DEVICE AND METHOD FOR PRODUCING LAYERS WITH IMPROVED UNIFORMITY IN COATING SYSTEMS WITH HORIZONTALLY ROTATING SUBSTRATE GUIDING

Abstract

The invention relates to a device and a method for producing layers with very good uniformity in coating systems with horizontally rotating substrate guiding. Alternatively, certain layer thickness gradients can be set. The particle loading is also significantly reduced. The service life is much higher compared to other methods. Parasitic coatings are reduced. The coating rate is also increased.

Claims

1-21. (canceled)

22. A device for depositing uniform layers on rotationally moved substrates by magnetron sputtering comprising a) a vacuum chamber; b) at least one inlet for a sputtering gas; c) a turntable with at least one substrate holder; and d) at least one lighting source consisting of a linearly extended dual magnetron source and the dual magnetron source consists of two linear magnetron electrodes, with a coating source having an inhomogeneous plasma density that enables an inhomogeneous removal rate.

23. The device according to claim 22, wherein the magnetron electrodes have an inhomogeneous magnetic field and/or the magnetron electrodes have a substantially asymmetrically poled magnet configuration and/or the coating source has a generator with a settable pulse shape and/or pulse frequency.

24. The device according to claim 23, wherein the inhomogeneous removal rate increases from the turntable center to the turntable margin.

25. The device according to claim 22, wherein the device has at least one plasma source.

26. The device according to claim 22, wherein the at least one dual magnetron source consists of magnetron electrodes of a cylindrical or planar source material and of a holder for the planar source material and a target belonging thereto.

27. The device according to claim 22, wherein the at least one magnetron electrode comprises a target material comprising a) ceramic material or material mixtures; b) thermally injected material or material mixtures; c) crystalline material; d) metallic material or material mixtures; and/or e) a material containing an oxide; and f) mixtures thereof.

28. The device according to claim 22, wherein the distance from the substrate to the at least one magnetron electrode amounts to 5 to 30 cm.

29. The device according to claim 22, wherein the distance between the turntable and the boundary walls of the magnetron sputtering device amounts to 0.1 to 5 mm.

30. The device according to claim 22, wherein the device has a DC current supply pulsed in the mid frequency range or a pulsed DC current supply.

31. The device according to claim 22, wherein the device comprises a photometer, ellipsometry flanges, and/or a component which exerts a polarization effect.

32. The device according to claim 22, wherein the device has a regulation system for regulating and/or stabilizing the partial pressure in the magnetron sputtering device.

33. The device according to claim 22, wherein the device has a unit for tilting and/or for rotating the sets of magnet in the magnetron electrodes.

34. The device according to claim 22, wherein the device has at least one correction aperture.

35. A method of depositing uniform layers on a rotationally moved substrate by magnetron sputtering, in which a) at least one substrate is arranged on a turntable in a vacuum chamber to enable a coating on a rotational movement of the substrate; and b) at least one layer is deposited on the at least one substrate by utilizing at least one coating source comprising a linearly extended dual magnetron source, with the layers of source material of the magnetron electrodes being formed by sputter gas, wherein the coating source has an inhomogeneous plasma density that effects an inhomogeneous removal rate of the source material.

36. The method according to claim 35, wherein the magnetron electrodes have an inhomogeneous magnetic field and/or the magnetron electrodes have a substantially asymmetrically poled magnet configuration and/or the coating source has a generator with a settable pulse shape and/or pulse frequency.

37. The method according to claim 35, wherein the inhomogeneous removal rate increases from the turntable center to the turntable margin.

38. The method according to claim 35, which includes pretreating the surface of the substrate with a plasma source or modifying the structure and/or the stoichiometry of the layer via plasma effect.

39. The method according to claim 35, which utilizes a noble gas as the sputtering gas.

40. The method according to claim 39, wherein the sputtering gas is argon.

41. The method according to claim 39, which utilizes at least one reactive gas in addition to the sputtering gas.

42. The method according to claim 41, wherein the at least one reactive gas is selected from the group consisting of oxygen, nitrogen, hydrogen, carbon dioxide, forming gas, hydrogen fluoride, acetylene, tetrafluoromethane, octafluorocyclobutane, and mixtures thereof.

