JP3564222B2 - Plasma processing method and apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma processing method using plasma such as etching, sputtering, or CVD, and a plasma processing apparatus used for the method, and more particularly to a technique capable of selectively removing fine particles (particles) that are problematic in a plasma process. is there.
[0002]
[Prior art]
FIG. 9 shows a schematic configuration of a conventional first plasma processing apparatus capable of removing fine particles present in a chamber. The first plasma processing apparatus includes a chamber 100 for generating plasma, An exhaust device 101 capable of exhausting gas in the chamber 100 at high speed is provided. In the first plasma processing apparatus, a reaction product generated in plasma or on a sample surface, a substance obtained by polymerizing the reactive product in a gas phase, and a reaction product attached to a wall surface of the chamber 100 or a sample surface are desorbed. By discharging the fine particles made of a substance or the like taken into the plasma to the outside of the chamber 100 by the exhaust device 101, the fine particles are removed.
[0003]
FIG. 10 shows a schematic configuration of a second conventional plasma processing apparatus capable of removing fine particles. The second plasma processing apparatus includes a chamber 110 for generating plasma, and a chamber 110 in the chamber 110. A source gas supply unit 111 for supplying a source gas and a decomposition gas supply unit 112 for supplying a decomposition gas for preventing a reaction product generated in plasma from being polymerized in a gas phase in the chamber 110 are provided. . In the second plasma processing apparatus, the fine particles are decomposed by the decomposed gas supplied from the decomposed gas supply means 112 to remove the fine particles.
[0004]
[Problems to be solved by the invention]
However, the first plasma processing apparatus requires an expensive and large-capacity exhaust device, and the exhaust device discharges not only the fine particles but also the raw material gas at the same ratio as the fine particles. There is a problem that is bad.
[0005]
In addition, in the second plasma processing apparatus, a decomposition gas capable of decomposing the fine particles made of a specific reaction product has been found for fine particles composed of a specific reaction product. At present, the decomposition gas corresponding to is not sufficiently found.
[0006]
In view of the above, the present invention does not require an expensive and large-capacity exhaust device, can cope with any combination of source gases and processes, and can selectively remove fine particles from a chamber. The purpose is to do.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a first plasma processing method according to the present invention includes a fine particle moving step of moving fine particles present in a plasma generation region in a chamber to a peripheral portion of the plasma generation region; A fine particle discharging step of discharging fine particles moved to a peripheral portion of the region to the outside of the chamber.
[0008]
According to the first plasma processing method, the fine particles present in the plasma generation region are moved to the peripheral portion of the plasma generation region and then discharged to the outside of the chamber. Therefore, the fine particles can be selectively discharged to the outside of the chamber. .
[0009]
In the first plasma processing method, the fine particle moving step may include generating a magnetic field in a direction perpendicular to a surface of the sample placed in the chamber and generating a high-frequency electric field in a direction parallel to the surface of the sample. Preferably, the method includes a step of causing the particles present in the plasma generation region to perform a resonance cyclotron motion, thereby moving the particles present in the plasma generation region to a peripheral portion of the plasma generation region.
[0010]
In the first plasma processing method, the fine particle discharging step includes a step of sucking fine particles moved to a peripheral portion of the plasma generation region into a cylindrical grid to which a positive voltage is applied by Coulomb force; Discharging the fine particles sucked into the chamber to the outside of the chamber by a reduced pressure.
[0011]
In a second plasma processing method according to the present invention, the flow rate of a gas introduced into a chamber having a plasma generation region is controlled to a predetermined value or less, and the pressure of the gas introduced into the chamber is controlled within a predetermined range. Thus, a fine particle moving step of moving fine particles present in the plasma generation region to a boundary portion between the plasma generation region and the sheath region, and moving the fine particles moving to a boundary portion between the plasma generation region and the sheath region in the chamber. And a step of discharging fine particles to the outside of the device. Here, the gas flow rate equal to or less than the predetermined value refers to a gas flow rate in which the motion of the fine particles present in the plasma generation region is mainly governed by the electric field force and the momentum transfer force from the ions, and the gas pressure within the predetermined range. Refers to a gas pressure at which the momentum transfer force from the ions in the sheath region becomes larger than the electric field force, and the plasma is stably generated in the plasma generation region and the generated plasma is maintained.
[0012]
According to the second plasma processing method, the gas flow velocity is equal to or less than a predetermined value, that is, the gas flow velocity is such that the movement of the fine particles present in the plasma generation region is mainly governed by the electric field force and the momentum transfer force from the ions. Can be controlled by the electric field force and the momentum transfer force from the ions. In the sheath region, the gas pressure is such that the momentum transfer force from the ions is larger than the electric field force, while the gas pressure is such that the electric field force is larger than the momentum transfer force from the ions in the plasma generation region. At the boundary with the sheath region, the electric field force balances with the momentum transfer force from the ions, so that the fine particles are confined at the boundary between the plasma generation region and the sheath region. Further, since the gas pressure is such that the plasma is generated stably in the plasma generation region and the generated plasma is maintained, the operation of the plasma in the plasma generation region is not impaired.
[0013]
In the second plasma processing method, in the fine particle discharging step, a position of a boundary portion between the plasma generation region and the sheath region is detected by an optical method, and a boundary between the detected plasma generation region and the sheath region is detected. It is preferable to include a step of discharging the fine particles present in the portion to the outside of the chamber.
[0014]
In the second plasma processing method, the fine particle moving step includes a step of moving fine particles present in the plasma generation region to a boundary portion between the plasma generation region and the sheath region and to a peripheral portion of the plasma generation region. Preferably, the fine particle discharging step includes a step of discharging fine particles that have moved to a boundary portion between the plasma generation region and the sheath region and to a peripheral portion of the plasma generation region to the outside of the chamber.
