In-liquid plasma processing device

Abstract

The in-liquid plasma processing device disclosed herein includes a processing space and an active species supply unit that is configured to supply in-liquid plasma to the processing space. The active species supply unit includes: a generation space that is configured to have a liquid introduced thereto; a shower plate that is configured to introduce an active species included in in-liquid plasma generated in the generation space into the processing space, and that has a plurality of shower holes arranged spread out along the processing space; and a microwave supply unit that includes a radial line slot antenna having a plurality of slots arranged spread out along the generation space. The microwave supply unit is configured to supply microwaves to the liquid in the generation space via the radial line slot antenna.

Description

Submerged plasma treatment equipment

[0001] An exemplary embodiment of the present disclosure relates to a submerged plasma processing apparatus.

[0002] In plasma etching, plasma generated by a Radial Line Slot Antenna (RLSA) is sometimes used to improve productivity in the miniaturization and large diameter of IC manufacturing. Patent Document 1 discloses a technique for inducing in-liquid plasma using a slot antenna. ２ The active species generated by the O plasma in liquid are expected to be applied to the modification of films used in semiconductor manufacturing (Patent Documents 2 and 3), photoresist film stripping (Patent Document 4), and the like.

[0003] Japanese Patent Application Laid-Open No. 2014-127705 Japanese Patent Application Laid-Open No. 2013-515355 U.S. Patent No. 7,521,378 Japanese Patent No. 7,105,649

[0004] The present disclosure provides a technique for reducing bias in the concentration distribution of active species while increasing the active species in a process using active species contained in in-liquid plasma.

[0005] In one exemplary embodiment, a submerged plasma processing apparatus is provided. The submerged plasma processing apparatus includes a processing space, an active species supply unit, a holding unit, and an exhaust path. The processing space is configured so that a wafer is processed using active species contained in the submerged plasma. The active species supply unit is configured to supply active species to the processing space. The holding unit is disposed opposite the active species supply unit across the processing space and is configured to hold the wafer. The exhaust path is configured to exhaust the active species supplied to the processing space from the processing space to the outside. The active species supply unit includes a generation space, a microwave supply unit, and a shower plate. The generation space is configured so that a liquid used to generate the submerged plasma is introduced therein. The microwave supply unit is configured to supply microwaves to the liquid introduced into the generation space to generate the submerged plasma. The shower plate is configured to introduce the active species together with the liquid into the processing space and has a plurality of shower holes arranged along the processing space. The microwave supply unit includes a radial line slot antenna having a plurality of slots arranged extending along the generation space, and is configured to supply microwaves to the liquid in the generation space via the radial line slot antenna.

[0006] According to one exemplary embodiment, there is provided a technique for increasing the amount of activated species while reducing the bias in the concentration distribution of activated species in a process using activated species contained in in-liquid plasma.

[0007] 1A and 1B are diagrams illustrating an example of a submerged plasma processing apparatus according to an embodiment of the present invention;

[0008] Various exemplary embodiments are described below.

[0009] In one exemplary embodiment, a submerged plasma processing apparatus is provided. The submerged plasma processing apparatus includes a processing space, an active species supply unit, a holding unit, and an exhaust path. The processing space is configured so that a wafer is processed using active species contained in the submerged plasma. The active species supply unit is configured to supply active species to the processing space. The holding unit is disposed opposite the active species supply unit across the processing space and is configured to hold the wafer. The exhaust path is configured to exhaust the active species supplied to the processing space from the processing space to the outside. The active species supply unit includes a generation space, a microwave supply unit, and a shower plate. The generation space is configured so that a liquid used to generate the submerged plasma is introduced therein. The microwave supply unit is configured to supply microwaves to the liquid introduced into the generation space to generate the submerged plasma. The shower plate is configured to introduce the active species together with the liquid into the processing space and has a plurality of shower holes arranged along the processing space. The microwave supply unit includes a radial line slot antenna having a plurality of slots arranged extending along the generation space, and is configured to supply microwaves to the liquid in the generation space via the radial line slot antenna.

[0010] According to the above-described in-liquid plasma processing apparatus, the use of in-liquid plasma can increase the number of active species in the in-liquid plasma. Furthermore, the above-described in-liquid plasma processing apparatus uses a radial line slot antenna having a plurality of slots arranged in a spreading manner along the generation space, and a shower plate having a plurality of shower holes arranged in a spreading manner along the processing space. The use of such a radial line slot antenna and shower plate can reduce the bias in the concentration distribution of active species in the processing space.

