Patent Application
20110209829
The present invention relates to an apparatus for causing a treatment gas to contact a surface of an object and treating the surface of the object, and in particular to a surface treatment apparatus that is suitable for treatment using a treatment gas having toxicity or corrosiveness.
There are known apparatuses that blow treatment gases to an object such as a glass substrate or a semiconductor wafer and that perform surface treatment such as etching, cleaning, surface modification, or film forming. Treatment gases used in such surface treatment often contain components undesirable for safety or environment when they leak to the outside. Therefore, in general, a treatment space is surrounded by a treatment housing (chamber) to prevent the treatment gases from leaking to the outside.
Each of the surface treatment apparatuses of the PATENT LITERATURES 1 and 2 includes: an inlet through which an object is led to a treatment housing (chamber); and an outlet through which the object is led out of the treatment housing. Each of the inlet and the outlet has a slit-like shape. A mitigation chamber is provided at each end of the treatment housing to mitigate a plasma-generating gas flowing out of the treatment housing and the outside air flowing into the treatment housing. Gas inside the treatment housing is discharged through an exhaust port.
The surface treatment apparatus of PATENT LITERATURE 3 includes: an internal housing which surrounds a discharge plasma generating unit; and an external housing which surrounds the internal housing. The internal pressure of the space between the external housing and the internal housing is lower than the internal pressure of the internal housing, and is lower than the outside air pressure. As a result, a treatment gas flows out of the internal housing into the space between the internal housing and the external housing, and outside air flows into the external housing.
[PATENT LITERATURE 1] Japanese Patent No. 4058857 (FIG. 9)
[PATENT LITERATURE 2] Japanese Patent No. 3994596 (FIG. 7)
[PATENT LITERATURE 3] Japanese Patent Laid-Open Publication No. 2003-142298
A treatment housing needs an opening through which an object is taken in and out. There is also a possibility that a treatment gas in the treatment housing leaks through this opening. In order to prevent such a leak, it may be considered that an exhaust system is connected to the treatment housing and discharges the gas from the treatment housing. This can direct the direction of the gas flow at the opening toward the outside of the treatment housing into a direction toward the inside of the treatment housing. However, the gas flowing in through the opening tends to be a turbulent flow. This makes gas distribution in the treatment housing unstable. In a case where external air outside the treatment housing becomes turbulent, the turbulence may be propagated to the interior of the treatment housing via the opening. The present inventor has confirmed a phenomenon in which when a swirl flow is formed outside the opening, gas in the opening comes out of the opening to the outside.
The present invention is made in view of the above situation, and intended to stabilize the gas flow at an opening, which is provided in a treatment housing for surface treatment, and through which the object is taken in and out.
In order to solve the above problem, the present invention is directed to an apparatus for causing a treatment gas to contact a surface of an object and treating the surface, the apparatus comprising:
a treatment housing including an opening through which the object is carried in or out in a conveying direction and a treatment space in which the surface treatment is performed;
a supply system for supplying the treatment gas to the treatment space; and
an exhaust system for discharging gas from an interior of the treatment housing, wherein
the opening of the treatment housing is defined by a pair of flow-rectifying faces which face each other, with an interval therebetween, in a direction perpendicular to the conveying direction, and a depth of the opening along the conveying direction is twice or more of the interval.
By the discharging operation by the exhaust system, a gas flow directed from the outside to the inside of the treatment housing can be formed at the opening. Accordingly, it is possible to prevent the treatment gas from leaking to the outside through the opening. In addition, with the presence of the pair of flow-rectifying faces, it is possible to stabilize the flow of the gas flowing into the treatment housing through the opening, and to prevent the flowing-in gas from becoming a turbulent flow or to turn the flowing-in gas into a flow similar to a laminar flow. Accordingly, it is possible to stabilize gas distribution in the treatment housing and moreover in the treatment space. Therefore, the stability of the surface treatment can be ensured. Further, it is possible to prevent the interior of the treatment housing from being affected by the outside environment. For example, in a case where gas turbulence such as a swirl flow occurs outside the treatment housing, it is possible to prevent the turbulence from being propagated to the interior of the treatment housing via the opening, and thus, to prevent the gas inside the treatment housing from becoming a swirl flow or the like and leaking through the opening to the outside. Therefore, it is possible to prevent, in a further assured manner, the treatment gas and the post-treatment gas from leaking.
Preferably, the depth of the opening is six to ten times of the interval. This can stabilize the gas flow at the opening in a further assured manner.
Preferably, the opening has a rectangular shape.
