DEVICE FOR THE TREATMENT OF A WEB SUBSTRATE IN A PLASMA ENHANCED PROCESS

Abstract

A device for treating a web substrate in a plasma enhanced process. The device includes a treatment station with a vacuum process chamber. A plasma treatment unit is allocated to the treatment station which is designed to form a plasma zone within the process chamber for treating a surface of the web substrate. The device further includes a transporting system for continuously transporting the web substrate through the treatment station with an unwind roller and a rewind roller, wherein the transporting system defines a transporting path of the web substrate through the process chamber. The plasma treatment unit includes an extensive antenna and a radiofrequency generator for exciting the extensive antenna to a resonant frequencies.

Claims

1. A device for continuously treating a web substrate in a plasma enhanced process, the device comprising: at least one treatment station including a process chamber, wherein at least one plasma treatment unit is allocated to the at least one treatment station which is designed to form a plasma zone within the process chamber for treating a surface of the web substrate a transporting system configured to continuously transport the web substrate through the at least one treatment station, with an unwind roller and a rewind roller, wherein the transporting system defines a transporting path of the web substrate through the process chamber, wherein the at least one plasma treatment unit comprises at least one extensive antenna and at least one radiofrequency generator configured to excite said at least one extensive antenna to at least one of its resonant frequencies, wherein the at least one extensive antenna comprises a plurality of interconnected elementary resonant meshes, each of the resonant meshes comprising at least two conductive legs and at least two capacitors, and wherein the transporting system in the process chamber defines a treatment path section for the web substrate, wherein the treatment path section for the web substrate lies opposite to the extensive antenna.

2. The device according to claim 1, wherein the extensive antenna comprises one of: a plane antenna; or a curved antenna.

3. The device according to claim 1, wherein the plasma treatment unit contains a separation surface which physically separates the extensive antenna from the plasma zone.

4. The device according to claim 3, wherein the plane antenna and the treatment path section are vertically aligned.

5. The device according to claim 3, wherein the transporting system contains a first and second span member which are spaced from each other, wherein between the span members, a free span for the web substrate is defined which contains the treatment path section for the web substrate.

6. The device according to claim 3, wherein the treatment path section of the web substrate runs at a distance from the separation surface so that the plasma zone is formed between the treatment path section of the web substrate and the separation surface.

7. The device according to claim 3, wherein the treatment path section of the web substrate runs close to the separation surface so that the plasma zone is formed on the side of the web substrate which is facing away from the extensive antenna.

8. The device according to claim 3, wherein the treatment path section of the web substrate forms the separation surface so that the plasma zone is formed on the side of the web substrate which is facing away from the extensive antenna.

9. The device according to claim 1, wherein the treatment station contains a feed passage opening configured to feed the web substrate into the process chamber and a discharge passage opening configured to discharge the treated web substrate from the process chamber.

10. The device according to claim 1, wherein the treatment station contains a gas supply system configured to supply a process gas to the plasma zone in the process chamber.

11. The device according to claim 1, wherein the treatment station contains a pumping system configured to remove gaseous components from the process chamber.

12. The device according to claim 1, wherein within a common process chamber at least two plasma treatment units or extensive antennas respectively are arranged, in each case forming a plasma zone for a surface treatment of the web substrate.

13. The device according to claim 1, wherein the at least one treatment stations comprises a first treatment station with at least one plasma treatment unit, and arranged in processing direction subsequent to the first treatment station, a second treatment station with at least one plasma treatment unit, wherein the transporting system is designed such that the web substrate first can be transported through the first treatment station and subsequently through the second treatment station in a continuous manner.

14. The device according to claim 13, wherein in processing direction between the plasma treatment unit of a preceding treatment station and the plasma treatment unit of a subsequent treatment station at least one deflection member is arranged, which deflects the web substrate such, that the transporting direction of the web substrate through the plasma zone of the plasma treatment unit of the subsequent treatment station is opposite or at an angle to the transporting direction of the web substrate through the plasma zone of the plasma treatment unit of the preceding treatment station.

15. The device according to claim 7, wherein a first treatment path section of the web substrate runs close to the separation surface or forms the separation surface and a second treatment path section runs at a distance to the separation surface and the first treatment path section, so that the plasma zone is formed between the first and second treatment path section of the web substrate.

16. The device according to claim 1, wherein the device has a modular layout and contains a base module with an unwind roller and a rewind roller and a treatment module with at least a treatment station.

