JP6317921B2 - Plasma processing equipment - Google Patents

Description

The present invention relates to a plasma processing apparatus for processing a substrate-like sample such as a semiconductor wafer disposed in a processing chamber using plasma formed in a processing chamber in a vacuum vessel, such as etching, ashing, CVD (Chemical Vapor Deposition). .

In mass production processes of semiconductor devices, plasma processing apparatuses such as plasma etching, plasma CVD, and plasma ashing apparatuses are widely used. Plasma processing is performed by irradiating a wafer placed on a wafer stage with ions or radicals in plasma generated by applying high-frequency power to the processing gas in a reduced pressure state.

In recent years, in the manufacture of semiconductor devices, the diameter of a wafer has been increased in order to improve productivity, and the plasma processing apparatus has also been increased in size. While the diameter of the wafer is increasing, the demands for improved throughput and processed shape uniformity are becoming stricter as the performance of the conventional apparatus is required. Throughput improvement can be realized, for example, by efficiently supplying ions or active species generated in the plasma generation unit to the wafer or generating active species efficiently. This is achieved by supplying ions and radicals uniformly within the wafer surface.

For example, in an ashing processing apparatus, a processing gas such as oxygen or hydrogen is turned into plasma by high-frequency power, irradiated onto the wafer, and the resist on the wafer is ashed and removed. The plasma ashing device introduces gas (O2 etc.) from the upper part of the discharge tube, and the electrons gained energy by the induction electric field generated from the antenna supplied with high frequency power collides with the supply gas, dissociates the supply gas molecules and activates. Generate seeds (such as O radicals).

The active species are irradiated to a wafer installed in the downstream region, and ashing is performed by a chemical reaction on the surface. Such a plasma ashing apparatus is often operated under relatively high power, pressure, and large flow rate conditions in order to improve throughput. Typically, the supply power is 1 to 10 kW and the internal pressure is 100 to 500 Pa. The gas flow rate supplied to the apparatus is 1 to 20 slm.

The active species involved in the process are mainly generated when high-energy electrons in the plasma collide with molecules of the processing gas and the processing gas is dissociated. Since the plasma ashing apparatus is often operated at a high pressure, the active species are diffused while being influenced by the flow of the source gas and transported to the wafer.

Therefore, in order to ensure the in-plane uniformity of a desired processing rate, it is necessary to determine the apparatus structure in consideration of the position where active species are generated by plasma and the flow of source gas. The flow of the source gas is mainly determined by the apparatus configuration such as the apparatus shape, and the apparatus parameters such as the gas flow rate supplied to the discharge tube and the pressure in the apparatus.

By adjusting the apparatus parameters, it is possible to control the in-plane uniformity of the processing rate to some extent. However, depending on the apparatus configuration, the uniformity may not be obtained only by adjusting these parameters. For example, when the diameter of the discharge tube that generates plasma is smaller than the diameter of the object to be processed, the active species generated in the discharge tube cannot sufficiently diffuse to the outer periphery of the object to be processed. The result is that the processing rate is low at the center and high at the center.

Conversely, when the discharge tube diameter is larger than the workpiece diameter, the treatment rate tends to be higher at the outer periphery of the workpiece. Therefore, in order to ensure in-plane processing rate uniformity, the diameter of the discharge tube must be determined to an appropriate value.

However, even if the discharge tube diameter is optimized under certain process conditions and the in-plane uniformity of the processing rate can be ensured, the in-plane uniformity of the processing rate will change greatly if the conditions are changed. Even if it does not improve. For example, when the gas type supplied to the apparatus is changed, the uniformity may be greatly deteriorated because the diffusion coefficient of the generated active species is different. In that case, it is necessary to optimize the discharge tube diameter again. Since it takes time and cost to change the apparatus configuration including the discharge tube diameter, it is desirable to achieve in-plane uniformity of a desired processing rate only by changing the apparatus parameters.

As an in-plane processing rate uniformity control method, for example, a technique described in Japanese Patent Publication No. 8-508852 (Patent Document 1) is known. In Patent Document 1, a non-conductive plug having a variable insertion depth that extends downward is installed in a processing space. In the above configuration, by changing the processing space volume by inserting the non-conductive plug, the gas flow can be changed and finally the in-plane uniformity of the processing rate can be improved.

