JP2005064063A - Plasma treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment apparatus that can prevent deactivation of ions, even if gas-separating plates which separate a gas which does not contain F and a gas containing F, in order to prevent the occurrence of damages in a chamber. <P>SOLUTION: In the chamber 1 of the plasma treatment apparatus, gas supply pipes 12 and 13 are respectively disposed on both sides of the gas-separating plates 4 and 4A which are provided in parallel with a dielectric window 2 separated from the window 2, an antenna means 5 is provided in the bottom of a waveguide 3, in a state of the means 5 passing through the dielectric window 2, and the front end of the antenna means is protruded from the gas-separating plates 4 and 4A. In addition, intervals d are respectively provided between the antenna means 5 and gas-separating plates 4 and 4A. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus capable of performing a good plasma process on an object to be processed with little damage to the apparatus.
[0002]
[Prior art]
An example of a conventional plasma processing apparatus will be described with reference to the schematic diagram shown in FIG. That is, the plasma processing apparatus vertically moves the interior of the chamber 51 up and down between the plasma generation unit 53 and the processing chamber 54 by the gas separation plate 52 made of a metal plate having a gas passage hole (not shown) arranged in the horizontal direction. Two gas supply pipes 55 a and 55 b are provided for partitioning and supplying process gas into the chamber 51. The gas supply pipes 55a and 55b are arranged vertically through the gas separation plate 52 so as to penetrate the upper side wall of the chamber 51.
[0003]
From the gas supply pipe 55 a provided above the gas separation plate 52, O ₂ gas not containing F is supplied as the process gas into the chamber 1, while from the gas supply pipe 55 b below the gas separation plate 52. Is configured to supply a mixed gas containing fluorine, such as CF ₄ , NF ₃ , SF ₆ or the like containing F, or a gas obtained by adding hydrogen gas to these gases into the chamber 51. .
[0004]
In this case, since the exhaust port 56 sucked by a vacuum pump (not shown) is located below the stage 57 on which the workpiece W is placed, the gas is introduced into the chamber 51 from above. It is flowing downward. Therefore, the gas containing F does not reach the plasma generation unit 53 above the gas separation plate 52, and the dielectric window is a dielectric that guides the microwave from the waveguide 58 to the inside of the chamber 51. Damage to the cavity 60 (part of the chamber) supporting 59 is prevented.
[0005]
[Problems to be solved by the invention]
As described above, the gas separation plate 52 provided inside the chamber 51 also serves to protect the cavity 60 that supports the dielectric window 59 from damage caused by electrons and ions present in the plasma. At the same time, for example, the surface of the device to be processed is heated to 200 ° C. or higher by cutting electrons and ions and cutting off the heat, and the substrate is etched. This prevents problems such as being easy to occur.
[0006]
However, the presence of the gas separation plate 52 has a problem that the active species are deactivated and the etching and ashing speeds are reduced. That is, when the processing pressure is high (about 60 to 200 Pa), since it is a radical rich processing, radical deactivation in the gas separation plate 52 is not large, but the pressure is set to a low pressure (about 5 to 30 Pa). When processing is performed using ions in this state, the ions are deactivated by the gas separation plate 52 and the processing rate of etching or the like is reduced.
[0007]
The present invention has been made based on these circumstances, and in order to prevent damage inside the chamber, even if a gas separation plate for separating a gas containing no F and a gas containing F is provided, It aims at providing the plasma processing apparatus which can prevent deactivation of ion.
[0008]
[Means for Solving the Problems]
According to the present invention, the antenna means for guiding the microwave traveling in the waveguide into the chamber and the dielectric window are provided, and the chamber is located at a position facing the dielectric window through a predetermined space. A holder for holding the object to be processed is provided, and a gas supply pipe for supplying gas into the chamber from the upper part of the chamber is provided, and the gas in the chamber is converted into plasma by the microwave. A plasma processing apparatus for processing the workpiece by:
The gas supply pipes are respectively arranged at positions sandwiching a gas separation plate provided in parallel with the dielectric window inside the chamber, and the antenna means is provided at the bottom of the waveguide. The antenna means is provided so as to penetrate the dielectric window, and the position of the tip portion is provided so as to protrude from the gas separation plate, and a gap is provided between the antenna means and the gas separation plate. A plasma processing apparatus.
[0009]
According to the present invention, the plasma processing apparatus is characterized in that a holo-cathode discharge is generated in a gap between the coaxial conversion antenna and the gas separation plate.
[0010]
According to the present invention, the gas supply pipe disposed above the gas separation plate supplies O ₂ gas not containing F into the chamber, while being disposed below the gas separation plate. The gas supply pipe is a plasma processing apparatus characterized in that a gas containing F is supplied into the chamber.