In a case where the intervals differ depending on their positions in the opening, the interval is defined as an average value of the intervals. Preferably, the depth of the opening is twice or more of the average value of the intervals. More preferably, the depth of the opening is six to ten times of the average value of the intervals.
According to the present invention, it is possible to stabilize the gas flow at the opening through which the object is carried in or out. Furthermore, it is possible to prevent the gas distribution in the treatment housing from varying, thereby ensuring the stability of the surface treatment.
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Hereinafter, an embodiment of the present invention will be described.
The length (dimension in the lateral direction of
As shown in
The treatment housing 10 has a container-like shape and is large enough for the object 9 to be arranged therein. A treatment space 19 is formed in a substantially center portion in the treatment housing 10. In other words, the treatment housing 10 surrounds the treatment space 19. The treatment space 19 is defined between a supply nozzle 33 described below and the object 9 to be arranged below the supply nozzle 33. In the drawing, the thickness (vertical dimension) of the treatment space 19 is shown in an exaggerated manner. The actual thickness of the treatment space 19 is about 0.5 to 5 mm.
A carry-in opening 13 is formed in a wall 11 on one end side (right side in
The conveyance means 20 is structured as a roller conveyor. A large number of rollers 21 of the roller conveyor are arranged with their axes perpendicular to the plane of the drawing of
The conveyance means 20 is not limited to a roller conveyor, and may be structured as a mobile stage, a floating stage, a robot arm, or the like.
The supply system 30 includes a source gas supply unit 31 and the supply nozzle 33. A supply passage 32 extends from the source gas supply unit 31. The supply passage 32 is connected to the supply nozzle 33. The supply nozzle 33 is located on a ceiling portion of the treatment housing 10. Although not shown in detail, the supply nozzle 33 extends in the direction perpendicular to the plane of the drawing of
The supply system 30 supplies the treatment space 19 with a treatment gas containing a reaction component corresponding to the type of treatment to be performed, a material component for the reaction component, and the like. Treatment gas components (such as the reaction component, the material component, and the like mentioned above) often have environmental impact, toxicity, and corrosiveness. According to the present embodiment for silicon etching, a fluorine-based reaction component and an oxidizing reaction component are used as the reaction component. Examples of the fluorine-based reaction component include HF, COF2, fluorine radicals, and the like. A fluorine-based reaction component can be generated by, for example, humidifying a fluorine-based material with water (H2O) and then converting the resultant material into a plasma (including decomposition, excitation, activation, ionization, and the like). In this embodiment, CF4 is used as the fluorine-based material. As the fluorine-based material, instead of CF4, other PFCs (perfluorocarbons) such as C2F6, C3F8, and C3F8 may be used; HFCs (hydrofluorocarbons) such as CHF3, CH2F2, and CH3F may be used; or fluorine containing compounds such as SF6, NF3, and XeF2 other than PFCs and HFCs may be used.
The fluorine-based material may be diluted with a dilution gas. As the dilution gas, for example, a rare gas such as Ar or He, or N2 is used. As an additive agent to the fluorine-based material, an OH group containing a compound such as alcohol may be used instead of water (H2O).
Examples of the oxidizing reaction component include O3, and O radicals. In this embodiment, O3 is used as the oxidizing reaction component. O3 can be generated from oxygen (O2) by using an ozonizer. The oxidizing reaction component may be generated by converting an oxygen-based material such as O2 into a plasma.
Converting the fluorine-based material and the oxygen-based material into a plasma can be performed by leading a gas containing the above described materials into a plasma space between a pair of electrodes of a plasma generating apparatus. Preferably, the plasma conversion is performed at a pressure near the atmospheric pressure. Here, “a pressure near the atmospheric pressure” means a range of 1.013×104 to 50.663×104 Pa. In consideration of easy pressure regulation and a simpler apparatus structure, the pressure is preferably 1.333×104 to 10.664×104 Pa, and more preferably 9.331×104 to 10.397×104 Pa.
According to the present embodiment for silicon etching, CF4 which is the fluorine-based material is diluted with Ar and then H2O is added to the diluted CF4 to yield a fluorine-based source gas (CF4+Ar+H2O) in the source gas supply unit 31. This fluorine-based source gas is led via the supply passage 32 to the supply nozzle 33. The supply nozzle 33 is provided with a pair of electrodes. The fluorine-based source gas is converted into a plasma between the electrodes. The supply nozzle 33 also serves as a plasma generating apparatus. Accordingly, a fluorine-based reaction component such as HF is generated. Although not shown, O3 is separately generated as an oxidizing reaction component by an ozonizer, is led into the supply nozzle 33, and mixed with the plasma gas described above. As a result, a treatment gas containing a fluorine-based reaction component (such as HF) and an oxidizing reaction component (such as O3) is generated. It is understood that the treatment gas contains source gas components (such as CF4, H2O, Ar, and O2). This treatment gas is blown from a nozzle hole, which is on the bottom surface (tip surface) of the supply nozzle 33, to the treatment space 19. The supply flow rate of the treatment gas is, for example, about 32 slm.
