than the edge bar radial thickness.

In yet another aspect, a method of manufacturing a semiconductor wafer in a reaction apparatus is provided. The reaction apparatus includes an upper dome and a lower dome defining a reaction chamber and an upper liner and a lower liner defining a process gas inlet. The reaction apparatus further includes a preheat ring positioned within the reaction chamber for heating the process gas prior to contacting the semiconductor wafer. The preheating ring is attached to an inner circumference of the lower liner and includes an annular disk and an edge bar positioned on the annular disk. The method includes channeling a process gas into the reaction chamber through the process gas inlet. The method also includes heating the process gas with the preheat ring. The method further includes adjusting at least one of a velocity and a direction of the process gas with the edge bar. The method also includes depositing a layer on the semiconductor wafer with the process gas. The edge bar facilitates forming a uniform thickness of the layer on the semiconductor wafer.

Various refinements exist of the features noted in relation to the above-mentioned aspects of the present disclosure. Further features may also be incorporated in the above-mentioned aspects of the present disclosure as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments of the present disclosure may be incorporated into any of the above-described aspects of the present disclosure, alone or in any combination.

Referring now to <FIG>, an apparatus for depositing an epitaxial layer on a semiconductor substrate in accordance with an embodiment of the present disclosure is generally referred to as <NUM>. The illustrated apparatus is a single wafer reactor (i.e., a <NUM> AMAT Centura reactor); however, the apparatus and methods disclosed herein for providing a more uniform epitaxial layer are suitable for use in other reactor designs including, for example, multiple wafer reactors. The apparatus <NUM> includes a reaction chamber <NUM> comprising an upper dome <NUM>, a lower dome <NUM>, an upper liner <NUM>, and a lower liner <NUM>. Collectively, the upper dome <NUM>, lower dome <NUM>, upper liner <NUM>, and lower liner <NUM> define an interior space <NUM> of the reaction chamber <NUM> in which process gas contacts a semiconductor wafer <NUM>. A gas manifold <NUM> is used to direct process gas into the reaction chamber <NUM>. A perspective view of the reaction chamber <NUM> and gas manifold <NUM> is shown in <FIG>. In this embodiment, the apparatus <NUM> is a <NUM> AMAT Centura reactor. In alternative embodiments, the apparatus <NUM> may be any type of reactor.

The apparatus <NUM> may be used to process a wafer in a wafering process, including without limitation, depositing any type of material on a wafer performed by a chemical vapor deposition (CVD) process, such as epitaxial CVD or polycrystalline CVD. In this regard, reference herein to epitaxy and/or CVD processes should not be considered limiting as the apparatus <NUM> may also be used for other purposes such as to perform etching or smoothing processes on the wafer. Also, the wafer shown herein is generally circular in shape, though wafers of other shapes are contemplated within the scope of this disclosure.

The apparatus <NUM> is shown in cross section to better illustrate the apparatus in <FIG>. Within the interior space <NUM> of the reaction chamber <NUM> is a preheat ring <NUM> for heating the process gas prior to contact with a semiconductor wafer <NUM>. The outside circumference of the preheat ring <NUM> is attached to the inner circumference of the lower liner <NUM>. For example, the preheat ring <NUM> may be supported by an annular ledge <NUM> of the lower liner <NUM>. A susceptor <NUM> (which may also be referred to herein as a "susceptor body") traversing the space interior to the preheat ring <NUM> supports the semiconductor wafer <NUM>.

Process gas may be heated prior to contacting the semiconductor wafer <NUM>. Both the preheat ring <NUM> and the susceptor <NUM> are generally opaque to absorb radiant heating light produced by high intensity lamps <NUM>, <NUM> that may be located above and below the reaction chamber <NUM>. Maintaining the preheat ring <NUM> and the susceptor <NUM> at a temperature above ambient allows the preheat ring <NUM> and the susceptor <NUM> to transfer heat to the process gas as the process gas passes over the preheat ring and the susceptor. Typically, the diameter of the semiconductor wafer <NUM> is less than the diameter of the susceptor <NUM> to allow the susceptor to heat the process gas before it contacts the wafer.

