SYSTEM AND METHOD FOR SELECTIVE ETCHING OF AMORPHOUS SILICON OVER EPITAXIAL SILICON AT LOW SUBSTRATE TEMPERATURE

Disclosed herein are a processing chamber, a radical generation cartridge, and a method for etching amorphous silicon selectively relative to crystalline silicon. In one example, the selective silicon etching process is performed in an epitaxy processing chamber. In an example, a processing chamber is provided that includes a chamber body, a transparent dome, a susceptor, a heat source, and a first hot wire filament. The transparent dome is disposed on the chamber body and with the body, partially enclosing a processing volume. The susceptor is disposed in the processing volume. The heat source is positioned to direct radiant energy through the transparent dome toward the susceptor. The first hot wire filament is disposed in a first gas inlet formed through the chamber body. The first hot wire filament is configured to generate radicals from gas flowing through the first gas inlet into the processing volume of the processing chamber.

BACKGROUND

Field

The present disclosure relates to components and epitaxial system that includes a filament for dissociating process gases, and more specifically to system and method for selectively etching amorphous silicon (a-Si) over epitaxial silicon (Si) and other materials at a low substrate temperature using disassociated hydrogen.

Description of the Related Art

Epitaxy refers to processes used to grow a thin crystalline layer on a crystalline substrate (epi layer). Epitaxy is a method of vapor deposition and type of semiconductor manufacturing used to form devices on silicon wafers. The epi layer on a semiconductor substrate can improve the electrical characteristics of the surface and make the substrate and the surface suitable for highly complex microprocessors and memory devices.

Selectively etching amorphous silicon (a-Si) over crystalline silicon (c-Si) is a method used in growth of epitaxial layers for forming semiconductor devices on silicon wafers. High temperatures can damage materials in Epi chambers, including the underlying layers of the substrate. Low temperature dry etching is preferred in order to reduce thermal damage to the substrate, reduce processing times, and reduce the overall cost of processing. Selectively etching of a-Si at temperatures lower than 500° C. is important in processing and fabricating advanced logic devices and integrated circuits in an Epi chamber. Conventional Epi chambers often use chlorine (Cl) based Si etchants, however, dry etching of a-Si can also be achieved using atomic hydrogen. However, atomic hydrogen recombines quickly and state of the art Epi chambers are currently not configured for effective use of hydrogen as an etchant.

Thus, a need exists for an improved substrate processing system for selectively etching a-Si at low temperatures.

SUMMARY

Disclosed herein are a processing chamber, a radical generation cartridge, and a method for etching amorphous silicon selectively relative to crystalline silicon. In one example, the selective silicon etching process is performed in an epitaxy processing chamber. In an example, a processing chamber is provided that includes a chamber body, a transparent dome, a susceptor, a heat source, and a first hot wire filament. The transparent dome is disposed on the chamber body and with the body, partially enclosing a processing volume. The susceptor is disposed in the processing volume. The heat source is positioned to direct radiant energy through the transparent dome toward the susceptor. The first hot wire filament is disposed in a first gas inlet formed through the chamber body. The first hot wire filament is configured to generate radicals from gas flowing through the first gas inlet into the processing volume of the processing chamber.

In some examples, the first hot wire filament is disposed a first cartridge that is replaceably insertable into the first gas inlet of the chamber body. The first cartridge may include gas port coupled to a gas channel. The gas port is exposed to an exterior of the chamber body, while the gas channel configured to direct the gas flowing through first gas port across the first hot wire filament and into the processing volume.

In some examples, the first cartridge includes a first electrical connector electrically coupled to the first hot wire filament. The first electrical connector is also exposed to the exterior of the chamber body.

In some examples, a first primary gas port formed through the chamber body. The first primary gas port is disposed at a distance relative to the dome that is different a distance that the first gas inlet is disposed from the dome. The first primary gas port and the first gas inlet may be coupled to different gas sources or to a common gas source.

