JP5584412B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus for exciting a plasma of a processing gas to perform a predetermined process on a substrate to be processed.

  This type of plasma processing apparatus is used for various process processes such as etching, ashing, and plasma deposition on a target substrate such as a semiconductor wafer or an FPD (flat panel display) substrate. As such a plasma processing apparatus, for example, a flat spiral coil is provided on the top of a dielectric, both ends of the spiral coil are grounded, and a high frequency power source is connected between the one end and the ground. (See, for example, Patent Document 1). According to this, a high frequency is supplied from a high frequency power source to the spiral coil, and a standing wave is induced by resonating at a high frequency of, for example, ½ wavelength (or ¼ wavelength), and is induced at the lower part of the dielectric. An electric field is generated to excite the plasma of the processing gas.

Japanese Patent Laid-Open No. 7-269992 JP 2007-142444 A

  Incidentally, in recent years, with the demand for further miniaturization and multilayering of semiconductor elements, it is required to perform processing with less damage even in such process processing. For example, when a process is performed with radicals, it is required to promote the reaction by the radicals and reduce ion damage as much as possible. That is, excessive ions cause damages such as mixing of materials between layers, destruction of oxides, invasion of contaminants, and changes in characteristics, and various measures have been taken to avoid this. Moreover, it is preferable to avoid ion bombardment that causes low selectivity in an etching process that prescribes the selectivity with high accuracy. It is known that such ion damage can be effectively suppressed, for example, by exciting plasma with a potential as low as possible.

  However, when both ends of the spiral coil are grounded as in the plasma processing apparatus described above, even if the standing wave is induced by resonating at a high-frequency half-wave (or quarter-wave), Since the voltage component on the spiral coil is always positive or negative, and both the positive and negative voltage components do not exist at the same time, the voltage component always remains on the spiral coil. For this reason, since many capacitive coupling components are generated in the plasma, the occurrence of ion damage is inevitable.

  Further, in order to reduce the capacitive coupling component in the plasma, the voltage component remaining in the spiral coil may be reduced. Therefore, as described in Patent Document 1, a low-inductance spiral coil is used. Thus, it is possible to reduce the capacitive coupling component in the plasma. However, when a spiral coil having a low inductance is used, the magnetic field excited is weakened. As a result, strong inductively coupled plasma is hardly generated, and the plasma density is also lowered.

  In Patent Document 2, a spiral coil wound outside the vertically long reaction vessel that can be depressurized is provided, and a high-frequency wave of a predetermined wavelength is supplied to the spiral coil so that, for example, a full-wavelength mode, a half-wavelength mode, etc. By resonating with, a standing wave is induced and an induced electric field is generated in the reaction vessel to excite the plasma of the processing gas. According to this, by adjusting the voltage waveform so that the phase voltage and the reverse phase voltage are symmetrical with respect to the point where the phase voltage is switched by the wavelength adjusting circuit, the potential at which the phase voltage is switched is zero at the node. Inductively coupled plasma can be excited.

  However, because this is an antenna element of a spiral coil wound in the vertical direction, the waveform is adjusted by the wavelength adjustment circuit so that the phase voltage and the antiphase voltage are symmetrical with respect to the point where the phase voltage is switched. It can be done. On the other hand, in the case of a planar coil antenna element, the diameter gradually increases from the inner end toward the outer end on the same plane, unlike the case of a spiral coil wound in the vertical direction. Become. For this reason, the reactance is different between the inner line and the outer line of the point where the phase voltage and the antiphase voltage are switched, and the waveform cannot be adjusted to be symmetric with respect to the point. For this reason, the technique in the case of the helical coil of Patent Document 2 cannot be applied to the case of the planar coil as it is.

  Therefore, the present invention has been made in view of such problems, and an object of the present invention is to provide a plasma processing apparatus that can easily form a more stable and high-density plasma with a low plasma potential. is there.

  In order to solve the above problems, according to one aspect of the present invention, there is provided a plasma processing apparatus for performing a predetermined plasma process on a substrate to be processed by generating inductively coupled plasma of a processing gas in a decompressed processing chamber. , A mounting table provided in the processing chamber for mounting the substrate to be processed, a gas supply unit for introducing the processing gas into the processing chamber, an exhaust unit for exhausting and depressurizing the processing chamber, A planar high-frequency antenna disposed via a plate-shaped dielectric so as to face the mounting table, a shield member provided so as to cover the high-frequency antenna, and the plate-shaped dielectric and the mounting table described above And a high frequency power source for applying a high frequency for generating the inductively coupled plasma to the high frequency antenna. The high frequency antenna is open at both ends and grounded at or near its midpoint. Plasma processing apparatus characterized by comprising the configured antenna element to resonate at a half wavelength of the high frequency from the wave source is provided.

