JP2013175289A - Vacuum environment adaptive plate heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent impurity particles of fine powder etc., produced through thermal expansion and thermal contraction of a member constituting a heating element from being diffused out from a plate heater.SOLUTION: There is provided a plate heater 1 constituted by housing a heating element 4 in a back plate 2, and screwing and fixing peripheral edges of the back plate 2 and a face plate 3 while an upper surface of the heating element and an upper surface of the back plate 2 are in contact with a reverse surface of the face plate 3, the plate heater being characterized in that an outside air passage coming into contact with the heating element 4 is formed at an interval with at least one of the back plate 2 and the face plate 3, and a metal filter blocking impurities of fine particles and a heat-resistant seal securing airtightness between the peripheral edge of the heating element and both the plates 2, 3 are provided to the outside air passage on sides close to outside air.

Description

  The present invention relates to a plate heater used in a vacuum environment such as a decompression tank, a vacuum tank, etc., and from the plate heater itself when drying various objects to be dried such as a semiconductor wafer, a glass substrate for a liquid crystal display, and an optical disk substrate Impurities such as fine powder particles and fine powder particles generated from mica plates and adhesives are covered by the organic matter components generated, friction between the heating element and the plate due to thermal expansion and contraction due to thermal contraction, etc. The present invention relates to a vacuum environment-compatible plate heater that does not adhere to dry matter.

  Conventionally, a mica heater has been used as a plate heater. This mica heater is arranged and fixed so that a heating element made of stainless steel foil is sandwiched between upper and lower rectangular mica plates. Other plate heaters include cast aluminum heaters, embedded aluminum heaters, and aluminum plate heaters. The cast aluminum heater is a heater in which a sheathed heater is cast in aluminum. The embedded aluminum heater is a heater in which a groove is formed in an aluminum plate and the sheathed heater is fixed with heat transfer cement to fill a gap. The aluminum plate heater is a heater in which holes are drilled in the aluminum plate and a cartridge heater is inserted. As the material of the plate, stainless steel, aluminum or the like is used. The present invention is an invention for a vacuum environment-compatible plate heater in which generation of impurities such as fine dust in a combination of a heating element and a plate does not adhere to an object to be dried.

  As a conventional plate heater, a metal foil heater is insulated via polyimide or polybenzimidazole between a heating plate made of a metal plate and a metal pressing plate, and the insulation is on the side in contact with the metal foil heater. A polyimide or polybenzimidazole film is formed by applying or vapor-depositing polyimide or polybenzimidazole on the heating plate and metal pressing plate, and the polyimide or polybenzimidazole film is formed on the metal. The heating plate and the pressing plate are sandwiched from both sides of the plate heater so as to be in contact with the foil heater, and are screwed together to be an integrated heating body (Claim 4 of Patent Document 1).

As another conventional example, the thermal plate has a plurality of through holes penetrating in the vertical direction, and a substrate support pin is inserted in each through hole so as to be moved up and down. Each substrate support pin is erected on a support member that is interlocked and connected to an air cylinder and can be raised and lowered, and these substrate support pins are raised and lowered in synchronization. By raising each substrate support pin, the substrate is transferred to and from a substrate transfer device (not shown) above the heat plate, and by lowering each substrate support pin, the substrate is placed on the upper surface of the heat plate. It is described that it can be supported (paragraph 0016 of Patent Document 2).
JP 2003-217800 A JP 2000-164601 A

  In Patent Document 1, a screw hole formed inside the heating plate, a hole penetrating the mica winding heater, a hole penetrating the insulating plate, and a hole penetrating the pressing plate are integrally fixed with screws. As a result of this structure, fine powdery impurities due to thermal expansion and contraction through the gaps between the holes and screws, impurities such as fine particles generated from materials such as mica, etc. are generated, and the substrate that is to be dried The impurities adhere to the surface of the metal and contribute to the deterioration of the product yield.

  Further, in the cited document 2, since the substrate support pin is inserted in each of the plurality of through holes penetrating in the vertical direction of the heat plate so as to be moved up and down, the heat expansion and contraction of a heating element such as a mica heater Impurity particles such as fine particles that are generated adhere to the substrate or the like during drying, resulting in inconveniences such as a product with a low yield.

  The present invention has been made to solve the above-described disadvantages. The object of the present invention is to prevent impurities such as fine particles generated by thermal expansion and contraction of members constituting the heating element from the plate heater to the outside. The object of the present invention is to prevent the material from being diffused and to obtain an object to be dried having a high yield, and to allow the heating element sandwiched between the metal plates to be constantly ventilated with the outside air, the vacuum chamber or the clean room.

  The present invention is a plate heater in which a heating element is housed in a back plate, and the peripheral edges of both plates are screwed and fixed in a state where the upper surface of the heating element and the upper surface of the back plate are in contact with the back surface of the face plate. A filter made of a metal or ceramic material that forms an outside air passage in contact with the body at an interval in at least one of the back plate and the face plate and blocks impurities of fine particles on each side of the outside air passage. The plate heater is characterized in that it is provided with a heat-resistant seal that ensures airtightness between the peripheral edge of the heating element and both plates.

