Ulllted States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,892,207
`
`Kawamura et al.
`
`[45] Date of Patent:
`
`Apr. 6, 1999
`
`US005892207A
`
`[54] HEATING AND COOLING APPARATUS FOR
`REACTION CHAMBER
`
`[75]
`
`Inventors: Hideki Kawamura, Hyogo-ken;
`Hirochika Yamamoto, Ibaragi-ken;
`Yukinobu Nishikawa, Tokyo, all of
`Japan
`
`[73] Assignee: Teisan Kabushiki Kaisha, Tokyo,
`Japan
`
`[21] Appl. No.: 758,246
`
`[22]
`
`Filed:
`
`Nov. 27, 1996
`
`[30]
`
`Foreign Application Priority Data
`
`Dec. 1, 1995
`
`[JP]
`
`Japan .................................. .. 7—335657
`
`Int. Cl.5 ................................................... .. B23K 10/00
`[51]
`[52] U.S. Cl.
`............. .. 219/492; 219/121.43; 219/121.49;
`118/724; 204/298.09
`[58] Field of Search .......................... .. 219/121.4, 121.43,
`219/121.52, 121.44, 121.49, 492, 497, 148/723 R,
`724, 725, 204/298.09, 308, 298.31; 156/646.1,
`345
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,646,243
`3,744,935
`4,726,195
`4,971,653
`5,376,213
`5,414,244
`
`2/1972 Graneau et al.
`........................ .. 174/15
`
`7/1973 Magni
`............ ..
`417/366
`
`. . . . . . .. 62/62
`2/1988 Klee . . . . . . . . . . . . .
`......................... .. 156/626
`11/1990 Powell et al.
`12/1994 Ueda et al.
`....................... .. 118/723 E
`5/1995 Imahashi
`............................... .. 219/497
`
`5,584,971
`5,589,041
`5,591,269
`
`12/1996 Komino ........................... .. 204/192.13
`
`12/1996 Lantsman
`204/192.33
`...................... .. 118/723 R
`1/1997 Arami et al.
`
`FOREIGN PATENT DOCUMENTS
`
`0436070A1
`1515303
`60—245778
`1004739
`
`European Pat. Off.
`10/1991
`4/1969 Germany .
`5/1985
`Japan .
`9/1965 United Kingdom .
`
`.
`
`Primary Examiner—Mark H. Paschall
`Attorney, Agent, or Firm—Burns, Doane, Swecker &
`Mathis, L.L.P.
`
`[57]
`
`ABSTRACT
`
`The present invention relates to a temperature regulation
`apparatus capable of easily regulating the temperature of a
`support for a substance to be treated, such as a semicon-
`ductor Wafer.
`
`The temperature regulation apparatus includes a liquid nitro-
`gen supply device for supplying liquid nitrogen into a
`temperature regulation space provided in the inside of a
`support so as to effect flashing of the liquid nitrogen. A
`heating device for heating the support and temperature
`sensors for detecting the temperature of the support are also
`provided. A temperature setting device sets the temperature
`of the support at a desired temperature and a controller
`controls the liquid nitrogen supply device and the heating
`device based on a temperature detected by the temperature
`sensors, so that the support reaches and is maintained at the
`set temperature.
`
`17 Claims, 1 Drawing Sheet
`
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`U.S. Patent
`
`Apr. 6, 1999
`
`5,892,207
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`5,892,207
`
`1
`HEATING AND COOLING APPARATUS FOR
`REACTION CHAMBER
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`
`invention relates to a treatment unit, for
`The present
`example, an etching unit, spattering unit or CVD unit, and
`more particularly to a temperature control apparatus for
`controlling the temperature of a support for a substance to be
`treated, such as a semiconductor wafer.
`2. Brief Description of the Related Art
`In the treatment of semiconductor wafers, temperature
`plays an important role as a conditional factor for treating
`semiconductor wafers. For instance, in the case of a reactive
`ion etching (RIE) treatment,
`it has been known that the
`anisotropy of etching is improved if a semiconductor wafer
`is cooled down to —100° C. or less. In a conventional RIE
`
`unit, there has therefore been previously developed a means
`of introducing a liquefied gas, such as liquid nitrogen, to a
`liquid reservoir in a support for a semiconductor wafer, i.e.,
`a susceptor assembly,
`to cool down the semiconductor
`wafer. See, for example, Japanese Patent Application Laid-
`open (KOKAI) No. 216,076/1994.
