JP2017120721A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly start plasma discharge, and to retain stable plasma.SOLUTION: An etching device 100 comprises: a chamber 1 into which an etching gas is introduced, and a work W is loaded; a window part 5 formed on the chamber 1, and including a dielectric or semiconductor; an antenna part 6 having a plurality of partial antennas 61a, 61b and 61c disposed on the window part 5 outside the chamber 1 and capacitors 62a and 62b disposed therebetween; a power source 8 for supplying an electric power to the antenna part 6; and a booster part 65 connected to an end of the antenna part 6 on the grounding side so that it can be separated therefrom, which boosts a voltage input to the antenna part 6 from the power source 8.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a plasma processing apparatus.

  In a manufacturing process of a product such as a semiconductor device, a liquid crystal display, or an optical disk, a plasma process such as etching may be performed on a workpiece such as a wafer or a glass substrate. The plasma processing apparatus generates plasma in a container into which a process gas has been introduced, and performs plasma processing on the workpiece carried into the container. As one of the methods for generating plasma, there is a method for performing plasma discharge by generating an induction electric field by flowing a high-frequency current through a loop antenna. Plasma generated by such a method is called inductively coupled plasma.

  When the power supplied to the antenna is increased in order to increase the plasma density, the voltage difference between the power supply side and the ground side of the antenna, that is, the voltage amplitude increases. A dielectric or semiconductor window is attached to the container. A coil antenna is attached to this window. When the voltage amplitude is increased, the plasma may collide with the window and damage the window.

  In order to reduce the voltage amplitude, there is a technique in which a loop antenna is constituted by a plurality of partial antennas, and a capacitor is disposed between the partial antennas. Since the impedance is lowered by the capacitor and the amplitude of the voltage is reduced, stable plasma can be maintained.

JP-A-10-70107 JP 2002-217175 A

  By introducing a capacitor, the voltage amplitude can be kept small. On the other hand, when starting the plasma discharge, it is desirable to increase the voltage rapidly and greatly. If the amplitude of the voltage is kept small, the voltage decreases as a whole, so that it may take time to start plasma discharge.

  In order to solve the above-described problems, the present invention provides a highly convenient plasma processing apparatus that can quickly start plasma discharge and maintain stable plasma during plasma processing. Objective.

  In order to achieve the above object, a plasma processing apparatus of the present invention is a plasma processing apparatus for processing a workpiece with plasma, wherein a process gas is introduced and a container into which the workpiece is carried is formed in the container. An antenna unit having a window portion made of a dielectric or a semiconductor, and a plurality of partial antennas and a capacitor provided between the partial antennas arranged outside the container of the window portion, and the antenna unit A power supply unit that supplies power to the antenna unit, and a step-up unit that is detachably connected to the ground-side end of the antenna unit and increases a voltage input from the power supply unit to the antenna unit.

  The boosting unit may include an inductor.

  The boosting unit may include a resistor.

  A first switch may be provided at the ground side end of the antenna unit, and the booster unit may be connected in parallel to the first switch via a second switch.

  A step-up unit that raises the input voltage is detachably connected to the ground side end of the antenna unit including the capacitor. As a result, when plasma processing is started, the voltage is increased to quickly discharge the plasma, and during plasma processing, the amplitude of the voltage can be kept low and stable plasma can be maintained. Can be provided.

It is a figure which shows typically the structure of the plasma processing apparatus which concerns on embodiment of this invention. It is a schematic diagram which shows the structure of an antenna part and a pressure | voltage rise part. (A) is a circuit diagram which shows the state which separated the pressure | voltage rise part from the antenna part, (b) is a graph which shows the voltage of the antenna part in the state of (a). (A) is a circuit diagram which shows the state which connected the pressure | voltage rise part to the antenna part, (b) is a graph which shows the voltage of the antenna part in the state of (a). It is a schematic diagram which shows the structure of the antenna part and the pressure | voltage rise part of the plasma processing apparatus which concerns on other embodiment of this invention.

[Constitution]
Embodiments of the present invention will be specifically described with reference to the drawings.

