.
`
`United States PBtGIlt [19]
`Moslehi
`
`US005192849A
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,192,849
`Mar. 9, 1993
`
`[54] MULTIPURPOSE LOW-THERMAL-MASS
`CHUCK FOR SEMICONDUCTOR
`PROCESSING EQUIPMENT
`[75] Inventor: Melirdad M. Moslelu, Dallas, Text.
`[73] Assignee: Tens lumen“ Mum-119d,
`'
`Dallas, Tex.
`-
`
`[21] App!‘ NO‘: 565765
`[22] Filed:
`Aug. 10, 1990
`
`[56]
`-
`
`00
`Int. GL5 .............................................. ea
`[52] US. Cl. ........ .t .............. .. 219/ 121.43; 219/ 121.49;
`219/1214; 219/158; 156/345
`[58] Held of Search ...... .. 219/ 121.43, 121.4, 159-161,
`219/1214‘); 156/345’ 643' 646; 427/34;
`313/ 11111’ 11131, 111-51
`References Cited
`
`~
`us‘ PATENT DOCUMENTS
`4,361,749 11/ 1982 Lord ............................. .. 219/ 121.43
`4,430,547 2/1984 Yoneda et a1. ..
`..
`4,565,601 1/1986 Kakchi et al ------ --
`4,631,106 12/1986 Nakazato et a1.
`4,886,571 12/1989 Suzuki et a1. ...... ..
`4,971,653 11/1990 Powell et a1. ..................... .. 156/345
`Primary Examiner-Mark H. Paschall
`
`Attorney, Agent, or Finn-Stanton C. Braden; Richard
`L. Donaldson; William E. Hiller
`[57]
`ABSTRACT
`A multipurpose IOWthCrmaLm ndiwfrequency
`chuck for semiconductor device processing equipment
`(18) and applicable to plasma processing over a wide
`range of substrate temperatures. The stacked multilayer
`chuck structure comprises process vacuum base plate
`(16). heating module (48), cooling module (44) and
`radio-frequency power plate (50). Vacuum base plate
`provid?
`support
`fecd
`throughs (RF power connection, molmt inlet/outlet,
`heater wires and thermocouple) for main chuck (20).
`wammoled v‘cuum base plate (15) is thermally insu.
`lated from main chuck module (20). Heating element
`(48) comprises top layer (so) of electrical insulation and
`passivation, power heating resister (82), bottom layer of
`electrical insulation (84) and heater substrate (86) made
`of boron nitride or quartz or SiC-coated graphite. Cool
`ant module (44) comprises a plurality of coolant tunnels
`and is made of a high thermal conductivity material
`(nickel-plated copper, aluminum or a suitable refractory
`metal. Radio-fr uenc late 50 com rises a refrac
`)
`eq
`y p
`(
`)
`p
`tory metal or aluminum material.
