Optically heated substrate support assembly with removable optical fibers

A substrate support includes a plate comprising a top surface and a bottom surface, wherein the top surface is to support a substrate. The plate further comprises an electrode, one or more resistive heating elements, a first plurality of channels, and a plurality of optical fibers in the first plurality of channels, wherein the plurality of optical fibers are removable from the substrate support.

TECHNICAL FIELD

Embodiments of the present invention relate to an apparatus for controlling substrate temperature using optical heating.

BACKGROUND

Conventional electronic device manufacturing systems may include one or more process chambers. In some electronic device manufacturing systems, the one or more process chambers may be arranged around a mainframe housing having a transfer chamber and one or more load lock chambers. These systems may employ one or more process chambers that may perform a process on a substrate (e.g., a wafer) inserted into the process chamber. Processing may include a chemical vapor deposition (CVD) process, such as plasma-enhanced chemical vapor deposition (PECVD) process, used to deposit a thin film on a substrate or other high-temperature process. During processing, wafers may rest on a pedestal (e.g., a substrate support) and the temperature thereof may be controlled (e.g., heated or cooled) at one or more times during the process. Conventionally, heating may be provided by resistive heaters provided within the pedestal in some embodiments.

It should be recognized, however, that even small variations in temperature across the substrate during such high-temperature processing may cause differential processing (e.g., possibly uneven deposition).

SUMMARY

In one aspect, a substrate support includes a plate comprising a top surface and a bottom surface, wherein the top surface is to support a substrate. The plate further comprises an electrode, one or more resistive heating elements, a first plurality of channels, and a plurality of optical fibers in the first plurality of channels, wherein the plurality of optical fibers are removable from the substrate support.

In another aspect, a substrate support assembly includes a ceramic plate comprising a top surface and a bottom surface, wherein the top surface is to support a substrate, the ceramic plate further comprising a first plurality of channels for receiving a plurality of optical fibers. The substrate support assembly further includes a ceramic shaft bonded to the bottom surface of the ceramic plate, the ceramic shaft comprising a cavity. The substrate support assembly further includes a fiber guide inserted into the cavity of the ceramic shaft, the fiber guide comprising a second plurality of channels, wherein a second channel of the second plurality of channels is to guide a first optical fiber of the plurality of optical fibers into a first channel of the first plurality of channels.

In another aspect, a substrate support assembly includes a ceramic plate comprising a top surface and a bottom surface, wherein the top surface is to support a substrate, the ceramic plate further comprising a first plurality of channels for receiving a plurality of optical fibers. The substrate support assembly further includes a ceramic shaft bonded to the bottom surface of the ceramic plate, the ceramic shaft comprising a cavity and a second plurality of channels, wherein a second channel of the second plurality of channels is to guide a first optical fiber of the plurality of optical fibers into a first channel of the first plurality of channels.

In another aspect, a method of refurbishing an electrostatic chuck includes identifying a faulty optical fiber in the electrostatic chuck comprising a plurality of removable optical fibers, wherein each of the plurality of removable optical fibers is inside of one of a first plurality of channels in the electrostatic chuck. The method further includes removing the faulty optical fiber from a first channel of the first plurality of channels in the electrostatic chuck, wherein the first channel is substantially parallel to a top surface of the electrostatic chuck. The method further includes inserting a new optical fiber into the first channel in the electrostatic chuck.

Numerous other aspects are provided in accordance with these and other embodiments of the invention. Other features and aspects of embodiments of the present invention will become more fully apparent from the following description, the appended claims, and the accompanying drawings.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention provide a substrate support assembly and an electrostatic chuck that include channels for retaining removable optical fibers. The optical fibers may be used to deliver heat energy by way of photons that impinge on a ceramic material and/or on metal containing inserts in the electrostatic chuck.

Within electronic device manufacturing systems adapted to process substrates at high temperature, very precise temperature control may be beneficial. In some electronic device manufacturing systems, such as PECVD systems, the systems are configured and adapted to operate at operating temperatures above 500° C., at above 600° C., and even as high as 650° C. may be beneficial. Additionally, high temperatures may also be desirable in other semiconductor device manufacturing systems, such as etch systems, furnaces, and so on. Various methods have been employed that utilize zoned resistive heating to accomplish temperature control.

According to one or more embodiments of the invention, electronic device processing systems include a substrate support assemblies adapted to provide improved substrate temperature control during high temperature processing are provided. The apparatus, systems, and methods described herein may provide improved temperature control by providing a temperature-controlled platform such as an electrostatic chuck adapted to thermally control a temperature of a substrate at high temperature, such as above 200° C., above 500° C., and even at about 650° C. The temperature-controlled platform may also be used at lower temperatures, such as at temperatures between 120 to 200° C.

In some embodiments, the substrate support assembly may include a substrate support such as an electrostatic chuck. The electrostatic chuck may include a ceramic plate that acts as a temperature-controlled platform. The substrate support assembly additionally includes a ceramic shaft that has been bonded (e.g., diffusion bonded) to a bottom surface of the ceramic plate. Additionally, the substrate support assembly may include a fiber guide inserted into a cavity in the ceramic shaft. Multiple optical fibers may be routed through channels formed in the fiber guide and into additional channels formed in the ceramic plate. The optical fibers enter individually or in one or more bundles through first channels in the fiber guide and extend (e.g., horizontally or at an angle) within second channels in the ceramic plate and terminate at multiple target locations within the ceramic plate. The multiple optical fibers may be used to provide individually-controllable pixelated heat sources, or optionally, the pixelated sources may be zonally controlled. The optical fiber heating may be used alone as a primary heat source, or as a supplement to other forms of temperature control, such as resistive heating. Including optical fiber heating may provide improved range and flexibility of temperature tuning.

