JPWO2012060423A1 - Radical cleaning apparatus and method - Google Patents

Abstract

As a radical cleaning device using μ wave plasma and high frequency plasma, or a high frequency plasma, which can extend the life of the plasma generation chamber by reducing the consumption of the inner wall of the plasma generation chamber and can be processed at low temperature, A substrate support stage 22 on which the substrate to be processed S is placed is installed. The μ wave applying means or the high frequency applying means, the plasma generating chamber 27 for generating plasma by the μ wave applying means or the high frequency applying means, The first shower plate 28 is provided with a first shower plate 28 to which a high frequency power supply 28b provided below is connected, and a second shower plate 29 also serving as a discharge electrode provided under the first shower plate 28. And the second shower plate 29, the radical generation chamber 30 is formed under the first shower plate 28 and the second shower plate 28. Will have on the shower plate 29 is configured to the target substrate S is etched, and radical cleaning to remove the etch residue product. A radical cleaning method is performed using this apparatus.

Description

  The present invention relates to a radical cleaning apparatus and method, and more particularly to a radical cleaning apparatus and method using μ-wave plasma and high-frequency plasma, or high-frequency plasma.

  In the process of making a Si transistor, as a pre-process for forming a salicide of Ni and Co for the contact between the source, drain and wiring, and as a pre-process for the contact between the gate Poly-Si film and the wiring, In order to remove the oxide film, cleaning with HF has been performed in the past. However, as the device shrinks, the HF solution does not enter the fine holes well, and the removal of the natural oxide film has become insufficient.

In order to solve the above problem, a radical etching technique (CDT) in a gas phase using NF ₂ H or NFH ₂ radicals has begun to be used. When SiO ₂ is etched with NFH radicals, residual products (NH ₄ ) ₂ SiF _{6 and the} like are generated. In order to remove this residual product, it is generally evaporated by heating to about 200 ° C. This is an application of the characteristic that (NH ₄ ) ₂ SiF ₆ evaporates at about 120 ° C. In order to form NFH radicals, N ₂ , H ₂ , and NH ₃ gases were decomposed with μ-wave plasma, H radicals were introduced into a vacuum chamber, and reacted with separately introduced NF ₃ (for example, patents). Reference 1). At this time, the generation of the plasma by the μ wave was performed by introducing N ₂ , H ₂ , NH ₃ gas into the quartz tube or the sapphire tube and irradiating the μ wave.

The case of using this μ wave plasma will be described below with reference to FIG. As shown in FIG. 1, N ₂ , H ₂ , and NH ₃ gases are introduced into a quartz tube 1 through a gas introduction system 2, and a microwave is introduced into the quartz tube 1 through a matching unit 3 and a waveguide 4. Then, the gas introduced into the quartz tube 1 was decomposed with μ-wave plasma to generate H radicals. The H radicals were introduced into the vacuum chamber 5 and reacted with NF ₃ gas separately introduced in the vacuum chamber to form NFH radicals. However, since the generated plasma P is concentrated in a small quartz tube, the inner wall of the tube is consumed so much that it has to be frequently replaced. This has been one of the main reasons for raising the operating cost of the apparatus.

  Further, in order to remove the residual product generated by etching, it is necessary to heat the substrate to about 200 ° C. Further, when BPSG is used as an interlayer insulating film in a semiconductor device (actual device), heating up to 400 ° C. is necessary because a phosphorus-based residue is formed. Heating up to 400 ° C. is not preferable because it is expensive in terms of equipment. In addition, heating at a high temperature may cause thermal damage to the device, and processing at a low temperature is desired. Furthermore, there is also a demand that it is desirable to perform all of the above processing in one room if possible.

JP 2010165595 A

  An object of the present invention is to solve the above-mentioned problems of the prior art, and reduce the consumption of the inner wall of the plasma generation chamber, thereby extending the life of the plasma generation chamber and enabling processing at a low temperature. Another object of the present invention is to provide a high frequency plasma or a radical cleaning apparatus and method using the high frequency plasma.

  According to a first aspect of the radical cleaning apparatus of the present invention, in the radical cleaning apparatus having a vacuum chamber, a substrate support stage for placing a substrate to be processed is installed in the vacuum chamber, and a μ wave applying means or a high frequency applying means is provided. A plasma generating chamber for generating plasma by the μ wave applying means or the high frequency applying means, a first shower plate connected to a high frequency power source provided under the plasma generating chamber, and the first shower plate And a second shower plate also serving as a discharge electrode, and a radical generation chamber defined by the first shower plate and the second shower plate is disposed under the first shower plate and the second shower plate. It is provided on the second shower plate, etches the substrate to be processed, and removes etching residual products to perform radical cleaning. It is comprised so that it may do.

  In the first invention of the radical cleaning device, the μ wave applying means comprises a μ wave introducing means, a μ wave shielding member, and a μ wave diffusing dielectric member, and the high frequency applying means includes a gas inside. It is characterized by comprising a gas introduction member provided with an introduction path, and a top plate to which a high-frequency power source provided under the gas introduction member is connected.

  In the first invention of the radical cleaning device, there is provided a means for switching between application of a high frequency power source to the first shower plate and grounding in order to set the first shower plate to ground potential. To do.

  A second aspect of the radical cleaning apparatus according to the present invention is a radical cleaning apparatus having a vacuum chamber, wherein a substrate support stage for placing a substrate to be processed is installed in the vacuum chamber, and a μ wave applying means or a high frequency applying means is provided. A plasma generating chamber for generating plasma by the μ wave applying means or the high frequency applying means, a first shower plate connected to a high frequency power source provided under the plasma generating chamber, and the first shower plate And a radical generation chamber provided underneath, and configured to perform radical cleaning after etching the substrate to be processed.

  In the second invention of the radical cleaning device, the μ wave applying means comprises a μ wave introducing means, a μ wave shielding member, and a μ wave diffusing dielectric member, and the high frequency applying means includes a gas inside. It is characterized by comprising a gas introduction member provided with an introduction path, and a top plate to which a high-frequency power source provided under the gas introduction member is connected.

  In the second invention of the radical cleaning device, further comprising a second shower plate that also serves as a discharge electrode provided under the first shower plate, wherein the radical generation chamber has the first shower plate and the first shower plate. 2 is a space defined by the shower plate, and is configured to generate plasma in the space on the substrate to be processed and to remove radicals generated by the etching to perform radical cleaning. It is characterized by that.

  In the second invention of the radical cleaning device, characterized in that there is provided means for switching between application of a high-frequency power source to the first shower plate and grounding in order to make the first shower plate have a ground potential. To do.

  In the second invention of the radical cleaning device, the device is a single wafer device for cleaning substrates to be processed one by one, or a batch device for simultaneously processing a large number of substrates.

A first aspect of the radical cleaning method according to the present invention is a method for performing radical cleaning in a vacuum chamber, wherein N ₂ gas and H radical generation gas are introduced into a plasma generation chamber, and μ wave or high frequency To generate plasma, decompose the gas by the plasma to generate H radicals, introduce the H radicals through the first shower plate at the ground potential, and introduce the radicals into the radical generation chamber. NF ₃ gas is introduced into the production chamber, and the H radical and NF ₃ gas are reacted to generate NF _x H _y (x = 1 to 3, y = 1 to 4) radicals. This NF _x H _y radical with the etched surface of the substrate to be processed by irradiating the substrate to be processed placed in the vacuum chamber, and then stopping the application or high frequency application of the μ-wave, said N ₂ Scan, and stopping the introduction of the H radical generation gas and NF ₃ gas, while introducing an inert gas into the vacuum chamber, the second serving as the discharge electrodes by applying a high frequency to the first shower plate Etching residual products generated by etching using plasma ions and radicals generated by applying high frequency to the shower plate to discharge, generating plasma on the substrate to be processed placed in the vacuum chamber Is removed by evaporation.

A second aspect of the radical cleaning method of the present invention is a method for performing radical cleaning in a vacuum chamber, wherein N ₂ gas and H radical generation gas are introduced into a plasma generation chamber, and μ wave or high frequency is generated. Applied to generate plasma, decompose the gas by this plasma to generate H radicals, introduce the H radicals through the first shower plate at the ground potential, and introduce the radicals into the radical generation chamber. An NF ₃ gas is introduced into the room, the H radical and the NF ₃ gas are reacted to generate NF _x H _y (x = 1 to 3, y = 1 to 4) radicals, and the NF _x H _y radicals are The surface of the substrate to be processed is etched by irradiating the substrate to be processed placed in the vacuum chamber.

In the second invention of the radical cleaning method according to the present invention, after etching the surface of the substrate to be processed, the application of the μ wave or high frequency is stopped, and the N ₂ gas, H radical generating gas and NF ₃ gas are stopped. And introducing an inert gas into the vacuum chamber and applying a high frequency to the first shower plate to apply a high frequency to the second shower plate that also serves as a discharge electrode to discharge, Plasma is generated on a substrate to be processed placed in the vacuum chamber, and etching residual products generated by the etching are evaporated and removed using ions and radicals of the plasma.

