Abstract:
A vacuum processing chamber for measuring the temperature of a surface of an object comprising a cap is provided. The cap has a non-deformable end wall of thermally conducting material and a side wall connected thereto. An outside surface of the end wall is shaped to conform to a shape of the object surface to be measured. A surface on an inside of the end wall of the cap emits electromagnetic radiation having a detectable optical characteristic that is proportional to the temperature of the cap end wall. The vacuum processing chamber further comprises a light wave guide having one end held within the cap a distance from the radiation emitting element and in optical communication therewith.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of application Ser. No. 10/452,551, filed May 30, 2003, which is a continuation of U.S. Pat. No. 6,572,265 filed Apr. 20, 2001, the contents of each are incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to optical temperature measuring techniques, and, more specifically, to devices and techniques for contact and non-contact methods of measurement of the surface temperature of an article during processing. 
       BACKGROUND OF THE INVENTION 
       [0003]    There has been a great deal written about various optical temperature measuring techniques, both in patents and the technical literature, as well as many commercial products utilizing this technology. In one aspect of this technology, a luminescent material is used as a temperature sensor because certain aspects of its luminescence are temperature dependent. Typically in the form of a sensor at the end of a fiber optic cable, the luminescent material is excited to luminescence by sending excitation radiation of one wavelength to the sensor through the optical fiber, and the resulting luminescence at a different wavelength is photo-detected after passing back along the optical fiber. The detected signal is then processed to determine the temperature of the luminescent material in the sensor. Basic concepts of luminescent temperature sensing, as well as many different forms of sensors, are described in U.S. Pat. No. 4,448,547. The measurement of the decay time of the luminescence after termination of an excitation pulse, as a measurement of temperature, is described in U.S. Pat. No. 4,652,143. Commercial products adopted the decay time measurement technique as a good measurement of temperature. One advantage and focus of luminescent temperature measurement techniques has been for applications in environments having strong electric and/or magnetic fields and the like, where metal sensors cannot be relied upon to provide accurate results because the metal is heated when immersed in the electromagnetic field, causing a bias in the readings. 
         [0004]    Applications of these luminescent sensor measurement techniques are numerous, including the measurement of surface temperature. U.S. Pat. No. 4,752,141 describes an elastomeric luminescent sensor at the end of an optical fiber that deforms as it is pushed against a surface being measured in order to establish good thermal contact. Another embodiment employing a thin non-metallic disc with a layer of luminescent material between it and the end of an optical fiber is also described. 
         [0005]    Another optical temperature measuring technique relies upon the infrared emissions of a black-body sensor, or one having the characteristics of a black-body. An example of such a system, generally used to measure higher temperatures than measured with luminescent sensors, is described in U.S. Pat. No. 4,750,139. The sensor is a black-body emitter formed at the end of an optical fiber. U.S. Pat. No. 5,183,338 describes several forms of a fiber optic sensor that includes both luminescent and blackbody temperature measuring elements. Each of the foregoing identified patents is expressly incorporated herein in its entirety by this reference. 
         [0006]    There are also many other optical temperature sensing techniques that have been described in patents and the literature, as well as being used commercially. But the luminescent and black-body techniques have generally been preferred over those others. 
       SUMMARY OF THE INVENTION 
       [0007]    Additional aspects, features and advantages of the present invention are included in the following description of exemplary embodiments thereof, which description should be taken in conjunction with the accompanying drawings. 
         [0008]    A sensor for measuring the temperature of the surface of an object is disclosed. The sensor has a cap having an end wall of thermally conducting material that is shaped to conform to a shape of the object. The inside surface of the end wall of the cap emits electromagnetic radiation having a detectable optical characteristic that is proportional to the temperate of the end wall. The sensor further comprises a waveguide disposed generally orthogonal to the cap. The inside surface of the cap is in optical communication with the waveguide in order to transmit the electromagnetic radiation therefrom. The sensor also has a resilient member connected to the cap in a manner to urge the cap away from the waveguide a limited distance in a manner that allows a limited degree of axial and directional freedom with respect to the waveguide. In this respect, the cap can firmly engage the object surface when positioned in contact therewith. 