[0011]
According to the invention, there is provided a plasma processing apparatus, wherein a plurality of the antenna means are arranged at a predetermined interval.
[0012]
According to the present invention, the plasma processing apparatus is characterized in that the discharge frequency of the microwave is 2.45 GHz.
[0013]
According to the invention, the gas separation plate is a plasma processing apparatus characterized in that a Si plate or a quartz plate is superposed on a Si plate.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
First, the basic concept of the present invention will be described. While maintaining the function of suppressing damage to the cavity (part of the chamber) that fixes the dielectric window, the deactivation of ions in the low-pressure discharge region is prevented, and the object to be processed is processed at a predetermined processing rate. At the same time, the following knowledge was obtained as a result of considering the simultaneous prevention of damage to the workpiece by electrons, ions and heat.
[0016]
That is, when a slot-type surface wave plasma is generated inside the chamber in the plasma processing apparatus, if a gas separation plate having a conventional structure is used inside the chamber, The space of the processing unit is separated. As a result, the generated plasma is in a state of being confined inside the plasma generation unit by the gas separation plate, causing a problem.
[0017]
Therefore, even if a gas separation plate is used, the plasma generation unit and the processing unit are configured not to be separated so that the plasma is not confined in a narrow region near the cavity fixing the dielectric window. Each problem can be solved.
[0018]
Specifically, FIG. 1 is a schematic diagram showing an embodiment of a plasma processing apparatus using microwave excitation according to the present invention. In the plasma processing apparatus, a dielectric window 2 is provided in the upper part of the chamber 1, and a waveguide 3 having a rectangular cross section for introducing a microwave into the chamber 1 is provided above the dielectric window 2. A terminal portion is arranged. A gas separation plate 4 is disposed in parallel with the dielectric window 2 at a position below the dielectric window 2.
[0019]
The waveguide 3 includes a plane (H plane) perpendicular to the microwave electric field direction, a plane (E plane) parallel to the microwave electric field direction extending in a direction perpendicular to the H plane, and a microwave introduction side. The coaxial conversion antenna 5, which will be described later, has a reflection surface (R surface) that reflects the microwaves provided perpendicularly to the H surface and the E surface on the opposite side. It is provided so that it may be located in.
[0020]
By using a common TEM mode (coaxial surface wave plasma) using the coaxial conversion antenna 5, the plasma generation unit 6 can be set in the vertical direction. Therefore, even if the gas separation plate 4 exists, the plasma generation unit 6 is not separated by it. By adopting this method, the deactivation of ions in the low-pressure discharge region can be performed while the cavity (part of the chamber 1) 7 fixing the dielectric window 2 due to the surface wave has a function of suppressing damage due to the surface wave. It becomes possible to prevent.
[0021]
The length of the coaxial conversion antenna 5 can be set to an arbitrary length as long as the distal end portion 5a penetrates to a space below the gas separation plate 4.
[0022]
In the chamber 1, a plasma generation unit 6 is provided above the inside, and a processing chamber 8 is formed below the plasma generation unit 6. In the processing chamber 8, a holder 11, which is an electrostatic chuck on which, for example, a substrate (a semiconductor substrate, a substrate for a liquid crystal display device or the like, hereinafter simply referred to as a substrate) 9 as a member to be processed is placed. The holder 11 includes an RF bias and He cooling mechanism (not shown), and an RF oscillator and a chiller (not shown) are connected to the holder 11. The gas supply pipes 12 and 13 are formed on the side wall of the plasma generation unit 6 at the top of the chamber 1, and a gas exhaust pipe (not shown) is attached to the bottom of the chamber 1 in which the processing chamber 8 is formed, An exhaust system (not shown) such as a vacuum pump is connected to the other end of the gas exhaust pipe (not shown).
[0023]
Further, in order to introduce the microwave from the waveguide 3 to the plasma generation unit 6, the surface perpendicular to the electric field direction of the microwave traveling in the waveguide 3 (H plane) and the opposing dielectric window 2 are provided. A circular opening 15 is provided, and the coaxial conversion antenna 5 is installed through the opening 15. The quartz dielectric window 2 constitutes a part of the coaxial conversion antenna 5.
[0024]
The central portion of the gas separation plate 4 with respect to the coaxial conversion antenna 5 is disposed with a gap d as shown in FIG. The gap d is set so that the process gas supplied from the gas supply pipe 12 can sufficiently flow into the chamber 1. At the same time, this gap d is also considered to generate a holo-cathode discharge. In order to ensure the plasma, a space is required in addition to the sheath region, and the gap d needs to be 3 to 20 mm considering that the sheath with surface waves is about 1 mm. When a hollow cathode discharge is generated, the life of the electrons in the plasma is extended, and the electron temperature is lowered because the electrons collide with the gas.