`The prior art treatment units, however, perform only a
`single temperature treatment in each unit. Temperature con-
`trol
`in prior art
`treatment units therefore has not been
`performed with large variations in the treatment tempera-
`ture. The prior art treatment units thus have taken long
`periods of time to continuously carry out different kinds of
`heat treatments in one treatment unit.
`
`It is therefore an object of the present invention to provide
`a treatment unit which overcomes the deficiencies in the
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`25
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`prior art by providing a treatment unit which is capable of
`quickly controlling the temperature of the treatment unit
`over
`
`35
`
`SUMMARY OF THE INVENTION
`
`In accordance with the foregoing objectives, the present
`invention provides a treatment unit
`for semi-conductor
`wafers including a support
`to support
`the wafer and a
`temperature controller to control
`the temperature of the
`wafer during a treatment process carried out in the unit. The
`temperature controller comprises a cooling substance supply
`device for supplying a cooling substance into a temperature
`controlled space provided inside of the support, the cooling
`substance supply device flashing the cooling substance
`inside the space. A heating device is also provided which
`heats the support. The device also includes at least one
`temperature sensor for measuring the temperature of the
`support and a temperature setting device for setting the
`temperature of the support at a desired temperature. A
`controller controls at least one of the cooling substance
`supply device and the heating device based on the tempera-
`ture measured by the at least one temperature sensor and
`obtains the desired temperature of the support by selectively
`supplying the cooling substance to the support when its
`temperature is higher than the desired temperature and
`heating the support when its temperature is lower than the
`desired temperature.
`According to another embodiment of the invention, a
`treatment unit for a substance comprises a housing, a support
`including a substance supporting surface,
`the support
`located within the housing for supporting a substance on the
`substance supporting surface, means for cooling the support
`in heat transfer communication with the support, and means
`for heating the support in heat transfer communication with
`said support.
`
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`2
`According to yet another embodiment of the invention, a
`method for controlling the temperature of a substance in a
`treatment chamber during a treatment process comprises the
`steps of sensing the temperature of a support, the substance
`being in heat transfer communication with said support,
`cooling the support if the temperature is above a desired
`temperature, and heating the support if the temperature is
`below the desired temperature.
`
`BRIEF DESCRIPTION OF THE DRAWING
`
`The invention will be described in greater detail with
`reference to the accompanying drawing, wherein FIG. 1 is a
`schematic view of a treatment unit according to one embodi-
`ment of the invention.
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`FIG. 1 is a schematic drawing illustrating a RIE unit
`according to one embodiment of the present invention. RIE
`unit 10 includes a treatment chamber 12,
`the interior of
`which is in fluid connection with a vacuum system (not
`shown). In treatment chamber 12, a susceptor assembly or
`support 16 is provided for supporting a semiconductor wafer
`14 mounted on the support. Susceptor assembly 16 is
`connected to a high frequency power source 20 through a
`matching device 18 and functions as a cathode. Above
`susceptor assembly 16, an electrode 22 is arranged at a
`predetermined distance from assembly 16. Electrode 22 is
`grounded so as to function as an anode. Electrode 22 is made
`as a hollow structure, including an inner space 24 commu-
`nicating with a reactive gas supply source (not shown) by
`way of a pipe 26. A reactive gas supplied from the reactive
`gas supply source to inner space 24 of electrode 22 is
`introduced into treatment chamber 12 through a number of
`small holes 28 formed on the bottom surface of the elec-
`trode.
`When the inside of treatment chamber 12 is reduced in
`
`pressure to, for example, 10‘2 Torr (1.33><103 KPa) or less,
`a reactive gas is introduced into the treatment chamber. The
`reactive gas may be, but is not limited to, CF4. A high
`frequency voltage is applied between electrode 22 and
`susceptor assembly 16, igniting the reactive gas to its plasma
`state and producing activated species such as ions and
`radicals. Since susceptor assembly 16 is given a negative
`voltage, the activated species such as the produced ions are
`forced in a direction toward susceptor assembly 16 and to
`etch semiconductor wafer 14 on the susceptor assembly.
`A temperature control apparatus 30 according to the
`present invention includes a cooling substance, e.g., liquid
`nitrogen, supply device 34 for supplying liquid nitrogen into
`a temperature control space 32 formed in susceptor assem-
`bly 16. Liquid nitrogen supply device 34 in the embodiment
`illustrated in the drawing preferably includes a gas-liquid
`separator 36, into which liquid nitrogen is introduced, dis-
`posed outside of treatment chamber 12, and a flash disc 38
`disposed in temperature control space 32. Gas-liquid sepa-
`rator 36 and flash disc 38 are connected with each other by
`a vacuum-j acketed pipe 40 so that nitrogen in the gasliquid
`separator is sent to the flash disc in liquid phase only, thereby
`maintaining a very low temperature. Flash disc 38 has a
`number of liquid injection holes (not shown) formed on its
`top surface, as seen in FIG. 1, where the liquid nitrogen sent
`to the flash disc is caused to flash upwards from the liquid
`injection holes.