`
`25 Claims, 11 Drawing Sheets
`
`10
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`IAGNETRW MlXlULE Fm PLASMA DHANGIENT All) WENT
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`LAM Exh 1003-pg 1
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`

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`US. Patent
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`Mar. 9, 1993
`
`'
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`Sheet 1 of 11
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`‘5,192,849
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`FIG. 1
`
`0/
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`MAGNETRON MODULE FOR PLASMA ENHANCDAENT AND CONFINEMENT
`
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`U.S. Patent
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`Mar. 9, 1993
`
`Shget 2 of 11
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`5,192,849
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`CXJTLET 2
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`INLET 2
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`K’
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`78
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`28
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`LAM Exh 1003.-pg 3
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`LAM Exh 1003-pg 3
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`

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`US. Patent
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`Mar. 9, 1993
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`Sheet 3 of 11
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`5,192,849
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`LAM Exh 1003-pg 4
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`US. Patent
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`Mar. 9, 1993
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`Sheet 4 of 11
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`5,192,849
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`OUTLET1 ‘
`
`GAS
`INLET 2
`WATER
`INLET 1
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`OUTLET 1
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`US. Patent
`
`Mar. 9, 1993
`
`Sheet 5 of 11
`
`5,192,849
`
`FIG. 7
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`MAGNETRON MODULE FOR PLASMA ENHANCEMENT AND CONFINEMENT
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`US. Patent
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`Mar. 9, 1993
`
`Sheet 6 of 11
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`5,192,849
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`88
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`LAM Exh 1003-pg 7
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`

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`US. Patent
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`Mar. 9, 1993
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`Sheet 7 of 11
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`5,192,849
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`U.S. Patent
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`Mar. 9, 1993
`
`Sheet 8 of 11
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`5,192,849
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`

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`US. Patent
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`Mar. 9, 1993
`
`Sheet 9 of 11
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`5,192,849
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`122
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`FIG. 13 134
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`LAM Exh 1003-pg 10
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`US. Patent
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`Mar. 9, 1993
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`Sheet 10 of 11
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`5,192,849
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`FIG. 14 '
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`

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`US. Patent
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`Mar. 9, 1993
`
`Sheet 11 of 11
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`‘5,192,849
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`FIG. 15
`
`N‘lllllllll's
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`LAM Exh 1003-pg 12
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`

`
`1
`
`MULTIPURPOSE IDW-Tl'IERMAL-MASS CHUCK
`FOR SEMICONDUCTOR PROCESSING
`EQUIPMENT
`
`15
`
`25
`
`v5,192,849
`,
`2
`via its interactions with the process chamber walls and
`the plasma electrodes.
`The combined effects of plasma-induced surface dam
`. age and contamination produce semiconductor devices
`with less than optimal performance characteristics and
`limit fabrication process yield. Thus, with conventional
`plasma-assisted processing techniques, increasing RF
`power to increase plasma density with the intent to raise
`the process rate can have serious detrimental effects. If
`a method existed, however, to increase the plasma den
`sity and ion flux without also significantly increasing
`ion energies, then a manufacturer may increase plasma
`assistcd processing rates.
`Therefore, a need exists for a method and apparatus
`to increase plasma density near a semiconductor wafer
`during plasma-assisted processing without at the same
`time increasing ion energy levels.
`As indicated before, another limitation of conven
`tional plasma-assisted processes derives from the fact
`that, during these processes, plasma disperses through
`out the fabrication process chamber. In so doing, it
`interacts with the process chamber walls. These walls
`contain various metals that the activated plasma species
`can remove, transport to a semiconductor substrate
`surface, and embed into the semiconductor devices. As
`a result, further semiconductor device performance and
`reliability degradation occurs.
`Consequently, there is a need for a method and appa
`ratus to prevent plasma interaction with fabrication
`reactor process chamber walls during plasma-assisted
`processing.
`To remedy the above problems, manufacturers often
`use a special type of plasma-assisted processing known
`as “magnetron-plasma-enhanced” (MPE) processing.
`MPE processing basically entails crossing a magnetic
`?eld with an electric ?eld in the proximity of a semicon
`ductor substrate during plasma processing. The crossed
`magnetic and electric ?elds cause the plasma to appear
`as a gaseous ball enveloping the semiconductor wafer
`and centered therewith. As a result, the plasma ion
`density is greatest around the semiconductor wafer.
`The plasma that the semiconductor substrate sees,
`therefore, does not interact signi?cantly with the pro—
`cess chamber walls. MPE processing also provides
`improved gas excitation and higher plasma density than
`with the conventional plasma-assisted processes. MPE
`processing raises the device processing rate and reduces
`semiconductor device degradation from plasma
`induced contaminants by making the plasma medium
`concentrate near the semiconductor substrate. Thus,
`MPE processing can produce higher semiconductor
`device processing rates without having to increase the
`local plasma ion energies.
