JP2004146838A - Method and device for plasma treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for plasma treatment by which the expansion of plasma to an area on the downstream side of a substrate electrode is made to hardly occur, and power efficiency is improved and, in addition, maintenance work is reduced. <P>SOLUTION: Plasma is generated in a vacuum vessel (1) by impressing high-frequency power of 100 Khz to 3 GHz in frequency upon an antenna (5) provided to face the substrate electrode (6) in the vessel (1), by controlling the inside of the vessel (1) to a prescribed pressure by exhausting the vessel (1) while a gas is supplied to the vessel (1). At that time, the vessel (1) is grounded, and a substrate (7) is treated in a state where the vessel (1) is divided into the substrate (7) existing side and the substrate (7) nonexisting side by a wave absorber (23) having many holes. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a plasma processing method and apparatus used for manufacturing electronic devices such as semiconductors and micromachines.

Hereinafter, as an example of a conventional plasma processing method, a plasma processing using a patch antenna type plasma source will be described with reference to FIG. In FIG. 6, while a predetermined gas is introduced from a gas supply device 2 into a vacuum container 1, the gas is exhausted by a turbo-molecular pump 3 as an exhaust device. By supplying high-frequency power of 100 MHz to the antenna 5 protruding into the vacuum vessel 1 by the high-frequency power supply 4, plasma is generated in the vacuum vessel 1 and the plasma is generated on the substrate 7 placed on the substrate electrode 6. To perform a plasma treatment.

Also, a high-frequency power supply 8 for the substrate electrode for supplying high-frequency power to the substrate electrode 6 is provided, so that the ion energy reaching the substrate 7 can be controlled. The high-frequency voltage supplied to the antenna 5 is supplied to the vicinity of the center of the antenna 5 by the power supply rod 9. Further, a plurality of portions different from the center and the periphery of the antenna 5 and the surface 1 ′ of the vacuum vessel 1 facing the substrate 7 are short-circuited by the short pins 10. A dielectric plate 11 is sandwiched between the antenna 5 and the vacuum vessel 1, and the feeder rod 9 and the short pin 10 are respectively connected to the antenna 5, the antenna high-frequency power supply 4, and the antenna 5 through through holes provided in the dielectric plate 11. And the vacuum vessel 1 '. The surface of the antenna 5 is covered with a cover 12.

Further, a groove-shaped space between the dielectric plate 11 and a dielectric ring 13 provided around the dielectric plate 11 and a groove between the antenna 5 and a conductor ring 14 provided around the antenna 5 are provided. There is provided a plasma trap 15 composed of a space in the shape of a circle.

The turbo molecular pump 3 and the exhaust port 16 are arranged directly below the substrate electrode 6, and a pressure regulating valve 17 for controlling the vacuum vessel 1 to a predetermined pressure is provided immediately below the substrate electrode 6 and the turbocharger. The elevating valve is located immediately above the molecular pump 3.

Further, the inner wall surface of the vacuum vessel 1 is covered by the inner chamber 18 to prevent the vacuum vessel 1 from being stained by the plasma processing. After the predetermined number of substrates 7 have been processed, the dirty inner chamber 18 is replaced with a rotation part so that maintenance work can be promptly performed.
JP-A-10-12597 JP-A-7-29894 JP 2000-91315 A JP-A-2000-195842 JP-A-4-225226

However, in the plasma processing described in the conventional example, there is a problem that, depending on the processing conditions, the plasma spreads downstream of the substrate electrode 6 (hatched portion in FIG. 6).

(4) Since the plasma spread to the downstream is completely unnecessary for processing the substrate 7, the processing efficiency is deteriorated with respect to the power supplied to the vacuum chamber 1 as a processing chamber. In addition, the contamination of the vacuum vessel 1 due to the processing also spreads downstream, resulting in an increase in maintenance work.

The present invention has been made in view of the above-described conventional problems, and provides a plasma processing method and apparatus in which plasma is hardly spread to a region downstream of a substrate electrode, power efficiency is high, and maintenance work can be reduced. The purpose is.

In the plasma processing method according to the first invention of the present application, the gas is exhausted while supplying gas into the vacuum vessel, and the antenna provided to face the substrate electrode in the vacuum vessel while controlling the inside of the vacuum vessel to a predetermined pressure. A plasma processing method for processing a substrate by generating plasma in a vacuum vessel by applying high-frequency power having a frequency of 100 kHz to 3 GHz, wherein the vacuum vessel is grounded and has a plurality of holes. The method is characterized in that the substrate is processed in a state where the vacuum container is separated into a side with the substrate and a side without the substrate by a body.

