Substrate processing apparatuses and systems

A system for processing substrates is described. In one embodiment, the system comprises a process chamber, at least one electrical resistance heater, and at least one Coanda effect gas injector.

BACKGROUND

This invention relates to systems, apparatuses, and methods for processing substrates; more particularly, chemically and/or thermally processing substrates for electronic devices and optical-electronic devices.

Chemical and/or thermal processing of substrates is used in numerous applications such as modern microelectronic device manufacturing. These processes may include processes such as chemical vapor deposition (CVD) and epitaxial semiconductor deposition such as silicon epitaxy, silicon germanium epitaxy, and compound semiconductor epitaxy. These processes may be performed using one or more gases for causing reactions on the surface of substrates such as semiconductor wafers, flat panel display substrates, solar cell substrates, and other substrates.

SUMMARY

This invention seeks to provide systems, apparatuses, and methods that can overcome one or more deficiencies in processing substrates. One aspect of the invention is a system for processing substrates. The system comprises a process chamber; a substrate support disposed in the process chamber, a heating system, and a gas injection system.

In one embodiment, the heating system comprises at least one electrical resistance heater comprising a sinusoidal heating element having a plurality of peaks disposed to delineate an outer radius and a plurality of troughs disposed to delineate an inner radius. The cross-section width of the heating element is a first function of radial position and the cross-section thickness of the heating element is a second function of radial position so that the heating element provides a substantially constant heat flux at each radial position and forms a substantially constant spacing between facing side surfaces of the heating element.

In another embodiment, the gas injection system comprises at least one Coanda effect gas injector disposed proximate a peripheral edge of the substrate support so as to provide a Coanda effect gas flow over the surface of the substrate(s) and/or substrate support.

In yet another embodiment the heating system comprises at least one electrical resistance heater comprising a sinusoidal heating element having a plurality of peaks disposed to delineate an outer radius and a plurality of troughs disposed to delineate an inner radius. The cross-section width of the heating element is a first function of radial position and the cross-section thickness of the heating element is a second function of radial position so that the heating element provides a substantially constant heat flux at each radial position and forms a substantially constant spacing between facing side surfaces of the heating element. The gas injection system comprises at least one Coanda effect gas injector disposed proximate a peripheral edge of the substrate support so as to provide a Coanda effect gas flow over the surface of the substrate(s) and/or substrate support.

Another aspect of the present invention is a method of processing a substrate. The method comprises providing a substrate and providing one or more reactive gases. The method also comprises providing at least one heater or heater assembly comprising a sinusoidal heating element having a plurality of peaks disposed to delineate an outer radius and a plurality of troughs disposed to delineate an inner radius. The cross-section width of the heating element is a first function of radial position and the cross-section thickness of the heating element is a second function of radial position so that the heating element provides a substantially constant heat flux at each radial position and forms a substantially constant spacing between facing side surfaces of the heating element. The method further comprises applying heat to the substrate with the at least one heater or heating assembly and creating a Coanda effect gas flow of the one or more reactive gases over the substrate.

DESCRIPTION

For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. All numeric values are herein defined as being modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that a person of ordinary skill in the art would consider equivalent to the stated value to produce substantially the same properties, function, result, etc. A numerical range indicated by a low value and a high value is defined to include all numbers subsumed within the numerical range and all subranges subsumed within the numerical range. As an example, the range 10 to 15 includes, but is not limited to, 10, 10.1, 10.47, 11, 11.75 to 12.2, 12.5, 13 to 13.8, 14, 14.025, and 15.

The operation of embodiments of the present invention will be discussed below in the context of the deposition of an epitaxial layer of doped silicon on a silicon wafer. It is to be understood, however, that embodiments in accordance with the present invention may be used to perform essentially any substrate processing that may benefit from layer thickness uniformity, composition uniformity, and/or temperature uniformity across the substrate. As examples, embodiments of the present invention may include equipment and/or processes for depositing layers of materials such as gallium nitride, gallium arsenide, silicon germanium, gallium aluminum arsenide, indium phosphide, cadmium telluride, mercury cadmium telluride, silicon carbide, silicon nitride, silicon dioxide, doped silicon oxide, boron phosphorus silicate glass, phosphorus silicate glass, and others.

Reference is now made toFIG. 1where there is shown a block diagram of a system100according to an embodiment of the present invention. System100includes a process chamber150. Process chamber150may be a process chamber such as a process chamber for processing substrates such as substrates used for fabricating electronic and optoelectronic devices. The substrates may be substrates such as semiconductor wafers, single crystal substrates such as a Sapphire wafers, and glass substrate. System100also includes a heating system200for providing heat to the substrates. System100includes a gas injection system250for providing one or more gases or gas mixtures to the substrates and/or process chamber150. System100may include, as an option, a control system. If present, the control system may be in communication with process chamber150, heating system200, and gas injection system250so as to monitor their operation, collect information, issue and execute commands to control the operation of system100.

