JP5008509B2 - Plasma processing method - Google Patents

Description

  The present invention relates to a plasma processing technique for generating a plasma discharge in a space formed in a chamber, for example, and performing plasma processing using the semiconductor substrate placed in the chamber as a processing target by the plasma discharge. .

  Conventionally, in a manufacturing process of a semiconductor substrate on which various semiconductor integrated circuits constituting an LSI, for example, are formed, a plasma discharge is generated with the semiconductor substrate being placed in an etching chamber, and etching is performed by the plasma discharge. A plasma processing technique for performing plasma processing such as dry etching using a semiconductor substrate in a chamber as a processing target is used. In recent years, as this plasma processing apparatus, an inductive coupling plasma is adopted as a discharge type. The ICP type plasma processing apparatus is widely used.

  With ICP type plasma processing equipment as described above, it is increasingly important to obtain high-density plasma, maintain high uniformity, and suppress damages such as charge-up as semiconductor integrated circuits are further miniaturized. It has been developed as a means to achieve this.

  The occurrence of damage as described above is particularly noticeable in an apparatus using high-pressure plasma or an apparatus in which a plasma density is increased by applying a magnetic field, and often occurs when the plasma is non-uniform. In order to improve this, the ICP type makes it unnecessary to generate a magnetic field by a magnet or the like by generating plasma in the antenna portion which is an electrode.

The conventional technology (for example, refer to Patent Document 1) of the ICP type plasma processing apparatus as described above will be described below.
FIG. 9 is a schematic sectional view showing a basic structure of a conventional ICP type plasma processing apparatus. The plasma processing apparatus shown in FIG. 9 includes an etching chamber 900, high-frequency power sources 910a and 910b, a gas introduction path 920, an exhaust port 930, a dielectric coil 940, an electrode 950, and an inner wall of the etching chamber 900 immediately below the dielectric coil 940. A dielectric plate 960a, such as a quartz plate, a dielectric plate 960b disposed on the Faraday shield 970b, a Faraday shield 970a disposed between the dielectric coil 940 and the dielectric plate 960a, and a dielectric coil 940. And a Faraday shield 970b disposed on the inner wall of the etching chamber 900 which is not directly below.

  Focusing on the part shown in FIG. 10A in this plasma processing apparatus, for example, a dielectric coil (ICP electrode) 940 and Faraday shields (FS electrodes) 970a and 970b are provided as two or more electrodes in the same space of the etching chamber 900. When the high-frequency power is separately applied to the electrodes 940, 970a, and 970b from the individually connected high-frequency power sources 910a and 910b in the plasma processing apparatus provided, as shown in FIG. When high-frequency signals having substantially the same frequency are applied, frequency interference is likely to occur between these high-frequency signals, and frequency interference is particularly likely to occur when the phases are close or the same.

Therefore, when there are two or more electrodes 940, 970a, 970b in the same space of the etching chamber 900 as in the plasma processing apparatus shown in FIG. 9, as shown in FIG. , 970a and 970b, each of the high-frequency power supplies 910a and 910b connected individually is independently applied with a high-frequency signal having substantially the same frequency, and the phase-shift adjuster 990 causes each high-frequency power supply 910a, Plasma discharge is performed in the space 980 in the etching chamber 900 by shifting the phase of each high-frequency signal between the 910b substantially by 180 degrees (here, 180 degrees ± 30 degrees) so that the phases are substantially reversed. It is trying to generate.
JP 2005-209885 A

  However, in the conventional plasma processing apparatus as described above, the frequency relationship between the high-frequency signals supplied to the ICP electrode and the FS electrode is set to be substantially opposite to each other by making the phase relationship between the high-frequency signals substantially opposite to each other. Interference can be almost suppressed, but the impedance matching itself between the high frequency power supply for the ICP electrode and the ICP electrode and between the high frequency power supply for the FS electrode and the FS electrode, as well as its accuracy and workability Almost no consideration is given, and it is difficult to obtain stable plasma ignition simply by suppressing frequency interference between each high-frequency signal as described above. For this purpose, adjustment of each part such as output power of each high-frequency power source is difficult. This is not only very troublesome, but also has the problem that plasma discharge cannot be excited reliably.