In addition, in the technique described in Japanese Patent Application Laid-Open No. 2005-203209 (Patent Document 2), a configuration in which a cylindrical flow rate restrictor is disposed inside the discharge tube and a central flow channel and an outer flow channel are set in the discharge tube. It is disclosed. In plasma processing, when it is desired to control the degree of dissociation of the supply gas to produce a large number of desired active species, a gas whose degree of dissociation is to be kept low is caused to flow in the central flow path, and a gas whose degree of dissociation is to be increased is directed to the outside A technique that can generate a large number of desired active species by flowing in a path is disclosed.

Japanese National Patent Publication No. 8-508852 JP 2005-203209 JP

The prior art described above has a problem due to insufficient consideration of the following points. That is, in Patent Document 1, if the nonconductive plug is not thick, the gas rectifying effect cannot be obtained, and the uniformity cannot be controlled. In this case, since the ratio of the surface area to the processing space volume increases, the active species are lost on the plug wall surface, and the processing rate is lowered. Further, in the configuration of Patent Document 1, the uniformity of the processing rate in the in-plane circumferential direction cannot be controlled.

Further, in the technique disclosed in Patent Document 2, since the flow restrictor is cylindrical, the gas supplied from the inner flow path is supplied with almost no radial component velocity. Therefore, even if the gas flow rate supplied to the inner flow path is controlled, there is a problem that it is difficult to control the in-plane uniformity of the processing rate.

The objective of this invention is providing the plasma processing apparatus which can suppress the nonuniformity of the process of the surface of substrate-like samples, such as a semiconductor wafer.

The purpose is to form an upper part of a vacuum vessel whose inside is depressurized and a cylindrical discharge part in which plasma is formed inside, and to form the vacuum container below the discharge part and to which a wafer to be processed is placed. A processing container to be disposed; a first gas supply port disposed at an upper portion of the discharge unit for supplying a first gas for generating plasma; and wound around the periphery of the discharge unit. A plasma processing apparatus comprising: an antenna to which electric power for forming the plasma is supplied; and a stage disposed inside the processing container and below the discharge unit and on which the wafer is placed. The discharge portion has a step portion having a diameter smaller than the diameter of the wafer and having a larger diameter at a lower portion thereof connected to the processing vessel, and the center of the discharge portion above the stage. Up and down direction A second gas supply port that extends from the center side of the stage toward the outer periphery side of the gas introduction pipe that is disposed to extend radially from the center side to the outer peripheral side of the processing vessel. This is achieved by providing the gas introduction pipe provided in the above.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the plasma processing apparatus which can suppress the nonuniformity of the process of the surface of substrate-like samples, such as a semiconductor wafer.

The block diagram of the plasma processing apparatus which concerns on the 1st Example of this invention. In the Example shown in FIG. 1, it is a graph which shows the influence which the flow volume of 2nd process gas has on the distribution of the in-plane direction of the oxygen radical density on a semiconductor wafer. The block diagram of the plasma processing apparatus which concerns on the 2nd Example of this invention. The schematic of the gas introduction pipe | tube in the plasma processing apparatus which concerns on the 2nd Example of this invention.

Embodiments of the present invention will be described below with reference to the drawings.

First, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view schematically showing the configuration of a plasma apparatus according to an embodiment of the present invention.

The plasma processing apparatus according to the present embodiment includes a metal processing vessel 1 having a cylindrical processing chamber therein and constituting a vacuum vessel, and a dielectric discharge tube having a substantially cylindrical shape disposed above the processing vessel 1. 2 is provided. Further, an upper lid 3 made of a circular metal is arranged on the upper part of the discharge tube 2, and the discharge tube 2 and a processing chamber inside the processing vessel 1 connected to the discharge tube 2 and an external atmosphere are hermetically sealed. doing.

The material of the processing container 1 is preferably a material that is excellent in plasma resistance and hardly causes contamination of the wafer by heavy metal contamination or foreign matter, that is, aluminum whose surface is anodized. Alternatively, an aluminum base material coated with a material such as yttria, alumina, or silicon oxide may be used. The material of the discharge tube 2 is preferably a material having high plasma resistance, low dielectric loss, and hardly causing foreign matter or contamination, that is, quartz, alumina, yttria, or the like.