Reference is now made toFIG. 2where there is shown a cross-section side view of a system101according to an embodiment of the present invention. System101comprises a process chamber having a top surface152-1and a bottom surface152-2substantially as shown inFIG. 2. Optionally, one or more substrates154(position of substrates shown as broken lines) may be placed on the bottom of the process chamber for processing. Alternatively, system101includes a substrate holder156disposed so as to hold one or more substrates154in the process chamber. As an option for some embodiments of the present invention, bottom surface152-2of the process chamber has a recessed area153that at least partially contains substrate holder156.

System101shown inFIG. 2comprises a rotary coupling180connected with substrate holder156so as to provide rotation for one or more substrates154. More specifically, system101comprises rotary coupling180disposed for rotating the surface of substrate support156and the one or more substrates154, if present thereon. Alternatively, system101may comprise a linear actuator connected with substrate support156for linear translation of the surface of substrate support156.

System101comprises a heating system that includes a heater assembly202disposed so as to provide heat to the substrates154. System101has heater assembly202disposed so as to face the external side of bottom surface152-2so as to heat the substrates from the back surface. Heater assembly202includes one or more electrical resistance heaters.

Reference is now made toFIG. 3where there is shown a back view of an electrical resistance heater220that may be used in heater assembly202according to an embodiment of the present invention. Electrical resistance heater220is formed by a sinusoidal heating element222having a plurality of troughs224disposed to delineate an inner radius226and a plurality of peaks228disposed to delineate an outer radius230. In other words, electrical resistance heater220forms a ring or section of a ring having an inner radius226and an outer radius230so as to make heater220circular, either a circle or part of a circle. The cross-section width of sinusoidal heating element222is a first function of radial position and the cross-section thickness of sinusoidal heating element222is a second function of radial position so that sinusoidal heating element222provides a substantially constant heat flux at each radial position and forms a substantially constant spacing232between facing side surfaces234and236of sinusoidal heating element222. Spacing232between facing side surfaces of sinusoidal heating element222is maintained at a selected constant and may be kept to a minimum with the limits being determined by the need to avoid arcing, thermal expansion and contraction limitations, and fabrication limitations. Heating element222can be represented as having a plurality of spokes233extending from the inside radius226to the outside radius230.

The cross-section area of sinusoidal heating element222is given by multiplying the cross-section width of sinusoidal heating element222generally at each radial position by the cross-section thickness of sinusoidal heating element222generally at each radial position. The cross-section area varies with radial position based on the size of the surface to be heated and the wattage requirement. Additional factors that determine the cross-section area of the sinusoidal heating element are the number of oscillations in the sinusoidal heating element, resistivity of the sinusoidal heating element, spacing between facing sides of the sinusoidal heating element, and the length of the sinusoidal heating element.

As indicated above, the cross-section thickness and the cross-section width of the heating element at each radial position are functions of the radial position on the sinusoidal heating element. The thickness can be represented in general by a function of the form f1(1/r) where r is radial position on the sinusoidal heating element and f1is the function. The term 1/r is used to indicate that the relation is an inverse relation. The width can be represented in general by a function of the form f2(r) where r is radial position on the sinusoidal heating element and f2is the function. Consequently, the cross-section area of the sinusoidal heating element is a function of the form (f1(1/r)(f2(r).

For some embodiments of the present invention, the cross-section thickness of the sinusoidal heating element is derived from the equation:
t=2πri2Gti/(2πr2G−Sr)  (1)
where t is cross-section thickness of the heating element, r is radial position on the heating element, π is the mathematical constant pi, riis an inside radius of the heating element, tiis an initial trial thickness, G is a geometry factor equaling the angular width of the heating element spoke divided by the angular size of the heater, and S is the spacing between facing side surfaces of the heating element. More specifically, t and r are variables and π, ri, ti, G, and S are numerical parameters. With the knowledge of the numerical parameters for a heater, the thickness can be calculated as a function of radial position.

As will be recognized by persons of ordinary skill in the art, Equation 1 and the numerical parameters are the result of only one approach to obtaining a numerical representation of the dimensions of heaters according to one or more embodiments of the present invention. Other approaches will be recognized by persons of ordinary skill in the art in view of the disclosure in this specification. The derivation of Equation (1) was accomplished using π the mathematical constant, rias a designer choice, an outside radius of the heater as a designer choice, G as a designer choice, and S as a designer choice. The initial trial thickness of the heater element at the inside radius, ti, is also a designer choice, but optionally timay have to be refined by iteration so that the resistance of the heater element is more suitably matched for use with the full voltage and current capacity of the power source to be used with the heater. The capacity of the power source is also a designer choice. One possible iteration procedure is presented below in an example heater design.

It is also possible to derive the numerical parameters or equivalent constants for an equation similar to Equation (1) if heater thickness data as a function of radial position is known for a heater. A further simplified equation for such situations could be of the form:
t=A/(Br2−Sr)  (1.1)
where t, r, and S are the same as presented above and A and B are numerical values resulting from combining one or more of the numerical parameters presented above.