         [0009]    In accordance with another embodiment of a temperature sensor, there is provided a sensor with a thermally conducting contact having a surface that emits electromagnetic radiation with a detectable optical characteristic that is proportional to the temperature of the contact. A resilient member is attached to the contact and configured to extend the contact toward the object to be measured. A first waveguide is attached to the contact and is configured to transmit the electromagnetic radiation from the contact. The sensor further has a guide with a bore formed therein. The first waveguide is insertable into the bore such that when the contact is moved, the first waveguide moves within the bore. A second waveguide is attached to the guide such that a variable gap is formed between the ends of the first waveguide and the second waveguide. Electromagnetic energy from the first waveguide traverses the gap such that it can be transmitted by the second waveguide. In this regard, the guide allows first waveguide to be able to move with the contact in order to ensure that the contact is filly engaged with the surface of the object. 
         [0010]    In accordance with yet another embodiment, a temperature sensor having a tip and a contact is disclosed. The temperature sensor has a thermally conducting contact with a surface that emits electromagnetic radiation with a detectable optical characteristic that is proportional to the temperature of the contact. The tip has a barrel section and a mating section and is attached to the contact. The sensor further includes a shield with an opening formed in an end thereof and an annular ledge formed around the opening. The opening is configured such that the barrel portion of the tip passes through the opening and the annular ledge is shaped to be complementary to the mating section of the tip. The sensor has a resilient member attached to the contact and is configured to extend the barrel portion through the opening such that the contact is extended toward the object. A waveguide is disposed within the tip and is configured to transmit the electromagnetic radiation emitted from the surface of the contact. The opening and the ledge allow a limited degree of rotational freedom of the tip to thereby provide engagement between the contact and the object. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a general schematic diagram that shows a processing chamber in which a temperature sensor of the present invention may be used; 
           [0012]      FIG. 2  is a cross-sectional view of a general form of a surface temperature sensor; 
           [0013]      FIG. 3  shows the temperature sensor of  FIG. 2  in contact with a surface being measured; 
           [0014]      FIG. 4  is a cross-sectional view of a first specific example surface temperature sensor; 
           [0015]      FIG. 5  is a cross-sectional view of a second specific example surface temperature sensor; 
           [0016]      FIG. 6  is a cross-sectional view of a third specific example surface temperature sensor; 
           [0017]      FIG. 7  is a cross-sectional view of a fourth specific example surface temperature sensor; 
           [0018]      FIG. 8  illustrates a modification of any of the temperature sensors of  FIGS. 2-7  to include a first form of an infrared emitter as the temperature sensor; 
           [0019]      FIG. 9  illustrates a modification of any of the temperature sensors of  FIGS. 2-7  to include a second form of an infrared emitter as the temperature sensor; 
           [0020]      FIG. 10  shows a form of package for any of the temperature sensors of  FIGS. 4-9 ; 
           [0021]      FIG. 11  shows one example use of a temperature sensor, according to any of  FIGS. 2-10 ; 
           [0022]      FIG. 12  shows another example use of a temperature sensor according to any of  FIGS. 2-10 ; 
           [0023]      FIG. 13  illustrates a test substrate with a luminescent temperature sensor built into a surface; 
           [0024]      FIG. 14  is a sectional view of  FIG. 13 , taken at section A-A thereof; 
           [0025]      FIG. 15  shows one way of optically coupling with the substrate sensor of  FIGS. 13 and 14 ; 
           [0026]      FIG. 16  is a block diagram of another embodiment of a temperature sensor for measuring the temperature of a substrate; 
           [0027]      FIG. 17  is an elevation view of the sensor shown in  FIG. 16 ; 
           [0028]      FIG. 18  is a cross-sectional view of another embodiment of the temperature sensor using two waveguides; and 
           [0029]      FIG. 19  is a cross-sectional view of yet another embodiment of a temperature sensor having a tip. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0030]    The surface temperature techniques and sensors of the present invention may be used in a wide variety of environments and applications. The temperature of surfaces on any of a large number of types of objects may be measured. These measurements can be made while the object is being subjected to some processing where knowledge of the temperature of its surface is desired, or, otherwise. The example application described herein is the measurement of the temperature of the surface of substrates during one or more steps of processing to form integrated circuits and/or visual display elements such as liquid crystal display devices (LCDs) thereon. The substrate is either a semiconductor wafer or that of a flat panel display, in the examples described. 