[0025]
The plate thickness of the bottom portion 3a of the waveguide 3 is set to a predetermined thickness, is used as an electrode, and is connected to a metal inner wall of the chamber 1 to form a coaxial line.
[0026]
The structure of the coaxial conversion antenna 5 is a concentric structure with a central portion made of a metal rod 16 and a peripheral portion thereof made of a dielectric 17 (for example, alumina, aluminum nitride, etc.). Sealed with a dielectric 17. Therefore, the metal rod 16 is not exposed inside the chamber 1.
[0027]
Gas supply pipes 12 and 13 for supplying a process gas to the inside of the chamber 1 are arranged vertically through the gas separation plate 4 so as to penetrate the side wall of the plasma generation unit 6 at the top of the chamber 1. .
[0028]
As the process gas, for example, when etching is performed on the thin film on the surface of the object to be processed (substrate 9), oxygen gas (O ₂ ) alone, or oxygen gas containing CF ₄ , NF ₃ , SF ₆ or the like. A mixed gas in which a fluorine-based gas is added or a gas in which hydrogen gas is added to these gases is used.
[0029]
The process gas is supplied from the gas supply pipe 12 provided above the gas separation plate 4 by supplying O ₂ gas not containing F into the chamber 1, while the gas supply below the gas separation plate 4 is supplied. From the tube 13, a mixed gas in which a fluorine-based gas such as CF ₄ , NF ₃ , or SF ₆ containing F is added, or a gas in which hydrogen gas is added to these gases is supplied into the chamber 1. I have to.
[0030]
In this case, a gas exhaust pipe (not shown) sucked by a vacuum pump (not shown) is installed below the holder 11 on which the object to be processed (substrate 9) is placed. The gas flows from the top to the bottom. Therefore, the O ₂ gas not containing F supplied from the gas supply pipe 12 provided above the gas separation plate 4 to the inside of the chamber 1 is, as indicated by the arrow A, the coaxial conversion antenna 5 and the gas separation plate 4. The gas flows into the chamber 1 through the gap d and joins with the gas containing F supplied into the chamber 1 through the gas supply pipe 13 below the gas separation plate 4. Moreover, the gas containing F supplied into the chamber 1 from the gas supply pipe 13 below the gas separation plate 4 does not reach the upper side of the gas separation plate 4.
[0031]
With these structures, the microwave radiated from the metal rod 16 constituting the coaxial conversion antenna 5 generates plasma in the vicinity of the coaxial conversion antenna 5.
[0032]
Next, a method for etching the glass substrate for liquid crystal 9 having a resist pattern formed on the surface thereof will be described as an example of the processing by the microwave-excited plasma processing apparatus having these configurations.
[0033]
First, a liquid crystal glass substrate 9 that is a workpiece W having a resist pattern formed on the surface thereof is placed on a holder 11 inside the chamber 1. A vacuum pump (not shown) is operated to exhaust the gas inside the chamber 1 to the outside from the chamber 1 through a gas exhaust pipe (not shown), thereby bringing the inside of the chamber 1 into a state close to a vacuum. After exhaust, for example, O ₂ gas is supplied as a process gas into the chamber 1 through a gas supply pipe 12 provided above the gas separation plate 4, and a mixed gas of O ₂ and carbon tetrafluoride. Is supplied into the chamber 1 through a gas supply pipe 13 provided below the gas separation plate 4.
[0034]
When the inside of the chamber 1 reaches a predetermined pressure, a microwave is introduced into the waveguide 3 from a microwave generation source (not shown), so that plasma in the vicinity of the coaxial conversion antenna 5 inside the chamber 1 is obtained. Plasma is generated in the generator 6. Then, activated species due to the generated plasma is introduced into the processing chamber 8. In this case, since there are no obstacles that deactivate the active species between the active species generated by the plasma and the processing chamber 8, active oxygen atoms in the plasma are placed on the holder 11. By reacting with the resist pattern on the surface of the workpiece (substrate 9), the resist pattern can be peeled off at a good processing rate.
[0035]
Next, a modification of the plasma processing apparatus described in the above embodiment will be described.
[0036]
(Modification 1)
In the above-described embodiment, the single coaxial conversion antenna 5 for guiding the microwave to the inside of the chamber 1 is configured, but the coaxial conversion antenna 5 is shown in FIG. 3A and FIG. A plurality of can be arranged. That is, the plasma 3 in the chamber 1 can be further increased in density because it is arranged in a contrasting position corresponding to the structure of the terminal end 3b of the waveguide 3, and efficient processing is performed. be able to.
