US20130098068A1

US20130098068A1 - Temperature control device

Info

Publication number: US20130098068A1
Application number: US13/654,695
Authority: US
Inventors: Norio Takahashi; Wataru Kiyosawa
Original assignee: Kelk Ltd
Current assignee: Kelk Ltd
Priority date: 2011-10-19
Filing date: 2012-10-18
Publication date: 2013-04-25
Also published as: JP6017906B2; JP2013102135A

Abstract

A temperature control device includes: a top plate; a heat exchanger plate; a thermoelectric module including a temperature-control-side electrode disposed near the top plate, a heat-exchanger-side electrode disposed near the heat exchanger plate and a thermoelectric element of which one side is connected with the temperature-control-side electrode and the other side is connected with the heat-exchanger-side electrode; and a polyimide film provided on the thermoelectric module near the top plate. The thermoelectric module is spaced apart from and surrounded by a seal wall having a ceramic outer circumference and disposed between the polyimide film and the heat exchanger plate. An adhesion sheet or an adhesive is interposed between the seal wall and the polyimide film.

Description

The entire disclosure of Japanese Patent Applications No. 2011-229879 filed Oct. 19, 2011 and No. 2012-211942 filed Sep. 26, 2012 is expressly incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a temperature control device for controlling a temperature of an object to be temperature-controlled.
2. Description of Related Art
A semiconductor wafer (an object to be temperature-controlled) is placed on a stage plate of a susceptor provided in a vacuum chamber to be subjected to various semiconductor processing such as dry etching with a process gas in a plasma atmosphere. When the various semiconductor processing is performed, a temperature distribution on a surface of the semiconductor wafer has to be controlled as desired.
A typically known temperature control device for performing the control includes a stage plate on which an object to be temperature-controlled is placed, a heat exchanger plate and a thermoelectric module plate held between the stage plate and the heat exchanger plate and provided with a thermoelectric module. The temperature control of the object is effected by supplying electric power to the thermoelectric module (see, for instance, Literature 1: JP-A-10-284761, Literature 2: JP-A-2007-258298).
The thermoelectric module includes a first electrode disposed near the stage plate, a second electrode disposed near the heat exchanger plate, and a P-type thermoelectric element and an N-type thermoelectric element alternately coupled with the first and second electrodes to be electrically connected in series. When an electric current is applied to the P-type and N-type thermoelectric elements to supply power to the thermoelectric module, an endothermic or an exothermic action occurs on the surface of the stage plate in accordance with a current-carrying direction of the electric current. Thus, the semiconductor wafer is cooled by the endothermic action or is heated by the exothermic action via the stage plate.
In such a temperature-control device, the thermoelectric module is sealed in a thermoelectric module plate with a resin seal member as disclosed in Literature 1, or is sealed in a thermoelectric module plate with a metal frame as disclosed in Literature 2.
In the temperature-control device disclosed in Literature 2, a frame-bonding metal plate is interposed between a top plate of the thermoelectric module plate and the metal frame.
However, in a typical temperature-control device, since the seal member is made of resin as disclosed in Literature 1 or is made of metal as disclosed in Literature 2, the strength of the seal member is reduced on account of the heat of the high-temperature process gas or a high corrosivity of the process gas, resulting in a damage on the seal member is damaged. Thus, a highly corrosive process gas enters the thermoelectric module to corrode the thermoelectric module, thereby inhibiting the proper operation of the temperature-control device.
It is possible to increase the thickness of the seal member in order to keep the seal member from being damaged. However, when the thickness of the seal member is increased, since the space occupied by the seal member in the thermoelectric module plate increases, the thermoelectric module cannot be densely arranged, so that the temperature of the object to be temperature-controlled cannot be appropriately controlled.
Further, since a metal plate is interposed between the top plate of the thermoelectric module plate and the seal member of the typical temperature-control device disclosed in Literature 2, a differential in thermal expansion generated due to the heat of the process gas between the top plate of the thermoelectric module plate and the seal member cannot be absorbed, so that the temperature-control device is damaged through the bonding portion between the top plate of the thermoelectric module plate and the seal member and the durability of the temperature-control device is deteriorated.