  The plasma processing apparatus is an apparatus that performs plasma processing on a workpiece that is an object using plasma generated in a container. The workpiece is, for example, a wafer or a glass substrate, but is not limited to a specific one. As the plasma processing, there are film formation processing such as sputtering and film processing such as etching. Although the plasma processing apparatus is not limited to a specific one, here, a configuration of an etching apparatus that performs etching will be described.

  As shown in FIG. 1, the etching apparatus 100 includes a chamber 1 made of metal such as aluminum or stainless steel as a container. The chamber 1 is connected to a ground (not shown).

  A gas introduction channel 11 is provided on the side wall near the top of the chamber 1. The gas introduction channel 11 is a channel for introducing an etching gas as a process gas into the chamber 1. The etching gas is supplied to the gas introduction channel 11 from a gas supply device (not shown). A voltage is applied to the etching gas to generate plasma, and ions and radicals are generated. Etching is performed by the ions and radicals acting on the workpiece W. As the etching gas, for example, an inert gas such as argon can be used.

  Light emission occurs by plasma discharge. The chamber 1 is provided with a light emission sensor (not shown), and the start of plasma discharge is determined by detecting light emission with the light emission sensor.

  An exhaust passage 12 and an exhaust device 13 such as a pump are provided at the bottom of the chamber 1, and the chamber 1 is kept in an exhaust state. A pressure gauge (not shown) is installed in the gas introduction channel 11 and the exhaust channel 12. By controlling the exhaust device 13 based on the pressure detected by the pressure gauge, the pressure of the etching gas introduced into the chamber 1 can be controlled within a desired range.

  An inlet 14 for the workpiece W is provided on the side wall of the chamber 1. The loading / unloading port 14 is provided with an opening / closing device (not shown), and the loading / unloading port 14 is opened when the workpiece W is loaded and unloaded.

  A columnar stage 2 on which the workpiece W is placed is provided at the bottom of the chamber 1. A lower electrode 21 and a holding device 22 are disposed on the upper surface of the stage 2. The holding device 22 holds the workpiece W on the upper surface of the stage 2 and can be, for example, an electrostatic chuck mechanism. The stage 2 incorporates a temperature adjustment device 23 that adjusts the temperature of the workpiece W placed thereon. The temperature adjusting device 23 can be a heating device, a cooling device, or both functions.

  The lower electrode 21 is connected to a matching circuit 3 and a power source 4 provided outside the chamber 1 by a cable. High frequency power of several hundred kHz to several MHz is supplied from the power source 4.

  A circular opening 15 is provided in the ceiling of the chamber 1. The opening 15 is closed by a window portion 5 attached from the outside of the chamber 1. The window 5 is a disc made of a dielectric such as quartz or alumina or a semiconductor made of silicon or the like.

  The antenna portion 6 is attached to the surface of the window portion 5 opposite to the surface attached to the opening 15. A matching circuit 7 and a power source 8 are connected to the antenna unit 6. The power supply 8 supplies high frequency power of several hundred kHz to several MHz to the antenna unit 6 as a power supply unit. The matching circuit 7 matches the impedance of the power supply 8 and the power supply 4 together with the matching circuit 3 connected to the lower electrode 21 described above.

  FIG. 2 shows a configuration of the antenna unit 6 as a circuit diagram. The antenna unit 6 is an annular loop antenna as a whole, and both ends are close to each other. One end of the antenna unit 6 is connected to the power source 8 via the matching circuit 7, but the matching circuit 7 is not shown in FIG. The other end of the antenna unit 6 is connected to the ground 63. Hereinafter, one end is referred to as a power supply side end, and the other end is referred to as a ground side end.

  The antenna unit 6 includes a plurality of partial antennas 61a, 61b, and 61c, and capacitors 62a and 62b disposed between them. In the present embodiment, there are three partial antennas 61a, 61b, 61c having the same size and shape. The partial antennas 61a, 61b, 61c are formed of arcuate metal thin plates. The antenna 62 is configured by disposing the capacitor 62a between the partial antennas 61a and 61b, disposing the capacitor 62b between the partial antennas 61b and 61c, and electrically connecting the whole.