The optical fibers may be inserted into the substrate support during forming or during assembly after the substrate support assembly has been formed. Any of the optical fibers may then later be removed from the substrate support individually or in bundles. New optical fibers may then be inserted into channels into which the removed optical fibers had been located. As optical fibers fail those failed optical fibers may be replaced. Accordingly, the substrate support assembly may be refurbished by replacing one or more failed optical fibers.

Further details of example substrate support assemblies and electrostatic chucks including channel-routed optical fiber heating, electronic device processing systems, and methods are described with reference toFIGS. 1-9herein.

Embodiments are described herein with reference to a substrate support assembly that includes a ceramic plate and a ceramic shaft bonded to the ceramic plate. However, in alternative embodiments a metal plate may be used instead of a ceramic plate. Additionally, in some embodiments a metal shaft may be used instead of a ceramic shaft. The metal plate and/or metal shaft may be, for example, aluminum or stainless steel. Accordingly, embodiments may include a ceramic plate bonded to a ceramic shaft, a ceramic plate bonded to a metal shaft, a metal plate bonded to a metal shaft, or a ceramic plate bonded to a metal shaft. If a metal plate and/or metal shaft are used, then the plate may be bonded to the shaft, for example, by brazing. It should be understood that all embodiments describing a ceramic plate herein may be modified to instead include a metal plate. It should additionally be understood that all embodiments describing a ceramic shaft herein may be modified to instead include a metal shaft.

FIG. 1illustrates a schematic top view diagram of an example embodiment of an electronic device processing system100including optical fiber heating according to one or more embodiments of the present invention. The electronic device processing system100may include a housing101having walls defining a transfer chamber102. Walls may include side walls, floor, and ceiling, for example. A robot103(shown as a dotted circle) may be at least partially housed within the transfer chamber102. The robot103may be configured and adapted to place or extract substrates to and from various destinations via operation of moveable arms of the robot103. “Substrates” as used herein shall mean articles used to make electronic devices or electrical circuit components, such as silicon-containing wafers or articles, patterned or masked silicon wafers or articles, or the like. However, the apparatus, systems, and methods described herein may have broad utility wherever high-temperature control of a substrate is beneficial. Embodiments of the invention may be useful for controlled high-temperature heating, such as above 200° C., above 500° C., about 650° C., or even higher temperatures.

Robot103, in the depicted embodiment, may be any suitable type of robot adapted to service the various chambers that are coupled to, and accessible from, the transfer chamber102. Robot103may be a selective compliance assembly robot arm (SCARA) robot or other suitable robot type.

The motion of the various arms of the robot103may be controlled by suitable commands to a drive assembly (not shown) containing a plurality of drive motors from a robot controller104. Signals from the robot controller104may cause motion of the various components of the robot103to cause movement of substrates between the process chambers106A-106C and one or more load lock chambers110C. Suitable feedback mechanisms may be provided for one or more of the components by various sensors, such as position encoders, or the like. The robot103may include a base that is adapted to be attached to a wall (e.g., a floor or ceiling) of the housing101. Arms of the robot103may be adapted to be moveable in an X-Y plane (as shown) relative to the housing101. Any suitable number of arm components and end effectors (sometimes referred to as “blades”) adapted to carry the substrates may be used.

Additionally, the drive assembly of the robot103may include Z-axis motion capability in some embodiments. In particular, vertical motion of the arms along the vertical direction (into and out of the paper inFIG. 1) may be provided so as to place and pick substrates to and from the process chambers106A-106C and the one or more load lock chambers110C.

In the depicted embodiment, transfer chamber102may have one or more process chambers106A-106C coupled to and accessible therefrom, at least some of which are adapted to carry out high-temperature processing on the substrates inserted therein. The process chambers106A-106C may be coupled to facets of the housing101, and each process chamber106A-106C may be configured and operable to carry out a suitable process (e.g. a PECVD process or etch process) on the substrates. It should be understood that the substrate support assembly130including channel-routed optical fiber heating described herein may have utility for other processes taking place at high temperature, such as physical vapor deposition and ion implant, or the like. In particular, one or more of the processes taking place in the process chambers106A-106C may include temperature control via channel-routed optical fiber heating in accordance with an aspect of the invention.

Within the electronic device processing system100, substrates may be received from a factory interface108, and also exit the transfer chamber102into the factory interface108through load lock chamber110C of a load lock apparatus110. The factory interface108may be any enclosure having wall surfaces forming the factory interface chamber108C. One or more load ports112may be provided on some surfaces of the factory interface108and may be configured and adapted to receive (e.g., dock) one or more substrate carriers114(e.g., front opening unified pods—FOUPs) such as at a front surface thereof.

Factory interface108may include a suitable load/unload robot116(shown dotted) of conventional construction within a factory interface chamber108C. The load/unload robot116may be configured and operational to extract substrates from the interior of the one or more substrate carriers114and feed the substrates into the one or more load lock chambers110C of load lock apparatus110.

In accordance with one or more embodiments of the invention, a substrate support assembly130that includes a substrate support (e.g., an electrostatic chuck) may be provided in one or more of the process chambers106A-106C. As will be apparent from the following, channel-routed optical fiber heating adapted to provide light-based heating of a substrate may be provided by the substrate support assembly130. The description herein will focus on providing the substrate support assembly130in process chamber106B. However, an identical substrate support assembly130may be included in one or both of the other process chambers106A,106B. In some embodiments, the substrate support assembly130may be included in all process chambers106A-106C. More or less numbers of process chambers including the substrate support assembly130may be provided.