SUMMARY OF THE INVENTION

An object of the invention is to provide a temperature-control device that is capable of avoiding corrosion of a thermoelectric module caused on account of invasion of highly corrosive gas into the thermoelectric module, capable of densely arranging the thermoelectric modules and capable of improving a durability against the heat of the gas.
A temperature control device according to a first aspect of the invention includes:
a stage plate on which an object of which temperature is to be controlled is placed; a heat exchanger plate; a thermoelectric module comprising a temperature-control-side electrode disposed near the stage plate, a heat-exchanger-side electrode disposed near the heat exchanger plate and a thermoelectric element, the thermoelectric element comprising one side connected with the temperature-control-side electrode and the other side connected with the heat-exchanger-side electrode; and a protection member provided at least on a side of the thermoelectric module near the stage plate, in which the thermoelectric module is spaced apart from and surrounded by a seal wall having a ceramic outer circumference and disposed between the protection member and the heat exchanger plate, and an adhesion sheet or an adhesive is interposed between the seal wall and the protection member.
In a temperature control device according to a second aspect of the invention, the seal wall is made of aluminum oxide, aluminum nitride or alumited aluminum.
In a temperature control device according to a third aspect of the invention, the protection member is a polyimide film.
In a temperature control device according to a fourth aspect of the invention, the protection member is a ceramic plate.
A temperature control device according to a fifth aspect of the invention further includes a thermoelectric module plate provided between the stage plate and the heat exchanger plate, the thermoelectric module plate being provided thereon with the thermoelectric module; and a bush or a boss provided at a position corresponding to a through hole penetrating through the protection member, the bush or the boss being bonded with the protection member.
According to the first aspect of the invention, the thermoelectric module is spaced apart from and surrounded by the seal wall having a ceramic outer circumference and interposed between the protection member and the heat exchanger plate. Thus, the strength of the seal wall can be enhanced, the seal wall is not damaged by the high-temperature corrosive process gas, invasion of the highly corrosive process gas into the thermoelectric module can be prevented and failure of the temperature control device due to corrosion of the thermoelectric module can be avoided. Further, since it is not necessary to increase the thickness of the seal wall, the space required for providing the seal wall can be reduced, so that the thermoelectric module can be more densely provided and the temperature control of the object to be temperature-controlled can be more properly performed. Further, durability of the temperature control device against the heat of the process gas can be improved.
According to the second aspect of the invention, since the seal wall is made of aluminum oxide, aluminum nitride or alumited aluminum, the seal wall exhibits excellent resistance against a highly corrosive process gas.
According to the third and fourth aspects of the invention, since the protection member is made of a polyimide film or ceramic plate, the heat at least from the stage plate can be kept from being transferred to the seal wall. Thus, the seal wall can be thermally isolated from the stage plate and the seal wall can be kept from being heated to a high temperature due to the transferred heat. Further, since the thermoelectric module and the stage plate can be electrically insulated, an appropriate operation of the thermoelectric module can be ensured.
According to the fifth aspect of the invention, since the bush or the boss is provided, the process gas flowing from an outside of the thermoelectric module plate through the through hole can be kept from entering the thermoelectric module through the through hole, so that corrosion of the thermoelectric module can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a temperature control device according to an exemplary embodiment of the invention placed in a vacuum chamber.

FIG. 2 is an exploded perspective view showing the temperature control device.

FIG. 3 is a cross section of the temperature control device.

FIG. 4 is an exploded perspective view showing a part of a thermoelectric module of the temperature control device in an enlarged manner.

FIG. 5 is a cross section taken along A-A′ line in FIG. 4.

FIG. 6 is a cross section showing a first modification of the invention, which specifically is an exploded perspective view showing a part of a thermoelectric module of the temperature control device in an enlarged manner.

FIG. 7 is a cross section taken along B-B′ line in FIG. 6.