`Vacuum-j acketed pipe 40 includes an electromagnetic
`valve 42. Electromagnetic valve 42 is preferably controlled
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`5,892,207
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`3
`by control signals from a controller 44. Controller 44 may
`be, but is not limited to, a microcomputer.
`Temperature control apparatus 30 also includes a high
`temperature nitrogen gas supply device 46 for supplying
`high temperature nitrogen gas into temperature control space
`32 of susceptor assembly 16. High temperature nitrogen gas
`supply device 46 includes a nitrogen gas tank 48 preferably
`disposed outside of treatment chamber 12 into which nitro-
`gen gas is introduced. A heating device 50, such as an
`electric heater, is disposed inside nitrogen gas tank 48 in
`order to heat nitrogen gas introduced therein to a high
`temperature. High temperature nitrogen gas supply device
`46 includes a nitrogen gas release disc 52 disposed in
`temperature control space 32. Nitrogen gas release disc 52
`and nitrogen gas tank 48 are connected with each other by
`an insulated pipe 54. Insulated pipe 54 preferably includes
`a solenoid valve 56. Solenoid valve 56 is also controlled by
`controller 44.
`
`Temperature sensors 58, 60 are provided for sensing the
`temperature of susceptor assembly 16 and are connected to
`controller 44. In the illustrated embodiment, temperature
`sensors 58, 60 are disposed at two places, i.e., in the vicinity
`of a wafer-supporting face 62 of susceptor assembly 16 and
`in the vicinity of temperature control space 32. Controller 44
`calculates the temperature of wafer-supporting face 62 based
`on at least the temperature signals from temperature sensors
`58, 60. Controller 44 includes an input device 64 connected
`thereto for setting a desired treatment temperature. Input
`device 64 may be, but is not limited to, a keyboard.
`A treatment
`temperature control method will now be
`described with reference to FIG. 1. In this method, treatment
`temperature refers to a temperature of wafer supporting face
`62 of susceptor assembly 16.
`When it is desired that the treatment temperature be a
`particular temperature, e.g., —100° C., in order to enhance
`the anisotropy of etching, a set treatment temperature of
`—100° C. is input from input device 64. After the desired
`temperature has been set, controller 44 calculates the tem-
`perature of wafer-supporting face 62 of the susceptor assem-
`bly 16 based at least upon signals from temperature sensors
`58, 60. If the temperature of wafer-supporting face 62 is
`calculated to be over the set temperature (e.g., —100° C.), a
`solenoid valve control signal will be produced to open
`solenoid valve 42 and to leave solenoid valve 56 closed.
`
`When solenoid valve 42 has been opened, liquid nitrogen is
`transferred from gas-liquid separator 36 to flash disc 38
`through vacuum-jacketed pipe 40 and blown onto the top
`surface of temperature control space 32 by using the pres-
`sure of the nitrogen gas in gas-liquid separator 36 as a
`driving source. Since very low temperature liquid nitrogen
`is directly blown onto susceptor assembly 16, susceptor
`assembly 16 is rapidly cooled down and the semiconductor
`wafer 14 supported thereon is also cooled down. When the
`temperature of wafer-supporting face 62 has reached the set
`temperature as determined by controller 44, controller 44
`recognizes, from signals of temperature sensors 58, 60, that
`the set temperature has been reached, and controls solenoid
`valve 42 so that the flow of liquid nitrogen to flash disc 38
`is stopped or significantly decreased.
`in treatment
`An etching treatment
`is then carried out
`chamber 12, as described above. Turning on high frequency
`power source 20, semiconductor wafer 14 is heated by
`electric discharge, and hence it is necessary for controller 44
`to control solenoid valve 42 to send liquid nitrogen to
`temperature control space 32 to cool susceptor assembly 16.
`Liquid nitrogen introduced to temperature control space 32
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`is evaporated at the same time as it is caused to flow from
`flash disc 38, from which it
`is quickly released to the
`atmosphere by way of a pipe 66.
