Plasma processing apparatus

Abstract

To provide a plasma processing apparatus capable of effectively performing plasma processing on a processing object.SOLUTION: A plasma processing apparatus is a plasma processing apparatus that blows a plasma-containing gas to a processing object, and comprises: a nozzle having an injection port that injects the plasma-containing gas; and a buffer chamber that contains a bottom surface that is opposite to the processing object, and a side surface that surrounds the processing containing gas injected from the injection port and connects the bottom surface and the nozzle. The bottom surface includes: a bottom plate part; and an open part that injects the plasma-containing gas injected from the injection port, and the open part is larger than the injection port in regard to a width direction of the injection port when viewing it in a direction orthogonal to the bottom surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a plasma processing apparatus. [Background technology]

[0002] Plasma treatment devices are used in manufacturing processes for plastics, paper, textiles, semiconductors, liquid crystals, films, etc. By spraying a plasma-containing gas ejected from the plasma treatment device onto an object to be treated, for example, treatments such as improving the hydrophilicity of the surface of the object to be treated or removing organic matter present on the surface of the object to be treated are performed.

[0003] For example, Patent Document 1 listed below describes a plasma processing apparatus that performs surface processing on a processing object by spraying a plasma-containing gas onto the processing object while transporting the processing object.

[0004] Fig. 17 is a cross-sectional view showing a schematic structure of the plasma processing apparatus 100 described in Patent Document 1. In Fig. 17, an XYZ coordinate system is also shown in which the transport direction of the processing object S1 is the X direction, the direction in which the plasma processing apparatus 100 and the processing object S1 face each other is the Z direction, and the direction perpendicular to the X direction and the Z direction is the Y direction.

[0005] 17, the plasma processing apparatus 100 includes an electrode 101, a ground electrode 102, an opposing surface forming part 102a that contacts the ground electrode 102 to form an opposing surface with the electrode 101, a dielectric 103 that contacts the electrode 101, and a gas flow passage 104 formed by the dielectric 103 and the opposing surface forming part 102a. The opposing surface forming part 102a has an ejection port 105 that ejects gas that flows through the gas flow passage 104 on the side of the processing object S1. The plasma processing apparatus 100 also includes a cover 106 and a fixing screw 107 that contacts the electrode 101 with the dielectric 103.

[0006] The plasma processing apparatus 100 applies a high-frequency voltage between the electrode 101 and the ground electrode 102 to generate a discharge in the gas flow passage 104, and generates a plasma-containing gas P1 from the raw material gas G1 introduced into the gas flow passage 104 through the cover 106. Then, the plasma processing apparatus 100 ejects the plasma-containing gas P1 from the ejection port 105, and sprays the plasma-containing gas P1 onto the processing target S1. In FIG. 17, the width W10 of the ejection port 105 in the X-direction is illustrated typically.

[0007] 17, in the processing object S1, the plasma-containing gas P1 is sprayed toward a region facing the injection port 105. The processing object S1 is transported in the X direction, so that the plasma processing is performed over the entire surface of the processing object S1. Note that the length of the injection port 105 in the Y direction is set longer than the length of the processing object S1 extending in the Y direction. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2014-220056 Summary of the Invention [Problem to be solved by the invention]

[0009] As represented by the plasma processing apparatus 100, in order to efficiently generate a discharge between electrodes by applying a high frequency voltage and generate a plasma-containing gas P1 in the gas flow passage 104, the gas flow passage 104 is made a narrow path. For example, in Patent Document 1, the distance between the dielectric 103 and the facing surface forming portion 102a is set to 1 mm.

[0010] From the viewpoint of efficiently injecting the plasma-containing gas P1 generated in the gas passage 104, the width W10 of the injection port 105 is set to be approximately the same as the width of the gas passage 104. For example, Patent Document 1 discloses that the width W10 is 1 to 3 mm. In this manner, the width W10 of the injection port 105 is designed according to the width of the gas passage 104 where the discharge is generated, and therefore has a certain limit.

[0011] Incidentally, as shown in FIG. 17, when the plasma-containing gas P1 is sprayed onto the processing object S1 while the processing object S1 is being transported, it is preferable to increase the transport speed of the processing object S1 in order to shorten the time required for the plasma treatment of the processing object S1 and to efficiently perform the plasma treatment of the processing object S1. However, as described above, the plasma-containing gas P1 is mainly sprayed onto the area facing the injection port 105. For this reason, if the transport speed of the processing object S1 is increased, the processing object S1 is transported without being sufficiently plasma-treated, and the plasma treatment of the processing object S1 becomes insufficient. In other words, since the width W10 of the injection port 105 is narrow in the transport direction, it is necessary to slow down the transport speed of the processing object S1, and there is room for improvement in terms of efficiently plasma-treating the processing object S1.

[0012] The length of the injection port 105 in the longitudinal direction, i.e., in the Y direction, can be made larger than the width W10 relatively easily, for example, by increasing the area in which the electrodes (101, 102) are formed. For this reason, it would seem that if the plasma processing apparatus 100 is installed so that the longitudinal direction of the injection port 105 coincides with the transport direction, i.e., the X direction, the area to which the plasma-containing gas P1 is sprayed can be made longer in the X direction. However, in this case, the width of the area in the Y direction becomes narrow, so that the plasma processing of the processing target object S1 cannot be performed efficiently, and thus arranging the plasma processing apparatus 100 in this manner is not an effective measure.