The preheat ring <NUM> and susceptor <NUM> may suitably be constructed of opaque graphite coated with silicon carbide, though other materials are contemplated. The upper dome <NUM> and lower dome <NUM> are typically made of a transparent material to allow radiant heating light to pass into the reaction chamber <NUM> and onto the preheat ring <NUM> and the susceptor <NUM>. The upper dome <NUM> and lower dome <NUM> may be constructed of transparent quartz. Quartz is generally transparent to infrared and visible light and is chemically stable under the reaction conditions of the deposition reaction. Equipment other than high intensity lamps <NUM>, <NUM> may be used to provide heat to the reaction chamber such as, for example, resistance heaters and inductive heaters. An infrared temperature sensor (not shown) such as a pyrometer may be mounted on the reaction chamber <NUM> to monitor the temperature of the susceptor <NUM>, preheat ring <NUM>, or semiconductor wafer <NUM> by receiving infrared radiation emitted by the susceptor, preheat ring, or wafer.

The apparatus <NUM> includes a shaft <NUM> that may support the susceptor <NUM>. The shaft <NUM> extends through a central column <NUM>. The shaft <NUM> includes a first end <NUM> attached to the central column <NUM> and a second end <NUM> positioned proximate a center region <NUM> of the semiconductor wafer <NUM>. The shaft <NUM> has a shaft diameter <NUM> of about <NUM> millimeters (mm) to about <NUM>.

The shaft <NUM> is connected to a suitable rotation mechanism (not shown) for rotation of the shaft <NUM>, susceptor <NUM>, and semiconductor wafer <NUM> about a longitudinal axis X with respect to the apparatus <NUM>. The outside edge of the susceptor <NUM> and inside edge of the preheat ring <NUM> (<FIG>) are separated by a gap <NUM> to allow rotation of the susceptor. The semiconductor wafer <NUM> is rotated to prevent an excess of material from being deposited on the wafer leading edge and provide a more uniform epitaxial layer.

The preheat ring <NUM> modifies or tunes the process gas prior to contact with the semiconductor wafer <NUM> in order to improve the growth rate on the semiconductor wafer and create a more uniform radial deposition profile. The upper liner <NUM> and the lower liner <NUM> define a process gas inlet <NUM> and a process gas outlet <NUM>. The process gas inlet <NUM> channels process gas into the reaction chamber <NUM>, and the process gas outlet <NUM> channels process gas out of the reaction chamber. The process gas is channeled from the process gas inlet <NUM> to the process gas outlet <NUM> within the reaction chamber <NUM> as the semiconductor wafer <NUM> is rotated within the reaction chamber.

The process gas inlet <NUM> may be separated into inlet segments <NUM>, <NUM>, <NUM>, <NUM> each having a segment height <NUM> and a segment width <NUM>. Each inlet segment <NUM>, <NUM>, <NUM>, <NUM> channels process gas to a different portion of the semiconductor wafer <NUM>. For example, as illustrated in <FIG>, the upper liner <NUM> and the lower liner <NUM> define a first inlet segment <NUM> that channels process gas to an edge <NUM> of the semiconductor wafer <NUM>, a second inlet segment <NUM> that channels process gas the center region <NUM> of the semiconductor wafer <NUM>, a third inlet segment <NUM> that also channels process gas the center region <NUM> of the semiconductor wafer <NUM>, and a fourth inlet segment <NUM> that also channels process gas to the edge <NUM> of the semiconductor wafer <NUM>.

The growth rate of the semiconductor wafer <NUM> at an edge <NUM> of the semiconductor wafer is greater than the growth rate of the center region <NUM> of the semiconductor wafer. Increased growth rate at the edge <NUM> relative to the center region <NUM> may generate a non-uniform radial deposition profile and a non-uniform thickness of the semiconductor wafer <NUM>. The preheat ring <NUM> described herein modifies or tunes the process gas prior to contact with the semiconductor wafer <NUM> in order to improve the growth rate on the semiconductor wafer, create a more uniform radial deposition profile, and manufacture semiconductor wafers with a uniform thickness.

The preheat ring <NUM> includes an annular disk <NUM> and an edge bar <NUM> attached to the annular disk. The annular disk <NUM> defines an inner edge <NUM> defining a disk hole <NUM> and an inner diameter <NUM>, an outer edge <NUM> defining an outer diameter <NUM>, a first side <NUM>, a second side <NUM>, and a disk thickness <NUM> between the first and second side. The inner diameter <NUM> is greater than a susceptor diameter <NUM> of the susceptor <NUM> such that the preheat ring <NUM> circumscribes the susceptor. Also, the preheat ring <NUM> shown herein is generally circular in shape to compliment the shape of the semiconductor wafer <NUM>, though preheat rings of other shapes are contemplated within the scope of this disclosure to compliment wafers of other shapes.