43. The method according to claim 35, wherein the thickness of the layer on the substrate is monitored by at least one of the measures a) to e) for a process control: a) time control; b) optical transmission monitoring; c) optical reflection monitoring; d) optical absorption monitoring; e) monowavelength ellipsometry or spectral ellipsometry; and/or f) crystal quartz measurement.

44. The method according to claim 35, which utilizes a device for depositing uniform layers on rotationally moved substrates by magnetron sputtering comprising a) a vacuum chamber; b) at least one inlet for a sputtering gas; c) a turntable with at least one substrate holder; and d) at least one lighting source consisting of a linearly extended dual magnetron source and the dual magnetron source consists of two linear magnetron electrodes, with a coating source having an inhomogeneous plasma density that enables an inhomogeneous removal rate.

Description

[0122] FIG. 1 shows a device in accordance with the invention without a turntable in a plan view;

[0123] FIG. 2 shows a device in accordance with the invention with a turntable in a plan view;

[0124] FIG. 3 shows a device in accordance with the invention in a sectional representation;

[0125] FIG. 4 shows a device in accordance with the prior art with symmetrical polarity;

[0126] FIG. 5 shows a device in accordance with the invention with asymmetrical polarity;

[0127] FIG. 6 shows the time dependent voltage difference between the targets with a sinusoidal excitation of 40 kHz in a diagram;

[0128] FIG. 7 schematically shows a visualization of the averaged ion flow density on cylindrical targets;

[0129] FIG. 8 shows a diagram in which the averaged ion flow density for the configuration “even” is shown over time and target area;

[0130] FIG. 9 shows a diagram in which the averaged ion flow density for the configuration “odd” is shown over time and target area;

[0131] FIG. 10 shows the comparison of the emission profiles for argon ions in accordance with the method in accordance with the invention and the method in accordance with the prior art in a diagram; and

[0132] FIG. 11 shows the comparison of the coating rate resulting on the substrate without a separate uniformity screen in accordance with the invention and in accordance with the prior art.

[0133] FIG. 1 schematically shows a preferred device in accordance with the invention without a turntable in a plan view. The device has three magnetron sputtering devices 2, 3, 4, of which one is designed in the single magnetron arrangement 2 and two in the dual magnetron arrangement 3, 4. The magnetron sputtering device 2 comprises a magnetron electrode 5, sputtering gas 11 and optionally reactive gas 8 and is in a vacuum 1. The magnetron sputtering devices 3, 4 each comprise two magnetron electrodes 6, 7, sputtering gas 11, and optionally reactive gas 8 and are in a vacuum 1. A plasma source 12 and a photometer 16 and/or an ellipsometry flange 17 are located in the vicinity of the magnetron sputtering devices 2, 3, 4.

[0134] FIG. 2 schematically shows a preferred embodiment of the turntable in a plan view. The turntable 10 is located in the apparatus and in this example has ten identical substrate holders 9.

[0135] FIG. 3 schematically shows a preferred embodiment of the device with a turntable 10 in a side view. The cross-section of a magnetron sputtering device is visible which comprises two cylinders of source material 6, 7 (dual magnetron arrangement). The magnetron sputtering device is delineated in a gas-tight manner from the rest of the device at the sides of boundary walls 14, 15 and at the top by the turntable 10; it comprises sputtering gas 11, optionally reactive gas 8 and is in a vacuum 1. Two substrate holders 9 of the turntable 10 are shown or visible in the cross-section. A cover 13 is located above the turntable 10 and has boundary walls which are located to the side of the turntable 10 that close the device in a gas-tight manner.

[0136] A sputtering device in accordance with the prior art is shown in FIG. 4 that has a cylindrical dual magnetron arrangement with symmetrical polarity.

[0137] The generator supplies the sources with voltage pulsed in a bipolar manner, with the pulses being able to have sinusoidal, rectangular, or also other pulse patterns.

[0138] A sputtering device in accordance with the invention is shown in FIG. 5 that has a cylindrical dual magnetron with asymmetrical polarity. The generator supplies the sources in this example with voltage that is pulsed in a bipolar manner, with the pulses being sinusoidal. The correction aperture is here largely removed from the coating region.

[0139] The cylindrical dual magnetron arrangement shown in FIG. 5 was examined by means of particle-in-cell plasma simulation.