[0011] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0012] The configuration of a submerged plasma processing apparatus 1 according to one exemplary embodiment will be described with reference to Figures 1 and 2. Figure 1 is a diagram illustrating the configuration defining an example generation space 10 included in the submerged plasma processing apparatus 1.

[0013] The in-liquid plasma processing apparatus 1 is an apparatus that generates in-liquid plasma and processes a wafer W using the in-liquid plasma. The in-liquid plasma processing apparatus 1 includes a processing space PA, an active species supply unit PS, a holding unit WH, and a discharge path DP. The processing space PA is configured so that processing using active species contained in the in-liquid plasma is performed on the wafer W. The discharge path DP is configured to discharge the in-liquid plasma supplied to the processing space PA to the outside.

[0014] The activated species supply part PS is configured to supply activated species contained in the in-liquid plasma to the processing space PA. The activated species supply part PS includes a generation space 10, a microwave supply part MS, and a shower plate 13. The activated species supply part PS also includes a storage chamber 11 and a wall part 12. Note that although the in-liquid plasma processing apparatus 1 illustrated in FIG. 1 includes one activated species supply part PS, the present invention is not limited to this and may include a plurality of activated species supply parts PS.

[0015] The storage chamber 11 is configured to store the liquid to be introduced into the generation space 10. The wall portion 12 extends between the storage chamber 11 and the generation space 10 to define the generation space 10. The planar shape of the generation space 10 shown in Figure 2 is circular as an example, but is not limited to this and may be other shapes.

[0016] An outer surface 12a of the wall portion 12 is exposed to the storage chamber 11. An inner surface 12b of the wall portion 12 is exposed to the generation space 10. The wall portion 12 includes a communication hole 12c that connects the storage chamber 11 and the generation space 10 and is configured to introduce liquid from the storage chamber 11 to the generation space 10.

[0017] The communication hole 12c extends from the outer surface 12a to the inner surface 12b. In plan view, the center axis AX2 of the communication hole 12c extends at an angle θ with respect to a tangent TG to the inner surface 12b at the intersection of the communication hole 12c and the inner surface 12b. The angle θ satisfies 0 degrees < θ ≦ 90 degrees. That is, the communication hole 12c may extend perpendicular to the tangent TG or at an acute angle to the tangent TG. The active species supply section PS may include multiple communication holes 12c. While FIG. 2 illustrates eight communication holes 12c, the number of communication holes 12c may be one or a number other than eight.

[0018] The holding part WH is disposed opposite the active species supply part PS across the processing space PA and is configured to hold a wafer W. The wafer W can be placed on a mounting surface HS of the holding part WH. A central axis AX1 of the holding part WH can be perpendicular to the mounting surface HS of the wafer W. The holding part WH is configured to be rotatable about the central axis AX1. The holding part WH can be rotated about the central axis AX1 by a driving device (not shown). A convex narrow portion (not shown) can be provided on the outer periphery of the holding part WH between the outer periphery of the holding part WH and the ceiling of the processing space PA. In other words, the outer periphery (edge) of the holding part WH can be shaped to rise toward the ceiling of the processing space PA. This allows the processing space PA above the wafer W to be filled with a liquid containing active species when the wafer W is held on the holding part WH. The processing space PA is preferably filled with a liquid containing active species, but it is sufficient if at least the wafer W held by the holder WH is immersed in the liquid containing active species.

[0019] The shower plate 13 is disposed above the mounting surface HS of the holder WH and facing the mounting surface HS. A processing space PA is provided between the shower plate 13 and the mounting surface HS.

[0020] The generation space 10 is configured so that the liquid used to generate in-liquid plasma is introduced from a liquid supply device LS via an introduction path IP. The generation space 10 is located above the shower plate 13 and between the shower plate 13 and the antenna 20. The liquid supplied from the liquid supply device LS may be, for example, water, but liquids other than water may also be used.

[0021] The microwave supply unit MS is configured to generate in-liquid plasma by supplying microwaves to the liquid introduced into the generation space 10. The microwave supply unit MS includes the generation space 10, a dielectric window 16, an antenna 20, a dielectric plate 25, a coaxial waveguide 30, a microwave generator 35, a rectangular waveguide 36, and a mode converter 37.

[0022] The coaxial waveguide 30 includes an inner conductor 31 and an outer conductor 32. The inner conductor 31 passes through the dielectric plate 25 and is connected to the antenna 20. A microwave generator 35 is connected to the coaxial waveguide 30 via a mode converter 37 and a rectangular waveguide 36.