For some embodiments of the present invention, the cross-section width of the sinusoidal heating element is derived from the equation:
w=2πGr−S(2)
where w is the cross-section width of the heating element, r is the radial position on the heating element, π is the mathematical constant pi, G is a geometry factor equaling the angular width of the heating element spoke divided by the angular size of the heater, and S is a spacing between facing side surfaces of the heating element. The width of the heating element as a function of radial position can be calculated for more one or more embodiment of the present invention with designer specified values for angular width of the heating element spoke, the angular size of the heater, and the spacing.

A variety of materials may be used for sinusoidal heating element222. According to one embodiment of the present invention, sinusoidal heating element222comprises a refractory electrical conductor. Sinusoidal heating element222may comprise graphite such as pyrolytic graphite. Further modifications can be made such as coating pyrolytic graphite with a material such as silicon carbide to produce sinusoidal heating element222having, as an example, a pyrolytic graphite conductor coated with silicon carbide. Examples of other materials that can be used for sinusoidal heating element222include, but are not limited to, nickel-chromium alloy, molybdenum, tantalum, tungsten, and other materials used for electrical resistance heating.

According to one embodiment of the present invention, spacing232between facing side surfaces of sinusoidal heating element222is at vacuum or filled with gas during operation of sinusoidal heating element222.

FIG. 3shows electrical resistance heater220comprising two optional electrical contacts238positioned approximately at each end of sinusoidal heating element222. It is to be understood that other means of making contact can be used for electrical heater220. Electrical contact238shown for the embodiment inFIG. 3may be a tab machined as part of sinusoidal heating element222. As an option, electrical contact238is oriented substantially perpendicular to the surface of electrical resistance heater220. Other orientations for electrical contact238can be used as will be clear to persons of ordinary skill in the art in view of the present disclosure. Electrical contacts238can be used to apply a DC or AC current through sinusoidal heating element222.

Reference is now made toFIG. 3-1where there is shown a perspective view of an electrical resistance heater220-1that may be used in heater assembly202according to an embodiment of the present invention. Electrical resistance heater220-1is essentially the same as described for electrical resistance heater220described forFIG. 3with the exception that electrical resistance heater220-1includes an optional electrical adapter240coupled with electrical contact238for each end of serpentine electrical conductor222.

According to one embodiment of the present invention, electrical adapter240is formed so as to make a press-fit, also known in the art has an interference fit, coupling to electrical contact238. For some embodiments of the present invention, serpentine heating element222may be made of pyrolytic graphite; as an option for those embodiments, electrical adapter240may be made of pyrolytic graphite. Optionally, electrical adapter240may be made of materials other than pyrolytic graphite that are also suitable for electrical connections.

The present inventors have found that a synergistic benefit may be occurring for embodiments of the present invention that use pyrolytic graphite for sinusoidal heating element222and pyrolytic graphite for electrical adapter240in a press-fit coupling configuration and a silicon carbide coating process. More specifically, applying a thermal coating of silicon carbide to sinusoidal heating element222and press-fit coupled electrical adapter240produces a mechanically strong connection between sinusoidal heating element222and electrical adapter240with a low contact resistance. Consequently, a strong mechanical connection is formed that is electrically conductive and it may be accomplished without complicated machining steps beyond a press-fit coupling.

The deposition conditions used for forming the silicon carbide coatings are the same as those typically used for coating pyrolytic graphite. Generally, a silicon source and a carbon source are caused to react at elevated temperatures 1200 degrees C. to produce a deposited coating of silicon carbide.

Reference is now made toFIG. 3-2where there is shown a perspective view andFIG. 3-3where there is shown a cross-section perspective view of an electrical adapter240-1suitable for one or more embodiments of the present invention. Electrical adapter240-1is a substantially rigid body made of a suitable electrical conductor such as pyrolytic graphite or other material suitable for electrical contact for an electrical resistance heater. Electrical adapter240-1has a threaded bore240-2that has been threaded for making a threaded connection. Electrical adapter240-1has a press-fit bore240-3that has been configured to make a press-fit coupling with electrical contacts of electrical resistance heaters such as, but not limited to, electrical resistance heater220.

Reference is now made toFIG. 4where there is shown a back view of an electrical resistance heater242that may be used in heater assembly202according to an embodiment of the present invention. Electrical resistance heater242is formed by a sinusoidal heating element222having a plurality of troughs224disposed to delineate an inner radius226and a plurality of peaks228disposed to delineate an outer radius230. In other words, heater242forms a section of a ring having an inner radius226and an outer radius230so as to make heater242a part of a circle. The cross-section width of sinusoidal heating element222is a first function of radial position and the cross-section thickness of sinusoidal heating element222is a second function of radial position so that sinusoidal heating element222provides a substantially constant heat flux at each radial position and forms a substantially constant spacing232between facing side surfaces234and236of sinusoidal heating element222. Spacing232between facing side surfaces of sinusoidal heating element222is maintained at a selected constant and may be kept to a minimum with the limits being determined by the need to avoid arcing, thermal expansion and contraction limitations, and fabrication limitations.