  2. The plate heater according to claim 1, wherein lift pin holes for supporting an object to be dried pass through each of the heating element, the face plate, and the back plate at a plurality of locations in the thickness direction of the plate heater and penetrate the heating element. A seal plug is embedded in a back plate and a face plate around a lift pin hole in a part, and a heat-resistant seal is provided on each side of the face plate and the back plate on the outer peripheral surface of the seal plug.

  The heating element according to claim 1 or 2, wherein the heating element is any one of a mica heater, a sheathed heater, an aluminum cast heater, an aluminum embedded heater, and an aluminum plate heater.

  In claim 1, claim 2, or claim 3, the face plate and the back plate are made of a metal having good thermal conductivity including any of aluminum, stainless steel, and iron.

  In claim 1, claim 2, claim 3, or claim 4, the plate heater is installed in a clean room, a decompression tank, or a vacuum tank.

  In claim 1, claim 2, claim 3, claim 4 or claim 5, the mounting position of the plate heater installed in the decompression tank or the vacuum tank is any one of a bottom part, a ceiling part and a side wall part in the tank. Alternatively, it is provided at a plurality of sites.

  Generation of impurity particles such as fine particles due to heat generated by heating elements such as mica heaters, thermal expansion and thermal contraction due to the temperature drop of the heaters, etc. due to friction etc Even in the case of being collected and dried in a clean room or in a vacuum environment, the adhesion of impurities to a material to be dried such as a substrate is eliminated, and the yield of products is greatly improved. In addition, the heating element always communicates with the atmosphere in the clean room or the vacuum chamber, which is outside air, and also communicates with the vacuum environment in the atmosphere or the vacuum chamber. Moreover, in the present invention, when the material to be dried is put into a vacuum chamber or the like, or when the material to be dried is taken out after completion of drying, the pressure is atmospheric pressure. Since the fine impurity particles perform a respiration movement that separates and repeats adsorption due to pressure change, clogging of the filter itself is eliminated, and continuous use is possible.

  That is, an outside air passage that contacts the heating element is formed at an interval in at least one of the back plate and the face plate, and a metal filter or a ceramic filter that blocks fine impurity particles is provided near each outside air in the outside air passage. Therefore, since the heating element is always placed in the same environment as the clean room, or in the same environment as the reduced pressure or vacuum environment, the temperature management of the plate heater is unified, and temperature control and the like are facilitated.

  Even if the plate heater according to the present invention has a structure including a lift pin for supporting an object to be dried such as a substrate, the path of the lift pin is completely blocked by the heat generating element and the heat-resistant seal, and thus is generated by the heat generating element. Fine impurity particles are not released into the clean room or vacuum environment through the lift pin passage.

It is a schematic sectional drawing which shows one Example of this invention. It is a top view of the face plate in FIG. It is a top view of the back plate in FIG. In another Example of this invention, it is a schematic sectional drawing which shows the case where the lift pin which supports a to-be-dried object is provided. It is a top view of the face plate in FIG. It is a top view of the back plate in FIG. It is a schematic explanatory drawing which shows the case where the plate heater which is the other Example of this invention is installed in a vacuum chamber. It is a schematic sectional drawing which shows a prior art example. It is a top view of the face plate which shows a prior art example. It is a top view of the back plate which shows a prior art example.

An embodiment of the present invention will be described below with reference to the drawings.
1 is a plate heater. The plate heater 1 is in contact with the upper surface of the back plate 2 and the back surface of the face plate 3 in close contact with each other. The back surface of the heating element 4 is in contact with the upper surface of the heating element 4.

The back plate 2 and the face plate 3 are made of a metal material such as aluminum, aluminum alloy, stainless steel, or iron, and a material having good thermal conductivity is preferable.
The back plate 2 and the face plate 3 may have various shapes depending on the application. For example, the back plate 2 and the face plate 3 have the same size of 420 mm in length and 520 mm in width, the thickness of the back plate 2 is 6 mm, and the thickness of the face plate 3. Although the case of 8 mm was shown, it is not limited to these sizes. The maximum temperature during continuous use is 350 ° C. for aluminum, 800 ° C. for iron, and 600 ° C. for stainless steel. However, considering the durability of the heating element 4, it is preferable to use it at the above temperature or lower. In this example, it is used in the range of 50 ° C to 500 ° C.

The heating element 4 accommodated in the hollow part 2a formed in the upper surface of the back plate 2 shows the case where the mica heater 4a is employ | adopted in this example. The mica heater 4a is formed by placing a heat generating stainless steel foil (not shown) between the upper and lower insulating mica plates to form a thickness of 1 mm. The upper surface of the mica heater 4a It is formed flush.
The back plate 2 in a state of sandwiching the mica heater 4a and the outer rectangular peripheral edge of the face plate 3 where the mica heater 4a is not disposed are screwed (not shown) and fixed integrally.
Although the mica heater 4a of this example has shown the case of AC200V, 3.5KW electric power, it is not limited to this numerical value, and a voltage and electric power can be changed suitably according to the intended purpose.
The heating element 4 is not limited to the mica heater 4a, but may be a metal plate embedded with a sheathed heater (not shown), or other means.

