JP3949405B2 - Plasma processing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to plasma processing such as dry etching, and more particularly to a high frequency induction type plasma processing method and apparatus.
[0002]
[Prior art]
In recent years, in response to the miniaturization of semiconductor elements and liquid crystal driving elements, it is required to realize high aspect ratio processing in dry etching technology and high aspect ratio embedding in plasma CVD technology. Therefore, it is required to perform plasma processing at a higher vacuum.
[0003]
For example, in the case of dry etching, if high-density plasma is generated in a high vacuum, the probability of ions colliding with neutral gas particles in the ion sheath formed on the surface of the substrate to be processed is reduced. Since the directivity is aligned toward the substrate to be processed and the degree of ionization is high, the ratio of the incident particle flux of ions to the neutral radical that reaches the substrate to be processed increases. Therefore, the etching anisotropy is increased and processing with a high aspect ratio becomes possible.
[0004]
As one of plasma processing apparatuses capable of generating high-density plasma in a high vacuum in this way, a high-frequency induction method for generating plasma by introducing electromagnetic waves into a vacuum vessel by applying a high-frequency voltage to a coil or an antenna. There is a plasma processing apparatus. This type of plasma processing apparatus generates a high-frequency magnetic field in a vacuum vessel, generates an induction magnetic field in the vacuum vessel by the high-frequency magnetic field, accelerates electrons, and generates plasma, so that the coil current can be increased. Thus, high-density plasma can be generated even in a high vacuum, and a sufficient processing speed can be obtained.
[0005]
An example of a conventional high-frequency induction plasma processing apparatus will be described with reference to FIG. In FIG. 3, while evacuating the inside of the vacuum vessel 21 by the evacuating means 22, an appropriate gas is introduced by the gas introducing means 23 to keep the inside of the vacuum vessel 21 at an appropriate pressure, and the coil or antenna 25 is connected to the coil or antenna 25. When a high frequency power is applied by a high frequency power source 26, electromagnetic waves are introduced into the vacuum vessel 21 through the dielectric plate 24 to generate plasma, and etching, deposition, and surface modification are performed on the substrate 28 on the electrode 27. Plasma processing such as quality can be performed. At this time, the ion energy reaching the substrate 28 can be controlled by applying a high frequency voltage to the electrode 27 from the high frequency power supply 29 for the electrode.
[0006]
Reference numeral 30 denotes a heater for heating the dielectric plate, which prevents the reaction product from adhering to the dielectric plate 24 and also has an effect of preventing the etching of the dielectric plate 24 by plasma. As shown in FIG. 31 are arranged in a uniform distribution so that the overall shape is a lattice. In this heater 30, the heater opening ratio, which is the ratio occupied by portions other than the heating wire 31, is generally 80% to 85%, which is uniform over the entire heater surface.
[0007]
[Problems to be solved by the invention]
However, in recent years, more uniform plasma processing has been required due to miniaturization of devices. In particular, in liquid crystal applications and the like, a wide and highly uniform plasma process has been required due to the increase in size of the substrate to be processed.
[0008]
By the way, the shape of the coil or antenna 25 is generally circular when viewed from above, and in the conventional configuration shown in FIGS. 3 and 4, the arrangement pattern of the heating wires 31 of the heater 30 for heating the dielectric plate is a lattice pattern. Therefore, it has been found that the angle at which the coil 25 and the heating wire 31 intersect changes, so that there is a problem that uniform plasma cannot be obtained.
[0009]
Further, since the magnetic field generated from the coil or antenna 25 is usually strongest at the outer peripheral portion, the aperture ratio of the outer peripheral portion has the greatest influence on the plasma density even in the pattern of the heating wire 31 of the heater 30 for heating the dielectric plate. However, in the configuration of FIGS. 3 and 4, it has also been found that there is a problem in that the efficiency deteriorates because the heating wires 31 are arranged in a uniform distribution on the entire surface of the heater.