         [0031]    Referring to  FIG. 1 , a general evacuated processing chamber  11  formed by an enclosure  13  is schematically illustrated. A substrate  15  being processed within the chamber is supported horizontally or vertically by a structure appropriate for the substrate and type of processing, the support in this case being a chuck  17  upon which the substrate rests in a horizontal position. The substrate  15  is typically heated in some fashion, a radiant heater  19  being shown. In some processes, the chuck  17  is cooled by circulation of water or some other coolant through it from an outside water supply  21  that includes refrigeration to cool the water. A vacuum pump  23  lowers the pressure within the chamber  11 . Many processes involve the introduction of one or more gases into the chamber  11 , an external supply  25  of such gas(es) being shown. Specific processing elements  27  within the chamber  11  vary depending upon the process being performed. Chemical vapor deposition (CVD) and physical vapor deposition (PVD), such as sputtering and vaporization, are among the processes wherein the temperature measurement techniques of the present invention have application. Substrates are loaded into and unloaded from the chamber  11  through a load lock  29 . 
         [0032]    In the example of  FIG. 1 , the chuck  17  is provided with a temperature sensor  31  that contacts an underside of the substrate  15 , when lying on the chuck, to measure the temperature of the contacted surface. An optical signal of the sensor  31  is coupled to a photodetector  35  by an optical communication medium  33  which can be a waveguide in the form of an optical fiber, other form of light pipe or a hollow waveguide. An electrical signal output of the photodetector  35  is received by a measuring circuit card or instrument  37  to provide an output signal  39  of the measured temperature. This signal can be used for a number of purposes, such as to drive an indicator (not shown) that provides a human operator with the temperature information that enables he or she to make adjustments to the heater  19  or other aspects of the processing. Alternatively, the signal  39  can be used by a control system (not shown) of the processing chamber in a feedback loop to control the heater  19  or other processing element. 
         [0033]    The optical temperature measuring element of the sensor  31  may be a luminescent material that has some aspect of its luminescence highly temperature-dependent. Measurement of the decaying characteristics of the luminescent radiation output signal is usually preferred, as described in the patents discussed in the Background section above. When a luminescent sensor is employed, an excitation source  36  and beam splitter  34  are added to the configuration of  FIG. 1 . An alternative sensor element is a non-luminescent surface of known emissivity that emits electromagnetic radiation with a magnitude proportional to its temperature, as previously described. Other potential optical temperature measuring techniques include monitoring the frequency of the band edge of a semiconductor element, the absorption of incident radiation by an element of temperature dependent transmission and the color of a material that changes with temperature. 
         [0034]    A general form of sensor  31  is illustrated in  FIGS. 2 and 3 . A light waveguide  41 , such as an optical fiber, or other form of light pipe or hollow waveguide, is held fixed within the chuck  17 . A cap  43  of material having a high degree of thermal conductivity is positioned within an aperture  45  and held by a resilient element  47  a distance away from an end of the waveguide  41 . The cap  43  normally extends a short distance above the upper surface of the chuck  17 , as shown in  FIG. 2 , but the resilient element  47  that holds the cap in that position has a strength that is designed to allow the weight of the substrate  15  to urge the cap downward into the opening  45  when the substrate  15  is laid on the chuck  17 . A substrate contacting end of the cap  43  has at least a significant portion of its surface formed in a mating shape to that of the surface being measured in order to form an intimate contact with that surface. That shape in this case is planar. The cap  43  is also allowed to rotate within some limit with respect to the fixed waveguide in order to facilitate its mating surface being orientated in close contact with the substrate surface as the substrate is lowered onto the chuck  17 . 