[0140] The simulation parameters are compiled in the following:

[0141] Model dimensions: 800×600×400 mm.sup.2

[0142] Cell number: 100×150×100

[0143] Time step: 5e-11 s

[0144] Time interval: 250 μs

[0145] Length, cyl. targets: 513 mm

[0146] Target diameter: 138 mm

[0147] Excitation frequency: 40 kHz

[0148] Modeled power: 1 W (temporal average)

[0149] Max. voltage difference: 1000 V

[0150] Secondary electron yield: 12%

[0151] Electron capture at the target: 100%

[0152] Magnetic remanence: 1.4 T

[0153] Magnetic susceptibility: 1.05

[0154] Susceptibility of the yoke: 1000

[0155] Magnetic tilt: ±6° to the inside

[0156] The electrical feed into the two cylindrical targets takes place in a bipolar manner. In this respect, the voltage difference between the targets is predefined; the potential difference from the mass (=chamber wall) results automatically during the simulation with reference to the reception of positive and negative charges. The targets are periodically reversed in polarity in the form of a sinusoidal signal; the excitation frequency amounts to 40 kHz.

[0157] A model of a commercial set of magnets for cylindrical targets is first assumed for the magnets. Both sets of magnets are tilted toward the center by 100 in the model. In the standard design, both sets of magnets have the same polarity, i.e., the upper side of the outer magnetic ring to the north pole, the upper side of the inner magnet to the south pole. This configuration will be called “even” in the following. In the case in accordance with the invention, the second set of magnets (at the right hand side in FIG. 5) are reversed in polarity; this configuration will be called “odd” in the following.

[0158] During the simulation, the dissipated plasma power is continuously detected (with reference to the kinetic energy of charged particles before and after a time step) and is respectively accumulated over 0.1 μs. The voltage difference between the targets is regulated by means of a proportional regulator by a comparison of the desired power and the actual power. The resulting time dependent curves of voltage and power can be seen from FIG. 6. It generally takes longer than 50 μs until a quasi-stationary discharge state is assumed. It is furthermore conspicuous that a smaller voltage difference is adopted in balance in the “odd” configuration in accordance with the invention, i.e., the discharge takes place with low impedance. The ion flow profiles on the target for the determination of the sputter erosion distribution are therefore averaged over the last 12 half waves, i.e., in a time interval of 102.5 μs to 250 μs in steps of 2.5 μs. The ion flows in a three-dimensional view are shown in FIG. 7. The ion flow density accumulated from the ion flows at the targets shows a diagonally symmetrical distribution for the “even” configuration (see FIG. 8) and a unilateral distribution for the “odd” configuration (see FIG. 9).

[0159] It can furthermore be seen that the absolute value of the flow density is higher in the “odd” configuration, which is associated with the already mentioned lower plasma impedance. A lower plasma impedance is advantageous as long as the voltage for the sputtering effect is sufficient because generally the tendency to unwanted discharges (arcs) is reduced. The higher ion flow density in FIG. 9 is also advantageous because it results in a higher rate.

[0160] FIG. 10 shows the cumulative ion flow density at the target in a second arrangement. In this respect, the gradient of the ion flow density is reversed so that a small removal rate toward the outside results. With a further distribution mask, it is thus possible to produce a greater layer thickness gradient.

[0161] Since the targets rotate during the coating and the substrates rotate on the turntable over both targets, the ion flow profile averaged over the target area is decisive both for the erosion profile on the target and for the layer thickness distribution. With an approximately constant energy distribution of the Ar ions on the target, the ion flow profile is proportional to the sputtering rate. This is shown in FIG. 11 for a time average interval of 100-250 μs, i.e., over 12 half cycles of the sinusoidal excitation.

[0162] It can be recognized for the “even” arrangement that an incident coating rate results in the region of the substrates. This region comprises the radial position 270 to 470 mm (substrate diameter 200 mm). With a mask, the rate inwardly then has to be set to the inside to the minimal value of 70 (relative rate).

[0163] In the “odd” arrangement, an approximately smooth, homogeneous layer thickness profile results on the substrates in contrast, even without a uniformity mask. With a correct arrangement of the magnet polarity, the reduction of the layer thickness can thus be approximately compensated by the “odd” configuration over the turntable radius. Only a small portion of the coating flow toward the substrate thus to be screened and a higher coating rate results with the same sputtering power.