FIG. 8 is a cross section showing a second modification of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A temperature control device according to an exemplary embodiment of the invention will be described below with reference to the attached drawings.
As shown in FIG. 1, a semiconductor wafer W (an object to be temperature-controlled) is a disc that is sucked and placed on a top plate 2 by an electrostatic chuck in a vacuum chamber 100 so that various semiconductor processing such as dry etching is performed on the semiconductor wafer with a process gas in a plasma atmosphere. When the semiconductor wafer is subjected to a dry etching, the inside of the vacuum chamber 100 is vacuumized and is kept at a predetermined low pressure. In this state, etching gas is introduced into the vacuum chamber 100. The introduced etching gas is turned into plasma for etching the semiconductor wafer W. When such various semiconductor processing is performed, the temperature of the semiconductor wafer W is controlled at a target temperature by the temperature control device 1 and a temperature distribution on the surface of the semiconductor wafer W is controlled as desired.
As shown in FIG. 2, the temperature control device 1 includes the top plate 2 (stage plate) on which the semiconductor wafer W (see a two-dot chain line in FIG. 2) is placed, a heat equalizer plate 3 provided beneath the top plate 2, a heat exchanger plate 4 provided at the lowermost part of the temperature control device 1 and a thermoelectric module plate 5 held between the heat equalizer plate 3 and the heat exchanger plate 4 and provided thereon with a thermoelectric module 50. The temperature control device 1 supplies electric power to the thermoelectric module 50 to control the temperature of the semiconductor wafer W.
The top plate 2 is a disc member. The semiconductor wafer W is placed on the top plate 2 via helium gas flowing between the top plate 2 and the semiconductor wafer W.
The heat equalizer plate 3 is a disc member that transmits heat from the thermoelectric module 50 to the top plate 2 in a more uniformly distributed manner.
The heat exchanger plate 4 is a thick disc member provided with a spiral channel 41 thereinside as shown in FIG. 3. A temperature-controlling fluid that is controlled at a predetermined temperature flows in through an inlet (not shown), passes through the entire heat exchanger plate 4 via the channel 41 and flows out of an outlet (not shown). According to the above arrangement, as described later, when an endothermic phenomenon occurs at the top plate 2 via the thermoelectric module 50, the heat exchanger plate 4 of which temperature is raised by the endothermic action of the top plate 2 is cooled by the fluid flowing in the channel 41. Further, as shown in FIG. 2, cylindrical bosses 43 (also see FIG. 5) projecting from the heat exchanger plate 4 toward the top plate 2 and the heat equalizer plate 3 are provided on the heat exchanger plate 4 at a position corresponding to each of through holes 42 (described later) of the heat exchanger plate 4.
As shown in FIGS. 3 and 4, the thermoelectric module plate 5 is a disc member on which the thermoelectric module 50 is provided. The thermoelectric module plate 5 includes polyimide films 60A and 60B and a seal wall 70. An inside of the thermoelectric module plate 5 relative to a chain line shown in FIG. 2 serves as the thermoelectric module 50. The thermoelectric module 50 is provided in a circle and is provided with a plurality of temperature-control areas inside the chain line as necessary.
Through holes 21, 31, 42 and 51 are respectively provided on the above-described top plate 2, heat equalizer plate 3, heat exchanger plate 4 and thermoelectric module plate 5.
When the top plate 2, heat equalizer plate 3, heat exchanger plate 4 and thermoelectric module plate 5 are assembled, the through holes 21, 31, 42 and 51 are brought into communication to define a lift pin insertion hole 11 that penetrates all of the top plate 2, heat equalizer plate 3, heat exchanger plate 4 and thermoelectric module plate 5. A lift pin (not shown) for vertically moving the semiconductor wafer W is inserted into the lift pin insertion hole 11 from a lower side (i.e. a lower side in FIG. 2).
As shown in FIGS. 3 and 4, the thermoelectric module 50 includes a plurality of thermoelectric elements. Specifically, the thermoelectric module 50 includes temperature-control- side electrodes 52 and 52′ near the top plate 2 and heat-exchanger- side electrodes 53 and 53′ near the heat exchanger plate 4 (see FIG. 5). Ends of P-type thermoelectric elements 54P and N-type thermoelectric elements 54N near the top plate 2 are connected with the temperature-control- side electrodes 52 and 52′, while ends of the thermoelectric elements 54P and 54N near the heat exchanger plate 4 are connected with the heat-exchanger- side electrodes 53 and 53′. The thermoelectric elements 54P and the thermoelectric elements 54N are alternately arranged and electrically connected in series via the temperature-control- side electrodes 52 and 52′ and the heat-exchanger- side electrodes 53 and 53′ to provide the thermoelectric module 50.
Incidentally, though the temperature-control-side electrodes 52 and the heat-exchanger-side electrodes 53 have a rectangular profile in plan view as shown in FIG. 4, the temperature-control-side electrodes 52 and the heat-exchanger-side electrode 53 may have different profiles in plan view (e.g. cocoon shape) as long as the temperature-control-side electrodes 52 and the heat-exchanger-side electrodes 53 are evenly arranged to avoid locally uneven temperature control.
When electric power is supplied to the thermoelectric module 50 by applying an electric current to the thermoelectric elements 54P and 54N via a power line (not shown) penetrating through the heat exchanger plate 4 from the lower side of the heat exchanger plate 4, a charge transfer occurs between the temperature-control- side electrodes 52 and 52′ and the heat-exchanger- side electrodes 53 and 53′ to cause heat (energy) transfer since the charge carries heat. Thus, an endothermic phenomenon occurs at the temperature-control- side electrodes 52 and 52′ and an exothermic phenomenon occurs at the heat-exchanger- side electrodes 53 and 53′ to release heat. Thus, the semiconductor wafer W is cooled by the endothermic phenomenon at the temperature-control- side electrodes 52 and 52′ via the top plate 2. On the other hand, when electric current is applied in reverse direction, heat is released at the temperature-control- side electrodes 52 and 52′ by an exothermic phenomenon. Thus, the semiconductor wafer W is heated by the exothermic phenomenon at the temperature-control- side electrodes 52 and 52′ via the top plate 2. In other words, an endothermic or exothermic action occurs at the top plate 2 at portions corresponding to the temperature-control- side electrodes 52 and 52′ in accordance with current-applying direction.
Further, an upper side (a side near the top plate 2) of the temperature-control- side electrodes 52 and 52′ is covered with the polyimide film 60A (protection member). The heat equalizer plate 3 is provided on an upper side of the polyimide film 60A. A lower side of the heat-exchanger- side electrodes 53 and 53′ is covered with the polyimide film 60B (protection member). The heat exchanger plate 4 is provided on a lower side of the polyimide film 60B. Though the thickness of the polyimide films 60A and 60B is not limitative, the polyimide films 60A and 60B are approximately 25 μm thick in this exemplary embodiment.