The cross-section area of sinusoidal heating element222is given by the multiplying the cross-section width of sinusoidal heating element222generally at each radial position by the cross-section thickness of sinusoidal heating element222generally at each radial position. The cross-section area is held at a selected constant based on the size of the surface to be heated and the wattage requirement. Additional factors that determine the cross-section area of the sinusoidal heating element are the number of oscillations in the sinusoidal heating element, resistivity of the heating element, spacing between facing sides of the sinusoidal heating element, and the length of the sinusoidal heating element.

As indicated above, the cross-section thickness and the cross-section width of the heating element at each radial position are functions of the radial position on the sinusoidal heating element. The thickness can be represented in general by a function of the form f1(1/r) where r is radial position on the sinusoidal heating element and f1is the function. The term 1/r is used to indicate that the relation is an inverse relation. The width can be represented in general by a function of the form f2(r) where r is radial position on the sinusoidal heating element and f2is the function. Consequently, the cross-section area of the sinusoidal heating element is a function of the form (f1(1/r))(f2(r)).

For some embodiments of the present invention, the cross-section thickness of the sinusoidal heating element is derived from the equation:
t=2πri2Gti/(2πr2G−Sr)  (1)
where t is cross-section thickness of the heating element, r is radial position on the heating element, π is the mathematical constant pi, riis an inside radius of the heating element, tiis an initial trial thickness, G is a geometry factor equaling the angular width of the heating element spoke divided by the angular size of the heater, and S is the spacing between facing side surfaces of the heating element. More specifically, t and r are variables and π, ri, ti, G, and S are numerical parameters. With the knowledge of the numerical parameters for a heater, the thickness can be calculated as a function of radial position.

As will be recognized by persons of ordinary skill in the art, Equation 1 and the numerical parameters are the result of only one approach to obtaining a numerical representation of the dimensions of heaters according to one or more embodiments of the present invention. Other approaches will be recognized by persons of ordinary skill in the art in view of the disclosure in this specification. The derivation of Equation (1) was accomplished using π the mathematical constant, rias a designer choice, an outside radius of the heater as a designer choice, G as a designer choice, and S as a designer choice. The initial trial thickness of the heater element at the inside radius, ti, is also a designer choice, but optionally timay have to be refined by iteration so that the resistance of the heater element is more suitably matched for use with the full voltage and current capacity of the power source to be used with the heater. The capacity of the power source is also a designer choice. One possible iteration procedure is presented below in an example heater design.

It is also possible to derive the numerical parameters or equivalent constants for an equation similar to Equation (1) if heater thickness data as a function of radial position is known for a heater. A further simplified equation for such situations could be of the form:
t=A/(Br2−Sr)  (1.1)

where t, r, and S are the same as presented above and A and B are numerical values resulting from combining one or more of the numerical parameters presented above.

For some embodiments of the present invention, the cross-section width of the sinusoidal heating element is derived from the equation:
w=2πGr−S(2)
where w is the cross-section width of the heating element, r is the radial position on the heating element, π is the mathematical constant pi, G is a geometry factor equaling the angular width of the heating element spoke divided by the angular size of the heater, and S is a spacing between facing side surfaces of the heating element. The width of the heating element as a function of radial position can be calculated for more one or more embodiment of the present invention with designer specified values for angular width of the heating element spoke, the angular size of the heater, and the spacing.

A variety of materials may be used for sinusoidal heating element222. According to one embodiment of the present invention, sinusoidal heating element222comprises a refractory electrical conductor. The sinusoidal heating element222may comprise graphite such as pyrolytic graphite. Further modifications can be made such as coating pyrolytic graphite with a material such as silicon carbide to produce sinusoidal heating element222having, as an example, a pyrolytic graphite conductor coated with silicon carbide. Examples of other materials that can be used for sinusoidal heating element222include, but are not limited to, nickel-chromium alloy, molybdenum, tantalum, tungsten, and other materials used for electrical resistance heating.

FIG. 4shows electrical resistance heater242comprising two optional electrical contacts238positioned approximately at each end of sinusoidal heating element222. It is to be understood that other means of making contact can be used for electrical heater220. Electrical contact238may be a tab machined as part of sinusoidal heating element222. As an option, electrical contact238is oriented substantially perpendicular to the surface of electrical resistance heater220. Other orientations for electrical contact238can be used as will be clear to persons of ordinary skill in the art in view of the present disclosure. Electrical contacts238can be used to apply a DC or AC current through sinusoidal heating element222.

FIG. 4shows an optional configuration for peaks228. Specifically, one or more of the peaks may be shorter than surrounding peaks as is shown for two of the peaks inFIG. 4. This optional configuration can be used to accommodate other structures such as attachment structures, sensors, holders that could be used for operating and monitoring electrical resistance heater242. Similar modifications can be made to troughs224.

Reference is now made toFIG. 4-1where there is shown a perspective back view of an electrical resistance heater242-1. Electrical resistance heater242-1is essentially the same as described for electrical resistance heater242described forFIG. 4with the exception that electrical resistance heater242-1includes an optional electrical adapter240coupled with electrical contact238for each end of sinusoidal electrical conductor222.