[0013] In view of the above, an object of the present invention is to provide a plasma processing apparatus capable of efficiently performing plasma processing on an object to be processed. [Means for solving the problem]

[0014] The plasma processing apparatus according to the present invention comprises: A plasma processing apparatus that sprays a plasma-containing gas onto an object to be processed, a nozzle having an injection port for injecting the plasma-containing gas; a buffer chamber having a bottom surface facing the object to be processed and a side surface surrounding the plasma-containing gas jetted from the jet port and connecting the bottom surface and the nozzle; the bottom surface has a bottom plate portion and an opening portion through which the plasma-containing gas injected from the injection port is ejected, When viewed in a direction perpendicular to the bottom surface, the opening is larger than the jet port in a width direction of the jet port.

[0015] As described with reference to FIG. 17, the minimum width of the injection port is limited to a certain extent, and the width direction is typically aligned with the transport direction of the object to be treated. Therefore, the inventors of the present invention have considered plasma processing of the object to be treated over a wider range in the transport direction by increasing the distance between the object to be treated and the injection port. In other words, it is considered that by increasing the distance, the plasma-containing gas diffuses before reaching the object to be treated, and the plasma-containing gas is sprayed over a wider range against the object to be treated. However, even if the distance between the object to be treated and the injection port is increased in this way, the efficiency of the plasma processing is significantly reduced, far from expanding the processing area.

[0016] The present inventors have conducted extensive research into the cause of this problem, and have found that by increasing the distance between the object to be treated and the injection port, activated chemical species such as radicals constituting the plasma in the plasma-containing gas (hereinafter, for convenience, referred to as "activated chemical species") react with oxygen contained in the gas in the atmosphere in which the object to be treated is placed (hereinafter, for convenience, referred to as "atmospheric gas"), and are deactivated. In view of this, the present inventors have considered that if it is possible to prevent the activated chemical species contained in the plasma-containing gas from reacting with oxygen in the atmospheric gas before it is supplied to the object to be treated, the plasma-containing gas can be sprayed over a wider area while containing a high concentration of activated chemical species, and have devised the above configuration.

[0017] According to the above configuration, the plasma-containing gas injected from the injection port is surrounded by the buffer chamber. In addition, since the plasma-containing gas is injected from the opening of the buffer chamber, the surrounding atmospheric gas is unlikely to enter the buffer chamber. Therefore, the plasma-containing gas is prevented from coming into contact with oxygen in the atmospheric gas. Therefore, the active chemical species contained in the plasma-containing gas are unlikely to be deactivated, and the plasma-containing gas is efficiently guided to the opening of the buffer chamber with a higher concentration of active chemical species.

[0018] That is, the plasma-containing gas containing a high concentration of active chemical species is ejected from the opening of the buffer chamber. The width of the opening of the buffer chamber in the width direction of the nozzle when viewed in a direction perpendicular to the bottom surface facing the processing object is made larger than the minimum width of the nozzle, so that the processing area of ​​the processing object becomes wider in the width direction than when the plasma-containing gas is directly sprayed from the nozzle. This enables efficient plasma processing of the processing object.

[0019] In addition, the plasma processing apparatus having the above configuration can efficiently perform plasma processing on the object to be processed, regardless of whether the object to be processed is in a transported state or in a stationary state. When performing plasma processing while transporting the object to be processed, the plasma-containing gas may be sprayed onto the object to be processed that is in a transported state in the width direction of the injection port. By arranging the plasma processing apparatus so that the width direction of the injection port coincides with the transport direction of the object to be processed, the processing area of ​​the object to be processed becomes wider in the transport direction, and as a result, it is possible to increase the transport speed of the object to be processed, for example.

[0020] Furthermore, even when plasma processing is performed on a stationary object to be processed, the processing area on the object to be processed is widened in the width direction of the injection port, so that the object to be processed can be processed efficiently.

[0021] In the above plasma processing apparatus, At least a portion of the injection port may face the bottom plate portion of the bottom surface in a direction perpendicular to the bottom surface.

[0022] According to the above configuration, the plasma-containing gas injected from the injection port is likely to remain in the buffer chamber after being sprayed onto the bottom plate portion, which makes it easier for the buffer chamber to be filled with the plasma-containing gas and makes it difficult for the surrounding atmospheric gas to enter through the opening.

[0023] In the above plasma processing apparatus, When viewed in a direction perpendicular to the bottom surface, the opening may be smaller than the jet orifice in a longitudinal direction of the jet orifice.

[0024] The above configuration is preferable because a part of the injection port and the bottom plate portion face each other in a direction perpendicular to the bottom surface, which makes it easier for the plasma-containing gas P1 to remain in the buffer chamber.

[0025] In the above plasma processing apparatus, The distance between the bottom surface and the injection port in the direction perpendicular to the bottom surface may be 20 mm or less. Details will be explained in the [Verification] section below.

[0026] In the above plasma processing apparatus, The area of ​​the opening may be larger than the area of ​​the jet orifice.