`The electric ?eld for the magnetron-plasma-enhance
`ment can be the result of either an externally applied
`DC bias or, alternatively, a self-induced plasma DC bias
`produced on a radio frequency (RF) power source
`coupled to the wafer stage and the plasma medium.
`Coupling an RF power source to the wafer stage results
`in the formation of an electric ?eld perpendicular to the
`wafer surface across the plasma sheath and produces
`the EXD magnetron effect (in the presence of a trans
`verse magnetic ?eld). Conventional chucks for RF
`plasma processing, however, suffer from numerous
`limitations.
`Conventional RF chucks used for plasma processing
`in a semiconductor device fabrication chamber use an
`
`TECHNICAL FIELD OF THE INVENTION
`The present invention relates in general to a multipur
`pose low-thermal-mass chuck for semiconductor pro
`cessing equipment, and more particularly to a method
`and apparatus for producing radio-frequency plasma,
`wafer heating, and wafer cooling in plasma processing
`applications (etch, deposition, annealing, and surface
`cleaning).
`BACKGROUND OF THE INVENTION
`Manufacturers of electronic components use a vari
`_ ety of techniques to fabricate semiconductor devices.
`One technique that has many applications is known as
`“plasma-assisted” processing. In plasma-assisted pro
`cessing, a substantially ionized gas, usually produced by
`a radio-frequency electromagnetic gas discharge, pro
`vides activated neutral and ionic species that chemically
`react to deposit or to etch material layers on semicon
`ductor wafers in a fabrication reactor. Reactive-ion
`etching (RIE), an example of plasma-assisted processes,
`uses the directional and energetic ions in a plasma to
`anisotropically etch a material layer. RIE can take place
`in a conventional parallel-electrode plasma processing
`equipment or similar semiconductor device fabrication
`reactor.
`Applications of plasma-assisted processing for semi
`conductor device manufacturing include RIE process
`a ing of polysilicon, aluminum, oxides, and polyimides;
`plasma-enhanced chemical-vapor deposition (PECVD)
`35
`of dielectrics, aluminum, and other materials; low-tem
`perature metal-organic chemical-vapor deposition
`(MOCVD) of metals including aluminum and copper;
`low-temperature dielectric chemical-vapor deposition
`for planarized interlevel dielectric formation; and low
`temperature growth of epitaxial semiconductor layers.
`In RIE, a high-energy radio-frequency (RF) power
`source is applied across two parallel electrodes to pro
`duce a plasma via electrical gas discharge. Conven
`tional plasma processes such as RIE, impose a trade-off
`between processing rate and semiconductor device
`45
`quality. To increase the RIE processing rate requires
`greater plasma density and/or ion flux. The plasma
`density and ion ?ux can be increased by raising the
`electrical RF power absorbed within the plasma me
`dium. Increasing the RF power to the plasma medium,
`however, raises the plasma ion energy levels. Ions with
`excessive energies may damage semiconductor devices.
`This is because the ions can be so energetic (hundreds of
`electron volts) that upon impact they penetrate and
`cause irradiation damage to the semiconductor device
`surface. When this type of ion radiation damage occurs,
`a post'etch surface cleaning and/or annealing process is
`necessary to
`the adverse effects to the semi
`conductor device performance. Some RIE processes
`may also leave undesirable chemical deposits such as
`?uorohydrocarbons on the semiconductor device sur
`face. Ultimately, the manufacturer must remove these
`deposits from the semiconductor device in order to
`prevent degradation of device fabrication yield. Due to
`lack of plasma con?nement, the conventional plasma
`65
`processing techniques may introduce various contami
`nants (e.g., metals into the semiconductor substrate. The
`contaminants can be transferred by the plasma medium
`
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`equipment for applications such as chemical-vapor de
`RF electrode to generate the plasma. These devices
`position (CVD) and RF plasma processing of a semi
`usually have a large thermal mass and do not possess
`conductor wafer. The stacked chuck structure com
`capability to operate over a wide range of temperatures.