         [0035]    The cap  43  may be made of a very thin heat conducting metal, such as nickel, whose substrate-contacting end does not deform in shape during normal use. In this general example, the cap  43  has a cylindrical shape in side-view, a cross-sectional side view being shown in  FIGS. 2 and 3 . In addition to serving to contact the substrate, the cap  43  is a carrier of the optical temperature sensing element. In  FIGS. 2 and 3 , this element is a layer  49  of luminescent material that is attached to an inside surface of the cap  43 . An optically transparent cover  51  is usually used to seal the luminescent material layer  49  from out-gassing that can result from use in a very low-pressure chamber. Gasses escaping from the luminescent material can interfere with the processing. The cover  51  may be made from sapphire, for example, since it is a very stable and inert material. Similarly, a sapphire cover  53  may be attached to the end of the waveguide  41  to prevent out-gassing of the waveguide materials. However, if the waveguide is itself made of sapphire, this is not necessary. Although the cap form of the carrier for the luminescent material is preferred, alternate carrier shapes are also possible. 
         [0036]    Four different specific embodiments of the sensor generally shown and described with respect to  FIGS. 2 and 3  are shown in  FIGS. 4-8 , wherein the same reference numbers are used for corresponding elements. Each sensor is shown in the form of a cartridge having an outer housing  55  with an outside shape that is suitable for its intended application. The entire unit is then inserted into a mating aperture of the chuck  17  or other element in which it is installed. The outside shape of the housing  55 , and thus the mating aperture of the chuck  17 , can be cylindrical (as shown), square or any other suitable shape. The housing preferably has an outwardly extending flange  57  that positions the sensor within the chuck in an axial direction. 
         [0037]    In the embodiment of  FIG. 4 , the cap  43  is shaped to provide a ledge  59  against which a spring  61  (the resilient element  47 ) urges the cap upward. That same ledge also abuts a ledge  63  around the opening in the housing  57  through which the cap  43  extends, thereby constraining maximum movement of the cap  43  out of the housing, When the substrate  15  pushes against the end surface of the cap  43 , the cap is pushed downward into the opening  45  against the force of the spring  61 . In order to make sure that the cover  51  does not touch the end cover  53  of the optical fiber when the cover is pushed into the opening by the weight of a substrate, and thus limit its travel, the distances are made sufficient so that this does not occur. A void exists between the covers  51  and  53  at all times. 
         [0038]    A difference with the embodiment of  FIG. 5  is that the resilient element is formed as part of the cap. The cap  43 , instead of cylindrically shaped side walls, includes integral fingers  61 ,  62  and  63  that bend to cause their lower terminations to spread horizontally as the cap is pushed downward into the opening  45  when urged against a substrate surface. When not pushed downward, these fingers  61 ,  62  and  63  hold the surface contacting end of the cap  43  above the upper surface of the housing flange  57 . 
         [0039]    The embodiment of  FIG. 6  also uses a cap that has the resilient element formed in its side walls. In this case, the side walls are a bellows that allows the exposed end of the cap  43  to be pushed into the opening  45 . An end  65  of the integral cap structure is conveniently made to fit onto a mating boss formed as part of the housing  55 . The two mating surfaces may be held together by a layer of glue between them. The shape of the mating surfaces may be cylindrical (as shown), square or any other shape that is suitable for a particular application. The end of the waveguide thus extends into the interior of the bellows, again with space between the waveguide and the inside of the cap being maintained even when the cap is pushed downward by contact with the surface being measured. Such an open end bellows cap element, suitable for this application is available from Servometer Company. The housing  55  is preferably machined or molded as a single piece from polyamide-imide, this material being available from the General Electric Company. When the cap  43  is of a unitary, gas impermeable structure, and its open end is sealed to the housing  55 , the covers  51  and  53  may be omitted. 