[0037]
(Modification 2)
The plasma used when ashing or etching is performed by the plasma processing apparatus needs to consider damage to the device. Therefore, recently, it has been reported that the problem can be solved by using low electron temperature plasma.
[0038]
It is known that the means for generating the low electron temperature plasma can be achieved by increasing the discharge frequency of the microwave. Therefore, it was confirmed that the plasma processing apparatus shown in FIG. 1 can perform a good process without damaging the device by using a discharge format using a 2.45 GHz microwave coaxial type TEM mode. .
[0039]
(Modification 3)
This will be described with reference to the schematic structural diagram shown in FIG. In FIG. 4, the same functional parts as those in FIG. That is, in the plasma processing apparatus in which a plurality of coaxial conversion antennas 5 are arranged, the gap between the gas separation plate 4 and the coaxial conversion antenna 5 is formed so that sufficient holo-cathode discharge is generated. When this hollow cathode discharge is generated, the life of electrons in the plasma is extended, and the electron temperature decreases because the electrons collide with the gas. Further, when the gas separation plate 4 is made of Si, further effects can be expected. This is because the hollow cathode discharge is efficiently generated by the occurrence of the γ effect. The structure of the gas separation plate 4 has the same effect even when the number of coaxial conversion antennas 5 is one as shown in FIG.
[0040]
(Modification 4)
This will be described with reference to the schematic structural diagram shown in FIG. In FIG. 5, the same functional parts as those in FIG.
[0041]
In the modified example of the modified example 3, the gas separation plate 4 is made of Si. However, in this modified example, in order to extend the life of the gas separating plate 4A, quartz 18 is provided under the conventional Si gas separating plate 4. The plywood structure is laid. With this configuration, in addition to the effect described in the third embodiment, an effect of extending the life of the gas separation plate 4A can be obtained. The structure of the gas separation plate 4A has the same effect even when the number of coaxial conversion antennas 5 is one as shown in FIG.
[0042]
【The invention's effect】
According to the present invention, in order to prevent damage inside the chamber, even if a gas separation plate for separating a gas not containing F and a gas containing F is provided, deactivation of ions by the gas separation plate Can be prevented.
[0043]
Accordingly, damage to the chamber and the device can be prevented, and plasma processing with a high processing rate can be performed on the object to be processed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of a plasma processing apparatus using microwave excitation according to the present invention.
FIG. 2 is an explanatory diagram of a gap between a gas separation plate and a coaxial conversion antenna.
FIGS. 3A and 3B are explanatory views of a modification of the present invention. FIGS.
FIG. 4 is an explanatory diagram of a modification of the present invention.
FIG. 5 is an explanatory diagram of a modification of the present invention.
FIG. 6 is a schematic diagram showing an embodiment of a conventional plasma processing apparatus using microwave excitation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Chamber, 2 ... Dielectric window, 3 ... Waveguide, 4A ... Gas separation plate, 5 ... Coaxial conversion antenna (antenna means), 6 ... Plasma generation part, 7 ... Cavity, 8 ... Processing chamber, 9 ... Substrate, 11 ... Holder, 12, 13 ... Gas supply pipe, 16 ... Metal rod

Claims (6)

An antenna means for guiding the microwave traveling in the waveguide into the chamber and a dielectric window are provided, and the object to be processed is held in the chamber at a position facing the dielectric window through a predetermined space. And a gas supply pipe for supplying gas into the chamber from the upper part of the chamber. The gas in the chamber is converted into plasma by the microwave, thereby converting the object to be processed. A plasma processing apparatus for processing,
The gas supply pipes are respectively arranged at positions sandwiching a gas separation plate provided in parallel with the dielectric window inside the chamber, and the antenna means is provided at the bottom of the waveguide. The antenna means is provided so as to penetrate the dielectric window, and the position of the tip portion is provided so as to protrude from the gas separation plate, and a gap is provided between the antenna means and the gas separation plate. A plasma processing apparatus. 2. The plasma processing apparatus according to claim 1, wherein a holo-cathode discharge is generated in a gap between the antenna means and the gas separation plate. The gas supply pipe arranged above the gas separation plate supplies O ₂ gas not containing F into the chamber, while the gas supply pipe arranged below the gas separation plate supplies F. 2. The plasma processing apparatus according to claim 1, wherein the contained gas is supplied into the chamber. 4. The plasma processing apparatus according to claim 1, wherein a plurality of the antenna means are arranged at a predetermined interval. The plasma processing apparatus according to claim 1, wherein a discharge frequency of the microwave is 2.45 GHz. 6. The plasma processing apparatus according to claim 1, wherein the gas separation plate is configured by superposing a quartz plate on a Si plate or a Si plate.

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