Referring now toFIGS. 1 and 2, in some embodiments, a temperature unit122that may be coupled to one or more thermal elements242(e.g., resistive heating elements) may be used in conjunction with channel-routed optical fiber heating provided by the substrate support assembly130to control a temperature of one or more portions of a substrate240to a target temperature. The thermal elements (resistive heating elements)242may provide a first level of temperature control of a substrate support (e.g., of a ceramic plate or electrostatic chuck) and the optical fibers may provide a second level of temperature control of the substrate support (e.g., of the ceramic plate or electrostatic chuck).

At a system level, the temperature control may be provided, in the depicted embodiment, by a substrate temperature control system120. Substrate temperature control system120may be a subpart of the electronic device processing system100. Substrate temperature control system120may include the temperature unit122that may couple and provide power to the thermal elements242(e.g., metal resistive heating elements or traces) and which may constitute a primary source of temperature control (e.g., heating) to one or more of the chambers (e.g., process chambers106A,106B,106C).

An optical heating system124may operate as a supplemental heating system in conjunction with the temperature unit122and thermal elements242in some embodiments. In other embodiments, the optical heating system124may be the sole heating system adapted to heat the substrates240within the one or more process chambers106A-106C.

Optical heating system124may include a light source array125coupled (e.g., optically coupled) to the substrate support assembly130, and an optical controller126. Substrate temperature control system120may include a temperature controller128operational to control temperature of the substrate240that is being temperature controlled within the chamber (e.g., process chamber106B). Temperature controller128may be operational to control the temperature unit122and may interface with the optical controller126in some embodiments. Thus, the temperature controller128may be used to communicate with the optical controller126and the temperature unit122to control a temperature of the substrate240in thermal contact with the substrate support assembly130. Suitable temperature feedback may be provided from one or more locations. In some embodiments, the temperature controller128and/or the optical controller126may receive temperature feedback from optical sensors inserted into the substrate support assembly130, as will be explained further herein.

Now referring toFIGS. 2 and 3, the substrate support assembly130, which is included in optical heating system124, is described in more detail. Optical heating system124may include a substrate support assembly130, which may include a platform (e.g., an electrostatic chuck that includes a ceramic plate and an embedded chucking electrode) on which a substrate240(shown dotted) may rest or be in thermal contact with. Substrate support assembly130, as shown, includes an electrostatic chuck that includes a ceramic plate234with embedded electrodes, resistive heating elements, channels, and so on. The substrate support assembly130additionally includes a ceramic shaft232bonded to the ceramic plate234. In some embodiments, the substrate support assembly further includes a fiber guide244inserted into a cavity in the ceramic shaft232. A plurality of channels235are formed in the ceramic plate234. An additional plurality of channels is formed in the fiber guide244and/or in the ceramic shaft232. A plurality of optical fibers236, adapted to provide light-based heating, are routed through the channels in the ceramic shaft232and/or fiber guide244and extend within channels235in the ceramic plate234of an electrostatic chuck.

As shown, the plurality of optical fibers236are configured to extend laterally within the channels235. Extend laterally, as used herein, means that the length of the optical fiber (along its longitudinal axis) passes horizontally within the channels235. Channels235may be oriented to extend substantially parallel to an upper surface plane of the ceramic plate234. Some slight deviation from parallel is possible due to laying the optical fibers236in the channels235. The plurality of channels235may be provided in any suitable pattern. One pattern includes a plurality of radial spokes, as shown inFIG. 3. Other suitable channel patterns may be used.

The plurality of optical fibers236are adapted to provide light-based heating of the substrate240. The plurality of optical fibers236may terminate at multiple radial locations in the channels235(seeFIG. 3, for example). Optical fibers236may pass through the ceramic shaft232and/or fiber guide244individually or as a bundle (e.g., as a group of fibers) and then bend and extend laterally within the channels235. Optical heating system124may include the light source array125including a plurality of light sources238coupled to at least some, and preferably most or all, of the plurality of optical fibers236. The optical controller126may be configured to control light power (e.g., intensity) channeled into, and carried by, the plurality of optical fibers236.

In operation, light carried in at least some of the plurality of optical fibers236is used to heat local portions of the ceramic plate234, and thus by at least conduction, the substrate240. In some embodiments, metal containing objects (not shown) are embedded in the ceramic plate proximate to ends of the channels. The metal containing objects may absorb photons emitted by the optical fibers and heat as a result of the absorption. When the plurality of optical fibers236are positioned and terminated at target locations, many local portions of the ceramic plate234may be heated. In some embodiments, this localized heating may be in conjunction with temperature control provided by the temperature unit122and the thermal elements242. In other embodiments, the localized (e.g. pixelated) heating by the plurality of optical fibers236may be the sole heating provided to the ceramic plate234.

For example, temperature control may, in some embodiments, cause the substrate240(shown dotted) to be heated to a nominal temperature of greater than about 200° C., greater than about 500° C., greater than about 600° C., or even about 650° C., or a greater temperature. For example, temperature control may, in some embodiments, cause the substrate240(shown dotted) to be heated to a nominal temperature of between about 600° C. and about 700° C. Such heating may be carried out on substrates240within the one or more process chambers106A-106C in some embodiments. For example, temperature control may, in some embodiments, cause the substrate240(shown dotted) to be heated, such as in a PECVD process.

In some embodiments, the thermal elements242may provide a primary heating source to heat the ceramic plate234to a nominal temperature, and the optical fibers236may act as assistive or supplemental heating sources, such that the nominal temperature may be further adjusted between bounds, such as between about +/−5° C. from a nominal temperature, between about +/−10° C. from the nominal, or even between about +/−25° C. from the nominal, for example. Other temperature adjustment magnitudes may be accomplished by using light sources238that are more or less powerful (having more or less light output power). Thus, in accordance with aspects of the invention, temperature control may be implemented by the optical fiber heating on a pixelated basis.