  The present invention solves the above-mentioned conventional problems, and not only eliminates the frequency interference between the high frequency signals for the ICP electrode and the FS electrode, but also for the ICP electrode and the FS for each of the high frequency signals. Impedance matching between each high-frequency power supply for electrodes and each corresponding electrode can be performed easily and accurately in a short time, enabling stable ignition of plasma easily and exciting plasma discharge reliably. Provided is a plasma processing method capable of

In order to solve the above problems, flop plasma processing method of the present invention, the first space, the first electrode is provided for inductive coupling with a second space which the treatment object adjacent to the first space is provided A second electrode for providing a Faraday shield between the first electrode and the second space is provided in the first space between the first electrode and the second space in the first space; A first high-frequency power source that supplies a first high-frequency signal to one electrode, and a second high-frequency signal that is substantially opposite in phase to the first high-frequency signal to the second electrode and is independent of the first high-frequency power source A first high-frequency power source, a first matching unit that impedance-matches the first high-frequency signal between the first high-frequency power source and the first electrode, and between the second high-frequency power source and the second electrode, A second adjustment for impedance matching with the second high frequency signal A first variable capacitor connected in series to the first electrode for impedance matching between the first high-frequency power source and the first electrode; and A second variable capacitor for a load connected in parallel to the output side of the first high-frequency power source, and the second matching unit is configured to adjust the impedance matching between the second high-frequency power source and the second electrode. For this purpose, it includes a third variable capacitor for impedance adjustment connected in series to the second electrode, and a fourth variable capacitor for load connected in parallel to the output side of the second high-frequency power source, together with the first high-frequency signal is supplied to the electrode, the second high-frequency signal is supplied to the second electrode, a plasma discharge generated in the second space, the processing object of the second space To plasm For a plasma processing apparatus that performs processing, the capacitance value of the fourth variable capacitor is fixed, and the input power to the first matching unit by the first high-frequency signal and the second matching by the second high-frequency signal An output power that is a ratio of an input power ratio that is a ratio to the input power to the device, an output power of the first electrode by the first high-frequency signal, and an output power of the second electrode by the second high-frequency signal Control is performed so that the ratio is a predetermined value.

Moreover, equal camphor Rukoto Preferably the output power ratio and the entering force power ratio.

Further, after fixing the pre Symbol capacitance value of the fourth variable capacitor, each high-frequency signal is put into the first electrode and the second electrode, and fixing the third variable capacitor to the plasma discharge ignition start position, the by automatically aligning the first matching unit by automatically changing the capacity value of the first variable capacitor second variable capacitor, when the plasma discharge is stabilized by exciting, of the third variable capacitor it may be self-aligned with the second matching unit by automatically changing the capacitance value.

In addition, before fixing the third variable capacitor at the ignition start position of the plasma discharge, an ignition matching region at the start of the plasma discharge ignition and an ignition matching region at the time elapsed after the plasma discharge ignition. seeking the door, the region encompassing both ignition matching region may be automatically moved to set the ignition alignment position during the plasma discharge ignition start.

  As described above, according to the present invention, as a preset condition for the automatic matching process, by fixing the fourth variable capacitor of the second matching unit to a predetermined capacitance value, a plurality of matching points are combined into one. The ratio of the input power ratio and the output power ratio can be managed at 1: 1 with respect to the first electrode and the second electrode, and the process can be controlled without using a special conversion table.

  Therefore, not only the frequency interference between the high-frequency signals for the first electrode and the second electrode is eliminated, but the high-frequency power sources for the first electrode and the second electrode are respectively applied to these high-frequency signals. Impedance matching between each corresponding electrode can be performed easily and accurately in a short time, stable ignition of plasma can be easily realized, and plasma discharge can be excited reliably.

Hereinafter, a plasma processing method showing an embodiment of the present invention will be specifically described with reference to the drawings.
(Embodiment 1)
A plasma processing method according to Embodiment 1 of the present invention will be described.

  FIG. 1 is a circuit block diagram showing a configuration example of a plasma processing apparatus for the plasma processing method of the first embodiment. In FIG. 1, ID1 is an ICP electrode (coil), IR1 is an RF (high frequency) power source for ICP (here, a high frequency signal of 13.56 MHz is output), IM1 is an ICP matching device, and CIT1 is a tuning device on the ICP matching device IM1 side. (Adjustment) Variable capacitor (here 100-500 pF), CIL1 is a load (load) variable capacitor (here 100-2000 pF) on the ICP matching device IM1 side, FD1 is an FS electrode (conductor plate), FR1 is FS RF (high frequency) power source (here, outputs a high frequency signal of 13.56 MHz), FM1 is an FS matching device, LF1 is an inductor (coil) (here 2 μH), and CFT1 is for Tuning on the FS matching device FM1 side (for adjustment) ) Variable capacitor (here 50-500pF), CFL1 is for load on FS matching unit FM1 side (for load) Variable capacitor (here 150-1500pF is), ZFT1 impedance element, SS1 control means, the IS1 a phase shift adjuster.

