JPH11330049A - Plasma processing method and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing method and a device which can generate uniform plasma and moreover which is superior in power efficiency. SOLUTION: A prescribed gas is introduced into a vacuum container 1 from a gas supply device 2. Gas is evacuated by a pump 3 as an evacuating device. The vacuum container 1 is kept to a prescribed pressure, and an antenna high frequency power source 4 supplies high frequency power of 100 MHz to a planar antenna 5. Thus, plasma is generated in the vacuum container 1, when an electromagnetic wave is radiated into the vacuum container 1 via a dielectric window 6. Then, a uniform processing is realized by a conductor board 12 for executing the plasma processing of etching, deposition and surface reforming on a substrate 8 installed on an electrode 7 in a state, where the capacity connection of the planar antenna 5 and plasma is weakened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing method and apparatus for dry etching, sputtering, plasma CVD and the like used in the manufacture of electronic devices and micromachines such as semiconductors, and more particularly to the use of plasma excited by electromagnetic waves. The present invention relates to a plasma processing method and apparatus.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 8-83696 describes the importance of using high-density plasma in order to cope with miniaturization of electronic devices such as semiconductors. Low electron temperature plasma, which has high electron temperature and low electron temperature, has attracted attention.

[0003] Strongly negative gases such as Cl ₂ and SF ₆
In other words, when a gas that easily generates negative ions is turned into plasma, when the electron temperature is about 3 eV or less, a larger amount of negative ions is generated than when the electron temperature is high. Utilizing this phenomenon, it is possible to prevent an abnormal etching shape called a notch, which is caused by the accumulation of positive charges at the bottom of the fine pattern due to excessive incidence of positive ions. It can be carried out.

Further, CxFy and CxHy generally used when etching an insulating film such as a silicon oxide film are used.
When a gas containing carbon and fluorine such as Fz (x, y, and z are natural numbers) is plasmatized, when the electron temperature becomes about 3 eV or less, the decomposition of the gas is suppressed as compared with the case where the electron temperature is high. Generation of atoms, F radicals, and the like is suppressed. Since F atoms, F radicals, and the like have a high silicon etching rate, the lower the electron temperature, the higher the etching selectivity with respect to silicon.

[0005] When the electron temperature becomes 3 eV or less, the ion temperature also drops, so that ion damage to the substrate in plasma CVD can be reduced.

A technique that can generate plasma having a low electron temperature has been attracting attention at present from a plasma source using electromagnetic waves. This generates plasma by radiating electromagnetic waves into a vacuum vessel, and various forms of antennas and dielectric windows for radiating electromagnetic waves are used.

FIG. 4 is a sectional view of an etching apparatus equipped with a flat antenna type plasma source which has already been proposed. In FIG. 4, a gas supply device 2 is provided in a vacuum vessel 1.
Pump 3 as an exhaust device while introducing a predetermined gas from
While maintaining the inside of the vacuum vessel 1 at a predetermined pressure, by the high frequency power supply for antenna 4 to 50 to 300M.
When high-frequency power of 1 Hz is supplied to the flat plate antenna 5 on the dielectric window 6, plasma is generated in the vacuum vessel 1 and etching, deposition, surface modification, and the like are performed on the substrate 8 placed on the electrode 7. Plasma treatment can be performed. At this time, as shown in FIG. 4, by supplying high-frequency power to the electrode 7 from the electrode high-frequency power supply 9, the ion energy reaching the substrate 8 can be controlled.

[0008]

However, in the conventional method shown in FIG. 4, power efficiency must be sacrificed when importance is placed on plasma uniformity, and conversely, when importance is placed on power efficiency, plasma uniformity is sacrificed. There was a problem that it had to be done.

FIG. 5 shows the outer dimensions (diameter) of the (disk-shaped) flat antenna 5 when the frequency of the electromagnetic wave is 100 MHz.
Is changed to 100 mm to 300 mm, and the ion saturation current density is measured at a position of 20 mm immediately above the substrate 8. Plasma generation conditions are as follows: gas type and gas flow rate are Cl ₂ = 100 sccm, pressure is 1 Pa, and high-frequency power is 1 kW. FIG. 5 shows that when the outer dimension (diameter) of the flat plate antenna 5 is small, high-density plasma is obtained, but the plasma density at the center is higher than that at the periphery, and the uniformity of the plasma is poor. . Also, when the outer dimensions (diameter) of the flat antenna 5 are large, the plasma uniformity is excellent, but the plasma density is significantly lower than when the outer dimensions (diameter) of the flat antenna are small.