Some of the optical fibers236may include various optical features at the fiber termination, including a diffuse emitter, a lensed tip, or an angled cleave. Such optical features may be used to direct light to one or more surfaces of the diffuser or otherwise minimize light reflection back into the optical fiber236.

Operation of the optical fiber heating will now be described. For example, if the nominal target temperature of the substrate240is about 650° C., but geometrical or thermal anomalies or other differences in the process chamber106B or the design of the ceramic plate234make it difficult to achieve that nominal temperature across all parts of the substrate240, then auxiliary heating may be provided by the optical heating system124in addition to any heat provided by the temperature unit122and coupled thermal elements242. Auxiliary heating may be provided, in one or more embodiments, by the optical heating system124to adjust localized regions in order to meet any target temperature profile. In some embodiments, optical heating system124may be used to adjust localized regions to provide a substantially uniform temperature profile of the substrate240. However, the target temperature profile may be made intentionally non-uniform in some embodiments.

It should also be apparent that in some embodiments, the optical heating system124may be the sole source of heating (i.e., no temperature unit122or thermal elements242are present). In this embodiment, the optical controller126may be the sole temperature controller present and may adjust temperature of localized regions by adjusting the light intensity to individual optical fibers236, either individually or zonally.

The ceramic plate234and the ceramic shaft232may be formed of the same ceramic material. In one embodiment, the ceramic plate234and ceramic shaft232are aluminum nitride (AlN). In another embodiment, the ceramic plate234and ceramic shaft232are aluminum oxide (Al2O3). The ceramic plate234and the ceramic shaft232may have been diffusion bonded to form a single monolithic ceramic body that includes the ceramic shaft232and the ceramic plate234. An exterior of the ceramic shaft232may be exposed to a processing chamber in embodiments. In some implementations, the processing chamber may be exposed to a plasma environment (e.g., a fluorine plasma environment) and/or may be pumped down to reduced pressure (e.g., to vacuum). An interior of the ceramic shaft232may be protected from the plasma environment.

One or more holes may be drilled into a wall of the ceramic shaft to provide access for electrical lines to connect to the thermal elements242(also referred to as heating elements) and/or to one or more electrodes. The electrodes may include a chucking electrode that is used to secure a substrate to the substrate support assembly and/or a radio frequency (RF) electrode. The chucking electrode may use electrostatic forces to pull the substrate towards the ceramic plate. Holes may also be drilled into the wall of the ceramic shaft to enable helium to be pumped into region between a backside of substrate240and the upper surface of the ceramic plate234.

In the depicted embodiment, a single cavity that is centrally located is provided through the ceramic shaft232as shown. The fiber guide244is then inserted into the cavity in the ceramic shaft232. In one embodiment, the cavity is a circular cavity and the fiber guide is cylindrical (has a cylindrical shape). In one embodiment, the fiber guide244is a metal cylinder that includes the multiple channels. Examples of metals that may be used for the fiber guide244include stainless steel and aluminum. The channels may be holes drilled in walls of the fiber guide244or may be grooves machined into the outer perimeter of the fiber guide. The fiber guide244may be removable from the ceramic shaft232. Secondary passages245may also be included through the ceramic body234to accommodate lift pins246, temperature probes, or the like.

In alternative embodiments, no separate fiber guide244is used. Instead, the ceramic shaft232may have multiple channels formed therein for routing optical fibers into the channels235and may act as a fiber guide.

In some embodiments, a single optical fiber236may be received in each channel235. In other embodiments, multiple optical fibers236may be received in some channels235(seeFIGS. 6A-6B).

Once passing through the fiber guide244, the optical fibers236are bent around the radius249(e.g., at an approximate 90 degree angle) and extend outwardly (e.g., radially in some embodiments) and are laid in the channels235. The fiber guide244may be shaped to cause the fibers to automatically bend and be guided into the channels235as the optical fibers are pushed into the fiber guide244.

In addition to optical fibers236that are used to provide heating, some optical fibers236may be used as fiber optic temperature sensors. For example, some optical fibers236may be fiber optical thermocouples. The fiber optical thermocouples and/or other fiber optical temperature sensors may be used to measure the temperature of the ceramic plate at various regions. Each optical fiber that is a component of a fiber optic temperature sensor may be used to measure a temperature at a region of the ceramic plate. In some embodiments, optical fibers may be used both for heating and for temperature measurement. For example, an optical fiber may be split into two portions at one end. A first portion may be routed to an optical heat source such as a laser diode and a second portion may be routed to a temperature sensor.

Optical fibers236may be of various suitable lengths and may extend laterally to various target termination locations within the channels235. Channels235may be of different lengths as shown inFIG. 3, and may have any suitable channel shape. In some embodiments, the channels235may be straight, whereas others may be curved, circular, or even serpentine (seeFIGS. 5 and 6A). Combinations of straight, curved, circular, and serpentine channels235, or straight, curved, circular, and serpentine portions may be used to construct each channel235.

Channels235may also have any suitable cross-sectional shape. For example,FIGS. 4A-4Cillustrates various shapes of channels235.FIG. 4Aillustrates an enlarged partial cross-sectional view taken along section line4A-4A′ inFIG. 3. The shape of the channel235, as shown, may be generally rectangular in cross-section. However, other cross sectional shapes may be used, such as half round, trapezoidal, or the like. The ceramic plate234may initially be multiple different ceramic green bodies. The channels235may be formed in one of the ceramic green bodies after which the ceramic green bodies may be compressed and heated to fire or sinter the ceramic green bodies together to diffusion bond the ceramic green bodies and transform them into a monolithic sintered ceramic plate. The channels235may be formed by any suitable machining means, such as laser machining, abrasive water jet cutting, grinding or milling (e.g., with diamond tools), and the like. The channels235may be larger in width than a width of the optical fiber236so that the optical fiber236may not undergo stress due to thermal expansion mismatch. For example, the width of the channel235may be about 1 mm greater than or more than an outer dimension of the optical fiber236or group of optical fibers236that are routed within the channel235. For example, the dimensions of the channels235may be between about 1 mm and 3 mm wide, and between about 1 mm and 3 mm deep. Other dimensions may be used.