According to one embodiment of the present invention, electrical adapter240is formed so as to make a press-fit, also known in the art has an interference fit, coupling to electrical contact238. For some embodiments of the present invention, serpentine heating element222may be made of pyrolytic graphite; as an option for those embodiments, electrical adapter240may be made of pyrolytic graphite. Optionally, electrical adapter240may be made of materials other than pyrolytic graphite that are also suitable for electrical connections.

Reference is now made toFIG. 5where there is shown a front view of a heater assembly244that may be used in system100or system101according to one embodiment of the present invention. Heater assembly244comprises a plurality of electrical resistance heaters shaped as rings or sections of rings. More specifically, heater assembly244comprises a first heater246located at the center. Optionally, first heater246may be a ring heater or a section of a ring heater. As another option, first heater246may be a ring heater that is essentially the same as electrical resistance heater220as described inFIG. 3or a combination of electrical resistance heaters242as described inFIG. 4. Alternatively, first heater246may have a configuration other than the configuration for electrical resistance heaters220and electrical resistance heaters242described supra. The embodiment of the present invention shown inFIG. 5has first heater246including a heating element having a dissimilar configuration to those of electrical resistance heater220and electrical resistance heater242.

Heater assembly244further comprises an electrical resistance heater220surrounding first heater246. Electrical resistance heater220is essentially the same as described for electrical resistance heater220inFIG. 3.

Heater assembly244further comprises12electrical resistance heaters242shaped as quarter ring sections and disposed so as to form a substantially planar array of concentric rings for a substantially circular heated area. Electrical resistance heater242is essentially the same as described for electrical resistance heaters242inFIG. 4. It is to be understood that other embodiments of the present invention may use a number of electrical resistance heaters242other than12and that the combination of ring heaters and sections of ring heaters may also differ from what is described forFIG. 5. Specifically, more than12electrical resistance heaters242may be used in embodiments of the present invention or fewer than12electrical resistance heaters242may be used in heating assemblies according to embodiments of the present invention. Similarly, more than one electrical resistance heater220may be used in heating assemblies according to embodiments of the present invention or no resistance heater220may be used in embodiments of the present invention.

Heater assemblies according to embodiments of the present invention include at least one electrical resistance heater selected from the group consisting of: electrical resistance heater220, electrical resistance heater220-1, electrical resistance heater242, and electrical resistance heater242-1.

Reference is now made toFIG. 5-1where there is shown a back view of a heater assembly244-1according to one embodiment of the present invention. Heater assembly244-1comprises a plurality of electrical resistance heaters shaped as rings or sections of rings. More specifically, heater assembly244-1comprises a first heater246-1located at the center. First heater246-1comprises electrical contacts substantially as described above (electrical contacts not visible inFIG. 5-1) and electrical adapters such as electrical adapter240-1substantially as described above coupled to the electrical contacts. Optionally, first heater246-1may be a ring heater or a section of a ring heater. As another option, first heater246-1may be a ring heater that is essentially the same as electrical resistance heater220-1as described inFIG. 3-1or a combination of electrical resistance heaters242-1as described inFIG. 4-1. Alternatively, first heater246-1may have a configuration other than the configuration for electrical resistance heaters220-1and electrical resistance heaters242-1described supra. The embodiment of the present invention shown inFIG. 5-1has first heater246-1including a heating element having a dissimilar configuration to those of electrical resistance heaters220-1and electrical resistance heaters242-2.

Heater assembly244-1further comprises an electrical resistance heater220-1surrounding first heater246-1. Electrical resistance heater220-1is essentially the same as described for electrical resistance heaters220-1inFIG. 3-1. Electrical adapters240-1for electrical resistance heater220-1are also shown inFIG. 5-1.

Heater assembly244-1further comprises12electrical resistance heaters242-1shaped as quarter ring sections and disposed so as to form a substantially planar array of concentric rings for a substantially circular heated area. Electrical resistance heater242-1is essentially the same as described for electrical resistance heaters242-1inFIG. 4-1. Electrical adapters240-1for electrical resistance heater242-1are also shown inFIG. 5-1.

An apparatus according to another embodiment of the present invention is an electrical resistance heater that comprises a pyrolytic graphite heating element. The pyrolytic graphite heating element has one or more pyrolytic graphite electrical contacts. The electrical resistance heater further comprises one or more pyrolytic graphite electrical adapters such as electrical adapters240and electrical adapters240-1described above. The one or more electrical adapters are press-fit coupled to the one or more pyrolytic graphite electrical contacts. The electrical resistance heater further includes a layer of silicon carbide overcoating the heating element and electrical adapter. The silicon carbide overcoating is applied after press-fit coupling the one or more pyrolytic graphite electrical contacts to the one or more electrical adapters. The silicon carbide coating may be applied using a high temperature chemical vapor deposition process.

Reference is now made toFIG. 6where there is shown a cross-section side view of a system103according to an embodiment of the present invention. System103comprises a process chamber having a top surface152-1and a bottom surface152-2. Optionally, one or more substrates154(position of substrates shown as broken lines) may be placed on the bottom of the process chamber for processing. Alternatively, system103includes a substrate holder156disposed so as to hold one or more substrates154in the process chamber. As an option for some embodiments of the present invention, bottom surface152-2of the process chamber has a recessed area153that at least partially contains substrate holder156. System103comprises a Rotary coupling180substantially as described above and a heater assembly202substantially as described above. System103is essentially the same as system101, as described above, with the addition of at least one Coanda a gas injector252.