Hereinafter, the cause of such a phenomenon will be considered. When the outer dimension (diameter) of the flat plate antenna 5 is small, the largest electric field is generated near the center of the dielectric window 6, so that the plasma density in the center is highest. Since a high-frequency voltage is applied to the flat plate antenna 5, the flat plate antenna 5 and the plasma are capacitively coupled via the dielectric window 6, and the central portion of the dielectric window 6 (directly below the flat plate antenna 5). , A so-called negative self-bias voltage is generated. Positive ions in the plasma collide with the dielectric window 6 due to the negative self-bias voltage, thereby etching the dielectric window 6 or heating the dielectric window 6, resulting in energy loss. The region where the self-bias voltage is generated depends on the dielectric window 6.
The energy loss is not so large because it is only in the vicinity of the central part of.

On the other hand, when the diameter of the flat antenna 5 is large, a relatively uniform electric field is generated in the vicinity of the dielectric window 6, so that the plasma density becomes uniform. Since a high-frequency voltage is applied to the flat antenna 5, a so-called negative self-bias voltage is generated in the dielectric window 6 as in the case where the diameter of the flat antenna 5 is small as described above. The area to be covered extends over a wide range of the dielectric window 6, and the positive electrode in the plasma collides with the dielectric window 6, so that the dielectric window 6 is etched or the dielectric window 6 is heated. Energy loss is relatively large. Therefore, the plasma density is lower than when the external dimensions of the flat plate antenna 5 are small. In general, since the self-bias voltage increases as the plasma density decreases, the self-bias voltage itself generated in the dielectric window 6 becomes higher than when the diameter of the flat antenna 5 is small, and as a result, the unit of the dielectric window 6 The energy loss per area is larger than when the external dimensions of the flat antenna 5 are small. That is, as the diameter of the flat antenna 5 increases, the power efficiency sharply decreases.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a plasma processing method and apparatus capable of generating uniform plasma and having excellent power efficiency.

[0013]

According to a first aspect of the present invention, there is provided a plasma processing method, wherein the inside of a vacuum vessel is evacuated while supplying gas into the vacuum vessel, and the inside of the vacuum vessel is controlled to a predetermined pressure.
A frequency of 50 MHz to 3 MHz is applied to a flat antenna substantially parallel to a substrate placed on an electrode in a vacuum vessel via a matching circuit.
By supplying high-frequency power of GHz, electromagnetic waves are radiated into the vacuum vessel through a dielectric window provided on the inner wall surface of the vacuum vessel facing the substrate, thereby generating plasma in the vacuum vessel. A plasma processing method characterized in that the substrate is processed in a state where capacitive coupling between the flat antenna and plasma is weakened by a conductor plate provided between the flat antenna and the dielectric window. Processing.

In the plasma processing method according to the first aspect of the present invention, it is preferable that the diameter or the length of the diagonal line of the flat antenna is 1/10 or less of the wavelength of the electromagnetic wave.

[0015] Preferably, the connection conductor for connecting the matching circuit and the flat antenna is desirably provided substantially along the center of the substrate and along a straight line substantially perpendicular to the substrate.

Preferably, the length of the connection conductor for connecting the matching circuit and the flat antenna is not more than 1/10 of the wavelength of the electromagnetic wave.

Preferably, the outer dimensions of the conductor plate are larger than the outer dimensions of the flat antenna.

The potential of the conductor plate may be a ground potential or a floating potential.

The plasma processing method of the first invention of the present application is a particularly effective plasma processing method when no DC magnetic field exists in the vacuum vessel.

Preferably, the frequency of the electromagnetic wave is 50 M
Hz to 300 MHz.

A plasma processing apparatus according to a second aspect of the present invention includes a vacuum container, a gas supply device for supplying gas into the vacuum container, an exhaust device for exhausting the inside of the vacuum container, and an inner wall surface of the vacuum container. A dielectric window provided on the surface facing the substrate, a flat antenna for radiating electromagnetic waves into the vacuum chamber through the dielectric window,
What is claimed is: 1. A plasma processing apparatus comprising: a high-frequency power supply capable of supplying a high-frequency power of 0 MHz to 3 GHz; a matching circuit; and an electrode for mounting a substrate in a vacuum vessel. A conductor plate is provided between the two.

In the plasma processing apparatus according to the second aspect of the present invention, it is preferable that the diameter or the length of the diagonal line of the flat antenna is 1/10 or less of the wavelength of the electromagnetic wave.