The outer diameter <NUM> is smaller than a liner diameter <NUM> of the lower liner <NUM> such that the lower liner circumscribes the preheat ring <NUM> and the semiconductor wafer <NUM>. The annular disk <NUM> extends from the inner edge <NUM> to the outer edge <NUM> a radial distance <NUM>. The radial distance <NUM> is configured to enable the preheat ring <NUM> to absorb heat from the high intensity lamps <NUM> and <NUM> and transfer the absorbed heat to the process gas as the process gas passes over the preheat ring.

The edge bar <NUM> extends from the first side <NUM> of the annular disk <NUM> and modifies or tunes the process gas prior to contact with the semiconductor wafer <NUM> in order to improve the growth rate on the semiconductor wafer and create a more uniform radial deposition profile. Specifically, the edge bar <NUM> modifies, tunes, and/or changes at least one of a direction of flow of the process gas, a velocity of the process gas, and a flow rate of the process gas in order to improve the growth rate on the semiconductor wafer and create a more uniform radial deposition profile.

In the illustrated embodiment, the preheat ring <NUM> includes two edge bars <NUM>. In alternative embodiments, the preheat ring <NUM> includes one edge bar <NUM>. In yet another alternative embodiment, the preheat ring <NUM> may include multiple smaller edge bars <NUM>. Accordingly, the preheat ring <NUM> may include at least one edge bar <NUM> and/or a plurality of edge bars <NUM> depending on the flow of process gas within the reaction chamber <NUM>. More specifically, simulations and/or experimental results may be used to determine the number and position of edge bars <NUM> on the preheat ring <NUM> in order to improve the growth rate on the semiconductor wafer <NUM> and create a more uniform radial deposition profile. Similar to the preheat ring <NUM>, the edge bars <NUM> is suitably made of opaque graphite coated with silicon carbide, though other materials are contemplated. In other embodiments, rather than being opaque, the edge bar <NUM> may be made of a translucent or transparent material.

Generally, the edge bar <NUM> is suitably positioned proximate the outer edge <NUM> of the annular disk <NUM>, proximate the process gas inlet <NUM>, and proximate specific regions of the semiconductor wafer <NUM> to correct and/or affect the growth rate of the semiconductor wafer <NUM> during processing, such as epitaxial deposition to alleviate non-uniformities. Specifically, the edge bar <NUM> is positioned proximate the process gas inlet <NUM> to cause the velocity or flow rate of the process gas at the edge <NUM> of the semiconductor wafer <NUM> to increase (relative to when an edge bar is not used) thereby decreasing the amount of material (e.g., silicon) that deposits at the edge of the semiconductor wafer during epitaxial CVD processes. Additionally, the position of the edge bar <NUM> proximate the process gas inlet may cause the direction of the process gas at the edge <NUM> of the semiconductor wafer <NUM> to change (relative to when an edge bar is not used) thereby decreasing the amount of material (e.g., silicon) that deposits in the edge of the semiconductor wafer during epitaxial CVD processes. Accordingly, the edge bar <NUM> is suitably positioned proximate the outer edge <NUM> of the annular disk <NUM> proximate the process gas inlet <NUM> to modify the process gas as it enters the reaction chamber <NUM>. In alternative embodiments, the edge bar <NUM> may be positioned at any location on the preheat ring <NUM> that enables the edge bar <NUM> to operate as described herein.

Additionally, the edge bar <NUM> is positioned relative to the semiconductor wafer <NUM> to correct and/or affect the growth rate of non-uniformities of the semiconductor wafer <NUM> during processing. A simulation and/or experimentation may be used to determine where non-uniformities occur on the semiconductor wafer <NUM> when an edge bar is not used, and the edge bar <NUM> may be positioned on the preheat ring <NUM> to alleviate the non-uniformities. For example, the edge bar <NUM> may be positioned proximate the edge <NUM> of the semiconductor wafer <NUM> to cause the velocity or flow rate of the process gas at the edge to increase (relative to when an edge bar is not used) thereby decreasing the amount of material (e.g., silicon) that deposits at the edge of the semiconductor wafer during epitaxial CVD processes. Additionally, the edge bar <NUM> may be positioned proximate the edge <NUM> of the semiconductor wafer <NUM> to cause the direction of the process gas at the edge to change (relative to when an edge bar is not used) thereby decreasing the amount of material (e.g., silicon) that deposits in the edge of the semiconductor wafer during epitaxial CVD processes.