Further, the plasma processing apparatus of the second invention of the present application controls the vacuum vessel, a gas supply device that supplies gas into the vacuum vessel, an exhaust device that evacuates the vacuum vessel, and controls the inside of the vacuum vessel to a predetermined pressure. Plasma processing comprising a pressure regulating valve, a substrate electrode for mounting a substrate in a vacuum vessel, an antenna provided to face the substrate electrode, and a high-frequency power supply for supplying high-frequency power having a frequency of 100 kHz to 3 GHz to the antenna. The apparatus is characterized in that the vacuum vessel is grounded, and the vacuum vessel is separated into a side without a substrate and a side without a substrate by a radio wave absorber provided with a number of holes.

At this time, a dielectric plate is provided between the vacuum container and the antenna, the antenna and the dielectric plate have a structure protruding into the vacuum container, and a through hole provided near the center of the dielectric plate. High-frequency voltage to the antenna, and short-circuit the vacuum vessel and the antenna through a through hole that is provided at a position different from the center and the periphery of the dielectric plate, and is arranged approximately equally to the center of the antenna. Preferably, it is shorted by a pin.

The plasma processing apparatus according to the third aspect of the present invention includes a grounded 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 a predetermined pressure inside the vacuum container. A pressure regulating valve, a substrate electrode for placing a substrate in a vacuum vessel, an antenna provided to face the substrate electrode, and a high frequency power supply for supplying high frequency power of 100 kHz to 3 GHz to the antenna. A plasma processing apparatus comprising: a porous conductor having substantially the entire outer periphery grounded; and a vacuum vessel separated by a porous electromagnetic wave absorber into a side with a substrate and a side without a substrate.

At this time, it is preferable that the porous conductor faces the side where the substrate of the vacuum container separated into the two regions is present, and the porous electromagnetic wave absorber faces the side where the substrate of the vacuum container separated into the two regions is not present. It is.

As is clear from the above description, according to the plasma processing method of the first invention of the present application, the gas is exhausted while supplying the gas inside the vacuum vessel, and the inside of the vacuum vessel is controlled while controlling the inside of the vacuum vessel to a predetermined pressure. A plasma processing method for generating plasma in a vacuum vessel by applying high-frequency power having a frequency of 100 kHz to 3 GHz to an antenna provided to face a substrate electrode and treating a substrate, wherein the vacuum vessel is grounded; In addition, since the substrate is processed in a state where the vacuum vessel is separated into the side with the substrate and the side without the substrate by a radio wave absorber provided with a large number of holes, the plasma efficiency is high and the maintenance work can be reduced. A processing method can be realized.

According to the plasma processing apparatus of the second invention of the present application, a vacuum vessel, a gas supply device that supplies gas into the vacuum vessel, an exhaust device that exhausts the inside of the vacuum vessel, and the inside of the vacuum vessel is maintained at a predetermined pressure. A pressure regulating valve to be controlled, a substrate electrode for placing the substrate in a vacuum vessel, an antenna provided to face the substrate electrode, and a high-frequency power supply for supplying high-frequency power having a frequency of 100 kHz to 3 GHz to the antenna. A plasma processing apparatus, wherein the vacuum vessel is grounded, and for processing a substrate in a state where the vacuum vessel is separated into a side with a substrate and a side without a substrate by a radio wave absorber provided with a number of holes. In addition, it is possible to realize a plasma processing apparatus in which plasma is hardly spread to a region downstream of the substrate electrode, power efficiency is high, and maintenance work can be reduced.

Further, according to the plasma processing apparatus of the third invention of the present application, a grounded 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 Pressure regulating valve, a substrate electrode for mounting a substrate in a vacuum vessel, an antenna provided opposite to the substrate electrode, and a high-frequency power supply for supplying high-frequency power having a frequency of 100 kHz to 3 GHz to the antenna A plasma processing apparatus comprising: a porous conductor having substantially the entire outer periphery grounded; and a substrate processed in a state in which the vacuum vessel is separated into a side having no substrate and a side having no substrate by a porous electromagnetic wave absorber. Therefore, it is possible to realize a plasma processing apparatus that has good power efficiency and can reduce maintenance work.