Preferably, the connecting conductor for connecting the matching circuit and the flat antenna is provided substantially along the center of the substrate and along a straight line substantially perpendicular to the substrate.

Preferably, the length of the connecting conductor for connecting the matching circuit and the flat antenna is not more than 1/10 of the wavelength of the electromagnetic wave.

Preferably, the diameter or the length of the diagonal of the conductor plate is larger than the diameter or the length of the diagonal of the flat antenna.

The potential of the conductor plate may be a ground potential or a floating potential.

The plasma processing apparatus according to the second aspect of the present invention is a plasma processing apparatus particularly effective when a vacuum vessel is not provided with a coil or a permanent magnet for applying a DC magnetic field.

Preferably, the frequency of the electromagnetic wave is 50 M
Hz to 300 MHz.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view of a plasma processing apparatus used in the first embodiment of the present invention. In FIG.
While introducing a predetermined gas from the gas supply device 2 into the vacuum vessel 1, the gas is exhausted by the pump 3 as an exhaust device,
When the high frequency power of 100 MHz is supplied to the flat antenna 5 by the high frequency power supply for antenna 4 while maintaining the inside of the vacuum vessel 1 at a predetermined pressure, the electromagnetic wave is radiated into the vacuum vessel 1 through the dielectric window 6. Plasma is generated in the vacuum vessel 1, and plasma processing such as etching, deposition, and surface modification can be performed on the substrate 8 placed on the electrode 7. An electrode high-frequency power supply 9 for supplying high-frequency power to the electrode 7 is provided so that ion energy reaching the substrate 8 can be controlled. The dielectric window 6 is provided on a surface facing the substrate 8. Further, the matching circuit 10 and the flat antenna 5
Is provided along a straight line substantially passing through the center of the substrate and substantially perpendicular to the substrate. Further, the length of the connection conductor 11 for connecting the matching circuit and the flat antenna is 150 mm (the wavelength is 3000 mm because the frequency of the electromagnetic wave is 100 MHz,
In this case, the length of the connection conductor is 1/20 of the wavelength).

The flat antenna 5 has a circular shape with a diameter of 150 mm and is provided substantially parallel to a plane parallel to the substrate 8. The electric field of the electromagnetic wave radiated into the vacuum vessel 1 is substantially perpendicular to the substrate surface. It is configured to be. Also,
A circular conductor plate 12 having a diameter of 250 mm is provided between the flat antenna 5 and the dielectric window 6.
The substrate can be processed in a state where the capacitive coupling between the plasma and the plasma is weakened. Therefore, since a so-called negative self-bias voltage is hardly generated in the dielectric window 6, the positive ions in the plasma collide with the dielectric window 6, and the dielectric window 6 is etched or the dielectric window 6 is etched. The energy loss due to heating is extremely small. Note that the potential of the conductor plate 12 is a floating potential.

The electromagnetic wave radiated from the flat antenna 5 is introduced into the vacuum chamber 1 from the periphery of the conductor plate 12 through the dielectric window 6, but can sufficiently circulate directly below the conductor plate 12. A uniform plasma can be generated. FIG. 2 shows the ion saturation current density measured at a position 20 mm directly above the substrate 8. The plasma generation condition is such that the gas type and the gas flow rate are Cl ₂ = 100 sc.
cm, pressure is 1 Pa, and high-frequency power is 1 kW. FIG.
This shows that plasma with extremely excellent uniformity was generated. Further, compared with FIG. 5, although the density of the flat antenna 5 is slightly lower than the density at the center when the outer dimension is 100 mm, a higher plasma density is obtained than when the outer dimension is 150 mm or more. You can see that it is. That is, it can be seen that in the first embodiment of the present invention, uniform plasma can be generated and plasma processing excellent in power efficiency can be performed as compared with the conventional example.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment of the present invention is different from the first embodiment of the present invention only in that the conductor plate 12 is grounded. To achieve such a configuration,
Although it has the disadvantage of increasing the complexity of the device design, it is excellent in that the capacitive coupling between the planar antenna 5 and the plasma can be more effectively weakened.