  In addition, as shown in FIG. 1, the plasma processing apparatus for the plasma processing method of the first embodiment has an ICP matching device IM1 between the output of the ICP RF power source IR1 and the ICP electrode ID1. The Tun variable capacitor CIT1 is connected in series from the output of the RF power supply IR1, and the Load variable capacitor CIL1 is connected in parallel from the connection point of the ICP RF power supply IR1 and the Tun variable capacitor CIT1 to the ground. .

  Further, as the FS matching unit FM1, between the output of the FS RF power supply FR1 and the FS electrode FD1, the output of the FS RF power supply FR1 is connected in series in the order of the inductor LF1 for Tun and the variable capacitor CFT1 for Tun. A load variable capacitor CFL1 is connected in parallel from the connection point of the output of the FS RF power supply FR1 and the inductor LF1 to the ground.

  Further, the control means SS1 uses the ICP matching unit IM1 between the ICP RF power source IR1 and the ICP electrode ID1 and the FS matching unit FM1 between the FS RF power source FR1 and the FS electrode FD1. When impedance matching is performed on signals, the variable capacitors for Tunes CIT1, CFT1, and Variable for Load provided in the ICP matching unit IM1 and the FS matching unit FM1, respectively, according to the current matching state between them. By controlling the adjustment positions of the capacitors CIL1 and CFL1, each value (capacitance) of each of the variable capacitors CIT1 and CFT1 for Tune and the variable capacitors CIL1 and CFL1 for Load is adjusted.

  In the above plasma processing apparatus, each variable capacitor can be changed in its adjustment position by manual (manual) operation from the operation means (not shown) via the control means or directly. It is configured.

The operation of the plasma processing apparatus configured as described above will be described below.
Here, the input power to the ICP matching unit IM1 by the ICP high frequency signal (hereinafter simply referred to as “input power to the ICP matching unit IM1”) and the input power to the FS matching unit FM1 by the FS high frequency signal. (Hereinafter, simply referred to as “input power to the FS matching unit FM1”) is defined as an input power ratio, and the output power of the ICP electrode ID1 by the ICP high frequency signal (hereinafter simply referred to as “output of the ICP electrode ID1”). The ratio of the output power of the FS electrode FD1 by the FS high-frequency signal (hereinafter simply referred to as “output power of the FS electrode FD1”) will be described as the output power ratio.

  First, the reason why a matching unit is required as in the plasma processing apparatus shown in FIG. 1 will be described as a process from the unmatched conventional configuration to the configuration for the plasma processing method of the present invention using the matching unit.

  The plasma processing apparatus shown in FIG. 1 is not matched by adjusting only the phase shift adjuster IS1 as before (regardless of matching). Therefore, as shown in FIG. 1, the ICP matching unit IM1 for impedance matching between the output of the ICP RF power supply IR1 and the ICP electrode ID1, and the output of the FS RF power supply FR1 and the FS electrode FD1. The FS matching unit FM1 for impedance matching and the phase shift adjuster IS1 are adjusted. That is, the impedances of the ICP matching unit IM1 and the FS matching unit FM1 are adjusted, and further the phase shift adjusting unit IS1 is adjusted, so that the output voltage from the ICP matching unit IM1 to the ICP electrode ID1 and the FS matching unit FM1 to the FS electrode FD1. When the phase of the output voltage is shifted by approximately 180 degrees, impedance matching can be achieved between the output of the ICP RF power supply IR1 and the ICP electrode ID1, and between the output of the FS RF power supply FR1 and the FS electrode FD1.

  The FS-ICP matching unit as shown in FIG. 1 has each high-frequency signal generated by the phase difference between the high-frequency signals at the position where both high-frequency signals from the ICP RF power supply IR1 / FS RF power supply FR1 are applied and matched. The ratio applied to each electrode of the ICP electrode ID1 / FS electrode FD1 is different. Thus, for example, the power distribution varies sensitively due to the value change (change in the adjustment position) of the load variable capacitor CFL1 of the FS matching unit FM1, so that both high-frequency signals are applied almost independently. A fixed value (adjustment position) of the load variable capacitor CFL1 of the instrument FM1 is acquired in advance.