  According to the present invention, the antenna element is configured such that both ends thereof are open and the midpoint or the vicinity thereof is grounded and resonated at a half wavelength of the high frequency from the high frequency power source. Although the magnitudes of the voltage components are slightly different, since positive and negative always exist at the same time, they cancel each other out, and the voltage component as a whole becomes smaller. As a result, the capacitive coupling component in the plasma can be reduced, so that ion damage caused by the plasma can be reduced.

  Further, it is preferable that the distance between the antenna element and the shield member can be adjusted. According to this, since the stray capacitance between them can be changed by adjusting the distance between the antenna element and the shield member, the resonance frequency of the antenna element can be adjusted without changing the physical length of the antenna element. Can be adjusted. In addition, since the electrical length of the antenna element can be adjusted by adjusting the stray capacitance between the antenna element and the shield member, the degree of freedom of the size and shape of the antenna element can be greatly increased.

  Further, it is preferable that the distance between the antenna element and the plate-like dielectric can be adjusted. According to this, since the distance between the antenna element and the plasma can be changed, the capacitive coupling between the antenna element and the plasma can be changed, and the plasma potential can be adjusted.

  In this case, a shield height adjusting mechanism that adjusts the distance between the antenna element and the shield member by adjusting the height of the shield member, and the antenna element and the antenna by adjusting the height of the high-frequency antenna. You may make it provide the antenna height adjustment mechanism which adjusts the distance with a shield member. According to this, the resonance frequency of the antenna element can be adjusted by a simple operation of adjusting the height of the shield member by the shield height adjusting mechanism. In addition, the plasma potential can be adjusted by a simple operation of adjusting the height of the high-frequency antenna by the antenna height adjustment mechanism.

  In addition, a high frequency power meter is provided on the output side of the high frequency power source, and the height of the shield member is adjusted by controlling the actuator according to the high frequency power detected by the high frequency power meter so that the resonance frequency of the antenna element is optimal. You may make it adjust automatically so that it may become. According to this, the resonance frequency of the antenna element can be optimally adjusted more easily.

  The antenna element preferably has a spiral coil shape. In the case of a planar and spiral coil antenna element, the diameter gradually increases from the inner end to the outer end on the same plane, unlike the case of a spiral coil wound in the vertical direction. Become bigger. For this reason, if the ground point is the midpoint of the antenna element or its vicinity, the reactance differs between the line from the inner end to the ground point and the line from the ground point to the outer end. The line on the inside and the line on the outside from the ground point of the antenna element are not strictly symmetrical, and the waveforms of both are slightly different. For this reason, a small voltage component remains in the antenna element. Even in such a case, according to the present invention, for example, the plasma potential can be reduced by adjusting the height of the high-frequency antenna so that the distance between the antenna element and the plasma becomes long. According to this, plasma can be generated so as not to be affected by a slight voltage component remaining in the antenna element.

  According to the present invention, the antenna element is configured such that both ends thereof are opened and the middle point or the vicinity thereof is grounded to resonate at a half wavelength of the high frequency from the high frequency power source, thereby reducing the plasma potential and stabilizing the antenna element. It is possible to provide a plasma processing apparatus that can easily form a high density plasma.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Configuration example of plasma processing equipment)
First, a configuration example of a plasma processing apparatus 100 according to an embodiment of the present invention will be described with reference to the drawings. Here, a predetermined plasma process is performed on a substrate to be processed, for example, a semiconductor wafer (hereinafter, also simply referred to as “wafer”) W by plasma of a processing gas excited in a processing chamber by applying high-frequency power to a planar high-frequency antenna. An inductively coupled plasma processing apparatus is taken as an example. FIG. 1 is a cross-sectional view illustrating a schematic configuration of a plasma processing apparatus 100 according to the present embodiment, and FIG. 2 is a top view of a high-frequency antenna 140 provided in the plasma processing apparatus 100. The plasma processing apparatus 100 includes a processing chamber (chamber) 102 formed in a cylindrical shape (for example, a cylindrical shape) made of metal (for example, aluminum). Note that the shape of the processing chamber 102 is not limited to a cylindrical shape. For example, a rectangular tube shape (for example, a box shape) may be used.

  On the bottom of the processing chamber 102, a mounting table 110 for mounting the wafer W is provided. The mounting table 110 is formed into a substantially columnar shape (for example, a cylindrical shape) with aluminum or the like. In addition, the shape of the mounting table 110 is not limited to a cylindrical shape. For example, a prismatic shape (for example, a polygonal prism shape) may be used. Although not shown, the mounting table 110 can be provided with various functions as required, such as an electrostatic chuck for attracting and holding the wafer W by a Coulomb force, a temperature adjustment mechanism such as a heater and a refrigerant flow path, and the like.