The important point in the present invention is that the outer peripheral edge of the mica heater 4a, which is the heating element 4 housed in the groove 2a on the upper surface of the back plate 2, the contact portion of the back plate 2 with the outer peripheral edge of the mica heater 4a, and the face plate 3 is provided with a heat-resistant seal 5 between the contact portion with the outer peripheral edge of the mica heater 4a so that impurity particles such as fine particles generated from the heating element 4 do not leak to the outside, and the mica that is the heating element 4 A vent hole 6 through which the heater 4 a communicates with the outside is formed in the thickness direction of the back plate 2, and a metal filter 7 is provided near the end of the vent hole 6. The heat-resistant seal 5 provided on the outer peripheral edge of the mica heater 4a is sealed with a heat-resistant O-ring. As the heat-resistant O-ring, a heat-resistant resin such as fluorine resin or polyimide is used. A metal filter 7 is provided near the end of the ventilation hole 6 through which the mica heater 4a communicates with the outside. The metal filter 7 is made of a sintered metal having a large number of porous materials, such as a ceramic filter or a stainless steel filter.
Although not shown in the figure, the plate heater 1 is provided with a thermocouple (not shown) for controlling the temperature of the heater 4.

FIGS. 4 to 7 are views showing a case where a lift pin for supporting an object to be dried is provided in another embodiment of the present invention, and FIG. 7 is a schematic view showing a case where the plate heater 1 is installed in a vacuum chamber. It is explanatory drawing.
Lift pin holes 8 for supporting the material to be dried A are formed at a plurality of positions in the thickness direction of the plate heater 1 so as to penetrate the heating element 4, the face plate 3, and the back plate 2. A tubular seal plug 9 into which a lift pin (not shown) is inserted is embedded in the back plate 2 and the face plate 3 around the lift pin hole 8 at a portion that penetrates the heating element 4. A heat-resistant seal 10 is provided on each side of the face plate 3 and the back plate 2 in the outer peripheral surface of the seal plug 9. The lift pins are adjusted in advance to the same height in order to support the object A to be dried such as a substrate conveyed from the outside through the door (not shown) of the vacuum chamber 11 at the same level. The lift pin may be lowered after being received and placed directly on the face plate 3 or may be set to a predetermined height from the upper surface of the face plate 3. The lift pins are moved up and down by vertical drive means (not shown). Moreover, the case where the to-be-dried object A is being fixed in the vacuum chamber 11 without a lift pin moving up and down as needed may be sufficient.

  The present invention is a precision component field capable of drying an object to be dried in a clean environment in which impurities such as semiconductor wafers, glass substrates for liquid crystal displays, optical disk substrates, pharmaceuticals, foods and the like are not mixed, pharmaceuticals, It can be used in a wide range of industrial fields such as food.

DESCRIPTION OF SYMBOLS 1 Plate heater 2 Back plate 2a Recessed part 3 Face plate 4 Heating element 4a Mica heater 5 Heat resistant seal 6 Vent hole 7 Metal filter 8 Lift pin hole 9 Seal plug 10 Heat resistant seal 11 Vacuum chamber A

Claims (6)

A plate heater in which a heating element is housed in a back plate, and the periphery of both plates is screwed and fixed in a state where the upper surface of the heating element and the upper surface of the back plate are in contact with the back surface of the face plate. A passage is formed in at least one of the back plate and the face plate with an interval, and a filter made of a metal or ceramic material that prevents impurities of fine particles is provided near the outside air in the outside air passage, and the heat generation A plate heater comprising a heat-resistant seal that ensures airtightness between the peripheral edge of the body and both plates. 2. The plate heater according to claim 1, wherein lift pin holes for supporting an object to be dried pass through each of the heating element, the face plate, and the back plate at a plurality of locations in the thickness direction of the plate heater and penetrate the heating element. A seal plug is embedded in a back plate and a face plate around a lift pin hole in a part, and a heat-resistant seal is provided on each side of the face plate and the back plate on the outer peripheral surface of the seal plug. The plate heater according to 1. 3. The plate heater according to claim 1, wherein the heating element is any one of a mica heater, a sheathed heater, an aluminum cast heater, an aluminum embedded heater, and an aluminum plate heater. 4. The metal plate according to claim 1, wherein the face plate and the back plate are made of a metal having good thermal conductivity, including aluminum, stainless steel, and iron. The plate heater according to claim 2 or claim 3. In Claim 1, Claim 2, Claim 3, or Claim 4, the plate heater is installed in a clean room, a decompression tank, or a vacuum tank. 4. The plate heater according to 4. In claim 1, claim 2, claim 3, claim 4 or claim 5, the mounting position of the plate heater installed in the decompression tank or the vacuum tank is any one of a bottom part, a ceiling part and a side wall part in the tank. Alternatively, the plate heater according to claim 1, 2, 3, 4 or 5, wherein the plate heater is provided at a plurality of portions.

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