KR20080087738A - Plasma processing apparatus, plasma processing method and recording medium - Google Patents

Abstract

A plasma processing apparatus, a plasma processing method and a recording medium are provided to implement a plasma processing by performing a proper impedance adjustment irrespective of a high frequency bias. A plasma processing apparatus includes a high frequency power(39), an impedance adjusting unit(5), a voltage measuring unit(57), a bandpass filter(56), and a control unit(6). The high frequency power applies a high frequency for a bias lower than a high frequency for plasma to an electrode. An end of the impedance adjusting unit is coupled to an anode electrode, and the other end of the impedance adjusting unit is coupled to a processing chamber. The impedance adjusting unit controls an impedance value from a cathode electrode to a ground housing of a matching circuit via plasma, the anode electrode and the processing chamber. The voltage measuring unit measures a voltage of the impedance adjusting unit. The bandpass filter is installed between the impedance adjusting unit and the voltage measuring unit. The bandpass filter has an attenuation band of f1-f2 and f1+f2, wherein the f1 is defined by a high frequency for the plasma and the f2 is defined by a high frequency for the bias. The control unit changes the impedance value of the impedance adjusting unit and receives a voltage value measured by the voltage measuring unit. The control unit calculates a current value received to the anode electrode, and sets the impedance value of the impedance adjusting unit.

Description

Plasma processing apparatus, plasma processing method and storage medium {PLASMA PROCESSING APPARATUS, PLASMA PROCESSING METHOD AND RECORDING MEDIUM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus, a plasma processing method, and a storage medium in which a processing gas is converted into plasma by high frequency power, and the substrate is subjected to processing such as etching.

In the manufacturing process of flat panels, such as a semiconductor device and a liquid crystal display device, in order to perform process processes, such as an etching process and a film-forming process, to a to-be-processed substrate, such as a semiconductor wafer and a glass substrate, a plasma etching apparatus, a plasma CVD film-forming apparatus, etc. Plasma processing apparatus is used.

In general, a parallel plate type capacitively coupled plasma processing apparatus is used as the plasma processing apparatus. Fig. 11 is an equivalent circuit in this type of plasma processing apparatus, and the wall portion of the processing container 11 becomes an inductance component with respect to high frequency. Therefore, when plasma is generated in the processing container 11, the capacitive coupling between the upper electrode 12 and the lower electrode 13 causes the path of the high frequency current from the high frequency power supply 14 to match the circuit 15. The lower electrode 13 → plasma → upper electrode 12 → wall portion of the processing vessel 11 → matching box 16 → ground.

By the way, the glass substrate for flat panels, such as a liquid crystal monitor, tends to become larger in a board | substrate which is a process target, and when the processing container 11 becomes large according to this, the inductance component of the processing container 11 becomes large, for this reason, Coupling between the upper electrode 12 and the lower electrode 13 becomes weak, and there is a fear that plasma will be generated between the lower electrode 13 and the wall of the processing container 11 (described as capacitive coupling in FIG. 11). . When such plasma is generated, the plasma in the processing container 11 is biased toward the periphery, and as a result, the processing with high in-plane uniformity cannot be performed on the substrate 10, or the inner wall or the inside of the processing container 11 is eliminated. There is a problem that the parts are damaged or the consumption becomes easy to proceed.

Therefore, the applicant of this application proposes the technique of providing an impedance adjustment part in order to solve such a problem (patent document 1). FIG. 12 shows a plasma etching apparatus 1 in which an impedance adjusting unit 17 including an inductor 17a and a capacitor variable capacitor 17b is provided when the lower electrode is a cathode electrode, and the high frequency path is a high frequency power source. (14) → conductive path 14A → matching circuit 15 → lower electrode 13 → plasma → upper electrode 12 → conductive path 12A → impedance adjusting unit 17 → wall of processing vessel 11 → The matching box 16 is grounded. In Patent Document 1, when the impedance value of the impedance adjusting unit 17 is adjusted so that the current value flowing through the anode electrode (the lower electrode in Patent Document 1) is maximized, the impedance value between the anode electrode and the processing container becomes maximum. It promotes and suppresses abnormal discharge. In addition, although abbreviate | omitted in FIG. 12, a high frequency bias may be applied to the lower electrode 13, and a plasma etching process may be performed.

By the way, as shown in FIG. 13, the actual current value is measured between the probe 18a and 18a for measuring the high voltage between the upper electrode 12, the capacitor variable capacitor 17b, and the inductor 17a, respectively. ), And the broadband oscilloscope 18b connected to the computer 18 on which dedicated software is installed is connected to these probes 18a and 18a, and then predetermined processing conditions are set to form plasma. And each position of the capacitive variable capacitor 17b using the probes 18a and 18a, the computer 18, and the broadband oscilloscope 18b, while the operator of the apparatus manually changes the capacitance of the capacitive variable capacitor 17b. In the above, the voltage waveform data corresponding to the frequency of the high frequency power supply 14 is measured, and the current [I-total] flowing to the upper electrode 12 is calculated based on this data, and the formed plasma is visually observed. The capacitance of the variable capacitance capacitor 17b was determined from the discharge state by visual observation and the calculated current value, and a lot of hand went.