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

In FIG. 1, while a predetermined gas is introduced from a gas supply device 2 into a vacuum vessel 1, the gas is exhausted by a turbo-molecular pump 3 as an exhaust device. By supplying high-frequency power of 100 MHz to the antenna 5 protruding into the vacuum vessel 1 by the high-frequency power supply 4, plasma is generated in the vacuum vessel 1 and the plasma is generated on the substrate 7 placed on the substrate electrode 6. To perform a plasma treatment.

Also, a high-frequency power supply 8 for the substrate electrode for supplying high-frequency power to the substrate electrode 6 is provided, so that the ion energy reaching the substrate 7 can be controlled. The high-frequency voltage supplied to the antenna 5 is supplied to the vicinity of the center of the antenna 5 by the power supply rod 9. Further, a plurality of portions different from the center and the periphery of the antenna 5 and the surface 1 ′ of the vacuum vessel 1 facing the substrate 7 are short-circuited by the short pins 10. A dielectric plate 11 is sandwiched between the antenna 5 and the vacuum vessel 1, and the feeder rod 9 and the short pin 10 are respectively connected to the antenna 5, the antenna high-frequency power supply 4, and the antenna 5 through through holes provided in the dielectric plate 11. And the vacuum vessel 1 '.

表面 The surface of the antenna 5 is covered with the cover 12. Further, a groove-shaped space between the dielectric plate 11 and a dielectric ring 13 provided around the dielectric plate 11 and a groove between the antenna 5 and a conductor ring 14 provided around the antenna 5 are provided. There is provided a plasma trap 15 composed of a space in the shape of a circle.

The turbo molecular pump 3 and the exhaust port 16 are arranged directly below the substrate electrode 6, and a pressure regulating valve 17 for controlling the vacuum vessel 1 to a predetermined pressure is provided immediately below the substrate electrode 6 and the turbocharger. The elevating valve is located immediately above the molecular pump 3. Further, the inner wall of the vacuum vessel 1 is covered by the inner chamber 18 to prevent the vacuum vessel 1 from being contaminated by the plasma processing. After the predetermined number of substrates 7 have been processed, the dirty inner chamber 18 is replaced with a rotation part so that maintenance work can be promptly performed. The substrate electrode 6 is fixed to the vacuum vessel 1 by four columns 19.

(4) The vacuum vessel 1 is grounded, and the vacuum vessel 1 is separated by a radio wave absorber 23 into a side with the substrate 7 and a side without the substrate 7 (hatched portion in FIG. 1). As the electromagnetic wave absorber 23, one using eddy current loss such as ferrite can be used.

(2) As shown in the plan view of the plasma processing apparatus in FIG. 2, the pitch of the holes provided in the radio wave absorber 23 is 12 mm. For the sake of simplicity, the size of the holes is drawn larger in FIG. 2, and the number of holes is actually larger. Typically, the diameter of the substrate electrode 6 is 220 mm, the inner diameter of the inner chamber 18 is 450 mm, and the holes provided in the radio wave absorber 23 are (450−220) / (2 × 12) ≒ 9 holes in the radial direction. Is provided.

Further, the vacuum vessel 1 separated into two regions from an opening 21 of the inner chamber 18 (a gate for taking a wafer in and out of the vacuum vessel 1 and a viewing port for observing plasma emission). In order to prevent the electromagnetic wave from leaking to the side where the substrate 7 is not provided, a grounding point 22 (FIG. 1) downstream of the opening 21 of the inner chamber 18 is provided.

FIG. 3 shows a plan view of the antenna 5.

In FIG. 3, the short pins 10 are provided at three places, and the short pins 10 are equally arranged with respect to the center of the antenna 5.

に お い て In the plasma processing apparatus shown in FIGS. 1 and 2, the substrate with a platinum film was etched. The etching conditions are argon / chlorine = 260/20 sccm, pressure = 0.3 Pa, antenna power = 1500 W, and substrate electrode power = 400 W. When etching was performed under such conditions, plasma did not spread to a region downstream of the substrate electrode 6 (hatched portion in FIG. 1), and a favorable discharge state could be obtained.