It should be noted that a treatment gas containing a fluorine-based reaction component and an oxidizing reaction component may be generated in the gas supply unit 31 and the generated treatment gas may be sent via the supply passage 32 to the supply nozzle 33 to be blown.
The treatment gas blown out of the supply nozzle 33 is blown to the object 9 in the treatment space 19, and thus the surface of the object 9 is treated. In silicon etching, silicon is oxidized by the oxidizing component (such as O3) in the treatment gas, the oxidized silicon reacts with the fluorine-based reaction component (such as HF) in the treatment gas, and SiF4, which is a volatile component, is generated. Accordingly, the silicon layer on the surface of the object 9 can be removed.
Next, the exhaust system 40 will be described. An exhaust port 43 is provided at, for example, a substantially center portion of the bottom of the treatment housing 10. An exhaust passage 42 extends from the exhaust port 43. To the exhaust passage 42, a filter unit 45 and an exhaust pump 41 are provided in this order. Although not shown, a local exhaust port is formed at the bottom surface of the supply nozzle 33 and at a position adjacent to the nozzle hole from which the treatment gas is blown. A suction passage connected to the local exhaust port is drawn from an upper portion of the supply nozzle 33. This suction passage joins the exhaust passage 42 at a position upstream (to the exhaust port 43 side) of the filter unit 45. The local exhaust port and the suction passage are also components of the exhaust system 40.
The filter unit 45 includes a scrubber which removes HF and the like in the discharged gas, a mist trap which removes H2O in the discharged gas, and an ozone killer which removes O3 in the discharged gas, in addition to a filter which removes dusts and the like in the discharged gas.
By the drive of the exhaust pump 41 (exhaust means), the gas inside the treatment housing 10 is sucked into the exhaust passage 42 through the exhaust port 43. Further, the treatment gas having been blown to the object 9 in the treatment space 19 (hereinafter referred to as post-treatment gas) is mainly sucked into the local exhaust port, and is brought into the exhaust passage 42 via the suction passage. The post-treatment gas contains the components of the treatment gas (such as HF, O3, CF4, H2O, and Ar) and by-products (such as SiF4) resulting from the surface treatment reaction. There may be a case where a portion of the post-treatment gas leaks from the treatment space 19. In such a case, the post-treatment gas is sucked through the exhaust port 43.
The discharged gas flow rate of the exhaust system 40 is set to a rate that is low but sufficient to prevent the gas inside the treatment housing 10 from leaking through the carry-in opening 13 and the carry-out opening 14. In order to prevent the gas from leaking through the carry-in opening 13 and the carry-out opening 14, the discharged gas flow rate is set at a value greater than the supply flow rate of the treatment gas, so that the atmospheric gas (air) outside the treatment housing 10 flows into the treatment housing 10 through the carry-in opening 13 and the carry-out opening 14. In the present embodiment, the supply flow rate of the treatment gas is about 32 slm as described above, whereas the discharged gas flow rate of the first exhaust system 40 is, for example, about 200 to 400 slm.
Therefore, the most part of the discharged gas from the exhaust system 40 is air. The component that accounts for the greatest percentage in the discharged gas is nitrogen. The discharged gas further contains components of the post-treatment gas (such as HF, O3, CF4, H2O, Ar, and SiF4).
The surface treatment apparatus 1 further includes a reuse unit 50. The reuse unit 50 recovers the reaction components contained in the treatment gas from the gas discharged by the exhaust system 40. Specifically, the reuse unit 50 includes a separation/recovery device 51. The separation/recovery device 51 includes a separation membrane 52. The interior of the separation/recovery device 51 is divided into a condensation chamber 53 and a dilution chamber 54 by the separation membrane 52. As the separation membrane 52, a glassy polymer membrane is used, for example (see Japanese Patent No. 3151151). The separation membrane 52 allows CF4 (reaction component) to permeate itself at a relatively low speed, and nitrogen (impurity) to permeate itself at a relatively high speed. The exhaust passage 42 is connected to the condensation chamber 53 at a position downstream of the exhaust pump 41. The discharged gas from the exhaust pump 41 is led into the condensation chamber 53, and separated by the separation membrane 52 into a recovery gas which remains in the condensation chamber 53 and a release gas which permeates the separation membrane 52 to enter the dilution chamber 54. The recovery gas has a high concentration of CF4 (CF4=90 vol % or more) and a low flow rate. The release gas has a low concentration of CF4 (CF4=1 vol % or less) and a high flow rate.