In yet another example, a processing chamber is provided that includes a chamber body, a transparent dome, a susceptor, a heat source, and a hot wire filament array. The transparent dome is disposed on the chamber body and with the body, partially enclosing a processing volume. The susceptor is disposed in the processing volume. The heat source is positioned to direct radiant energy through the transparent dome toward the susceptor. The hot wire filament array is disposed within the processing volume between the susceptor and the dome. The first hot wire filament is configured to heat gas flowing from the first gas inlet within the processing volume of the processing chamber.

In some examples, the hot wire filament array has an orientation substantially parallel to an orientation of the susceptor.

In some examples, the hot wire filament array includes wires arranged in a grid.

In some examples, the hot wire filament array and the first gas inlet are spaced at a common elevation relative to a top surface of the chamber body.

In some examples, a first primary gas port is formed through the chamber body at a distance relative to the dome that is different a distance that the first gas inlet is disposed from the dome.

In some examples, the first primary gas port and the first gas inlet are coupled to different gas sources.

In some examples, the first primary gas port and the first gas inlet are coupled to a common gas source, wherein a ratio of gas provided to the first primary gas port and the first gas inlet is controllable.

In still another example, a method for selectively etching a substrate is provided that includes directing radiant energy through a transparent dome to a substrate disposed on a susceptor disposed in a processing volume defined in a processing chamber; maintaining a temperature of the substrate disposed on the susceptor below 500 degrees Celsius; creating hydrogen radicals from a hydrogen containing gas flowing across one or more hot wire filaments; and selectively etching a-Si relative to c-Si disposed on the substrate within the processing volume using the hydrogen radicals.

In some examples, creating hydrogen radicals further includes forming creating hydrogen radicals within a cartridge coupled to a sidewall of the processing chamber.

In some examples, creating hydrogen radicals further includes forming creating hydrogen radicals above the susceptor within the processing volume.

In some examples, the method further includes flowing a gas used to create the hydrogen radicals and a main processing gas into the processing chamber from inlets disposed at different elevations relative to the susceptor.

DETAILED DESCRIPTION

Disclosed herein are a processing chamber, a radical generation cartridge, and a method for dry etching amorphous silicon selectively relative to crystalline silicon. The apparatus and method both utilize atomic hydrogen radicals as an etchant generated using a hot-wire filament disposed in the gas inlet, or the interior of an Epi chamber, or other suitable processing chamber. For some substrate manufacturing processes, performing an etch process within an Epi chamber is desirable due to ability to precisely control substrate temperatures via radiant heating, and/or the ability to also perform epitaxial processes in-situ the same processing chamber. In one example, a hydrogen containing gas is exposed to a hot wire filament, with the filament dissociating the hydrogen from the molecular gas into atomic hydrogen. The atomic hydrogen is then used to etch a-Si selectively over c-Si. The method and apparatus advantageously enables molecular hydrogen to be dissociated into atomic hydrogen very close to the substrate, thus reducing recombination. Moreover, the hot wire filament does not substantially heat the substrate, all allowing low temperature (e.g., temperatures less than 500 degrees Celsius) to be maintaining in the Epi chamber.

When a semiconductor substrate is heated in the Epi chamber during a substrate processing, maintaining uniform temperatures across the surface of a semiconductor substrate can be challenging. Temperature is an important factor impacting deposition rate, crystal structure, and doping, and this a large temperature gradient can cause the Epi layer to have relatively large variations in terms of thickness and electrical resistivity throughout the substrate, or cause thermal damage to underlying layers. Dry etching of a-Si at a low temperature can be achieved using atomic hydrogen to break Si—Si bonds. The atomic hydrogen radicals etches a-Si faster than c-Si, that is the atomic hydrogen is selective to a-Si over c-Si. Further, boron doping can be used to decrease the etch rate of c-Si relative to the etch rate of a-Si. Thus, Si etching can be also selectively controlled using boron dopant.

According to an embodiment of the present application, a hot wire filament is configured disposed in a gas inlet. For example, the hot wire filament may be disposed in a replaceable cartridge inserted into the gas inlet.

In other examples, the hot wire filament may be part of a hot wire filament array. The hot wire filament array is disposed within the Epi chamber, affixed to the main body of the chamber above the susceptor. A carrier gas containing at least molecular hydrogen is flowed into the chamber such that the molecular hydrogen comes into contact with the filament array disposed in the Epi chamber.