More specifically, system103comprises at least one Coanda effect gas injector252disposed proximate a peripheral edge of substrate support156so as to provide a Coanda effect gas flow over the surface of substrate support156and/or the one or more substrates154. According to some embodiments of the present invention, system103further comprises a gas flow control system (not shown inFIG. 3) in fluid communication with the at least one Coanda effect gas injector252so as to provide one or more reactive gases to the at least one Coanda effect gas injector252.

In one embodiment of system103, Coanda effect gas injector252has a gas entry port253, a gas flow channel254, and a gas exit port255. Gas exit port255is in fluid communication with gas flow channel254, and gas flow channel254is in fluid communication with the gas entry port253. Gas flow channel254is formed by a convex surface254-1of Coanda effect gas injector252to produce the Coanda effect gas flow. More specifically, convex surface254-1is formed and disposed so as to tangentially approach a plane located approximately at the surface of a substrates154and/or the surface of substrate holder156. Convex surface254-1, according to one embodiment of the present invention, is a curved surface. As an option for other embodiments, convex surface254-1is formed by one or more sloping surfaces with little or no curvature for each of the sloping surfaces.

The Coanda effect gas flow results from flowing the gas over convex surface254-1which induces an attachment between the gas flow and convex surface254-1so that the gas flow substantially follows convex surface254-1. The present inventors have found that the gas leaving Coanda effect gas injector252appears to continue the attachment for some distance to include at least part of the surface of substrate holder156and/or at least part of the surface of the one or more substrates154. The present inventors believe that a possible explanation is that the attachment between the gas flow and the surfaces aid in keeping one or more reactive chemicals in the gas flow closer to the surface of the substrate so that the one or more reactive chemicals are more efficiently used for processing the surface of the substrates, or one or more other phenomena may be involved with producing the benefits from the use of the Coanda effect. In other words, the Coanda effect gas flow appears to interact synergistically with the surface of the substrate to keep the one or more reactive chemicals near the surface of the substrate for a longer time interval. Discussions of the Coanda effect can be found in “Applications of the Coanda Effect,” by Imants Reba, Scientific American, Vol. 214, No. 6, June 1966, pages 84-92 and U.S. Pat. No. 2,052,869 to H. Coanda; the content of these documents are incorporated herein by this reference for all purposes.

As an option for some embodiments of the present invention, the at least one Coanda effect gas injector252has a gas exit port255that is rectangular in shape so as to form a slit. Alternatively, the gas exit port255may be square or another geometric shape.

As an option for some embodiments of the present invention, the at least one Coanda effect gas injector252is disposed in the process chamber so that gas exit port255is substantially coplanar with or above the surface of the one or more substrates154and/or substantially coplanar with or above the surface of substrate support156. As another option, the at least one Coanda effect gas injector252is disposed in the process chamber so that gas exit port255is substantially coplanar with or above bottom surface152-2of the process chamber.

Reference is now made toFIG. 7andFIG. 7-1where there is shown a top view and a cross-section side view, respectively, of a Coanda effect gas injector252-1for one or more embodiments of the present invention. Broken lines are used to illustrate hidden lines. Coanda effect gas injector252-1may be used, as an option, to replace the at least one Coanda effect gas injector252described for embodiments of the present invention illustrated inFIG. 6. Coanda effect gas injector252-1is similar to the at least one Coanda effect gas injector252.

Coanda effect gas injector252-1is a substantially rigid structure having a gas entry port253, a gas flow channel254, and a gas exit port255. Coanda effect gas injector252-1also has a plenum256that is not present in the at least one Coanda effect gas injector252. Gas exit port255is in fluid communication with plenum256via gas flow channel254. Gas entry port253is in fluid communication with plenum256. Gas flow channel254is formed by at least one convex surface254-1of Coanda effect gas injector252-1so as to produce the Coanda effect gas flow.

During operation, Coanda effect gas injector252-1receives a gas or a mixture of gases at gas entry port253, the gas flows into plenum256from gas entry port253and continues on into gas flow channel254, passes over convex surface254-1, and exits at gas exit port255.

Reference is now made toFIG. 8andFIG. 8-1where there are shown a cross-section side view of a system106for processing substrates and a top view of the interior of system106according to an embodiment of the present invention. System106comprises a process chamber that includes a bottom surface152-2and a top surface (the top surface is not shown inFIG. 8-1). System106includes a substrate holder156disposed so as to hold one or more substrates154in the process chamber.FIG. 8andFIG. 8-1, as an example, use broken lines to illustrate how three substrates154can be positioned for processing on substrate holder156. As an option for some embodiments of the present invention, bottom surface152-2of the process chamber has a recessed area (not shown inFIG. 8-1) that at least partially contains substrate holder156. System106comprises an outer chamber170having an exhaust port172. Outer chamber170substantially encloses the process chamber.