It should be noted that although only one separation/recovery device 51 is shown in the drawing, the reuse unit 50 may include a plurality of separation/recovery devices 51. Such a plurality of separation/recovery devices 51 may be connected in series or in parallel, or in a combination of series and parallel arrangements.
A recovery passage 55 extends from a downstream end of the condensation chamber 53. The recovery passage 55 is connected to the source gas supply unit 31.
A release passage 46 extends from the dilution chamber 54. The release passage 46 is connected to detoxification equipment 47.
The structure of the carry-in opening 13 and the carry-out opening 14 of the treatment housing 10 will be described in detail.
As shown in
A pair of flow-rectifying plates 15, which are disposed to face each other in the vertical direction, is mounted to the carry-in-side wall 11. Hereinafter, when the upper flow-rectifying plate 15 and the lower flow-rectifying plate 15 are need to be identified separately, the upper flow-rectifying plate 15 is designated as a flow-rectifying plate 15A and the lower flow-rectifying plate 15 is designated as a flow-rectifying plate 15B.
As shown in
The lower flow-rectifying plate 15B is divided into two lower flow-rectifying plate parts 15b. As shown in
The upper flow-rectifying face 17 and the lower flow-rectifying face 18 are parallel to each other, and face each other in the vertical direction (a direction perpendicular to the conveying direction of the object 9 (the lateral direction in
A length L of each of the flow-rectifying faces 17 and 18 along the conveying direction (the lateral direction in
In this embodiment, the interval D between the flow-rectifying faces 17 and 18, that is, the thickness D of the opening 13, is about 5 mm, for example. Accordingly, the depth L of the opening 13 is 10 mm or more, and more preferably, 30 mm or more.
Although not shown in detail, the carry-out opening 14 also has a similar structure to that of the carry-in opening 13. That is, the opening 16 is formed in the carry-out-side wall 12. The flow-rectifying plates 15 are mounted to the opening 16, thereby forming a pair of the flow-rectifying faces 17 and 18 which face each other in the vertical direction. The carry-out opening 14 is defined between the flow-rectifying faces 17 and 18. The depth L of the carry-out opening 14 is twice or more, and more preferably six times or more, of the thickness D.
In the surface treatment apparatus 1 having the above described structure, the object 9 is carried into the interior of the treatment housing 10 through the carry-in opening 13 and led to the treatment space 19 by the conveyance means 20. Further, the treatment gas is supplied to the treatment space 19 by the supply system 30. The treatment gas contacts the object 9, thereby performing surface treatment such as etching. The treated object 9 is carried out of the treatment housing 10 through the carry-out opening 14. A plurality of the objects 9 are aligned on the roller conveyor 20 in such a manner as to be spaced from each other in a line, sequentially carried into the treatment housing 10 to be subjected to surface treatment, and then carried out of the treatment housing 10.
In parallel with the supply of the treatment gas, the gas inside the treatment housing 10 (including the post-treatment gas in the treatment space 19) is discharged by the exhaust system 40. By this discharging operation, gas outside the treatment housing 10 flows into the treatment housing 10 through the carry-in opening 13 and the carry-out opening 14. This allows the gas flows in the carry-in opening 13 and the carry-out opening 14 to be directed from the outside to the inside (inside the treatment housing 10). This makes it possible to prevent the treatment gas or the post-treatment gas in the treatment housing 10 from leaking to the outside through the carry-in opening 13 and the carry-out opening 14.
In addition, the depth L of each of the carry-in opening 13 and the carry-out opening 14 is twice or more of the thickness D (L≧2×D), and more preferably six times or more (L≧6×D). This makes it possible to stabilize the flow of the gas flowing in through the carry-in opening 13 and the carry-out opening 14, and to prevent the flowing-in gas from becoming a turbulent flow or to turn the flowing-in gas into a flow similar to a laminar flow. Accordingly, the gas distribution in the treatment housing 10 can be stabilized. In addition, the flow of the treatment gas in the treatment space 19 can be stabilized. Therefore, the stability of the surface treatment can be ensured. Further, it is possible to prevent the interior of the treatment housing 10 from being affected by the outside environment. For example, in a case where gas turbulence such as a swirl flow occurs outside the treatment housing 10, it is possible to prevent the turbulence from being propagated to the interior of the treatment housing 10 via the openings 13 and 14, and thus, to prevent the gas inside the treatment housing 10 from becoming a swirl flow or the like and leaking through the openings 13 and 14 to the outside. Therefore, it is possible to prevent in a further assured manner the treatment gas and the post-treatment gas from leaking.