The number of channels235may number 20 or more, and between about 50 and 500 in some embodiments, such as when a single optical fiber236is received in each channel. In some embodiments, where multiple optical fibers236are received in each channel235, between about 5 and about 50 channels235may be provided. Thus, depending on the design, between about 5 and about 500 channels may be provided. A coating may be applied to the interior of one or more of the channels235to improve light absorption. For example, a black-colored high temperature coating suitable for high temperature service may be used.

InFIG. 4B, a sheath or sleeve450may be provided in the channel235and may loosely surround the optical fiber236along its length. In one or more embodiments, the sheath or sleeve450may be a woven, braided, or fibrous ceramic cloth or paper. Other materials such as fiberglass, capillary tubing or plastic tubing may be used. Other suitable high-temperature materials may be used for the sheath or sleeve450.

In some embodiments, a radial edge and/or upper surface of substrate support assembly130may include a protective layer256of an etch-resistant material. The protective layer256may be made of any material that resists etching by the gases or other material present within the process chamber106B. For example, the protective layer256may be a Yttrium oxide (Yttria) material, which may be applied by a spraying process (e.g., plasma spraying). Other suitable application processes may be used.

The ceramic plate234may include the thermal elements242imbedded therein. The thermal elements242may provide single-zone heating or dual-zone heating in some embodiments, and may be configured vertically above the location of the optical fibers236. The thermal elements242may provide a majority of the heat and the light-based heating provided by the optical fibers236provide localized heating supplements to provide the capability of making local temperature adjustments adjacent to the terminations locations of the optical fibers236.

In the depicted embodiment ofFIGS. 1-2, the optical controller126may be any suitable controller having a processor, memory, and peripheral components adapted to execute a closed loop or other suitable control scheme and control the optical power (e.g., Watts) emanating from each of the light sources238of the light source array125. At least some of the light sources238are coupled to the optical fibers236and provide optical power thereto (e.g., infrared energy). Optical fibers236may be arranged in a bundle (as shown) and may include a protective sheath252over at least some of the length. Sheath252may be a flexible stainless steel tube in some embodiments. Other suitable sheath materials may be used.

Optical fibers236may include any suitable optical fiber type, such as graded-index optical fiber, step-index single mode optical fiber, multi-mode optical fiber, or even photonic crystal optical fiber. Optical fibers236that exhibit relatively high bend resistance may be used in some embodiments. Relatively high numerical aperture (NA) fibers may be used, such as NA of greater than about 0.1, greater than about 0.2, or even greater than about 0.3. Any suitable number of optical fibers236may be used, such as 20 or more, 50 or more, 100 or more, 200 or more 300 or more, 400 or more, and even up to 500 or more. As previously mentioned, some of the optical fibers may be fiber thermocouples. The termination of the optical fibers236may be located below the upper surface of the ceramic plate234by between about 0.125 inch (about 3.2 mm) to about 0.5 inch (12.3 mm). Other vertical locations are possible.

One example with277optical fibers236coupled to 10 W light sources238where the terminations of the optical fibers236in the channels235are located at 0.325 inch (8.3 mm) below the upper surface of the ceramic plate234provides relatively uniform light-based heating. Optical fibers236may be coupled to the respective light sources238by any suitable conventional coupling means.

As shown inFIG. 4A, the optical fibers236may each include a metal film453. Depending on the operating temperature, aluminum, copper or gold may be used for the metal film453. At temperature around 650° C., gold may be used for the metal film453. The metal film453may be about 15 microns thick, for example. Other thicknesses may be used.

The optical fibers236may comprise standard polymer-coated optical fibers (e.g., acrylate or acrylate-epoxy polymer coating). The optical fibers236may be spliced to the polymer-coated fibers in some embodiments.

In some embodiments, one or more of the light sources238C may be coupled by a sensor fiber254to a control sensor255, such as a light receiver (e.g., photodiode). Each light source238may be a laser diode, such as a single emitter diode. The laser diode may have any suitable output wavelength range, such as between about 915 nm and about 980 nm, for example. Other output ranges may be used. Output power may be modulated between about 0 W to about 10 W. However, ever higher power diodes (e.g., >10 W) may be used. The laser diode may include an optical fiber output having a 105 or 110 micron core diameter, for example. For example, a model PLD-10 from IPG Photonics of Oxford, Mass. may be used. Other types of light sources238may be alternatively used. According to embodiments, between about 20 and about 500 light sources238may be used. As shown, the light sources238may be rest upon or be in thermal engagement with a common heat sink459, which may be cooled (e.g., liquid cooled) to between about 20° C. and about 30° C. by a cooling source462. Cooling source462may be a source of chilled water, for example. Other types of cooling sources462may be used.