System106comprises an optional rotary coupling connected with substrate support156for rotating the surface of substrate support156and the one or more substrates154, if present thereon. Alternatively, system106may comprise a linear actuator connected with substrate support156for linear translation of the surface of substrate support156.

System106comprises a heating system that includes a heater assembly202disposed so as to provide heat to substrates154. System106has heater assembly202disposed so as to face the external side of bottom surface152-2so as to heat the substrates from the back surface. Optionally, heater assembly202may be disposed so as to face the external side of top surface152-1so as to heat the substrates from the front surface. As still another option as shown inFIG. 8, system106has a heater assembly202disposed over top surface152-1and a heater assembly202disposed below bottom surface152-2so that the substrates can be heated from the back surface and from the front surface. Heater assembly202includes one or more electrical resistance heaters substantially as described above.

More specifically, heater assembly202may comprise one or more electrical resistance heaters220as described above, one or more electrical resistance heaters220-1as described above, one or more electrical resistance heaters242as described above, one or more electrical resistance heaters242-1as described above, and/or one or more first heaters246-1as described above. Heater assembly202may be a heater assembly such as heater assembly244as described above or a heater assembly such as heater assembly244-1as described above.

System106comprises at least one Coanda effect gas injector252-1disposed proximate a peripheral edge of substrate support156so as to provide a Coanda effect gas flow over the surface of substrate support156and/or the one or more substrates154.FIG. 8-1shows five Coanda effect gas injectors252-1. According to some embodiments of the present invention, system106further comprises a gas flow control system (not shown inFIG. 8andFIG. 8-1) in fluid communication with the at least one Coanda effect gas injector252-1so as to provide one or more reactive gases to the at least one Coanda effect gas injector252-1.

Coanda effect gas injector252-1is essentially the same as described above forFIG. 7andFIG. 7-1. Alternatively, system106may comprise one or more or combinations of Coanda effect gas injectors such as Coanda effect gas injector252as described above forFIG. 6.

System106comprises at least one secondary gas injector270disposed so as to provide one or more gases or gas mixtures over bottom surface152-2of the process chamber. More specifically, the at least one secondary gas injector270is arranged to flow a gas or gas mixture over substrates154and/or substrate holder156.FIG. 7has five secondary gas injectors270. The at least one secondary gas injector270is not a Coanda effect gas injector. The at least one secondary gas injector270may be a standard gas injector such as those typically used for processing substrates such as a solid body having a borehole for gas flow therethrough, such as a tube, such as a tube having a showerhead or nozzle, or such as another type of nozzle.

System106shows an embodiment with the at least one secondary gas injector270positioned behind the at least one Coanda effect gas injector252-1. It is to be understood that other embodiments of the present invention may have relative positions and orientations of the at least one secondary gas injector270and the at least one Coanda effect gas injector252-1different from the arrangement shown inFIG. 8andFIG. 8-1.

A potential benefit may be achieved for some embodiments of the present invention as a result of combining the use of the at least one Coanda effect gas injector252-1and the at least one secondary injector270. In other words, a synergistic interaction between the gas flow from the at least one Coanda effect gas injector252-1and the gas flow from the at least one secondary injector270may yield improved process results.

As an option for some embodiments of the present invention, systems such as system101, system103, and system106may be configured to have hot wall process chambers for which the electrical resistance heaters are disposed so as to heat the substrates154, the substrate holder156, and the walls of the process chamber including top surface152-1and bottom surface152-2. Alternatively, the system may be a cold wall system configured so that the electrical resistance heaters substantially only heat the substrates154and/or the substrate holder156without substantial heating of the walls of the process chamber and/or having cooled process chamber walls. A potential benefit for some embodiments of the present invention is that the Coanda effect gas flow could mitigate some of the effects of temperature-induced convection caused by variations in temperatures above the substrates.

For some embodiments of the present invention, the process chamber, the substrate support, the outer chamber, the heater assembly, and the Coanda effect gas injectors comprise materials suitable for processing semiconductor devices. Examples of materials suitable for use with embodiments of the present invention include, but are not limited to, aluminum oxide, aluminum nitride, silicon carbide, silicon nitride, silicon dioxide such as quartz or fused silica, stainless steel, graphite, and silicon carbide coated graphite.

The systems and apparatuses described supra may be used for a wide variety of processes according to embodiments of the present invention. Reference is now made toFIG. 9where there is shown an exemplary process diagram291according to one embodiment of the present invention. Exemplary process diagram291comprises a non-exhaustive series of steps to which additional steps (not shown) may also be added. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.FIG. 9shows exemplary process diagram291for performing a chemical reaction on a substrate comprises providing a substrate293. Exemplary process diagram291comprises providing at least one heater or heater assembly295as described above and illustrated inFIG. 2,FIG. 3,FIG. 3-1,FIG. 4,FIG. 4-1,FIG. 5, andFIG. 5-1. Specific examples of heaters suitable for exemplary process diagram291are electrical resistance heater220, electrical resistance heater220-1, electrical resistance heater242, electrical resistance heater242-1, and first heater246-1. Exemplary process diagram291comprises providing one or more reactive gases297. Exemplary process diagram291further comprises applying heat to the substrate with the at least one heater or heating assembly and creating a Coanda effect gas flow of the one or more reactive gases over the substrate299. The heat may be used to bring the substrate to a process temperature and/or to maintain the substrate at a process temperature for a process. Exemplary process diagram291may also comprise maintaining additional process conditions sufficient to cause the chemical reaction to occur.