[0023] The microwaves generated by the microwave generator 35 propagate sequentially through the rectangular waveguide 36, the mode converter 37, the coaxial waveguide 30, and the dielectric plate 25. The rectangular waveguide 36, the mode converter 37, the coaxial waveguide 30, and the dielectric plate 25 function as a microwave introduction path.

[0024] The microwave supply unit MS includes an antenna 20 having a plurality of slots 21 arranged extending along the generation space 10, and is configured to supply microwaves to the liquid in the generation space 10 via the antenna 20. The antenna 20 is provided between the dielectric window 16 and the dielectric plate 25. The materials of the dielectric window 16 and the dielectric plate 25 are both transparent to microwaves and may be dielectric materials such as quartz, aluminum oxide, aluminum nitride, etc.

[0025] The antenna 20 may be a radial line slot antenna. The multiple slots 21 are arranged to extend along the generation space 10. This allows microwaves to be supplied uniformly to the liquid introduced into the generation space 10 without bias. Therefore, bias in the concentration distribution of active species in the in-liquid plasma generated in the generation space 10 can be reduced.

[0026] The microwaves propagating through the dielectric plate 25 are supplied into the generation space 10 from the multiple slots 21 of the antenna 20 through the dielectric window 16. The microwaves form an electric field below the dielectric window 16 in the generation space 10, generating plasma in the liquid introduced into the generation space 10, thereby generating in-liquid plasma.

[0027] The shower plate 13 is configured to introduce active species contained in the in-liquid plasma generated in the generation space 10 into the processing space PA. The shower plate 13 has a plurality of shower holes 13a. The plurality of shower holes 13a are arranged in a spread manner along the processing space PA. Therefore, the active species can be uniformly supplied from the generation space 10 to the processing space PA without unevenness in the concentration of the active species. Therefore, unevenness in the concentration distribution of the active species introduced into the processing space PA can be reduced. In particular, unevenness in the concentration distribution of the active species on the wafer W placed on the mounting surface HS of the holder WH can be further reduced.

[0028] The slot pattern of the plurality of slots 21 in the antenna 20 and the shower hole pattern of the plurality of shower holes 13a in the shower plate 13 can be set in accordance with the adjustment of the concentration distribution of the active species in the processing space PA.

[0029] According to the in-liquid plasma processing apparatus 1 described above, the use of in-liquid plasma can increase the number of active species in the in-liquid plasma.

[0030] The liquid plasma processing apparatus 1 also uses an antenna 20 having a plurality of slots 21 arranged to extend along the generation space 10, and a shower plate 13 having a plurality of shower holes 13a arranged to extend along the processing space PA. By using such an antenna 20 and shower plate 13, it is possible to reduce the bias in the concentration distribution of active species in the processing space PA.

[0031] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0032] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E9] below.

[0033] [E1] An in-liquid plasma processing apparatus comprising: a processing space configured to perform processing on a wafer using active species contained in in-liquid plasma; an active species supply unit configured to supply the active species to the processing space; a holding unit arranged opposite the active species supply unit across the processing space and configured to hold the wafer; and a discharge path configured to discharge the active species supplied to the processing space from the processing space to the outside, wherein the active species supply unit includes: a generation space configured to be introduced with a liquid used for generating the in-liquid plasma; a microwave supply unit configured to supply microwaves to the liquid introduced into the generation space to generate the in-liquid plasma; and a shower plate configured to introduce the active species together with the liquid into the processing space, the shower plate having a plurality of shower holes arranged extending along the processing space, wherein the microwave supply unit includes a radial line slot antenna having a plurality of slots arranged extending along the generation space, and configured to supply the microwaves to the liquid in the generation space via the radial line slot antenna.

[0034] [E2] The liquid plasma processing apparatus described in [E1] above, wherein the active species supply unit includes: a storage chamber configured to store the liquid to be introduced into the generation space; and a wall portion extending between the storage chamber and the generation space and defining the generation space, the wall portion including a communication hole configured to communicate the storage chamber and the generation space and to introduce the liquid from the storage chamber into the generation space.

[0035] [E3] The liquid plasma processing apparatus according to [E2], wherein the communication hole extends from the outer surface of the wall portion to the inner surface of the wall portion, and the communication hole extends perpendicularly to a tangent to the inner surface at an intersection of the communication hole and the inner surface in a plan view.