`prises a coolant module for extracting heat from the
`As a result, they have associated long thermal heat-up
`semiconductor device, a heating element adjoining the
`and cool-down transient times and cause substrate tem
`perature nonuniformities during heating and cooling.
`coolant module for heating the semiconductor device.
`A radio-frequency plate for associating an electromag
`During MPE processing, temperatures within a fabrica
`netic radio-frequency power source with the semicon
`tion reactor can range from —- 150‘ C. to +750’ C. (The
`conventional RF plasma chucks can usually operate
`ductor wafer, and a vacuum base plate for mechanical
`either in the lower temperature range (e.g., 0' C. to 200‘
`support and providing vacuum seal to a process cham
`C. for plasma etch processes) or in the medium tempera
`ber.
`Another aspect of the present invention includes a
`ture range (for temperatures up to 450' C. for plasma
`plasma processing radio-frequency chuck for magne
`deposition processes). The conventional RF plasma
`tron-plasma-enhanced processing of a semiconductor
`chuck devices are not multipurpose and are usually
`wafer. The radio-frequency chuck comprises a coolant
`incompatible with external magnetron sources. Ad
`vanced anisotropic etch processes can greatly bene?t
`module (stacked or sandwiched between two electri
`cally insulating and thermally conducting boron nitride
`from very low or cryogenic substrate temperatures (as
`disks) for extracting heat from the semiconductor wa
`low as - 150' C.) due to elimination of lateral etch (no
`fer, a heating element adjacent to the coolant module
`etch undercut) and enhanced etch selectivity. More
`for heating the clamped semiconductor substrate, a
`over, magnetron-plasma enhancement (with or without
`radio-frequency plate for associating an electromag
`cryogenic substrate temperature) provides additional
`process improvements. Magnetron-plasma-enhanced
`netic radio-frequency power source with the semicon
`(MPE) cryogenic processing may also have important
`ductor wafer, and a vacuum base plate for mechanical
`applications for deposition of thin ?lms. MPE process
`support and providing vacuum seal to an MPE process
`ing chamber. The coolant module includes a plurality of
`ing at higher temperatures (100° C. up to 750° C.) has
`important applications for thin-?lm (e.g. metal) deposi
`coolant tunnels for permitting a liquid or gas coolant to
`tion and plasma annealing. Capabilities for rapid wafer
`flow and cool the semiconductor wafer. The heating
`temperature cycling and uniform wafer heating and
`element has a top layer of electrical insulation and pas
`sivation. Beneath the top layer a power resistor made of
`cooling over a wide range of temperatures (— 150° C. to
`750' C.) are essential for device fabrication throughput
`a thin refractory metal ?lm generates thermal energy to
`and yield. Conventional chucks do not provide all these
`heat the semiconductor substrate. A bottom layer of
`electrical insulation and adhesion ?lm adjoins the top
`capabilities together. As a result, there is a need for
`layer and power resistor and seals the power heating
`multipurpose RF chuck having a low thermal mass for
`rapid semiconductor wafer heating and cooling times.
`resistor therebetween. Additionally, a metallic or
`graphite wafer adjoins the coolant module (with a
`There is also a need for an MPE processing RF chuck
`that provides uniform wafer heating and cooling during
`boron nitride buffer wafer placed in between) and struc
`turally supports the stacked chuck elements. The radio
`both transient and steady-state conditions, and strong
`frequency plate can be made of a silicon-carbide-coated
`magnetic ?eld at the substrate surface using an external
`graphite wafer or various metals for coupling a radio
`magnetron source.
`.
`frequency electromagnetic power to the semiconductor
`Other limitations associated with the conventional
`RF chucks for MPE processing include limited operat
`wafer surface. The radio-frequency chuck of the pres
`ing temperature ranges and limited magnetic ?eld trans
`ent invention has a thickness of less than 1.25" (total
`thickness including the vacuum base plate).