[0027] In the above plasma processing apparatus, The jet orifice may be in the form of a slit extending in the longitudinal direction. Effect of the Invention

[0028] According to the present invention, there is provided a plasma processing apparatus capable of efficiently performing plasma processing on an object to be processed. [Brief description of the drawings]

[0029] [Figure 1] 1 is a perspective view showing a configuration example of a plasma processing apparatus; [Diagram 2] 2 is a cross-sectional view of the plasma processing apparatus taken along the XZ plane. [Diagram 3] FIG. 13 is a plan view of the nozzle as viewed in the Z direction, with the buffer chamber not shown. [Figure 4] This is a drawing of FIG. 1 as seen in the X direction. [Diagram 5] This is a drawing of the bottom surface as seen in the Z direction. [Figure 6] FIG. 1 is a schematic diagram of the experimental system used in Verification 1. [Figure 7] 1 is a graph showing the results of verification 1. [Figure 8] 8 is a graph showing the results of verification 2, following FIG. 7. [Figure 9] 6 is a diagram showing the structure of a buffer chamber used in the verification, following FIG. 5 . [Figure 10] 8 is a graph showing the results of Verification 3, following FIG. 7. [Figure 11] 13 is a graph showing the results of Verification 3. [Figure 12]10 is a view showing a bottom surface of a buffer chamber according to another configuration example, following FIG. 9. [Figure 13] 13 is a diagram showing a bottom view of a buffer chamber according to another configuration example. [Figure 14] 4 is a diagram showing another example of the nozzle configuration similar to FIG. 3. [Figure 15] FIG. 11 is a cross-sectional view of a plasma processing apparatus according to another embodiment. [Figure 16] 16 is a plan view of the nozzle in FIG. 15 as viewed in the Z direction. [Figure 17] FIG. 1 is a cross-sectional view that illustrates a schematic structure of a plasma processing apparatus described in Patent Document 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] An embodiment of a plasma processing apparatus according to the present invention will be described with reference to the drawings. Note that the drawings are schematic except for the graphs, and the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios. Furthermore, the dimensional ratios may not match between the drawings.

[0031] [First embodiment] Fig. 1 is a perspective view showing a configuration example of a plasma processing apparatus. As shown in Fig. 1, the plasma processing apparatus 1 includes a nozzle 2 and a buffer chamber 3. Fig. 1 shows an example in which a plasma-containing gas (not shown in Fig. 1) is sprayed onto the processing object S1 being transported on a stage 4 of a transport unit such as a conveyor, thereby performing plasma processing on the processing object S1. Also, in Fig. 1, the processing object S1 is plate-shaped.

[0032] In each of the following figures, the direction in which the processing object S1 faces the bottom surface 32 of the buffer chamber 3 described later is defined as the Z direction, and the plane perpendicular to the Z direction is defined as the XYZ coordinate system, which is appropriately referenced for explanation. In this embodiment, the X direction is the transport direction of the processing object S1, and corresponds to the width direction of the injection port 25 of the nozzle 2 described later. The Y direction corresponds to the length direction of the injection port 25. In the following explanation, when referring to dimensions, etc., the X direction will be described as the "width direction" and the Y direction as the "length direction". Typically, the Z direction is the vertical direction.

[0033] In the following description, when a positive or negative direction is to be distinguished from a positive or negative direction, the direction is described with a positive or negative sign, such as "+X direction" and "-X direction". When a direction is to be described without distinguishing between positive and negative directions, the direction is simply described as "X direction". In other words, in this specification, when the direction is simply described as "X direction", both the "+X direction" and the "-X direction" are included. The same applies to the Y direction and the Z direction.

[0034] [nozzle] Fig. 2 is a cross-sectional view of the plasma processing apparatus 1 cut along the XZ plane. Fig. 2 shows a schematic diagram of the plasma processing apparatus 1 and the ambient gas G2 around the processing target S1. Fig. 3 is a plan view of the nozzle 2 as viewed in the +Z direction, without showing the buffer chamber 3. Note that Fig. 3 does not show a housing 20 of the nozzle 2, which will be described later.

[0035] In this embodiment, the atmospheric gas G2 is air, and the processing target S1 is processed in an air atmosphere.

[0036] As shown in FIG. 2, the nozzle 2 includes a housing 20, a pair of electrodes (21, 22), a dielectric 23 in contact with the electrode 21 and facing the electrode 22 in the X direction, a gas flow passage 24 formed between the dielectric 23 and the electrode 22, and an injection port 25 for injecting gas that has flowed through the gas flow passage 24.

[0037] A high-frequency voltage is applied between the electrodes 21 and 22 by a power source 26 via the dielectric 23 and the gas flow passage 24. For example, the electrode 21 is the high-voltage electrode and the electrode 22 is the low-voltage electrode, but the two may be reversed. When the high-frequency voltage is applied, a discharge occurs in the region where the electrodes 21 and 22 face each other.

[0038] In this embodiment, the distance D1 between the electrode 22 and the dielectric 23 in the X direction is 0.3 mm. The length D2 in the Y direction of the region where the pair of electrodes (21, 22) face each other is 240 mm.

[0039] A source gas G1 is introduced into the gas flow passage 24 from an arbitrary gas introduction mechanism 27. As shown in Fig. 3, the gas flow passage 24 has a slit shape extending in the Y direction according to the region where the electrode 21 and the electrode 22 face each other. The width of the gas flow passage 24 in the X direction corresponds to the separation distance D1 between the electrode 22 and the dielectric 23 in the X direction, and the length D3 in the Y direction is 260 mm. The source gas G1 is, for example, nitrogen gas with a purity of 99% or more.