         [0040]    In the embodiment of  FIG. 7 , the fingers of the embodiment of  FIG. 5  are extended substantially horizontally and provided with folds similar to those of the bellows in the embodiment of  FIG. 6 . The ends of these fingers are attached by glue to the housing  55 . As the top surface of the cap is pushed downward, as with the bellows of the  FIG. 6  embodiment, the folds of the fingers move closer together but return to their uncompressed state shown in the drawings when that force is removed from the cap. 
         [0041]      FIGS. 8 and 9  show a modification of the sensors of  FIGS. 2-7  where a blackbody surface is substituted for the luminescent material layer  49  as the temperature sensor. This is desirable when the range of temperatures being measured is higher than that which can be measured by luminescent materials. In  FIG. 8 , a layer  71  of material of a known, controlled surface emissivity is applied to an inside surface of an end of the cap  43 ′. This emissivity is preferably made to be high, in a range of 0.8 to 1.0, where 1.0 is the emissivity of a black body. The layer  71  can most simply be a paint that is applied to the inside of the cap. Alternatively, the layer  71  is omitted if the material of the cap  43 ′ is selected to have a known emissivity of its surfaces that is high enough for practical use. 
         [0042]    In the sensor of  FIG. 9 , the inside surface of the cap  43 ″ is altered to include a number of cavities  73 , preferably conical in shape, that simulate the emissivity of a black body. With either of the sensors of  FIG. 8  or  9 , it is the intensity of emissions of the surface in the infrared range that are detected by the photo-detector  35  of  FIG. 1  and measured by the system  37 . The excitation source  36  and beamsplitter  34  of  FIG. 1  are not used. The intensity is proportional to the temperature of the surface that is emitting the infrared radiation. 
         [0043]    A preferred form of a cartridge sensor according to any one of  FIGS. 4-9  is shown in  FIG. 10 . A sensor  81  includes an outer housing  55 ′ like the housing  55  of  FIGS. 4-7  but with threads  83  added to a portion of an outside surface. An opening in the chuck  17  is preferably configured to be completely filled by the sensor  81  and includes threads on an inside surface that mate with the threads  83  to firmly hold the sensor  81  in place within the chuck  17 . The threads are replaced with smooth mating surfaces, which are then glued together, when used within vacuum chambers in order to avoid pockets between the threads which can hold gases. Or, if threads are used in a vacuum application, the housing  55 ′ is sealed to the chuck  17  at its top surface to prevent the escape of such trapped gases into the processing chamber. An opening  85  extends through the chuck  17  from the opening receiving the sensor  81  as a conduit for the waveguide  41 . Rather than extending that waveguide continuously through the chuck  17 , however, it is terminated to form a short stub extending from the bottom of the sensor  83 . Another waveguide  87 , preferably in the form of an optical fiber, is inserted into the opening  85  to optically communicate with the waveguide  41  and extend to the detection and measurement equipment. A lens, as shown, is attached to the mating ends of each of the waveguide  41  and optical fiber  87  in order to more efficiently couple radiation between the two. An advantage of the configuration of the sensor  81  is that it can easily be installed and replaced in the chuck  17 . 
         [0044]    The general form of the sensors described is shown in  FIGS. 2 and 3  to operate with the substrate being carried directly by an upper surface of the chuck  17 . The temperature sensors described above also have other applications. In  FIG. 11 , for example, the substrate is held above the surface of the chuck  17  by posts  91  and  92 . A sensor  81 ′, like the sensor  81  but without the upper flange, extends above the chuck surface to position the sensor cap  43  above the dashed line that represents the lower surface of the substrate  15  when carried by the posts. The cap  43  is then pushed downward by the weight of the substrate when carried by the posts  91  and  92 , to make firm contact with the underside of the substrate. 
