JP4120566B2 - Plasma processing method and apparatus - Google Patents

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, plasma processing using a patch antenna type plasma source will be described with reference to FIG.

  In FIG. 7, while introducing a predetermined gas from the gas supply device 2 into the vacuum vessel 1, exhausting is performed by a turbo molecular pump 3 as an exhaust device, and the vacuum vessel 1 is kept at a predetermined pressure while being used for an antenna. By supplying high-frequency power of 100 MHz to the antenna 5 provided to protrude into the vacuum vessel 1 from the high-frequency power source 4, plasma is generated in the vacuum vessel 1 and is applied to the substrate 7 placed on the substrate electrode 6. The plasma treatment can be performed.

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

  Further, a groove-like space between the dielectric plate 11 and the dielectric ring 13 provided in the peripheral portion of the dielectric plate 11 and a groove between the antenna 5 and the conductor ring 14 provided in the peripheral portion of the antenna 5 are provided. A plasma trap 15 composed of a space is provided.

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

Moreover, the inner wall surface of the vacuum vessel 1 is covered by the inner chamber 18 to prevent the vacuum vessel 1 from being contaminated by plasma processing. After the predetermined number of substrates 7 are processed, it is considered that the dirty inner chamber 18 is replaced with a rotation part so that the maintenance work can be performed promptly.
Japanese Patent Laid-Open No. 10-12597 JP-A-7-29894 JP-A-4-225226

  However, in the plasma processing technique described in the above-described conventional example, there is a problem that the plasma spreads below the substrate electrode 6 (hatched portion in FIG. 7) depending on processing conditions.

  The plasma that has spread to the lower side of the substrate electrode 6 is completely unnecessary for processing the substrate 7, so that the processing efficiency with respect to the power supplied to the vacuum chamber 1 as a processing chamber is deteriorated. Further, the contamination of the vacuum container 1 due to the processing also spreads below the substrate electrode 6, resulting in an increase in maintenance work.

  In view of the above-described conventional problems, the present invention is a plasma processing method and apparatus in which plasma does not easily spread to a region below the antenna-side surface of the substrate electrode, power efficiency is high, and maintenance work can be reduced. The purpose is to provide.

The plasma processing method according to the first invention of the present application is provided so as to face the substrate electrode in the vacuum vessel while exhausting the gas while supplying the gas into the vacuum vessel and 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 to an antenna, wherein a plurality of layers of porous conductors are disposed below the antenna-side surface of the substrate electrode, and the inner wall surface of the vacuum vessel was covered by the inner chamber, and wherein the grounded lower side of the opening of the inner chamber.

Further, the plasma processing method of the second invention of the present application is provided so as to face the substrate electrode in the vacuum vessel while exhausting while supplying the gas into the vacuum vessel and controlling the inside of the vacuum vessel to a predetermined pressure. A plasma processing method for processing a substrate by generating a plasma in a vacuum vessel by applying high-frequency power to a prepared antenna, wherein a porous conductor and a porous radio wave absorber are provided below the antenna-side surface of the substrate electrode. There is arranged, and the inner wall surface of the vacuum vessel was covered by the inner chamber, and wherein the grounded lower side of the opening of the inner chamber.

Further, the plasma processing apparatus of the third invention of the present application is a vacuum vessel, a gas supply device for supplying gas into the vacuum vessel, an exhaust device for exhausting the inside of the vacuum vessel, and controlling the inside of the vacuum vessel to a predetermined pressure. The plasma processing apparatus includes a pressure regulating valve, a substrate electrode on which a substrate is placed in a vacuum vessel, an antenna provided to face the substrate electrode, and a high-frequency power source that supplies high-frequency power to the antenna. Te, porous conductors of a plurality of layers is disposed on the lower side of the antenna-side surface of the substrate electrode and the inner wall surface of the vacuum vessel was covered by the inner chamber and grounded lower side of the opening of the inner chamber It is characterized by that.

As is apparent from the above description, according to the plasma processing method of the first invention of the present application, the vacuum vessel is evacuated while supplying the gas to the vacuum vessel, and the vacuum vessel is controlled to a predetermined pressure. A plasma processing method for generating a plasma in a vacuum vessel by applying high-frequency power to an antenna provided opposite to an inner substrate electrode to process the substrate, wherein the substrate electrode is below a surface on the antenna side. porous conductors of the plurality of layers are arranged on the side, and the inner wall surface of the vacuum vessel was covered by the inner chamber, because of the grounded lower side of the opening of the inner chamber, good power efficiency, and maintenance work reduces A possible plasma processing method can be realized.