[0040] The jet port 25 jets the plasma-containing gas P1 generated by discharge generated between the pair of electrodes (21, 22). In this embodiment, the jet port 25 has a slit shape extending in the Y direction similar to the gas flow passage 24. The jet port 25 faces the processing target S1 in the Z direction and jets the plasma-containing gas P1 toward the processing target S1. The width W1 of the jet port 25 in the X direction and the length L1 of the jet port 25 in the Y direction are similar to the width D1 and length D3 of the gas flow passage 24, respectively.

[0041] [Buffer chamber] Although details will be described later in the [Verification] section, the inventors considered that it is important to reduce contact between the plasma-containing gas P1 and the atmospheric gas G2 in order to efficiently plasma-treat the processing target S1. More specifically, the buffer chamber 3 is configured for the purpose of reducing contact between the activated chemical species constituting the plasma in the plasma-containing gas P1 and the oxygen in the atmospheric gas G2.

[0042] Fig. 4 is a view of Fig. 1 as viewed in the X direction. For convenience of illustration, the electrode 21 is omitted in Fig. 4, and the internal structure of the nozzle 2 and the buffer chamber 3 is shown typically. Fig. 4 also shows a schematic view of the flow of the plasma-containing gas P1 in the buffer chamber 3.

[0043] As shown in Figs. 2 and 4, the buffer chamber 3 has side surfaces (31x, 31y) and a bottom surface 32 facing the processing target S1. Fig. 2 illustrates a separation distance A1 in the Z direction between the bottom surface 32 and the processing target S1. The side surfaces (31x, 31y) are shaped to extend in the Z direction from the housing 20 of the nozzle 2, and connect the bottom surface 32 to the nozzle 2. The bottom surface 32 has a bottom plate portion 33 and an opening 34. For convenience of illustration, the bottom plate portion 33 and the opening 34 are not shown in Fig. 2.

[0044] The side surfaces (31x, 31y) surround the plasma-containing gas P1 injected from the injection port 25. This suppresses contact between the plasma-containing gas P1 in the buffer chamber 3 and the atmospheric gas G2 in the direction parallel to the XY plane. Similarly, the bottom plate portion 33 suppresses contact between the plasma-containing gas P1 in the buffer chamber 3 and the atmospheric gas G2 in the Z direction. In addition, as shown in FIG. 4, the plasma-containing gas (hereinafter, for convenience, referred to as the "plasma-containing gas P2") that has flowed through the buffer chamber 3 is ejected from the opening 34, so that the atmospheric gas G2 is unlikely to enter the buffer chamber 3. That is, the buffer chamber 3 suppresses contact between the plasma-containing gas P1 and the atmospheric gas G2 until the plasma-containing gas P1 reaches the opening 34 after being injected from the injection port 25. This makes it easier for the plasma-containing gas P1 to be introduced to the opening 34 in a state in which it contains a high concentration of active chemical species.

[0045] 4, the plasma-containing gas P1 injected from the injection port 25 is blown onto the bottom plate portion 33, and therefore tends to remain in the buffer chamber 3. This makes it easier for the buffer chamber 3 to be filled with the plasma-containing gas P1, and makes it difficult for the surrounding atmospheric gas G2 to flow in from the opening 34. In view of this, it is preferable that a part of the injection port 25 faces the bottom plate portion 33, as shown in FIG.

[0046] FIG. 5 is a drawing of the bottom surface 32 as viewed in the +Z direction. In FIG. 5, the position of the hidden portion of the injection port 25 is indicated by a broken line. As shown in FIG. 5, the width W2 of the opening 34 in the X direction is made larger than the minimum width of the injection port 25, i.e., the width W1 in the X direction. After the plasma-containing gas P1 containing a high concentration of active chemical species is introduced into the opening 34, the plasma-containing gas P2 is ejected from the opening 34 having a width W2 larger than the width W1 of the injection port 25, so that the plasma processing area of ​​the processing target S1 in the X direction can be widened. The width W1 of the injection port 25 is typically the width in the direction in which the electrode 21 and the electrode 22 face each other.

[0047] As an example, in this embodiment, the width W2 is 50 mm, and the length L2 of the opening 34 in the Y direction is 40 mm. As described above, the length L1 of the jet port 25 in the Y direction is 260 mm (see also FIG. 3). As shown in FIG. 4, the length L2 of the opening 34 is preferably shorter than the length L1 of the jet port 25. This causes a part of the jet port 25 to face the bottom plate portion 33, making it easier for the plasma-containing gas P1 to stagnate in the buffer chamber 3.

[0048] In order to spray the plasma-containing gas P2 over a wider range of the processing object S1, the area of ​​the opening 34 is preferably larger than the area of ​​the injection port 25. In this case, it is also preferable that the bottom plate portion 33 and a part of the injection port 25 face each other, as in the above.

[0049] It is preferable that the length D3 of the gas flow passage 24 in the Y direction and the length L1 of the injection port 25 are greater than the length D2 of the region where the electrodes 21 and 22 face each other (see FIG. 3). In this case, the plasma-containing gas P1 includes a gas that has flowed through the gas flow passage 24 without application of a discharge between the electrodes (21, 22). From the viewpoint of quickly replacing the inside of the buffer chamber 3 with the plasma-containing gas P1 including the gas, the length D3 of the gas flow passage 24 and the length L1 of the injection port 25 may be greater than the length D2 of the region where the electrodes 21 and 22 face each other.

