KR100678696B1 - Magnetically enhanced plasma source having ferrite core assembly for forming toroidal plasma - Google Patents

Abstract

A magnetically enhanced plasma source is provided to more uniformly maintain plasma of high density by forming toroidal plasma in a plasma reaction chamber. A plasma source includes a plasma reaction chamber(10) having a susceptor(17) loaded with a substrate, and a ferrite core assembly(20) disposed on an outer ceiling of the plasma reaction chamber for forming toroidal plasma in the plasma reaction chamber. The ferrite core assembly has at least two annular ferrite cores(21,22) concentrically disposed, plural bar-type ferrite cores(23) each wound with an induction coil(24), and a first power supply source(30) supplying an AC power to induce plasma on the induction coil.

Description

MAGNETICALLY ENHANCED PLASMA SOURCE HAVING FERRITE CORE ASSEMBLY FOR FORMING TOROIDAL PLASMA}

In order to more fully understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

1 is a perspective view showing the appearance of a plasma reaction chamber according to a preferred embodiment of the present invention.

2 is a cross-sectional view of the plasma reaction chamber of FIG. 1.

3 is a view illustrating the annular plasma as viewed from the ceiling inside the plasma reaction chamber.

4 is a partial cross-sectional view of a plasma reaction chamber showing an example in which a gas inlet is expanded.

5 is a cross-sectional view of a plasma reaction chamber showing an example with a dual bias power source.

6 is a perspective view of a plasma reaction chamber in which a ferrite core assembly is embedded.

FIG. 7 is a cross-sectional view of the plasma reaction chamber of FIG. 6.

8 is a partial cross-sectional view of a plasma reaction chamber showing an example in which a gas inlet is expanded.

9 is a partial cross-sectional view of the plasma reaction chamber showing an example of installing a gas distribution plate below the gas inlet.

FIG. 10 is a plan view of a plasma reaction chamber in which a ferrite core assembly in which three annular ferrite cores are arranged concentrically is installed.

11 and 12 are partial cross-sectional views of the plasma reaction chamber of FIG. 10. FIG. 11 is a diagram illustrating a case in which the magnetic field induction directions are the same in FIG.

* Description of the symbols for the main parts of the drawings *

10: plasma reaction chamber 17: susceptor

19: vacuum pump 20: ferrite core assembly

30, 32, 36: power source

TECHNICAL FIELD The present invention relates to a plasma source for processing a semiconductor substrate, and more particularly, to a magnetically strengthened plasma source that enhances plasma density and uniformity by forming an annular plasma inside a process chamber using a ferrite core assembly.

Due to various factors such as ultra miniaturization of semiconductor devices, increase in substrate size, and the emergence of new materials to be treated, further improvements in substrate processing technologies are required in the semiconductor manufacturing process. In particular, in the field of dry etching process and physical / chemical vapor deposition, semiconductor technology using plasma continues to develop technologies for plasma sources that can uniformly obtain high-density plasma using magnetic fields. .

In general, lowering the pressure of the plasma reaction tube increases the average free distance of ions, which increases the energy of ions colliding with the wafer and reduces scattering between the ions, which is known to be advantageous for anisotropic etching. However, when the pressure is lowered, the electrons also increase the average free distance, which reduces the collision with neutral atoms, making it difficult to maintain the plasma state. Therefore, a technique has been proposed to maintain the plasma at low pressure by increasing the frequency of collision with the neutral atoms by increasing the moving distance of electrons by using the magnetic field to maintain the plasma at low pressure.

In addition, as the substrate size increases, the size of the plasma reaction chamber in which the substrate is processed also increases, in which case it is difficult to uniformly distribute the plasma inside the plasma reaction chamber. Therefore, techniques for using a magnetic field to maintain a uniform plasma density inside the plasma reaction chamber have been proposed.

Techniques using permanent magnets have been proposed to form a uniform plasma inside the plasma reaction chamber. For example, techniques have been proposed, such as mounting a permanent magnet on top of a reaction tube, or rotating on top. Alternatively, the substrate may be rotated to allow a relatively uniform substrate treatment.

In the case of using permanent magnets, the uniformity can be improved relatively simply because they are small in size, simple to install, and do not require external power supply. However, the uniformity of the magnetic field is not good and the strength of the magnetic field is not controllable. When rotating a substrate or rotating a permanent magnet, there exists a burden for constructing a rotating structure.

Accordingly, an object of the present invention is to provide a self-reinforced plasma source having a ferrite core assembly for forming an annular plasma in the reaction chamber to more uniformly generate and maintain a high density plasma in the plasma reaction chamber.