17. The device according to claim 1, wherein the device contains at least two process sections, wherein to each process section at least one plasma treatment unit for treating the web substrate is allocated, and wherein the process direction in one process section is bottom up and wherein the process direction in the other process section is top down.

18. The device according to claim 1, wherein the transporting system contains a rotatable drum, wherein the treatment path section of the web substrate is curved and runs along a peripheral surface section of the rotatable drum which defines a curved resting surface for the web substrate in the process chamber.

19. The device according to claim 1, wherein the treatment unit is designed to establish a plasma zone on both sides of the antenna, lying opposite to each other.

20. A method for continuously treating a web substrate in a plasma enhanced process with a device according to claim 1, the method comprising: providing a web substrate with a first web end section which is placed on an unwind roller and with a second web end section which is placed on a rewind roller and with an intermediate web section; generating a plasma in the plasma zone of the at least one plasma treatment unit; unwinding the web substrate from the unwind roller and rewinding the treated web substrate by the rewind roller, thereby transporting an intermediate web section of the web substrate along the treatment path section in the at least one treatment station through the plasma zone of the plasma treatment unit and thereby plasma treating a surface of the web substrate.

Description

[0276] Exemplified embodiments of the device according to the invention are described in connection with the following figures. The figures show schematically:

[0277] FIGS. 1a and 1b a first embodiment of elementary mesh for the plane antenna, and the equivalent electric circuit thereof;

[0278] FIG. 1c illustrates a high pass antenna with a series of elementary meshes according to the first embodiment;

[0279] FIGS. 2a and 2b a second embodiment of elementary mesh for the plane antenna, and the equivalent electric circuit thereof;

[0280] FIG. 2c a low pass antenna with a series of elementary meshes according to the second embodiment;

[0281] FIGS. 3a and 3b a third embodiment of elementary mesh for the plane antenna, and the equivalent electric circuit thereof;

[0282] FIG. 3c a hybrid antenna with elementary meshes according to the third embodiment;

[0283] FIG. 4 a first embodiment of a device according to the invention;

[0284] FIG. 5 a second embodiment of a device according to the invention;

[0285] FIG. 6a a third embodiment of a device according to the invention;

[0286] FIG. 6b a cross section of the web substrate treated with the device according to FIG. 6a;

[0287] FIG. 7a a fourth embodiment of a device according to the invention;

[0288] FIG. 7b a cross section of the web substrate treated with the device according to FIG. 7a;

[0289] FIG. 8 an embodiment of a treatment station according to the invention;

[0290] FIG. 9 a further embodiment of a web run in a treatment station according to the invention;

[0291] FIG. 10 a further embodiment of a web run in a treatment station according to the invention;

[0292] FIG. 11 an embodiment of a plasma source assembly according to the invention;

[0293] FIG. 12 an assembly draft of a specific embodiment of a device according to present invention;

[0294] FIG. 13 a first embodiment of a plasma treatment unit with a rotatable drum;

[0295] FIG. 14 a second embodiment of a plasma treatment unit with a rotatable drum;

[0296] FIG. 15 a further embodiment of a treatment station according to the invention;

[0297] FIG. 16 a further embodiment of a treatment station according to the invention.

[0298] According to the invention, a plane antenna with a plurality of elementary resonant meshes is provided as a source for generating large area plasmas.

[0299] FIGS. 1, 2 and 3 show three embodiments for such an elementary mesh M1 and the corresponding equivalent electric circuit E1.

[0300] Each elementary mesh M1 has two parallel longer conductive legs 1 and 2 whose ends are interconnected by transverse shorter connecting elements 3 and 4. The longer connecting legs 1 and 2 act essentially as inductive components. Each elementary mesh has at least two opposing capacitors 5 and 6 (FIGS. 1a, 2a, 3a).

[0301] In the high pass mesh of FIG. 1, the opposing capacitors 5 and 6 constitute said shorter connecting elements 3 and 4.

[0302] In the low pass mesh of FIG. 2, the opposing capacitors 5 and 6 are each connected in series between two lengths 1a, 1b or 2a, 2b of a respective conductive leg 1 or 2.

[0303] In the pass band mesh of FIG. 3, two first opposing capacitors 5 and 6 constitute said shorter connecting elements 3 and 4, and two second capacitors 5a and 6a are each connected in series between two lengths 1a, 1b or 2a, 2b of a respective conductive leg 1 or 2.

