阅读说明：本技术 微波等离子体装置 (Microwave plasma device ) 是由 拉尔夫·施皮茨尔 于 2018-12-21 设计创作，主要内容包括：本发明涉及一种微波等离子体装置,所述微波等离子体装置包括处理空间和数量为两个以上的微波半导体。微波等离子体装置的特征在于,微波半导体以这样的方式附接到所述处理空间,使得微波半导体中的所述微波仅在所述处理空间中时干扰其他微波半导体的所述微波。本发明还涉及一种对应的方法。(The present invention relates to a microwave plasma device including a processing space and two or more microwave semiconductors. The microwave plasma device is characterized in that microwave semiconductors are attached to the process space in such a way that the microwaves in a microwave semiconductor only interfere with the microwaves of other microwave semiconductors when in the process space. The invention also relates to a corresponding method.)

1. A microwave plasma device comprising a process space and a number of more than two microwave semiconductors, characterized in that the microwave semiconductors are attached to the process space in such a way that the microwaves of a microwave semiconductor disturb the microwaves of other microwave semiconductors only when in the process space.

2. A microwave plasma device according to claim 1, characterized in that the microwaves are coupled out of the microwave semiconductor by means of an antenna, preferably a rod antenna, wherein the rod antenna is preferably configured as an extension of an inner conductor of an in particular coaxial output coupling device coupled out of the microwave semiconductor.

3. A microwave plasma device according to one of the preceding claims, characterized in that it is configured in such a way that microwaves are fed from the microwave semiconductor via further couplers and/or wave converters into the processing space, wherein the microwave plasma device preferably comprises a rectangular, elliptical or circular waveguide and/or coupler into which the microwaves are initially coupled, and an antenna arrangement from which the microwaves are coupled into the processing space, wherein the antenna of the antenna arrangement is preferably a slot antenna, a rod antenna or a hole coupler.

4. A microwave plasma device according to one of the preceding claims, characterized in that the process space is divided into two regions, in particular by means of a dielectric wall element as a wall or window, wherein the process space is preferably configured as a resonator, preferably as a cylindrical, rectangular, spherical, elliptical, coaxial resonator, or as a combination thereof.

5. A microwave plasma apparatus according to one of the preceding claims, characterized in that the microwave input coupling point in the process space lies in at least one plane.

6. A microwave plasma device according to one of the preceding claims, characterized in that a group of the microwave semiconductors is frequency coupled, wherein preferably all microwave semiconductors are frequency coupled to each other, and that there are separate microwave semiconductors or other groups of mutually frequency coupled microwave semiconductors emitting microwaves with other frequencies than the above-mentioned group.

7. A microwave plasma device according to one of the previous claims, characterized in that microwave semiconductors are configured to be excited in a pulsed manner, wherein preferably a group of said microwave semiconductors are pulse coupled and wherein all microwave semiconductors of the microwave plasma device are pulse coupled to each other, or there is a separate microwave semiconductor or other group of microwave semiconductors pulse coupled to each other emitting microwaves with other pulses than the above mentioned group.

8. A microwave plasma device according to one of the previous claims, characterized in that a group of microwave semiconductors is power coupled, wherein the power coupled in preferably varies over time, and wherein preferably all microwave semiconductors of the microwave plasma device are in this group, or there are separate microwave semiconductors or other groups of mutually power coupled microwave semiconductors emitting microwaves with a power other than the above-mentioned group.

9. A microwave plasma device according to one of the preceding claims, characterized in that the microwave semiconductors are configured to emit microwaves with a linear or circular polarization, wherein preferably a group of the microwave semiconductors is configured such that these microwave semiconductors emit microwaves of the same polarization.

10. A method for operating a microwave plasma device comprising two or more microwave semiconductors in a process space, wherein the microwaves of a microwave semiconductor are coupled into the process space in such a way that they interfere with the microwaves of the other microwave semiconductors only when in the process space.

Technical Field

The present invention relates to a microwave plasma device and a method for operating a microwave plasma device.

Background

Microwave radiators are used in various fields of industrial use. For example, they are used for the heat treatment of foodstuffs, plastics, rubbers or other substances. The technical field considered here is the use of microwave radiators for generating microwave plasma for various plasma applications, such as etching processes, cleaning processes, modification processes or coating processes. Typical frequencies of microwaves are in the range of 300MHz to 300 GHz.