[0015]
In the second plasma processing method, the fine particle moving step may include generating a magnetic field in a direction perpendicular to a surface of the sample placed in the chamber and generating a high-frequency electric field in a direction parallel to the surface of the sample. Causes the particles present in the plasma generation region to undergo resonant cyclotron motion, thereby causing the particles present in the plasma generation region to move at the boundary between the plasma generation region and the sheath region and at the peripheral portion of the plasma generation region. It is preferable to include a step of moving to.
[0016]
A third plasma processing method according to the present invention is characterized in that a magnetic field line extending between a plasma generation region of a plasma generation chamber and a fine particle discharge region provided to communicate with the plasma generation region is formed, Moving the fine particles in the plasma generation region along the line of magnetic force to move the fine particles in the plasma generation region to the fine particle discharge region; and discharging the fine particles guided to the fine particle discharge region to the outside of the chamber. And a step of discharging fine particles.
[0017]
According to the third plasma processing method, the fine particles are moved along the line of magnetic force straddling between the plasma generation region and the fine particle discharge region, so that the fine particles in the plasma generation region can be guided to the fine particle discharge region. The fine particles guided to the chamber are discharged to the outside of the chamber, so that the spatiotemporal structure of the plasma in the plasma generation region is not disturbed.
[0018]
In the third plasma process method, in the fine particle discharging step, the fine particles guided to the fine particle discharging area may be attached to a diverter member provided in the fine particle discharging area; A step of taking the particles out of the fine particle discharge region.
[0019]
In the third plasma processing method, the fine particle discharging step preferably includes a step of discharging the fine particles guided to the fine particle discharging region to the outside of the fine particle discharging region by a reduced pressure.
[0020]
In the third plasma processing method, it is preferable that the magnetic field lines are separatrix magnetic field lines.
[0021]
The first plasma processing apparatus according to the present invention includes: a fine particle moving unit configured to move fine particles present in a plasma generation region in a chamber to a peripheral portion of the plasma generation region; A fine particle discharging means for discharging the fine particles to the outside of the chamber.
[0022]
With the first plasma processing apparatus, the fine particles in the plasma generation region can be moved to the peripheral portion of the plasma generation region by the fine particle moving means, and the fine particles moved to the peripheral portion of the plasma generation region can be moved to the peripheral portion of the chamber by the fine particle discharge device. Can be discharged outside.
[0023]
In the first plasma processing apparatus, the fine particle moving means may include a magnetic field generating means for generating a magnetic field in a direction perpendicular to a surface of the sample placed in the chamber, and a high frequency electric field in a direction parallel to the surface of the sample. A means for generating high-frequency electric field generating means for causing fine particles present in the plasma generation region to undergo a resonance cyclotron motion to move fine particles present in the plasma generation region to a peripheral portion of the plasma generation region. Is preferred.
[0024]
In the first plasma processing apparatus, the fine particle discharging means may include a cylindrical grid that applies a positive voltage to move the fine particles that have moved to the peripheral portion of the plasma generation region by Coulomb force, and that is drawn into the grid. It is preferable that the apparatus further comprises exhaust means for discharging the fine particles to the outside of the chamber by a reduced pressure.
[0025]
The second plasma processing apparatus according to the present invention, by controlling the flow rate of the gas introduced into the chamber to a predetermined value or less and controlling the pressure of the gas introduced into the chamber within a predetermined range, Fine particle moving means for moving fine particles present in the plasma generation region in the chamber to the boundary between the plasma generation region and the sheath region; and fine particles moving to the boundary between the plasma generation region and the sheath region in the chamber. And a means for discharging fine particles to the outside. Here, the gas flow rate equal to or less than the predetermined value refers to a gas flow rate in which the motion of the fine particles present in the plasma generation region is mainly governed by the electric field force and the momentum transfer force from the ions, and the gas pressure within the predetermined range. Refers to a gas pressure at which the momentum transfer force from the ions in the sheath region becomes larger than the electric field force, and the plasma is stably generated in the plasma generation region and the generated plasma is maintained.
[0026]
The second plasma processing apparatus controls the gas flow rate such that the movement of the fine particles is mainly governed by the electric field force and the momentum transfer force from the ions. Therefore, the movement of the fine particles is controlled by the electric field force and the momentum transfer force from the ions. can do. In addition, since the gas pressure is controlled so that the movement of the fine particles in the sheath region has a larger momentum transfer force from the ions than the electric field force, at the boundary between the plasma generation region and the sheath region, the electric field force and the momentum transfer from the ions are increased. Since the force balances the electric field force, the fine particles are confined at the boundary between the plasma generation region and the sheath region. Further, since the gas pressure is controlled such that the plasma is generated stably in the plasma generation region and the generated plasma is maintained, the operation of the plasma in the plasma generation region is not impaired.
[0027]
It is preferable that the second plasma processing apparatus further includes a boundary detection unit that detects a position of a boundary between the plasma generation region and the sheath region.
[0028]
In this case, it is preferable that the boundary detecting means is an emitting probe.
[0029]
In the second plasma processing apparatus, it is preferable that the fine particle discharge unit is provided so as to move to a boundary between the plasma generation region and the sheath region detected by the boundary detection unit.
[0030]
In the second plasma processing apparatus, it is preferable that the apparatus further includes a fine particle peripheral portion moving means for moving fine particles present in the plasma generating region to a peripheral portion of the plasma generating region.
[0031]
In the second plasma processing apparatus, the fine particle peripheral portion moving means may include a magnetic field generating means for generating a magnetic field in a direction perpendicular to a surface of the sample placed in the chamber, and a high frequency in a direction parallel to the surface of the sample. A high-frequency electric field generating means for generating an electric field, wherein the fine particles present in the plasma generation region are subjected to resonance cyclotron motion to move the fine particles present in the plasma generation region to a peripheral portion of the plasma generation region. Preferably, there is.
[0032]
In the second plasma processing apparatus, the fine particle discharging means may include a cylindrical grid that applies a positive voltage to move the fine particles that have moved to the peripheral portion of the plasma generation region by Coulomb force, and that is drawn into the grid. It is preferable that the apparatus further comprises exhaust means for discharging the fine particles to the outside of the chamber by a reduced pressure.