A control sensor255may be used to provide feedback to the optical controller126on a relative output of a control light source238C (e.g., of light intensity or heat generation, for example). Optionally or in addition, one or more optical temperature sensors may be provided in one or more of the channels235and coupled to a temperature measuring system460to enable localized temperature monitoring of an inside portion of the substrate support assembly130. For example, the optical temperature sensor may be a fiber Bragg grating coupled to a spectrometer, which may be the temperature measuring system460. A fiber multiplexer or other like component may be used to connect multiple optical temperature sensors to a single spectrometer. An optical temperature sensor may also be accomplished by other suitable means, such as by embedding a tip of an optical fiber in a suitable adhesive material (e.g., CERAMACAST 865 available from Aremco Products Inc. of Valley Cottage, N.Y.) and measuring the thermal radiation emitted by that material. Thermal measurement may be accomplished by coupling the optical fiber to an indium gallium arsenide photodiode. The optical fibers coupled to the optical temperature sensor may also be placed in a channel235. Any suitable temperature measuring system460may be used to interrogate the optical temperature sensor458. Temperature measuring system460may interface with the temperature controller128and/or the optical controller126to provide temperature feedback. Optionally or additionally, thermal feedback by other methods, such as two or more RTDs on the substrate support assembly130may be used.

Each light source238may be individually controlled and modulated from a low or zero level of optical power output to a high or maximum level of optical power output. Each light source238may be individually controlled in order to control temperature at finite points (pixels) or collectively controlled in groups of optical fibers to control temperatures of one or more regions or zones of the substrate support assembly130.

Any suitable temperature control philosophy may be implemented. In one control aspect, a highly uniform temperature distribution across an upper surface of the substrate240may be sought. In another aspect, a deliberately non-uniform temperature distribution may be beneficial (e.g., hotter or cooler at an edge of the substrate240). Each temperature profile may be provided, in accordance with aspect of the invention depending on the control philosophy implemented by the optical controller126. Some embodiments of the invention may provide azimuthal temperature variations.

FIG. 4Cillustrates an enlarged partial cross-sectioned view of a portion of a substrate support assembly showing one embodiment of an optical fiber within a channel.FIG. 4Dillustrates an enlarged partial cross-sectioned view of a portion of a substrate support assembly showing another embodiment of an optical fiber within a channel. The cross-sectioned views ofFIG. 4CandFIG. 4Dare taken at line4D-4D′ inFIG. 3according to embodiments. As shown, a ceramic plate234of the substrate support assembly includes thermal elements242and a channel235into which an optical fiber236has been inserted.

With reference toFIG. 4C, a metal containing object480has been inserted into the ceramic plate234proximate to an end478of the channel235. The metal containing object480may be a metal absorption tablet such as a molybdenum tablet, a tungsten tablet or a metal alloy tablet that includes molybdenum and/or tungsten. The metal containing object480may also be a metal wire or a mixture of a metal (e.g., tungsten or molybdenum) and a ceramic (e.g., AlN or Al2O3). Prior to forming the ceramic plate a ceramic green body into which the channels are formed may also be machined to include cavities for receiving the metal containing objects480. The metal containing objects480may then be placed into the cavities in the green body before the green body is sintered with other green bodies to form the ceramic plate234.

A thin wall482of the ceramic plate separates the metal containing object480from the channel235. This may protect the metal containing object480from exposure to air and may prevent the metal containing object480from oxidizing. Photons may be emitted from an end of the optical fiber236and projected toward the metal containing object480. The metal containing object may absorb the photons and heat up. The metal containing object may then radiate heat and heat up a region of the ceramic plate234.

With reference toFIG. 4D, a metal containing object486has been inserted into the ceramic plate234in the channel235at an end484of the channel235. The metal containing object486may correspond to any of the aforementioned metal containing objects. In one embodiment, the metal containing object486is the mixture of metal and ceramic and is screen printed onto the end478of the channel235. Alternatively, the metal containing object486may be screen printed onto a surface of a green body such that when the green body is bonded to another green body that includes the channel235, the metal containing object486occupies a space at the end of the channel235. The green bodies may then be co-sintered to form the ceramic plate234having the metal containing object486at the end of the channel235.

Referring now toFIG. 5, a sectional view of another embodiment of a ceramic plate532including a plurality of channels535formed in a pattern and interconnecting to a passage544is shown. Optical fibers (not shown) of pre-measured length may be fed as a bundle through the passage544and routed within and positioned into place (e.g., laid and at least temporarily adhered) in the plurality of channels535. The plurality of channels535may be provided in a pattern including at least some radial spokes535S. Radial spokes535S may emanate from at or near the passage544and extend radially outward therefrom. In some embodiments, the radial spokes535S may not be straight, but may include a curvature thereon. In some embodiments, the radial spokes535S may depart from a purely radial orientation, and may be angled by as much as 60 degrees therefrom. Six radial spokes535S are shown, but more or less numbers of radial spokes535S may be used.

In another aspect, the plurality of channels535may be provided in a pattern including one or more of circular channel sections535C that may be either partial or full circles. A plurality of full circles as circular channel sections535C are shown inFIG. 5. The circular channel sections535C may be concentric, as shown, in some embodiments. Eight circular channel sections535C are shown, but more or less numbers of circular channel sections535C may be used.

As shown inFIG. 5, when the plurality of channels535include a pattern having both a plurality of radial spokes535S and circular channel sections535C, then transition channels535T may be provided. Transition channels535T may have a radius of greater than about 15 mm to allow for a smooth transition from the radial spokes535S to the circular channel sections535C. Each of the channels535may terminate in a channel pocket535P (a few labeled) and the optical fibers (not shown) may be cleaved to a length where the termination ends within the channel pocket535P. This aids in precisely locating the terminations.

FIG. 6Aillustrates a sectional view of another embodiment of the a ceramic plate632including channels635formed therein. Channels635comprise serpentine paths as shown, but the channel paths can be of any shape. The channels635are shown machined in the ceramic plate632. These channels635start at near center and intersect target “pixel” locations as they move outward. Eight channels635are shown, but the number of channels635may be more or less, depending on the number of target “pixel” locations.

