JP2004296868A - Plasma processing apparatus and processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus or the like and a plasma processing method capable of adopting higher concentration radical irradiation for ensuring high speed etching even under a low pressure and ensuring ion concentration required for vertical etching performance. <P>SOLUTION: The plasma processing apparatus comprises a decomposition chamber provided with a gas decomposition means for decomposing a reactive gas; and a process chamber located at the downstream of the decomposition chamber and for processing a substrate supported by a substrate placing base by means of a decomposition gas flowing from the gas decomposition chamber, the plasma processing method adopts the processing apparatus, and the process chamber is provided with a plasma production means for producing plasma of the decomposition gas. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a dry etching apparatus that enables high-speed and vertical etching.
[0002]
[Prior art]
As a conventional plasma processing technique, a silicon high-speed dry etching technique will be described as an example.
Usually, an inductively coupled plasma etching apparatus capable of generating low-pressure and high-density plasma is used for etching a high aspect ratio hole. An example of this etching apparatus is shown in FIG. The etching apparatus of FIG. 7 introduces reactive gas from the gas supply apparatus 3 into the reaction vessel 10 to which the gas supply apparatus 3 and the exhaust apparatus 6 are connected, and supplies power to the external antenna 11 from the high frequency power supply 12. Generate plasma. On the other hand, a high frequency power is applied from a high frequency power source 24 to the substrate mounting table 24 holding the substrate 26 to apply a bias to the substrate. In this way, anisotropic etching with a vertical step shape can be performed by F radicals transported to the substrate surface and ions drawn by the substrate bias.
[0003]
[Problems to be solved by the invention]
However, this apparatus has a problem that since the pressure is low, the amount of F radicals produced is small and high-speed etching is difficult. Therefore, in order to increase the radical density, a method of supplying a larger electric power is usually adopted. However, the radical concentration obtained in this way is not yet sufficient, and in addition to the radical, the ion concentration is increased. Furthermore, since the ion energy incident on the substrate also increases, the etching rate of the inner wall of the hole due to obliquely incident ions increases to destroy the sidewall protective film, or the etching rate of the mask increases and the etching ratio to the mask decreases. As a result, there are problems that the vertical etching property is deteriorated and deep holes cannot be etched.
[0004]
Therefore, as shown in FIG. 8, there has been proposed an etching apparatus having a configuration in which the inside of a vacuum vessel is divided into a plasma generation chamber 1 and a substrate processing chamber by a partition plate 20 having a large number of holes (Japanese Patent Laid-Open No. 10-270428, JP-A-10-270429, JP-A-10-270430, JP-A-10-270431, etc.). This apparatus generates a large amount of radicals and ions by setting the plasma chamber 1 at a high pressure, and transports the radicals and ions to the processing chamber 2 at a low pressure to perform anisotropic etching by ions and perform high-speed etching. Is.
However, even with the apparatus having the configuration shown in FIG. 8, it was found that ions were almost lost when they were transported to the processing chamber, and it was difficult to perform ion etching to maintain verticality.
[0005]
In such a situation, the present inventor examined various apparatus configurations, etching conditions, etc., by discharging the gas containing radicals again, and performing etching treatment with the generated plasma, compared with the case of normal gas. It was found that the etching rate was greatly increased. The present invention has been completed with further studies based on this finding.
[0006]
That is, the present invention provides a dry etching apparatus capable of increasing the concentration of radicals for ensuring high-speed etching while maintaining a low ion concentration necessary for vertical etching properties while being under low pressure. An object is to provide a processing method. It is another object of the present invention to provide a dry etching apparatus capable of controlling the radical / ion concentration ratio and enabling an etching process with a higher degree of freedom.
It is another object of the present invention to provide a plasma processing apparatus and a processing method such as a plasma CVD apparatus and an ashing apparatus capable of forming films having various characteristics.
[0007]
[Means for Solving the Problems]
The plasma processing apparatus of the present invention includes a decomposition chamber having a gas decomposition means for decomposing a reactive gas, and a substrate disposed on the downstream side of the decomposition chamber and held on the substrate mounting table by the decomposition gas flowing from the gas decomposition chamber. A substrate processing apparatus comprising: a processing chamber for performing processing, wherein the processing chamber includes plasma generation means for generating plasma of the decomposition gas.
A partition plate having a plurality of through holes is disposed between the decomposition chamber and the processing chamber. Thereby, not only the pressure difference between both chambers but also the radical / ion concentration ratio of the gas transported to the processing chamber can be controlled.