[0010]
As a specific example, as a result of measuring the electron density at 48 measurement points on the substrate to be processed 28 using the heater 30 in which the heating wires 31 are arranged in a grid pattern with an aperture ratio of 80%, The average value was Isat = 2.41 mA / cm ² , and the variation in electron density showing uniformity at 48 points was ± 24.1%. The conditions at this time are as follows: a 680 × 880 mm rectangular glass substrate is used as the substrate 28 to be processed, the gas used is Ar = 1000 sccm, the pressure is 2 Pa, and the high-frequency power value is 12 kW. When measurement was performed without using the heater 30 for heating the dielectric plate under the same conditions, the average value of the electron density was Isat = 3.53 mA / cm ² and the uniformity was ± 22.2%. This resulted in a loss of 31.7% and a deterioration of uniformity of 1.9%.
[0011]
In view of the above-described conventional problems, an object of the present invention is to provide a plasma processing method and apparatus capable of preventing reaction products from adhering to a dielectric plate, ensuring processing uniformity, and reducing loss. .
[0012]
[Means for Solving the Problems]
The plasma processing method of the present invention is a plasma processing method for generating a plasma by applying a high-frequency voltage to a coil or an antenna and introducing electromagnetic waves into a vacuum vessel through a plurality of divided dielectric plates to process a substrate. In which the ends of arcs having different diameters are connected in the radial direction, having a group of arcs arranged concentrically around the center of the substrate and having the same diameter intermittent in the circumferential direction. Each of the divided dielectric plates is continuously arranged , and the inner diameter is approximately half the outer diameter or diagonal length of the substrate to be processed, and the outer diameter is substantially the outer diameter or diagonal length of the substrate to be processed. Each of the divided dielectric plates is heated by a heating wire arranged so that the donut-shaped range of the ridge is smaller than other portions , and the reaction product adheres to the dielectric plates. Can prevent and coil or antenna Intersection angle of the heating wire is not changed, to obtain a uniform plasma can be performed with high uniform treatment and that the arrangement density of the heating wire portion having strong magnetic field emanating from the coil or antenna is small, Efficiency can be improved and plasma treatment can be performed with high efficiency. Note that “substantially” in the inner and outer diameters is within a range of about ± 20%.
[0015]
Further, the plasma processing apparatus of the present invention is a vacuum vessel comprising a high-frequency power source, a coil or antenna to which a high-frequency voltage is applied from the high-frequency power source, and a dielectric plate in which a wall surface facing the coil or antenna is divided into a plurality of parts. And an electrode disposed in the vacuum vessel so as to place the substrate to be processed, and a plurality of heaters for heating the dielectric plate, the heaters being arranged concentrically with the center directly above the center of the substrate. A heating wire that is provided for each dielectric plate divided by connecting ends of arcs having different diameters in a radial direction and having a group of arcs having the same diameter and being interrupted in the circumferential direction. Yes and, and heating wire inside diameter of approximately half of the outer diameter or the diagonal length of the substrate, the outer diameter or diagonal length donut-shaped range of the outer diameter almost the substrate to be processed than the other portion is obtained by arranged such that the smaller the density of arrangement Crossing angle of the coil or antenna and the heating wire is not changed, to obtain a uniform plasma can be performed with high uniform treatment, and with the arrangement density of the heating wire portion having strong magnetic field emanating from the coil or antenna is reduced by there, it is possible to improve the efficiency, Ru can be subjected to plasma treatment with high efficiency.
[0016]
In addition, when the heater opening ratio, which is the ratio of the portion other than the heating wire to the area of the entire heater, is 87% or more on average, processing can be performed with high efficiency.
[0017]
Further, when the inner diameter is approximately half of the outer diameter or diagonal length of the substrate to be processed and the outer diameter is approximately 90% or more in the donut-shaped range of the outer diameter or diagonal length of the substrate to be processed, Processing can be performed with high efficiency.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the plasma processing apparatus of the present invention will be described with reference to FIGS.
[0019]
In FIG. 1, 1 is a vacuum vessel, 2 is a dielectric plate arranged so as to constitute its ceiling wall surface, 3 prevents reaction products from adhering to the dielectric plate 2, and the dielectric plate 2 is caused by plasma. It is a heater for preventing etching. Reference numeral 4 denotes exhaust means for evacuating the inside of the vacuum vessel 1, and reference numeral 5 denotes gas introduction means for introducing an appropriate gas into the vacuum vessel 1. A coil or antenna 6 is disposed on the upper part of the dielectric plate 2 of the vacuum vessel 1 with the center as an axis, and a high frequency power source 7 for the coil or antenna is connected to the axis of the coil or antenna 6. . Reference numeral 8 denotes an electrode disposed in the lower part of the vacuum vessel 1 and is connected to a high frequency power source 9 for the electrode. The substrate 10 is configured to be placed on the electrode 8.