  A plate-like dielectric 104 made of, for example, quartz glass or ceramic is provided on the ceiling of the processing chamber 102 so as to face the mounting table 110. Specifically, the plate-like dielectric 104 is formed in a disk shape, for example, and is airtightly attached so as to close an opening formed in the ceiling portion of the processing chamber 102.

  The processing chamber 102 is provided with a gas supply unit 120 that supplies a processing gas or the like for processing the wafer W. The gas supply unit 120 is configured as shown in FIG. That is, a gas inlet 121 is formed in the side wall of the processing chamber 102, and a gas supply source 122 is connected to the gas inlet 121 via a gas supply pipe 123. In the middle of the gas supply pipe 123, a flow rate controller for controlling the flow rate of the processing gas, for example, a mass flow controller 124 and an opening / closing valve 126 are interposed. According to such a gas supply unit 120, the processing gas from the gas supply source 122 is controlled to a predetermined flow rate by the mass flow controller (MFC) 124 and is supplied into the processing chamber 102 from the gas inlet 121.

  In FIG. 1, the gas supply unit 120 is represented by a single gas line for the sake of simplicity, but the gas supply unit 120 is not limited to supplying a processing gas of a single gas type. A plurality of gas species may be supplied as the processing gas. In this case, a plurality of gas supply sources may be provided to form a plurality of gas lines, and a mass flow controller may be provided in each gas line. In addition, although FIG. 1 illustrates an example in which the gas supply unit 120 is configured to supply gas from the side wall portion of the processing chamber 102, the present invention is not necessarily limited thereto. For example, the gas may be supplied from the ceiling of the processing chamber 102. In this case, for example, a gas inlet may be formed in the center of the plate-like dielectric 104, for example, and gas may be supplied therefrom.

As a processing gas supplied into the processing chamber 102 by such a gas supply unit 120, for example, in etching an oxide film, a halogen-based gas containing Cl or the like is used. Specifically, when etching a silicon oxide film such as a SiO ₂ film, CHF ₃ gas or the like is used as a processing gas. Further, when etching a high dielectric thin film such as HfO ₂ , HfSiO ₂ , ZrO ₂ , ZrSiO ₄ , BCl ₃ gas is used as a processing gas, or a mixed gas of BCl ₃ gas and O ₂ gas is used as a processing gas. Used.

  An exhaust unit 130 that exhausts the atmosphere in the processing chamber 102 is connected to the bottom of the processing chamber 102 via an exhaust pipe 132. The exhaust unit 130 is constituted by a vacuum pump, for example, and can reduce the pressure in the processing chamber 102 to a predetermined pressure. A wafer loading / unloading port 134 is formed in the side wall of the processing chamber 102, and a gate valve 136 is provided at the wafer loading / unloading port 134. For example, when the wafer W is loaded, the gate valve 136 is opened, the wafer W is placed on the mounting table 110 in the processing chamber 102 by a transfer mechanism such as a transfer arm (not shown), and the gate valve 136 is closed. Perform the process.

  A planar high frequency antenna 140 is disposed on the outer surface (upper side surface) of the plate-like dielectric 104 at the ceiling of the processing chamber 102, and is substantially cylindrical (for example, cylindrical) so as to cover the high frequency antenna 140. The shield member 160 is provided. The shape of the shield member 160 is not limited to a cylindrical shape. The shape of the shield member 160 may be another shape such as a rectangular tube, but is preferably matched to the shape of the processing chamber 102. Here, for example, since the processing chamber 102 has a substantially cylindrical shape, the shield member 160 is also formed in a substantially cylindrical shape accordingly. In addition, if the processing chamber 102 has a substantially rectangular tube shape, it is preferable that the shield member 160 also has a substantially rectangular tube shape.

  The high-frequency antenna 140 is formed by sandwiching a spiral coil-shaped antenna element 142 made of a conductor such as copper, aluminum, or stainless steel, by a plurality of sandwiching bodies 144. The sandwiching body 144 is formed in a rod shape as shown in FIG. 2, for example, and the three sandwiching bodies 144 are arranged radially from the vicinity of the center of the antenna element 142 to the outside thereof.

  A high frequency power supply 150 is connected to the antenna element 142. An induction magnetic field is formed in the processing chamber 102 by supplying a high frequency of a predetermined frequency (for example, 27.12 MHz) from the high frequency power supply 150 to the antenna element 142 with a predetermined power. As a result, the gas introduced into the processing chamber 102 is excited to generate plasma, and predetermined plasma processing is performed on the wafer, such as ashing processing, etching processing, and film formation processing. The high frequency output from the high frequency power supply 150 is not limited to 27.12 MHz. For example, it may be 13.56 MHz or 60 MHz. However, the electrical length of the antenna element 142 needs to be adjusted according to the high frequency output from the high frequency power supply 150.