[0033]
A third plasma processing apparatus according to the present invention includes a plasma generation chamber having a plasma generation region, a particle discharge chamber having a particle discharge region communicating with the plasma generation region, the plasma generation region and the particle discharge region. A fine particle moving means for guiding the fine particles in the plasma generation region to the fine particle discharge region by forming fine lines of magnetic force straddling between the fine particles and moving the fine particles in the plasma generating region along the lines of magnetic force; And a fine particle discharging means for discharging fine particles guided to the discharge region to the outside of the chamber.
[0034]
The third plasma processing apparatus guides the fine particles to the fine particle discharge region along the magnetic field lines extending between the plasma generation region and the fine particle discharge region, and discharges the fine particles guided to the fine particle discharge region to the outside of the chamber. In addition, the spatiotemporal structure of the plasma in the plasma generation region is not disturbed.
[0035]
In the third plasma processing apparatus, the fine particle moving means is provided so as to extend around a center of the fine particle discharging chamber and a helical coil provided so as to surround the plasma generating chamber and the fine particle discharge chamber. It is preferable that the coil comprises a linear coil.
[0036]
In the third plasma processing apparatus, it is preferable that the fine particle discharging means has a diverter member provided on the magnetic field lines in the fine particle discharging area and to which fine particles moving along the magnetic field lines adhere.
[0037]
In the third plasma processing apparatus, the fine particle discharge means has a suction port on the magnetic field line in the fine particle discharge area, and sucks the fine particles moving along the magnetic field line from the suction port by a decompression force to reduce the fine particles. It is preferable to have a fine particle suction means for discharging to the outside of the discharge area.
[0038]
In the third plasma processing apparatus, the magnetic field lines are preferably separatrix magnetic field lines.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a plasma processing method and an apparatus therefor according to each embodiment of the present invention will be described. As a premise, a solution principle of the present invention will be described with reference to FIGS. 6 and 7, 1 is a chamber, 2 is an anode electrode, 3 is a cathode electrode, 4 is a high frequency power supply connected to the cathode electrode 3 via a coupling capacitor 5, 6 is a bulk plasma region, and 7 is a sheath region. It is.
[0040]
Electrons and ions are incident on the surface of the fine particles present in the plasma, but the electrons are lighter than the ions and fly at high speed in the plasma, so there is a high probability that they will collide with and adhere to the surface of the fine particles. Is negatively charged. Further, the fine particles are transported by receiving a momentum transfer force from ions, a force due to a temperature gradient of gas, a force from a gas flow, and gravity, in addition to the electric field force. The momentum transfer force that the particles receive from the ions is represented by the sum of the force received from the ions reaching the particle surface and the force received when the ions bend at the sheath around the particles.
[0041]
The charge amount of the fine particles is substantially proportional to the diameter of the fine particles, and is 10 -16 to 10 -15 coulomb when the diameter of the fine particles is, for example, 0.1 μm to 1 μm.
[0042]
When the gas flow rate is relatively small, the particles are mainly governed by the electric field force FE and the momentum transfer force Fm from the ions.
[0043]
When the gas pressure is relatively high, the electric field force becomes larger than the momentum transfer force from the ions in the plasma generation region. Therefore, the fine particles p are almost uniformly confined in the bulk plasma region 6 as shown in FIG. Can be On the other hand, when the gas pressure is relatively low, the momentum transfer force from the ions is larger than the electric field force in the sheath region 7, and therefore, as shown in FIG. Particles p collect at the bulk plasma / sheath boundary where the balance is achieved.
[0044]
Hereinafter, a cyclotron resonance method as a method for moving the negatively charged fine particles p to the vicinity of the side wall of the chamber 1 will be described with reference to FIG.
[0045]
FIGS. 5A and 5B show the locus of cyclotron motion of the fine particles p when a uniform magnetic field B exists in the direction between the electrodes connecting the anode electrode and the cathode electrode, and FIG. 5A is a plan view. (B) is a side view. FIG. 5C shows the locus of the fine particles p when a high-frequency electric field E having a frequency fE that resonates with the frequency fc of the cyclotron motion is applied in a direction perpendicular to the direction of the magnetic field B in addition to the uniform magnetic field B. FIG.
[0046]
When the direction of the electric field E changes from the downward direction to the upward direction in FIG. 5C when the fine particle p passes through the point T on the locus of the fine particle p shown in FIG. 5C, the fine particle p is attracted to the electric field E. To the side wall 8 of the chamber.
[0047]
Hereinafter, a method for selectively removing fine particles from the chamber will be described with reference to the flowchart of FIG.
[0048]
First, in step 1, when the gas pressure in the chamber is relatively high during the process of generating plasma, if the gas pressure in the chamber is relatively high, the gas pressure is reduced as much as possible within a range necessary to stably generate and maintain the plasma. Lower. If the gas pressure in the chamber is relatively low, the gas pressure is maintained.
[0049]
Next, in step 2, when the gas flow rate in the chamber is high, the gas flow rate is reduced as much as possible. Due to the steps 1 and 2, most of the particles collect at the bulk plasma / sheath interface.
[0050]
Next, in step 3, the position of the bulk plasma / sheath boundary is detected by an emissive probe or the like.
[0051]
Although the steps 1 to 3 are not always necessary, most of the fine particles can be collected at the bulk plasma / sheath boundary and the position of the bulk plasma / sheath boundary is detected through these steps. Therefore, the subsequent step of selectively removing fine particles can be efficiently performed.
[0052]
Next, in step 4, a spatially uniform magnetic field in the direction between the electrodes and a high-frequency electric field in a direction orthogonal to the direction between the electrodes are applied to the chamber to form a resonance cyclotron corresponding to the specific charge of the fine particles. The movement causes the fine particles to move to the periphery of the plasma generation region, that is, to the vicinity of the side wall of the chamber. This makes it possible to perform the subsequent selective fine particle removal step more efficiently.
[0053]
Next, in step 5, the fine particles in the chamber are discharged to the outside of the chamber by suction, adsorption or forced exhaustion.