According to a general aspect of the present application, a carrier gas mixed with a hydrogen containing gas is injected into the Epi chamber via a gas inlet. The hydrogen containing gas may be molecular hydrogen (H2) or other suitable hydrogen source gas. The molecular hydrogen (H2) is flowed across the filament according to the various embodiments disclosed herein and heated to a temperature sufficient to dissociate the molecular hydrogen (H2) into atomic hydrogen (e.g., hydrogen radicals), but without significantly increasing the ambient temperature of the Epi chamber or the substrate. The atomic hydrogen is then used to processes the substrate by selectively etching the amorphous silicon a-Si over the crystalline silicon c-Si, without affecting the materials inside of the Epi chamber such as metals, quartz, and oxides, or exceeding the thermal budget of the device being formed on the substrate.

Turning now toFIG.1,FIG.1illustrates a schematic top view of a processing system100, according to one or more embodiments. The processing system100includes one or more load lock chambers122(two are shown inFIG.1), a processing platform104, a factory interface102, and a controller144. In one or more embodiments, the processing system100is a CENTURA® integrated processing system, commercially available from Applied Materials, Inc., located in Santa Clara, California. It is contemplated that other processing systems (including those from other manufacturers) may be adapted to benefit from the disclosure.

The platform104includes a plurality of processing chambers110,112,120,128, and the one or more load lock chambers122that are coupled to a transfer chamber136. The transfer chamber136can be maintained under vacuum, or can be maintained at an ambient (e.g., atmospheric) pressure. Two load lock chambers122are shown inFIG.1. The factory interface102is coupled to the transfer chamber136through the load lock chambers122.

In one or more embodiments, the factory interface102includes at least one docking station109and at least one factory interface robot114to facilitate the transfer of substrates. The docking station109is configured to accept one or more front opening unified pods (FOUPs). Two FOUPS106A,106B are shown in the implementation ofFIG.1. The factory interface robot114having a blade116disposed on one end of the robot114is configured to transfer one or more substrates from the FOUPS106A,106B, through the load lock chambers122, to the processing platform104for processing. Substrates being transferred can be stored at least temporarily in the load lock chambers122.

Each of the load lock chambers122has a first port interfacing with the factory interface102and a second port interfacing with the transfer chamber136. The load lock chambers122are coupled to a pressure control system (not shown) which pumps down and vents the load lock chambers122to facilitate passing the substrates between the environment (e.g., vacuum environment or ambient environment, such as atmospheric environment) of the transfer chamber136and a substantially ambient (e.g., atmospheric) environment of the factory interface102.

The transfer chamber136has a vacuum robot130disposed therein. The vacuum robot130has one or more blades134(two are shown inFIG.1) capable of transferring the substrates124between the load lock chambers122and the processing chambers110,112,120,128.

The controller144is coupled to the processing system100and is used to control processes and methods, such as the operations of the methods described herein (for example the operations of the method1000and/or the method1050described below). The controller144includes a central processing unit (CPU)138, a memory140containing instructions, and support circuits142for the CPU. The controller144controls various items directly, or via other computers and/or controllers.

FIG.2illustrates a schematic cross-sectional view of an Epi processing chamber200according to an embodiment. The Epi processing chamber200is a deposition chamber to grow an Epi layer on a substrate202. The processing chamber200represents one or more of the processing chambers110,112,128shown inFIG.1. In one or more embodiments, a processing chamber120conducts processing (such as pre-cleaning or etching) at a temperature (such as an ambient temperature, for example a room temperature) that is lower than a processing temperature used in the processing chamber200. A controller144is in communication with the processing chamber200and is used to control processes performed in, and function of, the processing chamber200. The controller144may be the same or different than the controller144illustrated inFIG.1.

