Page 1 of 14
`
`Samsung Exhibit 1010
`Samsung Electronics Co., Ltd. v. Daniel L. Flamm
`
`

`
`911.}678,5
`
`xm“NV
`
`.9mgcEmmmmS9
`
`WmWI_.nlII|HfluI:UW:IIIlI1_N.rInA
`
`‘
`
`Page 2 of 14
`
`

`
`Mar. 2, 1999
`
`Sheet 2 of 4
`
`5,876,119
`
`80
`
`OPTICAL _ FILTERS &
`SYSTEM 11 DETECTOR
`
`READOUT
`
`Page 3 of 14
`
`

`
`U.S. Patent
`
`Mar. 2, 1
`
`5,876,119
`
`_
`
`J ml
`
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`
`V!,..“_
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`
`“.
`
`Page 4 of 14
`
`

`
`5,876,119
`
`A .
`1
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`L1I
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`Page 5 of 14
`
`

`
`5,876,119
`
`1
`IN-SITU SUBSTRATE TEMPERATURE
`MEASUREMENT SCHEME IN PLASMA
`REACTOR
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`
`The present invention relates generally to devices and
`methods for making temperature measurements. More
`particularly,
`the present invention relates to devices and
`methods for measuring the temperature of a semiconductor
`substrate through non-contact arrangements utilizing a tem-
`perature sensitive member located adjacent the substrate to
`be measured.
`
`,,
`
`2. Background of tl1e Art
`The fabrication of semiconductor devices on substrates
`typically requires the deposition and etching of multiple
`metal, dielectric and other semiconductor film layers on the
`surface of a substrate. The film layers are typically deposited
`onto, and etched from, the substrates in vac11um chambers.
`Controlling the deposition and etch rate uniformity are
`critically important to the manufacture of integrated circuits.
`One of the parameters which must be tightly controlled
`during such deposition or etching process is the film
`temperature, which is particularly important for fabricating
`semiconductor multilayer structures from silicon (Si) or
`gallium arsenide (GaAs).
`It
`is also critical
`to obtaining
`high-TC (high critical temperature) superconductor film of
`optimal quality on a substrate.
`There are many methods currently used for temperature j
`measurement of the substrate or film layer. One common
`technique is to locate thermocouples thermistors or resis-
`ta11ce thermometers in the chamber to inferentially measure
`the substrate temperature. In some cases, the temperature
`measuring device has been embedded in the substrate sup-
`port where it
`is protected from the environment of the
`vacuum chamber. An electrical signal is generated by the
`device, which is then converted into temperature readings or
`employed for control functions.
`I11 certain situations, it is necessary or desirable to obtain
`temperature data by non-electrical
`techniques. This may
`occur: (1) where temperatures over large areas are to be
`measured and measurement by a dense distribution of ther-
`mocouples thus becomes impractical; (2) where the attach-
`ment of thermocouples and leads to the chamber would alter
`the temperatures to be measured; (3) in environments where,
`because of high electric or magnetic fields, metallic wires
`are undesirable; (4) where electrical isolation and/or insen-
`sitivity to electrical noise generation is desired; (5) where,
`because of motion or remoteness of the part to be sensed,
`permanent lead wires are impractical; or
`where, because
`of corrosive chemical environments, wires and thermo-
`couple junctions would be adversely affected, with resultant
`changes in electrical characteristics and erratic or erroneous
`temperature readings. For example, a plasma, such as used
`in chemical vapor deposition, can have an adverse effect on
`conventional
`temperature monitoring probes placed in
`physical contact with the substrate, and any contact between
`the probe and the substrate may cause substrate defects in
`the vicinity of the contact area. Such contact can cause
`high-density circuitry formed on the substrate near the
`contact area to be destroyed,
`thereby reducing substrate
`yield and the number of chips recoverable from a single
`substrate.
`
`The above considerations are important for determining
`production worthiness of processing tools used for adding
`and removing materials from semiconductor substrates. A
`
`2
`dielectric substrate formed of silicon or a III-V or II-IV
`compound, such as gallium arsenide or zinc telluride,
`is
`typically processed in a high-vacuum environment. This
`environment can have an adverse effect on conventional
`temperature monitoring probes placed in physical contact
`witl1 the substrate, and contact between the probe and the
`substrate may cause substrate defects in the vicinity of the
`Contact area. Such contact can cause high-density circuitry
`formed on the substrate near
`the contact area to be
`destroyed, thereby reducing substrate yield and the number
`of chips recoverable from a single substrate.