In the first and second inventions of the radical cleaning method, the inert gas is introduced into the vacuum chamber through the N ₂ gas and H radical generating gas inlet or the NF ₃ gas inlet. Or is directly introduced into the vacuum chamber.

In the first and second inventions of the radical cleaning method, the inert gas is at least one gas selected from the group consisting of H ₂ , Ar, He, Ne, and Xe.

In the first and second inventions of the radical cleaning method, a substrate having a SiO ₂ film formed on a surface thereof is used as the substrate to be processed.

  In the first and second inventions of the radical cleaning method, the radical cleaning is performed using any one of the radical cleaning devices of the first and second inventions.

  According to the present invention, in order to generate plasma for generating H radicals, a parallel plate type plasma discharge chamber (plasma generation chamber) is preferably installed to widen the discharge space, and the μ wave is preferably a dielectric member. The plasma density per unit area can be reduced by diffusing in a large area using and introducing it into the discharge space, or by diffusing a high frequency into the discharge space and introducing it into the discharge space. As a result, by reducing damage to the walls covering the discharge space, the life of the discharge chamber is significantly increased, eliminating the need for frequent replacements that have been done with conventional quartz tubes, There is an effect that the operation cost is reduced.

In addition, a reaction chamber (radical generation chamber) that performs a reaction between the H radical that has passed through the first shower plate and the introduced NF ₃ gas is provided, and further generated through a second shower plate having a predetermined pore size. Since only NF _x H _y (x = 1 to 3, y = 1 to 4) radicals can be supplied to the substrate, there is no influence of ions, and radical cleaning with a high selectivity with SiN is possible. Can be played. Substrates used in the present invention include substrates on which various films constituting semiconductor devices (actual devices) are formed in addition to the SiO ₂ film on the surface. Therefore, a part of the substrate surface may be SiN, for example. Therefore, if SiN is etched, a portion that should not be etched is removed, so that cleaning with a high selectivity to SiN is required. The present invention is also suitable for such a case.

  Further, after etching, a high frequency is continuously applied to the second shower plate that opposes the substrate to be processed, and an inert gas is introduced to generate plasma on the substrate to be processed, thereby removing residual etching products. In addition, the temperature of the substrate can be lowered, and the etching process and the residual product removal process can be performed consistently in one vacuum chamber, so that it is possible to reduce the cost of the apparatus. .

The cross-sectional schematic which shows typically one structure of the apparatus for performing the H radical generation by microwave irradiation by a prior art. 1 is a schematic cross-sectional view schematically showing an example of the configuration of a radical cleaning apparatus using μ wave plasma and high frequency plasma according to the present invention. The cross-sectional schematic which shows typically another structural example of the radical cleaning apparatus using micro wave plasma and high frequency plasma by this invention. The cross-sectional schematic which shows typically the example of 1 structure of the radical cleaning apparatus using the high frequency (RF) plasma by this invention. The cross-sectional schematic which shows typically another structural example of the radical cleaning apparatus using RF plasma by this invention. 6 is a graph showing the relationship between the μ wave irradiation time (seconds) when the μ wave is applied and the etching amount (etching thickness (nm)) of the SiO ₂ film, obtained in Example 1. The relationship between the RF irradiation time (second) for applying RF to the second shower plate and the etching amount (etching thickness (nm)) with the μ wave application time fixed at 80 seconds, obtained in Example 1. the graph (a), etching and etching residual product of SiO ₂ film _{(NH 4)} 2 SiF ₆ schematically schematic diagram for illustrating a series of process of elimination ((b) ~ (d) ). The relationship between RF irradiation time (second) when applying RF (13.56 MHz) to the RF top plate obtained in Example 2 and the etching amount (etching thickness (nm)) of the SiO ₂ film is shown. Graph. The RF (13.56 MHz) application time of the RF top plate obtained in Example 2 is fixed to 60 seconds, and the RF irradiation time (seconds) for applying RF to the second shower plate and the etching amount (etching) Graph (a) showing the relationship with the thickness (nm)), and a schematic schematic diagram for explaining a series of processes of etching the SiO ₂ film and removing the etching residual product (NH ₄ ) ₂ SiF ₆ ((b ) To (d)). RF irradiation time (seconds) when the frequency of the first RF power source obtained in Example 2 was changed (13.56 MHz, 40 MHz, and 80 MHz) and the etching amount (etching thickness (nm) of the SiO ₂ film ).

  Hereinafter, embodiments of the radical cleaning apparatus and method according to the present invention will be described for a case where μ wave plasma and high frequency plasma are used, and a case where only high frequency plasma is used, respectively. Some overlapping parts are omitted.

According to the first embodiment of the radical cleaning apparatus of the present invention, this radical cleaning apparatus has a vacuum chamber, and a substrate support stage for placing a substrate to be processed is installed in the vacuum chamber, and the vacuum chamber In order from the atmosphere side, the microwave introduction means, the microwave shielding member provided around the microwave introduction means, the microwave diffusion dielectric member provided below the microwave shielding member, Generation of plasma for H radical generation provided with a μ wave applying means comprising a dielectric member for μ wave diffusion, and a gas inlet for introducing N ₂ gas and H radical generation gas provided in parallel thereunder. And a discharge electrode provided under the first shower plate, which is provided in parallel under the plasma generation chamber and to which a high-frequency power source is connected for allowing the generated radicals to pass therethrough. Second shower And a radical generation chamber, which is a space defined by the first shower plate and the second shower plate, is provided below the first shower plate and above the second shower plate. The radical generation chamber (space) has a gas inlet for introducing a gas (for example, NF ₃ gas) that reacts with the H radical passing through the first shower plate. It is configured to react to generate radicals for etching the substrate to be processed (for example, NF _x H _y (x = 1 to 3, y = 1 to 4) radicals). Active gas is introduced, for example, from the gas inlet provided in the plasma generation chamber through the plasma generation chamber and the radical generation chamber, through the gas inlet provided in the radical generation chamber, or in the vacuum chamber An inert gas is directly introduced into the vacuum chamber from the gas inlet, and plasma is generated in the space above the substrate to be processed under the second shower plate and in the upper portion of the vacuum chamber. The apparatus is configured to remove residual products and includes means for switching between application of a high-frequency power source to the first shower plate and ground to bring the first shower plate to ground potential. May be a single-wafer apparatus that cleans the substrates to be processed one by one, or a batch apparatus that simultaneously processes a large number of sheets. The plasma generation chamber may be a parallel plate type as described above, or may be an ICP mode.

Examples of the NF _x H _y (x = 1 to 3, y = 1 to 4) radical include NF ₂ H and NFH ₂ radicals.

  The introduction of the inert gas into the vacuum chamber can be carried out through the above-described path, and discharge occurs in the vacuum chamber and plasma is generated, but the vacuum chamber directly from the gas inlet provided in the vacuum chamber. If introduced into the chamber, the pressure in the plasma generation chamber becomes lower than the pressure in the plasma space in the vacuum chamber, which may cause inconvenience. Therefore, it is more preferable to introduce into the vacuum chamber through the plasma generation chamber and / or the radical generation chamber.

According to the second embodiment of the radical cleaning apparatus according to the present invention, the radical cleaning apparatus has a vacuum chamber, and a substrate support stage for placing a substrate to be processed is installed in the vacuum chamber. In order from the air side to the upper lid having the opening, the μ wave introducing means, the μ wave shielding member provided around the μ wave introducing means, and the μ wave diffusion dielectric member provided below the μ wave shielding member A plasma generation chamber for generating H radicals provided with a gas inlet for introducing N ₂ gas and a gas for generating H radicals, which are provided in parallel under the dielectric member for μ wave diffusion, and this plasma generation A first shower plate for passing the generated radicals connected in parallel under the chamber and connected to the high-frequency power supply; and a radical generation chamber provided under the first shower plate. The chamber is the first It has a gas inlet for introducing a gas (for example, NF ₃ gas) that reacts with H radicals passing through the power plate, and reacts both in the space to etch the radical ( For example, the first shower is configured to generate NF _x H _y (x = 1 to 3, y = 1 to 4) radicals, and the first shower plate is set to the ground potential. Means for switching between application of a high-frequency power source to the plate and grounding are provided, and this apparatus may be a single-wafer apparatus for cleaning substrates to be processed one by one or a batch apparatus for simultaneously processing a large number of sheets. In this case, after etching the substrate to be processed, an etching residual product on the substrate to be processed can be removed using another vacuum chamber.

  In the second embodiment of the radical cleaning device, a second shower plate that also serves as a discharge electrode provided in parallel below the first shower plate is further provided, and the radical generation chamber has the first shower plate and the first shower plate. The second plasma is generated in the space above the substrate to be processed in the upper part of the vacuum chamber, and the residual etching product generated by the etching is removed to generate radicals. It is configured to be cleaned.