[0304] Each elementary mesh forms a resonant L-C loop as shown on the corresponding equivalent electric circuits E1 (FIGS. 1b, 2b, 3b).

[0305] Several elementary meshes are interconnected in order to form a plane antenna of the desired dimensions.

[0306] For instance, FIG. 1c shows a high pass antenna 9.1 (generally named: 9) made of a series of elementary high pass meshes M1, M2, M3 according to FIG. 1b, interconnected to form a ladder-shaped resonant antenna.

[0307] FIG. 2c shows a low pass antenna 9.2 made of a series of low pass meshes M1, M2, M3 according to FIG. 2b, interconnected to form a ladder-shaped resonant antenna.

[0308] FIG. 3c shows a hybrid antenna 9.3 made of a series of elementary meshes M1, M2, M3 according to FIG. 3b, interconnected to form a ladder-shaped resonant antenna.

[0309] In all three embodiments, adjacent meshes such as meshes M1 and M2 have a common conductive leg 2.

[0310] If N is the number of legs of the antenna, said antenna presents N1 resonant frequencies.

[0311] The values of these resonant frequencies depend on the geometry of the legs 1, 2 (length, diameter, distance between two adjacent legs . . . ) and on the values of the capacitors 5, 6.

[0312] The antenna can be operated at e.g. 50 kW and 13.56 MHz.

[0313] If all capacitors 5, 6 have the same capacitance, and if all the legs 1,2 are identical (same inductance), each resonant frequency corresponds to a sinusoidal current distribution in the antenna legs such as legs 1,2, as shown for instance on FIG. 7 of EP 2 396 804 B1.

[0314] When excited at a resonant frequency, the antenna produces an electromagnetic (EM) field pattern with a very well defined sinusoidal spatial structure. This allows a great control on the excitation of EM normal modes in the plasma (normal mode=eigenfunction). The antenna will always be excited (or fed) at one, or several, of its resonant frequencies.

[0315] A large variety of EM waves can be excited in plasmas. Certain categories of waves can only exist if the plasma is magnetized, as for example helicon waves.

[0316] Helicon waves are interesting because they lead, when damped, to a strong heating of the plasma, and then to high electrons densities. Plane polarized helicon-like waves can be excited in a plasma slab, typically in the radiofrequency (RF) range (typ. 1-100 MHz). Hence in a preferred embodiment a static magnetic field is applied in the vicinity of the antenna and the process chamber.

[0317] It has to be noticed that this is not a strict requirement for a plasma to be generated by the antenna, as the antenna can also operate without any (static) magnetic field, essentially by means of an inductive coupling with the plasma.

[0318] The (static) magnetic field can be generated by different means, such as permanent magnets as shown on FIGS. 11 and 12 of EP 2 396 804 B1, or DC (direct current) injected into the antenna on both ends of the conductive legs in each case through choke coils as shown in FIG. 18 of EP 2 396 804 B1.

[0319] As long as the RF generator frequency corresponds to a desired resonant frequency of the antenna, the RF energy might be injected anywhere on the antenna structure. As a matter of fact, if the antenna is excited at a resonant frequency, the current distribution is not affected by the localization of the RF injection points. But the antenna impedance seen by the RF generator will depend on these injection points. From this point of view, it is generally better, although not necessary, to feed the antenna all across its structure, that is to say at end injection points as shown on FIG. 13 or 14 of EP 2 396 804 B1. On FIG. 13 of EP 2 396 804 B1, the RF generator feeds the antenna at two opposing end points. On FIG. 14 of EP 2 396 804 B1, the RF generator feeds the antenna at two lower end injection points.

[0320] A quadratic (or bi-phased) feeding of the antenna is also possible. An example of such a configuration is shown on FIG. 9 of EP 2 396 804 B1. According to this embodiment the first leg and the last leg of the antenna are connected together at both ends by means of return lines each one containing a compensation capacitor. The value of the compensation capacitors is adjusted to compensate the inductance of the long conductors, necessary to cover the distance between the two extreme legs. The principle of the bi-phased feeding consists in exciting the antenna with two phase shifted signals injected at two distant injection points such as injection points.

[0321] FIGS. 4, 5, 6a and 7a show in a very schematic manner different embodiments of the device 10.1, 10.2, 10.3, 10.4 (generally named: 10) according to the invention with a modular layout.