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2005-340760: Paragraphs 0027 to 0030, 0058, and 0061

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an impedance adjusting unit provided between an anode electrode and a processing container, whereby impedance adjustment of the impedance adjusting unit for suppressing abnormal discharge can be easily and appropriately performed. Is to provide the technology.

The plasma processing apparatus of the present invention is provided with a cathode electrode which is insulated from the processing container in a processing container and connected to a high frequency power source for outputting a high frequency for plasma generation via a matching circuit, facing the cathode electrode, An anode electrode insulated from the processing container via an insulator; a substrate is mounted on one of the cathode electrode and the anode electrode, and plasma treatment of the processing gas is carried out by high-frequency power; A plasma processing apparatus of a parallel plate type plasma processing comprising: a high frequency power source for bias for applying a high frequency wave for bias lower than a high frequency frequency for plasma generation to an electrode on the side where a substrate is mounted during plasma generation; One side is connected to the anode electrode and the other end is An impedance adjusting unit connected to the processing vessel and controlling an impedance value from the cathode electrode to the ground housing of the matching circuit via the plasma, the anode electrode and the wall of the processing vessel, and a voltage measurement for measuring the voltage of the impedance adjusting unit; Interposed between the impedance adjusting unit and the voltage measuring unit. When the frequency of the high frequency for plasma generation is f1 and the frequency of the high frequency for bias is f2 at the voltage of the impedance adjusting unit, f1 is a pass band, and f1 a bandpass filter having -f2 and f1 + f2 as the attenuation bands, and a voltage value measured by the voltage measuring unit while varying the impedance value of the impedance adjusting unit at the time of plasma generation, and based on the voltage value, The value of the current flowing into the anode electrode is calculated so that the value of this current is at or near the maximum value. As such is characterized in that it includes a control unit for setting an impedance value of the impedance adjusting section.

For example, the impedance adjusting unit includes a variable capacitance capacitor, and a driving mechanism for driving a trimmer mechanism for adjusting the capacitance of the variable capacitance capacitor is provided, and the control unit sets the capacitance value of the variable capacitance capacitor via the driving mechanism. The impedance adjusting unit may set an impedance value of the impedance adjusting unit, and the control unit may constitute an impedance adjusting unit other than the voltage value measured by the voltage measuring unit, the capacitance value of the variable capacitance capacitor, and the capacitance variable capacitor. The value of the current flowing into the anode current may be calculated based on the impedance value of the element and the insulation capacitance value of the insulator insulating the anode electrode from the processing vessel.

The control unit controls the drive mechanism such that, for example, the capacitance value of the variable capacitance capacitor is sequentially increased, and stops the drive mechanism when the current value flowing into the anode electrode starts to decrease, thereby causing the capacitance value of the variable capacitor. Set. The impedance adjusting unit may include a series circuit between a first element unit including the capacitive variable capacitor and a second element unit including a capacitor or an inductor, and the voltage measuring unit includes a voltage at both ends of the first element unit, or a second circuit. The voltage at both ends of the element portion may be measured, and a plurality of impedance adjusting portions are provided in the plane direction of the anode electrode, and the control portion sets capacitance values for the capacitance variable capacitor of one impedance adjusting portion, or two or more. The capacitance value may be set simultaneously for the capacitance variable capacitor of the impedance adjusting unit. Further, for example, a storage unit for storing the processing conditions when performing plasma processing and the trimmer position of the capacitive variable capacitor determined in the processing conditions is provided, and the control unit positions the trimmer position corresponding to the processing conditions when performing plasma processing on the substrate. May be read from the storage to control the drive mechanism.

The plasma processing method of the present invention is provided so as to face the cathode and the cathode which are insulated from the processing container and connected to a high frequency power source for outputting high frequency for plasma generation via a matching circuit, An anode insulated from the processing container via an insulator; one end thereof is connected to the anode electrode, and the other end thereof is connected to the processing container; and from the cathode electrode through the plasma, the anode electrode, and the wall of the processing container, Using a plasma processing apparatus equipped with an impedance adjusting unit for controlling the impedance value up to the ground housing of the matching circuit, plasma treatment of the processing gas by high-frequency power in the processing vessel, and the cathode and the anode by the plasma To process the substrate mounted on one side of the electrode In the plasma processing method, a step of generating a plasma by applying a high frequency for plasma generation between the cathode electrode and the anode electrode, and at this step, lower than the frequency of the high frequency for plasma generation to the electrode on which the substrate is mounted If the step of applying a high frequency for bias, the frequency of the high frequency for plasma generation f1 and the frequency of the high frequency for bias is f2, the impedance adjusting unit and the voltage measuring unit for measuring the voltage of the impedance adjusting unit A step of passing a voltage of f1 among the voltages of the impedance adjusting unit by a band pass filter interposed therebetween to suppress the voltage of the frequency component of f1-f2 or less and the voltage of the high frequency component of f1 + f2 or more, Side by the voltage measuring section while changing the impedance value of the impedance adjusting section by A step of taking in the calculated voltage value, a step of calculating the value of the current flowing into the anode electrode based on the voltage value taken in this step, and a value of the current calculated in this step is the maximum value or the vicinity thereof. And setting the impedance value of the impedance adjusting unit to be a value.