  According to the third embodiment of the radical cleaning apparatus of the present invention, this radical cleaning apparatus is a radical cleaning apparatus having a vacuum chamber, and a substrate support stage for placing a substrate to be processed is installed in the vacuum chamber. The high-frequency applying means for covering the opening of the vacuum chamber in order from the atmosphere side, the gas introduction member provided with a gas introduction path having a bent shape inside, and provided below the gas introduction member A high-frequency applying means comprising a high-frequency top plate connected to a first high-frequency power source, a first plasma generation chamber provided in parallel with the top plate under the top plate, and provided in parallel under the plasma generation chamber In addition, a first shower plate connected to a second high-frequency power source for allowing the generated radicals to pass through, and a second electrode serving also as a discharge electrode provided under the first shower plate A radical generation chamber, which is a space defined by the first shower plate and the second shower plate, below the first shower plate and above the second shower plate. A gas that reacts with H radicals passing through the first shower plate is introduced into the radical generation chamber to react with H radicals to generate radicals, and the substrate to be processed is etched with these radicals. Introducing an inert gas into the vacuum chamber, for example, from the gas introduction port provided in the gas introduction member through the plasma generation chamber and the radical generation chamber, or through the gas introduction port provided in the radical generation chamber, or An inert gas is directly introduced into the vacuum chamber directly from the gas inlet provided in the vacuum chamber, and is located under the second shower plate and in the vacuum chamber. It is configured to generate radicals in the space above the substrate to be processed to remove etching residual products and perform radical cleaning, and in order to set the first shower plate to ground potential, Means is provided for switching between application of the second high-frequency power source to the shower plate and grounding, and this apparatus is a batch apparatus that simultaneously processes a large number of sheets, even if it is a single wafer apparatus that cleans substrates to be processed one by one. May be.

  The gas introduction path is not linear, but has a shape configured to bend once in the gas introduction member and go to the plasma generation chamber, so that the plasma component flows back from the plasma generation chamber. It is configured not to. The gas introduction path may be linear, and in this case, a structure for providing a plasma backflow prevention filter in the middle of the path may be used. The plasma generation chamber may be a parallel plate type as described above, or may be an ICP mode. Note that, instead of the gas introduction member provided with the gas introduction path, a gas introduction path may be provided on the side wall of the first plasma generation chamber.

  The introduction of the inert gas into the vacuum chamber can be carried out through the above-described path, and discharge occurs in the vacuum chamber and plasma is generated, but the vacuum chamber directly from the gas inlet provided in the vacuum chamber. If introduced into the chamber, the pressure in the plasma generation chamber becomes lower than the pressure in the plasma space in the vacuum chamber, which may cause inconvenience. Therefore, it is more preferable to introduce into the vacuum chamber through the plasma generation chamber and / or the radical generation chamber.

  According to the fourth embodiment of the radical cleaning apparatus of the present invention, this radical cleaning apparatus is a radical cleaning apparatus having a vacuum chamber, and a substrate support stage for placing a substrate to be processed is installed in the vacuum chamber. The high-frequency applying means for covering the opening of the vacuum chamber in order from the atmosphere side, the gas introduction member provided with a gas introduction path having a bent shape inside, and provided below the gas introduction member A high-frequency applying means comprising a high-frequency top plate connected to a first high-frequency power source, a first plasma generation chamber provided in parallel under the top plate, and a parallel generation under the plasma generation chamber were generated. A first shower plate connected to a second high-frequency power source for passing radicals, and a radical generation chamber provided under the first shower plate. A gas that reacts with the H radical passing through the first shower plate is introduced into the radical generation chamber to react with the H radical, thereby generating a radical, and the substrate to be processed is etched with this radical. Further, in order to set the first shower plate to the ground potential, there is provided means for switching between application of the second high-frequency power source to the first shower plate and ground, and this apparatus cleans the substrates to be processed one by one. It may be a single wafer processing apparatus or a batch apparatus that processes a large number of sheets simultaneously. In this case, after etching the substrate to be processed, an etching residual product on the substrate to be processed can be removed using another vacuum chamber.

  In the fourth embodiment of the radical cleaning device, a second shower plate also serving as a discharge electrode provided in parallel below the first shower plate is further provided, and the radical generation chamber has the first shower plate and the first shower plate. The second plasma is generated in the space above the substrate to be processed in the upper part of the vacuum chamber, and the residual etching product generated by the etching is removed to generate radicals. It is configured to be cleaned.

  The gas introduction path in the fourth embodiment of the radical cleaning device is not linear, but has a shape configured to bend once in the gas introduction member and go into the plasma generation chamber. Thus, the plasma component is configured not to flow backward from the generation chamber. The gas introduction path may be linear as described above. In this case, a structure for providing a plasma backflow prevention filter in the middle of the path may be used. The first plasma generation chamber may be a parallel plate type as described above, or may be an ICP mode. The gas introduction member provided with the gas introduction path is as described above.

According to the first embodiment of the radical cleaning method of the present invention, this cleaning method is a method of performing radical cleaning in a vacuum chamber, and includes N ₂ gas and H radical generating gas in the plasma generation chamber. (For example, H ₂ gas or NH ₃ gas) is introduced, and a μ wave is applied to the introduced gas to generate a μ wave plasma, and the plasma is decomposed to generate H radicals. The H radical passes through the first shower plate having the ground potential and is introduced into the radical generation chamber, and NF ₃ gas is introduced into the radical generation chamber to cause the H radical and NF ₃ gas to react with each other to generate NF _x H _y (x = 1 to 3, y = 1 to 4) radicals are generated, and the NF _x H _y radicals pass through a second shower plate that also serves as a discharge electrode. By, substrate to be processed placed in the vacuum chamber (e.g., the substrate SiO ₂ film is formed on the surface) was irradiated onto the substrate to be processed surface (e.g., SiO ₂ film formed on the surface ), And then, if desired, after the etching, the application of μ-wave is stopped and the introduction of N ₂ gas, H radical generating gas and NF ₃ gas is stopped, and an inert gas (for example, , H ₂ , Ar, He, Ne, and Xe), and the plasma generation chamber and the radical are introduced from, for example, a gas inlet provided in the plasma generation chamber. The inert gas is introduced into the vacuum chamber through the generation chamber, from the gas inlet provided in the radical generation chamber, through the radical generation chamber, or directly from the gas inlet provided in the vacuum chamber. By applying a high frequency to the shower plate, a high frequency is applied to the second shower plate that also serves as a discharge electrode to cause discharge, and plasma is generated on the substrate to be processed placed in the vacuum chamber. It consists of evaporating and removing etching residual products generated by etching using radicals.

  In the first embodiment of the radical cleaning method, the introduction of the inert gas into the vacuum chamber can be performed through the above-described path, and a discharge occurs in the vacuum chamber to generate plasma. In this case, if the gas is directly introduced into the vacuum chamber from the gas inlet provided in the vacuum chamber, the above-described disadvantage may occur. Therefore, it is more preferable to introduce into the vacuum chamber through the plasma generation chamber and / or the radical generation chamber.

  In the first embodiment of the radical cleaning method, the etching process and the etching residual product removal process can be performed by using the apparatus of the first embodiment of the radical cleaning apparatus. Only by using the apparatus of the second embodiment of the radical cleaning apparatus, and then using another vacuum chamber capable of processing the etching residual product by introducing an inert gas. However, it may be carried out continuously using the apparatus of the first embodiment.

According to the second embodiment of the radical cleaning method of the present invention, this cleaning method is a method for performing radical cleaning in a vacuum chamber, and includes N ₂ gas and H radical generation gas in the plasma generation chamber. (For example, H ₂ gas or NH ₃ gas) is applied, a high frequency is applied from the first high frequency power source to generate a high frequency plasma, the gas is decomposed by this plasma to generate H radicals, The H radical passes through the first shower plate having the ground potential and is introduced into the radical generation chamber, and NF ₃ gas is introduced into the radical generation chamber, and the H radical and NF ₃ gas are reacted to generate NF _x H _y. (x = 1~3, y = 1~4 ) to generate radicals, the _NF x _{H y} radicals is passed through the second shower plate, vacuum Is irradiated on the SiO ₂ film formed on the substrate to be processed placed within, the film is etched, and then, if desired, the first connected to the SiO ₂ film after etching, the high-frequency baking sheet The high frequency power supply (discharge) from the high frequency power source is stopped and the introduction of N ₂ gas, H radical generating gas and NF ₃ gas is stopped, and inert gas (for example, H ₂ , Ar, At least one kind of inert gas selected from the group consisting of He, Ne, and Xe), for example, from a gas introduction port provided in the gas introduction member through a plasma generation chamber and a radical generation chamber, or An inert gas is introduced into the vacuum chamber from the gas inlet provided in the radical generation chamber through the radical generation chamber or directly from the gas inlet provided in the vacuum chamber, and the first shower By applying a high frequency from a second high frequency power source to the second electrode, a high frequency is applied to the second shower plate that also serves as a discharge electrode to discharge, and plasma is generated on the substrate to be processed placed in the vacuum chamber. The plasma ions and radicals are used to evaporate and remove etching residual products generated by etching.