One aspect of the present invention for achieving the above technical problem relates to a self-enhanced plasma source. The self-enhanced plasma source of the present invention comprises: a hollow plasma reaction chamber having a susceptor on which a substrate is placed; A ferrite core assembly disposed on an outer ceiling of the plasma reaction chamber, the ferrite core assembly configured to form an annular plasma inside the plasma reaction chamber, the ferrite core assembly comprising: two or more annular sizes of different sizes that are planarly arranged to have a concentric structure; Ferrite cores; And a plurality of rod-like ferrite cores having both ends connected to two neighboring annular ferrite cores and disposed radially as a whole, and each of which an induction coil is wound. A magnetic field focused on a plurality of rod-like ferrite cores, including a first power source providing an alternating current power source of a first frequency for plasma induction with an induction coil, is introduced into the plasma reaction chamber through two adjacent annular ferrite cores. An annular plasma is formed inside the plasma reaction chamber by a radially induced, radially induced magnetic field and thereby a secondary induced electric field.

Preferably, at least one gas inlet for injecting process gas into the plasma reaction chamber, the gas inlet is arranged in a region between adjacent annular ferrite cores.

Preferably, the first frequency has a 10khz ~ 100MHz.

Preferably, the gas inlet for injecting the process gas into the plasma reaction chamber, the gas inlet is a plurality of first gas inlet disposed in the region between the adjacent annular ferrite core and the second gas inlet disposed in the chamber ceiling center Include.

Preferably, the first and second gas inlets are inputted separately from different types of process gases.

Preferably, the ceiling structure of the plasma reaction chamber is structured such that there is a high step between two adjacent annular ferrite cores.

Preferably, a gas distribution plate is installed below the gas inlet.

Preferably, the plurality of induction coils are connected to the first power source in any one of a series, parallel, or a series and a parallel mixing scheme.

Advantageously, a second power supply provides a second frequency to said susceptor.

Preferably, it includes a second power source for providing a second frequency to the susceptor and a third power source for providing a third frequency different from the second frequency.

Preferably, the second frequency is 50khz ~ 2MHz, the power is 500W ~ 5kW, the third frequency is 10khz ~ 60MHz, the power is 500W ~ 5kW.

Preferably, the ceiling of the plasma reaction chamber includes one or more insulator regions that form electrical discontinuities.

Preferably, the ceiling of the plasma reaction chamber includes one or more insulator regions that form an electrical discontinuity with the conductive metal.

DETAILED DESCRIPTION In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the embodiments of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings. In understanding the drawings, it should be noted that like parts are intended to be represented by the same reference numerals as much as possible. And detailed description of known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention is omitted.

(Example)

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a self-enhanced plasma source having a ferrite core assembly for forming an annular plasma of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view showing the appearance of a plasma reaction chamber according to a preferred embodiment of the present invention, Figure 2 is a cross-sectional view of the plasma reaction chamber of FIG. 3 is a view illustrating the annular plasma as viewed from the ceiling inside the plasma reaction chamber.

1 and 2, the plasma reaction chamber 10 is provided with a susceptor 17 on which a substrate 8 is placed, and a vacuum pump 34 is provided at the exhaust port 18 of the chamber 10. Connected. The outer ceiling 12 of the plasma reaction chamber 10 is provided with a ferrite core assembly 20. The ferrite core assembly 20 is structured to form an annular plasma inside the plasma reaction chamber 10 as described below.

Specifically, the ferrite core assembly 20 has two or more annular ferrite cores 21 and 22 of different sizes arranged in a plane to have a concentric structure. In addition, both ends are connected to two adjacent annular ferrite cores 21 and 22 and are disposed radially as a whole, and each includes a plurality of rod-like ferrite cores 23 in which an induction coil 24 is wound. In this embodiment, an example in which two annular ferrite cores 21 and 22 and eight rod ferrite cores 23 are assembled is described. However, those skilled in the art will appreciate that the ferrite core assembly 20 can be constructed using two or more annular ferrite cores and a larger number of rod ferrite cores, as described below. will be.

Induction coils 23 respectively wound around the plurality of rod-shaped ferrite cores 23 are connected to the first power source 30 to receive AC power for plasma induction. Although the plurality of induction coils 23 are connected in series, they are connected to the first power source 30 in any one of parallel or in series and parallel mixing. The first frequency provided from the first power source 30 may be selected in the range of approximately 10 khz to 100 MHz. However, this is not limitative and other ranges of frequencies may be chosen. As a general technical matter, a matcher (not shown) for impedance matching is connected between the first power supply 30 and the plurality of induction coils 23.