  Connection terminals (not shown) are provided at both ends of each of the partial antennas 61a, 61b, 61c, and the capacitors 62a, 62b are attached to the connection terminals. A capacitor 62c is also attached to the end of the partial antenna 61c opposite to the connection end with the capacitor 62b. The capacitor 62 c is connected to the matching circuit 7 and the power supply 8. That is, the capacitors 62a, 62b, and 62c are disposed at positions of 120 °, 240 °, and 360 °, respectively, when the azimuth angle of the ground side end portion is 0 ° when viewed from the entire antenna unit 6. The voltage input to the antenna unit 6 drops by passing through the capacitors 62a, 62b, and 62c. By arranging the capacitors 62a, 62b, and 62c evenly on the antenna unit 6, the voltage amplitude of the antenna unit 6 as a whole is kept low.

  The number of partial antennas and the number and capacity of capacitors arranged between the partial antennas can be appropriately determined depending on how much the amplitude of the voltage is suppressed.

  In FIG. 2, a switch 64 is provided at the end of the partial antenna 61 a opposite to the connection end with the capacitor 62 a, that is, the ground end of the antenna unit 6. In other words, the antenna unit 6 is connected to the ground 63 via the switch 64. A booster 65 is connected to the switch 64 in parallel. The step-up unit 65 is detachably connected to the ground side end of the antenna unit 6, and increases the voltage input from the power supply 8 to the antenna unit 6. Here, the connection means an electrical connection, and the disconnection means the release of the electrical connection.

  Specifically, the step-up unit 65 includes an inductor 66 and is connected in parallel to the switch 64 via a pair of switches 67 and 67. As shown in FIG. 3A, by closing the switch 64 and opening the switches 67 and 67, the boosting unit 65 is disconnected from the ground side end of the antenna unit 6, and the antenna unit 6 is connected in series to the ground. . 4A, by opening the switch 64 and closing the switches 67 and 67, the ground side end of the antenna unit 6 is connected in series to the boosting unit 65. That is, the antenna unit 6 is connected to the ground via the booster unit 65.

  The etching apparatus 100 further includes a control unit 9. The control unit 9 includes an arithmetic processing device such as a PLC or a CPU. The control unit 9 controls the introduction and exhaust of the etching gas into the chamber 1, controls the heating or cooling of the temperature adjusting device 23, controls the timing of loading / unloading the work W, controls the outputs of the power supply 4 and the power supply 8, switches 64, switches Controls such as opening / closing control 67 and 67 are performed.

[Operation]
The operation of the etching process and the operation of the antenna unit 6 in the etching apparatus 100 of this embodiment will be described. As described above, the etching process is performed by controlling each mechanism of the etching apparatus 100 by the control unit 9.

  When performing the etching process, the loading port 14 is opened and the workpiece W is loaded into the chamber 1 and placed on the stage 2. The work W may be carried in by a transfer device (not shown) or manually. The mounted workpiece W is held by the holding device 22.

  The inlet 14 is closed and the chamber 1 is sealed. The work W is heated or cooled by the temperature adjusting device 23 as necessary. The temperature adjusting device 23 may be driven in advance before the work W is carried in so that heating or cooling can be started simultaneously with the work W being placed on the stage 2.

  An etching gas is introduced into the chamber 1 from the gas introduction channel 11. The exhaust device 13 is adjusted to control the pressure of the etching gas within a desired range.

  Power is supplied from the power source 4 and the power source 8 to the antenna unit 6 and the lower electrode 21. A high-frequency current flows through the antenna unit 6, and the etching gas is turned into plasma by a magnetic field generated by the high-frequency current. Furthermore, an electric field is induced by the time change of the magnetic field, and electrons are accelerated by the electric field to maintain the plasma. Ions or radicals generated in the plasma etching gas are guided to the stage 2 by the lower electrode 21, and the workpiece W held on the stage 2 is etched.