In the embodiment of the present invention described above,
Within the scope of the present invention, only some of the various variations are illustrated with respect to the shape of the vacuum vessel, the shape and arrangement of the antenna, and the shape and arrangement of the dielectric window. In applying the present invention, it goes without saying that various variations other than those exemplified here are possible. For example, in the embodiment of the present invention, the case where the flat antenna is circular has been described, but a configuration having another shape such as a polygon, an ellipse, and the like is also possible. Similarly, the case where the conductor plate is circular has been described, but a configuration with other shapes such as a polygon and an ellipse is also possible. When the flat antenna and the conductor plate are other than the same shape, the outer diameter is the length of the diagonal line, and when it is circular, the outer diameter is the diameter.

In the above-described embodiment of the present invention, the case where the outer dimensions of the flat antenna and the outer dimensions of the conductor plate are 150 mm and 250 mm has been described. The plasma density and its uniformity may be adjusted according to the shape of the vacuum vessel, the dimensions of the substrate, and the like. However,
According to our experiments, when the external dimensions of the flat antenna exceeded 1/10 of the wavelength of the electromagnetic wave, the impedance of the flat antenna was too high and it was difficult to obtain a good matching state. It is considered that the outer dimensions of the antenna are desirably 1/10 or less of the wavelength of the electromagnetic wave. Also, in order to sufficiently weaken the capacitive coupling between the flat antenna and the plasma, the outer dimensions of the conductor plate are desirably larger than the outer dimensions of the flat antenna, and preferably less than twice.

In the embodiment of the present invention described above, the connection conductor for connecting the matching circuit and the flat antenna is provided substantially along the center of the substrate and along a straight line substantially perpendicular to the substrate. Has been described,
By employing such a configuration, electromagnetic waves can be radiated into the vacuum vessel without bias. There may be cases where such a configuration cannot be taken due to restrictions on device design, but such cases are also considered to be application examples of the present invention.

In the above-described embodiment of the present invention, the case where the length of the connection conductor for connecting the matching circuit and the flat antenna is 150 mm has been described.
If the length of the connection conductor exceeds 1/10 of the wavelength of the electromagnetic wave, the impedance of the connection conductor is too high to obtain a good matching state. It is considered that it is desirable to be 1/10 or less.

Further, in the above-described embodiment of the present invention, a case where high-frequency power of 100 MHz is supplied to the antenna has been described. However, the form and frequency of the antenna are not limited to this, and a frequency of 50 MHz to 3 GHz is used. The present invention is effective in a plasma processing method and apparatus using the method. Especially, 50MHz to 300MHZ
When the frequency z is used, there is an advantage that the discharge is easily started even under a low pressure. Therefore, when the substrate is to be processed under a low pressure, a frequency in this range is desirably used.

In the embodiment of the present invention described above, the case where no DC magnetic field exists in the vacuum vessel has been described. However, when there is no DC magnetic field large enough to allow electromagnetic waves to enter the plasma, for example, The present invention is effective even when a small DC magnetic field of about several tens of gauss is used to improve the ignitability. However, the present invention is particularly effective when no DC magnetic field exists in the vacuum vessel.

[0040]

As is clear from the above description, according to the plasma processing method of the first invention of the present application, the inside of the vacuum vessel is evacuated while supplying the gas into the vacuum vessel, and the inside of the vacuum vessel is maintained at a predetermined pressure. By supplying high-frequency power having a frequency of 50 MHz to 3 GHz through a matching circuit to a flat antenna substantially parallel to a substrate mounted on an electrode in the vacuum vessel while controlling the inner wall of the vacuum vessel, A plasma processing method comprising: irradiating an electromagnetic wave into a vacuum container through a dielectric window provided on a surface facing a substrate to generate plasma in the vacuum container; and processing the substrate. Since the substrate is processed in a state where the capacitive coupling between the flat antenna and the plasma is weakened by the conductor plate provided between the flat antenna and the dielectric window, uniform plasma can be generated. And, it is possible to better plasma treatment power efficiency.

Further, according to the plasma processing apparatus of the second invention of the present application, a vacuum container, a gas supply device for supplying gas into the vacuum container, an exhaust device for exhausting the inside of the vacuum container, A dielectric window provided on a surface of the inner wall surface of the container facing the substrate, a flat antenna for radiating electromagnetic waves into the vacuum container through the dielectric window, and a flat antenna having a frequency of 50 MHz to 3 GHz. A plasma processing apparatus comprising a high-frequency power supply capable of supplying high-frequency power, a matching circuit, and an electrode for placing a substrate in a vacuum vessel, wherein a conductor is provided between the flat antenna and the dielectric window. Since the plate is provided, uniform plasma can be generated, and plasma processing with excellent power efficiency can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a plasma processing apparatus used in a first embodiment of the present invention.