`Therefore, in some process situations, radiation pyrom-
`etry techniques are preferable since they measure the tem-
`perature of an object by means of the quantity and character
`of the energy which it radiates. These techniques can be
`applied to semiconductor manufacturing to avoid the prob-
`lems associated with temperature probes being in contact
`with the substrate. Therefore, optical pyrometers and light
`probes may be used to monitor substrate temperature by
`comparing the in—spectral intensity of the hot substrate with
`that of a source of standard intensity. To provide an accurate
`indication of substrate temperature from an optical
`pyrometer, the emissivity of the substrate must be known.
`With currently available pyrometer techniques,
`it is very
`difficult, if not impossible, to ascertain accurately emissivity
`of a semiconductor substrate undergoing processing for
`manufacture of integrated circuits. At temperatures below
`approximately 600° C, undoped silicon is transparent to
`infrared energy. As the temperature or doping level of the
`substrate increases, the substrate becomes less transparent to
`infrared energy. The decrease in transparency causes the
`emissivity of radiant energy that can be detected by an
`optical pyrometer to change in a fairly unpredictable inan-
`ner. Emissivity of optical energy from the substrate is also
`dependent on how rough the substrate emitting surface is. In
`addition, substrate emissivity as a whole is a function of
`material deposited on the face of the substrate in the optical
`pyrometer field of view. Since emissivity from the substrate
`is variable, the output of the optical pyrometer is frequently
`not an accurate indication of substrate temperature.
`Presently, the optical techniques used to measure tem-
`perature of a substrate require placement of a temperature
`sensitive material onto the backside of a substrate so that the
`decay of that material and light emissions associated there-
`with can be measured. A light probe is housed within the
`support member below the substrate receiving surface of the
`support member. The light probe excites the temperature
`sensitive material and causes it
`to emit radiation. The
`emitted radiation is quantified and compared with known
`temperature values. One drawback to this method is that it
`requires additional processing steps to be performed on the
`substrate prior to the continual formation of integrated
`circuits thereon. In addition to increased cost and time, the
`material deposited on the substrate for this purpose may
`jeopardize the integrated circuits ultimately formed on the
`substrate.
`
`U.S. Pat. No. 4,560,286, entitled “Optical Temperature
`Measurement Techniques Utilizing Phosphors”,
`Wickersheim, incorporated herein by reference, describes a
`method and apparatus for measuring the temperature of an
`object provided with a phosphor material layer that emits at
`least
`two optically isolatable wavelength ranges whose
`intensity ratio depends upon the object or environment
`temperature. The emitted radiation is quantified by ar1 opti-
`cal system that may include an optical fiber. One known
`application utilizing this art is the measurement of substrate
`temperature by providing a small amount of temperature
`
`Page 6 of 14
`
`

`
`5,876,119
`
`3
`sensitive material on the backside of the substrate. A light
`detecting member is provided within the substrate support
`member normal to the surface on which the temperature
`sensitive material is placed to measure the emitted radiation
`from the temperature sensitive material. Aprocessor quan-
`tifies the emitted radiation and determines the temperature of
`the substrate.
`
`5
`
`This technique, however, requires that the temperature
`sensitive material be placed on the backside of the semi-
`conductor substrate. This poses several problems. First, the
`phosphor material may migrate into the silicon substrate on
`which it is provided. Second, the process of applying the
`temperature sensitive material to the backside of the sub-
`strate requires additional processing steps which are both
`time consuming and expensive.
`Therefore, there exists a need for an apparatus and method
`for determining the temperature of a substrate during pro-
`cessing through a non-contact arrangement utilizing optical
`techniques which eliminate the need to deposit temperature _
`sensitive material on the substrate.
`
`SUMMARY OF THE INVENTION
`
`'
`
`Generally, the present invention provides an apparatus
`and method for determining the temperature of an object in
`situ through measurement of the temperature of an interme-
`diate member having a known thermal relationship with an
`adjacent surface of the object.