[0054]
As a method of discharging the fine particles to the outside of the chamber, a grid having a positive voltage applied so as not to disturb the spatiotemporal structure of the plasma is provided, and the bulk plasma / sheath is determined based on the positional information of the bulk plasma / sheath boundary. A method can be employed in which fine particles in the chamber are suctioned and selectively removed by a fine particle exhaust device that can move to the boundary. Further, instead of the above-described particulate exhaust device having a grid to which a positive voltage is applied, a particulate exhaust chamber is provided so as to communicate with the plasma generating chamber, and a magnetic field generating coil is appropriately combined and arranged. By forming a separatrix magnetic field line, that is, a diverter magnetic field, straddling both chambers, and installing a diverter plate so as to intersect with the separatrix magnetic field line in the particle exhaust chamber, fine particles moving along the separatrix magnetic field line are removed. It can also be discharged by adsorbing on a diverter plate. Note that the former method of discharging fine particles by the fine particle exhaust device having a grid will be described in detail in the first embodiment, and the latter method of discharging fine particles by a diverter plate that intersects with the separatrix magnetic field lines will be described in the second embodiment. The embodiment will be described in detail.
[0055]
Through the above-described steps, the fine particles collected at the boundary between the bulk plasma and the sheath can be selectively and efficiently discharged.
[0056]
Hereinafter, a plasma processing method and a plasma processing apparatus provided with a selective particle exhaust device according to a first embodiment of the present invention will be described with reference to FIGS.
[0057]
FIG. 1 shows a cross-sectional structure of the parallel plate type plasma processing apparatus according to the first embodiment, and FIG. 2 shows a longitudinal cross-sectional structure. As shown in FIG. 2, an anode electrode 12 and a cathode electrode 13 are arranged in a chamber 11, and the cathode electrode 13 is connected to a high frequency power supply 15 via a coupling capacitor 14. Thus, a bulk plasma region 16 is formed between the anode electrode 12 and the cathode electrode 13, and a sheath region 17 is formed near the anode electrode 12 and the cathode electrode 13, respectively.
[0058]
As a feature of the first embodiment, as shown in FIGS. 1 and 2, an emitter for detecting position information of each bulk plasma / sheath boundary (hereinafter, referred to as a bulk sheath boundary) is provided on the side wall of the chamber 11. Bulk sheath boundary detection devices including a sib probe 18 and the like are installed so as to face each other. At the boundary of each bulk sheath in the chamber 11, fine particle extraction devices 19 having a cylindrical grid to which a positive voltage that does not disturb the spatiotemporal structure of the plasma is arranged so as to face each other. An exhaust device 20 is connected to one end of the particle extracting device 19. Thus, the fine particles collected by the fine particle extracting device 19 are discharged to the outside of the chamber 11 by the exhaust device 20. Each particle extracting device 19 is movable in the vertical direction in FIG. 2 and moves to the bulk sheath boundary based on the position information of the bulk sheath boundary detected by the emissive probe 18.
[0059]
When the gas flow velocity is small, the particles are mainly governed by the electric field force and the momentum transfer force from the ions. When the gas pressure is relatively high (when the distance between the electrodes is L and the mean free path of the fine particles is λ, the gas pressure is such that L / λ becomes approximately 10 or more), the bulk plasma region At 16, since the electric field force is superior to the momentum transfer force from the ions, the fine particles are almost uniformly confined in the bulk plasma region 16, while the gas pressure is relatively low (L / λ becomes approximately 2-3). In the case of such a gas pressure), in the sheath region 17, the momentum transfer force from the ions becomes larger than the electric field force, so that the fine particles gather at the bulk sheath boundary portion where the electric field force and the momentum transfer force from the ions balance.
[0060]
During a plasma process performed while generating plasma, if the gas pressure in the chamber 11 is relatively high, the gas pressure is reduced as much as possible within the range of the gas pressure necessary to stably generate and maintain the plasma. Preferably, when the gas pressure in the chamber 11 is relatively low, the gas pressure is maintained as it is. As a result, most of the fine particles gather at the boundary of the bulk sheath. Specifically, when the gas pressure is higher than a predetermined value, it is preferable to reduce the gas pressure to a value necessary for stably generating and maintaining plasma.
[0061]
Hereinafter, the case of plasma etching of a polysilicon film performed by using HBr gas as a plasma processing method will be specifically described. Plasma etching was performed under the conditions of a gas flow rate of 200 sccm and a gas pressure of 10 Pa. After plasma etching was performed on 10 wafers, the gas flow rate was reduced to 80 sccm and the gas pressure was reduced to 5 Pa. After maintaining this state for 1 minute, the state was returned to the original state, and the plasma etching on the wafer was continued. did. The fine particle extracting device 19 was operated from the beginning of the etching all the time.
[0062]
As a result, the fine particles collected at the boundary of the bulk sheath could be selectively removed, and an extremely clean plasma process could be realized.
[0063]
In the first embodiment, as shown in FIGS. 1 and 2, external electrodes 21 are arranged so as to face each other at a portion corresponding to each bulk sheath boundary outside the chamber 11, and each external electrode 21 A high-frequency power source 22 is connected to generate a high-frequency electric field in a direction parallel to the sample surface (a direction orthogonal to the direction between the electrodes), and a plurality of circular coils or permanent magnets (not shown) are appropriately arranged. As shown by an arrow 23 in FIG. 2, a uniform magnetic field is generated in a direction perpendicular to the sample surface (inter-electrode direction) to cause the particles to perform a resonance cyclotron motion corresponding to the specific charge of the particles. Accordingly, when the fine particles existing in the bulk plasma region 16 are promptly moved to the peripheral portion of the chamber 11, that is, near the side wall of the chamber 11, the selective removal of the fine particles is more efficiently performed. It can be carried out.
[0064]
Specific methods for the magnetic field and the electric field are as follows. That is, a magnetic field of 1 to 100 Gauss is applied while being spatially uniform and temporally constant or changing at a period of 10 Hz. Also, 13.56 MHz high frequency power is applied so that the amplitude intensity of the high frequency electric field becomes 100 V / m.