[0322] Basically, the layout of the device 10 is such that the device forms a first process section where the transporting path T1 of the web substrate is bottom up and that the device forms a second process section where the transporting path T2 of the web substrate is top down.

[0323] The device comprises a base module 25a with a unwind roller 20 and a rewind roller 21. The base module 25a also contains drives for driving the rollers 20, 21 (not shown). The base module 25a can also contain a treatment station, e.g. a pre-treatment station as e.g. shown in the embodiment according to FIG. 12.

[0324] The device 10 further comprises at least one treatment module 25b, 25b, 25b which is arranged atop the base module 25a. The at least one treatment module 25b, 25b, 25b contains a first and second treatment station 12a, 12b, each with a process chamber and a pumping system 19 to evacuate the process chamber. The pumping system 19 reduces and maintains the pressure in the region of e.g. a few Pa.

[0325] Of course, in each case a gas supply system is provided to feed the process chamber with a process gas. However, for reasons of simplicity the gas supply system is not shown in FIGS. 4, 5, 6 and 7.

[0326] The treatment stations 12a, 12b are arranged side by side wherein the process direction, i.e. the transporting path T1 of the web substrate in the first treatment station 12a is bottom up and in the second treatment station 12b top down.

[0327] Each treatment station 12a, 12b further comprises a feed and a discharge passage opening for the web substrate. The passage openings form process interfaces between the modules.

[0328] On top of the modular device 10, i.e. above the at least one treatment module 25b, 25b, 25b, a deflection module 25c, i.e. a top module, is arranged. The deflection module 25c contains two deflection rollers 22a, 22b which deflect the web substrate 15 from a bottom up direction T1 into a top down direction T2.

[0329] In present case the deflection rollers 22a, 22b also serve as span rollers which forms together with the span rollers 16, 17 in the base module 25a a free span for the web substrate 15 in the treatment station 12a, 12b of the at least one treatment module 25b, 25b, 25b.

[0330] Each treatment station 12a, 12b of the at least one treatment module 25b, 25b, 25b contains at least one plasma treatment unit 13a, 13b with a flat antenna as it is e.g. shown in FIGS. 1 to 3. The at least one plasma treatment unit 13a, 13b can e.g. comprise a plasma source assembly 80 as shown in FIG. 11.

[0331] The plane antenna 9 of the at least one plasma treatment unit 13a, 13b is vertically (X) aligned and runs parallel to the web substrate 15. Between the web substrate 15 and the antenna of the at least one plasma treatment unit 13a, 13b a vertical planer plasma zone 14a, 14b is formed for treating the surface of the web substrate facing the plasma zone 14a, 14b.

[0332] For treating the web substrate 15 the untreated web substrate 15a is continuously unwound from the unwind roller 20 and deflected by the deflection and span roller 16 into a bottom up direction. The web substrate enters the process chamber of the first treatment station 12a of the at least one treatment module 25b, 25b, 25b through a feed passage opening (not shown) and is transported through the first treatment station 12a. Thereby the web substrate 15 is transported in a bottom up direction through the plasma zone 14a and continuously treated by the plasma generated by the plasma treatment unit 13a of the first treatment station 12a.

[0333] The web substrate 15 leaves the process chamber of the first treatment station 12a through a discharge passage opening (not shown) and enters the deflection module 25c. In the deflection module 25c the web substrate 15 is deflected by the deflection and span rollers 22a, 22b from the bottom up direction into a top down direction T2.

[0334] The web substrate 15 during its transportation leaves the deflection module 25c and enters the process chamber of the second treatment station 12b by a feed passage opening (not shown) in the top down direction. Thereby the web substrate 15 is transported in a top down direction through the plasma zone 14b and continuously treated by the plasma generated by the plasma treatment unit 13b of the second treatment station 12b.

[0335] The web substrate 15 leaves the process chamber of the second treatment station 12b through a discharge passage opening (not shown) in the top down direction and enters the base module 25a. In the base module 25a the treated web substrate 15b is rewound by the rewind roller 21.

[0336] The devices 10.1, 10.3, 10.4 according to FIGS. 4, 6a and 7a contain exactly one treatment module 25b, 25b, 25b which is arranged between the base module 25a and the deflection module 25c.