For example, the edge bars <NUM> of the illustrated embodiment are positioned immediately downstream of the first inlet segment <NUM> and the fourth inlet segment <NUM> to increase the velocity, increase the flow rate, and/or change the direction of the process gas directed toward the edge <NUM> of the semiconductor wafer <NUM>. Accordingly, the edge bar <NUM> is suitably positioned proximate the edge <NUM> of the semiconductor wafer <NUM> in which a localized or global maximum layer thickness occurs to decrease the deposition at the edge and create a more uniform radial deposition profile. Note that this maximum layer thickness may be a local or global maximum, and may generally be referred to as a non-uniformity.

The thickness profile may be determined by use of any suitable method available to those of skill in the art including, for example, use of a Fourier-Transform Infrared (FTIR) spectrometer or use of a wafer flatness tool (e.g., KLA-Tencor Wafersight or WaferSight2; Milpitas, California). In some embodiments, the radial thickness profile of the substrate is determined before material deposition (e.g., before deposition of an epitaxial layer) and the thickness profile of the layered structure may then be measured. The thickness profile of the deposited layer may be determined by subtracting the substrate thickness from the layered structure thickness.

In the illustrated embodiment, each edge bar <NUM> is positioned on the preheat ring <NUM> such that each edge bar defines an edge bar radius <NUM>, an edge bar angle θ relative to a center <NUM> of the semiconductor wafer <NUM>, and an edge bar radial thickness <NUM>. Specifically, the edge bar <NUM> has a first end <NUM> and a second end <NUM>, and the edge bar angle θ is the angle defined between the center <NUM> of the semiconductor wafer <NUM>, the first end, and the second end. The edge bar <NUM> also defines an edge bar circumferential length <NUM> between the first end <NUM> and the second end <NUM> and has an edge bar height <NUM> and an edge bar radial width <NUM>. Additionally, the radial distance <NUM> is greater than the edge bar radial thickness <NUM>.

In the illustrated embodiment, the edge bar <NUM> is a bump or rounded protrusion extending from the first side <NUM> of the preheat ring <NUM>. In alternative embodiments, the edge bar <NUM> may have any shape that enables the edge bar to operate as described herein. Additionally, in the illustrated embodiment, the edge bar <NUM> is curved such that the edge bar forms an arc segment complimentary to the shape of the outer edge <NUM> of the preheat ring <NUM>. In alternative embodiments, the edge bar <NUM> may have any shape that enables the edge bar to operate as described herein. In other embodiments, the edge bar <NUM> may be shaped to include various projections and/or notches or recesses. The edge bar <NUM> may also be beveled or rounded. Such non-uniform shapes may enable the edge bar <NUM> to correct and/or affect the growth rate of non-uniformities of the semiconductor wafer <NUM> during processing. For example, analysis of the thickness profile of the semiconductor wafer <NUM> may identify regions outside of the edges <NUM> that have decreased velocity or flow rate such that the deposition of material in those areas is non-uniform. The shape of the edge bar <NUM> may be adjusted to correct and/or affect the flow of process gas to those regions to decrease material deposition within those regions.

In the illustrated embodiment, the inner diameter <NUM> is about <NUM> to about <NUM>; the outer diameter <NUM> is about <NUM> to about <NUM>; the disk thickness <NUM> is about <NUM> to about <NUM>; the susceptor diameter <NUM> is about <NUM> to about <NUM>; the liner diameter <NUM> is about <NUM> to about <NUM>; the radial distance <NUM> is about <NUM> to about <NUM>; the edge bar radius <NUM> is about <NUM> to about <NUM>; the edge bar circumferential length <NUM> is about <NUM> to about <NUM>; the edge bar height <NUM> is about <NUM> to about <NUM>; the edge bar angle θ is about <NUM>° to about <NUM>°; the segment height <NUM> is about <NUM> to about <NUM>; and the segment width <NUM> is about <NUM> to about <NUM>. In alternative embodiments, the inner diameter <NUM>, the outer diameter <NUM>, the disk thickness <NUM>, the susceptor diameter <NUM>, the liner diameter <NUM>, the radial distance <NUM>, the edge bar radius <NUM>, the edge bar circumferential length <NUM>, the edge bar height <NUM>, the edge bar angle θ, the segment height <NUM>, and the segment width <NUM> may be any distance or angle that enables the edge bar <NUM> to operate as described herein. More specifically, the inner diameter <NUM>, the outer diameter <NUM>, the disk thickness <NUM>, the susceptor diameter <NUM>, the liner diameter <NUM>, the radial distance <NUM>, the edge bar radius <NUM>, the edge bar circumferential length <NUM>, the edge bar height <NUM>, the edge bar angle θ, the segment height <NUM>, and the segment width <NUM> are suitably chosen depending on a location and size of a local or global epitaxial layer thickness minimum or maximum. The ranges recited above for the inner diameter <NUM>, the outer diameter <NUM>, the disk thickness <NUM>, the susceptor diameter <NUM>, the liner diameter <NUM>, the radial distance <NUM>, the edge bar radius <NUM>, the edge bar circumferential length <NUM>, the edge bar height <NUM>, the edge bar angle θ, the segment height <NUM>, the segment width <NUM>, and the like are exemplary and values outside of the stated ranges may be used without limitation.