On the outside of the cylindrical outer peripheral side wall of the discharge tube 2, a coil-shaped antenna 11 wound around the discharge tube 2 and wound in a plurality of stages is disposed. Further, the inner diameter of the discharge tube 2 at the height position where the antenna 11 is disposed is smaller than the diameter of the semiconductor wafer 8 to be processed. Further, the discharge tube 2 has a configuration in which the inner diameter is larger than the upper part below the antenna 11, and in this example, there is a step in the inner diameter between the upper and lower sides.

The upper lid 3 is attached to the upper end of the discharge tube 2 through a vacuum sealing means such as an O-ring disposed so as to surround the center side on the lower surface of the outer peripheral side portion, and the inside of the discharge tube 2 to be decompressed and the atmospheric pressure. It is connected so as to keep a hermetically sealed state with a certain outside. The material of the upper lid 3 is preferably a material that is excellent in plasma resistance and hardly causes contamination of the wafer by heavy metal contamination or foreign matter, that is, aluminum whose surface is anodized. Alternatively, an aluminum base material coated with a material such as yttria, alumina, or silicon oxide may be used. Alternatively, a material having high plasma resistance, low dielectric loss, and hardly causing foreign matter or contamination, that is, quartz, alumina, yttria, or the like may be used.

The upper lid 3 is connected to first gas supply means 4 arranged outside the discharge tube 2. The first processing gas supplied from the first gas supply means 4 is rectified into a desired flow pattern by the gas rectification means 5 disposed below the upper lid 3 and then into the discharge tube 2. It is introduced from top to bottom.

Further, the first gas supply means 4 of the present embodiment is configured to supply a desired type of mixed gas. The substance constituting the first processing gas supplied from the first gas supply means 4 is appropriately selected depending on the type of film to be processed. For example, in the case of an ashing process for stripping various organic films, O2, N2, H2, Ar, He, CF4, CO2 or a mixed gas of a plurality of substances selected from these is used.

Further, in this embodiment, a substantially disc-shaped rectifying means 5 is disposed in the space inside the discharge tube 2 below the upper lid 3. The material of the rectifying means 5 is preferably a material having high plasma resistance, low dielectric loss, and unlikely to cause foreign matter or contamination, that is, quartz, alumina, yttria, or the like.

In addition, the shape of the gas rectifying means 5 is appropriately selected to be suitable for supplying the processing gas to the space inside the discharge tube 2 (discharge chamber). For example, in the case where a shower plate having a circular shape corresponding to the shape of the discharge chamber and having a plurality of through holes appropriately dispersed in a circular plane is used as the gas rectifying means 5, The non-uniformity of the supplied gas is reduced. On the other hand, in the case of a disk having a sufficiently small gap (0.5 to 20 mm in this embodiment) between the outer peripheral edge of the gas rectifying means 5 and the cylindrical inner wall of the discharge tube, Then, the processing gas is supplied from the outer peripheral side portion at the top of the discharge chamber.

Further, inside the discharge tube 2, a gas introduction tube 6 having a cylindrical shape and extending downward is disposed below the gas rectifying means 5 so as to match the discharge tube 2 and the central axis thereof. The gas introduction tube 6 is connected to the second gas supply means 7 disposed outside the discharge tube 2, and the second processing gas supplied from the second gas supply means 7 passes through the inside of the gas introduction tube 6. A second processing gas flows out in the radial direction of a plurality of flowing gas pipes and a processing chamber having a cylindrical shape inside the discharge tube 2 or the processing vessel 1 disposed below the gas introduction tube 6. And a gas outlet 20.

The gas outlet 20 of the present embodiment is arranged in a ring shape in which one ring shape or a plurality of circular arc shapes are arranged in an annular shape in the horizontal direction in the figure surrounding the tip of the gas introduction pipe 6. It is an opening, and the second processing gas that has flowed out of the opening is configured to suppress unevenness in the flow rate or flow velocity in the circumferential direction. Further, the gas outlet 20 is installed below the stepped portion at the bottom of the discharge tube 2. The shape of the gas introduction tube 6 is preferably a cylindrical shape in which the discharge chamber and the axis coincide with each other in order that the gas flow passing around the gas introduction tube 6 in the discharge chamber becomes more uniform around the central axis of the cylinder. .

The material of the gas introduction tube 6 is preferably a material that has high plasma resistance, low dielectric loss, and is unlikely to cause foreign matter or contamination, that is, quartz, alumina, yttria, or the like. Alternatively, a metal may be used if it has high plasma resistance and does not cause foreign matter or contamination.