  Therefore, in the plasma processing apparatus shown in FIG. 1, the value of the load variable capacitor CFL1 of the FS matching unit FM1 is changed for each power source of the ICP RF power source IR1 / FS RF power source FR1, and the ICP electrode ID1 and By controlling the ratio of the input power ratio and the output power ratio with respect to the FS electrode FD1, the value of the load variable capacitor CFL1 of the FS matching unit FM1 is fixed at a position where the ratio becomes a predetermined value.

  Further, by changing the input power ratio of the high frequency signal to the ICP matching unit IM1 and the FS matching unit FM1 with the value of the load variable capacitor CFL1 of the FS matching unit FM1 fixed at a predetermined position, the ICP electrode ID1 Further, the control is performed so that the ratio of the input power ratio and the output power ratio becomes a predetermined value with respect to the FS electrode FD1.

Note that the ratio of the input power ratio and the output power ratio controlled for the ICP electrode ID1 and the FS electrode FD1 is preferably 1: 1 in terms of operation.
This will be explained supplementarily.

  The ICP electrode ID1 is mainly responsible for generating high-density plasma in order to perform the etching process, and the FS electrode FD1 is capacitively coupled with the plasma to remove deposits attached to the dielectric plate 960, and is connected to the dielectric plate. The role is to sputter (remove) the deposited deposits. In order to control such plasma density and removal of deposits independently, it is necessary to individually control the input power and output power for each of the ICP electrode ID1 and the FS electrode FD1.

  Therefore, by setting the ratio of the input power ratio and the output power ratio of the ICP electrode ID1 and the FS electrode FD1 to 1: 1, an independent power source is used between the ICP electrode ID1 and the FS electrode FD1. Independent control of plasma density and deposit removal can be performed efficiently without the need for significant numerical conversion during operation.

  This means that in order to efficiently execute independent control of plasma density and deposit removal between the ICP electrode ID1 and the FS electrode FD1, the ratio between the input power ratio and the output power ratio is 1: 1. This is preferable.

Here, ancillary conditions of the circuit constants of the Tun inductor LF1 of the FS matching unit FM1 will be described.
As shown in FIG. 2A, the plasma processing apparatus shown in FIG. 1 has a configuration in which the ICP electrode ID1 and the FS electrode FD1 are arranged so as to overlap each other through a vacuum space. In terms of an equivalent circuit, as shown in FIG. 2B, the ICP electrode ID1 and the FS electrode FD1 are capacitively connected with the above space as a capacitance. Also, the impedance ZFT1 due to the Tun variable capacitor CFT1 and the Tun inductor (coil) LF1, which are the variable elements for Tun of the FS matching device FM1, acts as a capacitance component on the input side of the FS matching device FM1.

  In the FS matching unit FM1 shown in FIG. 1, as shown in FIGS. 3A and 3B, the value of the variable variable capacitor CFL1 (adjusted value of the FS LOAD) is used as a parameter. By adjusting the value (adjusted value of FS TUNE) and the value of the inductor (coil) LF1 for Tune, and changing the R component of the impedance (Z = R + jX) ZFT1 by them, the output power in the ICP electrode ID1 enters the chamber As a result, the ratio between the input power ratio and the output power ratio can be controlled with respect to the ICP electrode ID1 and the FS electrode FD1.

  For example, in FIG. 3, with the adjustment value of FS LOAD as a parameter, the value of Tun variable capacitor CFT1 (adjustment value of FS TUNE) out of Tun variable capacitor CFT1 and Tune inductor (coil) LF1 of FS matcher FM1 As shown in FIG. 3B, the real part (resistance value: R) component of impedance (Z = R + jX) ZFT1 changes, so that the terminal voltage of the ICP electrode ID1 and the FS electrode FD1 Although the terminal voltage (Vpp) can be adjusted, the real part (resistance value: R) component of the impedance (Z = R + jX) ZFT1 in this case is the change range FZH2 (see FIG. 3B). It is preferable to adjust to the change range FZH1 (the solid line side in FIG. 3B) with the lowest possible value from the dotted line side) For this purpose, the inductance value of the Tune inductor (coil) LF1 is changed to the impedance (as shown in FIG. 3B) with respect to the variable range (50 to 500 pF) of the Tun variable capacitor CFT1 shown in FIG. Z = R + jX) For example, the number of turns of the Tune inductor (coil) LF1 is changed so that the change range of the real part (resistance value: R) component of ZFT1 becomes the appropriate change range (approximately 7 to 110Ω) FZH1. Adjust by.