The impedance adjusting unit includes a capacitive variable capacitor whose capacitance is adjusted via a driving mechanism, and includes a step of controlling the driving mechanism so that the capacitance value of the capacitive variable capacitor is sequentially increased. The setting of the capacitance value may be performed by stopping the drive mechanism when the current value flowing into the anode electrode begins to decrease, and the step of calculating the value of the current flowing into the anode electrode may include: Based on the measured voltage value, the capacitance value of the capacitive variable capacitor, the impedance value of the elements constituting the impedance adjusting unit other than the capacitive variable capacitor, and the insulation capacitance value of the insulator insulating the anode electrode from the processing container. May be performed.

In addition, the storage medium of the present invention is used in a plasma processing apparatus that performs a plasma processing on a substrate, and is a storage medium storing a computer program running on a computer, wherein the computer program is configured to perform the above-described plasma processing method. The group is organized.

According to the plasma processing apparatus of the present invention, the voltage of the impedance adjusting unit is measured through a bandpass filter while changing the impedance value of the impedance adjusting unit by the control unit, the measured voltage is taken in, and the impedance adjusting unit sets an appropriate impedance value. Therefore, an appropriate point of the impedance value can be obtained automatically, and appropriate impedance adjustment can be performed without being influenced by the high frequency bias applied to the substrate side, so that good plasma processing can be realized.

Further, for example, the impedance adjusting unit is constituted by a series circuit of a first element portion including the capacitive variable capacitor and a second element portion formed of a capacitor or an inductor, and the impedance is measured by measuring the voltage of one of these element portions. Compared with the case of measuring the voltage of the entire parallel circuit of the adjusting unit and the insulator, since the voltage can be largely prevented from being affected by the parallel resonance, more appropriate impedance adjustment can be performed.

EMBODIMENT OF THE INVENTION The Example which applied the plasma processing apparatus of this invention to the apparatus which etches the glass substrate 10 for liquid crystal monitors is demonstrated, referring FIG. This plasma etching apparatus 2 is provided with the processing chamber 20 of the square cylinder shape which consists of aluminum whose surface was anodized, for example. The lower electrode 31 is provided in the center lower part of this processing container 20, and the lower electrode 31 mounts the mounting table which mounts the board | substrate 10 conveyed in the processing container 20 by the conveying means which is not shown in figure. It is also used. The insulator 32 is provided in the lower part of the lower electrode 31 along the periphery of the opening of the matching box mentioned later. By this insulator 32, the lower electrode 3l is fully electrically floating from the processing container 20. The lower part of the insulator 32 is provided with the matching box 34 which penetrates the opening part 21 formed in the bottom wall of the processing container 20 via the support part 33, and extends downward.

Upper and lower portions of the matching box 34 are open, and a matching circuit 35 is provided therein. One end of the conductive path 36 is connected to the lower electrode 31, and the other end of the conductive path 36 is branched, one of which is provided outside the matching box 34 via a matching circuit 35. It is connected to a 13.56 MHz high frequency power supply 37 for plasma formation, and the other is connected to a 3.2 MHz high frequency power supply 39 for bias application provided outside the matching box 34 via a matching circuit 38. Connected. In addition, the lower portion of the matching box 34 extends as the outer layer portions 3B and 3B constituting the coaxial cables 3A and 3A together with the branched conductive path 36, and each outer layer portion 3B is grounded. have. In this way, the matching box 34 is configured as a ground housing of the matching circuits 35 and 38.

In addition, an exhaust passage 22 is connected to the side wall of the processing container 20, and a vacuum exhaust means 23 is connected to the exhaust passage 22. Moreover, the gate valve 25 for opening / closing the conveyance port 24 of the board | substrate 10 is provided in the side wall of the processing container 20.

The upper electrode 41 which serves as the gas shower head which is a gas supply part is provided above the lower electrode 31 so that the said lower electrode 31 may be provided. In this plasma etching apparatus 2, the lower electrode 31, The upper electrode 41 corresponds to a cathode electrode and an anode electrode, respectively. Moreover, the upper electrode 41 is connected to the ceiling part of the processing container 20 via the insulator 42 provided along the opening periphery of the opening 26 provided in the upper side of the processing container 20, and this insulator 42 ), The upper electrode 41 is in a sufficiently electrically floating state from the processing container 20. The process gas supply part 44 is connected to the process gas supply part 44 via the gas supply path 43, and it is comprised so that the process gas supplied from the gas supply path 43 may be supplied into the process container 20 from many gas holes 45. As shown in FIG.

On the processing container 20, the cover member 46 with the upper side closed is provided so that the opening part 26 may be covered, and the upper electrode 41 and the cover member 46 have one end and the other end of the conductive path 51, respectively. Connected. In the conductive path 51, an impedance adjusting unit 5 constituted by a capacitor variable capacitor 53 which is a first element part connected in series with each other and an inductor 52 which is a second element part is provided therebetween, and the capacitor variable capacitor ( 53 is provided on the cover member 46 side, and the inductor 52 is provided on the upper electrode 41 side, respectively. The variable capacitance capacitor 53 includes a trimmer mechanism, and the capacitance thereof is changed by adjusting the trimmer position. The conductive path 54, the band pass filter 56, and the voltage measuring part 57 are connected between the connection point of the capacitor | capacitance variable capacitor 53, the inductor 52, and ground.