There are various microwave generators for generating microwaves. Typically, magnetrons are used for the above applications.

As an alternative to magnetrons, power semiconductors may be used for microwave generation in plasma applications. However, they have only a relatively low power on the order of a few hundred watts. When using power semiconductors for generating microwaves at high power, several power semiconductors for generating microwaves may be interconnected by a combiner and then coupled to a rectangular waveguide. The rectangular waveguide then serves as a microwave input coupling device or generator for the plasma source. Such power semiconductors for generating microwaves are hereinafter referred to as "microwave semiconductors".

In order to couple high power uniformly into the microwave radiators, for example, DE 19600223a1 and DE19608949a1 describe a microwave divider in the form of a ring or coaxial resonator, which is connected upstream of the process space to achieve uniform coupling of microwave power into the process space from different directions. A disadvantage of this type of input coupling is that the uniformity of the power input coupling from the power supply structure is reduced due to load variations in the processing space.

Disclosure of Invention

It is an object of the present invention to overcome the disadvantages of the prior art and to provide a microwave plasma device and a method for operating a microwave plasma device by which power can be uniformly coupled into a processing space.

This object is achieved by a microwave plasma device and method according to the claims.

According to the invention, the object of power input coupling is achieved in that a plurality of microwave semiconductors are attached to the process space of a microwave plasma device in such a way that they couple microwaves directly into the process space. The term "directly" means that the microwaves of the individual microwave semiconductors do not overlap one another before irradiation. Thus, in contrast to the prior art, microwaves are independently coupled out of the microwave semiconductor. The term "directly" does not exclude that the microwave semiconductor may also couple microwaves into the process space through the guiding structure.

The processing space is configured such that plasma processing can be performed therein. In this regard, the process space is also synonymously referred to as a "plasma chamber" in the specification.

A microwave plasma device, in particular a microwave plasma device for generating a microwave-excited plasma, according to the invention comprises a process space and at least two or more microwave semiconductors. It is characterized in that the microwave semiconductors are attached to the process space in such a way that the microwaves of the (in particular each) microwave semiconductor interfere with the microwaves of the other microwave semiconductors only when in the process space.

For example, a microwave semiconductor may couple microwaves into the processing space through an antenna. However, the microwave semiconductors may also couple microwaves into the process space via a feed (feed) with a corresponding coupling point, wherein no further microwave semiconductors couple microwaves into this feed. Therefore, the feed member does not function as a combiner. The frequency ratio and the phase ratio of the respective microwave semiconductors may be coupled to each other, as necessary.

Although according to the invention only a single microwave semiconductor needs to fulfill the above-mentioned conditions, while other microwave semiconductors may in principle be connected by means of a combiner, it is particularly preferred that each microwave semiconductor couples its microwaves into the process space in the manner according to the invention, that is to say that no microwaves interfere with one another before they have been coupled in.

Preferred microwave semiconductors have a power of several tens of watts to several hundreds of watts, wherein a plurality of microwave semiconductors can preferably be connected on a circuit board in order to obtain a higher total power, in particular below 1000W. Preferably, the microwaves are coupled out of the plates by coaxial conductors. In particular, a plurality of microwave semiconductors for generating microwaves or a plurality of the above-mentioned circuit boards may be interconnected in terms of power. Due to its function, a circuit board having a plurality of microwave semiconductors is considered herein as a single "microwave semiconductor".

According to the invention, a plurality of microwave semiconductors are used in the invention for generating microwaves and microwave input couplings. The advantage of the microwave semiconductor is its simple and robust design and the possibility to adjust the frequency and phase characteristics of the individual microwave generators.

In the method according to the invention for operating a microwave plasma device (i.e. a device for generating a plasma excited by microwaves), preferably of the type described above, the microwaves of (in particular each) microwave semiconductor are coupled into the process space by means of more than two microwave semiconductors in such a way that they interfere with the microwaves of the other microwave semiconductors only when in the process space.

The microwaves are preferably coupled out of the microwave semiconductor by means of an antenna, which is preferably a rod antenna. For this purpose, the microwave semiconductor in question comprises an antenna, by means of which the microwaves generated by the microwave semiconductor are coupled out of the latter. The rod antenna is preferably realized as an extension of the inner conductor of the out-coupling means coupled out from the microwave semiconductor. The output coupling means are typically arranged coaxially.