  Here, as shown in FIG. 1, the inductance value of the Tune inductor (coil) LF1 is 2 μF compared to the case where the capacitance value of the Tune variable capacitor CFT1 can be varied from 50 pF to 500 pF.

  Based on the above description, as a method of adjusting the ratio between the input power ratio and the output power ratio performed for the ICP electrode ID1 and the FS electrode FD1 in the plasma characteristic independent control system using the ICP matching unit IM1 and the FS matching unit FM1. Setting of input power ratio for ICP matching unit IM1 and FS matching unit FM1, output power ratio for ICP electrode ID1 and FS electrode FD1, and value of variable capacitor CFL1 for load of FS matching unit FM1 (FS LOAD adjustment position) explain.

  FIG. 4 is an explanatory diagram of an output power ratio adjustment method in the plasma processing method of the first embodiment. In this output power ratio adjustment method during matching adjustment, as shown in FIG. 4, the value of the load variable capacitor CFL1 (FS LOAD adjustment position) of the FS matching unit FM1 is changed with respect to the individual high-frequency power sources IR1 and FR1. The output power ratio with respect to the ICP electrode ID1 and the FS electrode FD1 is adjusted, and the ratio of the input power ratio and the output power ratio with respect to the ICP electrode ID1 and the FS electrode FD1 is controlled, so that the load of the FS matching unit FM1 is loaded. The value of the variable capacitor CFL1 (FS LOAD adjustment position) is fixed at a position where the input power ratio and the output power ratio are equal to the ICP electrode ID1 and the FS electrode FD1.

  4A shows the case where the input power ratio is 300 W / 600 W (1: 2) with respect to the ICP electrode ID1 and the FS electrode FD1, and FIG. 4B shows the input with respect to the ICP electrode ID1 and the FS electrode FD1. FIG. 4C shows the case where the power ratio is 600 W / 300 W (2: 1), and FIG. 4C shows the case where the input power ratio is 900 W / 300 W (3: 1) with respect to the ICP electrode ID1 and the FS electrode FD1. 4 (d) shows a case where the input power ratio is 900 W / 600 W (3: 2) with respect to the ICP electrode ID1 and the FS electrode FD1, and here, for convenience of the following explanation, it is equal to the input power ratio in each case. The FS LOAD adjustment position for obtaining the output power ratio is assumed to be 6.5 in all cases.

  As described above, the plasma density is adjusted by the ICP electrode ID1, and the deposits adhered to the top plate by the FS electrode FD1 (the strength of capacitive coupling and the strength of the voltage generated between the plasma and the dielectric plate) are removed. Adjustments are being made.

  By changing each input power to the ICP electrode ID1 and the FS electrode FD1, the ICP electrode ID1 increases the plasma density and performs higher-speed etching, or adjusts the plasma density and decreases it to an appropriate value. Appropriate measures are taken when maintaining the selection ratio with the resist or when high power is applied to increase the ignition stability during the ignition step, and then the input power is reduced (adjusted) to the desired value during the main etch step. The FS electrode FD1 removes deposits attached to the top plate, but there is a difference in the amount of deposits attached to the top plate depending on the type of film to be etched, pattern and conditions. Accordingly, when adjusting the input power accordingly, it is possible to appropriately cope with it.

  As described above, by changing the input powers to the ICP electrode ID1 and the FS electrode FD1, it is possible to use in a stepwise manner before the plasma treatment and to adjust according to the conditions. By the matching circuit and the matching operation in the plasma processing apparatus for the above, mutual interference by the individual high-frequency power sources IR1 and FR1 can be suppressed, and independent controllability can be ensured and efficient control can be performed.

  Based on the above, next, in the plasma characteristic independent control system using the ICP matching unit IM1 and the FS matching unit FM1, adjustment of the output power ratio for the ICP electrode ID1 and the FS electrode FD1 with respect to the change of the input power ratio due to each high frequency signal As a method, when the value of the load variable capacitor CFL1 (FS LOAD adjustment position) of the FS matching unit FM1 is fixed at a predetermined position, each input power to the ICP matching unit IM1 and the FS matching unit FM1 by each high frequency signal is set. The influence dependency on the output power of the ICP electrode ID1 and the FS electrode FD1 when changed is described.

  FIG. 5 is an explanatory diagram of the dependency due to the input power on each electrode side in the plasma processing method of the first embodiment. In this output power ratio adjustment method at the time of matching adjustment, as shown in FIG. 5, the value of the load variable capacitor CFL1 (FS LOAD adjustment position) of the FS matching unit FM1 is set to a predetermined position (here, for convenience, FIG. 4). The output power ratio is adjusted by changing the input power ratio in a state where the obtained adjustment position is fixed to 6.5), and the input power ratio and the output power ratio with respect to the ICP electrode ID1 and the FS electrode FD1. The ratio is controlled so as to be a predetermined value.