  When the supply of power to the antenna unit 6 is started, as shown in FIG. 4A, the switch 64 of the antenna unit 6 is set to “open”, and the switches 67 and 67 of the booster unit 65 are set to “closed”. The ground side end of the antenna unit 6 is connected to the ground via the boosting unit 65. This state continues until light emission by plasma discharge is detected by the light emission sensor. When light emission is detected by the light emission sensor, as shown in FIG. 3A, the switch 64 of the antenna unit 6 is set to “closed” and the switches 67 and 67 of the booster unit 65 are set to “open”. As a result, the step-up unit 65 is disconnected from the ground side end of the antenna unit 6, and the ground side end is directly connected to the ground. While the work W is being etched, this direct connection is maintained. In addition, in switching between “closed” of the switch 64 and “open” of the switches 67 and 67, there is a possibility that the discharge disappears due to the presence of time when both the switch 64 and the switches 67 and 67 are “open”. There is. Therefore, it is preferable to perform switching so that the switch 64 and the switches 67 and 67 are both “closed”, that is, a state where a current flows in both circuits, so that the discharge can be maintained. Here, for example, in a short time of less than 10 microseconds, it is possible to maintain the discharge even if the switch 64 and the switches 67 and 67 are both “open” and no current flows. is there. Therefore, in a mode in which the switch 64 and the switches 67 and 67 are switched so that there is a time when both are closed, the switch 64 and the switches 67 and 67 are both “open” for only a short time during which the discharge can be maintained. It is also included that the switching is performed while allowing the state to become.

  Here, the behavior of the voltage of the antenna unit 6 when the booster unit 65 is connected to and disconnected from the antenna unit 6 is shown in the graphs of FIG. 3B and FIG. 4B. In the graph, the azimuth angle of the ground-side end is 0 ° and the power-supply-side end is 360 ° when viewed from the whole antenna unit 6. Capacitors 62a, 62b and 62c are arranged at positions of 120 °, 240 ° and 360 °, respectively.

  First, the behavior of the voltage when the booster 65 shown in FIG. 3B is disconnected will be described. At 0 °, which is the ground point, the voltage is zero. When approaching the power supply 8 side from 0 °, the voltage gradually increases. This rise is due to the inductance component included in the partial antenna 61a. Although the voltage continues to rise, the voltage drops at the portion of the capacitor 62a located at 120 °. The amount of voltage drop depends on the capacitance of the capacitor 62a. Here, the capacitance of the capacitor 62a is adjusted so that the voltage drops by the amount increased by the inductance component of the partial antenna 61a.

  Even between 120 ° and 240 ° and 240 ° and 360 °, the voltage rises due to the inductance components included in the partial antennas 61b and 61c, respectively, but the voltage drops due to capacitors 62b and 62c installed at 240 ° and 360 °. . If the capacitors 62a, 62b, and 62c are not provided, the voltage continues to rise due to the inductance components of the partial antennas 61a, 61b, and 61c as shown by the dotted line in FIG. As the increased voltage drops in the capacitors 62a, 62b, and 62c, the amplitude of the voltage is kept low in the entire antenna unit 6.

  Next, the behavior of the voltage when the booster 65 shown in FIG. 4B is connected will be described. By connecting the step-up unit 65 to 0 ° of the ground point, the input voltage to the antenna unit 6 rapidly increases from the voltage zero point. Between 0 ° and 120 °, the sudden rise in voltage changes gradually, but the moderate rise is due to the inductance component of the partial antenna 61a.

  The voltage drops by the capacitors 62a, 62b, and 62c at 120 °, 240 °, and 360 °, respectively, but the amount of drop is an amount corresponding to the amount of increase due to the inductance components of the partial antennas 61a, 61b, and 61c. Therefore, the voltage raised by the booster 65 is maintained throughout the antenna unit 6.