The thermoelectric module 50 is spaced apart from and surrounded by a ring-shaped seal wall 70 held between the polyimide films 60A and 60B.
The seal wall 70 is made of a ceramic of aluminum oxide, aluminum nitride or alumited aluminum. Specifically, the outer circumference of the seal wall 70 is made of a ceramic. As shown in FIG. 3, the seal wall 70 has a thickness H1 smaller than a thickness H0 (a distance between an upper end surface of the temperature-control-side electrode 52 and a lower end surface of the heat-exchanger-side electrode 53) of the thermoelectric module 50. The seal wall 70 is bonded to the polyimide films 60A and 60B via a polyimide, silicone or epoxy adhesion sheet or adhesive 80.
The seal wall 70 is spaced apart from an outer circumference of the thermoelectric module 50 at an interval t0. The interval t0 is equal to or larger than an interval t1 between adjacent ones of the temperature-control-side electrodes 52 and an interval t2 between adjacent ones of the heat-exchanger-side electrodes 53.
The seal wall 70 has a greater strength than that of a typical resin seal. Thus, with the same thickness as the typical resin seal, the seal wall 70 can sufficiently resist the heat of the high-temperature process gas or a highly corrosive process gas. Further, since the seal wall 70 and the polyimide films 60A and 60B are bonded via the polyimide, silicone or epoxy adhesion sheet or adhesive 80, a differential thermal expansion caused between the seal wall 70 and the polyimide films 60A and 60B can be absorbed by the adhesion sheet or adhesive 80, thus enhancing durability.
FIG. 5 shows a cross section of the thermoelectric module 50 of the temperature control device 1 taken along A-A′ line in FIG. 4.
As show in FIG. 5, the through hole 51 penetrates the polyimide films 60A and 60B at a position not interfering with the temperature-control- side electrodes 52 and 52′, the heat-exchanger- side electrodes 53 and 53′ and the thermoelectric elements 54P and 54N.
The diameter of the through hole 51 near the polyimide film 60A is the same as an inner diameter of the boss 43. The diameter of the through hole 51 near the polyimide film 60B is greater than an outer diameter of the boss 43.
When the heat exchanger plate 4 and the thermoelectric module plate 5 are assembled, each of the bosses 43 enters the through hole 51 from the side of the polyimide film 60B to be located at a position corresponding to the through hole 51 and adjacent to the temperature-control-side electrode 52′ and the heat-exchanger-side electrode 53′. Thus, a part of the through hole 51 penetrates the top and bottom sides of the thermoelectric module plate 5 through an inner space of the boss 43 to be in communication with the through hole 42.
A projection length H2 of the boss 43 is smaller than the thickness HO of the thermoelectric module 50. Upper ends of the bosses 43 are bonded to the polyimide films 60A via the adhesion sheet or adhesive 80. A side of a part of the temperature-control-side electrodes 52′ and the heat-exchanger-side electrodes 53′ facing the boss 43 extends toward the boss 43 to form a curved portion while keeping an interval t3 with the boss 43. A circular clearance S is formed between the boss 43 and the surrounding temperature-control-side electrodes ST. The interval t3 of the clearance S is equal to or larger than the interval t1 between adjacent ones of the temperature-control-side electrodes 52′ and the interval t2 between adjacent ones of the heat-exchanger-side electrodes 53 (see FIG. 3).
The bosses 43 thus arranged keep the process gas flowing through the through hole 51 from flowing into the thermoelectric module 50 through the through hole 51.
A first modification of the invention will be described below. It should be noted that the same components as those of the above exemplary embodiment will be denoted by the same reference numeral to omit the description thereof.
FIG. 6 is a cross section showing a first modification of the invention, which specifically is an exploded perspective view showing a part of a thermoelectric module 50 of the temperature control device 1 in an enlarged manner. FIG. 7 is a cross section taken along B-B′ line in FIG. 6.
As shown in FIGS. 6 and 7, unlike the exemplary embodiment shown in FIGS. 4 and 5, the thermoelectric module plate 5 according to the first modification includes polyimide films 60A and 60B, a seal wall 70 and a bush 90.
As shown in FIG. 7, the diameter of the through hole 51 near the polyimide film 60A and the diameter of the through hole 51 near the polyimide film 60B are the same as an inner diameter of the bush 90.
The bush 90 having a cylindrical shape is provided between the polyimide films 60A and 60B at a position corresponding to the through hole 51 and adjacent to the temperature-control-side electrodes 52′ and the heat-exchanger-side electrodes 53′. The through hole 51 penetrates the top and bottom sides of the thermoelectric module plate 5 via the inner space of the bush 90.
A thickness 113 of the bush 90 is smaller than the thickness H0 of the thermoelectric module 50. Upper and lower ends of the bush 90 are bonded to the polyimide films 60A and 60B via the adhesion sheet or adhesive 80.
The bush 90 thus arranged keeps the process gas flowing through the through hole 51 from flowing into the thermoelectric module 50 through the through hole 51.
Next, a second modification of the invention will be described below. It should be noted that the same components as those of the above exemplary embodiment will be denoted by the same reference numeral to omit the description thereof.
As shown in FIG. 8, unlike the exemplary embodiment shown in FIG. 3, an upper side of the temperature-control- side electrodes 52 and 52′ is covered with a ceramic plate 61A (protection member). The heat equalizer plate 3 is provided on an upper side of the ceramic plate 61A. A lower side of the heat-exchanger- side electrodes 53 and 53′ is also covered with a ceramic plate 61B (protection member). The heat exchanger plate 4 is provided on a lower side of the ceramic plate 61B. Though not limitative, the thickness of the ceramic plates 61A and 61B is approximately 1 mm in this modification, which is thicker than the thickness of the polyimide films 60A and 60B of the exemplary embodiment shown in FIG. 3 for the purpose of production convenience.
It should be understood that the scope of the present invention is not limited to the above-described exemplary embodiment(s) but includes modifications and improvements as long as the modifications and improvements are compatible with the invention.
For instance, though the heat equalizer plate 3 is provided between the top plate 2 and the thermoelectric module plate 5, the heat equalizer plate 3 may be provided as necessary and is not requisite for the invention.
Though the upper side of the temperature-control- side electrodes 52 and 52′ and the lower side of the heat-exchanger- side electrodes 53 and 53′ are covered with the polyimide films 60A and 60B or the ceramic plates 61A and 61B in the above exemplary embodiment, it is only required for the upper side of the temperature-control- side electrodes 52 and 52′ to be covered with the polyimide film 60A or the ceramic plate 61A and the lower side of the heat-exchanger- side electrodes 53 and 53′ may not be covered.