  FIG. 5A shows the dependency of the input power on the ICP electrode ID1 side on the output power. FIG. 5A shows each output power when the input power ratio is ** / 200 W and the input power on the ICP electrode ID1 side is changed. FIG. 5B shows the change of each output power when the input power ratio is ** / 600 W and the input power on the ICP electrode ID1 side is changed, and the input on the FS electrode FD1 side. FIG. 5C shows the change in output power when the input power ratio is 200 W / ** and the input power on the FS electrode FD1 side is changed. d) shows the change of each output power when the input power ratio is 600 W / ** and the input power on the FS electrode FD1 side is changed.

  As described above, as a preset condition for the automatic matching process, the load (fourth) variable capacitor CFL1 of the FS (second) matching unit FM1 is fixed to a predetermined capacitance value so that a plurality of matching points are obtained. Thus, the ratio of the input power ratio and the output power ratio can be managed at 1: 1 with respect to the ICP (first) electrode ID1 and the FS (second) electrode FD1, and a special conversion table is used. Control in the process is possible.

Next, an automatic matching feedback method at the time of individual high frequency power supply in the plasma processing method of the first embodiment will be described.
FIG. 6 is an explanatory diagram of processing steps by the plasma processing method of the first embodiment. FIG. 7 is an explanatory view of a plasma discharge ignition situation by the plasma processing method of the first embodiment.

  When the individual high frequency power supply of the plasma processing apparatus shown in FIG. 1 is supplied, the automatic matching feedback method uses the load variable capacitor (FS LOAD) CFL1 of the FS matching unit FM1 as the output power ratio as shown in FIGS. FS matching is performed by outputting high-frequency signals (RF signals) from the individual high-frequency power sources IR1 and FR1 to the ICP electrode ID1 and the FS electrode FD1 in the same space and fixing the corresponding preset positions. After the excitation of plasma discharge by the ICP electrode ID1, the variable capacitor for tune (FS TUNE) CFT1 of the vessel FM1 is fixed at the On Prise position, which is the plasma ignition start position by the ICP electrode ID1, and the ICP electrode ID1 side is automatically aligned ( Plasma discharge is excited on the ICP electrode ID1 side The FS electrode FD1 side is moved to the FS matching device by the automatic matching operation at the time when the reflected wave decreases and falls within the allowable value. FM1 Tuning Capacitor for FM (FS TUNE) CFT1 is adjusted in position and impedance matched automatically.

First, an operation flow at the time of plasma discharge ignition NG will be described.
In the operation at the time of plasma discharge ignition NG, as shown in FIGS. 6A and 7A, the ICP RF signal from the ICP RF power source IR1 and the FS RF signal from the FS RF power source FR1 are applied. The plasma processing apparatus is preset in a state where it is not (step S600A). Here, the capacitance value (adjustment position of FS LOAD) of the load variable capacitor CFL1 of the FS matching unit FM1 is fixed to the capacitance value (adjustment position) obtained as a preset condition according to the description shown in FIGS. The output power ratio between the ICP electrode ID1 and the FS electrode FD1 is fixed.

  Then, RF signal power is input from the RF power sources IR1 and FR1 corresponding to the respective electrodes of the ICP electrode ID1 and the FS electrode FD1 (step S601A). In this case, since the RF signal power of the same frequency is input from the corresponding RF power source to each of the ICP electrode ID1 and the FS electrode FD1, the matching positions on the ICP electrode ID1 side and the FS electrode FD1 side interfere with each other. This is a problem in the mating operation.

  Thereafter, until the plasma discharge by the ICP electrode ID1 is excited, both the ICP matcher IM1 and the FS matcher FM1 simultaneously start an automatic matching operation (Matching) (step S602A). Plasma discharge ignition is started (step S603A).

  In this case, due to the start of the automatic matching operation of the ICP matching unit IM1 and the FS matching unit FM1, before the plasma ignition, the load variable capacitors CIL1, CFL1 or the Tuning variable of one of the ICP matching unit IM1 and the FS matching unit FM1 are changed. When the adjustment positions of the capacitors CIT1 and CFT1 have moved greatly, the adjustment position of the other load variable capacitor or Tune variable capacitor is also greatly deviated from the normal matching point. Therefore, the reflected wave from ICP electrode ID1 increases, and the plasma discharge by ICP electrode ID1 may not ignite normally and may not be excited.