Further, according to the plasma processing method of the second invention of the present application, the gas is exhausted while supplying the gas into the vacuum vessel, and the substrate is opposed to 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 a plasma in a vacuum vessel by applying high frequency power to an antenna provided to process a substrate, wherein a plurality of layers of porous conductors are provided below the antenna side surface of the substrate electrode. There is arranged, and the inner wall surface of the vacuum vessel was covered by the inner chamber, wherein for a grounded lower side of the opening of the inner chamber, a plasma spread to the area below the antenna-side surface of the substrate electrode It is possible to realize a plasma processing method that hardly occurs, has high power efficiency, and can reduce maintenance work.

Furthermore, according to the plasma processing apparatus of the third 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 a predetermined pressure inside the vacuum vessel. A plasma processing apparatus comprising: a pressure regulating valve for controlling the substrate; a substrate electrode for placing a substrate in a vacuum vessel; an antenna provided facing the substrate electrode; and a high-frequency power source for supplying high-frequency power to the antenna a is, the porous conductors of the plurality of layers is disposed on the lower side of the antenna-side surface of the substrate electrode and the inner wall surface of the vacuum vessel was covered by the inner chamber, the lower side of the opening of the inner chamber Since it is grounded, it is possible to realize a plasma processing apparatus that has good power efficiency and can reduce maintenance work.

  Next, an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 shows a cross-sectional view of a plasma processing apparatus used in an embodiment of the present invention. In FIG. 1, while introducing a predetermined gas from a gas supply device 2 into a vacuum vessel 1 and exhausting it by a turbo molecular pump 3 as an exhaust device, the vacuum vessel 1 is kept at a predetermined pressure while being used for an antenna. By supplying high-frequency power of 100 MHz to the antenna 5 provided to protrude into the vacuum vessel 1 from the high-frequency power source 4, plasma is generated in the vacuum vessel 1 and is applied to the substrate 7 placed on the substrate electrode 6. The plasma treatment can be performed.

  In addition, a substrate electrode high frequency power supply 8 for supplying high frequency power to the substrate electrode 6 is provided so that ion energy reaching the substrate 7 can be controlled. The high-frequency voltage supplied to the antenna 5 is fed to the vicinity of the center of the antenna 5 by the feed rod 9.

  Further, a plurality of parts different from the center and the periphery of the antenna 5 and the surface 1 ′ facing the substrate 7 of the vacuum vessel 1 are short-circuited by a short pin 10. A dielectric plate 11 is sandwiched between the antenna 5 and the vacuum vessel 1, and the feeding rod 9 and the short pin 10 are connected to the antenna 5, the antenna high-frequency power source 4, and the antenna 5 through a through hole provided in the dielectric plate 11, respectively. Are connected to the vacuum vessel 1 ′. The surface of the antenna 5 is covered with a cover 12.

  Further, a groove-like space between the dielectric plate 11 and the dielectric ring 13 provided in the peripheral portion of the dielectric plate 11 and a groove between the antenna 5 and the conductor ring 14 provided in the peripheral portion of the antenna 5 are provided. A plasma trap 15 composed of a space is provided.

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

  The vacuum vessel 1 is grounded, and the vacuum vessel 1 is separated by a plurality of porous conductors 20 and 26 into a side where the substrate 7 is present and a side where the substrate 7 is not present (hatched portion in FIG. 1). FIG. 2 shows the planes of the porous conductors 20 and 26, and the sizes of the porous conductors 20 and 26 are drawn larger, but 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 of the porous conductors 20 and 26 are (450−220) / (2 × 1.2) ≈95 in the radial direction. An example in which the holes are provided is shown. The hole pitch is as large as 5 mm and the aperture ratio is as large as 65%. Further, the vacuum container 1 separated into two regions from the opening 21 of the inner chamber 18 (a gate for taking a wafer in and out of the vacuum container 1 and a viewing port for observing plasma emission). A ground point 22 (FIG. 1) below the opening 21 of the inner chamber 18 is grounded so that electromagnetic waves do not leak to the side without the substrate 7.

  The distance between the porous conductors 20 and 26 was 10 mm. Further, the vacuum container 1 separated into two regions from the opening 21 of the inner chamber 18 (a gate for taking a wafer in and out of the vacuum container 1 and a viewing port for observing plasma emission). A ground point 22 (FIG. 1) below the opening 21 of the inner chamber 18 is grounded so that electromagnetic waves do not leak to the side without the substrate 7.

  Further, in the plan view of the antenna 5, as shown in FIG. 3, the short pins 10 are provided at three locations, and the respective short pins 10 are equally arranged with respect to the center of the antenna 5.