[0036] [E4] The liquid plasma processing apparatus according to [E2], wherein the communication hole extends from the outer surface of the wall portion to the inner surface of the wall portion, and the communication hole extends at an acute angle to a tangent to the inner surface at an intersection of the communication hole and the inner surface in a plan view.

[0037] [E5] The in-liquid plasma processing apparatus according to any one of [E2] to [E4] above, wherein the active species supply unit includes a plurality of the communication holes.

[0038] [E6] The liquid plasma processing apparatus according to any one of [E1] to [E5] above, wherein the liquid is water.

[0039] [E7] The submerged plasma processing apparatus according to any one of [E1] to [E6] above, comprising a plurality of the activated species supply units.

[0040] [E8] The liquid plasma processing apparatus according to any one of [E1] to [E7] above, wherein the central axis of the holding unit is perpendicular to the wafer mounting surface, and the holding unit is configured to be rotatable about the central axis as a rotation axis.

[0041] [E9] The in-liquid plasma processing apparatus according to any one of [E1] to [E8] above, wherein a slot pattern of the radial line slot antenna and a shower hole pattern of the shower plate are set in accordance with adjustment of a concentration distribution of the active species in the processing space.

[0042] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

[0043] 1...submerged plasma processing apparatus, 10...generation space, 11...storage chamber, 12...wall portion, 12a...outer surface, 12b...inner surface, 12c...communicating hole, 13...shower plate, 13a...shower hole, 20...antenna, 30...coaxial waveguide, 31...inner conductor, 32...outer conductor, 35...microwave generator, 36...rectangular waveguide, 37...mode converter, AX1...central axis, AX2...hole central axis, DP...discharge path, HS...mounting surface, IP...inlet path, LS...liquid supply device, MS...microwave supply unit, PA...processing space, PS...active species supply unit, TG...tangent, W...wafer, WH...holding unit.

Claims

1. An in-liquid plasma processing apparatus comprising: a processing space configured to subject a wafer to processing using active species contained in in-liquid plasma; an active species supply unit configured to supply the active species to the processing space; a holding unit arranged opposite the active species supply unit across the processing space and configured to hold the wafer; and a discharge path configured to discharge the active species supplied to the processing space from the processing space to the outside, wherein the active species supply unit comprises: a generation space configured to introduce a liquid used for generating the in-liquid plasma; a microwave supply unit configured to supply microwaves to the liquid introduced into the generation space to generate the in-liquid plasma; and a shower plate configured to introduce the active species together with the liquid into the processing space and having a plurality of shower holes arranged extending along the processing space, and the microwave supply unit includes a radial line slot antenna having a plurality of slots arranged extending along the generation space, and is configured to supply the microwaves to the liquid in the generation space via the radial line slot antenna.

2. The liquid plasma processing apparatus of claim 1, wherein the active species supply unit includes a storage chamber configured to store the liquid to be introduced into the generation space, and a wall portion extending between the storage chamber and the generation space and defining the generation space, the wall portion including a communication hole communicating the storage chamber and the generation space and configured to introduce the liquid from the storage chamber into the generation space.

3. The liquid plasma processing apparatus according to claim 2, wherein the communication hole extends from the outer surface of the wall portion to the inner surface of the wall portion, and the communication hole extends perpendicularly to a tangent to the inner surface at the intersection of the communication hole and the inner surface in a plan view.

4. The liquid plasma processing apparatus of claim 2, wherein the communication hole extends from the outer surface of the wall portion to the inner surface of the wall portion, and the communication hole extends, in a plan view, at an acute angle to a tangent to the inner surface at the intersection of the communication hole and the inner surface.

5. The liquid plasma processing apparatus according to claim 2, wherein the active species supply section includes a plurality of the communication holes.

6. The liquid plasma processing apparatus according to any one of claims 1 to 5, wherein the liquid is water.

7. The liquid plasma processing apparatus according to claim 1, further comprising a plurality of the activated species supply units.

8. The liquid plasma processing apparatus according to any one of claims 1 to 5, wherein a central axis of the holding part is perpendicular to a surface on which the wafer is placed, and the holding part is configured to be rotatable about the central axis as a rotation axis.

9. The liquid plasma processing apparatus according to any one of claims 1 to 5, wherein a slot pattern of the radial line slot antenna and a shower hole pattern of the shower plate are set in accordance with adjustment of a concentration distribution of the active species in the processing space.

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