[0008]
The gas decomposition means and the plasma generating means are inductively coupled or capacitively coupled plasma generators. Alternatively, the gas decomposition means is a heater made of a refractory metal of any one of tungsten, tantalum, niobium, osmium, iridium, molybdenum and ruthenium or platinum disposed in the gas decomposition chamber, and the surface temperature of the heater Is heated to a temperature equal to or higher than the decomposition temperature of the reactive gas to decompose the reactive gas, and the plasma generating means is an inductively coupled or capacitively coupled plasma generator.
[0009]
As described above, a large amount of radicals are generated at a high pressure, which is led to a processing chamber having a lower pressure than the radical generation region, where plasma is generated and etching is performed with a large amount of radicals while irradiating the obtained ions onto the substrate. By performing the etching, it is possible to perform etching with high speed and excellent verticality. Since this method can obtain a higher concentration of radicals than the conventional method, it enables higher-speed etching.
[0010]
In the present invention, the plasma generating means may be configured to generate a plasma by supplying a high frequency power to the partition plate, and the inductive coupling type and capacitive coupling type plasma generating apparatus may be a high frequency plasma. It is preferable to provide a magnetic device for generating a multicusp magnetic field in the space.
It is preferable that a high frequency power supply for applying a substrate bias is connected to the substrate mounting table. Thereby, it becomes possible to control ion energy according to the process requested | required.
[0011]
The plasma processing method of the present invention includes a step of introducing a reactive gas into a decomposition chamber for decomposition, a step of transporting the decomposition gas to a processing chamber on which a substrate is placed, and a substrate by the decomposition gas in the processing chamber. A substrate processing method comprising: generating a plasma of the decomposition gas in the processing chamber.
The reactive gas is decomposed by generating plasma of the reactive gas with high-frequency power, or any of tungsten, tantalum, niobium, osmium, iridium, molybdenum or ruthenium heated to a temperature higher than the decomposition temperature of the reactive gas. It can be carried out by contacting with such a refractory metal or platinum.
[0012]
Moreover, it is preferable that the pressure of the decomposition chamber is 100 to 10,000 Pa and the pressure of the processing chamber is 1 to 10 Pa. Thereby, it becomes possible to etch a high aspect ratio minute hole with higher accuracy and higher speed.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing a configuration example of a dry etching apparatus according to the first embodiment of the present invention.
As shown in the figure, the dry etching apparatus is composed of a decomposition chamber 1 for decomposing a reactive gas and a processing chamber 2 for processing a substrate, and the decomposition chamber is connected to a gas supply device 3 through a pipe 4 to form a processing chamber. Is connected to the exhaust device 5 via a valve 6.
[0014]
The decomposition chamber 1 is provided with an inductively coupled plasma generator (first plasma generator) including an external antenna (high frequency electrode) 11 and a high frequency power source 12. In the decomposition chamber, a dielectric material such as quartz glass is used so that high-frequency power is supplied into the chamber.
A substrate mounting table 24 that holds a substrate 26 is attached inside the processing chamber 2, and a high-frequency power source 25 for applying a bias to the substrate is connected. In order to generate plasma also in the processing chamber, a capacitively coupled plasma generation device (second plasma generation device) including a partition plate 21 acting as a high frequency electrode and a high frequency power source 23 is provided. The partition plate 21 is formed with a large number of through holes through which gas passes, and is attached to the wall of the processing chamber via an insulator 22. The pressure difference between the upstream side and the downstream side is determined by the size and number of the through holes of the partition plate.
[0015]
Next, a method for etching silicon, for example, will be described using the apparatus shown in FIG. The substrate 26 is set on the mounting table 24 and the inside of the apparatus is exhausted by the exhaust apparatus 5. A silicon etching gas (for example, SF ₆ ) is supplied at a predetermined flow rate from the gas supply device 3, and the valve 6 is adjusted to set the substrate side pressure in the processing chamber to, for example, 1 to 10 Pa. On the other hand, the number and diameter of the through holes of the partition plate are previously formed so that the pressure on the decomposition chamber side is about 100 to 10,000 Pa. A pore diameter of 0.1 to 1.0 μm and an aperture ratio of 10% or less is preferably used.