[0065]
Hereinafter, a plasma processing method and a plasma processing apparatus provided with the selective particle exhaust device according to the second embodiment of the present invention will be described with reference to FIGS.
[0066]
FIG. 3 shows a cross-sectional structure of the parallel plate type plasma processing apparatus according to the second embodiment, and FIG. 4 shows a longitudinal cross-sectional structure. As shown in FIG. 3, a plasma generation chamber 31 and a particulate discharge chamber 32 are provided so as to communicate with each other via a communication portion 33. An anode electrode 34 and a cathode electrode 35 are arranged in the plasma generation chamber 31, and the cathode electrode 35 is connected to a high-frequency power supply 37 via a coupling capacitor 36. Thus, a bulk plasma region 38 is formed between the anode electrode 34 and the cathode electrode 35, and a sheath region 39 is formed near the anode electrode 34 and the cathode electrode 35, respectively. Although not shown, an emissive probe for detecting the position information of the boundary portion of the bulk sheath is provided on the side wall of the plasma generation chamber 31 as in the first embodiment.
[0067]
As shown in FIGS. 3 and 4, a circular helical coil 40 spirally surrounds the plasma generation chamber 31 and the particle discharge chamber 32, and a linear coil 41 extending in the direction between the electrodes at the center of the particle discharge chamber 32. , A first DC voltage source 42 is connected to the circular helical coil 40, and a second DC voltage source 43 is connected to the linear coil 41. As a result, as shown in FIG. 3, a cross-shaped (8-shaped) separatrix magnetic field line 44, that is, a diverter magnetic field, is formed in the plasma generation chamber 31 and the fine particle discharge chamber 32 through the communicating portion 33. As shown in FIGS. 3 and 4, a diverter plate 45 is installed inside the particle discharge chamber 32 so as to intersect the separatrix magnetic lines of force 44.
[0068]
Since the moving speed of the charged fine particles in the direction along the line of magnetic force is much higher than the moving speed in the direction of crossing the line of magnetic force, the charged fine particles are generated in the plasma generation chamber 31 and move to the vicinity of the side wall of the plasma processing chamber 31. As shown in FIG. 3, the charged fine particles rapidly spiral around the separatrix magnetic field lines 44 in a spiral manner. At this time, since the diverter plate 45 is installed so as to intersect the separatrix magnetic lines of force 44, the fine particles circulating along the separatrix lines of magnetic force 44 adhere to the diverter plate 45. Then, by removing the diverter plate 45 to the outside of the fine particle discharge chamber 32, the fine particles can be efficiently discharged.
[0069]
The circular helical coil 40 generates a magnetic field in the direction perpendicular to the sample surface (direction between electrodes) spatially uniformly as described in the first embodiment. By generating a high-frequency electric field in a direction parallel to the direction (direction perpendicular to the direction between the electrodes), the particles perform a resonance cyclotron motion corresponding to the specific charge of the particles, and the particles existing in the bulk plasma region 38 are used for plasma generation. Since it can be moved near the side wall of the chamber 31, that is, toward the separatrix magnetic field lines 44, the selective removal of fine particles can be performed more efficiently.
[0070]
In this case, the conditions of the gas type, the gas flow rate and the gas pressure are the same as in the first embodiment. That is, the strength of the magnetic field in the direction between the electrodes in the plasma generating chamber 31 is 20 Gauss, the strength of the rotating magnetic field in the direction perpendicular to the direction between the electrodes is 5 Gauss, and the strength of the rotating magnetic field in the chamber 32 for exhausting fine particles. Is 10 Gauss. However, the direction of rotation of the rotating magnetic field in the chamber 32 for exhausting fine particles is opposite to the direction of the rotating magnetic field in the chamber 31 for plasma generation.
[0071]
【The invention's effect】
According to the first plasma processing method of the present invention, the fine particles present in the plasma generation region are moved to the peripheral portion of the plasma generation region and then discharged to the outside of the chamber. Since the exhaust gas can be exhausted, an expensive and large-capacity exhaust device is not required, and fine particles can be efficiently exhausted to the outside of the chamber regardless of the combination of any source gas and process.
[0072]
In the first plasma processing method, the fine particle moving step generates a magnetic field in a direction perpendicular to the surface of the sample and generates a high-frequency electric field in a direction parallel to the surface of the sample, so that the fine particles existing in the plasma generation region are generated. Including a step of causing a resonance cyclotron motion in the plasma generation region allows fine particles existing in the plasma generation region to be quickly and reliably moved to the peripheral portion of the plasma generation region, so that the particles can be more efficiently discharged to the outside of the chamber. Can be.
[0073]
In the first plasma processing method, in the fine particle discharging step, the fine particles moved to the peripheral portion of the plasma generation region are sucked into a cylindrical grid to which a positive voltage is applied by Coulomb force, and then the chamber is decompressed by a reduced pressure force. Including the step of discharging to the outside, the negatively charged fine particles due to the attachment of electrons are efficiently sucked into the grid, so that the fine particles can be reliably removed without disturbing the spatiotemporal structure of the plasma in the chamber. It can be drained out of the chamber.
[0074]
According to the second plasma processing method of the present invention, the momentum transfer force from ions is larger than the electric field force in the sheath region, while the electric field force is larger than the momentum transfer force from the ions in the plasma generation region. At the boundary between the plasma generation region and the sheath region, the momentum transfer force from the ions balances with the electric field force, and the fine particles are confined at the boundary between the plasma generation region and the sheath region. Can be efficiently discharged to the outside of the chamber, thereby eliminating the need for an expensive and large-volume exhaust device and efficiently discharging fine particles to the outside of the chamber regardless of the combination of any source gas and process. can do.