  In the plasma processing apparatus shown in FIG. 1, the substrate with the platinum film was etched. 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, the plasma did not spread to the region below the substrate electrode 6 (hatched portion in FIG. 1), and a good discharge state could be obtained.

  Thus, the discharge below the substrate electrode 6 can be suppressed, and the decrease in the exhaust speed can be suppressed. This effect can be explained as follows. The strength of the electric field due to electromagnetic waves leaking to the non-substrate side of the vacuum vessel separated into two regions is reduced to about 1/10 by the porous conductor having a single layer opening ratio of 65%, and the porous layer having a single layer opening ratio of 65%. The conductor reduces the pumping speed to about 2/3. The electric field strength due to electromagnetic waves leaking to the side without the substrate of the vacuum vessel separated into two regions by the porous conductor having two layers of aperture ratio of 65% is (1/10) 2 = 1/100, and the aperture ratio of one layer is 65. %, The pumping speed is reduced to (2/3) 2 = 4/9. On the other hand, the aperture ratio of the porous conductor needs to be 20% in order to reduce the electric field strength due to electromagnetic waves leaking to the side without the substrate of the vacuum container separated into two regions by one layer of the porous conductor. There is. At this time, the exhaust speed decreases to about 1/5. Accordingly, when a two-layered porous conductor having a high aperture ratio is used, it is possible to effectively prevent the electromagnetic wave from wrapping around while minimizing the decrease in exhaust speed.

  In the embodiment of the present invention, the case where two layers of porous conductors are used has been described, but three or more layers of porous conductors can also be used. Moreover, it is possible to suppress the discharge below the substrate electrode 6 by using both the porous conductor and the radio wave absorber. Since the wave absorber is generally made of ferrite and contains iron, there is a risk of heavy metal contamination of the substrate. However, the porous conductor is porous on the side of the substrate of the vacuum vessel separated into two regions. By using a structure in which the radio wave absorber faces the non-substrate side of the vacuum vessel separated into two regions, the occurrence of contamination can be suppressed. Therefore, by using the porous conductor and the porous radio wave absorber, it is possible to effectively prevent the electromagnetic wave from wrapping around while minimizing the decrease in the exhaust speed.

  In the embodiment of the present invention, the case where the distance between the porous conductors is 10 mm has been described. However, the distance between the multi-layered porous conductors is preferably 3 mm to 30 mm. If it is less than 3 mm, there is a tendency that the electromagnetic wave wraps around to the side without the substrate. Conversely, if it exceeds 30 mm, discharge may occur in the space between the layers of the porous conductor. In addition, it is desirable that each of the multi-layer porous conductors has an aperture ratio of 50% or more. When it is less than 50%, the exhaust speed is remarkably lowered and the effect of multi-layering is small. Further, when using a porous conductor and a porous wave absorber, the distance between the porous conductor and the wave absorber is preferably 3 mm to 30 mm. If the thickness is less than 3 mm, the electromagnetic wave tends to increase toward the side without the substrate. Conversely, if it exceeds 30 mm, discharge may occur in the space between the porous conductor and the porous radio wave absorber.

  Further, it is desirable that each of the aperture ratios of the porous conductor and the radio wave absorber is 50% or more. When it is less than 50%, the exhaust speed is remarkably lowered and the effect of multi-layering is small.

  In the embodiment of the present invention, the plasma does not spread to the lower side of the antenna side surface of the substrate electrode, so that the processing efficiency with respect to the power input to the vacuum chamber 1 as the processing chamber is improved as compared with the conventional example, and the same The etching rate was improved by 5% (conventional example: 80 nm / min, embodiment of the present invention: 84 nm / min). Further, the contamination of the vacuum container 1 due to the processing did not spread below the antenna side surface of the substrate electrode, and the burden of maintenance work could be reduced.

  In the embodiment of the present invention described above, only a part of various variations with respect to the shape of the vacuum vessel, the shape and arrangement of the antenna, etc., is illustrated in the scope of the present invention. It goes without saying that various variations other than those exemplified here can be considered in the application of the present invention.

  In the embodiment of the present invention described above, a high frequency voltage is fed to the antenna through a through hole provided in the vicinity of the center of the dielectric plate, and is provided at a partial position different from the center and the periphery of the dielectric plate. Although the case where the antenna and the vacuum vessel are short-circuited by the short pin through the through hole that is substantially equally arranged with respect to the center of the plasma has been described, this configuration further enhances the plasma isotropicity. be able to. Needless to say, when the substrate is small, sufficiently high in-plane uniformity can be obtained without using short pins.