[0016]
Thereafter, high frequency power in the HF band (for example, 13.56 MHz) is applied to the external antenna 11 from the high frequency power source 12 of the first plasma generator to generate plasma. In addition, high frequency power in the VHF band (for example, 60 MHz) is supplied from the high frequency power source of the second plasma generator to the partition plate 22 to generate plasma between the partition plate 21 and the substrate 26. At the same time, high frequency power in the HF band (for example, 1.6 MHz) is supplied to the substrate mounting table 24, and a predetermined bias is applied to the substrate.
[0017]
The reactive gas is decomposed by high-frequency power supplied from the high-frequency power source 12 to generate ions such as F radicals and SF _n ⁺ . Since the pressure in the decomposition chamber is set as high as 100 Pa or more, high-density F radicals and ions are generated. The generated F radicals and ions are transported to the processing chamber together with the undecomposed gas and other active species. Here, since the lifetime of F radicals is much longer than that of ions, the concentration of F radicals in the gas when reaching the processing chamber is kept high, and the F radical / ion concentration ratio is compared with the value in plasma. It can be a very large value. The F radical / ion concentration ratio can be adjusted by, for example, the transport distance.
[0018]
Thus, the gas containing a large amount of F radicals is blown out from the through hole of the partition plate toward the substrate in a low pressure state of about 1 to 10 Pa, and the second plasma is generated based on this gas. That is, since the gas for generating the second plasma originally contains a large amount of F radicals, when the plasma is generated based on this gas, the F radicals are further increased even though the pressure is low. A plasma containing a high concentration of F radicals is generated. On the other hand, since the plasma generated in this way contains a large amount of F radicals without excessively applying high-frequency power, the ion density and the substrate incident energy of ions can be kept low. That is, since a small number of ions can be made perpendicularly incident on the substrate with a small energy while containing high-density F radicals, only the protective film on the bottom surface of the etching is etched with these ions, and the etching of the side wall protective film can be suppressed. Therefore, the vertical etching of silicon proceeds at a high speed by the F radicals.
As described above, since the amount of radicals is added by the amount generated by the first plasma generator, despite the low pressure that can utilize the anisotropy of ions, low-pressure plasma containing high-concentration radicals is generated. Realized and enables unprecedented high-speed etching. That is, vertical etching by ions is ensured and high-speed etching can be performed.
[0019]
In the present embodiment, a ground potential shield plate having a large number of through holes may be disposed upstream of the partition plate 21. As a result, the plasma generated by the second plasma generator does not extend above the partition plate, and can be separated from the plasma generated by the first plasma generator, and ions can be blocked. Can be reduced, and the apparatus can be miniaturized.
[0020]
As the dry etching apparatus provided with two plasma generation apparatuses, apparatuses having various configurations can be considered by combining the inductive coupling method and the capacitive coupling method. In addition to the case of using an external antenna, an internal antenna can be used for the inductive coupling method. Some examples of these configurations are shown in the schematic diagrams of FIGS.
[0021]
The dry etching apparatus of FIG. 2 has a configuration in which the decomposition chamber 1 and the processing chamber 2 are partitioned by a partition plate 20. As the first plasma generating device in the decomposition chamber 1 and the second plasma generating device in the processing chamber 2, a capacitive coupling type plasma generating device and an internal antenna inductive coupling type plasma generating device are used, respectively.
That is, in the first plasma generator, the shower head 11 having a large number of gas ejection holes is connected to the high-frequency power source 12, and discharge occurs between the partition plate 20 at the ground potential and plasma is generated. On the other hand, the second plasma generator comprises, for example, an annular internal antenna (electrode) 21 connected to the high-frequency power source 23 at one end and connected to the processing chamber wall (ground potential) at one end, and plasma is generated around the antenna. Generate. As such an inductive coupling method of the internal antenna, for example, the one described in JP-A-9-106899 is preferably used. The substrate mounting table 24 is connected to a high frequency power supply for applying a substrate bias.
[0022]
As in the case of FIG. 1, the pressure in the decomposition chamber 1 is set to a high pressure of 100 to 10000 Pa in order to generate a high concentration of F radicals. Since the distance between the two plasmas is short, the first plasma oozes out through the through hole of the partition wall, and as a result, it becomes difficult to control the F radical / ion ratio. Therefore, the shape, length, density, etc. of the through-holes of the partition plate of this embodiment need not only determine the pressure ratio between the decomposition chamber and the processing chamber, but also must have such a shape that only radicals do not pass through ions. There may also be a through hole in the passage that bends for this purpose.