[0075]
In the second plasma processing method, the fine particle discharging step detects the position of the boundary between the plasma generation region and the sheath region by an optical method, and detects the fine particles existing at the detected boundary between the plasma generation region and the sheath region. If the step of discharging the gas to the outside of the chamber is included, the position of the boundary between the plasma generation region and the sheath region can be accurately known, so that the efficiency of discharging fine particles from the boundary is improved.
[0076]
In the second plasma processing method, the fine particle moving step includes a step of moving fine particles present in the plasma generation region to a boundary portion between the plasma generation region and the sheath region and to a peripheral portion of the plasma generation region. Discharging the fine particles that have moved to the boundary between the plasma generation region and the sheath region and to the periphery of the plasma generation region to the outside of the chamber. After being moved to the outside of the chamber after being moved to the boundary portion of the plasma generation region and the periphery thereof, the locally trapped fine particles can be discharged, so that the fine particle discharge efficiency is further improved.
[0077]
In the second plasma processing method, the fine particle moving step generates a magnetic field in a direction perpendicular to the surface of the sample and generates a high-frequency electric field in a direction parallel to the surface of the sample, so that fine particles existing in the plasma generation region are generated. If the method includes the step of performing the resonance cyclotron motion, the fine particles can be reliably moved to the boundary between the plasma generation region and the sheath region and to the peripheral portion of the plasma generation region, so that the discharge efficiency of the fine particles is further improved.
[0078]
According to the third plasma processing method of the present invention, since the fine particles in the plasma generation region are guided to the fine particle discharge region and then discharged to the outside of the chamber, the plasma spatio-temporal structure in the plasma generation region is not disturbed. Fine particles can be efficiently discharged to the outside of the chamber without affecting the process.
[0079]
In the third plasma process method, the fine particle discharging step includes a step of adhering the fine particles guided to the fine particle discharging area to a diverter member provided in the fine particle discharging area, and a step of attaching the diverter member with the fine particles to the fine particle discharging area. The step of taking out the particles to the outside, the fine particles guided to the fine particle discharge region are attached to the diverter member, and the diverter member to which the fine particles are adhered is taken out of the fine particle discharge region. Can be discharged outside.
[0080]
In the third plasma process method, when the fine particle discharging step includes a step of discharging the fine particles guided to the fine particle discharging region to the outside of the fine particle discharging region by the depressurizing force, the fine particles are easily and reliably discharged to the outside of the chamber. be able to.
[0081]
In the third plasma processing method, when the magnetic field lines are the separatrix magnetic field lines, the fine particles in the plasma generation region can be reliably guided to the fine particle discharge chamber and discharged to the outside of the chamber.
[0082]
According to the first plasma processing apparatus of the present invention, the fine particles moved to the periphery of the plasma generation region by the fine particle moving means can be discharged to the outside of the chamber by the fine particle discharging means. No exhaust device is required, and the fine particles can be efficiently exhausted to the outside of the chamber regardless of the combination of any source gas and process.
[0083]
In the first plasma processing apparatus, the fine particle moving means includes a magnetic field generating means for generating a magnetic field in a direction perpendicular to the surface of the sample disposed in the chamber, and a high frequency for generating a high frequency electric field in a direction parallel to the surface of the sample. The electric field generating means moves the fine particles present in the plasma generation region to the periphery of the plasma generation region by causing the fine particles present in the plasma generation region to move in a resonant cyclotron motion. The magnetic field generating means for generating a magnetic field in any direction, and the high-frequency electric field generating means for generating a high-frequency electric field in a direction parallel to the surface of the sample can cause the particles present in the plasma generation region to undergo resonant cyclotron motion. Particles existing in the plasma generation area are quickly and reliably moved to the periphery of the plasma generation area It is possible to, can be discharged to more efficiently chamber outer microparticles.
[0084]
In the first plasma processing apparatus, the fine particle discharging means includes: a cylindrical grid for suctioning fine particles applied to a peripheral portion of a plasma generation region to which a positive voltage is applied by a Coulomb force; and fine particles sucked inside the grid. And exhaust means for exhausting the gas to the outside of the chamber by the depressurizing force. The fine particles that have moved to the peripheral portion of the plasma generation region are sucked into the cylindrical grid to which a positive voltage is applied by the Coulomb force, and then the depressurizing force is applied. Can be discharged to the outside of the chamber, so that the negatively charged microparticles with attached electrons are sucked into the grid, ensuring that the spatiotemporal structure of the plasma in the chamber is not disturbed outside the chamber. Can be discharged.
[0085]
According to the second plasma processing apparatus of the present invention, at the boundary between the plasma generation region and the sheath region, the momentum transfer force from the ions and the electric field force are balanced, and the fine particles are separated from the boundary between the plasma generation region and the sheath region. Since the particles trapped in the boundary can be efficiently discharged to the outside of the chamber, an expensive and large-capacity exhaust device is not required, and any combination of source gas and process can be used. However, the fine particles can be efficiently discharged to the outside of the chamber.
[0086]
If the second plasma processing apparatus is provided with boundary detecting means for detecting the position of the boundary between the plasma generation region and the sheath region, the position of the boundary between the plasma generation region and the sheath region can be accurately known. Therefore, the efficiency of discharging fine particles from the boundary between the plasma generation region and the sheath region is improved.
[0087]
In this case, if the boundary detection means is an emitting probe, the position of the boundary between the plasma generation region and the sheath region can be accurately detected by an optical method. The efficiency of discharging fine particles is improved.
[0088]
In the second plasma processing apparatus, if the fine particle discharge means is provided so as to move to a boundary between the plasma generation area and the sheath area detected by the boundary detection means, the fine particle discharge means may be connected to the plasma generation area. Since it can move to the boundary between the sheath region, the efficiency of discharging fine particles from the boundary between the plasma generation region and the sheath region is further improved.
[0089]
When the second plasma processing apparatus is provided with fine particle peripheral moving means for moving fine particles present in the plasma generating region to the peripheral portion of the plasma generating region, the fine particle moving means moves the fine particles between the plasma generating region and the sheath region. Since the particles can be moved to the boundary and the particles can be moved to the peripheral portion of the plasma generation region by the particle periphery moving means, the locally trapped particles can be discharged, and the discharge efficiency of the particles can be further improved.