`In one aspect of the present invention, an apparatus is
`provided comprising a semiconductor substrate support
`member, an intermediate member, and a temperature mea-
`suring instrument. The intermediate member is located adja-
`cent
`the substrate support member in a passage defined
`between the support member and the substrate. The inter-
`mediate member has first and second surfaces positioned in
`a sufliciently close relationship between the adjacent sur-
`faces of the substrate support member and the substrate to
`have a known thermal relationship therebetween. It is pre-
`ferred that
`the apparatus is designed so that the thermal
`relationship is essentially that of free molecular thermal
`conduction. The temperature of the intermediate member
`can be measured with any temperature measuring instrument
`such as a thermocouple, thermistor, resistance thermometer,
`optical pyrometer, or
`radiation pyrometer.
`In one
`embodiment,
`the intermediate member may be provided
`with a temperature sensitive element on one surface, the
`temperature sensitive element characterized by emitting,
`when excited, detectable optical radiation that varies as a
`Known function of the material temperature.
`However,
`regardless of what
`temperature measuring
`instrument is used, knowing the temperature of the inter-
`mediate member and the support member enables the tem-
`perature of the substrate to be inferred. For any given
`combination of process conditions and spatial relationships
`between the substrate,
`intermediate member and support
`member, a calibration can be made by measuring the tem-
`peratures of the intermediate member and support member
`over a range of substrate temperatures.
`An alternative to using a calibration method, is to deter-
`mine the temperature of the object by application of the
`following equation:
`
`mot;
`m + or; — mug
`
`/\P(T; — T1)
`A1
`
`4
`—continued
`ago;
`(X2 + or; — (110.3
`
`where:
`n
`(X : accommodation factor for surface n
`
`A: free molecular thermal conductivity of the gas
`1’: gas pressure
`Tn: temperature of surface n
`A1: heat transfer area between substrate and intermediate
`member
`
`A2: heat transfer area between intermediate member and
`support member
`surface n=l: surface of object adjacent the intermediate
`member
`
`surface n=2: surface of intermediate member adjacent
`object
`surface n=2‘: surface of intermediate member adjacent
`support member
`surface n=3: surface of support member adjacent inter-
`mediate member
`Regardless of whether a calibration, equation, or both are
`used,
`it is instructive to use the equation as a basis for
`designing apparatus of the present invention having minimal
`measurement error. For example, in the situation where gas
`pressure and thermal conductivity above and below the
`intermediate member are equal and the top and bottom heat
`transfer surfaces of the intermediate member have equal
`areas,
`then the above equation becomes awpATwp=
`cL,,o,m,,,AT,,O,,o,,,. Therefore, when the intermediate member
`l1as a very high thermal conductivity so that the temperature
`of both surfaces will be substantially equal,
`i.e., T2 is
`substantially equal to T2, relative to measurement accuracy,
`and when the system is designed so that the accommodation
`factor of both sides is about equal, the intermediate member
`has a temperature of T2=(T1+T3)/2.
`invention, a method
`In another aspect of the present
`generally comprises the steps of providing an intermediate
`member in a space defined between an object to be measured
`and a second surface, measuring the temperature of the
`intermediate member and the second surface, and determin-
`ing the temperature of the substrate. The intermediate mem-
`ber is positioned in a su ‘iciently close relationship between
`the adjacent surfaces of the substrate support member and
`the substrate to have a known thermal relationship. It is
`preferred that the apparatus is designed so that the thermal
`relationship is essentia y that of free molecular thermal
`conduction. By measuring the temperature of the interme-
`diate member and the second surface, the temperature of the
`object can be inferred either through a calibration or by
`application of the equation above.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`So that the manner in which the above recited features,
`advantages and objects of the present invention are attained
`and can be understood in detail, a more particular descrip-
`tion of the invention, briefly summarized above, may be had
`by reference to the embodiments thereof which are illus-
`trated in the appended drawings.
`It is to be noted, however, that the appended drawings
`illustrate only typical embodiments of this invention and are
`therefore not to be considered limiting of its scope, for the
`invention may admit
`to other equally effective embodi-
`ments.