  The introduction of the inert gas into the vacuum chamber can be performed through the above-described path, and discharge occurs in the vacuum chamber, thereby generating plasma. In this case, if the gas is directly introduced into the vacuum chamber from the gas inlet provided in the vacuum chamber, the above-described disadvantage may occur. Therefore, it is more preferable to introduce into the vacuum chamber through the plasma generation chamber and / or the radical generation chamber.

Examples of the NF _x H _y (x = 1 to 3, y = 1 to 4) radical include NF ₂ H and NFH ₂ radicals as described above.

  In the second embodiment of the radical cleaning method, the etching process and the etching residual product removal process can be performed using the radical cleaning apparatus of the third embodiment, and only the etching process is performed. It may be performed using the radical cleaning apparatus of the fourth embodiment, and then may be performed using another vacuum chamber that can introduce an inert gas to treat the etching residual product, or continuously. Alternatively, the apparatus of the third embodiment may be used.

  Next, first and second embodiments of the radical cleaning apparatus according to the present invention will be described in detail with reference to FIGS.

  According to one configuration example of the radical cleaning apparatus of the present invention schematically shown in FIG. 2, the radical cleaning apparatus has a vacuum chamber 21 that can be evacuated by a vacuum exhaust system (not shown). A substrate support stage 22 for placing the substrate to be processed S is disposed in the lower portion of the vacuum chamber 21, and an upper lid 21a for the vacuum chamber having an opening is disposed on the upper portion. The substrate support stage 22 includes a heating means 23 such as a hot plate for heating the substrate S to be processed, and lift pins that can move the substrate up and down when the substrate S is transferred. Etc. (not shown). The wall surface of the vacuum chamber 21 is provided with a substrate transfer port 21b, a gas introduction port 21c and an exhaust port 21d when an inert gas is directly introduced into the vacuum chamber. As the introduction of the inert gas, it is introduced into the plasma generation chamber from a gas introduction port 27b provided in the plasma generation chamber 27 described below, or from the gas introduction port 29a provided in the radical generation chamber 30 to the radical generation chamber. In some cases, it is preferable to introduce it into the vacuum chamber 21 directly.

  Above the upper lid 21 a of the vacuum chamber 21, in order from the atmosphere side, a μ wave introducing means 24 comprising a waveguide and a matching device, a μ wave shielding member 25, a μ wave diffusion dielectric member 26, and H A plasma generation chamber (space) 27 for generating radicals, a first shower plate 28, and a second shower plate 29 are provided, and the first shower plate 28 and the second shower plate 29 define the plasma. The radical generation chamber 30, which is a space formed, is provided below the first shower plate 28 and above the second shower plate 29. The outer peripheral edge portion of the first shower plate 28 and the outer peripheral edge portion of the second shower plate 29 are in contact with each other.

The μ-wave shielding member 25 is provided around the μ-wave introduction unit 24 so that the μ-wave does not leak into the atmosphere and the μ-wave applied from the μ-wave introduction unit 24 can be introduced into the vacuum chamber. Of course, it is not arranged in a portion facing the waveguide. The μ wave diffusion dielectric member 26 is provided under the μ wave introducing means 24 and the μ wave shielding member 25 so that the μ wave applied from the μ wave introducing means 24 can be diffused and introduced into the vacuum chamber. It is configured. The plasma generation chamber (space) 27 for H radical generation is provided below the dielectric member 26 for diffusing the microwave, the side wall 27a is made of an insulator, and the microwave is passed through a hermetic seal member such as an O-ring. It is provided parallel to the diffusion dielectric member 26, has a horizontally long shape in the drawing, and has a gas inlet 27b for introducing N ₂ gas and H radical generating gas. The first shower plate 28 is provided below the plasma generation chamber 27 in parallel via a hermetic seal member 28a such as an O-ring, and passes through the radicals generated in the plasma generation chamber 27 made of the insulator. And has a size equal to or larger than the size of the substrate to be processed S, and is connected to the high frequency power supply 28b. The second shower plate 29 is provided below the first shower plate 28 in parallel via a sealing member 29b such as an O-ring, and is the same as the dimension of the substrate S to be processed or the dimension of the substrate S to be processed. Larger dimensions. As described above, the radical generation chamber 30 is a space defined by the first shower plate 28 and the second shower plate 29. This space has a gas inlet 29a for introducing a gas that reacts with the H radical passing through the first shower plate 28, and reacts both in the space to generate a radical. The substrate to be processed is configured to be etched. In the next step, for example, an inert gas (for example, at least one kind of inert gas selected from the group consisting of H ₂ , Ar, He, Ne, and Xe) in this space (radical generation chamber 30). The plasma P2 is generated in the space above the substrate to be processed S in the vacuum chamber 21 below the second shower plate 29 to remove residual etching products and perform radical cleaning. It is configured.

With the configuration described above, a gas (for example, NF ₃ gas) that reacts with the H radical passing through the first shower plate 28 into the radical generation chamber 30 is introduced from the gas inlet 29a, and the H radical To generate radicals. As a result, the surface of the substrate S to be processed placed in the vacuum chamber 21 opposite to the second shower plate 29 is irradiated with radicals. Can be etched.

  Even if an inert gas is introduced into the radical generation chamber 30 from the gas inlet 29a or 27b or both, plasma can be generated in the vacuum chamber as a result. In this case, it is preferable to introduce an inert gas from the gas inlet 27b. This is because if the gas is introduced from the gas introduction port 29a, the gas flows backward through the space 27 and may cause generation of particles. As a result, the plasma P2 is generated between the second shower plate 29 and the surface of the substrate S to be processed placed in the vacuum chamber 21, and the etching residual products can be removed. This apparatus may be a single wafer apparatus for cleaning the substrates to be processed one by one, or a batch apparatus for simultaneously processing a large number of sheets.

When removing the residual product after the etching, the discharge from the μ wave introduction means 24 is stopped, and the gas from the gas introduction port 27b (for example, N ₂ gas, H ₂ gas or NH ₃ gas). And the introduction of a gas (for example, NF ₃ gas) from the gas inlet 29a are stopped, and then a high frequency is applied to the first shower plate 28 from a high frequency power supply 28b to connect the first shower plate 28 to the second shower plate 28. The shower plate 29 is kept at the same potential, and, for example, an inert gas is introduced into the radical generation chamber 30 from the gas introduction port 29a or 27b or both, and the second shower plate 29 serves as the second shower plate 29 via the discharge electrode. The second plasma P2 is generated in the upper space between the shower plate 29 of No. 2 and the substrate to be processed S placed in the vacuum chamber 21, and the substrate to be processed S is made into this plasma. By Succoth, it is possible to remove the etch residue products adhering to the substrate S to be processed or on the vacuum chamber 21 interior wall. For this reason, in the present invention, there is provided means for switching between application of the second high-frequency power supply 28b and grounding to the first shower plate 28.

  The above-described radical cleaning apparatus shown in FIG. 2 is suitable for processing, for example, about 1 to 4 substrates, and the radical cleaning apparatus described below with reference to FIG. The processing substrate is cleaned.

  In the case of one configuration example of the radical cleaning apparatus schematically shown in FIG. 3, this radical cleaning apparatus is an apparatus for simultaneously processing a large number of substrates to be processed. Although FIG. 3 shows an example of processing 50 sheets, this number is not particularly limited, and can be set appropriately according to the purpose. In this case, the configuration other than the vacuum chamber 31 is as shown in FIG. 2, and the same reference numerals are also given. A predetermined number of substrates to be processed S are placed in the vacuum chamber 31. As in the case of FIG. 2, the etching residual product can be removed by the plasma generated in the vacuum chamber 31 so that the substrate S can be etched by radicals introduced into the vacuum chamber 31. It is configured as follows.

  In FIGS. 2 and 3, the case where the substrate to be processed is etched and the etching residual product is removed in the same vacuum chamber has been described. However, after performing the etching process using a radical etching apparatus that performs only the etching process, Etching residual products may be removed in the vacuum chamber.

  In FIGS. 2 and 3, parallel plate type plasma generation is provided as a plasma generation chamber 27 provided under the μ-wave diffusion dielectric member 26 and having a horizontally long shape in the drawing and generating the first plasma P1. A chamber (discharge chamber) is defined, and the discharge space is widened to reduce the plasma density per unit area, thereby reducing damage to the wall covering the discharge space. As a result, the life of the plasma generation chamber is significantly increased, so that frequent replacements required when a conventional quartz tube is used are unnecessary, and the operation cost is greatly reduced.

  Further, after etching, an inert gas is introduced, and a high frequency is applied to the second shower plate 29 that continuously opposes the substrate to be processed to generate plasma on the substrate to be processed, thereby removing etching residual products. Therefore, the temperature of the substrate can be lowered, and the etching process and the etching residual product removal process can be performed consistently in one vacuum chamber, which leads to reduction in apparatus cost.