The processing chamber200includes an upper body256, a lower body248disposed below the upper body256, and a chamber body212disposed between the upper body256and the lower body248. An upper window208(such as an upper dome) and a lower window210(such as a lower dome) are disposed on the upper and lower surfaces of the chamber body212to enclose a processing volume204. The windows208,210are generally substantially transparent to radiant energy. A susceptor203is disposed in the processing volume204and configured to support a substrate202thereon during processing.

A plurality of upper heat sources241are disposed in the upper body256above the upper window208and below a lid254enclosing the upper body256. The plurality of upper heat sources241are configured to direct radiant energy through the upper window208toward the susceptor203and a top surface250of the substrate202disposed thereon. Similarly, a plurality of lower heat sources243are disposed below the lower window210. The plurality of lower heat sources243are configured to direct radiant energy through the lower window210toward the bottom of the susceptor203.

According to an embodiment, the heat sources241,243are lamps that are capable of generating infrared radiation. Other heat sources that are capable of generating infrared radiation are contemplated, such as resistive heaters, light emitting diodes (LEDs), and/or lasers.

The plurality of lower heat sources243are disposed between the lower window210and a chamber floor252. The plurality of lower heat sources243form a portion of a lower heating module245. The upper window208is an upper dome and is formed at least partially of an energy transmissive material, such as quartz. The lower window210is a lower dome and is formed at least partially of an energy transmissive material, such as quartz.

The processing chamber200includes one or more thermal sensors271configured to detect a thermal condition of the processing chamber200. In one or more embodiments, the one or more thermal sensors271may include one or more cameras, one or more pyrometers, one or more thermoelectric sensors, and/or one or more thermal labels. The one or more thermal sensors271can be mounted, for example, below the lower window210(as shown inFIG.2), or above the upper window208(such as on or in the lid254), or any other suitable place in the processing chamber200. According to an embodiment, a pyrometer is mounted below the lower window210and is configured to remotely measure temperature of the substrate202during the growth process of an Epi layer or during etching.

The susceptor203is support in the processing chamber by a plurality of arms239coupled to an inner shaft218. The inner shaft218is coupled to a motion assembly221includes one or more actuators and/or motors that provide vertical and/or rotational movement of the inner shaft218, which, in turn, moves susceptor203and the substrate202disposed thereon. Lift pin holes207are formed through the susceptor203and are each sized to accommodate lift pins232that is used to lift the substrate202during substrate transfer into and out of the chamber body212through a slit valve not shown inFIG.1. An outer shaft235surrounds a portion of the inner shaft218. The outer shaft235has a plurality of arms239, each arm239terminating at a lift pins stop234. The relative elevation of the outer shaft235and inner shaft218may be changed to cause the lift pins stop234to displace the lift pins232through the susceptor203, thus lifting the substrate202above the susceptor203to allow access by a robot blade (not shown) that moves the substrate202into and out of the processing chamber200.

The chamber body212includes a plurality of gas inlets214, a plurality of purge gas inlets264, and one or more gas exhaust outlets216. The plurality of gas inlets214are generally aligned at a common elevation within the processing chamber200, for example at a common distance from a top surface of the chamber body212. The gas inlets214are connected with a plurality of process gas sources251,253and provides a cross-flow of processing gases across the top surface250of the substrate202. In some embodiments of the present application, some or all of the gas inlets214includes a hot wire filament205. The process gas source251generally provides a hydrogen containing gas, such as H2and the like. The process gases supplied using the plurality of process gas sources251,253can include one or more reactive gases (such as one or more of silicon (Si), phosphorus (P), and/or germanium (Ge)) and/or one or more carrier gases (such as one or more of nitrogen (N2) and/or hydrogen (H2)). The process gas source251may alternatively provide another type of gas disassociatable by a hot wire filament. The process gas source253generally provides processing gas and/or a carrier gas. The processing gas provided by the process gas source253may be the same as or different than the process gas provided by the process gas source251. In one example, the carrier gas provided by the process gas source253is mixed with processing gas provided by the process gas source251prior to delivery to the gas inlets214. The purge gas inlets264are connected with a purge gas source262and provide purge gas to the EPI processing chamber200. The one or more purge gases supplied using the one or more purge gas sources262can include one or more inert gases (such as one or more of argon (Ar), helium (He), and/or nitrogen (N2)). In one or more embodiments, the process gases may include silicon phosphide (SiP) and/or phosphine (PH3).