`When it is desired to raise the treatment temperature, a
`desired temperature is input from input device 64 into
`controller 44. After the treatment temperature has been set,
`controller 44 closes solenoid valve 42 and opens solenoid
`valve 56. High temperature nitrogen gas is introduced from
`nitrogen gas tank 48 into temperature control space 32
`through insulated pipe 54 and nitrogen gas release disc 52.
`As a result, the temperature of susceptor assembly 16, and
`of semiconductor wafer 14 supported thereon, rises. Because
`the liquid nitrogen previously introduced in temperature
`control space 32 has been discharged by way of pipe 66, the
`temperature of susceptor assembly 16 rises rapidly. If the
`temperature of wafer-supporting face 62 of the susceptor
`assembly 16 has reached the set temperature, e.g., 20° C., a
`control signal will be produced from controller 44 so as to
`close solenoid valve 46. Etching is then performed in
`treatment chamber 16. Semiconductor wafer 14 is heated as
`
`described above and the temperature of the wafer-supporting
`face 62 potentially then exceeds the set temperature, e.g.,
`20° C. If the temperature of wafer-supporting face 62
`exceeds the set temperature, controller 44 controls solenoid
`valve 42 so that liquid nitrogen is introduced into tempera-
`ture control space 32 to keep the treatment temperature
`constant.
`
`Although an illustrative embodiment of the present inven-
`tion has been described, the present invention is not limited
`thereto, and variations may be devised without departing
`from the spirit of the invention. For example, high tempera-
`ture nitrogen gas supply device 46 is used as a heating
`device for heating the susceptor assembly 16. Alternatively,
`an electric heater, e.g., a heating resistor (not shown), may
`be embedded in susceptor assembly 16 in place of high
`temperature nitrogen gas supply device 46. Controller 44
`then controls the amount of electricity to be fed to this
`electric heater.
`
`is of an
`Although the aforementioned embodiment
`example where the present invention is applied to a RIE unit,
`a temperature control apparatus according to the present
`invention also can be applied to other treatment units, for
`example, a pressure-reduced CVD unit, a spattering unit, or
`other types of etching units.
`According to the present invention, wafer-supporting face
`62 and support 16 can be cooled down to a desired tem-
`perature within a short period of time because liquid nitro-
`gen is used as a cooling substance. The discharge of liquid
`nitrogen from support 16 can be carried out within a short
`period of time and the switching operation from the cooling
`mode to the heating mode can be rapidly carried out because
`the liquid nitrogen introduced to support 16 is flash evapo-
`rated. Furthermore, the heating of support 16 also can be
`performed within a short period of time because there is no
`liquid nitrogen within temperature control space 32 at the
`time heating is desired.
`A temperature control apparatus according to the present
`invention controls temperature over a large temperature
`range and within a short period of time. When it is desired
`to perform successive treatments at different temperatures,
`the overall
`treatment duration can be greatly reduced,
`whereby the treating capacity and productivity of a treat-
`ment unit according to the present
`invention are vastly
`improved. Since different kinds of such treatments have
`been performed in the prior art devices by using a plurality
`of treatment units, a treatment unit according to the present
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`5,892,207
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`5
`invention decreases the number of such treatment units
`
`which are required to perform multiple treatments.
`While the invention has been described in detail with
`
`it will be
`thereof,
`reference to a preferred embodiment
`apparent to one of ordinary skill in the art that various
`changes can be made, and equivalents employed, without
`depicting from the spirit and scope of the invention.
`What is claimed is:
`
`1. A treatment unit for semi-conductor wafers including a
`support to support said wafer and a temperature controller to
`control the temperature of said wafer during a treatment
`process carried out in said unit, wherein said temperature
`controller comprises:
`a cooling substance supply device having a reservoir
`positioned outside said support for supplying a cooling
`substance into a temperature controlled space provided
`inside of said support, said cooling substance supply
`device further comprising means for flashing said cool-
`ing substance in said temperature controlled space, said
`means for flashing including a flash disk in fluid
`communication with said reservoir;
`a heating device for heating said support;
`at least one temperature sensor for measuring the tem-
`perature of said support;
`a temperature setting device for setting the temperature of
`said support at a desired temperature;
`a controller for controlling at least one of said cooling
`substance supply device and said heating device based
`on the temperature measured by said at
`least one
`temperature sensor for obtaining said desired tempera-
`ture of said support by selectively supplying said
`cooling substance to said support when its temperature
`is higher than said desired temperature and heating said
`support when its temperature is lower than said desired
`temperature;
`wherein when said cooling substance supply device sup-
`plies said cooling substance from said reservoir to said
`means for flashing, said cooling substance exits said
`cooling substance supply device at said flash disk to
`primarily vaporize said cooling substance in said tem-
`perature controlled space to minimize accumulation of
`a liquid phase of said cooling substance in said tem-
`perature controlled space.