[0020]
In FIG. 2, the pattern of the heating wire 11 arrange | positioned at the heater 3 is shown. The heating wire 11 has a group of arcs arranged concentrically centering directly above the center of the substrate 10 to be processed, and having the same diameter intermittent in the circumferential direction, and ends of arcs having different diameters. By connecting each other in the radial direction, each of the divided dielectric plates 2 is continued.
[0021]
In the above configuration, a high-frequency power source is supplied to the coil or antenna 6 while an appropriate gas is introduced by the gas introduction means 5 while the inside of the vacuum container 1 is exhausted by the exhaust means 4 and an appropriate pressure is maintained in the vacuum container 1. When high frequency power is applied by 7, electromagnetic waves are introduced into the vacuum vessel 1 through the dielectric plate 2 to generate plasma, and plasma for etching, deposition, surface modification, etc. on the substrate 10 to be processed on the electrode 8. Processing can be performed. At this time, the ion energy reaching the substrate 10 can be controlled by applying a high-frequency voltage to the electrode 8 from the high-frequency power supply 9 for the electrode.
[0022]
Here, the coil or antenna 6 is usually circular, and the arrangement pattern of the heating wires 11 has a concentric circular arc group centering directly on the center of the substrate 10 to be processed and having a diameter as described above. By forming a continuous pattern by connecting the ends of different arcs in the radial direction, the angle formed by the coil 6 and the heating wire 11 can be made constant over the entire surface of the heater 3 and is generated in the vacuum vessel 1. The plasma to be made can be made uniform.
[0023]
In the present embodiment, a rectangular glass substrate of 680 × 880 mm is used as the substrate 10 to be processed, and the heater 3 having an average aperture ratio of 90% is used as shown in FIG. The aperture ratio of the heater 3 is not evenly distributed over the entire surface, and the aperture ratio in a donut-shaped range having an inner diameter D ₁ of 660 mm and an outer diameter D ₂ of 1260 mm is set to 92%, which is higher than the average. . Since the diagonal length (outermost diameter) of the glass substrate of 680 × 880 mm is 1112 mm, the inner diameter 660 mm and the outer diameter 1260 mm are 59.3% and 113.3%, respectively, with respect to the outermost diameter.
[0024]
As a result of measuring the electron density at 48 measurement points on the substrate 10 to be processed, the average value of the electron density is Isat = 3.52 mA / cm ² , and the uniformity at 48 points is ± 19.9%. there were. The conditions at this time are Ar = 1000 sccm for the gas used, a pressure of 2 Pa, and a high-frequency power value of 12 kW. Under the same conditions, when measured without using the heater 3 for heating the dielectric plate, the average value of the electron density was Isat = 3.53 mA / cm ² and the uniformity was ± 22.2%. Even so, the loss was improved by 0% and the uniformity was improved by 2.3%.
[0025]
In the description of the above embodiment, a dry etching apparatus for a liquid crystal device is illustrated, but the present invention is not limited to this, and a dry etching apparatus for a semiconductor, or a plasma processing apparatus such as a plasma CVD apparatus or a sputtering apparatus. The same applies to the above.
[0026]
【The invention's effect】
According to the plasma processing method of the present invention, as described above, it has a group of arcs arranged concentrically around the center of the substrate and having the same diameter intermittently in the circumferential direction, and Each of the divided dielectric plates is heated by a heating wire that is continuous for each of the divided dielectric plates by connecting the ends of arcs of different diameters in the radial direction. Even when a dielectric plate divided into two is used, reaction products can be prevented from adhering to the dielectric plate, and the crossing angle between the coil or antenna and the heating wire does not change. The heating wire is arranged in a donut-shaped range in which the inner diameter is approximately half of the outer diameter or diagonal length of the substrate to be processed and the outer diameter is approximately the outer diameter or diagonal length of the substrate to be processed. Make the installation density smaller than other parts, from the coil or antenna Since the smaller the density of arrangement of the portion having strong magnetic field, the efficiency can be improved, Ru can be subjected to plasma treatment with high efficiency.