  Hereinafter, the radical cleaning method of the present invention implemented using the radical cleaning apparatus shown in FIG. 2 will be described. This also applies to the radical cleaning method of the present invention implemented using the radical cleaning apparatus shown in FIG.

N ₂ gas and H radical generating gas such as H ₂ gas or NH ₃ gas are introduced into the plasma generating chamber 27 through the gas introducing port 27b, and at this time, the μ wave introducing means 24 performs the μ wave discharge. Then, the microwave plasma P1 is generated in the plasma generation chamber 27, and the introduced gas is decomposed by the plasma to generate H radicals.

The H radicals generated as described above are introduced into the radical generation chamber 30 through the first shower plate 28 having a predetermined pore diameter, and NF is introduced into the radical generation chamber via the gas inlet 29a. ₃ gas is introduced, H radical and NF ₃ gas are reacted to generate the above NF _x H _y radical, and this NF _x H _y radical is passed through the second shower plate 29, Irradiation is performed on the substrate S to be processed, and a film such as a SiO ₂ film formed on the surface is etched.

Next, the discharge from the μ wave introducing means 24 is stopped, and the introduction of N ₂ gas, H radical generating gas and NF ₃ gas is stopped. For example, an inert gas is introduced into the radical generating chamber 30, A high frequency is applied to one shower plate 28 from a high frequency power supply 28 b to cause the discharge electrode, which is the second shower plate 29, to discharge a high frequency, and on the substrate S to be processed placed in the vacuum chamber 21. The second plasma P2 is generated, and etching residual products generated by the etching are removed by evaporation using the plasma ions and radicals. The diameter of the second plasma P2 is made larger than the dimension of the substrate to be processed.

When the μ wave is discharged, the first shower plate 28 (second shower plate 29) is at the ground potential, and the radical generation chamber 30 is simply NF ₃ gas introduced from the gas inlet 29a. And a space for causing a reaction between the H radicals irradiated from the first shower plate 28. The NF _x H _y radicals generated by the reaction in the radical generation chamber 30 are irradiated onto the substrate S to be processed through the second shower plate 29, and etching of a film such as SiO _{2 on} the substrate surface is performed. After the etching is finished, the discharge from the μ wave introducing means 24 is stopped, the introduction of N ₂ gas and H radical generating gas such as H ₂ gas or NH ₃ gas is stopped, and the gas is introduced into the radical generating chamber 30. Introducing an inert gas from the mouth 29a or 27b or both, applying a high frequency from the high frequency power source 28b to the first shower plate 28, keeping the first shower plate 28 and the second shower plate 29 at the same potential, Plasma P2 of an inert gas is generated on the substrate S to be processed, and etching residual products such as (NH ₄ ) ₂ SiF ₆ formed on the substrate and the like are removed by etching.

The process with the NF _x H _y radical is usually carried out at 0 to 50 ° C., and when it exceeds 50 ° C., the etching rate tends to decrease rapidly. Moreover, the process by plasma P2 is normally implemented at 0-300 degreeC.

  In the above-described process, the temperature of the substrate to be processed is not particularly limited, but can be performed in the range of 25 to 300 ° C., for example. Etching residual products can be removed even at a low temperature such as 25 to 50 ° C. Moreover, regarding the high frequency that can be used in the present invention, the lower limit of the frequency is 13.56 MHz, which is available at a low cost, and the upper limit is less than 100 MHz. For example, 27 MHz, 40 MHz, etc. can be mentioned. Although discharge is possible even at a frequency lower than 13.56 MHz, 13.56 MHz, which can be obtained at a low cost, is preferably set as the lower limit.

The general reaction formula in the above etching process is as follows.
SiO ₂ + NF _x H _y → (NH ₄ ) ₂ SiF ₆ + H ₂ O

If this equation is described more accurately, it is assumed that there are the following three reactions.
SiO ₂ + 6NFH ₂ + 12H ₂ → (NH ₄ ) ₂ SiF ₆ + 2H ₂ O + 4NH ₃
SiO ₂ + NFH + 5HF + NH ₃ → (NH ₄ ) ₂ SiF ₆ + 2H ₂ O + 2H ₂ + H
SiO ₂ + 2NH ₄ + 2HF ₂ + 2HF → (NH ₄ ) ₂ SiF ₆ + 2H ₂ O

In the etching process, when a layer containing a phosphoric acid compound is present on the surface of the substrate to be processed instead of the SiO ₂ film, the etching residual products include H ₃ PO ₄ , (NH ₄ ) ₃ PO ₄ , ( NH ₄ ) ₂ HPO ₄ , (NH ₄ ) H ₂ PO _{4 and the} like are expected to be generated, and these compounds can also be removed by inert gas plasma (hydrogen plasma). Even when a BPSG film (SiO ₂ film containing P (phosphorus) and B (boron)) or a PSG film (SiO ₂ film containing P) is used instead of the SiO ₂ film as an interlayer insulating film, Similar etching processes and etching residue product removal processes can be used.

  Next, third and fourth embodiments of the radical cleaning apparatus according to the present invention will be described in detail with reference to FIGS.

  According to one configuration example of the radical cleaning apparatus of the present invention schematically shown in FIG. 4, the radical cleaning apparatus has a vacuum chamber 41 that can be evacuated to a vacuum state by a vacuum exhaust system (not shown). A substrate support stage 42 on which the substrate to be processed S is placed is disposed in the lower portion of the vacuum chamber 41, and a vacuum chamber upper lid 41a having an opening is disposed on the upper portion. The substrate support stage 42 is provided with heating means 43 such as a hot plate for heating the substrate to be processed S, and lift pins that can move the substrate up and down during the transfer of the substrate to be processed S. Etc. (not shown). The wall surface of the vacuum chamber 41 is provided with a substrate transfer port 41b, a gas introduction port 41c and an exhaust port 41d for directly introducing an inert gas into the vacuum chamber. As the introduction of the inert gas, when introducing into the plasma generation chamber from a gas introduction port 44a provided in the gas introduction member 44 described below, or from the gas introduction port 48b provided in the radical generation chamber 49, the radical generation chamber. It is preferable to introduce it directly into the vacuum chamber.

  According to the above radical cleaning device, the upper lid 41a of the vacuum chamber 41 is not linear in order from the atmosphere side, but has a shape configured to bend once toward the plasma generation chamber. A high-frequency top plate to which a gas introduction member 44 provided with a gas introduction path (gas introduction port 44 a) and a first high-frequency power source 45 a are connected, and an O-ring or the like under the gas introduction member 44. The high-frequency top plate 45 provided through the hermetic seal member 45b, and the side wall 46a is formed of an insulator below the top plate 45, and provided in parallel via the hermetic seal member 45c such as an O-ring. In addition, the above-mentioned insulation is provided in parallel with a plasma generation chamber (space) 46 for generating a first plasma having a horizontally long shape in the drawing, and a hermetic seal member 47a such as an O-ring under the plasma generation chamber 46. A first shower plate having a predetermined hole diameter for allowing radicals generated in the plasma generation chamber 46 configured to pass through and having a size equal to or larger than the size of the substrate S to be processed. A substrate to be processed, which is provided in parallel with the first shower plate 47 to which the second high-frequency power source 47b is connected, and a hermetic seal member 48a such as an O-ring under the first shower plate 47. And a second shower plate 48 that also serves as a discharge electrode having the same dimension as that of S or larger than the dimension of the substrate S to be processed. A radical generation chamber 49, which is a formed space, is provided below the first shower plate 47 and above the second shower plate 48.

With the configuration described above, a gas (for example, NF ₃ gas) that reacts with radicals passing through the first shower plate 47 in the radical generation chamber 49 is introduced from the gas inlet 48b to react with the radicals. Thus, radicals can be generated, and an inert gas can be introduced into the radical generation chamber 49 from the gas inlet 48b or 44a or both to generate plasma in the vacuum chamber. It is more preferable to introduce an inert gas from the gas inlet 44a. This is because if the gas is introduced from the gas introduction port 48b, the gas flows backward through the space 46, which may cause particles. As a result, the surface of the substrate S to be processed placed in the vacuum chamber 41 opposite to the second shower plate 48 can be etched by irradiating radicals, and the second shower plate 48 Etching residual products can be removed by generating plasma P <b> 2 between the surface of the substrate S to be processed placed in the vacuum chamber 41. This apparatus may be a single wafer apparatus for cleaning the substrates to be processed one by one, or a batch apparatus for simultaneously processing a large number of sheets.