[0337] The first and second station 12a, 12b of the treatment module 25b together form two plasma zones for the same treatment, e.g. coating, of the same surface of the web substrate 15. Due to the double treatment of the web surface in a first treatment station 12a in a bottom up direction and in a second treatment station 12b in the top down direction the efficiency of the treatment process is increased.

[0338] The doubling of the treatment allows either the formation of thicker coatings at the same process speed or a coating of same quality at double speed in comparison with only one treatment step for the web surface.

[0339] In the embodiment according to FIG. 4 the process speed can be increased up to 400 m/min instead of 200 m/min with only one treatment station 12a. The line speed of a known capacitive plasma coupled magnetron device with one treatment drum is for comparison 100 m/min.

[0340] The device 10.2 according to FIG. 5 contains two identical treatment modules 25b as described above. The treatment modules 25b are arranged atop each other between the base module 25a and the deflection module 25c.

[0341] According to this arrangement the web substrate is transported in the first bottom up process section through to treatment stations 12a, 12b of the two treatment modules 25b and in the following second top down process section through another two treatment stations, 12c, 12d of the same two treatment modules 25b. Each of the four treatment stations 12a, 12b, 12c, 12d contains a plasma treatment unit 13a, 13b, 13c, 13d which forms a plasma zone 14a, 14b, 14c, 14d.

[0342] Accordingly, the treatment zone quadruples. I.e., the process speed can be increased up to 800 m/min instead of 400 m/min with only one treatment module 25b.

[0343] The treatment stations 12a, 12b of the devices according to FIGS. 6a and 7a in each case contain a first and second plasma treatment unit 13a, 13a; 13b, 13b which are arranged opposite to each other so that the treatment path of the web substrates runs between a pair of plasma treatment units 13a, 13a; 13b, 13b. Between the web substrate 15 and the plasma treatment units 13a, 13a; 13b, 13b in each case a plasma zone 14a, 14a; 14b, 14b is formed, so that both sides of the web substrate 15 are treated simultaneously.

[0344] In the device according to FIG. 6a the web substrate 30c (see also FIG. 6b) in the first bottom up treatment station 12a is coated on a first web substrate side with a first coating 30b, e.g. a barrier coating, by a first plasma treatment unit 13a and on a second web substrate side with a second coating 30d by a second plasma treatment unit 13a.

[0345] Subsequently the web substrate 30 in the second top down treatment station 12b is coated on the first web substrate side with a third coating 30a, e.g. a second barrier coating, by a first plasma treatment unit 13b and on the second web substrate side again with a further second coating 30d by a second plasma treatment unit 13b.

[0346] As the different coating layers 30a, 30b are only coated with one plasma treatment unit 13a, 13b, the process speed is relatively low and is about 200 m/min. However, in return the web substrate is coated on both sides and with multi-layers within the mentioned process speed.

[0347] In the device according to FIG. 7a the web substrate 31b (see also FIG. 7b) in the first bottom up treatment station 12a is coated on a first web substrate side with a first coating 31a, e.g. a barrier coating, by a first plasma treatment unit 13a and on a second web substrate side with a second coating 31c by a second plasma treatment unit 13a.

[0348] Subsequently the web substrate 31 in the second top down treatment station 12b is coated on the first web substrate side again with the same first coating 31a by a first plasma treatment unit 13b and on the second web substrate side again with the same second coating 31c by a second plasma treatment unit 13b.

[0349] As the coating layers 31a, 31c on both sides of the web substrate are in each case coated on two plasma treatment units 13a, 13a; 13b, 13b the process speed is higher and amounts about 400 m/min.

[0350] FIG. 8 shows schematically a treatment station 40 in more detail. The treatment station 40 defines a process chamber 50 with a feed passage opening 48a for the incoming web substrate 47a and with a discharge passage opening 48b for the outgoing treated web substrate 47c. The treatment station 40 further comprises a pumping system 42 for generating a low pressure in the process chamber 50.

[0351] Within the process chamber 50 a plasma treatment unit 45 with a plasma source assembly containing a plane antenna 9 is arranged. The plane antenna 9 is connected to an RF generator 41.

[0352] The plasma treatment unit 45 also contains a bias electrode arrangement with a bias electrode 44. The bias electrode 44 is arranged opposite to the plasma source assembly and extends over the whole area of the plane antenna 9. The bias electrode 44 runs parallel to the plane antenna 9. The bias electrode 44 is powered by an RF generator 52. A matching network 51 is provided which interconnects the RF generator 52 and the bias electrode 44.