  Details of a specific configuration of the antenna element 142 will be described later. Further, the height of the shield member 160 can be adjusted by an actuator 168. The height of the high frequency antenna 140 can also be adjusted by the actuator 148. These details will also be described later.

  A control unit (overall control device) 200 is connected to the plasma processing apparatus 100, and each unit of the plasma processing apparatus 100 is controlled by the control unit 200. In addition, the control unit 200 includes an operation unit 210 including a keyboard for an operator to input a command for managing the plasma processing apparatus 100, a display for visualizing and displaying the operating status of the plasma processing apparatus 100, and the like. It is connected.

  Furthermore, the control unit 200 stores a program for realizing various processes executed by the plasma processing apparatus 100 under the control of the control unit 200, recipe data necessary for executing the program, and the like. Is connected.

  The storage unit 220 stores, for example, a plurality of process processing recipes for executing wafer process processing, as well as recipes for performing necessary processing such as cleaning processing in the processing chamber. These recipes are a collection of a plurality of parameter values such as control parameters and setting parameters for controlling each part of the plasma processing apparatus 100. For example, the process processing recipe has parameter values such as a processing gas flow rate ratio, a processing chamber pressure, and high-frequency power.

  These recipes may be stored in a hard disk or a semiconductor memory, and set in a predetermined position of the storage unit 220 while being stored in a portable computer-readable storage medium such as a CD-ROM or DVD. You may come to do.

  The control unit 200 executes a desired process in the plasma processing apparatus 100 by reading out a desired process processing recipe from the storage unit 220 based on an instruction from the operation unit 210 and controlling each unit. Further, the recipe can be edited by an operation from the operation unit 210.

(Configuration example of high-frequency antenna)
Here, a specific configuration example of the high-frequency antenna 140 according to the present embodiment will be described with reference to the drawings. For example, as shown in FIG. 2, the high-frequency antenna 140 has both ends of the antenna element 142 as free ends 142a and 142b, and a midpoint in the winding direction or its vicinity (hereinafter simply referred to as “midpoint”). A ½ wavelength standing wave as a ground point (ground) can be formed.

  That is, the antenna element 142 has a length so as to resonate at a half wavelength of the reference frequency (resonance in a half wavelength mode) with a predetermined frequency (for example, 27.12 MHz) supplied from the high frequency power supply 150 as a reference. , Winding diameter, winding pitch, and number of turns are set. For example, the electrical length of the antenna element 142 is a length that resonates by ½ times the reference frequency, that is, a length that is ½ times one wavelength at the reference frequency of 27.12 MHz.

  The antenna element 142 may be configured in any shape such as a pipe shape, a wire shape, or a plate shape. When the winding pitch of the antenna element 142 is the same, it is advantageous in that the withstand voltage can be increased by increasing the distance between the conductors. Therefore, from the viewpoint of withstand voltage, the shape of the antenna element 142 is advantageous in that the distance between the conductors can be increased by using a plate having a small thickness rather than a pipe having a large thickness. Even when it is desired to make the winding pitch of the antenna element 142 narrower, it is more advantageous to use a plate shape from the viewpoint of withstand voltage.

  In this case, the feeding point for supplying the high frequency from the high frequency power supply 150 may be inside or outside the grounding point, and is preferably a point where the impedance is, for example, 50Ω. The feeding point may be variable. In this case, the feeding point may be automatically changed by a motor or the like.

  According to such an antenna element 142, when a high frequency of a reference frequency (for example, 27.12 MHz) is applied from the high frequency power supply 150 to the high frequency antenna 140 and resonated in the half wavelength mode, the antenna is shown at a certain moment as shown in FIG. The voltage V applied to the element 142 has a waveform such that the middle point (grounding point) is zero, one end has a positive peak, and the other end has a negative peak. On the other hand, the current I applied to the antenna element 142 is 90 ° out of phase with the voltage waveform, and therefore has a waveform in which the middle point (ground point) is maximum and both ends are zero.

  At this time, since the instantaneous capacitances increase and decrease in opposite directions for each positive and negative cycle of the high frequency, the waveforms of the voltage V and the current I applied to the antenna element 142 are as shown in FIG. That is, the voltage V is canceled by the positive and negative voltage components generated on the antenna element 142, and a standing wave of a half wavelength mode is formed so that the average voltage becomes very small. On the other hand, the current I has the strongest midpoint (grounding point) on the antenna element 142, and a standing wave is formed by a current component of only positive or negative.