When removing the residual product after the etching, the discharge from the first high frequency power supply 45a connected to the top plate is stopped, and the gas (for example, N ₂ gas, H ₂₎ from the gas inlet 44a is stopped. _2, NH ₃ gas, etc.) and gas (for example, NF ₃ gas, etc.) from the gas inlet 48 b are stopped, and then a high frequency is applied to the first shower plate 47 from the second high frequency power supply 47 b. Then, the first shower plate 47 and the second shower plate 48 are kept at the same potential, and an inert gas (for example, H ₂ , Ar, etc.) is introduced into the radical generation chamber 49 from the gas inlet 48 b or 44 a or both. At least one inert gas selected from the group consisting of He, Ne, and Xe), and the second shower plate 48 is discharged via the discharge electrode which is the second shower plate 48. The second plasma P2 is generated in the upper space between the substrate 48 and the substrate S to be processed placed in the vacuum chamber 41, and the substrate S to be processed is exposed to the plasma. Etching residual products adhering to the inner wall of the vacuum chamber 41 can be removed. For this reason, the present invention includes means for switching between application of the second high frequency power supply 47b and grounding to the first shower plate 47.

  The radical cleaning apparatus shown in FIG. 4 is suitable for processing, for example, about 1 to 4 substrates, and the radical cleaning apparatus described below with reference to FIG. The processing substrate is cleaned.

  In the case of one configuration example of the radical cleaning apparatus schematically shown in FIG. 5, this radical cleaning apparatus is an apparatus for simultaneously processing a large number of substrates to be processed. Although FIG. 5 shows an example of processing 50 sheets, this number is not particularly limited and can be set appropriately according to the purpose. In this case, the configuration other than the vacuum chamber 50 is as shown in FIG. 4, and the same reference numerals are also given. A predetermined number of substrates to be processed S are placed in the vacuum chamber 50. As in the case of FIG. 4, the etching residual product can be removed by the plasma generated in the vacuum chamber 50 so that the substrate S can be etched by radicals introduced into the vacuum chamber 50. It is configured as follows.

  In FIGS. 4 and 5, the case where the substrate to be processed is etched and the residual etching product is removed in the same vacuum chamber has been described. However, after performing the etching process using a radical etching apparatus that performs only the etching process, Etching residual products may be removed in the vacuum chamber.

  4 and 5, a parallel plate type plasma generation chamber is provided as a first plasma generation chamber 46 which is provided below the high-frequency top plate 45 and has a horizontally long shape in the drawing and generates the first plasma. By defining a (discharge chamber) and expanding the discharge space, the plasma density per unit area is reduced to reduce damage to the walls covering the discharge space. As a result, the life of the plasma generation chamber is significantly increased, so that frequent replacements required when a conventional quartz tube is used are unnecessary, and the operation cost is greatly reduced.

  In addition, after etching, plasma is generated on the substrate to be processed by applying a high frequency to the shower plate that opposes the substrate to be processed, and etching residual products are removed. Since the process and the etching residual product removal process can be performed consistently in one vacuum chamber, the apparatus cost can be reduced.

  Hereinafter, the radical cleaning method of the present invention implemented using the radical cleaning apparatus shown in FIG. 4 will be described. This also applies to the radical cleaning method of the present invention implemented using the radical cleaning apparatus shown in FIG.

N ₂ gas and H radio generated gas such as H ₂ gas or NH ₃ gas are introduced into the first plasma generation chamber 46 through the gas introduction port 44 a, and at this time, the first high frequency top plate 45 is supplied with the first A high frequency is applied from the high frequency power supply 45a to generate a high frequency plasma P1 in the plasma generation chamber 46, and the introduced gas is decomposed by this plasma to generate H radicals.

The H radicals generated as described above are introduced into the radical generation chamber 49 through the first shower plate 47 having a predetermined hole diameter, and into the radical generation chamber 49 through the gas inlet 48b. NF ₃ gas is introduced, H radical and NF ₃ gas are reacted to generate the above-mentioned NF _x H _y radical, the NF _x H _y radical is passed through the second shower plate 48, and the vacuum chamber The SiO ₂ film formed on the substrate to be processed S placed in 41 is irradiated and this film is etched.

Next, the discharge from the first high frequency power supply 45a is stopped, and the introduction of N ₂ gas, H radical generating gas and NF ₃ gas is stopped, and for example, an inert gas (for example, H ₂ , at least one kind of inert gas selected from the group consisting of Ar, He, Ne, and Xe), and applying a high frequency to the first shower plate 47 from the second high-frequency power source 47b. The discharge electrode, which is the second shower plate 48, is discharged by applying a high frequency to generate a second plasma P2 on the substrate S to be processed placed in the vacuum chamber 41, and ions and radicals of the plasma are generated. The residual etching product generated by etching is removed by evaporation. The diameter of the second plasma is made larger than the dimension of the substrate to be processed.

When a high frequency is applied to the high frequency top plate 45, the second shower plate 48 is at the ground potential, and the radical generation chamber 49 is simply connected to the NF ₃ gas introduced from the gas inlet 48b and the first It is provided as a space for causing a reaction with the H radical irradiated from the shower plate 47. The NFH radicals generated by the reaction in the radical generation chamber 49 are irradiated onto the substrate S to be processed through the second shower plate 48, and SiO ₂ etching on the substrate surface is performed. After the etching is finished, the application from the first high frequency power supply 45a is stopped, the introduction of N ₂ gas and H radical generating gas such as H ₂ gas or NH ₃ gas is stopped, and the gas is generated in the radical generation chamber 49. An inert gas (H ₂ gas or the like) is introduced from the introduction port 48b or 44a or both, and a high frequency is applied to the first shower plate 47 from the second high-frequency power source 47b, so that the first shower plate 47 and the second The shower plate 48 is kept at the same potential, an inert gas plasma P2 is generated on the substrate S to be processed, and etching residual products such as (NH ₄ ) ₂ SiF ₆ formed on the substrate and the like by etching are removed. To do.

  In the above-described process, the temperature of the substrate to be processed is not particularly limited, but can be performed in the range of 25 to 300 ° C., for example. Etching residual products can be removed even at a low temperature such as 25 to 50 ° C.

  The general reaction formula in the above etching process is as described above.

In the etching process, when a layer containing a phosphoric acid compound is present on the surface of the substrate to be processed instead of the SiO ₂ film, the etching residual products include H ₃ PO ₄ , (NH ₄ ) ₃ PO ₄ , ( NH ₄ ) ₂ HPO ₄ , (NH ₄ ) H ₂ PO _{4 and the} like are expected to be generated, and these compounds can also be removed by hydrogen plasma. Even when a BPSG film (SiO ₂ film containing P (phosphorus) and B (boron)) or a PSG film (SiO ₂ film containing P) is used instead of the SiO ₂ film as an interlayer insulating film, Similarly, etching and etching residual products can be removed.

  In the second to fourth embodiments of the radical cleaning apparatus according to the present invention, the same configuration as that of the first embodiment is partly omitted, and the second embodiment of the radical cleaning method according to the present invention is omitted. In this embodiment, the same processes as those in the first embodiment are partially omitted.

In this example, the radical cleaning apparatus shown in FIG. 2 is used, N ₂ gas and H ₂ gas are used to generate H radicals, NF ₃ gas is used to generate NF _x H _y radicals, and The etching process and the etching residual product removal process were performed using a substrate having a SiO ₂ film formed on the surface as the substrate to be processed. The series of process flow is as follows. In addition, an apparatus in which the first shower plate 28 is installed 15 mm away from the μ-wave diffusing dielectric member 26 is used.

(1) N ₂ and H ₂ gases were introduced into the plasma generation chamber 27 from the gas inlet 27b.
(2) A μ wave was applied from the μ wave introducing means 24 to generate plasma P1 in the plasma generating chamber 27, and the gas introduced by the plasma was decomposed to generate H radicals.
(3) The H radicals thus obtained are introduced into the radical production chamber 30 through the first shower plate 28, and NF ₃ gas is introduced into the radical production chamber, and both are reacted to produce NF _x H _y radicals. This radical was introduced into the vacuum chamber 21 through the second shower plate 29, irradiated onto the substrate to be processed, and the SiO ₂ film on the substrate to be processed was etched for a predetermined time. When the microwave is applied and a discharge is generated, the first shower plate 28 is at the ground potential, and the radical generation chamber 30 is used to cause a reaction between NF ₃ and H radical as described above. It only provides space.
(4) The microwave discharge from the microwave introduction means 24 was stopped.
(5) The introduction of N ₂ gas, H ₂ gas and NF ₃ gas was stopped.

(6) H ₂ gas was introduced as an inert gas into the radical generation chamber 30 from the gas inlet 29a or 27b.
(7) RF is applied to the first shower plate 28 from a high frequency (RF) power supply 28b, the first shower plate 28 and the second shower plate 29 are kept at the same potential, and the second shower plate 29 is passed through. H ₂ discharge was generated on the substrate S to be processed in the vacuum chamber 21.
(8) The substrate S to be processed placed in the vacuum chamber 21 was irradiated with H ₂ plasma for a predetermined time to remove residual products such as (NH ₄ ) ₂ SiF ₆ on the substrate. .
(9) The introduction of H ₂ gas was stopped, and the application of the RF power supply 28b was stopped.