[0090]
In the second plasma processing apparatus, the fine particle peripheral portion moving means generates a magnetic field in a direction perpendicular to the surface of the sample placed in the chamber and a high frequency electric field in a direction parallel to the surface of the sample. A high-frequency electric field generating means for causing the fine particles present in the plasma generation region to undergo a resonance cyclotron motion, thereby moving the fine particles present in the plasma generation region to the periphery of the plasma generation region, and a device perpendicular to the surface of the sample. In addition to generating a magnetic field in various directions and generating a high-frequency electric field in a direction parallel to the surface of the sample, the particles existing in the plasma generation region can be subjected to resonance cyclotron motion, so that the particles can be moved to the plasma generation region and the sheath region. Particles can be reliably moved to the boundary with Emission efficiency can be further improved.
[0091]
In the second plasma processing apparatus, the fine particle discharging means includes: a cylindrical grid for attracting fine particles applied to a peripheral portion of the plasma generation region to which a positive voltage is applied by a Coulomb force; and fine particles sucked into the grid. And exhaust means for exhausting the gas to the outside of the chamber by the depressurizing force. The fine particles that have moved to the peripheral portion of the plasma generation region are sucked into the cylindrical grid to which a positive voltage is applied by the Coulomb force, and then the depressurizing force is applied. Can be discharged to the outside of the chamber, so that the negatively charged microparticles with attached electrons are sucked into the grid, ensuring that the spatiotemporal structure of the plasma in the chamber is not disturbed outside the chamber. Can be discharged.
[0092]
According to the third plasma processing apparatus of the present invention, since the fine particles are guided to the fine particle discharge region along the magnetic force line extending between the plasma generation region and the fine particle discharge region, and then discharged to the outside of the chamber, the plasma generation is performed. The fine particles can be efficiently discharged to the outside of the chamber without disturbing the spatiotemporal structure of the plasma in the region, that is, without affecting the plasma process.
[0093]
In the third plasma processing apparatus, the fine particle moving means includes a helical coil provided so as to surround the plasma generation chamber and the fine particle discharge chamber, and a linear coil provided so as to extend the center of the fine particle discharge chamber. Since the magnetic field lines extending between the plasma generation region and the fine particle discharge region can be reliably formed, the fine particles in the plasma generation region can be reliably guided to the fine particle discharge region.
[0094]
In the third plasma processing apparatus, when the fine particle discharging means has a diverter member provided on the magnetic field line in the fine particle discharging area and to which fine particles moving along the magnetic field line adhere, the fine particle discharging means is guided to the fine particle discharging area. By attaching the fine particles to the diverter member and taking out the diverter member to which the fine particles are attached to the outside of the fine particle discharge region, the fine particles can be easily and reliably discharged to the outside of the chamber.
[0095]
In the third plasma processing apparatus, the fine particle discharge means has a suction port on a magnetic line of force in the fine particle discharge area, and sucks the fine particles moving along the magnetic line of force from the suction port by a depressurizing force and discharges the fine particles to the outside of the fine particle discharge area. With the fine particle suction means, the fine particles can be easily and reliably discharged to the outside of the chamber.
[0096]
In the third plasma processing apparatus, when the magnetic field lines are the separatrix magnetic field lines, the fine particles in the plasma generation region can be reliably guided to the fine particle discharge chamber and discharged to the outside of the chamber.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a plasma processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of the plasma processing apparatus according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view of a plasma processing apparatus according to a second embodiment of the present invention.
FIG. 4 is a longitudinal sectional view of a plasma processing apparatus according to a second embodiment of the present invention.
5 (a) and 5 (b) show the trajectories of cyclotron motion of fine particles in the case where a uniform magnetic field exists in the direction between the electrodes, FIG. 5 (a) is a plan view, and FIG. FIG. (C) is a plan view showing a locus of fine particles when a high-frequency electric field having a frequency that resonates with the frequency of cyclotron motion is applied in a direction perpendicular to the direction of the magnetic field in addition to a uniform magnetic field.
FIGS. 6A and 6B are diagrams showing a state in which fine particles are almost uniformly confined in a bulk plasma region when the gas pressure is relatively high.
FIGS. 7A and 7B are diagrams showing a state in which fine particles gather at a bulk plasma / sheath boundary when the gas pressure is relatively low.
FIG. 8 is a flowchart for explaining the solution principle of the present invention.
FIG. 9 is a block diagram of a plasma processing apparatus according to a first conventional example.
FIG. 10 is a block diagram of a plasma processing apparatus according to a second conventional example.