Here, since the high frequency of 3.2 MHz for the 13.56 MHz bias for plasma generation flows into the said impedance adjusting part 5, the frequency of the capacitor | condenser variable capacitor 53 (potential of the said connection point), in addition to the voltage of 13.56 MHz, both frequencies. The voltage of 10.36 (13.56-3.2) MHz, which is the difference between the voltage of 16.76 (13.56 + 3.2) MHz and the frequency of both, is shown. For this reason, as shown in FIG. 2, the bandpass filter 56 sets 13.53 MHz as a pass band, and sets 16.76 MHz or more and 10.36 MHz or less as an attenuation band. That is, the structure has a large Q value of 13.56 MHz.

The voltage measuring unit 57 is configured to measure the voltage of the variable capacitance capacitor 53 and output the voltage measured value to the control unit 6 described later. In addition, the trimmer mechanism of the capacitive variable capacitor 53 is driven by the motor 58 which is a drive mechanism, and the trimmer position of the capacitive variable capacitor 53 is controlled by the controller 6 driving control of the motor 58. It is operated, and the capacitance is adjusted.

3 schematically shows the plasma etching apparatus 2, which will be described with reference to this figure. 3, the high frequency power supply 39 for bias is not shown in figure for convenience. When the high frequency power supply 37 is turned on, a high frequency current flows through the path from the high frequency power supply 37 to the matching circuit 35 to the lower electrode 31 to the plasma to the upper electrode 41. The high frequency current flowing through the upper electrode 41 mainly flows through the path of the impedance adjusting unit 5 to the processing container 20, but part of the high frequency current flows through the path of the insulator 42 to the processing container 20. The high frequency current flowing through the processing container 20 flows through the path of the matching box 34 which is a ground housing → the outer layer 3B → ground of the coaxial cable 3A, but as described in the column of the background art. Similarly, since there is a possibility that a high frequency current may flow from the lower electrode 31 to the wall of the processing container 20 through the plasma and in an abnormal path, the path from the upper electrode 41 to the upper part of the processing container 20. The impedance value of the (return path) is adjusted by the impedance adjusting unit 5.

In FIG. 3, the capacitance indicated by [Co] corresponds to the insulation capacity of the insulator 42 interposed between the processing container 20 and the upper electrode 41. In the figure, [ICo] is the current flowing through the insulator 42, [Cs] is the capacitance of the capacitive variable capacitor 53, [ICs] is the current flowing through the impedance adjusting unit 5, and [VCs] is the voltage measuring unit. The voltage across the capacitor variable capacitor 53, [I-total], measured by 57, is the current flowing from the lower electrode 31 to the upper electrode 41, and [Ls] is the inductance of the inductor 52, respectively. It is shown.

When the current [I-total] flowing in the upper electrode 41 becomes maximum, the high frequency flowing through the path of the lower electrode 31 → plasma → processing vessel 20 described above is the least, and therefore, in the processing described later, By changing the position of the capacitive variable capacitor 53 and changing its capacitance Cs, the impedance value of the impedance adjusting unit 5 is changed, so that the position of the capacitive variable capacitor 53 in which [I-total] becomes maximum in this way. Determine.

Next, the structure of the control part 6 is demonstrated, referring FIG. The control part 6 is comprised by the computer, for example, and is provided with the input screen (not shown). This input screen is configured to arbitrarily input and set processing conditions such as gas species, pressure in the processing vessel 20, and power of the high frequency power supply 37, and is also a trimmer of the capacitive variable capacitor 53 of the impedance adjusting unit 5. It is comprised so that the impedance setting mode which determines a position, or the substrate processing mode which performs a plasma etching process to a board | substrate can be selected. 61 is a bus. In addition, the bus 61 includes a program 63 stored in the program storage 62 and a work memory 64 which calculates a current [I-total] flowing through the upper electrode 41 and a program 63 for executing the operation described later. Connected. The bus 61 also has a table 65 in which the trimmer position of the capacitive variable capacitor 53 corresponds to the capacitance [Cs], and the current [I-total] and the trimmer position of the capacitive variable capacitor 53. A memory for storing the data 66 obtained from the relationship and the table 67 in which the processing conditions are related to the optimum trimmer position is connected. However, in FIG. 4, the table 65, the data 66, and the table 67 are connected. It is shown.

In the program 63, a step group is formed so that the trimmer position of the capacitive variable capacitor 53 at which [I-total] is at or near the maximum value can be determined by executing the process described later. 63 is installed in the control unit 6 from a storage medium constituted by, for example, a flexible disc, a compact disc, a magneto-optical disc, or the like, and is stored in the program storage unit 62.

Various operations are performed in the work memory 64, and the values of [Co] and [Ls] are stored in advance, and these values and the values of [VCs] output from the voltage measuring unit 57, and The value of [I-total] is calculated from the value of [Cs] corresponding to the trimmer position of the capacitive variable capacitor 53 when [VCs] is obtained.

In the table 65, predetermined predetermined positions of the trimmer of the capacitive variable capacitor 53 and values of the capacitance [Cs] of the capacitive variable capacitor 53 at the respective positions are stored. In addition, the trimmer position is, for example, the number of pulses of the encoder connected to the motor 58 in detail. The data 66 is data indicating a relationship between the trimmer positions of the capacitive variable capacitors 53 and [I-total] calculated at the trimmer positions of the capacitive variable capacitors 53, which will be described later. When [I-total] is calculated at each trimmer position of the capacitor 53, the result of the calculation is stored in correspondence with the trimmer position. This data is grasped | ascertained substantially as the graph shown in FIG. The data 66 and the tables 65 and 67 are displayed on the input screen, for example. In the table 67, the optimum processing position of the trimmer of the capacitive variable capacitor 53, in which the set processing condition and [I-total] calculated under the processing condition is maximized, is written and stored.