[0023]
A gas containing high-concentration F radicals is transported to the processing chamber 2 where high-frequency power is supplied to generate plasma, which becomes plasma containing high-concentration F radicals despite the low pressure. Thereby, the vertical etching property by ions is maintained and high-speed etching is possible.
The shape of the internal antenna is not limited to an annular shape, and various shapes such as a U shape and a straight line are used.
[0024]
The dry etching apparatus shown in FIG. 3 is an inductive coupling system in which two plasma generators each have an external antenna. Therefore, at least the chamber wall of the antenna placement portion must be made of quartz glass or the like.
Further, as in the case of FIG. 2, the partition plate 20 is devised in the shape of the through hole so as to separate the plasma and prevent the ions from passing therethrough.
[0025]
The dry etching apparatus shown in FIG. 4 is configured to use a capacitive coupling system for both of the two plasma generators. In the decomposition chamber 1, discharge occurs between a shower head (high-frequency electrode) 11 that blows out gas and a partition plate (ground potential) 20 having a large number of through holes. In the processing chamber 2, discharge occurs between the high-frequency electrode 21 having a large number of through holes and the substrate 26. Here, the partition plate 20 having the ground potential and the high-frequency electrode 21 are arranged as an interval at which no discharge occurs between them.
With such a configuration, the pressure difference between the decomposition chamber and the processing chamber can be further increased, and high-speed etching with further excellent vertical etching performance can be achieved.
[0026]
Next, a second embodiment of the present invention will be described with reference to FIG.
In this embodiment, a tungsten wire heater is used as a reactive gas decomposition means, and the F radical is heated by heating the wire to a temperature higher than the decomposition temperature of the reactive gas and bringing it into contact with the reactive gas. Other active species are generated. That is, as shown in FIG. 5, the tungsten wire 13 is fixedly attached to the support 14 and power is supplied from the external power source 12.
[0027]
First, after exhausting the inside of the processing chamber 2 and the decomposition chamber 1 with the exhaust device 5, a reactive gas is introduced from the gas supply device 3 through the gas pipe 4, and the valve 6 is adjusted to set the inside of the processing chamber to a predetermined amount. Set to pressure. Subsequently, power is supplied to the tungsten wire 13 to heat it to a predetermined temperature, and high-frequency power is supplied to the high-frequency electrode (partition plate) 22 to generate plasma between the substrate 26.
The reactive gas decomposes on the tungsten wire surface, and F radicals and other active species are generated. The F radicals are transported to the processing chamber 2 and discharge occurs due to the gas containing the F radicals, so that plasma containing a high concentration of F radicals is generated at a low pressure. As a result, high-speed etching can be performed while maintaining vertical etching properties.
[0028]
As the wire material of this embodiment, refractory metals such as tantalum, niobium, osmium, iridium, molybdenum, ruthenium, and platinum can be used in addition to tungsten. These metal wires react with F radicals and other active species and gradually decrease in diameter, so it is necessary to replace them periodically. Although this reaction is more severe at higher temperatures, the wire is heated to a predetermined temperature or higher. On the contrary, it has been confirmed that the reaction does not occur. Therefore, it is preferable to heat the wire temperature to a temperature higher than the temperature at which the above reaction is suppressed, and to heat above this temperature before introducing the reactive gas. Is preferred. For example, in the case of tungsten, if it is heated to 2000 ° C. or higher, it becomes possible to substantially prevent the thinning of the wire, and maintenance such as replacement can be greatly extended.
In addition to the wire, any shape may be used as long as it can be heated by energization, such as a rod shape or a plate shape.
[0029]
In place of the plasma generating means of the dry etching apparatus of FIG. 5, as shown in FIG. 6, the plasma generating apparatus is at a ground potential by supplying power from a high frequency power supply 25 using, for example, a substrate mounting table 24 as a high frequency electrode. It is good also as a structure which generates a plasma between the partition plates 20.
Furthermore, in the present invention, by attaching a magnetic field device that forms a multicusp magnetic field as disclosed in, for example, Japanese Patent Laid-Open No. 9-106899, the plasma is confined in the magnetic field, and a higher density and uniform plasma is generated. I can do it.
[0030]
In the present invention, the VHF band is used for the high frequency of the plasma generator, but ECR microwave plasma may also be used in the HF band. Various combinations of device configurations are possible. Although etching of silicon has been described, it goes without saying that it is not limited to silicon. Moreover, it can be applied not only to etching but also to plasma CVD, and the degree of freedom of film formation for controlling the relationship between various radical species or other active species and ions is widened, and a thin film having a wide range of characteristics can be produced. Is possible.