`
`Page 7 of 14
`
`

`
`5,876,119
`
`5
`FIG. 1 is a partial cross—sectional View of the chamber of
`the present invention having a temperature measuring appa-
`ratus including a substrate support member, an intermediate
`member, a light detecting member, and a semiconductor
`substrate to be measured;
`FIG. 2 is a cross—sectional View of an intermediate mem-
`ber of the present invention;
`FIG. 3 is a bottom View of an intermediate member of the
`present invention;
`FIG. 4 is a top view of a substrate support member
`showing two intermediate members positioned therein;
`FIG. 5 is a partial cross—sectional View of a processing
`chamber showing the placement of an intermediate member
`relative to the support member and substrate;
`FIG. 6 is a schematic diagram of an optical pyrometer
`system utilizing a temperature sensitive material and a light
`probe to provide a temperature reading of the temperature
`sensitive material; and
`FIG. 7 is a cross—sectional view of a preferred temperature "
`measuring apparatus of the present invention.
`DESCRIPTION OF A PREFERRED
`JJMBODIMEN'I'
`
`In order to achieve the benefits of the present invention,
`a11 inventive system can be configured for repeatedly or
`continuously measuring the temperature of a substrate 12
`based on the surface temperature of an intermediate member
`or puck 10 maintained in a sufliciently close relationship
`between the substrate 12 and a substrate support member 14 ’
`to have a known thermal relationship therebetween. It is
`preferred that the apparatus is designed so that the thermal
`relationship is essentially that of free molecular thermal
`conduction. By measuring the temperature of the interme-
`diate member and the second surface, the temperature of the
`object can be inferred either through a calibration or by
`application of a heat transfer equation.
`Referring to FIG. 1, a partial cross—sectional view of a
`chamber of the present
`invention having a temperature
`measuring apparatus including a substrate support member,
`an intermediate member, a light detecting member, and a
`semiconductor substrate to be measured is illustrated. Semi-
`conductor substrate 12 is illustrated as being located in
`integrated circuit processing chamber 11, maintained at the
`usual high vacuum level and including sources (not shown)
`of materials to be deposited on the substrate 12. The
`substrate 12 is supported within the chamber 11 on a
`substrate support member 14. The substrate support member
`14 is positioned in the lower portion of the chamber 11. To
`adhere the substrate 12 to the support 14, an electrostatic
`chuck or clamping arrangement may be employed.
`According to the present invention, an intermediate mem-
`ber 10 is located in a semiconductor processing chamber 11
`between the semiconductor substrate 12 and the substrate
`support member 14. The intermediate member 10 is located
`in a recess 18 formed in the support member 14. The recess
`18 is in fluid communication with the space 15 typically
`present between the substrate and its mounting surface
`wherein a gas, such as helium (He), is made to flow for the
`purpose of controlling the temperature of the substrate 12.
`Recess 18 houses the intermediate member 10 so that
`thermal energy is conducted through the gap 21 between the
`substrate 12 and intermediate member 10 during processing
`of the substrate. The use of the intermediate member 10
`eliminates the need to place a temperature measuring instru-
`ment in direct physical contact with the substrate or subject
`
`6
`the substrate itself to processing steps to locate a tempera-
`ture sensitive material
`thereon. Rather,
`the intermediate
`member 10 is formed with an integral temperature measur-
`ing instrument or in some other 111anner facilitating tem-
`perature measurement, such as having a temperature sensi-
`tive material 28 on its lower surface in cooperation with a
`light probe 3 positioned within the channel 17.
`
`Thermal energy is also conducted through the gap 16 from
`the intermediate member to the substrate support member
`14. The temperature of the substrate receiving surface of the
`support member 14 is measured by any temperature mea-
`suring device, such as a temperature sensitive material 29
`and light probe 33.
`It
`is preferred that
`the temperature
`measuring device be protected from the process environ-
`ment in chamber 11. For this reason, the device is shown
`positioned in a channel 34 (partially shown) through the
`support member 14.
`
`In applications where substrate temperature is controlled
`by thermal conduction via low density gas in the narrow gap
`15, typically defined as the space between the substrate 12
`and the substrate mounting surface of the support member
`14, the intermediate member 10 is located in fluid commu-
`nication with the low density gas in recess 18. Recess 18 is
`in fluid communication with narrow gap 15. The interme-
`diate member 10 and the substrate mounting surface of the
`support member 14 are preferably designed with substan-
`tially planar surfaces in substantially parallel planes so that
`heat transfer between adjacent surfaces will occur substan-
`tially uniformly over the entire surface area. The adjacent
`surface areas for heat transfer, i.e., acceptance and release of
`heat between the substrate 12 and intermediate member 10
`(hereinafter referred to as A1) and the area for heat transfer
`between the intermediate member 10 and the support mem-
`ber 14 (hereinafter referred to as A2) are largely a matter of
`design choice, but will be fixed at a known amount for
`purposes of calibration and/or use in a heat transfer equation.