The procedure for obtaining the optimum position of the trimmer of the capacitive variable capacitor 53 is described below with reference to the flow shown in FIG. 5.

(Step S1)

When the operator inputs processing conditions such as gas species, pressure in the processing vessel 20, and power of the high frequency power supply 37 from the input screen, the control unit 6 enters the capacitance [Cs] from the table 65, for example. The trimmer position of the capacitive variable capacitor 53 is minimized, and is adjusted to the position where [Cs] of the capacitive variable capacitor 53 is minimized via the motor 58.

(Step S2)

Subsequently, the set gas is supplied from the upper electrode 41 into the processing container 20, and the inside of the processing container 20 is vacuum sucked to become the set pressure. Thereafter, the high frequency power supply 37 is turned on, the high frequency of the set electric power is supplied to the lower electrode 31, and a plasma is formed between the lower electrode 31 and the upper electrode 41, so that the high frequency current As described above, it flows through the impedance adjusting unit 5 to the processing vessel 20.

(Step S3)

The voltage measuring unit 57 measures the voltage [VCs] of the current flowing through the capacitive variable capacitor 53, and the control unit 6 writes the voltage measuring value [VCs] into the work memory 64 and the table. The value of [Cs] is read from 65, and the value [ICs] of the current flowing through the impedance adjusting unit 5 is calculated based on these [VCs] and [Cs].

(Step S4)

Then, the control part 6 calculates the value of the electric potential [VCo] of the upper electrode 41 with which the impedance adjustment part 5 was connected from the computed [ICs], and this insulator 42 previously inputted with this [VCo]. The value of the current [ICo] flowing through the insulator 42 is calculated from the value of the insulation capacity [Co] of the ().

(Step S5)

The control unit 6 also calculates the value of [I-total] by calculating [ICs] + [IC0], and stores the corresponding [I-total] and the trimmer position in correspondence. This process corresponds to plotting on the graph shown as data 66.

(Step S6)

After the end of the plot, the control section 6 reads the trimmer position corresponding to the value of [Cs] one step larger than the current [Cs] from the table 65 and in this step the value of [Cs] the second largest. The capacitor variable capacitor 53 is set at the position. Thereafter, steps S3 to S6 are performed. In practice, since the approximate appropriate value of [Cs] can be grasped in advance by experience or the like, it may be started from the trimmer position corresponding to [Cs] which is larger than the minimum value of [Cs].

(Step S7)

Steps S3 to S7 are repeated, [I-total] is sequentially measured with respect to the trimmer position of the capacitive variable capacitor 53 set in the table 65, and a graph which is the relationship data of both is drawn. When the newly calculated value of [I-total] becomes lower than the value of [I-total] calculated at the previous timing, the operation of changing the trimmer position is stopped at that point, and the trimmer position at that point is optimized. As the position, the optimum position and the processing condition entered first are stored in the table 67, and the contents thereof are displayed on the input screen, for example.

When the operator inputs a processing condition different from the processing condition input by the operator on the input screen, the steps S1 to S7 are similarly performed, and the table 67 shows the processing variable and the capacitance variable capacitor corresponding to the processing condition. 53) is optimally stored.

Next, the procedure of performing a plasma etching process on the board | substrate 10 is demonstrated. When the operator selects the substrate processing mode from the input screen and sets the processing conditions, the controller 6 reads the optimum position of the trimmer of the capacitor variable capacitor 53 corresponding to the processing conditions from the table 67 and The variable capacitor 53 is set to its optimum position.

Subsequently, the substrate 10 is loaded into the processing container 20, mounted on the lower electrode 31, and the inside of the processing container is vacuum- suctioned to a predetermined pressure so as to correspond to the set processing conditions, and the processing is performed from the upper electrode 41. Gas is supplied into the vessel 20. Thereafter, the high frequency power supplies 37 and 39 are turned on, and a high frequency is introduced into the processing vessel 20 from the high frequency power supply 37 at the set power value, so that a plasma is generated between the lower electrode 31 and the upper electrode 41. In addition, a bias is applied to the substrate 10 to etch the substrate 10. For example, after a predetermined time elapses after the plasma is formed, the high frequency power supplies 37 and 39 are turned off, the gas supply to the processing vessel 20 is stopped, the etching process is completed, and the predetermined pressure in the processing vessel 20 is terminated. Becomes

According to the plasma etching apparatus 2, the variable capacitance capacitor 53 is changed while changing the trimmer position of the variable capacitance capacitor 53 included in the impedance adjusting unit 5 provided between the upper electrode 41 and the processing container 20. Voltage is measured via the bandpass filter 56, and an appropriate trimmer position of the capacitive variable capacitor 53 is set based on the measured voltage, so that an appropriate point of the impedance value can be automatically obtained. In addition, it is possible to adjust the impedance appropriately without being influenced by the high frequency wave for bias, to suppress the time required for the impedance adjustment, and to realize good plasma processing.