The edge bar height <NUM> is configured to increase the velocity, increase the flow rate, and/or change the direction of the process gas directed toward the edge <NUM> of the semiconductor wafer <NUM>. In the illustrated embodiment, the edge bar height <NUM> is about <NUM> % to about <NUM> % of the segment height <NUM>. Increasing the edge bar height <NUM> relative to the segment height <NUM> generally results increased process gas velocity, flow rate, and/or a change in direction of the process gas which results in deposition of less material on the semiconductor wafer <NUM> in portions of the semiconductor wafer proximate the edge bar <NUM>. Conversely, decreasing the edge bar height <NUM> relative to the segment height <NUM> generally results decreased process gas velocity, flow rate, and/or less change in direction of the process gas which results in deposition of more material on the semiconductor wafer <NUM> in portions of the semiconductor wafer proximate the edge bar <NUM>. Therefore, the amount of material deposited on portions of the semiconductor wafer <NUM> proximate the edge bar <NUM> is adjusted by varying the edge bar height <NUM>.

The edge bar circumferential length <NUM> is also configured to increase the velocity, increase the flow rate, and/or change the direction of the process gas directed toward the edge <NUM> of the semiconductor wafer <NUM>. In the illustrated embodiment, the edge bar circumferential length <NUM> is about <NUM> % to about <NUM> % of the segment width <NUM>. Increasing the edge bar circumferential length <NUM> relative to the segment width <NUM> generally results increased process gas velocity, flow rate, and/or a change in direction of the process gas which results in deposition of less material on the semiconductor wafer <NUM> in portions of the semiconductor wafer proximate the edge bar <NUM>. Conversely, decreasing the edge bar circumferential length <NUM> relative to the segment width <NUM> generally results decreased process gas velocity, flow rate, and/or less change in direction of the process gas which results in deposition of more material on the semiconductor wafer <NUM> in portions of the semiconductor wafer proximate the edge bar <NUM>. Therefore, the amount of material deposited on portions of the semiconductor wafer <NUM> proximate the edge bar <NUM> is adjusted by varying the edge bar circumferential length <NUM>.

<FIG> is a perspective view of an alternative preheat ring <NUM> including a single edge bar <NUM> positioned immediately downstream of the second inlet segment <NUM> and the third inlet segment <NUM> to increase the velocity, increase the flow rate, or change the direction of the process gas directed toward the center region <NUM> of the semiconductor wafer <NUM>. The edge bar <NUM> illustrated in <FIG> is substantially similar to the edge bars <NUM> illustrated in <FIG> except the edge bar is positioned to address when a localized or global maximum layer thickness occurs in the center region <NUM> rather than the edge <NUM> of the semiconductor wafer <NUM>. Accordingly, the preheat ring <NUM> includes the edge bar <NUM> that is suitably positioned immediately downstream of the second inlet segment <NUM> and the third inlet segment <NUM> to decrease the deposition at the center region and create a more uniform radial deposition profile.

<FIG> is a flow diagram of a method <NUM> of manufacturing a semiconductor wafer in a reaction apparatus. The method <NUM> includes channeling <NUM> a process gas into the reaction chamber through the process gas inlet. The method <NUM> also includes heating <NUM> the semiconductor wafer with the preheat ring. The method <NUM> further includes adjusting <NUM> at least one of a velocity and a direction of the process gas with the edge bar. The method <NUM> also includes depositing <NUM> a layer on the semiconductor wafer with the process gas. The edge bar facilitates forming a uniform thickness of the layer on the semiconductor wafer.