FIG. 2 is a diagram showing a measurement result of an ion saturation current density in the first embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a plasma processing apparatus used in a second embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration of a plasma processing apparatus used in a conventional example.

FIG. 5 is a diagram showing a measurement result of an ion saturation current density in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Gas supply device 3 Pump 4 High frequency power supply for antenna 5 Flat antenna 6 Dielectric window 7 Electrode 8 Substrate 9 High frequency power supply for electrode 10 Matching circuit 11 Connection conductor 12 Conductor plate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05H 1/46 H05H 1/46 M (72) Inventor Matsuda 1006 Ojidoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72 Inventor Shozo Watanabe 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (18)

[Claims] 1. While evacuating the inside of a vacuum vessel while supplying gas into the vacuum vessel and controlling the inside of the vacuum vessel to a predetermined pressure,
A frequency of 50 MHz to 3 MHz is applied to a flat antenna substantially parallel to a substrate placed on an electrode in a vacuum vessel via a matching circuit.
By supplying high-frequency power of GHz, electromagnetic waves are radiated into the vacuum vessel through a dielectric window provided on the inner wall surface of the vacuum vessel facing the substrate, thereby generating plasma in the vacuum vessel. A plasma processing method characterized in that the substrate is processed in a state where capacitive coupling between the flat antenna and plasma is weakened by a conductor plate provided between the flat antenna and the dielectric window. A plasma processing method characterized by performing processing. 2. The plasma processing method according to claim 1, wherein the diameter or the length of the diagonal line of the flat antenna is 1/10 or less of the wavelength of the electromagnetic wave. 3. A connection conductor for connecting a matching circuit and a flat antenna, wherein the connection conductor is provided substantially along the center of the substrate and along a straight line substantially perpendicular to the substrate. 2. The plasma processing method according to 1. 4. The plasma processing method according to claim 1, wherein a length of a connecting conductor for connecting the matching circuit and the flat antenna is 1/10 or less of a wavelength of the electromagnetic wave. 5. The plasma processing method according to claim 1, wherein a diameter or a diagonal length of the conductor plate is larger than a diameter or a diagonal length of the flat antenna. 6. The plasma processing method according to claim 1, wherein the potential of the conductive plate is a ground potential. 7. The plasma processing method according to claim 1, wherein the potential of the conductive plate is a floating potential. 8. The plasma processing method according to claim 1, wherein no DC magnetic field exists in the vacuum vessel. 9. An electromagnetic wave having a frequency of 50 MHz to 300 MHz.
2. The plasma processing method according to claim 1, wherein the frequency is MHz. 10. A vacuum container, a gas supply device for supplying a gas into the vacuum container, an exhaust device for exhausting the inside of the vacuum container, and an inner wall surface of the vacuum container facing a substrate. A matched dielectric window, a flat antenna for radiating electromagnetic waves into the vacuum vessel through the dielectric window, and a high-frequency power supply capable of supplying high-frequency power having a frequency of 50 MHz to 3 GHz to the flat antenna. What is claimed is: 1. A plasma processing apparatus comprising: a circuit; and an electrode for mounting a substrate in a vacuum vessel, wherein a conductor plate is provided between a flat antenna and a dielectric window. 11. The plasma processing apparatus according to claim 10, wherein the diameter or the length of the diagonal line of the flat antenna is 1/10 or less of the wavelength of the electromagnetic wave. 12. A connection conductor for connecting a matching circuit and a planar antenna is provided along a straight line substantially passing through the center of the substrate and substantially perpendicular to the substrate. A plasma processing apparatus according to claim 10. 13. The plasma processing apparatus according to claim 10, wherein a length of a connection conductor for connecting the matching circuit and the flat antenna is 1/10 or less of a wavelength of the electromagnetic wave. 14. The plasma processing apparatus according to claim 10, wherein the diameter or the diagonal length of the conductor plate is larger than the diameter or the diagonal length of the flat antenna. 15. The plasma processing apparatus according to claim 10, wherein the potential of the conductive plate is a ground potential. 16. The plasma processing apparatus according to claim 10, wherein the potential of the conductor plate is a floating potential. 17. The plasma processing apparatus according to claim 10, wherein a coil or a permanent magnet for applying a DC magnetic field is not provided in the vacuum vessel. 18. An electromagnetic wave having a frequency of 50 MHz to 30 MHz.
The plasma processing apparatus according to claim 10, wherein the frequency is 0 MHz.