The plurality of gas inlets214and the plurality of purge gas inlets264are disposed on the opposite side of the chamber body212from the one or more gas exhaust outlets216. In one example, the plurality of gas inlets214are disposed at an elevation above the susceptor203. The one or more gas exhaust outlets216are connected an exhaust conduit278. The exhaust conduit278fluidly connects the one or more gas exhaust outlets216formed through the chamber body212to an exhaust pump257that evacuates the processing volume204and gases flowing into the processing volume204from at least the gas inlets214.

The hot wire filament205is generally disposed in a location within the gas inlet214where gas flowing through the inlet may be disassociated prior to entering the processing volume204. To better prevent recombination of the disassociated processing gases, the hot wire filament205may be preferentially located closer to the processing volume204than an exterior of the chamber body212. The hot wire filament205is coupled to a power source209that controls the power provided to the filament205.

In one example, power is provided from the power source209to heat the hot wire filament205to temperatures greater than 1500° C. in order to dissociate molecular hydrogen into atomic hydrogen. For example, the hot wire filament205may be heated to between 1500° C. to 2400° C. In an exemplary embodiment, the hot wire filament205is heated to 1850° C. The hot wire filament205can be made of materials such as tungsten (W) or carbon (C). The hot wire filament205may be subjected to a range of materials which may be corrosive. In some embodiments, the hot wire filament205is coated with corrosive resistant materials. Some examples of corrosive resistant materials that may be used to coat the hot wire filament205include boron nitride (BN) or silicon dioxide (SiO2), among others. The hot wire filament205has a sufficiently thin diameter dissociate molecular hydrogen into atomic hydrogen without deferentially impacting the temperature of the substrate202and/or processing chamber200. The hot wire filament205may have a diameter in a range of about 100 μm to about 2.5 mm. In an exemplary embodiment, the hot wire filament205has a diameter of about 250 μm. The hot wire filament205may also be made of other materials sufficient to meet the required conditions described herein. The hot wire filament205may also be coated with a range of other corrosive resistant materials not specifically disclosed herein.

The hot wire filament205may also be used to dissociate precursor molecules for the growth of Epi Si and silicon-germanium (SiGe) based materials. In some embodiments, precursor molecules can include SiH4, Si2H6, Si2H2Cl2, or other high order silane and germane precursors.

Alternatively, or in addition to the hot wire filaments205disposed in the gas inlets214, a hot wire filament array255comprised of a plurality of hot wire filament205may be disposed in the processing volume204between the susceptor203and the upper window208. The hot wire filament array255may be secured by a frame (shown inFIGS.4and5) to the chamber body212, or other portion of the processing chamber200. In one example, the hot wire filament array255may be between 15 mm to 30 mm or more above the susceptor203.

The hot wire filament array255may be centered within the processing chamber200, or disposed closer to the inlet ports214relative to the one or more gas exhaust outlets216to reduce the potential for recombination of radicals produced by the hot wire filaments205of the hot wire filament array255. The hot wire filaments205of the hot wire filament array255are also coupled to the power source209. The hot wire filaments205of the hot wire filament array255may be arranged in a grid, such as in rows and columns, or other suitable arrangement. In another example, some or all of the hot wire filaments205of the hot wire filament array255are arranged at a non-zero angle (i.e., are not parallel) to a flow direction within the chamber volume defined between the gas inlet214and the exhaust outlets216, which in one example is 90 degrees.

FIG.3illustrates a schematic cross-sectional view of a portion of the chamber body212, according to an embodiment of the present application. The chamber body212has a ring shape with an inner wall312exposed to the processing volume204, and an outer wall310exposed to the exterior of the chamber body212. The gas inlet214is formed through the chamber body212exiting the walls310,312.

A hot wire filament cartridge300is disposed in the gas inlet214. The hot wire filament cartridge300may be secured to the chamber body212via clamps, fasteners or other suitable technique. In the example depicted inFIG.3, the cartridge300includes a male threaded portion304that engages a female threaded portion302of the gas inlet214.