The gas discharged out of the treatment housing 10 by the exhaust system 40 is filtered in the filter unit 45 and then compressed by the exhaust pump 41, and then led into the separation/recovery device 51. The discharged gas is separated into a recovery gas of a high CF4 concentration and a release gas of a low CF4 concentration by the separation/recovery device 51. The recovery gas is sent to the source gas supply unit 31 via the recovery passage 55. Thus, the reaction component (CF4) recovered in the separation/recovery device 51 can be returned into the recovery passage 55 for reuse. This allows reduction of the total amount of CF4 used in the surface treatment apparatus 1 and suppression of the running cost. The release gas is sent to the detoxification equipment 47 via the release passage 46 to be detoxified and then released to the atmosphere.
The exhaust flow rate of the exhaust system 40 is low but sufficient to prevent the post-treatment gas from leaking through the carry-in opening 13 and the carry-out opening 14. This allows the load to the separation/recovery device 51 to be reduced. Further, the load to the detoxification equipment 47 can also be reduced. This allows the size of the separation/recovery device 51 and the detoxification equipment 47 to be reduced.
Next, other embodiments of the present invention will be described. In the embodiments below, the same components as those in the embodiment described above are denoted by the same reference numerals, respectively, and the description thereof will be omitted.
The lower flow-rectifying plate 15B is attached to a portion, below the opening 16, of the outside surface of the carry-in-side wall 11. An upper surface of the lower flow-rectifying plate 15B and the lower edge of the opening 16 are flush with each other. The upper surface of the lower flow-rectifying plate 15B and the lower edge of the opening 16, which are flush with each other, form the lower flow-rectifying face 18.
Although not shown, the flow-rectifying plates 15 at the carry-out-side wall 12 also have a similar structure to that of the flow-rectifying plates 15 at the carry-in-side wall 11 shown in
Similarly to the first embodiment, the depth L of each of the carry-in opening 13 and the carry-out opening 14 is twice or more of the thickness D (L≧2×D), and preferably six times or more (L≧6×D). It should be noted that the flow-rectifying plates 15 may be attached not to the outside surfaces of but to the inside surfaces of the walls 11 and 12, in such a manner as to protrude to the interior of the treatment housing 10.
Although not shown, the carry-out opening 14 is defined similarly to the carry-in opening 13 shown in
In this embodiment, the length of each of the flow-rectifying plates 15 along the conveying direction of the object 9 coincides with the depth L of each of the carry-in opening 13 and the carry-out opening 14. Similarly to the above described embodiments, the depth L of each of the carry-in opening 13 and the carry-out opening 14 is twice or more of the thickness D (L≧2×D), and more preferably six times or more (L≧6×D).
The present invention is not limited to the above embodiments, and may be modified without departing from the scope of the present invention.
For example, the carry-in opening 13 and the carry-out opening 14 may be provided in a form of a single common opening. The conveyance means 20 may carry the object 9 through the common opening into the treatment housing 10, locate the object 9 in the treatment space 19 to be subjected to surface treatment, and then carry the treated object 9 through the common opening to the outside. The operations of carrying the object 9 into and out of the treatment housing 10 may be performed by an operator instead of the conveyance means 20.
The positions of the outer edges of the upper flow-rectifying plate 15A and the lower flow-rectifying plate 15B may not coincide with each other in the conveying direction of the object 9, or the positions of the inner edges of the upper flow-rectifying plate 15A and the lower flow-rectifying plate 15B may not coincide with each other in the conveying direction of the object 9. One of the upper and lower flow-rectifying plates 15A and 15B may protrude further than the other to the outside of the treatment housing 10, or to the inside of the treatment housing 10. In such a case, the depth (L), along the conveying direction, of the space (the opening 13 or 14) between the overlapping portions of the flow-rectifying plates 15 in their facing direction only has to be twice or more of the interval (D) between the flow-rectifying plates 15, and more preferably six times or more.
The present invention is applicable, for example, to manufacture of flat panel displays (FPDs) and semiconductor wafers.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-252334 | Sep 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/004634 | 9/16/2009 | WO | 00 | 5/16/2011 |