Since the ferrite core assembly 20 configured as described above is installed in the outer ceiling 12 of the plasma reaction chamber 10, the magnetic field 15 focused on the plurality of rod-like ferrite cores 23 is adjacent to two annular ferrite cores. Radial 15 is guided into the plasma reaction chamber 10 through the 21 and 22. Reference numerals 6a and 6b in the drawings illustrate the direction of the secondary electric field induced by the magnetic field 15.

As shown in FIG. 3 by the radially induced magnetic field 15 and by the secondary electric fields 6a and 6b induced by it, an annular plasma 2 is formed inside the plasma reaction chamber 10 so that The plasma is generated and maintained more uniformly. Therefore, the target substrate processing can be finely processed more precisely and uniformly. Such a plasma source of the present invention can be used in various plasma processing processes for processing semiconductor substrates such as, for example, a vapor deposition process or an etching process.

Meanwhile, one or more gas inlets 16 are installed on the ceiling of the process chamber 10 to inject process gas into the plasma reaction chamber 10. Preferably, the gas inlet 16 is arranged in the region 14 between the two annular ferrite cores 21, 22. Therefore, since the gas injected into the plasma reaction chamber 10 is injected into a portion where the magnetic field 15 is strongly concentrated, plasma generation is more actively performed.

4 is a partial cross-sectional view of a plasma reaction chamber showing an example in which a gas inlet is expanded.

Referring to FIG. 4, a first gas inlet 16 and a second gas inlet 19 may be provided to inject process gas into the plasma reaction chamber 10. The first gas inlet 16 is arranged in the region 14 between the annular ferrite cores 21, 22 adjacent to each other, and the second gas inlet 19 is arranged in the center of the chamber ceiling 12. The same process gas may be input to the first and second gas inlets 16 and 19, respectively, or different kinds of process gases may be input. For example, a carrier gas may be input to the first gas inlet 16, and a process gas may be input to the second gas inlet 19.

Again, referring to FIG. 2, the susceptor 17 installed inside the plasma reaction chamber 10 is electrically connected to a second power supply 32 that provides a bias power at a second frequency. The second frequency provided from the second power source 32 may be selected in the range of 50 khz to 2 MHz, and the power to 500 W to 5 kW. As such, the susceptor 17 may be configured in a single bias manner, but as illustrated in FIG. 5, a double bias scheme is also possible. In a double bias scheme, a third power source 36 providing a bias power source of a third frequency is electrically connected to the susceptor 17. Here, the third frequency may be selected from the range of 10khz ~ 60MHz, the power 500W ~ 5kW.

The ceiling 12 of the plasma reaction chamber 10 may include one or more dielectric regions that form an electrical discontinuity with the conductive metal. The area of conductive metal is connected to ground. The insulator region may be provided on a surface where the ferrite core is in contact, or the ceiling may be entirely composed of an insulator.

6 is a perspective view of a plasma reaction chamber in which a ferrite core assembly is embedded, and FIG. 7 is a cross-sectional view of the plasma reaction chamber of FIG. 6.

As shown in FIGS. 6 and 7, the ceiling 12 of the plasma reaction chamber 10 is structured to have a high step between two adjacent annular ferrite cores 21, 22. That is, the annular embedding grooves 40 and 42 are formed such that the annular ferrite cores 21 and 22 are embedded in the ceiling 12, and the region 14 between the embedding grooves 40 and 42 is formed from the ceiling 12. It is formed to have the same plane height.

Here, a plurality of gas inlets 16 are provided in the region 14 between the buried grooves 40, 42. Alternatively, as shown in FIG. 8, the first gas inlet 16 and the second gas inlet 19 may be provided to inject the process gas into the plasma reaction chamber 10. The first gas inlet 16 is arranged in the region 14 between the buried grooves 40, 42, and the second gas inlet 19 is arranged in the center of the chamber ceiling 12. The same process gas may be input to the first and second gas inlets 16 and 19, respectively, or different kinds of process gases may be input. For example, a carrier gas may be input to the first gas inlet 16, and a process gas may be input to the second gas inlet 19. And, in order to obtain a more uniform flow of gas, as shown in FIG. 9, gas distribution plates 44 and 46 may be installed below the gas inlets 16 and 19.

The ferrite core assembly 20 of the present invention as described above to form an annular plasma in the plasma reaction chamber 10. This function of ferrite core assembly 20 can further expand its size by increasing the number of annular ferrite cores in the basic concentric circles.

FIG. 10 is a plan view of a plasma reaction chamber in which a ferrite core assembly in which three annular ferrite cores are arranged concentrically is installed.