[0353] The bias electrode aims the control of the ion bombardment on the coating during the coating growth process. In particular the coating density, the coating chemistry (e.g. hydrogen to carbon ratio and carbon atomic orbital hybridization, sp2/sp3) and the coating amorphisation can be controlled. As the ion bombardment is present during the full coating growth time, the obtained coating is isotropic.

[0354] According to a modification of the embodiment according to FIG. 8, the bias electrode 44a extends only over a part of the area of the plane antenna 9 as viewed in process direction. According to this modification the obtained coating exhibits anisotropic properties.

[0355] It is also possible to operate the treatment station 40 according to FIG. 8 without a bias electrode arrangement.

[0356] The web substrate 47 in the process chamber 50 is transported along a treatment path section between the plasma source assembly and the bias electrode 44. The length of the treatment path section within the plasma can e.g. be 0.2 to 1 m.

[0357] The treatment path section and accordingly the web substrate 47b in the treatment path section runs at a distance to the separation plane of the plasma source assembly so that the plasma zone 46 is formed between the web substrate 47b in the treatment path section and the separation plane. Thus, the plasma generated in the plasma zone 46 is confined between the web substrate 47b and the separation plane.

[0358] Within the process chamber 50 two deflection rollers 49a, 49b in the function of span members are provided which are spaced from each other and which form a free span for the web substrate 47. The treatment path section for the web substrate 47b lies within this free span.

[0359] Furthermore, a gas supply system 43 is provided which supplies a process gas into the plasma zone 46.

[0360] The FIGS. 9 and 10 show different layouts of the web run within the process chamber of a plasma treatment unit, e.g. according to FIG. 8. FIGS. 9 and 10 also show a plasma treatment unit 55, 65 with a plasma source assembly connected to an RF generator 51, 61. Further, FIGS. 9 and 10 show the incoming web substrate 57a, 67a and the outgoing treated web substrate 57c, 67d.

[0361] In FIG. 9 the deflection rollers 59a, 59b, which form the span members, are arranged such that the free span of the web substrate and accordingly the treatment path section is close to the separation plane of the plasma treatment unit 55 such that the plasma zone 56 is arranged on the side of the web substrate 57b in the treatment path section facing away from the plane antenna of the plasma treatment unit 55.

[0362] In FIG. 10 a first and second deflection roller 69a, 69b form a first and second span member and are arranged such that a first free span of the web substrate 67b and thus a first treatment path section are formed close to the separation plane of the plasma treatment unit 65. This, such that the plasma zone 66 is formed on the side of the web substrate 67b along the treatment path section facing away from the plane antenna of the plasma treatment unit 65.

[0363] The web substrate 67 is deflected on the second deflecting roller 69b such that the web substrate 67 runs in opposite direction towards a third deflection roller 69c which forms a third span member. The second and third deflection roller 69b, 69c are arranged such that a second free span of the web substrate 67c and thus a second treatment path section is formed which is spaced from the separation plane of the plasma treatment unit 65. This, such that the plasma zone 66 is arranged between the first and second free span of web substrate 67b, 67c, i.e. between the first and second treatment path section.

[0364] The treated web substrate 57c is deflected by a further deflection roller 69d before it leaves the process chamber (not shown).

[0365] The plasma source assembly according to FIG. 4, 5, 6a, 7a, 8, 9, 10, but also according to FIG. 12 can be designed according to FIG. 11. FIG. 11 shows a plasma treatment unit with a plasma source assembly 80 and an RF generator 82. The plasma source assembly 80 comprises a plane antenna 9 as e.g. shown in FIGS. 1, 2 and 3 which is connected to the RF generator 82.

[0366] The plane antenna 9 is embedded in a dielectric material 83. The plasma source assembly 80 further comprises a conductive bottom plate 85, e.g. of metal, which defines a lower termination of the plasma source assembly 80. The plasma source assembly 80 further contains a dielectric top plate 84, e.g. made of glass or ceramics, which defines an upper termination of the plasma source assembly 80. The dielectric top plate 84 is facing the plasma zone of the plasma treatment unit and forms the separation plane.

[0367] The dielectric material 83 is confined between the conductive bottom plate 85 and the dielectric top plate 84. The dielectric material 83 is further confined by a lateral frame 86 which laterally encloses the plasma source assembly 80.