  In contrast to this, in the first embodiment of the present invention, as shown in FIGS. 6B and 7B, first, the ICP RF signal from the ICP RF power source IR1 and the FS RF power source FR1 are used. The plasma processing apparatus is preset without applying the FS RF signal (step S600B). Here again, as in the case of step S600A, the capacitance value (adjustment position of FS LOAD) of the load variable capacitor CFL1 of the FS matching unit FM1 is obtained as a preset condition according to the description shown in FIG. 4 and FIG. The output power ratio between the ICP electrode ID1 and the FS electrode FD1 is fixed.

  Then, corresponding RF signal power is input to each of the ICP electrode ID1 and the FS electrode FD1 (step S601B), and the Tun variable capacitor CFT1 of the FS matching unit FM1 is excited by the On Prise position (excited by the ICP electrode ID1). After being fixed at the plasma ignition position (step S602B), the ICP electrode ID1 side is automatically aligned by the ICP matcher IM1 (step S603B), thereby stably igniting the plasma discharge by the ICP electrode ID1 (step S604B).

After that, the FS electrode FD1 side is automatically matched by the Tun variable capacitor CFT1 of the FS matching unit FM1 (step S605B).
By the above operation, the phases between the high frequency signals supplied to the respective electrodes of the ICP electrode ID1 and the FS electrode FD1 are substantially reversed in phase (with a phase difference of 180 ° ± 30 °). In addition to eliminating frequency interference between the high-frequency signals for the FS electrodes, for each of the high-frequency signals, between the high-frequency power sources for the ICP electrode and the FS electrode and the corresponding electrodes ID1, FD1, Impedance matching can be performed easily and accurately in a short time, stable ignition of plasma can be easily realized, and plasma discharge can be excited reliably.
(Embodiment 2)
A plasma processing method according to Embodiment 2 of the present invention will be described.

  FIG. 8 is an explanatory diagram of the plasma processing method of the second embodiment. In FIG. 8, PCS1 is an ignition matching region at the start of plasma ignition (unconsumed / non-attached), PCK1 is an ignition matching region at the start of plasma ignition (consumed / attached) after the mass production processing time has elapsed, and CM1 and CM2 are ignited. Alignment position.

  Here, in the mass production process by plasma etching, when several hundred or more wafers are processed, the dielectric plate 960 may be partially deposited or the dielectric plate may be scraped depending on the etching film type and conditions ( exhaust. In addition, when a depot adheres to the dielectric plate and the FS power is set high so that the depot does not adhere to the dielectric plate 960, the dielectric plate 960 is scraped little by little, and this is repeated, and the dielectric plate becomes thin. Occurs. As a result, the dielectric plate after mass production processing by plasma etching is consumed or deposits are deposited, so that the plasma ignition matching region is changed from the time of starting plasma ignition (unconsumed / unattached).

  In the plasma processing method according to the second embodiment, as shown in FIG. 8, the ignition matching region PCS1 at the start of plasma ignition in the initial state of the dielectric plate (unconsumed / unattached) is used for mass production by plasma etching. Then, a region including both ignition matching regions with the ignition matching region PCK1 when the dielectric plate is worn out or the time after the plasma ignition when the deposit is attached (consumed / attached state) is obtained, and only the ignition matching region PCS1 is obtained. For example, the existing ignition alignment position CM1 is moved to a region including both ignition alignment regions to be set as, for example, an ignition alignment position CM2, and the ignition alignment position CM2 is set as a good ignition alignment position that can cope with a change with time in the plasma ignition state. To do.

  As described above, stable ignition characteristics of plasma can be obtained over a long period of time.

  The plasma processing method of the present invention not only eliminates the frequency interference between the high frequency signals for the ICP electrode and the FS electrode, but also provides the high frequency power source for the ICP electrode and the FS electrode with respect to each high frequency signal. Impedance can be easily and accurately matched between each corresponding electrode in a short time, stable plasma ignition can be easily realized, and plasma discharge can be excited reliably. For example, the present invention can be applied to various plasma processing techniques such as performing plasma processing on a semiconductor substrate.