`It is preferred that Al and A2 be substantially equal and as
`large as practical. Furthermore, the distance between the
`substrate 12 and the intermediate member 10 (hereinafter
`referred to as dl) and the distance between the intermediate
`member 10 and the support member 14 (hereinafter referred
`to as dz) are largely a matter of design choice, but will be
`fixed at a known amount. It is preferred that d1 and d2 be
`substantially the same and as small as practical in order to
`minimize error in the determination of substrate tempera-
`ture. It is most preferred that (11 and d2 be on the order of the
`mean free path of the gas in the chamber during processing.
`
`When a gas having good thermal conductivity is used,
`such as helium having a thermal conductivity of about
`2.93><l0’2 (Watts/cmz)/(°K’torr), a substrate 12 positioned
`adjacent the intermediate member 10 approaches a steady
`state temperature within a period of time that is short relative
`to the substrate processing period, typically on the order of
`a few seconds. Under conditions of free molecular thermal
`conduction, i.e., when d1 and d2 are less than the mean free
`path of the gas (d1<;\., d2<7»),
`the steady state thermal
`condition of the present apparatus can be expressed by
`Equation (1):
`
`oc1oL;
`0.1+ (X2 — (x1cLg
`
`AP(T; — T1)
`A1
`
`Equation (1)
`
`oL;‘oL3
`org‘ + a3 — oL;‘oL3
`
`/\(T3 — T2‘)
`Ag
`
`Page 8 of 14
`
`

`
`5,876,119
`
`where:
`
`7
`
`or": accommodation factor for surface n
`A: free molecular thermal conductivity of the gas
`1’: gas pressilre
`Tn: temperature of surface n
`A1: heat transfer area between substrate and intermediate
`member
`
`A2: heat transfer area between intermediate member and
`support member
`surface n=l: surface of object adjacent the intermediate
`member
`
`surface n=2: surface of intermediate member adjacent
`object
`surface n=2‘: surface of intermediate member adjacent
`support member
`surface n=3: surface of support member adjacent inter-
`mediate member
`In applications where the gas pressure and thermal con- N
`ductivity above and below the intermediate member area
`equal, the accommodation factors are constant and the top
`and bottom heat transfer surface areas of the intermediate
`
`member are Known, then the Equation
`as shown in Equation (2):
`
`can be simplified
`
`T2 — T.
`rs — T2’
`
`AT,
`7 Azmm
`
`or as shown in Equation (3):
`
`Equation (2)
`
`aX0PA1X0p=ab0fXD7MA1lb0XXOIfl
`
`Equation (38,)
`
`Therefore, when the intermediate member has a very high
`thermal conductivity so that the temperature of both surfaces
`will be substantially equal, i.e., T2 is substantially equal to
`T2 relative to measurement accuracy, the temperature of the
`intermediate member 10 will be a temperature between T1
`and T2 according to the ratio of overall accommodation
`factors, rxwpabonom.
`When the temperature measurement according to the
`present invention is performed under high pressure, i.e., the
`distances d1 and d2 are greater than the mean free path of the
`gas (d1>}., d2>}t), then he at transfer between the substrate 12
`and the intermediate member 10 becomes insensitive to gas
`pressure and becomes an inversely linear function of dis-
`tance according to Equation (4):
`
`?\.(T3 — T2’)
`MT; — T1)
`T =F
`
`Equation (4)
`
`Therefore, when the surface areas are equal and the
`distances are fixed, the thermal condition of the apparatus in
`a high pressure gas can be expressed by Equation (5):
`
`(ll
`2
`d— = Constant
`
`Equation (1)
`
`Referring now to FIG. 2, a cross-sectional view of an
`intermediate member 10 of the present invention. Interme-
`diate member 10 is comprised of a thin disk 23 having high
`thermal conductivity and thus a small temperature difference
`across its surfaces. On the lower surface of disk 23, a
`reflective layer 26 such as aluminum or gold is formed
`thereon. A dot of temperature sensitive material 28, such as
`a phosphor, is centered on the lower surface of the reflective
`layer 26. An encapsulation layer 30 may be formed over the
`temperature sensitive material 28 to prevent the material 28
`from being exposed to the vacuum environment. The layer
`
`8
`30 is preferably comprised of a dielectric, such as sapphire
`or diamond. Sapphire and diamond have been found to
`provide corrosion resistance at high temperatures and pre-
`vent eddy currents from heating the temperature sensitive
`material.