  The series of processes described above can be divided into etching processes (1) to (5) and etching residual product removal processes (6) to (9).

  The optimization of each process will be described below.

FIG. 6 shows μ wave irradiation time (seconds) when μ wave: 2000 W is applied from the μ wave introducing means 24 through the μ wave diffusion dielectric member 26 and etching of SiO ₂ measured by an optical film thickness meter. The relationship with the quantity (etching thickness (nm)) is shown. In this case, a Si wafer provided with a thermal silicon oxide film of 1000 nm was used as the substrate S to be processed. Etching conditions are: substrate temperature to be processed: 25 ° C., N ₂ gas flow rate: 500 sccm, H ₂ gas flow rate: 500 sccm, NF ₃ gas flow rate: 1000 sccm, H ₂ plasma generation RF (13.56 MHz): 1000 W, 300 seconds applied Met.

As apparent from FIG. 6, the etching amount increases with the μ wave irradiation time (μ wave application time), and is saturated at an etching thickness of 29 nm for 80 seconds. This is determined to be a self-stop here. If the H ₂ discharge is insufficient, (NH ₄ ) ₂ SiF ₆ should be deposited and the amount of etching should seem to decrease, but this tendency was not observed. Therefore, it can be seen from this result that NF _x H _y radicals are sufficiently generated in the planar μ-wave plasma.

In FIG. 7 (a), the μ wave application time is fixed at 80 seconds where self-stop is applied, the RF irradiation time (seconds) and the residual product etching amount (etching thickness (nm)) measured with an optical film thickness meter. ). In this case, the Si wafer as described above is used as the substrate to be processed S, and the substrate temperature to be processed, the N ₂ gas flow rate, the H ₂ gas flow rate, the NF ₃ gas flow rate, and the RF for generating H ₂ plasma are the same as described above. Etching was performed under set conditions. A series of processes for etching the SiO ₂ film existing on the Si wafer and removing the etching residual product (NH ₄ ) ₂ SiF ₆ are schematically shown in FIGS. That is, when the SiO ₂ film existing on the Si wafer is subjected to NHF radical treatment and the SiO ₂ film is etched, a residual product (NH ₄ ) ₂ SiF ₆ is generated (FIG. 7B), and then the deposited residual product The product is removed (region A in FIG. 7 (a); FIG. 7 (c)), and if the removal process is continued, the residual product is finally removed (region B in FIG. 7 (a); FIG. 7 ( d)). This region B shows the thickness of the etched SiO ₂ film. For convenience, the etching amount was measured under the assumption that the thickness does not change even when SiO ₂ becomes (NH ₄ ) ₂ SiF ₆ , so the etching amounts in the regions A and B approximate to relative values.

As is apparent from FIG. 7, the etching amount increased with the RF irradiation time (RF application time) to the second shower plate 29 and saturated at 110 seconds. That is, it can be understood that the etching residual product can be removed even at the substrate temperature of 25 ° C., and the removal process can be made low temperature by using H ₂ plasma together.

  The plasma generation chamber of the radical cleaning apparatus shown in FIG. 2 after performing the above-described series of processes, that is, the etching processes (1) to (9) and the etching residual product removal process shown in FIGS. As a result of observing the state in the inner wall 27, no trace of damage was observed on the inner wall, it was not consumed, and the temperature of the substrate when removing the etching residual product could be lowered.

In this example, the radical cleaning apparatus shown in FIG. 4 is used, N ₂ gas and H ₂ gas are used to generate H radicals, and NF ₃ gas is used to generate NF _x H _y radicals. Then, an etching process and an etching residual product removal process were performed. The series of process flow is as follows.

(1) N ₂ and H ₂ gases were introduced into the first plasma generation chamber 46 from the gas inlet 44a.
(2) RF is applied to the high frequency (RF) top plate 45 from the first high frequency (RF) power supply 45a (at this time, the first shower plate 47 is set to the ground potential), and the inside of the first plasma generation chamber 46 A plasma was generated, and the gas introduced by the plasma was decomposed to generate H radicals.
(3) The H radicals thus obtained are introduced into the radical generation chamber 49 through the first shower plate 47, and NF ₃ gas is introduced into the radical generation chamber 49, and both are reacted to produce NF _x H _y Radicals were generated, the radicals were introduced into the vacuum chamber 41 through the second shower plate 48, and the SiO ₂ film on the substrate to be processed was etched for a predetermined time.

(4) The application of high frequency from the first RF power supply 45a was stopped.
(5) The introduction of N ₂ gas, H ₂ gas and NF ₃ gas was stopped.
(6) H ₂ gas was introduced as an inert gas into the second radical generation chamber 49 from the gas inlet 44a.
(7) RF is applied to the first shower plate 47 from the second RF power source 47b, and the first shower plate 47 and the second shower plate 48 are kept at the same potential, and the second shower plate 48 After that, H ₂ discharge was generated on the substrate S to be processed in the vacuum chamber 41.
(8) The substrate 2 to be processed placed in the vacuum chamber 41 was irradiated with H ₂ plasma for a predetermined time.
(9) The introduction of H ₂ gas was stopped, and the application of the second RF power supply 47b was stopped.

  The series of processes described above can be divided into etching processes (1) to (5) and etching residual product removal processes (6) to (9).

  The optimization of each process will be described below.

FIG. 8 shows RF irradiation time (seconds) when RF (13.56 MHz): 1000 W is applied to the RF top plate 45 and the etching amount (etching thickness (nm) of the SiO ₂ film measured with an optical film thickness meter. )). In this case, a Si wafer provided with a thermal silicon oxide film of 1000 nm was used as the substrate S to be processed. Temperature of substrate to be processed: 25 ° C., N ₂ gas: 500 sccm, H ₂ gas: 500 sccm, NF ₃ gas: 1000 sccm, RF for generating H ₂ plasma (13.56 MHz) was applied at 1000 W for 300 seconds.

As is apparent from FIG. 8, the etching amount increases with the RF irradiation time (RF application time), and is saturated for 60 seconds and 35 nm etching. This is determined to be a self-stop here. If the H ₂ discharge is insufficient, (NH ₄ ) ₂ SiF ₆ should be deposited and the amount of etching should seem to decrease, but this tendency was not observed. Therefore, it can be seen from this result that the NF _x H _y radicals are sufficiently generated in the plasma of the RF discharge.

In FIG. 9A, the RF (13.56 MHz) application time of the RF top plate 45 is fixed to 60 seconds that require self-stop, and the RF irradiation time (seconds) for applying RF to the second shower plate 48 And the etching amount (etching thickness (nm)) measured with an optical film thickness meter. In this case, the Si wafer as described above is used as the substrate to be processed S, and the temperature of the substrate to be processed, the flow rate of N ₂ gas, the flow rate of H ₂ gas, the flow rate of NF ₃ gas, and the RF for generating H ₂ plasma are set. It carried out like the above. A series of processes for etching the SiO ₂ film existing on the Si wafer and removing the etching residual product (NH ₄ ) ₂ SiF ₆ are schematically shown in FIGS. 9B to 9D. That is, when the SiO ₂ film existing on the Si wafer is treated with NHF and the SiO ₂ film is etched, a residual product (NH ₄ ) ₂ SiF ₆ is generated (FIG. 9B), and then the deposited residual product Is removed (region A in FIG. 9A; FIG. 9C), and if the removal process is continued, residual products are finally removed (region B in FIG. 9A; FIG. 9D). )). This region B shows the thickness of the etched SiO ₂ film. For convenience, the etching amount was measured under the assumption that the thickness does not change even when SiO ₂ becomes (NH ₄ ) ₂ SiF ₆ , so the etching amounts in the regions A and B approximate to relative values.

As is apparent from FIG. 9, the etching amount increased with the RF irradiation time (RF application time) to the second shower plate 48 and was saturated at 120 seconds. That is, it can be understood that the etching residual product can be removed even at the substrate temperature of 25 ° C., and the removal process can be made low temperature by using H ₂ plasma together.

FIG. 10 shows the RF irradiation time (seconds) when the frequency of the first high-frequency power supply 45a is changed (13.56 MHz, 40 MHz, and 80 MHz) and the etching amount (etching) of the SiO ₂ film measured by the optical film thickness meter. (Thickness (nm)). In this case, the Si wafer as described above is used as the substrate to be processed S, and the temperature of the substrate to be processed, the flow rate of N ₂ gas, the flow rate of H ₂ gas, the flow rate of NF ₃ gas, and the RF for generating H ₂ plasma are set. It carried out like the above.