  In the embodiment of the present invention described above, 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. As described above, the plasma uniformity can be further improved by adopting such a configuration. 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.

  In the embodiment of the present invention described above, the turbo molecular pump for evacuating the vacuum vessel is disposed immediately below the substrate electrode, and the substrate side of the vacuum vessel separated into two regions is not provided. The pressure control valve for controlling the vacuum vessel to a predetermined pressure is a lift valve located immediately below the substrate electrode and directly above the turbo molecular pump. Although the case where the pressure regulating valve is located on the side of the separated vacuum vessel where the substrate is not provided has been described, as shown in FIG. 6, the turbo molecular pump 3 is not disposed directly under the substrate electrode 6, The present invention is effective even when the pressure valve 17 is not disposed immediately below the substrate electrode 6 and the pressure regulating valve 17 is not a lift valve.

  Moreover, although the case where the pressure in a vacuum vessel is 0.3 Pa was demonstrated, since the plasma below the antenna side surface of a substrate electrode is easy to generate | occur | produce as the pressure in a vacuum vessel is low, this invention is This is an effective method when the pressure in the vacuum vessel is 10 Pa or less. Furthermore, this method is particularly effective when the pressure in the vacuum vessel is 1 Pa or less.

  In addition, 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 low pressure, and the present invention is applied to all the regions. Is valid. However, as the frequency of the high-frequency power is higher, the electromagnetic wave tends to spread over a wider range, so that plasma is more easily generated below the antenna-side surface of the substrate electrode. 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.

  Further, in the embodiment of the present invention, the inner wall of the vacuum vessel is covered by the inner chamber, and electromagnetic waves do not leak from the opening of the inner chamber to the side of the vacuum vessel that is separated into two regions without the substrate. The case where the lower side from the opening of the inner chamber is grounded has been described, but this structure can more effectively prevent the generation of plasma below the antenna side surface of the substrate electrode. it can. However, in some cases, the generation of plasma below the antenna-side surface of the substrate electrode can be prevented without using such a structure.

Sectional drawing which shows the structure of the plasma processing apparatus used by embodiment of this invention The top view which shows the porous conductor used by embodiment of this invention Plan view of an antenna used in an embodiment of the present invention Sectional drawing which shows a structure at the time of applying this invention to an inductively coupled plasma source system plasma processing apparatus Sectional drawing which shows a structure at the time of applying this invention to a surface wave plasma source system plasma processing apparatus Sectional drawing which shows the structure of the plasma processing apparatus which is a modification of embodiment of this invention Sectional drawing which shows the structure of the plasma processing apparatus used by the prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Gas supply apparatus 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 Feed rod 10 Short pin 11 Dielectric plate 12 Cover 13 Dielectric ring 14 Conductor ring 15 Plasma trap 16 Exhaust port 17 Pressure regulating valve 18 Inner chamber 19 Strut 20 Porous conductor 21 Opening 22 Grounding point 26 Porous conductor

Claims (3)

By supplying high-frequency power to an antenna provided facing the substrate electrode in the vacuum vessel while exhausting while supplying gas into the vacuum vessel and controlling the inside of the vacuum vessel to a predetermined pressure, a vacuum is obtained. A plasma processing method for generating a plasma in a container to process a substrate, wherein a plurality of layers of porous conductors are disposed below the antenna side surface of the substrate electrode, and an inner wall of the vacuum container is formed in an inner chamber plasma processing method covering, and wherein the grounded lower side of the opening of the inner chamber by. By supplying high-frequency power to an antenna provided facing the substrate electrode in the vacuum vessel while exhausting while supplying gas into the vacuum vessel and controlling the inside of the vacuum vessel to a predetermined pressure, a vacuum is obtained. A plasma processing method for generating a plasma in a container to process a substrate, wherein a porous conductor and a porous radio wave absorber are disposed below the antenna side surface of the substrate electrode, and the inner wall surface of the vacuum container is covered by the inner chamber, the plasma processing method characterized by grounded lower side of the opening of the inner chamber. 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, a pressure regulating valve that controls the inside of the vacuum vessel to a predetermined pressure, and a substrate placed in the vacuum vessel A plasma processing apparatus comprising: a substrate electrode to be mounted; an antenna provided opposite to the substrate electrode; and a high-frequency power source for supplying high-frequency power to the antenna, wherein the substrate electrode is below the antenna-side surface. the porous conductors of the plurality of layers are arranged, and a plasma processing apparatus characterized by the inner wall surface of the vacuum vessel was covered by the inner chamber and grounded lower side of the opening of the inner chamber.

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