`mittance values. As temperatures exceed 500° C.,
`The RF chuck of the present invention is low thermal
`known RF chucks overheat and suffer from component
`and performance degradation. Conventional RF chucks
`mass and multipurpose because it not only allows RF
`45
`biasing of the substrate, but it also beats and cools the
`also fail at very low or cryogenic temperatures. Thus,
`semiconductor wafer with rapid thermal transients over
`there is a need for an MPE processing RF source that
`a wide range of temperatures. Because it can perform
`possesses extended temperature ranges of — 150° C. up
`to 750‘ C. with negligible component or performance
`these three functions, the RF chuck of the present in
`degradation.
`vention greatly enhances the performance and applica
`tion domain of the semiconductor device processing
`Known RF chucks also suffer from a large compo
`chamber. This can also increase MPE processing uni
`nent thickness (e.g., over two inches) that necessarily
`formity and throughput and semiconductor device fab
`places the semiconductor substrate a distance from an
`rication yield.
`external magnetron module. A thinner RF chuck would
`A technical advantage of the RF chuck of the present
`permit placing a semiconductor wafer closer to the
`magnetron, thus allowing either a smaller and less ex
`invention is that it has a low thermal mass for rapid
`semiconductor wafer heating and cooling. The low
`pensive magnetron or a greater magnetic ?eld strength
`and process uniformity for an optimal MPE effect. A
`thermal mass of the RF chuck and the con?guration of
`the coolant block and power resistor plate ensures that
`need exists for an RF chuck having a smaller thickness
`the chuck uniformly heats and cools the semiconductor
`device both during transient and steady-state conditions
`within the fabrication reactor.
`Another technical advantage of the RF chuck of the
`present invention is that it possesses an extended tem
`perature range of operation relative to known RF
`chucks. The RF chuck can operate at temperatures in
`the range of — 150' C. to 750' C. with negligible com
`ponent or performance degradation.
`
`SUMMARY OF THE INVENTION
`According to one aspect of the present invention,
`there is provided a multipurpose low-thermal-mass ra
`die-frequency chuck for semiconductor processing
`
`55
`
`than that of conventional devices in order to the distance between a semiconductor substrate and an
`
`MPE module and, as a result, enhance the MPE process
`uniformity and throughput.
`'
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`25
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`LAM Exh 1003-pg 14
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`present invention with a different boundary arrange
`Yet mother technical advantage of the present inven
`ment and termination of the magnets at the periphery of
`tion is that it is based on a stacked multilayer design and
`the circular magnetic assembly;
`is a thinner device than known RF chuck for plasma
`FIG. 10 shows a cross-sectional view of the preferred
`and MPE processing. This results in a minimal spacing
`embodiment of the magnetron module shown in
`betweena semiconductor substrate within the plasma
`FIG. 8 (along the A-A and B—B axes);
`process chamber and an external magnetron module.
`FIG. 11 shows a cross-sectional view of the preferred
`This feature results in an increase in overall MPE pro
`embodiment of the magnetron module shown in FIG. 9
`cessing rate and improved process uniformity.
`(along the A-A and 8-8 axes);
`Another technical advantage of the present invention
`FIG. 12 shows an alternative embodiment of the
`is that it is easily scalable for semiconductor wafer sizes
`magnetron module of the present invention using a
`larger than the conventional 150 mm wafers (e.g. 200
`distributed grid magnetic array;
`mm and larger). Also, the RF chuck of the present
`invention is compatible with single-wafer plasma pro‘
`FIG. 13 is an alternative embodiment of the magne
`tron module of the present invention using a distributed
`cessing reactors and various magnetron plasma modules
`square magnetic array;
`thereby making it more useful and functional than many
`FIG. 14 shows an alternative embodiment of the
`known RF chucks that can only be used with a limited
`magnetron module of the present invention using a
`number of processing equipment con?gurations. A
`cylindrical concentric-ring magnetic array; and
`manufacturer can expect the RF chuck of the present
`FIG. 15 is an alternative embodiment of the magne
`invention to have a long lifetime, be reliable, and be
`tron module of the present invention using distributed
`applicable to a wide range of plasma processing equip
`cylindrical magnetic array with a combination of ring
`ment con?gurations.