As is apparent from FIG. 10, it can be seen that the etching rate (etching thickness) is higher in the case of 40 MHz than in the case of 13.56 MHz. This is presumably because the plasma density increased as the frequency increased, and the NF _x H _y radicals increased. This is because it is generally said that plasma increases in proportion to the square of the frequency. On the other hand, at 80 MHz, the etching rate is extremely reduced. This is because the impedance of the entire apparatus becomes high at 80 MHz, and the input power is almost consumed before entering the plasma. Although discharge was possible at 80 MHz, the discharge limit was 95 MHz, and discharge was not possible at 100 MHz. From the above, the lower limit of the frequency that can be used in the present invention is 13.56 MHz, which can be obtained at low cost, and the upper limit is less than 100 MHz. For example, 27 MHz, 40 MHz, etc. can be mentioned. Although discharge is possible even at a frequency lower than 13.56 MHz, 13.56 MHz, which can be obtained at a low cost, is preferably set as the lower limit.

  After performing the above-described series of processes, that is, the etching processes (1) to (9) and the etching residual product removal process shown in FIGS. 8 to 10, the plasma generation chamber of the radical cleaning apparatus shown in FIG. When the state in 46 was observed, no trace of damage was observed on the inner wall, and it was not consumed, and the temperature of the substrate when removing the etching residual product could be lowered.

  According to the present invention, it is possible to extend the life of the plasma generation chamber by reducing the consumption of the inner wall of the plasma generation chamber, and to perform processing at a low temperature. Since a method can be provided, the present invention can be used for radical cleaning of a surface of a substrate to be processed in a technical field such as a semiconductor device.

DESCRIPTION OF SYMBOLS 1 Quartz tube 2 Gas introduction system 3 Matching device 4 Waveguide 5 Vacuum tank 21 Vacuum tank 21a (Vacuum tank) Upper lid 21b Substrate conveyance port 21c Gas introduction port 21d Exhaust port 22 Substrate support stage 23 Heating means 24 Microwave introduction means 25 μ-wave shielding member 26 μ-wave diffusion dielectric member 27 Plasma generation chamber (space)
27a Side wall 27b Gas inlet 28 First shower plate 28a Sealing seal member 28b High frequency power source 29 Second shower plate 29a Gas inlet 29b Sealing seal member 30 Radical generation chamber (space) 31 Vacuum chamber P1, P2 Plasma S Processed Substrate 41 Vacuum chamber 41a (Vacuum chamber) Upper lid 41b Substrate transport port 41c Gas inlet 41d Exhaust port 42 Substrate support stage 43 Heating means 44 Gas introducing member 44a Gas inlet 45 (for high frequency (RF)) Top plate 45a High frequency (RF) Power supply 45b, 45c Sealing member 46 Plasma generation chamber (space)
46a Side wall of plasma generation chamber 47 First shower plate 47a Sealing seal member 47b High frequency power supply (RF power supply)
48 Second shower plate 48a Sealing member 48b Gas inlet 49 Radical generation chamber (space)
50 vacuum chamber

Claims (17)

In a radical cleaning apparatus having a vacuum chamber, a substrate support stage for placing a substrate to be processed is installed in the vacuum chamber, and plasma is generated by the μ wave applying means or the high frequency applying means and the μ wave applying means or the high frequency applying means. A plasma generation chamber for generating a gas, a first shower plate connected to a high frequency power source provided under the plasma generation chamber, and a second shower plate also serving as a discharge electrode provided under the first shower plate Comprising a radical generating chamber defined by the first shower plate and the second shower plate, below the first shower plate and above the second shower plate, Radical cleaning characterized in that it is configured to etch a substrate to be processed and to remove radicals remaining by etching and to perform radical cleaning. -Ning device. 2. The radical cleaning apparatus according to claim 1, wherein the μ wave applying means comprises a μ wave introducing means, a μ wave shielding member, and a μ wave diffusing dielectric member, and the high frequency applying means includes a gas inside. A radical cleaning device comprising: a gas introduction member provided with an introduction path; and a top plate to which a high-frequency power source provided under the gas introduction member is connected. 3. The radical cleaning apparatus according to claim 1 or 2, further comprising means for switching between application of a high-frequency power source to the first shower plate and grounding in order to set the first shower plate to ground potential. A radical cleaning device. In a radical cleaning apparatus having a vacuum chamber, a substrate support stage for placing a substrate to be processed is installed in the vacuum chamber, and plasma is generated by the μ wave applying means or the high frequency applying means and the μ wave applying means or the high frequency applying means. A plasma generation chamber for generating a gas, a first shower plate connected to a high frequency power source provided under the plasma generation chamber, and a radical generation chamber provided under the first shower plate, A radical cleaning apparatus configured to perform radical cleaning after etching the substrate to be processed. 5. The radical cleaning apparatus according to claim 4, wherein the μ wave applying means comprises a μ wave introducing means, a μ wave shielding member, and a μ wave diffusing dielectric member, and the high frequency applying means includes a gas inside. A radical cleaning device comprising: a gas introduction member provided with an introduction path; and a top plate to which a high-frequency power source provided under the gas introduction member is connected. The radical cleaning apparatus according to claim 4 or 5, further comprising a second shower plate that also serves as a discharge electrode provided under the first shower plate, wherein the radical generation chamber includes the first shower plate and the second shower plate. A space defined by the second shower plate, configured to generate a plasma in a space on the substrate to be processed, and to remove radicals generated by the etching to perform radical cleaning. A radical cleaning device. The radical cleaning device according to any one of claims 4 to 6, further comprising means for switching between application of a high-frequency power source to the first shower plate and grounding in order to set the first shower plate to ground potential. A radical cleaning device comprising: The radical cleaning apparatus according to any one of claims 1 to 7, wherein the apparatus is a single wafer apparatus for cleaning substrates to be processed one by one, or a batch apparatus for simultaneously processing a large number of sheets. Radical cleaning device. A method for performing radical cleaning in a vacuum chamber, in which N ₂ gas and H radical generating gas are introduced into a plasma generating chamber, and plasma is generated by applying μ wave or high frequency, and the plasma generates the gas. Is decomposed to generate H radicals, and the H radicals are passed through the first shower plate having a ground potential to be introduced into the radical generating chamber, and NF ₃ gas is introduced into the radical generating chamber. NF _x H _y (x = 1 to 3, y = 1 to 4) radicals are generated by reacting with NF ₃ gas, and the NF _x H _y radicals on the substrate to be processed placed in the vacuum chamber Is applied to etch the surface of the substrate to be processed, and then the application of the μ wave or high frequency is stopped, and the introduction of the N ₂ gas, H radical generating gas and NF ₃ gas is stopped. And introducing an inert gas into the vacuum chamber and applying a high frequency to the first shower plate to apply a high frequency to the second shower plate that also serves as a discharge electrode to cause discharge. A radical cleaning method comprising: generating plasma on a substrate to be processed placed on the substrate; and evaporating and removing etching residual products generated by the etching using ions and radicals of the plasma. The radical cleaning method according to claim 9, wherein the inert gas is introduced into the vacuum chamber through the N ₂ gas and H radical generating gas inlet or the NF ₃ gas inlet. Or the radical cleaning method characterized by introduce | transducing directly in this vacuum chamber. The radical cleaning method according to claim 9 or 10, wherein the inert gas is at least one gas selected from the group consisting of H ₂ , Ar, He, Ne, and Xe. Cleaning method. A method for performing radical cleaning in a vacuum chamber, in which N ₂ gas and H radical generating gas are introduced into a plasma generating chamber, and plasma is generated by applying μ wave or high frequency, and the plasma generates the gas. Is decomposed to generate H radicals, and the H radicals are passed through the first shower plate having a ground potential to be introduced into the radical generating chamber, and NF ₃ gas is introduced into the radical generating chamber. NF _x H _y (x = 1 to 3, y = 1 to 4) radicals are generated by reacting with NF ₃ gas, and the NF _x H _y radicals on the substrate to be processed placed in the vacuum chamber A radical cleaning method characterized by etching the surface of a substrate to be processed by irradiating the substrate. After etching the surface of the substrate to be processed by the method according to claim 12, the application of the μ wave or high frequency is stopped, and the introduction of the N ₂ gas, the H radical generating gas and the NF ₃ gas is stopped, An inert gas is introduced into the vacuum chamber, and a high frequency is applied to the first shower plate so that a high frequency is applied to the second shower plate that also serves as a discharge electrode to cause discharge. A radical cleaning method comprising: generating plasma on a substrate to be processed; and using the ions and radicals of the plasma to evaporate and remove etching residual products generated by the etching. The radical cleaning method according to claim 13, wherein the inert gas is introduced into the vacuum chamber through the N ₂ gas and H radical generating gas inlet or the NF ₃ gas inlet. Or the radical cleaning method characterized by introduce | transducing directly in this vacuum chamber. The radical cleaning method according to claim 13 or 14, wherein the inert gas is at least one kind of gas selected from the group consisting of H ₂ , Ar, He, Ne, and Xe. Cleaning method. In radical cleaning method according to any one of claims 9 to 15, as該被substrate, a radical cleaning method characterized by using a substrate SiO ₂ film is formed on the surface thereof. The radical cleaning method according to any one of claims 9 to 16, wherein the radical cleaning is performed using the radical cleaning device according to any one of claims 1 to 8. .

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