The processes of the present disclosure are further illustrated by the following Example. This Example should not be viewed in a limiting sense.

A preheat ring including at two edge bars positioned in front of the first inlet segment and the fourth inlet segment as described herein was tested in a single wafer epitaxy reactor to determine its effect on the epitaxial wafer growth rate profile. The epitaxial wafers were prepared by exposing single crystal silicon wafers produced by the Czochralski method to a process gas at a wafer temperature between <NUM> to <NUM>. The edge bar had an edge bar height of <NUM>.

A control run was performed in which a preheat ring without an edge bar was used. <FIG> is a graph <NUM> of epitaxial wafer radial growth rate as a function of wafer radial distance. As can be seen from <FIG>, the control resulted in a higher growth rate radial profile <NUM>, and the edge bar resulted in a lower growth rate radial profile <NUM>. The higher growth rate radial profile <NUM> has a first edge growth rate <NUM> and a first center region growth rate <NUM> and the difference between the first edge growth rate <NUM> and the first center region growth rate <NUM> is a first growth rate difference <NUM>. Similarly, the lower growth rate radial profile <NUM> has a second edge growth rate <NUM> and a second center region growth rate <NUM> and the difference between the second edge growth rate <NUM> and the second center region growth rate <NUM> is a second growth rate difference <NUM>. As shown in <FIG>, the first growth rate difference <NUM> is greater than the second growth rate difference <NUM>, and the lower growth rate radial profile <NUM> is more uniform because the difference between the edge growth rate and the center region growth rate of the lower growth rate radial profile <NUM> is smaller than the difference between the edge growth rate and the center region growth rate of the higher growth rate radial profile <NUM>. Accordingly, the edge bars generated a uniform growth rate profile of the epitaxial wafer.

Compared to conventional methods for producing silicon wafers, the systems and methods of the present disclosure have several advantages. For example, reactors that include preheat rings including edge bars as described facilitate cost-effective manufacture of semiconductor wafers with a uniform growth rate profile during deposition. The uniform growth rate profile generates a more uniform deposition thickness profile. Thus, the edge bars enable production of a semiconductor wafer with a uniform thickness profile. An example preheat ring has edge bars near a process gas inlet to correct and/or affect the growth rate of non-uniformities of the semiconductor wafer during processing. The edge bars thereby increase the velocity, increase the flow rate, and/or change the direction of process gas to the edges of the semiconductor wafers, reducing the growth rate of the edges of the semiconductor wafer and manufacturing semiconductor wafers with a uniform thickness profile. Accordingly, the example preheat rings eliminate or reduce local growth rate deviations, as compared to the prior art, to improve the uniformity of epitaxial CVD growth on a wafer. Additionally, use of the above examples can improve the production rate of the epitaxial CVD system, and can lower operational costs by reducing waste.

When introducing elements of the present invention or the embodiment(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," "containing" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of terms indicating a particular orientation (e.g., "top", "bottom", "side", etc.) is for convenience of description and does not require any particular orientation of the item described.

Claim 1:
A reaction apparatus for contacting a process gas with a semiconductor wafer (<NUM>), the reaction apparatus comprising:
an upper dome (<NUM>);
a lower dome (<NUM>) attached to the upper dome, the upper dome and the lower dome defining a reaction chamber (<NUM>);
an upper liner (<NUM>);
a lower liner (<NUM>) positioned below the upper liner, the upper liner and the lower liner defining a process gas inlet (<NUM>) for channeling the process gas into the reaction chamber; and
a preheat ring (<NUM>) positioned within the reaction chamber for heating the process gas prior to contacting the semiconductor wafer, the preheating ring attached to an inner circumference of the lower liner, the preheat ring comprising:
an annular disk (<NUM>) having an inner edge (<NUM>), an outer edge (<NUM>), a first side (<NUM>), and a second side opposite the first side (<NUM>), the inner edge and the outer edge defining a radial distance (<NUM>) therebetween;
characterized in
an edge bar (<NUM>) positioned on the first side and extending from the outer edge toward the inner edge an edge bar radial thickness (<NUM>), wherein the radial distance (<NUM>) is greater than the edge bar radial thickness (<NUM>);
the edge bar (<NUM>) has an edge bar height (<NUM>) and an edge bar circumferential length (<NUM>), wherein the edge bar height (<NUM>) and the edge bar circumferential length (<NUM>) are each configured to adjust a velocity and/or a direction of the process gas.