         [0045]      FIG. 12  illustrates use of two or more sensors  81  to additionally provide support for the weight of the substrate  15 . In this case, the resilient element within the sensor is made stronger than before so that the cap  43  is not pushed within the housing of the sensor. Some small degree of compression of the resilient element and rotation of the cap are desired in order to make firm thermal contact with an underside of the substrate. 
         [0046]    A different form of luminescent temperature sensor is shown in  FIGS. 13 and 14 . A test substrate  101 , preferably in the shape of a semiconductor wafer, flat panel display, or other substrate being processed, includes a temperature sensor  103  built into a substrate surface. A layer  105  of luminescent material is sealed within a recess of the substrate by an optically transparent window  107  made of an appropriate material such as sapphire. Excitation radiation is passed through the window to the luminescent material, and resulting temperature dependent luminescent radiation passes back through the window. 
         [0047]    Interrogation of the sensor  103  occurs by positioning appropriate optics to communicate with it while the substrate  101  is positioned within the processing chamber  11  ( FIG. 1 ) in the same manner as substrates that are being processed. An example is shown in  FIG. 15 , where the test wafer  101  is held by posts  91 ′ and  92 ′ above a chuck  17 ′. An optical fiber  33 ′, or other appropriate waveguide, terminates in an upper surface of the chuck  17 ′. The sensor  103  is within the field of view of the optical fiber  33 ′ when the test wafer  101  is properly positioned on the chuck  17 ′. Although use of posts  91 ′ and  92 ′ is shown, the wafer can be supported by the upper surface of the chuck  17 ′ with the sensor  103  being very close to, or in contact with, the end of the optical fiber  33 ′. In the course of processing a large number of substrates, such a test substrate is occasionally substituted for a substrate being processed in order to occasionally calibrate the substrate heating system within the chamber. 
         [0048]    In addition to the foregoing,  FIGS. 16 and 17  illustrate a temperature sensor  200  in contact with a substrate  202  at varying angles of separation. Referring to  FIG. 16 , the temperature sensor  200  is mounted within a chamber  204  such as a reactive gas and/or vacuum containment chamber used for processing materials such as semiconductors. The substrate  202  is supported by posts  206  or any other type of fixture used to securely mount the substrate  202  within the chamber  204 . The temperature sensor  200  is positioned under the substrate  202  in a manner whereby the temperature sensor  200  contacts the underside of the substrate  204 . The temperatures sensor  200  physically contacts the material to be measured and is similar to the temperature sensor  31  and other embodiments previously described. In this respect, the temperature sensor  200  may include a cap  43  that contacts the underside of the substrate  202 , a layer  49  of luminescent material, a resilient member  47  and an optical fiber  41  for the measurement of temperatures, as previously described. The temperature sensor  200  is attached to a shield  208  and a variable seal core  210  which is made from a material such as stainless steel that is resistant to the vacuum and reactive gases contained within the chamber  204 . As seen in  FIG. 16 , the core  201  is attached to an equipment mounting plate  212  and enters the chamber  204  through a seal-able opening oriented at an axial direction different than the axial direction of temperature sensor  200 . In this respect, the temperature sensor  200  is mounted at an angle generally orthogonal to the shield  208  and the core  210 . It will be recognized by those of ordinary skill in the art that the temperature sensor  200  can be oriented at any angle that allows contact with the underside of the substrate  204 . 
         [0049]    In order to communicate the optical signal from the temperature sensor  200 , an optical waveguide  216  is attached to the temperature sensor  200  and an optical connecter  214  outside of the chamber  204 . The optical connector  214  is attached to an optical reading device  220  such as processing element  27  as previously described. The optical waveguide  216  can be a fiber composed of sapphire or other materials that can efficiently transmit and contain optical energy. The optical waveguide  216  is protected from the environment of the chamber  204  by the shield  208  that is constructed from a thermal and optical energy reflective material such as aluminum. Because the shield  208  and the optical waveguide  216  are bent to position the sensor  200  on the underside of the substrate  202 , a thermally excited output signal from the sensor  200  proceeds down the waveguide  216  and changes axial direction while remaining within the waveguide  216 . The thermally excited signal then proceeds through the optical connector  214  to the reading device  220 . 