In addition, the impedance adjusting unit 5 is constituted by a series circuit composed of the variable capacitance capacitor 53 and the inductor 52, and the impedance adjusting unit 5 and the insulator ( Compared with the case of measuring the voltage of the entire parallel circuit of 42), since the large fluctuation of the voltage due to the parallel resonance or the impedance value of the parallel circuit becomes zero is avoided, more appropriate impedance adjustment can be performed.

In the region where the current [I-total] flowing through the upper electrode 41 decreases beyond the maximum value, abnormal discharge is likely to occur. However, in the above-described embodiment, when the current [I-total] decreases, Since the change of the electrostatic capacity is stopped, damage to the inner wall and internal parts of the processing container 20 due to abnormal discharge can be prevented.

In addition, the processing conditions and the trimmer positions of the capacitive variable capacitors corresponding to the processing conditions are stored in the table 67 of the control unit 6, and the trimmer positions are automatically read and stored at the positions during the plasma processing of the substrate. Since the capacitive variable capacitor 53 is set and the processing is performed, the operator's time can be omitted.

FIG. 6 shows an impedance adjusting section 8 which is a modification of the impedance adjusting section 5. In this impedance adjusting section 8, the inductor 52 and the capacitor variable capacitor 53 are provided oppositely. The voltage measuring unit 57 measures the voltage [VCc] of the inductor 52, and [I-total] is calculated by using [VCc] instead of [VCs] in the calculation. Here, the inductor 52 corresponds to the second element portion described in the claims, but even when the inductor part is not provided, the impedance adjusting unit 5 is provided in the processing container via the connecting copper plate. This connecting copper plate corresponds to the second element portion forming the inductor.

In addition, a plurality of impedance adjusting units 5 may be provided. In this case, the capacitance [Cs] of the capacitive variable capacitor 53 of each impedance adjusting unit 5 is operated to be the same value at the same time, while the voltage of one of the variable capacitors is changed to the same as in the previous embodiment. Similarly, the optimum trimmer position may be obtained based on the measured value. Alternatively, only [Cs] of one variable capacitance capacitor 53 is adjusted, and other [Cs] is fixed, and the optimum trimmer position is similarly set based on the voltage of the one variable capacitance capacitor 53. You may do so.

In addition, each of the high frequency power sources 37 and 39 and the impedance adjusting unit 5 may be provided upside down, that is, the impedance adjusting unit 5 is provided between the processing vessel 20 and the lower electrode 31, and the upper electrode 41 is provided. ) May be connected to the high frequency power supplies 37 and 39.

(Evaluation test 1-1)

As the evaluation test 1-1, first, the relationship between [I-total] and the trimmer position of the capacitive variable capacitor 53 is investigated using the above-described plasma etching apparatus 2, and the trimmer of the capacitive variable capacitor 53 is examined. The optimal position of was detected. Cl ₂ / SF ₆ was used as the processing gas supplied from the upper electrode 41 into the processing vessel 20. However, the bandpass filter 56 is not provided in the plasma etching apparatus 2 used in this evaluation test 1, and the high frequency for bias from the high frequency power supply 39 is not applied. 7A shows the impedance value of the impedance adjustment part 5 in each position at the time of changing the trimmer position of the capacitive variable capacitor 53 measured beforehand.

(Evaluation examination 1-2)

In addition, in the conventional method using the plasma etching apparatus 1 and the probe 18a, the oscilloscope 18b, and the computer 18 shown in the column of the background art as evaluation test 1-2, [I-total] and a capacitive variable capacitor The relationship with the trimmer position was examined and the state of the formed plasma was visually confirmed. Each processing condition is set similarly to the evaluation test 1-1, and the high frequency for bias is not applied also in this evaluation test 1-2.

The graph of Fig. 7 (b) shows the results of the evaluation test 1-1, and the graph of Fig. 7 (c) shows the results of the evaluation test 1-2, and Table 1 below shows the doses in the evaluation test 1-2. The relationship between each position of the variable capacitor and the state of the plasma confirmed by the eye is shown. It can be seen from the graph of FIG. 7B that the most [I-total] becomes higher when the trimmer position of the capacitive variable capacitor 53 is around 70% in the plasma etching apparatus 2. In addition, from the graph of Fig. 7 (c), it can be seen that even in the conventional method, [I-total] is higher when the trimmer position is around 70%, and as shown in Table 1, the plasma state is 70%. It was the best time. From this, in the plasma etching apparatus 2, it was confirmed that the optimum position of the trimmer of the capacitive variable capacitor 53 is properly detected, and according to the present invention, it is possible to optimally set the impedance value of the impedance adjusting unit 5. Supported.

(Evaluation test 2-1)

Subsequently, except for changing the gas supplied into the processing container 20 from Cl ₂ / SF ₆ to O ₂ gas, each trimmer of the capacitive variable capacitor 53 using the plasma etching apparatus 2 in the same manner as in the evaluation test 1-1. [I-total] at the position was measured. In addition, the impedance value of the impedance adjustment part 5 in each position is the same as that of the evaluation test 1-1.

(Evaluation test 2-2)

In addition, as the evaluation test 2-2, the relationship between [I-total] and the trimmer position of the capacitive variable capacitor was examined in the same manner as in the evaluation test 1-2, and the state of the formed plasma was visually confirmed. Each processing condition was set like the evaluation test 2-1.