  Such a standing wave generates a vertical magnetic field B having the maximum intensity in the vicinity of the center of the antenna element 142 as shown in FIG. 5, so that the vertical magnetic field B shown in FIG. A circular electric field E is excited and a donut-shaped plasma P is generated. In addition, since the average voltage applied to the antenna element 142 is very small, the capacitive coupling degree is extremely weak, so that plasma with a low potential can be generated.

  By the way, if both the inner end 142a and the outer end 142b of the antenna element 142 are grounded as shown in FIG. 6 and the high frequency power supply 150 is connected between the outer end 142b and the ground, FIG. The waveforms of the voltage V and current I shown are reversed. That is, when a high frequency of a reference frequency (for example, 27.12 MHz) is applied from the high frequency power supply 150 to the high frequency antenna 140 to resonate in the half wavelength mode, the voltage V applied to the antenna element 142 at a certain moment is shown in FIG. The waveform is such that the midpoint (grounding point) is maximum and both ends are zero. On the other hand, since the current I applied to the antenna element 142 is 90 degrees out of phase with the voltage waveform, the midpoint (grounding point) is zero, one end has a positive peak, and the other end Becomes a negative peak.

  As described above, when both ends of the antenna element 142 are grounded (FIG. 6) and the center point of the antenna element 142 is resonated in the same half-wavelength mode as that of FIG. The magnetic field in the opposite direction is always formed between the inner side and the outer side of the antenna element 142. For example, two circular electric fields as shown in FIG. 5 are formed in the processing chamber 102 in the vicinity of substantially the same plane by the opposite magnetic fields. Moreover, since the rotation directions of the two circular electric fields are always in conflict, they may interfere with each other and the generated plasma may become unstable.

  On the other hand, in the case of FIG. 3 in which the midpoint of the antenna element 142 is the grounding point, as described above, the circular electric field excited in the processing chamber 102 is one and always in one direction. There is no electric field in the opposite direction. For this reason, when the midpoint of the antenna element 142 is a grounding point, more stable plasma can be formed than when the end of the antenna element 142 is a grounding point.

  Further, when both ends of the antenna element 142 are grounded (FIG. 6), a voltage component remains on the antenna element 142 in the resonance state, so that many capacitive coupling components are generated in the plasma. In this case, in the case of FIG. 3 where the midpoint of the antenna element 142 is the ground point, as described above, the voltage component on the antenna element 142 in the resonance state is very small, and thus a capacitive coupling component is generated in the plasma. It is hard to do. Therefore, in order to perform plasma processing with less damage, it is more advantageous to use the midpoint of the antenna element 142 as a ground point (FIG. 3).

  In order to reduce the capacitive coupling component in the plasma, the voltage component remaining in the antenna element 142 may be reduced. Therefore, when both ends of the antenna element 142 are grounded (FIG. 6), it is possible to reduce the capacitive coupling component in the plasma by using the antenna element 142 having a low inductance. However, when the low-inductance antenna element 142 is used, the excited magnetic field becomes weak, and as a result, strong inductively coupled plasma is hardly generated. On the other hand, when the midpoint of the antenna element 142 is used as the ground point (FIG. 3), it is not necessary to consider reducing the capacitive coupling component in the plasma. it can. As the antenna element 142 having a higher inductance is used, a higher magnetic field can be formed, so that a stronger inductively coupled plasma can be formed. Therefore, in order to form a higher density plasma, it is more advantageous to use the midpoint of the antenna element 142 as the ground point (FIG. 3).

  As described above, in the high-frequency antenna 140 according to the present embodiment, the both ends of the antenna element 142 are the free ends 142a and 142b, and the midpoint of the length in the winding direction is the grounding point (ground). It is possible to easily form a more stable and high-density plasma with a very simple configuration of resonating at a low plasma potential.

  By the way, in order to resonate the antenna element 142 in the ½ wavelength mode in the present embodiment, the electrical length of the antenna element 142 is accurately set to ½ of the reference frequency (here, 27.12 MHz) as described above. It is necessary to adjust to double the length. That is, it is necessary to accurately match the resonance frequency of the antenna element 142.

  However, it is not easy to accurately manufacture the physical length of the antenna element 142. Further, the resonance frequency of the antenna element 142 affects not only the inherent reactance of the antenna element 142 but also the stray capacitance (stray capacitance) between the antenna element 142 and the shield member 160 as shown in FIG. For this reason, even if the physical length of the antenna element 142 can be accurately manufactured, an error may occur in the distance between the antenna element 142 and the shield member 160 due to an attachment error or the like, and the designed resonance frequency may not be obtained. is there.