[0368] The ladder-type, plane antenna 9 contains a plurality of parallel legs 1, 2 which are connected with shorter elements each containing a capacitor 5. The transporting direction P of the web substrate can be parallel to the legs 1, 2. However, more uniform treatment results are achieved, when the transporting direction P of the web substrate runs perpendicular to the legs 1, 2.

[0369] FIG. 12 shows a cross-section of a schematically outlined device 90 according to a further embodiment. The device comprises a base module 95a with an unwind roller 91 to unwind the untreated web substrate 94a and a rewind roller 93 to rewind the treated web substrate 94b.

[0370] The base module 95a further comprises a pre-treatment station 92a with a plasma treatment unit according to the invention which is arranged in a rear section of the base module 95a. Span rollers 98a, 98b define a free span which contains the treatment path section of the web substrate 94 in the treatment station 92a. The free span and accordingly the pre-treatment path section for the web substrate 94 and the plane antenna are vertically (X) aligned.

[0371] In the pre-treatment station 92a the web substrate 94 is prepared for a subsequent coating. A task of the preparation process is to increase the adhesion of the coating on the web substrate 94.

[0372] Furthermore, a treatment module 95b is arranged atop the base module 95a. The treatment module 95b contains two treatment stations 92b, 92c, each with a plasma treatment unit according to the invention for coating the web substrate 94. The treatment stations 92b, 92c are arranged side by side. The first treatment station 92b is arranged in a back section of the treatment module 95b and operated in a bottom up process direction P. The second treatment station 92c is arranged in a front section of the treatment module 95b and is operated in a top down process direction P.

[0373] Span rollers 98a, 98b in each case define a free span which contains the treatment path section of the web substrate 94 in the treatment stations 92b, 92c. The free spans and accordingly the treatment path sections for the web substrate 94 and the plane antenna are vertically (X) aligned.

[0374] On top of the device 90 and atop the treatment module 95b a top module 95c is arranged with driven deflection rollers 97a, 97b which deflect the web substrate 94 from a bottom up process direction into a top down process direction. The deflection rollers 97a, 97b also serve as cooling rollers.

[0375] The device 90 is operated by continuously unwinding an untreated web substrate 94a from the unwind roller 91 and continuously rewinding the treated web substrate 94b on the rewinding roller 93. During this process the web substrate 94 is transported in a back section of the device 90 via deflection rollers in a bottom up process direction through the pre-treatment station 92a. The web substrate 94 is pre-treated while passing through the pre-treatment station 92a.

[0376] Subsequently, the pre-treated web substrate 94 leaves the base module 95a and enters the treatment module 95b in the back section of the device 90, still in a bottom up process direction P.

[0377] The web substrate 94 is transported in the back section of the device 90 in a bottom up process direction through the first treatment station 92b of the treatment module 95b. The web substrate 94 is coated while passing through the first treatment station 92b.

[0378] Subsequently, the coated web substrate 94 leaves the treatment module 95b and enters the top module 95c. In the top module 95c the web substrate 94 is deflected from the bottom up process direction P into the top down process direction via deflecting rollers 97a, 97b.

[0379] Subsequently, the coated web substrate 94 leaves the top module 95c and enters again the treatment module 95b, this time in the top down process direction P and in a front section of the treatment module 95b or the device 90 respectively.

[0380] The web substrate 94 is transported in the front section of the device 90 in the top down process direction through the second treatment station 92c of the treatment module 95b. The web substrate 94 is coated while passing through the second treatment station 92c.

[0381] Subsequently, the treated web substrate 94b leaves again the treatment module 95b in the top down process direction and enters the base module 95a again.

[0382] In the base module 95a a quality control system 100 is arranged along the transporting path of the treated web substrate 94b. The quality control system 100 can comprise sensors which work on the principle of coating optical density measurement.

[0383] After the passing the quality control system 100 the treated web substrate 94b is further transported via deflection rollers to the rewind roller 93 and rewound. A lay on roller 99 with constant distance assures a wrinkle free winding.

[0384] To ensure the required tension of the web substrate 94 along its process path, dancer rollers 96 can be provided.