The type of the second processing gas supplied from the second gas supply means 7 may be the same type as the first processing gas, but is not limited thereto. For example, for example, He, Ar, or N2 may be used as a gas that changes the flow direction of the first processing gas and does not adversely affect the substrate processing.

Inside the processing chamber, a wafer stage having a cylindrical shape, the central axis of which is arranged to coincide with the axis of the discharge tube 2, and the semiconductor wafer 8 as the object to be processed is mounted on the mounting surface which is the upper surface thereof. 9 and a circular exhaust port disposed directly below the wafer stage 9 and having its central axis aligned with the discharge tube 2 or the wafer stage 9 are disposed.

The material of the wafer stage 9 is preferably aluminum or titanium alloy whose surface is anodized. Further, the wafer stage 9 is provided with a heater or chiller (not shown), and in this example, the temperature of the wafer stage 9 can be adjusted in a range from 20 ° C. to 400 ° C. Furthermore, lift pins for raising and lowering the semiconductor wafer 8 (not shown) to be placed on or separated from the placement surface are provided inside the wafer stage 9 so as to be housed therein.

The exhaust port is connected to a vacuum exhaust means 10 disposed below the processing container 1. In this embodiment, as the vacuum exhaust means 10 for exhausting the inside of the processing chamber, the cross-sectional area of the exhaust pump that is disposed between the vacuum pump and the vacuum pump and the exhaust port and communicates therewith is increased or decreased. And a variable conductance valve for adjusting the exhaust flow rate.

By increasing or decreasing the cross-sectional area of the flow path by the variable conductance valve in a state where the first or second processing gas having a desired flow rate is flowed into the discharge tube 2 or the processing chamber, the inside of the discharge tube 2 or the processing chamber is processed. Is adjusted to a desired pressure suitable for Further, a gate (not shown) that is an opening for loading and unloading the semiconductor wafer 8 is disposed on the side surface of the processing container 1, and is disposed in a transport container that is another vacuum container connected to the side wall of the processing container 1. An unprocessed semiconductor wafer 8 is carried into the processing chamber via a gate by a transfer device such as a robot arm, or the semiconductor wafer 8 processed in the processing chamber is unloaded from the processing chamber.

The second processing gas supplied from the second gas supply means 7 passes through the gas conduit inside the gas introduction pipe 6 and goes out of the radial direction from the gas outlet 20 to the discharge chamber or processing chamber inside the discharge tube 2. The gas is introduced radially around the gas introduction tube 6 with the velocity of the direction component, and diffuses radially from the central portion of the semiconductor wafer 8 toward the outer periphery in the processing chamber below the stepped portion below the discharge tube 2. Then, after passing through the outer peripheral edge of the semiconductor wafer 8 and descending downward in the space between the outer peripheral side wall of the wafer stage 9 and the inner side wall of the cylindrical processing chamber, the wafer is discharged from the exhaust port. In the embodiment, by providing such a configuration of the gas introduction pipe 6, a flow of gas and particles from the central side toward the outer peripheral side is formed in the space above the semiconductor wafer 8 in the processing chamber and formed in the discharge chamber. The active species present in the plasma can be effectively transported to the outer periphery of the semiconductor wafer 8 disposed in the processing chamber inside the processing container 1 below the discharge tube 2.

Outside the discharge tube 2, an antenna 11 and a matching circuit 12 and a high-frequency power source 13 that are electrically connected to one end of the antenna 11 are arranged, and the high-frequency power from the high-frequency power source 13 is sent to the matching circuit 12 and the antenna 11. And a closed circuit with a grounded end (earth).

As a material of the antenna 11 of the present embodiment, copper which is a general material having a small electric resistance value is used. Also, silver or gold plating may be applied to the copper surface for the purpose of improving high frequency characteristics.

Further, the matching circuit 12 is not always necessary, and if there is a means that can achieve impedance matching without the matching circuit 12, that means may be used. The power supplied from the high frequency power supply 13 of this embodiment is appropriately selected to have a frequency between 400 kHz and 40 MHz.