[Explanation of symbols]
1 chamber
2 Anode electrode
3 Cathode electrode
4 High frequency power supply
5 Coupling capacitors
6 Bulk plasma region
7 sheath area
11 chambers
12 Anode electrode
13 Cathode electrode
14 Coupling capacitors
15 High frequency power supply
16 Bulk plasma region
17 sheath area
18 Emissive probe
19 Particle extraction device
20 Exhaust device
21 External electrode
22 High frequency power supply
31 Plasma Generation Chamber
32 chamber for discharging fine particles
33 Communication section
34 Anode electrode
35 Cathode electrode
36 Coupling capacitors
37 High frequency power supply
38 Bulk plasma region
39 sheath area
40 circular helical coil
41 linear coil
42. First DC voltage source
43 Second DC Voltage Source
44 Separatrix magnetic field lines
45 diverter plate
100 chambers
101 Exhaust device
110 chamber
111 Source gas supply means
112 Decomposition gas supply means

Claims (14)

By controlling the flow rate of the gas introduced into the chamber having the plasma generation region to a predetermined value or less and controlling the pressure of the gas introduced into the chamber within a predetermined range, the fine particles present in the plasma generation region are reduced. Fine particle moving step of moving to the boundary between the plasma generation region and the sheath region,
A fine particle discharging step of discharging fine particles moved to a boundary portion between the plasma generation region and the sheath region to the outside of the chamber,
The particulate discharging step detects the position of the boundary between the plasma generation region and the sheath region by an optical method, and removes the detected fine particles present at the boundary between the plasma generation region and the sheath region into the chamber. A plasma processing method, comprising the step of discharging to the outside of the device. The fine particle moving step includes a step of moving fine particles present in the plasma generation region to a boundary portion between the plasma generation region and the sheath region and to a peripheral portion of the plasma generation region,
The particulate emissions process according to claim 1, characterized in that it comprises a step of discharging the fine particles moved and the periphery of the plasma generating region at the boundary between the plasma generation region and the sheath region to the outside of the chamber 3. The plasma processing method according to 1. The fine particle moving step includes generating a magnetic field in a direction perpendicular to the surface of the sample placed in the chamber and generating a high-frequency electric field in a direction parallel to the surface of the sample, so that the particles are present in the plasma generation region. Causing the particles to be subjected to resonance cyclotron motion, thereby moving the particles present in the plasma generation region to the boundary between the plasma generation region and the sheath region and to the peripheral portion of the plasma generation region. The plasma processing method according to claim 2 , wherein: Forming magnetic lines of force extending between a plasma generation region of the plasma generation chamber and a particle discharge region provided to communicate with the plasma generation region, and moving the particles of the plasma generation region along the magnetic lines of force. By doing so, a fine particle moving step of guiding the fine particles in the plasma generation region to the fine particle discharge region,
A fine particle discharge step of discharging fine particles guided to the fine particle discharge region to the outside of the chamber,
The fine particle discharging step is a step of attaching fine particles guided to the fine particle discharging region to a diverter member provided in the fine particle discharging region, and taking out the diverter member with the fine particles attached to the outside of the fine particle discharging region. And a plasma processing method. Forming magnetic lines of force extending between a plasma generation region of the plasma generation chamber and a particle discharge region provided to communicate with the plasma generation region, and moving the particles of the plasma generation region along the magnetic lines of force. By doing so, a fine particle moving step of guiding the fine particles in the plasma generation region to the fine particle discharge region,
A fine particle discharge step of discharging fine particles guided to the fine particle discharge region to the outside of the chamber,
The plasma processing method according to claim 1, wherein the magnetic field lines are separatrix magnetic field lines. By controlling the flow rate of the gas introduced into the chamber to a predetermined value or less and controlling the pressure of the gas introduced into the chamber within a predetermined range, the fine particles present in the plasma generation region in the chamber are removed. Particle moving means for moving to the boundary between the plasma generation region and the sheath region,
Fine particle discharge means for discharging fine particles moved to the boundary between the plasma generation region and the sheath region to the outside of the chamber,
A plasma processing apparatus further comprising a boundary detection unit that detects a position of a boundary between the plasma generation region and the sheath region. 7. The plasma processing apparatus according to claim 6 , wherein said boundary detecting means is an emitting probe. 8. The plasma process according to claim 6 , wherein the fine particle discharging means is provided so as to move to a boundary between the plasma generation area and the sheath area detected by the boundary detection means. apparatus. The plasma processing apparatus according to any one of claims 6 to 8 , further comprising a fine particle peripheral portion moving means for moving fine particles present in the plasma generating region to a peripheral portion of the plasma generating region. . The fine particle peripheral portion moving means includes a magnetic field generating means for generating a magnetic field in a direction perpendicular to the surface of the sample disposed in the chamber, and a high frequency electric field generating means for generating a high frequency electric field in a direction parallel to the surface of the sample. It consists of a claim that by the resonance cyclotron motion to the microparticles present in the plasma generation region, and wherein the fine particles present in the plasma generation region is a means for moving the peripheral portion of the plasma generation region 9. The plasma processing apparatus according to 8 . The particle discharging means includes a cylindrical grid that applies a positive voltage to move the fine particles moved to the peripheral portion of the plasma generation region by Coulomb force, and the fine particles sucked into the grid by the depressurizing force into the chamber. The plasma processing apparatus according to any one of claims 6 to 10 , further comprising exhaust means for discharging the gas to the outside of the plasma processing apparatus. A plasma generation chamber having a plasma generation region,
A fine particle discharge chamber having a fine particle discharge region communicating with the plasma generation region,
Forming magnetic lines of force extending between the plasma generation region and the particle discharge region, and moving the particles of the plasma generation region along the line of magnetic force, thereby moving the particles of the plasma generation region to the particle discharge region. Means for moving fine particles leading to
A fine particle discharge means for discharging fine particles guided to the fine particle discharge region to the outside of the chamber,
The fine particle moving means comprises a helical coil provided so as to surround the plasma generation chamber and the fine particle discharge chamber, and a linear coil provided so as to extend a central portion of the fine particle discharge chamber. Characteristic plasma processing equipment. A plasma generation chamber having a plasma generation region,
A fine particle discharge chamber having a fine particle discharge region communicating with the plasma generation region,
Forming magnetic lines of force extending between the plasma generation region and the particle discharge region, and moving the particles of the plasma generation region along the line of magnetic force, thereby moving the particles of the plasma generation region to the particle discharge region. Means for moving fine particles leading to
A fine particle discharge means for discharging fine particles guided to the fine particle discharge region to the outside of the chamber,
The plasma processing apparatus according to claim 1, wherein the fine particle discharging means includes a diverter member provided on the magnetic line of force in the fine particle discharging region and to which fine particles moving along the magnetic line of force adhere. A plasma generation chamber having a plasma generation region,
A fine particle discharge chamber having a fine particle discharge region communicating with the plasma generation region,
Forming magnetic lines of force extending between the plasma generation region and the particle discharge region, and moving the particles of the plasma generation region along the line of magnetic force, thereby moving the particles of the plasma generation region to the particle discharge region. Means for moving fine particles leading to
A fine particle discharge means for discharging fine particles guided to the fine particle discharge region to the outside of the chamber,
The said magnetic field line is a separatrix magnetic field line, The plasma process apparatus characterized by the above-mentioned.

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