The cartridge300includes an elongated portion306and a head308. The head308abuts the outer wall310of the chamber body212when the cartridge300is fully installed in the chamber body212. An o-ring or other gasket (not shown) may be disposed between the cartridge300and the chamber body212to provide a vacuum seal therebetween.

A central passage314extends through the elongated portion306and the head308of the cartridge300. One end of the central passage314is open to the processing volume204. The other end of the central passage314has a port316. The port316is configured to accept a fitting318that coupled the cartridge300via a conduit326to one or both of the gas sources251,253. In this manner, gas from one or both of the gas sources251,253may be delivered through the passage314into the processing volume204.

The hot wire filament205is disposed in the passage314of the cartridge300. The hot wire filament205is connected to an electrical connector320that is also connected to the cartridge300. The electrical connector320, such as a socket or banana plug, is configured to receive a complimentary mating electrical connector322. The electrical connector322is connect by one or more leads324to the power source209. Thus, the power source209is able to power of the hot wire filament205disposed in the passage314of the cartridge300.

As the gas flows through the passage314of the cartridge300, the hot wire filament205is operable to disassociate at least some of the gases flowing into the processing volume204through the cartridge300. In one example, a hydrogen containing gas, such as H2, is flowed over the hot wire filament205disposed in the cartridge300such that hydrogen radicals are introduced into the processing volume204. As depicted inFIG.3, the hot wire filament205is disposed closer to the inter wall312than the outer wall310to reduce the probability of recombination of the disassociated hydrogen radicals prior to reaching the substrate202.

As the fitting318and connector322allow the cartridge300to be easily disconnected from the sources209,251,253, the cartridge300can be readily replaced.

FIG.4illustrates a schematic cross-sectional a portion of the chamber body212, according to another embodiment of the present application. The chamber body212illustrated inFIG.4may be utilized in place of the chamber body212illustrated inFIG.3as part of the processing chamber200ofFIG.2. The chamber body212ofFIG.4is essentially the same as the chamber body212illustrated inFIG.3except that the gas sources251,253are coupled to the processing volume204not only through the gas inlet214formed through the chamber body212, but additionally through one or more primary gas ports400formed through the chamber body212. The primary gas port400disposed at a distance relative to the upper window208and the susceptor203that is different a distance that the gas inlet214is disposed from the upper window208and the susceptor203formed through the chamber body212. In the example depicted inFIG.4, the primary gas port400is farther from the upper window208and closer to the susceptor203than the gas inlet214.

In one example, the gas inlet214is substantially aligned with, i.e., disposed at the elevation, as an optional hot wire filament array255. The hot wire filament array255is secured by a frame455to the chamber body212, in one example, by fasteners456secured to the chamber body212. When the optional hot wire filament array255is utilized, the cartridges300become optional. The cartridges300may disposed in one or both of the primary gas port400and the gas inlet214. When the optional hot wire filament array255is not present, the cartridges300may disposed in one or both of the primary gas port400and the gas inlet214.

In one example, the primary gas port400and the gas inlet214are coupled to the same gas sources251,253. In another example, the primary gas port400is coupled to the processing gas source253, while the gas inlet214is coupled to the processing gas source251such that the hydrogen containing as is directed in contact with the hot wire filament205disposed in the cartridge300and/or the hot wire filament array255.

In some examples, the ratio of gases provided to the primary gas port400and the gas inlet214is different. In one instance, an amount of hydrogen containing gas within processing gas provide to the primary gas port400is greater than an amount of hydrogen containing gas within processing gas provided to the gas inlet214. In another instance, an amount of hydrogen containing gas within processing gas provide to the primary gas port400is less than an amount of hydrogen containing gas within processing gas provided to the gas inlet214.

FIG.5is a schematic cross-sectional view of a portion of a chamber body of the EPI processing chamber ofFIG.2, according to another embodiment of the present application. The chamber body212illustrated inFIG.5may be utilized in place of the chamber body212illustrated inFIG.3as part of the processing chamber200ofFIG.2. The chamber body212ofFIG.5is essentially the same as the chamber body212illustrated inFIG.3except that the hot wire filament205is disposed in the passage514of the cartridge500in gas inlet214and also in the processing volume204.