The microwaves can be fed directly from the microwave semiconductor to the process space by means of the aforementioned antenna. However, depending on the application, it may be beneficial to do this feeding indirectly.

In this indirect case, the microwaves are fed from the microwave semiconductor into the processing space, preferably via further coupling elements or via a wave converter. In this case, microwaves from the microwave semiconductor are preferably coupled into such a coupling element. The coupling element preferably comprises a rectangular, elliptical or circular waveguide.

From the coupling element, the microwaves are preferably coupled into the processing space via a further antenna arrangement. Basically, the shape of the antennas of the antenna arrangement may be selected as desired according to the contemplated embodiments. Preferred antennas for coupling microwaves into the processing space are slot antennas, rod antennas or aperture couplers.

Preferably, the process space is divided into two regions, in particular by means of walls made of dielectric material or walls with dielectric windows. For this purpose, a quartz glass container (receiver) is preferable. A region into which microwaves are not directly coupled is used as a process space or a plasma chamber. This serves to protect the microwave source.

In a preferred embodiment of the device, the process space may be configured in the form of a resonator structure, such as a cylinder, a rectangle, a sphere, an ellipse, a coaxial resonator or a combination of these structures. This has the advantage that resonant microwaves can be generated inside it.

The process space, i.e. the plasma chamber, may comprise a sample receiving unit and/or a biasing electrode. The combination has the advantage that the elements of the plasma can be specifically directed onto the sample arranged on the sample receiving unit by means of a suitable potential between the biasing electrode and the sample receiving unit.

Those elements through which microwaves are introduced into the process space, in other words, for example, the antenna of a microwave semiconductor in the case of direct input coupling, or the elements of the antenna arrangement in the case of indirect input coupling, can be referred to as microwave input coupling points, since the microwaves are coupled into the process space through said microwave input coupling points.

Depending on the application, the microwave input coupling points may be distributed as desired in the process space. The microwave input coupling point is preferably located in one plane or in more than two planes in the process space.

Although input coupling of only one microwave frequency may be advantageous depending on the application, coupling microwaves of different frequencies may be advantageous in other applications. A group of microwave semiconductors is preferably configured such that they emit microwaves of the same frequency or that microwaves of the same frequency are coupled into the process space. This group of microwave semiconductors is also referred to herein as "frequency-coupled" microwave semiconductors. In this case, all microwave semiconductors of the microwave plasma device may be in this group, so that all microwave semiconductors are frequency-coupled, but depending on the application there may also be separate microwave semiconductors or other groups of microwave semiconductors frequency-coupled to each other, which emit microwaves having a frequency other than the above-mentioned groups. Thus, depending on the application, there may be different groups, each having more than two frequency-coupled microwave semiconductors, wherein the microwave frequencies of the different groups are different in each case.

Even though non-pulsed microwave transmission may be advantageous depending on the application, coupling in microwave pulses may be advantageous in other applications. According to a preferred embodiment, in this respect, the microwave semiconductor is configured to be pulsed or to be pulsed coupled into the microwaves. A group of microwave semiconductors is preferably configured such that they are synchronously pulsed or microwave pulses that are identical in the time domain are coupled into the process space. Such a set of microwave semiconductors is also referred to herein as a "pulse coupled" microwave semiconductor. In this case all microwave semiconductors of the microwave plasma device may be in the group, so that all microwave semiconductors are pulse-coupled, but depending on the application there may also be separate microwave semiconductors or other groups of microwave semiconductors pulse-coupled to each other, which emit microwaves with pulses other than the above-mentioned groups. Thus, depending on the application, there may be different groups, each group having more than two pulse-coupled microwave semiconductors, wherein the microwave pulses of the different groups differ in each case.

Thus, the microwaves may be coupled in a pulsed or non-pulsed manner as desired. Any desired pulse shape is possible. For example, the pulse trains of the individual microwave semiconductors, which are related to one another, can occur in groups, in a time-shifted manner, or simultaneously.