  In this regard, when the end of the antenna element 142 described above is used as a ground point (FIG. 6), for example, a variable capacitor can be attached to the ground point, thereby adjusting the electrical length of the antenna element 142. It is. However, when the midpoint of the antenna element 142 is used as a ground point (FIG. 3), there is no merit in that even if a variable capacitor is connected between the midpoint of the antenna element 142 and the ground, the loss due to the capacitor increases. If a variable capacitor is inserted, if the C value is reduced, there is a high possibility that the matching condition with the high-frequency power supply 150 will not be met. Conversely, if the C value is increased, a large current flows through the variable capacitor and the resistance itself is insufficient. Is likely to break.

  Therefore, in the present embodiment, the height of the shield member 160 can be adjusted, and by adjusting the distance between the antenna element 142 and the shield member 160 and changing the stray capacitance, the resonance frequency of the antenna element 142 can be changed. Can be adjusted. Furthermore, in this embodiment, the height of the high-frequency antenna 140 can also be adjusted, and thereby the plasma potential can be adjusted by adjusting the distance between the plasma and the antenna element 142.

  Hereinafter, the height adjusting mechanism of the shield member 160 and the high-frequency antenna 140 will be described in detail with reference to the drawings. FIG. 7 is an enlarged view of the configuration in the vicinity of the high-frequency antenna 140 shown in FIG. FIG. 8A and FIG. 8B are diagrams for explaining the action when the height of the shield member 160 is adjusted. 8A shows a case where the height of the shield member 160 is lowered, and FIG. 8B shows a case where the height of the shield member 160 is made high. FIG. 9A and FIG. 9B are diagrams for explaining the action when the height of the high-frequency antenna 140 is adjusted. FIG. 9A shows a case where the height of the high-frequency antenna 140 is reduced, and FIG. 9B shows a case where the height of the high-frequency antenna 140 is increased.

  First, a specific configuration example of the height adjustment mechanism of the shield member 160 will be described. As shown in FIG. 7, the shield member 160 includes a substantially cylindrical lower shield member 162 fixed to the ceiling of the process chamber 102 (here, a substantially cylindrical shape according to the shape of the process chamber 102), and the lower shield member. The upper shield member 164 is slidably provided on the outer side of 162. The upper shield member 164 is formed in a substantially cylindrical shape with the upper surface closed and the lower surface opened.

  The upper shield member 164 is slid up and down by an actuator 168 provided on the side wall of the processing chamber 102. Specifically, for example, each of the plurality of actuators 168 is configured by a motor that can drive the drive rod 169 up and down, and the tip of each drive rod 169 is attached to an overhanging portion 166 that protrudes outside the upper shield member 164. May be.

  According to this, by driving the upper shield member 164 up and down by the drive rod 169 of each actuator 168, the distance between the shield member 160 and the high frequency antenna 140 (distance between the upper surface of the upper shield member 164 and the antenna element 142). D can be adjusted.

  Specifically, by driving the actuator 168 to raise the upper shield member 164 from the position shown in FIG. 8A to the position shown in FIG. 8B, the distance D between the shield member 160 and the high-frequency antenna 140 becomes longer. Thereby, since the stray capacitance C becomes small, the resonance frequency can be adjusted so that the electrical length of the antenna element 142 becomes long.

  Conversely, if the upper shield member 164 is lowered, the distance D between the shield member 160 and the high-frequency antenna 140 can be shortened. Thereby, since the stray capacitance C is increased, the resonance frequency can be adjusted so that the electrical length of the antenna element 142 is shortened. Note that the height adjustment mechanism of the shield member 160 is not limited to the above. For example, the number of actuators 168 may be one.

  As described above, according to the present embodiment, the stray capacitance C between the antenna element 142 and the shield member 160 can be changed by adjusting the height of the shield member 160. Therefore, the physical length of the antenna element 142 can be changed. The resonance frequency of the antenna element 142 can be adjusted without changing the height.

  In addition, the resonance frequency can be easily adjusted by a simple operation of simply adjusting the height of the shield member 160, and resonance can be achieved at a desired frequency. For example, when an antenna element 142 constituted by a spiral coiled copper pipe having a maximum outer diameter of 320 mm and a winding pitch of 20 mm was resonated at a half wavelength of 27.12 MHz, a shield member 160 of about 10 mm to 100 mm was obtained. The resonance frequency could be adjusted within the range of ± 5% to ± 10% simply by adjusting the height of.