[0029]
Further, according to the plasma processing apparatus of the present invention, the plurality of heaters for heating the dielectric plates are arranged concentrically with the center just above the center of the substrate and the ones having the same diameter are intermittently provided in the circumferential direction. And the heating wire connected to each of the dielectric plates divided by connecting the ends of the circular arcs having different diameters in the radial direction, the crossing angle of the coil or antenna and the heating wire is It is possible to obtain a uniform plasma without any change and perform highly uniform processing , and the heating wire has an inner diameter that is approximately half the outer diameter or diagonal length of the substrate to be processed, and the outer diameter is substantially equal to that of the substrate to be processed. Since the donut-shaped range of the outer diameter or diagonal length is arranged to be smaller than the other parts, the arrangement density of the heating wire in the part where the magnetic field generated from the coil or antenna is strong is reduced. The efficiency can be improved and the Ru can be subjected to Ma processing.
[0030]
In addition, when the heater opening ratio, which is the ratio of the portion other than the heating wire to the area of the entire heater, is 87% or more on average, processing can be performed with high efficiency.
[0031]
Further, when the inner diameter is approximately half of the outer diameter or diagonal length of the substrate to be processed and the outer diameter is approximately 90% or more in the donut-shaped range of the outer diameter or diagonal length of the substrate to be processed, Processing can be performed with high efficiency.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a plasma processing apparatus according to an embodiment of the present invention.
FIG. 2 is a plan view showing an arrangement pattern of heating wires of a heater in the same embodiment.
FIG. 3 is a longitudinal sectional view of a conventional plasma processing apparatus.
FIG. 4 is a plan view showing an arrangement pattern of heating wires of a heater in a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Dielectric board 3 Heater 6 Coil or antenna 7 High frequency power supply 8 Electrode 10 Substrate 11 Heating wire

Claims (4)

In a plasma processing method for generating a plasma by applying a high frequency voltage to a coil or an antenna and introducing an electromagnetic wave into a vacuum vessel through a plurality of divided dielectric plates, the plasma processing method for processing a substrate is directly above the center of the substrate. Each of the dielectric plates is divided by connecting ends of arcs having different diameters in a radial direction, each having an arc group in which concentric circles centered on each other and having the same diameter are interrupted in the circumferential direction. The inner diameter is approximately half of the outer diameter or diagonal length of the substrate to be processed, and the outer diameter is approximately the outer diameter or diagonal length of the substrate to be processed. A plasma processing method, comprising: heating each divided dielectric plate with a heating wire arranged so as to have a density smaller than that of the portion . A high-frequency power source, a coil or antenna to which a high-frequency voltage is applied from the high-frequency power source, a vacuum vessel composed of a dielectric plate in which a wall surface facing the coil or antenna is divided into a plurality of parts, and a substrate to be processed are placed And a plurality of heaters for heating the dielectric plate, the heaters are arranged concentrically around the center of the substrate and have the same diameter in the circumferential direction. It has a different arc heating wire is continuously in each dielectric plate which is divided by connecting the ends to each other at radially and radially has an arc group being interrupted, and the heating wire is an inner diameter to be in the Arranged so that the outer diameter of the substrate to be processed is approximately half of the outer diameter or diagonal length, and the outer diameter is approximately the outer diameter or diagonal length of the substrate to be processed and the donut-shaped range is smaller than other portions. A plasma processing apparatus characterized by that. 3. The plasma processing apparatus according to claim 2 , wherein an opening ratio of the heater, which is a ratio occupied by a portion other than the heating wire with respect to the entire area of the heater, is set to an average of 87% or more. The inside diameter is approximately half of the outer diameter or diagonal length of the substrate to be processed, and the opening ratio in the donut-shaped range of the outer diameter or diagonal length of the substrate to be processed is approximately 90% or more. The plasma processing apparatus according to claim 3 .

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