A group of microwave semiconductors is preferably configured in such a way that they emit microwaves of the same microwave power, or that microwaves of the same power are coupled into the process space. Such a set of microwave semiconductors is also referred to herein as a "power coupled" microwave semiconductor. In this case, all microwave semiconductors of the microwave plasma device may be in the group, so that all microwave semiconductors are power coupled, but depending on the application there may also be separate microwave semiconductors or other groups of mutually power coupled microwave semiconductors emitting microwaves with other powers than the above-mentioned group. Thus, depending on the application, there may be different groups, each group having more than two power-coupled microwave semiconductors, wherein the microwave power of the different groups differs in each case.

The power of the coupling preferably varies over time. This has the advantage that a complex control of the microwave treatment can be performed with a well-defined power curve.

A group of microwave semiconductors is preferably configured such that they emit microwaves of the same phase, or excite or couple in microwaves of the same phase. This group of microwave semiconductors is also referred to herein as "phase-coupled" microwave semiconductors. In this case, all microwave semiconductors of the microwave plasma device may be in this group such that all microwave semiconductors are phase-coupled to each other, but depending on the application there may also be separate microwave semiconductors or other groups of microwave semiconductors polarization-coupled to each other, which emit microwaves having a phase other than the group. Thus, depending on the application, there may be different groups, each having more than two polarization-coupled microwave semiconductors, wherein the phases of the different groups are different in each case and/or vary over time.

The microwave semiconductor is preferably configured to emit microwaves having a linear or circular polarization, or it is configured and positioned such that the microwaves coupled in for microwave generation are linearly or circularly polarized. In this case, a group of microwave semiconductors is configured in such a way that they emit microwaves of the same polarization or excite or couple microwaves of the same polarization. This group of microwave semiconductors is also referred to herein as "polarization coupled" microwave semiconductors. In this case all microwave semiconductors of the microwave plasma device may be in the group such that all microwave semiconductors are coupled to each other, but depending on the application there may also be separate microwave semiconductors or other groups of mutually polarization-coupled microwave semiconductors emitting microwaves with other polarizations than the group. Thus, depending on the application, there may be different groups, each having more than two polarization-coupled microwave semiconductors, wherein the polarizations of the different groups are different in each case and/or vary over time.

Microwave devices are particularly suitable for use in plasma sources, but are also suitable for non-plasma related applications, particularly in the food, chemical or pharmaceutical industries.

It is noted that the indefinite article "a" or "an" may also comprise a plurality, and should be understood as meaning "at least one". However, singular is not explicitly excluded.

Drawings

Examples of preferred embodiments of microwave plasma devices according to the invention are schematically shown in the drawings.

Fig. 1 shows a top view of the preferred embodiment.

Fig. 2 shows a sectional view in side view of the embodiment according to fig. 1.

Fig. 3 shows a top view of a further preferred embodiment.

Fig. 4 shows a sectional view in side view of the embodiment according to fig. 3.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

All components of the device according to the invention may also be present more than once. Only those components necessary or helpful in understanding the present invention are shown. Thus, for example, no further components and embodiments thereof known to those skilled in the art are shown in the drawings; such components are, for example, gas inlets and outlets, pumps, pressure control units, controllers, material locks or corresponding components.

Fig. 1 shows a diagram of a preferred embodiment of a microwave plasma device from above. In the center, a process space 2 is shown, which is designed as a cylinder made of metal (e.g. brass, copper or aluminum), has a bottom and a cover, and can be used as a resonator. Although an embodiment of the processing space 2 in the form of a cylindrical resonator is particularly preferred, depending on the application, spherical resonators, elliptical resonators, rectangular resonators or a hybrid form thereof may also provide advantages.

Four microwave semiconductors 1 are arranged equidistantly around the process space 2. The number of microwave semiconductors 1 can be increased and decreased, if necessary. A bias electrode 3 can be seen in the center of the process space 2. The processing space 2 and the two microwave semiconductors 1 are transected by a section a-a at the center.

For purposes of better overview, components represented by dashed lines in the figures are not specified in detail herein. They are explained in more detail in the context of fig. 2.

Fig. 2 shows a section a-a in a side view according to the embodiment of fig. 1. It can be seen here that the input coupling of the microwaves from the microwave semiconductor 1 is in each case realized by a rod antenna 4, which rod antenna 4 is configured, for example, as an extension of the inner conductor of a coaxial output coupling arrangement which is coupled out of the microwave semiconductor 1 into the process space 2.