         [0050]    Referring to  FIG. 18 , a cross sectional view of a temperature sensor  300  is shown. The sensor  300  is used to measure the temperature of a substrate  302 . The sensor  300  can be positioned under the substrate as shown in  FIG. 18 , or in any position relative to the substrate whereat the sensor  300  can contact the substrate. A contact  304  constructed from a high temperature and reactive gas resistive material such as aluminum nitride is used to physically engage the substrate  302 . The contact  304  is formed and textured for thermal contact with the substrate  302 . Bonded within a cavity of the contact  304  is a thermographic (temperature-dependent luminescence properties) phosphor layer  306 . Alternatively, the cavity may also be coated with a black, high temperature tolerant material that radiates optically as a black body. The size and the shape of the contact  304  is determined such that thermal transmission away for the contact surface is minimized thereby allowing a sufficient percentage of the thermal power to be conductively transmitted to the phosphor layer  306 . 
         [0051]    As previously described for the temperature sensor of  FIG. 2 , the phosphor layer  306  emits optical radiation corresponding to the temperature of the substrate  302 . The optical radiation is coupled into a moveable fiber  308  that is fixedly adhered to the contact  304 . Specifically, the fiber  308  is adhered within the cavity of the contact  304  such that optical radiation from the phosphor layer  306  can be transmitted through the fiber  308 . In this regard, the fiber  308  can be adhered directly to the phosphor layer  306  or if a black body material is deposited within the cavity, the fiber  308  may be positioned an optimum distance from the black body material. The fiber  308  is adhered to the contact with a high temperature adhesive such as Cotronics Resbond 940 LE or any other low expansion, low out gassing adhesive. 
         [0052]    The contact  304  is fixedly attached to a resilient member  310  which is enclosed by a shield  312 . The resilient member  310  may be a spring manufactured from a high thermal and reactive gas resistant material. The resilient member  310  provides a biasing force against the contact  304  such that the contact  304  is urged toward the substrate  302 . Furthermore, the resilient member  310  allows the contact  304  rotational freedom to fully engage the substrate  302 . The resilient member  310  maybe manufactured from quartz, glassy carbon, nanotubes or other materials. The resilient member  310  provides variable axial positioning of the contact  304  of up to 10% in the axial direction such that the contact  304  maintains physical contact with the substrate  302  when the substrate  302  is moved or repositioned. Typically, the substrate  302  is held in position above the temperature sensor  300  during processing. Therefore, the contact  304  is urged downwardly by the substrate  302  and forced upwardly by the resilient member  310 . The downward force of the substrate  302  is greater than the biasing force of the resilient member  310  such that the resilient member  310  is compressed when the contact  304  physically touches the substrate  302 . 
         [0053]    As previously described, the moveable fiber  308  is fixedly attached to the contact  304 . Therefore, when the contact  304  is urged downward by the substrate  302 , the fiber  308  also moves downwardly. As seen in  FIG. 18 , if the resilient member  310  is a spring, the fiber  308  is inserted within the interior of the spring such that the fiber  308  is free to move in the axial direction unimpeded. The resilient member  310  and the fiber  308  are surrounded by a shield  312  made from a material such as alumina that is resistive to high temperature and reactive gasses. 