In some examples the hot wire filament205is one continuous filament from the gas inlet214through the processing volume204. In some examples there are multiple hot wire filaments205disposed in the gas inlet214and in the processing volume204. In yet another example, the hot wire filaments205in the processing volume204comprises a hot wire filament array255. The hot wire filaments205in a hot wire filament array255may be connected together a single wire or to a single power supply node so that the hot wire filaments205of the hot wire filament array255a commonly controlled, for example, by applying the same power/current. Alternatively, the hot wire filament array255may be comprises of a plurality of independently controllable the hot wire filaments205, for example, such that the power/current provided at least two hot wire filaments205is different. A single hot wire filament205disposed in an inlet cartridge may be combined with a hot wire filament array255. In some examples, the hot wire filament is arranged in the manner shown inFIG.6orFIG.7.

FIG.6is partial sectional view of a portion of the hot wire filament array255that can be optionally utilized in the processing chamber ofFIG.2, according to an embodiment of the present application. The frame455has a hoop602that includes a plurality of mounting holes608to through which the fasteners456(shown inFIG.4) pass to secure the hoop602to the chamber body212. A ring-shaped mounting flange604extends radially inward from the hoop602to an inside diameter cylindrical wall616. The mounting flange604includes a plurality of guides606, such as posts or hooks, around which the one or more hot wire filaments205of the hot wire filament array255are routed, thereby securing the hot wire filament array255to the frame255in a predefined pattern.

The one or more hot wire filaments205of the hot wire filament array255terminate at spring contacts610exposed on a cylindrical outer sidewall614of the mounting flange604. The spring contacts610are coupled to the hot wire filaments205via leads612. The spring contacts610may be pads, detent balls, pogo pins or other suitable electrical contacts for connecting the hot wire filaments205of the hot wire filament array255to the power source209through the chamber body212or other portion of the processing chamber200.

FIG.7is partial sectional view of a portion of the hot wire filament array255that can be optionally utilized in the processing chamber ofFIG.2, according to an embodiment of the present application. In the example shown inFIG.7, the hot wire filament array255is comprised of a plurality of hot wire filaments205arranged in parallel lines (alternative to the grid shown inFIG.6). In an example, each of the plurality of hot wire filaments205of the hot wire filament array255is orientated in the same direction. In some examples the direction of the hot wire filament array255is orientated in parallel to the direction of the gas flow through the processing volume204. In other examples, the hot wire filament array255is orientated perpendicular to the direction of the gas flow through the processing volume204. In yet another example, the hot wire filament array255may be orientated at an angle between 0 and 180° with respect to the direction of the gas flow through the processing volume204.

Each of the plurality of hot wire filaments205of the hot wire filament array255may be evenly spaced throughout the processing chamber. In some examples the plurality of hot wire filaments205of the hot wire filament array255may have uneven spacing throughout the processing chamber. For example, the plurality of hot wire filaments205may be more densely space closer to the gas inlet214. In yet another example, the plurality of hot wire filaments205of the hot wire filament array255may be disposed directly over the substrate202. In another example the plurality of hot wire filaments205of the hot wire filament array255may be disposed closer to the gas inlet214. Alternative examples may exist that comprise a combination of one or more of the examples discussed, such as even spacing of the plurality of hot wire filaments205disposed near the gas inlet214, or uneven spacing of the plurality of hot wire filaments205disposed over the substrate202.

The hot wire filaments205of the hot wire filament array255may be mounted in a similar manner to the hot wire filament array255ofFIG.6, via a mounting flange604which includes a plurality of guides, such as posts or hooks, around which the one or more hot wire filaments205of the hot wire filament array255are routed, thereby securing the hot wire filament array255to the frame. Each of the plurality of hot wire filaments205of the hot wire filament array255may alternatively be mounted to the processing chamber via one or more sealing connectors704. The one or more sealing connectors704may connect the plurality of hot wire filaments205to the power source209. In some examples the temperature of each of the plurality of hot wire filaments205of the hot wire filament array255may be individually controllable, for example, by providing more or less current from the power source209. In some examples, one or more of the plurality of hot wire filaments205have the same temperature (or current provided from the power source209) while one or more other hot wire filaments205of the hot wire filament array255have a different temperature (or current provided from the power source209).