Optical fibers636A,636B,636C, etc. may be inserted into the channels635after the ceramic plate632having the channels635has been formed. Because the optical fibers636A,636B,636C, etc. are not installed at the time of forming the ceramic plate632, high temperature bonding processes may be used (e.g., diffusion bonding process). Diffusion bonding takes place around 1500-1800° C., which is above the melting temperature of the optical fibers (about 1600° C.), and may provide a higher bond strength.

To accomplish insertion into the channels635after bonding, multiple optical fibers (e.g., optical fibers636A,636B,636C shown) may be bundled into a fiber assembly665as shown inFIG. 6B. The fiber assembly665may include a core668that may include a pusher wire669with a guide member670, such as a spherical-shaped plastic tip formed thereon. Other types of guide members670may be used. This core668provides the stiffness and guiding capability in order to thread the fiber assembly665into the channels635.

Optical fibers636A,636B,636C are shown bundled around the pusher wire669, with the terminal ends of the optical fibers636A,636B,636C being staggered along a length of the fiber assembly665. Heat shrink tubing672(shown dotted) may be used to secure the components of the fiber assembly665together. Other means, such as a suitable adhesive, may be used for bundling together the fiber assembly665.

The pusher wire669may be made of a high temperature alloy, such as Inconel600, suitable for operation at high temperature (e.g., about 650° C.). The pusher wire669may be gold plated, so to reflect laser energy back to the surrounding ceramic material of the ceramic plate.

In one or more embodiments, the optical fibers636A,636B,636C of the fiber assembly665may include angled cleaves (e.g. 45 degrees) so the laser energy fires off to a side. The direction that the angled cleave of the optical fibers636A,636B,636C point may not be controlled. Each individual optical fiber636A,636B,636C may point up, down, or to the side. Three optical fibers (e.g., fiber636A,636B,636C) are shown in the depicted embodiment. However, about two to about fifty optical fibers, or even two to a hundred may be included in each fiber assembly665. About five to about twenty optical fibers may be preferable in each fiber assembly665.

FIG. 7Aillustrates a perspective view of one embodiment of a ceramic shaft720and fiber guide735for a substrate support assembly705.FIG. 7Billustrates a cross sectional side view of the substrate support assembly705ofFIG. 7A, including the ceramic shaft720and fiber guide735.FIG. 7Bmay correspond to a cross section taken at line7B-7B ofFIG. 7A. The substrate support assembly705may correspond to substrate support assembly130ofFIGS. 1-2in embodiments.

The substrate support assembly705includes a ceramic plate710, a ceramic shaft720bonded to a bottom surface of the ceramic plate710, and a fiber guide735inserted into a cavity730in the ceramic shaft720. Multiple channels740are formed inside of the ceramic plate710. A recess715or cavity may be formed on a bottom surface of the ceramic plate710. The recess715may provide access to all of the channels740in the ceramic plate710. Accordingly, the channels740may all terminate at the recess715. In one embodiment, the recess715is a circular recess and is located at or near a center of the bottom surface of the ceramic plate710. In one embodiment, the recess715is fully surrounded by the ceramic shaft720.

The ceramic shaft720may have a lip725that has a larger diameter than a remainder of the ceramic shaft720. The lip725may provide increased surface area for improved bonding with the ceramic plate710and may provide improved strength and stability. The ceramic shaft720may be a hollow shaft having a cavity730that may or may not have a similar diameter to a diameter of the recess715. In one embodiment, the cavity730has a diameter of approximately 4 inches.

Fiber guide735is inserted into the cavity730in the ceramic shaft. The fiber guide may have a diameter of approximately 4 inches in one embodiment. Fiber guide735includes multiple channels745, which may be holes drilled into the fiber guide735. In one embodiment, each channel745is separated from a next channel745around a perimeter of the fiber guide by approximately 2 mm. For a fiber guide having a diameter of 4 inches, up to 150 channels may be formed having a spacing of 2 mm. The fiber guide735may be metal and may include multiple channels745. The channels745may receive optical fibers750and guide the optical fibers750into channels740in the ceramic plate710. In one embodiment, the fiber guide735includes the same number of channels745as the number of channels740in the ceramic plate710. Each channel745may line up with a corresponding channel740in the ceramic plate710. Channels740may extend laterally in the ceramic plate710and may be substantially parallel to a surface of the ceramic plate710. Channels745may be substantially perpendicular to the surface of the ceramic plate710.

FIG. 8Aillustrates a perspective view of one embodiment of a ceramic shaft820and fiber guide835for a substrate support assembly805.FIG. 8Billustrates a cross sectional side view of the substrate support assembly805ofFIG. 8A, including the ceramic shaft820and fiber guide835.FIG. 8Bmay correspond to a cross section taken at line8B-8B ofFIG. 8A. The substrate support assembly805may correspond to substrate support assembly130ofFIGS. 1-2in embodiments.

The substrate support assembly805includes a ceramic plate810, a ceramic shaft820bonded to a bottom surface of the ceramic plate810, and a fiber guide835inserted into a cavity830in the ceramic shaft820. Multiple channels840are formed inside of the ceramic plate810. A recess815or cavity may be formed on a bottom surface of the ceramic plate810. The recess815may provide access to all of the channels840in the ceramic plate810. Accordingly, the channels840may all terminate at the recess815. In one embodiment, the recess815is a circular recess and is located at or near a center of the bottom surface of the ceramic plate810. In one embodiment, the recess815is fully surrounded by the ceramic shaft820.

The ceramic shaft820may have a lip825that has a larger diameter than a remainder of the ceramic shaft820. The lip825may provide increased surface area for improved bonding with the ceramic plate810and may provide improved strength and stability. The ceramic shaft820may be a hollow shaft having a cavity830that may or may not have a similar diameter to a diameter of the recess815. In one embodiment, the cavity830has a diameter of approximately 4 inches.