`shaped and cylindrical magnets.
`Still another technical advantage is that the present
`invention has a wide variety of applications. Plasma
`DETAILED DESCRIPTION OF THE
`assisted processes that the present invention can im
`INVENTION
`prove include high-rate reactive-ion etching (RIE) of 25
`The preferred embodiment of the present invention is
`polysilicon, aluminum, oxides, and polyimides; plasma
`best understood by referring to FIGS. 1-15, like numer
`enhanced chemical-vapor deposition (PECVD) of di
`als being used for like and corresponding parts of the
`electrics, aluminum, and other materials; low-tempera
`various drawings.
`ture
`metal-organic
`chemical-vapor
`deposition
`FIG. 1 shows a partially brokenaway diagrammatic
`(MOCVD) of metals including aluminum and copper;
`low-temperature dielectric chemical-vapor deposition
`view of low-thermal-mass multipurpose chuck 20 and
`more particularly illustrates its connections and imple
`for planarized interlevel dielectric formation and low
`mentation within a single-wafer plasma processing sys—
`temperature epitaxial growth of semiconductors. Addi
`tem 10. According to FIG. 1, external magnetron mod
`tional applications include magnetron-plasma process
`ing (e.g., dry development of photoresist layers) and
`ule 12 mounts outside vacuum above stainless steel
`vacuum base plate 16 and main section of the multipur
`cryogenic magnetron plasma processing (for etch and
`deposition processes). Other applications will become
`pose chuck 20. Stainless steel support vacuum base plate
`16 provides vacuum seal for process chamber and en
`apparent as manufacturers use the present invention.
`gages quartz chuck jacket 22. Beginning at the upper
`left portion of FIG. 1 beneath magnetron module 12,
`inert gas (helium or argon) purge line 24 comprises a
`bore 25 through vacuum plate 16. The inert gas purge
`line provides a low gas flow purge between the‘ bottom
`face of the vacuum base plate and the top face of the
`quartz jacket. The small gap between the vacuum base
`plate and the quartz jacket reduces any direct heat
`transfer between the main body of the multipurpose
`chuck and the water-cooled vacuum base plate. The
`main portion of the multipurpose chuck enclosed in the
`quartz jacket can experience temperatures in the desired
`operating range (-l50‘ C. to 750’ C.); however, the
`vacuum base plate maintains a fairly constant tempera
`ture due to water cooling, relative thermal insulation
`from the main chuck, and its larger thermal mass com
`pared to that of the main chuck. Besides the small vac
`uum gap, the quartz jacket provides an additional ther
`mal insulation between the vacuum base plate and the
`main portion of the multipurpose chuck. Due to the
`high reflectivity of the electro-polished stainless steel
`vacuum base plate, the radiative component of heat
`transfer between the main chuck and the vacuum base
`plate is rather small. The gap purge flows radially over
`the quartz jacket and prevents formation of any plasma
`induced deposits in the cylindrical spacing between the
`main chuck and process chamber 14. RF contact 26
`penetrates through vacuum plate 16 via an RF feed
`through and connects to RF plate of multipurpose
`chuck 20. Although shown on the edge, the RF feed
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`The invention, as well as modes of use and further
`advantages, is best understood by reference to the fol
`lowing description of illustrative embodiments when
`read in conjunction with the accompanying drawings.