[0031]
【The invention's effect】
As described above, the plasma of the present invention can generate a higher concentration of F radicals for ensuring high-speed etching while being under a low pressure, and has an ion concentration for achieving vertical etching properties. Can be secured.
Furthermore, the radical concentration / ion concentration ratio can be controlled, and plasma processing that enables etching and film formation with a higher degree of freedom is possible.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a plasma processing apparatus according to a first embodiment of the present invention, in which plasma is used for decomposition of a reactive gas.
FIG. 2 is a schematic diagram showing another example of the first embodiment.
FIG. 3 is a schematic diagram showing another example of the first embodiment.
FIG. 4 is a schematic diagram showing another example of the first embodiment.
FIG. 5 is a schematic view showing a plasma processing apparatus according to a second embodiment of the present invention, in which a reactive gas is decomposed by contact with a refractory metal heated to a high temperature.
FIG. 6 is a schematic diagram illustrating another example of the second embodiment.
FIG. 7 is a schematic view showing an example of a conventional dry etching apparatus.
FIG. 8 is a schematic view showing another example of a conventional dry etching apparatus.
[Explanation of symbols]
1 decomposition chamber,
2 processing chamber,
3 Gas supply device,
4 Piping,
5 exhaust system,
6 valves,
11 High frequency electrode 12, 23, 25 High frequency power supply,
20 Bulkhead plate,
21 high frequency electrode (partition plate),
22 insulator,
24 substrate mounting table,
26 substrate.

Claims (14)

A decomposition chamber provided with a gas decomposition means for decomposing the reactive gas, and a processing chamber that is disposed on the downstream side of the decomposition chamber and that processes the substrate held on the substrate mounting table by the decomposition gas flowing in from the gas decomposition chamber; What is claimed is: 1. A plasma processing apparatus comprising: a plasma generating means for generating plasma of the decomposition gas in the processing chamber. The plasma processing apparatus according to claim 1, wherein a partition plate having a plurality of through holes is disposed between the decomposition chamber and the processing chamber. The plasma processing apparatus according to claim 1, wherein the gas decomposition unit and the plasma generation unit are an inductive coupling type or a capacitive coupling type plasma generation apparatus. The gas decomposition means is a heater made of a refractory metal of any one of tungsten, tantalum, niobium, osmium, iridium, molybdenum and ruthenium or platinum disposed inside the gas decomposition chamber, and the surface temperature of the heater is adjusted. 2. The structure according to claim 1, wherein the reactive gas is decomposed by being heated to a temperature equal to or higher than a decomposition temperature of the reactive gas, and the plasma generating means is an inductively coupled or capacitively coupled plasma generator. 2. The plasma processing apparatus according to 2. The plasma processing apparatus according to any one of claims 2 to 4, wherein the plasma generation unit is configured to generate plasma by supplying high-frequency power to the partition plate. 6. The plasma processing apparatus according to claim 3, further comprising a magnetic device that generates a multicusp magnetic field in the plasma space. The plasma processing apparatus according to claim 1, wherein a high frequency power supply for applying a substrate bias is connected to the substrate mounting table. The plasma processing apparatus according to claim 1, wherein the substrate is etched. Introducing a reactive gas into the decomposition chamber for decomposition, transporting the decomposition gas to a processing chamber on which the substrate is placed, and performing a surface treatment of the substrate with the decomposition gas in the processing chamber; A plasma processing method comprising: generating plasma of the decomposition gas in the processing chamber. The plasma processing method according to claim 9, wherein the decomposition of the reactive gas is performed by generating plasma of the reactive gas with high-frequency power. The plasma processing method according to claim 10, wherein a partition plate having a plurality of through holes is arranged to separate two plasmas. The plasma processing method according to claim 10 or 11, wherein the pressure in the decomposition chamber is set to 100 to 10,000 Pa, and the pressure in the processing chamber is set to 1 to 10 Pa. The decomposition of the reactive gas is performed by contacting with a refractory metal or platinum of any one of tungsten, tantalum, niobium, osmium, iridium, molybdenum, and ruthenium heated to a temperature higher than the decomposition temperature of the reactive gas. The plasma processing method according to claim 9. The plasma processing method according to claim 9, wherein the substrate is etched.

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