`Referring now to FIG. 3, a bottom view of the interme-
`diate member 10 is shown. Reflective layer 26 is the first
`layer formed on the lower surface of the disk 23 (see FIG.
`2). Temperature sensitive material 28 is formed on reflective
`layer 26. The temperature sensitive material, such as a
`phosphor compound, may be suspended in an organic
`binder, a silicone resin binder or a potassiiun silicate binder.
`Some of these binders may be the vehicle for a paint which
`can be maintained in a liquid state until thinly spread over
`the surface of the reflective layer 26 where it will dry and
`hold the phosphor on the surface in heat conductive contact
`with it. A clear encapsulation layer 30 (see FIG. 2) is then
`formed over reflective layer 26 and temperature sensitive
`material 28 to protect the material from the vacuum envi-
`ronment.
`Referring now to FIG. 4, a top view of a substrate support
`member 14 shows two intermediate members 24, 25 posi-
`ioned therein. The intermediate members 24, 25 are located
`within recesses 18, 19 in the support member. Preferably
`here are two recesses formed in the support member 14.
`One recess 18 is typically formed in the center portion of
`substrate support member 14 and one recess 19 is located in
`he outer portion of support member 14. This arrangement
`allows the temperature of the substrate to be measured both
`at an inner portion of the substrate as well as an outer portion
`of the substrate. While two intermediate members 24, 25 are
`areferred, any number and arrangement is contemplated by
`he present invention.
`Referring again to FIG. 1, a preferred method of the
`vresent invention will be generally described. The substrate
`12 for which the temperature is to be measured is introduced
`into chamber 11 by a robot (not shown) and positioned on
`he substrate support member 14. Located between a portion
`of the substrate 12 and support member 14 is disk member
`10 having temperature sensitive material 28 located on the
`lower surface thereof. A light pipe 31 is positioned within
`channel 17 of the support member 14 normal to the surface
`of temperature sensitive material 28. One light detecting
`apparatus used to advantage in the present
`invention is
`available from Luxtron Corporation, Santa Clara, Calif.,
`model no. 790.
`The intermediate member 10 preferably has a phosphor
`coating 28 over at least a portion thereof. The phosphor is
`characterized by emitting, when excited, electromagnetic
`radiation within separable band widths at
`two or more
`distinct wavelengths and with relative intensities in those
`bands that vary as a known function of the temperature of
`the phosphor 28. Thus, the temperature of the phosphor 28
`that is detected is substantially the same as or related to that
`of the substrate as previously described.
`Referring now to FIG. 5, a partial cross-sectional view of
`a processing chamber shows the placement of an interme-
`diate member relative to the support member and substrate.
`The intermediate member 10, dielectric material 22 and
`support member 14 are positioned below substrate 12 within
`a process chamber 11. A temperature sensitive material 28,
`such as a phosphor, is formed on the surface of the inter-
`mediate member 10 to emit electromagnetic radiation in
`cooperation with an optic cable 31. The optic cable 31 has
`a light receiving end 37 and is capable of transmitting the
`light or radiation to a processor 35 for determining the
`temperature of the temperature sensitive material 28. It
`should be recognized that the optic cable may following any
`convenient path through the support member 14 to the
`processor 35.
`
`Page 9 of 14
`
`

`
`5,876,119
`
`'7
`
`9
`luminescent emission of the
`Now referring to FIG. 6,
`phosphor 28 in the form of electromagnetic radiation, gen-
`erally in or near the visible spectrum, is excited by a source
`60 over a path 61. The source could he radioactive material,
`a source of cathode rays, an ultraviolet electromagnetic
`energy source, or any other remote source producing effi-
`cient fluorescence depending upon the particular type of
`phosphor utilized in the preferred forms of the present
`invention. The relative intensities of two distinct wavelength
`bands within the emitted radiation 41 contains the desired
`temperature information.