放電 It is considered that the reason why the downstream discharge can be suppressed is that the radio wave absorber 23 shields the high-frequency electromagnetic wave (absorbs and attenuates the electromagnetic wave) and stops the electromagnetic wave from reaching the downstream. In the second embodiment of the present invention, there is no need to ground the outer peripheral portion of the radio wave absorber 23, and there is an advantage that the degree of freedom in design is increased.

In the embodiment of the present invention, since the plasma does not spread to the downstream, the processing efficiency with respect to the power supplied to the vacuum chamber 1 as the processing chamber is improved as compared with the conventional example, and the etching rate is compared under the same etching condition. Was improved by 4% (conventional example: 82 nm / min, second embodiment of the present invention: 85 nm / min). In addition, the contamination of the vacuum vessel 1 due to the processing did not spread to the downstream, so that the burden of maintenance work could be reduced.

Also, in the embodiment of the present invention, only a part of various variations regarding the shape of the vacuum vessel, the shape and the arrangement of the antenna, etc. in the applicable range of the present invention are exemplified. In applying the present invention, it goes without saying that various variations other than those exemplified here are possible.

Also, in the embodiment of the present invention, a high-frequency voltage is supplied to the antenna through a through hole provided near the center of the dielectric plate, provided at a position different from the center and the periphery of the dielectric plate, and The case where the antenna and the vacuum vessel are short-circuited by the short pin through the through-holes substantially equidistant from the center has been described, but by adopting such a configuration, the isotropy of the plasma can be further improved. Can be. Needless to say, when the substrate is small, sufficiently high in-plane uniformity can be obtained without using short pins.

Further, in the embodiment of the present invention, the case where the substrate is processed in a state where the plasma distribution on the substrate is controlled by the annular and groove-shaped plasma trap provided between the antenna and the vacuum vessel has been described. With such a configuration, the uniformity of the plasma can be further improved. Needless to say, when the substrate is small, sufficiently high in-plane uniformity can be obtained without using a plasma trap.

The present invention is also effective when the coil 24 in the inductively coupled plasma source shown in FIG. 4 or the electromagnetic wave radiation antenna 25 in the surface wave plasma source shown in FIG. 5 is used as the antenna.

Further, in the embodiment of the present invention, a turbo-molecular pump for evacuating the vacuum vessel is disposed immediately below the substrate electrode, and is evacuated to the substrate-free side of the vacuum vessel separated into two regions. The opening is located, and the pressure regulating valve for controlling the vacuum vessel to a predetermined pressure is an elevating valve located immediately below the substrate electrode and immediately above the turbo molecular pump, and is separated into two regions. Although the case where the pressure regulating valve is located on the side of the vacuum vessel where no substrate is provided has been described, as shown in FIG. 6, the turbo molecular pump 3 is not disposed immediately below the substrate electrode 6 and the pressure regulating valve 17 is provided. The present invention is effective even when the pressure regulating valve 17 is not arranged directly below the substrate electrode 6 and the pressure regulating valve 17 is not an elevating valve.

Also, the case where the pressure in the vacuum vessel is 0.3 Pa has been described. However, the lower the pressure in the vacuum vessel, the more easily downstream plasma is generated. Is an effective method. Further, it is a particularly effective method when the pressure in the vacuum vessel is 1 Pa or less.

Although the case where the frequency of the high-frequency power applied to the antenna is 100 MHz has been described, high-frequency power of 100 kHz to 3 GHz can be used for the plasma treatment at a low pressure, and the present invention is applied to all the regions. Is valid. However, the higher the frequency of the high-frequency power, the more the electromagnetic wave tends to spread over a wider range, so that downstream plasma is more likely to be generated. Therefore, the present invention is an effective method when the frequency of the high-frequency power is high, particularly when the frequency is 50 MHz to 3 GHz.

Furthermore, in the embodiment of the present invention, the case where the pitch of the holes provided in the radio wave absorber is 12 mm has been described. However, in order to suppress the transmission of the electromagnetic wave, the hole pitch is set to be sufficiently smaller than the wavelength of the electromagnetic wave. There is a need. Unlike using punched metal or conductor mesh, when using a radio wave absorber, the electromagnetic wave penetrates into the radio wave absorber itself rather than through the holes and attenuates inside the radio wave absorber, so the radio wave absorber May be larger than in the case of using a punched metal or a conductor mesh. The larger the pitch of the holes, the more advantageous in the exhaust characteristics. According to our experiments, when the pitch of the holes provided in the radio wave absorber is p, the frequency of the high-frequency power applied to the antenna is f, and the speed of light is c,
p <0.02 × c / f
It has been found that when the following relational expression is satisfied, plasma generation downstream can be suppressed under a considerably wide range of discharge conditions. However, in order to more reliably suppress the downstream plasma generation, when the pitch of the holes provided in the radio wave absorber is p, the frequency of the high-frequency power applied to the antenna is f, and the speed of light is c,
p <0.005 × c / f
It is desirable to satisfy the following relational expression.