In the plasma processing apparatus of this example, the high-frequency power from the high-frequency power source 13 is supplied to the antenna 11 while the processing gas suitable for processing the semiconductor wafer 8 in the processing chamber is introduced from the first gas supply means 4 into the processing chamber. The processing gas is excited using an electric field by electromagnetic induction formed by supplying the plasma, and plasma 14 containing active species is generated in a cylindrical space inside the discharge tube 2. The generated active species are introduced from the first processing gas introduced below the discharge tube 2 through the rectifying means 5 and the gas outlet 20 at the lower part of the gas introduction tube 6 toward the radially outward direction of the processing chamber. It reaches the upper surface of the semiconductor wafer 8 while diffusing under the influence of the flow of the second processing gas supplied so as to have a component.

The membrane is processed by the interaction between the active species and the material constituting the membrane to be treated having a membrane structure having a plurality of membrane layers arranged on the surface thereof. Note that arrows 16 and 17 in FIG. 1 schematically show examples of the flow directions of the first and second processing gases, respectively.

Next, the result of processing of the semiconductor wafer 8 performed using the plasma processing apparatus according to the present embodiment will be described with reference to FIG. In particular, it will be described that the uniformity of the etching process speed (rate) in the in-plane direction of the semiconductor wafer 8 is improved. FIG. 2 shows the effect of the flow rate of the second processing gas supplied to the gas introduction pipe 6 on the oxygen radical density distribution on the wafer, that is, the distribution in the in-plane direction of the processing rate in the embodiment shown in FIG. It is a graph to show.

In this figure, the horizontal axis indicates the position (distance) in the radial direction from the center of the semiconductor wafer 8, and the vertical axis indicates the density of oxygen radicals on the semiconductor wafer 8. In this example, oxygen is supplied to the discharge tube 2 and the processing chamber as the first and second processing gases, and the advection diffusion equation of the active species is solved with the first processing gas flow rate set to 10 slm and reaches the semiconductor wafer 8. The calculation result of oxygen radical density distribution is shown.

As shown by the dotted line in FIG. 2, when the flow rate of the second processing gas is 0.01 slm, the distribution of radical density in the radial direction of the semiconductor wafer 8 is high at the center and low at the outer peripheral side. It turns out that it becomes distribution of. In addition, as shown in FIG. 2 by the one-dot chain line, when the flow rate of the second processing gas is increased to 0.1 slm, the processing rate in the outer peripheral portion is relatively higher than that in the central portion, and the semiconductor wafer It can be seen that the non-uniformity in the radial direction of the amount of oxygen radicals reaching 8 is reduced, that is, the density distribution of the semiconductor wafer 8 is made uniform. As shown by the solid line in FIG. 2, when the second process gas flow rate is further increased to 0.5 slm, the density distribution of radicals on the semiconductor wafer 8 is higher on the outer peripheral side than on the central side. It can be seen that the outer height can be distributed.

In this way, by adjusting the flow rate of the second processing gas discharged outwardly in the radial direction from the gas introduction tube 6, the gas flow in the discharge tube 2 and the processing chamber is changed, and the processing rate of the semiconductor wafer 8 is changed. It can be seen that the distribution in the in-plane direction can be adjusted. The adjustment of the distribution is realized by diffusing active species in the processing chamber by the flow of the second processing gas outward in the radial direction of the semiconductor wafer 8, and adjusting the degree of diffusion as desired.

Further, in order to effectively control the diffusion of the active species by the second processing gas, in the present embodiment, the position of the first processing gas is lower than the generation position of the active species in the discharge tube 2. A gas outlet 20 of the gas introduction pipe 6 is disposed at a downstream position in the flow direction. In particular, in this example, the gas outlet 20 is disposed below the center of the height of the antenna 11.

Furthermore, in order to realize in-plane uniformity at a higher processing rate, plasma is formed in the discharge tube 2 in a state in which the first processing gas is supplied without supplying the second processing gas, and the semiconductor wafer. The processing rate when processing No. 8 needs to be a medium-high distribution. In order to realize this, in this example, the inner diameter of the discharge tube 2 is made smaller than the diameter of the wafer 8, or the first processing gas is placed above the space inside the discharge tube 2 (discharge space). The rectifying means 5 may be used so that active species flow downward from the outer peripheral side toward the center.

A modification of the above embodiment will be described with reference to FIG. FIG. 3 is a longitudinal sectional view showing an outline of a configuration of a plasma processing apparatus according to a modification of the embodiment shown in FIG.