Referring to FIG. 10, a ferrite core assembly 60 is installed on the ceiling 52 of the plasma reaction chamber 50. The ferrite core assembly 60 has three annular ferrite cores 61, 62, 63 of different sizes arranged in a plane to have a concentric structure. In addition, both ends are connected to two neighboring annular ferrite cores 61, 62, 62, 63, and are disposed radially as a whole, and a plurality of rod-shaped ferrite cores 64, 65, each of which the induction coils 66, 67 are wound. ). Here, the rod-like ferrite core 64 disposed on the outside and the rod-like ferrite core 65 disposed on the inside are preferably arranged to be staggered with each other. A plurality of gas inlets 56 may be formed between two adjacent annular ferrite cores 61, 62, 62, 63, and may be additionally configured in the center of the ceiling 52.

11 and 12 are partial cross-sectional views of the plasma reaction chamber of FIG. 10. FIG. 11 is a diagram illustrating a case in which the magnetic field induction directions are the same in FIG.

11 and 12, the winding direction or the current direction of the induction coil 66 wound around the outer bar ferrite core 64 and the induction coil 67 wound around the inner bar ferrite core 65 is illustrated. By controlling the direction of the outer magnetic field 55a and the direction of the inner magnetic field 55b, thereby controlling the directions 6a, 6b, 6a ', 6b' of the induced electric field accordingly or differently. Density, uniformity and the like can be controlled.

As described above, the present invention has been described with reference to the embodiments shown in the drawings, but this is merely exemplary, and those skilled in the art to which the present invention pertains have various modifications and equivalent embodiments. You can see that it is possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the self-reinforced plasma source having a ferrite core assembly for forming the annular plasma of the present invention as described above, by forming the annular plasma inside the plasma reaction chamber, it is possible to generate and maintain a high density plasma more uniformly. In addition, since the configuration of the ferrite core assembly for obtaining the annular plasma is simple and easy to install, the configuration and maintenance efficiency of the plasma processing equipment can be improved.

Claims (13)

A hollow plasma reaction chamber having a susceptor on which the substrate is placed; A ferrite core assembly disposed on the outer ceiling of the plasma reaction chamber and structured to form an annular plasma inside the plasma reaction chamber, The ferrite core assembly is: Two or more annular ferrite cores of different sizes arranged in a plane to have a concentric structure; And A plurality of rod-shaped ferrite cores having both ends connected to two adjacent annular ferrite cores disposed radially as a whole and each of which an induction coil is wound; A first power source providing an AC power source of a first frequency for plasma induction to the induction coil, The magnetic field focused on a plurality of rod-like ferrite cores is radially induced into the plasma reaction chamber through two adjacent annular ferrite cores, and inside the plasma reaction chamber by the radially induced magnetic field and the secondary induced electric field. A self-enhanced plasma source in which an annular plasma is formed. 2. The self-enhanced plasma source of claim 1 wherein one or more gas inlets for injecting process gas into the plasma reaction chamber, wherein the gas inlets are disposed between regions of adjacent annular ferrite cores. The self-enhanced plasma source of claim 1 wherein the first frequency has a 10 kHz to 100 MHz. The gas inlet for injecting the process gas into the plasma reaction chamber, the gas inlet is a plurality of first gas inlet disposed in the region between the adjacent annular ferrite core and the second in the chamber ceiling Self-enhanced plasma source comprising a gas inlet. The self-enhanced plasma source of claim 4, wherein the first and second gas inlets are separately inputted with different kinds of process gases. 6. The self-enhanced plasma source according to any one of claims 2 to 5, wherein the ceiling structure of the plasma reaction chamber is structured such that there is a high step between two adjacent annular ferrite cores. 7. The self-enhanced plasma source of claim 6 wherein a gas distribution plate is installed below the gas inlet. The self-enhanced plasma source of claim 1 wherein the plurality of induction coils are connected to the first power source in any one of series, parallel, or series and parallel mixing. The self-enhanced plasma source of claim 1 comprising a second power source providing a second frequency to the susceptor. The self-enhanced plasma source of claim 1 comprising a second power source providing a second frequency to the susceptor and a third power source providing a third frequency different from the second frequency. 11. The method of claim 9 or 10, wherein the second frequency has a second frequency of 50khz ~ 2MHz, power of 500W ~ 5kW, the third frequency of 10khz ~ 60MHz, power of 500W ~ 5kW Having a self-enhanced plasma source. The self-enhanced plasma source of claim 1 wherein the ceiling of the plasma reaction chamber includes one or more insulator regions that form electrical discontinuities. The self-enhanced plasma source of claim 1 wherein the ceiling of the plasma reaction chamber comprises one or more insulator regions forming electrical discontinuity with the conductive metal.

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