The one or more hot wire filaments205of the hot wire filament array255may terminate at spring contacts610exposed on a cylindrical outer sidewall614of the mounting flange604or affixed to the sealing connectors704. The spring contacts610are coupled to the hot wire filaments205via leads612. The spring contacts610may be pads, detent balls, pogo pins or other suitable electrical contacts for connecting the hot wire filaments205of the hot wire filament array255to the power source209through the chamber body212or other portion of the processing chamber200.

FIG.8is a schematic cross-sectional view of a portion of a chamber body of the EPI processing chamber ofFIG.2, according to an embodiment of the present application. More specifically,FIG.8exhibits a cross-sectional view of the connections of the hot wire filament array255described and shown inFIG.7.FIG.8depicts the hot wire filament array255disposed over the substrate202in the processing volume204and extending through the chamber body212. Each hot wire filament205of the hot wire filament array255connects to the leads612connecting to the power source209via the sealing connector704.

FIG.9is a block diagram of a method900for processing a substrate within a processing chamber. The processing chamber may be configured as the processing chamber200described above, or within another suitable processing chamber. The method900is particularly suitable for etching amorphous silicon (a-Si) selectively over crystalline silicon (c-Si) at temperatures below 500 degrees Celsius.

The method900begins at operation902by directing radiant energy through a transparent dome (e.g., upper window) to a substrate disposed on a susceptor disposed in a processing volume defined in a processing chamber. In one example, radiant energy is provided by the heat sources, for example lamps, provide above and/or below the susceptor.

At operation904, a temperature of the substrate disposed on the susceptor is maintained below 500 degrees Celsius. In one example, the temperature sensors are utilized to control power provided to the upper and/or lower heat sources to control the temperature of the substrate.

At operation906, radicals are generated from a process gas flowing across one or more hot wire filaments. In one example, hydrogen radicals are generated from a hydrogen containing gas flowing across the one or more hot wire filaments while maintaining the filament at a temperature be greater than 1500 degrees Celsius, such as between 1500 and 2400 degrees Celsius. The one or more hot wire filaments may be disposed in a gas inlet of the processing chamber and/or within the processing volume of the processing chamber.

At operation908, an etch process is performed in the processing chamber. For example, operation908may etch a-Si selectively relative to c-Si disposed on the substrate within the processing volume using the hydrogen radicals. At operation908, the etch process occurs at temperatures less than 500 degrees Celsius. In other examples, other types of radicals may be utilized to etch material disposed on the substrate other than a-Si.

In some example, creating hydrogen radicals includes forming creating hydrogen radicals within a cartridge coupled to a sidewall of the processing chamber. In other examples, creating hydrogen radicals includes forming creating hydrogen radicals above the susceptor within the processing volume. In other examples, the process gas used to create the hydrogen radicals and a main processing gas are provided to the processing chamber from inlets disposed at different elevations relative to the susceptor. In some examples, the gas used to create the hydrogen radicals and the main processing gas are coupled to different gas sources. In some examples, the gas used to create the hydrogen radicals and the main processing gas are coupled to a common gas source, wherein a ratio of the gas used to create the hydrogen radicals and the main processing gas is controllable by adjusting the flow to one or both of the gas inlet and the main processing gas inlet.

By maintaining the hot wire filament at an appropriate temperature, molecular hydrogen is dissociated into atomic hydrogen without detrimentally heating the substrate above 500 degrees Celsius. Thus, good selectivity of a-Si over c-Si may be obtained throughout the etch process without exceeding the thermal budget of the device being formed or present on the substrate.

Is contemplated that one or more aspects disclosed herein may be combined. Moreover, it is contemplated that one or more aspects disclosed herein may include some or all of the aforementioned benefits. While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.