`2. A treatment unit according to claim 1, wherein said
`heating device comprises a high temperature nitrogen gas
`supply device for supplying high temperature nitrogen gas to
`said support.
`3. A treatment unit according to claim 1, wherein said
`heating device comprises an electric heater provided in said
`support.
`4. A treatment unit for a substance comprising:
`a housing;
`a support including a substance supporting surface and a
`temperature control space therein, said support located
`within said housing for supporting a substance on said
`substance supporting surface;
`means for cooling said support in heat transfer commu-
`nication with said support, said cooling means com-
`prising a source of a fluid cooling substance positioned
`outside of said support, a cooling device including a
`flash disk, and a cooling substance flow path connected
`between said cooling substance source and said cooling
`device, said flash disk located within said temperature
`control space and including a hole for allowing said
`fluid cooling substance to exit said flash disk into said
`
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`temperature control space, to primarily vaporize said
`fluid cooling substance to cool said support to minimize
`accumulation of a liquid phase of said cooling sub-
`stance in said temperature control space; and
`means for heating said support in heat transfer commu-
`nication with said support.
`5. A treatment unit for a substance according to claim 4,
`further comprising means for introducing a reactive gas into
`said housing, and means for igniting said reactive gas within
`said housing to form a plasma.
`6. A treatment unit for a substance according to claim 4,
`further comprising a first temperature sensor to sense the
`temperature of said substance supporting surface and to
`generate a first temperature signal.
`7. A treatment unit for a substance according to claim 6,
`further comprising a second temperature sensor to sense a
`temperature adjacent one of said cooling means and said
`heating means and to generate a second temperature signal.
`8. A treatment unit for a substance according to claim 6,
`further comprising a controller in communication with said
`cooling means and said heating means to control said
`cooling means and said heating means to modify the tem-
`perature of said support.
`9. A treatment unit for a substance according to claim 8,
`wherein said controller includes an input device for input-
`ting a desired temperature, said controller controlling said
`cooling means and said heating means to modify the tem-
`perature of said support to be substantially said desired
`temperature.
`10. A treatment unit for a substance according to claim 4,
`wherein said heating means comprises a source for a heating
`substance, a heating device in heat transfer communication
`with said support to allow said heating substance to heat said
`support, and a heating substance flow path connected
`between said heating substance source and said heating
`device.
`
`11. Atreatment unit for a substance according to claim 10,
`wherein said heating device includes a release disk, said
`support further comprising a temperature control space
`therein, said release disk located within said temperature
`control space and including a hole for allowing said heating
`substance to exit said release disk into said temperature
`control space to heat said support.
`12. A treatment unit for a substance according to claim 4,
`wherein said heating means comprises an electric heater in
`heat transfer communication with said support.
`13. A treatment unit for a substance according to claim 4,
`wherein said support further comprises a temperature con-
`trol space and a vent for said temperature control space, said
`cooling means comprises means for delivering a super-
`cooled gas to said temperature control space, said heating
`means comprising means selected from the group consisting
`of means for delivering a heated gas to said temperature
`control space and an electric heater in heat transfer com-
`munication with said support.
`14. A method for controlling the temperature of a sub-
`stance in a treatment chamber during a treatment process,
`comprising the steps of:
`sensing the temperature of a support, said substance being
`in heat transfer communication with said support;
`cooling said support with a cooling substance delivered
`from a reservoir outside said support to a temperature
`control space in said support if said temperature is
`above a desired temperature by flashing said liquid
`cooling substance adjacent said support to primarily
`vaporize and minimize accumulation of said liquid
`cooling substance in said temperature controlled space;
`and
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`5,892,207
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`7
`heating said support if said temperature is below said
`desired temperature.
`15. A method for controlling the temperature of a sub-
`stance treatment chamber during a treatment process accord-
`ing to claim 14, wherein said step of heating said support
`comprises selectively exposing said support to a gas which
`heats said support.
`16. A method for controlling the temperature of a sub-
`stance in a treatment chamber during a treatment process
`
`8
`according to claim 14, wherein said step of heating said
`support comprises heating said support with an electric
`heater.
`
`17. A method for controlling the temperature of a sub-
`stance in a treatment chamber during a treatment process
`according to claim 14, further comprising treating said
`substance in said treatment chamber while substantially
`simultaneously cooling said support.
`*
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