The graph of FIG. 8 (a) shows the result of the evaluation test 2-1, and the graph of FIG. 8 (b) shows the result of the evaluation test 2-2, respectively, and Table 2 below shows the evaluation test 2-2. The relationship between each position of the capacitive variable capacitor 53 and the state of the plasma confirmed by the eye is shown. From the graph of Fig. 8A, peaks were observed when the trimmer positions were 0% and 90%. Also, from the graph of Fig. 8 (b), it can be seen that in the conventional method, [I-total] is highest when the trimmer position is around 90%, and as shown in Table 2, the plasma state is 90%. Best at that time. The peak was observed even when the trimmer position was 0% in the graph of Fig. 8A because not only the component of 13.56 MHz of the high frequency for plasma formation but also the voltage of the frequency component of 27.12 MHz, which is its high frequency, were measured. . Therefore, it can be seen from this experiment that the bandpass filter and the effect of eliminating harmonics and the like as described in the above-described embodiments are effective in preventing false detection of the peak of [I-total].

(Evaluation examination 3)

As the evaluation test 3, [I-total] when the trimmer position of the capacitive variable capacitor was changed in the same procedure as in the evaluation test 1-1 using the plasma etching apparatus 2. In this evaluation test 3, a high frequency wave for bias is applied, but the band pass filter 56 is not provided in the same manner as in the evaluation test 1-1. As the gas, Cl ₂ / SF ₆ gas is used, and the impedance value of the impedance adjusting unit 5 at each trimmer position is the same as in the evaluation test 1-1. The conventional measurement method described above also measured [I-total] at each trimmer position and confirmed the state of the plasma by the eye. Also in this conventional measuring method, the high frequency for bias was applied.

The graph of FIG. 9 shows the result of the evaluation test 3, As shown in this graph, two or more peaks of [I-total] appear. The peak of [I-total] by the conventional measuring method appears when the trimmer position is 70%, and the state of plasma by the eyes is also the best at this position. Therefore, it can be seen that when the high frequency is superimposed, the peak of [I-total] is misdetected.

(Evaluation examination 4)

In the plasma etching apparatus 2 as the evaluation test 4, the voltage of each frequency component at the time of changing the trimmer position of a capacitance variable capacitor was investigated. Also in this evaluation test 4, although the high frequency wave for bias was applied to the lower electrode 31, the bandpass filter 73 is not provided in the etching apparatus 2. As shown in FIG. 10 (a) to 10 (c) are graphs showing the results at this time. According to this graph, when the high frequency applied to the lower electrode 31 is superposed, depending on the trimmer position of the variable capacitor 53, not only the 13.56 MHz component of the high frequency for plasma formation but also 13.56 + 3.2 = 16.76 MHz or 13.56 The voltage of the MHz + 2 x 3.2 = 19.96 MHz component is increased. Then, the output value of the voltage measuring section becomes unstable, so that accurate [I-total] cannot be calculated, and there is a possibility that the trimmer position at which this [I-total] is at or near the maximum may not be detected. From the results of the evaluation test 3 and the evaluation test 4, it turns out that it is effective to provide a bandpass filter as shown in the Example mentioned above.

1 is a longitudinal side view of a plasma etching apparatus of an embodiment of the present invention;

2 is a graph showing band characteristics of a band pass filter provided in the etching apparatus;

3 is a schematic diagram showing a state in which discharge is performed in the plasma etching apparatus;

4 is a configuration diagram showing a control unit provided in the plasma etching apparatus;

5 is a flowchart illustrating a process of determining an optimum position of a trimmer of a capacitive variable capacitor in the plasma etching apparatus;

6 is a configuration diagram showing another impedance adjusting unit provided in the plasma etching apparatus;

7 is a graph showing the results of an evaluation test;

8 is a graph showing the results of an evaluation test;

9 is a graph showing the results of an evaluation test;

10 is a graph showing the results of an evaluation test;

11 is a view showing an equivalent circuit of a conventional plasma etching apparatus,

12 is a vertical side view showing the structure of a conventional plasma etching apparatus;

Fig. 13 is a schematic diagram showing how to set impedance using the plasma etching apparatus.

Explanation of symbols for the main parts of the drawings

2: plasma etching apparatus 20: processing container

31: lower electrode 35, 38: matching circuit

37, 39: high frequency power supply 41: upper electrode

5: impedance adjusting unit 53: capacitor variable capacitor

56 bandpass filter 57 voltage measurement unit

6: control unit 63: program

Claims (11)