Further, in the embodiment of the present invention, the inner wall of the vacuum chamber is covered with the inner chamber, and the electromagnetic wave does not leak from the opening of the inner chamber to the side of the vacuum chamber separated into two regions without the substrate. The case where the downstream side is grounded from the opening of the inner chamber has been described, but by adopting such a structure, the generation of plasma downstream can be more effectively prevented. However, in some cases, even without such a structure, the generation of plasma downstream can be prevented.

Sectional view showing the configuration of the plasma processing apparatus used in the embodiment of the present invention. FIG. 2 is a plan view illustrating a configuration of a plasma processing apparatus used in an embodiment of the present invention. Plan view of an antenna used in an embodiment of the present invention Sectional drawing which shows the structure at the time of applying this invention to the inductively coupled plasma source type plasma processing apparatus. Sectional drawing which shows the structure at the time of applying this invention to the surface wave plasma source type plasma processing apparatus. Sectional view showing the configuration of the plasma processing apparatus used in the conventional example

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Gas supply device 3 Turbo molecular pump 4 High frequency power supply for antenna 5 Antenna 6 Substrate electrode 7 Substrate 8 High frequency power supply for substrate electrode 9 Power supply rod 10 Short pin 11 Dielectric plate 12 Cover 13 Dielectric ring 14 Conductor ring 15 Plasma trap Reference Signs List 16 exhaust port 17 pressure regulating valve 18 inner chamber 19 column 21 opening 22 grounding point 23 radio wave absorber

Claims (5)

Exhausting while supplying gas into the vacuum vessel, and applying high-frequency power having a frequency of 100 kHz to 3 GHz to an antenna provided to face the substrate electrode in the vacuum vessel while controlling the inside of the vacuum vessel to a predetermined pressure. A plasma processing method for generating plasma in a vacuum vessel and processing a substrate,
The plasma processing method, wherein the vacuum vessel is grounded, and the substrate is treated in a state where the vacuum vessel is separated into a side having no substrate and a side having no substrate by a radio wave absorber provided with a number of holes. . 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 pressure regulating valve for controlling the inside of the vacuum container to a predetermined pressure, and placing the substrate in the vacuum container A plasma processing apparatus comprising: a substrate electrode; an antenna provided to face the substrate electrode; and a high-frequency power supply that supplies high-frequency power having a frequency of 100 kHz to 3 GHz to the antenna,
The plasma processing apparatus according to claim 1, wherein the vacuum vessel is grounded, and the vacuum vessel is separated into a side having no substrate and a side having no substrate by a radio wave absorber provided with a number of holes. A dielectric plate is provided between the vacuum container and the antenna, the antenna and the dielectric plate have a structure protruding into the vacuum container, and are connected to the antenna through a through hole provided near the center of the dielectric plate. A high-frequency voltage is supplied, and the vacuum vessel and the antenna are short-circuited with a short pin through a through hole that is provided at a position different from the center and the periphery of the dielectric plate and that is arranged almost equally to the center of the antenna. 3. The plasma processing apparatus according to claim 2, wherein: A grounded 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 pressure regulating valve for controlling the inside of the vacuum container to a predetermined pressure, and a substrate in the vacuum container A plasma processing apparatus comprising: a substrate electrode to be mounted; an antenna provided to face the substrate electrode; and a high-frequency power supply that supplies high-frequency power having a frequency of 100 kHz to 3 GHz to the antenna.
A plasma processing apparatus, characterized in that a vacuum vessel is separated into a side with a substrate and a side without a substrate by a porous conductor whose outer peripheral portion is almost all grounded and a porous radio wave absorber. The porous conductor faces the non-substrate side of the vacuum container separated into two regions, and the porous electromagnetic wave absorber faces the side of the vacuum container separated into two regions. The plasma processing apparatus according to claim 4.

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