[0385] FIG. 13 shows an alternative design of a plasma treatment station 70a with a rotatable drum 72 and with a curved plasma source assembly 74a having a curved extensive antenna 73a. The curved shape of the extensive antenna 73a is adapted to the shape of the curved surface area of the rotatable drum 72. Accordingly, the cover plate of the plasma source assembly 74a facing the web substrate 71 is curved as well. The surface of the cover plate forms the separation surface.

[0386] The plasma source assembly 74a with its curved, extensive antenna 73a is arranged at a distance to the rotatable drum 72 so that a curved gap 75a is formed between the rotatable drum 72 and the plasma source assembly 74a. The plasma zone is formed in the space formed by the curved gap 75a.

[0387] FIG. 14 shows a further alternative design of a plasma treatment station 70b with a rotatable drum 72 and with two plane plasma source assembly 74b having a plane antenna 73b. The cover plate facing the rotatable drum 72 towards the transporting path of the web substrate 71 is plane. The surface of the cover plate forms the separation surface.

[0388] The plasma source assembly 74b with its plane antenna 73b is arranged at a distance to the rotatable drum 72 so that a gap 75b is formed between the rotatable drum 72 and the plasma source assembly 74b. The plasma zone is formed in the space formed by the gap 75b.

[0389] In operation, the web substrate 71 according to FIGS. 13 and 14, in the region of the formed plasma zone, rests on a curved circumferential treatment surface area of the drum 72 and is transported at the rotation speed of the rotating drum 72, while being coated.

[0390] FIG. 15 shows a further layout of a plasma treatment station with a plasma treatment unit 115 and the web run within plasma treatment station.

[0391] The plasma treatment unit 115 contains a plasma source assembly with a plane antenna embedded in a dielectric material. The plasma source assembly is connected to an RF generator 112.

[0392] The plasma source assembly comprise on both opposites sides a dielectric cover plate which, in each case, forms a separation surface towards a web substrate treatment path. I.e. instead of a conductive base plate a second dielectric cover plate is provided.

[0393] As a consequence on both sides of the cover plate a plasma zone 116a, 116b is formed. The web substrate 117 now runs along a first treatment path parallel to the plane antenna at a distance to the first cover plate so that a first plasma zone 116a is formed between the web substrate 117, i.e. the first treatment path, and the first cover plate.

[0394] Subsequent to the first treatment path the web substrate 117 is deflected via a deflection roller 118 in an opposite transport direction at a distance and parallel to the first treatment path. The deflected web substrate 117 passes now the plane antenna, i.e. the plasma source assembly, on the opposite side and at distance to the second cover plate along a second treatment path. Between the web substrate 117, i.e. the second treatment path, and the second cover plate a second plasma zone 116b is formed. In the second plasma zone 116b a second treatment step is carried out on the surface of the web substrate 117 already treated in the first plasma zone 116a. The web substrates may be cooled or adjusted to a desired web temperature by the e.g. deflection roller 118 being designed as a cooling roller. However, providing a separate cooling roller is also possible.

[0395] Furthermore, a gas supply system, in particular gas injectors 114, is provided which supplies a process gas into the plasma zones 116a, 116b.

[0396] Accordingly, the plane antenna, i.e. the plasma source assembly, is arranged between a first and second parallel web substrate treatment path.

[0397] FIG. 16 shows a further layout of a plasma treatment station with a plasma treatment unit 115 and the web run within plasma treatment station. The plasma treatment station is similar to the embodiment according to FIG. 15.

[0398] However, in this embodiment, two different substrate webs are treated along the first and second parallel web substrate treatment paths, in the plasma zones 116a and 116b, with the same plasma treatment unit 115 containing the same plasma source assembly arranged in between the two treatment paths as disclosed in FIG. 15. Thus, a first web substrate 119a is forwarded from a first unwinding storage reel 120a or prior treatment step, passing along the first treatment path, by the plasma source, and after plasma treatment forwarded to a next step or wound up onto a subsequent, first winding storage reel 120b, while simultaneously, a second web substrate 119b is forwarded from a second unwinding storage reel 121a or treatment step, passing along the second treatment path, by and on the other side of the plasma source, and after plasma treatment forwarded to a next step or wound up onto a second, subsequent, winding storage reel 121b.

[0399] The web substrates may be cooled or adjusted to a desired web temperature by cooling rollers at the inlets and outlets of the plasma treatment paths.

[0400] Furthermore, a gas supply system, in particular gas injectors 114, is provided which supplies a process gas into the plasma zones 116a, 116b.