`FIG. 1 shows a partially broken-away diagrammatic
`view of the plasma processing system and the multipur
`pose chuck integrated with the magnetron plasma mod
`ule that can be used with the present invention;
`FIG. 2 is a cross-sectional view of a preferred em
`bodiment of the multipurpose chuck coolant module;
`FIG. 3 provides a planar view of a preferred embodi
`ment of the groove pattern in the multipurpose chuck
`coolant module;
`FIG. 4 is a cross-sectional view of a preferred em
`bodiment of the multipurpose chuck heating plate;
`FIG. 5 shows a planar view of a preferred embodi
`ment of the multipurpose chuck power heating element;
`_ FIG. 6 shows a planar view of a preferred embodi
`ment of the stainless steel vacuum support plate;
`FIG. 7 is a partially broken-away schematic view of 60
`a single-wafer plasma processing system showing use
`and placement of the magnetron module of the present
`invention (face-down wafer processing);
`FIG. 8 shows a planar view of a preferred embodi
`ment of the hexagonal-array magnetron module of the
`present invention;
`FIG. 9 provides a planar view of a preferred embodi
`ment of the hexagonal-array magnetron module of the
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`55
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`65
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`35
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`45
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`LAM Exh 1003-pg 15
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`10
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`25
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`35
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`5,192,849
`8
`7
`extension component surrounds wafer pins 54 and con
`through may be placed at the center of the vacuum base
`plate. Coolant inlet 28 connects through vacuum plate
`tains quartz or metallic gas shower head 58. Gas shower
`head 58 provides one path for process gas injection.
`16 to the coolant block in the interior of chuck 20.
`Sapphire or quartz tube 60 provides a second gas injec
`Heater wire 30 electrically connects (via an electrical
`tion path for remote microwave (or RF induction)
`feed through) through vacuum plate 16 to chuck 20.
`Spring-loaded thermocouple 32 takes a temperature
`plasma stream 62 to enter process chamber via ground
`electrode 56. Microwave cavity 64 surrounds sapphire
`signal from chuck 20 Heater wire 34 taps from chuck 20
`and exits through vacuum plate 16 (via another electri
`or quartz discharge tube 60 which receives gas from gas
`inlet 66 to generate plasma stream 62. Auxiliary cham
`cal feed-through). From the interior of chuck 20, cool
`ber wall 38 seals to vacuum base plate 16 and surrounds
`ant outlet 36 begins and continues through vacuum
`process chamber wall 40. This arrangement provides an
`plate 16. Auxiliary chamber walls 38 seal to vacuum
`improved vacuum integrity for process chamber due to
`base plate 16 and surround process chamber 14 with a
`the fact that the space between process chamber collar
`vacuum shield. Within auxiliary chamber walls 38,
`40 and auxiliary chamber 38 is pumped down. The
`chuck vacuum base plate 16 seals to process chamber
`vacuum shield between process chamber collar 40 and
`wall 40 at chamber vacuum seal 42. If necessary, all the
`auxiliary chamber 38 is also connected to the load-lock
`chuck feed-throughs (RF, coolant, heater) can be made
`chamber vacuum (not shown).
`at the center with proper thermal and electrical insula
`tions. Only the RF and heater feed-throughs need to be
`FIGS. 2 and 3 more particularly show the construc
`electrically insulated from the vacuum base plate. The
`tion of cooling module 44 within chuck 20. FIG. 2 is a
`cross-sectional schematic view of coolant module 44
`coolant inlet/outlet can make direct physical and elec
`20
`trical contact to the vacuum base plate (system electri
`showing it to comprise a top metal (such as aluminum or
`cal ground). The coolant, heater, thermocouple, inert
`copper or nickel or molybdenum) plate 68 and a bottom
`metal plate 70 made of a similar material as the top
`gas and RF power connections may all run from the
`plate. Bottom metal plate 70 mechanically seals to top
`center of the chuck via the center of the magnetron
`metal plate 68 at welded joint 72 and contains coolant
`module towards the peripheral facilities. Moreover, as
`explained later, the chuck coolant block may employ
`tunnels 46.