Claims

What is claimed is:

1. A temperature control device, comprising:

a stage plate on which an object of which temperature is to be controlled is placed;

a heat exchanger plate;

a thermoelectric module comprising a temperature-control-side electrode disposed near the stage plate, a heat-exchanger-side electrode disposed near the heat exchanger plate and a thermoelectric element, the thermoelectric element comprising one side connected with the temperature-control-side electrode and the other side connected with the heat-exchanger-side electrode; and

a protection member provided at least on a side of the thermoelectric module near the stage plate, wherein

the thermoelectric module is spaced apart from and surrounded by a seal wall having a ceramic outer circumference and disposed between the protection member and the heat exchanger plate, and

an adhesion sheet or an adhesive is interposed between the seal wall and the protection member.

2. The temperature control device according to claim 1, wherein

the seal wall is made of a ceramic of aluminum oxide, aluminum nitride or alumited aluminum.

3. The temperature control device according to claim 1, wherein

the protection member is a polyimide

4. The temperature control device according to claim 1, wherein

the protection member is a ceramic plate.

5. The temperature control device according to claim 1, further comprising:

a thermoelectric module plate provided between the stage plate and the heat exchanger plate, the thermoelectric module plate being provided thereon with the thermoelectric module; and

a bush or a boss provided at a position corresponding to a through hole penetrating through the protection member, the bush or the boss being bonded with the protection member.