`The emitted radiation 41 is gathered by an optical system
`80 and directed in a form 81 onto an optical filter and
`radiation detector block 100. The block 100 contains filters
`to isolate each of the two bands or lines of interest within the
`emitted radiation that contain the temperature information.
`After isolation, the intensity of each of these bands or lines
`is detected wl1icl1 results i11 two separate electrical signals in
`lines 101 and 102, one signal proportional to the intensity of
`the radiation in one of the two bands and the other signal
`proportional to the intensity of the radiation in the other of
`the two bands of interest. These electrical signals are then
`applied to an electronic signal processing circuit 120. In a
`preferred form, the signal processing circuits 120 take a ratio
`of the signals in the lines 101 and 102 by the use of routinely
`available circuitry. This electronic ratio signal
`is then
`applied to a signal processor within the block 120. The
`signal processor is an analog or digital device which con-
`tains the relationship of the ratio of the two line intensities
`as a function of temperature for the particular phosphor 28 .
`utilized. This function is obtained by calibration data for the
`particular phosphor 28. The output of the signal processor
`121 is representative of the temperature of the phosphor 28
`and may be displayed on a readout device 140. The device
`140 could be any one of a nur11ber of known read out
`devices, such as a digital or analog display of the tempera-
`ture over some defined range. The device 140 could even be
`as elaborate as a color encoded television picture wherein
`each color represents a narrow temperature range on the
`object. It could also be a television picture stored on disc or
`tape. It 111ight also be a chart recorder or the input to a
`chamber/process control system.
`Referring back to FIG. 1, substrate 12 has a lower surface
`with a te111perature, T1. The intermediate member or disk 10
`has upper surface temperature, T2, and lower surface
`temperature, T2. Watts Recess 18 has lower surface
`temperature, T3, adjacent the lower surface of disk 10 having
`temperature T2.. Disk 10 is supported in recess 18 on
`dielectric member 22. The dielectric member 22 holds the
`intermediate member 10 above the surface of the support
`member 14 having temperature T3.
`In order to measure the temperature of substrate 12, the
`temperature of disk 10 is determined by measuring emitted
`radiation from temperature sensitive material 28. The tem-
`perature of substrate 12 can be determined from the tem-
`perature measured on the lower surface T2.. of disk 10 and
`T3 of support member 14. The temperature of substrate 12
`is related to the temperature of the disk 10 by equation (1),
`above.
`Referring now to FIG. 7, a cross—sectional View of a
`preferred temperature measuring apparatus of the present
`invention is shown. The intermediate member 40 has ped-
`estal 42 that elevates the intermediate member 40 above the
`support member 14 and dielectric 43. The amount of heat
`conduction from intermediate member 40 to the dielectric 43
`is minimized by reducing the degree of contact therebe—
`tween. While pedestal 42 effectively reduces the degree of
`
`10
`contact between the member 40 and the dielectric 43, it
`should be recognized that the pedestal 42 must hold the
`intermediate member 40 firmly ir1 place. Because the dis-
`ances between the substrate 12, intermediate member 40
`and support 14 are critical variables in the determination of
`he substrate temperature T,, as described above, the lower
`edge of pedestal 42 must be reliably and accurately secured
`onto the seat 44 of dielectric 43. It is preferred that the
`Jedestal 42 be joined by bo11ding to dielectric 43 along the
`side surface 46 rather than the seat 44 so that there is no
`chance that the bonding material will tilt or elevate the
`Jedestal 42 and intermediate member 40. Any excess glue
`from side surface 46 will be forced either above the dielec-
`ric 43 or into the channel 48 located at the base of side
`surface 46. In this manner, the intermediate member 40 is
`secured to the dielectric 43 without jeopardizing the desir-
`ably tight tolerances. Furthermore, direct contact between
`he dielectric 43 and the support member 14 l1as been
`reduced by incorporating a gap 50 to minimize heat con-
`duction into the support member 14.
`PREFERRED l’H()S1’HOR MATERLALS AND CHARAC-
`TERISTICS
`The fundamental characteristics of a preferred phosphor
`material for use in the present
`invention is that when
`properly excited it emits radiation in at least two different
`wavelength ranges that are optically isolatable from one
`another, and further that the relative intensity ofthe radiation
`emitted within each of these at least two wavelength ranges
`varies as a function of the phosp