         [0054]    The end of the moveable fiber  308  that is opposite the end disposed within the cavity of the contact  304  is inserted into a guide  314 . The guide  314  is fixedly attached to the shield  312  and an extension  316 . The guide  314  and the extension  316  are formed from high temperature and reactive gas resistive materials such as alumina. The guide  314  contains a bore  318  through which the moveable fiber  308  is inserted into. Also disposed within the bore  318  is a fixed fiber  320  that is attached to the guide  314 . The fixed fiber  320  may be a silica-silica optical fiber, sapphire or other material of high optical transmissivity as is well known in the art. The moveable fiber  308  is axially moveable within the bore  318  such that a gap is formed between the ends of the moveable fiber  308  and the fixed fiber  320 . The gap between the moveable fiber  308  and the fixed fiber  320  varies depending on the axial position of the contact  304 . In this respect, as the contact  304  is moved downwardly, the gap between the moveable fiber  308  and the fixed fiber  320  decreases. Transmitted optical radiation can traverse the gap between the moveable fiber  308  and the fixed fiber  320 . In this respect, optical radiation from the moveable fiber  308  can be transmitted through the fixed fiber  320 . 
         [0055]    The fixed fiber  320  extends from the guide  314  to a ferrule  328  in the extension  316  that is rigidly attached to a mount  326 . The ferrule  328  provides a way to optomechanically couple the fixed fiber  320  to a device for measuring the signals transmitted therethrough. The ferrule  328  is attached to a base  322  made from a high temperature and reactive gas resistive material such as stainless steel. The base  328  forms a vacuum and reactive gas tight seal with the mount  326 . A keeper  324  is used to urge the base  328  against the mount  326  in order to provide the vacuum and gas tight seal. 
         [0056]    The materials of the temperature sensor  300  have thermal expansion properties to allow thermal expansion capability at relatively high temperatures. In this respect, the temperature sensor  300  can function at temperatures from −200 to 600 degrees centigrade. 
         [0057]    Referring to  FIG. 19 , another embodiment of a temperature sensor  400  is shown. The sensor  400  is similar to the sensor  300  and has a thermally conductive contact  402  which makes physical contact with a substrate (not shown). The contact  402  may have beveled or rounded corners  403  surrounding the surface thereof. By rounding the corners or edges of the surface of the contact  402 , it is easier to achieve face-to-face engagement between the surface of the substrate and the surface of the contact  402 . It will be recognized by those of ordinary skill in the art that the probes and contacts previously described can have beveled or rounded edges and corners. The rounded or beveled edges and corners  403  allow the contact  402  to slide into the best position for thermal contact with the substrate without hanging up on a relatively rough surface of the substrate. 
         [0058]    The contact  402  has a cavity  404  upon which a layer  406  of phosphorescent material or black body material is deposited. The contact  402  is attached to a moveable tip  408  that is inserted within a shield  412 . An adhesive layer  410  bonds the contact  402  to the tip  408 . 
         [0059]    Disposed within a cavity of the tip  408  is an optical fiber  416  that can transmit optical radiation from the layer  406 . In this respect, the optical fiber  416  is positioned at a distance whereby optical radiation generated by the layer  406  can be transmitted through the fiber  416 . 
         [0060]    The tip  408  is moveable within the shield  412  and is biased toward the substrate by a resilient member  414  such as a spring. The resilient member  414  urges the tip  408  toward an annular ledge  418  formed within the end of the shield  412 . A complementary mating surface  420  is formed in the tip  408 . The resilient member  414  biases the mating surface  420  against the ledge  418 . As can be seen in  FIG. 19 , the tip  420  comprises a barrel portion  422  that is disposed within an aperture  424  of the shield  412 . The aperture  424  is formed slightly larger than the barrel portion  422  so that the tip  408  can rotate in order to maintain optimal contact with the substrate. The annular ledge  418  and complementary mating surface  420  ensures that the tip  418  is maintained within the shield  412 . In order to ensure that the fiber  416  aligns with the phosphorescent material layer  406 , the fiber  416  is inserted into a fixed fiber guide  426 . 
         [0061]    Although the various aspects of the present invention have been described with respect to exemplary embodiments, it will be understood that the invention is to be protected within the fill scope of the attached claims. The temperature sensors previously described are ideally suited for different types of applications such as physical vapor deposition (PVD), dielectric etching, optical coating of glass substrates, chemical vapor deposition (CVD), metal organic chemical vapor deposition (MOCVD), low pressure chemical vapor deposition (LPCVD) and atomic layer deposition.