`multiple (two) inlets and multiple (two) outlets. The
`FIG. 3 provides a planar view of a suggested groove
`pattern in the bottom plate 70 that demonstrates the
`chuck coolant lines can be connected to grooves made
`metal groove pattern 74 for coolant ?ow through cool
`in the vacuum base plate 16 in order to use the vacuum
`ant tunnels 46. In bottom plate 70 there are two separate
`base plate 16 as a heat exchanger. Both the vacuum base
`plate and the coolant are connected to the system elec
`sets of coolant tunnels 46. One set uses coolant inlet 28
`trical ground and properly insulated from the RF
`and coolant outlet 36 (also shown in FIG. 1), another
`uses coolant inlet 76 and coolant outlet 78 (not shown in
`power connection.
`FIG. 1). The superimposed combination of these two
`Basic elements of multipurpose chuck 20 include
`coolant tunnels is expected to result in uniform transient
`cooling module 44 which incorporates liquid or com
`and steady-state wafer cooling using a gas cooling me
`press gas coolant tunnels 46. Heating element 48 is sepa
`rated from the cooling module 44 by a thin (e.g. 0.060")
`dium such as air or helium or a liquid coolant. Various
`thermally conducting electrically insulating boron ni
`other coolant groove patterns may be used. The coolant
`tride wafer (not shown) and makes electrical contact
`module may be made of anodized aluminum (for a low
`temperature chuck) or nickel-plated copper (for a high
`with heater wires 30 and 34. Heating element 48 is
`placed adjacent to the quartz jacket and is thermally
`temperature chuck). Other choices of coolant module
`insulated from vacuum base plate 16. RF plate 50 inte
`materials include refractory metals such as nickel or
`grally connects to a thermally conducting electrically
`molybdenum. If anodized aluminum is used in the cool
`insulating boron nitride wafer (not shown) at the bot
`ing module 44, the chuck can be used over a tempera
`tom side of cooling module 44 opposite that of heating
`ture range of — 150' C. to +500‘ C. On the other hand,
`nickel, molybdenum, or copper extend the upper tem
`element 48 and connects to RF power contact 26. Semi
`conductor wafer 52 is clamped against the RF plate 50
`perature limit to beyond 750‘ C.
`and quartz wafer holding pins 54 hold wafer 52 in place
`FIGS. 4 and 5 show the construction of heating ele
`inside the plasma processing module. The RF plate 50
`ment 48. FIG. 4 is a cross-sectional view of heating
`element 48 exhibiting top layer 80 of electrical insula
`provides radial and circular grooves on its bottom sur
`tion and passivation through which heater wires 30 and
`face in order to allow flow of a purge gas such as helium
`34 contact resistor line 82. Bottom layer 84 of electrical
`or argon resulting in improved thermal contact between
`insulation integrally joins top layer 80 and heater sub
`wafer and chuck. The inert gas grooves on the bottom
`strate wafer 86. Heater substrate wafer 86 comprises
`face of the RF plate 50 are connected to a center hole
`graphite wafer 88 which SiC-coating 90 surrounds.
`which is used both for a thermocouple and the wafer
`backside purge. The thermocouple junction is electri
`FIG. 5 shows a planar view of top layer 80 and displays
`cally insulated from the RF plate by a small boron ni
`the pattern that thin-?lm power resistor line 82 makes to
`tride pin. The two boron nitride wafers (0.040" to
`form a one-zone power heating resistor 92. Alternative
`patterns may be used for multizone wafer heating.
`0.100" thick) in the multilayer stacked chuck structure
`provide proper electrical insulation between the RF
`Contacts 94 provide electrical connection between
`heater wires 30 and 34 and resistor line 82. Electrical
`plate and the coolant module as well as between the
`contact can be made via spring loading the wire. The
`coolant module and the heater plate. There will be some
`capacitive RF coupling between the RF plate and the
`heater substrate 86 may be also made of boron nitride or
`ground coolant block; however, this e?'ect can be