As an option, exemplary process diagram291may also include one or more modifications for additional embodiments of the present invention. Exemplary modifications may include, but are not limited to, the following: Rotating the substrate during299. Providing the substrate293comprises providing a semiconductor wafer. Providing the substrate293comprises providing a substrate for fabricating electronic or optoelectronic devices. Providing the substrate293comprises providing a silicon wafer. Providing the one or more reactive gases297comprises providing one or more precursors for semiconductor deposition. Providing the one or more reactive gases297comprises providing a silicon precursor. Providing the one or more reactive gases297comprises providing a compound selected from the group consisting of silane, dichlorosilane, trichlorosilane, and silicon tetrachloride. Providing the one or more reactive gases297comprises providing a dopant compound for a semiconductor. Providing the one or more reactive gases297comprises providing one or more precursors for deposition of Group IV element semiconductors, Group IV element compound semiconductors, Group III-V element semiconductors, or Group II-VI element semiconductors. Creating the Coanda effect gas flow of the one or more reactive gases over the substrate299while maintaining conditions sufficient to cause the chemical reaction to occur comprises conditions for deposition of epitaxial silicon. Creating the Coanda effect gas flow of the one or more reactive gases over the substrate299while maintaining conditions sufficient to cause the chemical reaction to occur comprises conditions for deposition of an epitaxial layer of materials such as, but not limited to, cadmium telluride, cadmium mercury telluride, gallium arsenide, gallium nitride, indium antimonide, indium phosphide, silicon, silicon germanium, and silicon carbide.

Clearly, embodiments of the present invention can be used for a wide variety of processes such as those for semiconductor device fabrication. Changes in the selected process gases and process conditions allow embodiments of the present invention to include substrate processes such as deposition processes for epitaxial layers, polycrystalline layers, nanocrystalline layers, or amorphous layers; processes such as substrate etching or cleaning; substrate oxidation; and/or substrate doping.

Embodiments of the present invention also include methods and apparatus for growing layers of materials such as elemental materials, compounds, compound semiconductors, and compound dielectric materials. In preferred embodiments for compound semiconductor applications, at least one of the Coanda effect gas injectors is connected so as to provide a flow of a gas comprising at least one of the elements boron, aluminum, gallium, indium, carbon, silicon, germanium, tin, lead, nitrogen, phosphorus, arsenic, antimony, sulfur, selenium, tellurium, mercury, cadmium, and zinc. Optionally, one or more Coanda effect gas injectors and/or one or more secondary gas injectors is connected so as to provide a flow of a gas or gas mixture such as hydrogen; an inert gas; hydrogen mixed with a dopant; or an inert gas mixed with a dopant.

Methods according to embodiments of the present invention may include the use of a variety of process gases such as those described above. The gases used for the method will depend on the process. In one embodiment, the gas flow streams comprise silicon source gas, dopant gas, and hydrogen.

Presented next is an exemplary procedure that may be used to design a heater according to one embodiment of the present invention. The heater for this design is similar in configuration to the ring heater shown inFIG. 1. Input data used for the heater include the following: inside radius: 2.75 inches; outside radius: 4.85 inches; spacing between facing side surfaces: 0.060 inch; heater material: molded graphite having a resistivity of about 0.00049 ohm inch; heater angular size: substantially 360°; number of spokes:101; angular width of spoke+spacing: 3.545 degrees; segment length: 0.21 inch; and initial trial thickness: 0.135 inch. The input data for this example is used with Equation (1) and Equation (2) to calculate the heating element cross-section width and the heating element cross-section thickness at radial positions incrementally increasing by an amount equal to the segment length so as to provide calculations ranging from the inside radius to the outside radius of the heater. The calculations are shown in Table 1. For this example are in, the calculations are performed at11equally spaced radial positions along one of the spokes including the inside radius and the outside radius.

Additional related calculations are also shown in Table 1 such as cross-section area of the heating element as a function of radial position and the resistance for each of the segmented lengths. The resistance for the segment lengths are totaled to give the total resistance for the spoke and multiplied by the number of spokes to determine the total resistance for the heating element. These calculations also aid in showing a possible approach a designer can use to modify the design of the heater so that it more closely matches a desired or optimum utilization of the power source capability. Specifically, a designer can select a different initial trial thickness and repeat the calculations to obtain the total resistance for the heating element for comparison with the desired or optimum resistance for use with a power supply. This iteration process can be continued until the total resistance for the heating element is an optimum or desired match of resistance for use with the power source.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims.

While there have been described and illustrated specific embodiments of the invention, it will be clear that variations in the details of the embodiments specifically illustrated and described may be made without departing from the true spirit and scope of the invention as defined in the appended claims and their legal equivalents.