The cathode is insulated from the processing container, and is provided to face a cathode electrode connected to a high frequency power source for outputting a high frequency for plasma generation through a matching circuit, the cathode electrode, and the processing container via an insulator. A parallel flat plate having an insulated anode electrode and having a substrate mounted on one of the cathode electrode and the anode electrode, plasma treatment of the processing gas by high frequency power, and plasma treatment of the substrate by the plasma. In the plasma processing apparatus of A high frequency power supply for bias for applying a high frequency wave for bias lower than a high frequency frequency for plasma generation to an electrode on the side where the substrate is mounted when the plasma is generated; One end thereof is connected to the anode electrode, and the other end side thereof is connected to the processing container, and from the cathode electrode, the plasma, the anode electrode, and the wall of the processing container are connected to each other. An impedance adjusting unit for controlling the impedance value up to the ground housing; A voltage measuring unit measuring a voltage of the impedance adjusting unit; It is interposed between the impedance adjusting unit and the voltage measuring unit, and when the frequency of the high frequency for plasma generation is f1 and the frequency of the high frequency for bias is f2 at the voltage of the impedance adjusting unit, f1 is set as a pass band. a bandpass filter having f1-f2 and f1 + f2 as attenuation bands, Taking the voltage value measured by the voltage measuring unit while changing the impedance value of the impedance adjusting unit at the time of plasma generation, and calculating the value of the current flowing into the anode electrode based on this voltage value, A control unit that sets an impedance value of the impedance adjusting unit such that the value is at or near the maximum value Plasma processing apparatus comprising the. The method of claim 1, The impedance adjusting unit includes a capacitive variable capacitor, A drive mechanism for driving a trimmer mechanism for adjusting the capacitance of the capacitive variable capacitor is provided, The control unit sets the capacitance value of the variable capacitance capacitor via the drive mechanism to set the impedance value of the impedance adjustment unit. Plasma processing apparatus, characterized in that. The method of claim 2, The controller controls the voltage value measured by the voltage measuring unit, the capacitance value of the variable capacitance capacitor, the impedance value of an element constituting the impedance adjusting unit other than the variable capacitance capacitor, and the anode electrode. And calculating the value of the current flowing into the anode current based on the insulation capacitance value of the insulator insulated from the container. The method of claim 2 or 3, The control unit controls the driving mechanism so that the capacitance value of the variable capacitance capacitor sequentially increases, and sets the capacitance value of the variable capacitance capacitor by stopping the driving mechanism when the current value flowing into the anode electrode begins to decrease. Plasma processing apparatus, characterized in that. The method according to any one of claims 1 to 3, The impedance adjusting unit is composed of a series circuit between a first element unit including the capacitive variable capacitor and a second element unit including a capacitor or an inductor. The voltage measuring unit measures the voltage across the first device portion or the voltage across the second device portion. Plasma processing apparatus, characterized in that. The method according to any one of claims 1 to 3, The impedance adjusting unit is provided in plural in the surface direction of the anode electrode, The control unit sets the capacitance value for the capacitance variable capacitor of one impedance adjusting unit, or simultaneously sets the capacitance value for the capacitance variable capacitor of two or more impedance adjusting units. Plasma processing apparatus, characterized in that. The method of claim 2 or 3, A storage section is provided for storing the processing conditions at the time of performing the plasma processing and the trimmer position of the capacitive variable capacitor determined at the processing conditions, and the controller controls the trimmer position corresponding to the processing conditions when the plasma processing is performed on the substrate. A plasma processing apparatus characterized by reading from a storage unit and controlling the drive mechanism. The cathode is insulated from the processing container, and is provided to face a cathode electrode connected to a high frequency power source for outputting a high frequency for plasma generation through a matching circuit, the cathode electrode, and the processing container via an insulator. An insulated anode electrode, one end of which is connected to the anode electrode and the other end of which is connected to the processing container, and a ground housing of the matching circuit via the plasma, the anode electrode and the wall of the processing container from the cathode electrode; Plasma processing gas by high frequency power in the processing vessel using a plasma processing apparatus having an impedance adjusting unit for controlling an impedance value up to, wherein the plasma of the cathode electrode and the anode electrode is For processing the substrate mounted on one side In the town Raj processing method, Generating a plasma by applying a high frequency for plasma generation between the cathode electrode and the anode electrode; In the process, applying a high frequency wave for bias lower than a high frequency frequency for plasma generation to an electrode on which the substrate is mounted; If the frequency of the high frequency for plasma generation is f1 and the frequency of the bias high frequency is f2, the bandpass filter is interposed between the impedance adjusting unit and a voltage measuring unit for measuring the voltage of the impedance adjusting unit. Passing the voltage of f1 among the voltages of the impedance adjusting unit and suppressing the voltage of the frequency component of f1-f2 or less and the voltage of the frequency component of f1 + f2 or more; A step of taking in the voltage value measured by the voltage measuring unit while changing the impedance value of the impedance adjusting unit by the control unit when the plasma is generated; Calculating a value of a current flowing into the anode electrode based on the voltage value taken in the step; Setting an impedance value of the impedance adjusting unit so that the value of the current calculated in the step becomes a maximum value or a value thereof Plasma processing method comprising a. The method of claim 8, The impedance adjusting unit includes a capacitive variable capacitor whose capacitance is adjusted via a driving mechanism, And controlling the drive mechanism such that the capacitance value of the variable capacitance capacitor is sequentially increased. Setting of the capacitance value of the variable capacitance capacitor is performed by stopping the drive mechanism when the current value flowing into the anode electrode begins to decrease. Plasma processing method characterized in that. The method of claim 9, The step of calculating the value of the current flowing into the anode electrode includes a voltage value measured by the voltage measuring unit, an electrostatic capacitance value of the variable capacitance capacitor, and an impedance adjusting unit other than the variable capacitance capacitor. And an impedance value and an insulating capacitance value of an insulator that insulates the anode electrode from the processing container. A storage medium used for a plasma processing apparatus for performing plasma processing on a substrate and storing a computer program operating on a computer, The said computer program is a storage medium characterized by the step group formed so that the plasma processing method of any one of Claims 8-10 may be implemented.

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