[0050] [Verification 1] The following describes the results of verifying the influence of increasing the distance between the injection port 25 and the processing target S1 when the plasma processing apparatus 1 does not have the buffer chamber 3.

[0051] (Sample 1A) 6 is a schematic diagram of an experimental system used in verification 1. The plasma processing apparatus 40 used in this verification has the same configuration as the plasma processing apparatus 1 described with reference to FIGS. 1 to 3, except that it does not have a buffer chamber 3. In this verification, the plasma processing apparatus 40, the processing object S1, and a stage 41 supporting the processing object S1 were placed in a box 42. The box 42 has an air inlet and an exhaust port (not shown) that can replace the atmospheric gas G2 in the box 42 with any gas.

[0052] The raw material gas G1 was nitrogen gas with a purity of 99% or more, and the flow rate was 80 NL / min. Although not shown in FIG. 6, the raw material gas G1 was introduced from the outside of the box 42 to the gas introduction mechanism 27 via a piping (not shown). A high-frequency voltage of 8 kVp-p at a frequency of 70 kHz was applied to the electrodes (21, 22). The input power was 240 W.

[0053] The processing object S1 was a polymethyl methacrylate (PMMA) substrate with a width in the X direction of 100 mm, a length in the Y direction of 25 mm, and a thickness in the Z direction of 3 mm. In this verification, the plasma-containing gas P1 was sprayed onto the processing object S1 in a stationary state. The separation distance A2 between the processing object S1 and the injection port 25 in the Z direction was set to 2 mm.

[0054] In the case of sample 1A, the processing object S1 was processed in the air atmosphere. That is, in the case of sample 1A, the plasma processing was performed without replacing the atmospheric gas G2 in the box 42. The spraying time of the plasma-containing gas was set to 10 seconds.

[0055] After performing plasma processing on the processing object S1 under the above conditions, the water contact angle on the surface of the processing object S1 was measured while changing the position in the X direction. In this way, the range where the plasma processing was performed was evaluated. The water contact angle was measured by a method based on JIS R3257 "Test method for wettability of substrate glass surface."

[0056] (Sample 1B) It was carried out under the same conditions as sample 1A, except that the separation distance A2 was 20 mm.

[0057] (Sample 1C) This was carried out under the same conditions as Sample 1A, except that the inside of box 42 was replaced with 99% pure nitrogen gas.

[0058] (Sample 1D) The experiment was carried out under the same conditions as Sample 1A, except that the separation distance A2 was set to 20 mm and the inside of the box 42 was replaced with nitrogen gas of 99% purity.

[0059] [Results and Considerations of Test 1] Fig. 7 is a graph showing the results of verification 1. In Fig. 7, the horizontal axis shows the position in the X direction with reference to the center of the injection port 25, and the vertical axis shows the water contact angle of the treatment target S1 at each position.

[0060] First, looking at the results of sample 1A, it can be seen that the water contact angle of the surface of the treatment object S1 is reduced mainly in the area facing the injection port 25. The water contact angle of the treatment object S1 before the plasma treatment is about 65°. In other words, the spraying of the plasma-containing gas P1 modifies the surface of the treatment object S1, and polar molecules such as hydroxyl groups (-OH groups), carbonyl groups (C=O groups), carboxyl groups (-COOH groups), and amino groups (-NH2 groups) are increased on the surface, thereby making the treatment object S1 hydrophilic. In sample 1A, the range in which the water contact angle is reduced to, for example, 50° or less was approximately ±5 mm.

[0061] On the other hand, looking at the results of sample 1B, even within the range of ±5 mm, the water contact angle of the treatment object S1 is 60° or more, and it can be seen that the treatment object S1 is hardly hydrophilized. This is thought to be because the plasma contained in the plasma-containing gas P1 is inactivated before being supplied to the treatment object S1 due to the large separation distance A2 between the injection port 25 and the treatment object S1.

[0062] More specifically, the activated chemical species contained in the plasma may be nitrogen radicals derived from nitrogen gas, oxygen radicals derived from oxygen and water as impurities contained in the nitrogen gas, and hydrogen radicals. Each radical reacts with oxygen to generate compounds such as ozone and NOx. For this reason, it is considered that the plasma-containing gas P1 comes into contact with the atmospheric gas G2, which is the air, before being supplied to the object S1 to be treated, and as a result, the reaction between the radicals and oxygen progresses, and the activated chemical species are deactivated. It is considered that the generated compounds such as ozone contribute to the modification of the object S1 to be treated, but compared to radicals, the reaction rate of the compounds with the molecules constituting the surface of the object S1 to be treated is slow. Due to the above circumstances, it is considered that the activated chemical species are deactivated when the plasma-containing gas P1 comes into contact with the atmospheric gas G2, resulting in insufficient treatment of the object S1 to be treated.

[0063] This point is consistent with the results of Sample 1C and Sample 1D. Looking at the results of Sample 1C, even though the separation distance A2 in Sample 1C is the same as that in Sample 1B, the contact angle in Sample 1C is generally lower than that in Sample 1B. This is considered to be because the atmospheric gas G2 in the box 42 is replaced with nitrogen gas, and the oxygen in the box 42 is reduced, making it difficult for the active chemical species in the plasma-containing gas P1 to be deactivated. Furthermore, looking at the results of Sample 1D, the water contact angle is reduced to 50° or less in the range of ±40 mm, and it can be seen that the plasma treatment was performed over a wider range than in Sample 1A. It can also be seen from the results of Sample 1A and Sample 1D that the replacement of the inside of the box 42 with nitrogen gas can suppress the active chemical species from reacting with oxygen and being deactivated.