Fiber guide835is inserted into the cavity830in the ceramic shaft. The fiber guide835may have a diameter of approximately 4 inches in one embodiment. Fiber guide835includes multiple channels845, which may be grooves or ribs machined into the outer perimeter or wall of the fiber guide835. In one embodiment, each channel845is separated from a next channel845around a perimeter of the fiber guide by approximately 2 mm. For a fiber guide having a diameter of 4 inches, up to 150 channels may be formed having a spacing of 2 mm. The fiber guide835may be metal and may include multiple channels845. The channels845may receive optical fibers850and guide the optical fibers850into channels840in the ceramic plate810. In one embodiment, the fiber guide835includes the same number of channels845as the number of channels840in the ceramic plate810. Each channel845may line up with a corresponding channel840in the ceramic plate810. Channels840may extend laterally in the ceramic plate810and may be substantially parallel to a surface of the ceramic plate810. Channels845may be substantially perpendicular to the surface of the ceramic plate810.

FIG. 9illustrates a flowchart depicting a method900of manufacturing a substrate support assembly that includes optical fibers for heating. At block905, channels may be machined into a first ceramic green body using any of the techniques described herein above. At block910, receiving areas for metal containing objects may be machined into the first ceramic green body. At block915, metal containing objects are interested into the first ceramic green body or are otherwise formed in the first ceramic green body (e.g., by screen printing). Alternatively, the metal containing objects may be formed on a second ceramic green body, such as by screen printing. If no metal containing objects or targets are to be used, then blocks910and915may be skipped.

At block920, the first ceramic green body is stacked with one or more additional ceramic green bodies. The first ceramic green body, may be stacked over another ceramic green body for example. The other ceramic green body may include thermal elements such as resistive heating elements. Additionally, the first ceramic green body may be stacked under still one or more additional ceramic green bodies. These additional ceramic green bodies may have formed thereon electrodes (e.g., an RF mesh), and so on. Alternatively, a ceramic green body including the thermal elements may be positioned over the ceramic green body having the channels.

At block925, the stack of ceramic green bodies is compressed and sintered or fired together to form a ceramic plate that has a monolithic body. The sintering process may be performed at temperatures of about 1500° C. or above. At block930, a hole or recess is formed in a bottom surface of the ceramic plate. The hole may provide access to the channels formed in the ceramic plate.

At block935, a ceramic shaft is diffusion bonded to the bottom surface of the ceramic plate. The ceramic shaft may be placed to surround the hole formed in the bottom surface of the ceramic plate. The diffusion bonding may be performed by compressing the ceramic shaft against the ceramic plate a temperatures of about 1500° C. or above.

In one embodiment, the ceramic shaft is a hollow shaft that has a central cavity. At block940, a fiber guide may be inserted into the central cavity in the ceramic shaft. At block945, optical fibers may be inserted through channels in the fiber guide and into the channels in the ceramic plate. The substrate support assembly may then be ready for use.

FIG. 10illustrates a flowchart depicting a method1000of refurbishing a substrate support assembly that includes removable optical fibers. At block1005of method1000, a faulty optical fiber is identified in an electrostatic chuck comprising a plurality of removable optical fibers. Each of the plurality of removable optical fibers may be inside a first plurality of channels in the electrostatic chuck. The electrostatic chuck may be a ceramic plate of the substrate support assembly that includes a chucking electrode.

At block1010, the faulty optical fiber is removed from a first channel of the first plurality of channels in the electrostatic chuck and a second channel of a ceramic shaft that is bonded to the electrostatic chuck. The second channel is one of a second plurality of channels in the ceramic shaft. The first channel may be substantially parallel to a top surface of the electrostatic chuck and the second channel may be substantially perpendicular to the top surface of the electrostatic chuck.

At block1015, a new optical fiber is inserted into the first channel in the electrostatic chuck. In one embodiment, at block1020the new optical fiber is pushed through the second channel of the second plurality of channels that is aligned with the first channel of the first plurality of channels. The second channel guides the new optical fiber into the first channel. The electrostatic chuck of the substrate support assembly is then ready for use again.

A method of processing substrates, such as within an electronic device processing system (e.g., electronic device processing system100) will be described briefly. The method includes providing a substrate support assembly (e.g., substrate support assembly130) including a ceramic plate, a ceramic shaft, and a plurality of optical fibers (e.g., optical fibers236,636A,636B,636C) extending laterally in channels (e.g., channels235,535,635). Optical fibers may be installed in channels after the substrate support assembly is manufactured.

The method further includes controlling light intensity provided to at least some of the plurality of optical fibers to accomplish light-based temperature control of the ceramic plate. Of course, temperature control of the ceramic plate also controls temperature of the substrate (e.g., substrate240) that is in thermal contact therewith. In one or more embodiments, the method may further comprise heating the substrate support assembly by way of a coupled temperature unit (e.g., temperature unit122) and thermal elements (e.g., thermal elements242).

The method of controlling temperature of the substrate240may include providing temperature feedback, such as though the use of optical sensors (e.g., optical sensors) embedded in one or more of the channels235,535,635. In some embodiments, large numbers of embedded optical sensors may be used. In others, model based control and a lesser number of temperature sensors may be employed. The control methodology for controlling the optical fibers236may be adjusted based on feedback from the process taking place in the process chamber (e.g., process chamber106B), such as by measuring process results on the substrate240.

The foregoing description discloses example embodiments of the invention. Modifications of the above-disclosed apparatus, systems, and methods which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. Accordingly, the present invention has been disclosed in connection with example embodiments, it should be understood that other embodiments may fall within the scope of the invention, as defined by the following claims.