1 is a circuit block diagram showing a configuration example of a plasma processing apparatus for the plasma processing method of Embodiment 1 of the present invention. Explanatory drawing of the circuit constant conditions in the plasma processing apparatus for the plasma processing method of Embodiment 1 Explanation of the reason for the occurrence of circuit constant conditions in the plasma processing method of the first embodiment Explanatory drawing of the output power ratio adjustment method in the plasma processing method of Embodiment 1 Explanatory drawing of the input power dependence of each electrode in the plasma processing method of the first embodiment Explanatory drawing of the process process by the plasma processing method of Embodiment 1 Explanatory drawing of the plasma discharge ignition situation by the plasma processing method of the first embodiment Explanatory drawing of the plasma processing method of Embodiment 2 of this invention Circuit block diagram showing a configuration example of a conventional plasma processing apparatus Waveform diagram showing the operation of the conventional plasma processing apparatus

Explanation of symbols

ID1 ICP electrode (coil)
IR1 RF (high frequency) power supply for ICP IM1 ICP matcher LI1 Inductor (coil)
Variable capacitor for CIT1 Tune (for adjustment) Variable capacitor for CIL1 Load (for load) CI1 capacitor FD1 FS electrode (conductor plate)
FR1 FS RF (high frequency) power supply FM1 FS matching unit LF2 Inductor (coil)
LF1 inductor (coil)
Variable capacitor for CFT1 Tuning (for adjustment) Variable capacitor for CFL1 Load (for load) CF2 capacitor CF1 capacitor ZFT1 Impedance element SS1 Control means IS1 Phase shift adjuster PZ1 Plasma capacity FZH1 (with respect to the low band position of FS TUNE) Change range FZH2 Change range of real part of impedance (with respect to high frequency position of FS TUNE) CM1, CM2 Ignition matching position PCS1 Ignition matching area at the start of plasma ignition (unconsumed / unattached) PCK1 At the start of plasma ignition (consumed / attached) Ignition matching area

Claims (4)

The first space is provided with a first electrode that is inductively coupled to a second space in which a treatment object is provided adjacent to the first space ;
A second electrode for providing a Faraday shield between the first electrode and the second space is provided in the first space between the first electrode and the second space in the first space ;
A first high frequency power supply for supplying a first high frequency signal to the first electrode;
A second high-frequency power source that supplies a second high-frequency signal having a substantially opposite phase to the first high-frequency signal to the second electrode and is independent of the first high-frequency power source;
A first matching unit for impedance matching with the first high-frequency signal between the first high-frequency power source and the first electrode;
A second matching unit for impedance matching with the second high-frequency signal between the second high-frequency power source and the second electrode;
The first matching unit includes:
For the impedance matching between the first high frequency power source and the first electrode,
A first variable capacitor for impedance adjustment connected in series to the first electrode;
A second variable capacitor for a load connected in parallel to the output side of the first high-frequency power source;
The second matching unit includes:
For the impedance matching between the second high frequency power source and the second electrode,
A third variable capacitor for impedance adjustment connected in series to the second electrode;
A fourth variable capacitor for load connected in parallel to the output side of the second high frequency power supply;
Together with the first high-frequency signal to said first electrode is supplied, said second electrode a second high-frequency signal is supplied, the plasma discharge generated in the second space, said second space For plasma processing equipment that performs plasma processing on objects
The capacitance value of the fourth variable capacitor is fixed,
An input power ratio that is a ratio of an input power to the first matching unit by the first high-frequency signal and an input power to the second matching unit by the second high-frequency signal;
Control is performed so that the ratio of the output power ratio, which is the ratio of the output power of the first electrode by the first high-frequency signal and the output power of the second electrode by the second high-frequency signal, becomes a predetermined value. A plasma processing method. The plasma processing method according to claim 1,
A plasma processing method, wherein the input power ratio and the output power ratio are made equal. The plasma processing method according to claim 1 or 2, wherein
After fixing the capacitance value of the fourth variable capacitor, each high frequency signal is input to the first electrode and the second electrode, and the third variable capacitor is fixed to the plasma discharge ignition start position,
By automatically changing the capacitance values of the first variable capacitor and the second variable capacitor, the first matching unit is automatically matched,
When the plasma discharge is excited and stabilized, the second matching unit is automatically matched by automatically changing the capacitance value of the third variable capacitor. The plasma processing method according to claim 3,
Before fixing the third variable capacitor at the ignition start position of the plasma discharge,
Finding the ignition matching region at the start of ignition of the plasma discharge and the ignition matching region at the time elapsed after the ignition of the plasma discharge,
A plasma processing method, wherein the setting of the ignition alignment position at the start of the plasma discharge ignition is automatically moved to a region including both ignition matching regions.

Images