[0064] In view of the above, it is preferable to suppress contact between the plasma-containing gas P1 and the oxygen contained in the atmospheric gas G2 before the plasma-containing gas P1 is supplied to the processing object S1. However, when actually performing plasma processing on the processing object S1, it is not realistic to replace the atmosphere around the plasma processing device 40 and the processing object S1 with nitrogen gas.

[0065] [Verification 2] In consideration of the above-mentioned verification 1, the effect of providing a buffer chamber surrounding the plasma-containing gas P1 injected from the injection port 25 was verified, and will be described below.

[0066] (Sample 2A) This verification was carried out in the plasma processing apparatus 1 having the configuration described with reference to Figures 1 to 5. In this verification, similarly to verification 1, the plasma-containing gas P1 was sprayed onto the processing target S1 in a stationary state.

[0067] More specifically, the distance between the injection port 25 and the treatment object S1 was set to 22 mm, and the buffer chamber 3 was attached. The height of the buffer chamber 3 in the Z direction was 20 mm. That is, in this verification, the distance A1 between the treatment object S1 and the buffer chamber 3 was set to 2 mm. Also, in this verification, the treatment object S1 was treated in an atmospheric environment.

[0068] The structure of the buffer chamber 3 is the same as that described above with reference to Figures 4 and 5. The other conditions are the same as those of sample 1A in the above-mentioned verification 1.

[0069] (Sample 2B) As a comparative example, the buffer chamber 3 was removed, and the plasma processing was performed with the separation distance between the injection port 25 and the processing target S1 set to 2 mm. The other conditions were the same as those of the sample 2A.

[0070] (Sample 2C) The experiment was carried out under the same conditions as sample 2B, except that the distance between the injection port 25 and the object to be treated S1 was set to 20 mm.

[0071] (Results and Considerations of Test 2) FIG. 8 is a graph showing the results of verification 2, following FIG. 7. The results of Sample 2B and Sample 2C are similar to those of Sample 1A and Sample 1B of verification 1. On the other hand, the results of Sample 2A show that the range in which the water contact angle was reduced to about 50° or less was within ±20 mm, and the plasma treatment was performed over a wider range than Sample 2B. That is, it can be seen that in Sample 2A, the plasma-containing gas P1 was guided to the opening 34 of the buffer chamber 3 in a state in which it contained a higher concentration of active chemical species. This is considered to be because the plasma-containing gas P1 injected from the injection port 25 was surrounded by the buffer chamber 3, suppressing contact between the plasma-containing gas P1 and the atmospheric gas G2, and making it difficult for the active chemical species to be deactivated.

[0072] Moreover, the width W2 in the X direction of the opening 34 of the buffer chamber 3 is 50 mm, which is larger than the width W1 of the injection port 25 (see FIG. 5). This is thought to increase the area on the surface of the processing target S1 onto which the plasma-containing gas P2 is sprayed, thereby expanding the range of the plasma processing.

[0073] As described above, by providing the plasma processing apparatus 1 with the buffer chamber 3, the range of plasma processing of the processing target object S1 can be expanded.

[0074] The same is true for the processing object S1 in the transport state. That is, it can be understood that the plasma processing apparatus 1 according to the first embodiment can efficiently plasma-process the processing object S1. More specifically, by widening the range of the plasma processing, for example, the transport speed of the processing object S1 can be increased.

[0075] [Verification 3] The plasma processing of the processing object S1 was carried out using buffer chambers with different structures, which will be described below.

[0076] (Sample 3A) This was carried out under the same conditions as sample 2A in Verification 2 above, except that the height in the Z direction of the side surfaces (31x, 31y) of the buffer chamber 3 was changed to 5 mm.

[0077] (Sample 3B) The test was carried out under the same conditions as for sample 3A, except that the length L2 in the Y direction of the opening 34 of the buffer chamber 3 was set to 100 mm.

[0078] (Sample 3C) The test was carried out under the same conditions as for sample 3A, except that the length L2 in the Y direction of the opening 34 of the buffer chamber 3 was set to 150 mm.

[0079] (Sample 3D) As a comparative example, a state in which the plasma processing apparatus does not have a buffer chamber was verified. Specifically, the same conditions as those of Sample 2B in Verification 2 were used.

[0080] (Sample 3E) FIG. 9 is a diagram showing the structure of the buffer chamber 3 used in this verification, following FIG. 5. In the plasma processing of sample 3E, as shown in FIG. 9, a buffer chamber 3 having a plurality of openings (34a, 34b) on the bottom surface 32 was used. More specifically, the widths (W21, W22) of the openings 34a and 34b in the X direction were each set to 5 mm. That is, the bottom surface 32 of the buffer chamber 3 can be said to have an opening 34 with a width of 10 mm in the X direction. In addition, the length L2 of the openings (34a, 34b) in the Y direction was each set to 100 mm. Except for the fact that the structure of the bottom surface of the buffer chamber 3 was changed, the processing was performed under the same conditions as sample 2A of the above verification 2.