The dielectric wall element 6 (for example, a quartz glass cylinder) divides the process space 2 in such a way that, depending on the application, a corresponding gas atmosphere having a desired gas composition and pressure can be adjusted in the region located inside the dielectric wall element 6. The dielectric wall elements 6 can be constructed as complete partition walls or as windows in non-dielectric walls.

The sample-receiving unit 5 is located below the bias electrode 3, wherein the bias electrode 3 and the sample-receiving unit 5 can be designed to be movable along the cylindrical axis of the process space 2, in other words, upward and downward in the figure. A bias voltage may be applied between the bias electrode 3 and the sample receiving element 5 to direct plasma species (e.g. ions or electrons) onto the sample receiving element 5.

Fig. 3 shows a diagram of a further preferred embodiment of the microwave plasma device from above. As in fig. 1, four microwave semiconductors 1 are again arranged equidistantly around the process space 2. The bias electrode 3 can again be seen in the center of the process space 2. In contrast to fig. 1, the coupling elements 7 are shown in this figure, each at the location of the microwave semiconductor 1. The processing space 2 and the two microwave semiconductors 1 are intersected by a section B-B at the center.

Fig. 4 shows a section B-B in a side view of the embodiment according to fig. 3. As in the preceding examples, the microwave from the microwave semiconductor 1 is in each case coupled in via a rod antenna 4. In contrast to fig. 2, the microwaves are coupled from the microwave semiconductor 1 via the rod antenna 4 into the coupling element 7. Here, the coupling element 7 is configured as a rectangular waveguide element, and converts the coaxial microwave feed into a rectangular wave guided wave. Which is coupled into the process space 2 via a coupling slot 8. In a variant of this embodiment, there may be more or fewer microwave feeds consisting of microwave semiconductor 1, rod antenna 4, coupling element 7 and coupling slot 8.

In the figure, the coupling point 7 for coupling microwaves into the process space or microwave feed is located in a plane. Arrangements of coupling points or microwave feeds in multiple planes are also possible. In this way, a higher power or better uniformity of the radiated microwave radiation (e.g. for plasma) may be obtained.

For example, the preferred embodiments of fig. 1 and 2 or 3 and 4 represent a microwave plasma device for generating plasma. As mentioned above, the dielectric wall element 6 may be a quartz glass container which separates an internal plasma chamber which serves as a space for performing plasma treatment. Desired process conditions, such as gas composition, gas pressure, or microwave power, may be set in the plasma chamber.

Fig. 1 and 2 show a preferred way of coupling the microwaves into the process space 2, i.e. directly in-coupling from a coaxial outlet. The inner conductor of the microwave semiconductor 1 is coupled into the process space 2 in the form of a rod antenna 4 in the case shown.

Fig. 3 and 4 show other preferred ways of coupling the microwaves into the processing space 2, i.e. indirect input coupling from a coaxial outlet.

Here, the microwaves are converted into any type of waveguide wave by a coupling element 7 (e.g., a rectangular waveguide or a circular waveguide), and then, are fed to the processing space through a coupling slot 8. The way in which the power is coupled can thus be adapted to the structure of the processing space 2.

The input coupling of microwaves via the various microwave semiconductors 1 is preferably performed at the same frequency and phase, but may also be adapted to the input coupling of microwave plasma devices if desired.

An advantage of embodiments according to the invention is that circulators and tuning elements in the feeding of microwaves to the processing space may, but need not, be omitted.

The microwaves may be coupled in a pulsed or non-pulsed manner as desired. The power may vary between different power levels, i.e. it does not have to vary between 0 and 100%, but may also be pulsed, e.g. between 20 and 80%.

The polarization (e.g. linear, circular or elliptical) of the microwaves of the respective microwave semiconductors or microwave feeds may be implemented so as to be identical. The polarization of the different microwave semiconductors may also be chosen to be different, or time varying, depending on the application.

The various input coupling options (pulse, polarization, phase or frequency ratio) may also be combined as desired.

List of reference numerals

1 microwave semiconductor

2 treatment space

3 bias electrode

4-rod antenna

5 sample receiving Unit

6 dielectric wall element

7 coupling element

8 coupling groove