  Further, since the electrical length of the antenna element 142 can be adjusted by adjusting the stray capacitance C between the antenna element 142 and the shield member 160, the degree of freedom of the size and shape of the antenna element 142 is greatly expanded. Can be made. That is, in the plasma processing apparatus 100 according to the present embodiment, antenna elements having various sizes and shapes can be used. For example, in addition to the rectangular antenna element 142 as shown in FIG. 10, an elliptical or other antenna element can be used.

  Furthermore, since the degree of freedom of the size and shape of the antenna element 142 has been expanded, it is possible to design the antenna element 142 corresponding to the required plasma size. For example, the size and shape of the antenna element 142 can be designed freely according to the diameter of the wafer W. In addition, by optimizing the winding pitch and resonance frequency, the degree of freedom in plasma size can be greatly increased.

  Since the height of the shield member 160 can be adjusted, when the height of the shield member 160 is too low and the distance between the antenna element 142 is too short, the shield member 160 and the antenna element 142 An abnormal discharge can be prevented by inserting a dielectric between them.

  Next, a specific configuration example of the height adjustment mechanism of the high-frequency antenna 140 will be described. As shown in FIG. 7, the high-frequency antenna 140 is slid up and down by an actuator 148 provided on the side wall of the processing chamber 102. Specifically, for example, the plurality of actuators 148 may be configured by motors that can drive the drive rod 149 up and down, and the tip of each drive rod 149 may be attached to the support member 146 of the high-frequency antenna 140. The actuator 168 is not necessarily provided, and the upper shield member 164 itself may be manually driven up and down.

  In this case, the support member 146 is provided on the holding body 144 of the high-frequency antenna 140 so as to protrude outwardly, and the tip of each support member 146 extends outwardly from a vertically extending slit-like hole formed in the shield member 160. The tip of the drive rod 149 is attached to that part.

  According to this, by driving the high-frequency antenna 140 up and down by the drive rod 149 of each actuator 148, the distance d1 between the high-frequency antenna 140 and the plate-like dielectric 104, and hence the distance d2 between the antenna element 142 and the plasma P is obtained. Can be adjusted.

  Specifically, by driving the actuator 148 to raise the high frequency antenna 140 from the position shown in FIG. 9A to the position shown in FIG. 9B, the distance d2 between the antenna element 142 and the plasma P becomes longer. As a result, the capacitive coupling between the plasma P generated in the processing chamber 102 and the voltage component on the antenna element 142 can be weakened, so that the potential of the plasma P can be reduced.

  Conversely, if the high-frequency antenna 140 is lowered, the distance d2 between the antenna element 142 and the plasma P can be shortened. As a result, the degree of capacitive coupling between the plasma P generated in the processing chamber 102 and the voltage component on the antenna element 142 can be increased, so that the potential of the plasma P can be increased. Note that the height adjustment mechanism of the high-frequency antenna 140 is not limited to the above. For example, the number of actuators 148 may be one. The actuator 148 is not necessarily provided, and the high frequency antenna 140 itself may be manually driven up and down by the support member 146.

  Thus, according to the present embodiment, the distance d2 between the antenna element 142 and the plasma P can be changed by adjusting the height of the high-frequency antenna 140, so that the plasma potential can be adjusted. Moreover, the plasma potential can be easily adjusted by a simple operation of simply adjusting the height of the high-frequency antenna 140. Therefore, for example, in the case of plasma processing that requires high-potential plasma, the height of the high-frequency antenna 140 may be reduced to shorten the distance d2 between the antenna element 142 and the plasma P.

  In addition, since the antenna element 142 in the present embodiment is a planar spiral coil shape, the diameter gradually increases from the inner end 142a to the outer end 142b on the same plane. Therefore, if the midpoint of the antenna element 142 is a ground point, the reactance is different between the line from the inner end 142a to the ground point and the line from the ground point to the outer end 142b. The waveform of V is not strictly symmetrical between the inner line and the outer line from the midpoint of the antenna element 142, and the waveforms of both are slightly different. For this reason, a small voltage component remains in the antenna element 142.

  Even in such a case, according to the present embodiment, the height of the high-frequency antenna 140 is adjusted so that the distance between the antenna element 142 and the plasma P is increased, thereby reducing the plasma potential to a level that can be ignored in practice. be able to. Therefore, plasma can be generated so as not to be affected by a slight voltage component remaining in the antenna element 142.

  The height adjustment of the high-frequency antenna 140 and the shield member 160 described above is performed by controlling the actuators 148 and 168 by the control unit 200, respectively. In this case, the height adjustment of the high-frequency antenna 140 and the shield member 160 may be performed by an operator's operation by the operation unit 210 or may be performed by automatic control of the control unit 200.