[0081] (Results and Considerations of Test 3) Fig. 10 is a graph showing the results of Samples 3A to 3D following Fig. 7. Also, Fig. 11 is a graph showing the results of Sample 3E.

[0082] As shown in Fig. 10, Sample 3A, Sample 3B, and Sample 3C all have a wider range in which the contact angle of the processing target S1 decreases than Sample 3D, which was processed without a buffer chamber. In Samples 3A to 3C, the height in the Z direction of the side surface (31x, 31y) of the buffer chamber 3 is set to 5 mm compared to Sample 2A in Verification 2. In other words, referring to the results of Sample 2A and Samples 3A to 3C, it can be understood that the height in the Z direction of the side surface (31x, 31y) of the buffer chamber 3 is arbitrary. In view of the above results, it is preferable that the height is set to 20 mm or less.

[0083] In addition, in FIG. 10, when comparing the results of the samples 3A to 3C, it can be seen that the range of the plasma treatment becomes wider in the order of the samples 3A, 3B, and 3C. That is, in the samples 3A to 3C, as the length L2 (see FIG. 5) of the opening 34 in the Y direction becomes narrower, the range of the plasma treatment becomes wider. The inventors speculate that the reason for this is that the atmosphere in the buffer chamber 3 is more easily replaced with the plasma-containing gas P1 in the sample 3A than in the samples 3B and 3C. That is, in the sample 3A, the length L2 of the opening 34 is shorter than in the samples 3B and 3C, so that the area of ​​the bottom plate portion 33 is larger. The area of ​​the bottom plate portion 33 facing the injection port 25 is larger, so that the plasma-containing gas P1 is more likely to remain in the buffer chamber 3. As a result, it is considered that the atmosphere in the buffer chamber 3 is more easily replaced with the plasma-containing gas P1, and the contact between the plasma-containing gas P1 and the oxygen contained in the atmospheric gas G2 is suppressed. In view of this, it is preferable that at least a portion of the injection port 25 faces the bottom plate portion 33 of the buffer chamber 3 .

[0084] 11, even when a plurality of openings (34a, 34b) are provided in the bottom surface 32 (see FIG. 9), the range of plasma processing is expanded. This point is also clear from a comparison of the results of sample 3E in FIG. 11 with the results of sample 1A in FIG. 7. That is, in the bottom surface 32 of the buffer chamber 3, the opening 34 may be composed of a plurality of openings.

[0085] [Another embodiment] <1> In the above first embodiment, a rectangular opening 34 is provided at one location on the bottom surface 32 of the buffer chamber 3. However, as described in Experiment 3 and with reference to FIG. 9, the opening 34 may be configured as openings provided at multiple locations on the bottom surface 32.

[0086] As shown in FIG. 9, when multiple openings (34a, 34b) are formed in the X direction, the width of the opening 34 in the X direction may be the sum of the widths of the respective openings (34a, 34b) in the X direction.

[0087] 12 is a diagram showing the bottom surface 32 of the buffer chamber 3 according to another configuration example, following FIG. 9. As shown in FIG. 12, the opening 34 may be composed of an opening 34a and an opening 34b provided on the +Y side and the -Y side of the bottom surface 32. In this case, the length L2 of the opening 34 in the Y direction can be defined as the sum of the lengths of the opening 34a and the opening 34b. Although not shown in the figure, the opening 34 may be provided only on the +Y side of the bottom surface 32, for example.

[0088] The shape of the opening 34 is arbitrary. For example, the opening 34 may be circular.

[0089] 13 is a diagram showing the bottom surface 32 of the buffer chamber 3 according to another configuration example. As shown in FIG. 13, the opening 34 may be configured in a mesh shape with a plurality of circular holes 34c. When the opening 34 is configured in a mesh shape with a plurality of holes 34c, in FIG. 13, the width W2 of the opening 34 in the X direction can be defined as the width in the X direction of the opening region 35 formed by virtually connecting the outer edges of the holes 34c located on the outer side when viewed in the Z direction. Furthermore, the length L2 of the opening 34 in the Y direction can be defined as the length in the Y direction of the opening region 35.

[0090] As described above, the shape of the opening 34 can be designed arbitrarily depending on the processing target S1.

[0091] <2> Fig. 14 is a drawing showing another example of the configuration of the nozzle 2 following Fig. 3. In the above, the ejection port 25 has been described as having a slit shape. However, the present invention is not limited to the shape of the ejection port 25 of the nozzle 2. For example, as shown in Fig. 14, the ejection port 25 may be configured with a plurality of holes 25a provided in the Y direction. Fig. 14 shows an example in which the gas flow passage 24 is partitioned by a plurality of partition members 28 to form a plurality of holes 25a.

[0092] Since the plasma-containing gas P1 is injected from each hole 25a, the holes 25a form an injection region 25b, which is an area formed by virtually connecting the outer edges of the holes 25a when viewed in the Z direction, in Fig. 14. In this case, the width W1 of the injection port 25 in the X direction can be defined as the width of the injection region 25b in the X direction. Also, the length L1 of the injection port 25 in the Y direction can be defined as the length of the injection region 25b in the Y direction.