  When starting the plasma discharge, it is desirable to increase the voltage input to the antenna unit 6, so the booster unit 65 is connected to the antenna unit 6. On the other hand, after light emission due to plasma discharge is detected, that is, after plasma discharge has started, it is desirable to keep the voltage amplitude low in order to maintain a stable plasma. Therefore, after the plasma discharge is started, the booster 65 is separated from the antenna 6. Further, the voltage increase due to the inductance components of the partial antennas 61a, 61b, 61c is lowered by the capacitors 62a, 62b, 62c, thereby suppressing the amplitude of the entire voltage of the antenna unit 6 to be low.

[effect]
(1) An etching apparatus 100 that is a plasma processing apparatus of this embodiment includes a chamber 1 into which an etching gas is introduced and a workpiece W is carried in, and a window portion 5 formed in the chamber 1 and made of a dielectric or semiconductor. And the antenna unit 6 having a plurality of partial antennas 61a, 61b, 61c and capacitors 62a, 62b arranged between them, and the antenna unit 6 is supplied with electric power. And a booster unit 65 that is detachably connected to the ground-side end of the antenna unit 6 and increases the voltage input from the power source 8 to the antenna unit 6.

  By connecting the step-up unit 65, even in the antenna unit 6 where the voltage drops by the capacitors 62a and 62b, the plasma can be discharged quickly by rapidly increasing the voltage at the start of the plasma processing. After plasma discharge, by separating the booster 65, it is possible to maintain a stable plasma while keeping the voltage amplitude low. As a result, the highly convenient etching apparatus 100 can be provided.

(2) The booster 65 may include an inductor 66. For example, the voltage can be adjusted by making the capacitor of the antenna unit 6 variable in capacity, but the variable capacity capacitor is expensive. On the other hand, since the coil that is the inductor 66 is a relatively inexpensive member, it is possible to provide the etching apparatus 100 with excellent economy.

(3) The switch 64 may be provided at the ground side end of the antenna unit 6, and the booster 65 may be connected in parallel to the switch 64 via the switches 67 and 67. By switching the two switches, the booster 65 can be easily connected and disconnected, which is highly convenient.

[Other Embodiments]
The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the boosting unit 65 includes the inductor 66. However, any device that can increase the voltage input to the antenna unit 6 can be used as appropriate. For example, as shown in FIG. 5, the booster 65 may include a resistor 68. The input voltage to the antenna unit 6 can also be increased by connecting a resistor to the ground side end of the antenna unit 6.

  In the above-described embodiment, the etching apparatus 100 has been described as an example of the plasma processing apparatus, but is not limited thereto. A film processing apparatus other than etching or a film forming apparatus such as sputtering may be used. Alternatively, a multi-chamber plasma processing apparatus including a transfer apparatus and a plurality of chambers 1 may be used.

DESCRIPTION OF SYMBOLS 1 Chamber 2 Stage 3 Matching circuit 4 Power supply 5 Window part 6 Antenna part 7 Matching circuit 8 Power supply 9 Control part 11 Gas introduction flow path 12 Exhaust flow path 13 Exhaust apparatus 14 Carry-in entrance 15 Opening 21 Lower electrode 22 Holding apparatus 23 Temperature control apparatus 61a, 61b, 61c Partial antennas 62a, 62b, 62c Capacitor 63 Ground 64 Switch 65 Boosting unit 66 Inductor 67 Switch 68 Resistance 100 Etching device

Claims (4)

A plasma processing apparatus for processing a workpiece with plasma,
A container into which process gas is introduced and the workpiece is carried;
A window formed in the container and made of a dielectric or semiconductor;
An antenna part disposed outside the container of the window part and having a capacitor provided between the plurality of partial antennas and the plurality of partial antennas;
A power supply unit for supplying power to the antenna unit;
A step-up unit that is detachably connected to the ground side end of the antenna unit, and that raises a voltage input from the power supply unit to the antenna unit,
A plasma processing apparatus comprising:   The plasma processing apparatus according to claim 1, wherein the boosting unit includes an inductor.   The plasma processing apparatus according to claim 1, wherein the boosting unit includes a resistor. A first switch is provided at a ground-side end of the antenna unit;
The plasma processing apparatus according to claim 1, wherein the boosting unit is connected in parallel to the first switch via a second switch.

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