  Specifically, when the height of the shield member 160 is automatically adjusted, a high frequency power meter (for example, a reflected wave power meter) 152 is provided on the output side of the high frequency power supply 150 as shown in FIG. The resonance frequency of the antenna element 142 is automatically adjusted by controlling the actuator 168 to adjust the height of the shield member 160 in accordance with the high frequency power detected by the meter 152 (for example, the reflected wave power is minimized). You may make it adjust. According to this, it is possible to automatically adjust the resonance frequency of the antenna element 142 to an optimum resonance condition in accordance with a desired output frequency from the high frequency power supply 150.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  The present invention is applicable to a plasma processing apparatus that excites plasma of a processing gas to perform a predetermined process on a substrate to be processed.

It is a longitudinal cross-sectional view which shows schematic structure of the plasma processing apparatus concerning embodiment of this invention. It is a top view which shows the structural example of the high frequency antenna shown in FIG. It is the figure which represented typically the electric current and voltage applied at a certain moment when the antenna element which made the midpoint the grounding point was resonated. It is a figure showing the electric current and voltage which are actually applied to the antenna element shown in FIG. It is a perspective view for demonstrating the effect | action of the antenna element concerning this embodiment. It is the figure which represented typically the electric current and voltage applied at a certain moment when the antenna element which made the edge part the grounding point was resonated. It is a fragmentary sectional view for demonstrating the height adjustment mechanism of a shield member and a high frequency antenna. It is operation | movement explanatory drawing of the height adjustment mechanism of a shield member. It is operation | movement explanatory drawing of the height adjustment mechanism of a shield member. It is operation | movement explanatory drawing of the height adjustment mechanism of a high frequency antenna. It is operation | movement explanatory drawing of the height adjustment mechanism of a high frequency antenna. It is a top view which shows the other structural example of an antenna element. It is a fragmentary sectional view which shows the modification of the plasma processing apparatus concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Plasma processing apparatus 102 Processing chamber 104 Plate-shaped dielectric 110 Mounting stand 120 Gas supply part 121 Gas introduction port 122 Gas supply source 123 Gas supply pipe 124 Mass flow controller 126 Open / close valve 130 Exhaust part 132 Exhaust pipe 134 Wafer carry-in / out port 136 Gate valve 140 High-frequency antenna 142 Antenna element 142a Inner end 142b Outer end 144
Holding member 146 Support member 148 Actuator 149 Drive rod 150 High frequency power supply 152 RF power meter 160 Shield member 162 Lower shield member 164 Upper shield member 166 Overhang portion 168 Actuator 169 Drive rod 200 Control portion 210 Operation portion 220 Storage portion W Wafer

Claims (5)

A plasma processing apparatus for performing predetermined plasma processing on a substrate to be processed by generating inductively coupled plasma of a processing gas in a decompressed processing chamber,
A mounting table provided in the processing chamber for mounting the substrate to be processed;
A gas supply unit for introducing the processing gas into the processing chamber;
An exhaust section for exhausting and depressurizing the processing chamber;
A plate-like dielectric disposed opposite the mounting table;
A high-frequency antenna disposed above the plate-like dielectric;
A shield member provided to cover the high-frequency antenna from above;
A high frequency power source for applying a high frequency for generating the inductively coupled plasma between the plate dielectric and the mounting table to the high frequency antenna;
The high-frequency antenna is in the form of a planar spiral coil wound around the central axis of the plate-like dielectric so that the diameter gradually increases from the inner end toward the outer end. And an antenna element having a ground point at the midpoint of the winding direction as a grounding point. The antenna element is adjusted by adjusting a distance between the antenna element and the shield member. By adjusting the stray capacitance, the electrical length of the part wound inside and the part wound outside from the grounding point becomes the same, and the resonance occurs at the half wavelength of the high frequency from the high frequency power source. configuration plasma processing apparatus characterized the kite to. The shield height adjusting mechanism for adjusting the height of the shield member with respect to the antenna element is provided, and the distance between the antenna element and the shield member can be adjusted by the shield height adjusting mechanism. 2. The plasma processing apparatus according to 1. An antenna height adjustment mechanism for adjusting the height of the high-frequency antenna with respect to the plate dielectric is provided, and the distance between the antenna element and the plate dielectric can be adjusted by the antenna height adjustment mechanism. The plasma processing apparatus according to claim 2. The position at which the impedance is 50 ohms at a portion inside or outside the ground point of the high-frequency antenna is set as a feeding point for applying a high frequency from the high-frequency power source. The plasma processing apparatus as described. A high-frequency power meter provided on the output side of the high-frequency power source;
A control unit that automatically adjusts the height of the shield member to optimize the resonance frequency of the antenna element by controlling the shield height adjustment mechanism according to the high frequency power detected by the high frequency power meter. When,
The plasma processing apparatus according to claim 2, further comprising:

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