In this example, an example having a configuration of the rectifying means 5 or the gas introduction pipe 6 different from the embodiment is shown. In this example, the processing rate can be increased and the uniformity in the circumferential direction can be improved as well as the processing rate in the radial direction of the semiconductor wafer 8.

The basic configuration of this example is the same as that of the embodiment, and the description of the equivalent configuration is omitted. In FIG. 3, the gas rectifying means 5 arranged inside the discharge tube 2 has a cylindrical member 15 in which the gap between the outer peripheral edge and the inner wall surface of the discharge tube is arranged with a value in the range of 0.5 to 20 mm. have.

Further, below the member 15 in the discharge tube 2, a gas introduction tube 6 having a cylindrical shape connected to and extending downward is disposed. In this example, in order to reduce the amount of active species in the plasma formed in the discharge chamber that disappears in contact with the wall surface of the gas introduction tube 6 or transitions from the excited state to the stable state, A smaller diameter or surface area is desirable.

Further, the first processing gas flows through the gap between the member 15 and the inner wall of the discharge tube 2 along the inner wall surface instead of the center portion of the discharge tube 2, and the high gas corresponding to each winding of the antenna 11. It is supplied to the region (plasma formation region) of the plasma 14 having the highest density formed at this position. In this example, the lower end of the cylindrical member 15 in the discharge chamber is positioned below the highest winding position in the vertical direction of the antenna 11.

With the above configuration, the flow rate of the first processing gas passing through the region of the plasma 14 can be increased, and the processing gas can be efficiently dissociated to generate active species efficiently. Furthermore, by increasing the diameter of the member 15 and narrowing the flow path through which the first processing gas passes, the velocity of the first processing gas flowing into the discharge tube 2 and flowing downward in the discharge chamber can be increased. The active species is efficiently supplied onto the semiconductor wafer 8 by increasing the height.

Further, in order to efficiently supply the first processing gas to the region of the plasma 14, the lower end portion of the member 15 is 1 to 5 cm above the height center in the vertical direction of the antenna 11 having a plurality of turns. It is desirable to be. If the lower end of the member 15 is at a position below the center of the height of the antenna 11, the discharge in the region of the plasma 14 is physically hindered, making it difficult to generate active species. Even if it is generated in the area 14, it disappears or changes its state in contact with the surface of the member 15 along a path that diffuses and moves downward.

Moreover, the member 15 does not necessarily need to be comprised with one structure like said example, and may be comprised from another shape and several members. For example, a plurality of baffle plates made of a disc having a gap between the outer peripheral edge and the inner wall surface of the discharge tube 2 of about 0.5 to 20 mm are arranged with a gap in the vertical direction. May be.

Next, the configuration of the gas introduction pipe 6 used in this example will be described with reference to FIG. FIG. 4 is a perspective view schematically illustrating the outline of the configuration of the gas introduction pipe according to the modification shown in FIG.

This figure shows a configuration in which a plurality of (three in this example) flow paths for the second processing gas supplied from the second gas supply means 7 are arranged inside the gas introduction pipe 6. Note that the number of flow paths in the gas introduction pipe 6 connected to the second gas supply means 7 is not necessarily three.

A plurality of flow paths, each having a gas outlet 20 corresponding to each flow path, is opened radially outwardly around the axis at the lower part of the gas introduction pipe 6 and the second processing gas flowing out is directed radially outward. It is necessary that the flow rate of each gas flow path be adjustable independently so as to have components, and the number and arrangement of gas flow paths to be arranged or used according to the content of processing required. Is selected. Further, the flow rate of the second processing gas supplied to each flow path is independently adjusted with respect to a plurality of flow paths installed in the gas introduction pipe 6, so that the circumferential direction of the processing rate of the semiconductor wafer 8 is increased. Non-uniformity can be reduced.

In recent years, it has been demanded to further reduce the number of foreign substances adhering to the semiconductor wafer 8. It is known that when fine particle foreign matter generated from foreign matter generation sources inside and outside the plasma processing apparatus adheres to a fine pattern on a wafer, defects such as disconnection occur, resulting in a decrease in yield.

For example, when the semiconductor wafer 8 is transported, the generation source of the foreign matter adhering to the semiconductor wafer 8 is switched between processing conditions such as a gas type, a gas flow rate, an internal pressure, and an electric power for performing discharge. It is assumed that a sudden change in pressure in the space inside the apparatus occurs as a trigger. A plasma processing apparatus or a plasma processing method that prevents such foreign matter from adhering to the semiconductor wafer 8 is desired.