[0093] Although not shown, the configuration of the nozzle 2 shown in Fig. 14 is the same as that described in Fig. 2, except that a partition member 28 is disposed on the -Z side of the gas flow passage 24. In Fig. 14, the diameters of the multiple holes 25a constituting the injection port 25 may be different from each other. In addition, it is optional whether or not the holes 25a are disposed in a straight line. Furthermore, the holes 25a may have an elliptical shape.

[0094] <3> Fig. 15 is a cross-sectional view of a plasma processing apparatus according to another embodiment. Fig. 16 is a plan view of the nozzle 2 according to Fig. 15 when viewed in the Z direction. In the above description, the flat electrodes (21, 22) are described as facing each other. However, as shown in Fig. 15, the electrodes 21 and 22 may be facing each other on the +X side and the -X side of the dielectric 23, respectively. In this case, the injection port 25 has a frame shape as shown in Fig. 16. In this case, the width of the injection port 25 in the X direction can be defined as the sum of the width W11 where the electrode 22 and the dielectric 23 face each other on the +X side and the width W12 where the electrode 22 and the dielectric 23 face each other on the -X side.

[0095] <4> In the above, the source gas G1 is described as being nitrogen gas, but the source gas G1 may be any gas as long as it can generate active chemical species such as radicals by discharging between electrodes. For example, the source gas G1 may be a gas containing one or more selected from the group consisting of nitrogen, helium, and argon. Furthermore, in consideration of the generation of radicals, the source gas G1 may contain trace amounts of oxygen, hydrogen, water, and volatile organic compounds.

[0096] <5> In the above, the processing object S1 has been described as being plate-shaped, but the processing object S1 may be any shape as long as the plasma-containing gas P1 is sprayed onto the processing object S1. For example, the processing object S1 may be in the form of a film or powder.

[0097] <6> In the above, the description has been focused on making the surface of the processing object S1 hydrophilic by plasma processing. However, as mentioned at the beginning, the plasma processing apparatus 1 may also be used to remove organic matter, etc., from the surface of the processing object S1.

[0098] <7> In the above embodiment, the processing object S1 is described as being transported in the X direction by, for example, a transport unit having a stage 4. However, the processing object S1 may be processed while moving the plasma processing apparatus 1 in the X direction relative to the processing object S1.

[0099] Furthermore, the processing object S1 may be processed by spraying the plasma-containing gas P1 against the processing object S1 in a stationary state. Even in this case, it is clear from the results of the above-mentioned verification 2 that the processing object S1 can be efficiently processed.

[0100] <8> As described above, since the plasma processing apparatus 1 has the buffer chamber 3, the buffer chamber 3 is filled with the plasma-containing gas P1, and contact between the plasma-containing gas P1 and the atmospheric gas G2 is suppressed before the plasma-containing gas P1 is sprayed to the outside. In view of this, in order to replace the inside of the buffer chamber 3 with a gas different from the atmospheric gas G2 at an earlier stage, an inlet may be provided at a part of the side surface of the buffer chamber 3, and a purge gas made of the same kind of gas as the source gas G1 or an inert gas such as nitrogen may be introduced into the buffer chamber 3. [Explanation of symbols]

[0101] 1: Plasma processing equipment 2: Nozzle 3: Buffer chamber 4: Stage 20: Case 21,22 : Electrode 23: Dielectric 24: Gas passage 25 : Jet nozzle 25a: Hole 25b: Injection area 26: Power supply 27: Gas introduction mechanism 28: Partition material 31x,31y: Side 32: Bottom 33: Bottom plate part 34: Opening 34a,34b: Opening 34c: Hole 35: Opening area 40: Plasma processing equipment 41: Stage 42: Box 100: Plasma processing equipment 101 : Electrode 102 : Ground electrode 102a: Opposing surface forming part 103: Dielectric 104: Gas passage 105: Injection port 106: Cover 107: Fixing screw G1: Source gas G2: Atmospheric gas P1, P2: Plasma-containing gas S1: Processing object

Claims

1. A plasma processing apparatus that sprays a plasma-containing gas onto an object to be processed, a nozzle having an injection port for injecting the plasma-containing gas; a buffer chamber having a bottom surface facing the object to be processed and a side surface surrounding the plasma-containing gas jetted from the jet port and connecting the bottom surface and the nozzle; the bottom surface has a bottom plate portion and an opening portion through which the plasma-containing gas injected from the injection port is ejected, The plasma processing apparatus, wherein, when viewed in a direction perpendicular to the bottom surface, the opening is larger than the jet nozzle in a width direction of the jet nozzle.

2. 2. The plasma processing apparatus according to claim 1, wherein at least a portion of the injection port faces the bottom plate portion of the bottom surface in a direction perpendicular to the bottom surface.

3. 3. The plasma processing apparatus according to claim 2, wherein the opening is smaller than the jet nozzle in a length direction of the jet nozzle when viewed in a direction perpendicular to the bottom surface.

4. 4. The plasma processing apparatus according to claim 1, wherein the plasma-containing gas is sprayed against the object to be processed, which is being transported in a width direction of the injection port.

5. 4. The plasma processing apparatus according to claim 1, wherein a distance between said bottom surface and said injection port in a direction perpendicular to said bottom surface is 20 mm or less.

6. 3. The plasma processing apparatus according to claim 2, wherein an area of ​​the opening is larger than an area of ​​the injection port.

7. 4. The plasma processing apparatus according to claim 1, wherein the injection port has a slit shape extending in a longitudinal direction.

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