Such foreign matter continues to supply the second processing gas from the start of the processing of the semiconductor wafer 8 to the end of the processing to maintain the flow of gas and particles inside the processing chamber or the discharge chamber. Can be suppressed. This is because the second processing gas flows outward from the central side in the radial direction of the semiconductor wafer 8, so that the particles having adhesion floating in the processing chamber above the semiconductor wafer 8 are the second processing gas. This is because the viscous force of the fluid causes the gas to flow from the central side to the outer peripheral side of the semiconductor wafer 8 and further lowers the outer periphery of the wafer stage 9 to be exhausted.

As such a second processing gas, as a gas that does not adversely affect the processing of the film to be processed of the semiconductor wafer 8, for example, a chemically inert gas such as He, Ar, N2, Kr, Xe It is desirable to use etc. By using a chemically inert gas as the second processing gas, for example, by a reaction in the gas phase with the first processing gas or a reaction product generated during the plasma processing. Generation of a depositing (nonvolatile) substance or the like can be suppressed.

The invention according to the above embodiments can be applied to a plasma processing apparatus for processing a sample by etching, ashing, CVD (Chemical Vapor Deposition) or the like of a substrate such as a semiconductor wafer.

As described above, the uniformity of the processing rate of the semiconductor wafer 8 in the in-plane direction can be improved. Furthermore, it is possible to increase the processing rate and suppress the adhesion of foreign matters to the semiconductor wafer 8.

DESCRIPTION OF SYMBOLS 1 ... Processing chamber 2 ... Discharge tube 3 ... Upper cover 4 ... First gas supply means 5 ... Gas rectification means 6 ... Gas introduction pipe 7 ... Second gas supply means 8 ... Semiconductor wafer 9 ... Wafer stage 10 ... Vacuum exhaust means DESCRIPTION OF SYMBOLS 11 ... Antenna 12 ... Matching circuit 13 ... High frequency power supply 14 ... Plasma 20 ... Gas outlet

Claims (7)

A cylindrical discharge part that constitutes the upper part of the vacuum vessel whose inside is depressurized and plasma is formed inside thereof, and a process in which the vacuum vessel is constituted below the discharge part and the wafer to be processed is placed inside A container, a first gas supply port that is disposed above the discharge unit and supplies a first gas for generating plasma therein, and is wound around the periphery of the discharge unit to form the plasma. A plasma processing apparatus comprising: an antenna to which electric power is supplied; and a stage disposed inside the processing vessel and below the discharge unit and on which the wafer is placed.
The discharge part has a stepped part having a diameter smaller than the diameter of the wafer and having a larger diameter at a lower part thereof connected to the processing container, and is vertically moved at a center part of the discharge part above the stage. A gas introduction pipe arranged extending in a direction, wherein the step portion has a second gas supply port for supplying a second gas radially into the processing vessel from the center side toward the outer peripheral side of the stage. A plasma processing apparatus provided with a gas introduction pipe provided below.
The plasma processing apparatus according to claim 1,
The gas introduction pipe has a plurality of the second gas supply ports and a plurality of flow paths through which the second gas flows and communicates with the second gas supply ports. A plasma processing apparatus comprising means for independently adjusting the flow of the second gas in the flow path.
The plasma processing apparatus according to claim 1 or 2,
The plasma processing apparatus, wherein the gas introduction tube has a cylindrical shape, and the cylindrical axis is arranged in the discharge portion with the axis of the discharge portion being aligned.
The plasma processing apparatus according to any one of claims 1 to 3,
A plasma processing apparatus, comprising: a first gas rectifier arranged at an upper portion in the discharge portion and configured of at least one disk-like structure and coaxially with the discharge tube.
The plasma processing apparatus according to any one of claims 1 to 4,
The plasma processing apparatus, wherein the rectifying means is made of either quartz or ceramic.
A plasma processing apparatus according to any one of claims 1 to 5,
The gas introducing pipe is a plasma processing apparatus made of metal .
A plasma processing apparatus according to any one of claims 1 to 5 ,
A material for the gas introduction pipe is a plasma processing apparatus made of quartz or ceramic .